Cracks were introduced via microindentation along the prism direction and evaluated as a function of time after the indentation. In this investigation the crack repair characteristics of young human enamel were evaluated as a function of patient gender and as a function of the distance from the Dentin Enamel Junction (DEJ). While there have been a number of studies aimed at understanding the hardness and crack growth resistance behavior of this tissue, no study has evaluated if cracks in this tissue undergo repair. Tooth enamel is the hardest and most highly mineralized tissue in the human body. Indentation Damage and Crack Repair in Human Enamel* Thin non-functional cusp walls of adhesively bonded restorations should be completely covered or reduced to avoid enamel cracks and marginal deficiency. Preparation designs with horizontal reduction of non-functional cusps showed a tendency to less enamel crack formation than preparation designs without cusp coverage. PCC with horizontal reduction of non-functional cusps showed statistically significant less microleakage than PCC without such a cusp coverage. The data were statistically analysed with the Mann-Whitney U test, the Fishers exact test (alpha = 0.05) and the error rates method. Enamel cracks were documented under a reflective-light microscope. Marginal integrity was assessed by evaluating dye penetration after thermal cycling and mechanical loading. The specimens were exposed to thermocycling and central mechanical loading. Ceramic restorations (Vita Mark II, Cerec3 System) were adhesively luted with Excite/Variolink II. Non-functional cusps were adjusted to 1.0-mm wall thickness and 1.0-mm wall thickness with horizontal reduction of about 2.0 mm. CI and PCC preparations were performed on extracted human molars. The aim of this in vitro study was to investigate the effect of cusp coverage of thin non-functional cusps on marginal integrity and enamel crack formation. No information is available to date about cusp design of thin (1.0 mm) non-functional cusps and its influence upon (1) marginal integrity of ceramic inlays (CI) and partial ceramic crowns (PCC) and (2) crack formation of dental tissues. Krifka, Stephanie Stangl, Martin Wiesbauer, Sarah Hiller, Karl-Anton Schmalz, Gottfried Federlin, Marianne Influence of different cusp coverage methods for the extension of ceramic inlays on marginal integrity and enamel crack formation in vitro.
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February 2023
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