Influence of cavity dimensions, insertion technique and adhesive system on microleakage of Class V restorations

Background. The authors evaluated the influence of cavity dimensions, insertion technique and adhesive system on microleakage of Class V composite restorations. Methods. The authors prepared cylindrical cavities with enamel margins of 3-millimeter diameter by 1-mm depth or 6-mm diameter by 2-mm depth on the labial surface of bovine incisors. They defined experimental groups (n = 15) according to cavity size, insertion technique (bulk or incremental) and adhesive system applied (Single Bond, 3M ESPE, St. Paul, Minn., or Excite, Ivoclar Vivadent, Amherst, N.Y.). They restored preparations with Tetric Ceram (Ivoclar Vivadent). After 36 hours' storage in distilled water at 37 C, specimens were submitted to microleakage using 50 percent silver nitrate as tracer. Teeth were sectioned twice and dye penetration on the axial wall was determined in millimeters. Results. The authors analyzed the data using analysis of variance/Tukey test (α = .05). For large restorations, the use of Single Bond resulted in higher microleakage than Excite (1.56 ± standard deviation [SD] 0.26 mm and 0.63 ± SD 0.56 mm, respectively; P < .001), whereas for small restorations there was no statistical difference between adhesives (Excite: 0.47 ± SD 0.28 mm; Single Bond: 0.46 ± SD 0.28 mm). Conclusion. The choice of adhesive system influenced microleakage only for large restorations. Incremental insertion of the composite did not affect dye penetration. Clinical Implications. Microleakage of composite restorations cannot be predicted only on the basis of the restorations' dimensions. In large restorations, it also depends on the choice of adhesive system, whereas in small restorations, the adhesive used does not seem to be an influential factor. Incremental insertion did not seem to reduce restorations' microleakage.