European Journal of Prosthodontics and Restorative Dentistry最新文献

Introduction: Adjustments with diamond burs on the ceramic surface can affect its roughness and decrease flexural strength. This study evaluated the effect of polishing or glazing on the surface roughness and biaxial flexural strength of a zirconia-reinforced lithium silicate glass-ceramic upon adjustment with diamond burs.

Methods: Seventy disks were prepared according to ISO 6872 and divided into seven groups (n = 10) according to different adjustments and finishing processes. Surface roughness was measured prior to biaxial flexural strength testing. The topography was analyzed using an atomic force microscope , fracture markings were identified using a stereomicroscope and representative specimens were analyzed using scanning electron microscopy.

Results: The use of diamond burs significantly increased the surface roughness and decreased the strength of the evaluated ceramic (p⟨0.05). Polishing reduced the ceramic's roughness but resulted in flexural strength similar to that of the groups with wear (p⟩0.05). The glaze-treated specimens showed flexural strength statistically similar to the control group (p>0.05) but higher roughness, similar to those with wear.

Conclusions: Polishing reduced the surface roughness but did not affect the biaxial flexural strength of the ZLS ceramic. At the same time, the application of glaze after wear increased the strength.

Correct implant placement is necessary for satisfactory implant restoration. Therefore, the use of surgical guide is recommended. This study evaluated the accuracy of implant placement in posterior edentulous areas with different levels of tooth-support by novice clinicians according to fully-guided (FG), pilot-guided (PG), and freehand (FH) placement protocols. A mandibular model with missing first molars was designed. On one side, the model had a bound edentulous area (BEA), and on the other side, a free end edentulous area (FEA). Fourteen clinicians new to implant dentistry participated in the study, and each clinician inserted an implant in the BEA and FEA sites for every placement protocol. Angle, vertical and maximum horizontal platform and apex deviations were measured. The FG placement was more accurate than the PG and FH placements. This was significant for BEA angle deviation, BEA and FEA maximum horizontal platform deviations, and BEA maximum horizontal apex deviation. The PG placement was significantly more accurate than the FH placement for BEA and FEA maximum horizontal platform deviations. FG shows significantly greater angle, maximum horizontal platform and maximum horizontal apex deviations at FEA than BEA. This can be attributed to reduced guide support and the possibility of guide displacement during surgery.

This study evaluated the effect of the thickness and translucency of lithium disilicatebased glass ceramics on resin composite substrates on color change and masking effect. Laminate veneers were fabricated using IPS e.max CAD (A1) blocks with two different light transmittance values (High translucent [HT], Low translucent [LT]). Slices of two different thicknesses (0.3 mm, 0.5 mm) were obtained (n=10) and laminate veneers were cemented on the resin composite substrates of two different shades (A2, A3.5). The color change (ΔE values) was evaluated with the CIELab color system using a spectrophotometer, while the masking effect was calculated. The data were analyzed using independent-samples t-test and two-way analysis of variance. The ceramic thickness and translucency had a significant effect on final color and masking. When HT was used, and the laminate veneer thickness decreased (0.3 mm), the masking effect in ΔE values were lower (p⟨0.05). The ΔE values (⟩3.7) were clinically unacceptable. With the increase in thickness, translucency of porcelain laminate veneers decreases showing better color masking ability. Veneer thickness seems to be more effective on the restoration's masking ability than the shade of the substrate and translucency. Cinically, in case a 0.5-mm or thinner laminate veneer is planned, tooth color, resin cement and ceramic type should be considered.

