STATEMENT OF PROBLEM:Proper prosthetic fit is essential to prevent biofilm accumulation and inflammatory reactions in the peri-implant region. Early detection of misfit at the abutment-prosthesis interface is critical, and periapical radiography has been widely used for this purpose during treatment. However, whether the presence of a cement line influences the accuracy of the radiographic detection of misfit at this interface remains unclear. PURPOSE:To evaluate the influence of a cement line on the detection of abutment-prosthesis misfit of different magnitudes using the bisecting-angle and paralleling periapical radiographic techniques. MATERIAL AND METHODS:A total of 320 periapical radiographs obtained by the bisecting-angle and paralleling techniques were used to analyze 50-, 100-, and 150-µm simulated misfits between the abutment and the prosthetic crown. Three dentists evaluated the images using a 5-point confidence scale (definitely present, probably present, uncertain, probably absent, and definitely absent). Diagnostic accuracy, assessed by the area under the receiver operating characteristic curve (Az), sensitivity, and specificity, were analyzed using Generalized Linear Models (α=.05). RESULTS:Sensitivity was higher in the cemented groups, particularly for 50 µm (0.87 versus 0.48; P<.001), whereas specificity was higher in the noncemented groups across all techniques and misfit magnitudes (P<.001). Az values were significantly influenced by radiographic technique (P=.005), cementation (P=.035), and misfit magnitude (P<.001), with significant interaction effects between cementation and both technique (P<.001) and magnitude (P=.002). CONCLUSIONS:The presence of a cement line increases sensitivity but reduces specificity, favoring the detection of misfit at the expense of a higher rate of false-positive findings.
STATEMENT OF PROBLEM:Advancements in computer-aided design and computer-aided manufacturing (CAD-CAM) have enabled greater precision and customization in implant abutment fabrication. However, current evidence remains limited regarding the comparative mechanical stability and torque retention of stock versus CAD-CAM-fabricated abutments, particularly under dynamic loading conditions. PURPOSE:The purpose of this study was to compare the stability and removal torque values of custom CAD-CAM abutments and stock abutments before and after dynamic loading. MATERIAL AND METHODS:This systematic review was registered on PROSPERO (CRD42025634444) and conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive electronic search was performed across the PubMed, Scopus, EBSCOhost, and Google Scholar databases for studies published between January 2010 and November 2025. Only English-language in vitro studies evaluating removal torque values for stock versus CAD-CAM abutments were included. Data extraction and meta-analysis were performed using the Review Manager (RevMan; version 5.4; Cochrane Collaboration) software program. Risk of bias was assessed using the Quality Assessment Tool for In Vitro Studies (QUIN), and certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach on the GRADEpro platform. A leave-one-out sensitivity analysis was conducted to assess the robustness of the pooled estimates. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated under a random-effects model. Heterogeneity was assessed using the I² statistic, and statistical significance was defined at α=.05 (P<.05). RESULTS:Among 1222 identified studies, 5 met the inclusion criteria for qualitative synthesis and 4 for meta-analysis, comprising 107 implant-abutment assemblies. Meta-analysis revealed significantly higher removal torque values for stock abutments compared with CAD-CAM abutments both before (SMD=-0.91; 95% CI: -1.56 to -0.26; P=.006) and after (SMD=-1.05; 95% CI: -1.87 to -0.23; P=.01) cyclic loading. Moderate heterogeneity was observed (I²=54%). The overall certainty of evidence was rated as very low. CONCLUSIONS:Despite better customization, CAD-CAM abutments demonstrated greater torque reduction compared with stock abutments both before and after dynamic loading, suggesting reduced preload maintenance under functional stresses. Further long-term clinical studies are required to validate these in vitro findings.
STATEMENT OF PROBLEM:Limited evidence is available regarding the clinical behavior of the newly developed materials and computer-aided technologies used to fabricate occlusal devices. PURPOSE:The purpose of this retrospective study was to evaluate the effect of digital manufacturing techniques and materials on the clinical performance of occlusal devices. MATERIAL AND METHODS:A total of 49 participants treated with computer-aided design and computer-aided manufacturing (CAD-CAM) occlusal devices were included in this retrospective clinical study. Two different manufacturing technologies, 3-dimensional (3D) printing and milling, and 3 different materials were investigated. Fully and hybrid digital workflows were applied. In the fully digital workflow, intraoral scans were imported into a dental software program, where the occlusal devices were designed and subsequently 3D printed or milled. In the hybrid workflow, maxillary and mandibular stone casts were scanned with an extraoral scanner, after which the devices were digitally designed and produced either additively or subtractively. The participants wore the occlusal devices for 6 months. Dental arch fit, surface wear, and participant satisfaction were evaluated. Descriptive statistical methods were used to evaluate the study data. ANOVA and the t test were used for comparisons. The chi-squared test was used to compare qualitative data (α=.05). RESULTS:Milled occlusal devices demonstrated significantly better fit accuracy compared with the 3D printed ones (0.039 ±0.075 mm versus 0.28 ±0.304 mm; P<.001). Material-based analysis indicated that milled polymethyl methacrylate (PMMA) and polyetheretherketone (PEEK) occlusal devices exhibited lower fit deviations than 3D printed PMMA devices (P<.001). Additively manufactured occlusal devices, regardless of workflow, revealed greater surface wear (P<.001). Occlusal contact counts did not differ significantly between workflows (P>.05). However, a significant material‑based difference was found, with PEEK showing higher contact values than PMMA‑printed devices (P=.010). CONCLUSIONS:The results suggested that occlusal devices fabricated using digital techniques showed clinical outcomes and participant satisfaction similar to those produced using hybrid workflows.
