The influence of insertion torque values on the failure and complication rates of dental implants: A systematic review and meta-analysis

High insertion torque versus regular insertion torque: early crestal bone changes on dental implants in relation to primary stability-a retrospective clinical study

The aim of the presented retrospective study was to evaluate the early crestal bone changes around an implant type designed for high primary stability. A total number of 111 implants placed clinically were evaluated regarding insertion torque, bone density, implant stability quotient (ISQ) and early crestal bone loss from standardized digital radiographs. The implants were allocated in two groups: the "regular torque " group contained all implants that achieved less than 50 Ncm as final insertion torque (n = 63) and the "high torque" group contained the implants that achieved 50-80 Ncm (n = 48). To avoid possible damage either to the implant´s inner connection or to the bone by application of excessive force, a limit of 80 Ncm was set for all surgeries. All implants underwent submerged healing for three months. ISQ measurements and standardized digital radiographs were taken at day of insertion and at day of second stage surgery. The bone loss was measured on the mesial and distal aspect of the implant. The data evaluation showed the following results: Mean bone loss was 0.27 ± 0.30 mm for the high torque group and 0.24 ± 0.27 mm for the regular torque group. The difference was not statistically significant (p = 0.552). In the two groups, no complications nor implant loss occurred. For the evaluated implant type, there was no significant difference in crestal bone changes and complication rate between high and regular insertion torque in the early healing period.

Survival Rate of Dental Implants in the Cleft Area: A Cross-Sectional Retrospective Study

This study aimed to evaluate the survival rate of osseointegrated implants installed in the cleft area. An extensive data survey was conducted using the medical records of individuals who had implants installed in the cleft area between 1999 and 2020. The variables assessed were age, sex, implant follow-up time, implantation procedures, and rehabilitation with implant-supported prostheses. Data were analyzed in terms of implant survival time, correlating with the factors: age, sex, execution, or no-execution of bone regrafting, the time interval between secondary alveolar bone grafting and regrafting, the time interval between regrafting and implant installation, and the time interval between implant installation and provisional and definitive prosthesis. Data were analyzed with respect to implant survival. χ 2 and Student t tests were used with a 5% significance level. A total of 1295 medical records were analyzed, of which 688 reported implants in cleft areas (56.1% in females, 43.9% in males) with a success rate of 92.73% and a mean follow-up time of 53.2 (±45.0) months. There were no statistically significant differences in the correlation between the survival rate and sex ( P = 0.895, χ 2 test), between the implant survival rate and regrafted area ( P = 0.904, χ 2 test), or between the survival rate and patient age ( P = 0.246, Student t test). The survival rate of implants in the cleft area was 92.73%. Age, sex, and the need for regrafting did not influence the survival rate of implants installed in the cleft area. Clinical studies that evaluate the survival rate of implants installed in patients with cleft maxilla are of great relevance to the dental field.

Influence of Implant Macro-Design, -Length, and -Diameter on Primary Implant Stability Depending on Different Bone Qualities Using Standard Drilling Protocols-An In Vitro Analysis

(1) Background: Primary implant stability is vital for successful implant therapy. This study explores the influence of implant shape, length, and diameter on primary stability in different bone qualities. (2) Methods: Three implant systems (two parallel-walled and one tapered) with various lengths and diameters were inserted into polyurethane foam blocks of different densities (35, 25, 15, and 10 PCF) using standard drilling protocols. Primary stability was assessed through insertion torque (IT) and resonance frequency analysis (RFA). Optimal ranges were defined for IT (25 to 50 Ncm) and RFA (ISQ 60 to 80). A comparison of implant groups was conducted to determine adherence to the optimal ranges. (3) Results: Implant macro-design, -length, and -diameter and bone block density significantly influenced IT and RFA. Optimal IT was observed in 8/40 and 9/40 groups for the parallel-walled implants, while the tapered implant achieved optimal IT in 13/40 groups (within a 25-50 Ncm range). Implant diameter strongly impacted primary stability, with sufficient stability achieved in only one-third of cases despite the tapered implant's superiority. (4) Conclusions: The findings highlight the need to adapt the drilling protocol based on diverse bone qualities in clinical practice. Further investigations should explore the impact of these adapted protocols on implant outcomes.

