Objectives: Dental tissue conditioners have been used to deliver various antimiocrobial/antibacterial agents to treat intraoral Candidal infections. The objective of this study was to investigate the effect of such additives on the gelation time and water uptake characteristics of two tissue conditioner formulations.
Methods: The formulations comprised a polymer powder (polyethyl methacrylate, PEMA, from Lucite International) with a 95% plasticiser 5% ethanol mix. Two plasticisers were used, acetyl tributyl citrate (ATBC) and butyl phthalyl butyl glycollate (BPBG) from Morflex Inc., USA. Powder liquid ratio used was 5g to 3ml. Additives were clorhexidine diacetate (CHD) and sodium fluoride (NaF) from BDH Chemicals, UK. Formulations were tested with no additives (control) and with 1% CHD and 1% CHD/0.5% NaF mix. Gelation time at 37ºC was determined (using 60% trace reduction method) for all formulations (n=6) with an oscillating rheometer. Water uptake was measured gravimetrically using specimens (n=4) 40 x 10 x 1mm immersed in 100mls of distilled water at 37ºC. Weight change with time was recorded for 14 days after which specimens were removed, desorbed and solubility calculated.
Results:
| ATBC | ATBC/CHD | ATBC/ CHD/NaF | BPBG | BPBG/CHD | BPBG/ CHD/NaF |
Gel time min (SD) | 36.9 (3.8) | 25.0 (4.3) | 26.0 (2.7) | 17.4 (3.2) | 14.1 (2.5) | 9.2 (1.5) |
% weight change (SD) | 2.1 (0.2) | 7.6 (0.6) | 32.6 (1.8) | 3.1 (0.2) | 4.8 (0.4) | 31.0 (1.6) |
% solubility (SD) | 0.97 (0.06) | 1.37 (0.02) | 1.85 (0.11) | 1.42 (0.07) | 1.73 (0.06) | 2.45 (0.06) |
The additives reduced the gelation time for both plasticiser formulations. CHD/NaF combination had the most effect on water uptake and solubility. Further analysis of data showed a change in kinetics from Fickean to Fickean plus Case II when CHD/NaF was added.
Conclusions: The additives affected both gelation time and water uptake characteristics, this needs to be taken into consideration when using these systems for drug delivery