Influence of the mechanical properties of resilient denture liners on the retention of overdenture attachments

Effect of Professional Denture Cleaning on Surface Roughness of Silicone or Acrylic Soft Relining Materials

The aim of this study was to investigate the effects of combining mechanical (ultrasonic) and chemical cleaning (using denture cleaners) on the surface roughness of silicone or acrylic soft relining materials. The silicone soft relining material with the lowest Shore A hardness and a acrylic soft relining material routinely used in Japan were selected. Four groups were established based on type of treatment: immersion in water (W); ultrasonic cleaning in tap water (U); ultrasonic cleaning in a hypochlorous acid denture cleanser (HU); or ultrasonic cleaning in an acidic denture cleanser (AU). Following the tests, surface roughness was determined as the arithmetic mean height of the surface (Sa) and maximum height (Sz). Data were analyzed using the Kruskal-Wallis test followed by Bonferroni correction for a multiple comparison. No significant difference was observed in the Sa or Sz of the silicone soft relining material between the 4 groups. Significant differences were observed in the Sa of the acrylic soft relining material between Groups W and HU (p=0.008) and between Groups W and AU (p=0.008), but no significant differences in the Sz among the 4 groups. Combining U with AU or U with HU yielded no increase in the surface roughness of the silicon soft relining material. The surface roughness of the acrylic soft relining material showed an increase, however, with the combination treatments used.

Retention force of Molloplast-B with ball attachment in implant-supported overdentures: An in vitro study

Aim

The purpose of this study is to evaluate the retention effectiveness of Molloplast B as a female attachment compared to O rings' in implant supported overdentures.

Settings and Design

This systematic review and meta-analysis was evaluated using the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines.

Materials and Methods

Sixteen female part models were divided into two groups: eight female parts made with O ring (Group A) and eight female parts made with Molloplast B (Group B). All of the models were soaked in artificial saliva for 24 h, then, their retention force was measured in Newton using a Universal mechanical testing machine, initially, after 500, after 1000, and after 1500 of loading and dislodging cycles.

Statistical Analysis Used

: The statistical analysis was conducted by using one way ANOVA test and Bonferroni test. SPSS Software (SPSS, Version 27, IBM Co., Chicago, IL, USA).

Results

After 1500 loading and dislodging cycles, Group B has the highest mean retention force (4.09), followed by Group A, which has a mean retention force of 3.73.

Conclusion

Molloplast B with a 2.7 mm diameter ball attachment lost the least amount of retention force after 1500 loading and dislodging cycles.

Satisfaction with resilient denture liner versus acrylic resin telescopic prostheses for patients with ectodermal dysplasia: A nonrandomized crossover clinical trial

STATEMENT OF PROBLEM

Patients with ectodermal dysplasia are characterized by anodontia or oligodontia. How their challenging prosthodontic rehabilitation might be optimized is unclear.

PURPOSE

The purpose of this crossover study was to evaluate the effect of resilient denture liner versus acrylic resin copings in complete overdentures for patients with ectodermal dysplasia. Outcome measures included patient satisfaction, retention, and periodontal health of the abutment tooth.

MATERIAL AND METHODS

Ten partially edentulous participants diagnosed with ectodermal dysplasia were recruited from the Faculty of Dentistry, Cairo University, Egypt, and enrolled in this crossover clinical trial. All participants received acrylic resin coping-retained maxillary complete overdentures (group N, stage 1). The acrylic resin copings were then replaced by a resilient denture liner (group S, stage 2). Patient satisfaction, retention, and periodontal health parameters were evaluated 1 week and 3 months after the completion of each stage. Patient satisfaction was assessed with a validated, reliable questionnaire. The results of the periodontal probing depths were tested with repeated measures ANOVA followed by the Bonferroni correction for pairwise comparisons. Tooth mobility, patient satisfaction, retention, and gingival index were tested by using the Wilcoxon signed ranked test. Ordinal data as the sixth and seventh domains of patient satisfaction were tested by using the McNemar test for paired comparisons (α=.05).

RESULTS

Three months after overdenture delivery, a statistically significant difference was found between the groups regarding retention (P=.025), probing depth (P<.001), and gingival index (P=.011) favoring the acrylic resin coping-retained overdentures. Results of tooth mobility (P=.035), overall attitude (P=.041), ease of eating (P=.023), denture comfort (P=.024), and degree of teasing (P=.038) on wearing the denture showed a statistically significant difference between the groups, favoring the resilient denture liner.

CONCLUSIONS

In children with oligodontia and ectodermal dysplasia, the resilient denture liner-retained maxillary complete overdenture enhanced patient satisfaction and tooth mobility of anterior teeth, while minimally jeopardizing the periodontal condition of the abutment teeth.

Comparison of adhesiveness of chewing gum to hard and soft denture base materials

PURPOSE

The purpose of this study was to compare the adhesiveness of chewing gum to hard and soft denture base materials to investigate food retention associated with the basal surface of the denture.

METHODS

Test specimens were fabricated using acrylic resin[Re], cobalt-chromium alloy[Co], zirconia[Zr], silicone soft relining material[SS], and acrylic soft relining material[AS]. Samples were set on a top-and-bottom pair lifting platform equipped with a digital force gauge. The experimenter chewed 3.0 g of chewing gum for 5 min. After surface saliva was wiped off, the chewing gum was placed on the lower test fragment and compressed until the distance between the upper and lower test fragments decreased to 1 mm. The upper test fragment was pulled at a crosshead speed of 100 mm/min. Adhesiveness was measured under dry conditions, and under wet conditions with inter-positioned artificial saliva.

