Comparative in-vivo bond failure rate of orthodontic brackets when bracket base is treated with micro-abrasive blasting vs. acid etching: eighteen month randomized control trial and scanning electron microscope study.

Background: The aim of this study was threefold. Firstly, it aimed to introduce and detail a novel method for chemically etching the bases of stainless-steel orthodontic brackets. Secondly, the study sought to investigate the structural alterations within the brackets' microstructure following chemical etching compared to those with sandblasted bases, using electron microscopy analysis. Lastly, the study aimed to evaluate and compare the long-term durability and survivability of orthodontic brackets with chemically etched bases versus those with sandblasted bases, both bonded using the conventional acid etch technique with Transbond XT adhesive, over an 18-month follow-up period. Methods: The study was a randomized clinical control trial with triple blinding and split-mouth study design and consisted of two groups. The brackets in the sandblasted group were prepared by sandblasting the intaglio surface of the base of the bracket with 50 µm SiO2 particles. Hydrofluoric acid was used to roughen the base in the acid-etched group. The bases of the brackets were viewed under an electron microscope to analyze the topographical changes. Results: A total of 5,803 brackets (3,006 acid-etch, 2,797 sandblasted) in 310 patients were bonded, in a split-mouth design by the same operator. The patients were followed for 18 months. The failure rate of 2.59% and 2.7% was noted in an acid-etched and sandblasted group, respectively. There was a close approximation of curves in the Kaplan-Meier plot, and the survival distribution of the two groups in the log-rank (Mantel-Cox) test was insignificant; x2 = 0.062 (P value = 0.804). Conclusion: Acid etching if the bases of the brackets can be used as an alternative to sandblasting furthermore acid etching can be performed on the chair side.

Effect of surface treatment strategies on bond strength of additively and subtractively manufactured hybrid materials for permanent crowns.

OBJECTIVES: The purpose of this study is to evaluate the bond strength of different computer-aided design / computer-aided manufacturing (CAD/CAM) hybrid ceramic materials following different pretreatments. METHODS: A total of 306 CAD/CAM hybrid material specimens were manufactured, n = 102 for each material (VarseoSmile Crownplus [VSCP] by 3D-printing; Vita Enamic [VE] and Grandio Blocs [GB] by milling). Each material was randomly divided into six groups regarding different pretreatment strategies: control, silane, sandblasting (50 µm aluminum oxide particles), sandblasting + silane, etching (9% hydrofluorics acid), etching + silane. Subsequently, surface roughness (Ra) values, surface free energy (SFE) were measured. Each specimen was bonded with a dual-cured adhesive composite. Half of the specimens were subjected to thermocycling (5000 cycles, 5-55 °C). The shear bond strength (SBS) test was performed. Data were analyzed by using a two-way analysis of variance, independent t-test, and Mann-Whitney-U-test (α = 0.05). RESULTS: Material type (p = 0.001), pretreatment strategy (p < 0.001), and the interaction (p < 0.001) all had significant effects on Ra value. However, only etching on VSCP and VE surface increased SFE value significantly. Regarding SBS value, no significant difference was found among the three materials (p = 0.937), while the pretreatment strategy significantly influenced SBS (p < 0.05). Etching on VSCP specimens showed the lowest mean value among all groups, while sandblasting and silane result in higher SBS for all test materials. CONCLUSIONS: The bond strength of CAD/CAM hybrid ceramic materials for milling and 3D-printing was comparable. Sandblasting and silane coupling were suitable for both millable and printable materials, while hydrofluoric etching should not be recommended for CAD/CAM hybrid ceramic materials. CLINICAL RELEVANCE: Since comparable evidence between 3D-printable and millable CAD/CAM dental hybrid materials is scarce, the present study gives clear guidance for pretreatment planning on different materials.

[Impact of chemical surface treatment of samples made of domestic zirconium dioxide on adhesive strength]. / Vliyanie khimicheskikh metodov podgotovki poverkhnosti obraztsov iz otechestvennogo dioksida tsirkoniya na pokazateli adgezionnoi prochnosti.