To assess the clinical periodontal status of abutment teeth in regards of different design components of distal-extension removable partial dentures. Subjects (N=100) with acrylic or cobalt-chromium distal-extension removable partial dentures were enrolled and their periodontal parameters plaque and gingival indices [PI, GI], probing depths [PD], clinical attachment loss [CAL] and a mobility index [MI] evaluated. Denture base type, major connector, occlusal rests position, design of direct retainers, retention, stability and denture wearing habits were further evaluated. Acrylic RPDs were associated with higher mean±SE PI [1.70±0.74], GI [1.76±0.55], PD scores [2.47±1.02 mm] and CAL values [4.46±2.11 mm] compared to CO-CR RPDs [p⟨0.05]. For abutments, the PI [1.6±0.83], GI [1.72±0.57], PD [2.32±1.03] and CAL [4.26±2.08] were higher than their non-abutments counterparts [p⟨0.05]. CAL scores were found to be significantly higher for mandibular abutments compared to maxillary ones [P=0.002]. The highest PI [1.83±1.10] and GI [2.00±0.00] scores were associated with lingual bars and horse-shoe connectors, respectively. Full palatal coverage and lingual plates were associated with the highest PD [2.80±0.48] and CAL [4.70±0.37] scores. Acrylic RPDs, type of major connector, wrought wire clasps and distal occlusal rests may be considered as risk factors for periodontal disease progression in distal-extension removable partial denture wearers.

Purpose: This study evaluated the effect of coating traditional and translucent Y-TZP with an industrial nanometric colloidal silica or glaze before or after sintering on the adhesion of zirconia with various ytrria concentration.

Materials and methods: Specimens of Y-TZP with 3% and 5% yttria were subdivided into 5 groups (n=10), according to the coating applied and moment of application (before or after Y-TZP sintering): Control (no coating), Colloidal Silica/Sintering, Sintering/Colloidal Silica, Glaze/Sintering, Sintering/ Glaze. Lithium disilicate (LD) was used as positive control. Except for Y-TZP controls, groups were conditioned with silane before cementation with a self-adhesive resin cement. After 24 hours, the shear bond strength and failure analysis were performed. Also, analysis of specimens' surface was accomplished with SEM-EDX. Kruskal-Wallis and Dunn tests were applied to analyze differences between groups (p⟨0.05).

Results: Overall, the worst and best values of shear bond strength test were control and glaze after sintering groups. Different morphological and chemical aspects were observed in SEM-EDX analysis.

Conclusions: Coating Y-TZP with colloidal silica showed unsatisfactory results. In 3Y-TZP, the surface treatment associated with the best adhesion values was the application of glaze after zirconia sintering. However, in 5Y-TZP, glaze application can be performed before or after the zirconia sintering to optimize clinical steps.

Purpose: This clinical observational study aimed to determine the reproducibility of digital color measurement methods of different front teeth.

Methods: Color determination was performed using two spectrophotometric systems (Easyshade Advance; ES and Shadepilot; SP) and digital photography using a camera with ring flash and gray card with subsequent evaluation using computer software (DP; Adobe Photoshop). In 50 patients, at two time points, a digital color determination was performed on maxillary central incisors (MCI) and maxillary canines (MC) by a calibrated examiner. Outcome parameters were: color difference ΔE based on CIE L*a*b* values and VITA color match given by spectrophotometers.

Results: SP showed significantly lower median ΔE values (⟨1.2) than ES (⟨3.5) and DP (⟨4.4), while no significant differences were found between ES and DP. For all methods, both ΔE values and VITA color showed lower reliability regarding MC compared with MCI. The ΔE examination of subareas revealed significant differences in MCI for all devices and in MC only for SP. When comparing VITA color stability, SP showed a significantly higher color match than ES (81% and 57%, respectively).

Conclusions: Digital color determination methods tested in the current study provided reliable results. However, there are significant differences between the devices used and the teeth examined.

