Journal of prosthodontic research最新文献

Purpose: This review examined clinical and technological factors that influence implant placement accuracy in computer-assisted implant surgery (CAIS) systems.

Study selection: A systematic search of PubMed, Scopus, and Embase identified English-language studies published between January 2015 and January 2025. The eligible studies included randomized controlled trials, observational studies, systematic reviews, in vitro investigations, and case reports. Data extraction focused on the coronal, apical, and angular deviations. Methodological quality was appraised using the Oxford Centre for Evidence-Based Medicine (CEBM) framework and validated bias assessment tools.

Results: Fifty-three studies were included. Accuracy was influenced by patient-related factors (arch type, bone density, and edentulous span), surgical variables (flap design, operator experience, and guide protocol), and technological parameters (imaging modality, fiducial markers, and calibration). Static systems achieved high accuracy in dentate cases with stable guide support, but were less reliable in posterior or edentulous jaws. Dynamic navigation provided intraoperative flexibility and consistent performance across arches, although outcomes depended on calibration precision and operator learning curves. Robotic-assisted systems achieved the lowest mean deviations through trajectory control and haptic feedback, although evidence remains limited to early clinical and in vitro studies.

Conclusions: Although all CAIS systems achieve high accuracy, their performance varies according to the design of the system and clinical context. Static systems are effective when stabilization is ensured, while dynamic navigation offers adaptable accuracy across scenarios, and robotics exhibit the greatest consistency by reducing operator variability. Further multicenter randomized trials and standardized reporting are needed to strengthen the available evidence and guide clinical selection.

Purpose: Hard reline procedures are commonly used to improve denture fit; however, the long-term durability of reline materials remains unclear. This study evaluated time-dependent changes in the surface properties and biofilm adhesion of light- and auto-polymerizing hard reline materials following long-term immersion in artificial saliva. The findings may help determine optimal timing for clinical intervention and enhance prosthesis longevity.

Methods: Specimens of three materials-light-polymerizing reline, auto-polymerizing reline, and heat-polymerizing denture base polymethyl methacrylate-were immersed in artificial saliva for up to 180 days. Auto-polymerizing materials continue to polymerize over time, whereas light-polymerizing materials require light irradiation. The surface properties were evaluated based on Vickers hardness, surface roughness, color stability, contact angle, and Candida albicans (C. albicans) biofilm adhesion.

Results: After 180 days, the light-polymerizing material exhibited a significant increase in hardness (P < 0.001), whereas the auto-polymerizing material exhibited an increase from day 120 (P < 0.001). Contrastingly, the heat-polymerizing PMMA exhibited a significant decrease in hardness. The surface roughness increased nearly threefold for the auto-polymerizing material, indicating pronounced degradation. Color changes in the light-polymerizing material were weaker than those in the auto-polymerizing material at all time points except at 60 and 150 days. C. albicans adhesion increased significantly in the auto-polymerizing material (P = 0.034), whereas the light-polymerized material showed no significant change (P = 0.258).

Conclusions: Time-dependent changes in surface characteristics were observed in both reline materials. The light-polymerizing material superior stability throughout the immersion period compared with that of the auto-polymerizing material, indicating superior long-term performance.

Purpose: This study evaluated the wear behavior of dental materials for definitive fixed prostheses, including computer-aided design (CAD)- and manufacturing (CAM) composite resins, polyether-ether-ketone (PEEK), Ag-Pd-Au alloys, titanium, and zirconia, under standardized experimental conditions.

Methods: Three CAD-CAM-produced composite resins (HC, HCH, and CS), PEEK (SPE), Ag-Pd-Au alloys (CW), pure titanium class II (TJ), and zirconia (ZL) were tested. Two-body wear tests were conducted using an abrasion-testing machine under wet conditions using stainless-steel styluses as antagonists. Wear traces were examined using laser confocal scanning microscopy and scanning electron microscopy (SEM). Wear depths and heights were analyzed by one-way analysis of variance with Tukey's multiple comparison test.

Results: The wear depths of CS and TJ were significantly greater than those of the other materials (P < 0.05), whereas ZL exhibited the lowest wear depth. No significant differences were found among HC, HCH, SPE, and CW. The stylus opposing the SPE exhibited the smallest wear height, whereas TJ caused the most antagonist wear. SEM revealed distinct wear mechanisms, including adhesive and abrasive wear, depending on the material.

Conclusions: The SPE and CW showed similar wear behavior. CAD/CAM composite resins demonstrated variable wear rates, which was likely attributable to variations in the composition and morphology of the constituent fillers. The TJ exhibited excessive antagonist wear, suggesting the need for improved tribological properties. These findings provide guidance for selecting materials that preserve occlusion and prevent excessive wear.

Purpose: To assess the time efficiency of an innovative workflow (SafetyCrown) for implant-supported rehabilitation of posterior single-tooth sites against the standard workflow. The hypothesis was that there is no difference in treatment duration and accuracy, as represented by the number of clinical adjustments and additional visits required.

Methods: 31 participants (16 females, 15 males) were included in this analysis from a randomized clinical trial. Participants were randomly assigned to the test group (SafetyCrown workflow, three visits) or control group (conventional digital workflow, six visits). The SafetyCrown workflow combined immediate restoration with a prefabricated definitive abutment and chairside provisional restoration. The control group followed a conventional digital approach in six visits. Treatment times per visit were recorded with a stopwatch; clinical adjustments and additional visits were documented.

