Journal of Prosthetic Dentistry最新文献

This article presents an innovative 3-dimensionally (3D) printed surgical guide design that incorporates a supplementary saline irrigation tube, digitally designed as part of the guided system. The additional saline irrigation line was created using a Y-shaped connection that branched off the main saline line. The presented technique features a targeted, automated, and consistent saline irrigation flow for enhanced cooling and debris removal during osteotomy preparation. The aim of this design modification was to improve the surgical efficiency and safety of implant site preparation and potentially promote improved osseointegration.

Surgical guides play a crucial role in achieving accurate implant placement, yet their physical presence often obstructs the clinician's view of the surgical site. Conventional methods for improving access using sutures or surgical instruments frequently introduce additional tools into the operative field, potentially hindering the surgical workflow. This technique article describes a straightforward yet effective modification to conventional implant guides by integrating retractor arms and attachment hooks on the buccal and lingual aspects. The arms gently displace the cheek and tongue, while the hooks retract the gingival flaps, collectively ensuring sufficient exposure of the alveolar bone crest. Importantly, these accessories can be designed using the existing connector-generation modules in common guide-design software programs and require no additional training with the program.

Statement of problem: Implant-supported prostheses provide a reliable method of replacing missing teeth. To avoid complications, their accurate placement is critical. Advances in static computer-aided implant surgery (sCAIS), which uses 3-dimensional (3D) imaging and printing, have improved implant placement accuracy. However, whether the location of supporting teeth (anterior versus posterior; maxilla versus mandible) influences accuracy has not been fully explored.

Purpose: The purpose of this prospective observational clinical study was to assess the accuracy of 3D printed, tooth-supported implant surgical guides in both the anterior and posterior regions of the maxilla and mandible.

Material and methods: A total of 67 participants (116 implants) were included, with preoperative cone beam computed tomography (CBCT) and intraoral scans used to plan implant positions. Printed surgical guides were used for implant placement, and deviations (entrance, apical, depth, and angular) were measured postoperatively. Implant deviations were analyzed using mixed-effects models with patient intercepts and Holm-Bonferroni-adjusted tests.

Results: No significant differences in accuracy were found between the anterior and posterior regions or between the maxilla and mandible (P>.05). The mean deviations were similar across entrance, apical, depth, and angular parameters. Apical deviation exhibited the highest inaccuracy, while depth deviation showed the least variation across all regions. The maxilla showed the most notable deviation in the mesiobuccal direction and the least deviation in the mesiolingual direction (P=.029), while other regions showed no statistically significant differences (P>.05).

Conclusions: Printed, tooth-supported implant surgical guides demonstrated high accuracy across all regions, with apical deviation as the main source of inaccuracy.

Statement of problem: Localized tooth wear compromises function and esthetics, while conventional restorative options often require invasive preparation. Evidence on the long-term stability of 3-dimensionally (3D) printed restorations applying the Dahl concept is limited.

Purpose: The purpose of this preliminary clinical trial was to evaluate the clinical feasibility and long-term stability of 3D printed, noninvasive restorations implementing the Dahl concept for managing localized tooth wear while preserving tooth structure and restoring vertical dimension of occlusion.

Material and methods: Five patients with localized tooth wear received 3D printed computer-aided design and computer-aided manufacturing (CAD-CAM) restorations fabricated using digital workflows. Intraoral scans were performed at baseline and follow-up visits at 6, 12, and 24 months after insertion. Quantitative movement was analyzed using 3D superimposition techniques to assess posterior tooth extrusion and anterior tooth intrusion. The Wilcoxon rank sum test and independent t test were used for statistical analysis (α=.05).

Results: Posterior tooth extrusion demonstrated a characteristic time-dependent pattern with progressive stabilization from 0.37 ±0.25 mm at 6 months to 0.31 ±0.23 mm at 24 months. Movement variability decreased substantially over time, indicating predictable treatment outcomes. Anterior tooth intrusion remained clinically absent throughout the observation period (median ≤0.07 mm), confirming the preservation of vertical positioning. The 3D superimposition analysis corroborated quantitative measurements, revealing controlled bilateral posterior movements while maintaining anterior stability.