The chemomechanical cleaning of the root canal system is performed using manual and rotary files. This study aimed to compare the effect of ProTaper, Reciproc and HyFlex rotary files considering 2.5% sodium hypochlorite and 2% chlorhexidine (CHX) as irrigating solutions on apical extrusion of intracanal debris. Single-canal mandibular premolars (N=165) were evaluated. The teeth were divided into 6 experimental groups (N=25) for root canal instrumentation using 3 file systems, (Reciproc, HyFlex and ProTaper) and two irrigation solutions, namely 2.5% sodium hypochlorite or 2% CHX. Fifteen teeth were also assigned into three control groups (n=5) with saline as irrigation solution. Eppendorf tubes were weighed and the teeth were placed inside. The canals were instrumented and the tubes weighed to determine the dry weight of extruded debris. Data were analyzed using one-way ANOVA and Bonferroni test (α=0.05). The mean amount of extruded debris using the sodium hypochlorite solution was significantly higher than other irrigating solutions (p⟨0.001). The mean amount of extruded debris using the Reciproc file system was significantly higher compared to ProTaper and HyFlex (p⟨0.001). The use of the sodium hypochlorite solution, single-file systems and reciprocal movement are associated with higher debris extrusion and might be associated with higher risk of postoperative pain.

Introduction: Pit and fissure sealants are effective in preventing caries disease, however, they may present flaws that damage the physical barrier leading to treatment failure.

Objective: To answer the question ''Do pit and fissure sealants present good adhering to the dental structure when analyzed by their resistance to shear/microshear?".

Methods: This systematic review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) and was recorded in Open Science Framework. Embase, PubMed, SCOPUS, and Web of Science databases were used for the search strategy. The articles were selected according to the eligibility criteria. The risk of bias was performed with the adaptation of the quasi-experimental studies tool by Joanna Briggs Institute (JBI).

Results: 1245 studies were found in the databases when applying the search strategy, after removal of duplicates 881 were evaluated and 44 were selected. After applying the JBI tool, 30 studies presented low risk and 15 moderate risk of bias. Meta-analysis was not possible to performed due to the heterogeneity of the studies.

Conclusion: The adhesion is dependent on the application protocol, and among the protocols evaluated, conditioning with 37% phosphoric acid for 60 seconds and contamination of the substrate, as these can affect sealant adhesion.

Introduction and objectives: CAD/CAM prostheses may be produced in prosthetic laboratories or directly by practitioners. Quality of ceramic polishing procedures is a controversial topic and it would be interesting for practitioners working with CAD/CAM devices to determine which method is the most efficient regarding finishing and polishing. This systematic review aims to evaluate the impact of different finishing and polishing procedures on the surface of milled ceramics.

Materials and methods: A precise request was launched on the PubMed database. Studies included if they met the criteria of a specifically prepared PICO search. A first selection was performed by analysing titles and abstracts: the articles presenting a study conducted on non-CAD/CAM milled ceramics and research not containing comparisons of finishing procedures were not included. Roughness was evaluated in 15 articles. Nine papers recommended mechanical polishing over glazing regardless of the type of ceramic used. However, no significant differences were detected between the surface roughness of glazed and polished ceramics in nine other publications.

Conclusions: there is no scientific evidence demonstrating the superiority of hand polishing over glazing on CAD/CAM-milled ceramics.

Quantifying in edentulous patients the facial collapse and whether complete conventional denture (CCD) and implant-supported fixed complete denture (ISFCD) can restore the facial proportions to match those of a dentate patient (CG) is relevant for clinical dentists. One hundred and four participants were enrolled and divided into edentulous (n=56) and CG (n=48). The edentulous participants were rehabilitated with CCD (n=28) or ISFCD (n=28) in both arches. Anthropometric landmarks in the face were marked and captured by stereophotogrammetry. Linear, angular, and surface measurements were analyzed and compared among groups. The statistical analysis was performed by an independent t-test, the one-way ANOVA, and Tukey's test. The significance level was set at 0.05. The facial collapse was quantified as a significant shortening of the lower third of the face affecting facial aesthetics in all parameters evaluated and the same was observed in comparison among CCD, ISFCD, and CG. The CCD presented statistical differences with the CG group in the lower third of the face and labial surface, and the ISFCD showed no statistical differences with the CG and CCD. The facial collapse in edentulous patients could be restored through oral rehabilitation with an ISFCD similar to those of dentate patients.