Journal of Esthetic and Restorative Dentistry最新文献

Objectives: To evaluate the influence of preheating and water storage on color, whiteness, and translucency of one-shaded, group-shaded, and multi-shaded resin-based composites.

Materials and methods: A total of 270 samples were fabricated from one-shaded (Omnichroma), group-shaded (Optishade MD), and multi-shaded (Enamel Plus HRI) resin-based composites and divided into six groups: no heating (control) and 1-5 heatings (test) (n = 15). The CIE L*, a*, b*, C*, and h° color coordinates were registered over white, black, and gray backgrounds with a spectrophotometer before and after 24, 72, 144 h water storage. Kruskal-Wallis test was used to evaluate differences in the color coordinates, whiteness index, and translucency parameter (α = 0.05). The Mann-Whitney U test was performed with a Bonferroni correction (p < 0.001) for pairwise comparisons. CIEDE2000 color, whiteness, and translucency differences between groups and subgroups were evaluated using their respective 50%:50% perceptibility and acceptability thresholds.

Results: Preheating influenced color coordinates, whiteness index, and relative translucency parameters (p < 0.001). Although color differences were below the acceptability threshold for all materials, translucency differences were above the acceptability threshold for Omnichroma. Water storage significantly influenced the whiteness index of Optishade MD (p < 0.001).

Conclusions: Preheating had a more considerable effect on the color, whiteness, and translucency of one-shaded resin-based composite, while water storage influenced group-shaded resin-based composite more importantly.

Clinical significance: Preheating influences the color, whiteness level, and translucency of the resin-based composites, but the variations remain generally clinically acceptable; however, practitioners should be aware that the modifications in translucency for one-shaded resin-based composites could be more important than for group-shaded and multi-shaded resin-based composites.

Objective: Digital technology in dentistry has advanced rapidly in recent years, and as a result, the identification of static virtual articulation as a crucial stage in the digital process has attracted increasing attention. The use of intraoral scanners (IOSs) has made the acquisition of occlusal records more efficient. The purpose of this article is to review information on evaluation methods and influencing factors on the accuracy of static virtual articulation obtained by intraoral scanners.

Overview: An electronic search of the published literature was performed up to November 2023 using five databases: PubMed, Cochrane, Embase, Web of Science, and Scopus. The inclusion criteria were defined as relevant clinical or in vitro English studies on the accuracy of the occlusal relationship obtained using intraoral scanners. Therefore, a total of 30 articles were selected, reviewed, and discussed. Based on the results of the literature review, three methods have been used to evaluate the accuracy of virtual interocclusal records, including distance measurement (10 studies), occlusal contact analysis (13 studies), and deviation analysis after superimposing casts (8 studies). However, direct comparisons between these studies are challenging due to the different methods employed. Factors that were found to potentially impact accuracies, such as the range of vestibular scans, the number and position of virtual interocclusal records (VIRs), the location and extension of edentulous areas, alignment methods, and evaluation software programs have been extensively studied, but the extent to which these factors affect accuracy remains uncertain and varies depending on the specific circumstances.

Conclusions: A combination of multiple evaluation methods for a more rigid assessment of virtual interocclusal records may be a better approach. Attention should be given to the factors that may influence the accuracy of virtual interocclusal records. Future research should focus on optimizing these factors to improve the clinical applicability of virtual interocclusal records.

Clinical significance: In restorative dentistry, virtual interocclusal records obtained with intraoral scanners have been successfully used with acceptable accuracy, although they present some issues. Understanding the evaluation methods for virtual interocclusal records and the factors that may affect the accuracy of VIRs may lead to better use in clinical practice.

Objectives: To classify the complete-arch implant scanning techniques recorded by using intraoral scanners (IOSs).

Overview: Different implant scanning techniques have been described for recording complete-arch implant scans by using IOSs. However, dental literature lacks on a classification of these implant scanning techniques. Implant scanning techniques aim is to record the 3-dimensional position of the implants being scanned, while implant scanning workflows require additional scans to record all the information needed for designing an implant prosthesis. This additional information includes soft tissue information, tooth position, antagonist arch, and maxillomandibular relationship.

Conclusions: There are five complete-arch implant scanning techniques captured by using IOSs: non-splinting, non-calibrated splinting, calibrated implant scan bodies, calibrated frameworks, and reverse impression methods. The digital workflow varies depending on the implant scanning technique selected.

Clinical significance: The understanding of the varying implant scanning techniques and the main differences among them may ease the decision criteria for recording digital implant scans by using intraoral scanners.

Objective: To characterize the composition, flexure resistance, and optical properties of a multilayer translucent zirconia in relation to its multi-transition zones.

Materials and methods: A multilayer zirconia (5Y/4Y) and a conventional 3 mol% yttria partially stabilized zirconia (3Y) were investigated. Bar-shaped specimens were obtained from the enamel and dentin layers, and the vertical cross-section of 5Y/4Y (N = 10). A four-point flexural (σ_f) test was performed using a universal testing machine (1.0 mm/min). Plate-shaped specimens (N = 6) were also produced from the enamel, transition 1, transition 2, and dentin layers. Translucency parameters (TP_ab and TP₀₀) were determined using a dental spectrophotometer (N = 6). X-ray fluorescence and X-ray diffraction techniques were used to analyze elemental (N = 2) and phase compositions (N = 2), respectively. Data were analyzed using analysis of variance (ANOVA) and Tukey's test (α = 0.05).

Results: The yttrium content and σ_f varied between layers of 5Y/4Y. 3Y had the highest σ_f, followed by dentin. Enamel and cross-section showed lower and statically similar σ_f. 3Y and dentin groups had similar but statistically lower TP_ab and TP₀₀ than the enamel.

Conclusions: Different layers of multilayered zirconia have distinct compositions, which affect their mechanical and optical properties. The weak enamel layer compromises the mechanical properties of cross-sectional specimens.

Clinical significance: The development of novel cubic-containing multilayer zirconia ceramics to produce monolithic restorations brings new challenges to dental clinicians and laboratory technicians. The CAD/CAM design of multilayered 5Y/4Y restorations should consider the esthetic and mechanical requirements of each clinical case, as different properties are found in the different layers of these materials.

The cover image is based on the article Three dimensionally printed template with an interproximal isolation design guide consecutive closure of multiple diastema with injectable resin composite by Yusen Shui et al., https://doi.org/10.1111/jerd.13268.