Conclusions: The provision of 3D printed, noninvasive restorations successfully implemented the Dahl concept, achieving predictable vertical dimension restoration with progressive occlusal stabilization over 24 months while preserving dental hard tissues.

Statement of problem: A high prevalence of localized tooth wear has been reported among the adult population. The Dahl concept is a method of gaining space for restoring localized tooth wear, but a systematic review and meta-analysis is lacking.

Purpose: The purpose of this study was to systematically assess the clinical outcomes of fixed Dahl restorations for treating localized tooth wear.

Material and methods: Electronic searches were conducted in the PubMed, Embase, Cochrane Central Register of Controlled Trial, Web of Science, and Scopus databases and in the website ClinicalTrials.gov up to June 2025. Randomized clinical trials (RCTs), cohort studies, and case series were identified. The revised Cochrane risk of bias tool, the Newcastle-Ottawa scale, and the Joanna Briggs Institute critical appraisal were respectively adopted to assess the quality of the RCTs, cohort studies, and case series. The certainty of the evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). Poisson regression was used to compare the clinical results of direct and indirect materials (α=.05). Meta-analysis and meta-regression were conducted for occlusal re-establishment.

Results: A total of 11 studies were included in the review, with 8 studies classified as low risk and 3 as moderate risk of bias. Annual failure rates (AFRs) and annual complication rates (ACRs) of fixed Dahl restorations using direct materials were 0% to 8.7% and 5.2% to 30.2%, respectively, after 1.3 to 7 years of follow-up. AFRs and ACRs of indirect restorations were 0 to 0.7% and 5.6% to 7.2%, respectively, after 1.7 to 2.2 years of follow-up. The AFRs of indirect materials were much lower than those of direct materials (P<.05). Restoration fracture, wear, and loss accounted for most failures and complications. Occlusal re-establishment after fixed Dahl restorations was mainly reported between 1 and 25.4 months. The pooled proportions of no occlusal contact, partial, and complete occlusal re-establishment were 0.6%, 10.0%, and 86.9%, respectively. These values were not influenced significantly by the patient's age. GRADE revealed low to moderate levels of evidence for the pooled proportions.

Conclusions: Based on low- to moderate-level evidence, fixed Dahl restorations were found to be a suitable treatment option for treating localized tooth wear. Most of the patients treated with the fixed Dahl restorations were satisfied with the clinical outcomes, even though the range of time of therapy was wide and a high propensity for restoration failures and complications was found.

Statement of problem: Current methods of evaluating denture retention lack clinical relevance because of simplified testing conditions and limited design innovation. Bioinspired features such as octopus-like suction cups (SCs) offer a promising solution but remain underinvestigated. A more realistic in vitro model incorporating a peripheral seal (PS), artificial saliva, and these novel designs is needed to better assess and enhance denture retention.

Purpose: The purpose of this in vitro study was to evaluate the influence of preload forces, PS simulation, and spatially distributed octopus-inspired SC surface modifications on the retention of maxillary complete dentures.

Material and methods: The investigation was conducted in 2 phases. In Phase I, 12 3-dimensionally (3D) printed maxillary dentures were divided into 2 groups (n=6) to assess the effect of a simulated PS. Group NO PS (control) lacked a PS, while Group PS incorporated a silicone-based PS created using a printed mold. Retention was measured using a vertical pull-off test under 2 preload forces (4 N and 10 N) with artificial saliva. In Phase II, 50 dentures were assigned to 5 groups (n=10): Smooth (smooth surface), PSC (palatal SCs), Peri-SC (peripheral SCs), Peri-NSC (peripheral negative suction cups), and Adhesive-smooth (smooth surface with adhesive). All dentures were tested using the same PS simulation and preload conditions with triplicate retention measurements. Data were analyzed using 2-way analysis of variance (ANOVA) and Tukey post hoc tests (α=.05).