Ceramic based on zirconium dioxide (ZD) is a modern, durable material for the manufacture of dentures. It is known that ZD is not etched as glass-ceramic, making it difficult to prepare this material before fixing. OBJECTIVE: To study the impact of various methods of surface treatment of ZD-based ceramic on adhesive strength. MATERIALS AND METHODS: Sandblasting with Al2O3 particles sized 50 µm and application of primers with 10-MDP phosphate monomer were used. Adhesive strength values for following 4 groups of samples were obtained: 1st group - RelyX U200 + sandblasting + Compofix new primer (n=9); 2nd group - Compofix + sandblasting + Compofix new primer (n=9); 3rd group - Panavia F 2.0 + sandblasting (n=9); 4th group (control) - Variolink Esthetic DC + sandblasting + Monobond Plus primer (n=9). RESULTS: The highest strength of adhesion was in the 4th group - 48.71±5.71MPa, the smallest in the 3rd group - 9.49±35.24 MPa. Fully domestic components used in the 2nd group allowed to obtain values of 42.50±9.79 MPa. Adhesive strength in the 1st group was 34.11±4.78 MPa. CONCLUSION: The absence of the 10-MDP-based primers application in the preparation of ZD ceramic reduces the adhesive strength between resin cement and its surface. The domestic set for fixation of dentures can be effectively used for ZD on the same basis as European analogue.

Sandblasting increases the microtensile bond strength between resin and sclerotic dentin in noncarious cervical lesions.

PURPOSE: To evaluate the effect of sandblasting on the microtensile strength between sclerotic dentin and resin composite. METHODS: 32 premolars with noncarious cervical lesions (NCCLs) were collected, and the teeth were randomly assigned to the control group (C group) and the sandblasted group (S group). Teeth in the S group were sandblasted with 110 µm Al2O3 particles at a pressure of 75 psi, while those in the C group received no further treatment. The characteristics of the tooth surface were observed by scanning electron microscopy (SEM), and the relative area of open dentin tubules (OTs) was calculated by IPP6.0 software. Surface roughness (Ra) was also assessed. The noncarious cervical lesions of all teeth were restored with a resin composite and subsequently sectioned into sticks to measure the microtensile bond strength (µTBS). RESULTS: The mean ± SD µTBS (in MPa) of the sandblasted group was 17.9 ± 0.69 and 14.23 ± 0.44 in the control group (P< 0.05). The relative area of OTs at the gingival wall of the sandblasted group was 69.74 ± 5.23%, and 47.24 ± 7.67% in the control group (P< 0.05). The average surface roughness (µm) was 1.01 ± 0.05 in the sandblasted group and 0.16 ± 0.03 in the control group. Sandblasting could increase the bond strength of sclerotic dentin and resin restorations. CLINICAL SIGNIFICANCE: After sandblasting, the microtensile strength of sclerotic dentin on the surface of noncarious cervical lesions increased, prolonging the resin adhesion longevity. Sandblasting could also alleviate the pain of patients during the treatment process and achieve a minimally invasive treatment.

The influence of Zircos-E® etchant, silica coating, and alumina air-particle abrasion on the debonding resistance of endocrowns with three different preparation designs.

OBJECTIVES: The study aimed to evaluate the debonding resistance of three different endocrown designs on molar teeth, using three different zirconia surface pretreatments. MATERIAL AND METHOD: Ninety human mandibular first molars were divided into three main groups: endocrowns without ferrule, with 1 mm ferrule, and with 2 mm ferrule. The subgroups were defined by their surface pretreatment method used (n = 15): 50 µm alumina air-particle abrasion, silica coating using 30 µm Cojet™ particles, and Zircos-E® etching. The endocrowns were fabricated using multilayer zirconia ceramic, cemented with self-adhesive resin cement, and subjected to 5000 thermocycles (5-55°C) before debonding. The data obtained were analyzed using a two-way ANOVA. RESULTS: All test specimens survived the thermocyclic aging. The results indicated that both the preparation design and the surface treatment had a significant impact on the resistance to debonding of the endocrowns (p < .001). The 2 mm ferrule followed by the 1 mm ferrule designs exhibited the highest debonding resistance, both were superior to the endocrown without ferrule. Zircos-E® etching and silica coating yielded comparable debonding resistance, which were significantly higher than alumina air-particle abrasion. All endocrowns demonstrated a favorable failure mode. CONCLUSIONS: All designs and surface treatments showed high debonding resistance for a single restoration. However, ferrule designs with Zircos-E® etching or silica coating may represent better clinical options compared to the nonferrule design or alumina airborne-particle abrasion. Nonetheless, further research, including fatigue testing and evaluations with different luting agents is recommended.

Effect of surface treatment and resin cement type on the bond strength of polyetheretherketone to lithium disilicate ceramic.

