Bond strength of short-pulsed laser-irradiated zirconia to veneer ceramic

Objective: The aim was to evaluate the effect of 1064 nm Yb-doped fiber-based nanosecond pulsed laser on surface roughness and bond strength between veneer ceramic and zirconia. Material and methods: Zirconia discs were divided into three groups: sandblasted (SB), laser irradiated (YL), and control (n?=?12). YL group was treated with ytterbium laser with the setting of 85 W/25 kHz. Sandblasting was done using 50 μm Al₂O₃ particles from a distance of 10 mm for 20 s under 3.5 atm. No surface treatment was applied to the control group. The surface roughness values and SEM images of the groups were obtained. X-ray diffraction analysis was applied to a spare sample of each group to determine the monoclinic phase ratio. The samples were subjected to shear bond strength (SBS) test with a cross-head speed of 1 mm/min after being veneered. The fracture modes were evaluated. One-way analysis of variance and Tukey’s HSD tests were used for statistical analysis. Results: The YL group had higher surface roughness than the control (p?≤?0.0001) and the SB group (p?=?0.007) with a mean value of 2.90 μm. The SEM images of the groups supported this result, but formation of the microcracks was more intense for the YL group. The monoclinic phase ratio was highest for the SB group. However, the differences of SBS between SB and YL groups were not statistically significant. Mostly the combined failure of samples was observed. Conclusions: Ytterbium laser treatment increased the surface roughness of zirconia, but the SBS was not higher than sandblasting. Surface roughness results did not correlate with the SBS results.     

Effect of thermal cycling and low pressure sandblasting on the bond strength of a self-adhesive cement to Y-TZP zirconia

The aim of this investigation was to assess the influence of several surface treatments on the shear bond strength (SBS) of a self-adhesive resin cement containing 10-methacryloxydecyl-dihydrogenphosphate monomer to densely sintered zirconia ceramic, before and after thermal cycles. Hundred densely sintered zirconia cylinders were divided into five groups (n = 20). Each of them received a different surface treatment: (1) control [No_T], with the zirconia surface unconditioned, (2) low pressure air abrasion [Sand_S], (50 μm, 1 bar), (3) standardized air abrasion [Sand_H], (50 μm, 2.8 bar), (4) standardized Rocatec? Plus (silica-coated alumina oxide) air abrasion (2.8 bar) and silanization [Roc_H], (5) low pressure Rocatec? Plus (silica-coated alumina oxide) air abrasion (1 bar) and silanization [Roc_S]. Five more surface-treated specimens were addressed to scanning electron microscope for qualitative observations. After specimen fabrication, subgroups of 10 bonded samples were stored in water either for 24 h (T1) or subjected to 5000 thermal cycles (T2); SBSs were determined with a universal testing machine at a crosshead speed of 1 mm/min. At T1, mean SBSs (MPa) obtained for the examined groups were: [Sand_H] 16.24 ± 2.95; [Sand_S] 16.01 ± 2.68; [Roc_H] 17.17 ± 1.64; [Roc_S] 15.92 ± 1.99. All surface treatments positively affected (p < 0.05) the initial self-adhesive cement adhesion to zirconia with respect to No_T (13.29 MPa). Artificial aging decreased the bond strength in all test groups significantly, but no spontaneous debonding was observed in [No_T]: at T2, SBS values ranged from 7.76 ± 2.37 (No_T) to 8.89 ± 1.74 (Sand_S), with no statistically significant difference between groups (p = 0.5293). Both air abrasion with alumina oxide and Rocatec? universal bonding system, used with hard or low air pressure, produced comparable effects on cement–zirconia interface before and after thermal cycles. After artificial aging, minimal differences in bond strength values between sandblasted and control groups were not of statistical significance.     

