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Objectives: Aim was to evaluate the impact of glass fiber versus titanium endodontic posts on the interproximal bone level around severely damaged endodontically treated teeth. Materials and methods: Thirty-eight participants of a randomized controlled trial on glass fiber (n = 18) and titanium post-endodontic restorations (n = 20) received radiographs at two different times after post placement (T0 = <12 months and T1 = 36–72 months after post placement). A total of 76 radiographs were analyzed with an image-editing software. Medians of changes in mesial and distal interproximal bone level (∆MBL, ∆DBL) were calculated and tested for statistical significance with respect to post material using Mann-Whitney U test (p < 0.05). Impact of post material on bone level changes was assessed in multilevel mixed-effect linear regression models. Results: The mean observation period was 54 months for glass fiber and 50 months for titanium posts. Interproximal bone loss was small in both groups during the study period with no significant differences between groups (glass-fiber group, ∆MBL = − 0.03 mm and ∆DBL = − 0.06 mm; titanium group, ∆MBL = − 0.07 mm and ∆DBL = − 0.17 mm; both p > 0.05). Overall, impact of post material on bone loss was almost negligible with a nonsignificant difference between materials of 0.10 mm during the entire study period. Conclusion: The rigidity of endodontic post material has no impact on the level of alveolar bone support of severely damaged endodontically treated teeth. Clinical relevance: Post-endodontic restorations of severely damaged teeth can achieve steady levels of periodontal bone support as a parameter of periodontal health, irrespective of post material. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the values of retentive forces of double crowns. The effect of the abutment height, the material of the inner crown, and the taper were evaluated. Sixty inner crowns each were fabricated from zirconia and a gold alloy having three different abutment heights (5, 7, and 9 mm) and two different tapers (0° and 2°). All outer crowns were made with an electroforming system. The removal test was performed by a standardized setup using a universal testing machine at a crosshead speed of 1,000 mm min−1. Ten separation cycles were performed of each specimen, and the mean was imported into a statistical program. The retention forces were in the range of 0.37 and 2.65 N. The abutment height ( p < 0.001), the material of the inner crown ( p = 0.035), and the taper ( p < 0.001) showed statistical influence on the retention force in the two-way ANOVA. Zirconia primary crowns performed better than gold alloy in the 0° group, especially with short abutments. However, a taper of 0° and short abutments have clinical drawbacks that were not evaluated in this study. In situations with long abutment teeth and a 2° taper zirconia is an alternative to gold alloy primary crowns. [ABSTRACT FROM AUTHOR]