Craniofacial Growth, Developing Dentition and Occlusion Flashcards
fPeriod of the ovum
- Day 0 to 10-14
- Fertilization to implantation
- Cell division (proliferation)
Period of the embryo
- Week 2 to 8
- Remainder of 1st trimester
- Cell differentiation
Period of the fetus
- Week 8 to 40
- 2nd and 3rd trimester
- Maturation of organ systems
Branchial arch structure
Cartilage, a nerve, and blood vessels surrounded by mesenchyme
Palate formation
- Initially palatal shelves grow vertically on either side of the developing tongue
- Palatal shelf elevation occurs rapidly bringing the shelves into proximity
- Fusion of the shelves to each other and to the nasal septum follows
Definition of growth
- an increase in size or number
- anatomical phenomenon
Definition of development
- an increasing degree of organization, complexity, and specialization
- physiological and behavioral phenomenon
Hypertrophy
Increase in size
Hyperplasia
Increase in number
Interstitial growth
- Occurs throughout the tissue
- Soft tissues
- Uncalcified cartilage
Appositional growth
- Occurs only on the surface of the tissue
- Hard tissues
- Calcified tissues
Growth of cartilage
- Grows by appositional and interstitial growth
- Appositional growth: new cartilage is added to the surface of the cartilage by chondroblasts from the inner layer of the perichondrium
- Interstitial growth: new cartilage is formed within the cartilage by chondrocytes that divide and produce additional matrix
Intramembranous
- No structural precursor
- Secretion of bone matrix directly within connective tissues
- Cranial vault, maxilla, mandible
Appositional
- Cartilaginous precursor
- Replacement of cartilage with centers of ossification
- Axial and appendicular skeleton, cranial base
AKA endochondral ossification? Needing a cartilage precursor
Condylar cartilage
- Arises independently as secondary cartilage
- Initially separated from the body of the mandible, but eventually fuses in fetal life
** Both endochondral and intramembranous ossification contribute to the origin of the mandible **
Craniofacial complex
1) Cranial vault
2) Cranial base
3) Nasomaxillary
4) Mandible
Differential growth patterns
- Neural is the majority at first, then plateaus
- Lymphoid tissue increases then decreases
- Mandible follows the general curve
Cranial vault
- Intramembranous, no interstitial growth
- Anterior fontanelle, mastoid fontanelle, sphenoid fontanelle, posterior fontanelle
Cranial base
- Endochondral growh
- Frontal bone, sphenoid bone, temporal bone, occipital bone
Maxilla
- Intramembranous
- Sutures connects the maxilla to the rest of the cranium
- Apposition occurs upward and backward, however, it results in downward and forward net effect.
Maxillary growth
- Apposition of the bone at the sutures –> displaces maxilla downward and forward
- Apposition of bone at the maxillary tuberosity –> increases arch depth
- Resorption at anterior surface of maxilla –> maintains position of anterior surface
Mandible
Mix of both intramembranous and endochondral
Mandibular growth
- Endochondral growth at the condyle –> displaces mandible downward and forward
- Apposition at posterior border, resorption at anterior border of ramus –> relocates ramus posteriorly, displaces mandible downward and forward
Primary germ layers
- Ectoderm –> Epidermis (skin), oral mucosa, enamel
- Mesoderm –> Skeletal muscle
- Endoderm –> Lining of the gut (pharynx)
- Neural crest –> Connective tissue proper, cartilage, bone, dentin, cementum, pulp, PDL
___ is from the ectoderm, while the rest of the dental tissues comes from the ____
Enamel; neural crest
Stages of tooth development
A) Bud
B) Cap
C) Bell
D) Dentinogenesis
E) Amelogenesis
F) Crown formation
G) Root formation and eruption
H) Root completion
Root formation timeline
Root formation begins BEFORE eruption, but finishes 2-3 years AFTER
Life cycle of the tooth
1) Growth
- Initiation
- Proliferation
- Histodifferentiation
- Morphodifferentiation
- Apposition
2) Calcification
3) Eruption
4) Attrition
Stage of tooth development: Initiation
Initial formation of the bud
Stage of tooth development: Proliferation
Proliferation of the cells of the bud to proceed through the cap stage
Stage of tooth development: Histodifferentiation
Differentiation of the cells of the tooth germ into inner and outer epithelium and dental papilla (bell)
Stage of tooth development: Morphodifferentiation
Tooth germ begins to take on the morphology of the tooth (advanced bell)
Stage of tooth development: Apposition
Tissue matrix is deposited
Tooth germ composition
- Enamel organ –> from the ectoderm, surrounded by ectomesenchyme forming the dental sac and papilla
- Dental papilla
- Dental sac
Dental papilla becomes?
Dentin and pulp
Dental sac becomes?
