The precision of drill calibration for dynamic navigation.

OBJECTIVES: To quantify the reproducibility of the drill calibration process in dynamic navigation guided placement of dental implants and to identify the human factors that could affect the precision of this process in order to improve the overall implant placement accuracy. METHODS: A set of six drills and four implants were calibrated by three operators following the standard calibration process of NaviDent® (ClaroNav Inc.). The reproducibility of the position of each tip of a drill or implant was calculated in relation to the pre-planned implants' entry and apex positions. Intra- and inter-operator reliabilities were reported. The effects of the drill length and shape on the reproducibility of the calibration process were also investigated. The outcome measures for reproducibility were expressed in terms of variability range, average and maximum deviations from the mean distance. RESULTS: A satisfactory inter-rater reproducibility was noted. The precision of the calibration of the tip position in terms of variability range was between 0.3 and 3.7 mm. We noted a tendency towards a higher precision of the calibration process with longer drills. More calibration errors were observed when calibrating long zygomatic implants with non-locking adapters than with pointed drills. Flexible long-pointed drills had low calibration precision that was comparable to the non-flexible short-pointed drills. CONCLUSION: The clinicians should be aware of the calibration error associated with the dynamic navigation placement of dental and zygomatic implants. This should be taken in consideration especially for long implants, short drills, and long drills that have some degree of flexibility. CLINICAL SIGNIFICANCE: Dynamic navigation procedures are associated with an inherent drill calibration error. The manual stability during the calibration process is crucial in minimising this error. In addition, the clinician must never ignore the prescribed accuracy checking procedures after each calibration process.

Accuracy of dental implants positioning in computer-assisted surgeries: In vitro study.

OBJECTIVES: The aim of this study is to presents an experimental method for surgical guide confection using an intraoral scanner to obtain a 3D model of the patient's complete denture and compare its accuracy with the conventional methodology using computed tomography. STUDY DESIGN: This prospective in-vitro study used 30 polyurethane pre-manufactured mandibles which were divided into two groups, conventional technique (group I) and a new method using intraoral scanner (group II), establishing the virtually planned position of the dental implants as a control group, considered as the gold standard for postoperative comparison. RESULTS: The difference between these methods is close to zero and not statistically significant (p > 0.05), being heigh deviation (Xh) with p:0.130 and angulation difference of dental implants between the groups (Ang) with p:0.396. CONCLUSION: The acquisition of stereolithography image of the prosthesis using an intraoral scanner has a clinically acceptable accuracy, being in agreement with the conventional method.

Relationship between Implant Length and Implant Stability of Single-Implant Restorations: A 12-Month Follow-Up Clinical Study.

Background and Objectives: Implant stability in vivo is contingent on multiple factors, such as bone structure, instrument positioning and implant surface modifications, implant diameter, and implant length. Resonance-frequency analysis is considered a non-invasive, reliable, predictable, and objective method by which to evaluate implant stability, due to its correlation with bone-to-implant contact. The purpose of this study was to evaluate the effect of implant length on the primary and secondary stability of single-implant crown rehabilitations, as measured by resonance-frequency analysis at different times. Materials and Methods: Implants of 10 and 11.5 mm were placed, and the resonance frequency was measured at the time of surgery (T0), as well as at 3 (T1), 6 (T2), and 12 (T3) months post-surgery. Results: A total of 559 implants were placed in 195 patients. Significant differences were observed when comparing the implant stability quotient (ISQ) values at T1, with values for 10-mm implants being greater than those for 11.5-mm implants (p = 0.035). These differences were also observed when comparing ISQ values for buccal and lingual areas. At T0, T2, and T3, no significant differences in ISQ values were observed. The use of 10-mm implants in the anterior maxilla yielded significantly greater values at T0 (p = 0.018) and T1 (p = 0.031) when compared with 11.5-mm implants. Significant differences in measurements were observed only for buccal areas (p = 0.005; p = 0.018). When comparing the sample lengths and sex, women with 11.5-mm implants showed significantly lower results than those with 10-mm implants (p < 0.001). Conclusions: There is a direct relationship between implants of a smaller length and greater ISQ values, with this relationship being most evident in the maxilla and in women.

