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This study aimed to compare the 2-year clinical outcomes of polyetheretherketone (PEEK) and hybrid resin crowns placed on molars. Patients who received PEEK (P-Cr) and hybrid resin (H-Cr) crowns at Hiroshima University Hospital between 2016 and 2021 were evaluated in 2024 for crown conditions, including loss, fractures, and occlusal wear. No cases of crown debonding or fracture were observed in the P-Cr group. In contrast, the H-Cr group had 10 cases of loss and 4 cases of fractures. The P-Cr group demonstrated significantly fewer cases of crown debonding than the H-Cr group. Occlusal wear was observed in most crowns in the P-Cr group. Compared to the hybrid resin crowns, the PEEK crowns had a lower risk of fracture and debonding and retained long-term functionality; however, surface roughness and color changes were observed, suggesting that they may not be ideal for patients with particularly high esthetic demands. Nevertheless, physiological occlusal relationships and functionality were preserved, indicating that PEEK crowns could be a viable option for restoring molar defects.

ObjectivesIndirect CAD/CAM restorations can be fabricated using both subtractive and additive CAD/CAM technology. This study investigated the fracture load of crowns fabricated from three particle-filled composite CAD/CAM materials and one 3D-printed composite material.Materials and methodsLava Ultimate, Cerasmart and Brilliant Crios were used as particle-filled composite CAD/CAM material and els-3D Harz as 3D-printed composite material. For each group, crowns with three different material thicknesses (0.5/1.0/1.5 mm) were fabricated. Control group was composed of ceramic-based CAD/CAM materials e.max CAD and Enamic. Totally, n = 180 crowns were fabricated and adhesively seated on SLA fabricated dies. Thermomechanical loading and fracture testing were performed. The data for fracture loading force were statistically analyzed by two-way ANOVA followed with multiple comparisons by post hoc Tukey’s test (α = 0.05).ResultsIn contrast to ceramics, all particle-filled composite crowns with 0.5-mm thickness survived fatigue testing. Forces varied statistically significantly. Brilliant Crios showed highest maximum loading force with 1580.4 ± 521.0 N (1.5 mm). Two-way ANOVA indicated that both the material and the thickness affected the fracture load (p < 0.05).ConclusionsParticle-filled composite resin CAD/CAM materials may have advantageous material characteristics compared to ceramic CAD/CAM materials for minimal restoration thicknesses.Clinical relevanceComposite-based CAD/CAM materials may offer new possibilities in minimally invasive restorative treatment concepts.

The aim of this systematic review and meta-analysis was to evaluate the clinical performance of tooth-borne partial and full-coverage fixed dental prosthesis fabricated using hybrid polymer and ceramic CAD/CAM materials regarding their biologic, technical and esthetical outcomes. PICOS search strategy was applied using MEDLINE and were searched for RCTs and case control studies by two reviewers using MeSH Terms. Bias risk was evaluated using the Cochrane collaboration tool and Newcastle–Ottawa assessment scale. A meta-analysis was conducted to calculate the mean long-term survival difference of both materials at two different periods (≤24, ≥36 months(m)). Mean differences in biologic, technical and esthetical complications of partial vs. full crown reconstructions were analyzed using software package R (p < 0.05). 28 studies included in the systematic review and 25 studies in the meta-analysis. The overall survival rate was 99% (0.95–1.00, ≤24 m) and dropped to 95% (0.87–0.98, ≥36 m), while the overall success ratio was 88% (0.54–0.98; ≤24 m) vs. 77% (0.62–0.88; ≥36 m). No significance, neither for the follow-up time points, nor for biologic, technical and esthetical (88% vs. 77%; 90% vs. 74%; 96% vs. 95%) outcomes was overserved. A significance was found for the technical/clinical performance between full 93% (0.88–0.96) and partial 64% (0.34–0.86) crowns. The biologic success rate of partial crowns with 69% (0.42–0.87) was lower, but not significant compared to 91% (0.79–0.97) of full crowns. The esthetical success rate of partial crowns with 90% (0.65–0.98) was lower, but not significant compared to 99% (0.92–1.00) of full crowns.

A polymer-infiltrated ceramic network (PICN) material has recently been introduced for dental use and evidence is developing regarding the fit accuracy of such crowns with different preparation designs. The aim of this in vitro study was to evaluate the precision of fit of machined monolithic PICN single crowns in comparison to lithium disilicate crowns in terms of marginal gap, internal gap, and absolute marginal discrepancies. A secondary aim was to assess the effect of finish line configuration on the fit accuracy of crowns made from the two materials. Two master metal dies were used to create forty stone dies, with twenty each for the two finish lines, shoulder and chamfer. The stone dies were scanned to produce virtual models, on which ceramic crowns were designed and milled, with ten each for the four material–finish line combinations (n = 10). Marginal gaps and absolute marginal discrepancies were evaluated at six pre-determined margin locations, and the internal gap was measured at 60 designated points using a stereomicroscope-based digital image analysis system. The influence of the material and finish line on the marginal and internal adaptation of crowns was assessed by analyzing the data using two-way analysis of variance (ANOVA), non-parametric, and Bonferroni multiple comparison post-hoc tests (α = 0.05). ANOVA revealed that the differences in the marginal gaps and the absolute marginal discrepancies between the two materials were significant (p < 0.05), but that those the finish line effect and the interaction were not significant (p > 0.05). Using the Mann–Whitney U test, the differences in IG for ‘material’ and ‘finish line’ were not found to be significant (p > 0.05). In conclusion, the finish line configuration did not seem to affect the marginal and internal adaptation of PICN and lithium disilicate crowns. The marginal gap of PICN crowns was below the clinically acceptable threshold of 120 µm.

