Deterioration of Resilient Denture Liners and Patient Characteristics
Condition: Xerostomia; Menopause; Kidney Disease
MeSH terms: Xerostomia; Kidney Diseases
Study type: Observational

Summary: 
      Thirty complete maxillary denture wearers were recruited after obtaining informed consent.
      One investigator measured the Shore D hardness of the commercially available RDLs using a
      Vesmeter®. The salivary flow rates and pH values and the occlusal force were measured for all
      patients before initiation of the study.

      T-tests and Pearson's correlation coefficients were used for statistical analyses.

      A p-value of <0.05 was considered statistically significant.
    

Detailed description: 
      1. Participants This study was approved by the Human Ethics Committee of Nihon University
           School of Dentistry, Matsudo (EC 13-006). Thirty wearers of complete maxillary dentures
           (12 men; mean age, 71.8 ± 9.2 years and 18 women; mean age, 70.2 ± 10.7 years) who
           visited the Department of Removable Prosthodontics at our institute were recruited for
           this study. The volunteers were enrolled only after they provided written informed
           consent. Complete maxillary denture wearers who had been treated with a tissue
           conditioner, RDLs, and denture adhesives were excluded. Before starting the clinical
           trial, the participants were asked about the following environmental factors in a
           questionnaire: smoking, drinking, denture wearing during sleeping, and denture cleanser
           usage.

           After specimen making, all participants were instructed to wear their dentures as per
           their normal routine.

        2. Specimen Preparation A cylinder shapes six places with a 4-mm diameter and 2-mm depth ,
           that was drilled into the inner surface of the denture base. Then, the RDL materials
           were mixed by each product, packed into the cavity, and polymerized at room temperature
           . The six commercial RDLs used in this study:Evatouch Super (EVA; Neo Dental Chemical
           products, Washington, USA), GC RELINE (GCR; GC Dental Products Corp, Tokyo, Japan),
           Mucopren soft (MCP; Kettenbach GmbH & Co KG, California, USA) Soften (SFT; KAMEMIZU
           CHEM, Osaka, Japan), FD Soft (FDS; KAMEMIZU CHEM, Osaka, Japan), and Bio Liner (BIO;
           Nissin Dental Products, Kyoto, Japan).

           Hardness was measured using a Vesmeter® (WaveCyber Corp, Saitama, Japan). When the
           probe, which included a built-in position sensor connected to a personal computer, was
           placed in a perpendicular orientation to an RDL, the indenter of the probe was depressed
           onto the RDL at a constant speed through electromagnetic power. Simultaneously, the path
           of the indenter was constantly traced by the position sensor. The computer processed
           electrical signals from the measuring device and calculated the Shore D hardness, which
           was the primary outcome in the present study. The same investigator measured the
           hardness at each appointment. The original hardness and the hardness at 1 month after
           oral exposure were used for analysis. Each specimen was measured five times, and the
           highest and lowest values were eliminated from the calculation of the mean
           representative value for each specimen. The specimens embedded in the dentures were
           measured on a hot plate to maintain the temperature at 37°C or as close to the oral
           temperature as possible.

        3. Statistical Analyses Before other statistical analyses, the normality of the data was
           tested using the Kolmogorov - Smirnov test, and then parametric statistical methods were
           applied.Two-way repeated measures analysis of variance ( ANOVA ) with the material type
           (EVA, MCP, GCR, FDS, SFT, and BIO) and time period (baseline and one month after) as
           factors was used to assess changes in the hardness of the six RDLs over time. The
           Tukey-Kramer test was used as a post hoc test after the two-way repeated measures ANOVA
           .The effects of categorical variables such as sex, smoking, drinking, denture wearing
           during sleeping, and denture cleanser usage on the hardness of the RDLs were analyzed
           using a two-way ANOVA without a post hoc test; we were not interested in comparing each
           RDL but rather in analyzing the effects of categorical variables on the RDLs. The
           effects of continuous variables, including age, salivary flow rate, and occlusal force,
           were analyzed using Pearson's correlation coefficients. All statistical analyses were
           performed using IBM® SPSS® Statistics 21 (IBM, Armonk, NY, USA). A p-value of <0.05 was
           considered statistically significant.
    

Intervention name(s): Evatouch Super
Intervention type(s): Other
Intervention description(s): The deterioration of RDLs may differ between in vitro conditions and the conditions encountered in denture wearers. We conducted an in vivo study to investigate how resilient denture liners (RDLs) changed in hardness when embedded in complete maxillary dentures worn by patients for one month in a clinical setting. We hypothesized that the hardness one month after application of the RDLs would be affected by the age, the condition of the saliva, the occlusal force, type of denture used, the patients habits related to smoking, drinking, wearing dentures while sleeping, and using a denture cleanser.
Other intervention name(s): GC RELINE; Mucopren soft; Soften; FD Soft; Bio Liner
Sampling method: Non-Probability Sample
Study population: 
        The patient of wearing complete maxillary dentures who visited the Department of Removable
        Prosthodontics at our institute were recruited for this study.

        The volunteers were enrolled only after they provided written informed consent.