COMPARING THE PATTERNS OF ENAMEL ETCHING BY TWO IRANIAN ACID-ETCHES AND ONE FOREIGN STANDARD ACID-ETCH IN VITRO

Анотація

Abstract. Introduction: One of the main steps in composite restorations is enamel etching to create a strong bond between composite resin and dental surfaces and prepare these surfaces. This increases the bonding surface and the grip of composite resins, and improves the margin bonding of restorations. Given the fact that today there are various acid-etches with different features in the dental market, the answer to this question that which one of the different types of acid-etches used provides better etching pattern and greater bond strength in development of composite resin adhesion to dental surface
compared to others is uncertain, therefore, we decided to conducted a study with the aim of comparing the patterns of enamel etching by two Iranian acid-etches and one foreign standard acid-etch in Vitro. Materials and Methods: In this study, 20 extracted human maxillary premolars that were free of decays and fractures were selected, and after cleaning them with Pumice powder, they were stored in 0.2% Thymol solution at room temperature. Prior to acid-etching, the teeth were  divided into two groups of 10. The labial surfaces of teeth were polished, and then, with a nail polish, the labial surface of
each tooth was divided into two distinct mesial and distal parts. In one group, the mesial part of each tooth was etched by standard acid (Ultradent) and the distal part of each tooth was etched by an Iranian acid (Kimia), and in other group, it was etched by another Iranian acid (MorvaBon). Both groups were etched according to the manufacturer's instructions. After washing the acids for 20 seconds, and also drying them up for 20 seconds, the etching patterns developed in the SEM study center was investigated and compared. Findings: The etched enamel surfaces by two type of acids showed corrosion
around the prisms and no coverage in the center of prisms (Type 2 pattern) in the middle 1/3 and incisal 1/3, however, the cervical 1/3 was developed in most samples of type 3 pattern. In some areas, the Iranian acid also did not create a pattern associated with the shape of the prisms. One of the morphological differences observed in regions etched with the foreign acid in comparison to the Iranian acid was the better order and arrangement of etching pattern induced by the foreign acid.
Another difference was the formation of more sediments in the sections etched by the Iranian acid, which may reduce the resin grip to enamel, and the last difference was more corrosion of foreign acid measured by an image analysis machine. Discussion and conclusion: In present SEM study, the corrosion from the Iranian acid was visually more than foreign acid, thus, it is necessary to study the chemical composition of Iranian acid and make necessary amendments. Also, studies on the
bond strength of resin to enamel and the degree of microleakage in applications of Iranian acid seems necessary.
Keywords: Acid etch, Etching pattern, Enamel