PDL and cementum
Enamel organ
- Differentiates into 4 layers: outer enamel epithelium (OEE), inner enamel epithelium (IEE), stellate reticulum, stratum intermedium
- IEE becomes ameloblasts that produce enamel
- Stellate reticulum and stratum intermedium are the supporting structures for the IEE
Histodifferentiation and apposition
- Odontoblasts are signaled by preameloblasts to make predentin – beginning the first dentin at the DEJ
- Preameloblasts differentiate into mature ameloblasts when stimulated by dentin laid down by odontoblasts
Basement membrane or basal lamina
- Microscopic interface between epithelial and mesenchymal tissues
- Product of both tissues
- Mediator of molecular signaling that controls differentiation
- Becomes the dentino-enamel junction
Root formation
- Begins towards the end of crown formation, and will not complete until 2-3 years after tooth eruption
- Outer enamel epithelium + inner enamel epithelium = Hertwig’s epithelial root sheath –> function is to GUIDE the SHAPE and NUMBER of roots
Cementogenesis
- Breakup of hertwig’s epithelial root sheath allows cells of dental sac to contact root dentin and differentiate into cementoblasts.
- These cells produce cemented which mineralizes to form cementum.
- The root sheath thus directs the cementoblasts where to go.
PDL and tooth eruption
- Root formation is not complete until 2-3 years after eruption
- Cementum of the root is connected to the alveolar bone via connective fibers called the Periodontal Ligament (PDL)
- As the tooth erupts –> more and more PDL will form
Three phases of tooth eruption
1) Preeruptive –> root formation begins and tooth is moving toward bony surface
2) Eruptive (prefunctional) –> development of tooth root through gingival emergence; most roots are 1/2 to 2/3 developed upon gingival emergence
3) Eruptive (functional) –> From gingival emergence to the point where the tooth meets its antagonist
Developmental events of dentition
- Primary dentition stage (6 months to 6 years) –> first inter-transitional period
- Mixed dentition stage (6 to 12 years)
- First transitional period
- Second inter-transitional period –> ugly ducking stage
- Second transitional period
- Permanent dentition stage (12 years to adult)
Eruption of primary teeth
Maxillary:
Central (10 mo) –> Lateral (11 mo) –> First molar (16 mo) –> Canine (19 mo) –> Second molar (29 mo)
Mandibular:
Central (8 mo) –> Lateral (13 mo) –> First molar (16 mo) –> Canine (20 mo) –> Second molar (27 mo)
General features of the primary dentition
- Developmental spacing
- Flush terminal plane molar relationship
- Dental arches ovoid in shape
- Deep bite present initially that changes to edge-to-edge
- Flat curve of spee
Developmental spacing
- Maxillary spacing – 70% of children
- Mandibular spacing - 63% of children
**Primary dentition without spacing will be followed by crowding of the permanent dentition in 40% of children
** Baume type 1: spacing
** Baume type 2: no spacing
Primate space
Maxillary: between lateral incisors and canine
Mandibule: between canine and first primary molar
Primary molar relationship
Flush terminal plane –> 76% of children (distal of maxillary primary second molar flush with distal of mandibular primary second molar)
Mesial step –> 14% of children
Distal step –> 10% of children
Early mesial shift
- Closing of interdental space between primary molars prior to eruption of first permanent molars
- Affects mandibular primate space
- Convert flush terminal plane to mesial step
- Approximately age 4
First inter-transitional period (primary dentition)
- The period between the completion of the primary dentition and the emergence of the first permanent tooth
- Vertical skeletal growth
- Deepening of the bite due to attrition of the primary incisors
Orthodontic implications of first inter-transitional period (primary dentition)
- Close/non-spaced dentitions have increased risk of crowding
- Distal step molar relationship should be evaluated for class II malocclusion
- Mesial step molar relationship should be monitored for the development of class III malocclusion
- Closed/non-spaced dentitions have a decreased probability of converting to class I molar relationship if initially distal step or flush terminal plane
Eruption sequence of permanent dentition
Maxillary: First molar (6-7 years) –> central (7-8 years) –> lateral (8-9 years) –> first premolar (10-11 years) –> second premolar (10-12 years) –> canine (11-12 years) –> second molar (12-13 years)
Mandibular: First molar (6-7 years) –> central (6-7 years) –> lateral (7-8 years) –> canine (9-10 years) –> first premolar (10-12 years) –> second premolar (11-12 years) –> second molar (11-13 years)
First transitional period (mixed dentition)
- From ages 6-8 years
- Eruption of first permanent molars
- Replacement of incisors
Incisor liability
- Permanent incisors are larger than primary incisors
- 7.6 mm in maxilla
- 6 mm in mandible
Compensation for incisor liability
- Interdental spacing in primary dentition –> maxillary primate space
- Labial eruption of permanent incisors –> Increased proclination of permanent incisors
- Increased intercanine width –> 4mm in maxilla, 2-3mm in mandible
Orthodontic implications of first transitional period (mixed dentition)
- “Shark teeth”
