Adhesive Performance of Pit and Fissure Sealants on Deproteinized Enamel with Different Proteolytic Agents: In Vitro Study.

The objective of this work was to assess the efficacy of different proteolytic agents on the bond strength of pit and fissure sealants to bovine enamel. Eighty-four bovine enamel specimens were randomly assigned in groups according to the pit and fissure sealant applied (HelioSeal F or Dyad Flow). Then, the specimens were subdivided according to the proteolytic agent used (n = 7): Group 1, distilled water (control); Group 2, 10 wt.% Tergazyme®; Group 3, 10 wt.% ZYME®; Group 4, 10% papain gel; Group 5, 10% bromelain gel; and Group 6, 5.25 wt.% sodium hypochlorite. The cell viability of the proteolytic solutions was assessed through the MTT assay. The proteolytic agents were applied on the enamel surface prior to the acid-etching procedure; then, the pit and fissure sealants were placed. The micro-shear bond strength was evaluated after 24 h or 6 months of water storing at 37 °C. Representative SEM images were taken for each experimental group. The bond strength data were statistically analyzed by a three-way ANOVA test using a significance level of α = 0.05. Bromelain and papain proteolytic solutions did not exert any cytotoxic effect on the human dental pulp cells. After 24 h and 6 months of aging, for both pit and fissure sealants, sodium hypochlorite, papain, bromelain, and Tergazyme® achieved statistically significant higher bond strength values (p < 0.05). Irrespective of the deproteinizing agent used, Dyad Flow resulted in a better bond strength after 6 months of aging. The type 1 etching pattern was identified for sodium hypochlorite, papain, and bromelain. Tergazyme®, papain, and bromelain demonstrated efficacy in deproteinizing enamel surfaces prior to acid etching, leading to the improved bond strength of pit and fissure sealants. Clinically, this suggests that these proteolytic agents can be considered viable alternatives to traditional methods for enhancing sealant retention and longevity. Utilizing these agents in dental practice could potentially reduce sealant failures.

An In Vitro Study to Compare the Shear Bond Strength of Metal and Ceramic Brackets Using Conventional Acid Etch and Self-Etch Primer.

Aim: In this, in vitro study's objective is to assess the shear bond strength (SBS) of metal and ceramic orthodontic brackets that have been adhered to enamel using a conventional acid etch/primer and self-etching primer (SEP) adhesive method. Materials and Methods: One hundred excised human premolars were bonded on brackets and were divided into group 1 -Metal brackets were bonded on teeth and group 2 -Ceramic brackets were bonded on teeth. These two groups were further subdivided: subgroup 1a - 25 metal brackets bonded using conventional acid etch/primer adhesive system, subgroup 1b - 25 metal brackets bonded using SEP, subgroup 2a - 25 ceramic brackets bonded using conventional acid etch/primer adhesive system, and subgroup 2b - 25 ceramic brackets bonded using SEP; brackets were debonded using a computerized Instron universal testing machine. Results: The mean value of SBS of metal and ceramic brackets bonded using conventional acid etch/primer adhesive systems had higher SBS than those bonded using SEP. SBS ranged from 7.95 to 12.24 MPa which was in the acceptable clinical range. Conclusion: SBS values of all four subgroups exceeded the range of 6-8 MPa observed to be acceptable for routine clinical use.

Phosphoric Acid Etch Partially Restores the Initial Bond Strength of Composite to Silver Diamine Fluoride-Treated Enamel Using Universal Adhesives.

BACKGROUND: Restoring bonding composite to silver diamine fluoride (SDF)-treated enamel is challenging. This study investigates if phosphoric acid etch restores composite bond strength to SDF-treated enamel using universal adhesives. METHODS: Twenty-four recently extracted permanent teeth were randomly divided into 4 (2 experimental (SDF) and 2 control (CTR)) groups: SDF+Water: SDF (1 min) then water rinse (15 mL); CTR+Water: no treatment and water rinse (15 mL); SDF+Etch+Water: SDF (1 min), 35% phosphoric acid (40 s) then water rinse (15 mL); CTR+Etch+Water no treatment, 35% phosphoric acid (40 s) then water rinse (15 mL). The enamel surface in all the groups was bonded (All-Bond Universal) to 4-5 mm composite blocks (Z-250). Each sample was sectioned, and 6-8 beams (1 mm × 1 mm) were selected. The micro-tensile bond strength was measured by dividing the micro-tensile force peak by the adhesive surface area. Univariate ANOVA and Chi-square were used for between-group comparisons with p < 0.05. RESULTS: SDF+Water had significantly lower tensile strength compared to all the groups (p < 0.05). Although no difference was found in the tensile strength between the SDF+Etch+Water and the CTR+Etch+Water, the SDF+Etch+Water had significantly more adhesive failures compared to the CTR+Etch+Water (p = 0.047). CONCLUSIONS: While phosphoric acid etch seems to restore the initial composite bond strength to SDF-treated enamel, the long-term success of composite restorations bonded to SDF-treated enamel may need further investigation.

