A survey for the use of torque-limiting devices among dental clinicians in Europe.

PURPOSE: To assess how well torque-limiting devices (TLDs) are known and used by European dentists, and their adherence to screw tightening protocols and screw loosening occurrence through a survey, including the correlation between the dental specialty-of-interest and the recognition, the tightening protocol used, and between the calibration and the occurrence of screw loosening. MATERIALS AND METHODS: A 10-question survey was distributed to dentists to collect data on their specialty-of-interest, TLD usage, knowledge on TLDs, calibration, the term "preload," tightening speed, tightening protocols used, and occurrence of screw loosening. Pearson test was used for correlation analysis between the specialty-of-interest and the recognition-based questions, the tightening protocol used, and between the calibration and the frequency of screw loosening. RESULTS: Of 422 respondents, 24% calibrated their TLDs, 27% knew the term "preload," 76% selected the correct location to read on TLDs, and 6% was aware of the effect of tightening speed. The correlation between the specialty-of-interest and the recognition-based questions was nonsignificant (p < .05) but was significant for used tightening protocol (p < .001). The correlation between the calibration and the occurrence of screw loosening was nonsignificant (p = 0.16). Tightening protocols' effect on screw loosening was similar, which was mostly observed less than once a year (p < .001). CONCLUSIONS: A lack in dentists' knowledge was found on calibration, the term preload, and the effect of tightening speed, which were not impacted by the dentists' specialty-of-interest, which affected the preferred tightening protocol. The tightening protocol and calibration did not impact the occurrence of screw loosening, which was mostly observed less than once a year.

Accuracy of dynamic computer-assisted implant surgery in fully edentulous patients: An in vitro study.

OBJECTIVES: To compare miniscrew versus bone tracing registration methods on dental implant placement accuracy and time efficiency in edentulous jaws using a dynamic computer-assisted implant surgery (d-CAIS) system. METHODS: Twelve fully edentulous maxillary models were allocated into two groups: miniscrew tracing (MST) group, where registration was performed by tracing four miniscrews; and bone tracing (BT) group, where registration was conducted by tracing maxillary bone fiducial landmarks. Six implants were placed on each model using the X-Guide® d-CAIS system. Pre- and postoperative cone-beam computed tomography (CBCT) scans were superimposed to evaluate implant placement accuracy. The time required for registration and the overall surgery time were also recorded. RESULTS: Thirty-six implants were placed in each group. The MST group showed significantly lower mean angulation deviations (mean difference (MD): -3.33°; 95% confidence interval (CI): -6.56 to -0.09); p = 0.044), 3D platform deviations (MD: -1.01 mm; 95%CI: -1.74 to -0.29; p = 0.006), 2D platform deviations (MD: -0.97 mm; 95%CI: -1.71 to -0.23; p = 0.010), and 3D apex deviations (MD: -1.18 mm; 95%CI: -1.92 to -0.44; p = 0.002) versus the BT group. The overall surgery time was similar for both groups (MD: 6.10 min.; 95%CI: -0.31 to 12.51; p = 0.06), though bone tracing required significantly more time compared with miniscrew registration (MD: 4.79 min.; 95%CI: 2.96 to 6.62; p < 0.05). CONCLUSIONS: Registration with MST increases the accuracy of implant placement with a d-CAIS system in edentulous jaws compared with the BT method, and slightly reduces the overall surgery time. CLINICAL SIGNIFICANCE: Miniscrew tracing registration improves implant placement accuracy in comparison with bone tracing registration.

The mechanical complications and behavior of angulated dental implant abutment systems versus conventional abutments, a narrative review.

Background: Angulated screw channel (ASC) abutment allows off-axis dental implants to be used in dental restorations without the need for cementation. As this is a relatively new system, research on its clinical performance is limited. Objectives: To summarize the available in-vitro and in-vivo studies on the mechanical and technical issues associated with the ASC system and compare its clinical performance with that of conventional implant-supported abutments. Methods: A comprehensive literature search in PubMed, Web of Science, and ScienceDirect databases was performed, focusing on articles about angulated (angled) screw channel (ASC) systems published in English between January 2015 and November 2023. Only in-vitro and in-vivo studies were included. Results: After analyzing the recorded articles, 26 studies (11 in vivo and 15 in vitro) were included in the final discussion and review. Conclusion: Although the ASC system is still relatively new, and is presently outperformed by conventional abutment systems in terms of technical and mechanical properties, in short- and medium-term in-vivo studies, it was shown reliable for retaining single or multiple-unit implant restorations in both posterior and anterior zones. Still, further long-term clinical research is needed to fully elucidate the risk factors associated with ASC failures.

