European Journal of Prosthodontics and Restorative Dentistry最新文献

The aim of this study was to evaluate the influence of flexible models on the marginal adaptation of indirect resin composite restorations. Thirty-six cavity preparations were made for class II restorations in permanent molar teeth. Three groups (n=12) were defined following three impressions/model material combinations: G(STONE), polyvinylsiloxane, and type IV stone model, as a control group; G(IMPRESSIONPVS), alginate and flexible polyvinylsiloxane; G(MODELPVS), alginate and flexible polyvinylsiloxane for models. All restorations were positioned on their respective teeth and evaluated by micro-computed tomography. Absolute marginal discrepancies were measured digitally (ImageJ). The results were compared using one-way ANOVA (p⟨ 0.05). The mean ± SD absolute marginal discrepancy of indirect resin composite restorations made from flexible and rigid stone models was as follows: G(STONE), 206 (±79.95) μm; G(IMPRESSIONPVS), 221.50 (±61.73) μm; G(MODELPVS), 203.25 (±65.93) μm. Absolute marginal discrepancies were not significantly influenced by the flexible and rigid stone models (p=0.78). The flexible or rigid stone model did not influence the marginal adaptation of the indirect resin composite restorations.

This study aimed to perform a systematic review and meta-analysis to analyze the results obtained clinically for bar-clip versus stud-retainers in overdentures. Three databases (PubMed Central, MEDLINE, and BvSalud) were used beyond a manual search. The study followed strictly the inclusion and exclusion criteria, considering the PICO strategy. For the risk of bias and quality assessment of studies, in the case of RCT, there were six domains of analysis, and for non-RCT studies, the Modified Newcastle-Ottawa Scale was performed. A meta-analysis was developed using the available data for marginal bone loss (MBL) and survival rate. 25 studies were included. The stud-retentor had the lowest implant SR (87.6%) and the greatest MBL (1.96 mm). For the bar-clip system, the mean survival rate was 95.91%, with only 4 studies included for this system, and the mean MBL was 1.13 mm. Only 3 studies directly compared both systems quantitatively, showing a significantly greater MBL toward the stud-retention group. The results may not allow determination of the best system for overdenture (stud retentor or bar-clip). Therefore, most of the studies suggested the stud-retentor as a more preferable system due to better distribution of forces, biological peri-implant behavior, low-cost, and ease for removal facilitating the sanitization and/or repair.

Objective: The aim of this in-vitro study was to compare the amount of material (post and luting agent) and root dentine removed using two methods for removal of endodontic posts.

Methods: Human premolar teeth (n=20) were sectioned at the CEJ and fibre reinforced posts were cemented at a length of 10mm following root canal therapy. Teeth were randomly assigned to two study groups. The methods of removal compared were: the use of RTD re-access kit (Composipost, RTD, France, St Egreve) in a conventional hand-piece driven by an electric motor (Group A); or a long tapered diamond bur (FG Diamond grit bur, Dentsply Ltd, UK) in an air-driven high speed turbine (Group B). Using micro- CT the volume of material and root dentine removed for each sample was calculated.

Results: Both the volume of material removed and the volume of root dentine removed were significantly greater when using diamond burs. (p⟨0.001). The volume of dentine removed using the diamond bur method (mean 22.64mm³) was greater than the volume removed using the reaccess kit (mean 11.71mm³).

Significance: Use of a diamond bur to remove fibre reinforced endodontic post removal poses higher risk for root perforation compared to the reaccess kit.

Purpose/aim: To determine the effect of translucency of four CAD/CAM materials and different curing modes on the degree of conversion of resin cements.

Materials and methods: Disks were fabricated from IPS e.max CAD, Vita Suprinity, Vita Enamic, and DD Cube X². Translucency was measured using a spectrophotometer. The degree of conversion of two resin cements Variolink Esthetic DC and LC were measured using a Fourier transform infrared spectrometer. For Esthetic DC, the degree of conversion was determined in self-cure and dual cure modes. ANOVA, Tukey HSD test, and /Linear Regression R2 were used to statistically analyze the data.

Results: There was a significant difference in the translucency of the four materials (P ⟨ 0.0001). The mean translucency of Vita Suprinity was significantly higher, followed by Vita Enamic, DD Cube X², and IPS E.max CAD. Degree of conversion of resin cements cured under DD Cube X² had the highest values (25.22%), whereas those cured under Vita Suprinity showed the lowest values (17.86%). The self-cure mode had the lowest degree of conversion values (16.22%) and dual cure mode showed the highest values (26.12%). A negative linear relationship was found between degree of conversion and translucency of the CAD/CAM materials.

Purpose: To compare the stresses induced on the supporting abutments by different secondary coping materials; zirconia, Polyetheretherketone (PEEK) and Polyetherketone ketone (PEKK) in tooth supported telescopic overdentures using strain gauge analysis.

Materials and methods: A virtual model simulating a completely edentulous mandibular arch with two telescopic overdenture abutments in the canine region was designed and printed. The abutments received a milled zirconia primary coping. The secondary coping was milled out of zirconia in the model ZR, PEEK in the model PE and PEKK in the model PK. Five overdentures were made for each model. Strain gauge rosettes were bonded mesial and distal to each abutment. Unilateral and bilateral loadings were applied. An ANOVA test was used for statistical analysis between the three models.(α=0.01).

