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AU14 - Ortho Exam1 > au14_-_orthodontics_exam_1_20141210195046 > Flashcards

au14_-_orthodontics_exam_1_20141210195046 Flashcards

1
Q

What is the difference between growth and development?

A
  • GROWTH: an anatomical phenomenon which involves an increase in size or number- DEVELOPMENT: a physiological phenomenon which involves an increase in organization, complexity, or specialization at the expense of a loss in potential
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2
Q

Does the mandible grow outward from a fixed point (i.e. condyle)? Does the mandible grow outward from a central point?

A

NO and NO!

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3
Q

The mandible does not merely ___. It also ___ by changing its position and shape via translation and remodeling. This results in ___.

A
  • grow- develops- higher specialization for the functions of mastication and speech
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4
Q

What are the 3 concepts of growth?

A
  • normal growth follows a PATTERN- there is VARIABILITY among individuals- differences in TIMING may result in inter-individual differences
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5
Q

What is the definition of normal growth pattern? Which has a larger growth: the head or the lower limb? The forehead/cranium or the jaw?

A
  • changes in body proportions over time through differential tissue growth- lower limb- jaw*growth gradient seems to usually go from low to high as you travel down the body toward the feet
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6
Q

True or false: The constancy of the growth pattern gives predictability.

A

true

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7
Q

Which has an earlier development: maxilla or mandible? Which is more similar to neural growth and which is more similar to general growth?

A
  • maxilla- maxilla- mandible
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8
Q

True or false: Deviations from the usual pattern of growth can only be expressed qualitatively.

A

FALSE. Deviations from the usual pattern can be expressed quantitatively.

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9
Q

True or false: A patient who falls into the 10th percentile for height and remains in the 10th percentile is less likely to be diseased than a patient who begins in the 50th percentile and then goes into the 20th percentile.

A

true

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10
Q

True or false: Variations in growth due to timing are more evident during childhood.

A

FALSE. They are more evident during ADOLESCENCE.

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11
Q

What are the different methods of measuring growth?

A
  • craniometry (measurement of the skull)- anthropometry (measurement and proportions of the human body)- cephalometric radiology- 3D imaging (CAT-scans, cone beam CT, and MRI)
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12
Q

What is interstitial growth? What are some examples?

A
  • growth that occurs by a combination of hyperplasia, hypertrophy, and secretion of extracellular matrix; occurs at ALL points within the tissue- ex: all soft tissues; cartilage; cranial base
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13
Q

What is the difference between hyperplasia and hypertrophy?

A
  • HYPERPLASIA: proliferating cells (cell division)- HYPERTROPHY: increase in cell size
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14
Q

If the extracellular matrix is NOT mineralized, ___ growth may continue in soft tissues and cartilages.

A

interstitial

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15
Q

What is appositional growth? What cells are responsible? What are some examples?

A
  • growth that occurs by a combination of hyperplasia, hypertrophy, and secretion of extracellular matrix; occurs only at SURFACE of bones; addition of new bone to the surface of existing bones- occurs through the activity of cells in the periosteum- ex: bony surfaces of cranial vault; bony surfaces of maxilla and mandible
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16
Q

True or false: Interstitial growth can occur within bone.

A

FALSE. It CANNOT occur within bone.

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17
Q

Once the cartilage is transformed into bone, it continues to grow only by ___.

A

apposition

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18
Q

What is endochondral growth? What are some examples?

A
  • bone growth within cartilage; ossification centers occur within the cartilage and cartilage is transformed into bone- ex: chondrocranium (ethmoid, sphenoid, and basiocciptial); ephiphyseal plate cartilage of long bones
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19
Q

What is intramembranous growth? What are some examples?

A
  • secretion of bone matrix within and between connective tissue membranes; NO intermediate formation of cartilage; it does NOT replace cartilage- ex: desmocranium (cranial vault); maxilla and mandible
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20
Q

Describe the development of the condylar cartilage of the mandible?

A
  • it does NOT arise from Meckel’s cartilage- it develops from an independent secondary cartilage- fuses with the mandibular ramus
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21
Q

What is surface remodeling? What are some examples?

A
  • change in the shape of bones; result of bone removal (resorption) in one area and bone addition (apposition) in another; occurs at the surfaces of growing endochondral AND intramembranous bones- ex: bony surfaces of cranial vault; maxilla and mandible
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22
Q

What is internal remodeling?

A
  • vascular channels within bones bring osteocytes to the area- allows the bone to adapt to mechanical stress- allows for exchange of calcium and phosphate- internal remodeling does not make bone grow or change its shape
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23
Q

What are the 4 sites of growth in the craniofacial complex?

A
  • cranial vault- cranial base- nasomaxillary complex (maxilla)- mandible
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24
Q

The cranial vault contains ___ bones formed by ___ formation from ossification centers. Are there cartilaginous precursors? Where does bone remodeling take place?

A
  • flat bones- intramembranous formation- no cartilaginous precursors- bone remodeling both at sutures and inner/outer surfaces
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25
Q

How does the brain case primarily grow?

A

primarily by apposition of new bone at sutures, but also by remodeling of inner and outer surfaces of bones

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26
Q

The cranial base is formed by ___ ossification. Are there cartilaginous precursors? What are the names of the 3 resulting bones?

A
  • endochondral ossification- formed initially in cartilage and then transformed to bone- ethmoid, sphenoid, and basioccipital bones
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27
Q

What is the definition of the synchondroses of the cranial base? Are they movable? What are the 3 most important ones?

A
  • cartilaginous joints between the bones of the cranial base- immovable joints- spheno-ethmoidal, inter-sphenoidal, and spheno-occipital
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28
Q

What type of growth occurs within the synchondroses of the cranial base? What does this growth do?

A
  • endochondral growth- lengthens the area of the cranial base*bone surface remodeling also occurs in the cranial base
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29
Q

What is the difference between a synchondrosis and suture in terms of what it is a junction between? What type of tissue?

A
  • synchondrosis and sutures are both junctions between adjacent bones- synchondrosis is cartilage while suture is connective tissue
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30
Q

What is the difference between synchonrosis and suture in terms of ossification? Phase of growth?

A
  • synchondrosis has endochondral ossification; suture has direct ossification- synchondrosis has active growth (primary); suture has re-active growth (secondary)
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31
Q

What type of ossification is in the nasomaxillary complex? Is there a cartilage precursor? How does growth occur?

A
  • formed entirely by intramembranous ossification- no cartilaginous precursor- growth occurs by apposition and surface remodeling
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32
Q

When the maxilla is growing, which way does it translate? Where does the apposition of growth occur and what does this do?

A
  • translated downward and forward (away from cranial base)- occurs at circum-maxillary sutures which elongate the maxilla
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33
Q

During surface remodeling of the maxilla in the anterior/posterior direction, bone in the ___ surface of the maxilla is resorbed and apposition of bone occurs at the ___.

A
  • anterior- maxillary tuberosity
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34
Q

During surface remodeling of the maxilla in the up/down direction, bone is resorbed in ___ and apposition of the bone occurs ___. As a result, the palate moves ___.

A
  • the floor of the nose- at the palate and alveolar process- mostly downward and widens transversely
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35
Q

What types of growth are seen in the mandible?

A
  • endochondral growth occurs at the carilage that covers the mandibular cartilage- all other areas grow by surface apposition and remodeling
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36
Q

As the mandible is growing, the mandible is translated ___. Where are the principle sites of growth?

A
  • translated downward and forward (away from cranial base)- posterior surface of ramus and the condylar and coronoid processes
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37
Q

During surface remodeling, the body of the mandible grows ___, the ramus of the mandible grows ___, and there is more room in the body of the mandible for ___.

A
  • longer- higher- molars to erupt
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38
Q

What are the 4 theories that describe what controls the growth of the jaws?

A
  • suture theory- cartilage theory- functional matrix theory- combination of theories
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39
Q

What is the difference between a site of growth and a center of growth?

A
  • SITE OF GROWTH: location at which growth occurs- CENTER OF GROWTH: location at which independent growth occurs
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40
Q

What are the principles of the suture theory of growth?

A
  • all tissues that form bone have the intrinsic potential to do so- growth centers are locations of genetically controlled growth, independent from the environment- includes sutures, periosteum, synchondroses, and mandibular condyle as growth centers
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41
Q

Does experimental evidence control the suture therapy? What are the conclusions?

