These results demonstrate that the commercial collagen membrane holds an osteoconductive competence in a rat calvaria defect model. Soaking collagen membranes with BCM shifts bone formation toward the formation of bony islands rather than new bone connected to the host bone.

BackgroundEvaluation of the marginal fit of cemented zirconia copings manufactured after digital impression with Lava™ Chairside Oral Scanner in comparison to that of zirconia copings manufactured after conventional impressions with polyvinyl siloxane.MethodsA prepared typodont tooth #36, was replicated 40 times with a vinyl silicone and precise model resin. The dies were randomly divided into two groups according to the impression taking technique. Digital impressions with Lava™ C.O.S. and conventional impressions were taken according to the group. Subsequently zirconia copings were manufactured and cemented on their respective dies with zinc oxide phosphate cement. After embedding in resin, mesio-distal section of each coping was performed with a diamond saw in order to obtain two slices. One half of the specimen was used for evaluation with an optical microscope (OM) and the other half for evaluation with a scanning electron microscope (SEM). Marginal gap (MG) and absolute marginal discrepancy (AMD) were measured mesial and distal on each slice.ResultsNo significant difference of the marginal parameters between the digital and the conventional group was found. The mean values for MG in the digital group were 96.28 μm (+/−43.21 μm) measured with the OM and 99.26 μm (+/−48.73 μm) measured with the SEM, respectively. AMD mean values were 191.54 μm (+/−85.42 μm) measured with the optical microscope and 211.6 μm (+/−96.55 μm) with the SEM. For the conventional group the mean MG values were 94.84 μm (+/−50.77 μm) measured with the OM and 83.37 μm (+/−44.38 μm) measured with the SEM, respectively. AMD mean values were 158.60 μm (+/−69.14 μm) for the OM and 152.72 μm (+/−72.36) for the SEM.ConclusionsCopings manufactured after digital impression with Lava™ C.O.S. show comparable marginal parameters with the copings manufactured after conventional impression with polyvinyl syloxane. The mean MG values of both groups fit in the clinically acceptable range.Electronic supplementary materialThe online version of this article (doi:10.1186/s12903-016-0323-8) contains supplementary material, which is available to authorized users.

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