• Abstract and Figures
• Public Full-text

AVERY Chap.06 27-11-2002 10:09 Pagina 108 108 II Development of the Teeth and Supporting Structures 6 Development of the Teeth: Root and Supporting Structures Nagat M. ElNesr and James K. Avery Chapter Outline Introduction Introduction... 108 Objectives... 108 Root development is initiated through the contributions Root Sheath Development... 109 of the cells originating from the enamel organ, dental Single-Root Formation... 110 papilla, and dental follicle. The cells of the outer enamel Multiple-Root Formation... 111 epithelium contact the inner enamel epithelium at the Root Formation Anomalies... 112 base of the enamel organ, the cervical loop (Figs. 6.1 and Fate of the Epithelial Root Sheath (Hertwig's Sheath)... 113 6.2A). Later, with crown completion, the cells of the cer- Dental Follicle... 114 vical loop continue to grow away from the crown and Development of (Intermediate) Cementum... 116 become root sheath cells (Figs. 6.2B and 6.3). The inner Cellular and Acellular Cementum... 116 root sheath cells cause root formation by inducing the Development of the Periodontal Ligament... 117 adjacent cells of the dental papilla to become odonto- Development of the Alveolar Process... 119 blasts, which in turn will form root dentin. The root Summary... 121 sheath will further dictate whether the tooth will have Self-Evaluation Review... 122 single or multiple roots. The remainder of the cells of the dental papilla will then become the cells of the root pulp.The third compo- nent in root formation, the dental follicle, is the tissue that surrounds the enamel organ, the dental papilla, and the root. It will give rise to cells that form the supporting structures of the tooth—that is, the cementum that forms on the surface of the root, the periodontal liga- ment, and the surface layer of the alveolar bone. This bone initially encloses the developing crown of the tooth and later surrounds the roots (Fig. 6.3). It attaches to the periodontal ligament fibers, which also attach to the root by means of the cementum. Objectives After studying this chapter, details of the following top- Fig. 6.1 Formation of cervical loop. ics should be understood: root formation including ori- Outer enamel epithelium Stratum intermedium gin; functions of the root sheath in the initiation of root Stellate reticulum Inner enamel epithelium dentin and intermediate cementum formation; develop- ment of cementum and periodontal ligament; formation of alveolar bone. A B Fig. 6.2 Higher magnification of cervical loop (A) and root sheath (B)..

Load more

  1

Copy Link