The International journal of prosthodontics最新文献

Purpose: This study aimed to comparatively evaluate the manufacturing accuracy, marginal and internal fit of implant-supported permanent crowns fabricated using different brands of permanent hybrid ceramic resins via 3D printing. Additionally, these outcomes were compared with crowns produced from Vita-Enamic using the subtractive CAD/CAM technique.

Materials and methods: Six groups were formed, including five different 3D printing resins and Vita-Enamic. Crown accuracy was evaluated following ISO Standard 12836:2015. For accuracy measurements, root mean square values were calculated and recorded using Geomagic-DesignX software, based on methodologies described in the literature. Marginal and internal fit were assessed by measuring points on sectioned specimens under an optical microscope. Data were analyzed using SPSS version 22.0.

Results: The Saremco Crowntec showed (p<0,05) the highest internal and marginal fit (55,10 ± 9,433; 89,30 ± 20,966), while the Bego VarseoSmile TriniQ demonstrated the lowest marginal fit (141,70 ± 39,668) and external accuracy (92,90 ± 11,239). No significant difference was found between additive and subtractive groups in marginal fit and accuracy; the best internal fit (63,62 ± 13,352) was observed in additive groups, whereas Vita-Enamic showed (p<0,05) external accuracy (27,70 ± 6,961). Among production technologies, digital light processing exhibited (p<0,05) the lowest external accuracy (64,73 ± 25,209), with no significant difference between subtractive manufacturing and stereolithography (p>0,05).

Conclusions: Case-specific material choice is essential. Each material has distinct advantages and limitations. Additive resins may be preferred where retention and internal fit are critical, while subtractive materials are suitable when surface accuracy is prioritized.

Purpose: Artificial intelligence (AI) is transforming modern dentistry, particularly in prosthodontics. However, evidence regarding AI integration among dental professionals in Jordan remains limited, while insights into educational and clinical gaps affecting AI adoption remain unknown. Therefore, the objective of this study was to evaluate the knowledge, awareness, and perception of AI-driven prosthodontics among general dental practitioners and specialists in Jordan.

Material and methods: A cross-sectional design was chosen for this study using a self-administered questionnaire to evaluate knowledge, awareness, and perceptions of AI technologies in fixed and removable prosthodontics among dental practitioners in Jordan. Study participants were recruited using a convenience sampling technique. The study consisted of an anonymized questionnaire containing multiple choice, Likert scale and open- ended questions. The survey assessed demographic data, knowledge of AI applications, awareness of specific tools, and perceptions toward benefits, limitations, and ethical considerations of AI in prosthodontics. The association between the categorical variables was assessed using the chi-squared test of independence. The Spearman rank correlation test was used to assess the correlation between variables. A p-value of 0.05 was set as the level of significance.

Results: A total of 385 dental professionals participated in the survey (192 specialists in prosthetic dentistry and 193 general dental practitioners). Specialists reported higher awareness and use of AI in prosthodontics, including patient education, treatment planning, 3D implant positioning and quality control (P<0.001). Overall knowledge scores were moderate (78.72 ± 9.93), while general practitioners showed higher agreement for general diagnostic use (P<0.001).

Conclusions: In Jordan dental professionals have moderate knowledge of AI in prosthodontics, with younger clinicians and specialists showing higher awareness and comfort. The perception of AI is mostly positive. However, actual adoption in practice remains limited.

Conventional complete dentures prioritize efficiency but may fail to address underlying temporomandibular disorder (TMD) pathologies like undetected disc displacement and joint overload in edentulous patients. This case report described the application of a digital maxillary-mandibular repositioning technology for a TMD patient with temporomandibular joint noises. Utilizing three-dimensional deviation analysis and condylar position quantification, the digital workflow established physiologically optimized jaw relationship and occlusion. This approach not only reduced patient visits and chairside time but also successfully resolved TMD symptoms and restored masticatory function. At the 3-month follow-up, optimized stomatognathic coordination with even occlusal contacts and balanced functional occlusion further confirmed its high clinical value for complex edentulous rehabilitation.

Purpose: Zirconia complete-arch fixed complete dentures are increasingly favored for the rehabilitation of edentulous patients due to their mechanical strength and esthetic qualities. Nonetheless, concerns persist regarding the risk of fracture, particularly in cases where restorative space is limited. This in vitro study investigated the compressive fracture resistance of zirconia superstructures with different occlusal-cervical heights (2mm, 4mm, and 6mm) when bonded to rigid titanium frameworks with cantilever extensions.

Materials and methods: Thirty zirconia superstructures - Zirlux Transitions partially stabilized zirconia(35mm×10mm; heights: 2mm, 4mm, or 6mm) were bonded to standardized inverted T-shaped titanium frameworks (Grade 5, 35mm×10mm×6 mm) featuring a 10 mm cantilever. Each assembly was screw-retained on implant analogs and subjected to vertical load until failure using a universal testing machine (1 mm/min crosshead speed, 3mm hemispherical tip). Fracture characteristics were examined under 50× magnification. The study was limited to static vertical loading and did not assess fatigue or lateral forces.