- Lingually erupting mandibular incisors –> 10-20% prevalence
- Closed primary dentition
Second inter-transitional period (mixed dentition)
- From age 8 to 9 or 10 years
- From the complete eruption of incisors until the beginning of replacement of primary canines and molars
- Maxillary arch –> 1) “ugly duckling” stage, 2) diastema, 3) loss of primate space, 4) excess overjet
- Mandibular arch –> 1) transitional crowding, 2) loss of primate space
- Vertical skeletal growth
- Bone remodeling in maxillary tuberosity and mandibular ramus
- Development of maxillary canines
Orthodontic implications of second inter-transitional period (mixed dentition)
- Mild mandibular crowding (<2mm) can resolve spontaneously
- Maxillary diastema has a high likelihood of resolving spontaneously –> wait until maxillary canines erupt to reassess
Second transitional phase (mixed dentition)
- Occurs between 10-12 years of age
- Replacement of primary canines and molars
- Leeway space
- Late mesial shift
- Closure of maxillary diastema
Leeway Space
Difference in the mesiodistal dimension between primary canine and molars and permanent canines and premolars
Average values for leeway space
Maxillary leeway space
- 2.2 mm (Bishara)
- 1.8 mm (Nance)
Mandibular leeway space
- 4.8 mm (Bishara)
- 3.4 mm (Nance)
Late mesial shift
** Late mesial shift = Leeway space
- Mesial movement of first permanent molars after exfoliation of the primary molars
- Closure of the leeway space
Late mesial shift and arch length
Maxilla: arch length greatest in mixed dentition (8-10 years), then decreases
Mandible: arch length greatest before early mesial shift (age 4 then continues to drop off
**Arch length decreases 2-3 mm
Closure of maxillary diastema
Arch length greatest before early mesial shift (age 4) then continues to drop off
Orthodontic implications of second transitional phase (mixed dentition)
- Leeway space may be used to address incisor liability
- Late mesial shift can help transition to a class I molar relationship from end on
- Maxillary diastema should be reassessed once permanent canines have erupted
- Moderate to severely crowded mixed dentition cases will have a lower likelihood of transitioning from class I molar relationship from class II
Permanent dentition
- From age 12 to adulthood
- Onset of adolescent growth spurt
- Finalization of molar relationship
Transverse dimension and adolescent growth spurt
Completed prior to growth spurt
Vertical dimension and adolescent growth spurt
Continues beyond growth spurt
Anterior-posterior dimension and adolescent growth spurt
Continues throughout growth spurt
Adolescent growth spurt additional changes
- Profile changes occur as changes in specific locations take place
- Frontal bone, brow, nose, and chin becomes more prominent
- Continued lowering of the palatal vault
- Vertical maxillary growth is often greater in females
Context of adolescent growth spurt
Modifying growth of the craniofacial structures might help to address malocclusion of skeletal origin
Implications of growth spurt
- Skeletal malocclusion
- Timing of growth modification
- Timing of surgery
- Dental interventions
- Timing of implant placement
Mandible and growth spurt
- Mandible demonstrates a pubertal growth peak
- Allows for additional change in molar relationship
Distal step can develop into
- Class II
- End to End
Flush terminal plane can develop into
- Class I
- End to end
Mesial step can develop into
- Class I
- Class III
How do we know when the growth peak will occur?
Developmental age –> biological age –> morphologic, skeletal, dental, circumpubertal
Somatotypic age
- Ectomorph
- Mesomorph
- Endomorph
Maturation: endomorph -> mesomorph -> ectomorph; no prediction in timing of growth spurt?
Height and weight and growth spurt
- Absolute height and weight not accurate predictors
Height velocity/growth peak
Prepubertal growth peak –> age 6-7
Pubertal growth peak –>
- Age 11.5 in females
- Age 14.5 in males
Dental age and developmental age
- Dental age generally does not correlate well with developmental age
- Variation in timing of eruption
Stages of canine calcification (compared to hand wrist radiograph)
D –> E –> F –> G –> H
Stage D of canine calcification
- Crown formation is completed down to the cemento-enamel junction
- The superior border of the pulp chamber in the uniradicular tooth has definite curved form, being concave towards the cervical region. The projection of the pulp horns, if present, given an outline shaped like an umbrella top.
- Beginning of root formation is seen in the form of a spicule.
Stage E of canine calcification
- The walls of the pulp chamber now form straight lines whose continuity is broken by the presence of the pulp horn, which is larger than the previous stage.
- The root length is less than the crown height.
Stage F of canine calcification
- The walls of the pulp chamber now form a more or less isosceles triangle. The apex ends in a funnel shape.
- The root length is equal to or greater than the crown height.
Stage G of canine calcification
The walls of the root canal are now parallel and its apical end is still partially open
Stage H of canine calcification
- The apical end of the root canal is completely closed.
- The periodontal membrane has a uniform width around the root and the apex.
