Comparative Analysis of Abrasive Materials and Polishing System on the Surface Roughness of Heat-Polymerized Acrylic Resins

Objective The aim of this in vitro experiment was to see how the operator's manual skills, polishing equipment, and abrasive materials affected the surface roughness of denture base resins. Materials and Methods Forty polymethyl methacrylate (PMMA) specimens were created and polished by using two different polishing systems, namely hand and automatic polishing machines. Three operators hand-polished 30 of specimens with eggshell powder and pumice, while 10 were automatically polished (n = 5). A profilometer was used to determine the average surface roughness (Ra) after polishing. The Ra values for the specimens hand-polished were analyzed by using paired sample testing. The Ra values for all polished specimens were analyzed by using a one-way ANOVA. Differences between the two abrasive materials as well as the polishing system were determined by using the Bonferonni tests (p = 0.05). Results and Conclusion For the PMMA specimens hand-polished, there was a strong connection in the Ra values. There were also significant variations in the Ra values across the three operators (p < 0.001). The automated technique created a substantially smoother surface than the traditional technique (p = 0.001). The greatest Ra values (0.20 µm) were found in specimens polished traditionally by using pumice, whereas the lowest Ra values (0.04 µm) were found in specimens polished mechanically with eggshell powder. The automated polishing system was the most effective polishing method when the Ra values were connected to the level of smoothness.

Evaluation Flexural Strength of PMMA Resins with the Addition of Nanoparticles

The flexural strength of heat cure acrylic resin was investigated by adding different concentrations of TiO2 and ZrO2 nanoparticles to increase its mechanical properties. ZrO2 and TiO2 nanoparticles were added at 1, 3, and 5% concentrations to the powder portion of heat polymerized acrylic resins. A total of 49 samples were prepared in 65 × 10 × 3 mm size. The structural characterisations of all experimental groups were determined by Fourier transform infrared spectroscopy. Flexural strength of the resin specimens was evaluated with a three-point bending test in a universal test machine and then examined under by scanning electron microscope to assess its topographic characteristics. The highest flexural strength value was obtained for 3% TiO2, while the lowest values were obtained for 1% and 5% TiO2. 1% ZrO2 and 3% TiO2 groups showed statistically higher flexural strength values than the control group. Addition of 3% and 5% ZrO2 and 1% and 5% TiO2 showed statistically lower flexural strength than the control group.

Soft Denture Liner Adhesion to Conventional and CAD/CAM Processed Poly(Methyl Methacrylate) Acrylic Denture Resins-An In-Vitro Study

This study aimed to evaluate the airborne-particle abrasion surface treatment effects on the tensile bond strength (TBS) between resilient denture liner and CAD/CAM or conventional heat polymerized poly (methyl methacrylate) (PMMA) acrylic denture resins. A total of 48 dumbbell-shaped specimens (70 mm in total length, and 12 mm and 7 mm in diameter at the thickest and thinnest section, respectively) were prepared from CAD/CAM and conventional acrylic resins. Before relining with denture liner, 12 specimens from each material were surface-treated by 110 µm Al2O3 airborne-particle abrasion, and the remaining specimens served as control (no treatment). Following relining, all the specimens were aged by thermal cycling (1000 cycles, 5–55 °C). The TBS of denture liner to acrylic denture resins was tested in a universal testing apparatus at a 5 mm/min crosshead speed. The debonded surfaces were visually examined for the failure modes. ANOVA and multiple comparisons posthoc analysis tests were applied to determine the significant difference in TBS between the study groups (α = 0.05). A significant difference in TBS was observed between the control and surface treated groups (p < 0.001) for both acrylic resins materials. However, there was no statistically significant difference in bond strength between the acrylic resins materials (p = 0.739). Surface treatment with airborne-particle abrasion demonstrated increased TBS of the soft denture liners to acrylic resins. The TBS of conventional and CAD/CAM acrylic resins to soft denture liners were not considerably different.

