Effect of the number of splinted abutments on the accuracy of zirconia copings

Abstract

STATEMENT OF PROBLEM: Splinting periodontally or structurally compromised abutments is a common procedure. However, studies that investigated the effect of splinting on the accuracy of zirconia copings are lacking.

PURPOSE: The purpose of this in vitro study was to evaluate the magnitude of marginal and internal gaps of zirconia copings based on the number of splinted abutments and digital scan technique.

MATERIAL AND METHODS: Four maxillary acrylic resin incisors were prepared for ceramic restorations. Epoxy resin master models were fabricated by duplicating the acrylic resin model. An intraoral scanner was used to build 40 digital models (direct digital scan group [DD]); an additional 40 digital models were constructed by scanning 40 maxillary definitive casts using a laboratory scanner (indirect digital scan group [ID]). During computer-aided design, the DD and ID groups were subdivided into 4 groups; single unit (group SU); 2-unit splinted (group 2S); 3-unit splinted (group 3S), and 4-unit splinted (group 4S). Zirconia copings were then fabricated. Using the replica technique, marginal, axial, and occlusal gaps were measured and statistically evaluated (α=.05).

RESULTS: In DD, group 4S exhibited larger marginal gaps than groups SU, 2S, and 3S (P<.001). In ID, group SU exhibited smaller marginal and occlusal gaps than group 4S (P<.001). Group 4S exhibited significantly greater axial gaps than groups SU, 2S, and 3S (P<.001).

CONCLUSIONS: As the number of splinting units increased, the magnitude of the marginal gap tended to increase; however, the differences were less than 5 μm, which is clinically insignificant. Axial gaps in the ID group demonstrated a significant difference (>35 μm) among the groups.