Journal of Prosthetic Dentistry最新文献

Interim crowns for immediately placed implants have been fabricated by using a prefabricated thin-walled hollow crown attached to an interim abutment. This article describes an alternative digital workflow for fabricating an immediate monolithic implant-supported interim restoration with a prefabricated screw-access channel and a positioning device. The workflow is based on prosthetically driven implant planning with computer-aided design and computer-aided manufacturing (CAD-CAM). This approach reduces the chair time required to adapt a thin-walled hollow crown to an interim abutment and forming a screw-access channel. The technique also eliminates the use of large amounts of relining resin material that can affect the color match of a thin-walled hollow crown in esthetically challenging locations.

The present technique uses a novel digital workflow that combines precise computer-aided design (CAD) with a 2-step milling process, allowing for the high-precision incorporation of metal mesh into the denture base without compromising tissue adaptation. This approach provides edentulous patients with a safer, longer-lasting, and more comfortable removable prosthesis.

A debonded post-and-core crown was relined with a light-body impression material to accurately capture the post space. After digitization and data alignment, an additively manufactured zirconia post-and-core crown was designed, fabricated, and delivered to replace the failed restoration. This technique offers a practical and efficient solution to replacing debonded or poorly adapted post-and-core restorations, reducing the need for a dedicated intraoral scanner.

This clinical report describes the digitally assisted prosthodontic rehabilitation of a patient with severe tooth wear and reduced vertical dimension of occlusion (VDO). Three-dimensional facial scanning, virtual waxing, and mandibular movement tracking analysis were used to evaluate esthetic and functional outcomes at incremental VDO increases of 2, 4, and 6 mm. Three-dimensionally printed posterior indices facilitated facial assessment and patient communication. A 4-mm increase was selected based on facial profile analysis and occlusal harmony. Interim and definitive restorations were fabricated from monolithic zirconia. The definitive restorations achieved harmonious function and esthetics, as assessed at the 3-year recall. These findings highlight the value of digital facial analysis and posterior index assisted simulation in individualized VDO planning for managing a patient with severe tooth wear.

Statement of problem: Fully automated artificial intelligence (AI)-based computer-aided design (CAD) software programs have shown promise for single-unit crown design, but their accuracy, acceptability, and efficiency in designing multi-unit fixed dental prostheses (FDPs) remain unclear.

Purpose: This in vitro study evaluated the design acceptability, trueness, and efficiency of 2 commercially available fully automated AI -based CAD software programs in designing anterior and posterior 3-unit FDPs compared with those designed by dental laboratory technicians.

Material and methods: Digital scans of natural abutments prepared for 3-unit fixed dental prostheses (12 anterior and 18 posterior FDPs) were replicated into 3 sets and allocated for restoration design by Certified Dental Technician (CDT), dentbird (DB), and Atomica AI (AA). Restoration designs were evaluated qualitatively using an 11-criteria acceptability score by 3 calibrated prosthodontists and quantitatively using root mean square (RMS) deviation analysis. CAD times were recorded for each group. Statistical analyses included the Kruskal-Wallis test followed by the Dunn post hoc test, paired t test, and repeated-measure ANOVA followed by the paired t test to evaluate intergroup differences (α=.05).

Results: DB successfully generated all designs (100%), while AA achieved a 93% overall success rate (83% for anterior and 100% posterior FDPs). AA obtained acceptability scores comparable with those of CDT, particularly in posterior FDPs, while DB exhibited significantly lower scores, especially in anterior FPDs. Both AI programs scored lower than CDT in occlusal and proximal contact areas and connector size (P<.001). AA demonstrated lower RMS deviation than DB in anterior FDPs (P<.05). Both AI systems significantly reduced design time, with AA completing design faster than DB in anterior FDPs (P<.05).

Conclusions: Fully automated AI-based CAD systems demonstrated variable performance in 3-unit FDP design. AA achieved acceptable trueness and morphology, particularly in posterior regions, while DB underperformed in esthetic and functional areas. Although both systems improved design efficiency, human oversight remains essential for occlusal and proximal contact, connector design, and anterior FDPs.

Statement of problem: Although minimally invasive repair of existing resin-based restorations is clinically advantageous, the effects of different surface pretreatments on additively and subtractively manufactured resins remain insufficiently studied. This lack of evidence hinders the development of a standardized and reliable protocol for the repair of such materials.

Purpose: This in vitro study aimed to evaluate the impact of different mechanical and chemical surface pretreatments (airborne-particle abrasion, grinding, universal adhesive application, or no treatment) on the shear bond strength (SBS) of composite resin repairs on hydrothermally aged resin-based materials, used either additively or subtractively for definitive fixed dental prostheses.