A
  • experimental evidence does NOT support this theory (transplantation studies, mechanical pull at sutures)- conclusion: sutures and periosteum are growth sties, merely a location of growth; sutures react, rather than acting independently
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42
Q

What are the principles of cartilage theory?

A
  • all cartilages are growth centers- cartilage in mandibular condyle controls growth of mandible- cartilage in nasal septum controls growth of maxilla- cartilage in the synchondroses controls growth of the cranial base
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43
Q

Does experimental evidence explain cartilage theory? Explain.

A

evidence PARTLY supports theory- transplanted cartilage forms synchondroses and nasal septum is capable of growth- transplanted cartilage from mandibular condyle shows significantly less growth- synchonrodses and nasal septum act as growth centers, but the mandibular condyle does not- early loss of nasal septum results in midface deficiency- after fractur of mandibular condyle, there is some reduction in mandibular growth; however, the original condyle is displaced and resorbs and a new condyle regenerates at the fracture site

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44
Q

What are the conclusions of the cartilage theory?

A
  • cranial base synchondroses and nasal septum act as independent growth centers, pushing maxilla forward- mandibular condyle is merely a growth site
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45
Q

What are the principles of the functional matrix theory?

A
  • heredity and genes play NO role in growth of craniofacial skeleton- growth of the face occurs in response to functional needs, mediated by the soft tissues in which the bones are embedded- ALL tissues that form bone are merely growth sites- clearest example: microcephaly vs. hydrocephaly
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46
Q

What is mandibular ankylosis? What theory does it support?

A
  • occurs as a result of infection or trauma in the TMJ area; mechanical restriction due to scarring prevents growth of the mandible- functional matrix theory
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47
Q

What are the clinical applications of the functional matrix theory?

A
  • rapid maxillary expansion- distraction osteogenesis (induction of bone at surgically-created sites; move bone away from each other and new bone fills in)
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48
Q

Does evidence support the functional matrix theory?

A

only has PARTIAL veracity- it is not clear how functional needs are transmitted to the tissues around the mouth and nose- recent advances in molecular biology and genetics show that genes are involved in the hereditary and mechanical modulation of craniofacial growth and development

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49
Q

Explain how the combination of theories describe craniofacial development.

A
  • growth of CRANIUM is a response to growth of the brain (sutures + periosteum = growth sites)- growth of CRANIAL BASE is a result of endochondral growth at synchodroses (growth centers)- growth of MAXILLA is primarily a result of apposition and remodeling as the bone is translated by soft tissues (sutures + periosteum = growth sites)- growth of the MAXILLA may result from endochondral growth at the nasal septum cartilage (growth center)- growth of the MANDIBLE occurs by endochondral growth at the condyle and surface remodeling as the bone is translated by soft tissues (condyle + periosteum = growth sites)
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50
Q

What 4 major changes occur during adolescence?

A
  • secondary sex characteristics appear- adolescent growth spurt takes place- fertility is attained- significant physiologic and psychological changes take place
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51
Q

What 4 changes do sex hormones cause?

A
  • accelerated growth of the genitals- development of secondary sex characteristics- physiologic changes such as shrinkage of lymphoid tissue and accelerated general body growth- even greater increase in transformation of cartilage to bone
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52
Q

According to Scammon’s growth curves, maxillary growth resembles ___ and mandibular growth resembles ___.

A
  • neural growth- general growth
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53
Q

Does sexual differences in adolescents begin earlier in males or females?

A

1.5-2.0 years earlier in females

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54
Q

True or false: One way to determine where an individual is developmentally is by asking their chronologic age.

A

FALSE. Chronologic age is no indication of where an individual is developmentally.

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55
Q

True or false: There is a correlation between secondary sexual characteristics and an individual’s position on the growth curve.

A

true

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56
Q

Growth in height correlates with ___.

A

jaw growth

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57
Q

A male’s growth spurt begins with ___ and ends with ___ and ___. It’s duration is ___.

A
  • growth- pigmented facial hair- mature voice- 5 years
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58
Q

A female’s growth spurt begins with ___ and ends at ___. It’s duration is ___.

A
  • breast development- menarche- 3 years
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59
Q

Other than relying on secondary sex characteristics, what are other ways to determine a patient’s growth status? Which is considered the “gold standard”?

A
  • hand and wrist radiograph- cervical vertebral maturational stage (CVMS)- superimposing serial radiographs (*gold standard!)
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60
Q

Place the following growths in the order in which they occur.- mandibular- maxillary- general- genital

A
  1. maxillary2. mandibular3. general4. genital
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61
Q

Between the maxilla and mandible, which grows more and longer? As growth occurs, does the profile become more/less convex?

A
  • mandible- less convex
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62
Q

What is the sequence of growth between length, width, and height?

A

WIDTH stops before LENGTH before HEIGHT

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63
Q

Width stops before ___ except ___.

A
  • growth spurt- alveolar arches widen in the area of molar eruption
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64
Q

Length and height increase through ___. ___ of the face grows longer than the ___ due to ___.

A
  • puberty- height- length- vertical growth of the mandible
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65
Q

Do the permanent incisors lie to the buccal or lingual of the primary incisors?

A

lingual

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66
Q

What is incisor liability?

A

permanent incisors are 2.0-3.5mm/quadrant wider than primary incisors

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67
Q

What are the 4 possibilities of “solutions” for incisor liability?

A
  • normal spacing (developmental and primate)- labial eruption of permanent (maxillary) incisors- increase in arch width across canines so canines erupt buccally (max > mand; boys > girls)- distal repositioning of canines in mandible (eruption of lateral incisors force mandibular canines distally into primate space)
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68
Q

What are the 2 types of characteristic spacing in primary dentition? Where is each located?

A
  • DEVELOPMENTAL: spaces between incisors- PRIMATE: on maxillary, mesial of canine; on mandibular, distal of canine
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69
Q

True or false: Incisor crowding at age 5 will not lead to crowding at age 13.

A

FALSE. Crowding in primary incisors always leads to crowding in permanent incisors.

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70
Q

True or false: Eruption of the permanent dentition with a more labial inclination will increase arch perimeter.

A

true

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71
Q

If there is a central diastema present that is <2mm with mixed dentition, should this be treated? Why or why not?

A
  • will likely close by itself; only close for esthetics or to make room for the laterals- should close with the eruption of the lateral incisors and/or eruption of canines
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72
Q

What is the Leeway space? Is it larger on the maxillary or mandibular arch?

A
  • difference in M-D width between primary canine/molars and permanent canines/premolars- larger in mandibular arch
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73
Q

What teeth move into the Leeway space?

A

permanent molars

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74
Q

What is the E-space?

A

difference in M-D width between primary 2nd molars and permanent 2nd premolars

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75
Q

If there is anterior crowding present in the primary dentition, what should be done?

A

send patient to the orthodontist BEFORE primary 2nd molars exfoliate (can place a lower lingual holding arch)

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76
Q

Mesial step, flush terminal plane, and distal step are measured on what primary teeth?

A

maxillary and mandibular primary second molars

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77
Q

A mesial step will result in what class of occlusion in the permanent dentition? A flush terminal plane? A distal step?

A
  • MESIAL STEP: Class I- FLUSH TERMINAL PLANE: Class II (edge-to-edge)- DISTAL STEP: Class II (full-blown)
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78
Q

How may occlusion change if the mandibular primate space is available during the eruption of the permanent 1st molar? Why does this not happen in the maxillary arch?

A
  • flush terminal plane relationship may become a mesial step (good!)- doesn’t happen in maxillary arch because the primate space in that arch is on the mesial side of the canine and since the canine has such a long root, it wouldn’t be able to move as much
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79
Q

What are the 2 factors that can lead to late mesial shift? Are they greater in the maxilla or mandible?

A
  • LEEWAY (E-) SPACE: mesial movement greater in mandibular molars than maxillary molars- DIFFERENTIAL GROWTH: mesial movement greater in mandible (because it reflects general growth)
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80
Q

What is the definition of epidemiology? What two studies measured the epidemiology of malocclusion?

A
  • study of the dynamics of occurrence of a condition or trait in a population or group- USPHS survey- NHANES III
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81
Q

Where do we get our current malocclusion prevalence data? What does this survey study?