Results: The SafetyCrown workflow was completed in three visits in 53% of cases, with a mean of 3.5 visits compared with 6.1 visits in the control group. The total treatment time differed insignificantly by 10 minutes (test: 126.4 minutes; 95% CI: 116.4-136.5; control: 116.8 minutes; 95% CI: 104.4-129.3; P = 0.232), and individual visits lasted longer in the test group (e.g., surgical visit: 62 minutes vs. 33 minutes in control). Clinical adjustments were common in both groups when using model-free workflows.

Conclusions: Limitations aside, the SafetyCrown workflow reduced the total visits while maintaining the overall treatment time despite longer individual appointments, thus increasing efficiency. Both fully digital workflows were feasible, although frequent adjustments highlight the need to investigate sources of inaccuracy to improve the precision and efficiency further.

Purpose: This guideline aimed to make evidence-based clinical practice guidelines for the primary treatment of temporomandibular disorders (TMDs) for general practitioners who do not specialize in TMD.

Review process: Following the principles of evidence-based medicine, a systematic review and network meta-analysis (NMA) of multiple treatments was conducted, assessing the certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Randomized controlled trials published between January 2000 and December 2020 were included. Patients diagnosed with TMD according to the Diagnostic Criteria for Temporomandibular Disorders were considered. Myalgia, arthralgia, and maximal mouth opening were selected as outcomes, and 12 treatments were included in the NMA. The modified Delphi method was used to reach a consensus on recommendations during clinical guideline panel meetings of the Japanese Society for the Temporomandibular Joint.

Results: Self-administered mouth opening exercises, stabilization-type oral appliances, and low-level laser therapy (LLLT) were recognized as effective primary treatments, although the evidence level was graded as "very low" (Grade 2D). During the clinical guideline panel meetings, decisions were developed based on the NMA results, and recommendations for clinical practice guidelines were finalized following consensus.

Conclusions: This guideline recommends mouth opening exercises and the use of stabilization-type oral appliances as primary treatments for TMD. Additionally, it suggests that LLLT be a conditional recommendation, supplemented with additional considerations.

Purpose: This study evaluated the use of pre-sintered cobalt-chromium (Co-Cr) alloy discs in the fabrication of clasps for removable partial dentures, comparing their accuracy and mechanical properties, as determined via tensile testing, with those of conventional fabrication methods.

Methods: Accuracy of the clasps was assessed by obtaining three-dimensional (3D) data (design data) of the Akers clasp. The clasps were fabricated under three conditions: (1) pre-sintered, fabricated from pre-sintered Co-Cr alloy discs; (2) fully sintered, fabricated from fully sintered Co-Cr alloy discs; and (3) cast, fabricated via casting. For each method, 3D data were collected (fabrication data). The design and fabrication data were subsequently superimposed, and the accuracy of the clasps was investigated based on their inner surfaces. The mechanical properties were assessed via tensile testing of dumbbell-shaped Co-Cr alloy specimens fabricated under the same conditions used for accuracy testing (pre-sintered, fully sintered, and cast).

Results: Cast clasps typically exhibited the highest trueness values and fully sintered clasps exhibited the highest precision values. The pre-sintered clasps exhibited high trueness in every part of the rest area; however, the accuracy at the clasp tip was low. In terms of mechanical properties, the pre-sintered clasps exhibited the highest elongation, meeting the standards for Type 4 metals as specified by ISO 22674:2022.

Conclusions: The present study demonstrates that pre-sintered Co-Cr alloy discs are suitable for fabrication of clasps with good fit and mechanical properties, provided that the accuracy of the clasp tip is improved.

Purpose: The hyoid bone plays a key role in several physiological functions by interacting with the attached muscles. Understanding its kinematics and positional stability is essential for evaluating its functions: swallowing, mastication, intraoral transport, vocalization, and respiration. This study aimed to assess the position of the hyoid bone relative to the cranial base and mandible using cephalometric imaging and to examine its stability.

Methods: Cephalometric images of 140 patients were analyzed using specialized software. The positional relationship between the cranial base and hyoid bone was assessed by measuring the Porion-Hyoid distance (Po-Hy) and the angle between the Po-Hy and the Nasion-Porion line (∠CB-Hy). The relationship between the mandible and the hyoid bone and the cervical angle was also evaluated.

Results: The ∠CB-Hy showed a narrow distribution (mean ± SD: 89.2 ± 5.12°). A weak, but statistically significant, correlation was observed between age and the ∠CB-Hy. Additionally, a significant negative correlation was found between the number of missing molars and ∠CB-Hy, while a strong positive correlation was identified between the cervical angle and ∠CB-Hy. The relationship between the cervical angle and ∠CB-Hy was represented by the following linear regression equation: ∠CB-Hy = 0.484 × Cervical angle + 37.4.

Conclusions: Our findings suggest that the hyoid bone maintains a relatively stable position with respect to the cranial base with only slight variation. However, a significant relationship exists between ∠CB-Hy and cervical inclination. Clinicians and researchers should consider this relationship when assessing the hyoid position in clinical and research settings.