Effect of hydrofluoric acid concentration and etching time on microtensile bond strength of suprinity and enamic CAD/CAM ceramics to resin cement

Introduction: The use of dental ceramics has increased due to their beauty and biocompatibility. The aim of this study was to evaluate the effect of hydrofluoric acid concentration and etching time on microtensile bond strength (μTBS) of the Enamic and Suprinity ceramics. Material & Methods: In this in vitro study, two hydrofluoric acid (HFA) concentrations of 5 (A) and 10 (B) were used at the time of 20, 60 and 120 seconds (s) on the Suprinity and  Enamic ceramics of CAD/CAM. The etched surfaces were impregnated with silane coupling agent as well as priming and Clearfil SE bond. Then, the Panavia F 2.0  resin cement was applied on the ceramic surfaces and light-cured. There were groups of EA20, EA60, EA120, EB20, EB60, EB120 for Vita Enamic and SA20, SA60, SA120, SB20, SB60, SB120 for Vita Suprinity. The μTBS between resin cement and porcelains was measured with universal testing machine. Mode of failure was observed under the stereo microscope at 40x magnification. Data were analyzed using ANOVA and Chi-square. Results: The μTBS was significantly different between EB20 and EB60 (p=0.008), EB120 and EB20 (p=0.005), SA120 and SB120 (p=0.013), EA120 and EB120 (p=0.002) as well as EA60 and EB60 (p=0.44). In both ceramics, different concentrations and etching times had significant effect on the mean of μTBS (p=0.016). In both ceramics, the time had no effect on the failure mode. For Suprinity ceramic, the HFA concentration had effect on the failure mode (P=0.028). Conclusion: The best surface treatment for Suprinity ceramic is 120 s with 5 HFA and for Enamic is 20 s with 10 HFA, which create the highest bond strength. &#160

Effect of hydrofluoric acid concentration and etching time on the surface roughness of CAD/CAM ceramics

Introduction: Dental ceramics are considered as materials that can restore the appearance of natural teeth. Etching the inner surface of a ceramic restoration with hydrofluoric acid (HF) followed by using a silane coupling agent is a well-known and recommended method to increase the bond strength. The aim of etching on ceramic structure is to enhance the surface roughness (Ra) and energy and to cleanse the bonding area. The aim of this study was to evaluate the effect of different HF concentrations and etching times on the Ra of IPS e.max CADTM and Vita mark IITM. Material & Methods: Two HF concentrations (5% and 10%) and three etching times (20, 60 and 120 seconds) were evaluated. Etched patterns were observed by scanning electron microscopy (SEM) and Ra was measured using atomic force microscopy (AFM). Surface element analysis was performed using energy dispersive X-ray spectroscopy (EDAX). Data were analyzed on SPSS 20 using ANOVA and T-test. Results: The Ra had no significant difference among various Vita mark IITM specimens (P=0.973). Among IPS e.maxTM specimens etched with 5% HF, the AFM results showed that 20-s etching time had the lowest Ra and among those etched with 10% HF and 120-s etching time had the most Ra. In IPS e.maxTM specimens etched with acid for 20 s, a significant difference was observed in Ra of 5% and 10% acid concentrations (5% HF lower than 10% HF) (p=0.012). Conclusion: Among IPS e.maxTM specimens etched with 5% and 10% HF, increasing the etching time lead to higher Ra. For both IPS e.maxTM and Vita mark IITM, 20-s etching with 5% HF provides acceptable Ra for the bond

Effect of concentration of hydrofluoric acid and etching time on microtensile bond strength of Zirconia-reinforced lithium silicate ceramics

