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Ceramic inlays have shown good marginal seal as long as the margins of the cavities are located in enamel. The purpose of this study was to investigate the marginal seal of ceramic inlays with the cervical margins situated in dentin and to determine the effectiveness of dentin bonding agents. Sintered ceramic inlays were adhesively luted either without dentin bonding agents or with the use of Gluma or Miragebond. After thermocycling and incubation in a colored dye the penetration depth of the dye was measured on sequential sections. The used dentin bonding agents did not improve marginal seal. The glass ionomer cement base was able to prevent further penetration in most of the cases when deep leakage occurred. Unless a tight marginal seal in dentin can be achieved, the indication for adhesively luted inlays must be limited to cavities with margins located in enamel.

16 butt joint (Group A) and 16 beveled (Group B) class I cavities were prepared in extracted molars and filled with two hybrid composite resin materials using the enamel etching technique. Replicas were obtained before and after thermocycling (TC) and a computerized quantitative margin analysis was carried out in the SEM. Statistical analysis revealed significant differences (p less than 0.01) between the two groups only after TC. Group B showed significantly less marginal openings than Group A (A: 50.7%, B: 8.4%) after TC. Class I cavities for hybrid composite resin materials should be beveled.

The opacity of eleven composites, enamel, and dentin was determined quantitatively using densitometric measurements of X-rays. The reference material was aluminium 99.5% which was exposed with each film. Opacity values were 215% for enamel and 118% for dentin. Three of the composite materials demonstrated an opacity similar to enamel, one similar to dentin. The other materials showed higher values than enamel. Consequently, the majority of composites reaches opacity values necessary for the diagnosis of secondary caries.

Lemon juice was applied to intact and eroded tooth surfaces in vivo to demonstrate the development of erosions based on morphological changes. Under the influence of the fruit acid the protecting pellicles are removed and the enamel demonstrates the typical etch lesion with a honeycomb surface structure. In the dentin the acid works mainly on the peritubular area. Abrasive brushing techniques wear down the already damaged tooth surfaces.