Results: Retention significantly increased in the presence of a PS at both preload levels (P<.05). Higher preload forces enhanced retention across all groups. Adhesive-smooth exhibited the greatest retention (P<.001), Peri-NSCs outperformed the Peri-SCs, PSCs, and Smooth dentures.

Conclusions: The simulated PS method provides a more clinically relevant approach to denture retention testing. Bioinspired SC modifications significantly improved denture retention under varying preload conditions tested using the simulated PS. Peri-NSCs represent a promising design strategy for enhancing the retention and stability of maxillary complete dentures.

Statement of problem: Intaglio surface accuracy is essential for the proper fit and clinical performance of occlusal veneers. Comparative data on subtractive and additive methods for occlusal veneers fabricated from patient-derived casts with severe tooth wear are limited.

Purpose: The purpose of this in vitro study was to evaluate the trueness and precision of occlusal veneers fabricated by subtractive milling (Tetric CAD; Ivoclar AG) and additive manufacturing (Saremco print CROWNTEC; Saremco Dental AG) in a severely worn molar using a patient-derived cast under laboratory conditions.

Material and methods: A digital scan of the mandibular first molar tooth of a patient with severe occlusal wear was obtained using an intraoral scanner. Occlusal veneers were digitally designed and fabricated by milling (n=20) or 3-dimensional printing (n=20). Intaglio surface scans were compared with the reference design in the Geomagic Control X software program to assess trueness; precision was determined by pairwise alignment within groups. Data normality was assessed with Kolmogorov-Smirnov and Shapiro-Wilk tests, and groups were compared with the Mann-Whitney U test (α=.05).

Results: Trueness was significantly higher in the milling group (P<.05), while no significant difference in precision was observed (P>.05). Both materials showed trueness values within clinically acceptable limits (≤200 µm).

Conclusions: Subtractive milling produced more accurate intaglio surfaces than additive manufacturing, though both methods demonstrated acceptable adaptation and similar reproducibility. Although both methods appear to be clinically applicable, subtractive manufacturing offers higher trueness, whereas additive manufacturing provides advantages in material and cost efficiency.

Statement of problem: Plasma electrolytic polishing (PEP) offers a promising alternative to conventional polishing methods for additively manufactured (AM) Ti-6Al-4V (Ti64) removable partial denture (RPD) frameworks. However, its effect on the fatigue performance of AM Ti64 RPD clasps remains unclear.

Purpose: The purpose of this in vitro study was to evaluate the effect of PEP on the fatigue behavior of AM Ti64 RPD clasps and compare it with that of mechanical polishing.

Material and methods: AM Ti64 specimens were fabricated and divided into 4 groups: untreated (Raw), mechanical polishing (MP), pure plasma electrolytic polishing (PEP), and mechanical grinding followed by PEP (MG +PEP). Cylindrical specimens (Ø10×5 mm) were prepared for Vickers hardness testing. Clasp-shaped specimens were prepared for intaglio surface roughness assessment (n=10), X-ray diffraction (XRD) residual stress analysis (n=5), mercury intrusion porosimetry (MIP) porosity measurement (n=10), and fatigue testing across displacements from 0.30 mm to 1.00 mm for 10⁵ cycles (n=5 per displacement). Clasp fracture surfaces were examined using a scanning electron microscope (SEM). Finite element analysis (FEA) was conducted using Abaqus 2019 to evaluate the stress distribution and maximum principal stress of AM Ti64 clasp under simulated displacement. Statistical analyses were performed using 1-way ANOVA and Kruskal-Wallis tests (α=.05).

Results: No significant differences in Vickers hardness were observed among groups (P>.05), except between the Raw and MG +PEP groups (P=.012). The PEP group exhibited significantly rougher intaglio surfaces compared to the MP group (P=.001), while no difference was found between MP and MG +PEP groups (P=.433). The polished groups demonstrated similarly low porosity levels (MP: 0.427%, PEP: 0.372%, MG +PEP: 0.335%), in contrast to the Raw group (1.838%). Fatigue testing revealed significantly improved performance in the MP group compared to the Raw group (P=.044); no significant differences were found among the polished groups (P>.05). SEM analysis showed fatigue cracks originating from surface and subsurface defects. FEA indicated that regions of stress concentration corresponded to observed fracture sites.

