Exploring the impact of blood and bone debris at the implant-abutment interface on peak removal torque: Bridging clinical observations with laboratory evidence

Abstract

Three months after implant placement, difficulty was encountered in unscrewing the healing abutment within the normal torque range (<35 Ncm), resulting in the removal of the implant. Despite all attempts, the implant could not then be separated from the healing abutment. Retrospective analysis of intraoperative photographs revealed the presence of blood or bone debris within the implant before the healing abutment was placed; this was considered to be the likely cause of this phenomenon. The purpose of the study was to explore the impact of blood or bone debris within the implant during surgical placement on the torque required for unscrewing the healing abutment. A total of 27 implants were divided into 3 groups based on whether blood, blood and bone debris, or nothing was added. An electronic torque wrench was used to uniformly tighten the implants and healing abutments to 10 Ncm. These implants were then stored in a constant-temperature environment in physiological saline. After 1, 2, and 3 months, 3 implants from each group were randomly selected for microcomputed tomography analysis. Subsequently, an opening torque test was conducted to measure the maximum torque required to unscrew the healing abutment. The study data were compiled using Microsoft Excel 2019 and statistically analyzed with a statistical software package. One-way ANOVA was used to determine significant differences among groups, specifically by comparing and analyzing the bone volume fraction and maximum removal torque (RTQ) within the microgap between implants and healing abutments (α=.05). The in vitro simulated experiment revealed that the presence of blood mixed with bone debris led to an increase in high-density images within the microgap. Significant differences in the maximum removal torque were observed among the 3 groups 1, 2, and 3 months after in vitro placement (P<.05), indicating that blood and bone debris affected the torque required to unscrew the healing abutment. The presence of blood or bone debris in the microgap should be avoided to prevent an increase in the unscrewing torque.