Factors affecting accuracy of implant placement with mucosa-supported stereolithographic surgical guides in edentulous mandibles

The influence of guide stabilizers and their application sequences on trueness and precision of surgical guides in free end situations: An in vitro analysis

OBJECTIVES

To evaluate the impact of guide stabilizers and their application sequences on implant placement accuracy of guided implant surgery in multiple teeth loss at free end.

MATERIALS AND METHODS

In this study, 96 implants were placed in the regions of #34, #36, and #37 of 32 identical mandibular models. The influence of using guide stabilizers or not (group A and group B) and various guide stabilizers application sequences (group B: #34 → #36 → #37; group C: #36 → #34 → #37; group D: #37 → #34 → #36) on implant placement trueness and precision was investigated. Data were analyzed using T-tests and one-way ANOVA.

RESULTS

Group B showed significant benefits in enhancing implant placement precision. Compared to group A, it resulted in reducing 3D-deviation at crest and 2D deviation in vestibular-oral direction at both crest and apex. Furthermore, group D demonstrated greater improvement in global implant placement precision by reducing 2D deviation in mesial-distal direction at both crest and apex. Among the three different stabilizer application sequences, group D exhibited the highest level of implant placement precision.

CONCLUSIONS

In cases of missing teeth at distal free end, the use of guide stabilizers and their application sequences does not have a significant impact on implant placement trueness. However, they do improve implant placement precision compared to methods that do not utilize guide stabilizers. Specifically, applying a guide stabilizer first at the furthest implant site to change teeth loss classification from free end to edentulous space with posterior support is the most reliable sequence.

Influence of bone density on the accuracy of artificial intelligence-guided implant surgery: An in vitro study

STATEMENT OF PROBLEM

Artificial intelligence (AI) has been found to be applicable in medical tests and diagnostics. However, studies on the application of AI technology in oral implantology are lacking. In addition, whether bone density affects the accuracy of guided implant surgery has not been determined.

PURPOSE

The purpose of this in vitro study was to determine the clinical reliability of an AI-assisted implant planning software program with an in vitro model. An additional goal was to determine the effect of bone density on the accuracy of static computer-assisted implant surgery (CAIS).

MATERIAL AND METHODS

Ten participants with missing mandibular left first molars were selected for analysis, and surgical fully guided templates were designed by using an AI implant planning software program. Jaw models were produced in 3 filling rate groups (group L: 25%; group M: 40%; group H: 55%, higher filling rate with representatives of the denser simulated bone density) by 3-dimensional (3D) printing. The preoperative and postoperative positions of the implants were compared by measuring the value of deviation through oral scanning. The mean 3D shoulder and apical and angular deviations were calculated for each group. The data were analyzed using 1-way ANOVA (α=.05 corrected for multiple testing by using Bonferroni-Holm adjustment).

RESULTS

The mean ±standard deviation 3D shoulder and apical and angular deviations were 0.80 ±0.32 mm, 1.43 ±0.47 mm, and 3.68 ±1.30 degrees. These values were lower than the clinical safety distance of the fully guided implant template. A significantly lower mean 3D apical deviation (1.12 ±0.33 mm, P=.023) and angular deviation (2.81 ±1.11 degrees, P=.018) were observed in group L than in group H (1.68 ±0.37 mm, 4.32 ±0.99 degrees). However, no significant differences were found among the 3 groups in 3D deviation at the shoulder (P>.05).

CONCLUSIONS

AI implant planning software program could design the ideal implant position through self-learning. The accuracy of the AI-assisted designed implant template in this study indicated its clinical reliability. Higher bone density led to increased implant deviations.

Position of digitally guided implants in completely edentulous maxillae by using a modified double-scan and overlap of three digital surface protocol

STATEMENT OF PROBLEM

In patients with a completely edentulous maxilla, the variability in resilience and mucosal thickness and the lack of teeth and rigid supporting structures may lead to poor adaptation of the surgical guide and significant variation in the definitive implant position. Whether a modified double-scan technique with overlap of surfaces will improve implant placement is unclear.

PURPOSE

The purpose of this prospective clinical study was to evaluate the 3-dimensional position and the correlation of 6 dental implants in participants with a completely edentulous maxilla using a mucosa-supported flapless surgical guide designed with 3 matched digital surfaces obtained with a modified double-scan protocol.