BACKGROUND: This study aims to evaluate the effect of surface treatment and resin cement on the shear bond strength (SBS) and mode of failure of polyetheretherketone (PEEK) to lithium disilicate ceramic (LDC). This is suggested to study alternative veneering of PEEK frameworks with a ceramic material. METHODS: eighty discs were prepared from PEEK blank and from lithium disilicate ceramic. Samples were divided into four groups according to surface treatment: Group (A) air abraded with 110 µm Al2O3, Group (AP) air abrasion and primer application, Group (S) 98% sulfuric acid etching for 60 s, Group (SP) Sulfuric acid and primer. Each group was subdivided into two subgroups based on resin cement type used for bonding LDC:1) subgroup (L) self- adhesive resin cement and 2) subgroup (B) conventional resin cement (n = 10). Thermocycling was done for all samples. The bond strength was assessed using the shear bond strength test (SBS). Failure mode analysis was done at 50X magnification with a stereomicroscope. Samples were chosen from each group for scanning electron microscope (SEM). The three-way nested ANOVA followed by Tukey's post hoc test were used for statistical analysis of results. Comparisons of effects were done utilizing one way ANOVA and (p < 0.05). RESULTS: The highest mean of shear bond strength values was demonstrated in Group of air abrasion with primer application using conventional resin cement (APB) (12.21 ± 2.14 MPa). Sulfuric acid groups showed lower shear bond strength values and the majority failed in thermocycling especially when no primer was applied. The failure mode analysis showed that the predominant failure type was adhesive failure between cement and PEEK, while the remaining was mixed failure between cement and PEEK. CONCLUSION: The air abrasion followed by primer application and conventional resin cement used for bonding Lithium Disilicate to PEEK achieved the best bond strength. Primer application did not have an effect when self-adhesive resin cement was used in air-abraded groups. Priming step is mandatory whenever sulfuric acid etching surface treatment is utilized for PEEK.

Five-year Clinical Evaluation of Universal Adhesives in Noncarious Cervical Lesions.

OBJECTIVES: To compare the clinical performance of mildly acidic universal adhesives Scotchbond Universal (SU, 3M Oral Care, St Paul, MN, USA) and Prime & Bond Elect (PBE, Dentsply Sirona, Charlotte, NC, USA) in the restoration of noncarious cervical lesions (NCCLs). METHODS AND MATERIALS: A total of 63 patients in need of 203 NCCL restorations participated in this randomized controlled clinical trial. Notch-shaped lesions were restored with Kalore (GC Corporation, Tokyo, Japan) after application of either SU or PBE, following the etch-and-rinse (ER) or self-etch (SE) techniques. Subjects were followed up for 60 months. The focus of the statistical analyses was on the change of outcome over time as assessed by the Modified USPHS rating system (ie, Alfa vs Bravo + Charlie outcomes). Logistic regression was performed for each outcome separately with compound symmetric variance-covariance structure assumed to consider a correlation of restorations within subjects. All analyses were conducted using SAS 9.4 (SAS, Cary, NC, USA). RESULTS: One-hundred twenty-nine teeth in 35 subjects were assessed at the 60-month follow-up. In addition, three restorations that failed prior to the 60-month evaluation, two of which were in subjects who did not present for the 60-month follow-up, were included in the statistical analysis. In total, two restorations in the SU_ER group and three restorations in the PBE_SE group failed the retention category. Statistically significant differences were obtained for the comparison of restorations in the PBE_SE and PBE_ER groups, where the former was 58% less likely to maintain a score of Alfa for marginal discoloration than the latter. CONCLUSIONS: SU and PBE demonstrated acceptable clinical performance at 60 months with regard to restoration retention. Phosphoric-acid etching of the NCCLs prior to adhesive application significantly improved the performance of PBE in regard to marginal discoloration.

Efficacy of adhesive strategies for restorative dentistry: A systematic review and network meta-analysis of double-blind randomized controlled trials over 12 months of follow-up.

