Bond Strength of Porcelain Bonded to Enamel and Dentin Surfaces Prepared with Different Surface Treatments

Although acid etching is routinely used to condition tooth surfaces, it increases the caries susceptibility of enamel and enhances enamel demineralization; thus the role of alternative surface treatments such as alumina air abrasion and erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation for tooth conditioning is controversial. This study was undertaken to compare the effects of different conditioning methods on the shear bond strength (SBS) of resin cement on enamel and dentin. Prepared permanent human dentin and enamel samples (N = 210) embedded in clear acrylic resin were conditioned by 37% phosphoric acid etching, 50-µm alumina air abrasion, Er:YAG laser irradiation (120 mJ, 10 Hz, medium short pulse mode), or their combinations. Porcelain laminates were cemented by using photopolymerizing luting composite. SBS was evaluated after thermal cycling (10,000 cycles, 5–55°C) and fracture types (adhesive, cohesive, or mixed) were observed by stereomicroscopy. Data were analyzed by Kruskal–Wallis analysis of variance and followed by Tamhane's test (p < 0.05). Enamel and dentin specimens showed significant differences in SBS (p < 0.000). Er:YAG laser etching presents successful alternatives to acid etching on dentin surfaces; it does not enhance adhesion of the resin cement on enamel surfaces.     

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.     

Strengthen adhesion between zirconia and resin cement using different surface modifications

The aim of this research was to assess the influence of different surface modifications on the bond strength between resin cement and zirconia ceramics. Eighty-four zirconium samples were prepared. Four different surface treatments were applied; nano-alumina coating, 2 minutes gas-phase fluorination, 50 μm alumina airborne-particle abrasion, and 50 μm airborne-particle abrasion + 2 minutes gas-phase fluorination. Then specimens were bonded to resin cement. Half of the samples were then incubated in 37°C distilled water for 24 hours. The remaining samples were subjected to thermocycling for 5000 cycles. Shear-bond strength testing was applied at a cross head speed of 5 mm/s. Two-way ANOVA was used in comparison between groups. There is a significant difference between the groups with 5000 cycles and the groups with 24 hours of water cycling. The highest shear-bond strength values were observed in the groups with airborne-particle abrasion + 2 minutes fluorination (27.57 MPa) and nano-alumina coating (26.45 MPa) which were not subjected to thermal cycling. Nano-alumina coating of the zirconia surface and the 2 minutes gas-phase fluorination method following airborne-particle abrasion process increased bond strength between resin cement and zirconia.     

Bond strength of repaired composite resins: surface treatments,adhesive systems,and composite type

The aim of the present study was to investigate the effects of three different surface treatments and two different adhesives on the microtensile bond strength (μTBS) of repaired composites using the same or different type of resin. Twenty-four nano-hybrid (Ceram X mono-C) and 24 nanofilled (Filtek Ultimate-F) composite discs were prepared. The specimens were aged with 5000 thermocycles and randomly divided into groups according to the surface treatment methods: (a) phosphoric acid (b) Er:YAG laser and (c) aluminum trioxide particle (air abrasion). Fresh composite resins (C and F) were added to the treated surfaces with two different adhesives (two-step and one-step self-etch adhesives). Then, the specimens were aged again. The stick-shaped specimens were prepared from the discs (n = 25) and the sticks were subjected to the μTBS test. Results indicated that significant differences were found in μTBS values among the surface treatment methods. In the C groups, the highest μTBS value (41.3 ± 8.3 MPa) was recorded in the air abrasion and one-step self-etch adhesive group, which were repaired with the same kind of composite. In the F groups, the highest μTBS value was observed in the air abrasion and one-step self-etch adhesive (37.6 ± 12.3 MPa) group. The treatment with air abrasion is more effective than the others, and it may be suggested for composite repair.     

Effect of ceramic surface treatments on the bond strength of different composite resins

This study was aimed to observe the relationship between the different surface treatments and the bond strength of both composite based adhesive cement and zirconia ceramic. Thirty-two zirconia ceramic discs were fabricated by following the instructions of manufacturer (5 × 5 × 1.5 mm). Four subgroups were obtained from the specimens according to the specified surface treatments respectively: (a) C: control groups: no treatment; (b) SB: sandblasting with 125 μm aluminum oxide particles for 10 s; (c) SC: silica coating for 10 s; (d) Nd :YAG laser . The composite resin specimens Panavia F and Clearfil SA were introduced and polymerized to the treated bonding areas. Afterwards the specimens were stored in distilled water at 37 °C during 24 h, and the shear test was applied. The data were statistically analyzed by ANOVA and Duncan tests. The bond strength was stated significantly higher in silica coating/Panavia F group (23.35 MPa). The lowest bond strength was stated in control groups cemented with Clearfil SA (12.25 MPa). As a result it was determined that the bond strength has affected the both surface treatments and cement types (p < 0.001). The silica coating –treated zirconia ceramic recorded a significant increase in mean bond strength values.     

