First Semester Flashcards
What is the difference between the primary and secondary palate, and how do they form embyologically? Discuss which branchial arch they come from and the cartilage areas in them.
Primary palate is derived from the 1st pharyngeal arch. It forms at weeks 4-5 by the fusion of the medionasal and frontonasal processes.
Secondary palate is fusion of maxillary process shelves at 7-8 weeks.
Derived from the first branchial arch which is part of the viscerocranium
Derived from the first pharyngeal arch and are formed from intramembranous ossification
Primary epithelial band, odontogenic epithelium
The primary palate is derived from the ___ pharyngeal arch. It forms at weeks ___ by the fusion of the __ and ___ processes.
First
4-5
Medionasal and Frontonasal
The secondary palate forms at ___ weeks by the fusion of the ___.
7-8 weeks
Maxillary process shelves
The primary and secondary palate is derived from the ___ pharyngeal arch and are formed by ___ ossification
First
Intramembranous
From which branchial arch does the mandible grow from and how does the cartilage form in the mandible?
The mandible is derived from the first pharyngeal arch, specifically Meckel’s cartilage. Intramembranous ossification occurs lateral to Meckel’s cartilage and starts at the incisive or mental branches of the IAN
In regards to the cranial base, the basicranium is the template for…
The face. It helps establish the shape and perimeter of the face.
How does the calvaria and cranial base grow?
As the brain expands, the separate bones of the calvaria are correspondingly displaced in an outward direction
Primary displacement causes tension in the sutural membranes -> depositing new bone on sutural edge and enlarging in circumference
During growth, the bones of the calvaria become flatter
The calvaria is resorptive on the cranial floor and depository on endosteal surface
Cranial base is primarily resorptive on cranial floor (fossa). A/P growth occurs via growth and synchondroses
During growth, the bones of the calvaria become ___
Flatter
The cranial floor is [resorptive/depository], whereas the endocranial surface of the calvaria is predominantly [resorptive/depository].
Resorptive
Depository
What is the spheno-occipital synchondrosis and its importance?
The spheno-occipital syncondrosis provides elongation of the midline of the cranial floor (IE allows the cranial floor to expand with the brain).
It is the principle growth cartilage
Define cranial base growth spurt for both boys and girls
Rate of growth of the cranial base exceeding that in the preceding annual interval by at least 0.75mm for boys and 0.5mm for girls
When do the cranial base growth spurts occur for boys and girls?
Female: 11.6yo
Male: 13.2yo
Occurs 1.6 years earlier in females. Mandibular spurt occurs at the same time
How can orthodontics affect cranial base growth?
It has no effect
What is the importance of the cranial base in growth and how does it grow differently in class 1 and class 2 skeletal patterns?
Cranial base is important in growth in that it provides a template for the face. However, it does not grow much differently in class 1 or class 2 skeletal patterns.
What are the 3 evolutionary growth theories and the names associated with them? Where did the theories place the emphasis on growth control (which tissues)?
Genetic blueprint theory - genes control everything
Nasal septum theory - nasal cartilage (cartilage is pressure tolerant and thought capable of driving the maxilla downward and forward).
Functional matrix - genic and epigenetic tissues. Stimuli from growth and function
Discuss the functional matrix theory of growth in the format of what has been added with the most recent research as well as its general premise, genetics and environment.
Can be summarized as “form follows function”, but on a much deeper level, it goes beyond soft tissues driving form. Rather, it is an interplay between genetics (which provide the building blocks) and epigenetics (environment) to provide a phenotype.
General premise: not just soft tissues. Periosteal matrix = muscle and bone. Capsular matrix = neurocranial capsule and orofacial capsule
Genetics and environment: genomic and epigenetic factors are both necessary causes. Neither is sufficient alone, as causative factors
In regards to mandibular And maxillary growth, what are the clinical targets in growing people?
Mandible targets = ramus, condyle, alveolar process
Maxilla targets = Maxillary tuberosity, sutures, alveolar process
The ramus remodels in a ___ manner. It is resorptive at the __ border and depository at the ___ border. The ___ is its counterpart. It [can/cannot] be affected orthodontically.
