development of occlusion
DESCRIPTION
Development of dentition and occlusion, final year BDS, Development of teethTRANSCRIPT
Development of Development of Occlusion Occlusion
What is occlusion ?What is occlusion ? The way maxillary and mandibular teeth The way maxillary and mandibular teeth
articulatearticulate Much more complexMuch more complex Study of teeth , their morphologyStudy of teeth , their morphology AngulationsAngulations Muscles of masticationMuscles of mastication TMJTMJ Functional jaw movementsFunctional jaw movements Relationship of teeth in centric occlusion Relationship of teeth in centric occlusion
centric relation and in functioncentric relation and in function Neuromuscular controlNeuromuscular control
Changes in occlusion Changes in occlusion with agewith age
From birth till adulthood and From birth till adulthood and beyond occlusion undergoes beyond occlusion undergoes significant changessignificant changes
Sometimes drastic changes and Sometimes drastic changes and sometimes more subtlesometimes more subtle
Differentiate normal from Differentiate normal from abnormalabnormal
Stages of dental Stages of dental developmentdevelopment
Gum pad stageGum pad stage From birth till eruption of first primary From birth till eruption of first primary
toothtooth Pink firm with dense layer of fibrous Pink firm with dense layer of fibrous
periosteumperiosteum Horse shoe shapedHorse shoe shaped Show elevations and groovesShow elevations and grooves Labiobuccal portion and lingual portionLabiobuccal portion and lingual portion Dental grooveDental groove
Stages of dental Stages of dental developmentdevelopment
Gum pad stageGum pad stage Divided into ten segments by ten grooves, Divided into ten segments by ten grooves,
the transverse groovesthe transverse grooves Transverse groove between canine and first Transverse groove between canine and first
deciduous molar segment is lateral sulcusdeciduous molar segment is lateral sulcus Anterior open bite relation ( infantile tongue Anterior open bite relation ( infantile tongue
thrust)thrust) Posterior segments touchingPosterior segments touching Maxillary gum pads slightly overlaps Maxillary gum pads slightly overlaps
mandibular gum pads horizontally and mandibular gum pads horizontally and vertically i.e. complete overjetvertically i.e. complete overjet
Primary dentition stagePrimary dentition stage
Extends from time of eruption of Extends from time of eruption of first primary teeth to time of first primary teeth to time of eruption of first permanent eruption of first permanent molar around 6 yrs of agemolar around 6 yrs of age
Sequence of Calcification of Sequence of Calcification of Primary Teeth Primary Teeth
Central incisorCentral incisor 14 weeks in utero14 weeks in utero First molarFirst molar 15 weeks in utero15 weeks in utero Lateral incisorLateral incisor 16 weeks in utero16 weeks in utero CupidCupid 17 weeks in utero17 weeks in utero Second molarSecond molar 18 weeks in utero18 weeks in utero
Sequence of Eruption of Sequence of Eruption of Primary Teeth Primary Teeth
a - b - d - c - e a - b - d - c - e Eruption faster in girls Eruption faster in girls 6 month variation = normal 6 month variation = normal no significant left/right differencesno significant left/right differences
Timing of Eruption of Timing of Eruption of Primary Teeth Primary Teeth
MANDIBULARMANDIBULAR Central incisorCentral incisor 661/2 month1/2 month
Lateral incisorLateral incisor 7 months7 months CanineCanine 16-20 months16-20 months First molarFirst molar 14-16 months14-16 months Second molarSecond molar 20-30 months20-30 months
Timing of Eruption of Timing of Eruption of Primary Teeth Primary Teeth
MAXILLARYMAXILLARY Central incisorCentral incisor 771/2 month1/2 month
Lateral incisorLateral incisor 8 months8 months CanineCanine 16-20 months16-20 months First molarFirst molar 12-16 months12-16 months Second molarSecond molar 20-30 months20-30 months
Primary dentition stagePrimary dentition stage
Overbite Overbite OverjetOverjet SpacingSpacing Molar relationshipsMolar relationships
Primary dentition stagePrimary dentition stage Overbite Overbite Amount of vertical overlap between Amount of vertical overlap between
maxillary and mandibular central maxillary and mandibular central incisorsincisors
Described either in mm or as percentageDescribed either in mm or as percentage Normally varies between 10-40%Normally varies between 10-40% Edge to edge or zero overbiteEdge to edge or zero overbite Lack of overlap ------------- open bite Lack of overlap ------------- open bite