In Vitro Study of Zirconia Surface Modification for Dental Implants by Atomic Layer Deposition

Zirconia is a promising material for dental implants; however, an appropriate surface modification procedure has not yet been identified. Atomic layer deposition (ALD) is a nanotechnology that deposits thin films of metal oxides or metals on materials. The aim of this study was to deposit thin films of titanium dioxide (TiO₂), aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), and zinc oxide (ZnO) on zirconia disks (ZR-Ti, ZR-Al, ZR-Si, and ZR-Zn, respectively) using ALD and evaluate the cell proliferation abilities of mouse fibroblasts (L929) and mouse osteoblastic cells (MC3T3-E1) on each sample. Zirconia disks (ZR; diameter 10 mm) were fabricated using a computer-aided design/computer-aided manufacturing system. Following the ALD of TiO₂, Al₂O₃, SiO₂, or ZnO thin film, the thin-film thickness, elemental distribution, contact angle, adhesion strength, and elemental elution were determined. The L929 and MC3T3-E1 cell proliferation and morphologies on each sample were observed on days 1, 3, and 5 (L929) and days 1, 4, and 7 (MC3T3-E1). The ZR-Ti, ZR-Al, ZR-Si, and ZR-Zn thin-film thicknesses were 41.97, 42.36, 62.50, and 61.11 nm, respectively, and their average adhesion strengths were 163.5, 140.9, 157.3, and 161.6 mN, respectively. The contact angle on ZR-Si was significantly lower than that on all the other specimens. The eluted Zr, Ti, and Al amounts were below the detection limits, whereas the total Si and Zn elution amounts over two weeks were 0.019 and 0.695 ppm, respectively. For both L929 and MC3T3-E1, the cell numbers increased over time on ZR, ZR-Ti, ZR-Al, and ZR-Si. Particularly, cell proliferation in ZR-Ti exceeded that in the other samples. These results suggest that ALD application to zirconia, particularly for TiO₂ deposition, could be a new surface modification procedure for zirconia dental implants.

Marginal Bone Loss and Treatment Complications with Mandibular Overdentures Retained by Two Immediate or Conventionally Loaded Implants—A Randomized Clinical Trial

This study aimed to assess marginal bone loss and complication rates of mandibular overdentures retained on two implants with conventional and immediate loading protocols. Twenty edentulous patients were treated with mandibular two-implant-retained overdentures and new complete maxillary dentures. In one half of the sample, the implants were loaded immediately by VulkanLoc® abutments. In the counterpart group, these abutments were connected to the implants two months after implant placement (conventional protocol). Treatment outcomes were evaluated at 2, 6, and 12 months after implant placement. According to the pre- and post-insertion radiographs, there was a mean marginal bone loss of 0.25–0.59 mm (CI 95%) after 13.4 ± 2.1 months of follow-up. There were no significant differences between groups. The failure rate (percentage of implants failing per year) was slightly higher in the conventional loading group (14.0 ± 32.7%) than in the immediate loading group (8.3 ± 18.0%). The findings of the present study suggested that there were no differences in marginal bone loss observed at one year for immediately loaded implants (0.40–0.39 mm) versus conventionally loaded implants (0.44- 0.36 mm) placed for the retention of mandibular overdentures. There were no differences in primary and secondary stability of immediately loaded versus conventional implants; however, in the conventional loading group, stability increased significantly between implant placement compared at both 6 and 12 months post-placement.

Mandibular bone characteristics, drilling protocols, and final insertion torque for titanium-zirconium mini-implants for overdentures: A cross-sectional analysis

OBJECTIVE

The aim of this study was to assess the final insertion torque values achieved using site-specific drilling protocols for a novel mini implant system for removable complete overdentures. Anatomical and technical factors influencing final insertion torque were recorded and analyzed.