A
  • NHANES III (National Health and Nutrition Estimates Survey III) 1989-1994- national survey of health care problems and needs
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82
Q

Describe the study design of NHANES III. (how many individuals, target population, race break-down)

A
  • 14,000 individuals- target population of 150,000,000- statistically designed weighted samples- 75% whites, 11% African Americans, and 8% Hispanics
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83
Q

True or false: Malocclusion is a disease.

A

FALSE. It is NOT disease, but a spectrum representing biological variablility/diversity.

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84
Q

What is the definition of malocclusion?

A
  • not a disease, but a spectrum representing biological variability/diversity- when the deviation from the normal reaches a certain degree of severity (threshold), it is termed malocclusion- what is of relevance is “clinically significant” deviation from normal occlusion
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85
Q

What are the 4 components of malocclusion?

A
  • sagittal or antero-posterior- vertical- transverse- intra-arch (crowding/spacing)
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86
Q

What are the 5 NHANES III traits?

A
  • irregularity index (crowding) intra-arch- midline diastema (spacing) intra-arch- posterior cross-bite (transverse)- overjet (antero-posterior)- overbite/openbite (vertical)
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87
Q

How does irregularity (crowding) change from childhood to youth? From youth to adult?

A
  • from childhood to youth, irregularity increased- from youth to adult, irregularity increased
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88
Q

Going from ages 8-11 to later age groups, do maxillary midline diastemas increase or decrease?

A

decrease (26% to 6%)

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89
Q

Mild Class ___ decrease from childhood to adolescence, which is probably the result of differential jaw growth during the adolescent growth spurt. The increase in mild Class ___ cases probably has the same cause.

A
  • II- III
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90
Q

Why is there a lack in change in the more severe Class II and Class III malocclusions from childhood to adolescence?

A

more severe skeletal mal-relationships that continue to be expressed during growth

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91
Q

Overbite and overjet: which is a horizontal component and which is a vertical component?

A
  • OVERJET: horizontal component- OVERBITE: vertical component
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92
Q

What is the transverse component of malocclusion?

A

lingual posterior cross-bite

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93
Q

As we age, deep bite generally ___ (inc/dec) and ideal overbite ___ (inc/dec) probably due to ___.

A
  • decreases- increases- continued vertical growth
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94
Q

What types of problems of malocclusions exhibits racial differences? Which are more common with which race?

A
  • vertical problems (anterior open bite and anterior deep bite); probably because skeletal issues- ANTERIOR OPEN BITE: affect larger number of African-Americans- ANTERIOR DEEP BITE: more common in European-American
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95
Q

What is the general prevalence of normal Class I, Class I malocclusion, Class II malocclusion, and Class III malocclusion? What race is most prevalent for Class II and Class III?

A
  • NORMAL CLASS I: 30%- CLASS I MALOCCLUSION: 50-55% (mostly crowding)- CLASS II MALOCCLUSION: 15-20%; most prevalent in European descent- CLASS III MALOCCLUSION: <1%; more prevalent in African American, Hispanic, and East Asian populations
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96
Q

In terms of the etiology of malocclusion, malocclusion is, in most instances, a ___ condition. It results from ___, but occasionally ___.

A
  • developmental (rarely pathological) condition- a complex interaction among multiple facotrs- a single specific cause is apparent
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97
Q

What are the 4 reasons to study etiology of malocclusion?

A
  • better understanding of condition- prevention- prediction- management
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98
Q

Is it more common to have a malocclusion of known etiology or unknown?

A

unknown (12x more likely)

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99
Q

What are the 4 possible etiologic factors of malocclusion?

A
  • hereditary factors- interference with normal development (pre- and post-natal influences)- trauma- disturbance of normal function
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100
Q

What are the 3 hereditary factors of malocclusion?

A
  • inherited disproportion between size of upper and lower jaws- inherited disproportion between size of teeth and jaws- heterogenous gene pool
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101
Q

What percentage of dental and facial variations that lead to malocclusion can be attributed to hereditary factors?

A

40%

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102
Q

The facial skeletal measurements correlation coefficient for parent-child pairs is ___. For dental measurements, it ranges ___. With increasing age, heritability estimates ___ (inc/dec) for skeletal and ___ (inc/dec) for dental variables.

A
  • 0.5- 0.15-0.5- increases- decreases
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103
Q

Inheritance is particularly strong for ___ followed by ___.

A
  • mandibular prognathism- “long face” pattern of facial development
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104
Q

What 3 factors can affect pre-natal development which may result in malocclusion?

A
  • agents (teratogens, biological agents, radiation, fetal alcohol syndrome)- fetal molding and birth injuries (Pierre Robin Sequence)- migration of neural crest cells (Treacher-Collins Syndrome; Craniofacial Microsomia)
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105
Q

What are the 4 factors that can affect post-natal development which may result in malocclusion?

A
  • childhood fractures- muscle dysfunction (atrophy, hyperfunction, muscle weakness syndromes)- acromegaly- condylar hyperplasia (old) = hemi-mandibular hypertrophy
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106
Q

What are some interferences with normal dental development?

A
  • fusion- supernumerary teeth (ex. mesiodens)- partial adontia (hypodontia/oligodontia)- ectopic eruption
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107
Q

Explain the basis of form-function interaction.

A

if function could affect the growth of the jaws and/or the position of the teeth, then altered function would be a major cause of malocclusion

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108
Q

What are 3 functional influences on malocclusion?

A
  • digit sucking habits- tongue thrusting habits (juvenile vs. compensatory)- respiratory pattern (extreme mouth breathing -> long face, but long face may not show mouth breathing)
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109
Q

What is the threshold for a digit sucking habit?

A

6 hours

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110
Q

ETIOLOGY IN CONTEMPORARY PERSPECTIVE:Etiology of most malocclusions are ___. There is a role of ___ and ___ influences. ___ traits have greater genetic influence. ___ traits have relatively greater environmental influence.

A
  • unknown- genetic- environmental- skeletal traits- dental traits
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111
Q

What are the 3 purposes of the chief complaint?

A
  • needs to be established first so you know the expectations- helps set priorities- provides hints for motivation and cooperation
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112
Q

What 4 items does the growth assessment include?

A
  • interview information- clinical height and weight- adolescent changes (secondary sex characteristics, facial hair, voice change)- radiographic information (hand wrist, cervical spine)
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113
Q

What 8 items are included in a patient’s dental history?

A
  • history of dental care- oral hygiene- premature tooth loss- familial history of malocclusion- previous orthodontic care- trauma- TMD history- dental anomalies (missing teeth, impacted teeth, tooth shape, orofacial syndromes)
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114
Q

What 5 things are included in a patient’s social history?

A
  • family background- siblings- school- patient/familial concerns and expectations- compliance
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115
Q

Angles classification only applies to ___ and ___. Dental malocclusion nomenclature is often loosely applied to ___. This implies that Dental Class I’s have ___ relationships and so on.

A
  • permanent teeth- AP plane of space- skeletal relationships- Skeletal Class I
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116
Q

True or false: Few skeletal malocclusions have an anteroposterior problem without other problems.

A

true (alignment, vertical, transverse)

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117
Q

True or false: If a patient has a Class I Skeletal relationship, their dentition will not have any malocclusion.

A

FALSE. Within Class I skeletal relationships, other malocclusion problems can exist in the transverse and vertical planes.

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118
Q

What are the two skeletal relationships that would result in a Class II skeletal relationship?

A
  • maxillary protrusion- mandibular retrusion
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119
Q

What are the two skeletal relationships that would result in a Class III skeletal relationship?

A
  • maxillary retrusion- mandibular protrusion
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120
Q

What type of radiography is used to identify true facial asymmetry?

A

P-A cephalomeric head film

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121
Q

What type of transverse skeletal movement contributes to skeletal asymmetry?

A

movement of the maxilla and mandible laterally when looking at the coronal plane

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122
Q

What type of transverse skeletal movement contributes to maxillary constriction?

A

movement of the maxilla medially when looking at the coronal view

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123
Q

What are the 2 possible causes of posterior crossbites?

A
  • dental constriction- skeletal constriction
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124
Q

What type of bite can often be found with a long face? With a short face?

A
  • anterior open bite- deep bite
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125
Q

True or false: A short face can have a normal occlusion, but a long face never has a normal occlusion.

A

FALSE. All face types can have a normal occlusion.

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126
Q

To evaluate the facial relationship, what 5 factors are examined? What does it provide insight into?

