development of occlusion

Development of occlusion

Shrirang Anand Sevekar

www.dentistpro.org

Contents

Evolution of toothFormTypeNumber

Evolution of dentitionDevelopment of concept of occlusion

Fictional eraHypothetical eraFactual era

Prenatal Dental DevelopmentInitiation of odontogenesisSpatial pattern

The mouth of neonateGum padsJaw relationPrecocious eruption

Contents

The Primary teeth and occlusionDevelopment of teethDevelopment of occlusion

The mixed Dentition periodFirst transitional periodInter-transitional periodSecond transitional period

Permanent teeth and occlusionDentitional and occlusal development in Young AdultClinical ImplicationsAdaptive mechanismsConclusionReferences

Evolution of Tooth : Form

Evolution from reptilian dentitionReptiles

Single cusp tooth triangular in shape (homodonty)development from single lobe

Evolution of tooth : Form

Rise of Triconodonty (Concrescence theory- Rose)Multicusp teeth- Fusion of Adjacent single lobe teeth

Accessory small cusp - On these expanded portion of crown

Maxillary molar -Lingual expansion

Mandibular molars - Buccal extension

Evolution of tooth : Form

Cingulum theory (Tim)Cingulum

Extra cusp

Kinetogenetic theory (Ryder)TMJ movement

Formation of ridge and groove on occlusal surface

Evolution of tooth : Form

Tritubercular theory (Cope and Osborn)Three tubercle

ParaconeProtoconeMetacone

Multitubercular theory (Forsyth Major)Multitubercular since origin

Diamer theory (Bolk)One origin for all mammalian teethSupports the concrescence, Kinatogenetic and Cingulum theoryAgainst Tritubercular theory

Evolution of tooth : Form

Differentiation theory –

Additional cusp By budding or outgrowth from the crown of a tooth rather than clustering of multiple teeth.

Evolution of tooth : Form

Tooth crown development from lobesLobes grow and develop with in their bony crypts until they fuse.CoalescenceDevelopmental groves.

Evolution of tooth : Type

Butler’s Field theoryDevelopmental fields

Conc. Of morphogens-Heterodonty

Clayton theoryVestigial organ

Evolution of tooth : Number

Change in hunting patterns Reduction in tooth number

5-1-4-7 ----------- in mammal –like reptiles 4-1-4-7

3-1-3-4 ----------- as generalized mammalian pattern 3-1-3-4

2-1-2-3 ----------- as generalized pattern for primates 2-1-2-3

Recent human dentition evolution

Reduction in size - facial reduction.

Economical advantage as fewer resources will be utilized in making smaller teeth.

Reduced Culinary skills -teeth ceased to have survival value.

Food preparation - minimized the importance of teeth for survival.

Development of dentition

Reptilian -Many sets of teeth (polyphyodont)

Humans - Two sets of teeth (diphyodont)

Development of concept of occlusion

Oc- Up Clusion - Closing

Fictional periodJust growed, Antagonism, Meeting, Gliding of teeth

Development of concept of occlusion

Hypothetical periodAngle’s thinking

Shape of cusp, crown, roots, structure of teeth and attachmentkey to occlusionCornerstone of occlusionOcclusion-Normal relations of occlusal inclined planes of the teeth when the jaws are closed

Lischer and SimonRelation of teeth to rest of face and cranium outside denture proper

Development of concept of occlusion

Factual periodRelation with muscle physiology and TMJ

Harmonious correlation between musculature, TMJ, teeth

Development of concept of occlusion: Factual Era

Normal occlusion ingredients- spacing, crowding, axial inclination, overjet, overbite

Development of concept of occlusion

Current conceptOcclusal position or tooth contact

Size and shape of teeth, masticatory pattern, inclination, functional premature contact, environmental factors

Postural resting positionMusculature

Integrity of stomatognathic system Interrelation between TMJ, Tongue, Oral cavity, Musculature

Development of concept of occlusion: Current concept

Nervous regulation

Prenatal Dental Development

Prenatal Dental Development

Initiation of Odontogenesis-

3rd Embryonic weekEpithelial thickening6th week- ‘c’ shaped epithelial arches (Enamel organ)