RESULTS

Under dry conditions, the adhesive strength was 17.04 ± 1.99 N for Re, 12.88 ± 2.20 N for Co, 3.80 ± 1.03 N for Zr, 5.76 ± 1.41 N for SS, and 12.54 ± 2.44 N for AS. Under wet conditions, the adhesive strength was 5.26 ± 1.64 N for Re, 0.96 ± 0.21 N for Co, 3.32 ± 0.40 N for Zr, 5.20 ± 1.35 N for SS, and 6.78 ± 1.97 N for AS.

CONCLUSIONS

Among the hard denture base materials, zirconia recorded low adhesiveness and Re recorded high adhesiveness under both wet and dry conditions. The adhesiveness of Co was low under wet conditions but high under dry conditions. Among the soft denture base materials, SS under dry conditions recorded lower adhesiveness than that of AS. The adhesiveness of SS was low under both wet and dry conditions.

Effect of mechanical and chemical cleaning on surface roughness of silicone soft relining material

PURPOSE

This study aims to investigate the effect of mechanical and chemical cleaning on the surface roughness of silicone soft relining materials.

METHODS

We selected silicone soft relining materials with the highest (Soft) and lowest (Supersoft) Shore A hardness. In the abrasion test, specimens were cleaned 50,000 times using a kitchen sponge (Sponge), a soft (Soft brush) or hard (Hard brush) denture brush, or stored in water (No cleaning). In the immersion test, specimens were immersed in either water (Water), neutral peroxide denture cleanser (Neutral), alkaline peroxide denture cleanser (Alkaline), or hypochlorite denture cleanser (Hypochlorite) for 1440 h. Surface roughness of the arithmetic mean height of the surface (Sa) and maximum height (Sz) were measured before and after the tests. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

In the abrasion test, significant differences were observed for Sa and Sz with Soft relining materials, but not for No cleaning and Sponge. In the immersion test, significant differences were observed for Sa and Sz with Soft relining materials, but not between Water and Neutral or Water and Alkaline. Significant differences were observed with Supersoft, except between Water and Neutral or Water and Alkaline for Sa and between Water and Neutral for Sz.

CONCLUSIONS

Mechanical cleaning using a sponge did not increase the surface roughness of the material with a high Shore A hardness. Furthermore, neutral peroxide denture cleanser did not increase the roughness of materials with high and low Shore A hardness.

Mechanical and Surface Properties of Resilient Denture Liners Modified with Chitosan Salts

Chitosan (CS) and its derivatives show antibacterial and antifungal properties and could help treat and prevent denture stomatitis (DS). Mechanical and surface properties of resilient denture liners were evaluated when modified with CS salts. CS-hydrochloride (CS-HCl) and CS-glutamate (CS-G) were added to resilient denture liners Ufi Gel P and Coe-Soft at four different concentrations (0.1%, 0.2%, 0.4%, 1% w/w) from which specimens were produced, as well as a control group of each material with no added CS salt. Ten specimens per group (Ø 35 mm, height 6 mm) were manufactured. They were stored in distilled water at 37 °C for a total of 30 days (d). Shore A hardness (SHA) and surface roughness (Ra) were evaluated after 24 h (T1), 7 d (T2), 14 d (T3) and 30 d (T4). Kruskal-Wallis and U-test (Bonferroni-Holm adjusted) were used for statistical analysis (p ≤ 0.05). Ra increased significantly once CS salts were added. SHA increased significantly for some groups, but all specimens fulfilled requirements set by ISO 10139-2:2016. Modification with CS salts does not influence the mechanical properties of the modified resilient denture liners in a clinically relevant manner. Despite the increased roughness, the concept is suitable for further studies. Especially antimicrobial/antibiofilm studies are needed.

Surface morphology of silicone soft relining material after mechanical and chemical cleaning

PURPOSE

The objective was to investigate the influence of chemical and mechanical cleaning on the surface morphology of a silicone soft relining material.

METHODS

Three plate-shaped specimens were prepared for each group (Control, Hard and Soft) by laminating a 1.5-mm-thick silicone soft relining material. The Control group specimens were stored in water, and the Hard and Soft group specimens were cleaned with hard and soft bristle denture brushes, respectively. Abrasion testing with a toothbrush and immersion testing with an enzyme-containing peroxide denture cleanser were performed, simulating a period of approximately 4 months. The arithmetic mean roughness (Sa) and maximum height of the cross-section (Sz) were measured before and after abrasion and immersion testing.

RESULTS

Sa was 4.9±0.9, 22.1±4.2 and 44.2±4.0μm in the Control, Soft and Hard groups, respectively. Sz was 257.5±31.7, 392.0±23.8 and 452.2±41.9μm in the Control, Soft and Hard groups, respectively. After abrasion testing, Sa and Sz differed significantly between the Soft and Control groups and between the Hard and Control groups. Sa was 2.2±1.2μm before and after immersion, and Sz was 142.1±81.4μm before and after immersion. No significant difference was noted in either Sa or Sz in the Control specimens before or after immersion.

CONCLUSIONS

Surfaces cleaned using a soft bristle brush were less likely to roughen than those cleaned with a hard bristle brush under the conditions of this study. Additionally, chemical cleaning using the enzyme+neutral peroxide denture cleanser did not roughen the surface of the silicone soft relining material.