Journal of Prosthetic Dentistry最新文献

Statement of problem: Metrics-based reviews that analyze all publications on bulk-fill composite resins to identify publication characteristics and trends are lacking.

Purpose: The purpose of this study was to analyze the trends and main characteristics of articles related to bulk-fill techniques and composite resins in dentistry.

Material and methods: The search was conducted in November 2024 on the Web of Science. Three researchers selected the articles and excluded conference papers. The following data were extracted from the included articles: citations; publication year and journal; study design and topic; authorship and institutions, country, continent, and keywords. Collaboration networks were generated using the VOSviewer software program. The altmetric data were measured by consulting the Dimensions database. The correlation between the data was determined by the Spearman test.

Results: A total of 801 articles were included. The number of citations ranged from 0 to 270 and the articles had been published between 1988 and 2024. Most studies were laboratory-based (n=692) and evaluated restoration quality and polymerization stress (n=268), primarily high-viscosity composite resins (n=463) in adult patients (n=774). The country with the highest number of articles was Brazil (n=172), while the continent with the most publications was Asia (n=268). The most prominent author was Giannini (n=31) and co-authorship maps showed collaborations between groups of authors. According to Dimensions, significant mentions were identified mainly in news outlets and Mendeley readers, with the altmetric attention score ranging from 1 to 126.

Conclusions: This study identified an emerging trend in bulk-fill composite resin research in restorative dentistry. The greatest number of studies was published in Brazil, with a strong focus on laboratory studies aiming to investigate restoration quality and polymerization stress in high-viscosity composite resins of interest to Mendeley readers. Further clinical, observational, and systematic review studies are recommended.

Statement of problem: Grinding is often required for the clinical adjustments of zirconia restorations; nevertheless, the effects of following regeneration firing processes on additively manufactured zirconia are still unclear.

Purpose: The purpose of this in vitro study was to evaluate the effects of grinding and regeneration firing (RF) on the phase transformation and biaxial flexural strength (BFS) of additively or subtractively manufactured 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP).

Material and methods: A total of 108 disk-shaped (Ø15×1.5 mm) 3Y-TZP specimens (n=54) were fabricated using either subtractive manufacturing (SM) or additive manufacturing (AM) techniques. Grinding was performed using a 150-μm-grit diamond rotary instrument with a high-speed handpiece, and RF was carried out at 1000 °C for 15 minutes in a sintering furnace. The crystalline phases were analyzed using X-ray powder diffraction (XRD). All specimens were loaded until fracture using a universal testing machine for a biaxial flexural strength test at a crosshead speed of 1 mm/minute. Microstructure and fracture surfaces were examined using scanning electron microscopy. BFS data were statistically analyzed using 1-way ANOVA, followed by the Tukey post hoc test for pairwise comparisons. (α=.05). The Weibull modulus and characteristic strength were calculated to assess the reliability of strength data.

Results: Tetragonal-to-monoclinic phase transformation was detected in ground specimens of both AM and SM groups, whereas only the tetragonal phase was observed in their corresponding RF groups. The highest BFS (1427.2 MPa) was observed in ground AM specimens (P<.001). Grinding and RF did not significantly affect the BFS of SM zirconia (P=.927 and P=.999, respectively) but significantly increased the BFS of AM zirconia (P<.001). RF increased the Weibull modulus in both AM (from m=6.98 to 12.25) and SM (from m=5.91 to 8.35) zirconia.

Conclusions: The implementation of RF after grinding is crucial, particularly for AM zirconia, to improve mechanical strength and structural reliability.

This presentation combines a conceptual overview with a real clinical application. A 24-year-old woman, referred for esthetic enhancement, received porcelain veneers using the Bright Corus protocol. The outcome was biologically respectful, esthetically harmonious, and anatomically precise, with minimal human intervention and a high degree of predictability. This treatment exemplified how artificial intelligence-driven digitally assisted dentistry can enhance the reliability of restorative procedures by orchestrating a unified, precision-guided workflow.

Statement of problem: Denture hygiene is essential for oral health as acrylic resin roughness affects Candida albicans adhesion. Cleaning methods may alter surface properties, warranting further research to determine the most effective long-term approach.

Purpose: The aim of this in vitro study was to compare the effect of different denture cleaning procedures on the surface roughness and Candida adhesion of acrylic resins.

Material and methods: A total of 120 resin specimens were divided into 12 subgroups (n=10), including 3 materials, a heat-polymerized acrylic resin (Meliodent), an autopolymerized acrylic resin (Meliodent Rapid Repair), and a hard reline material (GC Reline Hard) and 4 cleaning methods, distilled water (control group), Corega alkaline peroxide-containing effervescent tablet, brushing, and electrolyzed water. Surface roughness values of the resin specimens were measured using a contact profilometer device before cleaning and after 7, 30, and 90 days. Candida adhesion was measured and colony forming units (CFU/mL) were assessed. Statistical analysis was performed by using 3-way ANOVA followed by the Bonferroni correction for the surface roughness data and the Kruskal-Wallis test for Candida colonization (α=.05).

Results: The surface roughness values of the 3 different acrylic resin materials decreased significantly 30 and 90 days after applying the denture cleaning procedures (P<.001). The denture cleaning procedure affected the surface roughness of heat-polymerized (P<.001) and autopolymerized resins after 90 days (P=.002). The surface roughness of the hard reline materials were affected by different cleaning procedures at all time intervals. Candida adhesion was significantly lower in all type of acrylic resin materials after immersion in alkaline peroxide-based cleansing tablets (P<.001).

