The Influence of Different Surface Cleansing Agents on Shear Bond Strength of Contaminated Lithium Disilicate Ceramic: An In Vitro Study

Effect of Combined Application of Hydrofluoric and Phosphoric Acids and Active Irrigation with a Microbrush on Shear Bond Strength of Lithium Disilicate Ceramics to Enamel

Background

This study assessed the effect of combined application of hydrofluoric (HF) acid and phosphoric acid (PA) and active irrigation (AI) with a microbrush on shear bond strength (SBS) of lithium disilicate (LDS) ceramics to enamel.

Materials and Methods

This in vitro study was conducted on 40 extracted teeth that received enamel preparation with a #12 cylindrical bur. Forty IPS e.max LT rods (3mm diameter, 6mm height) were fabricated and randomly assigned to four groups (n = 10) for surface treatment with 5% HF (group 1), 5% HF and AI with a microbrush for 20 seconds (group 2), 5% HF and 32% PA (group 3), and 5% HF and 32% PA plus AI with a microbrush for 20 seconds (group 4). Silane and Choice 2 cement were used for bonding rods to enamel. The SBS was measured by a universal testing machine. Data were analyzed by two-way analysis of variance (ANOVA), Bonferroni, and Chi-square tests (alpha = 0.05).

Results

Group 4 had the highest SBS, and group 1 had the lowest SBS (P < 0.05). Group 2 had a significantly higher SBS than group 1, and group 4 had a significantly higher SBS than group 3. AI with a microbrush significantly increased the SBS (P < 0.05), but the application of PA caused no significant change in SBS (P > 0.05). The interaction effect of PA and AI on SBS was not significant (P > 0.05).

Conclusion

The application of PA in addition to 5% HF acid caused no significant change in the SBS of LDS ceramic to enamel. However, AI with a microbrush significantly increased the SBS.

Assessment of physical/mechanical properties and cytotoxicity of dual-cured resin cements containing Sr-bioactive glass nanoparticles and calcium phosphate

The aim was to develop dual-cured resin cements containing Sr-bioactive glass nanoparticles (Sr-BGNPs; 5 or 10 wt%) and monocalcium phosphate monohydrate (MCPM; 3 or 6 wt%). Effects of additives on degree of monomer conversion (DC), biaxial flexural strength/modulus, shear bond strength (SBS), mass/volume change, color stability, ion release, and cytotoxicity were examined. Controls included material without reactive fillers and Panavia SA Plus (PV). Experimental cements showed higher DC than PV regardless of light activation (p<0.05). Mean SBS and color stability were comparable between experimental cements and PV. Cell viability upon the exposure to sample extracts of experimental cements was 80%-92%. High additive concentrations led to lower strength and modulus than PV (p<0.05). The additives increased mass change, reduced color stability, and promoted ion release. The experimental resin cements demonstrated acceptable mechanical/chemical properties and cytotoxicity. The additives reduced the strength but provided ion release, a desirable action to prevent recurrent caries.

Comparison of bond strength to three restorative materials after contamination and the use of two cleaning agents

STATEMENT OF PROBLEM

Scientific data on the decontamination effectiveness of a newly introduced cleaning agent are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate and compare the tensile bond strength (TBS) of 3 different restorative bonding surfaces after contamination with saliva following different cleaning protocols.

MATERIAL AND METHODS

A total of 192 disk specimens were made out of 3 materials (n=64); Katana Avencia (A), Katana Zirconia (Z), and e.max CAD (L). The bonding surfaces of all disks were polished, steam cleaned, and then pretreated by following the recommended protocol for each material. The specimens of each group were divided into 4 subgroups (n=16). The first subgroup served as the reference (R), where no contamination was applied. The 3 other subgroups were contaminated with saliva and subsequently rinsed with water for 20 seconds and dried with oil- and water-free air spray. They were then either not treated with any cleaning method (0), cleaned with Katana Cleaner (K), or cleaned with Ivoclean (I). The bonding surfaces of the specimens were perpendicularly luted to plexiglass tubes filled with dual-polymerizing composite resin (Clearfil DC Core) with resin cement (Panavia V5) after the recommended surface conditioning. Each subgroup was further subdivided into 2 groups: stored in 37 °C water for 3 days or subjected to thermal-cyclic loading for 150 days with 37 500 thermal cycles (7500 per month), temperature 5 to 55 °C, and dwell time of 30 seconds. All specimens were subjected to TBS testing in a universal testing machine. Three-way ANOVA was applied. A significant interaction (P<.01) was detected between the 3 different variables (material, treatment, aging). After significant interactions had been revealed by 3-way ANOVA, additional statistical analysis was performed by using separate 2-way ANOVAs, then separate 1-way ANOVAs followed by the Tukey-HSD test for post hoc pairwise comparisons among groups (α=.05 for all tests). All specimens underwent failure mode analysis after TBS testing RESULTS: All specimens survived the storage with thermocycling except for group Z-0, where all specimens debonded during thermocycling. The mean ±standard deviation TBS values ranged from 18.3 ±5.3 MPa to 34.0 ±5.4 MPa after 3 days and from 6.7 ±5.5 MPa to 26.9 ±5.4 MPa after 150 days.