Anterior/posterior
Anterior
Posterior
Middle cranial fossa
Cannot
The condyle requires ___ growth, yet it is __, ___, and grows in the direction of ___. How well is it affected orthodontically?
Endochondral
Adaptive, multidirectional, articulation
This is the site of growth in the mandible that we can affect most with orthodontic treatment albeit limited (Class 2 and class 3 correctors)
The lingual tuberosity grows in a __ direction but is augmented by ___ fields of the lingual fossa. How well is it affected orthodontically?
Posterior
Resorptive
Cannot be affected orthodontically
Which part of the mandible (besides the alveolar process) can be affected the most with orthodontic treatment?
The Condyle. Although orthodontic treatment has a very limited affect on growth of the condyle
Growth of the maxillary tuberosity causes ____. How can orthodontics affect growth here?
Horizontal lengthening of maxilla (deposition)
Nothing we can do to affect/create more bone (IE cant move teeth into tuberosity and expect to make more bone; the bone has to already be there)
Describe the relationship between growth and sutures in the maxilla.
Theory is that downward and forward growth of the maxilla is caused by tension placed in the sutures. Tension can be created/increased orthodontically with RPE, Headgear, Facemask
Describe the growth that occurs in the alveolar process. How can orthodontics affect this?
Vertical drift occurs here
We readily manipulate the alveolus with all sort of appliances including the straight wire appliance
How does the lingual tuberosity form during growth?
Equivalent of maxillary tuberosity
Growth straight distal with slight lateral shift
Allows maxillary and mandibular posteriors to stay in contact.
What are the major concepts in mandibular growth? Which way does it grow? Limits, borders, and maintenance of homeostasis.
A/P: Remodels and is displaced in a downward and forward fashion. Technically grows up and back to maintain articulation with glenoid fossa. Ramus remodeling.
Transverse: Established/limited by middle cranial fossa. Follows “V” principle.
Vertical: Uprighting of ramus during growth
Explain how neuromuscular development is associated with growth and development and its effect on orthodontic treatment.
Neuromuscular development follows an antero-posterior gradient (IE lips to posterior tongue) Infantile swallow (may be maintained and thus need to be addressed) to mature swallow Maintenance of airway, infant cry, gagging, mastication, neural regulation of jaw positions Neuromuscular mechanisms and bone growth factors are far more important in nature of occlusal relationships than cuspal height/inclination or condylar guidance. Teeth must change continually to adapt to growth and neuromuscular changes.
Does malocclusion affect neuromuscular functioning? How? Name some examples.
Malocclusion affects neuromuscular functioning in cases of crossbite
Throckmorton study: pts with unilateral crossbite had longer chewing cycle on crossbite side and path was more deviated. Treatment to correct crossbite helped chewing cycle approach that of controls
What are the three head/facial forms?
Dolichocephalic (leptoprosopic)
Brachycephalic (euryprosopic)
Dineric
Describe the dolichocephalic face type and how they grow differently. How does this affect our orthodontic treatment?
Long/narrow face, retrognathic, convex facial profile, eyes deep set, aquiline nose
Grow vertically
Worried about opening these pts up because our mechanics have an extrusive nature
Describe the brachycephalic face type. How do they grow? How does this affect our orthodontic treatment?
Short/wide face, prominent chin, straight/concave profile, eyes bulging
Grow horizontally
Try to open these pts up, but have to fight against strong musculature
Describe the dineric face type.
Technically brachycephalic with leptoprosopic facial form
Long face and large nose
Ears appear closer to back of head because of cranial flattening (Cradling)
Mesocephalic-intermediate form
Describe the changes that occur in normal-growing dolichocephalic individuals.
More anteriorly inclined middle cranial fossa (obtuse angle)
Longer and more narrow anterior cranial fossa
Steeper mandibular plane/clockwise rotation of the mandible
Prominent nose, deep set eyes
Describe the growth studies associated with dolichocephaly
Nanda 1988 - dolies eyes grow more vertically, tend to have larger values for LAFH and shorter posterior face heights. Pts have a propensity for anterior open bite
Chung 2003 - growth pattern remains the same (If growing dolie, will continue to grow dolie)
Cangialosi 1984 - LAFH greater than UAFH (agrees with Nanda)
Describe the changes that occur in normal-growing brachy individuals. Describe the growth studies associated with them.
