Effects of Surface Pretreatments on Bond Strength and Morphology of Aprismatic Enamel.

PURPOSE: To evaluate the effect of different pretreatment protocols and adhesives on the shear bond strength and surface morphology of aprismatic enamel. MATERIALS AND METHODS: Human maxillary incisors (N = 120) were assigned to five different groups according to pretreatment: 1) no treatment; 2) glycine; 3) sodium bicarbonate; 4) Al2O3 and 5) extra-fine bur. Then the teeth were divided into three subgroups, according to the adhesive applied: 3-step etch-and-rinse (ER), universal adhesive in ER mode, and universal adhesive in self-etch (SE) mode. Shear bond strength (SBS) testing was performed with a universal testing machine. For SEM observation, fifteen human molars were collected and analyzed after pretreatment with/without etching with 37% H3PO4 for 30s. RESULTS: Al2O3 showed higher SBS than all other groups considered. Comparable SBS values were obtained for other pretreatments. Universal adhesive in E&R mode performed better than did 3-step E&R and universal adhesive in SE mode. SEM images showed visible differences in enamel surface roughness. CONCLUSIONS: Airborne-particle abrasion with Al2O3 followed by etching with H3PO4 increased SBS on aprismatic enamel. The combination of airborne-particle abrasion with alumina powder followed by 15 s of H3PO4 etching and application of a universal adhesive in E&R mode proved to be the most effective adhesive protocol.

Effect of surface flattening and phototherapy on shear bond strength immediately after bleaching with different modes of universal adhesive.

OBJECTIVE: The aim of this study was to compare to effect of phototherapy and surface flattening after immediately bleaching on the shear bond strength to bleached enamel. METHODS: Ninety-six human upper incisors were divided into 4 groups (n = 24). Group NB: no bleached, group P: phototherapy with YSGG laser, group F: 0.5 mm surface flattening, group PF: 0.5 mm surface flattening and phototherapy with Er;Cr:YSGG laser. Then, each group was assigned to 2 subgroups according to adhesive mode (n = 12) as; subgroup S (self-etching mode), subgroup T (total-etching mode) which are universal adhesives. All surface conditionings and restorations were performed with composite resin materials immediately after bleaching. Shear bond strength test was performed by using universal testing machine. The surfaces were also evaluated with SEM. The data were statistically analyzed with one-way ANOVA post-hoc Tukey tests. RESULTS: The lowest SBS values were achieved in FS (13.72 ± 2.29) while the highest ones in PT (28.01 ± 6.81). However, the differences were not significant (P > 0.05). All surface conditioning methods provided SBS values similar to the control (P > 0.05). All subgroups of self-etching mode were significantly lower than their total-etching counterparts (P < 0.05). CONCLUSIONS: The present study showed that surface removal and phototherapy have a potential clinical application for eliminate to undesirable effect of bleaching treatment. Surface conditioning with either flattening and/or phototherapy may provide clinicians to restore bleached teeth at the same visit with bleaching and reduce chair-time.

Effect of grape seed extract-containing phosphoric acid formulations on bonding to enamel and dentin.

The aim was to evaluate the effect of 2% grape seed extract (GSE) containing phosphoric acid (PhA) on the bond strength to enamel and dentin. The control group was 37% PhA. The following three PhA formulations with 2% GSE and 20% ethanol were obtained: GSE5 = 5% PhA; GSE10 = 10% PhA; and GSE20 = 20% PhA. The enamel and dentin surfaces of molars were etched with the acid solutions, followed by Scotchbond Multi-Purpose adhesive and composite resin application. The tensile bond strength (TBS) test evaluated the bond to enamel after 24 h, and the microtensile bond strength (µTBS) test evaluated the bond to dentin after 24 h and 12-month water storage. Etched enamel and dentin were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The TBS data were submitted to one-way ANOVA, while µTBS data were submitted to two-way ANOVA and Tukey's test (α = 0.05). The TBS (MPa) to enamel did not significantly differ among the control (48.1 ± 15.7), GSE5 (46.1 ± 9.6), GSE10 (49.8 ± 13.6) and GSE20 (44.1 ± 11.9) groups (p = 0.537). The µTBS (MPa) to dentin of the control (28.4 ± 14.4) and GSE20 (24.1 ± 8.1) groups were significantly higher than those of the GSE5 (16.8 ± 7.4) and GSE10 (17.5 ± 6.6) groups at 24 h (p < 0.006). After 12-month storage, only GSE5 (21.0 ± 7.8) and GSE10 (17.6 ± 8.0) did not show significantly decreased µTBS (p > 0.145). SEM micrographs showed a shallower enamel etching pattern for GSE5. AFM images showed the formation of collagenous globular structures for GSE5 and GSE10. The different acid solutions did not influence the TBS to enamel, and the µTBS to dentin was stable over time when dentin was etched with GSE5 and GSE10.

