1.PEDODONTICSDEVELOPMENT AND MORPHOLOGYOF THE TEETH AND OCCLUSION1 Dr. Amal A. A. Kader Pediatric Dentist

2. DEVELOPMENT AND MORPHOLOGYOF THE TEETH AND OCCLUSIONIntroduction -Calcification -Importance of Primary teeth -Eruption -Principal morphological characteristics of primary teeth -Morphologic differences between primary and permanent teeth -Normal occlusion in children - 2 3. The developmentof the human toothcan be observedas early as the sixth week. of embryonic life 3 4. Calcification All primary teethAt birth and 6months 6 and 3 1 year 1 2years 2 4years 3 and 7 5years 9 8 4 5. Importance of Primary TeethPreparation of the food for digestion and assimilation . 1Maintenance of space for the permanent teeth . 2Helps to growth and development of the jaws . 3Helps to the development of speech . 4Aesthetic function . 55 6. ERUPTION Each tooth stars to move towards occlusionat the time of crown completion and beginning of root formationPre-eruptive phase: in which the tooth root begins its formation . 1. and begins to move toward the surface of the oral cavityEruptive phase: is the time of gingival emergence, and about or . 2. the root is formed 2/36 7. ERUPTION Age 6 12 18 24 30monthsToothA B D C E 7 8. Calcification EruptionAll primaryAgeAt birth teeth and 6Tooth((monthsmonths 6 and 3 1 A 6 B12 year 1 2 D18years 24 C24years 3and 7 5 E 36 -30years 9 8 8 9. ERUPTIONPermanent DentitionUpper 6 1 2 4 5 37Tooth 6 7 8 9 1011 12Lower 6 1 2 3 4 579 10. Principal Morphological Characteristics of individual primary teeth10 11. Maxillary Incisors The mesiodistal diameter of the crown of the maxillarycentral incisor is greater than the cervicoincisal lengt The maxillary lateral incisor crown is smaller in all dimensions and the length of the crown is greater. than the mesiodistal width11 12. CanineThe crown of the maxillary canine is more constricted. at the cervical region than are the incisorsThe canine root is more than twice the length of the. crown12 13. First maxillary primary molarThe mesiolingual cusp of the maxillary first molar isthe largest and sharpestThe distolingual cusp is poorly defined, small and rounded13 14. Second maxillary primary molarThere is considerable resemblance between themaxillary primary second molar and themaxillary. first permanent molarThere are two well-defined buccal cusps, with adevelopmental groove between. themThe crown of the second molar is considerably larger. than that of the first molar 14 15. First mandibular primary molarThe mandibular first primary molar doest not resemble. any of the permanent teeth; The mandibular first molar has two buccal cusps. the mesial cusp is the larger of the two15 16. Second mandibular primary molarThe mandibular second molar resembles the mandibular first permanent molarOne of differencebetween the crowns of the primarymolar and that of the first permanent molar is in thedistobuccal cusp because the distal cusp of the permanent molar is smaller than the others two buccal cusps16 17. Morphological differences between primary andpermanent teeth Number: 20 Color: White 17 18. Morphological differences between primary andpermanent teeth: SizePrimary teeth are smallerin all dimensionsThe mesiodistal width of primaryincisors and canines is less The mesiodistal width of primarymolars is wider than their premolarssuccesorsThe thickness of enamel and dentine in primary teeth is approximately halfIts thickness in permanent teeth 18 19. Morphological differences between primary andpermanent teeth Crowns The crowns of the primary teeth are wider mesiodistallyThe cervical ridge of enamel at the cervical third of the anterior crowns is much moreprominent labially and lingually The buccal and lingual surfaces of primary molars converge sharply toward the occlusal surface, forming a narrow occlusal table19 20. Morphological differences between primary andpermanent teeth Crowns The crowns of primary molars are bulbous due to their markedly constricted necks and pronounced cervical ridges on the buccal aspect especially in the maxillary and mandibular first molarsThe enamel cap in primary teeth is thinner and has nearly a constant depth throughout the crownThe enamel cap in primary molars ends abruptly at the cement enamel junction 20 21. Morphological differences between primary andpermanent teethCrownsThe enamel rods at the cervix slopeocclusally in primary teeth instead ofbeing oriented gingivally as in permanentteeth The interproximal contact betweenprimary molars is not a small roundarea as in permanent molars but tendsto be a large ellipsoid and flattened area 21 22. Morphological differences between primary andpermanent teethRoots The roots of primary anterior teeth are narrower mesiodistallyThe roots of the primary molars arerelatively longer and more slender22 23. Morphological differences between primary andpermanent teeth Pulp The pulp chambers are large The pulp horns are higher in primary .molars, especially the mesial pulp hornThe root canals of primary molarsshow more lateral branchings and apical ramifications Apical foraminae in primary teeth is relatively wider The pulp chamber will decrease in size with an increase in age 23 24. Morphological differences between primary andpermanent teethIncisor spacingPrimate spacesOverjet: 0Overbite: Can be edge to edge until acomplete crownSpee curve: There is not24 25. Normal Occlusion in childrenOcclusion at 3 yearsStraight or flush terminal plane Mesial step Distal step25 26. Normal Occlusion in childrenOcclusion at 6 years 26 27. Normal Occlusion in children Occlusion at 8 to 9 yearsWith the eruption of the upper and lowerpermanent incisors there is an increase indepth of overbite 27 28. Normal Occlusion in children Occlusion at 8 to 9 years,Diastema between upper permanent central incisors( which is normal for this age (ugly duckling stage 28 29. Normal Occlusion in childrenOcclusion at 8 to 9 years,Diastema between upper permanent central incisors( which is normal for this age (ugly duckling stage29 30. Normal Occlusion in children Occlusion at 10 to 12 yearsWith the eruption of premolars, the vertical dimensionis increased which corrects the deep overbiteClosure of Leeway spaces 30 31. Normal Occlusion in childrenOcclusion at 10 to 12 yearsDiastema between upper centralincisors is closed , With the eruption of premolars the vertical dimension is increasedwhich corrects the deep overbite Closure of Leeway spaces 31 32. 32