all-bond-2 and Smear-Layer

Tooth sensitivity after crown preparation is not an uncommon complication. For dentin bonding agents to be effective in preventing postoperative sensitivity, they must remain intact throughout the fixed prosthodontic procedures.. This study evaluated, by analyzing the change in dentin permeability, whether a dentin bonding agent was removed from the surface of prepared teeth in the process of making an impression.. Eighty extracted human molars were cut horizontally apical to the cemento-enamel junction and horizontally through the middle of the clinical crown. The specimens were prepared to measure dentin permeability (fluid flow rate, Lp). The specimens (n = 40) were randomly assigned to either the primer-only group (PO) or the primer + adhesive group (PA). Five different impression materials were tested: vinyl polysiloxane, polyether, polysulfide, irreversible hydrocolloid, and reversible hydrocolloid. Dentinal permeability was measured after smear layer removal (control, etched Lp = ELp), after coating the dentin with either PO or PA (coated Lp = CLp), and again after making an impression (impression Lp = ILp). A 1-way ANOVA of differences, followed by a Student-Newman-Keuls test (alpha=.05), was performed to compare the ELp, CLp, and ILp values.. A statistically significant difference was found between the CLp and ELp for all 5 impression materials in both groups (PO and PA). No difference was found between the CLp and ILp values for any of the impression materials. No significant differences were found between any of the 5 impression materials or either of the dentin surface treatments (PO or PA) when measuring the CLp and ILp.. The dentin bonding agent had a significant effect in decreasing the Lp of the treated specimens. None of the impression materials significantly affected the measured CLp. There was no significant difference between the PO or PA (CLp) values.

Topics: Acid Etching, Dental; Adhesives; Alginates; Analysis of Variance; Colloids; Dental Bonding; Dental Impression Materials; Dentin; Dentin Permeability; Dentin-Bonding Agents; Dentinal Fluid; Ethers; Humans; Methacrylates; Polyvinyls; Resin Cements; Resins, Synthetic; Siloxanes; Smear Layer; Statistics as Topic; Sulfides

To evaluate in vitro the dentin morphology in root canals in terms of tubule orientation, density and increase in surface area after etching.. Thirty anterior teeth were divided in 3 groups at random: the samples of Group 1 were used to study tubular morphology in SEM. Groups 2 and 3 samples were etched with 32% phosphoric acid. The teeth in Group 2 were examined by SEM without further treatment. The samples in Group 3 were treated with a bonding system and fiber posts were luted into the canal. These teeth were then processed for evaluation of hybrid layer formation and resin tags in dentin tubules. The observations were made according to location in the root dentin, tubule density was estimated, and the increase in area available for bonding after etching was calculated.. The observations revealed variability in tubule density and orientation within different areas of any one sample. Statistically significant differences in the density of tubules were found depending on location. The dentin surface area available for bonding increased by 202% after etching in the cervical third, 156% in the middle third, and 113% in the apical third of the root dentin. Group 3 samples showed that the thickness of the hybrid layer depended on the density of tubules. In the sectors with a low density of tubules, the hybrid layer was significantly thinner than in areas with a higher density of tubules. The increase in dentin surface area might be responsible for the enhanced bond strength after acid etching, but not all areas exhibited equal responses to etching.

Topics: Acid Etching, Dental; Analysis of Variance; Boron Compounds; Dental Bonding; Dental Pulp Cavity; Dentin; Dentin-Bonding Agents; Gutta-Percha; Humans; Methacrylates; Methylmethacrylates; Microscopy, Electron, Scanning; Phosphoric Acids; Post and Core Technique; Resin Cements; Root Canal Filling Materials; Root Canal Irrigants; Root Canal Preparation; Smear Layer; Sodium Hypochlorite; Statistics as Topic; Surface Properties; Tooth Apex; Tooth Cervix; Tooth Root