Prenatal Dental Development

Bud StageEnamel organ

Peripheral columnar cells

Central Polygonal cells

Dental sac and Dental papilla

7th week- first mand. Tooth bud formation

Prenatal Dental Development

Cap StageProliferation of tooth bud into cap form

Outer enamel epithelium

Inner enamel epithelium

Stellate reticulum

Prenatal Dental Development

Bell StageInner enamel epithelium –Ameloblast

Stratum intermedium

Dental papilla-Odontoblast formation

PDL formation

Dental papilla

Stratum reticulum

Prenatal Dental DevelopmentSequence pattern of development

CI-LI-C-M1-M2

25% - Postnatal variationsMand. Incisor eruption before max. incisor

Molar tooth germ development at same maturation

Sexual dimorphismDeciduous dentition

Male-faster growth

Permanent dentitionFemale

Faster growth

Prenatal Dental Development

Spatial patternArch shape

6-8 week- Flat anteroposterior

4th month- Elongation of Ant. Segment - Catenary curve

Prenatal Dental Development

Spacing JDR: 1971:73Laterals in more crowded position

Age advancement –Increased mesiodistal width of tooth germs - Decreased spacing

Prenatal Dental Development : Spatial pattern

Fields Tooth germ together with the space mesial and distal to it within the dental arch

Interdental space sharing

Prenatal Dental Development : Spatial pattern: Fields

Maximum occupancy of tooth field-

80%-1st Dec. Molar, Lateral incisors

More occupancy Rotation - DI-2 lingual displacement

Mouth of the neonate Predentate Period

Mouth of the neonate: Predentate Period

Gum padsAlveolar process at birthPink, firm, covered by dense fibrous periosteum,Form

State of maturity of infant at birthSize at birth as expressed by birth weightSize of developing primary teethGenetic factor

Predentate Period: Gum pads

Arch- Horse shoe shaped

Complete overjet

Contact areaMolar region

Infantile anterior open bite

Predentate Period: Gum pads

Dental grooveLabio buccal portion

Lingual portion

Transverse grooveTen segments

Lateral sulcus Interarch width

Predentate Period

Neonatal Jaw relationship

No precise ‘Bite’ or J.R. Ant. open bite incidenceSensory guidance system for neuromuscular functions

Suckling, swallowing respiration

Predentate Period

Dental arch width (AJO: 1997:401-9)Preeruptive

Significant increase between 6 week to 1 year

Predentate Period

Precociously erupted primary teeth

Natal teeth

Neonatal teeth

Pre-erupted teeth

Predeciduous teeth

Predentate Period : Self correcting anomalies

Retrognathic mandible

Differential and forward growth of mandible

Anterior open biteEruption of primary incisors

Predentate Period:Self correcting anomalies

Infantile swallowing pattern

Introduction of solid food in diet

Deciduous dentition

Deciduous dentition

Development of Primary teethCalcification

Central incisor- 14 week1st molar- 15 weekLateral incisor- 16 weekCanine- 17 week2nd molar- 18 week

Genetic control Morphology, rate and sequence of growth, pattern of calcification, mineral content

Deciduous dentition:Development of Primary teeth

EruptionMovement of tooth towards occlusionSexual differences

Male- early eruption till 15 monthFemale- Surpass after 15 months

Hatton studyHeredity- 78%Environmental factors- 22%

Height and weight (Clin.Pediatr.J:2005)

Deciduous dentition:Development of Primary teeth

Size and shape of primary teethMale- More largerNo marked sexual dimorphismHeredity Anomalies

Less frequent1% congenital absence

Deciduous dentition:Development of Primary teeth

AnkylosisMolars

Mand: Max -2:1

Physiologic resorption

PDL resorptionOsseous bridging and fusion between bone and dentin

Submerged toothFailure of vertical development

Deciduous dentition

Development of primary occlusion

Neuromuscular considerationSequential interdentation

Guidance of teeth in occlusal position by muscular functional matrix.

Role of low cusp ht. and attrition

Deciduous dentition: Development of occlusion

Primary dental arches

Ovoid in shapeRole of tongue

In maxillaIncreased intercanine width by 6 mm between 3-13 yrsIncreased Intermolar width of 2 mm between 3-5 yr

Deciduous dentition: Development of occlusion

In mandibleIncreased intercanine width by 3.7 mm between 3-13 yrsIncreased Intermolar width of 1.5 mm between 3-5 yr

