Application of phosphoric acid on enamel and dentin surfaces for attaining an optimum adhesion of the composite resins still represents a sensible and highly debatable aspect of restoration odontology. The application time also remains under discussion among researchers and clinicians, ideal being an as short and an as efficient period as possible. The aim of the present study was to compare the micromorphological modifications produced at enamel and dentin level by the 15, 30 and 60 sec action of the 37% orthophosphoric acid, throughy AFM analysis. 20 molars extracted from both orthodontic and periodontal reasons were employed in the study. The sections were randomly divided into 4 groups, each one containing10 samples, the acid being applied for 15, 30 and 60 sec, the last group acting as reference. The thus prepared sections were analyized as to surface roughness, on a SEM model VEGA II LSH scanning atomic force microscope, produced by TESCAN (Czech Rep.), coupled to an EDX type QUANTAX QX2 detector, produced by BRUKER/ROENTEC (Germany). The results were expressed as relative variation of roughness, according to formula: R= root mean square roughness after acid etching – value of the initial root mean square/value of the initial root mean square.
To conclude with, an action time of the 37% phosphoric acid of 15 sec induces morphological modifications at both enamel and dentin level comparable with the longer action times, which recommends its utilization in current stomatological practice, in the case of adhesive systems employing the total acid etching technique
- acid etching