The International journal of prosthodontics最新文献

Purpose: Restoring severely destructed anterior teeth without a ferrule remains a clinical challenge, and the choice between endocrowns and post-core systems is still debated. This study aimed to compare the fracture strength and failure modes of maxillary central incisors restored with conventional and CAD/CAM post-core systems versus endocrowns fabricated from different materials.

Materials and methods: Fifty endodontically treated maxillary central incisors were decoronated and divided into five groups:Glass-fiber post/composite core (F); CAD/CAM glass-fiber single-piece post-core (CF); CAD/CAM polyetheretherketone (PEEK) single-piece post-core (CP); hybrid ceramic endocrown (HE); lithium disilicate endocrown (LE). Hybrid ceramic crowns were produced on the post-core restorations. After thermocycling, fracture strength (N) was evaluated using a universal testing machine. Then the failure modes were examined under stereomicroscope. Statistical analysis was performed using Kruskal-Wallis and Tukey tests (P= .05).

Results: Group CF exhibited the highest fracture strength (331.624 N) and a 60% repairable failure rate. However, group F exhibited a 100% repairable failure, followed by the group CP, which showed 80% repairable failure. Among the endocrowns, HE demonstrated significantly higher fracture strength (313.9 N) compared with LE (128.9 N, P< .05), although both showed 60% repairable failures.

Conclusions: CAD/CAM glass-fiber post-cores and hybrid ceramic endocrowns provided superior fracture strength with predominantly repairable failures. In view of their simplified workflow and cost-effectiveness, hybrid ceramic endocrowns may be regarded as a clinically reliable restorative option for anterior teeth lacking a ferrule. In addition, the repairable nature of failures in glass-fiber posts plays a key role in preventing irreversible failures.

Purpose: Large language models (LLMs) have gained significant attention and are increasingly considered as decision-support tools in healthcare. Nevertheless, their accuracy in relation to established prosthodontic guidelines remains underexplored. The purpose of this study was to evaluate and compare the evidence-based potential of answers provided by 4 LLMs to common clinical questions regarding denture care and maintenance.

Material and methods: A total of 10 open-ended questions pertinent to denture care and maintenance were posed to 4 distinct LLMs, namely ChatGPT 4o, Google Gemini Advanced, Microsoft Copilot, and DeepSeek V3. The answers were evaluated independently by 2 prosthodontists against established guidelines for comprehensiveness, scientific accuracy, clarity, and relevance. Differences were analyzed using Friedman and Wilcoxon signed-rank tests. To assess intra-evaluator reliability, a reevaluation of the LLM responses was performed after 4 weeks, and Cronbach's α and interclass correlation coefficient (ICC) were used (α=.05).

Results: ChatGPT 4o and Google Gemini Advanced recorded the highest mean scores (8.5 out of 10), followed by DeepSeek V3 (8.4 out of 10) and Microsoft Copilot (8.0 out of 10). No statistically significant differences were observed among the models.

Conclusion: In this limited set of denture-care questions, LLMs often provided high-quality responses that aligned with ACP denture care guidelines, although occasional inaccuracies were observed. Their use shows potential as additional decision-support tools, but insights are limited to routine denture hygiene and maintenance questions. Caution and expert supervision are still crucial, as LLMs can't replace dental professionals in prosthodontic treatment or patient care.

Background: Emerging technologies have revolutionized the digital workflow in the fabrication of restorations. The reverse scan technique has been introduced as a solution for full-arch rehabilitation to simplify the recording of implant positions, as well as to improve splinted impression making and the recording of implant positions. Recent studies reported favorable outcomes for complex rehabilitation in full-arch, multiple-implant-supported restorations. However, no article in the current literature search on outcomes for short-span edentulous patients in the esthetic zone was found.

Case presentation: One of the critical aspects of achieving esthetic rehabilitation that is in harmony with pink esthetics is to provide a prototype or interim restoration that can be transferred into a definitive restoration. This reverse scanning technique enables the scanning of interim restoration designs and aesthetic parameters, allowing for the reverse engineering of the confirmed prosthetic volume from definitive materials. This patient report aims to demonstrate the proof of concept that reverse scan bodies can also be utilized as an alternative. Seventy-two-year-old female patient needs rehabilitation of maxillary four anterior incisors with implant supported screw retained restoration presented with two-piece design implants with two screw-retained abutments to support a 4-unit fixed dental prosthesis.

Conclusion: This patient report demonstrates that a reverse scan from the interim restoration used as a prototype, digitally recorded with an intra-oral scanner (Trios 4, 3Shape, Copenhagen, Denmark), can be used as a valid alternative workflow to fabricate a monolithic zirconia oxide restoration as the definitive restoration.

Purpose: The aim of the present in-vitro study was to evaluate the effect of various post-curing times (15, 30, and 45 minutes) and conditions (dry and glycerin-immersion) on the mechanical properties of a permanent crown resin used for 3D-printing.