quantified in mmquantified in mm May be due to presence of oral habitsMay be due to presence of oral habits
Primary dentition stagePrimary dentition stage Overjet Overjet Amount of horizontal overlap Amount of horizontal overlap
between most protruded between most protruded maxillary CI and corresponding maxillary CI and corresponding mandibular central incisorsmandibular central incisors
Described in mmDescribed in mm Normally varies between 0-4mmNormally varies between 0-4mm Excessive overjet may be due to Excessive overjet may be due to
presence of oral habitspresence of oral habits
Spacing in deciduous Spacing in deciduous dentitiondentition
Generalized spacing (Baume’s space)Generalized spacing (Baume’s space) Localized spacingLocalized spacing No spacingNo spacing CrowdingCrowding Generalized spacing is a common Generalized spacing is a common
occurrenceoccurrence Tooth size arch length discrepancy in the Tooth size arch length discrepancy in the
form of crowding less common ( 3% of form of crowding less common ( 3% of individuals with primary dentition )individuals with primary dentition )
Spacing in deciduous Spacing in deciduous dentitiondentition
Localized spacing ( primate spaces )Localized spacing ( primate spaces ) Maxillary arch between lateral incisor Maxillary arch between lateral incisor
and canineand canine Mandibular arch between canine and first Mandibular arch between canine and first
molarmolar Also known as simian and anthropoid Also known as simian and anthropoid
spacesspaces Helps in placement of canine cusps in Helps in placement of canine cusps in
opposite archesopposite arches
Occlusion of the Primary Occlusion of the Primary Second Molar Second Molar
In primary dentition A-P molar In primary dentition A-P molar relationship is described in terms of relationship is described in terms of relationship between terminal planesrelationship between terminal planes
Look at the distal aspect of the 2nd Look at the distal aspect of the 2nd
molarmolar Flush terminal plane – most common Flush terminal plane – most common Mesial step Mesial step Distal step Distal step
Flush Terminal Plane Flush Terminal Plane
In the flush terminal plane In the flush terminal plane both the maxillary and the both the maxillary and the mandibular plane are at the mandibular plane are at the same level anterio same level anterio posteriorlyposteriorly
Flush Terminal Plane Flush Terminal Plane
Mesial step Mesial step
In the mesial step In the mesial step relationship mandibular relationship mandibular terminal plane is relatively terminal plane is relatively more mesial ( anteriorly) more mesial ( anteriorly) than the maxillary terminal than the maxillary terminal planeplane
Distal step Distal step
In the distal step In the distal step relationship mandibular relationship mandibular terminal plane is relatively terminal plane is relatively more distal (posterior) than more distal (posterior) than the maxillary terminal planethe maxillary terminal plane
Distal step Distal step
Distribution of terminal Distribution of terminal plane relationships plane relationships
In one study involving 121 In one study involving 121 children at age 5 yrs it was children at age 5 yrs it was foundfound
Distal stepDistal step 10%10% Flush terminal planeFlush terminal plane
29%29% Mesial step 1mmMesial step 1mm
42%42% Mesial step >1mmMesial step >1mm
19%19%
Importance of terminal Importance of terminal plane plane
Erupting first permanent Erupting first permanent molars are guided by molars are guided by distal surface of second distal surface of second primary molars as they primary molars as they erupt into occlusionerupt into occlusion
Primary Cuspid Primary Cuspid Occlusion Occlusion
Look at long axis of the Look at long axis of the maxillary cuspid maxillary cuspid
Neutro cuspid (Class I) Neutro cuspid (Class I) Disto cuspid (Class II) Disto cuspid (Class II) Mesio cuspid (Class III)Mesio cuspid (Class III)
Neutro cuspid Neutro cuspid (Class I)(Class I)
Disto cuspid (Class II)Disto cuspid (Class II)
Mesio cuspid (Class III)Mesio cuspid (Class III)
The Ideal Primary The Ideal Primary Occlusion Occlusion
Ovoid arches Ovoid arches Good interdental or Good interdental or
primary spacing primary spacing Flush terminal plane or Flush terminal plane or
mesial step molarsmesial step molarsNeutro cuspidsNeutro cuspids
The Ideal Primary The Ideal Primary Occlusion Occlusion