Microleakage, microgap, and shear bond strength of an infiltrant for pit and fissure sealing.

Objectives: This study aimed to evaluate the potential clinical application of an infiltrant with different etchants as pit and fissure sealants and to compare them with a conventional resin-based sealant. Materials and methods: Seventy-five molars were randomly divided into three groups (n = 25): phosphoric acid etchant + conventional resin-based sealant (Group A); 15% hydrochloric acid etchant + infiltrant (Group B); phosphoric acid etchant + infiltrant (Group C). Fifteen teeth in each group were subjected to pit and fissure sealing procedures. After 500 thermocycling and methylene blue dye penetration, ten specimens were sectioned and the pencentages of dye penetration were measured under a stereomicroscope. Another five teeth in each group were sectioned and the microgaps between materials and enamel surface were measured using electron microscope scanning. Ten teeth in each group were used to measure shear bond strength and the failure mode was analyzed. Results: The results showed that infiltrant exhibited significantly less microleakage and microgap than resin-based sealant, no matter which echant was used. Although there was no significant difference betweern the three groups, infiltrant applied with 15% hydrochloric acid etching showed higher shear bond strength than resin-based sealant etching with 35% phosphoric acid. Conclusions: The infiltrant has significant advantages in reducing the degree of microleakage and microgap. Moreover, the infiltrant could achieve the same bonding strength as conventional resin-based sealant. Although, manufacturers do not currently recommend the infiltrant for fissure sealing, the potential clinical application would be an off-label use.Clinical relevance This report provides a theoretical basis for the potential clinical application of the infiltrant as a pit and fissure sealant, and provides a new perspective for selecting pit and fissure sealants.

Bonding CAD/CAM materials with current adhesive systems: An overview.

Objective: Overview of the updated literature on the classification of adhesives systems and CAD/CAM materials with clinical guidelines to condition various surfaces for bonding to the tooth structure. Data sources: Searches were conducted in MEDLINE, EMBASE, PubMed, Web of Science, Scopus, Cochrane Library, and Google Scholar using specific keywords. Results: 240 papers were revised, 150 articles were excluded, and 90 were eligible for the review. Most studies concluded the essentiality of bonding E-max, zirconia, and hybrid materials to enhance fracture toughness and fatigue resistance. The success of ceramic bonding depends on the microstructure and surface treatment of the materials. The proper treatment of the intaglio starts with using alumina oxide or hydrofluoric acid. This initial treatment could be followed by monobond salinization, which improves the chemical adhesion. Zirconia-based ceramics have grown lately and become the most prescribed for posterior and anterior teeth. Zirconia can be bonded to the tooth structure using the APC concept and 10 MDP promoting primers. Three hundred adhesive resin systems are currently available in the market, and each is different in chemical composition and clinical bonding strength. Of the three hundred systems, the total-etch system remains the gold standard, especially on the enamel surface. The self-etch adhesive system is favorable on dentin due to lowering the postoperative sensitivity. A new generation of dentin adhesives, called universal or multi-mode adhesives. This system has become popular and can be used either as etch-and-rinse or self-etch adhesives. Conclusion: The chemistry of adhesive systems has changed across generations. The variation of dental tissue is the decisive factor in selecting adhesive systems, resin cement, and ceramic materials. Moreover, a reliable bonding strength necessitates a perfect surface treatment and bonding promoter for tooth and CAD/CAM materials.

Comparison of clinical effectiveness of conventional and self-etch sealant: a split mouth randomized controlled trial.

