Normal development of occlusion part 1
- 1. DR. MAHER FOUDA PROFESSOR OF ORTHODONTICS NORMA DEVELOPMENT OF OCCLUSION
- 4. PRIMARY DENTITION Eruption age & sequence of deciduous dentition Spacing in deciduous dentition MIXED DANTITION First transitional period Inter – transitional period Second transitional period The Leeway spaces The ugly duckling stage PERMANENT DENTITION SELF CORRECTING TRANSIENT MALOCCLUSION Contents
- 6. THE PRIMARY DENTITION The initiation of primary tooth buds occurs during the first 6 weeks of intra-uterine life. primate space The primary teeth begin to erupt at the age of about 6 months.
- 7. The eruption of all primary teeth is completed by 2.5 - 3.5 years of age when the second deciduous molars come into occlusion.
- 8. ERUPTION AGE & SEQUENCE OF DECIDUOUS DENTITION The mandibular central incisors are the first teeth to erupt into the oral cavity. They erupt around 6-7 months of age.
- 9. THE SEQUENCE OF ERUPTION OF THE DECIDUOUS DENTITION Central Incisors ( 6 - 8 Mo) Lateral Incisors ( 6 - 10 Mo) Canines ( 16 - 20 mo) First Molars ( 10 - 15 Mo) Second Molars (2.5- 3.5 yrs ) The four front teeth-two upper and two lower usually erupt first, beginning as early as six months after birth. Usual Order of Appearance:
- 10. Between 3 - 6 years of age, the dental arch is relatively stable & very few changes occur.
- 11. SPACING IN DECIDUOUS DENTITION Spacing usually exists between the deciduous teeth. These spaces are called Physiological spaces or Developmental spaces Spacing in deciduous Dentition
- 12. Localized spaces like primate space are also seen Generalized spacing occurs in almost 2/3 of the children, referred to as physiological spaces or developmental spaces In primary dentition stage, a child may have generalized spacing; no spacing; localized spacing or crowded dentition. primate space Primary Spacing
- 14. Spaces present mesial to upper canines and distal to lower canines in human primary dentition Primate / anthropoid / Simian spaces
- 15. SPACES BETWEEN THE TEETH Spaced dentition Non-Spaced dentition Primate spaces Physiologic spaces Indicates crowding in developing permanent dentition.
- 16. Spaced dentition spaces in between the teeth can be utilized for adjustment of permanent successors, which are always larger in size compared to the deciduous teeth. The spaces present are of two types : Primate spaces Primate spaces Primate spaces Primate spaces i. Primate spaces - Exist between the upper lateral incisors and the canines and lower canines and first deciduous molars.
- 17. ii. Physiologic spaces - Present in between the primary teeth and play an important role in normal development of the permanent dentition Spaced dentition Physiologic spaces
- 18. Lack of space between primary teeth either due to small jaw or larger teeth. Non-Spaced dentition Non-Spaced dentition
- 19. DEEP BITE A deep bite may occur in the Initial Stages of development. The deep bite is accentuated by the fact that the deciduous incisors are more upright than their successors. The lower incisal edges often contact the cingula of the maxillary incisors. Deep bite
- 20. DEEP BITE This deep bite is later Reduced due to the following factors: • Eruption of deciduous molars. • Attrition of incisors. • Forward movement of the mandible due to growth. Deep bite
- 21. DECIDUOUS DENTITION SUMMARY Spacing usually exists between the deciduous teeth. A normal feature of deciduous dentition is a Flush Terminal Plane A deep bite may occur in the initial stages of development.
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- 23. PRIMARY DENTITION Eruption age & sequence of deciduous dentition Spacing in deciduous dentition MIXED DANTITION First transitional period Inter – transitional period Second transitional period The Leeway spaces The ugly duckling stage PERMANENT DENTITION SELF CORRECTING TRANSIENT MALOCCLUSION Contents
- 25. THE MIXED DENTITION The mixed dentition period begins at approximately 6 years of age with the eruption of the first permanent molars. During the mixed dentition period, the primary along with deciduous teeth are present in the oral cavity.
