Journal of Prosthetic Dentistry最新文献

Statement of problem: The static computer-aided implant system (S-CAIS), dynamic computer-aided implant system (D-CAIS), and robotic computer-aided implant system (R-CAIS) have been used to improve the accuracy of implant placement. However, the accuracy of freehand (FH),S-CAIS, D-CAIS, and R-CAIS implant placement has not been compared and verified under identical conditions.

Purpose: The purpose of this in vitro study was to compare the accuracy of dental implant placement using S-CAIS, D-CAIS, R-CAIS, and FH techniques under identical conditions.

Material and methods: A total of 60 standardized polyurethane resin models with missing mandibular teeth were prepared and divided into 4 groups: FH, S-CAIS, D-CAIS, and R-CAIS, each consisting of 15 models. Preoperative implant planning was performed using cone beam computed tomography (CBCT), and 2 implants were placed in each model using the FH, S-CAIS, D-CAIS, and R-CAIS techniques, respectively. Postoperatively, CBCT scans were made for analysis of the entry, apical, and angle deviations. The error results among groups were compared using 1-way analysis of variance or a nonparametric test. The Dunnett test was used for post hoc comparison (α=.05).

Results: The mean ±standard deviation values for entry deviation were 1.09 ±0.33 mm for the FH group, 0.72 ±0.33 mm for S-CAIS, 0.69 ±0.29 mm for D-CAIS, and 0.48 ±0.18 mm for R-CAIS (P<.05). The mean (quartiles) apical deviations were 1.01 (0.94 -1.22) for the FH group, and the mean ±standard deviation values were 0.87 ±0.07 mm for the S-CAIS group, 0.64 ±0.05 mm for D-CAIS, and 0.47 ±0.03 mm for R-CAIS (P<.05). The mean ±standard deviation values for angle deviation for the FH group were 2.74 ±0.84 degrees, 1.99 ±0.76 degrees for S-CAIS, 0.85 ±0.46 degrees for D-CAIS, and 0.53 ±0.20 degrees for R-CAIS (P<.05).

Conclusions: R-CAIS is a reliable implant placement method, demonstrating better implant accuracy compared with the S-CAIS, D-CAIS, and FH techniques.

Statement of problem: Although the use of artificial intelligence (AI) seems promising and may assist dentists in clinical practice, the consequences of inaccurate or even harmful responses are paramount. Research is required to examine whether large language models (LLMs) can be used in accessing periodontal content reliably.

Purpose: The purpose of this study was to evaluate and compare the evidence-based potential of answers provided by 4 LLMs to common clinical questions in the field of periodontology.

Material and methods: A total of 10 open-ended questions pertinent to periodontology were posed to 4 distinct LLMs: ChatGPT model GPT 4.0, Google Gemini, Google Gemini Advanced, and Microsoft Copilot. The answers to each question were evaluated independently by 2 periodontists against robust scientific evidence based on a predefined rubric assessing the comprehensiveness, scientific accuracy, clarity, and relevance. Each response received a score ranging from 0 (minimum) to 10 (maximum). After a period of 2 weeks from initial evaluation, the answers were re-graded independently to gauge intra-evaluator reliability. Inter-evaluator reliability was assessed using correlation tests, while Cronbach alpha and interclass correlation coefficient were used to measure overall reliability. The Kruskal-Wallis test was employed to compare the scores given by different LLMs.

Results: The scores provided by the 2 evaluators for both evaluations were statistically similar (P values ranging from .083 to >;.999), therefore an average score was calculated for each LLM. Both evaluators gave the highest scores to the answers generated by ChatGPT 4.0, while Google Gemini had the lowest scores. ChatGPT 4.0 received the highest average score, while significant differences were detected between ChatGPT 4.0 and Google Gemini (P=.042). ChatGPT 4.0 answers were found to be highly comprehensive, with scientific accuracy, clarity, and relevance.