Improvement of flexural bond strength of zirconia-resin cement by surface patterning using sub-nanosecond UV laser

Zirconia is a dental material that shows excellent biocompatibility and high strength in clinical applications. This study aims to evaluate the effects of ultrafast laser applications. The surface nanostructures were classified into three groups. Group 1 was generated using the burst mode, with three different distances between dots: 52 µm (Group 1a), 104 µm (Group 1b), and 156 µm (Group 1c). Group 2 was processed using the scanning mode configuration, with a set of parallel lines. Group 3 was also processed using this scanning configuration creating a set of square-shaped patterning. Group 4 was the control group. After the surface treatments, a pair of zirconia specimens was bonded end to end with resin cement. Flexural bond strength (FBS) test was applied in a universal test machine. Multiple comparisons were performed using a one-way analysis of variance and the Tukey's HSD test. All the samples that were treated with the laser showed higher FBS values than the untreated surface. Using the burst mode, preformed circular-shaped surface on an angle of 90⁰ at 52 µm distance (Group 1a) showed the highest FBS values among all groups (p < .05). Groups 2 and 3 had significantly higher values than 1b and 1c.     

Effectiveness of different surface cleaning methods on the shear bond strength of resin cement to contaminated zirconia: an in vitro study

The purpose of this in vitro study was to evaluate and compare the effectiveness of different surface cleaning methods on the shear bond strength (SBS) of zirconia ceramic surfaces. Seventy polished and cleaned zirconia disk specimens of 8 mm in diameter and 3.4 mm in thickness were immersed in fresh saliva. They were then pressed into a freshly mixed silicone disclosing medium. Six different cleaning methods were applied to the tested groups; they were airborne-particle abraded (AA), covered with a cleaning paste (Ivoclean®) (IV), etched with orthophosphoric acid (PA), immersed in alcohol (AL), rinsed with tap water only (WA), or cleaned with steam (SC). No surface cleaning was done after saliva immersion and silicone disclosing medium contamination to the control group (CC). The specimens were then bonded to an adhesive resin cement using polyethylene tubes. SBS was determined using a universal testing machine at a crosshead speed of 1 mm/min. The specimens were also examined with a scanning electron microscope and a stereomicroscope. Group AA yielded the highest SBS value (7.01 ± 1.4 MPa) among the groups, while Group WA had the lowest SBS value (3.03 ± 0.8 MPa). The SBS values of Group AA (7.01 ± 1.4 MPa) and IV (6.2 ± 1.7 MPa) were also significantly higher than those of the remaining four groups (p < 0.05). Within the limitations of this in vitro study, it was concluded that among the various cleaning methods tested, airborne-particle abrasion and Ivoclean® paste were effective in cleaning the zirconia surface.     

Influence of desensitizing procedures on adhesion of resin cements to dentin

This study evaluated the effect of two desensitizer agents with different contents and Nd:YAG laser irradiation on the shear bond strength (SBS) of adhesive resin cements to dentin. New treatment options of Nd:YAG laser irradiation and tetracalcium phosphate-containing agent applications were compared with routinely used glutaraldehyde-containing agents. One hundred and twenty human, caries-free premolars were embedded in acrylic resin blocks 2 mm below the cementoenamel junction. Buccal surfaces of the teeth were ground to expose dentin. The specimens were randomly assigned into three different surface treatments (desensitizing agents, Nd:YAG laser) and the control, then into three different adhesive resin cement applications (n = 10). Resin cements (Panavia SA cement (PA), Panavia SA cement with Clearfil Universal Bond (PACU), and Multilink N (MN)) were applied to the conditioned teeth surfaces using Teflon tubes. The specimens were thermocycled (5000 cycles, 5–55 ± 1 °C, dwell time 30 s). The SBS test was performed in all groups. The results were submitted to two-way ANOVA and Tukey HSD tests (p < .05). Further, SEM analysis was performed on the dentin surfaces. SBS values were significantly difference among the surface treatment groups and also among adhesive resin cement groups (p < .05). The specimen cemented with PA showed lower SBS values than PACU- and MN-applied specimens. The highest SBS value was obtained in the Nd:YAG laser group which was cemented with PACU cement. The lowest SBS value was obtained in the control group which was cemented with PA cement. In addition, SEM evaluation revealed that desensitizing agents and Nd:YAG laser occluded dentin tubules.     

