A new silicon-based root canal sealer (Roekoseal Ò -Automix) N. GENC ¸ OGLU*, C. TU ¨ RKMEN* & R. AHISKALI † *Department of Endodontics, Faculty of Dentistry, Marmara University, Istanbul, Turkey and † Department of Pathology, Faculty of Medicine, Marmara University, Istanbul, Turkey SUMMARY This study evaluated the new silicon- based sealer ‘Roekoseal Ò -Automix’ (RSA) with respect to sealing, bonding capabilities and biocom- patibility with rat subcutaneous connective tissue. For the microleakage study, 36 single rooted teeth were instrumented and 30 of these obturated with either Grossman’s sealer or RSA using lateral con- densation technique (15 of each). Six teeth were not obturated and used as control group. For investi- gating bonding capability, 10 of the obturated roots with RSA and Grossman’s sealer were ground and split longitudinally and examined by scanning electron microscopy (SEM). The RSA was found to seal significantly better than Grossman’s sealer. The SEM examination revealed a good bond between RSA and the dentine and between RSA and the gutta-percha. Tissue reaction was evaluated by injecting 0®1 mL RSA into the connective tissue of 21 male Albino–Wistar rats and observing at 24 h, 7 days and 30 days. Formation of a new granulation tissue with fibrous tissue adjacent to the material at 30 days. This study found that RSA performed well. KEYWORDS: dye penetration, Roekoseal, root canal sealer, silicon Introduction One of the aims of endodontic treatment is to obturate the root canal system with an impervious biocompat- ible and dimensionally stable filling material (Nyguen et al., 1991). Gutta-percha cones with a sealer is now accepted as the most reliable method for obturating the root canal system. According to Grossman (1982), ideal root canal sealer should be capable of producing a bond between core material and the dentine of the root canal, prevent leakage, be non-toxic and enhance healing of periapical lesions. Although various kinds of materials like, zinc oxide eugenol (ZOE), resin cements, glass–ionomer and polyketone compounds have been used as a root canal sealer, the ideal root canal sealer has yet to be found. Recently, a silicon-based sealer Roekoseal Ò -Automix (RSA) has been developed. It consists of polydimethyl siloxane, silicon oil, paraffin-base oil, hexachloropla- tinic acid (catalyst), zirconium dioxide (radiopaque material) (RSA Brochure)*. It is supplied ready to use in a dual-barrel syringe. With all synthetic rubbers – polysulphide, silicon, polyether or whatever the type – a homogeneous mix is essential for accuracy (Craig, 1989); RSA therefore comes in dual barrelled syringe form which forces equal quantities of base and catalyst through a removable static tip. The inside of the mixing tip contains a number of baffles that force the base and the catalyst to be folded over and over on each other as they are extruded. These systems have the advantage of uniformly dispensing and mixing the catalyst and the base in a way that results in fewer bubbles in the mixed material than with hand-spatulated mixes. Polydimethyl siloaxane has been used in dentistry for a long time especially in prosthodontics. Silicon-based impression materials are preferred because of low dimensional change (about 0®6–0®15%) and low water sorption. Silicon soft liners are suggested for use in patients with irritation of the denture-bearing mucosa (Phillips, 1981). Vulcanized or room temperature curing silicons are popular as maxillofacial materials for correcting facial defects resulting from cancer surgery, accident or congenital deformities because of good physical prop- erties and ease of processing and matching to living *Roeko GmbH Co, Langenau, Germany. ª 2003 Blackwell Publishing Ltd 753 Journal of Oral Rehabilitation 2003 30; 753–757