The Dental cosmos . d rest upon a gentlycurving line, rather than upon an angular or scalloped one. Manyoperators in their efforts to economize tooth-substance make the mis-take of producing results which are unsightly. A small filling withan odd border is more conspicuous than one which may be larger, butwhich has been placed in a cavity correctly formed. These rules, ofcourse, apply more especially to such fillings as reach the labial sur-faces of the anterior teeth. They apply, however, to the molarregion also, because in this instance esthetics and durability go handin hand. To leave irreg
The Dental cosmos . d rest upon a gentlycurving line, rather than upon an angular or scalloped one. Manyoperators in their efforts to economize tooth-substance make the mis-take of producing results which are unsightly. A small filling withan odd border is more conspicuous than one which may be larger, butwhich has been placed in a cavity correctly formed. These rules, ofcourse, apply more especially to such fillings as reach the labial sur-faces of the anterior teeth. They apply, however, to the molarregion also, because in this instance esthetics and durability go handin hand. To leave irregular borders in any cavity is to produce weak-ness along the points of contact between the tooth and the of the margin will occur either during the placing of thefilling or later. Reference to a few special cases will demonstrate the point morefully and clearly. Fig. 31 is diagrammatic, but conveys the ideaclearly enough. It is supposed to represent the ragged outline of a Fig. 31. Fig. 32. Fig. 1 \ cavity in the approximal surface of a central incisor. In Fig. 32 weobserve the same, prepared and filled, according to methods too oftenfollowed. There are three errors along the border. The cavity hasbeen formed on curved lines, it is true, but they are weak lines andnot esthetic. The slight prominence at a has been left, thus produc-ing an undulating border, instead of the more beautiful curve seen inFig. 33. Moreover, if we study the cleavage of enamel we discoverthat this prominence is weak, since it is unsupported, and must almostcertainly crack during the operation of filling. The force exertedin packing gold against it would probably produce fracture alongthe line of the enamel-rods, and if the disengaged piece did notcome away at once it would do so later, or else decay would be in-vited here. For similar reasons the sharp point at b should not havebeen left. Even if no fracture were produced during the packingof gold, the loss of a triangular segment
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