Loss of arch length in mixed and permanent dentition

Uprighting of incisors, loss of leeway space

Deciduous dentition: Primary dental arches

Arch length and circumference

Small amt. of decrease

Mesial migration of 2nd primary molar during eruption

Proximal caries

Not many changes during 3-6 yrs

Deciduous dentition: Primary dental arches

Arch widthNo substantial increase

Increase to accommodate permanent molars

Arch heightIncrease in height of alveolar bone

No substantial increase

Theoretical value

Deciduous dentition: Development of occlusion

Occlusal relationFlush terminal plane

Distal surface of U/L

Favourable to guide permanent molars

59.1%

Deciduous dentition: Development of occlusion

Mesial stepDistal surface of lower more mesial to upper

Eating habit, Attrition and growing mandible

Favourable

19.1%

Deciduous dentition: Development of occlusion

Distal stepDistal surface of lower more distal to upper

Sucking habits

Prognostically unfavourable

4.8%

Deciduous dentition

Normal characteristics

Over biteVertical Incisor overlapAverage- 1- 2mm10-40% variationFoster study

Ideal- 19%Reduced- 37%Openbite-24%Excessive overbite- 20%

Deciduous dentition: Normal characteristics

OverjetHorizontal relationship

Normal 1-2mm

EffectsHabits

Mandibular forward growth

Excess wear

Deciduous dentition: Development of occlusion

Canine relationship

Most stableCl-I

Interincisal angulations

150 in primary123 in permanent

Dental arch circumference wider

Deciduous dentition: Normal characteristics

SpacingAccording to Baume

Closed dentition

Spaced dentitionLocalized –Primate spaces (anthropoid/ simion spaces)

Generalized- Physiologic Pressure from the tongue (Barber)

Total space-Maxi-0 to 8mm

Mandible-0 to 7mm

Deciduous dentition: Normal characteristics

Normal signs of Deciduous dentition

Spaced anteriorsPrimate spaceShallow overbite and overjetStraight terminal planeCl-I molar and cuspid relationship Almost vertical inclination of anterior teethOvoid arch form

Self correcting anomalies of Deciduous dentition

Anterior deep bite

Cause- Incisors more uprightCorrection

Attrition of incisal edgesEruption of permanent molarsForward and downward growth of mandible

Self correcting anomalies of Deciduous dentition

Physiologic spacesPermanent incisor accommodation

Maxilla-7mm

Mandible-5mm

Self correcting anomalies of Deciduous dentition

Primate spaceEarly mesial shift

Flush terminal plane

Early mesial shiftLate mesial shift (Leeway space)

Deciduous dentition

Prevalence Crossbite, Cl-II molar relationship, Excessive overjet, Openbite

Mixed dentition

Mixed dentition

Period of both primary and permanent dentition

Clinical importanceUtilization of arch perimeter

Adaptive changes in occlusion

Orthodontic intervention

Mixed dentition

Three phasesFirst transitional period.

Inter transition period.

Second transitional period

Mixed dentition

First transitional period :-

Emergence of first permanent molars.

Exchange of deciduous incisors with permanent incisors.

Establishment of occlusion

Mixed dentition

Intertransitional period

Both sets of dentition

Permanent incisors, 1st molars

Deciduous canines, 1st ,2nd molars

Mixed dentition

Second transitional period

Emergence of Bicuspids, cuspids, 2nd molar.

Establishment of occlusion

Mixed dentition

1st molar eruptionMandible

Guidance by distal surface of 2nd primary molarMesial and lingual path of eruption

MaxillaDistal and buccal path of eruptionForward movement of maxillary growth

Space created posteriorly

Mixed dentition

Molar adjustmentClosure of primate space

Early mesial shift - Controversial

Late mesial shift- Mesial migration of first permanent molar after loss of second deciduous molar using leeway space.

5 Yr

7 Yr

Mixed dentition

Difference of space

Leeway spaceMandible- Per quadrant 1.7mm

Maxilla- 0.9mm

Mixed dentition :Leeway space

ControversyAnterior segment

Maxilla- 3.2- 3.5 mm larger in one segment

Mandible2.4-2.5 mm larger

Balancing of posterior Leeway space

Mixed dentition :Leeway space

Morree’s viewMeasurement of deciduous and permanent teeth in same mouth

No leeway space available

Maxilla1-6 mm More space required

MandibleAt least 1 mm space required

Mixed dentition

Occlusal changesFlush terminal plane of primary dentition

Cl I molar relations achieved by.