Potential Deviation Factors Affecting Stereolithographic Surgical Guides: A Systematic Review.

OBJECTIVE: The aim of this study was to review potential deviation factors in stereolithographic surgical guides for dental implantology, warnings, and limitations of the system. METHODS: An electronic search in databases EMBASE, the Cochrane Library, and PubMed were conducted by 3 researchers to collect information on the accuracy of static computer-guided implant placement to summarize and analyze the overall accuracy. The latter included a search for correlations between factors such as support (teeth/mucosa/bone), number of templates, use of fixation pins, jaw, template production, guiding system, and guided implant placement in articles related to guided surgery with stereolithographic static systems. Studies published between 2012 and 2017 were reviewed. RESULTS: From 761 identified articles, a total of 24 articles were reviewed, which included 2767 dental implants. Data from studies analysis had shown a mean deviation of 3.08 degrees in angular position, 1.14 at the entry point, and 1.46 at apex position. Involved deviation factors were related to planning, laboratory, and surgical phases. CONCLUSION: Guided surgery may have a limited precision as technique, which surgeons need to be aware in the planning process. This review suggests some security measures in guided surgery process.

Implant placement for patients with cleft lip and palate: A clinical report and guidelines for treatment.

The multidisciplinary teams involved in the treatment of individuals with cleft lip and palate are challenged when implants are indicated in the cleft area. Difficulties include obtaining a healthy peri-implant area and, especially, obtaining the natural-looking papilla essential for esthetic success. The area affected by the cleft has a bone deficiency, which is typically augmented with an alveolar bone graft at adolescence. Guidelines for the 3-dimensional placement of implants at the cleft area are presented based on clinical reports. The patients were followed up for at least 1 year. Adoption of the proposed guidelines enables satisfactory esthetic and functional outcomes in patients with cleft lip and palate.

A Comparative Study with Biphasic Calcium Phosphate to Deproteinized Bovine Bone in Maxillary Sinus Augmentation: A Prospective Randomized and Controlled Clinical Trial.

PURPOSE: The purpose of this study was to evaluate a new graft material, biphasic calcium phosphate, composed of 60% hydroxyapatite and 40% ß-Tricalcium phosphate and deproteinized bovine bone mineral, which is established as a predictable graft material for maxillary sinus augmentation. MATERIALS AND METHODS: Maxillary sinus augmentation was performed with different bone materials. Bone biopsies were performed on tissue harvested from the future implant bed using a trephine bur at 6 months after maxillary sinus augmentation. Resonance frequency analysis was performed immediately and at 6 months after the implant placement. Microcomputed tomography and histomorphometric analysis were performed in all patients. RESULTS: Fifty-six patients (60 sinuses) were included in the study. At 6 months postoperative, 31 biopsies were performed on tissues harvested from the calcium phosphate, and 29 biopsies on tissues from the bovine bone grafts. There was no implant failure during the 21-month mean follow-up period. The overall implant stability quotient values were higher than 60, and gradually increased for 6 months. Higher new bone volume fraction and new bone surface density were observed in the calcium phosphate group compared with the bovine bone group. In contrast, residual bone graft volume in the bovine bone group was higher than that in the calcium phosphate group. Nevertheless, there was no significant difference between groups in the microcomputed tomography and histomorphometric parameters. CONCLUSION: Within the study's limitations, both graft materials demonstrated similar biocompatibility and osteoconductivity in the maxillary sinus augmentation.

Biomechanical aspects: Summary and consensus statements of group 4. The 5th EAO Consensus Conference 2018.