Deep biteDeep biteFlat curve of speeFlat curve of speeShallow cuspal Shallow cuspal
interdigitationinterdigitation Incisors are more Incisors are more
vertically placedvertically placed
Mixed Dentition Mixed Dentition Occlusion Occlusion
Mixed dentition stage Mixed dentition stage
Starts with the eruption of Starts with the eruption of first permanent toothfirst permanent tooth
Completed at the time last Completed at the time last primary tooth is shedprimary tooth is shed
Significant changes in Significant changes in dentitiondentition
Mixed dentition stage Mixed dentition stage
Temporary open biteTemporary open biteAntimere should erupt Antimere should erupt
with in six monthswith in six monthsSequence of eruption of Sequence of eruption of
permanent teeth permanent teeth
Mixed dentition stage Mixed dentition stage
During mixed dentition stage presence During mixed dentition stage presence of midline diastema between central of midline diastema between central incisors is a normal occurrenceincisors is a normal occurrence
Mixed dentition stage Mixed dentition stage
Size may vary from 1mm-Size may vary from 1mm-3mm3mm
Usually closes by the time Usually closes by the time maxillary canine fully eruptmaxillary canine fully erupt
Molar relatitionship Molar relatitionship
Class IClass IClass IIClass IIClass IIIClass III
Molar relationship Molar relationship Flush terminal plane may lead to:Flush terminal plane may lead to:End to endEnd to end (end on) (end on) Class I (Early or late mesial shift)Class I (Early or late mesial shift) Class IIClass IIMesial step may lead to: Mesial step may lead to: Class I (normally) Class I (normally) Class III Class III Distal step leads to:Distal step leads to: Class IIClass II
Class II
Class I (desirable)
ETE
End to End Permanent Molar
Mesial Step
Class III
Class I (desirable)
Mesial Step
Disto Step
Class IIAlways
Disto Step
Causes of changes in molar Causes of changes in molar relationship relationship
Early mesial shift Early mesial shift Late mesial shift Late mesial shift Mandibular growthMandibular growth
Causes of changes in molar Causes of changes in molar relationship relationship
Early mesial shift Early mesial shift Late mesial shift Late mesial shift Mandibular growthMandibular growth
Early mesial shiftEarly mesial shift
Occurs during early mixed Occurs during early mixed dentitiondentition
The eruptive forces of 1The eruptive forces of 1stst permanent molar push permanent molar push deciduous 1deciduous 1stst and 2 and 2ndnd molars molars
Occurs when primate spaces Occurs when primate spaces are presentare present
Leeway spaceLeeway space
Sum of (c-d-e) > (3-4-5) This Sum of (c-d-e) > (3-4-5) This allows more space for 3-4-5 This allows more space for 3-4-5 This "leeway space" averages 1.7 "leeway space" averages 1.7 mm. in the mandibular mm. in the mandibular segment; 0.9 in the maxillary segment; 0.9 in the maxillary segment segment
Late mesial shiftLate mesial shift
Refers to mandibular Refers to mandibular permanent molar moving permanent molar moving mesially mesially
If permanent molars are ETE, If permanent molars are ETE, late mesial shift allows late mesial shift allows mandibular molar to move into mandibular molar to move into a Class I occlusion a Class I occlusion
Late mesial shiftLate mesial shift
FTP Class IMolar moves into this space...
Incisor Liability Incisor Liability
Permanent incisors are Permanent incisors are larger than primary incisors larger than primary incisors
This difference in size is This difference in size is termed "incisor liability" termed "incisor liability"
How does the body create How does the body create enough room for the larger, enough room for the larger, permanent incisors? permanent incisors?
Overcoming Incisor Overcoming Incisor Liability Liability
Interdental spacing of primary Interdental spacing of primary incisors incisors
Intercanine arch width growth Intercanine arch width growth Labial positioning of the Labial positioning of the
permanent incisorspermanent incisors Favorable size ratio between the Favorable size ratio between the
primary and permanent incisorsprimary and permanent incisors
Overcoming Incisor Overcoming Incisor Liability Liability
Interdental spacing of primary Interdental spacing of primary incisorsincisors
Good interdental spacing of Good interdental spacing of primary incisors allows for better primary incisors allows for better alignment of the larger alignment of the larger permanent incisors.permanent incisors.
