Development of Occlusion

1. NAVODAYA DENTAL COLLEGE
DEPARTMENT OF PEDODONTICS
STAFF NAME – Dr NAVEEN KUMAR
Professor
TOPIC NAME –Development of Occlusion and space management

2. i) 1st TransitionalPeriod (6to 8 years)
 period between completion of primary dentition and emergence of 1st
permanent teeth
 permanent 1st molar erupts posterior to 2nd primary molar
 exchange of 8 incisors occurs
Van der Linden. Development of the Dentition. 1st ed. Quintessence Publishers: Chicago, 1983.

3.  lower 1st molar erupts mesio-lingually
 upper 1st molar erupts disto-bucally
EruptionofMolars
Van der Linden. Development of the Dentition. 1st ed. Quintessence Publishers: Chicago, 1983.

4. Establishmentof1st permanentmolarocclusion
i) Early mesial shift (6 years)
- spaced primary dentition with
flush terminal relationship of 2nd
primary molar
- eruptive forces of permanent 1st
molars utilises the primate spaces
or physiological spaces between
primary molars
Ralph E. McDonald, David R. Avery & Jeffrey A. Dean. Dentistry for the Child and Adolescent. 8th ed. St. Louis:
Missouri, 2006.

5. ii) Late mesial shift (11 years)
- closed dentition, eruptive force of 1st permanent molar not able to close the
spaces
- utilises “leeway space of Nance” (difference in mesio-distal width between
CDE and 345
- 3.4 mm (1.7 mm in each quadrant) in mandible
- 1.8 mm (0.9 mm in each quadrant) in maxilla
- 6.2 mm (3.1 mm in each) in mandible
- 2.6 mm (1.3 mm in each) in maxilla
Nance, 1947
Lo & Moyers, 1953
Stephen H. Y. Wei. Pediatric Dentistry: Total Patient Care. Philadelphia: Lea and Febiger, 1988.

6. Ideal dentalOcclusion for7-yearschild
 Class I molar and canine relationship
 2 mm anterior and posterior overjet
 2 mm anterior open bite
 coincident dental midline
Ideal dentalArchpatternfor7-yearschild
 Tight proximal contacts
 No rotations
 Specific bucco-lingual axial inclinations
 Specific mesio-distal axial inclinations
 flat occlusal plane
 Excess (positive) leeway space
Ralph E. McDonald, David R. Avery & Jeffrey A. Dean. Dentistry for the Child and Adolescent. 8th ed. St. Louis:
Missouri, 2006.

7. Exchangeof Incisors
 Maxilla:
- 5 years → incisal edges of lateral incisors near occlusal plane than of C.In’s
- DI angle of central incisors are in contact with mesial surfaces of roots of L.In’s
- lateral incisors do not erupt till central ones have reached the level of occlusion
Van der Linden. Development of the Dentition. 1st ed. Quintessence Publishers: Chicago, 1983.

8. - lateral incisors then erupts more labially from a lingual position
- Lateral incisors erupts → more space in root region → apices of central
incisors moves distally → closure of midline diastema
- central incisors erupts → distal movement of lateral incisors → distal
movement of canines →  in Inter-canine width
Van der Linden. Development of the Dentition. 1st ed. Quintessence Publishers: Chicago, 1983.

9. Secondaryspacing (Baume,1950)
 closed primary dentition → mandibular lower incisors erupt → primary
mandibular canines move distally → space created for maxillary lateral
incisors to erupt
Stephen H. Y. Wei. Pediatric Dentistry: Total Patient Care. Philadelphia: Lea and Febiger, 1988.

10.  Mandible:
- incisal edges of permanent central incisors are slightly near the occlusal plane
than of laterals
- crowns of permanent centrals situated lingually to roots of their predecessors
- partly overlap the permanent laterals
- permanent central incisors erupts
before the laterals
Van der Linden. Development of the Dentition. 1st ed. Quintessence Publishers: Chicago, 1983.

11. Incisal Liability
 6 1/2 to 8 1/2 years
 unerupted permanent incisors are larger than primary incisors
 7.6 mm in upper arch
 6 mm in lower arch
 compensated by
i) Interdental spacing
- 4 mm (maxilla); 3 mm (mandible)
ii) Increase in Inter-canine arch width
Maxilla:
-  upto 12 years (females);  upto 16 years (males)
- 4.5 mm
Mandible:
-  upto 81/2 years (females);  upto 9 years (males)
- 3 mm
Warren Mayne, 1969
Robert E. Moyers. Handbook of Orthodontics. 4th ed. Year book Medical Publishers: Chicago, 1988.

12. iii) Increase in Inter-canine arch length
- permanent incisors erupts in a labial position
- 2.2 mm in maxilla; 1.3 mm in mandible
- 1230 in permanent dentition; 1500 in primary dentition
Robert E. Moyers. Handbook of Orthodontics. 4th ed. Year book Medical Publishers: Chicago, 1988.

13. Ugly Duckling stage
 transitional malalignment
 8 to 9 years of age
 distal divergence of crowns of upper permanent incisors; incisors crowding
 self correcting as permanent canine erupts
 absence in lower arch → incisors erupts simultaneously & vertical path of canine eruption
iv) Distal movement of primary canines

14. ii) Inter-transitional stage (8 to 10 years)
 lasts about 1.5 to 2 years
 temporary anterior open bite → incomplete eruption of permanent incisors
 vertical dimension of face → heightening of alveolar ridges → accommodates
continuous root growth of canines and bicuspids
 Leeway space utilized by
1) mesial shift of 1st permanent molar (establish Cl I molar relationship)
2) distal movement of cuspids (compensate for incisal liability)
Van der Linden. Development of the Dentition. 1st ed. Quintessence Publishers: Chicago, 1983.

15.  attrition of primary teeth → loss of intercuspation → growth of mandible → helps
to attain more anterior position than maxilla
 small rotations are corrected by tongue and lip pressure
 Gable effect – 1st bicuspid lies close to occlusal plane
 Catch up growth – late starting cuspids erupts 1st and by-passes premolars
Don M. Ranly. A synopsis of Craniofacial Growth.1st ed. Crofts: Newyork, 1984.

16. Permanent dentition period (> 13 years)
 presence of all permanent teeth except 3rd molars
 even distribution of roots in jaws
 maxillary teeth occlude buccally with mandibular teeth
 Inclination: roots of maxillary teeth distally angulated; 2nd premolars oriented
perpendicular to occlusal plane
 similar in mandible
 Angulation: - all anterior teeth are buccally inclined
- maxillary premolars and molars buccally inclined
- mandibular premolars oriented perpendicular to occlusal plane
- mandibular molars lingually inclined
Van der Linden. Development of the Dentition. 1st ed. Quintessence Publishers: Chicago, 1983.

17. Factors affecting Development of Occlusion
I] General factors
i) Abnormal Oral Musculature
ii) Oral Habits
iii) Existing Malocclusion
iv) Stage of Occlusal Development
v) Forces which start to operate when it makes contact with opposing tooth
II] Local factors
i) Proximal caries
ii) Premature loss of primary molars