The Peritoneal Explant Test for Evaluating Tissue Tolerance to Mouthrinses

Abstract

The tissue cultures of explants of neonatal rat peritoneum have been demonstrated to be a sensitive test for tissue compatibility with wound antiseptics. The present study investigated the suitability of this method to assess the relative toxicity of mouthrinses to tissue. Mouthrinses containing 0.1% chlorhexidine (Chlorhexamed® Fluid 0.1%) (A), 0.3% triclosan (Colgate®) (B), essential oil in ethanolic solution (Listerine®) (C), and amine/stannous fluoride (Meridol®) (D) were tested at use concentration and in dilutions of 10, 1, and 0.1% with exposure times of 1, 10, and 30 min, respectively. The mouthrinses (test) and Ringer’s solutions (control) were applied to opened rat peritoneum. After thorough irrigation with Ringer’s solution, a piece of peritoneum was removed and 1 × 1 mm explants were cut. The explants were cultivated with a bovine serum culture medium in 24-well plates at 37°C in a CO₂ incubator (95% air, 5% CO₂). After 10 days, the tissue proliferation for the explants was assessed by a stereo microscope at 10× magnification after ethanol fixing and hemalaun staining. With 24 grafts per test, the proliferation rate was calculated relative to a control, which was run for each mouthrinse and concentration/time combination. Data were analyzed using ANOVA (SPSS 11.0) and post-hoc paired t test. Statistical significance of all correlations was tested by setting the significance level at p < 0.05. At most concentrations, D caused significantly less tissue damage than A or B. There was no difference between C and A or C and B at 100%. However, the toxicity of C was significantly less than A or B at 10, 1, and 0.1%. C and D behaved similarly except for the 10% (30 min) and the 1% (10 min) solutions in which C was significantly less toxic. We concluded that the rat peritoneum explant test was demonstrated to be a sensitive test to assess the relative toxicity of mouthrinses to tissue.

Effect of lactoperoxidase on the antimicrobial effectiveness of the thiocyanate hydrogen peroxide combination in a quantitative suspension test

“…This assumption is supported by a study that showed a discrepancy between antiseptic activity and clinical effect on radiation-induced [52] or chemo-induced mucositis [53] by chlorhexidine mouth rinse compared with placebo. In a peritoneal explant test for evaluating tissue tolerance, chlorhexidine showed the highest cytotoxicity in comparison to an essential oil and an amine/stannous fluoride mouth rinse [54]. Thus, it could be interesting to increase host innate defence systems, such as the lactoperoxidase-thiocyanate-hydrogen peroxide system, which have no or low effectiveness at the physiological level, by increasing their level of concentration instead of using common antiseptics.…”

Listerine® Products: An Update on the Efficacy and Safety

“…This requirement should also be extended to other mouthwashes, for example, CHX (Tsourounakis et al, 2013). A comparative test of mouth rinses on tissue cultures of explanted neonatal rat peritoneum (exposure times up to 30 min) did not find that Listerine® was more toxic than 0.1% CHX, 0.3% triclosan, or amine/stannous fluoride (Welk et al, 2007), but because a negative control was not included in the study, it may well be that all mouth rinses are more or less harmful when used for longer periods. If they are to be effective at reducing tooth loss later in life, mouthwashes would presumably have to be used regularly over many years or even decades.…”

Impact of the cosmetic mouthwash “Jack Pro Spülung plus” (“rheodol-Spülung plus”) on the oral cavity flora, tested in a monocentric, controlled, randomized, blind, cross-over comparative study

“…During aggressive cancer chemotherapy, the oral mucosa is highly sensitive, meaning that teeth cannot be brushed and antiseptics such as chlorhexidine are not tolerated. In fact, due to the cytotoxicity of chlorhexidine [8], the rate of mucositis even increases [9]. …”