Development of new tissue conditioner using acetyl tributyl citrate and novel hyperbranched polyester to improve viscoelastic stability

Objective. The objective was to develop a new tissue conditioner using acetyl tributyl citrate (ATBC), tributyl citrate (TBC), and a novel hyperbranched polyester (TAH) with long-term stable viscoelasticity. Methods. Plasticizers, i.e., ATBC, TBC, TAH (number-average molecular weight, 1306 g/mol; weight-average molecular weight, 4245 g/mol), butyl phthalyl butyl glycolate (BPBG), dibutyl phthalate (DBP), benzyl benzoate (BB), Shofu Tissue Conditioner II (Shofu), and GC Soft-Liner (GC), in nine combinations (ATBC + TAH, TBC + TAH, ATBC, TBC, BPBG, DBP, BB, Shofu, and GC), with gelation times between 120 and 180s were used; Shofu and GC were used for comparison. The dynamic viscoelasticity properties, i.e., shear storage modulus (G'), shear loss modulus (G ''), loss tangent (tan 6), and complex dynamic shear modulus (G*) were determined at 37 degrees C, using a rheometer, after immersion in water for 0, 1, 3, 7, 14, and 28 d. The surface hydrophobicity was examined using a static contact angle analyzer, and the biocompatibility was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Weight changes, solubility, and water absorption were measured using an analytical balance. Results. TAH addition increased the viscoelastic stability; ATBC + TAH was the most stable among the tested groups. TAH decreased the contact angle and increased the water absorption, but decreased the ATBC solubility. The ATBC + TAH group biocompatibility was similar to those of the control group. Signcance. The developed ATBC + TAH plasticizer has potential applications as a new tissue conditioner. Its clinical efficacy needs to be evaluated in clinical trials. 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.