Post-treatment with high-power lasers to improve bond strength of adhesive systems to bleached dentin

To assess the effect of Er:YAG and diode lasers on the shear bond strength (SBS) of adhesive systems to bovine dentin submitted to bleaching with a high concentration agent. One hundred and twenty bovine dentin fragments were used. Fragments were distributed into 12 groups (n = 10) considering the bleaching (present or not), surface post-treatment (untreated, Er:YAG laser or diode laser) and adhesive system (total-etching or self-etching). Specimens received two applications of 38% hydrogen peroxide. Er:YAG laser (2940 nm, 200 mJ, 4 Hz) and diode laser (980 nm, 1.5 W) were applied for 15 s on bleached dentin surface. Restoration was performed with resin using split matrix. Specimens were submitted to SBS test and data (MPa) were analyzed by ANOVA and Tukey’s test (α = 0.05). SBS of bleached specimens decreased in comparison with non-bleached (p < 0.05). The highest values were obtained for the post-treatment with Er:YAG laser (p < 0.05). Total-etching adhesive was superior to self-etching system (p < 0.05). The irradiation of bleached dentin with Er:YAG laser followed by the application of the total-etching adhesive had similar SBS to unbleached dentin with no post-treatment (control) (p > 0.05). Er:YAG laser post-treatment followed by the total-etching adhesive system improve the bond strength of restorative material to bleached dentin.     

The effect of MDP-based primer on shear bond strength of various cements to two different ceramic materials

The aim of this study was to determine the effect of 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based primer on the shear bond strengths of thermally aged self-adhesive and conventional adhesive resin cements and zinc phosphate cement to zirconia and lithium disilicate substructures. Sixty zirconia (Z) and 60 lithium disilicate (L) disk specimens were cut from ceramic blocks. Each group was divided into six subgroups (n = 10). Half of the specimens of each ceramic group were treated with primer (P) and the other half was remained untreated. Three types of cement were applied: zinc phosphate cement [(ZPC) (Hoffmann Harmonic Shades)]; self-adhesive resin cement [(SAC) (RelyX U200)]; conventional adhesive resin cement [(CAC) (C&B)]. The specimens were subjected to thermal aging procedure for 1 week under 37 °C water bath. Shear bond strength (SBS) was determined using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with three-way (ANOVA). Pairwise comparisons and interactions between groups were analyzed by using Tukey’s simultaneous confidence intervals. There was no significant difference between the SBS values of SAC-Z (11,47 ± 0,47) and SAC-ZP (11,39 ± 0,42) (p > 0.05). However, the SBS values of SAC-L (12.34 ± 0,55) and SAC-LP (12,50 ± 0,49) were significantly higher than those of SAC-Z and SAC-ZP (p < 0.00). The use of primer significantly increased the SBS value of CAC-ZP (8,05 ± 0,55) when compared to the SBS value of CAC-Z (3,53 ± 0,41) (p < 0.00). Resin cement that contains methacrylate monomers with phosphoric ester functional groups exhibited reliable bond to zirconia. However, the use of an MDP-based primer may not further improve its bond strength.     

The effect of different bonding protocols on the repair microshear bond strength of water-stored CAD/CAM resin composite