Background: Self-etching has been shown to be beneficial compared to the other resin sealants especially in pediatric practice. The present in-vivo study was designed to clinically evaluate the sealing ability and retention of the self-etching sealant compared to the conventional resin sealant. The aim was to evaluate and compare the retention and marginal integrity of the self-etch and acid etch sealant materials at three, six and twelve-month follow up. Methods: The study was designed as a double blinded, split mouth randomized controlled trial, . In total, 35 children (70 teeth) between 7 and 10 years of age formed part of the study. Group 1 received acid-etch sealant and Group 2 received self-etch sealants. The study participants and the investigator who performed the statistical analysis were blinded to the treatment allocation. All the samples were evaluated at 3, 6, and 12 months. The inter-group and intragroup comparison were carried out using the Chi-Square test and Friedman test with level of significance set at 5% and the P value less than 0.05. Results: Complete retention of sealants was observed in 34.5% of conventional acid etch (group 1) and 22.9% of self-etch samples (group 2) whereas complete loss of sealants were seen in 11.4% of group 1 and 20% of the group 2 samples and intergroup comparison of retention failure was non-significant (p=0.135). In total, 85.7% of the group 1 and 82.9% of the group 2 samples exhibited good marginal integrity with no clinical changes in the enamel around the margins but this was not statistically significant (p=0.5). Conclusions: Sealants with fewer procedural steps and those which provide adequate retention would be ideal for use in children. Thus, self-etch sealants have been found to be effective and efficient as a sealant in the present in-vivo study. Clinical Trials Registry, India registration: CTRI/2019/03/018343 (29/03/2019).

Adhesive Dentistry: Understanding the Science and Achieving Clinical Success.

Successful adhesive dentistry begins with correct placement and polymerization of the bonding agent. Although numerous agents exist, all abide by certain key principles, including the newest group, the universal adhesives. Fundamental steps also exist in the application process that require the operator to understand the chemistry of the adhesive being used. Modalities exist that can help preserve the durability of the bond achieved, thus slowing down the degradation process. However, no material or agent can overcome poor technique. Thus, it is of the utmost importance that the practitioner respects the technique sensitivity of adhesives, and follows the manufacturer's instructions.

Three-Dimensionally-Printed Polyether-Ether-Ketone Implant with a Cross-Linked Structure and Acid-Etched Microporous Surface Promotes Integration with Soft Tissue.

Polyether-ether-ketone (peek) is one of the most common materials used for load-bearing orthopedic devices owing to its radiolucency and favorable mechanical properties. However, current smooth-surfaced peek implants can lead to fibrous capsule formation. To overcome this issue, here, peek specimens with well-defined internal cross-linked structures (macropore diameters of 1.0-2.0 mm) were fabricated using a three-dimensional (3D) printer, and an acid-etched microporous surface was achieved using injection-molding technology. The cell adhesion properties of smooth and microporous peek specimens was compared in vitro through a scanning electron microscope (SEM), and the soft tissue responses to the both microporous and cross-linked structure of different groups were determined in vivo using a New Zealand white rabbit model, and examined through histologic staining and separating test. The results showed that the acid-etched microporous surface promoted human skin fibroblasts (HSF) adherence, while internal cross-linked structure improved the ability of the peek specimen to form a mechanical combination with soft tissue, especially with the 1.5 mm porous specimen. The peek specimens with both the internal cross-linked structure and external acid-etched microporous surface could effectively promote the close integration of soft tissue and prevent formation of fibrous capsules, demonstrating the potential for clinical application in surgical repair.

The Intergranular Corrosion Susceptibility of Metastable Austenitic Cr⁻Mn⁻Ni⁻N⁻Cu High-Strength Stainless Steel under Various Heat Treatments.

The intergranular corrosion (IGC) behavior of a new metastable austenitic Cr-Mn-Ni-N-Cu high-strength stainless steel under various heat treatments was studied. The samples were solution treated at 1050 °C for 30 min and then aged at 600 to 900 °C for 10 to 300 min, respectively. The IGC susceptibility of aged samples was investigated using a double-loop electrochemical potentiokinetic reactivation (DL-EPR) test in a solution of 0.1 M H2SO4 and 0.002 M KSCN and the 10% oxalic acid etch. The surface morphologies of samples were characterized using optical microscopy and the scanning electron microscopy after electrochemical tests. Two time-temperature-sensitization diagrams were plotted based on the DL-EPR test and oxalic acid etching. No IGC and precipitate were observed for samples aged at 600 °C and 900 °C. For samples aged at 650 °C to 750 °C, the IGC susceptibility and the amount of precipitate both increased with the extended aging time. For samples aged at 800 °C and 850 °C, the amount of precipitate increased as the aging time was prolonged. However, only the sample aged at 800 °C for 60 min showed slight intergranular corrosion in the DL-EPR test. The IGC of the Cr-Mn-Ni-N-Cu austenitic stainless steel originated from the precipitation of Cr23C6 and Cr2N at the grain boundaries. The chromium-depleted zones near grain boundaries stood as the corrosion nucleation sites, but the dissolution of the weak area followed a consistent crystallographic orientation along each grain boundary.

