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There is little information in the literature regarding the relationship between preparations made for direct and indirect veneers and the loss of tooth structure required for each technique. This in vitro study sought to quantify the different mass losses from preparation techniques used for direct and indirect veneers. Thirty artificial teeth were weighted using a digital balance and placed in a dental manikin in the position corresponding to the right maxillary central incisor. Five clinicians-all experts in esthetic dentistry-were asked to perform conventional preparations for both a direct composite resin veneer and an indirect ceramic veneer. After preparations, specimens were weighted again in the same digital balance. Teeth undergoing veneer preparations demonstrated a statistically significant mass loss compared to unprepared teeth. Indirect ceramic veneer preparations produced more mass loss than direct composite veneer preparations (P0.01).

The knowledge about the potential adverse effects of radiotherapy compared to dental composites is a useful information for the clinician's decision regarding adoption of repairs or replacement of dental restorations during oral cancer treatment. This study evaluated the effects of irradiation on microhardness and surface roughness of a microfilled and a packable composite resin. The microfilled composite resin demonstrated significantly lower microhardness and a smoother surface compared to the packable composite resin (p0.05). Although irradiation significantly reduced the microhardness for both composite resins (P0.05), increasing the x-ray doses did not cause an additional significant decrease in surface hardness (P0.05). Meanwhile, irradiation did not produce a significantly rougher surface (P0.05), but specimens submitted to abrasion exhibited a significant increase in surface roughness for both composite resins (P0.05). It was concluded that while irradiation can adversely affect the hardness of tested composite resins, it does not interfere with surface roughness.

This study investigated how different photocuring units, exposure times, and ethanol storage affected the depth of cure in a microhybrid composite. Forty composite specimens (each with a depth of 4 mm) were prepared and divided randomly into four groups (n = 10) to receive treatment from a quartz-tungstenhalogen (QTH) curing unit (400 mW/cm2) or a light-emitting-diode (LED) curing unit (180 mW/cm2). The specimens were photocured for either 20 or 40 seconds and stored in the dark for 24 hours at room temperature. Knoop hardness was measured by making three indentations at each depth interval of 1 mm (up to 4 mm) with a 50 g load for 30 seconds. The specimens were stored in ethanol for 24 hours; at that time, hardness was measured again. Data were submitted to three-way ANOVA, Tukey's test, and Student's t-test (p0.05). Statistical analysis revealed that hardness was significantly affected by depth, exposure time, and storage in ethanol (p0.001). No differences were observed between the curing units tested.

This study evaluated the microtensile bond strength between a composite resin and a zirconia-reinforced alumina-based glass-infiltrated ceramic after different ceramic surface treatments. Blocks (12 mm x 10 mm x 5 mm3) of a ceramic containing zirconia were fabricated, polished, and divided at random into seven groups, with each group receiving a different surface treatment. The adhesive system and composite resin were applied to the treated ceramic; these composite-ceramic blocks were stored in distilled water (37 degrees C) for seven days. At that point, they were cut along two axes to produce specimens with a cross-sectional area of 1.0 (+/- 0.1) mm2. The specimens (n = 20) were loaded in tension in a universal testing machine with a cross-head speed of 0.5 mm/minute. The microtensile bond strength values were calculated and statistically analyzed using ANOVA and Tukey's test (alpha = 0.05). Among the seven groups, specimens with both a silica coating and a silane coupling agent showed the highest mean microtensile bond strength values. All specimens treated with 9.5% hydrofluoric acid failed during the cutting procedure; among all specimens, the majority of the failures were cohesive. A positive correlation was observed between the fracture type and the microtensile bond strength (r = 0.63).

Esthetic dentistry has received increased attention in recent years, as people are more aware of the esthetic appearance of their teeth, including alignment and whiteness. This development, combined with a decrease in the incidence and severity of caries, has directed some clinicians toward conservative and non-invasive treatments such as tooth bleaching. A number of methods for nonvital tooth bleaching are described in the literature; these procedures rely on the bleaching agent used, the agent's concentration, product format, and the source of light activation. This article presents two case reports in which dental bleaching with halogen light-activated agents was used to treat a nonvital discolored incisor. The advantages and disadvantages of the technique are discussed.