In-vitro evaluation of wear characteristics, microhardness and color stability of dental restorative CAD/CAM materials.

The aim of this study was to demonstrate the vertical and volumetric wear characteristics of CAD/CAM materials. The microhardness and color stability were evaluated. A polymer infiltrated ceramic network CAD/CAM block, resin nanoceramic CAD/CAM blocks, a resin composite, and enamel tissue were investigated. Samples were loaded in a chewing simulator. Other samples were aged and immersed in coffee. Color change was evaluated using the digital image analysis and a spectrophotometer. The data were analyzed using Kolmogorov-Smirnov, Kruskal Wallis, Mann Whitney U, Friedman, Spearman's rho tests (p<0.05). The lowest level of wear was obtained in enamel tissue group 0.20 (Q1:0.14; Q3:0.27µm). Resin composite group 2.48 (Q1:2.12; Q3:2.92) showed lower level of discoloration. No agreement was obtained between the digital image analysis and spectrophotometer data (Spearman's rho -0.314, p=0.014). Similar wear rate to the natural enamel tissue was obtained for Vita Enamic. Digital image analysis was considered a promising technique for monitoring the color change.

Assessment of Micro-Hardness, Degree of Conversion, and Flexural Strength for Single-Shade Universal Resin Composites.

Single-shade universal resin composites (SsURC) are preferred in clinical practice to reduce time for shade selection and obtain good esthetic results. In this study, the static mechanical properties of seven new SsURCs were investigated, their spectral analyzes were performed and scanning electron microscopy (SEM) evaluations were presented. Charisma Diamond One/DO, Admira Fusion x-tra/AFX, Omnichroma/OC, OptiShade/OS, Essentia Universal/EU, Zenchroma/ZC, Vittra APS Unique/VU were used in a three-point bending test to determine flexural strength (FS) and elastic modulus (EM); Vickers micro-hardness (VHN) and hardness-ratio (HR) were performed with a micro-hardness tester from top/bottom after 24-h/15-days of storage in distilled water at 37 °C (±1 °C). The degree of conversion (DC) was assessed by using Fourier transform infrared spectroscopy (FTIR). The structure of the resin matrix and filler content were assessed by SEM. Data were analyzed using IBM SPSS V23 and the R program and the significance level was taken as p < 0.05. The main effect of the tested SsURCs was found to be statistically significant on FS, EM, VHN, and DC values (p < 0.001). Bis-GMA free SsURCs (AFX, DO, VU) showed better DC and HR except for OC. All seven tested SsURCs conform to the requirements of ISO standards for dental resin composites for all tested categories.

Effect of Modeling Resins on Microhardness of Resin Composites.

OBJECTIVES: This study was aimed to determine the effects of modeling resins on the surface microhardness of composites. MATERIALS AND METHODS: Six resin-based composites (Charisma Smart, Estellite Asteria, CeramX-One SphereTEC, Admira Fusion, Filtek Ultimate, and Clearfil Majesty Es-2) and three wetting agents (Modeling Liquid, Composite Primer, and Modeling Resin) were investigated. In all, 240 specimens were prepared, and wetting agents were applied prior to light curing in the experimental groups. After 24 hours, specimens were polished and Vickers microhardness (VHN) values were measured. STATISTICAL ANALYSIS: Shapiro-Wilk and two-way analysis of variance (ANOVA) were used for analyses (p < 0.05). RESULTS: Both modeling resin and composites were determined to be effective factors (p < 0.001). The control group showed the highest VHN (70.37 ± 7.94), followed by Modeling Liquid (64.68 ± 12.07), Composite Primer (59.84 ± 6.33), and Modeling Resin (58 ± 3.52b; p < 0.001). Filtek Ultimate showed the highest VHN (76.62 ± 9.78c), whereas Charisma Smart (58.87 ± 7.95), and Clearfil Majesty (67.27 ± 2.58) showed the lowest (p < 0.001). Clearfil Majesty-Modeling Liquid (46.62 ± 5.33) and Charisma Smart-Composite Primer (50.81 ± 0.39) combinations showed the lowest VHN, whereas Filtek Ultimate-control (87.15 ± 2.12) and Filtek Ultimate-Modeling Liquid (84.24 ± 3.11) showed the highest (p < 0.001). CONCLUSION: All tested modeling resins decreased VHN value, and the amount of reduction varied among composites and wetting agents. It might be safer not to use wetting agents unless they are necessary.

Longevity of direct diastema closure and recontouring restorations with resin composites in maxillary anterior teeth: A 4-year clinical evaluation.

OBJECTIVES: To evaluate the clinical performance of resin composite restorations and to investigate causes of failure. MATERIALS AND METHODS: The longevity of 216 restorations in 53 patients (mean age, 33.3 years) was retrospectively evaluated according to Fédération Dentaire Internationale (FDI) criteria. Dental history and photographic data were used to evaluate diastema closure (n = 199) and recontouring (n = 19) restorations comprising microhybrid (Essentia Universal, GC Corp.), nanohybrid (Ceram.x One, Dentsply Sirona), and nanofilled (Estelite Asteria, Tokuyama Dental) composites. Data were analyzed with the Kaplan-Meier log-rank test, Cox regression analysis, Pearson chi-square test. p < 0.05 was considered statistically significant. The overall survival rate was 90.3 % and the mean survival duration was 46.2 months during the for 4 - year study period. The annual failure rate was 0.9 % - 3.4 %. Mean survival durations for diastema closure and recontouring restorations were 46.2 and 45.9 months, respectively (p = 0.328). Mean survival durations for Essentia Universal, Estelite Asteria, and Ceram.x One were 46.1, 46.7, and 45.7 months, respectively (p = 0.677). If we include failed restorations that were repaired and remained functional, the overall survival rate was 100 %. CONCLUSION: Longevity was similar among composites and restoration types. The long-term clinical performance of monochromatic anterior composite restorations was robust. Composite repair may be suitable for diastema closure and recontouring restorations. CLINICAL SIGNIFICANCE: There is a lack of long-term clinical evidence regarding the performance of direct anterior composite restorations. Monochromatic direct composite restorations may meet both the esthetic and functional expectations with even simpler restorative techniques. This 4 - year follow-up study evaluated the clinical performance of monochromatic anterior diastema closure and recontouring restorations with three different composite materials. The longevity of the restorations and the reasons for failure were investigated.

Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

OBJECTIVE: The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. MATERIAL AND METHODS: Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student's t-test. The failure modes of all groups were also evaluated. RESULTS: The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. CONCLUSION: The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.

Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin.

OBJECTIVE: The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. MATERIAL AND METHODS: Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student's t-test. The failure modes of all groups were also evaluated. RESULTS: The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. CONCLUSION: The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.

IPS Empress onlays luted with two dual-cured resin cements for endodontically treated teeth: a 3-year clinical evaluation.

The aim of this study was to evaluate the performance of IPS Empress ceramic onlays luted with two dual-cured adhesive resin cements for endodontically treated teeth. Twenty molar teeth were restored with all-ceramic restorations luted randomly with Maxcem or Clearfil Esthetic Cement and DC Bond Kit luting systems (n = 10 each) in 20 patients. The restorations were assessed using modified US Public Health Service criteria at baseline, 6 months, and 1, 2, and 3 years. A statistically significant deterioration was found for the criteria marginal integrity, anatomical form, and surface roughness. For luting of ceramic onlays, no difference between the two luting systems was detected.

Shear bond strength of composite bonded with three adhesives to Er,Cr:YSGG laser-prepared enamel.

OBJECTIVE: To assess in vitro the shear bond strength of a nanohybrid composite resin bonded with three adhesive systems to enamel surfaces prepared with acid and Er,Cr:YSGG laser etching. METHOD AND MATERIALS: Sixty extracted caries- and restoration-free human maxillary central incisors were used. The teeth were sectioned 2 mm below the cementoenamel junction. The crowns were embedded in autopolymerizing acrylic resin with the labial surfaces facing up. The labial surfaces were prepared with 0.5-mm reduction to receive composite veneers. Thirty specimens were etched with Er,Cr:YSGG laser. This group was also divided into three subgroups, and the following three bonding systems were then applied on the laser groups and the other three unlased groups: (1) 37% phosphoric acid etch + Bond 1 primer/adhesive (Pentron); (2) Nano-bond self-etch primer (Pentron) + Nano-bond adhesive (Pentron); and (3) all-in-one adhesive-single dose (Futurabond NR, Voco). All of the groups were restored with a nanohybrid composite resin (Smile, Pentron). Shear bond strength was measured with a Zwick universal test device with a knife-edge loading head. The data were analyzed with two-factor ANOVA. RESULTS: There were no significant differences in shear bond strength between self-etch primer + adhesive and all-in-one adhesive systems for nonetched and laser-etched enamel groups (P > .05). However, bond strength values for the laser-etched + Bond 1 primer/adhesive group (48.00 +/- 13.86 MPa) were significantly higher than the 37% phosphoric acid + Bond 1 primer/adhesive group (38.95 +/- 20.07 MPa) (P < .05). CONCLUSION: The Er,Cr:YSGG laser-powered hydrokinetic system etched the enamel surface more effectively than 37% phosphoric acid for subsequent attachment of composite material.

Tensile bond strength of dentin adhesives on acid- and laser-etched dentin surfaces.

OBJECTIVE: To evaluate tensile bond strengths of 2 dentin bonding agents containing solvents on Nd:YAG and Er,Cr:YSGG laser-etched dentin surface. METHOD AND MATERIALS: Occlusal enamel of 146 molars was removed, and exposed surfaces were ground with a diamond bur to produce bur-cut dentin surfaces. Of those teeth, 120 were assigned to 3 groups of 40 samples in which dentin was conditioned with Er,Cr:YSGG laser, Nd:YAG laser, and 37% orthophosphoric acid (control). Each group was further divided into 2 subgroups, acetone- and ethanol-containing bonding agents, and 4-mm-long x 4-mm-wide composite rods were bonded to all specimens using a Plexiglas mold. Tensile bond strength testing of 120 samples was performed at a crosshead speed of 0.5 mm/min using a 50-kgf load cell. The remaining 26 samples were examined under SEM to evaluate the adaptation/penetration of the bonding materials and the alterations in mineral content. Data were analyzed using 1-way ANOVA and Kruskal-Wallis tests; P < .05 was considered statistically significant. RESULTS: The difference between the mean tensile bond strength values obtained with bonding agents was statistically significant in the control group. The bond strength values of the acetone-containing agent in this group were found to be higher than the ethanol-containing agent (P < .001). When compared with Nd:YAG laser, bond strength values obtained with Er,Cr:YSGG laser were higher (P < .001). The bond strength values obtained in the acid-etched group were highest for both bonding agents and demonstrated statistical significance (P < .001). CONCLUSION: Although in this study laser etching is more influential than the solvent type on bond strengths of dentin bonding agents, it cannot be considered as an alternative to conventional acid etching.