Skeletal age
More highly correlated with menarche than height, weight, or growth velocity
Hand wrist radiographic evaluation techniques
- Tanner and Whitehouse method
- Bjork, Grave, and Brown method
Stage 1 of Bjork, Grave, and Brown method
3 years before pubertal growth spurt
Stage 4 of Bjork, Grave and Brown method
Beginning of pubertal growth spurt
Stage 5 of Bjork, Grave, and Brown method
Peak of pubertal growth spurt
Stage 6 of Bjork, Grave, and Brown method
End of pubertal growth
Cervical vertebrae maturation stage 1 (McNamara, Franci, Bacetti)
Peak mandibular growth will occur 2 years ager this stage
Cervical vertebrae maturation stage 2 (McNamara, Franci, Bacetti)
- Peak mandibular growth will occur 1 years after this stage
- Early class III treatment with facemask should take place before this stage
Cervical vertebrae maturation stage 3 (McNamara, Franci, Bacetti)
- Peak mandibular growth will occur within 1 year of this stage
- Early class II treatment with functional appliances should take place at this stage
- Treatment of vertical malocclusion also
Cervical vertebrae maturation stage 4 (McNamara, Franci, Bacetti)
Peak mandibular growth has occurred 1-2 years prior to this stage
Cervical vertebrae maturation stage 5 (McNamara, Franci, Bacetti)
Peka mandibular growth has ended 1 year prior to this stage
Cervical vertebrae maturation stage 6 (McNamara, Franci, Bacetti)
Peak mandibular growth has ended 2 years prior to this stage
Arch length changes
- Early mesial shift decreases arch perimeter
- Eruption of incisors results in crowding
- Labial eruption of maxillary incisors can increase arch perimeter
- Leeway space can allow for relief of crowding
- Late mesial shift decreases arch perimeter
Anterior posterior changes
Distal step –> develops into class II
Flush terminal plane –> converts to class I (56%), class II (44%)
Mesial step (>2 mm) –> converts to class I (68%), converts to class II (13%), converts to class III (19%)
*** Class I - 61.6%
*** Class II - 34.3%
*** Class III - 4.1%
Transverse changes
Intercanine width is complete:
- Mandible –> 9-10 years; earlier for girls than for boys
- Maxilla –> 12 years in girls, 18 years in boys
Favorable eruption sequence
Maxilla: 6, 1, 2, 4, 5, 3, 7 (Canine near to last)
Mandible: 6, 1, 2, 3, 4, 5, 7
Planes of Space
- Anterior posterior
- Vertical
- Transverse
- Alignment
AP dimension
- Angle classification of molars, canines, incisors
- Overjet –> anterior crossbite
- Incisor angulation
- Anteroposterior incisor portion
Class I malocclusion
Molars normal, but malposed teeth
Class II malocclusion
Lower molar distally positioned relative to the upper
Class III malocclusion
Lower molar mesially positioned relative to the upper
Overjet definition
Horizontal overlap of incisors measured from labial surface of lower incisor to Invisalign tip of upper incisor
Overjet values
- Normal = 2-3mm
- Larger than normal OJ
- Negative OJ
- End on incisors when OJ = 0
Class II Incisor Divisons
- Division 1: Flared incisors
- Division 2: Retroclined incisors
* -trusive refers to position
* -clined refers to angulation
Vertical measurements
- Overbite
- Incisor display
- Gingival display
- Curve of spee
- Occlusal cant
Overbite definition
Vertical overlap of the incisors
Measurements for Overbite
- Normal is 1-2mm or 20-30%
- Excessive OB = deep bite, possibly with palatal impingement
- No overbite = open bite
Transverse (items to consider)
- Midlines
- Posterior crossbite
- Arch width
- Arch symmetry
- Curve of Wilson
Alignment (items to consider)
- Crowding/arch length deficiency
- Missing teeth
- Supernumerary teeth
- Impacted teeth
- Transposed teeth
- Ankylosed teeth
- Diastema
- Bolton analysis/tooth size discrepancy
Crowding/arch length deficiency
Space analysis: comparison between the amount of space available and the amount of space required
Steps of space analysis
Step 1: measure available space by dividing the arch into segments that can be measured as straight lines
Step 2: calculate the amount of space required for the alignment of teeth; measure MD width of each tooth from contact point to contact point
Mixed dentition analysis
- Not necessary in the primary dentition
- Useful in the mixed dentition
- Should have permanent incisors and molars
Direct measurement (mixed dentition analysis)
- Measure unerupted teeth on radiographs
- Account for magnification errors
(True width of primary molar/apparent width of primary molar) = (True width of unerupted premolar/apparent width of unerupted premolar)
**Compare space required with space available**
Tanaka and Johnston Method (mixed dentition analysis)
- Mandibular incisors must be erupted
- Predicts underused permanent canines and premolars
**one half the mesiodistal width of the four lower incisors + 10.5mm = estimated width of Mandibular canine and premolars (one quadrant)
**one half the mesiodistal width of the four lower incisors + 11.0mm = estimated width of maxillary canine and premolars (one quadrant)
[Compare space required with space available]
Moyers prediction values (mixed dentition analysis)
- Mandibular incisors must be erupted
- Predicts underused permanent canines and premolars
- Based on a ratio of Mandibular incisor widths to canine and premolar widths
Tooth size discrepancy
- The degree of disproportion in the size of individual teeth
- About 5% of the population have some degree of tooth size discrepancy
- The most common teeth are the upper lateral incisors and 2nd premolars
- For good class I occlusion with ideal OB and OJ, teeth must be proportional in size
Bolton Analysis
Ideal ratio of the mandibular to maxillary teeth
- Sum mandibular 12/Sum maxillary 12 x 100 = 91.3
- Sum mandibular 6/sum maxillary 6 x 100 = 77.2
Cephalometric Analysis
- Used to compare the patient to a normal reference group, so that differences between the patient’s actual dentofacial relationships and those expected for his or her racial or ethnic group are revealed
- Helps diagnose if a skeletal discrepancy exists and if so, if it is due to the maxilla, mandible, or both
Different types of cephalometric analyses
- Steiner
- Ricketts
- Sassouni
- Wits
- Harvold
- McNamara
- Cohen
- Cutcliffe
- Burstone
- Jarabak
- Downs
- Bergman
Steiner Analysis
- Developed in 1950s by Cecil Steiner
- Can be considered the first modern cephalometric analysis for two reasons:
1) It displayed measurements in a way that emphasized not just the individual measurements but their interrelationship into a pattern
2) It offered specific guides for use of cephalometric measurements in treatment planning
What is the most widely used cephalometric analysis today?
