development of occlusion
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Development of Occlusion,OcclusionDental social network-- Find morehttp://www.dentistpro.orgTRANSCRIPT
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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