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RESEARCH PRODUCT

Self-drilling and self-tapping miniscrews for osteosynthesis fixture after LeFort I osteotomy: An ex vivo trial for primary stability and a randomized clinical study.

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Abstract Background Self-drilling osteosynthesis screws (SDS) have a potential higher primary stability together with clinical advantages such as less time effort compared to self-tapping screws (STS). The aims of the study were to compare the primary stability of SDS and STS ex vivo and to analyze of the time-saving effect in vivo . Materials and methods Ex vivo , both screws were placed in porcine bone. Torque was measured for insertion and removal. Four specimens were kept in bone for histologic bone-to-implant-contact examination. In vivo , 49 patients who received orthognathic surgery in the maxilla were included in 2 centers. In a split-mouth design, the time for osteosynthesis fixation and perioperative events were recorded. Results Ex vivo , insertion and removal torque measurements were higher for SDS, especially in dense bone. Histologic imaging on the exemplary-stained specimens showed higher bone contact and compressed bone matrix for SDS in all bone densities. In vivo , the mean osteosynthesis time in both centers was 5.5 min (±3.03) for SDS and 5.5 min (±2.37) for STS. Separate analysis showed that center I was faster with STS and center II with SDS. Although, in center I a higher rate of failed primary stability of SDS compared to STS was documented. Conclusions SDS showed a partially higher primary stability ex vivo , especially in dense bone. The timesaving effect of SDS is less pronounced than expected, but technically SDS might be favorable where drilling is difficult or even impossible.