Primary Spacing Primary Spacing
Primary Spacing Primary Spacing
Overcoming Incisor Overcoming Incisor Liability Liability
Intercanine arch width growth Intercanine arch width growth Width growth creates more room Width growth creates more room
for the permanent incisors for the permanent incisors Mandibular intercanine growth Mandibular intercanine growth
occurs mostly during permanent occurs mostly during permanent incisor eruption incisor eruption
Maxillary intercanine growth Maxillary intercanine growth occurs during incisor eruptionoccurs during incisor eruption
UnpredictableUnpredictable
Intercanine growth Intercanine growth
Overcoming Incisor Overcoming Incisor Liability Liability
Labial positioning of the Labial positioning of the permanent incisors permanent incisors
Permanent incisors erupt to Permanent incisors erupt to a more labial position a more labial position
Permanent incisors are Permanent incisors are angled more labially angled more labially
The above creates more arch The above creates more arch lengthlength
Labial positioning Labial positioning
Overcoming Incisor Overcoming Incisor Liability Liability
Favorable size ratio between the Favorable size ratio between the primary and permanent incisors primary and permanent incisors
Size ratio between the primary Size ratio between the primary and permanent incisors may be and permanent incisors may be favorable or unfavorable favorable or unfavorable
Favorable: large primary, small Favorable: large primary, small permanent permanent
Unfavorable: small primary, large Unfavorable: small primary, large permanentpermanent
Mixed dentitionMixed dentition
First transitional periodFirst transitional period Inter transitional periodInter transitional period Second transitional periodSecond transitional period
Second transitional Second transitional periodperiod
Characterized by replacement of Characterized by replacement of deciduous molars and canines by deciduous molars and canines by premolars and permanent canines premolars and permanent canines respectivelyrespectively
Ugly duckling stageUgly duckling stage
Ugly duckling stageUgly duckling stage
Transient malocclusion seen in maxillary Transient malocclusion seen in maxillary incisor region between 8-9 years of ageincisor region between 8-9 years of age
Eruption of permanent caninesEruption of permanent canines As canines erupt they put pressure on As canines erupt they put pressure on
roots of permanent lateral incisorsroots of permanent lateral incisors Pressure on permanent central incisorsPressure on permanent central incisors Midline spacingMidline spacing Described by Broadbent as ugly duckling Described by Broadbent as ugly duckling
stagestage Usually self correcting as the pressure is Usually self correcting as the pressure is
transferred from roots to crownstransferred from roots to crowns
Predicting Future Predicting Future Crowding – Crowding –
Mixed dentition Mixed dentition analysis analysis
Mixed Dentition Analysis Mixed Dentition Analysis
Why: predict amount of Why: predict amount of crowding after permanent crowding after permanent teeth come inteeth come in
When: during mixed When: during mixed dentition dentition
What: boley gauge, models, What: boley gauge, models, prediction tableprediction table
MDA Methodology MDA Methodology
Measure mesial-distal diameter of Measure mesial-distal diameter of the mandibular incisors and record the mandibular incisors and record the valuethe value
Determine the space required for Determine the space required for alignment of incisors alignment of incisors
Determine the amount of space Determine the amount of space available for permanent canines and available for permanent canines and premolars after incisor alignmentpremolars after incisor alignment
MDA Methodology MDA Methodology
Predict the combined width of Predict the combined width of mandibular canines and mandibular canines and premolars with the aid of premolars with the aid of probability chartprobability chart
This estimated canine and This estimated canine and premolar size value is premolar size value is subtracted from measured subtracted from measured spacespace
Moyer's Prediction Chart Moyer's Prediction Chart
19.19.55
20.20.00
20.20.55
21.21.00
21.21.55
22.22.00
22.22.55
23.23.00
23.23.55
24.24.00
MaxMax. . 75%75%
20.20.66
20.20.99
21.21.22
21.21.55
21.21.88
22.22.00
22.22.33
22.22.66
22.22.99
23.23.11
manmandd
75%75%
20.20.11
20.20.44
20.20.77
21.21.00
21.21.33
21.21.66
21.21.99
22.22.22
22.22.55
22.22.88
Allowance for Late Allowance for Late Mesial Shift Mesial Shift
If permanent molars are end to If permanent molars are end to end, mandibular molar should end, mandibular molar should move mesially to obtain Class I move mesially to obtain Class I interdigitation.interdigitation.
