Evaluation of the physical properties of a newly developed denture adhesive for patients with dry mouth.

PURPOSE: Elderly individuals with dry mouth wearing dentures require an appropriate denture adhesive. The purpose of this study was to evaluate the in vitro properties of a newly developed denture adhesive for patients with dry mouth and compare these with those of a currently available adhesive and oral moisturizing agent. METHODS: We developed a new gel-type denture adhesive with physical properties suitable for patients with dry mouth (DM). We subsequently performed in vitro comparisons among DM, New Poligrip (NP), and Biotene Oralbalance Gel (BT) with regard to the following properties: retention force, resistance to squeezing, and ease of removal. In accordance with the standards of the International Organization for Standardization (ISO10873:2010), the retention force was measured for dry samples (no water exposure, severe dry mouth model) and for samples exposed to water for 10min (normal model) and 1min (moderate dry mouth model). The resistance to squeezing was evaluated by pushing the samples out of syringes, while the ease of removal was evaluated by measuring the time required to wash the material from a polymethyl methacrylate plate. RESULTS: In the severe dry mouth model, DM exhibited greater retention force than did NP and BT. Moreover, the resistance to squeezing was significantly lower for DM than for NP. Both BT and DM showed better ease of removal than did NP. NP was the most difficult to wash out with water. CONCLUSIONS: Our findings suggest that the newly developed denture adhesive DM is suitable for use in patients with dry mouth.

Upregulated expression of MMP-9 in gingival epithelial cells induced by prolonged stimulation with arecoline.

Betel quid chewing is implicated in the high prevalence of oral cancer in Southeast Asian countries. One of the major components of betel quid is arecoline. In the present study, in order to characterize the association between chronic arecoline stimulation and carcinogenesis the expression level of matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 mRNA in human gingival epithelial progenitor cells (HGEPs) stimulated with arecoline was assessed. The HGEPs were alternated between 3 days of incubation with arecoline (50 µg/ml), and 3 days without arecoline, for up to 30 days. The expression levels of the MMPs and TIMPs in the cells stimulated with arecoline were evaluated by reverse transcription-quantitative polymerase chain reaction at 18 and 30 days. The expression of MMP-9 mRNA in the experimental group was significantly increased compared with in the control group (P<0.01). No significant differences in the expression of MMP-2, TIMP-1 or TIMP-2 mRNA were observed between the experimental and control groups. Using an MMP-9 activity assay, the levels of MMP-9 activity in the experimental group were demonstrated to be significantly higher than in the control group (P<0.05). To investigate associated cellular signaling pathways, PDTC [a nuclear factor (NF)-κB/inhibitor of NF-κB (IκB) inhibitor], PD98059 [a mitogen-activated protein kinase kinase (MAPKK)1 and MAPKK2 inhibitor], SB203580 (a p38 MAPK inhibitor) and 5,15-DPP [a signal transduction and activator of transcription (STAT) 3 inhibitor] were used. All inhibitors decreased the extent of MMP-9 upregulation induced by stimulation with arecoline. Based on the data, it is hypothesized that MMP-9 activity may be involved in the pathological alterations of oral epithelium induced by betel quid chewing, and that the NF-κB/IκB, MAPK, p38 MAPK and STAT3 signaling pathways may be involved in the production of MMP-9 induced by betel quid chewing.