Surface etching and silane heating using Er:YAG and Nd:YAG lasers in dental ceramic luted to human dentin

Investigate the tensile bond strength, surface morphology, and wettability of reinforced glass-ceramic etched with high power laser at different protocols and luted to human dentin. Fifty carious-free human molars were used in this study and distributed in five groups according to surface etching: (Control [HF10% + Silane]; Er [Er:YAG + Silane]; Sil + Er [Silane + Er:YAG]; Nd [Nd:YAG + Silane]; and Nd + Sil [Silane + Nd:YAG]). After, the tensile bond strength test was performed. Three specimens per group were used to perform the surface morphologies by using scanning electron microscopy analysis and wettability by using the sessile drop technique. Failure modes were determined. Data were analyzed with two-way analysis of variance and Tukey tests, with α = .05. The bond strength data showed statistically significant differences among tested groups for the laser and silanization technique type (p < .001). The highest calculated bond strength values were obtained with Er (19.25 ± 3.70 MPa) followed by Sil + Er (14.11 ± 4.11 MPa), Control (9.42 ± 2.27 MPa), Nd (9.66 ± 2.02 MPa), and Nd + Sil (6.71 ± 1.88 MPa), respectively. The silane application prior to the laser irradiation showed an inferior bond strength compared to the conventional silanization technique. The surface etching using Er:YAG laser showed promissor results for the lithium disilicate.     

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.     

The effect of different in-office bleaching techniques and etching procedures on bond strength of orthodontic brackets

The aim of this study was to compare the effects of different in-office bleaching techniques and acid/laser etching on bond strength of orthodontic brackets. Ninety-six extracted human premolar teeth were used in the study. The teeth were randomly divided into four groups according to different in-office bleaching techniques (n = 24); Group I: Diode laser-assisted bleaching, Group II: Er:YAG laser-assisted bleaching, Group III: In-office bleaching with LED, Group IV: Unbleached (control). After the samples were kept in artificial saliva for 2 weeks, each group were randomly divided into 2 subgroups according to etching methods; a–acid etching; b–laser etching. For laser etching Er,Cr:YSGG laser was used at 1.5 W, 15 Hz with 140 μs pulse duration for 20 s. For acid etching, 37% phosphoric acid was used for 30 s. The shear bond strength testing was performed using Instron Testing Machine with a crosshead speed of 1mm/min. Adhesive Remnant Index (ARI) scores were also measured. Data was analyzed using two-way ANOVA, Bonferroni, Kruskal Wallis and Mann Whitney U tests (p < 0.05). No statistically significant differences were found between bleaching groups and control (p > 0.05). There were statistically significant differences between acid and laser etching within each group (p < 0.05). Acid etching caused significantly higher bond strength values (p < 0.05). While no statistically significant differences were observed between the ARI scores of bleaching and control groups (p > 0.05), acid etching caused statistically higher ARI scores than laser etching groups (p < 0.05). In conclusion in-office bleaching either with LED or laser before bracket bonding did not affect bond strength. Prior to bracket bonding, acid etching of enamel caused higher shear bond strength values than laser etching.     

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.     

Could readily silanized silica particles substitute silica coating and silanization in conditioning zirconium dioxide for resin adhesion?

