Durability of bond between an indirect composite veneering material and zirconium dioxide ceramics.

OBJECTIVE: The purpose of the present study was to evaluate the durability of bond strength between an indirect composite material and zirconia ceramics after thermocycling (100 000 cycles) and to assess the effect of various priming agents for zirconia surface treatments. MATERIALS AND METHODS: A CAD/CAM system (Katana, Noritake Dental Supply) was used to fabricate 96 zirconia disks as a bonding substrate. The specimens were randomly divided into six groups (n = 16) and treated with one of the following acidic priming agents: Alloy Primer (ALP, Kuraray), Clearfil Ceramic Primer (CCP, Kuraray), Clearfil Photo Bond (CPB, Kuraray), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB + Activator, Kuraray), Estenia Opaque Primer (EOP, Kuraray) and Porcelain Liner M Liquid A (PLA, Sun Medical). The specimens were bonded with an indirect composite material (Estenia C&B Dentin, Kuraray). Shear bond strengths were tested before and after 100 000 thermocycles and the data were analyzed by using the Steel-Dwass test and Mann-Whitney U-test. RESULTS: After 100 000 thermocycles, the PLA group showed the lowest bond strength (p = 0.010), whereas the CPB + Activator (23.9 MPa; p < 0.014) and CPB (22.7 MPa; p < 0.028) groups had significantly higher bond strengths than the other groups. The Mann-Whitney U-test revealed that bond strengths did not significantly decrease after thermocycling, except for specimens in the PLA (p = 0.038) and CCP (p = 0.028) groups. CONCLUSIONS: Application of a combination of hydrophobic phosphate monomer (MDP) and initiator results in a durable long-term bond between Katana zirconia and Estenia C&B composite material.

Influence of convergence angle and cement space on adaptation of zirconium dioxide ceramic copings.

OBJECTIVE: The purpose of the present study was to evaluate the influence of total convergence angle and cement space on internal and marginal adaptation of posterior zirconium dioxide (zirconia) ceramic copings. MATERIAL AND METHODS: Seventy-two standardized mandibular first molar zirconia copings were fabricated with nine parameters: three different total convergence angles (6 degrees , 12 degrees , and 20 degrees ) with three different computer-fixed cement spaces (10, 30, and 60 microm). Marginal adaptation was assessed to measure vertical discrepancy between the coping and abutment by direct viewing. Internal adaptation was evaluated using the cement replica technique with a laser microscope. The Kruskal-Wallis test and Wilcoxon rank-sum test were performed to test for differences in internal space and marginal discrepancy values (alpha=0.05). RESULTS: The median of mean internal spaces/marginal discrepancies ranged from 54.0/27.4 to 128.1/77.8 microm. Statistically significant differences in the internal spaces were found between groups with 6 degrees and 20 degrees convergence angle, regardless of cement space. The different cement spaces did not have any significant influence on the 12 degrees and 20 degrees convergence angle groups. The 60-microm cement space group exhibited statistically smaller marginal discrepancies than the 10-microm cement space group in all the different convergence angles. CONCLUSIONS: Within the limitations of the present study, the internal spaces of zirconia ceramic copings may decrease as the convergence angles of abutments increase. The computer-fixed cement space might influence the marginal adaptation of zirconia ceramic copings. The internal and marginal adaptation of zirconia ceramic copings obtained was within the range of clinical acceptance.

Marginal and internal adaptation of zirconium dioxide ceramic copings and crowns with different finish line designs.

The present study evaluated the marginal and internal adaptation of single-tooth zirconium dioxide (ZrO2) ceramic copings or crowns with three different finish line designs. Twenty-four steel dies were prepared for maxillary central incisor crowns with the following finish line designs: shoulder (S), rounded shoulder (RS), and chamfer (C) preparations. Twenty-four standardized ZrO2 ceramic copings were manufactured with a CAD/CAM system (Cercon Smart Ceramics), and the crowns were finalized by veneering with a feldspathic ceramic. Measurements for marginal and internal adaptation were performed at two stages: the copings and the completed crowns. No significant differences were observed between the three groups in terms of marginal discrepancy median value: S, 73/69; RS, 61/60; C, 64/55 (microm). However, significant differences in internal adaptation were widely found among all groups: S, 117/111; RS, 72/75; C, 56/57 (microm). As for intra-group comparisons of marginal and internal adaptation values for all groups, the differences were not significant. It was found that the finish line design seemingly wielded no influence on marginal adaptation of single-tooth ZrO2 ceramic copings and crowns. It was also observed that the marginal and internal adaptation values in the present study were all within the clinically acceptable range.

Effect of cooling rate on shear bond strength of veneering porcelain to a zirconia ceramic material.