Conclusions: Although pure PEP treatment was not found to provide an optimal surface finish for AM Ti64 RPD clasps, its combination with mechanical grinding resulted in surface characteristics comparable to mechanical polishing. PEP-treated AM Ti64 clasps demonstrated fatigue resistance similar to that of mechanically polished counterparts.

Statement of problem: Polyetheretherketone (PEEK) can be adopted as a coping material for implant-supported crowns. However, data on the fracture resistance of PEEK implant-supported posterior crowns produced by different fabrication techniques are scarce.

Purpose: The purpose of this in vitro study was to evaluate the effect of different fabrication techniques on the fracture resistance of PEEK implant-supported posterior crowns.

Material and methods: Thirty implants were placed in autopolymerizing acrylic resin blocks, with implant abutments positioned on each implant. Thirty PEEK copings were fabricated and assigned to 3 groups (n=10) depending on the fabrication technique: group MP, milled from a reinforced PEEK disk; group PP, heat pressed from PEEK granules; and group AMP, additively manufactured from PEEK filaments. All PEEK copings were veneered with a nanohybrid composite resin in the form of the maxillary right premolar. Then, a composite resin cement was used to cement the crowns to the implant abutments. All crowns underwent cyclic loading in a mastication simulator (1 200 000 cycles, 1.7 Hz, and 50 N). Fracture resistance was determined by using a universal testing machine, and the failure mode was recorded by using a stereomicroscope at ×15 magnification. A representative fractured crown from each group was assessed under a scanning electron microscope (SEM) at ×1000 magnification. Data were analyzed by using 1-way analysis of variance and the pairwise Tukey (HSD) tests (α=.05).

Results: No debonding, chipping, or fractures were detected after cyclic loading. The mean ±standard deviation fracture load values after cyclic loading were 1047 ±108 N for the MP group, 762 ±78 N for the PP group, and 647 ±65 N for the AMP group. Statistically significant differences in fracture resistance were observed among all groups (F=56.77, P<.001). For the failure mode, all groups exhibited 100% unfavorable failures, as coping fractures necessitated complete restoration replacement.

Conclusions: The fabrication technique and material formulation influenced the fracture resistance of PEEK implant-supported posterior crowns. Milled PEEK implant-supported crowns exhibited significantly higher fracture resistance than heat-pressed or additively manufactured ones; however, all fabrication techniques produced fracture loads exceeding normal physiologic occlusal forces, regardless of differences in material formulation.

Statement of problem: Although complete dentures have been widely used in clinical practice, a synthesis of the evidence using a comprehensive bibliometric analysis is lacking.

Purpose: The purpose of this study was to map and quantify research trends on complete dentures using a comprehensive bibliometric analysis of the scientific literature.

Material and methods: Publications on complete dentures in the Web of Science Core Collection (2005 to 2024) were retrieved by topic search and limited to articles and reviews. A total of 2497 records were analyzed with bibliometric software programs (VOSviewer, CiteSpace, Bibliometrix, and Microsoft Excel).

Results: Shunsuke Minakuchi was the most productive author. The University of São Paulo ranked first in both publications and citations. The United States led in publication volume, total citations, and H-index. The Journal of Prosthetic Dentistry led in output and citations. Keyword co-occurrence and reference co-citation analyses indicated a stable thematic structure centered on digital and automated manufacturing, personalized design, materials innovation, and patient-reported outcomes (satisfaction and quality of life).

Conclusions: The global output of research on complete dentures has increased steadily, and international collaboration networks among leading countries and institutions have expanded. Research remains anchored in prosthodontics, with core outlets in specialty journals, and has shifted toward digital fabrication, including computer-aided design and computer-aided manufacturing (CAD-CAM) and 3-dimensional (3D) printing and patient-reported outcomes, including satisfaction and quality of life.