OBJECTIVES: The aim of the present publication was to report on the EAO Workshop group-4 discussions and consensus statements on the five reviews previously prepared. These reviews provided the scientific evidence on the effect of crown-to-implant ratio, on reconstructions with cantilevers in fully and partially edentulous patients, on biological and technical complications of tilted in comparison with straight implants, and on the effects of osseointegrated implants functioning in a residual dentition. MATERIAL AND METHODS: The group discussed, evaluated, corrected where deemed appropriate, and made recommendations to the authors regarding the following five reviews submitted: (a) Is there an effect of crown-to-implant ratio on implant treatment outcomes?; (b) Implant-supported cantilevered fixed dental rehabilitations in fully edentulous patients; (c) and in partially edentulous patients; (d) Biological and technical complications of tilted implants in comparison with straight implants supporting fixed dental prostheses; (e) What are the adverse effects of osseointegrated implants functioning among natural teeth of a residual dentition? Based on the five manuscripts and the discussion among the group as well as the plenum members, the major findings were summarized, consensus statements were formulated, clinical recommendations were proposed, and areas of future research were identified. RESULTS: Crown-to-implant ratios ranging from 0.9 to 2.2 did not influence the occurrence of biological or technical complications also in single-tooth restorations. Reconstructions with cantilevers for the rehabilitation of fully and partially edentulous jaws showed high implant and reconstruction survival rates. In contrast, the rate of complications-in particular associated with veneering material-was high during the observation period of 5-10 years. The data reported were primarily derived from studies with high risk of bias. The data for single-implant reconstructions were small. There was no evidence that distally tilted implants were associated with higher failure rates and increased amounts of marginal bone loss. The data supporting these findings, however, were at high risk of bias and frequently incompletely reported. Frequent positional changes occurred between the natural teeth and the implant-supported restorations. These changes were more pronounced in younger individuals, and even though they were reduced with age, they still occurred in adult patients. Even though these changes were frequent, potential implications for the patient are unclear. CONCLUSIONS: The use of single-tooth restorations with crown-to-implant ratio in between 0.9 and 2.2 may be considered a viable treatment option. Multiunit reconstructions with cantilevers are a viable treatment option in fully and partially edentulous patients. Clinicians and patients should be aware, however, that complications are frequent and primarily related to resin material used for veneering. There is some evidence that tilting an implant does affect stability of the implant and the surrounding bone. Treatment options to tilted implants should carefully be considered, as the effect on soft tissues and on prosthesis behavior is poorly reported for tilted implants. Positional changes in the dentition in relation to implant-supported restorations occur frequently. The patient should be informed about the possible need for a treatment related to these changes in the long term.

Dental implant register: Summary and consensus statements of group 2. The 5th EAO Consensus Conference 2018.

OBJECTIVES: This publication reports the EAO Workshop group-2 and consensus plenary discussions and statements on a narrative review providing the background and possible facilities and importance of a dental implant register, to allow for a systematic follow-up of the clinical outcome of dental implant treatment in various clinical settings. It should be observed that the format of the review and the subsequent consensus report consciously departs from conventional consensus publications and reports. MATERIAL AND METHODS: The publication was a narrative review on the presence and significance of quality registers regarding select medical conditions and procedures. The group discussed and evaluated the publication and made corrections and recommendations to the authors and agreed on the statements and recommendations described in this consensus report. RESULTS: Possible registrations to be included in an implant register were discussed and agreed as a preliminary basis for further development, meaning that additional parameters be included or some be deleted. CONCLUSIONS: It was agreed to bring the idea of an implant quality register, including the presented results of discussions and proposals by the group- and plenary sessions, to the EAO Board for further discussion and decision.

Dental Implant Quality Register-A possible tool to further improve implant treatment and outcome.

The Board of EAO (European Association for Osseointegration) has discussed an initiative to explore the conditions to establish a Dental Implant Register. It was suggested to bring this issue to the EAO Consensus Conference 2018 for a discussion and to possibly propose relevant and manageable parameters. This article presents some select examples from quality registers in the medical field. Based on the experience of established registers, essentially in the medical field, factors considered to be of importance, if and when establishing a Dental Implant Register are introduced and discussed.