Impact of Fixed Partial Dentures on Oral Microbial Flora and Gingival Health: An In Vitro Assessment of Salivary Microbial Profiles.

Introduction The oral cavity hosts diverse microorganisms affected by factors like pH, temperature, and oxygen levels, influencing disease potential. Dentists manage oral diseases and improve aesthetics using durable restorations. Understanding periodontal response to crowns and fixed partial dentures (FPDs) is essential for effective treatment. This study aims to assess the impact of FPDs on periodontal health by comparing microbial colonies in individuals with and without FPDs. The hypothesis is that there will be no difference in microbial flora and gingival health between the two groups. Materials and methods This in vitro study utilized 40 salivary samples divided into two groups: 20 from patients with FPDs/crowns (Group 1) and 20 from patients without (Group 2). Unstimulated saliva was collected, diluted, and cultured on nutrient agar and Sabouraud Dextrose Agar to quantify anaerobic bacteria and Candida colonies. Colony counts were scored from 0 to IV based on colony-forming unit (CFU), and microscopic examination identified the types of microbes present. Data were analyzed using an unpaired t-test with IBM SPSS Statistics for Windows, Version 26 (Released 2019; IBM Corp., Armonk, New York, United States), with significance set at p < 0.05. Results The independent t-test analysis showed significantly higher mean CFUs of anaerobic microbes in Group 1 (experimental) compared to Group 2 (control) (p = 0.000). However, mean CFUs of Candida did not significantly differ between groups (p = 0.194). Microscopic examination identified Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans, Staphylococcus aureus, and Streptococcus mutans in the experimental group, whereas the control group contained only Staphylococcus aureus and Streptococcus mutans. Conclusion Individuals with FPDs exhibit higher concentrations of anaerobic microbes and specific bacteria, suggesting an increased risk of gingival inflammation and emphasizing the importance of maintaining good oral hygiene.

Repair strength of 3D-printed denture base resins: Effect of surface treatment and repair material type.

PURPOSE: The aim of the study was to investigate the effect of surface treatment and repair materials on the flexural strength of repaired 3D-printed denture base resins after thermal aging. MATERIALS AND METHODS: Bar-shape specimens (64 × 10 × 3.3 mm) were designed as intact (control) specimens while repair specimens were printed in sections with 2.5 mm space for repair material. Printing was performed with either ASIGA or NextDent denture base material. In each material, one group received no surface treatment, while other repair groups were subjected to one of three surface treatments: (1) monomer application, (2) aluminium oxide particles-abrasion, or (3) both methods (aluminum oxide particles-abrasion and monomer application). Pairs were fixed in a customized mold then repaired with either autopolymerizing acrylic resin or flowable composite (n = 9). Repaired specimens were incubated for 48 h at 37°C in distilled water and then subjected to thermal cycling (5000 cycles). A 3-point bending test was used to evaluate the flexural strength using a universal testing machine, and mode of failure determined followed by fractured surface analysis using scanning electron microscope. Data were analyzed using ANOVA and post hoc Tukey test (α = 0.05). RESULTS: Both resin materials showed a significant decrease in the flexural strength of repaired specimens when compared to control ones (p < 0.001). Groups with no surface treatment had significantly lower flexural strength than those with surface treatment (p < 0.001). Groups treated with monomer application, and with aluminum oxide particles abrasion plus monomer application had similar flexural strength values (p > 0.05), which were higher than those treated with aluminum oxide particles abrasion alone (p < 0.001). Specimens repaired with composite resin showed higher flexural strength than those repaired with auto-polymerized resin (p < 0.05) however, specimens treated with aluminum oxide particles abrasion alone had similar values for both repair materials (p = 0.95). Adhesive failure was dominant in all repaired groups with auto-polymerized while cohesive and mixed were dominant with composite repair groups. CONCLUSION: Surface treatment improved the repair strength of 3D-printed denture base resins. Using composite resin for repair shows better strength with dominant cohesive and mixed failure suggesting that surface treatment and composite repair are suitable procedures for 3D-printed denture base repair.