This will decrease the arch This will decrease the arch length available for 3-4-5.length available for 3-4-5.
Reduce 1.7 mm. per side with Reduce 1.7 mm. per side with ETE relationship. ETE relationship.
Johnson and Tanaka Johnson and Tanaka analysisanalysis
Variation of moyer’s analysisVariation of moyer’s analysis Table is not neededTable is not needed Sum of widths of mandibular incisors is Sum of widths of mandibular incisors is
divided by 2divided by 2 For the mandibular arch add add 10.5 to For the mandibular arch add add 10.5 to
get the resultget the result For the maxillary arch add 11.0 to get the For the maxillary arch add 11.0 to get the
result result Corresponds to 75% probability of moyers Corresponds to 75% probability of moyers
tabletable
Hixon and oldfather Hixon and oldfather methodmethod
Maximum MD daimeter of CI and LI Maximum MD daimeter of CI and LI of one side + MD Diameter of of one side + MD Diameter of unerupted first and second unerupted first and second premolars on radigraphs taken by premolars on radigraphs taken by paralleling technique.paralleling technique.
Use this sum to estimate size of Use this sum to estimate size of 3+4+5 using the prediction chart 3+4+5 using the prediction chart
Hixon and oldfather Hixon and oldfather methodmethod
Measured value Estimated tooth size
23 18.4
24 19.0
25 19.7
26 20.3
27 21.0
28 21.6
29 22.3
30 22.9
Radiographic methodRadiographic method
IOPA of the unerupted teeth and of IOPA of the unerupted teeth and of overlying primary teeth are takenoverlying primary teeth are taken
The enlargement ratio for each The enlargement ratio for each unerupted permanent tooth is unerupted permanent tooth is computed by measuring the nearest computed by measuring the nearest erupted tooth in the mouth and then erupted tooth in the mouth and then in the radiograph.in the radiograph.
Radiographic methodRadiographic methodErupted tooth size in the mouth
X unerupted tooth size in X ray
Erupted tooth size in x ray
= correct tooth size
Eruption and Occlusion Eruption and Occlusion of the Permanent of the Permanent
Dentition Dentition
Permanent dentition Permanent dentition stagestage
First molar calcification at birthFirst molar calcification at birth Rest calcification after birthRest calcification after birth Sequence of eruptionSequence of eruption Timing of eruptionTiming of eruption Permanent incisor erupt lingual and Permanent incisor erupt lingual and
palatal to deciduous incisors palatal to deciduous incisors Move labially as they eruptMove labially as they erupt Premolars develop below the diverging Premolars develop below the diverging
roots of the deciduous molarsroots of the deciduous molars
Permanent dentition Permanent dentition stagestage
Overlap : in a normally occluding dentition, Overlap : in a normally occluding dentition, the maxillary teeth are labial/buccal to the maxillary teeth are labial/buccal to mandibular teethmandibular teeth
Angulations : primary dentition teeth are Angulations : primary dentition teeth are vertically positioned, permanent dentition vertically positioned, permanent dentition buccolingual and mesiodistal angulationsbuccolingual and mesiodistal angulations
Occlusion : with the exception of mandibular Occlusion : with the exception of mandibular central incisors and maxillary second molars, central incisors and maxillary second molars, each permanent teeth occludes with two teeth each permanent teeth occludes with two teeth from the opposite archfrom the opposite arch
Overbite and overjet : 10-50% and 1-3 mm Overbite and overjet : 10-50% and 1-3 mm res.res.
Permanent dentition Permanent dentition stagestage
Posterior relationships : Posterior relationships : Maxillary and mandibular molars are in Maxillary and mandibular molars are in
class I relationshipclass I relationship Posterior segment well interdigitatedPosterior segment well interdigitated Maxillary canine should be occluding in Maxillary canine should be occluding in
the embrasure between the mandibular the embrasure between the mandibular canine and first premolar.canine and first premolar.
