International Journal of Prosthodontics最新文献

Purpose: To compare the accuracy of occlusal stabilization appliances fabricated by digital workflows to those fabricated by conventional workflows.

Materials and methods: In total, 10 volunteers were recruited in this single-blinded crossover study. All volunteers received two types of occlusal stabilization appliances: a digital additively manufactured stabilization splint (DS) and a conventionally fabricated splint (CS). The accuracy was assessed using a 4-point rating scale addressing two aspects of the occlusal appliances: occlusal contact and basic performance. In addition, silicone impression materials were used to assess the gap between the appliance and the maxillary arch to ensure an accurate fit. Differences were quantitatively assessed with Mann-Whitney U test and independent-sample t test.

Results: The occlusal contact rating of DS (15.90 ± 1.73) was significantly higher than that of CS (14.10 ± 1.10, P < .05). The basic performance rating of DS (8.70 ± 0.48) was also significantly higher than that of CS (7.20 ± 0.92. P < .05). Quantitative evaluation of fit accuracy revealed a statistically significant difference (P < .05), with DS (636.29 ± 268.51 μm) being superior to CS (704.2 ± 306.05 μm).

Conclusion: The stabilization splints fabricated with a digital workflow showed better accuracy than the conventionally fabricated splints in terms of occlusal contact, basic performance, and fit accuracy. Because this is a pilot study, formal trials with a completely digital fabrication workflow will be conducted in the future.

Purpose: As the prevalence of failures of fixed prostheses have increased the need to assess the causes of failure of such prostheses have also increased to avoid all possible errors and thus achieving efficient treatment. This study was done to assess and survey clinically the failure rates of the fixed prosthesis according to the dental supported fixed prosthetic failure scale.

Materials and methods: A total of 156 patients were selected for the study who reported to the Department of fixed prosthodontics with complaints related to fixed dental prosthesis. Failure classification in prosthetic restorations was made with Manappallil's failure level scale. The SPSS program version 22 was used for statistical analysis. Relationships between categorical variables were determined by a Chi-square test.

Results: A total number of 253 failed fixed dental prostheses were evaluated. Majority of failures (39%) were found to be class 3 failure, which include unserviceable restorations. Porcelain fused to metal (PFM) prostheses showed more failure percentage (79%) than other types of prostheses. The results shows a statistically significant difference in the failure class of prosthesis according to prosthesis type, and its position in the dental arch.

Conclusion: Within the limitation of this survey, it was found that almost all of failed prostheses require replacement and the patients applied to the prosthodontics clinic when the rate of complications increased. Therefore proper patient selection, careful diagnosis, treatment planning, clinical and technical skills, and plane schedule of follow-up care must be kept in mind to provide successful treatment.

Clinical significance: By knowing the severity of the prosthodontics failures, we can provide a proper treatment plan so that the restoration will have a long time prognosis. Int J Prosthodont. 10.11607/ijp.8632.

Statement of problem: The assessment of bone loss around implants has been widely studied, but the effect of cantilever length as a risk factor is not fully understood.

Purpose: The objective of this randomized controlled clinical trial was to compare the peri-implant bone loss of mandibular complete-arch implant-supported fixed prosthesis supported (FPS) by 3 and 4 implants and to correlate with the size of the horizontal and vertical distal cantilever at prosthesis installation (T1) and after one year (T2).

Materials and methods: 72 external hexagon (EH) type implants were installed in 20 participants. Of these, 24 support FPS with 3 implants (GI3) and 48 with 4 implants (GI4). The inferior implants were named 1, 2, 3, and 4 according to their location in the mandibular arch, in a clockwise direction. Digital periapical radiographs were taken at times T1 and T2 for analysis and measurement of peri-implant bone loss. The horizontal and vertical distal cantilevers were measured with a digital caliper and correlated with peri-implant bone loss.

Results: The survival rate of implants in GI3 was 91.66%, in GI4 it was 97.91%. The mean bone loss in GI3 was 0.88 (± 0.89) mm and in GI4 it was 0.58 (± 0.78) mm (P = 0.225). There was no correlation between distal horizontal cantilevers and bone loss in the studied groups, with GI3 being -0.25 (P=0.197) and GI4-0.22 (0.129). Larger vertical cantilevers of implants 1 (P=0.018), 3 (P=0.015) and 4 (P=0.045) correlated with greater bone loss in GI4.

Conclusion: The number of implants in FPS did not influence peri-implant bone loss after 1 year of follow-up. Larger vertical cantilevers influenced greater bone loss in complete-arch implant-supported fixed prosthesis supported by 4 implants. Int J Prosthodont. 10.11607/ijp.8347.

Purpose: To compare the color dimensions, color discrepancies (ΔE00), and surface roughness of milled materials before and after the application of a bleaching agent.