Conclusions: Professionals need to be aware of the limitations of LLMs when utilizing them. These models must not replace dental professionals as improper use may negatively impact patient care. Chat GPT 4.0, Google Gemini, Google Gemini Advanced, and Microsoft CoPilot performed relatively well with Chat GPT 4.0 demonstrating the highest performance.

Statement of problem: Scientific evidence to determine the clinical performance of angled screw channel (ASC) versus straight screw channel (SC) implant-supported prostheses is lacking.

Purpose: This systematic review and meta-analysis investigated the mechanical and biological complications of ASC compared with those of SC implant-supported prostheses.

Material and methods: A systematic search was conducted by following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline in the PubMed, Embase, and Web of Science databases and was supplemented with a manual search for clinical studies reporting the mechanical and biological complications of ASC compared with those of SC implant-supported prostheses. The search was focused on porcelain fracture, screw loosening or fracture, marginal bone loss (MBL), and pink esthetic score (PES). The data were extracted from selected articles and compounded to estimate the complications with a 95% confidence interval (CI) using a random effects meta-analysis. The publication bias was assessed using the Cochrane Risk of Bias and Newcastle-Ottawa Scale (α=.05).

Results: A total of 4217 records were identified, and 14 studies were selected for quantitative synthesis of 629 participants with 658 ASC and 166 SC implant-supported prostheses. The meta-analyses of comparative studies showed no statistically significant difference in mechanical complications between ASC and SC prostheses, with odds ratio (OR) of 1.75 (95% CI=0.71-4.34, P=.224). Porcelain fracture and screw loosening were the most common complications with ASC prostheses. In addition, no statistically significant difference was found between ASC and SC prostheses in the MBL (mean difference=-0.07, 95% CI=-0.15-0.01, P=.077) and PES (mean difference=-0.19, 95% CI=-0.90-0.52, P=.593).

Conclusions: The clinical performance of ASC may be comparable with that of SC implant-supported prostheses in terms of mechanical and biological complications. However, the moderate level of evidence necessitates further research to validate these findings.

Statement of problem: Prosthetic screw loosening is a common mechanical complication of implant-supported fixed dental prostheses. Although techniques for detecting screw loosening in single implant-supported fixed dental prostheses have been reported, studies on the screw stability for splinted implant-supported fixed dental prostheses are lacking.

Purpose: The purpose of this in vitro study was to determine whether acoustic resonance frequency analysis using a newly developed system could detect prosthetic screw loosening in splinted implant-supported fixed dental prostheses.

Material and methods: Maxillary and mandibular edentulous gypsum casts with screw-retained definitive fixed dental prostheses supported by 6 implants were used. A tapping simulation (0.2 N, 50 Hz) was directly applied to the buccal side of the tested screw, and a pickup device was used to collect the acoustic signals. The resonance peak frequencies of these signals were extracted by using time-frequency-domain analysis based on short-time Fourier transform. A 2-way mixed analysis of variance was performed to evaluate how jaw position and insertion torque affect resonance peak frequency. The Pearson correlation analysis was used to assess the relationship between the insertion torque and resonance peak frequency for each screw (α=.05).

Results: Deviation from the insertion torque resulted in significant changes in the resonance peak frequency within 6 to 9 kHz. Additionally, significant positive correlation between the insertion torques and resonance peak frequencies was observed for all screws (P<.05). This correlation was affected by the position of the screw within the prosthesis. Specifically, screw loosening in the posterior and anterior regions had a greater influence on the resonance peak frequency than that in the central region.

Conclusions: The acoustic resonance peak frequency shifted leftward as the screw preload torque decreased, indicating a significant correlation with screw stability. These results suggest that acoustic resonance frequency analysis can be used to detect the stability status of a single prosthetic screw in a splinted implant-supported fixed dental prosthesis conveniently and with high sensitivity.

Statement of problem: Poor or lack of adherence to supportive peri-implant therapy (SPIT) or supportive care has been associated with a significantly higher rate of peri-implantitis or peri-implant mucositis. However, whether therapy with or without the removal of an implant-supported prosthesis yields different outcomes remains unclear.