This study evaluated the repair microshear bond strength (μSBS) of water stored CAD/CAM resin composite under eight different surface treatments using a silane-containing universal adhesive in etch-and-rinse and self-etching modes. In total, 48 CAD/CAM resin composite slices were prepared from Lava Ultimate CAD/CAM blocks and stored in water for 6 months. The slices were assigned into 8 main groups, according to surface treatments (no treatment, no-treatment/silane, surface grinding, surface grinding/silane, sandblasting, sandblasting/silane, silica coating and silica coating/silane). Each main group was divided according to the universal adhesive application mode (either the etch-and-rinse mode or the self-etch mode). Each slice received 6 resin composite micro-cylinders (0.8 × 1 mm). Micro-shear bond strength was run at 0.5 mm/min crosshead speed until failure. Treated surfaces were examined using SEM. Bond strength data were statistically analyzed using Two-Way ANOVA/Tukey HSD post hoc test. Only ‘surface treatment’ significantly affected the repair μSBS (p ? 0.001). Parameters ‘Adhesive application mode’ and ‘surface treatment × adhesive mode’ showed no significant effect on μSBS (p = 0.458 and p = 0.286 respectively). Regardless of the adhesive application mode, silica coating showed the highest μSBS (21.6 ± 6.8 MPa), while sandblasting/silane showed the lowest μSBS (13.0 ± 6.1 MPa). Regardless of adhesive application mode, the use of silica coating to treat the water-stored CAD/CAM resin composite surfaces is crucial to improve the repair bond strength.     

Effect of different surface treatments on the shear bond strength of resin cement to zirconia ceramic and metal alloy*

The bonding of resin cement to ceramic materials plays an important role in dentistry. The purpose of this study is to evaluate the effects of various surface treatments on the shear bond strength (SBS) of zirconia ceramic and metal alloy. A total of 60 specimens were prepared from Y-TZP ceramic and metal alloy. The specimens were divided into three subgroups (n = 10) that received different surface treatments for each material. An Er:YAG laser (ER), a femtosecond laser (FS), and air-borne particle abrasion (A) were employed as surface treatments. One specimen from each group was analyzed using a scanning electron microscope (SEM) at 500 x magnification after surface treatments. The self-adhesive resin cement was then bonded to the treated surfaces using a Teflon mold. The specimens were thermocycled for 5,000 cycles at 5–55 °C, and then the SBS test was performed. Kruskal–Wallis and Mann–Whitney U tests were used to determine the differences between the groups (p = 0.05), and failure modes were evaluated for each specimen. Statistical analyses revealed significant differences between the surface treatment methods. The mean SBS values of the air-borne particle-abraded groups were higher than those of the other groups. The femtosecond-irradiated groups of each material showed significantly higher SBS values than the Er:YAG-irradiated groups (p < 0.05). Within the limitations of this study, air-borne particle abrasion and the femtosecond laser were more effective than Er:YAG laser treatment.     

Effect of femtosecond laser beam angle and formed shape on surface roughness and shear bond strength between zirconia and resin cement

Achieving adhesion between resin cement and zirconia requires pretreatment of the surface. This in vitro study aimed to evaluate the effect of femtosecond laser beam angle and the shape of the formed surfaces, on the roughness and shear bond strength (SBS) of resin cement to zirconia ceramic. Seventy Y-TZP ceramic specimens were divided into seven groups (n = 10). A femtosecond laser irradiation was performed on the ceramic surface of three shapes (spiral (SP), square (SQ) and circular (CI) and at two angles (30 and 90°) to give SP-30, SQ-30 and CI-30 and SP-90, SQ-90 and CI-90, respectively. After treatment, the surface roughness of all specimens was evaluated using a profilometer. One specimen from each group was analysed using a scanning electron microscope. The bonded specimens were thermocycled 5000 times and then an SBS test was performed. Kruskal-Wallis and Mann-Whitney U tests were used to analyse surface roughness and SBS values. The control group had statistically lower surface roughness (R_a) values than the treated groups (p < 0.05). SP-30 and SQ-30 laser treated specimens showed higher R_a values than the other specimens. Statistically significant SBS values (p = 0.000) were observed between the groups. All laser treated samples showed greater SBS compared to the control group. SP-30, SQ-30 and SQ-90 groups showed the highest SBS values. Within the limitations of this experimental study, the highest mean values for R_a and SBS were achieved with SP and SQ surfaces using a 30° angle laser beam.     