Osteointegrative and microgeometric comparison between micro-blasted and alumina blasting/acid etching on grade II and V titanium alloys (Ti-6Al-4V).

This study evaluated the effect of alumina-blasted/acid-etched (AB/AE) or microabrasive blasting (C3-Microblasted) surface treatment on the osseointegration of commercially-pure Ti (grade II) and Ti-6Al-4V alloy (grade V) implants compared to as-machined surfaces. Surface characterization was performed by scanning electron microscopy and optical interferometry (IFM) to determine roughness parameters (Sa and Sq, n = 3 per group). One-hundred forty-four implants were placed in the radii of 12 beagle dogs, for histological (n = 72, bone-to-implant contact - BIC and bone-area-fraction occupancy -BAFO) and torque to interface failure test at 3 and 6 weeks (n = 72). SEM and IFM revealed a significant increase in surface texture for AB/AE and C3-Microblasted surfaces compared to machined surface, regardless of titanium substrate. Torque-to-interface failure test showed significant increase in values from as-machined to AB/AE and to C3-Microblasted. Considering time in vivo, alloy grade, and surface treatment, the C3-microblasted presented higher mean BIC values relative to AB/AE and machined surfaces for both alloy types. BAFO levels were significantly higher for both textured surfaces groups relative to the machined group at 3 weeks, but differences were not significant between the three surfaces for each alloy type at 6 weeks. Surface treatment resulted in roughness that improved osseointegration in Grade II and V titanium substrates.

Effect of grape seed extract-containing phosphoric acid formulations on bonding to enamel and dentin

Abstract The aim was to evaluate the effect of 2% grape seed extract (GSE) containing phosphoric acid (PhA) on the bond strength to enamel and dentin. The control group was 37% PhA. The following three PhA formulations with 2% GSE and 20% ethanol were obtained: GSE5 = 5% PhA; GSE10 = 10% PhA; and GSE20 = 20% PhA. The enamel and dentin surfaces of molars were etched with the acid solutions, followed by Scotchbond Multi-Purpose adhesive and composite resin application. The tensile bond strength (TBS) test evaluated the bond to enamel after 24 h, and the microtensile bond strength (μTBS) test evaluated the bond to dentin after 24 h and 12-month water storage. Etched enamel and dentin were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The TBS data were submitted to one-way ANOVA, while µTBS data were submitted to two-way ANOVA and Tukey's test (α = 0.05). The TBS (MPa) to enamel did not significantly differ among the control (48.1 ± 15.7), GSE5 (46.1 ± 9.6), GSE10 (49.8 ± 13.6) and GSE20 (44.1 ± 11.9) groups (p = 0.537). The µTBS (MPa) to dentin of the control (28.4 ± 14.4) and GSE20 (24.1 ± 8.1) groups were significantly higher than those of the GSE5 (16.8 ± 7.4) and GSE10 (17.5 ± 6.6) groups at 24 h (p < 0.006). After 12-month storage, only GSE5 (21.0 ± 7.8) and GSE10 (17.6 ± 8.0) did not show significantly decreased μTBS (p > 0.145). SEM micrographs showed a shallower enamel etching pattern for GSE5. AFM images showed the formation of collagenous globular structures for GSE5 and GSE10. The different acid solutions did not influence the TBS to enamel, and the µTBS to dentin was stable over time when dentin was etched with GSE5 and GSE10.

Effect of sandblasting and enamel deproteinization on shear bond strength of resin-modified glass ionomer.

