DIFFERENCE BETWEEN PRIMARY AND

PERMANENT TEETHDr. Amitha G

Dept of Oral pathology

Major Contrasts between Primary and Permanent Teeth In comparison with their counterparts in the permanent dentition,• Primary teeth are smaller in overall size and crown

dimensions. • They have markedly more prominent cervical ridges• Narrower at their “necks,” • Lighter in color• Have roots that are more widely flared• Buccolingual diameter of primary molar teeth is less than that

of permanent teeth

More specifically, in comparison with permanent teeth, the following differences are noted: •

The crowns of primary anterior teeth are wider mesiodistally in comparison with their crown length than are the permanent teeth.

• The roots of primary anterior teeth are narrower and longer comparatively.

• Narrow roots with wide crowns present an arrangement at the cervical third of crown and root that differs markedly from that of the permanent anterior teeth

3. The roots of the primary molars accordingly are longer and more slender and flare more, extending out beyond projected outlines of the crowns. This flare allows more room between the roots for the development of permanent tooth crowns

4. The cervical ridges of enamel of the anterior teeth are more prominent. These bulges must be considered seriously when they are involved in any operative procedure 5. The crowns and roots of primary molars at their cervical portions are more slender mesiodistally.

6. The cervical ridges buccally on the primary molars are much more pronounced, especially on the maxillary and mandibular first molars

7. The buccal and lingual surfaces of primary molars are flatter above the cervical curvatures than those of permanent molars, which narrows the occlusal surfaces.

8. The primary teeth are usually less pigmented and are whiter in appearance than the permanent teeth.

Pulp Chambers and Pulp Canals

A comparison of sections of primary and permanent teeth demonstrates the shape and relative size of pulp chambers and canals which is noted here:

1. Crown widths in all directions are large in comparison with root trunks and cervices. 2. The enamel is relatively thin and has a consistent depth. 3. The dentin thickness between the pulp chambers and the enamel is limited, particularly in some areas (lower second primary molar).4. The pulp horns are high, and the pulp chambers are large 5. Primary roots are narrow and long when compared with crown width and length

Comparison of maxillary, primary, and permanent second molars, linguobuccal cross section.

1. The enamel cap of primary molars is thinner and has a more consistent depth.

2. Comparatively greater thickness of dentin is over the pulpal wall at the occlusal fossa of primary molars.

3. The pulpal horns are higher in primary molars, especially the mesial horns, and pulp chambers are proportionately larger.

4. The cervical ridges are more pronounced, especially on the buccal aspect of the first primary molars.

1. The enamel rods at the cervix slope occlusally instead of gingivally as in the permanent teeth.

2. The primary molars have a markedly constricted neck compared with the permanent molars.

3. The roots of the primary teeth are longer and more slender in comparison with crown size than those of the permanent teeth.

4. The roots of the primary molars flare out nearer the cervix than do those of the permanent teeth.

Thankyou

Reference:Wheelers – Dental Anotomy, Physiology and Occlusion- 9th edition.