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Objectives: The aim of this study was to evaluate the buffering capacity of glass-ionomer material in vitro. The null hypothesis tested was that there is no effect of cured glass-ionomer pit-and-fissure sealant (PFS) pastes on the environmental acidity as well as the tooth substrate.Method: For each material, a cured PFS disk and a section of human enamel were simultaneously soaked in lactic acid solution in a conical tube, and the pH of the solution was measured daily for one week. Subsequently, the total amount of calcium leached out in solution was also measured with ICP-AES.Results: The results showed that the acidity of the solutions changed over time. Significant differences of calcium ion concentration in solution were observed as a result of decalcification. As the PFS products tested did not include calcium, the concentration of calcium ion released indicated acidic erosion of the tooth enamel.Conclusions: The glass-ionomer countered the acid of the solution rapidly and preserved the structure of human tooth enamel. [ABSTRACT FROM AUTHOR]

Resin–dentin bonds are known to degrade in the relatively aggressive oral environment. In order to obtain greater insight into the interfacial degradation process, we examined, by using transmission electron microscopy (TEM), the interfacial ultrastructure of two adhesives bonded to dentin after 1 yr in vivo. Class V cavities were prepared on the buccal surfaces of 14 intact teeth of two monkeys and then restored by using either the two-step self-etch adhesive, Unifil Bond, or the two-step etch-and-rinse adhesive, Single Bond, in combination with the restorative microhybrid composite, Z250. After 1 yr, 10 other teeth were restored by using the same materials (controls). One day later, the monkeys were killed, following which the microtensile bond strength to dentin was determined and the interfacial ultrastructure was examined by TEM. Whereas no noticeable changes in the morphology of the resin–dentin interface were observed between the 1-d and 1-yr specimens for Unifil Bond, Single Bond exhibited signs of interfacial degradation, in particular at the bottom of the 3 µm-deep hybrid layer. In conclusion, the adhesive interface produced by the etch-and-rinse adhesive was less resistant to degradation than that produced by the self-etch system. [ABSTRACT FROM AUTHOR]

Abstract: The use of fluoride for the prevention of caries is based on the transformation of hydroxylapatite to fluoroapatite in the presence of fluoride ions, thereby strengthening tooth structure. Adhesion of dentin and resin composite (tooth-colored restoration material) requires a dentin bonding system, since resin composite is not able to adhere to dentin directly. Demineralization of dentin by acid etching is an important step in the dentin bonding system, however, demineralization also introduces weaknesses in tooth structure. If the demineralized dentin could be strengthened by the application of fluoride, then the dentin–resin composite bond strength might also improve. To test this hypothesis, the present study evaluated the influence of fluoride applications on the strength of the dentin–resin composite bond by (1) tensile strength testing analyses, (2) SEM analyses of tooth structure, and (3) detection of calcium (Ca) and fluorine (F) distribution patterns by micro proton-induced X-ray emission (μ-PIXE) and micro proton-induced gamma-ray emission (μ-PIGE) analyses conducted at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) at the Takasaki Advanced Radiation Research Institute (TARRI). In this study, the dentin in extracted human molars was exposed by grinding and the dentin was etched with 35% phosphoric acid. Fluoride was applied at two concentrations, 0.022% (100ppm F) and 2.21% (10,000ppm F) NaF solution, for two time periods, 30 and 60s, prior to bonding the resin composite with the treated dentin. Controls were prepared in the same manner, but without the fluoride application. Bond strength was measured with a micro-tensile testing unit, and the fluorine and calcium distributions at the interface between dentin and resin composite were detected by μ-PIGE and μ-PIXE analysis, respectively. Results indicate that the 10,000ppm F applications resulted in higher bond strengths than observed in either the 100ppm F applications or the control group. In addition, PIGE analyses showed high concentrations of fluorine in the hybrid bonding layer of the 10,000ppm F samples, suggesting that the fluorine contributes to the strength of the dentin–resin composite bond. Detection of fluoroapatite within the hybrid bonding layer suggests that bond strength involves remineralization processes. [Copyright &y& Elsevier]

Since adhesive technology was introduced into dental field, metal-based restoration has been gradually replaced by metal-free restoration. Using the adhesive technology, minimum invasive technique has been possible in daily clinical practice as well as esthetic tooth-colored restorations have become very popular all over the world. One of the current issues of the dental adhesive is durability of bond between tooth structure and adhesive resin. Several approaches to overcome the issues have been carried out. Self-etching approach is believed to create durable bond because demineralization of superficial tooth surface is very shallow. Other approach is to utilize the inhibitor of enzymes which are suggested to catalyze the decomposition of resin composites and are always secreted within the oral environment. In the present study, Colloidal Platinum Nanoparticles (CPN) was applied before the application of 4-META/MMA-TBB resin cement as the third possibility to prolong the durability of bond. This implies that the use of the CPN solution would create higher conversion at the interface compared with conventional bonding procedures. [ABSTRACT FROM AUTHOR]

Ikeda T, Sidhu SK, Omata Y, Fujita M, Sano H. Colour and translucency of opaque-shades and body-shades of resin composites. Eur J Oral Sci 2005; 113: 170–173.© Eur J Oral Sci, 2005The purpose of this study was to evaluate the optical properties– not only the translucency but also the colours– of opaque-shade resin composites. The CIELAB parameters (L*, a* and b*) of disks of A2 and opaque A2 (OA2) shades of Charisma (Heraeus-Kulzer), Solare (GC) and Filtek Supreme (3M) were evaluated on backings of black, white and the material itself to calculate the translucency parameter (TP) and the colour differences (ΔE*) between A2 and OA2. A two-way analysis of variance (anova) for the TP indicated a less statistically significant TP value in the OA2 shade than the A2 shade for all products. As for the products, Charisma showed a statistically greater TP value than the other two products. Regarding theΔE* between A2 and OA2, all the products revealed clinically perceptible colour differences (ΔE* > 3.3). Hence, we must take the colour differences of opaque-shade resin composites into consideration, as well as the translucency of the materials, for a clinically acceptable colour match of the restoration. [ABSTRACT FROM AUTHOR]

Self-etching primer adhesives have recently been introduced to simplify bonding. However, the fundamental bonding mechanism of self-etching primers to enamel is not yet fully understood. This study aimed to investigate resin–enamel bonds of self-etching primer adhesives on ground enamel. Two self-etching primer adhesives (Clearfil Liner Bond 2 V and Clearfil SE Bond) were used in this study. A total-etch adhesive (One-Step) was used as a control. Resin–enamel beams were subjected to the microtensile bond test. Subsequently, the failure modes of all specimens were quantified using image analysis. Undemineralized and demineralized ultrathin sections of the resin–enamel bonded specimens were examined using transmission electron microscopy. The bond strengths of Clearfil SE Bond (39.8 ± 11.9 MPa) and One-Step (46.2 ± 12.7 MPa) were significantly greater than that of Clearfil Liner Bond 2V (30.4 ± 6.2 MPa). Scanning electron microscopy of the fractured surfaces revealed the failure direction and weakest portion within each bond. Transmission electron microscopy showed a thin hybridized complex of resin in enamel produced by the self-etching primers without the usual micrometer-sized resin tags seen in resin–enamel bonds produced using the total-etch adhesive. The morphological features of the resin–enamel bonds produced by two self-etching primers tested were different from that created with the total-etch adhesive. [ABSTRACT FROM AUTHOR]