Ch. 6 (Questions 31-35)

31. What are the developmental disturbances that can occur during
root development?

a. Dilaceration - distorted root or crown angulation in a formed tooth. It results from distortion of Hertwig's epithelial root sheath (HERS) caused by injury or pressure.
b. Accessory roots (supernumerary roots) - may due to trauma, pressure, or metabolic disease that affects HERS. Any tooth may be affected, but it occurs mainly with the permanent third molars and is rare in incisors.

32. Discuss the process of cementogenesis.

The cementoblasts move to over the rooot dentin area and undergo cementogenesis, laying down cementum matrix, or cementoid. Unlike ameloblasts and odontoblasts, which leave no cellular bodies in their secreted products, many cementoblasts become entrapped by the cementum they produce and become mature cementocytes in the later stages of apposition. As the cementoid surrounding the cementocytes becomes calcified, or matured, it is then considered cementum.

33. Where is the dentinocemental junction located, and what is its relationship to the pulp and other related tissues?

Junction between the dentin and cementum during the formation of the root of the tooth. At the time of the dentinocemental junction is formed, the central cells of the dental papilla are forming into the pulp. The pulp tissue is surrounded by the newly formed dentin.

34. How does the periodontal ligament develop?

The ectomesenchyme from the dental sac begins to form the periodontal ligament (PDL) adjacent to the newly formed cementum. This process involves forming collagen fibers that are immediately organized into the fiber bundles of the PDL.

35. How does the alveolar bone develop?

The ectomesenchyme of the dental sac also begins to mineralize to form the tooth socket or alveoli of the alveolar bone surrounding the PDL.