INTRODUCTION: The purpose of this study was to compare, in vitro, the shear bond strength of resin-modified glass ionomer (RMGI) bonded to an enamel surface prepared by either sandblasting with 50µm of aluminium oxide particles, deproteinization with 5.25% NaOCl, or by combining both techniques. MATERIAL AND METHODS: One hundred and fifty human premolars were cleaned and randomly divided into five groups. In group 1, the teeth were etched using 37% phosphoric acid and bonded with Transbond XT. In group 2, the teeth were etched using 37% phosphoric acid and bonded with Fuji Ortho LC. In group 3, the teeth were deproteinized with 5.25% NaOCl for one minute then etched with 37% phosphoric acid and bonded with Fuji Ortho LC. In group 4, the enamel was sandblasted with 50µm of aluminium oxide particles for 5seconds prior to etching and bonding with Fuji Ortho LC. In group 5, the teeth were both sandblasted with 50µm of aluminium oxide particles for 5seconds and deproteinized with 5.25% NaOCl for one minute prior to etching using 37% phosphoric acid and bonding with Fuji Ortho LC. The shear bond strength was tested using a universal testing machine with a crosshead speed of 1.0mm/min. The adhesive remnant index (ARI) index was also determined for each group. RESULTS: The mean shear bond strengths were as follows: group 1: 11.33±2.60MPa, group 2: 8.14±2.09, group 3: 9.57±3.25MPa, group 4: 9.49±1.99MPa and group 5: 9.76±2.29MPa (P=0.0001). CONCLUSION: The results show that pre-treating the enamel with either sandblasting, NaOCl, or both, could give a significantly higher shear bond strength than using RMGI with acid etch alone.

Deproteinizing Agents as an Effective Enamel Bond Enhancer-An in Vitro Study.

OBJECTIVE: The aim of this study was to compare the effect of different deproteinizing agents on shear bond strength of composite to primary teeth enamel. STUDY DESIGN: Forty sound primary molars divided in 4 groups of 10 teeth each. In control group 1, enamel was etched for 60 seconds with 37% phosphoric acid and rinsed with water. Group 2: after acid etching deproteinizing agent 5 % sodium hypochlorite was applied for 60 seconds and rinsed. Group 3: after acid etching deproteinizing agent papain gel was applied for 60 seconds and rinsed. Group 4: after acid etching deproteinizing agent bromelain gel applied for 60 seconds and rinsed. Following this, bonding agent was applied to treated enamel surface and composite resin disc were build. Samples were then tested for shear bond strength using Universal Testing Machine. RESULTS: Mean SBS was highest for group 4 and lowest for group 1. No statistically significant difference (p value >0.05) was found between all the four groups. CONCLUSION: Among deproteinizing agents, deproteinization when carried out with bromelain gel and sodium hypochlorite showed effective bond strength as compared to papain.

Influence of root dentin treatment on the push-out bond strength of fibre-reinforced posts

This study evaluates the influence of root dentin treatment with NaOCl alone and combined with EDTA, with and without ultrasound activation, on the push-out bond strength (BS) of fiber-reinforced posts in weakened roots, cemented with RelyX or Panavia. The root canals of 42 maxillary canines were instrumented with Reciproc and 2.5% NaOCl. In the coronal 12mm of all canals, experimental weakening of the roots was produced by reducing dentin thickness with 2.44mm diameter diamond burs. The roots were assigned to 3 groups (n = 14) according to root dentin treatment: 2.5% NaOCl; 2.5% NaOCl + 17% EDTA; and 2.5% NaOCl + 17% EDTA, with solutions agitated using passive ultrasonic irrigation. After cementation of the fiber-reinforced posts the roots were divided in thirds. The first slice of each third was used for the push-out BS test, the second slice for confocal laser scanning microscopy and dentin microhardness (Knoop) analysis. Data were analysed by a two-way ANOVA and Tukey test (a = 0.05). NaOCl + EDTA provided highest BS values than NaOCl (p < 0.0001). Specimens cemented with Panavia presented significantly higher BS than those with RelyX in the three root thirds (p < 0.0001). The highest BS values occurred in the cervical third (p < 0.001). Ultrasound-activated NaOCl + EDTA promoted the greatest reduction in dentin microhardness, followed by NaOCl/EDTA and NaOCl. Ultrasonic activation of NaOCl and EDTA reduced root dentin microhardness, but did not improve the push-out BS of resin-based cements. Panavia presented higher BS than RelyX. RelyX was not influenced by the root dentin treatment protocols.

