Effect of Operator-specific Handling on Tooth-composite Interface and Microleakage Formation

Abstract

The aim of this in vitro study was a comparative investigation of tooth-composite interface morphology and microleakage formation after the calibrated restoration of Class II cavities with a proven multi-component, three-step, total-etch adhesive system by three experienced operators. The current study also aimed to acquire data about the well-tried adhesive system under defined laboratory conditions for further comparative assessments with other adhesives. Forty Class II cavities were prepared on extracted, caries-free molars. In the first study (Part A), 24 cavities were restored (n=8 each) according to the manufacturers' instructions. In the second study (Part B), 16 teeth (n=6, 4, 6) were filled in the same way; however, the last component of the same adhesive system was applied twice. The teeth were prepared for microleakage testing and morphological assessment of the composite-tooth interface by scanning electron microscopy. The three operators had differences with regard to adhesive layer formation, inter-/peritubular adhesive penetration and the formation of adhesive failures on the dentin interface and microleakage on dentin. The lowest microleakage on dentin was related to enhanced peritubular and intertubular adhesive penetration. After double application of an adhesive component (Part B), the sealing of the enamel and dentin with adhesive increased partially, and adhesive failures on dentin were partly diminished, but no distinct effects on microleakage formation were found. The results confirm the technique-sensitivity of the etch-and-rinse adhesive related to interface morphology and microleakage formation. These results are helpful in the comparative evaluation of other bonding systems.