- 26. CLINICAL FEATURES OF MIXED DENTITION PERIOD
- 28. THE MIXED DENTITION PERIOD The mixed dentition period can be classified into three phases First transitional period Inter-transitional period Second transitional period
- 30. The first transitional period is characterized by : FIRST TRANSITIONAL PERIOD 1. The emergence of the first permanent molars. 2 . The exchange of the deciduous incisors with the permanent incisors
- 31. EMERGENCE OF THE FIRST PERMANENT MOLARS The mandibular first molar is the first permanent tooth to erupt at around 6 years of age
- 32. The location & relationship of the first permanent molars depend much upon the DISTAL SURFACE relationship between the lower & upper second deciduous molars. EMERGENCE OF THE FIRST PERMANENT MOLARS
- 33. FLUSH PLANE TYPE MESIAL STEP TYPE DISTAL STEP TYPE TYPES OF TERMINAL PLANES
- 34. Mesial step terminal plane (14%): The distal surface of the lower molar is more mesial to that of the upper molar Invariably, this guides the permanent molars into a class I relationship. The distal surfaces of the upper and lower teeth are in straight plane and therefore situated on the same vertical plane. It is usually the most favorable relationship to guide permanent molars into class I The distal surface of the lower molar is more distal to that of the upper molar. This relationship is unfavorable as it guides permanent molars into distal occlusion Flush Terminal Plane (74%): Distal step terminal plane (10%):
- 37. FLUSH TERMINAL PLANE When the distal surfaces of maxillary and mandibular deciduous second molars are in the same vertical plane, this is the normal molar relationship in the primary dentition because the mesiodistal width of mandibular molar is greater than maxillary molar. The same vertical planeThe same vertical plane
- 38. FLUSH TERMINAL PLANE CLASS I MOLAR For such transition: The lower molar has to move forward by about 3 - 5 mm relative to the upper molar.
- 39. FLUSH TERMINAL PLANE CLASS I MOLAR This occurs by: (1) Utilization of the physiological spaces & leeway space in the lower arch. (2) By differential forward growth of the mandible. Primate Spaces
- 40. FLUSH TERMINAL PLANE CLASS I MOLAR & The shift in lower molar can occur in two ways They are designated as the Early Shift Late Shift Shift: Refers to mandibular permanent molar moving mesially
- 41. Since this occur early in the mixed dentition period it is called early shift. The eruptive force of the first permanent molar is sufficient to push the deciduous first & second molars forward in the arch to close the primate spaces. Early Mesial shift
- 42. o Many children lack the primate spaces & thus the erupting permanent molars are unable to move forward to establish Class I relationship. o In these cases, when the deciduous second molars exfoliate, the permanent first molars DRIFT MESIALLY utilizing The leeway space.
- 43. This occurs in the late mixed dentition period & is thus called late shift. Late Mesial shift
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- 45. MESIAL STEP
- 46. MESIAL STEP In this type of relationship the Distal Surface of the lower second deciduous molar is more Mesial than that of the upper. Thus the permanent molars erupt directly into Angle’s Class I occlusion
- 47. MESIAL STEP This type of mesial step terminal plane most commonly occurs due to: EARLY FORWARD GROWTH OF THE MANDIBLE
- 48. If the differential growth of the mandible in a forward direction persists, it can lead to an Angle’s Class III molar relation. If the forward mandibular growth is minimal, it can establish a Class I molar relationship. MESIAL STEP
- 49. DISTAL STEP
- 50. This is characterized by the Distal Surface of the lower second deciduous molar being more DISTAL to that of the upper DISTAL STEP
- 51. The erupting permanent molars maybe in Angle’s Class II occlusion DISTAL STEP
- 53. The first transitional period is characterized by : First transitional period (Cont.) 1. The emergence of the first permanent molars. 2. The exchange of the deciduous incisors with the permanent incisors
- 54. THE EXCHANGE OF THE DECIDUOUS INCISORS WITH THE PERMANENT INCISORS During the first transitional period: The deciduous incisors are replaced by the permanent incisors The permanent incisors are considerably larger than the deciduous teeth they replace.
- 55. The mandibular central incisors are usually the first to erupt.