Steiner Analysis
What were the ideal measurements of Steiner Analysis based off of?
Original ideal measurements were reputedly based on one Hollywood starlet
SNA
- Sella-nasion-A point
- Norm = 82 degrees
SNB
- Sella-nasion-B point
- Norm = 80 degrees
ANB
- Norm = 2 degrees
Relationship of the upper incisor to the NA line
- -clined = angulation
- -trusive = bodily position
- 1-NA (mm) norm = 4mm
- 1-NA (deg) norm = 22 deg
Relationship of the lower incisor to the NB line
- 1-NB (mm) norm = 4 mm
- 1-NB (deg) norm = 25 deg
Interincisal angle
Norm 1-1 = 131 deg
Mandibular plane to Sella-Nasion Plane
- GoGn-SN angle
- Norm = 32 deg
Dolichofacial
- GoGn-SN > 32 deg
- Steep open bite, with mandibular plane greater than 32
Brachyfacial
- GoGn-SN < 32 deg
- Deep bite, mandibular plane is less than 32
Occlusal plane to SN (angle)
• Norm = 14 deg
Treatment of skeletal problems
• The mindset:
- Skeletal solutions for skeletal problems is considered ideal
- Dental solutions for skeletal problems is considered camouflage or compromise
• Growth modification vs surgery
Treatment of skeletal problems: Maxilla
- Encourage growth in the transverse dimension
- Encourage growth in the anteroposterior dimension
- Discourage growth in the anteroposterior dimension
- Discourage growth in the vertical dimension
Treatment of skeletal problems: Mandible
- Encourage growth in the anteroposterior dimension
- Discourage growth in the anteroposterior dimension
- Discourage growth in the vertical dimension
How to encourage maxillary growth when transverse deficiency is present?
• Create tension in the mid palatal suture:
- Quad helix
- W Arch
- Banded Hyrax Expander (RPE)
- Banded Haas Type Expander (RPE)
- Schwartz Appliance
- Crozat Appliance
Encouraging maxillary growth modification in anterior-posterior dimension
- Encourage maxillary growth in the AP
- Create tension in circum-maxillary sutures
- Allow normal mandibular growth
- Retrognathic maxilla — think prior to age 10
Device for maxillary protraction
Facemask/protraction headgear
Discouraging maxillary growth in anterior-posterior dimension
- Restrain maxillary growth
- Create pressure in circum-maxillary sutures
- Allow normal mandibular growth
- Prognathic maxilla
Device to discourage maxillary growth in AP dimension
Headgear
Headgear components
• Facebow with:
- Inner bow
- Outer bow
• Neck/head strap
• Bilateral attachments
Types of headgear
• Parietal pull (direction of pull is superior)
• Cervical pull (direction of pull is inferior)
• Occipital pull
(direction of pull is in between parietal and cervical)
Encouraging mandibular growth in the anterior-posterior
- Mandibular growth modification:
• Encourage mandibular growth
• Modify the function of the mandible - Functional matrix theory (hypothesis)
Functional appliances that aid in mandibular growth modification
- Bionator
- Twin block
- Herbst
- Fixed/removable Herbst
- Banded Herbst
- SSC Herbst
- MARA - Mandibular anterior repositioning appliance
Discouraging mandibular growth in the anterior-posterior dimension
• Mandibular growth modification
- Discourage mandibular growth
- Restrain growth in the condylar cartilage and periosteum
Mandibular restraint device
Chin cup/chin cap
Factors associated with prolonged sucking habits
- Older maternal age
- Higher maternal education level
- Having no older siblings
Pacifier, thumb habit facts
- Most will quit by 3 or 4 (years?)
- Pacifier before thumb habit ceased
- Aim: Spontaneous cessation first then intervention
Pacifier habit results in?
Posterior crossbite
**among others
Digit sucking habit results in?
Excessive OJ
**among others
Timing of intervention
• Opportunity for spontaneous cessation
• Prior to eruption of permanent teeth
- Since problems arise by age 4, consider intervention by 3-4 yo
• Psychosocial health
Treatment for non-nutritive sucking
- Counseling
- Reminder therapy
- Reward system
- Adjunctive therapy
Pacifier cessation
• Earlier than digit habits
- 90% before age 5
- 100% before age 8
• Theoretically easier due to parental control
• May result in transfer of habit to digit
Lip habits
- Lip licking
- Lip sucking
- Lip biting
Tongue thrust impact
Anterior open bite
• However, epidemiological studies indicate a higher percentage of people with tongue thrust than those with open bite
Diagnosis: tongue thrust
Discriminate between:
• Passive anterior tongue posture
AND
• Active thrust on swallow
- Atypical swallow
- “Opportunistic behavior”
Treatment for tongue thrust
• Appliance therapy
- Tongue crib
• Exercises (myofunctional therapy)
- Swallowing in front of mirror
- Hold mint in roof of mouth
- Tongue clicks
Impact of mouth breathing
• Long lower face
• Maxillary constriction
• “Adenoid fancies”: AKA long face syndrome, refers to the long, open-mouthed face of children with adenoid hypertrophy
• Unreliable definition and identification of habitual mouth breathers:
- Cannot be considered causative: 1) Normal for 3-6 year old children to be lip incompetent, 2) roughly equivalent percentage of nasal and oral breathers before age 8
Treatment for mouth breathing
• Mouth breathing resulting from airway obstruction
- Medical management of airway
- Turbinectomy
- Adenoidectomy
Nail biting
- Rare in children younger than 3 to 6 years
- Suggested as a manifestation of stress
Impact and treatment for nail biting
Impact:
• No evidence of impact on occlusion
• Possible enamel fractures
Treatment:
• none recommended
Bruxism impact
- Wear of primary canines and molars — rare effect on pulp
- Muscle soreness and TMJ pain
Cause of bruxism
Localized cause:
• Occlusal interference
Systemic cause:
• Intestinal parasites
• Subclinical nutritional deficiencies
• Allergies
• Endocrine disorders
Psychological cause:
• Personality disorder
• Increased stress
Medical cause:
• Musculoskeletal disorders
• Mental retardation
Treatment for nail biting
- Identification and equilibration of occlusal interferences
- Rule out systemic problems
- Mouth guard
- Stainless steel crowns as needed
- Referral to therapist for psychological evaluation
Etiology of premature tooth loss
- Caries
- Trauma
- Ectopic eruption
- Congenital disorders
- Arch length deficiencies resulting in resorption
Problem of premature tooth loss
Early loss of primary teeth may impact the alignment of permanent teeth.
