A Randomised Controlled Clinical Trial investigating the effect of osseodensification on implant stability and marginal bone levels.

Abstract

Osseointegration is a histologic term defined as the “direct structural and functional connection between living bone and the surface of a load-carrying dental implant”. Achieving successful osseointegration without the interposition of soft tissue is crucial for ensuring favourable implant stability and is essential for the long-term success of dental implants. Establishment of osseointegration depends on several factors including the surgical technique and implant loading conditions. Unlike conventional drills (CD) that remove bone by rotating clockwise (CW), osseodensification (OD) burs can also rotate counter-clockwise (CCW). This unique feature allows them to compact and push the autogenous bone laterally into the surrounding cancellous structure, preserving bone volume. This bone preservation and compaction leads to "autografting," facilitated by the elastic and plastic properties of bone, which allow it to deform. The lateral compaction of autogenous bone is causing residual strain, leading to a spring-back effect. This spring-back effect exerts gentle compressive forces against the implant, promoting a mechanical interlock between the bone and the implant, thereby increasing primary implant stability. Additionally, compacted bone fragments during OD can accelerate osteogenesis and new bone formation by acting as nucleating agents, improving implant stability throughout the healing process. Concerns have been raised regarding the strain level generated around peri-implant tissues using the OD technique. Bone tissue's elastic properties allow it to tolerate certain levels of strain, but excessive strain can lead to micro-cracks in the surrounding bone, resulting in extensive interfacial bone remodelling during healing, which can potentially cause marginal bone loss (MBL). Pre-clinical research on the effects of the OD technique has shown mixed biomechanical and histological results. Clinical research on OD's effects on primary implant stability is limited. Only three controlled trials compare implant stability between OD and CD, with contrasting results. Other clinical studies are either retrospective or prospective without control groups and only one study assessed OD's effects on marginal bone levels. A sample size calculation was performed and a sample of 19 subjects was required in each treatment group. The patients recruited had one maxillary implant placed using either CD or OD drills. Stability (in the form of ISQ values) was recorded immediately after surgery, at 3 and at 4-5 months. Clinical marginal bone levels were recorded immediately after surgery and at 3 months. Radiographic marginal bone levels were recorded using peri-apical radiographs immediately after surgery, at 3 and at 4-5 months. A repeated measure mixed ANOVA was used for analysing ISQ values at different time points. At placement, mean ISQ values ranged from 65.5 to 81 for the CD group and 29 to 80 for the OD group. For the CD group, ISQ values were 72.20 ± 2.6 (95% CI) at T1, 75.0 ± 2.0 at T2, and 74.8 ± 2.3 at T3. The corresponding ISQ values for the OD group were 68.1 ± 5.6, 71.9 ± 1.6, and 72.2 ± 2.4, respectively. There was an increase in implant stability over time for both treatment modalities. Implants placed using CD drills showed significantly greater stability compared to those placed using OD drills at 3 months but not at placement or at 4-5 months. No statistically significant differences were found in MBL around implants when comparing OD to the CD implant-specific drills. In general, factors like insertion torque, implant diameter, and length did not significantly impact the outcomes assessed in this study.