Evaluation of the Effects of Digital Manufacturing, Preparation Taper, Cement Type, and Aging on the Color Stability of Anterior Provisional Crowns Using Colorimetry.

BACKGROUND Replicating the 3-dimensional (3D) color of natural teeth in artificial substitutes is challenging. Fixed dental prosthodontics require aesthetic, color-stable provisional restorations. Recent milling and 3D printing digital manufacturing techniques offer improved outcomes. This study assesses color stability in various digital manufacturing methods, tapers, and aging effects on anterior provisional resin restorations. MATERIAL AND METHODS Two all-ceramic tooth preparations on typodont teeth with 10° and 20° tapers were converted into experimental dies. Forty temporary crowns were manufactured using 3D printing and computer-aided design/computer-aided manufacturing (milling). Within these 2 groups, 10 crowns were cemented using a regular and clear provisional cement. All samples were thermocycled to simulate clinical use of 6 months. Color difference formula (CIEDE2000) indicated changes between before and after cementation (ΔE00) and between after cementation and after thermocycling (ΔE00[II]). The color change was considered significant in terms of clinically perceptible (ΔE00 ≤0.62) and acceptable (ΔE00 ≤2.62) changes. One-way ANOVA (P value of less than 0.05) calculated overall differences, which were established using a Fisher post hoc test. RESULTS Crowns cemented with clear cement showed fewer color changes irrespective of the manufacturing technique or taper. Notably, only the 10° 3D-printed crown with clear cement had an imperceptible color change at the pre-/post-cementation phase. Meanwhile, the 10° and 20° milled crowns with regular cement exhibited unacceptable color changes after thermocycling. CONCLUSIONS For long­term temporization in the aesthetic zone, properly optimized 3D-printed provisional restorations cemented with clear cement had better color stability.

Comparative Evaluation of Dimensional and Occlusal Accuracy of Non-Working Antagonist Casts: A Study on Different Impression Materials and 3D Printing.

BACKGROUND The aim of this study was to assess and compare the vertical/horizontal dimensions and occlusal accuracy of non-working/opposing casts obtained from three different impression materials and 3D print cast. MATERIAL AND METHODS Dentulous Master models simulating a case of a fixed dental prosthesis were mounted on an articulator (control group). Opposing mandibular casts obtained from three different impression materialsand 3-dimensional print constituted test groups , ,and , respectively. Three points, anterior vertical (AV), posterior vertical (PV), and anteroposterior (AP) were compared for dimensional accuracy among casts. Occlusal accuracy was analyzed on Medit Link software at 3 teeth (#13, #17, and #27). After calculating means for each group, the differences were calculated at probability value of P≤0.05 using the single-sample t test, ANOVA, and Tukey test. RESULTS The dimensions were significantly different from those of the mounted master models except in Gp AL(E) and Gp AL(F) at AV dimension and Gp AL(E) at AP dimension (P>0.05). A statistically significant difference of the error of means among the 4 tested groupswere detected only at 2 dimensions (AV and PV) between the Gp AL(E) and Gp 3D-C and between Gp AL(F) and Gp 3D-C groups. Other groups showed no significant differences. CONCLUSIONS The opposing casts obtained from the extended-pour alginate and alginate alternative impression materials showed higher occlusal accuracy compared to conventional alginate and 3D printed casts.

Physical and Mechanical Properties of 3D-Printed Provisional Crowns and Fixed Dental Prosthesis Resins Compared to CAD/CAM Milled and Conventional Provisional Resins: A Systematic Review and Meta-Analysis.

Newly introduced provisional crowns and fixed dental prostheses (FDP) materials should exhibit good physical and mechanical properties necessary to serve the purpose of their fabrication. The aim of this systematic literature review and meta-analysis is to evaluate the articles comparing the physical and mechanical properties of 3D-printed provisional crown and FDP resin materials with CAD/CAM (Computer-Aided Designing/Computer-Aided Manufacturing) milled and conventional provisional resins. Indexed English literature up to April 2022 was systematically searched for articles using the following electronic databases: MEDLINE-PubMed, Web of Science (core collection), Scopus, and the Cochrane library. This systematic review was structured based on the guidelines given by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The focused PICO/PECO (Participant, Intervention/exposure, Comparison, Outcome) question was: 'Do 3D-printed (P) provisional crowns and FDPs (I) have similar physical and mechanical properties (O) when compared to CAD/CAM milled and other conventionally fabricated ones (C)'. Out of eight hundred and ninety-six titles, which were recognized after a primary search, twenty-five articles were included in the qualitative analysis, and their quality analysis was performed using the modified CONSORT scale. Due to the heterogeneity of the studies, only twelve articles were included for quantitative analysis. Within the limitations of this study, it can be concluded that 3D-printed provisional crown and FDP resin materials have superior mechanical properties but inferior physical properties compared to CAD/CAM milled and other conventionally fabricated ones. Three-dimensionally printed provisional crowns and FDP materials can be used as an alternative to conventional and CAD/CAM milled long-term provisional materials.