Development of occlusion
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This document discusses the development of teeth over four periods: pre-dentition, primary dentition, mixed dentition, and permanent dentition. It describes the key developments that occur in each period, including the eruption of baby teeth and permanent teeth. For example, in the primary dentition period, the first teeth begin erupting around 6 months of age and the set is complete by 2.5-3.5 years. In the mixed dentition period, the first permanent molars erupt around age 6 and both primary and permanent teeth are present.
Development of occlusion
- 1. BY Dr. ALVI FATIMA MDS 1ST YEAR DEPT OF PEDIATRIC & PREVENTIVE DENTISTRY 1
- 2. INDEX Introduction Development of tooth an overview Period of occlusal development Pre-dentition period Primary dentition period Mixed dentition period Permanent dentition period Developmental disturbances Conclusion 2
- 3. 3 Development of tooth an over-view
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- 10. PERIOD OF OCCLUSAL DEVELOPMENT Occlusal development can be divided into following development period. Pre-dental period Primary dentition period Mixed dentition period Permanent dentition period 10
- 11. (LAST UPTO 6 MONTHS AFERT BIRTH) 11
- 12. GUM PAD The alveolar process at the time of birth are known as gum pads. The gum pads are pink, firm and covered by a dense layer of fibrous periosteum 12
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- 14. They are horse shoe shaped and develop in two parts. They are labio-buccal portion and the lingual portion The two portion of the gum pads are separated from each other by a groove called the dental groove. The gum pads are divided into ten segments by certain grooves called transverse grooves. Each of this segments consist of one developing deciduous tooth sac 14
- 15. The transverse groove between the canine and firs deciduous molar segment is called the lateral sulcus. The sulci is useful in judging the inner-arch relationship at a very early stage. 15
- 16. The upper and lower gum pads are almost similar to each other The upper gum pad is both wider and longer then the mandibular gum pad When the upper and lower gum pads are approximated, there is a complete overjet all around 16
- 17. The contact point of upper and Lower gum pads in first molar region A space exist between them in the anterior region This infantile open bite is normal and it helps n suckling. 17
- 18. NATAL AND NEO NATAL TEETH Very rarely teeth are found to have erupted at the time of birth such teeth are known as natal teeth. Teeth that erupt during the first month of age are called as neonatal teeth The natal and neo natal are mostly located in the mandibular incisor region 18
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- 20. THE DECIDUOUS DENTITION PERIOD 20 •The primary teeth begin to erupt at the age of about 6 month •The eruption of primary teeth is completed by 21/2 - 31/2 years of the age
- 21. Eruption age and sequence of deciduous teeth The timing of the tooth eruption is highly variable, variation of 3 months is accepted as normal Sequence of eruption is A – B – D – C – E Between 3-6 years of age, the dental arch is relatively stable and very few changes occur 21
- 22. SPACING IN THE DECIDUOUS TEETH Spacing usually exist in deciduous teeth This space is known as the physiological or developmental space This space is important for normal development of permanent teeth If space is absent its an indication that crowding of the teeth may occur when permanent teeth erupt 22
- 23. The total space present may vary from 0-8mm with an average of 4mm in maxillary arch 1-7mm in mandibular arch with an average of 3mm 23
- 24. Spacing seen mesial to maxillary canines and distal to the mandibular canines are wider than in other spaces. These physiologic spaces are called Primate Spaces or Simian Spaces. They help in placement of canine cusp of the opposing arch. This space is used for early mesial shift. 24 Primate Spaces or Simian Spaces.