Effect of Erbium Laser on Microtensile Bond Strength of Fissure Sealant in Primary Teeth: An in vitro Study.

BACKGROUND: Laser etching has several advantages as compared with conventional acid etching. However, results of earlier studies on conditioning surfaces with erbium, chromium:yttrium-scandium-gallium-garnet (Er, Cr:YSGG) before application of the fissure sealant have been inconclusive. AIM: The study aimed to evaluate the microtensile strength of resin-based fissure sealant bonded to primary enamel conditioned by Er, Cr:YSGG laser with varying power outputs. MATERIALS AND METHODS: Fifty sound primary first molars were randomized into the following five groups based on pretreatment choice: Group 1: 3.5 W laser etching + acid etching; Group 2: 2.5 W laser etching + acid etching; Group 3: 3.5 W laser etching with no acid; Group 4: 2.5 W laser etching with no acid and Group 5: acid etching with no laser. Acid etch was performed with 35% orthophosphoric acid for 30 s. Laser etching was performed with Er, Cr:YSGG (2780 nm) laser using G6 tips and 600 µm diameter, 2.5 W or 3.5 W power outputs, pulse duration of 140 µs and a repetition rate of 20 Hz. Sealant was applied on the buccal surface followed by an incremental buildup with composite resin. Microtensile bond strength was assessed and compared among the five groups using one- and two-way ANOVA. RESULTS: There was no statistical difference in the mean bond strength between groups except in Group 4 (9.66 MPa) (Group 1: 15.57 MPa; Group 2: 14.18 MPa; Group 3: 14.78 MPa; Group 5: 14.63 MPa). CONCLUSION: Pretreatment with 3.5 W Er, Cr:YSGG laser alone results in microtensile bond strengths similar to that produced by acid etching, indicating that enamel etching using 3.5 W Er, Cr:YSGG laser would result in the long-term success of pit and fissure sealants in primary teeth.

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.

Confocal microscope analysis of depth of etch between self-limiting and traditional etchant systems.

OBJECTIVE: To see whether there is an advantage to using a self-limiting phosphoric acid etchant versus a traditional 34% phosphoric acid etchant for bonding by measuring the depth of etch at multiple time intervals. MATERIALS AND METHODS: A total of 25 bovine teeth were mounted and etched on the facial surface with two different etchants: standard 34% phosphoric acid and a self-limiting 35% phosphoric acid etchant at varied time intervals of 15, 30, 60, 90, and 120 seconds. Teeth were scanned using a three-dimensional laser confocal scanning microscope prior to etching and scanned again after etching to determine the depth of enamel etched compared to the baseline enamel surface prior to etching. RESULTS: The 34% phosphoric acid etchant etched significantly deeper than the self-limiting etch. Etch times exceeding 30 seconds also etched significantly deeper for both types of etchant. CONCLUSION: The etch depth of the self-limiting etchant was consistently less than the standard etchant. Both types of etchant etched deeper after 30 seconds, but the depth of etch at 120 seconds was not different than at 60 seconds, indicating that both etchants are somewhat self-limiting in depth. Therefore, there is no advantage to using the self-limiting etchant.

Bonding performance of universal adhesives to er,cr:YSGG laser-irradiated enamel.