Application of artificial intelligence in dental crown prosthesis: a scoping review.

BACKGROUND: In recent years, artificial intelligence (AI) has made remarkable advancements and achieved significant accomplishments across the entire field of dentistry. Notably, efforts to apply AI in prosthodontics are continually progressing. This scoping review aims to present the applications and performance of AI in dental crown prostheses and related topics. METHODS: We conducted a literature search of PubMed, Scopus, Web of Science, Google Scholar, and IEEE Xplore databases from January 2010 to January 2024. The included articles addressed the application of AI in various aspects of dental crown treatment, including fabrication, assessment, and prognosis. RESULTS: The initial electronic literature search yielded 393 records, which were reduced to 315 after eliminating duplicate references. The application of inclusion criteria led to analysis of 12 eligible publications in the qualitative review. The AI-based applications included in this review were related to detection of dental crown finish line, evaluation of AI-based color matching, evaluation of crown preparation, evaluation of dental crown designed by AI, identification of a dental crown in an intraoral photo, and prediction of debonding probability. CONCLUSIONS: AI has the potential to increase efficiency in processes such as fabricating and evaluating dental crowns, with a high level of accuracy reported in most of the analyzed studies. However, a significant number of studies focused on designing crowns using AI-based software, and these studies had a small number of patients and did not always present their algorithms. Standardized protocols for reporting and evaluating AI studies are needed to increase the evidence and effectiveness.

Clinical and radiographic evaluation of implant-supported single-unit crowns with cantilever extensions: A systematic review and meta-analysis.

PURPOSE: The purpose of this systematic review and meta-analysis was to analyze the clinical and radiographic outcomes of patients rehabilitated using a single implant supporting a crown with a cantilever extension or two implants supporting two single crowns. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 guidelines, a systematic review of relevant literature published from 2000 was conducted in the Cochrane Library, Scopus, and MEDLINE databases. Moreover, a manual search was performed. A meta-analysis of the resulting data was carried out. Peri-implant marginal bone level, probing pocket depth, prevalence of technical and mechanical complications, implant survival rate, and prosthesis survival rate were assessed. RESULTS: The meta-analysis showed a non-statistically significant change in the peri-implant marginal bone level and probing pocket depth in the cantilever group and revealed a non-significant prevalence of technical complications, showing a 27% rate in the cantilever group. The analysis of the prosthesis survival rate in the cantilever group showed a mean survival rate of 99% while the comparison of the implant survival between the two groups revealed an odds ratio of 0.50. CONCLUSIONS: The use of a single implant supporting a crown with a cantilever extension does not result in lower implant survival rate if compared with two implants supporting two single crowns. Moreover, a high prosthesis survival rate was observed in the cantilever group even if the high prevalence of complications should be carefully considered by the clinician.

Comparison of Aesthetic, Mechanical Outcome, and Bone Loss in Angulated Screw Channels (ASCs) and Cement-Retained Implant-Supported Prosthesis: A Case-Control Study.