- 25. THE FLUSH TERMINAL The mesio – distal relationship between the destal surface of the upper and lower second deciduous molars is called the terminal plane A normal feature of deciduous dentitions is a flush terminal plane where the distal surface of the upper and lower second deciduous molar are on the same vertical plane 25
- 26. MESIAL STEP Distal surface of mandibular deciduous second molar is mesial to the distal surface of maxillary deciduous second molar. DISTAL STEP Distal surface of mandibular second deciduous molar is more distal to the distal surface of the maxillary second deciduous molar 26
- 27. DEEP BITE A deep bite may occur in the initial stage of development It is prominent by the fact that the deciduous incisor are more upright then their successor The lower incisal edges often contact the cingulum area of the maxillary incisors This deep bite is later reduced by: Eruption of deciduous molars. Attrition of incisors. Forward movement of the mandible due to growth 27
- 29. The mix dentition period begins at approximately 6 years of age with the eruption of the first permanent molars During mixed dentition period, the deciduous teeth along with the permanent teeth are present in the oral cavity 29
- 30. The mixed dentition period can be classified into three phases 1. First transitional period 2. Inter transitional period 3. Second transitional period 30
- 31. FIRST TRANSITION PERIOD The first transitional period is characterized by the emergence of the first permanent molar and exchange of the deciduous incisors with the permanent 31
- 32. Emergence of the first permanent molars Mandibular first moral is the first permanent molar to erupt in the oral cavity at the age of 6. The location and relationship of the permanent molar depends much upon the distal surface relationship between the upper and lower second deciduous molar 32
- 33. The mesio-distal relation between the distal surface of the upper and lower second deciduous molars can be of three types a. Flush terminal plane b. Mesial step terminal plane c. Distal step terminal plane 33
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- 35. A. flush terminal plane The distal surface of the upper and lower second deciduous molars are in vertical plane This type of relationship is called flush or vertical terminal plane. This is a normal feature of the deciduous dentition Thus the erupting first permanent molars may also be in a flush or end on relationship. 35
- 36. For the transition of such an end on molar relation to a class I molar relation the lower molar has to move forward by about 3-5mm relative to the upper molar This occur by utilization of the physiologic spaces and lee way space in the lower arch and by differential forward growth of the mandible 36
- 37. The shift in the lower molar from a flush terminal plane to a class I relation can occur in two ways They are designated as the early and the late shift Early shift occurs during the early mixed dentition period The eruptive force of the first permanent molar is sufficient to push the deciduous first and second molar forward in the arch to close the primate space and there by establish a class I molar relationship 37
- 38. Since this occur early in the mixed dentition therefore it is called early shift Many children lack the primate space and thus the erupting permanent molars are enable to move forward to establish class I relationship In this cases, when the deciduous second molar exfoliate the permanent first molars drift mesially utilizing the leeway space This occur in the late mixed dentition period and thus called late shift. 38
- 39. B. Mesial step terminal plane In this type of relationship distal surface of the lower second deciduous molar is more mesial then that of the upper Thus the permanent molars erupt directly into Angles class I occlusion. This type of mesial step terminal plane most commonly occurs due to early forward growth of the mandible If the differential growth of the mandible in a forward direction persist, it can lead to an Angles class III molar relation 39
- 40. C. Distal step terminal plane This is characterized by the distal surface of the lower second deciduous molar being more distal to that of the upper Thus the erupting permanent molars may be in the Angels class II occlusion 40
- 41. The exchange of incisors During the first transitional period the deciduous incisors are replaced by the permanent incisor. The mandibular CI are usually the first to erupt The permanent incisor are considerably larger then the deciduous teeth they replace 41
- 42. This difference between the amount of space needed for the accommodation of the incisor and the amount of the space available is called incisor liability The incisor liability is roughly about 7mm in the maxillary arch and about 5 mm in the mandibular arch The incisor liability over come by the following factors 42
