Development of occlusion 2 /certified fixed orthodontic courses by Indian dental academy


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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

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Development of occlusion 2 /certified fixed orthodontic courses by Indian dental academy

  2. 2. Mixed dentition period: This is the period where teeth of both deciduous and permanent dentition are seen. It extends from 6 to 12 years of age. Most malocclusions make their appearance during this period. This period can be divided into two transitional periods- first and second.
  3. 3. First transitional period: Emergence of first permanent molars and transition of incisors are the events that take place during this period. Eruption of first permanent molars: The first permanent molars erupts at 6 years of age. They play an important role in the establishment and function of occlusion in the permanent dentition.
  4. 4. Factors influencing the antero posterior of the permanent molars:  Terminal plane relationship.  Differential growth of maxilla ad mandible Terminal plane relationship:  When the deciduous second molars are in flush terminal plane, the permanent first molars erupts into a cusp to cusp relationship Which later transforms into class I molar relationship by early mesial shift or late mesial shift of the molars.
  5. 5. Early mesial shift: In arches with physiologic spacing, the eruptive forces of the permanent molars causes closing of the spaces between the primary molars or the primate spaces thus allowing the molars to shift mesially (early) transforming into class I molar relationship.
  6. 6. Late mesial shift: In arches with no physiologic spacing, the mesial shift of the first permanent molars is delayed till the exfoliation of the primary molars. After the exfoliation of the primary molars the mesial shift (late) of the permanent molars takes place by making the use of Leeway space thus transforming into class I molar relationship
  7. 7. Leeway space: The combined mesiodistal widths of deciduous canine, first and second molars is more than that of the combined mesiodistal width of permanent canine, first and second premolar. The difference between the two is called Leeway Space. Maxilla 0.9 / segment = 1.8 mm total Mandible 1.7 / segment = 3.4 mm total
  8. 8.  When the deciduous second molars are in distal step, the permanent first molars will erupt into a class II relationship •This molar configuration is not self correcting and will cause a class II malocclusion despite leeway space and differential growth
  9. 9.  When the deciduous second molars are in mesial step, the permanent first molars will erupt into a class I relationship. This may remain or progress to a half or full cusp class III with continued mandibular growth.
  10. 10. Incisor eruption: Permanent incisors develop lingual to the primary incisors. For incisors to erupt in normal alignment, there is an obligate space requirement in the anterior part of both the arches which is termed as Incisor Liability. i.e. the total sum of mesiodistal width of the four permanent incisors is larger than the primary incisors by 7.6 mm in the maxilla and 6 mm in the mandible.
  11. 11. The space required is provided by –  interdental physiologic spacing in the primary incisor region. Increase in the inter canine arch width.  permanent incisors erupt labially to the primary incisors to obtain an added space of 2 to 3 mm. This is called Incisor Labiality.
  12. 12. Ugly duckling stage: (Broadbent’s Phenomenon) Around the age of 9 to 10 years, a midline diastema is commonly seen in the upper arch, which is usually misinterpreted by the parents as malocclusion. crowns of canines in young jaws impinges on the lateral incisor roots, driving them medially and causing the crowns to flare laterally. The roots of central incisors are also forced together thus causing a maxillary midline diastema.
  13. 13. This period from eruption of lateral incisor to the canine is termed as Ugly Duckling stage. With the eruption of the canines, the impingement from the roots shifts incisally thus driving the incisor crown medially, effecting closure of the diastema.
  14. 14. Inter transitional period: This is a stable phase where little changes take place in the dentition. Any asymmetry in emergence and corresponding differences in the height levels or crown length between the right and left side teeth are made up. Root formation of the emerged incisors, canines and molars continues, along with the concomitant increase in alveolar process height. Resorption of the roots of deciduous molars. This phase prepares for the second transitional phase.
  15. 15. Second transitional period: Following events take place. 1. Exfoliation of primary molars and canines at around 10 years. 2. In this period the first posterior teeth to erupt are the mandibular canine and the first premolar around 9 – 10 yrs, followed by maxillary premolars and canines around 11 – 12 yrs. Most common eruption sequence is 4 – 5 – 3 in the maxilla and 3 – 4 – 5 in the mandible
  16. 16. Favorable occlusion in this region is largely depend on – Favorable eruption sequence.  Satisfactory tooth size – available space ratio.  Attainment of normal molar relation with minimum diminution of space available for premolars.
  17. 17. Permanent dentition: The permanent dentition forms soon after birth except for the first molar which starts before birth. Calcification begins after birth with the calcification of first molar. At approximately 13 years of age all permanent teeth except third molars are fully erupted, thus establishing the occlusion of the permanent dentition.
  18. 18. Features of permanent dentition: Class I molar and canine relationship. Vertical overbite of about one third the clinical crown height of the mandibular central incisors. Coinciding midlines. Curve of Spee develops during transition and stabilizes in adulthood. The overjet and over bite decreases throughout the second decade of life due to greater forward growth pf the mandible
  19. 19. Leader in continuing dental education