Angulated-screw channels (ASCs) allow the clinician to employ screw-retained restorations in almost all cases, as the access hole can be moved away from the vestibular portion of the crown, where it would jeopardize the final esthetic result. The objective of this study was to compare screw-retained restorations employing ASCs with restorations cemented on angled abutments. In this study, 30 subjects, equally divided into two groups: group 1 (cemented restorations on angulated abutments) and group 2 (screw-retained restorations adopting ASCs), were treated and retrospectively compared after 2 years using the pink esthetic score (PES) and the white esthetic score (WES). All restorations were in use at the last follow-up, with a survival rate of 100%. Three mechanical complications were observed (2 chippings and 1 crown came loose), with a success rate of 93% in group 1 and 87% in group 2 (p > 0.05). No statistically significant differences were reported regarding the esthetic outcome; the marginal bone loss (MBL) showed better results for the screw-retained restorations, both at the distal aspect (group 1 = 0.98 mm ± 0.16; group 2 = 0.45 mm ± 0.06; p = 0.006) and at the mesial aspect (group 1 = 1.04 ± 0.27; group 2 = 0.45 ± 0.005; p < 0.001). From an esthetical perspective, screw-retained restorations with ASCs and cemented restorations on angulated abutments are both effective means of restoring implants; both have excellent esthetic outcomes, but screw-retained restorations have reduced bone loss when compared to cemented ones but are more prone to mechanical complications. Still, our results must be cautiously observed given the reduced dimension of our sample. Larger studies are needed to confirm our findings.

Classification system for maxillary fixed dental prostheses.

PURPOSE: To present an addendum to existing fixed dental prostheses (FDPs) classification system for maxillary prostheses. The new classification identifies the relationships between FP-1 (fixed prostheses) designs and newly developed clinical interdental gingival contours. MATERIALS AND METHODS: Clinical and laboratory descriptions of the various types of full-arch fixed prostheses are described with photographic illustrations. Benefits and limitations of the various prosthetic designs are explained. Surgical differences in the amount of alveolectomy are illustrated. One clinical case is demonstrated. RESULTS: A new classification system for maxillary implant fixed complete dentures is presented. The new system will serve as an improved communication aid for clinicians, patients, and laboratory technicians. Treatment of patients with edentulous maxillae and/or terminal dentitions and implant fixed complete dentures include several options relative to design and materials. Restorative space can have a major impact on prosthesis design and longevity. Early on in dental implant therapy, prostheses were generally made with cast metal frameworks, denture bases and denture teeth. Prosthetic complications were widely reported. With increased clinical experience and improved materials, computer-aided design and computer-aided manufacturing (CAD-CAM) protocols were developed that allowed stronger prostheses to be constructed in reduced or small restorative volumes. FP-1 ceramic implant-supported fixed prostheses (CISFPs) are designed to replace only the dental hard tissues and to promote preservation and rehabilitation of gingival soft tissues. The physical properties and minimum thickness requirements in full arch prostheses are influenced by several factors including distances between implants and rigid connector sizes. CONCLUSION: FP-1 CISFPs may be the closest prostheses the profession can offer edentulous patients that mimic the look, feel, and function of missing dentitions. Aesthetic outcomes of FP-1 CISFPs are variable and depend on a multitude of factors. This article presented a classification system that builds on existing classification by identifying the level of papilla heights achieved with FP-1 CISFPs.

One-stage prosthodontically driven jaw reconstruction in patients with benign and malignant pathologies: A 7- to 11-year cohort study.

OBJECTIVES: One stage functional jaw reconstruction is defined as the resection and reconstruction of segmental defects in conjunction with the placement of dental implants in an ideal prosthetic position and loaded with a provisional restoration, during one surgical procedure. The aim of the study is to describe clinical outcomes of patients who underwent one stage functional jaw reconstruction. METHODS: Patients who underwent one-stage functional jaw reconstruction, from January 2013 to March 2016 were recalled in 2022 and 2023. Planning and execution for the reconstruction utilized either analogue or digital techniques. Outcome parameters recorded were treatment-related outcomes at patient level, implant-related outcomes and patient-reported outcome measures. RESULTS: Eighteen patients underwent one-stage jaw reconstruction with a total of 57 implants. Four patients had maxillary and 14 had mandibular reconstructions. Ten patients underwent postoperative radiotherapy. Ten patients were planned using analogue and eight by digital planning. Three patients had partial flap necrosis, three patients had plate fractures, implant loss was seen in one patient and four patients died during the period. A functional prosthesis was provided in 16 out of the 18 patients. CONCLUSION: One-stage functional jaw reconstruction is a predictable method for providing rehabilitation with successful outcomes at 7-11 years. However, caution should be exercised when the treatment modality is carried out in patients with malignant pathologies who have undergone radiotherapy.

Immediate full-arch fixed rehabilitation of a narrow mandible with newly conceived connection system implants: A case report.