The objectives of this study were (1) to determine the depth of demineralization into intact dentin using several self-etching primer systems with different pH values, and (2) to evaluate whether hybridization of intact dentin in Clearfil SE Bond may be affected by variation in the thickness of the smear layers.. Dentin disks were created from mid-coronal dentin in extracted, human third molars. Three self-etching primer systems (Clearfil Liner Bond II, Liner Bond 2V, and SE Bond) were applied separately to these disks to evaluate how deep self-etching systems penetrate through smear layers into intact dentin. Dentin treated with All-Bond 2 using the "no-etch" technique was used as a control group. In the second part of the study, dentin disks with different smear-layer thicknesses were produced. The cryofractured control group was devoid of a smear layer. The experimental teeth were ground with 60-, 180-, or 600-grit SiC paper and bonded using SE Bond. Dentin disks were bonded together and examined with TEM.. All-Bond 2 did not etch beyond the smear layer. The three self-etching primers etched beyond the smear layer to form true hybrid layers within intact dentin. This layer was thickest with Liner Bond 2 (ca 1.2 to 1.4 microns), but very thin (0.5 micron) using both Liner Bond 2V and SE Bond. Application of SE Bond to dentin of different surface roughness produced hybridized smear layers of variable thickness. However, the thickness of the underlying true hybrid remained consistent for the four groups (ca 0.4 to 0.5 micron).. Self-etching primers create thin hybrid layers that incorporate the smear layer. The suspicion that thick smear layers may interfere with the diffusion of self-etching primers into the underlying intact dentin was not confirmed.

Topics: Acid Etching, Dental; Acids; Dental Bonding; Dentin; Dentin-Bonding Agents; Diffusion; Freeze Fracturing; Humans; Methacrylates; Microscopy, Electron; Resin Cements; Smear Layer; Surface Properties

The purpose of this pilot study was to determine how lactic acid solution at various concentrations and etching times affected prepared human enamel and dentin surfaces and to assess whether it could be used in place of phosphoric or maleic acid as an etchant. The occlusal surfaces of extracted molar teeth were ground wet with 600-grit silicon carbide paper and treated with various aqueous solutions of lactic acid. Random samples were prepared for observation by scanning electron microscopy. The rest were used to determine shear bond strength of bonded dental composite cylinders. The micrographs revealed that lactic acid dissolved the smear layer with various degrees of etching and demineralization. The degree of smear layer and matrix removal was proportional to the concentration of the acid and the length of application time. A 20% lactic acid concentration applied for 10 seconds produced a clearly etched surface with minimal demineralization. A 30% concentration not only removed the smear layer and enlarged the dentin tubule orifices but also appeared to affect the collagen matrix. The shear bond strength to enamel treated with 50% lactic acid (17.5 +/- 1.5 MPa) and All-Bond 2 etchant (18.9 +/- 1.3 MPa) were not significantly different (p > 0.05). However, mean dentin bond strengths for all groups of lactic acid etchant and All-Etch etchant (10% phosphoric acid) were statistically similar.

Topics: Acid Etching, Dental; Analysis of Variance; Dental Enamel; Dentin; Dentin-Bonding Agents; Humans; Hydrogen-Ion Concentration; Lactic Acid; Materials Testing; Methacrylates; Microscopy, Electron, Scanning; Phosphoric Acids; Pilot Projects; Smear Layer; Surface Properties; Tensile Strength

This paper reviews the fourth generation universal bonding system and highlights its supremacy over the earlier bonding systems. This new system has the ability to bond to all dentally related surfaces and its hydrophillic nature allows the advantage of bonding in a naturally moist environment. The effect of acid on dentine and the role of hydrophillic primers in the formation of a collagen-resin complex are described in relation to obtaining good bonding and adhesion. A new fourth generation universal bonding system. ALL-BOND 2, is discussed in the light of these developments and its features compared to those of the ideal bonding system.

Topics: Dental Bonding; Dentin; Dentin Sensitivity; Dentin-Bonding Agents; Methacrylates; Methylmethacrylates; Microscopy, Electron, Scanning; Smear Layer; Stress, Mechanical; Surface Properties