More posteriorly inclined middle cranial fossa (acute angle)
Wider and shorter anterior cranial fossa
Flatter mandibular plane/counter-clockwise rotation
Bulbous forehead, eyes appear more bulging
Nanda 1988 - deep bite pts (brachy) tend to have more UAFH
Chung 2003 - growth pattern remains the same
Why types of malocclusion tend to have orthognathic facial profiles?
Class 1 malocclusion
Class 2 div 2
Which malocclusions are typically the cause of prognathic facial profile?
Class 3 malocclusions.
Headform: brachycephalic more likely
Facial topography: short, round fat heads, protrusive mandible, concave profile
What type of malocclusion is the most likely cause of a retrognathic profile?
Class 2 div 1
Headform: dolicocephalic more likely
Facial topography: long narrow face, recursive mandible, convex profile.
There may be build in ___ features during growth, which can compensate for and help offset abnormal growth tendencies thereby produces a ___ occlusion. If the compensatory features are inadequate, ___ exists, but is generally [less/more] severe than than the abnormal tendencies might have otherwise produced if unchecked.
Compensatory
Class 1
Malocclusion
Less
Dolichofacial patients are associated with ___ bites. Brachyfacial patients are associated with __ bites.
Open
Deep
Dolichofacial pts are associated with a ___ airway while brachyfacial pts are associated with a ___ airway.
narrow
Wider
Why do malocclusions occur in each headform, dolichofacial or brachy?
Malocclusions form as a result of inadequate compensatory growth. For example, in a dolichofacial, LAFH tends to be longer than normal. To prevent an anterior openbite, posterior face height needs to keep pace, which does not happen in some cases. For a brachyfacial, the opposite can be seen; UAFH tends to be greater and LAFH does not keep pace resulting in a deep bite situation
In class 2 div 1, the lower incisors are [flared/steep]
Flared forward
In class 2 div 2, the lower incisors are [flared/steep]
Steep
In a dolichofacial patient, they have a ___ facial profile, a ___ mandible and lower lip, a ____ nose, and soft tissue tends to be ___
Convex
Retrognathic
Prominent
Thicker in a long vertical pattern
In a brachy patient, they tend to have a ___ facial profile, a __ chin, a ___ nose, and soft tissue thickness tends to be…
Straight to concave
Prominent
Less protrusive
Thinner in short facial pattern
What are the boundaries of the mandible and how are they anatomically defined?
Transverse boundary - middle cranial fossa
A/P - ramus (middle cranial fossa) and lingual tuberosity. Corpus of mandible should lie anterior to posterior maxillary plane
Vertical - condyle, ramus
What are the boundaries of the maxilla and how are they anatomically defined?
Transverse - anterior cranial fossa. Maxillary tuberosity
A/P - forward boundary is the brain. For the nasomaxillary complex - cribriform plates. Posterior boundary - posterior maxillary plane (at junction of middle and anterior cranial fossae). Maxillary tuberosity
Vertical - orientation of olfactory bulbs have an influence on how the nasomaxillary complex is oriented
According to longitudinal studies, with growth nose height ___, nose length ___, upper lip length ___, upper lip thickness ___, Lower lip length ___, lower lip thickness ___, nasolabial angle ___, chin ___
Nose height increases (more in boys)
Nose length grows equally
Upper lip length increases (more in boys)
Upper lip thickness decreases with age (according to Sarver), slightly increases (according to Prahl)
Lower lip length increases
Lower lip thickness decreases with age (Sarver), slightly increases (Prahl)
Chin increases in thickness with age
According to Bishara 1998, how does the overbite change from 5-45 yo?
Overbite: pretty stable once permanent teeth erupt. Difficult to predict the final overbite in a child (deciduous dentition). If little overbite to start then maintained in later stages of development
How does anterior face height change from 5-45yo?
Change early on more significant, get vertical change in N-ANS, N-Me throughout life
How does posterior face height change from ages 5-45?
Males>females, Ar-Go, S-Go, growth more significant early on, continuous until mid 20s
How does the relationship of AP face height change from 5-45yo?