MATERIAL AND METHODS

Dental implants were installed with an all-on-6 protocol in the edentulous maxilla of participants at the Santa Cruz Public Hospital, Chile. A stereolithographic mucosa-supported template was fabricated from a cone beam computed tomography (CBCT) scan made with a prosthesis with 8 radiopaque ceramic spheres inserted and by scanning the same prosthesis with an intraoral scanner. The mucosa was obtained by digitally casting the relining of the removable complete denture in the design software program. After 4 months, a second CBCT scan was obtained to evaluate the position of the installed implants measured at 3 locations: apical, coronal, platform depth, and angulation. Differences in position between the 6 implants in the completely edentulous maxilla and their linear correlation at the measured points were compared with the Kruskal-Wallis and Spearman correlation tests (α=.05).

RESULTS

Sixty implants were installed in 10 participants (age 54.3 ±8.2 years; 7 women). The average deviation in the apical axis was 1.02 ±0.9 mm, coronal 0.76 ±0.74 mm, platform depth 0.92 ±0.8 mm, and the major axis angulation of the 6 implants was 2.92 ±3.65 degrees. The implant in the maxillary left lateral incisor region had the most significant deviation in apical and angular points (P<.05). A linear correlation between apical-to-coronal deviations and apical-to-angular deviations was observed for all implants (P<.05).

CONCLUSIONS

A stereolithographic mucosa-supported guide designed with the overlap of 3 digital surfaces had average dental implant position values similar to those reported by systematic reviews and meta-analyses. In addition, implant position varied based on the location of the implant installation in the edentulous maxilla.

Evaluation of the passive fit and definitive marginal fit of prefabricated and conventional CAD-CAM milled titanium bars with a fully guided surgical protocol: An in vitro study

STATEMENT OF PROBLEM

Computer-aided design and computer-aided manufacturing (CAD-CAM) milled titanium bars have shown good clinically acceptable passive fit and definitive marginal fit; however, investigations into the passive fit and definitive marginal fit of prefabricated CAD-CAM milled titanium bars are lacking.

PURPOSE

The purpose of this in vitro study was to compare and evaluate the passive fit and definitive marginal fit of prefabricated and conventional CAD-CAM milled titanium bars.

MATERIAL AND METHODS

A total of 10 polyurethane radiopaque anatomic completely edentulous mandibular models had implants (Biohorizons) placed in the left and right canine and second premolar positions using a 3-dimensionally printed fully guided surgical guide. For the conventional bars, impressions were made, and casts were scanned and exported to a software program (exocad 3.0). For the prefabricated bars, the surgical plans were exported from the software program directly. The Sheffield test was used to evaluate the passive fit of the bars, and marginal fit was evaluated with a scanning electron microscope at ×50 magnification. The Shapiro-Wilk test was used to determine that the data were normally distributed; the data are presented using mean and standard deviation. Group comparisons were made with the independent t test (α=.05).

RESULTS

The passive and marginal fit of the conventional bars was better than that of the prefabricated bars. The mean ±standard deviation values for passive fit were 75.2 ±13.7 μm for conventional bars and 94.7 ±16.0 μm for prefabricated bars (P<.001). A statistically significant difference (P<.001) was also found between the marginal fit of the conventional bars 18.7 ±6.1 μm and the prefabricated bars 56.3 ±13.0 μm.

CONCLUSIONS

Conventional CAD-CAM milled titanium bars had a better passive and marginal fit than prefabricated CAD-CAM milled titanium bars; however, both had clinically acceptable passive fit ranging from 75.2 to 94.7 μm and definitive marginal fit ranging from 18.7 to 56.3 μm.

Comparison of Static and Dynamic Navigation in Root End Resection Performed by Experienced and Inexperienced Operators: An In Vitro Study

INTRODUCTION

This study aimed to compare the effects of static navigation (SN), a dynamic navigation system (DNS), and the freehand (FH) technique in root end resection and the differences between these effects according to the level of experience of the operator.

METHODS

Maxillary models reconstructed with Mimics software (Materialise, Leuven, Belgium) were 3-dimensionally printed and divided according to the experimental technique (FH, SN, or DNS) and the operator (experienced or inexperienced). SN was designed using 3-matic Medical software (Materialise) and printed, and a surgical approach plan for DNS was established and performed using DCARER (Suzhou, China) software. The accuracy, efficiency, and safety of the resections were assayed.

RESULTS

The length, angle, volume, and depth deviations of the root end resections were significantly lower in the SN and DNS group compared with the FH group. SN significantly improved the efficiency of both operators, whereas DNS only improved the efficiency of the inexperienced operator. No difference between the SN and DNS groups was found, except for the time required for the surgery. No mishaps occurred during surgery in the SN or DNS group. The number of mishaps with the FH technique when used by the inexperienced operator was significantly higher than that registered for the rest of the groups. No interaction effect between technique and operator experience level was detected.

CONCLUSIONS

Regardless of operator experience, both SN and DNS could improve the accuracy and safety of root end resection. SN significantly improved the chairside efficiency of both operators, whereas DNS was more helpful for the inexperienced operator.