Influence of root dentin treatment on the push-out bond strength of fibre-reinforced posts

Abstract This study evaluates the influence of root dentin treatment with NaOCl alone and combined with EDTA, with and without ultrasound activation, on the push-out bond strength (BS) of fiber-reinforced posts in weakened roots, cemented with RelyX or Panavia. The root canals of 42 maxillary canines were instrumented with Reciproc and 2.5% NaOCl. In the coronal 12mm of all canals, experimental weakening of the roots was produced by reducing dentin thickness with 2.44mm diameter diamond burs. The roots were assigned to 3 groups (n = 14) according to root dentin treatment: 2.5% NaOCl; 2.5% NaOCl + 17% EDTA; and 2.5% NaOCl + 17% EDTA, with solutions agitated using passive ultrasonic irrigation. After cementation of the fiber-reinforced posts the roots were divided in thirds. The first slice of each third was used for the push-out BS test, the second slice for confocal laser scanning microscopy and dentin microhardness (Knoop) analysis. Data were analysed by a two-way ANOVA and Tukey test (a = 0.05). NaOCl + EDTA provided highest BS values than NaOCl (p < 0.0001). Specimens cemented with Panavia presented significantly higher BS than those with RelyX in the three root thirds (p < 0.0001). The highest BS values occurred in the cervical third (p < 0.001). Ultrasound-activated NaOCl + EDTA promoted the greatest reduction in dentin microhardness, followed by NaOCl/EDTA and NaOCl. Ultrasonic activation of NaOCl and EDTA reduced root dentin microhardness, but did not improve the push-out BS of resin-based cements. Panavia presented higher BS than RelyX. RelyX was not influenced by the root dentin treatment protocols.

Effect of green tea extract on bonding durability of an etch-and-rinse adhesive system to caries-affected dentin.

OBJECTIVE: Green tea extract has been advocated as a matrix metalloproteinase (MMP) inhibitor; however, its effect on bond durability to caries-affected dentin has never been reported. Thus, the aim of this in vitro study was to evaluate the effect of two MMP inhibitors (2% chlorhexidine and 2% green tea extract), applied after acid etching, on bond durability of an etch-and-rinse adhesive system to caries-affected dentin. MATERIAL AND METHODS: Occlusal enamel was removed from third molars to expose the dentin surface, and the molars were submitted to a caries induction protocol for 15 days. After removal of infected dentin, specimens were conditioned with 37% phosphoric acid (15 seconds) and randomly divided into three groups, according to the type of dentin pretreatment (n=10): NT: no treatment; GT: 2% green tea extract; CLX: 2% chlorhexidine. The etch-and-rinse adhesive system (Adper™ Single Bond 2, 3M ESPE, St. Paul, MN, USA) was applied according to the manufacturer's instructions, and composite resin restorations were built on the dentin. After 24 hours, at 37°C, the resin-tooth blocks were sectioned perpendicularly to the adhesive interface in the form of sticks (0.8 mm2 of adhesive area) and randomly subdivided into two groups according to when they were to be submitted to microtensile bond strength (µTBS) testing: immediately or 6 months after storage in distilled water. Data were reported in MPa and submitted to two-way ANOVA for completely randomized blocks, followed by Tukey's test (α=0.05). RESULTS: After 24 hours, there was no significant difference in the µTBS of the groups. After 6 months, the GT group had significantly higher µTBS values. CONCLUSION: It was concluded that the application of 2% green tea extract was able to increase bond durability of the etch-and-rinse system to dentin. Neither the application of chlorhexidine nor non-treatment (NT - control) had any effect on bond strength after water storage.

Accelerated Fatigue Resistance of Thick CAD/CAM Composite Resin Overlays Bonded with Light- and Dual-polymerizing Luting Resins.