Group 2 ITI Consensus Report: Prosthodontics and implant dentistry.

OBJECTIVES: Working Group 2 was convened to address topics relevant to prosthodontics and dental implants. Systematic reviews were developed according to focused questions addressing (a) the number of implants required to support fixed full-arch restorations, (b) the influence of intentionally tilted implants compared to axial positioned implants when supporting fixed dental prostheses (FDPs), (c) implant placement and loading protocols, (d) zirconia dental implants, (e) zirconia and metal ceramic implant supported single crowns and (f) zirconia and metal ceramic implant supported FDPs. MATERIALS AND METHODS: Group 2 considered and discussed information gathered in six systematic reviews. Group participants discussed statements developed by the authors and developed consensus. The group developed and found consensus for clinical recommendations based on both the statements and the experience of the group. The consensus statements and clinical recommendations were presented to the plenary (gathering of all conference attendees) and discussed. Final versions were developed after consensus was reached. RESULTS: A total of 27 consensus statements were developed from the systematic reviews. Additionally, the group developed 24 clinical recommendations based on the combined expertise of the participants and the developed consensus statements. CONCLUSIONS: The literature supports the use of various implant numbers to support full-arch fixed prostheses. The use of intentionally tilted dental implants is indicated when appropriate conditions exist. Implant placement and loading protocols should be considered together when planning and treating patients. One-piece zirconia dental implants can be recommended when appropriate clinical conditions exist although two-piece zirconia implants should be used with caution as a result of insufficient data. Clinical performance of zirconia and metal ceramic single implant supported crowns is similar and each demonstrates significant, though different, complications. Zirconia ceramic FDPs are less reliable than metal ceramic. Implant supported monolithic zirconia prostheses may be a future option with more supporting evidence.

Guidelines for development of Implant Dentistry in the next 10 years regarding innovation, education, certification, and associations.

BACKGROUND: During the third Summer Camp of European Association of Osseointegration (EAO), 40 junior representatives from various European societies and associations were brought together to discuss and explore the following topics in Implant Dentistry in the next 10 years: (I) certification, (II) societies and associations, (III) continuing education, and (IV) innovations. AIMS: The aims of all working groups were to identify and outline the present situation in the area of the selected topic and to propose improvements and innovations to be implemented in the following 10 years. MATERIALS AND METHODS: Four different groups were assigned randomly to one of the four working units. The method to discuss the selected topics was World Cafè. The summaries of four topics were then given to all participants for peer review. RESULTS AND CONCLUSIONS: All four groups presented the conclusions and guidelines accordingly: (I) The recognition for Implant Dentistry and accreditation of training programs would lead to an improvement of the quality of care to the benefit of the patients; (II) Dental associations and societies have to continuously improve communication to meet needs of dental students, professionals, and patients (III) European Dental Board should be installed and become responsible for continue dental education; (IV) dental engineering, peri-implant diseases, and digital workflow in dentistry currently have limited tools that do not guarantee predictable results.

A multiscale analytical approach to evaluate osseointegration.

Osseointegrated implants are frequently used in reconstructive surgery, both in the dental and orthopedic field, restoring physical function and improving the quality of life for the patients. The bone anchorage is typically evaluated at micrometer resolution, while bone tissue is a dynamic composite material composed of nanoscale collagen fibrils and apatite crystals, with defined hierarchical levels at different length scales. In order to understand the bone formation and the ultrastructure of the interfacial tissue, analytical strategies needs to be implemented enabling multiscale and multimodal analyses of the intact interface. This paper describes a sample preparation route for successive analyses allowing assessment of the different hierarchical levels of interest, going from macro to nano scale and could be implemented on single samples. Examples of resulting analyses of different techniques on one type of implant surface is given, with emphasis on correlating the length scale between the different techniques. The bone-implant interface shows an intimate contact between mineralized collagen bundles and the outermost surface of the oxide layer, while bone mineral is found in the nanoscale surface features creating a functionally graded interface. Osteocytes exhibit a direct contact with the implant surface via canaliculi that house their dendritic processes. Blood vessels are frequently found in close proximity to the implant surface either within the mineralized bone matrix or at regions of remodeling.