Materials and methods: Crowns (n=90) and bars (n=90) were fabricated using a permanent crown resin (Saremco Crowntec) with a 3D printer (Nextdent 5100) in accordance with the manufacturer's recommendations. After washing with alcohol, the printed specimens were divided into 6 groups (n=15). Post-curing (LC-3DPrint Box) was performed under dry and glycerin- immersion conditions for 15, 30 and 45 minutes. A universal testing machine was used to measure the fracture resistance of crowns and the flexural strength of bars in a three-point bending test. Statistical analysis was performed using independent t-tests and one-way ANOVA (α =.05).

Results: Fracture resistance was not significantly different between the dry and glycerin- immersion groups (P ˃ .05). Flexural strength significantly decreased in the glycerin-immersion specimens, compared with the dry ones in the 15-minute post-cured group (P < .05). Fracture resistance increased, in accordance with the increment in the post-curing time, in both dry and wet conditions, even though no significant difference was obtained for post-processing times of longer than 30 minutes (P ˃ .05). In the glycerin-immersion group, flexural strength increased with post-curing time, showing a significant difference between 15 and 45 minutes (P < .05).

Conclusions: Post-curing time and conditions influence the mechanical features of the investigated 3D printed permanent crown material. The increment of the post-curing time had a favorable influence on the material's mechanical properties.

Background: This study evaluated the influence of self-image and self-esteem on overall quality of life and oral health in edentulous individuals before and after rehabilitation with new complete dentures.

Methods: An observational clinical study was conducted with 26 edentulous adults. Participants completed validated questionnaires (GOHAI, DIDL, RSES, SHS, BASS, MBSRQ-AS, ST, FOE) before treatment and 2-3 weeks after denture delivery. Pre- and post-treatment differences were analyzed using the Wilcoxon signed-rank test, and relationships among domains were examined using Spearman's correlation (α = 0.05).

Results: Significant improvements were observed in oral health perception and several psychosocial domains, including GOHAI (26.0 → 28.5; p = 0.015), self-esteem on the RSES (-0.25 → 1.0; p < 0.001), smile frequency on the ST (11.0 → 11.5; p = 0.006), and appearance-related dimensions of the DIDL (p < 0.001). Satisfaction with dental and facial-related body areas also increased, as reflected by improvements in BASS-General (37.5 → 31.0; p = 0.008), Teeth (3 → 1; p < 0.001), Mouth (2 → 1; p = 0.006), and Profile (2 → 1; p = 0.001). Spearman's analyses revealed statistically significant correlations among functional, esthetic, and psychosocial domains, of weak to moderate strength. No significant changes were detected for SHS, FOE, or the MBSRQ-AS subscales (p > 0.05).

Conclusion: Rehabilitation with dentures resulted in meaningful short-term improvements in oral-health perception, self-esteem, and esthetic self-perception. Weak to moderate correlations among functional, esthetic, and psychosocial domains indicate interconnected early changes, while broader emotional constructs showed no significant variation.

Purpose: This study aimed to compare the mechanical and surface properties of hybrid ceramic materials fabricated using different techniques for fixed dental restorations and to evaluate the clinical relevance of digital manufacturing. Five permanent hybrid resin materials produced via 3D printing and one hybrid ceramic fabricated by milling were assessed in terms of fracture resistance, surface roughness, and microhardness.

Materials and methods: Six groups were formed: five 3D-printed resins and one milled ceramic. For each group, 20 molar-shaped crowns were fabricated and divided into pre-aging and post-aging subgroups for fracture resistance testing. Additionally, 120 disk-shaped specimens were prepared. Crowns were cemented using resin cement under finger pressure and tested with universal testing machine. Surface roughness was measured with a profilometer, and microhardness was assessed using Vickers hardness tester. All specimens underwent thermal aging before retesting. Data were analyzed using SPSS.

Results: Significant differences in fracture resistance were found among groups (p<0.05). Flexcera Smile Ultra+ showed the highest values. Aging reduced fracture resistance in all groups. Senertek P-Crown V3 and Vita Enamic had higher surface roughness initially, with only Senertek P-Crown V3 showing significant post-aging decrease. The milled ceramic group showed higher microhardness than all 3D-printed groups. Post-aging, hardness increased in all but the Vita Enamic group.

Conclusion: Material selection and fabrication technique should be based on clinical requirements. Milled ceramics provide superior mechanical strength. However, the surface roughness of 3D-printed materials remained above the clinically acceptable threshold of 0.2 µm.

Purpose: This clinical study aimed to compare one-year survival rates of zirconia single-retainer resin-bonded fixed partial denture (RBFPD) on upper canines versus upper central incisors.

Materials and methods: Fifty-four multilayered, ultra-translucent zirconia single-retainer RBFPDs were placed in 50 patients, divided equally into two groups: an intervention group with a distal retainer (D-retainer) on the upper canine and a control group with a mesial retainer (M-retainer) on the upper central incisor. Patients were followed for one year. Survival was assessed by debonding, fracture, and abutment mobility using modified USPHS criteria. Patient satisfaction was measured via the visual analog scale (VAS). Fisher's exact test was used for comparisons, and survival analysis was performed with the Kaplan-Meier method (significance set at p ≤ 0.05).