PURPOSE: To evaluate the accelerated fatigue resistance of thick CAD/CAM composite resin overlays luted with three different bonding methods. MATERIALS AND METHODS: Forty-five sound human second mandibular molars were organized and distributed into three experimental groups. All teeth were restored with a 5-mm-thick CAD/CAM composite resin overlay. Group A: immediate dentin sealing (IDS) with Optibond FL and luted with light-polymerizing composite (Herculite XRV). Group B: IDS with Optibond FL and luted with dual-polymerizing composite (Nexus 3). Group C: direct luting with Optibond FL and dual-polymerizing composite (Nexus 3). Masticatory forces at a frequency of 5 Hz were simulated using closed-loop servo-hydraulics and forces starting with a load of 200 N for 5000 cycles, followed by steps of 400, 600, 800, 1000, 1200 and 1400 N for a maximum of 30,000 cycles. Each step was applied through a flat steel cylinder at a 45-degree angle under submerged conditions. RESULTS: The fatigue test generated one failure in group A, three failures in group B, and no failures in group C. The survival table analysis for the fatigue test did not demonstrate any significant difference between the groups (p = 0.154). The specimens that survived the fatigue test were set up for the load-to-failure test with a limit of 4600 N. The survival table analysis for the load-to-failure test demonstrates an average failure load of 3495.20 N with survival of four specimens in group A, an average failure load of 4103.60 N with survival of six specimens in group B, and an average failure load of 4075.33 N with survival of nine specimens in group C. Pairwise comparisons revealed no significant differences (p < 0.016 after Bonferroni correction). CONCLUSION: Within the limitations of this in vitro study, it can be concluded that although the dual-polymerizing luting material seems to provide better results under extreme conditions, light-polymerizing luting composites in combination with IDS are not contraindicated with thick restorations.

Porcelain surface conditioning protocols and shear bond strength of orthodontic brackets.

AIM: The objective of the present study was to determine which of six bonding protocols yielded a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets to CAD/CAM lithium disilicate porcelain restorations. A secondary aim was to determine which bonding protocol produced the least surface damage at debond. METHODS: Sixty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular first molar using a CEREC CAD/CAM machine. The samples were split into six test groups, each of which received different mechanical/chemical pretreatment protocols to roughen the porcelain surface prior to bonding a molar orthodontic attachment. Shear bond strength testing was conducted using an Instron machine. The mean, maximum, minimal, and standard deviation SBS values for each sample group including an enamel control were calculated. A t-test was used to evaluate the statistical significance between the groups. RESULTS: No significant differences were found in SBS values, with the exception of surface roughening with a green stone prior to HFA and silane treatment. This protocol yielded slightly higher bond strength which was statistically significant. CONCLUSION: Chemical treatment alone with HFA/silane yielded SBS values within an acceptable clinical range to withstand forces applied by orthodontic treatment and potentially eliminates the need to mechanically roughen the ceramic surface.

Effect of bromelain and papain gel on enamel deproteinisation before orthodontic bracket bonding.

AIM: To test the hypothesis that enamel surface deproteinisation with different concentrations of bromelain in association with 10% papain increases the shear bond strength (SBS) of brackets bonded with orthodontic composite and resin modified glass ionomer cement (RMGIC). MATERIALS AND METHODS: Orthodontic brackets were attached according to the following protocols to 195 bovine incisors, which were acquired and divided into 13 groups: 1) Transbond XT (TXT) according to the manufacturer's recommendations; 2) Deproteinisation with 3% bromelain (BD) plus 10% papain and TXT; 3) 6% BD plus 10% Papain and TXT; 4) RMGIC, without enamel deproteinisation and without acid etching; 5) RMGIC, with 3% BD plus 10% papain and without acid etching; 6) RMGIC, with 6% BD plus 10% papain and without acid etching; 7) attachment using RMGIC following etching with polyacrylic acid; 8) 3% BD plus 10% papain, attachment using RMGIC and etching with polyacrylic acid; 9) 6% BD plus 10% papain, and attachment using RMGIC following etching with polyacrylic acid; 10) etching with 37% phosphoric acid and attachment using RMGIC; 11) 3% BD plus 10% papain, etching with 37% phosphoric acid and attachment using RMGIC; 12) 6% BD plus 10% papain, etching with 37% phosphoric acid and attachment using RMGIC; 13) deproteinisation with 2.5% sodium hypochlorite (NaOCl), etching with polyacrylic acid and RMGIC. After bonding, the brackets were removed by a universal mechanical testing machine, which recorded shear bond strength at failure. The material remaining on the tooth was assessed using the adhesive remnant index (ARI). RESULTS: Deproteinisation with 3% and 6% bromelain gel plus papain significantly increased the shear bond strength (p < 0.05), when acid etching was performed with phosphoric acid, followed by primer application and attachment using Transbond XT (Group 3) and when attached with RMGIC without etching. Deproteinisation with 6% bromelain gel plus papain significantly increased (p < 0.05) the ARI score only when attachment was performed using RMGIC, without etching (Group 6). CONCLUSIONS: Deproteinisation with bromelain associated with papain in a gel increased the shear bond strength and is recommended before orthodontic bracket attachment.