The Accuracy of 3D Surgical Design and Simulation in Prefabricated Fibula Free Flaps for Jaw Reconstruction

The ideal jaw reconstruction involves the restoration and maintenance of jaw continuity, jaw relations, joint alignment, and facial contour, and, most importantly, dental occlusal reconstruction. One of the essential requirements of achieving a consistent functional outcome is to place the bony reconstruction in the correct three-dimensional position as it relates to the other jaw segments and dentition. A protocol of occlusion-driven reconstruction of prefabricated fibular free flaps that are customized to the patient with surgical design and simulation (SDS)-planned osseointegrated implant installation was developed by our institution. This innovation introduced significant flexibility and efficiency to jaw reconstructions, but functional and cosmetic outcomes were dependent on the accuracy of the final reconstructions when compared to the SDS plan. The purpose of this study was to examine the accuracy of the SDS-planned fibular flap prefabrication in a cohort of patients undergoing jaw reconstruction. All patients that had undergone primary jaw reconstruction with prefabricated fibular free flaps were reviewed. The primary outcome of this study was the accuracy of the postoperative implant positions as compared to the SDS plan. A total of 23 implants were included in the analysis. All flaps survived, there was no implant loss postoperatively, and all the patients underwent all stages of the reconstruction. SDS planning of fibular flap prefabrication resulted in better than 2 mm accuracy of osteointegrated implant placement in a cohort of patients undergoing jaw reconstruction. This accuracy could potentially result in improved functional and cosmetic outcomes.

Reducing errors in guided implant surgery to optimize treatment outcomes

Clinical considerations and treatment criteria in implant placement are constantly evolving. Prosthetically driven implant surgery has become the standard of care to improve short and long-term functional and esthetic outcomes. Therefore, implant position and angulation are planned according to the available bone, anatomical structures, and the requirements of the future prosthetic superstructure. In parallel with these developments, significant progress has been made in data imaging and different software technologies to allow the integration of data within a digital file format. Digitalization in implant surgery enables optimal planning of implant position, as well as the ability to transfer this planning to the surgical field-a process defined as "computer-supported implant planning and guided surgery." The aims of the present review are as follows: (a) to critically appraise the indications and potential "added value" of guided implant surgery, elaborating the main differences between dynamic and static guidance; and (b) to discuss the most important clinical considerations relevant for the different steps of the workflow that might influence the surgical outcome and to offer recommendations on how to avoid or reduce process errors in order to optimize treatment outcomes.

Guided Surgery with 3D Printed Device: A Case Report

Dental surgeons need in-depth knowledge of the bone tissue status and gingival morphology of atrophic maxillae. The aim of this study is to describe preoperative virtual planning of placement of 5 implants and to compare the plan with the actual surgical results. Three-dimensional (3D) planning of rehabilitation using software programs enables surgical guides to be specially designed for the implant site and manufactured using 3D printing. A patient with 5 teeth missing was selected for this study. The patient's maxillary region was scanned with cone-beam computed tomography (CBCT), and a cast model was produced. After virtual planning using ImplantViewer, 5 implants were placed using a printed surgical guide. Two weeks after the surgical procedure, the patient underwent another CBCT scan of the maxilla. Statistically significant differences were detected between the virtually planned positions and the actual positions of the implants, with a mean deviation of 0.36 mm in the cervical region and 0.7 mm in the apical region. The surgical technique used enables more accurate procedures compared with the conventional technique. Implants can be better positioned, with a high level of predictability, reducing both operating time and patient discomfort.

Computer-assisted surgery in medical and dental applications

INTRODUCTION

Computer-assisted surgery (CAS) is a broad surgical methodology that utilizes computer technology to both plan and execute surgical intervention. CAS is widespread in both medicine and dentistry as it allows for minimally invasive and precise surgical procedures. Key innovations in volumetric imaging, virtual surgical planning software, instrument tracking, and robotics have assisted in facilitating the transfer of surgical plans to precise execution of surgical procedures. CAS has long been used in certain medical specialties including neurosurgery, cardiology, orthopedic surgery, otolaryngology, and interventional radiology, and has since expanded to oral and maxillofacial application, particularly for computer-assisted implant surgery.

AREAS COVERED

This review provides an updated overview of the most current research for CAS in medicine and dentistry, with a focus on neurosurgery and dental implant surgery. The MEDLINE electronic database was searched and relevant original and review articles from 2005 to 2020 were included.