Material and methods: A total of 10 extracted molars were obtained. Each tooth was cut in transversal sections, to create discs (3 mm thick, 10 mm diameter) (control group). Disk specimens of 8 materials were fabricated: polymethyl methacrylate (PMMA) interim material (PMMA-Telio group), 2 resin nanoceramics: (RNC-Ultimate group) and (RNC-Cerasmart group), 2 hybrid ceramics: (HC-Shofu group) and (HC-Enamic group), lithium disilicate (LD-Emax group), zirconia reinforced glass ceramic (ZGC-Suprinity group), and zirconia (Zr group) (n=10). Color measurements were obtained using a spectrophotometer before and after applying 35% hydrogen peroxide-based bleaching agent. Pre- and post-bleaching surface roughness analysis were completed using a profilometer.

Results: Significant L*, a*, b*, and ΔE00 values differences were found (P < .05). Color discrepancies (ΔE00) ranged from 0.30 ± 0.14 to 4.82 ± 0.10. The highest color discrepancies were measured on the PMMA-Telio group, while the lowest color discrepancies were computed on the ZGC-Suprinity, RNC-Ultimate, and RNC-Cerasmart. Significant surface roughness differences were found (P <.05). The largest increase of surface roughness values between the pre- and post-bleaching measurements was obtained in the PMMA-Telio group with a mean ΔSa value of 4.73 ± 3.02, while the largest decrease of surface roughness values between the pre- and post-bleaching measurements was obtained in the Zr-InCeram group with a mean ΔSa value of -1.58 ± 0.10.

Conclusions: The milled materials tested showed significant pre- and post-bleaching color and surface roughness discrepancies. Int J Prosthodont. doi: 10.11607/ijp.8359.

Purpose: To evaluate the influence of abutment material, cement thickness, and crown type on the esthetics of implant supported restorations.

Material and methods: Sixty specimens were prepared to represent 6 abutment groups; Group PA = Pink-anodized Ti, Group GA = Gold-anodized Ti, Group T = Non-anodized Ti, Group H = Hybrid (Ti + zirconia), Group P = PEEK (Ti + PEEK), and Group C = Composite resin, (control). Crown specimens (n = 120) were 2 obtained from Vita Enamic (VE) and Vita Suprinity (VS). Two cement thicknesses (0.1 and 0.2 mm) were used. The color values of crown configurations were measured and ΔE00* values were calculated. Statistical analyses were included Shapiro Wilk, 3-way ANOVA and Tukey HSD tests (P ≤ 0.05).

Results: Abutment (P < 0.001) and crown materials (P = 0.001) had a significant effect on ΔE00* values, while cement thickness did not. Groups PA and H resulted in significantly lower mean ΔE00* values than other abutments, whereas Group T revealed the highest. Unlike VS, cement thicknesses created a significant difference on the ΔE00* values for VE (P ≤ 0.05).

Conclusions: Pink-anodized Ti or hybrid abutments for VE and pink- or gold-anodized Ti for VS seem to be better options, in terms of color change. Cement thickness of 0.1 mm resulted in higher ΔE00* value than 0.2 mm for VE (P ≤£ 0.05). Int J Prosthodont. 10.11607/ijp.8564.

Purpose: Evaluating the distortion probability in impressions of completely dentate arches when different impression materials are used in relation to operator experience.

Material and methods: Twenty-eight students (group A) and 7 dentists (group B) performed 3 maxillary impressions on 28 students (participants), each using vinyl siloxane ether (VSE), polyether (PE), and irreversible hydrocolloid (IHC). Gypsum master casts were fabricated and subsequently digitized. Intraoral scans were taken as a control. Differences between master casts and intraoral scans were visualized by heatmaps and planar deviations were investigated. If planar deviations of >120 μm were found, the impression was rated as "distorted." An additional superimposition using the casts from VSE or PE was performed to confirm the presence of distortions. The relative number of surfaces with distortions in each impression was calculated. The procedure was repeated for a distortion threshold of 500 μm. The statistical analyses included measures ANOVA and post-hoc tests (a < 0.05).

Results: When 120 μm was considered as the threshold for distortions, IHC impressions showed higher distortion probability than PE impressions in group A (P = 0.003) and group B (P < 0.0001). In group B only, PE showed a lower distortion probability than VSE (P = 0.02). There was no difference between the study groups (P = 0.42). Considering 500 μm as a threshold for distortions, there was no difference between impression materials (P = 0.17) or study groups (P = 0.53).

Conclusion: There were no statistic significant differences in relation to operator experience. Different impression materials had a significant impact on distortion probability. Polyether impressions showed the lowest distortion probability. Int J Prosthodont. 10.11607/ijp.8555.

Purpose: This study was aimed at analyzing the effect of disinfectants on the roughness and mechanical properties of computer-aided design/computer-aided manufacturing (CAD/CAM) polymethylmethacrylate (PMMA) dentures.