Effect of green tea extract on bonding durability of an etch-and-rinse adhesive system to caries-affected dentin

ABSTRACT Objective Green tea extract has been advocated as a matrix metalloproteinase (MMP) inhibitor; however, its effect on bond durability to caries-affected dentin has never been reported. Thus, the aim of this in vitro study was to evaluate the effect of two MMP inhibitors (2% chlorhexidine and 2% green tea extract), applied after acid etching, on bond durability of an etch-and-rinse adhesive system to caries-affected dentin. Material and Methods Occlusal enamel was removed from third molars to expose the dentin surface, and the molars were submitted to a caries induction protocol for 15 days. After removal of infected dentin, specimens were conditioned with 37% phosphoric acid (15 seconds) and randomly divided into three groups, according to the type of dentin pretreatment (n=10): NT: no treatment; GT: 2% green tea extract; CLX: 2% chlorhexidine. The etch-and-rinse adhesive system (Adper™ Single Bond 2, 3M ESPE, St. Paul, MN, USA) was applied according to the manufacturer's instructions, and composite resin restorations were built on the dentin. After 24 hours, at 37°C, the resin-tooth blocks were sectioned perpendicularly to the adhesive interface in the form of sticks (0.8 mm2 of adhesive area) and randomly subdivided into two groups according to when they were to be submitted to microtensile bond strength (μTBS) testing: immediately or 6 months after storage in distilled water. Data were reported in MPa and submitted to two-way ANOVA for completely randomized blocks, followed by Tukey’s test (α=0.05). Results After 24 hours, there was no significant difference in the μTBS of the groups. After 6 months, the GT group had significantly higher μTBS values. Conclusion It was concluded that the application of 2% green tea extract was able to increase bond durability of the etch-and-rinse system to dentin. Neither the application of chlorhexidine nor non-treatment (NT - control) had any effect on bond strength after water storage.

Bonding Effectiveness of Luting Composites to Different CAD/CAM Materials.

PURPOSE: To evaluate the influence of different surface treatments of six novel CAD/CAM materials on the bonding effectiveness of two luting composites. MATERIALS AND METHODS: Six different CAD/CAM materials were tested: four ceramics - Vita Mark II; IPS Empress CAD and IPS e.max CAD; Celtra Duo - one hybrid ceramic, Vita Enamic, and one composite CAD/CAM block, Lava Ultimate. A total of 60 blocks (10 per material) received various mechanical surface treatments: 1. 600-grit SiC paper; 2. sandblasting with 30-µm Al2O3; 3. tribochemical silica coating (CoJet). Subsequent chemical surface treatments involved either no further treatment (control), HF acid etching (HF), silanization (S, or HF acid etching followed by silanization (HF+S). Two specimens with the same surface treatment were bonded together using two dual-curing luting composites: Clearfil Esthetic Cement (self-etching) or Panavia SA Cement (self-adhesive). After 1 week of water storage, the microtensile bond strength of the sectioned microspecimens was measured and the failure mode was evaluated. RESULTS: The bonding performance of the six CAD/CAM materials was significantly influenced by surface treatment (linear mixed models, p < 0.05). The luting cement had a significant influence on bond strength for Celtra Duo and Lava Ultimate (linear mixed models, p < 0.05). Mechanical surface treatment significantly influenced the bond strength for Celtra Duo (p = 0.0117), IPS e.max CAD (p = 0.0115), and Lava Ultimate (p < 0.0001). Different chemical surface treatments resulted in the highest bond strengths for the six CAD/CAM materials: Vita Mark II and IPS Empress CAD: S, HF+S; Celtra Duo: HF, HF+S; IPS e.max CAD: HF+S; Vita Enamic: HF+S, S. For Lava Ultimate, the highest bond strengths were obtained with HF, S, HF+S. Failure analysis showed a relation between bond strength and failure type: more mixed failures were observed with higher bond strengths. Mainly adhesive failures were noticed if no further surface treatment was done. The percentage of adhesive failures was higher for CAD/CAM materials with higher flexural strength (Celtra Duo, IPS e.max CAD, and Lava Ultimate). CONCLUSION: The bond strength of luting composites to novel CAD/CAM materials is influenced by surface treatment. For each luting composite, an adhesive cementation protocol can be specified in order to obtain the highest bond to the individual CAD/CAM materials.

