. The science and practice of dental surgery. e Jaws and Teeth.—Itnow Icmains to trace the growtii of the jawsand teeth during tlie period of eruption ofthe second dentition, i. e. between the sixthand thirteenth years. The laying down ofbone on the outer surface of the body of themandible and on the posterior surface of its 30 ascending ramus continues, and the angle ofthe jaw becomes more massive and muscles attached to the jaw, by exertingtraction, open out its curvatures and develop bone of attachment . The tongue, possess-ing in addition independent movement, actsas a dilati
. The science and practice of dental surgery. e Jaws and Teeth.—Itnow Icmains to trace the growtii of the jawsand teeth during tlie period of eruption ofthe second dentition, i. e. between the sixthand thirteenth years. The laying down ofbone on the outer surface of the body of themandible and on the posterior surface of its 30 ascending ramus continues, and the angle ofthe jaw becomes more massive and muscles attached to the jaw, by exertingtraction, open out its curvatures and develop bone of attachment . The tongue, possess-ing in addition independent movement, actsas a dilating force in moulding the bony anddental arches. The jaws are further developedby carrying out the functions they subserve,e. g. mastication, deglutition, speech, and re-spiration. The increase of bone substance isproduced chiefly from the enclosing periosteum,in other words, subperiosteal or parostealgro\vth as opposed to interstitial or endostealgrowth. In the upper jaw a few other factorsare instrumental in its development; efficient Dii. PMx Fig. 44.—Showing the development of the maxillarysinus and its influence on the growth of themaxilla and on the position of the teeth (afterKeith). i, i^, c, ml, m. Deciduous teeth; IS 1°, C, PM\ PM=, MSM, M, Permanent teeth; AB, Maxillary sinus atbirth ; PMx, Posterior border of maxilla at birth ;AA, Maxillary sinus of adult; PMx, Posteriorborder of maxilla in adult; OA, Opening of sinusinto nose; Di, Deciduous central incisor. nasal respiration leads to increased develop-ment of the nasal passages and their communi-cating air sinuses, and thus of the bones thatsupport these cavities. The traction of musclesattached to its outlying processes, or those ofcontiguous bones, affect indirectly the growthof the body of the bone. The maxillary sinus at this period extendsbehind the second upper molar. The floor of thesinus not infrequently descends between theroots of the molars, a condition said by Cryer(9) to be more common among the wh
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentistry, bookyear19