EXPERT OPINION

Recent literature suggests that CAS performs favorably in both neurosurgical and dental implant applications. Computer-guided surgical navigation is well entrenched as standard of care in neurosurgery. Whereas static computer-assisted implant surgery has become established in dentistry, dynamic computer-assisted navigation is newly poised to trend upward in dental implant surgery.

The accuracy of implant placement with computer-guided surgery in partially edentulous patients and possible influencing factors: A systematic review and meta-analysis

PURPOSE

To review the current clinical studies regarding the accuracy of implant computer-guided surgery in partially edentulous patients and investigate potential influencing factors.

STUDY SELECTION

Electronic searches on the PubMed and Cochrane Central Register of Controlled Trials databases, and subsequent manual searches were performed. Two reviewers selected the studies following our inclusion and exclusion criteria. Qualitative review and meta-analysis of the implant placement accuracy were performed to analyze potential influencing factors. Angular deviation, coronal deviation, apical deviation, and depth deviation were evaluated as the accuracy outcomes.

RESULTS

Eighteen studies were included in this systematic review, including six randomized controlled trials, nine prospective studies, and three retrospective clinical studies. A total of 1317 implants placed in 642 partially edentulous patients were reviewed. Eight studies were evaluated using meta-analysis. Fully guided surgery showed statistically higher accuracy in angular (P <0.001), coronal (P <0.001), and apical deviation (P <0.05) compared with pilot-drill guided surgery. A statistically significant difference (P <0.001) was also observed in coronal deviation between the bounded edentulous (BES) and distal extension spaces (DES). A significantly lower angular deviation (P <0.001) was found in implants placed using computer-aided design/computer-aided manufacturing (CAD/CAM) compared to the conventional surgical guides.

CONCLUSIONS

The edentulous space type, surgical guide manufacturing procedure, and guided surgery protocol can influence the accuracy of computer-guided surgery in partially edentulous patients. Higher accuracy was found when the implants were placed in BES, with CAD/CAM manufactured surgical guides, using a fully guided surgery protocol.

Accuracy of Guided Implant Surgery in the Edentulous Jaw Using Desktop 3D-Printed Mucosal Supported Guides

Purpose: The aim of this in vitro study is to evaluate the accuracy of implant position using mucosal supported surgical guides, produced by a desktop 3D printer. Methods: Ninety implants (Bone Level Roxolid, 4.1 mm × 10 mm, Straumann, Villerat, Switzerland) were placed in fifteen mandibular casts (Bonemodels, Castellón de la Plana, Spain). A mucosa-supported guide was designed and printed for each of the fifteen casts. After placement of the implants, the location was assessed by scanning the cast and scan bodies with an intra-oral scanner (Primescan^®, Dentsply Sirona, York, PA, USA). Two comparisons were performed: one with the mucosa as a reference, and one where only the implants were aligned. Angular, coronal and apical deviations were measured. Results: The mean implant angular deviation for tissue and implant alignment were 3.25° (SD 1.69°) and 2.39° (SD 1.42°) respectively, the coronal deviation 0.82 mm (SD 0.43 mm) and 0.45 mm (SD 0.31 mm) and the apical deviation 0.99 mm (SD 0.45 mm) and 0.71 mm (SD 0.43 mm). All three variables were significantly different between the tissue and implant alignment (p < 0.001). Conclusion: Based on the results of this study, we conclude that guided implant surgery using desktop 3D printed mucosa-supported guides has a clinically acceptable level of accuracy. The resilience of the mucosa has a negative effect on the guide stability and increases the deviation in implant position.

The Influence of Surgical Experience and Bone Density on the Accuracy of Static Computer-Assisted Implant Surgery in Edentulous Jaws Using a Mucosa-Supported Surgical Template with a Half-Guided Implant Placement Protocol-A Randomized Clinical Study

The aim of our randomized clinical study was to analyze the influence of surgical experience and bone density on the accuracy of static computer-assisted implant surgery (CAIS) in edentulous jaws using a mucosa-supported surgical template with a half-guided implant placement protocol. Altogether, 40 dental implants were placed in the edentulous jaws of 13 patients (novice surgeons: 18 implants, 6 patients (4 male), age 71 ± 10.1 years; experienced surgeons: 22 implants, 7 patients (4 male), age 69.2 ± 4.55 years). Angular deviation, coronal and apical global deviation and grey level measurements were calculated for all implants by a blinded investigator using coDiagnostiX software. 3DSlicer software was applied to calculate the bone volume fraction (BV/TV) for each site of implant placement. There were no statistically significant differences between the two study groups in either of the primary outcome variables. There was a statistically significant negative correlation between angular deviation and both grey level measurements (R-value: −0.331, p < 0.05) and BV/TV (R-value: −0.377, p < 0.05). The results of the study suggest that surgical experience did not influence the accuracy of implant placement. The higher the bone density at the sites of implant placement, the higher the accuracy of static CAIS.