Early loss of primary incisors
• Usually due to caries or trauma
• Minimal loss of arch length
- Exceptions: very early loss, no spacing. Class II tendency, deep overbite
• Minimal impact on masticatory function
• Possible impact on speech
- Lingual-dental sounds (s, z, th)
- Especially prior to the development of speech skills
• < 2 years of age —> possible space loss
• > 2 years of age —> esthetic problem (for parents)
Early loss of canines
• Usually due to arch length deficiencies resulting in resorption by incisors
• No detectable relationship with posterior alignment
• Accompanied by lateral shift of incisors and midline shift
- If bilateral, accompanied by lingual tipping
Early loss of primary first molars
• Usually due to caries
• Canine and incisor dislocation toward the extraction site
- ~1.5 mm in mandible
• Mesial movement of primary second molar
- ~1 mm in maxilla
• Mesial eruption of maxillary first premolars
- Blocked out canines
Early loss of primary first molars - space loss vs arch width/length/perimeter
• No statistically significant loss of arch width, length and perimeter in the primary dentition
VERSUS
• Minor space loss
- Less space loss after eruption of permanent first molars
- Better intercuspation reduces space loss
Early loss of primary second molars
- Usually due to caries, sometimes due to ectopic eruption of permanent first molar
- Arch length reduction
- Blocked out second premolar
Important points regarding space loss
- Space loss often occurs before extraction (?)
- Greatest space loss usually occurs between 4-8 months after extraction
Impact of early tooth loss on occlusion (differences)
Differences:
• Mandibular effects worse than maxillary
• Second primary molar effects worse than first
• Earlier tooth loss worse than later
• Tooth loss in crowded arches worse than in spaced
Impact of early tooth loss on occlusion (summary)
- Premature loss of primary teeth correlates with increasing likelihood of orthodontic treatment
- Premature loss of primary incisors and canines does NOT affect posterior occlusion
- Premature loss of primary canines MAY affect anterior alignment
- Premature loss of primary molars MAY affect posterior occlusion
Fixed unilateral space maintainers
Band and loop:
• Band cemented around one abutment tooth
• Loop contacts another abutment tooth
Distal shoe:
• Premature loss of the primary second molar with an unerupted permanent first molar
• Band, distal extension, subgingival blade
• Requires an incision site
• Contraindicated in patients with poor oral hygiene, lack of cooperation, or medical conditions
Reverse band and loop:
• Loop faces distal
• Band is on the primary first molar
• Alternative to the distal shoe
Prefabricated space maintainers:
• Denote
• Appliance therapy group
Fixed bilateral space maintainers
Lower lingual holding arch:
• Bands cemented around primary second molars or permanent first molars
• Wire arch connecting molars and contacting mandibular incisors
Trans palatal arch:
• Bands cemented around primary second molars or permanent first molars
• Wire arch connecting molars
Nance holding arch:
• Bands cemented around primary second molars or permanent first molars
• Wire arch connecting molars with acrylic button connecting hard palate
Groper appliance:
• Mesh bonding base soldered to lingual arch
• Plastic denture tooth adapted and bonded to mesh base
** Can also be done as crown groper alliance with abutment teeth having SSCs
Removable space maintainer
- No single classic appliance
- Involves creativity
- Retentive features
- Acrylic to hold occlusion and fall the space
- Fill the saddle to encourage eruption behind the acrylic
Arch length discrepancy formula
Space available - space required = arch length discrepancy
Potential solutions for crowding
- Change space available
- Change space required
How to change space available
- Distalize molars
- Procline incisors
- Expand palate
- Upright posterior teeth
How to change space required
• Interproximal reduction
• Extract teeth
- Single tooth
- Four premolars
Treatment options for crowding
Less than 4mm:
• Non-extraction (change space available)
5mm to 9mm:
• Non-extraction or extraction (depending on facial esthetics, incisor position, etc.)