The purpose of the present study was to evaluate the effect of cooling rates after firing procedures of veneering porcelain on shear bond strength between veneering porcelain and a zirconium dioxide (zirconia; ZrO2) ceramic material. A total of 48 ZrO2 disks were divided equally into three groups. Two veneering porcelains that are recommended for ZrO2 material - Cerabien ZR (CZR), IPS e.max Ceram (EMX) - and one that is recommended for metal ceramics - Super Porcelain AAA (AAA) were assessed. Each group was then further divided into two subgroups (n = 8) according to cooling time (0 or 4 min) after porcelain firing. Specimens were fabricated by veneering the porcelain on the ZrO2 disks, after which shear bond testing was conducted. Bond strength differed significantly by cooling time in ZrO2-AAA (P < 0.001) and ZrO2-EMX (P = 0.001) specimens. There was no significant difference in shear bond strength with respect to cooling time in ZrO2-CZR specimens (P = 0.382). The duration of cooling from firing temperature to room temperature may affect the shear bond strength of veneering porcelain to a zirconia material depending on porcelain material used.

Shear bond strength between an indirect composite veneering material and zirconia ceramics after thermocycling.

The present study evaluated the shear bond strength between an indirect composite material and zirconium dioxide (zirconia) ceramics after thermocycling. A total of 80 zirconia (Katana) discs were divided into five groups and primed with one of following agents: All Bond 2 Primer B (ABB), Alloy Primer (ALP), AZ Primer (AZP), Estenia Opaque Primer (EOP), and Porcelain Liner M Liquid A (PLA). An indirect composite material (Estenia C&B) was then bonded to the primed zirconia. One-half of the specimens (n = 8) in each group were stored in distilled water at 37 degrees C for 24 h, and the remaining eight specimens were thermocycled 5,000 times before shear bond strength testing. Mean bond strengths before thermocycling varied from 10.1 to 15.6 MPa; bond strengths after thermocycling ranged from 4.3 to 17.6 MPa. The ALP group had the highest strengths after thermocycling; there were no significant differences among the PLA, AZP, and EOP groups. The bond strength values for PLA, AZP, EOP, and ALP did not decrease with thermocycling. The application of an acidic functional monomer containing carboxylic anhydride (4-META), phosphonic acid (6-MHPA), or phosphate monomer (MDP) provided durable bond strength between Estenia C&B indirect composite and Katana zirconia.

Influence of priming agents on the short-term bond strength of an indirect composite veneering material to zirconium dioxide ceramic.

OBJECTIVE: Indirect composites are promising alternatives as veneering materials for zirconium dioxide (zirconia) ceramic frameworks. This study evaluated the effects of priming agents and a high-flow bonding agent on the short-term bond of an indirect composite material to a zirconia framework material. METHOD AND MATERIALS: Indirect composite (Estenia C and B) was bonded to particle-abraded zirconia samples (Katana, n = 144) using no (control) or 1 of 8 priming agents: All Bond 2 Primer B (ABB), Alloy Primer (ALP), Clearfil Ceramic Primer (CCP), Clearfil Photo Bond (CPB), Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Activator), Estenia Opaque Primer (EOP), Porcelain Liner M Liquid A (PLA), and V-Primer (VPR) with or without a high-flow bonding agent (Estenia C and B Opaque). Shear bond strength was tested after 24-hour wet storage. Data were analyzed with Levene test for equality of variance, Dunnett T3 multiple comparison, and Mann-Whitney U test (P = .05). RESULTS: Mean bond strengths without the high-flow bonding agent application varied from 0.1 to 13.6 MPa, whereas bond strengths with bonding agent application ranged from 0.1 to 24.2 MPa. CPB+Activator (containing phosphate MDP and silane) and CPB (containing MDP) revealed the significantly highest bond strength among the 9 groups without high-flow bonding agent application (P < .05). Application of the high-flow bonding agent significantly increased bond strengths (P < .001). CONCLUSION: Primers containing either the functional phosphate monomer MDP or an MDP-silane combination provide superior resin bonds of Estenia C and B composite to Katana zirconia. An intermediate high-flow bonding agent further improves the bond between these materials.

Structure-activity relationship of an antibacterial peptide, maculatin 1.1, from the skin glands of the tree frog, Litoria genimaculata.

Maculatin 1.1 (Mac) is a cationic antibacterial peptide isolated from the dorsal glands of the tree frog, Litoria genimaculata, and has a sequence of GLFGVLAKVAAHVVPAIAEHF-NH2. A short peptide lacking the N-terminal two residues of Mac was reported to have no activity. To investigate the structure-activity relationship in detail, several analogs and related short peptides of Mac were synthesized. CD measurement showed that all the peptides took more or less an alpha-helical structure in the presence of anionic lipid vesicles. Analogs which are more basic than Mac had strong antibacterial and hemolytic activities, while short peptides lacking one or two terminal residues exhibited weak or no activity. Outer and inner membrane permeabilization activities of the peptides were also reduced with shortening of the peptide chain. These results indicate that the entire chain length of Mac is necessary for full activity, and the basicity of the peptides greatly affects the activity.