Comparison of the strain developed around implants with angled abutments with two reinforced polymeric CAD-CAM superstructure materials: An in vitro comparative study

The strain developed around implants with angled abutments should be considered when selecting a superstructure material. Studies that evaluated the strain developed around implants with angled abutments when using fiber-reinforced polymer as the implant superstructure material are lacking.The purpose of this in vitro study was to assess the strain developed around implants with angled abutments (15 and 25 degrees) of biocompatible high-performance polymer (BioHPP) and reinforced nanohybrid polymer with a multilayered glass fiber (TRINIA) superstructure under axial and oblique loading. The strain developed around implants was evaluated by using strain gauges.Thirty-two polyurethane test blocks were divided into 2 main groups (n=16) according to the degrees of buccal tilting of the implant platform (15 and 25 degrees). Each group was divided into 2 subgroups (n=8), and each subgroup received different superstructure materials (BioHPP or TRINIA). Two buccal and palatal strain gauges were installed on their corresponding prepared sites to measure the microstrains in the medium surrounding the implant. A universal testing machine was used to apply the static load from 0 to 100 N in the axial and 45-degree oblique direction, with the loading tip of the device on the loading point at the central fossa of the crown. For each tested implant, loads were applied, microstrains were recorded with the strain gauges, and the strain developed around the implant was statistically evaluated with 1-way ANOVA, followed by multiple pairwise comparisons by using the Bonferroni adjusted significance level (α=.05).For superstructure materials, the microstrain values recorded around implants restored with TRINIA were significantly lower than those restored with BioHPP in all groups (P<.001). The 25-degree implant angulation recorded significantly higher microstrain than 15 degrees buccally and palatally when axial and oblique loads were applied (P<.05). The microstrain was significantly higher in the oblique load than in the axial load in both the BioHPP and TRINIA groups in 15- and 25-degree implant angulations on the buccal and palatal sides (P<.001).The strain developed around dental implants was significantly affected by the superstructure material. The microstrain was considerably higher when the implant abutment angulation increased. When a 45-degree loading direction was used, this tendency became more pronounced.