A
  • general facial form- facial form analysis- overjet- molar, canine, and overjet relationships- cephalometrics- provides insight into AP, vertical, and transverse skeletal relationships
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127
Q

What medications may affect orthodontic procedures?

A

oral or intravenous bisphosphonates

128
Q

What is the most common malocclusion?

A

Dental Class I malocclusion

129
Q

What is the Frankfurt Horizontal Line between?

A

external acoustic meatus to the bottom of the eye

130
Q

The general facial form is defined by the appearance of what line? How specific is this measurement?

A
  • N-A-Pg line (nasion-ala-chin)- does not identify specific problems
131
Q

What is charted on the extraoral examination chart? (9)

A
  • asymmetry (midface/lower face)- lips apart at rest- mentalis muscle strain- profile (concave, convex, straight)- mandible/maxilla (prognathic, retrognathic)- vertical face height- mandibular plane angle- midlines (face, maxillary, mandibular)- CR/CO shift
132
Q

A straight profile is usually associated with what skeletal and dental class? Why can it include some convexity at younger ages?

A
  • skeletal and dental class I- because the differential growth of the mandible
133
Q

A convex profile is usually associated with what maxilla and mandibular position? With what skeletal and dental class?

A
  • protrusive maxilla- retrusive mandible- skeletal and dental class II
134
Q

A concave profile is usually associated with what maxilla and mandibular position? With what skeletal and dental class?

A
  • retrusive maxilla- protrusive mandible- skeletal and dental class III
135
Q

What are the (4) essential elements of anterior-posterior facial form analysis?

A
  • maxilla- mandible- maxilla/mandible- lip protrusion
136
Q

What are the (5) essential elements of vertical facial form analysis?

A
  • mandibular plane- facial proportions- lip competence- labiomental fold- teeth to upper lip
137
Q

What are the (2) essential elements of transverse facial form analysis?

A
  • upper and lower facial symmetry- maxillary teeth to facial midline
138
Q

Facial form analysis provides ___, addresses ___, relates ___, and attempts to ___.

A
  • provides skeletal information in multiple planes- addresses skeletal and dental protrusion by implication (A-P)- relates the teeth to the face (vertical and transverse)- attempts to localize the problem
139
Q

Where is the line drawn to identify protrusive/retrusive lips? What angles (2) are used?

A
  • line drawn from chin to tip of nose- nasal labial angle (between nose and philtrum)- mental-labial sulcus (dip between the lower lip and tip of chin)
140
Q

When assessing the vertical dimension of the face, what proportion of the face should be occupied from ala to tip of chin?

A

1/3

141
Q

What is lip incompetence?

A

the inability to close the lips over the anterior teeth

142
Q

Is the profile analysis reliable? In what 3 instances is it difficult?

A
  • reliable- very young children- Class III- when vertical problems are present
143
Q

Are noses typically more prominent in males or females? Chins?

A

males (for both)

144
Q

The late growth of the maxilla happens more in what direction in the female? The mandible in what direction in the male?

A
  • maxilla in vertical direction in female- mandible in anterior direction in male
145
Q

As you age, is there more or less incisor display? Are you lips thinner or thicker?

A
  • less incisor display- thinner
146
Q

True or false: Molars and overjet can be used as a guide for skeletal relationships.

A

true

147
Q

What is examined in an intraoral examination? (6)

A
  • oral hygiene problems- periodontal considerations- untreated caries- missing teeth- dental abnormalities- soft tissue pathology
148
Q

Describe a Class I molar occlusion and a Class I canine occlusion.

A
  • MOLAR: mesiobuccal cusp of maxillary first molar occludes in the buccal groove of the mandibular first molar- CANINE: maxillary canine incisal tip is between mandibular canine and premolar
149
Q

What percentage of cases has consistency between the skeletal and dental relationships?

A

96%

150
Q

Which is the most accurate predictor of skeletal relationship: canine, molar, or overjet?

A
  • canine: 0.66- molar: 0.69- OVERJET: 0.82-0.89
151
Q

What is the difference between overjet and overbite?

A
  • OVERJET: the distance between the maxillary incisors and mandibular incisors in the horizontal plane- OVERBITE: the distance of overlap between the maxillary incisors and mandibular incisors in the vertical direction (normal is 50%)
152
Q

What is an anterior crossbite also known as?

A

negative overjet

153
Q

What is the difference between buccal and lingual posterior crossbites?

A
  • buccal crossbite is when maxillary teeth are shifted more buccal- lingual crossbite is when the maxillary teeth are shifted more lingual
154
Q

What is the “standard of practice” used to evaluate faces? Does it allow evaluation of hard or soft tissues? What 4 things is it used for?

A
  • cephalometrics- hard AND soft tissues- diagnosis, progress, treatment, and growth record
155
Q

What angle is used to measure the maxilla position in cephalometrics? What does a larger angle indicate? A smaller angle? What is a normal value?

A
  • SNA (sella, nasion, a-point/front of maxilla)- larger = Class II tendency- smaller = Class III tendency- 82 degrees (81 in children)
156
Q

What angle is used to measure the mandible position in cephalometrics? What does a larger angle indicate? A smaller angle? What is a normal value?

A
  • SNB (sella, nasion, b-point/front of mandible)- larger = Class III tendency- smaller = Class II tendency- 80 degrees (78 in children)
157
Q

What angle is used to measure the relationship of the maxilla to mandible in cephalometrics? What does a larger angle indicate? A smaller angle? What is a normal value?

A
  • ANB (a-point, nasion, b-point)- larger = Class II tendency- smaller = Class III tendency (negative angle)- 2 degrees (3 in children)
158
Q

What two measurements are used to determine vertical proportions in cephalometrics? What does a larger measurement indicate? A smaller measurement?

A
  • mandibular plane angle (Downs Analysis) and % face height- larger = longer face- smaller = shorter face
159
Q

What angle is used to measure the upper incisal position in cephalometrics? What does a larger angle indicate? A smaller angle? What is a normal value?

A
  • upper incisor to frankfort horizontal plane (Reidel Analysis)- larger = more proclined- smaller = more uprighted- 110 degrees
160
Q

What angle is used to measure the lower incisal position in cephalometrics? What does a larger angle indicate? A smaller angle? What is a normal value?

A
  • lower incisor to mandibular plane- larger = more proclined- smaller = more upright- 90 degrees
161
Q

What angle is used to measure the upper and lower incisor relationship in cephalometrics? What does a larger angle indicate? A smaller angle? What is a normal value?

A
  • interincisal angle- larger = more upright- smaller = bimaxillary protrusion tendency- 135 degrees
162
Q

True or false: There is a lot of agreement between skeletal classes derived from different cephalometric methods.

A

FALSE: Recent OSU data revealed that there is little agreement among cephalometrically derived skeletal classes by different methods.

163
Q

Treatment planning ability was not enhanced by records other than ___ and ___. Treatment planning reliability is ___%.

A
  • casts- facial photos- 53-73%
164
Q

What are the 3 requirements in fabricating diagnostic study casts?

A
  • soft tissue reflected- trimmed in CO with backs parallel- symmetric trimming
165
Q

What are the 5 uses of diagnostic study casts?

A
  • evaluation- space analysis- tooth size analysis- case presentation- treatment evaluation/documentation
166
Q

How is an arch length analysis done with permanent dentition? With mixed dentition?

A
  • direct measurement- Tanaka-Johnson and Moyer’s
167
Q

What are the 5 assumptions made when doing an arch length analysis on a patient with mixed dentition? (Tanaka-Johnson)

A
  • all succedaneous teeth are developing normally- there is a correlation between the lower incisor width and the width of the unerupted succedaneous teeth- the prediction tables are valid for your patient- arch dimensions do not change during growth- the mesial molar shift is predictable
168
Q

In arch length analysis using the Tanaka-Johnson method, how can you predict the size of the premolars and canine on one side of the mandible? Of the maxilla?

A
  • MANDIBLE:1/2 the width of the LOWER incisors + 10.5mm- MAXILLA:1/2 the width of the LOWER incisors + 11.0mm
169
Q

How is the space discrepancy for each arch determined during arch length analysis?

A

(space available) - (measured size of the incisors + predicted size of the canines and premolars)

170
Q

Describe tooth size analysis. How is it stated?

A
  • compares the sum mesio-distal dimension of maxillary and mandibular teeth; usually canine-to-canine or molar-to-molar- stated in terms of maxillary or mandibular excess
171
Q

What is Moyer’s method to estimate arch length/space availability?