Fracture Strength of Endodontically Treated Teeth Restored with Composite Overlays with and without Glass-fiber Reinforcement.

PURPOSE: To evaluate the fracture strength and the failure mode of endodontically treated teeth restored with composite resin overlays with and without glass-fiber reinforcement. MATERIALS AND METHODS: A total of 32 extracted molars were divided into four equal groups. In the NFR-NFRC (no foundation restoration, no fiber-reinforced composite) and NFR-FRC (no foundation restoration, fiber-reinforced composite) groups, only a 5-mm-thick composite resin layer sealed the pulp chamber floors, whereas in the FR-NFRC (foundation restoration, no fiber-reinforced composite) and FR-FRC (foundation restoration, fiber-reinforced composite) groups, a 3.0-mm foundation restoration was used. NFR-NFRC and FR-NFRC groups were restored with composite resin overlays, whereas NFR-FRC and FR-FRC groups were restored with fiber-reinforced composite resin overlays. All specimens were subjected to mechanical loading in a computer-controlled masticator and then the fracture resistance was evaluated. Differences in means were compared using two-way ANOVA and Tukey's test. The level of significance was set at ɑ = 0.05. RESULTS: All specimens successfully completed the fatigue test. The least fracture-resistant group was NFR-FRC, exceeded by FR-NFRC, NFR-NFRC, and FR-FRC, in that order, with FR-FRC being the most fracture-resistant group. Statistically significant differences were detected between the pairs NFR-NFRC/FR-FRC (p = 0.001), NFR-FRC/FR-FRC (p = 0.001), and FR-NFRC/FR-FRC (p = 0.001). Eight vertical root fractures occurred in group FR-NFRC, six in group NFR-NFRC, four in group NFR-FRC, and none occurred in group FR-FRC. CONCLUSIONS: Within the limitations of this in vitro study, the incorporation of glass fibers and the presence of a foundation restoration were found to increase the fracture resistance and can favorably influence the fracture mode.

Influence of Surface Conditioning Protocols on Reparability of CAD/CAM Zirconia-reinforced Lithium Silicate Ceramic.

