Investigation of the Surface Roughness and Hardness of Different Denture Teeth Materials: An In vitro Study.

Background: Surface roughness and hardness are key factors that influence the clinical performance and durability of denture teeth. Understanding variations in these properties among different denture teeth materials can assist in selecting the most suitable materials for optimal patient outcomes. This study aimed to investigate the surface roughness and hardness of four commonly used denture teeth materials: acrylic resin, composite resin, porcelain, and nanohybrid composite. Materials and Methods: Ten specimens were prepared for each denture teeth material, resulting in a total of 40 specimens. Surface roughness was assessed using a profilometer, and measurements were recorded in micrometers (µm). Hardness was determined using a Vickers hardness tester, and results were expressed as Vickers hardness numbers (VHN). The surface roughness and hardness data were analyzed using appropriate statistical tests (e.g., analysis of variance), with significance set at P < 0.05. Results: The results revealed significant differences in both surface roughness and hardness among the different denture teeth materials (P < 0.05). Acrylic resin exhibited the highest surface roughness (mean ± standard deviation: 3.45 ± 0.78 µm) and the lowest hardness (mean ± standard deviation: 45.6 ± 2.3 VHN). Composite resin demonstrated intermediate values of surface roughness (mean ± standard deviation: 1.87 ± 0.54 µm) and hardness (mean ± standard deviation: 65.2 ± 3.9 VHN). Porcelain demonstrated the smoothest surface (mean ± standard deviation: 0.94 ± 0.28 µm) and the highest hardness (mean ± standard deviation: 78.5 ± 4.1 VHN). Nanohybrid composite displayed surface roughness and hardness values similar to composite resin. Conclusion: This study demonstrated significant variations in surface roughness and hardness among the different denture teeth materials evaluated. Acrylic resin exhibited the roughest surface and lowest hardness, while porcelain demonstrated the smoothest surface and highest hardness. Composite resin and nanohybrid composite exhibited intermediate values. These findings provide valuable insights for prosthodontic practitioners in selecting denture teeth materials based on specific clinical requirements, aiming to achieve optimal aesthetics, reduced plaque accumulation, and improved wear resistance.

Assessment of Flexural Strength and Cytotoxicity of Heat Cure Denture Base Resin Modified with Titanium Dioxide Nanoparticles: An In Vitro Study.

AIMS: To assess the effect of titanium dioxide nanoparticles (NPs) on flexural strength and cytotoxicity of heat-cured polymethyl methacrylate (PMMA) resins. METHODOLOGY: Sixty-four rectangular and 12 circular specimens were fabricated from metal dies to test flexural strength and cytotoxicity, respectively. The rectangular specimens were grouped into four (16 specimens each)-control group (Group 1), Group 2 with 3% TiO2, Group 3 with 5% TiO2, and Group 4 with 7% TiO2. They were tested for flexural strength using universal testing machine. The circular specimens were grouped into two (six specimens each)-control group and the test group which included the group which showed a highest flexural strength. They were tested for cytotoxicity using MTT assay. The analysis of variance (ANOVA) test was used to analyze the mean flexural strength of each group and Tukey's post hoc test, for pairwise group comparison (p <0.05). An independent sample t-test was used to analyze the cytotoxicity between the groups (p <0.05). RESULT: The study showed that there was a significant decrease in the flexural strength from the control group (mean: 298.95), which reduced as the concentration of TiO2 increased. However, the toxicity reduced considerably from 24 hours to 7 days in both groups while the test group showed better cell viability (%) than the control group. CONCLUSION: The flexural strength of heat cure acrylic resin (modified and unmodified) was much higher than the recommended flexural strength for these resins. On adding TiO2 NPs, flexural strength decreased when compared to the control group. However, with 3% TiO2 NPs, there was no significant decrease in flexural strength as compared to conventional resins. TiO2 NP-modified heat cure acrylic resin showed less toxicity on day 1 and even lesser toxicity after 7 days indicating that it is biocompatible. CLINICAL SIGNIFICANCE: TiO2 NPs incorporated at 3% concentration in denture base resin had less cytotoxicity and adequate flexural strength, to be used as a promising alternative to conventional denture base resin.