An In Vitro Model to Evaluate the Accuracy of Guided Implant Placement Based on the Surgeon's Experience.

PURPOSE: To evaluate whether there are differences in the accuracy of guided implant placement based on the surgeon's experience level. MATERIALS AND METHODS: Fifteen surgeons, divided into three groups based on experience level (group I, expert; group II, intermediate; group III, novice), placed six implants in five identical mandibles (75 mandibles and 450 implants). A planning and stereolithographic guide was generated using cone beam computed tomography (CBCT) images and implant planning software (Nemoscan, Nemotec) and was used in all cases. After the implants were placed in each mandible, another scan was taken, and the three-dimensional (3D) images of each scan were blended with the images in the planning guide to evaluate any deviations. Any differences in platform and apex position and the angle of the implant were measured. The differences between each surgeon and each group were compared using multivariate analysis of variance (MANOVA). RESULTS: There were significant differences in the implant angles among the three groups (P = .001). Group III (novices) presented the greatest angle deviation and showed more deviations than group I (experts) (P = .024) and group II (intermediate) (P = .001) did. There were no significant differences between groups I and II (P = .368). There were no significant differences among the groups in terms of platform (P = .135) and apex position (P = .092). CONCLUSION: Some degree of deviation can occur between the planned placement of the implant and its definitive placement, and this deviation may be influenced by the surgeon's experience. Expert surgeons show less angle deviation than novice surgeons. Although these differences (less than 0.5 degrees) are statistically significant, they may be considered clinically irrelevant.

Experimental investigation of commercial small diameter dental implants in porcine mandibular segments.

Small diameter (mini) dental implants have become more popular in recent years as alternatives to classical implant treatment in clinical cases with critical bony situations. However, an in-depth scientific analysis of the mechanical and biomechanical effects of small diameter implants has not yet been published. The aim of the present study was to investigate experimentally different commercial mini implants by measuring their displacements under immediate loading. Twelve commercially available mini implants were measured. Implants were inserted into porcine mandibular segments and loaded by means of a predefined displacement of 0.5 mm of the loading system. The implants were loaded at an angle of 30° to the implant long axis using the self-developed biomechanical hexapod measurement system. Implant displacements were registered. The experimental results were compared to the numerical ones from a previous study. Measured implant displacements were within the range of 39-194 µm. A large variation in the displacements was obtained among the different implant systems due to the different designs and thread profiles. Comparing experimental and numerical results, the displacements that were obtained numerically were within the range of 79-347 µm. The different commercial mini implants showed acceptable primary stability and could be loaded immediately after their insertion.

A Two-Year Evaluation of a Sloped Marginal Contour Implant System Placed in Healed Sites.

PURPOSE: The purpose of this clinical trial was to evaluate the survival rate, bone remodeling, and soft tissue health around sloped marginal contour implants when placed in healed sites posteriorly in the mouth. MATERIALS AND METHODS: Implants were placed in healed sites at premolar and molar regions. After a 3-month osseointegration period, definitive prostheses were connected. Clinical and radiographic examinations were performed at implant placement and then 1, 3, 6, 12, and 24 months after implant placement. An assessment of implant stability, peri-implant mucosa, level of attached gingivae, occlusion, proximal contact, and marginal bone levels was performed at each respective visit. RESULTS: Fourteen patients were treated and restored with 18 single crowns. The cumulative survival rate was 100% after 2 years. The mean marginal bone remodeling was 0.04 ± 0.26 mm (n = 18). The attached gingival change was +0.33 ± 0.35 mm. CONCLUSION: The 24-month results indicate that the sloped marginal contour implant performed well in posterior healed sites with a 100% survival rate and good marginal bone maintenance.

The Survival of Morse Cone-Connection Implants with Platform Switch.