Introduction: Etching the internal surface of ceramic restorations with hydrofluoric (HF) acid and silane is a well-accepted technique to enhance the bond strength. The aim of this study was to assess the effect of concentration of hydrofluoric acid and etching time on microtensile bond strength (µTBS) of zirconia-reinforced lithium silicate (ZLS) ceramics in 2021. Materials & Methods: This in vitro study was conducted on 8 Celtra-Duo ceramic blocks size 14 measuring 12×14×18 mm. Each ceramic block was divided into three equal pieces by a cutting machine to obtain a total of 24 specimens. The specimens were randomly divided into 6 groups for etching with 5% and 10% HF acid for 30, 60, and120 seconds. Silane (Clearfil porcelain activator) and bonding agent (Clearfil SE Bond) were applied to the etched specimens. Panavia F2 resin cement was applied on the surfaces and light-cured. The mTBS of resin cement to porcelain was measured by a universal testing machine. The mode of failure was determined under a stereomicroscope at x40 magnification. Data were analyzed by one- and two-way ANOVA (P<0.05). Results: The mean mTBS of Celtra-Duo ceramics subjected to etching for 30, 60, and 120 seconds was not significantly different in the use of 5% and 10% HF acid concentrations (P>0.05). Two-way ANOVA showed that the effects of HF acid concentration and etching time, and their interaction effect were not significant on µTBS of CAD/CAM Celtra-Duo ceramics (P>0.05). The mode of failure was dominantly adhesive in both concentrations of 5% and 10% HF acid. No mixed failure occurred in both concentrations. Conclusion: Considering the non-significant difference in µTBS of ceramics subjected to different concentrations of HF acid for different times, the application of HF acid with lower concentration for a shorter period is recommended to prevent possible adverse effects on ceramic strength

Effect of expiration date of universal adhesives on the alterations of microtensile bond strength of composite resin to dentin

Introduction: One of the factors affecting the success of bonded restoration is the use of appropriate adhesives and attention to their maintenance time. The aim of this study was to investigate the effect of three time periods related to the expiration date of two universal adhesives on the bond strength of resin composite to dentin. Materials & Methods: In this in-vitro study, 30 intact third human molars were selected. The roots of the teeth were cut and the crown part was mounted in acrylic resin in such a way that the enamel of the buccal surface was clearly visible. Using abrasive disks, the enamel of the buccal surface of the teeth was abraded to create a flat dentin area with dimensions of 25 mm2. The samples were randomly divided into 2 groups based on adhesive type (All Bond (Bisco, Fchaumburg,IL, USA) G-Permio and each group was divided into 3 subgroups based on expiration date. After the bonding process and fabrication of composite samples, microtensile bond strength (TBS) was measured at a speed of 1 mm/min. The data were analyzed using the Kruskal-Wallis test and post hoc Tukey's test. P<0.05 was considered as significant level. Results: Significant differences were found among samples with different expiration dates in both All-Bond Universal (p=0.0001) and G-Premio (p=0.0001) groups in terms of micro TBS (μTBS). In both adhesive groups, a significant difference was found between 2 months after expiration with expiration time and 2 months before expiration, but there was no significant difference between expiration time and 2 months before expiration. Conclusion: The end of the expiration date has a reducing effect on the μTBS of universal adhesives investigated in this study. However, the amount of this effect varies depending on the type of adhesive

Effect of hydrofluoric acid surface treatments on micro-shear bond strength of CAD/CAM ceramics

Introduction: Dental ceramics are appreciated as highly esthetic restorative materials that can simulate the appearance of natural dentition better than other materials. The aim of this study was to evaluate the effect of hydrofluoric acid concentration and etching time on micro-shear bond strength (µSBS) to IPS e.max CAD and Vita Mark II of a dual cured resin cement (Panavia F2.0). Methods: This study was an experimental in vitro study, performed in the dental material research center of Babol University of Medical Sciences in 2016. Two hydrofluoric acid concentrations (5% and 10%) and three different etching times (20, 60 and 120 seconds) were used to etch the specimens respectively. A silane coupling agent (Clearfil porcelain activator) and priming and bonding agent (Clearfil SE bond) were used on the etched surfaces in accordance to the manufacturer’s instructions of use. Then resin cement was applied on the prepared ceramic surfaces and light cured. µSBS between resin cement and the porcelains were measured with a universal testing machine. Mode of failure was observed with 40x magnification by means of a Stereo microscope. Data were analyzed with ANOVA and independent-samples t-test and Chi-square tests. Results: In both e.max and Vita Mark II groups, µSBS were not significantly different when different etching times (one-way ANOVA) and HF acid concentrations (Independent-samples t-test) were used (p>0.05), but the highest µSBS was shown in e.max specimens etched 60 s with 5% HF and Vita Mark II specimens etched 20 s with 10% HF. µSBS of e.max was significantly higher than Vita Mark II (p=0.00). Conclusion: Best surface treatment for e.max and Vita Mark II ceramics is 20 s etch using 5 % hydrofluoric acid