Influence of bone condition on implant placement accuracy with computer-guided surgery

BACKGROUND

The impact of the jaw bone condition, such as bone quantity and quality in the implant placement site, affecting the accuracy of implant placement with computer-guided surgery (CGS) remains unclear. Therefore, this study aimed to evaluate the influence of bone condition, i.e., bone density, bone width, and cortical bone thickness at the crestal bone on the accuracy of implant placement with CGS.

METHODS

A total of 47 tissue-level implants from 25 patients placed in the posterior mandibular area were studied. Implant placement position was planned on the simulation software, Simplant® Pro 16, by superimposing preoperative computed tomography images with stereolithography data of diagnostic wax-up on the dental cast. Implant placement surgery was performed using the surgical guide plate to reflect the planned implant position. The post-surgical dental cast was scanned to determine the position of the placed implant. Linear and vertical deviations between planned and placed implants were calculated. Deviations at both platform and apical of the implant were measured in the bucco-lingual and mesio-distal directions. Intra- and inter-observer variabilities were calculated to ensure measurement reliability. Multiple linear regression analysis was employed to investigate the effect of the bone condition, such as density, width, and cortical bone thickness at the implant site area, on the accuracy of implant placement (α = 0.05).

RESULT

Intra- and inter-observer variabilities of these measurements showed excellent agreement (intra class correlation coefficient ± 0.90). Bone condition significantly influenced the accuracy of implant placement using CGS (p < 0.05). Both bone density and width were found to be significant predictors.

CONCLUSIONS

Low bone density and/or narrow bucco-lingual width near the alveolar bone crest in the implant placement site might be a risk factor influencing the accuracy of implant placement with CGS.

Early Loading of Mandibular Molar Single Implants: 1 Year Results of a Randomized Controlled Clinical Trial

The purpose of this study was to compare the implant survival, peri-implant marginal bone level, and peri-implant soft tissue of three different types of implants. This was performed with an early loading protocol, using a complete digital workflow, for one year of follow-up. Twenty-four patients with a single missing tooth in the mandibular posterior region were randomly assigned to the control group (SLActive Bone level implant; Institut Straumann AG, Basel, Switzerland), experiment group 1 (CMI IS-III Active implant; Neobiotech Co., Seoul, Korea), and experiment group 2 (CMI IS-III HActive implant; Neobiotech Co., Seoul, Korea). For each patient, a single implant was installed using the surgical template, and all prostheses were fabricated using a computer-aided design/computer-aided manufacturing system on a 3-dimensional model. A provisional prosthesis was implanted at 4 weeks, and a definitive monolithic zirconia prosthesis was substituted 12 weeks following the implant placement. The implant stability quotient (ISQ) and peri-implant soft tissue parameters were measured, and periapical radiographs were taken at 1, 3, 4, 8, 12, 24, 36, and 48 weeks after implant placements. Seven implants in the control group, nine implants in the experiment 1 group, and eight implants in the experiment 2 group were analyzed. There were no significant differences among the three groups in terms of insertion torque, ISQ values between surgery and 8 weeks of follow-up, marginal bone loss at 48 weeks of follow-up, and peri-implant soft tissue parameters (P > 0.05). Statistically significant differences in ISQ values were observed between the control and experiment 1 groups, and the control and experiment 2 groups at the 12 to 48 weeks' follow-ups. Within the limits of this prospective study, an early loading protocol can be applied as a predictable treatment modality in posterior mandibular single missing restorations, achieving proper primary stability.

Evaluation of the accuracy of implant placement by using fully guided versus partially guided tissue-supported surgical guides with cylindrical versus C-shaped guiding holes: A split-mouth clinical study

STATEMENT OF PROBLEM

The accuracy of partially guided implant placement protocols in comparison with fully guided protocols is still unclear. C-shaped guide holes have become popular; however, their effect on drilling and implant position accuracy has not been thoroughly investigated.

PURPOSE

The purpose of this split-mouth clinical study was to evaluate the accuracy of implant placement by using fully guided versus partially guided surgical guides with cylindrical versus C-shaped guiding holes.

