DIFFERNCES BETWEEN DECIDUOUS AND PERMANENT TEETH

DIFFERENCES OF THE CROWN Primary Teeth Permanent Teeth Lighter in colour, bluish white/ milk teeth (R.I. is same as milk i.e. 1) Darker in colour, grayish or yellowish white. Duration: 6 months to 5-6 years Duration: 6 years onwards Number: 20 Number: 32 Smaller in dimension Larger in dimension

DIFFERENCES OF THE CROWN Crowns are wider mesiodistally. Crowns are wider cervico incisally Cervical ridges are prominent especially on buccal aspect Cervical ridges are less prominent Narrow occlusal tables Less convergence of buccal and lingual surfaces Sharp cervical constriction Less constriction of the neck

DIFFERENCES OF THE CROWN Enamel is thinner and uniformly thick(1mm). Enamel is about 2-3 mm thick. Contact areas are broader and flatter and gingival. Contact points are more occlusally situated. Enamel rods at the cervical slopes occlusally from DEJ Enamel rods are oriented gingivally Supplemental grooves are more Supplemental grooves are less

DIFFERENCES OF THE CROWN Mammelons absent Mammelons are present on newly erupted teeth First molar is smaller in dimension than second molar First molar is larger in dimension than second molar

DIFFERENCES OF THE ROOT AND PULP

DIFFERENCES OF THE ROOT The roots are larger and slender compared to crown size Roots are more bulbous and shorter in comparison to crown Root trunk is smaller Root trunk is larger Roots flare outward to accommodate permanent teeth Marked flaring is absent Physiologic resorption during shedding Physiologic resorption is absent

DIFFERENCES IN THE PULP Pulp chamber is larger in relation to crown size Pulp chamber is smaller in relation to crown size Pulp horns are more prominent and are closer to the outer surface Pulp horns are comparatively away from the outer surface High degree of cellularity and vascularity in tissue Comparatively less degree of cellularity and vascularity

DIFFERENCES IN THE PULP High potential for repair Less potential for repair Greater thickness of dentin over the pulpal wall at the occlusal fossa of molars Comparitively lesser dentin on the occlusal surface Root canals are ribbon like. Radicular pulp is thin, tortuous and branch. Root canals are well defined with less branching. Floor of pulp chamber is porous. Accessory canals are present in good number Floor of pulp chamber does not have any accessory canals.

HISTOLOGICAL DIFFERENCES Enlarged apical foramen Abundant blood supply demonstrates typical inflammatory response Foramens are restricted Reduced blood supply favours calcific response Reparative dentin formation is more extensive and irregular Reparative dentin formation is less Density of innervation is less of which primary teeth are less sensitive Density of innervation is more Localisation of infection and inflammation is poorer in pulp Inflammation and infection in pulp is localised.

MINERAL CONTENT Enamel and dentin are less mineralized Enamel and dentin are highly mineralized Neonatal lines are present Neonatal lines seen only in first molar Dentinal tubules are less regular Dentinal tubules are more regular Dentin is less dense. It cuts more easily Dentin is difficult to cut as it more dense.

PERIODONTAL DIFFERENCES Cementum is very thin. Secondary cementum is absent The secondary cementum is present Alveolar atrophy is rare Alveolar atrophy occurs Gingivitis is generally absent in healthy child Gingivitis is common in adult.

CLINICAL IMPLICATIONS Cavity cutting Root canal treatment.

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