This study investigated the effect of particle types with different morphology and surface properties on the wettability and adhesion of resin cement to zirconia. Zirconia specimens (5 × 5 × 1 mm³) were wet polished. Specimens were randomly assigned to one of the following protocols (N = 36, n = 9 per group): Group CON: Control, no surface conditioning; Group AL: Chairside air-abrasion with aluminium trioxide (50 μm Al₂O₃) + silane; Group SIL: Chairside air-abrasion with alumina particles coated with silica (SIL) (30 μm SiO2, SilJet) + air-drying + silane; Group 4: Chairside air-abrasion with readily silanized silica particles (SILP) (30 μm SiO_2, SilJet Plus). Adhesive resin was applied and resin cement (Variolink II, Ivoclar) was bonded using polyethylene moulds and photo-polymerized and aged (thermocycling, 6.000 cycles, 5–55 °C). Shear bond test was performed using Universal Testing Machine (1 mm/min). Pretest failures were considered 0 MPa. Contact angle measurements were performed (n = 2/group, sessile drop with water). Data (MPa) were analyzed (ANOVA, Tukey’s (α = 0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m) and shape (0), values were calculated. Contact angle measurements were in descending order as follows: SIL (74°)^c < CON (60°)^c < AL (51°)^b < SILP (40°)^a. Bond strength (MPa) with SIL (17.2 ± 4)^a and SILP (17.3 ± 1.9)^a demonstrated no significant difference (p > 0.05), being higher than AL (8.4 ± 1.5)^b and CON (0)^c (p < 0.05). Failure types were exclusively adhesive in all groups. Weibull distribution presented the highest shape (0) for SILP (10.8). SILP presented better wettability than AL. SILP provided similar bond strength to SIL. Readily silanized silica particles may substitute for conventional silica coating and silanization.     

An investigation of atomic force microscopy,surface topography and adhesion of luting cements to zirconia: effect of silica coating,zirconia primer and laser

This study evaluated the effect various surface conditioning methods on the surface topography and adhesion of luting cements to zirconia. Zirconia blocks (N?=?25) were randomly assigned to five groups according to the surface conditioning methods: (a) No conditioning, control (CON), (b) tribochemical silica coating (TSC), (c) MDP-based zirconia primer (ZRP), (d) coating with nano aluminum nitride (ALN) (e) etching with Er: YAG laser (LAS). The conditioned zirconia blocks were further divided into five subgroups to receive the luting cements: (a) MDP-based resin cement (Panavia F2.0) (PAN), (b) 4-META-based cement (Super Bond) (SUB), (c) UDMA-based (GCem) (GCE), (d) bis-GMA based (Bifix QM) (BIF) and (e) polycarboxylate cement (Poly-F) (POL). Cements were applied in polyethylene moulds (diameter: 3?mm; height: 2?mm). The bonded specimens were first thermocycled for 5500 cycles (5–55?°C) and then adhesive interface was loaded under shear (0.5?mm/min). The data (MPa) were analyzed using 2-way ANOVA, Tukey’s and Bonneferroni tests (alpha?=?0.05). Regardless of the cement type, TSC resulted in significantly higher bond strength (p???0.05) (13.3?±?4.35–25.3?±?6.3) compared to other conditioning methods (2.96?±?1.5–5.4?±?5.47). Regardless of the surface conditioning method, no significant difference was found between MDP, 4-META and UDMA based cements (p?>?0.05) being significantly higher than those of bis-GMA and polycarboxylate cements (p???0.05). Failure types were frequently adhesive in all groups. Tribochemical silica coating provided superior bond results compared to other conditioning methods tested on zirconia especially in conjunction with UDMA- and 4-META-based resin cements.     

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.     

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.     

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.     

Influence of zirconia surface treatments on resin cement bonding and phase transformation

It evaluated the effects of different zirconia surface treatments on the bond strength of a resin cement to Y-TZP (yttria-stabilized tetragonal zirconia) ceramics, as well as their phase-transformations. 75 blocks (5 mm × 5 mm × 4 mm) of Y-TZP were assigned into five groups (n = 15): (tribochemical silica coating - TBS) zirconia surface was abraded by silica coated alumina particles followed by silanization; (GLZ₁) zirconia surface received the application of a thin layer of low-fusing porcelain glaze, followed by hydrofluoric acid (HF) etching for 1 min; (GLZ₅) glaze application + HF etching by 5 min; (GLZ₁₀) glaze application + HF etching by 10 min; (GLZ₁₅) glaze application + HF etching by 15 min. After etching, all the specimens were washed, dried and silanized. Cylinders of composites (diameter: 3.25 mm; height: 3 mm) were cemented to the Y-TZP blocks using a resin cement. All the specimens were subjected to aging (10,000 thermal cycles and 90 days storage), tested under shear conditions, and finally analyzed by a stereomicroscope (failure analysis). In addition, we also performed topographical and phase transformation analyses of the treated zirconia surfaces. The TBS group presented the highest bond strength value (23.34 MPa). The glazed groups presented low bond values and high prevalences of pretest failures. X-ray diffraction analysis showed a phase transformation for the TBS group (13.14%); however, there was no clear phase change observed for the GLZ groups. From our results, we concluded that tribochemical silica coating is the main Y-TZP surface conditioning for resin bond improvements.     

