Influence of abutment connections on strain distribution for implant-supported 4-units bridge

Abstract

The purpose of this study is to evaluate the microstrain around two non-parallel implant-supported bridges with different types of abutment connections (engaging, non-engaging and scrp) and the different positions of abutments. The four models simulating the mandibular unilateral free end were fabricated. There were eight implants (4.0 x 10 mm and 5.0 x 10 mm) were inserted in four models in the position of the second premolar (45) that paralleled the long axis and the second molar (47) that tilted 15° from the long axis to support a 4-unit zirconia bridge, according to different abutment combinations: engaging and engaging abutments (angled abutment), both non-engaging abutments, both SCRP abutments, and engaging and non-engaging abutments. Four strain gauges were mounted buccally, lingually, mesially, and distally adjacent to each implant. Applied vertical static load: 300 N. Microstrains were recorded and analyzed statistically by three-way repeated ANOVA and pairwise comparisons (α=.5). The result showed group two (non-engaging, non-engaging) showed the highest compressive microstrains (-52.975), followed by control group one (engaging, angled abutment) (-25.239), and group three (SCRP-SCRP) had the lowest compressive microstrains (-14.505), while only group four (engaging, angled abutment) had tensile microstrains (0.418). The microstrains in groups three and four were significantly lower than those in the control group (α=.5) Area 45 showed compressive microstrains (-47.06), while area 47 had tensile microstrains (+0.91), with microstrains in area 45 being significantly higher than in area 47 (α=.5) In conclusion, the type and position of the abutment connection have significantly affected microstrain at the implant-bone interface of two non-parallel implant-supported bridges. Both SCRP abutments for two non-parallel implant-supported bridges provided optimal microstrain distribution on bone.