Results: Significant differences were found between the three models during unilateral and bilateral loading. Post Hoc Tukey tests showed significant difference between ZR and PE models, ZR and PK models in addition to PE and PK models during unilateral and bilateral loading.

Conclusion: Zirconia copings induced the highest stress while the lowest stress values were induced by the PEKK copings.

Porcelains and glass-ceramics have been used to produce CAD-milled veneers and crowns for zirconia copings and implant-abutments. This study evaluated the bondstrength of a polymer-infiltrated-ceramic-network to zirconia using two adhesive cement systems: Panavia 21 and Multilink Automix. Lithium disilicate and feldspathic porcelain were also tested as reference CAD-On materials. Long beams (3x6x40 mm³) of zirconia and short beams (3x6x15 mm³) of the CAD-On materials were prepared. Zirconia and each CAD-On material were bonded in a crossbeam arrangement and subjected to a modified tensile bond-strength test. Half of the samples in each group (n=10) were tested 5 days after bonding (baseline) and the remaining (n=10) underwent aging (50,000 thermocycles at 5°C and 55°C) prior to bond-strength testing. The effects of material, cement, and aging on the tensile bond-strength were tested using a three-way ANOVA. The reference lithium disilicate/Multilink system showed no significant differences in bond strength compared to polymer-infiltrated-ceramic-network and porcelain. The long-term retention of polymer-infiltrated-ceramic-network was not statistically different compared to the baseline values and the two reference materials. With comparable bond strength between all materials, polymer-infiltrated-ceramic-network is the favorable choice for CAD-On to zirconia copings and implant-abutments due to its superior resistance to fatigue fracture relative to porcelain.

Objective: The aim of this study was to investigate the surface roughness of lithium disilicates (LS2s) polished using various polishing systems.

Materials and methods: Two types of LS2 (A, Amber Mill and E, IPS e.max CAD) were polished using LS2-specific polishing systems (L-Edenta, L-Jota), a zirconia-specific polishing system (Z-Jota), and a conventional ceramic polishing system (P-Shofu) (n = 8 per group). The compositions of different polishing systems were analyzed using EDS. Surface roughness was measured using confocal laser scanning microscopy and analyzed using EDS and SEM. ANOVA and Tukey's tests were used for the statistical analyses (p = 0.05).

Results: The polishing systems were mainly composed of C, O, and Si. The L-Jota group exhibited rougher surfaces than the other groups. Amber Mill exhibited higher surface roughness than IPS e.max CAD (p⟨0.001). Among the polishing systems, the L-Jota group presented the highest roughness value (pp⟨0.001). The surface roughness of the AL-Jota group was higher than that of the other groups.

Conclusions: A sufficiently smooth surface can be achieved without a LS2-specific polishing system. Further, the same polishing system can have different effects depending on the type of LS2.

Rehabilitation of a patient after hemi-mandibulectomy without reconstruction represents a prosthodontic challenge. Indeed, mandibular deviation and decreased occlusal contacts are a common presentation post-surgery. This paper reports on a patient who presented with these challenges and where chronic osteoradionecrosis has resulted in significant mandibular deviation. A maxillary cobalt chrome mandibular deviation device, designed with palatal bite plane and constructed using 3D printing methods, resulted in a successful outcome. The authors aim to show how restorative management of similar patients can be successful using a modern approach.

A systematic review of the literature was conducted to determine whether immediate dentine sealing (IDS) or delayed dentine sealing (DDS) would lead to a more effective bond between dentine and indirect glass ceramic restorations. Bonding effectiveness was determined by assessing bond strength or force to fracture from the selected studies. This report followed the PRISMA Statement. A total of 10 articles were subsequently identified for inclusion. In vitro studies evaluating bond strength or force to fracture of etchable glass ceramic restorations, following a bonding protocol that incorporates IDS and DDS were eligible to be selected. Analysis has shown IDS creates a more effective bond between dentine and glass ceramic restorations compared with DDS in 9 out of 10 of the studies assessed. Bond effectiveness was judged using three outcomes; microtensile bond strength (μTBS), shear bond strength (SBS) and force to fracture. IDS was shown to increase μTBS and force to fracture, in all seven studies that assessed these outcomes. IDS was also shown to positively affect the SBS in 3 of the 4 studies that assessed SBS. Further clinical trials are now required to understand the significance of IDS in a clinical environment.

The purpose of this in-vitro study was to compare trueness, 3D deviation, production time and costs of milled and 3D-printed resin single crowns. A total of 20 CAD-CAM resin single crowns were fabricated from 10 digital wax patterns designed on 10 tooth preparations available in a reference model. Standardized control linear measurements were performed with a CAD software. Each STL file was then used to fabricate two resins crowns - one milled and one 3D-printed. All crowns underwent physical linear measurements using a digital caliper. The crowns were then scanned using an intraoral scanner for assessing 3D deviation. Finally, time to produce a single crown, as well as costs and production rates of both methods were also compared. Both CAM methods did not present statistically significant differences in linear measurements, as compared to controls (P⟩.05). Furthermore, 3D-printed crowns had significantly greater deviations in cervical margins (P=.032) and occlusal surfaces (P=.041), as compared with milled crowns. Finally, 3D-printing took significantly longer to produce one single crown (P=.001), but with a cheaper and higher production rate than milling. These findings suggest that milling devices produce resin single crowns with smaller 3D deviations but more expensive costs, as compared with low-cost 3D printers.