Bond strength of veneering porcelain to zirconia after different surface treatments

Aim: The aim of this study was to evaluate the effect of various surface treatments on the bond strength of veneering feldspathic porcelain to zirconia. Methods: Fifty yttria-stabilized tetragonal zirconia polycrystalline specimens were divided into five groups (n = 10) according to various surface treatments. The groups were as follows: Group 1: control group with liner application and no further surface treatment; Group 2: air-particle abrasion with 110 μm of alumina (Al₂O₃) particles; Group 3: grinding with a diamond disk; Group 4: Nd:YAG laser irradiation (the laser and the energy parameters were 10 Hz, and 2 W and 200 mJ, and the pulse duration (short pulse) range was up to 180 μs); Group 5: selective infiltration etching (SIE). After surface treatments, a liner application was performed for all surfaces according to the manufacturer’s instructions. Veneering porcelain was applied on zirconia surfaces using a Teflon mold. Shear bond strength was tested using a universal testing machine. The fractured surface morphologies were examined with scanning electron microscopy. The data were statistically analyzed using Mann–Whitney U and Kruskal–Wallis tests (α = .05). Results: The Megapascal values of the bonding groups were as follows: G1 = 8.62 ± 1.12, G2 = 13.87 ± 5.08, G3 = 12.31 ± 3.35, G4 = 17.32 ± 6.16, and G5 = 16.17 ± 4.55. Statistically significant differences were observed between the control group and the other groups (p < 0.05). Group 4 had the highest bond strength while G1 showed the lowest bond strength. No significant differences were found between the Nd:YAG, grinding, sandblasting, and SIE groups. Conclusion: Surface treatments had different effects on the shear bond strength of feldspathic porcelain to zirconia. Surface treatment techniques used in this study can be used on zirconia specimens prior to liner application to obtain an acceptable bond strength of veneering porcelain to zirconia. The effect of Nd:YAG laser irradiation and SIE techniques on bond strength of veneering ceramic to zirconia should be evaluated with further studies.     

Effects of two metal primers on the shear bond strength of orthodontic molar tubes bonded to silver amalgam restorations of different dimensions

The aim of this study was to evaluate the shear bond strength (SBS) of orthodontic molar tubes bonded to amalgam restorations and enamel with four different area ratios, with and without the use of various metal primers. One hundred and fifty-six sound lower first molars were divided into five groups; control group (CG;n = 12) then divided into three subgroups: A, B, and C. Class V buccal amalgam restorations consisting of 25%(G1), 50%(G2), 75%(G3), and 100%(G4) of the basal areas of the molar tubes. Transbond XT Primer (TXTP;subgroup A), Alloy Primer (AP;subgroup B) and Reliance Metal Primer (RMP;subgroup C) (n = 12). Transbond XT was used as an adhesive material in all groups. Thermocycling was as 5 –55 °C, 1000 cycles. Data were analysed by one-way ANOVA and post hoc least significant difference tests (p < 0.05). Bond failure sites were classified using a modified Adhesive Remnant Index (ARI) system. SBS did not differ significantly among the three intermediate adhesives in subgroups of groups 1, 2, or 3 (p > 0.05); however, SBS was significantly higher in groups 4B and 4C than in group 4A (p < 0.05). Mean SBSs of groups 1 and 2 were significantly higher than others (p < 0.05). Mean SBS of group 3 was higher than that of group 4, but lower than that of the other groups. For ARI, significant relationships between CG and the intermediate adhesive groups were found (p < 0.05). Application of metal primers, such as AP or RMP, to sandblasted amalgam adjacent to etched enamel (25, 50, and 75%) did not improve bond strength significantly compared with the application of TXTP to amalgam and enamel.     