- 56. The crowns of the permanent incisors (red) lie lingual to the crowns of the primary incisors (black), particularly in the case of the maxillary laterals. Arrows point to the primate spaces
- 57. The crowns of the permanent incisors lie lingual to the crowns of the primary incisors
- 58. THE EXCHANGE OF THE DECIDUOUS INCISORS WITH THE PERMANENT INCISORS This difference between the amount of space needed for the accommodation of the incisors & amount of space available for this is called “INCISAL LIABILITY” 7 mm in upper arch 5 mm in lower arch
- 59. OVERCOMING INCISAL LIABILITY The incisal liability is overcome by the following factors: A. Utilization of interdental spaces seen in primary dentition. B. Increase in the inter- canine width. C. Change in incisor inclination
- 60. The permanent incisors are much more easily accommodated in normal alignment in cases exhibiting Adequate Inter-dental Spaces than in cases with no spacing OVERCOMING INCISAL LIABILITY
- 61. • Mandibular intercanine growth: occurs mostly during permanent incisor eruption. • Maxillary intercanine growth: occurs during incisor eruption, and continues. WIDTH GROWTH creates more room for the permanent incisors OVERCOMING INCISAL LIABILITY B. INCREASE IN THE INTER - CANINE WIDTH
- 62. One of the differences between deciduous & permanent incisors is their inclination The primary incisors are more upright than the permanent incisors OVERCOMING INCISAL LIABILITY C. CHANGE IN INCISOR INCLINATION
- 63. Since the permanent incisors erupt more labially inclined they tend to increase the Dental Arch Perimeter This is another factor that helps in accommodating the larger permanent incisors OVERCOMING INCISAL LIABILITY C. CHANGE IN INCISOR INCLINATION
- 64. THE MIXED DENTITION PERIOD (CONT. ) The mixed dentition period can be classified into three phases First transitional period Inter-transitional period Second transitional period
- 65. Inter-transitional period After the completion of eruption of 1st molars and incisors, there is a silent period extend from 8.5 to 10 years of age, during which there is no teeth eruption or exfoliation, except a little changes in occlusion. The teeth present are : 6EDC21 12CDE6 6EDC21 12CDE6
- 67. THE MIXED DENTITION PERIOD (CONT. ) The mixed dentition period can be classified into three phases First transitional period Inter-transitional period Second transitional period
- 69. THE SECOND TRANSITIONAL PERIOD The second transitional period is characterized by the replacement of the deciduous molars & canines by the premolars & permanent cuspids respectively. The combined mesio-distal width of the permanent canines & premolars is usually less than that of the deciduous canines & molars The surplus is called leeway space of Nance
- 70. THE LEEWAY SPACE The amount of leeway space is greater in the mandibular arch than in the maxillary arch. Maxillary arch 1.8mm (0.9 mm on each side of the arch) Mandibular arch 3 .4mm (1.7 mm on each side of the arch)
- 71. Maxillary c-d-e minus 3-4-5 is 0.9 mm per side Mandibular c-d-e minus 3-4-5 is 1.7 mm per side THE LEEWAY SPACE
- 72. THE LEEWAY SPACE
- 73. LEEWAY SPACE The normal leeway according to Moyers is 2.6 mm in the maxilla and 6.2 mm in the mandible. However, this varies considerably and should be measured in each patient.
- 74. THE UGLY DUCKLING STAGE Sometimes a Transient or Self Correcting malocclusion is seen in the MAXILLARY INCISOR REGION between 8 - 9 years of age. This is a particular situation seen during the Eruption of the permanent canines
- 75. As the developing permanent canines erupt, they displace the roots of the lateral incisors mesially. This result in transmitting the force on to the roots of the central incisors which also get displaced mesially. THE UGLY DUCKLING STAGE
- 76. A resultant distal divergence of the crowns of the two central incisors causes a midline spacing. This situation has been described by Broadbent as the ugly duckling stage as children tend to look ugly during this phase of development. THE UGLY DUCKLING STAGE
- 77. Parents are often apprehensive during this stage & consult the dentist. This condition usually corrects by itself when the canines erupt & the pressure is transferred from the roots to the coronal area of the incisors. THE UGLY DUCKLING STAGE
- 80. NORMAL POSITION OF MAXILLARY CANINE TOOTH BUD FORMATION Almost never congenitally missing Often see simultaneous closure of a maxillary central incisor diastema Continues to erupt into the oral cavity labial to the resorbing deciduous cuspid Changes to a more vertical orientation when it engages the distal aspect of the lateral incisor root It starts out lingual to the arch and mesially directed Buccal to the developing lateral incisor and 1st bicuspid buds
- 81. Normal Position of Maxillary Canine Tooth .