Rice vinegar removes Candida albicans from denture acrylic resins

Denture stomatitis, mainly caused by Candida albicans, often affect denture wearers. To manage these patients, denture hygiene is of utmost importance. There is a need for low cost, easily accessible denture disinfectants. To investigate the efficacy of rice vinegar and other disinfecting solutions in removing C. albicans from acrylic resins. Hundred and eighty acrylic resin plates were contaminated with C. albicans strains and divided into five groups. These were immersed in apple cider vinegar (ACV), white wine vinegar (WWV), rice vinegar (RV), chlorhexidine (CHX), and sterile distilled H2O (control). The plates were incubated at room temperature for 30 minutes, 1 hour and 8 hours. Candida removing ability of the disinfecting solutions was evaluated, and data was analyzed using two-way ANOVAwith Tukey post-test. Significance level of p< 0.05 was used. RV, ACV, WWV and CHX showed the highest efficacy (100%) in removing both C. albicans strains at 8 hours (p>0.05). CHX was the most effective disinfectant in removing both C. albicans strains at 30 minutes, 1 hour, and 8 hours (99%-100%). RV was as effective as ACV, WWV and CHX in removing C. albicans from acrylic plates at 8 hours.

Surface roughness analysis of prepolymerized CAD/CAM dental acrylic resins following combined surface treatments

Oral dentures are subjected to mechanical and chemical cleansing processes. However, these processes alter the physical and mechanical properties of denture acrylic resins. This study analyzes the surface roughness of conventional heat-cured (HC) polymethacrylate, light-cured (LC) urethane dimethacrylate, and prepolymerized computer-aided design/computer-aided manufacturing (CAD/CAM) dental acrylic resins. The materials were subjected to combined surface treatment of mechanical brushing, thermal cycling, and immersion in chemical disinfectants (corega, chlorhexidine gluconate [CHG], and sodium hypochlorite) to simulate 1 year of clinical use. The surface roughness of the resin specimens before and after surface treatment was evaluated using a noncontact profilometer. Statistical tests based on analysis of variance revealed significant interactions between resin type and disinfectants, indicating that the effects of these two factors were interdependent. The highest and lowest surface roughness was observed in HC resins immersed in CHG and CAD/CAM resins immersed in sodium hypochlorite. Among the materials, HC resins demonstrated the overall highest mean roughness, followed by LC and CAD/CAM resins. Regarding the disinfectant use, the highest mean roughness was observed in disks immersed in CHG, followed by those immersed in corega and sodium hypochlorite. The prepolymerized CAD/CAM acrylic resin demonstrated superior surface quality following combined surface treatments. The HC and LC resins exceeded the roughness threshold and the reported roughness values for acrylic resins following surface treatments. Among the disinfectants tested, sodium hypochlorite produced overall low roughness values.

Auricular Prosthesis for Congenitally Deformed Ear with Acrylic Template for Colour Depiction - A Case Report

Prosthodontists usually stick to the dictum by MM Devan, “preservation of what remains than meticulous replacement of what has been lost.1” “Microtia” is a term used to describe congenital anomaly of the external ear. It is a combination of the words “micro” and “otia” each of the term denoting small and ear respectively. It includes a range of deformities which may consist of presence of a rudimentary ear, a grossly normal or smaller ear or complete absence of the entire external ear. These deformities usually account for 3 in every ten thousand births, with less than 10 % of all the cases showing bilaterally missing ears.2-4 Facial deformities are common for the microtia patient as the auricle develops from tissues of the branchial arches. Figure 1 describes the patient having congenitally missing unilateral ear. Maxillofacial prosthodontics deals with prosthetic rehabilitation of disfigured or missing parts of head and neck. Prosthetic replacement of the exterior part (Epithesis) can be related to as old as civilization. References to it are available in Indian, Greek, Roman, Egyptian Civilizations.5 Ambroise Pare is credited with making various contributions to the materials and techniques in facial prosthetics. Fabrication of an extra-oral prosthesis is probably more of an art than science. Throughout the recorded history, humans have attempted to restore missing parts of the body by using various artificial materials. MPF materials have evolved since centuries right from metals, ivory, porcelain, waxes, natural rubber, gelatin, and latex to modern day materials such as methacrylate or acrylic resins, polyurethane elastomers, and silicone elastomers each having their own set of advantages and disadvantages. But silicone is most commonly used because of its assorted benefits over other MFP materials. This case report describes an auricular prosthesis for the patient with congenital ear deformity using an acrylic template for colour depiction and room temperature volcanizing (RTV) silicone.6