Surface roughness and enamel loss with two microabrasion techniques.

AIM: The aim of this study was to evaluate and compare the surface roughness and enamel loss produced by two microabrasion techniques. METHODS AND MATERIALS: Bovine teeth were selected and an area was delimited for microabrasion techniques. Surface roughness was determined before and after treatment using a digital profilometer. Specimens were randomized to one of two acid treatments (n = 10): 18% hydrochloric acid (HCl) and pumice or 37% phosphoric acid (H3PO4) and pumice. Acid treatments were applied using a wooden spatula for 5 seconds for a total of ten applications. Then, specimens were sectioned through the center of the demineralization area to obtain 80 microm thick slices. The wear produced by the microabrasion techniques was evaluated using stereomicroscopy (40 x). The greatest depth (microm) and the total surface area (microm(2)) of demineralization were measured using the Image Tool software (University of Texas Health Science, San Antonio, TX, USA). In addition, three specimens of each group were subjected to SEM analysis at different magnifications. RESULTS: The mean surface roughness was statistically lower for HCl than for H3PO4 (p < 0.001). Deeper demineralization (p < 0.003) and a larger total demineralization area was observed for HCl (p < 0.005). Under SEM analysis H3PO4 showed a selective conditioning etching, while HCl exhibited a non-selective pattern. CONCLUSIONS: Microabrasion using H3PO4 produced greater surface roughness but less demineralization than the microabrasion technique using HCl. CLINICAL SIGNIFICANCE: Both microabrasion techniques effectively remove the superficial enamel layer. However, the technique using H3PO4 was less aggressive, safer, and easier to perform.

Class II composite restorations with metallic and translucent matrices: 2-year follow-up findings.

OBJECTIVE: The aim of this randomized, clinical study was to evaluate the performance of composite restorations placed with two matrix and wedge systems after a 2-year follow-up. METHODS: Twenty-three patients were selected, and received at least two Class II restorations, one with metallic matrix and wooden wedge and other with polyester matrix and reflective wedge. One dentist placed all the 109 restorations. All cavities were restored using Single Bond and P-60 (3M ESPE), according to manufacturer's instructions. In the metal matrix group, polymerization was performed from occlusal, and in the polyester group, through the reflective wedge. Restorations were evaluated at baseline and after 12 and 24 months by the modified USPHS criteria, and data were analyzed with Mann-Whitney and Wilcoxon Signed Rank tests (alpha=0.05). RESULTS: Fifteen subjects and 78 restorations were re-evaluated after 24 months. A significant decrease in the quality of cervical adaptation and proximal contacts by radiographic evaluation was evidenced (p<0.05), but no differences between the two matrix systems were detected (p>0.05). In the clinical evaluation there were no significant differences between matrices after 2 years (p>0.05). A compromising of marginal adaptation, marginal staining and proximal contacts aspects for both matrix systems was evidenced, and restorations placed with translucent matrices showed loss of color stability (p<0.05). CONCLUSIONS: Whereas restorations presented some clinical aspects somewhat compromised after 2 years, the matrix and wedge systems evaluated showed similar clinical performance.