MATERIAL AND METHODS

Adopting 80% power of the study in calculating sample size, a total of 48 implants were placed in the mandibular interforaminal area of 12 edentulous participants, who were randomly divided into 2 groups: a fully guided group, comprising 24 implants placed on 1 side by using a fully guided protocol and a partially guided group, comprising 24 implants placed on the other side in a partially guided protocol. Each group was further subdivided into 2 subgroups: cylindrical, including 12 implants placed through cylindrical guide holes, and C-shaped (12 implants) placed through C-shaped guiding holes. Postoperative cone beam computed tomography scans were made, and based on image fusion, the total deviations between the virtually preplanned and actual implant positions were determined and compared between both groups and subgroups. The linear horizontal deviation of the implant hexagon and apex, together with apical depth deviation and angular deviations between the position of the actually placed and virtually planned implants, were analyzed in 3 dimensions. The Kolmogorov-Smirnov test of normality was used. Comparisons were carried out by using the Kruskal-Wallis test. Post hoc pair-wise comparisons when the Kruskal-Wallis test was significant were carried out by using the Dunn-Sidak test (α=.05).

RESULTS

No statistically significant differences were found in coronal linear deviation (P>.05), apical linear deviation (P>.05), apical depth deviation (P=.086), or angular deviation (P=.247), between the fully guided protocol and the partially guided protocol.

CONCLUSIONS

The accuracy of partially guided implant placement was clinically comparable with that of fully guided placement whether the guiding holes were cylindrical or C-shaped.

Advantages and limitations of implant surgery with CAD/CAM surgical guides: A literature review

Background

The purpose of this study is to review the available literature associated with implant surgery using computer-aided design/computer-aided manufacturing (CAD/CAM) surgical guides and discuss the advantages and disadvantages of this advanced technique.

Material and Methods

An electronic literature search was conducted in the PubMed database for the relevant information on implant placement with CAD/CAM surgical guides. This review was constructed following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Articles were limited to those published within the past 10 years and in the English language. Only clinical studies were included. Inclusion criteria were: studies including 10 implants or more and studies presenting angular deviations in degrees and linear deviations in millimeter. Observational studies, reviews, animal studies, in vitro studies, case reports, simulation studies were excluded. Nine articles were included for qualitative synthesis.

Results

The initial search detected 61 articles, and after screening abstracts, a total of 15 articles were selected for full-text review. After the full-text analysis of the 15 articles, six articles were excluded as they did not meet inclusion criteria for study design, study population, and implant placement with data presentation for angular and linear deviations. Ultimately, nine articles providing angular and linear deviations between planned and actual placed implants were used in this review. Common problems that may be encountered by clinicians were listed, and recommendations were made on how to avoid those problems.

Conclusions

It has been suggested that although unrealistic expectations are often associated with implant placement with CAD/CAM surgical guides, there is no impeccable accuracy in the clinic. This review demonstrated that the practitioners should be aware of the angular and linear deviations up to 5 ° and 2.3 mm. Therefore, inexperienced dentists should obtain adequate training and be familiar with the basic steps with CAD/CAM surgical guides to avoid complications.

Key words:CAD/CAM, CBCT, implant, stereolithography, surgical guide.

[Research advances in the use of digital surgical guides in implantology]

Dental implants have become the main choice for patients to fill in their missing teeth. A precise placement is the basis for a functional and aesthetic restoration. A digital surgical guide is a carrier that transfers the preoperative plan of dental implants to the actual surgery. This paper provides some references that can help clinicians improve the accuracy of implant surgery by stating the development, classification, advantages and disadvantages, and factors that affect the accuracy of digital guides.

Guided implant surgery risks and their prevention

Ideal implant placement may reduce surgical complications, such as nerve injury and lingual cortical plate perforation, and minimize the likelihood of functional and prosthetic compromises. Guided implant surgery (GIS) has been used as the means to achieve ideal implant placement. GIS refers to the process of digital planning, custom-guide fabrication, and implant placement using the custom guide and an implant system-specific guided surgery kit. GIS includes numerous additional steps beyond the initial prosthetic diagnosis, treatment planning, and fabrication of surgical guide. Substantial errors can occur at each of these individual steps and can accumulate, significantly impacting the final accuracy of the process with potentially disastrous deviations from proper implant placement. Pertinent overall strategies to reduce or eliminate these risks can be summarized as follows: complete understanding of the possible risks is fundamental; knowledge of the systems and tools used is essential; consistent verification of both diagnostic and surgical procedures after each step is crucial; proper training and surgical experience are critical. This review article summarizes information on the accuracy and efficacy of GIS, provides insight on the potential risks and problems associated with each procedural step, and offers clinically relevant recommendations to minimize or eliminate these risks.

