The Dental cosmos . of chipping. Fig. 33 is correctly formed anddecidedly more pleasing to the eye. In Fig. 34 we have anothercavity, which is too often incorrectly formed, as seen in Fig. should have a border similar to Fig. 33. As prepared in Fig. 35the point a is weak. Gold is a soft, malleable metal, and where it isbrought to a thin edge, as seen, the impacting force of masticationtends to flatten it out until it curls and breaks, leaving a ragged point b is weak for reasons already given. As I have made my diagrams to deal with cavities involving the re-storation of corne
The Dental cosmos . of chipping. Fig. 33 is correctly formed anddecidedly more pleasing to the eye. In Fig. 34 we have anothercavity, which is too often incorrectly formed, as seen in Fig. should have a border similar to Fig. 33. As prepared in Fig. 35the point a is weak. Gold is a soft, malleable metal, and where it isbrought to a thin edge, as seen, the impacting force of masticationtends to flatten it out until it curls and breaks, leaving a ragged point b is weak for reasons already given. As I have made my diagrams to deal with cavities involving the re-storation of corners, this will be an opportune place to discuss thatparticular subject. It has been recommended by recognized authorityto form a cavity of this character as shown by the heavy shading inFig. 36. To my mind this is most unfortunate teaching. We thusget two sharp angles, both of which must become weak points save inthe hands of the most skillful, even if this exception be allowable, Fig. 34. Fig. 35. Fig. 36. Fig. which is doubtful. In any event the result is far from beautiful. Sucha cavity coming into my hands would have been formed as shown inFig, 33, for the L-like extension is supposed to have been intention-ally made by the operator. Once I was called upon to refill a toothwhich had been operated upon according to this method, and in thatinstance I formed my cavity as indicated by the dotted line, Fig. 36,approaching my ideal as nearly as possible under the could have shaped it as seen in Fig. 37, but such a form is so un-common as to be more conspicuous than that chosen. In Fig. 38 wesee a diagram showing two corners contoured. In cases of fracturefrom falling against a curbstone or from other accident, the corner willusually be lost, the line of fracture being a straight one. A filling placedwithout alteration of the border would appear as shown at a, and thecorrect border is seen at b. Let us consider these two forms aside fromesthetics. Suppose that
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