Results: Mean fracture loads were 2809.45±78.43N (2mm), 2895.60±104.49N (4mm), and 2892.30±76.54N (6mm), with no statistically significant differences (p > 0.05). The most frequent failure involved fracture of the prosthetic screw distal to the loading point. Two specimens in the 2 mm group showed superficial cracks, but no zirconia fractures or framework deformation occurred in any group.

Conclusion: Zirconia superstructures with reduced height (2mm) demonstrated compressive strength comparable to thicker designs when supported by a rigid titanium framework. These findings support the potential clinical use of such restorations in space-limited scenarios. However, further studies involving fatigue and multidirectional loading are necessary to validate clinical relevance.

Purpose: Conventional impressions produce predictably more retentive upper complete dentures which can be incorporated into a hybrid workflow by digitising them. The study investigates trueness of digitised conventional impression for data acquisition and explore qualitative clinical limitations in the discussion. It evaluates 1) the discrepancies of digitised impression scans captured by intraoral (IOS-IMP) and desktop scanners (LAB-IMP) compared to digitised stone cast (LS-MOD), and 2) the discrepancy of the various anatomical landmarks (peripheral, ridge, postdam and palatal vault) within the two methods.

Materials and methods: Twenty conventional border-moulded impressions of maxillary edentulous ridges were digitised using intraoral and desktop scanners. The impressions were poured and casts digitised using a desktop scanner. The root-mean-square (RMS) difference was determined by superimposing the intraoral scan and the desktop scan onto the digitised master cast. Additionally, results of different landmarks were analysed.

Results: Paired t-tests, Wilcoxon tests, Kruskal-Wallis and post hoc tests were done. The mean RMS for overall LS-IMP (38.90 ±7.67 µm) was significantly different compared to the overall IOS-IMP (75.11 ±22.37 µm) (p-value <0.01). Within the desktop scanner group, deviations between peripheral and both palatal vault and postdam were significantly different.

Conclusion: Within the limitations of this in-vitro study, there are significant differences between the various landmarks areas when using a desktop scanner to digitise a master cast. However, digitising a master cast using desktop scanner is more accurate than an intraoral scanner.

Clinical significance: Digitising a conventional maxillary edentulous impression with desktop scanner is more accurate than an intraoral scanner, though both seem clinically acceptable.

Purpose: This in vitro study aimed to evaluate intaglio surface accuracy for directly fabricated removable denture bases using different light- and dual-polymerized materials.

Materials and methods: A standard edentulous mandibular model was scanned with an intraoral scanner to generate a reference model. Four dental materials were selected: a light-polymerized splinting resin, a dual-polymerized resin for denture base extension and repair, a functional denture relining material, and a light-polymerized acrylic resin for relining dentures (n=6 per material). A 3-dimensional (3D)-printed U-shaped negative template (2 mm thick) was filled with each material and directly adapted to the mandibular model. After polymerization, intaglio surfaces were scanned and superimposed onto the reference model. Trueness was assessed by comparison with the reference, and precision was evaluated by comparing scans within each material group. Mean absolute deviation (MAD) was calculated to quantify accuracy. Statistical analysis was performed using the Kruskal-Wallis test and Dunn post-hoc test with Bonferroni correction (α=.05).

Results: The light-polymerized splinting resin demonstrated the highest trueness and precision (lowest MAD: 0.114 ±0.019 mm and 0.113 ±0.021 mm, respectively). In contrast, the light-polymerized acrylic resin for relining dentures showed the lowest trueness and precision (highest MAD: 0.303 ±0.059 mm and 0.228 ±0.021 mm, respectively). These differences were statistically significant.

Conclusions: Direct fabrication of denture bases using light- and dual-polymerized resins achieved clinically acceptable accuracy in all four tested materials, supporting the feasibility of this approach for denture base fabrication.

Purpose: This systematic review introduces a novel classification of healing abutments- categorized as standard, anatomical, and customized-based on current clinical data. The primary objective is to evaluate their effects on peri-implant soft and hard tissues, while also summarizing their clinical indications, advantages, and limitations.

Materials and methods: A comprehensive search was conducted in PubMed (MEDLINE), Scopus, and Web of Science, using MeSH terms such as 'Dental Abutment,' 'Computer-Aided Design,' 'Dental Implant-Abutment Design,' and 'Wound Healing.' The search strategy followed the PICO framework. From 1961 initial records, 11 clinical studies met the inclusion criteria after relevance screening and duplicate removal. The risk of bias was evaluated using the Cochrane Collaboration tool for randomized studies and the ROBINS-I Version 2 tool for non-randomized investigations.

