Twenty-four months in vivo wear of enamel antagonists to lithium disilicate implant crowns – a pilot study

Abstract

ObjectivesTo evaluate whether there is a significant difference between the ratio of wear of lithium disilicate implant crowns and their enamel antagonists and adjacent enamel/enamel antagonist contacts. Additionally, the movement of the adjacent teeth was determined. Materials and methodsIntraoral scans of the occlusal surfaces of 41 patients were performed after insertion of the implant restoration (baseline), after 12 and 24 months. From the initial study cohort, eleven implant crown/enamel antagonist pairs with adjacent enamel antagonist pairs could be analyzed in nine patients after 12 months. After 24 months, ten implant crowns of eight patients were available due to one decementation of an implant crown. A semiautomatic specifically developed iterative closest point algorithm was used to superimpose the surfaces of the baseline scan with the follow-up scans to measure the maximum height loss of each identified wear side. The mean maximum tooth wear and the standard deviation (SD) were calculated per unit. The ratio of wear of enamel/enamel antagonist teeth and the wear ratio of adjacent lithium disilicate implant crowns and their enamel antagonist surfaces were evaluated. Tooth movements were described by translations and rotations using a separate measurement procedure. The surfaces of the scans were superimposed setting the implant as a reference structure for registration. ResultsAfter 12 months the wear ratio between the enamel antagonist pairs was 0.95 ± 0.27 µm and the ratio between lithium disilicate/enamel was 0.73 ± 0.49 µm. After 24 months the ratio of enamel antagonist pairs was 1.04 ± 0.28 µm and the ratio of lithium disilicate/enamel was 0.73 ± 0.51 µm. The ratios did not differ significantly. ConclusionsIntraoral scanning and computer analysis showed that the two-years wear ratios between enamel/enamel and enamel/lithium disilicate implant crowns did not differ significantly. Statement of clinical relevanceThe methodology described in this study could measure tooth wear and detect long-term wear performance. In the future, digital monitoring of prosthetic restorations should be integrated into clinical workflow to identify potential factors affecting longevity.