A

measure the total width of permanent MANDIBULAR incisors and use table to predict width of permanent canines and premolars

172
Q

How is the space available in the arch measured?

A

measure from the mesial of the permanent 1st molar to the mesial of the permanent 1st molar; divide into 4 segments; add together

173
Q

What is Steiner Analysis?

A

relates the A-P position of the maxilla and mandible to the cranial base and to each other (SNA, SNB, ANB)

174
Q

What is the E line? Where should the upper and lower lip be? How does it change as you age?

A
  • esthetic plane from the nasal tip to the bulge of the chin- upper lip should be 4 mm behind the line- lower lip should be 2 mm behind the line- becomes less protrusive by 0.2 mm per year
175
Q

What are the 3 limitations of Angle’s classification?

A
  • only considers the anterior-posterior plane- does not include intra-arch problems (crowding/spacing)- does NOT discriminate between skeletal and dental malocclusions
176
Q

Describe the “Problem-Oriented Approach” to diagnosis.

A
  • diagnosis is a systematic approach to establishing the dental/orthodontic problems- treatment planning is determining potential solutions for the identified problems and integrating them into a cohesive plan
177
Q

What are the 5 steps of Ackerman and Proffit’s Classification of Malocclusion?

A
  1. facial proportion and esthetics2. alignment and symmetry within the dental arches3. skeletal and dental relations in the transverse plane4. skeletal and dental relations in the antero-posterior plane5. skeletal and dental relations in the vertical plane
178
Q

What are the 2 categories of problems in a problem list?

A
  • pathology (systemic disease, dental pathology, periodontal disease, dental caries)- developmental problems
179
Q

How do you prioritize the problem list?

A

sequence the 5 components of the Ackerman-Proffit scheme based on severity (NEED TO INCLUDE PATIENT’S WISHES!)

180
Q

Place these items in a prioritized problem list:- A-P (skeletal Class II, increased overjet)- transverse (mand midline shifted 3mm, crossbite)- missing #29- soft tissue, facial esthetics (protrusive lips)- malformed #28- ankylosed teeth- dental alignment (crowding, rotations)- vertical (80% overbite; increased curve of Spee)

A

PATHOLOGY:- ankylosed teeth- malformed #28- missing #29DENTOALVEOLAR:- dental alignment (crowding, rotations)- A-P (skeletal Class II, increased overjet)- vertical (80% overbite, increased curve of Spee)- transverse (mand midline shifted 3mm, crossbite)- soft tissue, facial esthetics (protrusive lips)

181
Q

What is the sequence of steps in treatment planning?

A
  • control all disease states first- set priorities for orthodontic treatment- balance between patient’s wishes and severity of the problem- above all, do no harm!
182
Q

True or false: When solving some problems on the problem list, the result may interact with other problems.

A

true (benefits need to outweigh the cost-risks)

183
Q

What type of informed consent is now common in treatment planning?

A

patient-centered (paternalistic approach, in which the patient gets little say, is a thing of the past)

184
Q

What are the 4 indications for orthodontic treatment?

A
  • psychosocial indications- developmental indications- functional indications (respiration, TMD, masication, and speech)- trauma/disease control
185
Q

True or false: If you wait to perform orthodontic treatment until a later age on a child who has psychosocial indications, his self esteem at the end of treatment will be the same as if he were treated earlier.

A

true (performing orthodontics early only gives him a greater self-esteem at an earlier point in time)

186
Q

What does evidence say about orthodontic treatment and TMD?

A

there is no evidence that treatment will prevent TMD and no evidence that it will introduce it

187
Q

Malocclusion can be related to what 3 components?

A
  • skeletal component (growing/non-growing)- soft tissue component- dental component (permanent/mixed dentition)
188
Q

What are 4 ways to fix a Class II malocclusion?

A
  • elastics (reciprocal)- head gear devices- space availability (so you can move teeth?)- extraction
189
Q

What are the 4 ways to fix a Class III malocclusion?

A
  • elastics (reciprocal)- head gear devices- space availability (so you can move teeth?)- extraction
190
Q

What type of bite is seen in anterior over eruption? In posterior overeruption? In anterior undereruption? In posterior undereruption?

A
  • ANTERIOR OVERERUPTION: anterior deep bite- POSTERIOR OVERERUPTION: anterior open bite- ANTERIOR UNDERERUPTION: anterior open bite- POSTERIOR UNDERERUPTION: anterior deep bite
191
Q

What device is used to intrude teeth?

A

TAD (temporary anchorage device)

192
Q

True or false: Retracting proclined incisors has an effect on overbite.

A

true

193
Q

There is severe crowding (9+ mm) in a patient.1. extract primary canines (to align incisors)2. extract primary 1st molars (to promote eruption of #4’s)3. extract #4’s (1st premolars)4. align teeth and close spaceThis is an example of…

A

serial extractions

194
Q

True or false: If there is deficient mandibular growth, one can treat it with an expander.

A

FALSE! There are no sutures.

195
Q

How does the PDL respond to short-duration forces and prolonged forces?

A
  • resists short-duration forces; acts as “shock absorber”- remodels PDL and adjacent bone; remodeling is mainly done by fibroblasts
196
Q

What type of cell does the remodeling of the PDL during tooth movement?

A

fibroblasts

197
Q

Force ___ and ___ are both important to remodel the PDL and move teeth.

A

magnitude and duration

198
Q

What type of cell is required for bone resorption? How does it remove bone? What is its origin?

A
  • osteoclasts- produces acid and enzymes to remove bone- hematopoietic stem cell -> monocytes -> osteoclasts
199
Q

Are osteoclasts normally available in the PDL? Where do they originally come from?

A
  • not normally available in PDL- need to be recruited from blood vessels or bone marrow
200
Q

What are the 2 theories of orthodontic tooth movement? Describe each.

A
  • BIOELECTRIC THEORY: bony changes caused by electric signals (force induces piezoelectric signals; bioelectric potential changes cell activity)- PRESSURE-TENSION THEORY: bony changes caused by chemical signals (pressure and tension alter blood flow; formation and release of chemical messengers; chemical messengers change cell activities)
201
Q

What is the response to sustained light pressure of 1-2 seconds? 3-5 seconds? Minutes? Hours? 2 days?

A
  • 1-2 SECONDS: tooth displacement within PDL space- 3-5 SECONDS: blood flow changes- MINUTES: oxygen tension at compression side decreases -> prostaglandins (PG-E) and cytokines (IL-1) release- HOURS: chemical messengers cause metabolic change; second messengers (cAMP) release -> osteoclast recruitment (from blood), maturation and activation -> frontal bone resorption- 2 DAYS: tooth movement beyond the PDL space
202
Q

What is the response to sustained heavy pressure of 1-2 seconds? 3-5 seconds? Minutes? Hours? 3-5 days? 7-14 days?

A
  • 1-2 SECONDS: tooth displacement within the PDL space- 3-5 SECONDS: blood vessels occluded on the pressure side- MINUTES: blood flow cut off to compressed PDL- HOURS: cell death in compressed area- 3-5 DAYS: osteoclasts recruitment (from bone marrow inside alveolar bone), maturation and activation -> undermining bone resorption- 7-14 DAYS: tooth movement beyond PDL space
203
Q

How does blood vessel response differ between light sustained pressure and heavy sustained pressure?

A
  • LIGHT: chemical messengers cause metabolic change; second messengers (cAMP) release -> osteoclast recruitment (from blood), maturation and activation -> frontal bone resorption (from the SAME side of PDL)- HEAVY: osteoclasts are recruited from bone marrow on the OPPOSITE side of PDL -> undermining resorption
204
Q

In the graph of time vs tooth movement, describe the differences in the plots of light force and heavy force.

A
  • LIGHT: a steady increase in tooth movement- HEAVY: bursts of tooth movement (looks like steps)
205
Q

True or false: Continuous force is required, but sustained force is not absolutely required.

A

FALSE: Sustained force is required, but continuous force is not absolutely required.

206
Q

How much time is needed per day for tooth movement?

A

4-8 hours

207
Q

The compression area is ___ (larger/smaller) during translation than tipping so ___ (greater/lesser) force is needed to produce the same pressure.

A
  • larger- greater
208
Q

Is tooth movement slower in adults or children? Why?