Accuracy of computer-guided surgery for dental implant placement in fully edentulous patients: A systematic review

Assess clinical studies regarding accuracy between virtual planning of computer-guided surgery and actual outcomes of dental implant placements in total edentulous alveolar ridges. A PubMed search was performed to identify only clinical studies published between 2011 and 2016, searching the following combinations of keywords: "Accuracy AND Computer-Assisted Surgery AND Dental Implants." Study designs were identified using the terms: Case Reports, Clinical study, Randomized Controlled Trial, Systematic Reviews, Meta-Analysis, humans. Level of agreement between the authors in the study selection process was substantial (k = 0.767), and the study eligibility was considered excellent (k = 0.863). Seven articles were included in this review. They describe the use of bone and muco-supported guides, demonstrating angular deviations cervically and apically ranging from (minimum and maximum means), respectively, 1.85-8.4 (°), 0.17-2.17 (mm), and 0.77-2.86 (mm). Angular deviations obtained most inaccuracy in maxila. For cervical and apical deviations, accuracy was preponderantly lower in maxilla. Despite the similar deviations measurement approaches described, clinical relevance of this study may be useful to warn the surgeon that safety margins in clinical situations.

Cone beam computed tomography in implant dentistry: recommendations for clinical use

BACKGROUND

In implant dentistry, three-dimensional (3D) imaging can be realised by dental cone beam computed tomography (CBCT), offering volumetric data on jaw bones and teeth with relatively low radiation doses and costs. The latter may explain why the market has been steadily growing since the first dental CBCT system appeared two decades ago. More than 85 different CBCT devices are currently available and this exponential growth has created a gap between scientific evidence and existing CBCT machines. Indeed, research for one CBCT machine cannot be automatically applied to other systems.

METHODS

Supported by a narrative review, recommendations for justified and optimized CBCT imaging in oral implant dentistry are provided.

RESULTS

The huge range in dose and diagnostic image quality requires further optimization and justification prior to clinical use. Yet, indications in implant dentistry may go beyond diagnostics. In fact, the inherent 3D datasets may further allow surgical planning and transfer to surgery via 3D printing or navigation. Nonetheless, effective radiation doses of distinct dental CBCT machines and protocols may largely vary with equivalent doses ranging between 2 to 200 panoramic radiographs, even for similar indications. Likewise, such variation is also noticed for diagnostic image quality, which reveals a massive variability amongst CBCT technologies and exposure protocols. For anatomical model making, the so-called segmentation accuracy may reach up to 200 μm, but considering wide variations in machine performance, larger inaccuracies may apply. This also holds true for linear measures, with accuracies of 200 μm being feasible, while sometimes fivefold inaccuracy levels may be reached. Diagnostic image quality may also be dramatically hampered by patient factors, such as motion and metal artefacts. Apart from radiodiagnostic possibilities, CBCT may offer a huge therapeutic potential, related to surgical guides and further prosthetic rehabilitation. Those additional opportunities may surely clarify part of the success of using CBCT for presurgical implant planning and its transfer to surgery and prosthetic solutions.

CONCLUSIONS

Hence, dental CBCT could be justified for presurgical diagnosis, preoperative planning and peroperative transfer for oral implant rehabilitation, whilst striving for optimisation of CBCT based machine-dependent, patient-specific and indication-oriented variables.

The patient general satisfaction of mandibular single-implant overdentures and conventional complete dentures: Study protocol for a randomized crossover trial

BACKGROUND

Mandibular overdentures retained by a single implant placed in the midline of edentulous mandible have been reported to be more comfortable and function better than complete dentures. Although single-implant overdentures are still more costly than conventional complete dentures, there are a few studies which investigated whether mandibular single-implant overdentures are superior to complete dentures when patient general satisfaction is compared. The aim of this study is to assess patient general satisfaction with mandibular single-implant overdentures and complete dentures.

METHODS

This study is a randomized crossover trial to compare mandibular single-implant overdentures and complete dentures in edentulous individuals. Participant recruitment is ongoing at the time of this submission. Twenty-two participants will be recruited. New mandibular complete dentures will be fabricated. A single implant will be placed in the midline of the edentulous mandible. The mucosal surface of the complete denture around the implant will be relieved for 3 months. The participants will then be randomly allocated into 2 groups according to the order of the interventions; group 1 will receive single-implant overdentures first and will wear them for 2 months, followed by complete dentures for 2 months. Group 2 will receive the same treatments in a reverse order. After experiencing the 2 interventions, the participants will choose one of the mandibular prostheses, and yearly follow-up visits are planned for 5 years. The primary outcome of this trial is patient ratings of general satisfaction on 100 mm visual analog scales. Assessments of the prostheses and oral health-related quality of life will also be recorded as patient-reported outcomes. The secondary outcomes are cost and time for treatment. Masticatory efficiency and cognitive capacity will also be recorded. Furthermore, qualitative research will be performed to investigate the factors associated with success of these mandibular denture types. Clinical outcomes, such as implant survival rate, marginal bone loss, and prosthodontic complications, will also be recorded.