Effect of experimental primers on hydrolytic stability of resin zirconia bonding

This study assessed the effect of experimental silane primers and two adhesive resin cements on resin zirconia adhesion strength. The surfaces of cut Y-TZP zirconia blocks (Lava? Frame), 16 mm × 16 mm × 4.5 mm, were pretreated twice. First, they were grit-blasted with Korox? alumina powder (110 μm) followed by silica-coating with Rocatec? Soft. Next, the blocks were randomly assigned into eighteen sub-groups (n = 6, N = 108) according to three primers (control ESPE Sil?, 1.0 vol.-% 3-acryloxypropyltrimethoxysilane, and 1.0 vol.-% 3-acryloxypropyltrimethoxysilane + 0.5 vol.-% bis-12-(triethoxysilyl)ethane), two in dentistry used resin cement products (Multilink? Speed, and Multilink? N), and three storage conditions (24 h dry, 1 month immersed in distilled water, and 6 months immersed in distilled water at room temperature) used. Onto each pretreated zirconia block, four cylindrical resin composite cement stubs were prepared and light-cured. The surface roughness, contact angle, and adhesion (shear bond) strength (SBS) were measured, and statistically analyzed (ANOVA, the Tukey’s test, p < 0.05). No statistical differences were observed in surface roughness values of different primer-treated zirconia groups. After six months of water aging, the shear bond strength of the groups that employed 1.0 vol.-% 3-acryloxypropyltrimethoxysilane (9.0 MPa ± 0.8 MPa), and the blend of 1 vol.-% 3-acryloxypropyltrimethoxysilane + 0.5 vol.-% bis-12-(triethoxysilyl)ethane (8.9 MPa ± 2.0 MPa) with Multilink? Speed resin composite cement were statistically insignificantly higher compared to using ESPE Sil? (8.7 MPa ± 1.8 MPa). The experimental primers may have potential to be used for long-term resin zirconia adhesion.     

Effects of neutralizing or antioxidant agents on the consequences induced by enamel bleaching agents in immediate resin composite restorations

Purpose: Bleaching agents are claimed to impair the bonding to the tooth structure when resin composite restorations are immediately performed. This study aimed to evaluate the effect of a neutralizing solution (10% sodium bicarbonate) or an antioxidant agent (10% sodium ascorbate) on the immediate or delayed (15 days) shear bond strength (SBS) of composite restorations performed on enamel. Seventy flat buccal enamel surfaces obtained from bovine incisors were divided into seven groups (n = 10): control group, unbleached enamel, restored (3M ESPE/Adper Single Bond 2/Filtek Z350XT) (G1); bleached, immediately restored (G2); bleached, delayed restoration (G3); bleached, antioxidant (sodium ascorbate), immediately restored (G4); bleached, antioxidant, delayed restoration (G5); bleached, neutralizing (sodium bicarbonate), immediate restoration (G6); bleached, neutralizing, delayed restoration (G7). Specimens were submitted to SBS test and examined after failure using scanning electron microscopy (SEM). Results were statistically analyzed with ANOVA/Tukey’s tests (5%). Bonding to enamel immediately restored after bleaching (G2) was significantly lower than G1 (unbleached enamel; p < 0.05). Applying the antioxidant or neutralizing agent significantly improved the bonding to enamel compared with G2 (bleached, immediate restored), irrespective of the restoration time (immediate or delayed) (p < 0.05). No significance was found between the two agents when applied after bleaching, and compared with the control group, regardless of evaluation time (p > 0.05). SEM images demonstrated adhesive failures in the bleached, immediately restored group (G2). G3–G7 exhibited majority of cohesive and mixed failure patterns. 10% sodium bicarbonate or 10% sodium ascorbate neutralizes the negative immediate and delayed effects of bleaching on bond strength of enamel bleached enamel.     

