Journal of Prosthodontics-Implant Esthetic and Reconstructive Dentistry最新文献

Purpose: The evidence on the mechanical reliability of thin and ultrathin ceramic crowns is inconclusive. This systematic review aimed to collect all the data on thin and ultrathin ceramic crowns, assessing their fatigue survival, mechanical behavior, and optical properties within laboratory measures.

Methods: A comprehensive literature search was conducted across PubMed, Scopus, Cochrane, and Google Scholar, concluding on May 20, 2025. All relevant studies were screened for eligibility; only English-language, peer-reviewed articles containing extractable data on thin or ultrathin ceramic crowns (measuring 0.6 to 0.9 mm and ≤ 0.5 mm, respectively) were included in this review. The meta-analysis was performed using RevMan 5.4 software from the Cochrane Collaboration, with p ≤ 0.05.

Results: A total of 14 studies were included. Both thin and ultrathin crowns demonstrated durability under thermomechanical loading for 5 years during clinical simulation. The fatigue survival rates under stepwise loading presented conflicting findings, which may be attributed to variations in procedural methodologies or cementation protocols. The mechanical strength of thin and ultrathin crowns was sufficient to endure occlusal stresses exceeding 1100 N. However, the fracture resistance of thin and ultrathin crowns was found to be statistically significantly lower than that of thick ceramic crowns (p = 0.01 and p ≤ 0.001, respectively). Furthermore, all crowns cemented with conventional cement exhibited statistically significant weakness compared to those bonded with resin cement (p ≤ 0.001). Lithium disilicate and nano lithium disilicate crowns revealed more stable optical properties than zirconia-reinforced lithium silicate, and all exhibited more staining with longer exposure time to colored drinks. Resin ceramic crowns revealed the highest microleakage rate compared with zirconia and composite crowns.

Conclusions: Laboratory evidence suggests that thin and ultrathin ceramic crowns exhibit favorable survival rates and fracture resistance. Crowns fabricated from high-strength ceramics such as 3Y-TZP performed better with conventional cements, whereas crowns cemented with adhesive resin protocols yielded similar fracture resistance regardless of crown thickness or material. Optical properties and microleakage are crown-material and time-dependent; however, evidence is scarce and remains insufficient. Thin and ultrathin ceramic crowns offer a conservative treatment option. Adhesive cementation enhances their survival, while the choice of ceramic material, cementation protocol, and luting shade is critical for optimal esthetics.

Purpose: To date, no evidence exists regarding the optimal technique/material to repair three-dimensional (3D) printed interim fixed dental prostheses (IFDPs). This study aimed to investigate different repair techniques/materials and compare their impact on the fracture strength of repaired 3D-printed IFDPs.

Materials and methods: A total of 208 3-unit IFDP specimens (n = 8) were printed using two materials (NextDent or ASIGA). One group had no surface treatment (control), while the other two groups were treated with alumina blasting and etch-primer (EP) and then repaired using flowable composite resin or Multilink in a customized putty index. Repaired specimens were thermocycled (5000 cycles) and then loaded onto a universal testing machine until fracture, and the fracture strength was recorded in newtons (N). ANOVA with Tukey's post hoc test and t-test were used for data analysis (α = 0.05).

Results: All repaired 3D-printed IFDPs exhibited lower fracture loads compared to intact specimens (p < 0.001). Repairs made with composite resin resulted in a superior fracture load than Multilink (p < 0.001). Alumina-blasting and EP treatment surface treatments significantly increased the fracture strength of repaired NextDent IFDPs compared with untreated groups (p < 0.001). EP surface treatment did not influence the repair of ASIGA specimens (p > 0.05).

Conclusion: The type of repair material significantly influences the repair strength. Repair using a composite showed the highest strength. Surface treatment (mechanical or chemical) increased repair strength for NextDent specimens. ASIGA specimens were not affected by chemical surface treatment, while mechanical treatment positively influenced repair strength.