PURPOSE: The aim of this prospective clinical study was to evaluate the survival up to 5 years of Morse cone-connection implants with platform switch considering the influence of biologically relevant, anatomical, and stress-related variables. STROBE guidelines were followed. MATERIALS AND METHODS: Seven hundred forty-eight implants were inserted in 350 patients. Follow-up visits were scheduled at the time of stagetwo surgery (2 months later) and at 6, 12, 24, 36, and 60 months. All implants were initially loaded with a cemented provisional acrylic restoration. The definitive metal-ceramic restorations were cemented at the 6-month follow-up. Implant cumulative survival rates (CSRs) were calculated using life table actuarial method. Survival data were also analyzed by the log-rank test and Cox regression. The statistical analysis was conducted at the patient level. P ≤ .05 was considered as an indicator of statistical significance. RESULTS: During the follow-up (mean: 40 months; SD: 20.27), 28 patients were considered failed (8%). The CSR and its standard error (SE) was 92% ± 2.17%. Patients with implant-supported single crowns had a CSR of 90%, whereas those with implant-supported fixed dental prostheses had a CSR of 93%. The implant diameter (P = .0399) and implant length (P = .0441) were statistically significant. The probability of failure was almost 75% lower for patients with wide rather than standard implants, 91% lower for patients with long implants, and 69% lower for patients with standard implants compared with short implants. CONCLUSION: The use of Morse cone-connection implants with platform switch is a safe and reliable treatment method. Stress-related variables influence the risk of failure confirming the importance of biomechanical factors in the longevity of osseointegrated implants; thus, the clinician may obtain better results if attention is paid to these factors.

Relationship Between Primary Stability and Crestal Bone Loss of Implants Placed with High Insertion Torque: A 3-Year Prospective Study.

PURPOSE: Concerns have been expressed about the possibility of high insertion torque (IT) causing necrosis, impaired osseointegration, and crestal bone loss over time. The present study investigated the relationship between primary stability and implant success, including early and late maintenance of crestal bone levels. MATERIALS AND METHODS: Implants were placed in patients at three study centers. Every effort was made to achieve the highest possible primary stability, which was measured with IT and implant stability quotient (ISQ). The IT and ISQ at insertion and reopening (3 to 4 months), as well as bone levels at several points in time, were recorded. The correlations between IT, ISQ, and immediate and 3-year crestal bone loss were investigated through linear regression analyses. RESULTS: Average IT was 76.1 ± 20.8 Ncm, while the average ISQ score was 80.4 ± 8.4. The implant success rate at 36 months was 98.6%. The crestal bone loss around most implants (41.0%) ranged from 0.05 to 0.5 mm. None of the osseointegrated implants had crestal bone loss greater than 2.5 mm. The linear regression analysis showed no correlation among early or 3-year crestal bone loss and IT, ISQ at surgery, and ISQ at reopening. CONCLUSION: The implants studied avoided any negative effects deriving from the high IT values (≥ 50 Ncm) applied during 3 years of follow-up.

Success and Survival Rates of Dental Implants Restored at an Undergraduate Dental Clinic: A 13-Year Retrospective Study with a Mean Follow-up of 5.8 Years.