- 43. a) Utilization of interdental spaces seen in the primary dentition The permanent incisor much more easily accommodated in normal alignment in cases exhibiting adequate interdental spaces then in an arch that has no space 43
- 44. b.) Increase in inter- canine width Significant amount of growth occurs with the eruption of incisors and canines. 44
- 45. c.) change in the incisor inclination One of the difference between deciduous and permanent incisor is there inclination The primary incisors are more upright then the permanent incisors 45
- 46. INTER- TRANSITIONAL PERIOD In this period the maxillary and mandibular arches consist sets of deciduous and permanent teeth This phase during the mixed dentition period is relatively stable and no changes occurs 46
- 47. SECON TRANSITIONAL PERIOD The Second transitional period is characterized by the replacement of the deciduous molars and canine by the premolars and the permanent cuspids respectively The combined mesio-distal width of the permanent canine and the premolars is usually less then that of the deciduous canine and molars. This surplus space is known as the leeways space Nance. 47
- 48. It is greater in the mandibular arch (3.4mm, 1.7mm on each side of the arch) And in maxillary it is 1.8mm that is 0.9mm on each side of the arch After the exchange of the deciduous canine and molars, the space available is utilized for mesial drift of the mandibular molars to establish class I molars relation 48
- 49. THE UGLY DUCKLING STAGE A self correcting malocclusion is seen in the maxillary incisors region between 8-9 years of age This particular situation is seen during the eruption of permanent canines As the permanent canine roots it displaces the root of the lateral incisors mesially, and it results in transmitting the force to CI, which also gets displaced mesially A resultant distal divergence of the crown of the two CI causes a midline spacing 49
- 50. 50 •Crowns of canines in young jaws impinge on developing lateral incisor roots, thus driving the roots medially and causing the crowns to flare laterally.
- 51. The roots of the central incisors are also forced together, thus causing a maxillary midline diastema 51
- 52. With the eruption of the canines, the impingement from the roots shift incisally thus driving the incisor crowns medially, resulting in closure of the diastema as well as the correction of the flared lateral incisors. 52
- 53. This situation is described by Broadbent as the ugly duckling stage This condition corrects by itself when the canines erupt and the pressure is transferred from the roots to the coronal area of the incisors 53
- 54. THE PERMANENT DENTION PERIOD The permanent dentition forms within the jaws soon after the birth, except the first permanent molars that form before birth The permanent incisors develop lingual or palatal to the deciduous incisors and move labially as the erupt The premolars develop below the diverging roots of the deciduous molars 54
- 55. The sequence of eruption in permanent may exhibit variation but most frequently seen in maxillary arch is 6 – 1 – 2 – 4 – 3 – 5 – 7 or 6 – 1 – 2 3 – 4 - 5 – 7 In case or mandibular 6 – 1 – 2 – 3 – 4 -5 – 7 or 6 – 1 – 2 – 4 – 3 – 5 - 7 55
- 56. Changes in Permanent Occlusion 56 Arch dimensional Changes: •Arch length decreases to a surprising amount during the late adolescent period. •Fish found that Mandibular arch perimeter decreases by 5.0mm between 9-16 years whereas maxillary arch perimeter decreased by about half the amount as it was in the mandibular arch.
- 57. Occlusal changes: Both overjet and overbite decreases throughout the second decade of life. It is due to greater forward growth of the mandible and the eruption of permanent molars. Overbite decreases up to the age of 18 years by 0.5mm Overjet decreases by 0.7mm between 12 and 20 years of age. The alveolar process may grow in height beyond 16 years of age. 57
- 58. FACTORS AFFECTING THE DEVELOPMENT OF OCCLUSION GENERAL FACTORS: Skeletal factors: The position, size and relation of bone in which the tooth develops. Muscle factors: The form and function of the muscle which surround the teeth. Dental Factors: The size of the dentition in relation to the size of the jaws. The position and relationship of the teeth within the bone. 58
- 59. LOCAL FACTORS: Aberrant developmental position of teeth The presence of supernumerary teeth. Hypodontia-The congenital absence of certain teeth. The effect of certain Habits. 59
- 60. MALOCCLUSION CAUSING HABITS. Thumb and finger sucking Tongue thrusting &Abnormal swallowing habits Lip and nail biting Mouth breathing Psychogenic habits and bruxism 60