Apical Site Preparation is Fundamental for the Entire Implant Stability

Objectives: The role of implant design and surgical technique are important parameters needed in order to improve primary stability. Implant stability depends on apical retention especially when they are placed in fresh extraction sockets. The aim of this study was to evaluate the role of mechanical stability of the apical part of an implant, placed in type I dense bone, by novice and experienced clinicians.
Methods: Implants with a progressive thread design (3.5mm diameter, 11mm length) were used. A total of 80 osteotomies were prepared in bone samples (quality type I) by two clinicians with different levels of experience (novice and experienced) under the same surgical protocol. 40 step osteotomies were prepared (20 by each clinician). The implants were placed into these step osteotomies with only the 3mm apical portion of the implant within the bone and without lateral contact between the residual implant length (T-implants) and the osteotomy wall. 40 control implants (same size) were inserted in 40 conventional osteotomies (20 by each clinician) having contact between the osteotomy wall and implant surface (C-implants). Apical stability of T-implants as well as the stability of C-implants was evaluated using an Osstell device (ISQ values). Statistical comparison between the groups was performed using Kruskal-Wallis test with Dunn's multiple comparison.
Results: The results did not show statistically significant differences (P>0.05) in terms of primary stability between implants placed by novice or experienced clinicians in dense bones. The T-implants showed significantly less ISQ values than the C-implants (P<0.001). The apical implant stability contributed to approximately 30% and 43% of the entire implant stability for novice and experienced clinicians respectively.
Conclusions: The apical portion of an implant plays a fundamental role in the entire implant stability. Therefore, precise implant site preparation is significant, especially in compromised clinical conditions.