Journal of Prosthetic Dentistry最新文献

A method of fabricating complete dentures with metal frameworks by combining 3-dimensional printing flasks and injection molding is described. Prefabricated artificial teeth and metal bases are integrated into the digital processing workflow of complete dentures.

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.