PURPOSE: The efficacy of etch-and-rinse, selective enamel-etching, and self-etching protocols for universal adhesives in follow-ups of over 12 months was compared in a network meta-analysis. STUDY SELECTION: Randomized controlled trials (RCTs) published from 1998 to 2022 that compared marginal staining, marginal adaptation, retention and fractures, post-operative sensitivity, or recurrence of caries that took place over 12-months post-restoration were selected. A network meta-analysis determined the performance of each adhesive protocol. RESULTS: After screening 981 articles, 16 RCTs were subjected to data extraction. Of which, 674 patients with 2816 restorations, were included in the network meta-analysis. The pooled risk of marginal discoloration following self-etching was significantly higher than that following etch-and-rinse at over 12, 24, and 36 months, which was time-dependent. The pooled risks of unfavorable marginal adaptation and unfavorable retention and fractures following self-etching were also significantly higher than that following etch-and-rinse, with the rates of unfavorable retention and fractures in non-carious cervical lesions increasing in a time-dependent manner. The pooled risks of marginal discoloration, unfavorable marginal adaptation, retention and fractures were similar between etch-and-rinse and selective enamel-etching protocols. Post-operative hypersensitivity and recurrence of caries were not significantly different among etch-and-rinse, selective enamel-etching, and self-etching protocols. CONCLUSIONS: In follow-ups over 12 months, esthetic and functional outcomes of restorations completed with an etch-and-rinse adhesive protocol were superior to the ones achieved with a self-etching strategy without selective enamel-etching. Selective enamel etching is recommended for self-etching systems. Biological responses were similar for all three adhesive strategies.

Shear bond strength of metallic orthodontic brackets to zirconium crowns treated by sandblasting compared to enamel using a universal adhesive: An in vitro study.

OBJECTIVES: Orthodontic brackets are increasingly bonded to the surface of zirconium crowns due to the growing aesthetic demands in adults' restorations. Therefore, providing a reliable bond between these substrates is of great importance. This study aimed at investigating the shear bond strength (SBS) of orthodontic metal brackets bonded to zirconium treated by sandblasting. In addition, the value was compared with SBS between metal brackets and enamel. MATERIALS AND METHODS: Samples were divided into three groups including first premolar enamel specimens (n=20), untreated zirconium blocks (n=20) and sandblasted zirconium blocks (n=20). Enamel specimens underwent etching and bonding procedures using 37% phosphoric acid and 3M™ Scotchbond™ Universal adhesive. Zirconium blocks were randomly allocated to two groups. The first group was prepared by sandblasting with 50µm aluminium oxide particles (Al2O3) under 4 bars pressure followed by bonding brackets with 3M™ Scotchbond™ Universal adhesive. Metal brackets were also bonded to the untreated zirconium group using the same adhesive. All samples underwent thermocycling, and SBS was calculated using a universal testing machine with a crosshead speed of 1mm/min. Data were analysed using One-way Anova and Tukey's tests. RESULTS: The highest SBS was recorded in sandblasted zirconium group (26.17±8.22MPa) followed by enamel group (23.667±7.00MPa) and untreated zirconium group (11.49±7.00MPa). There was a significant difference between the SBS of untreated zirconium and that of two other groups. CONCLUSION: Perfect SBS was achieved by sandblasting pre-treatment, comparable to that of enamel. Therefore, sandblasting of zirconium crowns is recommended prior to bonding orthodontic brackets.

Polifluoruro de amonio como alternativa de acondicionamiento para laminados ultradelgados de disilicato de litio. Reporte de caso / Ammonium polyfluoride as an alternative for the surface conditioning of ultrathin lithium disilicate veneers. A case report

RESUMEN: Los laminados vitrocerámicos ultradelgados constituyen una alternativa conservadora para la resolución de alteraciones estéticas. Sin embargo, su acondicionamiento con ácido fluorhídrico suele no estar exento de complicaciones, por lo que el uso de un sistema autograbante en base a polifluoruro de amonio (Monobond Etch&Prime, MEP) permite disminuir el riesgo de sobregrabado, simplificando la técnica. El presente reporte presenta el seguimiento a dieciocho meses de un caso clínico resuelto mediante laminados vitrocerámicos acondicionados únicamente con MEP. Caso. Paciente joven con alteraciones estéticas en el sector anterosuperior. Se realizaron preparaciones conservadoras para la confección de laminados ultradelgados en disilicato de litio (e.maxPress). Las vitrocerámicas fueron acondicionadas sólo con MEP y se cementaron con Variolink Esthetic LC. Al año y medio las restauraciones se observaron indemnes, manteniendo un buen ajuste marginal y ausencia de tinciones. Conclusiones. MEP aparece como una alternativa prometedora para reemplazar al ácido fluorhídrico en la cementación de laminados vitrocerámicos.

