An ultrastructural analysis of the prototype single-step adhesive applied on enamel and dentin surfaces. (41/389)

A new type of self-etching agent, the single-step adhesive, was developed. The purpose of this study was to investigate the difference in the ultrastructural features of enamel and dentin surfaces following application of the prototype single-step adhesive (EXM618, 3M, MN, USA). Extracted caries-free human premolars were used in this study. Occlusal enamels of teeth--to be used as cut surface specimens--were removed perpendicular to the long axis of the specimens. The mesial and distal surfaces of these teeth, on the other hand, were used as uncut surface specimens in the test. In addition, Mega Bond (Kuraray Medical Inc., Tokyo, Japan) and Xeno CFII Bond (Dentsply Sankin, Tokyo, Japan) were used as controls. After covering half of the tooth surfaces with nail varnish (for control), the other half of each surface was treated with one of the three test adhesives--EXM618, Mega Bond, or Xeno CFII Bond--according to the manufacturer's recommendations. Conditioned enamel and dentin surfaces (i.e., decalcified depth and rugged surface) were observed with a scanning confocal laser microscope (SCLM 1100, Olympus, Tokyo, Japan; henceforth abbreviated as SCLM). Based on the findings of this study, the prototype single-step adhesive EXM618 appears to be suitable for use in dental clinics.  (+info)

Six and 12 months' evaluation of a self-etching primer versus two-stage etch and prime for orthodontic bonding: a randomized clinical trial. (42/389)

The aim of the study was to compare the mean clinical chair-side time required for bracket bonding and the mean bond failure rate at 6 and 12 months of stainless steel brackets with a micro-etched base bonded with a light-cured composite using a self-etching primer (SEP) or a two-stage etch and prime system.Fifty-one subjects who required upper and/or lower pre-adjusted edgewise fixed appliances were recruited in a single centre randomized clinical trial. The trial was a single-blind design, involving a within-patient comparison of the two bonding systems with each patient randomly allocated the two bonding systems for each side of the mouth (all teeth except molars). The two bonding techniques used were standardized throughout the trial and all bracket bonding was performed by a single operator. Bonding time was recorded using a digital timer. The bond failure rate of a strictly paired sample was recorded at 6 and 12 months for each patient. The mean bracket bonding time per patient with the SEP was significantly less than that with the two-stage bonding system (mean difference 24.9 seconds; 95 per cent confidence interval 22.1-27.7 seconds; paired t-test P < 0.001). The overall bond failure rates at 6 and 12 months with the SEP were 0.8 and 1.6 per cent, respectively, and for the two-stage etch and prime 1.1 and 3.1 per cent, respectively. At 6 months, the mean bond failure rate per patient with the SEP was 0.81 per cent and with the two-stage bonding system 0.96 per cent (P = 0.87; Wilcoxon signed rank test). At 12 months, the mean bond failure rate with the SEP per patient was 1.54 per cent and with the two-stage bonding system 2.78 per cent (P = 0.33; Wilcoxon signed rank test). The mean bracket bonding time with the SEP per patient was significantly shorter than that of the two-stage bonding system (P < 0.001). The difference between the overall bond failure rate and the mean bond failure rate per patient for the two bonding systems was not statistically nor clinically significant at 6 and 12 months (P = 1.00 and P = 0.125, respectively; McNemar's test).  (+info)

A study of the effects of self-etching primers on the polymerization of bonding agents using electron spin resonance (ESR) spectroscopy. (43/389)

Though reputed for attaining the highest bonding strength, dentin bonding systems that use self-etching primer pose a grave concern. This is because the low pH environment induced by self-etching primer may have negative effects on polymerization reactions. In this study, we used electron spin resonance spectroscopy (ESR), high performance liquid chromatography (HPLC), and dynamic viscoelastic (DV) to analyze the effects of self-etching primer on the polymerization of bonding agents. The results of ESR revealed a lower concentration of polymerization radicals in a sample consisting of bonding agent and self-etching primer than in a sample consisting of bonding agent alone. However, in the results of HPLC and DV, the quantity of unpolymerized monomers decreased and the polymer produced was highly viscous in the sample with self-etching primer. It was suggested that hydroxyethyl methacrylate copolymerized as a plasticizer of Bis-GMA and that it formed the copolymer in the interface between the primer and bonding agent.  (+info)

Microtensile bond strength of dual-cure resin cement to root canal dentin with different curing strategies. (44/389)