Nolla's 10 Stages of Nolla's 10 Stages of Calcification Calcification
Stage 1 – absence of cryptStage 1 – absence of crypt Stage 2 - initial calcificationStage 2 - initial calcification Stage 3 - 1/3Stage 3 - 1/3rdrd of crown completed of crown completed Stage 4 - 2/3Stage 4 - 2/3rdrd of crown completed of crown completed Stage 5 - crown almost completedStage 5 - crown almost completed Stage 6 - crown formation completeStage 6 - crown formation complete stage 7 – 1/3stage 7 – 1/3rdrd of root completed of root completed Stage 8 - alveolar crest pierced (2/3 root development) Stage 8 - alveolar crest pierced (2/3 root development) Stage 9 - gingival margin pierced (3/4 root development) Stage 9 - gingival margin pierced (3/4 root development) Stage 10 – apical end of root development completedStage 10 – apical end of root development completed Interval between Stage 6 and full interdigitation is about Interval between Stage 6 and full interdigitation is about
5 years 5 years
Sequence Sequence
Girls 5 months faster than boys Girls 5 months faster than boys 6-1-2-4-3-5-7 and 6-1-2-4-5-3-7 6-1-2-4-3-5-7 and 6-1-2-4-5-3-7
most common in maxilla most common in maxilla (6-1)-2-3-4-5-7 and (6-1)-2-4-3-5-(6-1)-2-3-4-5-7 and (6-1)-2-4-3-5-
7 most common in mandible7 most common in mandible
Sequence is Important! Sequence is Important!
Alteration of sequence of Alteration of sequence of eruption alerts the practitioner eruption alerts the practitioner to potential problems to potential problems
Supernumerary Supernumerary Neoplasm or cyst Neoplasm or cyst ALWAYS COUNT THE TEETH!ALWAYS COUNT THE TEETH!
Calcification times (Max. Calcification times (Max. and mand. and mand. res.)res.)
Central incisorCentral incisor 3-4 m3-4 m 3-4 m 3-4 m Lateral incisorLateral incisor 10-12 m10-12 m 3-4 m 3-4 m CuspidCuspid 4-5 m4-5 m 4-5 m 4-5 m 1st bicuspid1st bicuspid 1 1/2 y1 1/2 y 1 3/4 y 1 3/4 y 2nd bicuspid2nd bicuspid 2 y2 y 2 1/4 y 2 1/4 y Second molarSecond molar 2 1/2 y2 1/2 y 2 3/4 y 2 3/4 y
How To Remember This How To Remember This
A group of teeth A group of teeth begin calcification begin calcification every six months every six months
Not exact, but Not exact, but close enough close enough
BirtBirth h
1st molars 1st molars
6m6m Anterior teeth, Anterior teeth, except maxillary except maxillary laterals laterals
12m12m Maxillary Maxillary laterals laterals
18m18m 1st bicuspids 1st bicuspids
24m24m 2nd bicuspids 2nd bicuspids
30m30m 2nd molars 2nd molars
Average Times to Average Times to Remember Remember
Hard tissue begins to enamel Hard tissue begins to enamel completed completed
4-5 years 4-5 years
Except for 1st molar (3) and cuspid (6)Except for 1st molar (3) and cuspid (6) Hard tissue begins to Root Hard tissue begins to Root
Completion Completion
10 years, except for cuspids (13)10 years, except for cuspids (13) Eruption to Root Completion Eruption to Root Completion
3 years3 years
Why Know Calcification Why Know Calcification Times? Times?
Enamel Enamel hypoplasiahypoplasia
Fluorosis Fluorosis
Mesial Drift and Anterior Mesial Drift and Anterior Component of ForceComponent of Force
• Axial inclination Axial inclination produces mesial force produces mesial force
• Mesial drift Mesial drift • Ectopic eruption Ectopic eruption • Space maintenanceSpace maintenance
Ectopic EruptionEctopic Eruption
Absence of Permanent Absence of Permanent Teeth Teeth
4-6% congenital absence 4-6% congenital absence Females more frequently missing Females more frequently missing
teeth teeth Most common congenitally absent Most common congenitally absent
teeth: teeth: mandibular 2nd premolar mandibular 2nd premolar maxillary lateral incisor maxillary lateral incisor maxillary 2nd premolarmaxillary 2nd premolar
Extra Permanent Teeth Extra Permanent Teeth
Supernumerary teeth found Supernumerary teeth found most frequently in the maxillary most frequently in the maxillary incisor region (mesiodens), and incisor region (mesiodens), and occasionally in the premolar occasionally in the premolar area area
2-3% supernumerary teeth2-3% supernumerary teeth Males more common Males more common
Terms: Mixed Dentition Terms: Mixed Dentition
Classic mixed dentitionClassic mixed dentition
12cde6 12cde6
Early mixed dentition Early mixed dentition 1bcde6 1bcde6
Late mixed dentitionLate mixed dentition1234e61234e6
Terms - Arch Length Terms - Arch Length
Arch length is the distance in Arch length is the distance in millimeters from the mesial millimeters from the mesial of the 1st permanent molar of the 1st permanent molar around the arch over the around the arch over the contact points to the mesial contact points to the mesial of the 1st permanent molar of the 1st permanent molar on the opposite side.on the opposite side.