- 82. NORMAL ERUPTION PATTERN OF THE MAXILLARY CANINE
- 83. NORMAL ERUPTION PATTERN OF THE MAXILLARY CANINE
- 84. NORMAL ERUPTION PATTERN OF THE MAXILLARY CANINE
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- 86. PRIMARY DENTITION Eruption age & sequence of deciduous dentition Spacing in deciduous dentition MIXED DANTITION First transitional period Inter – transitional period Second transitional period The Leeway spaces The ugly duckling stage PERMANENT DENTITION SELF CORRECTING TRANSIENT MALOCCLUSION Contents
- 88. THE PERMANENT DENTITION PERIOD • The permanent dentition forms within the jaws soon after birth, except the cusps of the first permanent molars which form before birth • The permanent incisors develop lingual or palatal to the deciduous incisors & move labially as they erupt
- 89. THE PERMANENT DENTITION PERIOD • The premolars develop below the diverging roots of the deciduous molars • The eruption sequence of the permanent dentition may exhibit variation
- 90. The frequently seen sequence in the maxillary arch is: 6 - 1 - 2 - 4 - 5 - 3 - 7 In case of the mandibular arch, the sequence is 6 - 1 - 2 - 3 - 4 - 5 - 7 THE PERMANENT DENTITION PERIOD
- 91. ESSENTIAL FACTORS FOR A SMOOTH TRANSITION FROM PRIMARY TO PERMANENT DENTITION Primate Spaces Generalized Spacing Preservation of leeway spaces Favorable sequence of eruption Tooth size and jaw in harmony
- 93. PRIMARY DENTITION Eruption age & sequence of deciduous dentition Spacing in deciduous dentition MIXED DANTITION First transitional period Inter – transitional period Second transitional period The Leeway spaces The ugly duckling stage PERMANENT DENTITION SELF CORRECTING TRANSIENT MALOCCLUSION Contents
- 95. Primary Dentition • Deep bite: corrected by i.eruption of primary molar ii.attrition of incisal edges. • Increased overjet: corrected by i. More forward growth of the mandible ii. Early mesial shift iii. Spacing closes with eruption of permanent successors . SELF-CORRECTING OR TRANSIENT MALOCCLUSIONS AND REASONS FOR SELF-CORRECTION
- 96. SELF-CORRECTING OR TRANSIENT MALOCCLUSIONS AND REASONS FOR SELF-CORRECTION Deep bite: corrected by physiologic bite raisers at 6 and 12 years with the eruption of the first and second permanent molars. The overlying gingival pad of tissue will act as bite raiser. Ugly duckling stage: corrected by eruption of maxillary canine Lower anterior crowding: corrected by increase in intercanine width End on molar relationship : corrected by late mesial shift Edge-to-edge at about 6 years of age flush terminal plane relationship: corrected by both late mesial shift and differential jaw growth MIXED DENTITION
- 97. Primary occlusion at 5 years Note the generalized interdental spacing, primate spaces (distal to lateral incisors in the maxilla and distal to cuspids in the mandible), moderate overbite and overjet, and flush terminal plane.
- 98. Occlusion at 6 years Note diminished overbite and overjet and beginning of a mesial step at the distal surfaces of the primary molars.
- 99. Occlusion at 7 years All first molars and central and lateral incisors have erupted. A distinct mesial step has permitted Class I interdigitation of the permanent molars, and the erupting incisors have closed the primate spaces in both arches.
- 100. Occlusion at 8 years Ordinarily, the mandibular lateral incisors erupt into the line of arch, completing closure of the primate spaces. Note interdental spacing in the maxillary incisor region. The permanent molars have a firm Class I occlusion by this age if a mesial step has been available at the time of their eruption.
- 101. Occlusion at 9 years Mandibular permanent cuspids have erupted in this case. Although this is desirable, often the mandibular cuspid and first bicuspid arrive almost simultaneously.
- 102. Occlusion at 10 years First bicuspids are erupted and maxillary permanent cuspids are appearing. In most mouths, the maxillary second bicuspids erupt before the cuspids.
- 103. Occlusion at 11 years Interdental spacing in the maxillary incisor region has been closed by eruption of the cuspids, and one second bicuspid has appeared in each arch. Eruption of second molars in the mandible at this time is not the most favorable sequence; it is better if they are delayed until all bicuspids have erupted.
- 104. Occlusion at 12 years All permanent teeth except the third molars are in position. Note absence of any interdental spacing and the slight tendency to procumbency of the dentition. The procumbency typical of the recently completed dentition seems to diminish soon unless there is gross discrepancy between the size of the teeth and the alveolar perimeter.
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