The purpose of this study was to measure the bond strength of dual-cure resin cement at different regions of root canal dentin using three kinds of curing method. Thirty-six extracted bovine teeth were used. Each root was sectioned vertically into halves. Their pulpal dentin walls were polished flat and then applied with two dual-cure resin cements (Bistite II, Panavia F), and divided into three curing strategy groups: multi-direction light, one-direction light and no-light. The bonded specimens were sectioned perpendicularly to the long axis of the root into approximately 0.7 mm thick slabs within two-third of the root from the coronal end, and prepared for microtensile bond strength (muTBS) test. Knoop hardness of the cements was also measured. Within each curing strategy for both dual-cure resin cements, there were no significant differences between the muTBS values at the coronal third and mid third regions. The effect of curing method on bond strength and KHN was found to be dependent on the material.  (+info)

Office reconditioning of stainless steel orthodontic attachments. (45/389)

An investigation was conducted to determine a simple, effective method for reconditioning stainless steel orthodontic attachments in the orthodontic office. In total, 100 new brackets were bonded to premolar teeth, then debonded and the bond strength recorded as a control for the reconditioning process. The debonded brackets were divided into six groups and each group reconditioned using different techniques as follows: attachments in four groups were flamed and then either (1) sandblasted, (2) ultrasonically cleaned, (3) ultrasonically cleaned followed by silane treatment, (4) rebonded without further treatment. Of the two remaining groups, one was sandblasted, while the brackets in the other were roughened with a greenstone. The brackets were rebonded to the premolar teeth after the enamel surfaces had been re-prepared, and their bond strengths measured. The results indicated that sandblasting was the most effective in removing composite without a significant change in bond strength compared with new attachments. Silane application did not improve the bond strength values of flamed and ultrasonically cleaned brackets. Attachments that had only been flamed had the lowest bond strength, followed by those that had been roughened with a greenstone.  (+info)

Comparative evaluation of tensile-bond strength, fracture mode and microleakage of fifth, and sixth generation adhesive systems in primary dentition. (46/389)

Conservative procedures using dentin-bonding agents are one of the important aspects of pediatric dental practice. The objectives of this in vitro study was to comparatively evaluate the tensile-bond strength, fracture mode (under SEM) and microleakage of total etching single bottle system to self-etching adhesive system in primary dentition. The flat buccal/lingual surfaces of 20 teeth were divided into two groups and treated with Single Bond (Group 1) and Adper Prompt (Group 2) to develop a composite resin cone. Then tensile-bond strength was measured using Instron machine. Fracture mode was evaluated in three specimens from each group under SEM. Microleakage of Class V composite restorations (in 20 teeth) with the above-mentioned adhesives was assessed under stereomicroscope after Basic fuschin dye immersion. Results showed no statistically significant difference between two groups. It was concluded that concerning the single step application with similar efficacy, the self-etching adhesive is better for bonding in primary dentition.  (+info)

Necrosis of gingiva and alveolar bone caused by acid etching and its treatment with subepithelial connective tissue graft. (47/389)

The misuse of various chemicals in dentistry may cause damage to gingiva and alveolar bone. In this case report, we describe necrosis of the gingiva and alveolar bone caused by acid etching. A patient whose caries on the cervical third of the root of his mandibular right first molar were treated 2 days earlier presented to our clinic with severe pain and discomfort in the treated area. Intraoral examination revealed a spreading gingival ulceration and exposed alveolar bone. The patient was followed and a week later, when the gingival inflammation had decreased, periodontal surgery was performed. A full-thickness flap was raised and necrotic gingiva and bone were removed. As a result, only a narrow band of keratinized gingiva remained. To treat the gingival recession and protect the underlying bone, a subepithelial connective tissue graft was placed during the same session. After the operation, the patient"s complaints resolved. Subepithelial connective tissue graft can be an important treatment approach in cases of necrosis and gingival recession caused by the misuse of various chemicals.  (+info)

Clinical and radiographic behaviour of 290 dental implants with a surface treated with hydrofluoric acid and passivated with hydrofluoric and nitric acid: early loading results after 2 years. (48/389)

OBJECTIVE: This work presents the results of clinical and radiological behaviour, for 2 years, of 290 implants treated with a first etching with HF and a second etching with HF and HNO3 acids and that were loaded 8 weeks after insertion. EXPERIMENTAL DESIGN: It is a prospective study on 290 implants placed in 56 patients with an age range from 28 to 81. The selection was previously made through radiological study with panoramic and tomographic radiographs, followed by the implantological treatment with prosthetic loading and clinical (15 days, 1, 3 , 6, 12, 18 and 24 months) and radiological control (12 and 24 months). RESULTS: During the healing period, 11 implants failed, resulting in a CSR of 96.21%. After prostheses placement at 2 months, 4 implants were retired, successfully remaining 275 implants. CONCLUSIONS: The following and favourable results after the prosthetic loading of 179 implants (CSR of 98.56%), attest that early loading may and must be applied, after rigorous planning and case selection.  (+info)