A
  • slower in adults- children have remaining alveolar growth and relatively less dense bone
209
Q

What is the effect of osteopetrosis and osteoporosis on tooth movement?

A
  • OSTEOPETROSIS: “stone-bone”; may slow tooth movement- OSTEOPOROSIS: accelerate tooth movement
210
Q

Is tooth movement generally faster in the maxilla or the mandible? Why?

A
  • faster in maxilla- bone density is lower in maxilla
211
Q

What are the 2 categories of drugs that may inhibit orthodontic tooth movement?

A
  • prostglandin inhibitors (NSAID, corticosteroids)- bisphosphonates
212
Q

What are the 2 major ways to accelerate tooth movement? What other ways have been suggested?

A
  • local injury (Regional Acceleratory Phenomenon “RAP”)- corticotomy assisted tooth movement (Wilckodontics)- other proposed methods: vibration, phototherapy, ultrasound
213
Q

True or false: The amount of tooth movement will steadily increase as you increase pressure.

A

true and false: it will increase for a while, but it will eventually reach an optimal force*optimal force varies with teeth and depends on the pressure produced at the PDLs

214
Q

What is the purpose of anchorage? Is anchorage needed in reciprocal space closure? In differential space closure?

A

-resistance to unwanted tooth movement and to the reaction force- no- yes

215
Q

What are anchorage control values based on? What type of force is used with anchorage control?

A
  • PDL surface area- light force
216
Q

What is the difference between stationary anchorage control and skeletal anchorage control?

A
  • STATIONARY: only allows bodily movement of the molars which requires stronger pressure (uses molar as anchor)- SKELETAL: uses temporary anchorage devices (TADs) to prevent unwanted tooth movement
217
Q

What is the general pulpal reactions to orthodontics? Can teeth with root canals be moved orthodontically? What must be done with calcium hydroxide filled teeth (anterior)?

A
  • generally pulpal reaction is minimal; if there is a loss of vitality, it may be due to previous trauma- teeth with proper root canals can be moved orthodontically- for calcium hydroxide filled teeth (anterior) with open apices, try to avoid major tooth movement
218
Q

What is the effect of orthodontic treatment on root remodeling? Where is there permanent loss of root surface? What teeth are most prone?

A
  • root remodeling is a constant feature of orthodontic tooth movement (all patients exhibit some resorption, with only 1-2% reaching severe); individual variability and multiple potential risk factors- primarily at the apex- incisors and second premolars
219
Q

What are the categories of apical root resorption?

A
  • category 1: slight blunting- category 2: moderate (1/4)
220
Q

What are the 4 risk factors for excessive root resorption?

A
  • abnormal root morphology (conical roots, pointed apices, dilacerations)- prolonged treatment time, excessive and prolonged orthodontic forces- genetic predisposition- history of root resorption
221
Q

What is the effect of orthodontic treatment on alveolar bone height? How does periodontal disease relate to this?

A
  • usually <0.5 mm height reduction during orthodontics- major periodontal concerns should be evaluated/addressed by periodontist; active periodontal disease must be controlled before orthodontic treatment
222
Q

How many grams are required for jaw movement? How many for tooth movement?

A
  • 500-1000 grams for jaw movement- 100-200 grams for tooth movement
223
Q

How many hours/day are required for jaw movement? For tooth movement?

A
  • 12-16 hours/day- 4-6 hours/day
224
Q

What are the 3 major clinical problems of maxillary growth?

A
  • maxillary hypoplasia (Class III)- maxillary prognathism (Class II)- transverse deficiency (posterior crossbite)
225
Q

To restrain maxillary growth with headgear, what force magnitude is needed? What duration? What frequency? What are the common headgear variations?

A
  • force magnitude: 500-1000 grams- duration: 12-16 hours/day- frequency: intermitent, not continuous- variations: high-pull, cervical pull, combo
226
Q

For maxillary protraction facemask and reverse pull headgear, where are the intraoral components? When is it done? How long does it last? How much skeletal movement can be achieved?

A
  • anchored on maxillary molars (and sometimes premolars) or temporary implants or ankylosed teeth- before age 10-11- often lasts 6-8 months- generally cannot achieve more than 3 mm of skeletal movement
227
Q

For a transverse deficiency palatal expansion, what type of malocclusion is it used for? What is targeted?

A
  • class III malocclusion, class II with vertical problems, and as an isolated problem (no class II/III); maxillary transverse deficiency- midpalatal suture
228
Q

What is the rate of rapid palatal expansion, when is it used, and how long does it take? What is the rate of slow expansion and when is this used? Expansion is followed by what?

A
  • 1mm/day for adolescents for 2-3 weeks- 1mm/week for late adolescents and young adults- expansion is followed by 3-6 months of retention for bone consolidation
229
Q

What type of expander is normally used? For preschoolers and pre-adolescent children, what type of expander is used?

A
  • Jackscrew-type is normally used- W-arch or Quad helix is used for preschool and pre-adolescents
230
Q

What is the biological basis for rapid palatal expansion? What increases with age which makes it more difficult for suture expansion? What group is RPE most often done on?

A
  • biologic basis is distraction osteogenesis- interdigitation (not fusion) of the midpalatal suture increases with age which increases the difficulty of suture expansion- most often done in adolescents and pre-adolescents
231
Q

What is the proportion of skeletal and dental movements that is produced by rapid palatal expansion in adolescents and pre-adolescents? In adults?

A
  • adolescents: 50% skeletal and 50% dental movement- adults: mostly, if not entirely, dental movement
232
Q

The mandible grows mainly at the ___ via ___ formation and the ___ and ___ surfaces via ___ formation.

A
  • condyles- endochondral- posterior and lateral- intramembranous formation
233
Q

What are the 3 common clinical problems of mandibular growth?

A
  • mandibular hypoplasia/retrognathism (Class II)- mandibular prognathism (Class III)- transverse constriction (Brodie bite)
234
Q

What effect do functional appliances have on the growth of the mandible?

A

can accelerate mandibular growth, but may not increase the final size of the mandible

235
Q

Why is there an inconsistent skeletal effect on the mandible by functional appliances?

A

loading pattern (only a small portion of the condyle was affected by the appliance)

236
Q

What type of tooth movement is caused by functional appliances?

A

proclined lower incisors or retroclined upper incisors (good to reduce overjet, but not good for patients who already had proclined/retroclined lower/upper teeth)

237
Q

Why is the restraining mandibular growth chin cup head gear rarely used nowadays? Instead, what is the most common treatment for mandibular prognathism?

A
  • reduces mandibular protrusion by increasing anterior face height rather than shortening its size- mandibular surgical setback after the cessation of mandibular growth
238
Q

Why is widening the mandible limited via orthodontics? How is mandibular bone expanded?

A
  • the symphysis connecting the 2 halves of the mandible fuses at age 7-8 months; mandibular expansion appliances can expand dento-alveolus, but not the basal bone- need surgical procedure (distraction osteogenesis)
239
Q

What is distraction osteogenesis? Distraction histogenesis?

A
  • DISTRACTION OSTEOGENESIS: surgically and mechanically induce the bone regeneration process by creating an osteotomy; the 2 bone fragments are gradually opened by the distractor to create a gap for new bone formation, consolidation and remodeling- DISTRACTION HISTOGENESIS: adaptation of the soft tissues (blood vessels, ligaments, muscles, and nerves)
240
Q

Name and describe the 4 major sequential phases of DO.

A
  1. LATENCY: the interval between osteotomy operation and the start of distraction2. DISTRACTION: the period that distractor activation takes place3. CONSOLIDATION: the post-distraction period (appliance still in place) to allow for new bone formation4. REMODELING: the period that the regenerated bone continues to remodel (after appliance removal)
241
Q

Rank the symphyseal distractors in terms of stability from high to low and in terms of reliability of transferring expansion force to bone.

A
  • STABILITY:hybrid > tooth-borne > bone-borne- RELIABILITY OF TRANSFERRING EXPANSION FORCE TO THE BONE:tooth-borne > hybrid
242
Q

True or false: Mechanical force can be used to modify bone growth without surgery for certain problems.

A

true (maxillary protrusion, hypoplasia and transverse constriction, mandibular retrognathia)

243
Q

True or false: Growth patterns and structures available for growth modification are the same between the maxilla and mandible.

A

FALSE: They are different.