Universal adhesives have been recently introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinical condition. However, their bonding effectiveness to laser-irradiated enamel is still not well-known. Thus, the aim of this study was to compare the shear bond strength (SBS) of universal adhesives (Single Bond Universal; Nova Compo-B Plus) applied to Er,Cr:YSGG laser-irradiated enamel with SBS of the same adhesives applied in self-etch and acid-etching modes, respectively. Crown segments of sixty bovine incisors were embedded into standardized acrylic blocks. Flattened enamel surfaces were prepared. Specimens were divided into six groups according to universal adhesives and application modes randomly (n = 10), as follows: Single Bond Universal/acid-etching mode; Nova Compo-B Plus/acid-etching mode; Single Bond Universal/self-etching mode; Nova Compo-B Plus/self-etching mode; and Single Bond Universal/Er,Cr:YSGG Laser-etching mode; Nova Compo-B Plus/Er,Cr:YSGG Laser-etching mode. After surface treatments, universal adhesives were applied onto surfaces. SBS was determined after storage in water for 24 h using a universal testing machine with a crosshead speed of 0.5 mm min-1 . Failure modes were evaluated using a stereomicroscope. Data was analyzed using two-way of analyses of variances (ANOVA) (p = 0.05). Two-way ANOVA revealed that adhesive had no effect on SBS (p = 0.88), but application mode significantly influenced SBS (p = 0.00). Acid-etching significantly increased SBS, whereas there are no significant differences between self-etch mode and laser-etching for both adhesives. The bond strength of universal adhesives may depend on application mode. Acid etching may significantly increase bond strength, while laser etching may provide similar bond strength when compared to self-etch mode.

An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching.

Introduction: The aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser. Methods: Thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. Specimens were ground to expose superficial and deep dentin. Samples were assigned to six groups: (1) AS (acid etching of superficial dentin); (2) AD (acid etching of deep dentin); (3) LS (Er:YAG laser irradiation on superficial dentin); (4) LD (Er:YAG laser irradiation on deep dentin); (5) LAS (Er:YAG laser irradiation on superficial dentin followed by acid etching); (6) LAD (Er:YAG laser irradiation on deep dentin followed by acid etching) The adhesive protocol was performed. Samples were thermocycled and micro-shear bond strength was tested to failure. The data were submitted to statistical analysis with one-way analysis of variance (ANOVA) and Tukey post hoc test. Results: The AS group, demonstrated the greatest amount of micro-shear bond strength. Statistical analysis showed a decrease in bond strength in laser-treated groups which was more significant for deep dentin. Conclusion: Preparation of dentin with laser did not improve bonding to superficial and deep dentin.

Bone mesenchymal stem cell functions on the hierarchical micro/nanotopographies of the Ti-6Al-7Nb alloy.

We investigated the response of rat bone mesenchymal stem cells (BMSC) placed on the titanium-6aluminium-7niobiuim (Ti-6Al-7Nb) alloy modified by hydrofluoric acid etch combined with subsequent anodic oxidation. Pure titanium (Ti) discs and Ti-6Al-7Nb discs were treated by hydrofluoric acid etch and anodic oxidation, and polished pure Ti discs and Ti-6Al-7Nb discs without surface modification served as controls (n=35 in each group). Scanning electron microscopy, atomic force microscopy, and radiographic photoelectron spectroscopy assays were used to detect the properties of the samples' surface. The morphology, adhesion, proliferation, and alkaline phosphatase activity of BMSC were examined using various techniques of microscopic and biological characterisation. The results showed that both Ti-6Al-7Nb samples and the pure Ti samples showed hierarchical micro/nanotopographies, and fluorine emerged on the surfaces of the samples after modification. The hierarchical micro/nanotopographies significantly increased the spreading, adhesion, and proliferation of BMSC and activity of alkaline phosphatase. In addition, modified samples of Ti-6Al-7Nb showed significantly higher alkaline phosphatase activity than modified pure Ti samples (p<0.05). The experiment successfully confirmed that Ti-6Al-7Nb alloy with hierarchical micro/nanotopographies treated by hydrofluoric acid etch and anodic oxidation possessed good biocompatibility, and may be a promising candidate for dental implants.

Evaluation of surface roughness and bond strength of quartz fiber posts after various pre-treatments.