ABSTRACT: Ultrathin glass-ceramic veneers are a conservative approach for the restorative treatment of aesthetic disorders in the anterior region. However, surface conditioning with hydrofluoric acid of the thin structures can be usually a challenging step. Therefore, the use of a self-etching ceramic primer containing ammonium polyfluoride (Monobond Etch&Prime, MEP) offers a simplified technique with a reduced risk of overetching. Here we present an 18-month follow-up of ultrathin glass-ceramic veneers conditioned with MEP only. Case. Young female patient with an aesthetic disorder in the front region. The four upper incisors were conservatively prepared for ultrathin lithium disilicate (e.maxPress) veneers. Pre-treatment of the glass-ceramics consisted only of MEP application, followed by adhesive cementation with Variolink Esthetic LC. At the 1.5-year recall, the restorations appeared undamaged, with no marginal gap or staining. Conclusions. MEP constitutes a promising alternative to hydrofluoric acid for the adhesive cementation of glass-ceramic veneers.

Resin-dentin bond stability of etch-and-rinse adhesive systems with different concentrations of MMP inhibitor GM1489.

Enzymatic degradation of the hybrid layer can be accelerated by the activation of dentin metalloproteinases (MMP) during the bonding procedure. MMP inhibitors may be used to contain this process. Objective To evaluate the degree of conversion (DC%), dentin bond strength (µTBS) (immediate and after 1 year of storage in water), and nanoleakage of an experimental (EXP) and a commercial (SB) adhesive system, containing different concentrations of the MMP inhibitor GM1489: 0, 1 µM, 5 µM and 10 µM. Methodology DC% was evaluated by FT-IR spectroscopy. Dentin bond strength was evaluated by µTBS test. Half of beams were submitted to the µTBS test after 24 h and the other half, after storage for 1 year. From each tooth and storage time, 2 beams were reserved for nanoleakage testing. Data were analyzed using ANOVA and Tukey's test to compare means (α=0.05). Results All adhesive systems maintained the µTBS after 1 year of storage. Groups with higher concentrations of inhibitor (5 µM and 10 µM) showed higher µTBS values than groups without inhibitor or with 1 µM. The nanoleakage values of all groups showed no increase after 1 year of storage and values were similar for SB and EXP groups, in both storage periods. The inhibitor did not affect the DC% of the EXP groups, but the SB5 and SB10 groups showed higher DC% values than those of SB0 and SB1. Conclusions The incorporation of GM1489 in the adhesive systems had no detrimental effect on DC%. The concentrations of 5 µM GM1489 for SB and 5 µM or 10 µM for EXP provided higher µTBS than groups without GM1489, in the evaluation after 1 year of storage; whereas the concentration of inhibitor did not affect adhesive systems nanoleakage.

Depth of acid penetration and enamel surface roughness associated with different methods of interproximal enamel reduction.

OBJECTIVES: To assess and compare the enamel surface quality after interproximal enamel reduction (IPR) was performed with different systems and to study the relation between acid penetration depth and enamel surface quality as well as the importance of remineralization. METHODS: Sixty-five extracted teeth were randomly allocated to five experimental groups: untreated control, manual with New Metal Strips, mechanical with oscillating segment (OS) discs, Safe-Tipped Bur Kit, and the Ortho-Strip, followed by 30 s of polishing with the Softflex system and the Compo-system after treating the tooth with OS discs. Mesial surfaces were demineralized for 24 h and distal surfaces were subjected to interchanging demineralization and remineralization cycles of 24 h each for 18 days. The analysis was carried out by profilometry, scanning electron microscopy, and polarization microscopy. RESULTS: After IPR and polishing, enamel roughness was reduced for all systems tested except for the Essix Safe-Tipped Bur Kit. Subsequent demineralization increased enamel roughness in all groups except controls beyond the original level prior to IPR except for IPR with New Metal Strips or Ortho-Strips and subsequent polishing. Cyclic demineralization and remineralization for 18 days yielded a reduction in acid penetration depth and an increase in surface smoothness, which correlated with each other only for controls and treatment with New Metal Strips or Ortho-Strips. CONCLUSIONS: Manual IPR, using New Metal Strips and, even more, the oscillating IPR system Ortho-Strips, yielded smoother interproximal enamel surfaces and less acid penetration depth than the IPR systems with OS discs and the Safe-Tipped Bur Kit after polishing and 18 days of cyclic demineralization and remineralization. Irrespective of the IPR procedure, proper remineralization of IPR-treated surfaces is advisable to reduce caries susceptibility.

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.