DISCUSSION

The results of this randomized crossover trial will clarify whether mandibular single implants and overdentures for edentulous individuals provide better patient general satisfaction when compared to conventional complete dentures.

TRIAL REGISTRATION

This clinical trial was registered at the University Hospital Medical Information Network (UMIN) Center (UMIN000017883).

Accuracy of Guided Surgery via Stereolithographic Mucosa-Supported Surgical Guide in Implant Surgery for Edentulous Patient: a Systematic Review

Objectives

The purpose of the present study is to systematically review the accuracy of implant placement with mucosa-supported stereolithographic surgical guide and to find out what factors can influence the accuracy.

Material and Methods

An electronic literature search was performed through the MEDLINE (PubMed) and EMBASE databases. The articles are including human studies published in English from October 2008 to October, 2017. From the examination of selected articles, deviations between virtual planning and actual implant placement were analysed regarding the global apical, global coronal, and angulation position.

Results

A total of 119 articles were reviewed, and 6 of the most relevant articles that are suitable to the criteria were selected. The present data included 572 implants and 93 patients. The result in the present systematic review shows that mean apical global deviation ranges from 0.67 (SD 0.34) mm to 2.19 (SD 0.83) mm, mean coronal global deviation ranges from 0.6 (SD 0.25) mm to 1.68 (SD 0.25) mm and mean angular deviation - from 2.6° (SD 1.61°) to 4.67° (SD 2.68°).

Conclusions

It's clearly shown from most of the examined studies that the mucosa-supported stereolithographic surgical guide, showed not exceeding in apically 2.19 mm, in coronally 1.68 mm and in angular deviation 4.67°. Surgeons should be aware of the possible linear and angular deviations of the system. Accuracy can be influenced by bone density, mucosal thickness, surgical techniques, type of jaw, smoking habits and implant length. Further studies should be performed in order to find out which jaw can have better accuracy and how the experience can influence the accuracy.

Vital Life-Threatening Hematoma after Implant Insertion in the Anterior Mandible: A Case Report and Review of the Literature

Dental implant insertion is considered a safe and reliable surgical procedure and severe complications are seldom reported. However, we present a case of a 52-year-old patient who attended our Department of Oral and Maxillofacial Surgery, Johannes Gutenberg University Medical Center, Mainz, with spreading hematoma in the floor of the mouth and acute airway obstruction after insertion of a dental implant in the anterior mandible. The hematoma was removed and submentally drained by a silicon drainage. However, the progressive swelling of the tongue and the floor of the mouth necessitated a temporary tracheotomy for three days. The review of the literature summarizes guidelines for prevention and management of this life-threatening complication.

Immediate loading of two freestanding implants placed by computer-guided flapless surgery supporting a mandibular overdenture with magnetic attachments

PURPOSE

The present article describes a novel clinical procedure for mandibular overdentures supported by two freestanding implants loaded immediately after placement via computer-guided flapless surgery.

METHODS

A conventional acrylic complete denture was fabricated, and CT scans obtained using the denture as a radiographic guide. Preoperative computer-assisted planning was performed using commercially available software, permitting simulation of implant placement at optimal positions. Using simulation data, a surgical guide was manufactured and used during surgery. The surgical guide was placed and local anesthesia injected for drilling of anchor pins to stabilize the surgical guide. The drilling protocol for each osteotomy site achieved an insertion torque greater than 35 Ncm. Immediately after implant placement, a keeper of the magnetic attachment was connected to each implant, and the magnetic assembly incorporated into the denture. The mucosal surface of the denture around the magnet was relieved to avoid excessive tissue pressure. The patients were instructed to wear the denture in place continually for the following 7 days. After six months of healing and follow-up, a final denture with a metal framework may be fabricated if necessary.

CONCLUSION

A novel treatment protocol for immediately loaded implant-supported mandibular overdentures is described in detail. The protocol ensures secure precise and safe implant placement, successful osseointegration, and immediate improvement of oral health-related quality of life for patients with unstable complete dentures.

Telescopic Overdenture and Implant Supported Fixed Partial Denture: A Pragmatic Treatment Approach

This case report presents a patient who had been rehabilitated with a telescopic overdenture and implant supported fixed partial denture (ISFPD). The treatment process was as follows: (1) fabricating telescopic crowns and overdenture prosthesis for the lower jaw and a temporary complete denture for the upper jaw, (2) using the temporary denture as diagnostic and surgical guide to optimize dental implant placement, and (3) fabricating ISFPD for the upper jaw. Using the patient's existing or temporary denture not only serves as an alternative surgical guide to calibrate the dental implant locations but also helps to finish the restoration at desired dimension, size, and anatomic form.