Comparison of three-dimensional digital technique with two-dimensional replica method for measuring marginal and internal fit of full coverage restorations

摘要

This study compared digital (reference point matching) and replica methods for measuring marginaland internal fit of full coverage restorations. MATERIALS AND METHODS. A maxillary left first molar typodentwas fixed on to an aluminum base and prepared to receive all-ceramic full coverage restoration. The model wasscanned with an intraoral scanner (CEREC Omnicam, Sirona, York, PA, USA). Twelve crowns were fabricatedfrom lithium disilicate blocks (IPS emax CAD, Ivoclar Vivadent) and then crystalized. Marginal and internal fit ofeach restoration was measured by two examiners using replica and a new digital three-dimensional technique.Reliability between the two methods and two examiners was assessed by correlation and Cronbach’s Alphacoefficient (P.05). A Bland-Altman assessment for agreement was used to compare the two methods. RESULTS.Bland-Altman assessment showed that the mean of difference for marginal, absolute marginal, and axial gap wasrespectively -1.04 μm, -41.9 μm, and -29.53 μm with limit of agreement (LOA) between -37.26 to 35.18 μm formarginal, -105.85 to 22.05 μm for absolute marginal and -80.52 to 22.02 μm for axial gap. Positive correlationfor repeatability (P.05) in determining marginal and internal gaps by the two examiners in both techniques wasrevealed. Reliability of both techniques in all sites of measurements was at least good (0.8 ≤ α 0.9).CONCLUSION. Both measuring techniques appeared highly reliable for evaluating fit of fixed dental restorations,while reference point matching provided higher values in axial and absolute marginal gap assessment.