Results: The D-retainer group showed an 81% survival rate, with five cases experiencing two debondings. The M-retainer group had an 86% survival rate, with three cases debonded twice. Both groups showed high patient satisfaction and stable abutment mobility.

Conclusions: Within the limitations of this study, no difference was found between canine and central incisor abutments. Both designs showed excellent fracture resistance, stable mobility, and high satisfaction. Debonding was the only failure mode. This study was registered at ClinicalTrials.gov (NCT05812066).

Purpose: To investigate the resistance, retention, and prosthetic adaptability of an abutment prosthetic support interface (APSI) for single and splinted implant restorations.

Materials and method: Twenty-five 3 mm hexagonal-tapered hybrid abutments were subjected to fatigue testing to evaluate resistance of cemented metal crowns, applied on-axis and off-axis. Crowns of three different heights, 10 mm, 12 mm, and 14 mm were assessed. Retention was evaluated via dislodgement force testing for two configurations, single crowns (n=5) cemented on five 3 mm-high hybrid abutments and five 6 mm-high 8° tapered abutments; and splinted two-unit prostheses (n=10) cemented on two 3 mm-high hybrid abutments and two 3 mm-high 8° tapered abutments, both arranged in converging implant configurations.

Results: All resistance specimens subjected to axial loading survived 1 million cycles. Off-axis loading resulted in implant body fractures in all specimens for 12 mm and 14 mm crown heights. Mean number of cycles to failure was 320,117 ± 114,230 for the 12 mm group and 137,375 ± 144,420 for the 14 mm group. Mean dislodgment forces of single crowns cemented on 3 mm-high hybrid abutments compared to 6 mm-high 8° tapered abutments were significantly different (p<0.05). Splinted prostheses on 3 mm-high hybrid abutments compared to 3 mm-high 8° tapered abutments were significantly different (p<0.001).

Conclusion: The APSI (hybrid abutment) concept demonstrated: (1) a cemented crown-abutment interface strength exceeding the inherent strength of the titanium implant material; (2) significantly greater cemented crown retention compared to tapered abutments; and (3) rotational adaptability, enabling optimized insertion paths for splinted restorations.

Purpose: The effect of ambient lighting on intraoral scanner accuracy has mostly been evaluated for single-arch scans, leaving limited evidence regarding its comparative influence on maxillary and mandibular arches. The purpose of this study was to compare intraoral scanner accuracy for maxillary and mandibular arches under varying ambient lighting conditions.

Material and methods: A maxillary and a mandibular typodont model was digitized using a laboratory scanner (3Shape E4) to obtain reference STL files. Two different intraoral scanners (iTero Element 5D and TRIOS 3) were evaluated under five different lighting conditions: zero light, daylight, room light, low intensity chair light and high intensity chair light. 10 digital scans per each group and a total of 200 scans were performed (n=10). The digital scans and the reference STL files were superimposed using Geomagic Design X software to analyze accuracy.

Results: Statistically significant differences were found among scanners, arches, and ambient lighting conditions (p<0.001). The mandibular arch showed greater accuracy than the maxillary arch (p<0.001). Zero light yielded the lowest trueness values while room light provided the most accurate results (p<0.001). Scanner performance varied under different lighting conditions, with iTero Element 5D consistently outperforming TRIOS 3.

Conclusions: Ambient lighting significantly affects intraoral scanner accuracy, with room light providing the most reliable results. Optimizing lighting conditions is crucial for improving digital impression accuracy in clinical and laboratory settings.

Purpose: This study evaluated the bond strength of flowable and packable composites to sandblasted dentin using different adhesive systems.

Materials and methods: A total of 160 extracted premolars were sectioned at the upper-middle third and allocated into 16 groups (n=10) based on composite type, surface treatment, and adhesive system. In sandblasted groups, dentin was air-abraded with 50 µm aluminum oxide for 10 s. Composite cylinders (3 mm × 3 mm; 7.065 mm²) were bonded using Single Bond 2, Palfique Bond, or Single Bond Universal. Shear bond strength (SBS, MPa) and failure modes were recorded, and bonding interfaces were examined by scanning electron microscopy (SEM). Data were analyzed using three-way ANOVA with Tukey's HSD, Kruskal-Wallis with Bonferroni correction, and Weibull analysis.

Results: Flowable composites, sandblasting, and the two-step application of Single Bond Universal each significantly improved bond strength. A three-way interaction was observed (F=5.12, p=0.01). Groups 1, 8, and 13 showed the highest bond strengths (11.47 ± 6.44, 15.88 ± 5.39, and 12.90 ± 4.98 MPa; p<0.05), with Groups 8 and 13 demonstrating superior Weibull modulus (m) and characteristic strength (σ₀). SEM analysis revealed these groups exhibited the most intimate adhesive-dentin contact with minimal interfacial defects. Failure mode assessment showed predominantly cohesive and mixed failures in Groups 1, 8, and 13.

Conclusions: Sandblasting, flowable composites, and two-step Single Bond Universal enhance dentin bond strength. The most effective combinations were sandblasted dentin with flowable composite and Single Bond Universal (one-step), and non-sandblasted dentin with packable composite and Single Bond Universal (two-step).