Rehabilitating thin jaws without reconstructive surgery entails using narrow implants. The proposed treatment adopted an innovative implant system, allowing the mini-screws to be parallel and immediately loaded. A mandible, wearing an overdenture, was functionalized contextually to the residual dental extraction and the placement of six 2.4-mm thick one-piece implants. Low-profile intermediate abutments, the LEMs, able to rotate over the spherical heads of the fixtures, were connected after suturing, oriented, and blocked in a mutual parallel position. The copings, engaging with a tapered juncture of the LEMs, resulted in their alignment to be intraorally wedged together. The provisional superstructure enclosed the copings and was immediately connected to the implants, and the definitive prosthesis was delivered after three months. No clinical signs of peri-implantitis or radiographically evident bone loss were recorded after a two-year follow-up without any prosthetic complication. No cases have been published regarding mini-implants bearing fixed prosthesis rehabilitation.

Clinical Performance of Implant-Supported Prostheses in the Rehabilitation of Patients Previously Treated for Medication-Related Osteonecrosis of the Jaws (MRONJ): A Systematic Review.

There is a lack of consensus on managing resultant bone and soft tissue defects or on restoring oral function and aesthetics following medication-related osteonecrosis of the jaws (MRONJ) lesion healing. This clinical challenge presents a dilemma for practitioners. Removable prostheses pose a recurrence risk if poorly fitted and may inadequately restore function or aesthetics in cases of significant bone defect. Dental implant-supported prostheses could enhance function and quality of life, though their risks and indications are not well-defined. This systematic review examines the clinical outcomes and complications associated with implant-supported rehabilitations post-MRONJ surgery. This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement recommendations and it was pre-registered in the Prospective Register of Systematic Reviews (PROSPERO) (CRD42023492539).

Prediction of lifespan and assessing risk factors of large-sample implant prostheses: a multicenter study.

PURPOSE: This study aimed to analyze factors influencing the success and failure of implant prostheses and to estimate the lifespan of prostheses using standardized evaluation criteria. An online survey platform was utilized to efficiently gather large samples from multiple institutions. MATERIALS AND METHODS: During the one-year period, patients visiting 16 institutions were assessed using standardized evaluation criteria (KAP criteria). Data from these institutions were collected through an online platform, and various statistical analyses were conducted. Risk factors were assessed using both the Cox proportional hazard model and Cox regression analysis. Survival analysis was conducted using Kaplan-Meier analysis and nomogram, and lifespan prediction was performed using principal component analysis. RESULTS: The number of patients involved in this study was 485, with a total of 841 prostheses evaluated. The median survival was estimated to be 16 years with a 95% confidence interval. Factors found to be significantly associated with implant prosthesis failure, characterized by higher hazard ratios, included the 'type of clinic', 'type of antagonist', and 'plaque index'. The lifespan of implant prostheses that did not fail was estimated to exceed the projected lifespan by approximately 1.34 years. CONCLUSION: To ensure the success of implant prostheses, maintaining good oral hygiene is crucial. The estimated lifespan of implant prostheses is often underestimated by approximately 1.34 years. Furthermore, standardized form, online platform, and visualization tool, such as nomogram, can be effectively utilized in future follow-up studies.

Impact of Printing Orientation on the Accuracy of Additively Fabricated Denture Base Materials: A Systematic Review.

Printing orientation is one of the printing parameters that affect the properties of three-dimensional (3D)-printed resins. Different printing orientations and directions have been suggested; however, no clear and specific orientations are recommended in the literature in terms of the printing orientation effect on the accuracy and fit of 3D-printed removable dental prostheses. This review aimed to evaluate the effect of printing orientation on the fit and accuracy of 3D-printed removable dental prostheses. The PubMed, Scopus, and Web of Science databases were searched for published articles that investigated the effect of printing orientations on the accuracy and fit of the 3D-printed denture base. Full-length English published articles were searched between January 2010 and December 2023, which examined topics related to printing orientations, building angles, 3D printing, printing technology, accuracy, dimensional changes, internal fit, marginal integrity, marginal discrepancies, trueness, precision, and adaptation. Of the ten included studies, one investigated maxillary and mandibular denture bases, seven assessed maxillary denture bases, and two evaluated mandibular bases. Different printing orientations, ranging from 0° to 315°, were explored, with a higher prevalence of 0°, 45°, and 90°. The included studies utilized stereolithography and digital light processing printing technologies. High accuracy was observed at 45°, followed by 90. Additional struts and bars on the cameo surface increased the accuracy of the 3D-printed denture base. These results shows that printing orientation has a significant effect on the accuracy of 3D-printed resin, with 45° exhibiting the highest accuracy. In addition to the support structure, the density and position can impact the accuracy.