Greater than 10mm:
• Extraction (change space required)
Serial extraction
- “A planned sequence of tooth removal [to] reduce crowding and irregularity during the transition from the primary to the permanent dentition”
- Extraction of primary canines, primary first molars, first premolars (Cs, Ds, and 4s)
- Allows permanent teeth to erupt over the alveolus and through keratinized tissue, rather than being displaced buccal or lingually
Result of early extraction of Cs
- Delayed eruption of 3s
- Early eruption of 4s
When is the serial extraction protocol initiated?
• Mixed dentition:
- Minimizes the amount of tooth movement
- Allows permanent teeth to erupt in better position
What space analyses are used with mixed dentition?
- Moyer’s mixed
- Tanaka + Johnston
- Huckaba’s
- Nance mixed
What space analyses are used with permanent dentition?
- Pont’s
- Linder Harth
- Korkhaus
- Ashley Howe’s
- Bolton’s
- Carey’s
- Arch perimeter
What space analyses uses radiographs?
- Huckaba’s
- Nance’s mixed
What space analysis is the most practical + why?
Tanaka + Johnston: Does not require radiographs or reference tables.
Downside: It overestimates space required in both arches of white females, underestimates space required in lower arch in black males.
A simple variation of the proportionality method, using a single equation + the width of the lower incisors to predict the size of unerupted canines + premolars.
Good accuracy w/ European descent.
Tanaka + Johnston prediction values
One half the mesiodistal width of the four lower incisors
- +10.5mm = estimated width of mandibular canine + premolars in one quadrant
- +11.0mm = estimated width of maxillary canine + premolars in one quadrant
Endochondral bone apposition
- Bony replacement of cartilaginous precursors
- Cranial base + condyle of mandible
- Less modifiable in the context of dentofacial orthopedics
Intramembranous bone formation
- Secretion of bone matrix w/o cartilaginous precursors
- Facial bones (maxilla, body of mandible)
- More modifiable in the context of dentofacial orthopedics
Bone apposition typically occurs in osteogenic areas under __
Tension, not pressure
Cranial vault
- Formed by intramembranous ossification
- Apposition of new bone primarily at sutures (periosteum-lined contact areas)
- Remodeling on inner + outer surfaces of bones to allow for changes in contour
Cranial base
- Formed by endochondral ossification
- Bony replacement at synchondroses (cartilage-lined contact areas)
- Spheno-occipital considered principal growth cartilage of cranial base + only one remaining active during childhood growth period
Maxilla (nasomaxillary complex)
- Formed by intramembranous ossification
- Apposition in superior + posterior sutures of maxilla
- Resorption on anterior surface of maxilla
- Balanced apposition + resorption (remodeling, cortical drift, displacement)
- Appositional growth occurs up + back against cranial base w/ growth expressed downward + forward “from under the cranial base”
Mandible
- Formed by endochondral ossification at condyle, intramembranous ossification for body of mandible.
- Endochondral replacement at fibrocartilage of condyle
- Appositional growth predominates along posterior border of ramus w/ remodeling resorption along anterior border.
- Appositional growth occurs up + back against glenoid fossa w/ growth expressed downward + forward “from under the cranial base”
Timing of facial growth generally corresponds to __
Somatic growth patterns
When do females reach skeletal maturity?
~2yr earlier than males, on average
Female growth spurt
- Starts at ~10.5-11yo
- Peaks in 14-18mo (~12-13yo)
- Complete by 13.5-14yo
Male growth spurt
- Starts at ~12.5-13.5yo
- Peaks in 18-24mo (~14-16yo)
- Complete by 17-18yo
Facial height (vertical dimension)
Nasion-Menton
70% complete by 3yo; 90% prior to adolescent growth spurt
Facial width (transverse dimension)
- Shows the least amount of changes of any facial dimension
- Upper face width (bizygomatic width) ⇑ throughout childhood + adolescence w/ greatest rate observed b/w 2-6yo
- Lower face width (bigonial width) is 85% complete by the time first molars erupt
Facial depth (anteroposterior)
- Longest growing facial dimension
- May be divided into upper, middle, lower facial dimensions w/ areas growth at different times + rates (differential growth)
- Greater mandibular increments allow profile to change from convex in childhood to straight adult profile
What facial dimension takes the longest to grow?
Anteroposterior (facial depth)
What facial dimension shows the least amount of change?
Facial width (transverse)
What facial dimension is 70% complete by 3yo, 90% complete prior to adolescent growth spurt?
Facial height (vertical dimension)
When should progress records be taken?