Purpose: This in vitro study evaluated the effect of simulated brushing on color stability, surface roughness, and microbial adhesion of resin composites with different viscosities applied to denture base materials.

Materials and methods: Disc-shaped specimens (10 × 3.0 mm) were fabricated using a 3D-printed denture base resin and heat-polymerized resin. Three extrinsic characterizations (2 mm thick) were applied to the 3D-printed resin specimens: one regular-viscosity (RV) and two low-viscosity (LV49, LV30), and light-cured. The heat-polymerized resin group (STG) was fabricated and characterized using a compression-molding technique. Color coordinates and color stability (ΔE₀₀) were measured using a colorimeter; surface roughness (R_a) was assessed using an optical profilometer; and microbial adhesion (Candida albicans, log CFU/mL) was evaluated before and after 20,000 brushing cycles. Color and roughness data were analyzed using the Kruskal-Wallis test and the Wilcoxon signed-rank test, while microbial adhesion was analyzed using one-way ANOVA followed by Tukey's post hoc test (α = 0.05).

Results: STG and LV49 exhibited greater color changes than did LV30 (p < 0.05), but all groups remained within clinically acceptable limits (ΔE₀₀ ≤ 2.25). Brushing increased surface roughness in all groups except STG (p < 0.05). Microbial adhesion increased after simulated brushing (p < 0.05); however, no significant differences were observed between the groups (p > 0.05).

Conclusions: Simulated brushing affected color stability, with some groups exhibiting clinically noticeable changes. It increased surface roughness in characterizing resin composites and enhanced Candida albicans adhesion in all groups, with no significant differences between materials.

Purpose: This in vitro study aimed to evaluate the accuracy of occlusal relationships in 3D-printed dental casts, comparing two mounting methodologies.

Materials and methods: Maxillary and mandibular dental casts were scanned and digitized for virtual digital design as reference models. A total of 30 pairs of casts were printed using a digital light synthesis (DLS) 3D printer and mounted either based on hand articulation (Group HA) or using computer-aided design (CAD)-generated articulation pins (Group CAP). Accuracy was assessed by using the root mean square (RMS) values and linear measurements against the reference models.

Results: Group HA demonstrated mean RMS values of 147.9, 133.9, and 166.5 for the canine, second premolar, and second molar regions, respectively, with a mean RMS value of 149.4. Group CAP had RMS values of 398.2, 298.9, and 301.4 for the same regions, respectively, averaging at 332.8. Statistically significant differences were observed between the two groups across all sites. Linear measurements also showed notable discrepancies, especially in Group CAP, with significant differences in vertical dimension when compared to the master standard tessellation language (STL) models.

Conclusions: The mounting methodology influences the accuracy of occlusal relationships in 3D-printed dental casts. Group HA demonstrated greater accuracy and consistency in replicating occlusal relationships compared to Group CAP. These findings underscore the importance of selecting an appropriate mounting methodology for precise replication of occlusal relationships in prosthodontic treatments within digital workflows.

Electrical burns to the oral commissure are uncommon injuries that can lead to significant functional and esthetic complications if not promptly and appropriately managed. This case report details the management of a 14-year-old male with post-burn oral commissure scarring resulting from an electrical injury sustained at the age of 6. The treatment included the fabrication and application of a custom commissure splint combined with intralesional corticosteroid injections by a plastic surgeon to improve scar pliability and oral function. The report highlights the integration of dental prostheses and surgical interventions to achieve favorable outcomes.

A technique is described to obtain a 3D-printed custom tray for complete dentures through open-source, free software and additive manufacturing. This approach enables the production of custom trays in a cost-effective and optimized manner. A three-dimensional (3D) digital cast is obtained by photogrammetry and later used to design a digital custom tray. Then, the digital custom tray is manufactured by a 3D printer to be used in clinical procedures. This technique is a clean, rapid, and low-cost alternative to the traditional technique.