Airborne-particle abrasion with niobium phosphate bioactive glass on caries-affected dentin: effect on the microtensile bond strength

This study evaluated the effect of airborne-particle abrasion with niobium phosphate bioglass (NbG) microparticles on the bond strength (μTBS) and longevity of an adhesive system to different dentin substrates. In this study, 18 Caries-free molars were used, of which 12 were microbiologically processed for caries induction. The dentin surfaces were evaluated in three groups: (1) Control – Healthy Dentin; (2) Partial removal of carious tissue; (3) complete removal of carious tissue. Half the teeth in each group were submitted to airborne-particle abrasion with NbG microparticles (15 s/1 cm/5 bar). After this, the adhesive Clearfil S³ was applied and composite buildups were constructed incrementally; and specimens were longitudinally sectioned to obtain bonded sticks (1.0 mm²) to be tested in tension (0.5 mm/min) immediately or after 6 months of storage in water. The fracture patterns were evaluated by stereomicroscope (40×) and then by scanning electron microscopy. The data were analyzed by the Kruskal-Wallis (post hoc Dunn) and Mann-Whitney tests (α = 0.05). Healthy dentin showed the highest bond strength (μTBS). Airborne-particle abrasion with NbG increased the μTBS values in the Group with complete caries removal. The bond strength values in the 24-h period were higher than those at 6 months. In the majority of the specimens the fracture mode was adhesive/mixed. The authors concluded that airborne-particle abrasion on dentin with NbG particles increased the μTBS in the group in which carious dentin was completely removed.     

Comparison of methanol/hydrochloric,ferric chloride acid versus tribochemical silica coating for adhesion of resin cement to zirconium dioxide

This study compared air-abrasion and etching regimens on adhesion of resin luting agent to zirconium dioxide. Ceramic specimens (LAVA, 3 M ESPE) (N = 16) were embedded in acrylic resin and exposed surfaces were polished. The specimens were randomly assigned into four groups (n = 12, 3 specimens for each disc): SC: Air-borne particle abrasion (30 μm aluminum oxide particles coated with silica, CoJet, 3 M ESPE); MH: Heated chemical solution (Methanol-800 mL; 37% Hydrochloric Acid-200 mL; Ferric Chloride-2 g) at 100 °C for 30 min, MHP: Primer (Metal/Zirconia Primer, Ivoclar Vivadent) + MH, P: Primer only (Metal/Zirconia Primer). Cylindrical molds (internal diameter: 0.7 mm; height: 1.5 mm) were placed on each conditioned specimen, filled with resin cement (Multilink Automix) and photo-polymerized for 60 s. After 24 h, the molds were removed and the specimens were stored in distilled water at 37 °C for six months). Microshear test was performed in a Universal Testing Machine (1 mm/min). Failures types were classified as adhesive, mixed, or cohesive. In another set of specimens (n = 2 per group) contact angle measurements were recorded. Data were analyzed statistically using Kruskal–Wallis and Dunn’s tests (α = 0.05). The surface conditioning method significantly affected the mean bond strength (MPa) (p < 0.0001): SC(18.3 ± 0.3)^a < P(5.00 ± 0.07)^b < MHP(4.7 ± 0.08)^c < MH(0.84 ± 0.01)^c. While Group SC showed mainly adhesive (58%) and mixed (41.7%) failure types, groups MH, MHP, and P presented exclusively adhesive failures. SC, MHP, and P (29–32°) showed lower contact angle than MH (78.9°). Volume loss was the highest with MHP (9.92 μl) followed by SC (9.67 μl).     