Material and methods: A total of 240 resin disks (Ø10×2 mm) were fabricated using 3 additive manufacturing resins (C&B Permanent; Tera Harz TC-80DP; and Crowntec); and 1 subtractive manufacturing resin (Brillant Crios) (n=60 each). All specimens underwent hydrothermal aging through 5000 thermal cycles between 5 °C and 55 °C. Disks were randomly assigned into 3 mechanical pretreatment groups: airborne-particle abrasion with 50 µm Al₂O₃ particles, grinding with a diamond rotary instrument, or no treatment (control) (n=20 each). Each group was then randomly divided into 2 chemical surface pretreatment subgroups: application of a universal adhesive (Clearfil Universal Bond Quick) or no treatment (control) (n=10 each) and then composite resin (Clearfil Majesty ES-2 Classic) was bonded in the center of the surface-treated area. SBS was assessed using a universal testing machine at a crosshead speed of 1 mm/minute. Failure modes were analyzed under a microscope at ×12.5 magnification. Statistical analysis included a 3-way ANOVA and chi-squared test to evaluate the effects of material, mechanical pretreatment, and adhesive on SBS (α=.05).

Results: The application of an adhesive substantially increased the SBS (Mean difference (MD): 6.91 ±3.30 MPa; P<.001). When adhesive was used, no differences were observed between resin materials or mechanical surface pretreatments (airborne-particle abrasion or grinding) in either SBS or failure mode (chi-squared test). In contrast, in the absence of adhesive, significant differences were found between materials (P<.001) and mechanical pretreatment (P=.001) for both outcomes.

Conclusions: Repair bond strength depended on the application of an adhesive. When applied, the impact of resin material and mechanical pretreatment remained minimal.

Statement of problem: Multiple noncalibrated splinting implant scanning techniques have been described. These techniques include the use of various materials, custom milled and printed devices, and horizontal implant scan bodies (ISBs) to connect adjacent implants aiming to increase scanning accuracy. However, the accuracy of these methods remains uncertain. Additionally, limited noncalibrated splinting methods are commercially available.

Purpose: The purpose of this systematic review was to analyze the accuracy (trueness and precision) of complete arch implant scans recorded by using commercially available noncalibrated splinting or noncalibrated ISBs methods.

Material and methods: A literature search was completed in 5 databases: PubMed/Medline, Scopus, Embase, Web of Science, and Cochrane. A manual search was also accomplished. Investigations analyzing the trueness and/or precision of complete arch implant scans using commercially available noncalibrated splinting techniques or noncalibrated ISBs were included. Two investigators evaluated the studies independently by applying the Joanna Briggs Institute critical appraisal. A third examiner was consulted to resolve any lack of consensus.

Results: A total of 12 articles were included: 10 in vitro and 2 in vivo. A total of 7 commercially available noncalibrated splinting methods were investigated among the reviewed studies. Five studies analyzed the accuracy of Bridge+ system, 1 evaluated the performance of IOConnect, 2 assessed the accuracy outcomes of M6 Dental method, 3 tested Multi-Unit Polo, 1 measured ScanLadder (Direct and Indirect techniques), 3 analyzed Smart Flag, and 1 examined Optisplint.

Conclusions: The scientific evidence regarding the accuracy of the commercially available noncalibrated splinting and noncalibrated ISBs methods is limited. Significant accuracy values discrepancies were found among the noncalibrated methods; however, all the noncalibrated techniques obtained accuracy values within the clinically acceptable threshold of 150 µm.

Accurate data acquisition is essential for the efficiency and predictability of complete arch implant-supported restorations. Conventional and hybrid workflows often require multiple analog steps, such as cast fabrication, mounting, verification, or the use of reference screws with repeated scans. These additional procedures may increase complexity, prolong treatment, and introduce errors through multiple dataset merges. Rapid Digital Conversion (RDC) 2.0 represents a fully digital, cast-less workflow that eliminates the need for reference screws, physical casts, and intraoral verification jigs. In this protocol, the patient serves as the articulator and occlusion is established virtually. This video article demonstrates the clinical application of RDC 2.0 in a mandibular complete arch prosthesis. An anterior scanning device was fabricated from a sectioned immediate denture and connected to anterior multiunit abutments to capture the interocclusal record. The scan was completed with soft-tissue scan bodies, followed by a biocopy step and definitive alignment. The resulting dataset provided all information necessary for digital articulation, implant position integration, and interim restoration design. RDC 2.0 simplifies the restorative process, reduces chair time, minimizes potential errors, and enables accurate same-day or next-day delivery of interim restorations.