Resin-dentin bond stability of etch-and-rinse adhesive systems with different concentrations of MMP inhibitor GM1489

Abstract Enzymatic degradation of the hybrid layer can be accelerated by the activation of dentin metalloproteinases (MMP) during the bonding procedure. MMP inhibitors may be used to contain this process. Objective To evaluate the degree of conversion (DC%), dentin bond strength (µTBS) (immediate and after 1 year of storage in water), and nanoleakage of an experimental (EXP) and a commercial (SB) adhesive system, containing different concentrations of the MMP inhibitor GM1489: 0, 1 µM, 5 µM and 10 µM. Methodology DC% was evaluated by FT-IR spectroscopy. Dentin bond strength was evaluated by µTBS test. Half of beams were submitted to the µTBS test after 24 h and the other half, after storage for 1 year. From each tooth and storage time, 2 beams were reserved for nanoleakage testing. Data were analyzed using ANOVA and Tukey's test to compare means (α=0.05). Results All adhesive systems maintained the µTBS after 1 year of storage. Groups with higher concentrations of inhibitor (5 µM and 10 µM) showed higher µTBS values than groups without inhibitor or with 1 µM. The nanoleakage values of all groups showed no increase after 1 year of storage and values were similar for SB and EXP groups, in both storage periods. The inhibitor did not affect the DC% of the EXP groups, but the SB5 and SB10 groups showed higher DC% values than those of SB0 and SB1. Conclusions The incorporation of GM1489 in the adhesive systems had no detrimental effect on DC%. The concentrations of 5 µM GM1489 for SB and 5 µM or 10 µM for EXP provided higher μTBS than groups without GM1489, in the evaluation after 1 year of storage; whereas the concentration of inhibitor did not affect adhesive systems nanoleakage.

Do ozonated water and boric acid affect the bond strength to dentin in different adhesive systems?

AIM: The aim of this in vitro study was to compare the effects of the application of three different cavity disinfecting agents to dentin on the micro-shear bond strength (µ-SBS) of one self-etch and two universal adhesive systems. MATERIALS AND METHODS: In total, 120 caries-free human permanent molar teeth were used in this study. Mid-coronal dentin surfaces were revealed by cutting occlusal enamel and a standard smear layer was obtained by using 600-800-1200 grid silicon carbide abrasive papers. Specimens were randomly assigned to four groups according to the disinfectant used: Group 1: Control (no disinfectant); Group 2: 2% chlorhexidine based (Consepsis); Group 3: 10 ppm ozonated water (TeknO3zone); Group 4: 5% boric acid (Handmade). Each group was divided into three subgroups according to the type of adhesive (Clearfil SE Bond, OptiBond XTR, and Tokuyama Universal). Specimens were bonded using either Clearfil SE Bond, OptiBond XTR or Tokuyama Universal, which were employed according to the manufacturer's instructions. Resin composite microcylinders were bonded using Tygon® tubes for µ-SBS testing. After specimens were stored for 24 h, at 37°C in distilled water, µ-SBS test was measured with a universal test machine (LF Plus, Lloyd, Instrument). µ-SBS results were analyzed by one-way analysis of variance (ANOVA) and Tukey's tests. RESULTS: When the mean microshear bond strength values of the control group were compared, the difference between the subgroups was not significant (P < 0.05). When the mean microshear bond strength values of the chx, ozonated water, and boric acid were compared, the difference between Clearfil SE Bond and Tokuyama Universal was significant (P < 0.05) and the difference between the other groups was not significant (P > 0.05). CONCLUSION: Ozonated water and boric acid may be as an alternative to other materials used as cavity disinfectants.

Effect of surface treatments to remove temporary cement remnants on the bond strength between the core composite and resin cement.

BACKGROUND: There was no enough data about the appropriate surface cleaning of core composite material after temporary cementation. AIM: To evaluate the effects of surface cleaning techniques on initial shear bond strength (SBS) between core composite material and resin nanoceramic crown materials after temporary cementation. MATERIAL AND METHODS: Cubic specimens were prepared from prosthetic materials, including Lava Ultimate. Cylinder-shaped composites were cemented to glass slides with eugenol-free temporary cement, resulting in a total of 44 cylinders (n = 11). The surfaces of composite cylinders were then cleaned with an Er, Cr:YSGG laser, 37% orthophosphoric acid, yellow tape diamond bur, or dental explorer. Cleaned cylinders were bonded to cubic specimens with resin cement. Initial SBS tests were performed with a universal testing machine at 0.5 mm/min crosshead speed. One-way ANOVA and post hoc Tukey tests were used to analyze the obtained data (P =0.05). RESULTS: Initial SBS values were significantly affected by the different surface cleaning methods (P <.05). The highest SBS value was obtained with the laser group (SBS = 17.14), while the lowest was obtained with dental explorer group (SBS = 5.95). There was no significant difference between the diamond bur group and the laser group (P =0.982). CONCLUSIONS: Laser irradiation or yellow tape diamond bur cleaning of the core composite surface could be recommended to strengthen bond strength between the resin luting cement and the core composite. Before adhesive or conventional cementation of prosthetic restoration, the core composite surface should be cleaned.