Arch LengthArch Length
Terms - Overbite/Overjet Terms - Overbite/Overjet
OverbiteOverbite is a vertical measurement is a vertical measurement of the amount of overlap of the of the amount of overlap of the incisors. incisors.
OverjetOverjet is the millimeter horizontal is the millimeter horizontal measurement from the labial of the measurement from the labial of the maxillary central incisor to the labial maxillary central incisor to the labial of the mandibular central incisor. of the mandibular central incisor.
OverbiteOverbite
OverjetOverjet
Straight ProfileStraight Profile
Protrusive ProfileProtrusive Profile
Retrusive ProfileRetrusive Profile
Typical Child Profile Typical Child Profile
Types of Faces Types of Faces
Brachycephalic - broad & Brachycephalic - broad & short short
Dolichocephalic - long & Dolichocephalic - long & narrow narrow
Mesocephalic - normalMesocephalic - normal
Dimensional changes in Dimensional changes in the dental archesthe dental arches
Dimensional changes in Dimensional changes in the dental archesthe dental arches
The transition from primary The transition from primary dentition stage to the permanent dentition stage to the permanent dentition stage has an impact on dentition stage has an impact on dental arch length and intermolar dental arch length and intermolar and intercanine width and intercanine width
Changes in the maxillary Changes in the maxillary archarch
The intercanine width increases by an average of The intercanine width increases by an average of 6.0 mm in a child between 3-13 years of age6.0 mm in a child between 3-13 years of age
It continues to increase between 13-45 years of age It continues to increase between 13-45 years of age by 1.7 mmby 1.7 mm
In primary dentition stage there is an increase of In primary dentition stage there is an increase of intermolar width of 2.0 mm between 3-5 years intermolar width of 2.0 mm between 3-5 years
The first permanent intermolar width increases by The first permanent intermolar width increases by 2.2 mm between 8-13 years of age and decreases 2.2 mm between 8-13 years of age and decreases by 1.0 mm by 45 years of ageby 1.0 mm by 45 years of age
There is a slight decrease in arch length with age There is a slight decrease in arch length with age because of uprighting of incisorsbecause of uprighting of incisors
( Bishara S E : arch width changes from 6weeks to 45 ( Bishara S E : arch width changes from 6weeks to 45 years of age, Am J of Orthod Dentofacial Ortop )years of age, Am J of Orthod Dentofacial Ortop )
Changes in the Changes in the mandibular archmandibular arch
The intercanine width increases by an average of The intercanine width increases by an average of 3.7 mm in a child between 3-13 years of age3.7 mm in a child between 3-13 years of age
It decreases between 13-45 years of age by 1.2 mmIt decreases between 13-45 years of age by 1.2 mm In primary dentition stage there is an increase of In primary dentition stage there is an increase of
intermolar width of 1.5 mm between 3-5 years intermolar width of 1.5 mm between 3-5 years The first permanent intermolar width increases by The first permanent intermolar width increases by
1.0 mm between 8-13 years of age and decreases by 1.0 mm between 8-13 years of age and decreases by 1.0 mm by 45 years of age1.0 mm by 45 years of age
The arch length decreases in mixed and permanent The arch length decreases in mixed and permanent dentition stages as a result of uprighting of incisors dentition stages as a result of uprighting of incisors and the loss of leeway space by mesial movement of and the loss of leeway space by mesial movement of first permanent molarsfirst permanent molars
( Bishara S E : arch width changes from 6weeks to 45 ( Bishara S E : arch width changes from 6weeks to 45 years of age, Am J of Orthod Dentofacial Ortop )years of age, Am J of Orthod Dentofacial Ortop )