The Influence of Cement Thickness within the Cap on Stress Distribution for Dental Implants.

The purpose of this finite element analysis (FEA) was to evaluate the stress distribution within the prosthetic components and bone in relation to varying cement thicknesses (from 20 to 60 µm) utilized to attach a zirconia crown on a conometric cap. The study focused on two types of implants (Cyroth and TAC, AoN Implants, Grisignano di Zocco, Italy) featuring a Morse cone connection. Detailed three-dimensional (3D) models were developed to represent the bone structure (cortical and trabecular) and the prosthetic components, including the crown, cement, cap, abutment, and the implant. Both implants were placed 1.5 mm subcrestally and subjected to a 200 N load at a 45° inclination on the crown. The results indicated that an increase in cement thickness led to a reduction in von Mises stress on the cortical bone for both Cyroth and TAC implants, while the decrease in stress on the trabecular bone (apical zone) was relatively less pronounced. However, the TAC implant exhibited a higher stress field in the apical area compared to the Cyroth implant. In summary, this study investigated the influence of cement thickness on stress transmission across prosthetic components and peri-implant tissues through FEA analysis, emphasizing that the 60 µm cement layer demonstrated higher stress values approaching the material strength limit.

Comparative Evaluation of Digital and Conventional Workflows for the Fabrication of Multi-Unit Implant-Supported Fixed Restorations: An Empty Review.

Objectives: This study aimed to do a comprehensive systematic review on the comparison of digital and conventional workflows regarding prosthetic outcomes, accuracy of implant impressions, framework passivity and fit, and clinical fabrication of multi-unit implant-supported fixed restorations. Materials and Methods: The EMBASE, PubMed, Scopus, and Cochrane Library databases were searched for relevant articles published up until April 2020. Results: No in-vivo article was found to compare full digital and conventional workflows regarding the accuracy of implant impressions, passivity and fit of frameworks, and prosthetic outcomes. There was no study to investigate full digital and conventional workflows for clinical fabrication of multi-unit implant-supported fixed restorations. Conclusion: This empty review highlights the need for further research to compare full digital and conventional workflows for implant-supported restorations.

Material and abutment selection for CAD/CAM implant-supported fixed dental prostheses in partially edentulous patients - A narrative review.

Restorative material selection has become increasingly challenging due to the speed of new developments in the field of dental material science. The present narrative review gives an overview of the current indications for implant abutments and restoration materials for provisional and definitive implant-supported fixed dental prostheses in partially edentulous patients. For single implant restorations, titanium base abutments for crowns are suggested as an alternative to the conventional stock- and customized abutments made out of metal or zirconia. They combine the mechanical stability of a metallic connection with the esthetic potential of ceramics. For multiple-unit restorations, conical titanium bases especially designed for bridges are recommended, to compensate for deviating implant insertion axes and angulations. Even though titanium base abutments with different geometries and heights are available, certain clinical scenarios still benefit from customized titanium abutments. Indications for the definitive material in fixed implant restorations depend on the region of tooth replacement. In the posterior (not esthetically critical) zone, ceramics such as zirconia (3-5-Ymol%) and lithium-disilicate are recommended to be used in a monolithic fashion. In the anterior sector, ceramic restorations may be buccally micro-veneered for an optimal esthetic appearance. Lithium-disilicate is only recommended for single-crowns, while zirconia (3-5-Ymol%) is also recommended for multiple-unit and cantilever restorations. Attention must be given to the specific mechanical properties of different types of zirconia, as some feature reduced mechanical strengths and are therefore not indicated for all regions and restoration span lengths. Metal-ceramics remain an option, especially for cantilever restorations.