244
Q

True or false: Growth modification treatments are age-sensitive and the effectiveness can very widely among individuals.

A

true

245
Q

What is the usual amount of growth modification possible?

A

several mm (thus not adequate for correcting severe skeletal problems -> surgery)

246
Q

In clinical orthodontics, what units are usually used to measure force vectors?

A

grams (g) or ounces (oz)

247
Q

What law is used to calculate a resultant force from multiple vectors? How is this done?

A
  • parallelogram law- split each vector into x, y, and z components and add each together separately to get the total x, y, and z forces
248
Q

How do you add force vectors together when they have a common point of application? When they have different points of application?

A
  • add them using parallelogram (lining them up, tip to tail)- extend the lines so that they intersect, then use parallelogram law
249
Q

What is the definition of the center of resistance? What is the difference in the center of resistance between a free object and a partially restraint object?

A
  • a point at which resistance to movement can be concentrated for mathematical analysis- FREE OBJECT: C res = center of mass/gravity, or the point of balance- PARTIALLY RESTRAINT OBJECT: C res is determined by the nature of the external constraints
250
Q

Where is the C res of a tooth located? What factors make the C res of a tooth vary?

A
  • C res is at the approximate midpoint of embedded portion of the root (or halfway between the apex and alveolar crest)- varies with alveolar bone height and root length (AKA the part of the root embedded in the alveolar bone); does NOT vary with an orthodontic force (unless that force changes alveolar bone height)
251
Q

If there is alveolar bone loss, which way would the C res move? If there were root resorption?

A
  • ALVEOLAR BONE LOSS: C res moves apically- ROOT RESORPTION: C res moves coronally
252
Q

What is the definition of moment?

A

if the line of action of a force does not pass through C res, the force will produce some rotation of the tooth; this potential for rotation is measured as a moment (can be clockwise or counterclockwise)

253
Q

How is the magnitude and direction of the moment found?

A
  • MAGNITUDE: (magnitude of the force) x (perpendicular distance from C res to the line of action)- DIRECTION: clockwise or counter-clockwise
254
Q

What is the definition of a couple? What can a couple produce? What can a single force produced?

A
  • two forces that are equal in magnitude, parallel and non-collinear, in opposite directions- a couple produces pure rotation (translational effects produced by the 2 forces of a couple cancel each other out)- a single force (not passing the C res) produces a rotational and translational effect, but not a pure rotation
255
Q

What is the definition of the center of rotation (C rot)? How does it vary from C res? What is C rot used for in orthodontics?

A
  • the point around which an object is rotating- unlike C res, C rot of a tooth is not at a fixed point and varies with the force/moment/couple applied to the tooth- in ortho, C rot can be changes to achieve different types of tooth movement and clinical goals
256
Q

What are the 3 types of orthodontic teeth movement?

A
  • translation- pure rotation- combination of translation and rotation (tipping)
257
Q

What is the definition of translation? How is translation produced?

A
  • all points on the object move in the same direction- to produce translation, the line of action of a single force needs to pass through the C res; it is the line of action, rather than the point of attachment (hook, bracket, etc.) that determines whether translation is produced
258
Q

True or false: If a force doesn’t pass through the C res, it is not possible to achieve translation.

A

FALSE. When a force is not passing through the C rest, translation is still achievable by canceling the moment produced by the force using opposite moment produced by a couple (torsion of the archwire)

259
Q

What is the definition of tipping? Under what conditions is tipping achieved?

A
  • when some points on an object move differently (direction, rate, or both) than other points on the same object- when the line of action of a single force does not pass through the C res
260
Q

How is the C rot of a particular tooth movement determined?

A

can be determined by examining the movements of two points on the tooth*this question asks about the OVERALL movement, not just the rotational component

261
Q

What is the difference between uncontrolled tipping and controlled tipping?

A
  • UNCONTROLLED TIPPING: a force to the crown causes a tooth to rotate around a center near (apical to) the middle of the root -> the apex and crowns move in opposite directions to each other (the incisal edge still moves more than the apex)- CONTROLLED TIPPING: a force, together with a moment to the crown, causes the tooth to rotate around its apex -> the crown moves the greatest distance and the apex moves the least
262
Q

When a simple (single or uncontrolled) tipping force is applied to the crown of a single-rooted tooth, the center of rotation is usually located:A. at the apexB. at the cervical lineC. 5 mm beyond the apexD. one-third root length from the apexE. two-thirds root length from the apex

A

D. one-third root length from the apex

263
Q

When an uncontrolled tipping force is applied to the crown of a single-rooted tooth, the fulcrum is usually located:A. at the apexB. at the cervical lineC. 5 mm beyond the apexD. 1/3 of the root length from the apex

A

D. 1/3 of the root length from the apex

264
Q

What type of material are orthodontic archwires made of? What are the 2 phases of that material? What does Hooke’s Law say about this material?

A
  • elastic material- elastic and plastic phases- it takes 2x as much force to make spring stretch 2x as much (F = -kx)
265
Q

On a force/deflection curve, what is the proportional limit? The failure point?

A
  • PROPORTIONAL LIMIT: when the wire begins to flex- FAILURE POINT: when the wire actually breaks
266
Q

True or false: The force/deflection curve changes with different archwire diameters and materials.

A

true

267
Q

How does the force/deflection curve change with increasing diameter of the archwire?

A

as diameter increases, slope of stiffness line becomes more steep

268
Q

What is the definition of stress? Of strain? Of elastic modulus? Identify the units of measurement for each.

A
  • STRESS = force/areaunits: newton/square millimeter, Pascal, etc.- STRAIN = (change in length)/(original length)units: none, often as a % (1 strain = 0.1% change)- ELASTIC MODULUS = stress/strainunits: same as stress
269
Q

What curve measures extrinsic stiffness? What curve measures intrinsic stiffness?

A
  • EXTRINSIC STIFFNESS: force/deflection curve (b/c does not take into account the geometry/diameter of the wire)- INTRINSIC STIFFNESS: stress/strain curve (b/c normalizes the geometry/diameter out)
270
Q

A homogenous material of different dimensions should have ___ (one/many) stress/strain curves and ___ (one/many) force/deflection curves.

A
  • one stress/strain curve- many force/deflection curves
271
Q

What is the definition of stiffness? Springiness? Springback? Range? Strength?

A
  • STIFFNESS: slope of linear portion of force/deflection curve or elastic modulus in stress/strain curve- SPRINGINESS: 1/(stiffness)- SPRINGBACK: ability to return to original shape- RANGE: distance a wire can be bent before permanent deformation- STRENGTH: (stiffness) x (range)
272
Q

What is the definition of resilience? Formability?

A
  • RESILIENCE: area under the stress/strain curve out to the proportional limit- FORMABILITY: amount of permanent deformation a wire can withstand before failure
273
Q

What are the 5 ideal properties of orthodontic archwires? Why?

A
  • HIGH STRENGTH (to produce desired force magnitude without excessive deflecting the archwire)- LOW STIFFNESS (to produce relatively constant force)- HIGH RANGE (to deflect the archwire to a great extent without causing permanent deformation- HIGH FORMABILITY (to make bends on the archwire without breaking it)- CAPABILITY OF TAKING WELD/SOLDER (not a direct mechanical property)
274
Q

What are the variables of the archwire that affect mechanical property? What is each important for?

A
  • SHAPE: (round vs. rectangular) is important for shear (torsion) force, but not bending force- SIZE: cross-sectional diameter is important for bending- ATTACHMENT MODE: tying archwire tightly to brackets increases strength, but decreases springiness and range- LENGTH: increasing length (adding loops) increases range and springiness- COMPOSITION: (NiTi vs. stainless steel vs. TMA)
275
Q

NiTi wires have ___ (high/low) stiffness, ___ (good/poor strength), ___ (high/low) range, and ___ (good/poor) formability.

A
  • low stiffness- good strength- high range- poor formability
276
Q

Describe the difference in the force deactivation curve (determines force applied to teeth) between stainless steel and NiTi archwires.

A
  • STAINLESS STEEL: sharp increase in bending moment with small increase in deflection; AKA by bending the wire slightly, it creates a lot of force- NITI: a more gentle change in bending moment as deflection increases; AKA when wire is bent, it will apply a more gentle force
277
Q

How is a superelastic NiTi (A-NiTi) different from a normal NiTi?