PURPOSE: Debonding at the post-adhesive interface is a major problem for quartz fiber posts. The objective of this study was to evaluate surface roughness and bond strength of quartz fiber posts after various surface treatments. MATERIALS AND METHODS: Sixty-six quartz fiber posts were randomly divided into six experimental groups (n = 11) including group C, untreated (control); group SB, sandblasted; group SC, silica coated; group HF, hydrofluoric acid-etched; group N, Nd:YAG laser irradiated; group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. They were then bonded to resin cement and tensile bond strength was determined in a universal testing machine. Furthermore, two-way ANOVA and post hoc comparison tests (α = 0.05) were performed on all data. RESULTS: The highest mean force value was observed in group SB and followed by group E. Tukey's HSD test showed that there was no statistical difference between group SB and group E (p = 0.673). The highest mean roughness value was observed in group SB and a significant difference was found between group SB and all other groups (p < 0.001). This study reveals that sandblasting and Er:YAG laser irradiation provided a significant increase in bond strength between quartz fiber posts and resin cement. CONCLUSIONS: Sandblasting or Er:YAG laser-irradiation of the surface of the quartz fiber post before cementation is recommended for increasing retention.

Análisis descriptivo morfoestructural mediante microscopía electrónica de barrido del efecto sobre el esmalte de la técnica de grabado ácido convencional y una nueva técnica de grabado ácido aplicada en 2 tiempos operatorios / Descriptive analysis of the enamel microestructure after the conventional and a two-step modified acid etch technique using scanning electron microscopy

INTRODUCCIÓN: El grabado ácido total constituye una técnica fiable para asegurar la adhesión en el esmalte. Con una excelente adhesión al esmalte del borde cavo superficial de la preparación cavitaria se podría evitar la aparición de la filtración marginal, es por esto que se desarrolló una técnica que asegure crear un patrón eficaz de grabado en el esmalte, resultando en mayor cantidad de microrretenciones y por lo tanto, en una mejor adhesión micromecánica. MATERIALES Y MÉTODOS: En el presente estudio se utilizaron 5 dientes, todos terceros molares sanos recientemente extraídos, que fueron limpiados y cavitados para luego ser cortados por la mitad y separados en 2 grupos. El grupo A que recibiría la técnica de grabado ácido convencional y el grupo B que recibiría una variación de la técnica en 2 tiempos operatorios. Todas las muestras fueron llevadas al microscopio electrónico de barrido para observar si existen diferencias en la microestructura obtenida en cuanto al esmalte. RESULTADOS: Se observaron diferencias entre las superficies adamantinas de un mismo diente, al ser grabadas con los diferentes métodos, existiendo un patrón de grabado con mayor definición y porosidad en las muestras sometidas a grabado ácido en 2 tiempos operatorios. CONCLUSIÓN: Existen diferencias microestructurales entre las superficies adamantinas obtenidas tras el grabado según la técnica convencional y las obtenidas mediante el grabado en 2 tiempos operatorios

INTRODUCTION: Total acid etch is a reliable technique for ensuring adhesion to enamel, providing a durable adhesive interface between enamel surface and composite restoration, in order to prevent the development of micro-leakage. A variation of the etching technique was developed to create an effective and regular etching pattern. This could result in large amounts of retentions and higher surface porosity, leading to better micromechanical adhesion. MATERIALS AND METHODS: A study was conducted on Àve healthy, recently extracted third molars. They were cleaned and cavitated before being cut in half and separated into two groups. Group A received conventional etching technique and group B received a variation of the technique in a two-step procedure. All samples were observed by scanning electron microscopy (SEM) order to observe the differences in enamel microstructure between both groups. RESULTS: There were differences between the surfaces of the same tooth when etched using the different methods. There was a pattern with greater deÀnition and porosity in the samples subjected to two-step acid etching. CONCLUSION: There where microstructural differences on the enamel surfaces between samples etched by a conventional technique and those using a two-step acid etching

Effect of dentine conditioning on adhesion of resin-modified glass ionomer adhesives.

BACKGROUND: The aim of this study was to investigate the use of phosphoric acid as a surface treatment compared to traditional conditioning agents to dentine bonded with resin-modified glass ionomer (RMGIC) adhesives. METHODS: Forty human molars were utilized in microtensile bond strength testing, while another 16 were used for evaluation of the bonded interface with scanning electron microscopy. Three RMGIC adhesives were evaluated: Fuji Bond LC (GC Corp); Riva Bond LC (SDI Ltd); and Ketac N100 (3M-ESPE). Surface treatments were 37% phosphoric acid (5 s) or 25-30% polyacrylic acid (PAA) (10 s), or the manufacturer's method - Fuji Bond LC: Cavity Conditioner (20% PAA + 3% AlCl3 10 s) or Ketac N100 primer: Ketac Nano priming agent (15 s). Teeth were finished with 600-grit SiC paper, surfaces treated and bonded with RMGIC adhesive and stored in distilled water for 24 h then subjected to microtensile bond strength testing. RESULTS: Two-way analysis of variance (ANOVA) revealed adhesion was affected by the 'type of RMGIC adhesive' and 'method of dentine surface treatment' (p < 0.05). The microtensile bond strength of Ketac N100 primer groups was lower than Fuji Bond LC and Riva Bond LC (p < 0.05). CONCLUSIONS: For RMGIC adhesives a brief etch with phosphoric acid does not adversely effect short-term bond strengths, but is no better than traditional conditioning with PAA.