Influence of crown-lengthening surgery on teeth rehabilitated with ceramic single crowns: A 12-month prospective clinical study.

OBJECTIVE: To compare the clinical periodontal parameters of teeth restored with a single ceramic crown, with and without crown lengthening procedure. METHODS: This prospective, longitudinal, controlled, and single-blinded clinical trial involved 22 patients with a total of forty-one teeth with ceramic crowns. The teeth were divided into two groups: test (n = 21), comprising teeth rehabilitated post crown-lengthening surgery, and control (n = 20), comprising teeth rehabilitated without crown-lengthening surgery. Plaque index (PI), gingival index (GI), probing depth (PD), bleeding on probing (BoP), and clinical attachment level (CAL) were compared between groups (surgically treated and non-surgically treated) and within each group for each type of site (treated -tt; adjacent - ad; and nonadjacent - nad). Additionally, gingival phenotype (GP), gingival recession (GR), and keratinized tissue width (KTW) were also assessed post- restoration. Statistical analyses used a significance level set at 5 %. RESULTS: PI, GI, and BoP were reduced, but no statistically significant differences were observed within each group or between groups for most follow-up periods. CAL of the TT sites was consistently higher in the test group, and PD was also higher in the test group (p < 0.05), except at T3. adPD, nadPD, adCAL, and nadCAL demonstrated no significant differences between groups and periods. A significant association was identified between GP and the occurrence of GR, with the thick-flat phenotype demonstrating less association with GR, regardless of whether crown lengthening was performed or not. CONCLUSION: Crown-lengthening surgery in rehabilitated teeth does not significantly affect PI and GI after 12 months. Although crown-lengthening surgery affected PD and CAL in TT sites, it did not affect adjacent and non-adjacent sites. CLINICAL RELEVANCE: These findings emphasize the importance of considering individual patient factors and the potential impact on periodontal tissues when planning crown-lengthening surgery. Clinicians must have a comprehensive understanding of the dynamics of the periodontal tissues involved in restorative treatments to optimize the procedure, increase success rates, and minimize potential complications.

The effect on the performance of a dynamic navigation system of superimposing a standard tessellation language (STL) file obtained with an intraoral scan on a cone beam computer tomograph (CBCT). An experimental in vitro study.

OBJECTIVES: To compare the accuracy and operative time of implant placement using a dynamic computer assisted implant surgery (dCAIS) system based on a cone beam computer tomography (CBCT) image, with and without superimposing a standard tessellation language (STL) file of an intraoral scan of the patient. METHODS: Ten identical resin models simulating an upper maxilla with posterior edentulism were assigned to two groups. In the CBCT+STL group, a CBCT file and an intraoral STL file were superimposed and used for registration; in the CBCT group, registration was performed using CBCT images. Six implants were placed in each model using the Navident® dynamic navigation system. Anatomy registration was performed by tracing fiducial points on the CBCT or STL image, depending on the group. Preoperative and postoperative CBCT images were overlaid to assess implant placement accuracy. RESULTS: Sixty implants were analyzed (30 implants in each group). 3D platform deviation was significantly lower (mean difference (MD): 0.17 mm; 95 % confidence interval (CI): 0.01 to 0.23; P = 0.039) in the CBCT+STL group (mean: 0.71 mm; standard deviation (SD): 0.29) than in the CBCT group (mean: 0.88 mm; SD: 0.39). The remaining accuracy outcome variables (angular deviation MD: -0.01; platform lateral deviation MD: 0.08 mm; apex global MD: 0.01 mm; apex depth MD: 0.33 mm) and surgery time (MD: 3.383 min.) were similar in both groups (p > 0.05). CONCLUSIONS: The introduction of an intraoral scan (STL) seems to reduce deviations slightly in dental implant placement with dCAIS systems. However, the clinical repercussion of this improvement is questionable. CLINICAL SIGNIFICANCE: Superimposing an intraoral scan on the CBCT image does not seem to increase the accuracy of dCAIS systems but can be useful when radiographic artifacts are present.