Purpose: The purpose of this clinical study was to evaluate the efficacy of ultrasonic devices in treating participants with or without the removal of implant-supported prostheses after more than 12 months of loading.

Material and methods: Twenty participants with 23 implant-supported fixed prostheses (39 implants) with indications for removal were included in this study. The following clinical parameters were recorded before the prostheses were removed: the maximum probing depth (PDmax), bleeding on probing (BOP), months of loading, and complications. Each prosthesis was removed and treated with a regular plaque indicator test and then reinserted. This was followed by the intraoral administration of regular supportive therapy via ultrasonically driven polyetheretherketone instrument tips. After instrumentation, the prostheses were removed to access the area positively stained for calculus or biofilm. PT0 and PT1 show the plaque coverage before and after intraoral ultrasonic cleaning, respectively. The reduction in the positive staining area and the efficacy of ultrasonic cleaning with or without prosthesis removal were measured. The Kolmogorov-Smirnov test was performed to verify that the sample data were normally distributed. Comparisons between PT0 and PT1 were conducted via paired t tests, followed by the Student t test for comparisons between groups (α=.05).

Results: A 27.3 ±15.0% reduction in plaque coverage was observed after the implant restorations had been cleaned intraorally. The efficacy of intraoral ultrasonic cleaning was only 45.4 ±20.6%, with a residual plaque rate of 54.6%. Cleaning without the removal of implant-supported restorations was less effective in participants with a PD >5 mm than in the other participants (P=.001). Neither the emergence angle nor the emergence profile had a significant influence on the cleaning effectiveness (P>.05).

Conclusions: Biofilms at the abutment-prosthesis connection and mucosal and proximal surfaces of the prosthesis may not be effectively cleaned by conventional SPIT. Biofilm reduction is improved by prosthesis removal when the PD is >5 mm.

Statement of problem: Bonded screw-retained implant-supported prostheses may become contaminated during fabrication, leading to biological complications. Studies supporting effective cleaning methods are sparse.

Purpose: The purpose of this in -vitro study was to compare the effectiveness of 3 different cleaning techniques for the removal of contaminants on the surfaces of bonded screw-retained implant-supported prostheses.

Material and methods: Forty-five screw-retained implant-supported prostheses were divided into 3 groups after their processing in the digital laboratory. Group VS included specimens cleaned using vapor steam, group ME using a multi-enzyme cleaner in an ultrasonic bath, and group 3UC using the 3-step ultrasonic cleaning method with different solutions. The presence of contaminants was determined using scanning electron microscopy (SEM) under ×200 and ×500 magnifications and energy dispersive X-ray spectroscopy (EDS). The ImageJ software program was used to locate and quantify the debris. Statistical tests, including the Wilcoxon signed-rank test, Kruskal-Wallis test, and Dunn test were used to evaluate the effectiveness of the 3 cleaning techniques.

Results: Statistically significant differences in the number of surface contaminants were observed at the implant-abutment interface in all 3 groups (P<.05) after each cleaning technique, with the highest mean difference for the 3-step ultrasonic cleaning. Elements such as carbon, oxygen, titanium, and calcium showed statistically significant differences (P<.05) compared with other elements among the groups.

Conclusions: All 3 cleaning techniques reduced the contaminants on the surfaces of the screw-retained implant-supported prostheses. The 3-step ultrasonic cleaning method yielded the best results.

An implant-supported overdenture is a cost-effective option that enhances both appearance and function. Advances in computer-aided design and computer-aided manufacturing (CAD-CAM) technology have simplified the procedures for denture fabrication, reducing time and costs while increasing patient satisfaction. However, fractures in overdentures are often caused by misalignment of the occlusal registration, excessive force, material wear, and insufficient space between the denture base and the attachment. Reinforcing the overdenture with a metal framework enhances mechanical strength, stability, and durability. A novel technique with a double milling procedure of a single resin disk using a digital workflow for a maxillary overdenture reinforced with a selective laser melting metal framework should increase the mechanical strength and accuracy of the implant overdenture.

