Journal of Prosthetic Dentistry最新文献

Statement of problem: Loss of periodontal ligament-mediated mechanoreception after tooth extraction compromises tactile sensibility and occlusal control. Implant-supported prostheses partially restore this function through osseoperception, but the extent and influencing factors of active tactile sensibility (ATS) in single-implant restorations remain unclear.

Purpose: The purpose of this systematic review was to compare ATS between a single implant opposing a natural tooth and contralateral natural tooth-to-tooth contacts in functional occlusion and to evaluate clinical factors influencing implant-mediated sensory rehabilitation.

Material and methods: This review followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 guidelines (PROSPERO registration: CRD420251104655). Electronic searches of the PubMed, Scopus, and Web of Science databases, supplemented by manual searches, identified clinical studies published up to June 2025. Inclusion criteria were human investigations reporting quantifiable ATS thresholds in a single implant opposing a natural tooth and contralaterally natural tooth pairs via psychophysical testing (such as foil detection). Data extraction included study design, implant variables, testing protocols, and outcomes.

Results: Six studies were included: 4 randomized controlled trials, 1 prospective cohort, and 1 cross-sectional study. Reported ATS thresholds for implants ranged from 10 to 100 µm, while natural teeth showed lower thresholds (<10 to 50 µm). Immediate loading protocols yielded earlier and greater tactile feedback than delayed loading. Implant location (anterior versus posterior) showed inconsistent effects. Implant-supported prostheses opposing natural teeth exhibited better tactile sensibility than implant-supported prostheses occluding against other implant-supported prostheses. No consistent effects of age or sex were identified. Longitudinal studies reported progressive improvement in ATS with functional loading.

Conclusions: Osseointegrated implants develop functional tactile sensibility over time, although thresholds remain higher than those of natural teeth. Immediate loading and occlusion against natural antagonists accelerate neuroplasticity.

Statement of problem: The conventional waxing method of designing occlusion relies on the skill of the dental laboratory technician and the use of articulating paper, resulting in limited accuracy. However, the clinical effects of computer-aided design (CAD) occlusal contacts and clearance in implant-supported crowns remain insufficiently investigated.

Purpose: The purpose of this randomized clinical trial was to compare the effects of CAD occlusal contacts and clearance with those of the waxing method in posterior implant-supported single crowns.

Material and methods: Sixty patients with a single missing posterior tooth scheduled for an implant-supported crown were enrolled and randomized into 2 groups. After making impressions and pouring definitive casts, crowns with an 80-μm occlusal clearance for light contacts were designed. The control group used the waxing method with articulating paper to design the occlusion, while the test group adopted a digital antagonist tool after cast scanning. The designed occlusal clearance was calculated by using digital casts of the designed crowns. Occlusal clearance of finished crowns on the definitive casts was evaluated with a silicone interocclusal record. During delivery, the crowns were scanned, and the occlusion was evaluated. Occlusal adjustment indicators were calculated. The independent-samples t test, Mann-Whitney U test, and Pearson chi-squared test were used to analyze the statistical differences (α=.05).

Results: Compared with the control group, the test group showed significantly lower mean ±standard deviation maximum occlusal adjustment distance (361.0 ±126.1 µm versus 451.5 ±179.3 µm, P=.037), but the root mean square (RMS) in the 2 groups was not significantly different (P=.121). The test group demonstrated significantly higher median (interquartile range) minimum designed occlusal clearance (72.4 [6.0] μm versus 26.1 [54.2] μm, P<.001) and lower median (interquartile range) RMS of occlusal clearance of finished crowns (116.2 [117.1] μm versus 227.3 [126.4] μm, P=.005) than the control group, both of which were closer to the design value (80 µm). Patient satisfaction before adjustment was significantly higher in the test group than in the control group (P=.005). Adjustment time and volume, lateral interference, and occlusal contact scores in the 2 groups were not significantly different (P>.05).

Conclusions: Compared with the waxing method, CAD occlusion for implant-supported single crowns reduced occlusal adjustment distance, controlled occlusal clearance closer to the design value, and improved initial patient satisfaction.

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.