Every 6-12mo
Due to major problems such as orthodontically induced external apical root resorption
Cephalometrics: Maxilla to cranium
- SNA
- A-point to Nasion perpendicular
- Maxillary length (Co-A)
Cephalometrics: Mandible to cranium
- SNB
- Pogonion to Nasion perpendicular
- Mandibular length (Co-Gn)
Cephalometrics: Maxilla to mandible
- ANB
- Mx-Md length difference
- Witt’s analysis (AO-BO)
Cephalometrics: Denture to denture
- Interincisal angle
- Wit’s
- Overbite/overjet
Cephalometrics: Incisor position
- Upper incisor to cranial base (FH, SN)
- Lower incisor to mandibular plane (IMPA)
- Upper + lower incisors to facial lines (NA, NB)
Cephalometrics: Growth direction
- Mandibular plane angle (FMA)
- Y-axis to cranial base
- Lower face height
Cephalometrics: Soft tissue profile
- Angle of convexity
- Lip profile to E-line
- Nasolabial fullness
Maxilla ceph values
Mandible ceph values
Basal relationship: Maxilla to mandible ceph values
Mandibular dentition ceph values
Maxillary to mandibular dentition ceph values
Facial/Soft tissue profile ceph values
Facial type/growth pattern ceph values
Maxillary dentition ceph values
Head orientation for qualitative ceph
FH plane should be perpendicular to vertical edge of the film
Chin position for qualitative ceph
- Nasion to pogonion line (facial plane) should be parallel w/ vertical edge of film after growth is complete
- In school-age children, positioning of chin point about 4-6mm behind facial plane allows for mandibular growth differential relative to cranial base
Maxillary position for qualitative ceph
- NA line should be parallel w/ vertical edge of film
- A-point approximates facial plane at all ages – if forward, suggests maxillary prognathism; if behind, suggest retrognathic position
Mandibular plane for qualitative ceph
- Go-Gn should intersect w/ cranial outline at occiput
- If plane “flat” extending below cranial outline into neck area, suggests brachyfacial horizontal grower
- If plane angled above cranial outline towards earhole, dolichofacial vertical growth pattern expressed
Maxillary incisor position for qualitative ceph
Long axis should be tangent w/ orbitale
Mandibular incisor position for qualitative ceph
- Long axis should show proclination approaching 100* to the mandibular plane in school-age children
- Long axis should upright to slightly above a right angle after growth is complete (mean of 93*)
Facial height for qualitative ceph (upper face height compared to lower face height)
Upper face height (N-ANS) should be about equal to lower face height (ANS-Me)
Primary teeth eruption timing
A B D C E
Primary teeth erupt from 8mo (lower As) to 30mo (upper Es); SD of 3mo
Primary dentition occlusal relationships are established by what age?
36mo
Spaced vs. non-spaced arches
- ~⅔ of primary dentition exhibits generalized spacing: Baume Type I
- ~⅓ are non-spaced: Baume Type II
- Once established, arches remain spaced or non-spaced over course of primary dentition
Where is the primate space?
Mesial to upper C’s; distal to lower C’s
Spaced vs. non-spaced arches are related to what?
Basal arch size rather than tooth mass differences
Molar terminal plane relationships
- Mesial step: 14%
- Flush terminal plane: 76%
- Distal step: 10%
What is early mesial shift + when does it occur?
- Closing of interdental space b/w molars prior to eruption of permanent molars
- Occurs due to eruption path of permanent molars which guide on distal roots of primary second molars
- Occurs at ~4yo
Permanent dentition eruption sequence
UA: 6 1 2 4 5 3 7
LA: 6 1 2 3 4 5 7
Occurs ~50% of the time
Most common variation is eruption of 7s in either arch before more anterior teeth
Transition of buccal segments in mixed dentition
L3s @10yo
4s @11-11.5yo
5s @11.5-12yo
U3s @12yo+
Increase in intercanine arch width during transition
- Lower width increase mean of 2.4mm w/ range of 0-5mm
- Upper width increase mean of 3.0mm w/ range of 0-6.5mm
Overjet + Overbite range for permanent dentition
Overjet: 0-3mm
Overbite: SD of 2 range is 0-5mm
What is the majority of mixed dentition occlusions?
End-on Class II
From FTP primary molars
Primary spacing affects crowding outcome into mixed dentition
- Spacing 3-4mm = no transitional crowding
- Spacing <3mm = 20% w/ incisor crowding
- No spacing = 50% w/ incisor crowding
- Crowded primary teeth = 100% w/ incisor crowding
What does mesial step convert into?
- 68% ⇒ Class I
- 19% ⇒ Class III
- Usually reflecting Class III skeletal malocclusion w/ mandibular prognathia + maxillary retrognathia
What does FTP convert into?
- 56% ⇒ shift into Class I
- 44% ⇒ stay end on or shift into full Class II
- Reflection of skeletal malocclusion involving mandibular retrognathia as a common causative factor
- Canines also demonstrate Class II positioning w/ pronounced overjet of 6mm+
What does distal step convert into?
Usually results in full Class III, some shift to end on Class II
What is the best predictor of sagittal relationship into permanent dentition?
Canine relationships
Mesial step canines usually result in what classification?
Class I
Distal step/end on canines usually result in what relationship?
Class II
Excessive mesial step (w/ incisor crossbite) usually results in what relationship?
Class III
What does premature loss of primary canines usually result in? What is it an indication of?
- Results in: ectopic eruption of permanent laterals
- Indication of significant tooth mass discrepancy
- Beyond space maintenance – space analysis required
Dimensional space loss is greater in which arch?
Maxillary
- U6s move forward bodily + rotate around palatal root
- L6s show mesial + lingual crown tipping
LLHA
- May also be used to prevent lingual tipping of incisors following premature loss of canines
- May interfere w/ eruption of permanent incisors if placed prior to eruption of those teeth
What is another name for TPA?
Goshgarian arch
What is less efficient? Nance vs. TPA
TPA
What appliances can be used for regaining space in the maxilla?
- Heagear
- Fixed molar “distalizing” appliances
- Removable appliance
What appliances can be used for regaining space in the mandible?
- Lip bumper
- Active lingual arch
- Removable split-saddle