CONCLUSIONS

Contaminated groups that did not receive any cleaning had significantly lower TBS. Thermocycling had a negative effect on the TBS but was not statistically significant for all groups. Using the same cleaning method, the restorative material did had a significant effect on the TBS after 150 days.

Decontamination of lithium disilicate ceramics using various photosensitizers, herbal and chemical disinfectants, and the effect of surface conditioners on bond strength values

AIM

To assess and compare the antimicrobial efficacy of disinfectants on lithium disilicate ceramic (LDC) used in dental applications and shear bond strength (SBS) of LDC after using different conditioners hydrofluoric acid (HF), self-etching ceramic primers (SECP) and Neodymium-doped yttrium orthovanadate (Nd: YVO4).

MATERIALS AND METHODS

One hundred and twenty LDC discs were fabricated by auto-polymerizing acrylic resin using the lost wax technique. S. aureus, S. mutans, and C. albican were inoculated on thirty discs (n=30 each). Each group was further divided into three subgroups based on different disinfecting agents used (n=30) Group 1: Garlic extract, Group 2: Rose Bengal (RB) activated by PDT, and Group 3: Sodium hypochlorite (NaOCl). An assessment of the survival rate of microorganisms was performed. The remaining thirty samples were surface treated using three different LDC surface conditioners (n=10) Group 1: HF + Silane (S), group 2: SECP, and Group 3: Nd: YVO4 laser+S. SBS and failure mode analysis were performed using a universal testing machine and stereomicroscope at 40x magnification, The statistical analysis was conducted using one-way ANOVA and Post Hoc Tukey test.

RESULTS

Garlic extract, RB, and 2% NaOCl sample displayed comparable outcomes of antimicrobial potency against C. albicans, S aureus, and S. mutans (p>0.05). Furthermore, SBS analysis showed HF+S, SECP, and Nd: YVO4+S exhibited comparable outcomes of bond strength (p>0.05).

CONCLUSION

Garlic extract and Rose bengal activated by PDT can be contemplated as alternatives to the chemical agent NaOCl used for LDC disinfection. Similarly, SECP and Nd: YVO4 possess the potential to be used for the surface conditioning of LDC to improve the bond integrity with resin cement.

Retentive Strength of CAD/CAM-Fabricated All-Ceramic Crowns Luted on Titanium Implant Abutments Using Different Ceramic Materials and Luting Agents: An In Vitro Study

Objectives: This study aimed to determine the retentive strength of monolithic hybrid-all-ceramic crowns luted on titanium implant abutments. Material and Methods: In total, 450 crowns (75 each of Mark II, Empress CAD, e.max CAD, Suprinity, Enamic, Celtra Duo) were milled using a CAD/CAM system. The crowns were cemented onto sandblasted titanium implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, Fujicem, and Panavia 2.0). After thermocycling was performed (5000 cycles: 5−55 °C, 30-s dwell time), the crowns were removed using a universal testing machine. The location of luting-agent residue on the abutment and inner crown surfaces was evaluated. Analyses of variance (ANOVA) with the Bonferroni correction were performed to evaluate differences of retentive strength depending on the crown material and the kind of the luting agent. Results: The retentive strengths for the different ceramic materials were Vita Mark II: 652N-759N (SD:134N-146N), Empress CAD: 681N-822N (SD: 89N-146N), e.max CAD: 784N-1044N (SD: 109N-176N), Vita Enamic: 716N-1177N (SD: 132N-220N), Vita Suprinity: 867N-1488N (SD: 202N-278N), and Celtra Duo 772N-1335N (SD:151N-229N). After the removal trials, the visual documentation showed different adhesive residue location depending on the ceramic materials. Furthermore, the pull-off force was dependent on the choice of adhesives. No significant differences were found between different luting agents and the ceramic material Vita Mark II and Empress CAD. EmaxCAD showed significant differences with Unicem and FujiCem compared to Panavia, as did VitaSuprinity, VitaEnamic, and Celtra Duo (p < 0.001). Conclusions: The ceramic material used seems to influence the retentive strength and the use of certain luting agents results in a higher retentive strength for some ceramic materials.