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Objectives: The aim of this study was to evaluate whether salivary contamination during placement of implants with different surface characteristics affects osseointegration in native and in augmented bone areas., Materials and Methods: Forty eight implants with machined surface (MS) and 48 implants with moderately rough surface (RS) were tested in the calvaria of 12 sheep. At the first surgery, 64 bony critical defects were randomly created and were subsequently augmented with two materials (autogenous or bovine bone). After 5 weeks of graft healing, 8 implants were placed per sheep, in native bone and in the centre of the augmented defects. Forty eight implants were soaked with saliva before placement (contaminated group [CG]), while 48 implants were not (non-contaminated group [NCG]). Five weeks after implant placement, bone-to-implant contact (BIC) and bone material area fraction occupancy (BMAFO) were calculated histomorphometrically., Results: Saliva contamination showed a significant negative effect (p = .000) on BIC, especially in augmented areas. RS showed significant positive effect on BIC, compared to MS (p = .000), while there were no significant differences for different bone conditions (p = .103). For BMAFO, the contamination showed a significantly negative affect (p = .000), while there were no significant differences for surface characteristics (p = .322) and for bone condition (p = .538)., Conclusion: Saliva contamination during dental implant placement has a negative effect on osseointegration in augmented areas. Moderately rough surface has a possible advantage in the aspect of initial bone to implant contact. However, it seems to be advisable to avoid saliva contamination especially for implants placed in augmented bone areas., (© 2023 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)

Purpose: There is no clinical consensus to determine the right balance between underpreparation and marginal bone level changes. The purpose of this systematic review and meta-regression was to investigate the influence of the type of drilling preparation of the implant site in relation to the bone mineral density on the clinical success, expressed in terms of the MBL and implant failure rate., Study Selection: A thorough search was performed using the digital databases MEDLINE PubMed, EMBASE, and Cochrane Central Register of Controlled Trials by entering research lines or various combinations of free words. The main keywords used were "dental implants", "bone density", and "torque"., Results: The mean bone resorption in the conventional preparation group was -0.43 (± 0.28) mm, whereas it was -0.80 (± 0.37) mm in the underprepared group. For the D1/D2/D3 bone group, the slope was significantly different from zero and linearity; the D4 bone group slope was not significantly different from zero and was almost parallel, although it was significantly different from linearity. The box and whiskers plot shows that the MBL in underprepared sites tended to be significantly higher with a higher variation than that in conventionally prepared sites., Conclusions: Within its limits, our meta-regression analysis showed that MBL is influenced by the type of drilling preparation and bone mineral density. In particular, a lower MBL was observed in the D1 bone with conventional preparation than with underpreparation. Moreover, a greater implant-to-osteotomy site mismatch was positively associated with greater MBLs in the bone densities of D1/D2/D3.

The aim of this study was to evaluate the influence of bone quality, drilling technique, implant diameter, and implant length on insertion torque (IT) and resonance frequency analysis (RFA) of a prototype-tapered implant with knife-edge threads. The investigators hypothesized that IT would be affected by variations in bone quality and drilling protocol, whereas RFA would be less influenced by such variables. The investigators implemented an in vitro experiment in which a prototype implant was inserted with different testing conditions into rigid polyurethane foam blocks. The independent variables were: bone quality, drilling protocol, implant diameter, and implant length. Group A implants were inserted with a conventional drilling protocol, whereas Group B implants were inserted with an undersized drilling protocol. Values of IT and RFA were measured at implant installation. IT and RFA values were significantly correlated (Pearson correlation coefficient: 0.54). A multivariable analysis showed a strong model. Higher IT values were associated with drilling protocol B vs A (mean difference: 71.7 Ncm), implant length (3.6 Ncm increase per mm in length), and substrate density (0.199 Ncm increase per mg/cm3 in density). Higher RFA values were associated with drilling protocol B vs A (mean difference: 3.9), implant length (1.0 increase per mm in length), and substrate density (0.032 increase per mg/cm3 in density). Implant diameter was not associated with RFA or IT. Within the limitations of an in vitro study, the results of this study suggest that the studied implant can achieve good level of primary stability in terms of IT and RFA. A strong correlation was found between values of IT and RFA. Both parameters are influenced by the drilling protocol, implant length, and substrate density. Further studies are required to investigate the clinical response in primary stability and marginal bone response.