MATERIAL AND METHODS

Participants were randomized to two surgical protocol groups (flapped or flapless) and all received four mini implants (Straumann® mini implant system; Straumann AG) in the anterior mandible, using a 1.6 mm needle drill and a 2.2 mm pilot drill for the implant bed site preparation. The final insertion torque was recorded as the main outcome variable during surgery. Bone type, radiographical bone density, ridge form, implant length, and the drilling protocol were considered as independent variables. Descriptive statistics, generalized estimating equations (GEE) regression, and heatmap charts were used for data analyses.

RESULTS

A total of 296 mini implants were placed in 74 patients (mean age = 64.1 ± 8.0; 64.9% female) using flapless (n = 37) or flapped (n = 37) surgeries. Mean final insertion torque was 55.8 ± 18.4 Ncm (10.5% > 35 Ncm, 48.9% between 35 and 65 Ncm, and 40.6% > 65 Ncm). The needle drill was used in only 43.9% of the implant bed sites. Higher final torque values were observed for higher bone densities (bone type I > II > III, and D1-D2 > D3-D4), highly resorbed ridge forms (5-6 > 3-4), flapped surgeries, and male patients. However, regression models showed that the likelihood of achieving optimal insertion torque (≥35 and ≤65 Ncm) was higher for females (OR = 2.14; 95%CI = 1.14-4.01; p = 0.018), ridge forms 3-4 (OR = 2.87; 95%CI = 1.05-7.85; p = 0.040), and flapless surgeries (OR = 1.96; 95%CI = 1.09-3.51; p = 0.024).

CONCLUSIONS

Sufficient primary stability for immediate loading was achieved for the majority of the mini implants placed. Surgical implant bed preparation should be site-specific to achieve optimal primary stability for immediate loading while avoiding excessive insertion torque.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2021 dental literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to coverage of this broad topical area. Specific subject areas addressed, in order of the appearance in this report, include COVID-19 and the dental profession (new); prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence daily dental treatment decisions with an emphasis on future trends in dentistry. With the tremendous volume of dentistry and related literature being published daily, this review cannot possibly be comprehensive. Rather, its purpose is to update interested readers and provide important resource material for those interested in pursuing greater details on their own. It remains our intent to assist colleagues in negotiating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the patients and dental problems they encounter.

Stability of Dental Implants and Thickness of Cortical Bone: Clinical Research and Future Perspectives. A Systematic Review

Dental surgery implantation has become increasingly important among procedures that aim to rehabilitate edentulous patients to restore esthetics and the mastication ability. The optimal stability of dental implants is correlated primarily to the quality and quantity of bone. This systematic literature review describes clinical research focusing on the correlation between cortical bone thickness and primary/secondary stability of dental fixtures. To predict successful outcome of prosthetic treatment, quantification of bone density at the osteotomy site is, in general, taken into account, with little attention being paid to assessment of the thickness of cortical bone. Nevertheless, local variations in bone structure (including cortical thickness) could explain differences in clinical practice with regard to implantation success, marginal bone resorption or anchorage loss. Current knowledge is preliminarily detailed, while tentatively identifying which inconclusive or unexplored aspects merit further investigation.

Comparison of Implant Stability between Regenerated and Non-Regenerated Bone. A Prospective Cohort Study

Implant stability is one of the main indicators of successful osseointegration. Although it has been measured in numerous studies, there has been little research on implant stability in regenerated bone. The study compares primary and secondary stability between implants placed in regenerated versus native bone and evaluates the influence of bone quality on the results. Sixty implants were placed in 31 patients: 30 implants inserted in native bone (non-regenerated) after a healing period of at least 6 months post-exodontia and 30 inserted in regenerated bone at 6 months after grafting with xenograft. Resonance frequency analysis (RFA) was used to obtain implant stability quotient (ISQ) values at baseline (implant placement), 8 weeks, and 12 weeks. Statistically significant differences were found between implants placed in regenerated bone and those placed in native bone at all measurement time points (p < 0.05). ISQ values were significantly influenced by bone quality at baseline (p < 0.05) but not at 8 or 12 weeks. Greater stability was obtained in implants placed in native bone; however, those placed in regenerated bone showed adequate primary and secondary stability for prosthetic loading. Bone quality influences the primary but not secondary stability of the implants in both native and regenerated bone.