There is ample evidence to support the use of endocrowns to restore endodontic teeth. However, the influence of the position of the interproximal margins on fracture strength has not yet been studied. The aim was to determine the relationship between the apicocoronal position of the interproximal restorative margins and fracture resistance in nonvital teeth restored with CAD/CAM endocrown overlays. Forty extracted human maxillary premolars were prepared for endocrown overlay restorations without ferrule on the interproximal aspects and classified according to the position of the interproximal restoration margins in relation to the alveolar crest: 2 mm (group A), 1 mm (group B), 0.5 mm (group C), and 0 mm (group D). Fracture strength was measured using a universal testing machine applying a compressive force to the longitudinal tooth axis. Group A had a mean fracture resistance of 859.61 (±267.951) N, group B 1053.9 (±333.985) N, group C 1124.6 (±291.172) N, and group D 780.67 (±183.269) N, with statistical differences between groups. Group C had the highest values for fracture strength compared to the other groups (p < 0.05). The location of the interproximal margins appears to influence the fracture resistance of CAD/CAM endocrown overlays. A distance of 0.5 mm between the interproximal margin and the alveolar crest was associated with increased fracture resistance.

Background Narrow diameter implants (NDIs) are used in cases of limited mesio‐distal space, or if the alveolar ridge does not allow placement of a standard diameter implant. Purpose The aim of this prospective case series study is to present the 5‐year clinical‐, radiological‐, and patient‐reported outcome measures (PROMs) of patients with partial edentulism in the anterior area of the jaws requiring the placement of two narrow diameter implants to support a 3‐ or 4‐unit fixed partial denture (FPD). Materials and Methods Thirty partially edentulous patients missing 3 or 4 adjacent teeth in the anterior area of the jaws were included in the study. Two titanium–zirconium tissue‐level NDIs were placed in each patient in healed anterior sites (60 implants). A conventional loading protocol was performed to provide a FPD. Implant survival, success, marginal bone‐level changes (MBL), clinical parameters, buccal bone stability with CBCT, adverse events and PROMs were recorded. Results The survival and success rates for the implants were 100%. The mean MBL (±SD) after prosthesis delivery, and 5‐year follow‐up (mean 58.8 months; range: 36–60) was 0.12 ± 0.22 and 0.52 ± 0.46 mm, respectively. Decementation and screw loosening were the most frequent prosthetic complications, yielding a prosthetic survival and success rates of 100% and 80%, respectively. Patient satisfaction was high with a mean (±SD) score of 89.6 ± 15.1. Conclusions The use of tissue‐level titanium–zirconium NDIs supporting splinted multi‐unit FPDs in the anterior area seems to be a safe and predictable treatment option after a 5‐year follow‐up period.

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