Assessment of microcracks and shear bond strength after debonding orthodontic ceramic brackets on enamel priorly etched by different Er,Cr:YSGG and Er:YAG laser settings without acid application: An in vitro study.

BACKGROUND DATA: Enamel microcrack formation has a high incidence after mechanical debonding of ceramic brackets. This may be due to high delivered shear bond strength values when enamel is priorly etched by phosphoric acid. It is still not well elucidated in the literature if laser etching affects enamel the same way. The aim of the research was to analyze different Er,Cr:YSGG and Er:YAG laser etching settings as an alternative to phosphoric acid, in an attempt to prevent enamel microcrack formation during laser etching and mechanical debonding, while reducing the shear bond strength to the minimal clinical acceptable value. MATERIALS AND METHODS: One hundred and thirty-three teeth were randomly divided into 7 experimental groups according to their etching modalities. Settings used for enamel etching were in Er,Cr:YSGG groups: Er,Cr:YSGG (1.5Watt, W/20Hertz, Hz); Er,Cr:YSGG (1.5W/15Hz) and Er,Cr:YSGG (2W/20Hz) and settings used for enamel etching in Er:YAG groups were: Er:YAG (60 millijoules, mJ), Er:YAG (80mJ) and Er:YAG (100mJ). Group C etched with 37% phosphoric acid served as control. Microscopic analysis was performed to assess presence of enamel microcracks. Shear bond strength was evaluated after thermocycling using Weibull survival analysis. RESULTS: All groups showed a reduction in additional microcracks after debonding when compared to control, but only group Er:YAG (60mJ) exhibited a statistically significant difference. Groups Er:YAG (80mJ), control and Er:YAG (100mJ) showed respectively the highest probability of survival at various stress levels followed by groups Er:YAG (60mJ); Er,Cr:YSGG (1.5W/15Hz); Er,Cr:YSGG (2W/20Hz) and Er,Cr:YSGG (1.5W/20Hz) that presented a relatively considerable risk of failure, even at low stress levels. CONCLUSIONS: When considering reduction of enamel microcrack formation and clinical acceptable shear bond strength, none of the groups succeeded both. Etching by Er:YAG (60mJ) and Er,Cr:YSGG (1.5W/15Hz), showed the least overall microcrack incidence between groups, but Er:YAG (60mJ) displayed significant reduction compared to phosphoric acid. However, etching by Er:YAG (80mJ) had the most predictable results in term of shear bond strength.

A Comparative Study of Laser Irradiation Versus Sandblasting in Improving the Bond Strength of Titanium Abutments.

Objective: The purpose of this study was to evaluate the effects of Er,Cr:YSGG laser irradiation with different energy powers versus sandblasting for enhancing the tensile bond strength (TBS) between titanium implant abutments (IAs) and resin cements. Background data: Clinical decementation of prosthetic restorations often occurs, particularly on short IAs. Increasing the bonding area on the IA surface can enhance the function and longevity of the superstructure. Materials and methods: Fifty dental IAs were used in solid form and randomly assigned to five groups (n = 10 each) for the following different pretreatments: control group was left untreated, a laser operating at 2.78 µm wavelength with different energy powers (1, 2, and 3 W) was used for three laser groups, and 50 µm alumina particles were applied to the abutment surface for the sandblasting group. Fifty metal substructures that had an occlusal metal O-ring were cast and cemented to all abutments using dual-cure resin cement. Test specimens were then subjected to thermal cycling. TBS tests were performed with a universal testing machine. The specimens' surface topography and roughness were evaluated with scanning electron microscope, and energy dispersive spectroscopy (EDS) was used to measure the elemental profiles of each specimen. Data were analyzed using a one-way analysis of variance/Kruskal-Wallis test at a significance level of p < 0.05. Results: Surface treatments affected the surface roughness and TBS of the IA. The sandblasting group showed the highest bond strength values (510.77 ± 60.86 N) and followed by the 2 W group (279.07 ± 37.9 N). In EDS analysis, no elemental components other than titanium and oxygen were observed, except for in the sandblasting group. Conclusions: Sandblasting and 2 W laser treatment increased the surface roughness of the IA, which could contribute to the increased interfacial bond strength between the IA and resin cement.

