9/12/2023 0 Comments Molar teeth numbersThe position of the incisors is usually relatively upright with spacing often between them. The primary dentition is complete at about 2.5 years of age, and no obvious intraoral changes in the dentition occur ( Figures 3-4 and 3-5) until the eruption of the first permanent molar. It comes in immediately distal to the primary second molar (see Figure 2-10). The first permanent molar, commonly called the 6-year molar, makes its appearance in the mouth before any of the primary teeth are lost. Premature loss of primary teeth because of dental caries is preventable and is to be avoided. It is emphasized again that they are needed for many years of growth and physical development. These terms are improper because they foster the implication that these teeth are useful for a short period only. The primary teeth have been called temporary, milk, or baby teeth. (From Ash MM, Ramfjord S: Occlusion, ed 4, Philadelphia, 1995, Saunders.) Beginning with the median line, the teeth are named in each jaw on each side of the mouth as follows: central incisor, lateral incisor, canine, first molar, and second molar.į igure 3-3 Universal numbering system for primary dentition. Figure 3-3 shows the primary dentition as numbered with the universal system of notation described in Chapter 1. The primary teeth number 20 total-10 in each jaw-and they are classified as follows: four incisors, two canines, and four molars in each jaw. It is only 1 or 2 years after the root is completely formed and the apical foramen is established that resorption begins at the apical extremity and continues in the direction of the crown until resorption of the entire root has taken place and the crown is lost from lack of support. This does not, however, indicate the period at which the root resorption of the deciduous tooth begins. The process of exfoliation of the primary teeth takes place between the seventh and the twelfth years. Some of the terminology for the primary dentition has already been introduced in Chapter 2 therefore the coverage here is more in the nature of a review. The development of the primary occlusion is considered in Chapter 16. Therefore in this book the primary teeth are described in advance of the permanent dentition so that they may be given their proper sequence in the study of dental anatomy and physiology. Thus there should be no question of the importance of preventing and treating dental decay and providing the child with a comfortable functional occlusion of the deciduous teeth. The development of adequate spacing ( Figure 3-2) is an important factor in the development of normal occlusal relations in the permanent dentition. Although dental caries of the primary dentition and loss of these teeth are sometimes thought of erroneously as only an annoyance, this belief fails to acknowledge the role of the primary teeth in mastication and their function in maintaining the space for eruption of the permanent teeth.Ī lack of space associated with premature loss of deciduous teeth is a significant factor in the development of malocclusion and is considered in Chapter 16. However, the relative susceptibility of different tooth surfaces is a complex problem. The increase in prevalence of dental caries among tooth types is the reverse of their order of eruption. The susceptibility to dental caries is a function of exposure time to the oral environment and morphological type. The high peak for caries attack occurs at age 13, when only 5% of the primary teeth remain. (Modified from McBeath EC: New concept of the development and calcification of the teeth, J Am Dent Assoc 23:675, 1936 and Noyes EB, Shour I, Noyes HJ: Dental histology and embryology, ed 5, Philadelphia, 1938, Lea & Febiger.) ![]() Eruption is completed at the approximate time indicated by the dotted area on the roots of the teeth. F igure 3-1 Diagrammatic representation of the chronology of the primary teeth.
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