Late mesial shift

Greater forward growth of mandible

Combination of both

Mixed dentition

A

Class I

Mixed dentition

Incisor eruptionMandible

Develop lingually to primary roots

Exfoliation of dec.lat.incisor

activation of eruption and labial movement

Lateral eruption- Crowding

Mixed dentition

Moves Primary cuspids distally and laterally closing the primate space

Premature loss of cuspids- Incisors tip lingually

Lingual tipping of incisors- Labioversion of cuspids

Mixed dentition: Incisor eruption

MaxillaSafety valve mechanism

Prevention of collapse by mandibular incisors

More labially eruption than primaryLabial inclinationLateral incisors

Developing crowns of cuspids lie labially and distally to its roots

Eruption more labially than centrals

No Orthodontic correction

Root resorption

Mixed dentition

Incisor liability (Alignment of incisors)

Deciduous – Permanent incisor difference= 6-7 mm

Mechanisms of incisor liability adjustment

Intercanine arch growth-3 to 4 mm

Mixed dentition: Incisor liability

Interdental (Developmental spacing)- 2 to 3 mm

More anterior position of permanent incisors as they erupt-1 to 2 mm

Mixed dentition:Cuspid and Bicuspid eruption

MandibleFavourable eruption sequence

6-1-2-3-4-5-7Eruption of 3

Maintenance of arch perimeter

Increased intercanine width

Prevention of lingual tipping of incisors

Hastened by extraction of primary cuspids

Mixed dentition:Cuspid and Bicuspid eruption

Eruption of 1st Bicuspid

Rarely any difficulty

Sometimes rotation due to uneven resorption of primary molar

Mixed dentition:Cuspid and Bicuspid eruption:

Mandible

Eruption of 2nd bicuspid

Last succedaneous tooth to eruptEruption complication

Mesial migration of 1st molarTooth size- Space available ratio poorPremature exfoliation of 2nd primary molar

Extreme variation in calcification and development schedule

Mixed dentition:Cuspid and Bicuspid eruption

MaxillaSequence of eruption

6-1-2-4-5-3-7 or 6-1-2-4-3-5-7

Displaced labiallyHabits

Affect eruptive pattern of cuspid and bicuspid

Mixed dentition:Cuspid and Bicuspid eruption

Maxilla1st bicuspid

Minimal difficulty in eruption

Same size as primary predecessor

2nd bicuspidEasy eruption

Larger mesiodistal width of primary predecessor

Mixed dentition:Cuspid and Bicuspid eruption:

MaxillaCuspid

Use of Leeway space to accommodateMore tortuous path of eruptionFavourable sequence

Cuspid before 2nd molar

Labioversion with mesial inclination

Ugly duckling stage (Broadbent Phenomenon)

Mixed dentition

2nd molar eruptionLast to erupt before 3rd molarMandible

If precede 2nd bicuspid tips the 1st molar mesially

MaxillaEruption before mandibular 2nd molar Symptom of developing ClI relation

Max. molar eruption before mand. molar- symptomic C lI

Mixed dentition

•Molar eruption

•Incisor eruption

•Leeway space

Mixed dentition

Self correcting anomalies

Anterior deep biteProprioceptive condition response of patient with slight supraeruption of permanent molars and premature contact of pads of tissue

Mixed dentition: Self correcting anomalies

Mandibular anterior crowding

Increased intercanine width

Tongue pressureLabial movement and inclination of incisors

Mixed dentition: Self correcting anomalies

Ugly Duckling Midline diastema

Eruption of canine

7 Year

8 Year 11 Year

Mixed dentition: Self correcting anomalies

End on molar relation

Late mesial shiftLeeway space

Permanent dentition

Development of permanent teeth

CalcificationSexual dimorphism

Nolla’s stages

Development of permanent teeth : Eruption

Ectopic developmentTeeth developing away from normal position

Most common- Maxi1st molar, canine, mand. Cuspid, maxi 2nd premolar, maxi lateral

Large primary and permanent teeth

Diminished maxi. Length

Posterior position of maxilla

Atypical angle of eruption

Sexual dimorphism

Development of permanent teeth : Eruption

Factors determining

the tooth’s position Inheritable trait

Presence or absence of adjacent teeth

Mesial drifting tendency

Factors determining the tooth’s position

Anterior component of force

Muscular forces (lip, cheek, tongue)

