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PURPOSEThis study was aimed to determine the effect of two chemically distinct denture cleansers and water on the surface hardness of acrylic and silicone based soft denture liners at various time intervals.MATERIALS AND METHODSTwo commonly used commercial resilient liner material were selected based on their chemical composition (silicone- and acrylic-based soft liners) for this investigation. 120 cylindrical specimens were made of 15 mm × 10 mm dimensions (according to ASTM: D-2240-64T) in a custom made metal mold. All specimens were stored in artificial saliva throughout the study. Forty specimens were cleansed daily in 0.5% sodium hypochlorite solution; forty were cleansed in sodium perborate and remaining forty specimens were daily rinsed in water. Testing was done at 1 week, 1 month, 3 months and 6 months for surface hardness using a Shore A Durometer. A mean of 3 reading for each sample was subjected to one-way ANOVA, Post Hoc test and pair-t test for statistical analysis. P values of less than 0.05 were taken as statistically significant.RESULTSSurface hardness of all the samples was significantly higher after a period of 6 months irrespective of the cleansing treatment. Minor changes were observed between control, sodium hypochlorite and sodium perborate groups with time. Greater change was observed in surface hardness of acrylic-based soft denture liners as compared to silicone-based soft liners for all groups, as time progressed.CONCLUSIONSilicone-based soft denture liners performed significantly better in all cleansing treatments than acrylic-based soft denture liners.

Abstract“The best of friends fall out with time and so do teeth.”Thus, there is a need to replace the lost teeth and the supporting structures for the patient's social demands and functional rehabilitation. Prosthetic treatment with complete dentures is a very common treatment modality; the biggest challenge in its fabrication is to duplicate the normal vertical dimension. Failure can be avoided by completing the treatment without changing the vertical dimension and obtaining an optimal facial proportion. There are many methods to record VD. Radiographic cephalometry has been used as a diagnostic tool in Prosthodontics for over five decades and numerous authors, like Ricketts (1981), McNamara (1984) and Slavicek (1984) developed and computerized these techniques to co-relate and record VD in patients. However cephalometric analysis can help to visualize skeletal and facial proportion relation. The present study was done to use the lateral radiographs with cephalometric analysis, as it could be a simple, non-technique sensitive, non-invasive and atraumatic way to determine VD for complete denture patients and also to compare physiologic methods (swallowing/phonetics) with cephalometric method to record lower facial height.

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Aim: To evaluate surface hardness and dimensional accuracy of type IV dental stone after incorporation of disinfectants. Materials and methods:A total of 100 specimens, 50 (40 mm × 10 mm) disk shaped and 50 frustum cone shaped, were fabricated from type IV dental stone after incorporation of various disinfectants, namely glutaraldehyde (2%), iodophor (1.76%), chlorhexidine (2%), and sodium hypochlorite (1%), for evaluation of surface hardness and dimensional accuracy. Surface hardness was tested after 1-and 24-hour time interval using Rockwell hardness testing machine. Dimensional accuracy was measured using traveling microscope. Data obtained were compiled and analyzed statistically by using analysis of variance and post hoc test. Results:Results showed significant decrease in surface hardness of samples incorporated with disinfectants at 1 hour as compared with control (distilled water). Surface hardness of all the samples increased with time and was almost equal to control group at 24-hour interval, with iodophor showing the maximum value in comparison with the other disinfectants used. When dimensional accuracy of all the groups was compared, iodophor and sodium hypochlorite were found to cause negative alterations. Conclusion:Within the limitations of this in vitro study, it was concluded that incorporation of disinfectants in die stone during mixing did not affect the hardness value at 24-hour interval. Dimensional accuracy was altered by iodophor and sodium hypochlorite, but remained unaffected by chlorhexidine and glutaraldehyde. Keywords