Influence of different surface treatments on zirconia/resin shear bond strength using one-bottle universal adhesive

ABSTRACT

This study was designed to evaluate the effect of different treatments on the zirconia/resin shear bond strength (SBS) using commercial one-bottle universal adhesive. Zirconia discs with different surface treatments (blank control; airborne-particle-abrasion; glazing) were bonded to the bovine enamel surfaces using one-bottle universal adhesive. All specimens were tested for SBS (MPa) before and after 10000 thermocycles. Statistically analysis were conducted by using one-way analysis of variance and multiple-comparison least significant difference tests (α = 0.05). Airborne-particle-abrasion group showed higher SBS (36.19 ± 11.86) than control group (14.98 ± 5.90) and glazing group (10.63 ± 5.39) (p < 0.05). After thermocycling test, the SBS significantly decreased for control group (8.84 ± 2.55) and glazing group (6.18 ± 2.78) while not for airborne-particle-abrasion group (41.5 ± 7.95). One-bottle universal adhesives combined with airborne-particle-abrasion showed quite high SBS of zirconia/resin, which was appropriate for bonding of zirconia restoration.     

Shear bond strength to enamel and failure type of different periodontal splints: an in vivo and in vitro study

The goal of this study was to evaluate the shear bond strength (SBS) and failure mode of four different splint materials [Polyethylene FRC Ribbond Thm (RB), Polyethylene FRC Construct (Kerr), Multifilament Fishing Line (MFL), and Non Fiber Reinforced Composite (control)]. Thirty-seven subjects were randomly divided into four splint methods. After splinting procedures, the subjects were recalled 12 months later. One hundred and sixty human mandibular incisors (for extracoronal and intracoronal splinting) and 40 sheep mandibles (only extracoronal splinting) were used for the in vitro part. The specimens were subjected to SBS at their incisoproximal contact, and debonding forces were measured with a universal testing machine (1 mm/min crosshead speed). Failure sites were examined under a stereomicroscope (×40 magnification). The SBS data were assessed via analysis of variance (ANOVA) and Tukey’s tests. The survival rate was significantly affected by the splint type (RB:95.3%, Kerr:91.6%, MFL:93.5%, Control:52.5%). No statistically significant differences were found between RB, Kerr, and MFL (p > 0.05) at all in vitro parts. Intracoronal splinting showed lower SBS values than extracoronal (p < 0.05). Lower SBS values were obtained in sheep teeth than human teeth (p < 0.05). Significantly different fracture patterns were noted between groups (p < 0.05). Only resin composite application seems to be inadequate for periodontal splinting. MFL splints are also economic and quite resistant, and they might be used as an alternative to fiber-reinforced composites.     

Effect of different denture adhesives on retention of complete dentures: an in vivo study

The increase in prevalence of tooth loss with the effect of population aging produces the growing need for complete dentures. The success and acceptance of complete dentures by the patient depends on sufficient retention and stability. Therefore, denture adhesives are regularly used by denture wearers to improve the function of complete denture. We evaluated the effect of three different denture adhesives (Corega, Protefix, Fittydent) on the retention of maxillary complete denture (MCD) using with digital dynamometer (DD). For this purpose, denture adhesives were applied on MCDs of 30 participants. After chewing procedure, the force was applied at 45° to the palatal surface of denture by DD. Dislodgement force was recorded by means of Newton. There were four measurements on each patient including; group of control: Group C; Group CR: Corega; Group F: Fittydent; Group P: Protefix. The result of the study was statistically evaluated by using analysis of variance (ANOVA) and Tukey HSD test. Statistics of ANOVA showed a significant difference among all the four groups (p = 0.00, <0.05). Tukey HSD test indicated that there was a statistical difference between Group F and the other groups, but there was not a significant difference between the other groups. The highest adhesive strength value was observed in group F, the lowest in group C. Use of denture adhesives improved the retentive strength of complete denture.     

Immediate and delayed repair bond strength of a new ormocer resin restorative material as a function of mechanical and chemical surface conditioning methods