One of the trendiest areas in the world of materials research is multifunctional polymer nanocomposites. The long-term behaviour of fibre-reinforced polymer composites exposed to cryogenic environments is discussed in this article in light of current advancements. The composites were created using the standard hand layup procedure in order to achieve the aforementioned goals. Crown flower fibre (CF) serves as a reinforcement, while 3 wt.% of nano-SiO 2 and 3 wt.% of zinc borates (4ZnO·B 2 O 3 ·H 2 O) serve as fillers, and the LY566 type of epoxy resin with the HY 951 type of hardener were considered as a matrix system. To complete the mentioned objectives, three types of composites were fabricated: pure epoxy-based CF laminate, CF/3 wt.% of nano SiO 2 hybrid, and CF/3 wt.% of nano 4ZnO·B 2 O 3 ·H 2 O-based hybrid laminates. Analysis of the mechanical behaviour of composite materials that had been created was done under both normal and cryogenic circumstances at two distinct temperatures (−60 and 30 °C). To investigate the flammability properties of the hybrid composites, tests with horizontal and vertical flame retardants were conducted. X-ray diffraction and Fourier transform infrared spectroscopy studies were used to validate the nanofiller’s existence. The manufactured CF/3 wt.% of SiO 2 -based hybrid composites have good mechanical capabilities in a cryogenic environment of −60 °C, according to the results. This is because the 3 wt% SiO 2 -loaded samples are more resistant to deformation and can take more force before breaking at the impact zone because they have a larger surface area per volume fraction and better adhesion. In terms of flammability characteristics, the hybrid CF/ 3 wt.% of 4ZnO.B 2 O 3. H 2 O (zinc borate) exhibits better results (burning rate of 7.14 mm/min). The burning rate was reduced as a result of the use of nanofillers. This is due to zinc borate's promising flame-retardant qualities, which prevent flame spread and aid in flame extinguishment.

The purpose of this retrospective study was to assess the incidence of biologic and technical complications for implant-supported fixed complete dental prostheses (IFCDPs) and their relationship to oral health-related quality of life (OHQoL) and patient-reported outcomes. Metal-acrylic (MA), retrievable crown (RC), monolithic zirconia (MZ), and porcelain veneered zirconia (PVZ) prostheses were included. Patients who received an IFCDP at least 1 year prior to recall were identified. Exclusion criteria were: (1) an opposing complete denture and (2) time in service >70 months. A total of 37 patients with 49 prostheses, including 22 MA, 14 RC, 7 MZ, and 6 PVZ prostheses were recalled. Patient-reported outcomes were assessed via OHIP-49 (Oral Health Impact Profile) and a scripted interview with open-ended questions. All designs had high complication rates (12 of 22 MA, 10 of 14 RC, 2 of 7 MZ, and 5 of 6 PVZ). The most common complications were: (1) MA: posterior tooth wear, (2) RC: chipping and fracturing of the restorations, (3) MZ: wear of opposing restorations, and (4) PVZ: chipping of opposing restorations. Average OHIP-49 scores ranged from 7 to 29, indicating high OHQoL, patient satisfaction, regardless of prosthetic design ( P = .16). The standardized interview highlighted that although most patients were extremely satisfied (73%), some continued to be bothered by material bulk (14%) and felt that maintenance of oral hygiene was excessively time-consuming (16%). In the context of this study, despite high complication rates and maintenance needs, all IFCDP designs resulted in high OHQoL and patient satisfaction.

Background: The aesthetic goals of our patients in dentistry have become a major concern in today's world. Discoloured vital anterior teeth have long been treated with different approaches including crowns, direct and indirect veneers, composite resin, and most conservatively bleaching. The use of composite resins is increasing due to minimal tooth reduction and cost effectiveness as compared to ceramic veneers to achieve the optical properties of natural teeth. But very often in daily dental practice, tooth-coloured restorations already exist in the teeth that are planned to be bleached. Materials and Methodology: 40 disc shaped composite specimens (A2 shade) were fabricated measuring 10mm in diameter and 2mm in thickness using a stainless steel mould. The mould was placed on a mylar strip using a glass slab and overfilled with composite resin. Another mylar strip was placed on top of the mould and pressured with a glass slab to eliminate possible voids and remove excess material. The light-cured composite material used in the study was Gaenial GC A2 shade (GC Corporation, Japan). The composite resin was covered with acetate matrix strips and light cured. Specimens were light-cured for 9 seconds by a light-curing unit- (LCU) based on LED (Woodpecker, China). Following light-curing, the specimens were removed from the molds and placed at 37°C distilled water for 24 hours to assure complete polymerization. Elastomeric putty impression of the samples (10 per group) were taken in an impression tray and casts were poured. Composite of 0.5 mm thickness was placed over the cast surface which acted as a separator. Four vacuum forming trays were fabricated using vacuum forming machine for each group. Results: The variables used in this study were one restorative material with three bleaching agents and artificial saliva as the control group. Statistical analysis done using Analysis of variance (ANOVA) with 'p' value <0.05 showed that the results between all the groups was statistically insignificant. Conclusion: Among the bleaching agents, 9% hydrogen peroxide (ΔE=0.615) had the highest colour change when compared to 10% carbamide peroxide (ΔE=0.482) and sodium perborate (ΔE=0.425). However the results were statistically insignificant with the control group. Gaenial GC, a microfilled hybrid composite has better colour stability when exposed to 9% hydrogen peroxide, 10% carbamide peroxide and sodium perborate which is in the clinically acceptable range.