Análisis comparativo in vitro del grado de filtración marginal de restauraciones de resina compuesta realizadas con dos métodos de grabado ácido distintos / In vitro comparative analysis of microleakage in composites resin restorations made with a conventional and a modified acid etch technique

La técnica de grabado ácido en esmalte representa el hito que marca la puerta de entrada para el establecimiento de la odontología adhesiva. Producto de que el sustrato adamantino pudiese presentar comportamiento refractario a la técnica convencional de grabado ácido es que se plantea una técnica en dos tiempos operatorios, la cual pudiese disminuir dicho comportamiento resistente al grabado ácido y combatir así el fenómeno de la filtración marginal de las resinas compuestas. En este estudio se utilizaron 30 terceros molares sanos, en los cuales se realizaron cavidades clases V en las caras vestibulares y linguales/palatinas, las cuales fueron obturadas con resina compuestas utilizando técnica de grabado ácido convencional y técnica de grabado ácido en dos tiempos operatorios, respectivamente. Estos especímenes fueron sometidos a un proceso de termociclado en presencia de un agente colorante marcador. Luego de un proceso de termociclado, las muestras fueron cortadas transversalmente para evaluar el porcentaje de penetración del agente marcador. El análisis de los resultados demostró que las restauraciones realizadas con técnica de grabado ácido en dos tiempos operatorios presentaron menores valores de filtración marginal, existiendo diferencias significativas entre ambos grupos estudiados.

The acid etch technique is the fact that marks the starting point for the establishment of the adhesive dentistry era. But as the enamel structure may have a resistant behavior towards the conventional acid etch technique ,a two-step acid etch technique is presented. This would diminish the aforementioned resistant behavior of enamel to the conventional acid etch technique, and minimize as well, the marginal leakage phenomenon of the composite materials. In this study 30 sound recently extracted molars were used. Equal class V cavities preparations were made in the buccal and palatal/lingual faces of each tooth. Buccal cavities were filled with composite before the use of the conventional acid etch technique, as adhesive method, while in the lingual/palatal faces the two-step acid etch technique was used. The samples were subjected to thermal cycles in the presence of a dying agent. After the thermocycling process, the samples were cut transversely to assess the percentage of penetration of the staining agent. The analysis of the results showed that there was a significant statistical difference between both groups. Moreover the restorations made with the two-step acid etch technique presented lower values of marginal leakage.

Adhesion between glass fiber posts and resin cement: evaluation of bond strength after various pre-treatments.

PURPOSE: To evaluate surface roughness and bond strength of glass fiber posts to a resin cement after various surface treatments. MATERIALS AND METHODS: Sixty individually formed glass fiber posts with a diameter of 1.5 mm and a length of 20 mm were used for this study. They were randomly assigned to six groups of pre-treatment (n = 10/group): Group C, untreated (control); Group SB, sandblasted; Group SC, silica coated; Group HF, hydrofluoric acid-etched; Group N, Nd:YAG laser irradiated; Group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. The posts were then bonded to resin cement and tensile bond strengths were determined in a universal testing machine. For statistical analysis, two-way ANOVA and post-hoc comparison tests (α = 0.05) were performed. RESULTS: The highest bond strength value was observed in group HF, followed by group SC. There was a statistically significant difference in bond strength between group C and groups HF, SC and E (p < 0.001, p = 0.002 and p = 0.041, respectively). Posts of group SB and group N showed the highest surface roughness. CONCLUSIONS: The findings of the present study reveal that hydrofluoric acid-etching, silica coating and Er:YAG laser irradiation provided a significant increase in bond strength between glass fiber posts and resin cement.