Materials and methods: Two groups of denture base resins were tested: heat-polymerized and milled blocks. The specimens were shaped (n=80) for flexural strength (FS), flexural modulus (FM), and (n=240) for the properties of roughness (Ra) and microhardness alterations (KHN). They were categorized into the following groups based on immersion: control (deionized water), H1 (1% sodium hypochlorite), H05 (0.5% sodium hypochlorite), and C2 (2% chlorhexidine) groups. The immersion periods were 0 (T0), 130 (T1), and 260 (T2) cycles. Statistical analyses were performed for flexural properties using the three-way analysis of variance (ANOVA). Microhardness and surface roughness were analyzed using repeatedmeasures ANOVA. A significance level of 5% was set.

Results: CAD/CAM PMMA showed higher FS (P = .001) and FM (P < .001) than conventional PMMA. The KHN value was superior to the conventional PMMA (P < .001). The chemical solution affected the surface roughness of both resins (P = .007). The CAD/CAM PMMA block showed increased Ra values when H1 was used. Cycling separately increased the FS of conventional PMMA (T1 vs. baseline; P < .05). However, the FM of CAD/CAM PMMA was higher (T1 and T2 vs. baseline; P < .05). The time factor increased the microhardness of both resins (T2 vs. baseline; P < .05).

Conclusion: The CAD/CAM resin showed higher values compared to conventional PMMA in all tests, regardless of the chemical solution used; however, the values obtained for both resins were clinically acceptable. Int J Prosthodont 2023. doi: 10.11607/ijp.8301.

Purpose: To identify and map the scientific evidence regarding the factors that may influence the adaptation of complete edentulous to the mandibular complete denture.

Materials and methods: An electronic search strategy in the PubMed/MEDLINE, Web of Science, Scopus, Cochrane Library, and Virtual Health Library databases from 1945 to 2021, was conducted, according to the criteria established by PRISMA-ScR. Studies that addressed factors that influenced adaptation and acceptance to mandibular complete denture were included, such as socio-demographic and psychological aspects and patient-centered condition, and denturer-elated factors.

Results: The search yielded 9264 studies, of which 87 articles were considered eligible for full-text screening. Of this total, 23 were included for data extraction. Sociodemographic factors do not interfere with adaptation to a mandibular complete denture. Reports of complaints regarding pain and discomfort negatively impact the acceptance of complete dentures. Patients with a neuroticism personality have more difficulty accepting the complete dentures, being more predisposed to abandon them.

Conclusion: The psychological condition interferes with the predictability of treatment. Older and female patients, using first mandibular dentures, with resorbed ridges, and poor technical quality had more difficulty adapting to the complete dentures. However, these data must be interpreted with caution due to the variability of methodologies of the studies included in this review. Int J Prosthodont 2023. doi: 10.11607/ijp.7774.

Purpose: The aim of this clinical study was to determine the influence of partial edentulous distal extension and the use of removable partial dental prostheses in partially edentulous areas on the force exerted on the anterior teeth.

Materials and methods: Eighty-three volunteer patients participated in this study. The occlusal force was measured by using an occlusal force measuring sheet in the patient's mouth. The occlusal forces and ratios were compared with the Wilcoxon signed-rank test (p < 0.05).

Results: The force exerted on the anterior teeth increased significantly as the number of remaining teeth decreased in an edentulous distal extension. The force exerted on the anterior teeth decreased significantly with the use of a removable partial dental prosthesis.

Conclusion: When the number of remaining teeth decreases in a partial edentulous distal extension, the burden on the anterior teeth increases in a clinical setting. Our findings suggest that, for patients with partial edentulous distal extension, using a removable partial dental prosthesis is effective in preserving the residual anterior teeth by reducing excessive force. Int J Prosthodont 2023. doi: 10.11607/ijp.8281.

Purpose: To investigate the association between the oro-facial implant position distance (ID) and facial bone crest thickness (FBCT) in single-tooth implant crowns (STIC) placed in the esthetic zone, and predict presence of facial bone above the implant shoulder and its impact on Pink and White Esthetic Score (PES and WES) and patient related outcome measurements (PROMS).

Material and methods: In this cross-sectional study, all patients treated with STIC in esthetic zone between 2006 and 2013, with at least 12 months post-loading were invited to enroll. CBCTs were used to assess ID and FBCT. Esthetic outcomes included the PES and WES. PROMS measures included participants' satisfaction questionnaire with 13 formulated questions for this study. Descriptive statistics and ROC analysis were used. The association between ID, FBCT, esthetic outcomes and PROMS were calculated.

Results: Data was available for 60 implants. Mean ID was 2.02mm (SD=0.77). Mean FBCT at implant shoulder was 0.99mm (SD=0.98). FBCT was significantly associated with higher PES scores (P=0.040), but not with WES scores (P=0.149). FBCT was significantly associated with ID (P=0.009) and implants positioned ≥ 1.6mm palatal in relation to the adjacent teeth were likely to have higher FBCT.

Conclusions: FBCT influences PES and is more predictable if implants are positioned ≥ 1.6mm palatal in relation to the adjacent teeth. Int J Prosthodont 2023. Doi: 10.11607/ijp.8052.