A Study to Determine the Correlation between the Intercondylar and Interdental Widths in South Indian Population: A Cross-sectional Study.

AIM: Anatomical landmarks that remain fairly constant throughout an individual's life help determine the position of the artificial teeth closer to that of their predecessors. The aim of the present study was to evaluate whether there is a relationship between the intercondylar widths (ICWs) and the interdental widths (IDWs) in the maxillary and mandibular arches in dentate subjects. MATERIALS AND METHODS: The study was conducted in two parts, with 80 dentate subjects in total. Initially, in the first 40 subjects, a mathematical index was obtained by dividing the mean ICWs by the mean IDWs. In the second part, the ICW was measured and was used along with the index obtained in the first part, to estimate the IDW. These estimated values were then verified with the real IDWs by direct intraoral measurements. An arbitrary earpiece facebow (ARTEX® Gesichtsbogen Facebow) was used to measure the ICW. Statistics was done using SPSS software version 18 using Karl Pearson's correlation test and paired t-test. RESULTS: The IDW was correlated to the ICW; the maximal correlation was found between ICW and lower 6-6 width (L6-6W) (p value 0.033) and the lowest correlation was found between ICW and upper 6-6 width (U6-6W) (p value 0.046). CONCLUSION: ICW can be used as an additional guide to position denture teeth. This method suggested would result in a better buccolingual positioning of the posterior teeth, which would help avoid encroaching on the tongue space, thereby improving phonetics and speech with dentures. CLINICAL SIGNIFICANCE: ICW bears a relationship with the IDWs in the maxillary and mandibular arches. ICW being a fairly constant anatomical landmark can be used as an additional guide aid in positioning the artificial teeth.

Microbial Analysis and Determination of Antibiotic Susceptibility of Dental Laboratory Equipments and Laboratory Attire.

CONTEXT: This study was done to determine the level and type of microbial contamination present on the surface of various dental laboratory equipment and laboratory attire and to determine the antibiotic susceptibility pattern of these isolated pathogens. SUBJECTS AND METHODS: The samples were divided into following groups: six groups of dental laboratory equipment (articulators, facebow, fox plane, polishing buff, micromotor handpiece, and surveyors) and dental attire of laboratory technicians and students. A total of 33 swabs were collected from each dental laboratory equipment, namely, articulators, facebow, fox plane, polishing buff, micromotor handpiece, and surveyors. The dental laboratory attire of students and dental technicians were analyzed separately. The swabs were collected from the laboratory attire at the end of the week, and they were washed once a week and at the beginning of the week. The groups are Group 1 - dental laboratory attire (students), Group 2 - dental laboratory attire (technicians), Group 3 - polishing buff, Group 4 - facebow, Group 5 - surveyor, Group 6 - fox plane, Group 7 - articulator, and Group 8 - micromotor handpiece. The moistened swabs were inoculated into the broth and subcultured on to the MacConkey Agar plates, and then incubated aerobically at 37°C for 24 h. The organisms were identified based on colony morphology, Gram staining, and standard biochemical tests. The antibiotic susceptibility patterns of the isolated organisms were done according to the CLSI guidelines. The collected data were statistically analyzed. STATISTICAL ANALYSIS USED: The data collected were entered into a Microsoft Excel Spreadsheet and analyzed using IBM SPSS Statistics, Version 22 (Armonk, NY, IBM Corp.). The frequency and mean standard deviation of the samples were analyzed using Fisher's exact value test. Percentage of resistance among the isolates to different antimicrobials was also determined. RESULTS: The microorganisms isolated were Staphylococcus aureus, Escherichia coli, coagulase-negative Staphylococcus, Pseudomonas, Klebsiella, nonfermenting Gram-negative bacteria, and Bacillus species. The mean microbial levels in dental laboratory attire were more (5 log10 colony-forming units [CFU]) compared with dental equipment (3 log10 CFU-4 log10 CFU). Furthermore, most of the isolated organisms showed increased antimicrobial resistance. CONCLUSION: Majority of the isolated organisms were not a part of the normal oral microflora and are capable of causing various diseases. The increased resistance to the antimicrobials showed by the isolated organisms proves that there are increased chances of multiresistant organisms to occur in the future.