MPA flattens with age. Small amount of vertical growth occurring in the face (N-ANS, N-Me, Ar-Go, S-Go)
What are the conclusions drawn regarding change in arch length from birth to 45yo from the Bishara study?
The greatest incremental increases in Mx and Mn arch length occur during the first two years of life
Arch length continues to increase until 13 years in the Mx arch and 8 years in the Mn arch
Following these ages, significant decreases in arch length occurred until 45 years of age. As a result, the decreases in arch length is translated as an increase in the tooth size-arch length discrepancy, unless interproximal attrition keeps pace with the decrease in arch lengths
According to the Bishara paper, how does arch width change from birth to 45yo?
Mx and Mn intercanine width increased between 3-13 years of age in both male and female subjects. After that age, it decreased and continued to do so until age 45 years in both males and females.
Intercanine and intermolar widths significantly increased between 3-13 years of age in both the Mx and Mn arches. After the complete eruption of the permanent dentition, there was a slight decrease in the dental arch widths, more in the intercanine than in the intermolar widths
Mn intercanine width, on average, was established by 8 years of age (after the eruption of the four incisors). After the eruption of the permanent dentition, the clinician should either expect no changes or a minimal decrease in arch widths
According to the Moore’s paper, how does intercanine width change with age?
The main growth phase occurred in both sexes during the incisor transition and levels off after full eruption of the lateral incisors. In the Mx, a second increase in arch breadth was noted after the emergence of the permanent canines, but this increase did not occur in the Mn.
The changes in the intercanine distances are explained by growth of the alveolar processes in the incisor region. Additionally, the changes in arch length in the maturing dentition are also a function of mesial migration of the posterior teeth.
What are the characteristics of the ugly duckling stage? What age does it occur?
4-12years
Diastema between upper incisors
Maligned lateral incisors
Large, protrusive upper incisors
Crowding in the lower incisors
Decreased available space maximum space lost/maximum crowding at this point. Normal on lower, some spacing on upper and will take a couple years to resolve
Describe the arch size/ alveolar growth increase from ages 4-12
Maxilla - slightly, between 8-10 years (after eruption of 2s) (females before males)
Mandible - significant; between 8-9yo males, 7-8 females (after eruption of 2s)
Decreased crowding or increased spacing again
Maxilla becomes slightly more spaced (especially in males) mandible remains slightly crowded but improves (especially in females)
Males have better recovery than females
Changes in arch dimensions (spacing and crowding) seem to be triggered by…
Eruption of permanent teeth
According to the Baume study - unable to accurately predict outcome of development based on ____
Deciduous dentition spacing/crowding
~___% of pts with no primary spacing resulted with normal outcomes
57% (9/16)
It is normal to have buck teeth in mixed dentition. There is typically space in upper incisors and crowded lower incisors (2-4mm). How long does this take to resolve?
About 2 years
What is incisor liability?
Permanent incisors are larger than primary incisors
Maxillary - just enough space to accomodate for larger permanent incisors
Mandible - shortage of space by 1.6 - 2mm
How is incisor liability compensated?
Resolved by widening of canines, facial eruption of maxillary incisors, and leeway space
How can early loss of deciduous teeth negatively affect incisor crowding?
Leeway space creates additional space for crowded lower incisors, if this space is lost you will have more crowded lower incisor.
True or false… there is a slight decrease in arch length upon emergence of the 6s
True
There is a small increase in arch length with eruption of the permanent incisors in the ___ arch, but negligible in the ___ arch
Maxillary
Mandibular
True or false… there is an arch length decrease after shedding of deciduous molars (especially 2nd molars)
True, especially on the lower arch
According to Bork, what are the three most stable superimposition points for the mandible during growth?
Mandibular canal
Internal symphysis
And third molar tooth germ
Failure of migration of the ____ causes treacher Collins syndrome
Neural crest cells
What bones are associated with the first branchial arch? How are they formed?
Intramembranous ossification
Premaxilla Maxilla Zygomatic bone Part of temporal bone Mandible Ossicles
What muscles are associated with the first branchial arch?
Temporalis Masseter Pterygoids Anterior belly of digastric Mylohyoid Tensor tympani Tensor palatini
What nerve(s) are associated with the first branchial arch?
Trigeminal (CN5) - forms maxillary and mandibular process (V2 and V3)