PURPOSE: To test the effect of surface conditioning protocols on the reparability of CAD/CAM zirconia-reinforced lithium silicate ceramic compared to lithium-disilicate glass ceramic. MATERIALS AND METHODS: Zirconia-reinforced lithium silicate ceramic (Vita Suprinity) and lithium disilicate glass-ceramic blocks (IPS e.max CAD) were categorized into four groups based on the surface conditioning protocol used. Group C: no treatment (control); group HF: 5% hydrofluoric acid etching for 60 s, silane (Monobond-S) application for 60 s, air drying; group HF-H: 5% HF acid etching for 60 s, application of silane for 60 s, air drying, application of Heliobond, light curing for 20 s; group CO: sandblasting with CoJet sand followed by silanization. Composite resin (Tetric EvoCeram) was built up into 4 x 6 x 3 mm blocks using teflon molds. All specimens were subjected to thermocycling (5000x, 5°C to 55°C). The microtensile bond strength test was employed at a crosshead speed of 1 mm/min. SEM was employed for evaluation of all the debonded microbars, the failure type was categorized as either adhesive (failure at adhesive layer), cohesive (failure at ceramic or composite resin), or mixed (failure between adhesive layer and substrate). Two-way ANOVA and the Tukey's HSD post-hoc test were applied to test for significant differences in bond strength values in relation to different materials and surface pretreatment (p < 0.05). RESULTS: The highest microtensile repair bond strength for Vita Suprinity was reported in group CO (33.1 ± 2.4 MPa) and the lowest in group HF (27.4 ± 4.4 MPa). Regarding IPS e.max CAD, group CO showed the highest (30.5 ± 4.9 MPa) and HF the lowest microtensile bond strength (22.4 ± 5.7 MPa). Groups HF, HF-H, and CO showed statistically significant differences in terms of all ceramic types used (p < 0.05). The control group showed exclusively adhesive failures, while in HF, HF-H, and CO groups, mixed failures were predominant. CONCLUSIONS: Repair bond strength to zirconia-reinforced lithium silicate ceramics and lithium-disilicate glass ceramic could be improved when ceramic surfaces are sandblasted with CoJet sand followed by silanization.

Pit and Fissure Sealant Retention Following Air Abrasion Preparation with Bioactive Glass and Aluminum Oxide Particles.

PURPOSE: Alumina air abrasion is an alternative for acid-etch technique for tooth preparation before placement of a fissure sealant. The aim of this study was to compare the retention of sealants placed subsequent to air abrasion with alumina and bioactive glass (BAG) particles. METHODS: Sixty-two 6-12 year old children were included in this study. Using a halfmouth design, the fissures were prepared using air abrasion with alumina particles on randomly assigned permanent mandibular or/and maxillary first molars on one side of the mouth (Group 1) and air abrasion with BAG on the contralateral side of the mouth (Group 2). Sealants were applied on 180 teeth, and were scored as missing, partially retained, and completely retained after three, six, nine and 12 months. Data were analyzed using Friedman and Wilcoxon tests (α=0.05). RESULTS: Sealant retention rates in the alumina group were higher than those in the BAG group at all time periods (P<0.001). CONCLUSIONS: Sealant retention after air abrasion with alumina particles was higher than BAG over 12 months.

Effect of Adhesive Resin Type for Bonding to Zirconia Using Two Surface Pretreatments.

PURPOSE: This laboratory study evaluated the short-term adhesive properties of one 10-MDP-containing and two MDP-free resin composite cements, using two types of zirconia surface pretreatments. MATERIALS AND METHODS: Eighteen sintered zirconia disks (Procera, Nobel Biocare) were randomly divided into three study groups according to their surface treatment: (a) polished surface (control group); (b) airborne-particle abraded (grit blasted) with 50-µm aluminum trioxide (APA); and (c) selective infiltration etching (SIE). The zirconia disks were then bonded to 180 pre-aged composite resin disks (0.9 mm×0.7 mm) using three different resin composite cements (Panavia F2.0, Esthetic, and Aegis). Resin-zirconia adhesion strength was evaluated using the microshear bond strength test (µSBS) after 24 h (baseline) and 2 weeks of storage in deionized water at 37°C. Three-way ANOVA, one-way ANOVA, and Scheffé's post-hoc tests were used to analyze the data (p=0.05). RESULTS: Surface treatments significantly influenced the µSBS (p<0.001). The highest mean µSBS values were recorded with the MDP-containing resin composite cement (Panavia F2.0) in both SIE (32.4±5.3 MPa) and APA (28.6±8.8 MPa) groups. Water storage significantly reduced the bond strength obtained with the MDP-free cements (Esthetic and Aegis) and in the control group, while the bond strength in SIE and APA groups using the 10- MDP-containing resin composite cement exhibited relatively unchanged values. CONCLUSION: SIE and APA in combination with the 10-MDP-containing resin composite cement established a strong, durable bond to zirconia substrates under short-term aging conditions. The cement containing amorphous calcium phosphate (Aegis) did not bond to zirconia surfaces. During the observation period, µSBS decreased significantly due to hydrolytic degradation, except when the 10-MDP-containing resin composite cement (Panavia F2.0) was used in the SIE and APA groups.