PURPOSE: The purpose of this study was to evaluate the clinical, radiographic, and patient-based outcomes of dental implants placed at an undergraduate student dental clinic. MATERIALS AND METHODS: A retrospective study was performed to determine the success and survival rates of dental implants placed at the undergraduate dental clinic at Dalhousie University between January 1999 and January 2012. Only patients with a minimum of 1-year follow-up were included. Clinical and radiographic assessments determined implant success and survival rates. Questionnaires recorded patients' satisfaction with esthetics, comfort, and ease of hygiene. RESULTS: Of the 352 patients (n = 591 implants) who received implants over 13 years, 165 patients completed the clinical and radiographic examinations. By the end of the study period, demographic information and implant characteristics were collected for 111 (n = 217 implants; 47.5% in the maxilla, 52.6% in the mandible) of these patients. Of those assessed clinically, 36.4% were males and 63.6% females, with a mean age of 56.1 ± 14.15 years (range, 17 to 86 years) at the time of implant placement. The mean follow-up period was 5.8 years (range, 1 to 13 years). The overall implant success and survival rates were 88.0% and 97.2%, respectively. No observable bone loss was evident in 88.0% of the surviving implants. There were no implant fractures. Most patients (91.2%) were very satisfied with the implant restoration appearance, 88.0% were very comfortable with the implant, 92.6% were very satisfied with their ability to chew, and 84.8% reported easy hygiene maintenance at the implant sites. CONCLUSION: Implant success and survival in an undergraduate student clinic were comparable to those reported in the literature. It seems that inexperienced students were able to provide restorations that were very satisfying to the patients.

Evaluation of a Reverse-Tapered Design on the Osseointegration of Narrow-Diameter Implants in Beagle Dogs: A Pilot Study.

PURPOSE: The purpose of this study was to evaluate a reverse-tapered design on the osseointegration of narrow-diameter implants in comparison with a conventional tapered design in beagle dogs. MATERIALS AND METHODS: All mandibular premolars and first molars were extracted bilaterally in four beagle dogs. Three months later, three kinds of implants were placed in both quadrants of the mandible: tapered narrow-diameter implants processed by cold working (TNC; n = 8), reverse-tapered narrow-diameter implants (RTN; n = 8), and reverse-tapered narrow-diameter implants processed by cold working (RTNC; n = 8). The animals were sacrificed at 4 weeks. Implant stability quotient (ISQ) values were measured at the time of implant placement and sacrifice. Histomorphometric analysis was performed. RESULTS: The baseline ISQ values were significantly lower in the RTN (56.0 ± 11.6) and RTNC (57.2 ± 9.8) than in the TNC (68.0 ± 5.4; P = .021). At 4 weeks, the TNC (69.9 ± 5.1) exhibited significantly higher ISQ values compared with the RTNC (61.6 ± 4.1; P = .024). Histologic analysis in the RTN and RTNC revealed osseointegration without any signs of inflammation; however, unresolved coronal gap or dehiscence was also observed. The total bone-to-implant contact ratios (BIC) in TNC, RTN, and RTNC were 55.1% ± 11.5%, 47.8% ± 19.1%, and 60.2% ± 15.3%, respectively, and no significant differences were shown among them. The BIC for the coronal part in each group was 51.1% ± 29.4%, 28.8% ± 33.8%, and 23.9% ± 23.3%, respectively, and the differences were not significant. In the threaded part, TNC, RTN, and RTNC showed a BIC of 56.3% ± 9.6%, 50.7% ± 18.3%, and 65.3% ± 15.6%, respectively. There was no significant difference among them. CONCLUSION: The reverse-tapered design on narrow-diameter implants showed a lower initial stability than the conventional tapered design; however, there was equivalent osseointegration in an early healing phase.

Loss of Accuracy of Torque Wrenches Due to Clinical Use and Cleaning Procedure: Short Communication.

PURPOSE: The aim of this study was to investigate the way intensive use and multiple cleanings of torque wrenches may interfere with accurary over time. MATERIALS AND METHODS: Three different brands (one spring-style and two friction-style types) were tested at baseline and after enduring mechanical testing (1,000 cycles) and cleaning in a thermal disinfector (150 cycles). Torque wrenches were tested at a predetermined value of 30 Ncm at given intervals, and true values were registered by means of a digital torque gauge. RESULTS: All measured values varied between 28.3 Ncm and 31.1 Ncm. Only the spring-style torque wrench revealed values that differed significantly from baseline after both mechanical testing (P < .001) and cleaning (P < .05). CONCLUSION: The spring-style torque wrench produced values that changed significantly after multiple mechanical and multiple cleaning cycles. However, the differences were small and the measured values from all tested specimens were close to the predetermined value of 30 Ncm.