Microleakage in class V cavities prepared using conventional method versus Er:YAG laser restored with glass ionomer cement or resin composite

This study evaluated the effect of tooth preparation method (diamond bur vs. Er:YAG laser) on the microleakage levels of glass ionomers and resin composite. Human permanent premolars (N = 80) were randomly divided into two groups (n = 40). Cavities on half of the teeth were prepared using diamond bur for enamel and carbide bur for dentin and the other half using Er:YAG laser. The teeth were randomly divided into four groups according to the restoration materials, namely (a) ChemFil Rock (CFR), (b) IonoluxAC (IAC), (c) EQUIA system (EQA) and one resin composite (d) AeliteLS (ALS) (n = 10 per group). Microleakage (μm) was assessed at the occlusal and gingival margins after dye penetration (0.5% basic fuchsine for 24 h). On the occlusal aspect, while the cavity preparation types significantly affected the microleakage for CFR (p = 0.015), IAC (p = 0.001) glass ionomer restorations, it did not show significant effect for glass ionomer EQA (p = 0.09) and resin composite ALS (p = 0.2). Er:YAG laser presented less microleakage compared to bur preparation in all groups except for EQA. On the gingival aspect, microleakage decreased significantly for CFR (p = 0.02), IAC (p = 0.001), except for EQA where significant increase was observed (p = 0.001) with the use of Er:YAG laser. Microleakage decrease was not significant at the gingival region between diamond bur and Er:YAG laser for ALS (p = 0.663). At the occlusal and gingival sites in all groups within each preparation method, microleakage level was not significant.     

Effect of Er,Cr:YSGG laser surface conditioning on the adhesion of fiber- reinforced composite and zirconia intraradicular posts to the root dentin

This study evaluated the influence of Er,Cr:YSGG laser surface conditioning on push-out bond strength of different root posts to the root dentin. Extracted (N = 27, n = 9 per group) and endodontically treated human mandibular premolars were prepared to receive the posts. Three types of posts, namely quartz fiber (D), glass fiber (S), and zirconium dioxide post (C) were luted with resin cement. The posts were randomly assigned to one of the surface conditioning method: (a) No conditioning, control (L0), (b) Er,Cr:YSGG laser at 175 mJ, 3.5 W for 60 s (L1), and (c) at 225 mJ, 4.5 W for 60 s, with 60 μs pulse duration and repetition rate was 20 Hz (L2) irradiation. Six sections (two coronal, two middle, and two apical) were made in each tooth yielding to 1 mm thick specimens. The specimens were stored in distilled water at 37?°C for 24 h and push-out bond strength (MPa) was tested in a Universal Testing Machine (1 mm/min). Data were analyzed using Kruskall–Wallis and Dunns`s post hoc tests (α = 0.05). In group D, both laser treated groups (L1:16.16 ± 19.89; L2:8.24 ± 9.26) presented significantly less bond strength compared to control group (L0:28.3 ± 16.8) (p < 0.001). Mean push-out bond strength values did not significantly differ according to the root segments (coronal, middle, and apical) (p = 0.106). Application of Er,Cr:YSGG laser, with the parameters tested, did not increase the bond strength of zirconium glass fiber and zirconium oxide posts. Laser surface conditioning decreased the bond strength of quartz fiber posts in the root canal.     

Er,Cr:YSGG laser irradiation influence on Y-TZP bond strength to resin cement

The aim of this study was to evaluate Y-TZP surface pretreatment with different protocols on microshear bond strength (μSBS) ceramic-cement interface. One hundred and sixty pre-sintered IPS e-max ZirCAD (Ivoclar-Vivadent) blocks were randomly divided into sixteen groups according to surface treatment (n=20): G1- no treatment (control); G2- ceramic primer; G3- tribochemical silica coating; G4- tribochemical silica coating+primer; G5- airborne particle abrasion (Al₂O₃); G6- airborne particle abrasion (Al₂O₃)+primer; G7- Er,Cr:YSGG laser; G8- Er,Cr:YSGG laser+primer. All specimens were sintered before surface treatment, except lasers groups, which were sintered after laser irradiation. Ceramic blocks were bonded with Panavia F resin cement (Kuraray, Okayama, Japan) (n=10) or RelyX ARC (3M ESPE, St. Paul, MN, USA) (n=10). The μSBS tests were carried out in a universal testing machine at a speed of 1mm/min after 24 h (n=5) or 6 months storage (n=5). Differences were found for both resin cements and storage conditions in relation to μSBS values (p<0.05). However, no significant difference for interaction between factors was observed in cemented blocks with RelyX ARC. Panavia F resin cement showed significant differences for interaction between factors (p<0.05). Laser treatment was not sufficient to increase μSBS values between Y-TZP and resin cements. Tribochemical silica coating followed by primer achieved the highest immediate μSBS values. The storage did not affect negatively μSBS values to both evaluated cements.