FUNCTIONS OF MILKY DENTITION DIFFERENCES BETWEEN PRIMARY AND PERMANENT TEETH 5 D M

Transcription

1 FUNCTIONS OF MILKY DENTITION DIFFERENCES BETWEEN PRIMARY AND PERMANENT TEETH 5 D M

2 FUNCTIONS OF THE DECIDUOUS DENTITION 1. bitting off and mastication of food 2. keeping the space for permanent dentition 3. suporting the growth of the jaws 4. correct articulation and phonatory function 5. esthetic function

3 1. MASTICATORY FUNCTION shape of the particular types of teeth position in the dental arch...consistent with masticatory function incisors bitting off canines (cuspids) terminate the separation molars - mastication

4 MASTICATORY FUNCTION bitting enabled by reciprocal location of upper and lower Incisors the relation termed as scissors-shape bite (psalidodontia) the cutting edges of the lower incisors sliding on the palatal side of upper incisors Canines serve as teeth keeping the food in the position and terminating the separation Molars serve as masticatory teeth, with cusps, groves and masticatory surfaces

5 MASTICATORY FUNCTION deffective intermaxillary position - limited function open bite, edge-to-edge (labiodontia) reduction or impossibility of bitting off a morsel Support of mastication also from: masticatory muscles, lips, tongue, cheeks and saliva

6 2. KEEPING THE SPACE FOR PERMANENT DENTITION milky teeth serve as physiologic (natural) space maintainer early loss can lead into PD eruption disturbances

7 3. SUPORTING THE GROWTH OF THE JAWS Complete and healthy milky dentition under functional load (masticatory forces) supports normal growth of the jaws

8 4. PHONATORY FUNCTION important prerequisite for correct articulation: harmonically formed dental arches complete dentition, mainly frontal section normal intermaxillary position

9 5. ESTHETIC FUNCTION up-to-lately...rather neglected important from psychological point of view plays a serious part in ensuring of the optimal development of both physical and psychological qualities of the developing organism

10 OVERALL FUNCTIONING OF MD Milky dentition though having limited time of function is very important for harmonious development of orofacial system and has influence on general health status For that reason a healthy kid is considered a kid with caries-free milky dentition or fully restored MD

11 DIFFERENCIES BETWEEN DECIDUOUS (MT) AND PERMANENT TEETH (PT) 1. Time of development and eruption 2. Number (no premolars, no 3rd molars) 3. Colour - MT are whiter 4. Size 5. HDT thinner and less mineralized in MT 6. Wider dentine tubules in MT 7. Crowns of MT have enamel thickening around neck area cingulum

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13 DIFFERENCIES BETWEEN DECIDUOUS (MT) AND PERMANENT TEETH (PT) 8. MT large pulp chamber, prominent horns 9. MT roots relatively longer (in comparison with crowns and ratio in PT), thinner and more divergent, thin root canals in molars 10. But - Root canals of frontal MT in comparison to frontal PT are wider 11. Roots of milky molars are divergent in coronal third and convergent in the apical third - MT apexes of the roots tend/incline to the long axis of the tooth

14 DIFFERENCIES BETWEEN DECIDUOUS (MT) AND PERMANENT TEETH (PT) 12. Vestibular surfaces of MT are more convex - bulbous crown 13. MT - Thick enamel ridges on occlusal surface 14. The curve of Spee is not described in MD 15. Long axes of MT are paralel and placed at the right angle to the occlusal plane 16. Spaces in MD physiologic (teeth i2 a c in Mx, and c and m1 in Mn)

15 DIFFERENCIES BETWEEN DECIDUOUS (MT) AND PERMANENT TEETH (PT) 17. MT occlusal surface of m1 narrower than m2 18. MT contact area broader 19. Cervical diameter of crowns of MT is wider than occlusal diameter 20. Mesiodistal distance of MT crowns is bigger than cervicooclusal distance 21. Enamel prisms in cervical area are oriented horizontaly or even oclusaly

16 DIFFERENCIES BETWEEN DECIDUOUS (MT) AND PERMANENT TEETH (PT) MT resorption of the roots elimination MT are smaller in all dimensions MT crowns are wider in mesiodistal diameter vs.cervicooclussal height MT cervical ridges more pronounced MT buccal and lingual surfaces converge toward the occlusal surface

17 DIFFERENCIES MILKY INCISORS smaller in all directions then permanent chisel shape large pulpal cavity in the crown enamel thickness 0.3 mm dentine from 1.3 to 1.5mm roots long, oval shape, multiple ramifications in the apical third

18 DIFFERENCIES MILKY CANINES similar quadrangular shape of crown like permanent resemblance to the permanent tooth crown is obvious (cuspis abrasion) large pulpal cavity in the crown enamel thickness 0.5 mm, dentine from 1.7 to 2.0mm root long

19 DIFFERENCIES 1st MILKY MOLAR shape does not resemble any other tooth occlusal surface of the upper has a trapezoid shape, the base placed vestibular (2 vestibular cusps, 2 palatal) occlusal surface of the lower is square (2 vestibular cusps, 2 linqual) bucolingual crest large pulpal cavity in the crown enamel thickness mm, dentine from 1.6 to 1.9mm roots 3Mx 2Mn

20 DIFFERENCIES 2nd MILKY MOLAR Mx resembles 1st permanent molar roots thinner and more divergent occlusal surface 4 cusps Mx, 5cusps Mn prominent bulge on cervical part of buccal surface large pulpal cavity in the crown enamel thickness 0.3 mm, dentine from 1.8 to 2.3mm roots 3Mx 2Mn, bifurcation just below the cervical margin