THE EFFECT OF PRETREATMENT WITH AN OXALIC-ACID SOLUTION ON MARGINAL ADAPTATION TO ENAMEL IN-VIVO

Statement of problem. New acids such as oxalic acid have been introduc ed as a conditioning agent in the total-etch technique. There is conce rn about long-term retention of the acid on enamel in relation to the superficial etch effect.Purpose. This in vivo study evaluated the marg inal adaptation to enamel conditioned with either an oxalic acid solut ion or a phosphoric acid with SEM replica technique. Material and meth ods. Twenty-four patients received one of each of three class III rest orations. Two cavity preparations were pretreated with aluminum nitrat e/oxalic acid/glycine solution 1 of the Gluma 2000 system. The first c avity was primed and sealed with Gluma 2000 solution 2, the second cav ity with Gluma 3 and 4. The third cavity was conditioned with phosphor ic acid (Gluma 1) and sealed with the bonding resin Gluma 4. All three cavities were restored with a hybrid resin composite (Pekafill). At b aseline and after 1 year, replica impressions were made to study the m argins with SEM. Semiquantitative analysis of the enamel interfaces wa s performed (x200 and x1000 magnifications). Marginal quality of the t hree restorative systems were compared and tested intraindividually.. Results. The three restorations exhibited good enamel marginal adaptat ion and a high percentage of gap-free margins at baseline, 96% to 97% of the total length of margins investigated. Marginal quality decrease d significantly after 1 year for all three groups. Gap-free margins we re observed in 81% to 85% of the marginal length. No significant diffe rences were found among the groups. Conclusion. Despite a less pronoun ced etch pattern created by conditioning of enamel with the oxalic aci d solution, a good enamel marginal quality was observed at both evalua tion times, comparable to the marginal adaptation of the phosphoric ac id conditioned cavities.