This study evaluated the μ-shear repair bond strength (μSBS) of a new ormocer restorative material as a function of repair time and repair protocol. Ormocer disks (N = 140) (Admira Fusion, Voco) were prepared and divided into 14 groups: Factor 1: Bonding protocol (No Conditioning, Admira Bond, Futurabond M+, Silane/Admira bond, Silane/Futurabond M+, Ceramic repair system, Silane/Cimara bond) and Factor 2: Repair procedure time (immediate versus delayed). Each disk received two ormocer micro-cylinders. Half of the disks were repaired immediately (24 h) and the other half after six-month water storage. Shear test was run at cross-head speed of 0.5 mm/min. Debonded specimens were evaluated for failure mode and SEM analysis was performed. Data were analyzed using two-way ANOVA and Tukey’s tests (p < 0.05). Both the repair time and the surface conditioning method showed a significant effect on the repair μSBS (MPa) of the ormocer material (p = 0.000). When immediate repair strengths were considered, all repair protocols tested reached the mean bond achieved based on oxygen-inhibited layer (10.8 ± 2.4 MPa), except. Futurabond M+(13.9 ± 3.4) and Silane/Cimara adhesives (16.3 ± 2.9) showed significantly higher μSBS (p = 0.001 and p = 0.000, respectively). For the delayed repair, non-conditioned (5 ± 1.7), showed significantly lower values compared to those of the other protocols (p < 0.05). Failure modes were predominantly adhesive type (immediate:95% and delayed:90%). No cohesive failures were observed either in the substrate or in the repair material.     

The effects of water flow rate on shear bond strength of self etch resin cement to dentin surface after Er,Cr:YSGG laser etching

The aim of the present study was to evaluate the effect of water flow rate on the morphological features of dentin and shear bond strength (SBS) of self-etching resin cement after Er,Cr:YSGG laser etching. Dentin specimens obtained from extracted human third molars were randomly assigned to four groups (n = 23), including one that received no laser irradiation (control-group D) and three others with different laser parameters: 2.25 W, 50 Hz, 60% air with water flow rates of 19 mL/min-100% water (group A), 2.25 W, 50 Hz, 6.75 mL/min-50% water (group B), and 2.25 W, and 50 Hz, 2.75 mL/min-25% water (group C). The morphological features of each group were examined with scanning electron microscopy and atomic force microscopy. The SBS of resin cement disks (Panavia F2.0, Kuraray; Tokyo, Japan) (3 mm in diameter and 2 mm in height) to the dentin specimens was measured using a universal testing machine at a cross head speed of 0.5 mm/min. Bond strength values were analyzed with one-way ANOVA/Tukey tests. There were no significant differences between the SBS values of groups A and B (p > 0.05). However, the SBS values of these groups were significantly higher when compared to groups C and D (p < 0.001). Er,Cr:YSGG laser application with water flow rates of 6.75 or 19 mL/min resulted in better dentin surface alterations and increased the SBS of self-etching resin cement to dentin.     

Effects of surface treatments on the shear bond strength of luting cements to zirconia

Objective: The aim of this in vitro study was to evaluate the effect of surface treatments on the shear bond strength of resin cements to zirconia. Material and methods: Sintered zirconia specimens (n = 192) were divided into four different surface treatment groups: control (no treatment); airborne-particle abrasion; glaze layer and hydrofluoric acid (HF) application, and hot etching solution application. Then, each group was divided into four subgroups (n = 12), and three different resin cements were applied to the zirconia surfaces. The shear bond strength value of each specimen was measured after 5000 thermo cycles. The failure types were examined with a stereomicroscope and the effects of the surface treatments were evaluated with a scanning electron microscope. Results were analyzed using analysis of variance and Tukey’s post hoc tests (α = 0.05). Results: The surface treatment and resin cement type significantly affected the bond strength results (p < 0.05). For all resin cements, the airborne-particle abrasion treatment increased the shear bond strength values (p < 0.05). The glaze layer & HF application increased shear bond strength values for all groups, except the Single Bond Universal-RelyX Unicem Aplicap group (p < 0.05). The surface roughness values of airborne-particle abraded specimens were similar to comparable values for specimens from the control group and the hot etching solution group (p > 0.05). The glaze layer & HF application group produced the highest surface roughness values (p < 0.05). Conclusion: The results of this study recommend using the appropriate combination of surface treatment and adhesive/silane coupling agent to achieve durable zirconia-resin bonding.