Journal of Prosthetic Dentistry最新文献

Statement of problem: Three-dimensional (3D) printing has been increasingly used in dentistry as an alternative to conventional restorative materials, but the mechanical, biological, optical, and long-term properties of 3D printed resins remain unclear.

Purpose: The aim of this systematic review was to synthesize the mechanical, optical, and biological properties of 3D printed resins intended for definitive restorations.

Material and methods: A Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA)-compliant search in the MEDLINE/PubMed, Embase, and Web of Science databases was performed following a registered protocol (PROSPERO CRD420250653401).

Results: Forty‑two eligible studies from 2020 to 2025 evaluated 7 resins. Crowntec (Saremco) generally showed the highest mechanical properties. The mechanical performance of all 3D printing resins, particularly in terms of flexural strength, surface roughness, and Vickers hardness, remained below that of most computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin blocks. Optical data indicated clinically acceptable ΔE00 values without exposure to staining agents. Data on biocompatibility remained limited.

Conclusions: This systematic review highlighted the potential and current limitations of 3D printed resins for definitive restorations. They were found to exhibit favorable mechanical and optical properties and potentially favorable biological properties for definitive single-unit restorations, but they remain mechanically and optically inferior to CAD-CAM composite resin blocks.

Statement of problem: Digital photogrammetry systems have the potential to simplify implant recording procedures and improve accuracy. Nevertheless, the surface and linear scan accuracy of these systems, particularly those using intraoral photogrammetry technology, compared with that of conventional impressions, has not been fully established.

Purpose: The purpose of this in vitro study was to evaluate the surface and linear scan accuracy (trueness and precision) of intraoral and extraoral photogrammetry systems by comparing them with conventional polyvinyl siloxane impressions for complete arch mandibular implant-supported prostheses.

Material and methods: An edentulous master mandibular stone cast with 6 implants was digitized with an industrial-grade scanner to generate its reference standard tessellation language (R-STL) file. Digital scans of the master cast were made using intraoral (Aoralscan Elite, AE) and extraoral photogrammetry systems (Icam4D, IC; OxoFit, OX), while stone casts obtained from conventional polyvinyl siloxane impressions of the master cast (CNV) were digitized with a laboratory scanner (n=20). The R-STL file and the STL files of all recordings were imported into an analysis software program to calculate the surface and linear deviations of the recording methods. While the surface deviations were analyzed with the Welch analysis of variance and Tamhane T2 tests, the linear deviations were assessed with Kruskal-Wallis and Bonferroni-adjusted post hoc tests. Precision was defined as the average of how much each measurement differed from the overall mean and was statistically analyzed with Kruskal-Wallis and Bonferroni-adjusted post hoc tests (α=.05).

Results: OX recordings had the highest surface deviations, while CNV impressions had the lowest linear deviations (P≤.009). In addition, OX led to lower linear deviations than IC (P=.002). Regardless of the outcome, IC led to the lowest values when the precision of the measured deviations was considered (P<.001).

Conclusions: Although the tested recording methods showed significant differences in scan accuracy, the magnitude of deviations was small, and the deviations were within clinically acceptable thresholds.

Statement of problem: The growing use of 3-dimensional (3D) printed denture base materials presents challenges in bonding with resilient denture liner materials, as traditional protocols may not suit their surface properties.

Purpose: The purpose of this in vitro study was to evaluate the effect of different surface treatments on the tensile bond strength between 3D printed denture base materials and a resilient denture liner material.

Material and methods: A total of 300 rectangular blocks (10×10×20 mm) were fabricated in 5 types of materials: a heat-polymerized polymethyl methacrylate (PMMA) and 4 types of 3D printed resins (Ivotion, Lucitone, APEX, and Dentca). The blocks were first thermocycled (5000 cycles, 5 °C-55 °C) and treated with either no surface treatment (control), alumina airborne-particle abrasion, or a chemical bonding agent. A 3-mm layer of Coe-Soft was applied between 2 blocks, and tensile bond strength was measured using a universal testing machine. Failure modes were assessed via SEM. Data were analyzed using 2-way ANOVA and the Tukey post hoc tests (α=.05).

Results: Bond strength was significantly affected by both surface treatment and material type (P<.001). Mechanical treatment yielded the highest bond strength in APEX (0.28 ±0.01 MPa) and Dentca (0.28 ±0.04 MPa), while chemical treatment decreased bond strength in the PMMA, Dentca, and Lucitone groups. Ivotion showed no significant response to either treatment (P>.05).

Conclusions: Surface treatment and material type significantly influenced tensile bond strength. Mechanical surface treatment generally improved bonding, while chemical treatments showed inconsistent effects depending on the material.

Immediate implant placement in the esthetic zone remains clinically challenging, particularly at sites with a retained impacted tooth. This clinical report illustrates the enhanced accuracy and favorable clinical outcomes of robot-assisted immediate implant placement in this situation, presenting a minimally invasive protocol for precise implant placement without damaging the adjacent impacted tooth.

Statement of problem: Conventional surgical guides pose challenges in patients with limited mouth openings, restricting coolant flow and risking surface contamination from sleeves. Although alternative implant guide designs such as handpiece guides have been developed, a scoping review of their performance is lacking.

Purpose: The purpose of this scoping review was to identify studies reporting the various designs of handpiece implant guides, understand their design features, method of fabrication, and seating accuracy, with their advantages and limitations, summarize the literature evidence on the accuracy of implant placement, and recognize research gaps in the field of handpiece-guided implant surgery.