A
  • not considered a typical elastic material because it has multiple phase transitions- constant force is produced during the austenitic martensitic phase transition
278
Q

What is the general archwire choice for initial alignment? For leveling?

A
  • INITIAL ALIGNMENT: small size NiTi (rarely stainless steel, only if some formability of the wire is needed)- LEVELING: relatively large size TMA or stainless steel
279
Q

What is the general archwire choice for torquing? For finishing? For growth modification devices?

A
  • TORQUING: large size rectangular stainless steel or TMA- FINISHING: stainless steel or TMA (size can vary depending on purpose)- GROWTH MODIFICATION DEVICES: much larger stainless steel wires than common arch wires
280
Q

Loops and helices are used in archwires primarily to:A. align teethB. increase force of the wiresC. increase flexibility of the wiresD. hold soft tissues away from the orthodontic brackets

A

C. increase flexibility of the wires

281
Q

What are the 4 advantages of removable appliances?

A
  • removable- more hygienic than fixed appliances- may be more esthetic (ex. invisalign)- easier for certain growth modification treatment than fixed appliances
282
Q

What are the 3 disadvantages of removable appliances?

A
  • relying on patient compliance- less precise force control than fixed appliance- involves lab work
283
Q

What are the 3 primary uses of removable appliances?

A
  • growth modification- minor tooth movements- retention
284
Q

What 3 removable intraoral appliances stimulate mandibular growth? Describe each.

A
  • BIONATOR: stimulates mandibular growth; controls tooth eruption; forces patient to move lower jaw forward to completely bite down- TWIN BLOCK: stimulates mandibular growth; can include an expander/headgear; has maxillary and mandibular portions that fit like a lock and key to make mandible go in the correct position- FRANKLE APPLIANCE: stimulates mandibular growth (lingual pads); completely tissue borne; buccal shields or lip pads to reduce cheek and lip pressure for expansion
285
Q

What is the difference between the J Hook headgear and other headgear?

A
  • J hook: connected to soldered hooks on the archwire- other headgears: connected to the molar tubes
286
Q

What is the facemask and reverse pull headgear used for?

A

for pre-adolescent patients exhibiting maxillary deficiency

287
Q

What is the activator/headgear hybrid appliance used for?

A

for class II; holds upper jaw to allow lower jaw to come forward

288
Q

How do removable appliances for tooth movement work?

A
  • force for active tooth movement provided by finger springs- acrylic, labial bow, and molar clasps provide anchorage and appliance retention
289
Q

Which are more recommended: removable or fixed palatal expanders?

A

fixed because if a patient forgets to wear a removable one for a day or two, it will no longer fit

290
Q

What is the purpose of an anterior bite plate? A posterior bite plate?

A
  • ANTERIOR: decreases overbite (acrylic pad falls between maxillary and mandibular incisors so that the posterior teeth are able to complete eruption)- POSTERIOR: increases overbite (acrylic between the maxillary and mandibular molars allows incisors to further erupt)
291
Q

What is a Hawley retainer?

A

removable retainer with a labial bow, clasps or rests on the posterior teeth, and acrylic; allows orthodontist to make fine adjustments and allows for some acetylate (molars can move slightly to allow for proper intercuspation)

292
Q

What is the purpose of a spring retainer?

A

used for both retention and minor tooth movement

293
Q

What is the purpose of a tooth positioner? How does it work?

A
  • used for minor tooth movement and retention- positioner is fabricated on models to which the desired tooth movement has been made; used after braces when the PDL is very loose and flexible; allows PDL to stiffen in the right position
294
Q

What is the Begg appliance?

A
  • modified based on Angle’s ribbon arch- added auxillary springs for root control- compared to edgewise, wire to bracket contact is very small and the friction is minimal (teeth can be moved quickly, but hard for root control)- not commonly used anymore
295
Q

How has the modern edgewise appliances changed?

A
  • automatic rotational control (twin brackets or single brackets with wings)- bracket slot change to 0.018 and 0.022 inch slots- pre-adjusted edgewise appliance developed with built-in adjustments for each tooth so you don’t need to wire each tooth differently
296
Q

How do pre-adjusted edgewise appliances work in general? What is another name for them? Is wire bending still necessary?

A
  • Larry Andrews (OSU grad!) developed ideal angle and position for each tooth; appliance is made with ideals for each of the teeth so that a straight wire (no bends) can be inserted and the brackets do the work- “straight wire” technique- wire bending is still necessary, especially for detailing and finishing phase since “ideal” may not be exactly ideal for every patient
297
Q

How do pre-adjusted edgewise appliances modify the horizontal plane? Standard edgewise?

A
  • PRE-ADJUSTED: make the bracket base of upper lateral incisors and lower incisors thicker while the molar tube profile is shorter than adjacent bracket slots- STANDARD: 1st order bends are needed to compensate for horizontal position variations
298
Q

How do pre-adjusted edgewise appliances modify the mesial-distal angulation? Standard edgewise?

A
  • PRE-ADJUSTED: align the vertical slot with root long axis; if mesial-distal angulation of tooth needs change, the straight wire will be deflected once engaged to that tooth- STANDARD: 2nd order bends are needed to change mesial-distal angulation
299
Q

How do pre-adjusted edgewise appliances modify the torque? Standard edgewise?

A
  • PRE-ADJUSTED: varying the slot-bracket angle or differentially changing the bracket base thickness- STANDARD: 3rd order or torque bends needed
300
Q

What are the 4 typical components of modern edgewise appliances?

A
  • bands with molar tubes- brackets- archwires- auxillaries (elastomeric chains, coil springs, lingual arches, transpalatal bars, extra-oral appliances, temporary anchorage devices, etc.)
301
Q

What is the difference between direct and indirect bonding of brackets?

A
  • DIRECT: glue each bracket individually onto the tooth- INDIRECT: place brackets in pre-made matrix and glue on all at once
302
Q

How are arches tied to brackets?

A

elastic and stainless steel ties

303
Q

What is the purpose of power chains? Of elastics?

A
  • POWERCHAINS: space closure- ELASTICS: improving occlusion, moving impacted teeth, shift midlines, etc.
304
Q

What are open coil springs used for? Closed coil springs?

A
  • OPEN: for opening space, retracting teeth- CLOSED: for maintaining space
305
Q

What are the 3 examples of fixed appliances for Class II correction?

A
  • Herbst- MARA- Forsus
306
Q

What are the 3 advantages of fixed appliances for Class II correction?

A
  • patient compliance not required- larger dental movement than elastics- Herbst and MARA may potentially have skeletal growth modification effects
307
Q

What are the Jasper Jumper and Lip Bumper used for?

A
  • Jasper Jumper: class II correction- lip bumper: arch expansion, molar distalization and incisor proclination
308
Q

What is the Hyrax appliance used for? The lower arch expander?

A
  • Hyrax: palatal expansion; dental and skeletal- lower arch expander: dental only
309
Q

What types of patients are the quad helix with finger springs and the W arch used in? What do they do? What type of archwire is used?

A
  • preferred for pre-adolescent and early mixed dentition patients- expansion appliances; helices are used for activation and increase the range of tooth movement- heavy stainless steel
310
Q

What is a transpalatal arch and lingual holding arch used for? What type of archwire is used?

A
  • used for anchorage and space maintenance purposes- heavier (0.036 or above) stainless steel than regular archwires
311
Q

What is the pendulum appliance used for? How does it work?

A
  • for molar distalization (kicks them back like a frog)- bonded to premolars; TMA wires with helices inserted to molar tubes; anchorage from palate; primarily molar movement with some movement of the anterior teeth as well
312
Q

What is a tongue crib used for? What type of wire is it made out of? Where is it anchored?

A
  • for correcting tongue or finger habit- heavy stainless steel wire- anchored on molars
313
Q

What are the 3 recent developments of fixed appliances?

A
  • lingual braces- clear (ceramic) braces- self-ligating brackets
314
Q

What is the difference between removable and fixed appliances in terms of type of movement of teeth and roots?

A
  • REMOVABLE: mostly produces tooth tipping; no control over root movement- FIXED: can produce bodily tooth movement and tipping; better control of root movement
315
Q

What is the difference between removable and fixed appliances in terms of patient’s compliance and hygiene?

A
  • REMOVABLE: patient’s compliance required; more hygienic- FIXED: less dependent on patient’s compliance; less hygienic

AU14 - Ortho Exam1 (1 decks)

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