Results: The included studies consisted of six randomized controlled trials, two prospective cohort studies, and three retrospective observational studies. Standard healing abutments were associated with increased need for provisional restorations and greater marginal bone loss. Anatomical abutments showed improved soft tissue healing and reduced postoperative discomfort. Indirectly customized abutments supported aesthetic outcomes and reduced the need for surgical reentry. Directly fabricated customized abutments enhanced soft tissue stability and minimized gingival recession. Overall, anatomical and customized abutments outperformed standard designs.

Conclusions: Healing abutments with anatomical or customized features appear to promote better clinical outcomes by improving peri-implant tissue health and simplifying treatment protocols. Their use is particularly valuable in immediate implant placements, where achieving both aesthetic success and functional integration is essential.

Purpose: To evaluate the effect of modifying digital occlusal spacers on the marginal gap of full monolithic zirconia-reinforced lithium silicate (ZLS) crowns using a 4-axis machine.

Materials and methods: In total, 45 acrylic teeth with preparation for full crowns were divided into three groups with different occlusal digital spacers (60, 90, and 120 μm). All 45 abutments were scanned by an intraoral scanner (IOS), and a 4-axis machine grinded ZLS crowns. Each crown was cemented to the abutment using universal resin cement, and for each unit (crown and abutment) a scanning electronic microscope (SEM) was used to assess the marginal gap. For comparing the marginal gap between the three groups, Kolmogorov-Smirnov test was performed on the study variables and indicated a normal distribution (P > .05) followed by one-way ANOVA with post-hoc Bonferroni test (α = .05).

Results: The total mean marginal gap (TMMG) for the 120-µm (101.38 ± 17.94 µm) occlusal spacer was found to be significantly higher compared to the 90-µm (72.84 ± 27.21 µm) and 60-µm (60.16 ± 29.34 µm; P < .05) occlusal spacers. There was no significant difference between the 90-μm (72.84 ± 27.21 µm) and 60-μm (60.16 ± 29.34 µm) groups (P = .533).

Conclusions: A clinically acceptable marginal gap (< 120 µm) was obtained for all three occlusal spacers (60, 90, 120 µm), and as the digital occlusal spacer was reduced the marginal gap reduced as well. The 120-µm occlusal spacer showed a significantly higher marginal gap compared to 90 and 60 µm. The digital occlusal spacer that should be favorable for ZLS crowns is 60 µm.

Purpose: To assess the trueness and precision of various intraoral scanners (IOSs) in relation to endocrown restorations.

Materials and methods: One mandibular molar was mounted within an acrylic resin block. The tooth was prepared for an endocrown restoration, involving a 2-mm cusp reduction, a 3.5-mm pulp chamber depth, and a butt-joint margin. The sample was scanned by three different IOSs (3Shape TRIOS 4, Carestream 3800, and Medit i700), with 10 scans taken by each and then converted into STL files. A high-precision scanner captured a reference scan, which was also converted into an STL file. Trueness was assessed by superimposing each sample scan onto the reference, while precision was determined by superimposing the STL files within each group. Statistical analysis was performed using one-way ANOVA with Tukey HSD post hoc test and Mann-Whitney U test (α = .05).

Results: The study found that TRIOS 4 exhibited the highest trueness (22.44 ± 15.01 μm), followed by Medit i700 (24.59 ± 12.80 μm) and CS 3800 (29.05 ± 7.75 μm). In terms of precision, CS 3800 had the best results (21.55 ± 8.87 μm), followed by Medit i700 (43.80 ± 17.42 μm) and TRIOS 4 (47.28 ± 13.93 μm). Only the differences between the precision of the CS 3800 and the other two scanners were statistically significant.

Conclusions: The study found that all three scanners had similar trueness, but CS 3800 had significantly better precision than the other two scanners. However, all of the scanners demonstrated acceptable levels of accuracy in the context of endocrown preparation.

Purpose: To introduce a novel digital technique for analyzing the inclination of the tooth emergence profile and the distance between the bone crest (BC) and the cementoenamel junction (CEJ).

Materials and methods: The study used CBCT scans from 24 patients, analyzing 57 teeth for emergence profile inclination and 206 teeth for the BC-CEJ distance. Digital measures were taken using an implant planning software.

Results: The emergence profile angle varies according to the tooth anatomy. Results indicated an increase in emergence profile angle from an average value of 13 to 19 degrees when simulating prosthetic chamfer preparation, highlighting the importance of maintaining the natural tooth anatomy in restorative procedures. The average distances between BC and CEJ were 2.43 ± 1.08 mm on the buccal side, 1.96 ± 0.88 mm on the palatal side, 1.88 ± 1.05 mm on the mesial side, and 1.97 ± 0.92 mm on the distal side. Discrepancies in BC heights, particularly at the vestibular reference point, were found, which could affect periodontal health.

Conclusions: The research provides a foundation for future studies to refine soft tissue management techniques in dental practice. These findings underscore the need for a deeper understanding of supracrestal tissues in prosthetic rehabilitation, aiming to enhance the design of anatomical implant abutments and improve patient outcomes.