Objective: The aim of this study was to investigate the extent of cortical bone remodeling between two different drilling protocols by means of histomorphometric, µ-CT, and biomechanical analyses., Material and Methods: A total of 48 implants were inserted into the mandible of six sheep following two drilling protocols: Group A (Test, n = 24), undersized preparation; Group B (Control, n = 24), non-undersized preparation. The animals were euthanatized to obtain 5 and 10 weeks of implantation time. Removal torque (RTQ) was measured on 12 implants of each group and the peri-implant bone was µ-CT scanned. Bone volume density (BV/TV) was calculated in pre-determined cylindrical volumes, up to 1.5 mm from implant surface. Non-decalcified histology was prepared on the remaining 12 implants from each group, where total bone-to-implant contact (totBIC) and newly-formed BIC (newBIC) was measured. Bone Area Fraction Occupancy (BAFO) was determined in pre-determined areas up to 1.5 mm from implant surface. Paired sample t test or Wilcoxon signed-rank test was used to investigate differences between the groups., Results: Group A presented significantly increased RTQ value at 5 weeks, while no difference was observed at 10 weeks. Group B presented increased BV/TV value at 5 weeks. Both groups showed comparable values for totBIC at both time-points. However, Group A presented significantly lower newBIC at 5 weeks. Higher BAFO was observed in Group B at 5 weeks., Conclusions: Implants inserted into undersized sites has an increased biomechanical performance, but provoked major remodeling of the cortical bone during the early healing period compared to non-undersized preparations. After 10 weeks, no difference was observed., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: To evaluate insertion torque value (ITV) and marginal bone loss (MBL) of an implant system after a clinically perceived bone quality-adapted drilling., Materials and Methods: This multicenter retrospective study included patients treated with implants, conventionally loaded, in completely healed sites. Operators customized the osteotomy preparation according to radiographic assessment and their perception of bone quality. Drilling sequence, bone quality, and ITV were recorded at the time of surgery. Radiographs were taken at the time of implant placement and permanent restoration. MBL between implant placement and permanent restoration was calculated. The implant was used as the statistical unit. Demographic and implant characteristics were shown by means of descriptive statistics. Outcome values were compared using analysis of variance (ANOVA) and Kruskal-Wallis tests. Multiple regression models were used to test the effect of independent variables on ITV and MBL., Results: One hundred eighty-eight implants placed in 87 patients were included in the analysis. The mean observation period was 144 ± 59 days. The mean ITV was 30.8 ± 15.1 Ncm. ITV differed significantly based on arches (mandible/maxilla) (P = .001), bone quality (P < .001), implant diameter (P = .032), and drilling protocol (P = .019). Median MBL was 0.05 mm (0.00; 0.24). A significant difference was found between the mandible and maxilla (P = .008) and between drilling protocols (P = .011). In particular, significantly higher MBL was found in the undersized drilling protocol. Multiple regression analysis showed that ITV was influenced by bone quality and implant diameter. MBL was influenced by bone quality, implant diameter, ITV, and the interaction between bone quality and ITV. It was estimated that MBL was greater with increased bone density and ITV., Conclusion: Excessive ITV in dense bone can cause negative marginal bone responses. A presurgical radiographic assessment and the perception of bone quality are necessary to select an optimal drilling protocol and to minimize surgical trauma.

Purpose: To compile the current evidence on biomechanical, biologic, and clinical outcomes of undersized surgical preparation protocols in dental implant surgery., Materials and Methods: An electronic search using three different databases (PubMed, Web of Science, and Cochrane Library) and a manual hand search were performed including in vitro, animal, and clinical studies published prior to October 2015. Studies in which an undersized drilling protocol was compared with a nonundersized drilling protocol were included., Results: From an initial selection of 1,655 titles, 29 studies met the inclusion criteria, including 14 biomechanical, 7 biologic, 6 biologic and biomechanical, and 2 clinical. Due to methodologic variation, meta-analysis was not performed. Several studies showed that implants inserted with an undersized drilling approach reached a significantly higher insertion torque value than conventional drilling in low-density substrates, while this effect is less evident if a thick cortical layer is present. Similar results in terms of boneto-implant contact (BIC) were achieved in the longer term between implants inserted with undersized and nonundersized protocols. Results in the short term were inconclusive. Clinical studies did not show negative outcomes for undersized drilling, although clinical evidence was sparse. No data are available on marginal bone loss., Conclusion: From the biomechanical standpoint, an undersized drilling protocol is effective in increasing insertion torque in low-density bone. Biologic response in long-term healing after undersized implant placement is comparable to that in the nonundersized surgical drilling protocol. Clinical studies indicate that performing an undersized drilling protocol on low-density bone is a safe procedure; however, more extensive studies are needed to confirm these data.