Effects of Toothpaste on the Gingival Barrier Function in vitro

Introduction: Toothpastes (TPs) routinely contain detergents for their emulsifying and foaming properties. The most common detergent sodium lauryl sulfate (SLS) displays irritant effects to skin. Studies suggested that it may also affect the structural integrity of the oral mucosa. Besides detergents protective substances may also be ingredients of toothpastes. The aim of this study was to investigate the effect of different toothpastes on the gingival epithelial barrier function. Materials and methods: Immortalised human gingival keratinocytes (IHGK) were seeded on ThinCertTM cell culture inserts. Slurries from 4 different TPs were applied apically to the cells (1:100 and 1:1000 diluted). One TP contained additionally triclosan, one herbal extracts and one zinc citrate. The Transepithelial Electrical Resistance (TER) was measured hourly (h) until 8h and after 24, 48 and 72h. The cytotoxicity of the slurries was investigated by Lactate Dehydrogenase (LDH) release. Results: All TP slurries in 1:100 dilution caused a decrease of the TER until 8h (8-13 Ohm x cm2) (p < 0.05). The most distinct decrease was observed using the TP without additional components. The 1:1000 dilution of the TP induced a TER increase (5-13 Ohm x cm2 ) after 48 and 72h (p < 0.05). The most distinct increase was induced by a TP containing zinc. No significant cytotoxic effect caused by TPs was observed. Conclusions: The results of this study showed that TP slurries dose-dependently modulated the gingival barrier function without increased cytotoxicity. High dilutions showed TER enhancing, lower dilutions TER impairing properties. The decreasing effect was reduced by active ingredients like zinc.