Effect of universal adhesives on microtensile bond strength to hybrid ceramic.

BACKGROUND: The aim of this study was to evaluate the effect of universal adhesives (UA) and silane on the microtensile bond strength (µTBS) of resin cement to a hybrid ceramic Vita Enamic (VE). METHODS: VE specimens were acid etched using hydrofluoric acid (HF) and were assigned to three groups (n = 10) based on the applied bonding technique. In group 1 (S), a silane-based primer was used as a surface treatment prior to the application of a resin cement (Variolink Esthetic DC). In group 2, a silane-containing UA, Clearfil Universal Bond (CUB) was used for the surface treatment, and in group 3, A silane-free UA, Tetric N-Bond Universal (TNU) was used for surface treatment. Resin cement build-ups were prepared. The bonded specimens were sectioned into resin-ceramic beams. Half of the beams of each group were stored for 24 h at 37 °C and the other half were subjected to a thermo-cycling aging. The microtensile bond strength (µTBS) was measured at a crosshead speed of 0.5 mm/min. Failure modes were assessed accordingly. Data were analyzed using a) two-way analysis of variance ANOVA followed by one-way ANOVA and Tukey tests between groups and b) independent t-test to detect differences (α = 0.05) for each group. The surface topographies of the ceramic surface were evaluated using scanning electron microscopy. RESULTS: The results showed that silane-based primer (S) application resulted in significantly higher (p < 0.05) µTBS values after 24 h and after thermocycling compared to both silane-containing UA (CUB) and silane-free UA (TNU). The µTBS values of all groups were significantly reduced after thermocycling. No statistically significant difference was observed between the µTBS of CUB and TNU after 24 h. However, TNU showed significantly higher µTBS after thermocycling. Different failure modes were observed, and adhesive failure was the most common in all groups. Marked surface topographic changes were observed following HF etching. CONCLUSION: It is concluded that, the UAs tested cannot be recommended as substitutes to the silanization of Hybrid ceramic.

Effect of Combined Surface Treatments on Surface Roughness and Resin Bond Strength to Y-TZP Ceramic and Nickel-Chromium Metal Alloy.

Objective: This study compared the effects of different surface treatments on the surface roughness (Ra), and shear bond strength (SBS) of resin cement to yttria-stabilized tetragonal zirconia (Y-TZP) ceramic and nickel-chromium (Ni-Cr) base metal alloy, respectively. Materials and methods: Thirty disk-shaped specimens (3 mm height and 10 mm diameter) of each material (Y-TZP and Ni-Cr) were prepared. Both zirconia and metal specimens were randomly assigned to three equal groups, according to the surface treatments (n = 10): sandblasting, sandblasting + Er:YAG laser, and sandblasting + Nd:YAG laser. Resin cement cylinders (4 mm diameter and 3 mm thickness) were placed on each specimen. The SBS tests were performed at a 1 mm per minute crosshead speed through a knife-edge rod after 5000 thermal cycles. The Ra (µm) of the specimens was measured using a profilometer and evaluated topographically by atomic force microscopy and scanning electron microscopy. Analysis of variance, followed by Tukey's honestly significant difference, in addition to the Kruskal-Wallis test, followed by the Mann-Whitney U test, were used for statistical analysis (α = 0.05). Results: Combined sandblasting and laser treatment of the metal groups led to statistically higher Ra values than sandblasting alone (p < 0.05). For Y-TZP, there were no significant differences between the Ra values of the subgroups (p > 0.05). The SBS of the sandblasted metal group was significantly higher than the other two laser-irradiated groups, whereas the SBS of sandblasted zirconia was only significantly higher than the Nd:YAG laser-irradiated group (p < 0.05). Conclusions: Combined laser and sandblasting surface treatments resulted in rougher surfaces than sandblasting alone, especially for the metal specimens. Sandblasting, alone, improved the SBS of resin cement in both metal and zirconia, compared with the laser and sandblasting treatments, combined.