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BACKGROUND: Dental ceramics are known for their natural appearance and their durable chemical and optical properties, and their uses mainly reflect their excellent aesthetic properties, biocompatibility and resistance to wear. In addition, dental ceramics are considered to be chemically inert restorative material with large differences in the chemical compositions and microstructures. Although ceramics exhibit excellent physical properties and biocompatibility, the oral environment presents a series of external factors that affect its physical and mechanical properties in its long term function. AIMS AND OBJECTIVES: The aim of this study is to compare and evaluate the surface roughness of 2 dental ceramics (Noritake® & IPS Emax ceram) before and after exposure to an aerated drink, a mouthwash and simulated vomit solution with distilled water. MATERIALS AND METHODS: 128 ceramic discs were made, 16 for each of the 4 groups of 2 ceramics to be tested. It was fabricated in the form of discs of diameter 10 mm × 2 mm thickness. The test specimens were calibrated by grinding, using a medium grit diamond bur. Both the above specimens were divided into 4 groups of 16 each. They were then subjected to test solutions. Each specimen in a group was immersed in the following solutions: Coca-Cola, chlorhexidine mouthwash, simulated vomit solution and distilled water. RESULTS: The results analyzed statistically using one way ANOVA (analysis of variance), paired t test and independent t test. CONCLUSION: Within the limitations of this study, it was concluded that the surface roughness of the evaluated ceramics increased upon exposure to Coca-Cola, chlorhexidine mouthwash and simulated vomit solution. Simulated vomit solution caused the maximum change in surface roughness followed by coca cola and then chlorhexidine mouthwash. No changes were observed after immersion in distilled water. Noritake® showed slightly more resistance to change in surface profile when compared to IPS e.max.
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AIM: Dental professionals are prone to have hearing impairment due to prolonged exposure of noise in dental college. The aim of the study was to assess the hearing ability of dental personnel working in Yenepoya Deemed to be University, Mangaluru, Karnataka, India. MATERIALS AND METHODS: A cross-sectional exploratory study was conducted on 60 subjects (30 male and 30 female). Audiometric analysis was carried out using pure-tone audiometry (PTA) and otoacoustic emission test (OAE). STATISTICAL ANALYSIS: Data were calculated and analyzed using two-way analysis of variance and Tukey's honestly significant difference test. RESULTS: No statistically significant difference was observed between hearing loss and its association with age, gender, working experience, mean daily working time, and specialization. PTA results showed a statistically significant hearing loss in the left ear, showing a dip at frequency of 4000 Hz among working experience group of 11-15 years and at 6000 Hz for 21-25 years. Also, a statistically significant hearing loss was observed in the left ear at 6000 and 8000 Hz for the age-group of 51-55 years. OAE results were consistent with PTA findings. CONCLUSION: Dentists and dental personnel are at a higher risk of noise-induced hearing loss. As the working experience increases, the threshold shift is seen to shift from 4000 to 6000 Hz, which is indicative of sensorineural hearing loss due to noise-induced dental environment.
RESUMEN
AIM: Zirconia-based restoration is successfully replacing metal ceramic restorations in posterior areas. Although higher mechanical properties of zirconia, their use in compromised situation is questionable. Hence, there is a need to modify the design which to strengthen the framework. The aim of this in vitro study was to evaluate the influence of lingual collar design on the flexural strength of CAD/CAM-fabricated posterior three-unit zirconia framework. MATERIALS AND METHODS: A mandibular metallic stainless steel master mold is designed for a three-unit fixed partial denture framework. All CAD-milled 20 samples are divided into two groups based on the design. Group A--with collar (10 samples) and Group B--without collar (10 samples), tested using universal testing machine to calculate the mean fracture load and flexural strength. STATISTICAL ANALYSIS USED: Descriptive statistics and independent sample t test were used to find the difference between the groups, and simple linear regression was used to find the relationship between load and displacement between the groups. RESULTS: The result of the mean flexural strength for Group A was 11328.06 ± 3770MPa and for Group B was 7633.95 ± 3196MPa; the mean fracture strength observed for Group A was 1274.04 ± 424MPa and for Group B was 858.80 ± 359MPa. A statistically significant difference was observed in flexural strength between Groups A and B (P < 0.05). CONCLUSION: Zirconia framework with connector dimension of 7 mm2 with lingual collar design can be successfully incorporated in compromised situation where an ideal connector dimension of 9 mm2 cannot be placed.