Conclusions: According to the findings of this study, when evaluating surface roughness, the cleaning procedure with electrolyzed water may be an alternative to mechanical cleaning but should be improved in terms of removing Candida adhesion. Chemical cleaning with denture cleaning tablets was found to be optimal for long-term usage.

Statement of problem: Acrylic resin denture teeth have been widely used in prosthodontics because of their affordability and ease of fabrication. However, their susceptibility to discoloration over time poses a significant esthetic challenge for denture wearers. Various intrinsic and extrinsic factors influence color stability, yet the impact of material composition and different brands remains inadequately explored.

Purpose: This systematic review and meta-analysis aimed to assess the impact of material composition and different brands of acrylic resin teeth on their color stability.

Material and methods: The PubMed, Scopus, Web of Science, Science Direct, and Cochrane Collaboration databases were analyzed. Studies from 2019 to 2023 on the color stability of acrylic resin denture teeth were assessed, and 11 articles were selected based on specific inclusion criteria.

Results: All the included studies showed that acrylic resin teeth were susceptible to discoloration, with variations by brand and material, influenced by composition, staining agents, and immersion duration. Brands of acrylic resin teeth such as Ivoclar (Ivoclar AG) and SR Orthosit PE (Ivoclar, AG) demonstrated superior resistance to discoloration, while Tritone (Vipi), SR Phonares II (Ivoclar AG), and Z250 (Filtek, 3M ESPE) showed higher color changes in various staining solutions. Polymethyl methacrylate teeth showed discoloration, while the cross-linked polymethyl methacrylate and nanohybrid composite resin formulations offered better color stability. Brands incorporating hydrophobic materials and reinforced polymer matrices generally maintained color stability more effectively over extended immersion time periods.

Conclusions: Material composition and brand significantly affected the color stability of acrylic resin denture teeth. Advanced resin formulations and composite-based materials exhibited improved resistance to discoloration.

Statement of problem: The consistency of the placement force provided by striking friction-locked abutments remains uncertain.

Purpose: The purpose of this in vitro study was to evaluate different strikes and repeated reconnection-disconnection cycles on the connection strength of a locking taper implant system with varying wells.

Material and methods: Sixty-three implant-abutment replica specimens (IARSs) with 2-, 2.5-, and 3-mm wells with a 1.5-degree locking taper design were fabricated from grade 5 titanium (Ti). Specimens were divided into 3 striking groups (3T, 6T, 12T, n=21/group) and 3 well subgroups (3T2, 3T2.5, 3T3; 6T2, 6T2.5, 6T3, and 12T2, 12T2.5, 12T3, n=7/subgroup). For subgroups 3T2, 3T2.5, and 3T3, the abutments were seated in the implants with finger load and then struck 3 times with a calibrated striker. The abutments were then disconnected using rotational movements and the removal torque values were recorded with a digital torque meter in newton centimeter (Ncm). This seating, striking, and removal cycle was repeated 7 times by the same operator. The same procedure was applied to the second and third subgroups with 6 and 12 strikes respectively. ANOVA and post hoc Bonferroni tests were used to analyze the data. Repeated measures ANOVA with the Greenhouse-Geisser correction was applied when the sphericity assumption was violated (α=.05).

Results: Removal torque values varied significantly with well diameter and the number of strikes (P<.001), peaking at 3 mm with 12 strikes. Torque values were statistically similar after repeated disconnection-reconnection cycles (P>.05).

Conclusions: Although wider wells and higher striking cycles tended to increase the removal torque and repeated disconnection-reconnection tended to decrease it, the values remained statistically similar.

Statement of problem: The nasal prosthesis is an artificial solution to the restoration of tissue in the nasal region, traditionally requiring time-intensive manual sculpting directly on the patient's face. Whether a novel, automated approach using Convolutional Neural Networks (CNNs) can reconstruct the nasofacial region from 2-dimensional (2D) photography is unclear.

Purpose: The purpose of this study was to evaluate whether the automated approach could generate 3-dimensional (3D) models suitable for direct 3D printing.

Material and methods: The Residual U-Net architecture was trained on a dataset derived from CelebA-HQ comprising 12 000 image pairs (input images with trapezoidal masks and corresponding mask-free output images). The dataset's normalized and square-aligned images facilitated efficient training, with the masked area prioritized during reconstruction through weighted loss functions. The model's performance was evaluated using Peak Signal-to-Noise Ratio (PSNR).

Results: Accurate reconstruction of nasal geometries that harmonized well with the overall facial structure were demonstrated. Visual assessments confirmed the approach's effectiveness, although minor limitations such as inconsistent texture modeling were observed under nonideal conditions. Beyond technical validation, this automated solution should reduce laboratory and clinical time requirements, minimizing patient travel and emotional stress and enhance accessibility to personalized prosthetic care. By leveraging advancements in CNNs and image-to-3D model conversion and manufacturing techniques, this approach offered a suitable path toward automating the creation of nasal prostheses.

Conclusions: This work represents a significant step toward automating the creation of nasal prostheses, enabling faster, more cost-effective, and patient-friendly solutions for patients with midfacial deficiency.