Statement of problem: The effect of 3-dimensional (3D) printed crown materials with lower flexural strength but higher ductility than lithium disilicate on enamel wear and fatigue resistance is unknown.

Purpose: The purpose of this in vitro study was to compare the enamel wear and fatigue resistance of a 50% filled 3D printed crown material with lithium disilicate.

Material and methods: Disks of a 3D printed crown material (Ceramic Crown; SprintRay Inc) and lithium disilicate (IPS e.max CAD; Ivoclar AG) (n=8) were tested for wear in a custom Alabama wear testing device which applied a 20-N load and 2-mm horizontal slide. The test was run for 400 000 cycles at 1 Hz in a 33% glycerin solution. Cusps of extracted human molars were used as the antagonists. The volumetric wear of the restorative material and enamel antagonists were measured every 100 000 cycles using a profilometer. Worn specimens were examined with a scanning electron microscope. Human molars were prepared for occlusal onlay preparations, and 1.2-mm 3D printed (Ceramic Crown) or lithium disilicate (IPS e.max CAD) restorations (n=10) were bonded to the teeth with resin cement. Restorations were subjected to 2 million cycles of fatigue loading (50 N, 1 Hz) in water against a Ø7.8-mm steel ball. Restorations were monitored for cracks every 100 000 cycles with transillumination and every1 million cycles with microcomputed tomography (µCT). After fatigue, specimens were fractured in a load-to-failure test. Fractured specimens were examined with µCT. Statistical analyses were performed with 2-way mixed ANOVAs and a t test (α=.05).

Results: The wear and opposing enamel wear of lithium disilicate was greater than the 3D printed material at every interval of cycles tested (P<.001). None of the restorations showed signs of internal cracks up to 2 million cycles of fatigue. No statistical difference was found in the load-to-failure fracture load of the 3D printed (2574 ±303 N) or lithium disilicate (2396 ±277 N) restorations (P=.110).

Conclusions: For the conditions tested, the 3D printed crown material demonstrated less wear than lithium disilicate and created less opposing enamel wear. All the occlusal onlay restorations survived 2 million cycles of fatigue at a 50-N load without signs of cracks. These results provide some support for the use of these restorations at 1.2-mm occlusal thickness when bonded with a resin cement.

Statement of problem: Implant-supported monolithic zirconia restorations manufactured using the additive 3-dimensional (3D) gel deposition technique have been introduced. However, studies determining the trueness and adaptation of implant-supported crowns made with the technique are lacking.

Purpose: The purpose of this in vitro study was to evaluate the trueness and adaptation of implant-supported zirconia crowns fabricated using additive 3D gel deposition in comparison with zirconia crowns made with the widely used subtractive milling technique.

Material and methods: Crowns were fabricated for wide-diameter titanium implants and wide-neck abutments. Self-glazed zirconia (SGZ) crowns were fabricated using 3D gel deposition (n=10) and from 2 brands of zirconia blanks, Wieland and Upcera, using subtractive milling (WMZ and UMZ, n=10). All crowns were digitalized by a scanner, and then 3D deviation analysis was applied. The trueness was assessed by root mean square (RMS). Marginal and internal adaptations were evaluated using the direct-view technique (DT) and replica technique (RT). The results were analyzed by using the 1-way ANOVA and Kruskal-Wallis statistical tests (α=.05).

Results: The RMS and marginal discrepancy of SGZ exhibited the lowest values among the 3 groups (P<.05), and the 2 types of milled zirconia crowns had comparable RMS and marginal discrepancy values (P>.05). The internal discrepancy values of SGZ were significantly lower than those of WMZ and UMZ in all regions (P<.05). Compared with the WMZ, UMZ showed comparable internal discrepancy values in the axial and axio-occlusal transition regions (P>.05) but had significantly lower internal discrepancy value in the occlusal region (P<.05).

Conclusions: The adaptation of 3 types of wide-diameter implant-supported zirconia crowns can meet the clinical requirements. Compared with the subtractive milling process, 3D gel deposition produced implant-supported zirconia crowns with improved trueness and adaptation.