The Additive Manufacturing and Injection Molding (AMIM) technique was modified by digitally integrating custom occlusal props into a translucent 3-dimensionally (3D) printed injection guide. The design improved mandibular stability, patient comfort, and clinical handling during the placement of multiple anterior composite resin restorations without interfering with the restorative procedure. The technique was demonstrated in a patient treated with direct composite veneers.
Accurate measurement of interimplant distances and angulations is essential for evaluating implant scanning workflows in implant-supported complete arch fixed dental prostheses. Current methods such as root mean square (RMS) surface deviation and geometric primitive fitting do not capture these relationships directly: RMS lacks implant-specific localization, while geometric fitting remains operator- and geometry-dependent. A scan body-independent technique for measuring interimplant distances and angulations directly from computer-aided design-generated multiunit abutment bottom components is described. An open-source program (DIME: Direct Implant Measurement and Evaluation) was used to extract coordinates and axes from corresponding components and reports per-implant deviations and pairwise interimplant relationships. Demonstration included controlled-displacement validation on a synthetic dataset and application across digital recording workflows with different scan body geometries. By measuring the fitting surface used for framework fabrication, the method captures implant spatial data complementary to existing accuracy-evaluation approaches.
Permanent molar loss is commonly encountered in clinical practice, and eruption of the opposing teeth caused by their prolonged absence increases the complexity of restorative treatment. How to rapidly and efficiently regain precise restorative space presents a clinical challenge. Orthodontic temporary anchorage devices (TADs) have been regarded as a minimally invasive treatment alternative with absolute anchorage and can simplify orthodontic intrusion. This digital technique aims to simulate the definitive restorative treatment outcome using a digital workflow that guides the design and 3-dimensional (3D) printing of a metal occlusal veneer with implant guides to intrude the target teeth. This intrusion system enables the precise control of the target tooth movement, thereby facilitating subsequent restorative treatment and ensuring a more favorable outcome.
STATEMENT OF PROBLEM:Collagen cross-linkers have great potential for enhancing dentin bond strength, but their types are diverse, and the existing evidence requires systematic review. PURPOSE:The purpose of this study was to systematically evaluate the effects of collagen cross-linkers on the immediate bonding strength and long-term stability of the resin-dentin interface, providing evidence for their experimental and potential clinical applications. MATERIAL AND METHODS:English-language studies published between January 2015 and September 2025 were retrieved from the PubMed, Web of Science, Embase, and Cochrane databases. In vitro studies assessing the effects of cross-linkers on dentin using microtensile bond strength (µTBS) were included. Subgroup analyses were conducted according to cross-linker type and application method. A random-effects model was used to pool effect sizes, and the standardized mean difference with 95% confidence intervals was calculated. RESULTS:A total of 63 studies were included. Aldehyde-, chitosan-, riboflavin-, polyphenol-, and carbodiimide-based cross-linkers were found to enhance immediate or long-term bonding strength under specific conditions, with more consistent effects when used as pretreatment with the etch-and-rinse system. Evidence for chitosan- and siloxane-based cross-linkers was limited, and their reinforcing effects remain unconfirmed. Bonding efficacy depended on cross-linker type, application mode, and adhesive strategy. Most studies had medium bias, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) evidence was low to very low, with significant publication bias in aged subgroups of aldehyde- and polyphenol-based pretreatments. CONCLUSIONS:Current in vitro evidence indicated that certain collagen cross-linkers may help enhance the bonding properties of the resin-dentin interface. However, their effectiveness was influenced by the material type, application strategy, and adhesive system. High heterogeneity, medium risk of bias, and low-quality evidence warrant cautious interpretation.
A 63-year-old man underwent segmental mandibulectomy for ameloblastoma, followed by fibula free-flap reconstruction. As the bone volume was inadequate, guided bone regeneration (GBR) was performed using iliac particulate cancellous bone and marrow, titanium mesh, and tenting screws. After consolidation, 4 implants were placed, and restoration was completed with a computer-aided design and computer-aided manufacturing titanium bar and LOCATOR-retained overdenture. This staged approach ensured stable implant placement and successful rehabilitation. At 1 year postoperatively, the patient’s appearance and masticatory function had improved significantly, with no peri-implant or prosthetic complication. The combined application of GBR and a 2-stage protocol after fibula flap surgery enables the predictable achievement of functional reconstruction.