Habits

Rate of resorption of primary teeth

Localized pathosis

Permanent dentition

Dimensional changes in the dental arches

Combined width of teeth

Dimensions of dental arches in which the teeth are arrayed

Dimension of basal bone

Permanent dentition: Dental arches

WidthWidth increase dependant on alveolar process growth

MaxillaryPath of eruption of canine

outward forward and downward

Premolar , Molar – More divergence

Clinical significance

Permanent dentition: Dental arches

MandibleMandibular process more parallel path of eruption - Less width

CanineDistal tipping of primary cuspids into primate spaces during incisor eruption

Premolar- Buccal crown placement

Molars- Mesial shift- Convergence

Permanent dentition: Dental arches

Circumference or perimeter

ReductionLate mesial shiftMesial drifting tendencyLingual positioning of incisors due to differential mandibulomaxillary growthOriginal tipped position of incisors and molarsLocalized factors3rd molar eruption

Maxillary arch perimeter Angulation of incisors- Preservation

Permanent dentition

Overjet and overbite

Primary dentition- Almost zeroMixed dentition-

Overbite- Increases followed by decreaseNo. of facial variation

OverjetAnteroposterior skeletal relationshipSensitivity to abnormal lip and tongue function

Dentitional and occlusal changes in young adults

3rd molar development

Most variable in calcification and eruptionRole of 3rd molar in crowdingSimultaneous events

Arch perimeter shorteningIncreased incisor crowdingMore Forward Mandibular growth than maxilla

Dentitional and occlusal changes in young adults

Intra arch tooth alignment :-

Relationship of teeth with in the dental arch.

Teeth in varying degree of inclination.

Maxillary archAnterior teeth

mesially inclined

Posterior teeth Distally inclined.

MandibleObliquely backward

Dentitional and occlusal changes in young adults

Inter arch tooth alignment :-Relationship of teeth in one arch to those in other arch.Mandibular arch length and width is slightly less than maxillary arch.Occlusal contacts occur mainly through two types

Cusp to fosse relationship Cusp to embrasure relationship

Dentitional and occlusal changes in young adults

Curve of speeAnteroposterior direction the occlusal plane

Inclination of teeth in lateral view

The average value 2.5 – 3 mm

Dentitional and occlusal changes in young adults

Curve of Wilson:-A mediolateral curvature to occlusal plane

In frontal view

Posterior teeth Maxillary arch

Slight buccal inclination

Mandibular arch

Lingual inclination

Andrew’s six keys of occlusion

These are a set of six characteristics that were consistently present in collection of 120 casts of naturally optimal occlusion, identified by Dr. Lawrence F Andrews.

AJO 1972;62:296-309

Andrew’s six keys of occlusion

Inter- arch relationship

MolarMaxillary 1st

Mesiobuccal cusp

Mesiolingual cusp

Distal marginal ridge

Andrew’s six keys of occlusion

Interarch relationship

PremolarCusp-Embrasure

CanineCusp-Embrasure

IncisorMaxillary overlap

Andrew’s six keys of occlusion

Mesio-distal crown Angulation

The gingival portion of the long axis of crown is more distal than the incisal portion

Andrew’s six keys of occlusion

Labio-lingual crown inclination

Maxillary incisors Positive inclination

Mandibular incisors Slightly negative inclination.

Andrew’s six keys of occlusion: Labio-lingual crown inclinationThe Canines and premolars

negative and similar. Maxillary first and second molars

More negative than canines and premolars.

Andrew’s six keys of occlusion

Absence of rotation

Andrew’s six keys of occlusion

Tight contact

Andrew’s six keys of occlusion

Curve of speeThe depth of the curve of Spee ranges from a flat plane to slightly concave surface.

Conclusion

•Occlusion ,good or bad is the result of an intricate and complicated synthesis of genetic and environmental relationship at work through out the early developmental stages of childhood and young adulthood.•Understanding the concept can have a far reaching implications in diagnosis, treatment planning and prognosis of malocclusion

References Handbook of orthodontics – Robert Meyers.Dental anatomy – Julian Woelfel, Rickne Scheid Oral anatomy,histology, embryology – B.K.B. Berkovitz,G.R. holland,B.J. moxhamDevelopment,function and evolution of teeth – Mark Teaford, Smith, W.J. Ferguson.Shobha TandonGraberProfitBhalajiBarber

Andrews six keys to normal occlusion –

AJO 1972;62:296-309 Genetics of human tooth agenesis

AJO 2000;117:650-6Occlusion – DCNA April 1995.AJO1997:111:401-9Ped.Dent:2001:118-122

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