. The Dental cosmos. cavities not so extended is unjustifi-able without a knowledge of the other possiblecontributory causes to such failures. The above answers paragraph 27 aswell. [Sec. 28.] Tt is further stated that thelateral extension of these walls is to bringthe margins within the path of the excursionsof food, so thai they may be cleaned by fric- CLACK.—EXTENSION FOR PREVENTION. 31 tion in the act of mastication. This, to becomplete, would require that some other forceor agent be utilized to similarly protect thegingival margin between the axio-eervicalangles. If the essayist knew the
. The Dental cosmos. cavities not so extended is unjustifi-able without a knowledge of the other possiblecontributory causes to such failures. The above answers paragraph 27 aswell. [Sec. 28.] Tt is further stated that thelateral extension of these walls is to bringthe margins within the path of the excursionsof food, so thai they may be cleaned by fric- CLACK.—EXTENSION FOR PREVENTION. 31 tion in the act of mastication. This, to becomplete, would require that some other forceor agent be utilized to similarly protect thegingival margin between the axio-eervicalangles. If the essayist knew the rules of exten-sion for prevention, he would not havemade this break. It is true that we ex-tend the lingual and buccal walls laterallyto bring the margins within the path ofthe excursions of food, but we extendthem gingivally also until the gum sep-tum in the apical space shall cover thatmargin (see Figs. 1 and 2), and wehave an absolute certainty that any mar-gin so covered with healthy gum tissue Fig. 1. Fig. will never decay. If the margins are leftas in Figs. 3 and 4 recurrence willtake place if the patient lives. There isno more -susceptible area than e e andF f. This is one of the articles of faithof the Black followers. [Sec. 29.] Curved margins are more grace-ful than angles. Curved walls are more con-servative of strength than angles. Shallowgrooves are more conservative of structurethan are angles. [Sec. 30.] There is greater danger of im-pairment of pulp function with the angulartype of cavity preparation. These sections—29, 30—refer to in-ternal cavity preparation and have noth-ing to do with extension for prevention,though we may take them up later undera different heading. [Sec. 31.] The character lines on ivhich acavity is prepared, and the skill toith whichgold is inserted, are the least of the factorspreventing recurrent decay. If by character lines the essayistmeans the outline of the cavity margins. he is only making an assertion withouta particle
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentist, bookyear1912