Material and methods: A literature search was conducted in the PubMed, Scopus, Cochrane, EBSCO, and Google Scholar electronic databases for English-language publications. The types of articles considered eligible were clinical reports, technical notes, in vitro studies, and experimental or interventional studies on handpiece-guided surgical guide designs.

Results: Of the 350 studies retrieved based on the search strategy and inclusion criteria, 14 were selected. Eight were clinical studies, and 6 were clinical reports or technique articles. The guide systems consisted of 2 commercially available surgical guides, StentCAD and Ingis, and 2 other designs of handpiece attachments. The angular deviations in handpiece-guided systems ranged from 2.5 to 5.0 degrees, coronal deviations at the shoulder from 0.52 to 1.70 mm, and apical deviations from 0.7 to 1.99 mm over free‑hand surgery (angular deviation of 1.40 to 7.36 degrees, coronal deviation of 1.25 to 2.77 mm and apical of 2.10 to 2.91 mm) and fully guided implant systems (angular deviation of 0.32 to 3.36 degrees and coronal deviation of 0.54 to 2.34 mm and apical of 0.90 to 2.53 mm).

Conclusions: The handpiece guide systems consisted of 2 commercially available surgical guides, StentCAD and Ingis, and 2 other designs of brass-based irrigation and tooth-template guides. The accuracy of implant placement of handpiece guides was comparable with that of freehand and fully guided implant systems.

Digital workflows integrating computer-aided design and computer-aided manufacturing (CAD-CAM) have improved precision in implant-supported prostheses. This article describes a step-by-step technique for guided mandibular implant placement and the CAD-CAM fabrication of a patient-specific titanium bar based on cone beam computed tomography (CBCT) segmentation, anatomic reconstruction, and a functional digital waxing. The workflow combines prosthetically driven planning with anatomic reference alignment to enhance bar adaptation and prosthetic accuracy. The digital sequence allows clinicians and dental laboratory technicians to virtually design and verify the bar on a 3-dimensionally printed mandibular model before clinical application, minimizing chairside adjustments and improving interdisciplinary communication when providing complex complete arch implant-supported prostheses.

Impression making for obturator fabrication in patients with a maxillectomy and extensive maxillary defects can be challenging because of anatomic complexity, restricted mouth opening, and difficulty in achieving an effective seal. This article presents an interlocking sectional tray technique in which the intaglio surface of an existing obturator is merged with intraoral scan data to design a custom tray without a cast. The interlocking sectional tray system enables separate recording of the defect and dentate areas in a closed-mouth position with simultaneous occlusal registration.

Abutment screw loosening is a common complication in single-implant restorations, and retrieval is often hindered by the risk of damaging the implant collar or by the unavailability of specialized kits. This article describes a straightforward, cost‑effective chairside technique that uses readily available modeling plastic impression compound to engage a damaged abutment-screw head and facilitate retrieval. After confirming loosening radiographically and cleaning the access, softened modeling plastic impression compound is loaded into the access hole; the hexagonal driver is coated with a separating medium and pressed into the softened material to create a hollow imprint. The driver is then reinserted to seat within the indentation, and a controlled anticlockwise rotation retrieves the damaged screw while preserving the implant's internal structure. The method can be integrated into conventional workflows and avoids reliance on expensive retrieval kits, offering a practical option when standard tools are unavailable. Limitations include dependence on the remaining screw-head geometry and lack of large‑scale validation; further clinical evaluation is recommended.

Statement of problem: The long-term clinical performance of computer-aided design and computer-aided manufacturing (CAD-CAM) materials in indirect Class II restorations remains unclear, as most studies have reported only short-term or in vitro outcomes.

Purpose: The purpose of this single-blind randomized clinical trial was to evaluate the 5-year performance of indirect Class II restorations using lithium disilicate glass-ceramic, polymer-infiltrated ceramic, and composite resin with nanoscale filler.

Material and methods: A total of 41 participants received 60 restorations using Cerasmart (CS; GC), Vita Enamic (VE; VITA Zahnfabrik), or IPS e.max CAD (IEC; Ivoclar AG) blocks. Restorations were evaluated at 1 week, 1 year, and 5 years using World Dental Federation (FDI) criteria. Kruskal-Wallis and Friedman tests with Bonferroni adjustment were applied (α=.05); missing data were handled with multiple imputation (intention-to-treat [ITT]).

Results: At 5 years, 42 restorations were available for evaluation (69% follow-up). Acceptable outcomes (FDI scores 1-3) were observed in 55% (CS), 65% (VE), and 60% (IEC), with no significant group differences (adjusted P>.05). IEC showed better color match and less marginal staining (adjusted P<.001), confirmed in both complete-case and ITT analyses. ITT further revealed differences in surface gloss and anatomic form (adjusted P≤.007). Functional and biological parameters showed no between-group differences, though ITT indicated progressive within-group deterioration in CS and VE over time (adjusted P<.001).

Conclusions: All materials demonstrated generally acceptable 5-year biological and functional performance, though clinical acceptability ranged between 55% and 65%. IEC provided superior long-term esthetic stability.

A standardized digital protocol for the virtual mounting of a semi-adjustable articulator by integrating cone beam computed tomography (CBCT) and intraoral and facial scans is described. The datasets were aligned in a dental design software program using craniofacial reference points and oriented to the Frankfort horizontal plane for accurate spatial positioning. Mandibular movements were simulated by adjusting the condylar inclination and Bennett angles to visualize functional occlusal contacts. This workflow eliminated physical facebow transfers, reduced operator variability, and enhanced interdisciplinary communication. By combining advanced imaging and prosthodontic principles, the protocol enabled precise, predictable, and collaborative treatment planning.