Aim:To determine the severity and distribution of occlusal tooth wear among young North Indian adults and to evaluate the correlation of occlusal tooth wear with bite force.Materials and Methods:A total of 164 subjects were enrolled in the present study. Inclusion criteria included subjects with age range of 25-40 years having a full complement of natural dentition (excluding third molars), with no history of orthodontic treatment, FPD and trauma. Maxillary and mandibular casts of each subject were taken. Tooth wear score of anterior and posterior teeth of both the arches was calculated using a five-point (0 to 4) ordinal scoring system. The calculated tooth wear scores were then compared with data concerning age, sex, number of daily meals, vegetarian/non-vegetarian diet, Group function/Canine guided occlusion and bite force. Nonparametric (Mann-Whitney) test was used to determine the relationship between various factors and occlusal tooth wear. Spearman’s correlation coefficient was used to determine the correlation between tooth wear and bite force.Results:After applying statistical analysis to the data collected, total tooth wear score of the whole sample was 30.07 ± 6.39. Anterior teeth had significantly higher wear score than posteriors (P < 0.01). Males showed significantly higher (P < 0.001) tooth wear in both arches factors such as bite force and age showed significant correlation with tooth wear (P=0.000), however, the number of meals taken per day did not show any significant correlation. Higher tooth wear loss was seen in non vegetarian dietary pattern but it was statistically insignificant. It was also found that Group function occlusion showed significantly higher mean tooth wear loss 45.76 ± 9.19 as compared to Canine guided occlusion 26.37 ± 10.68 (P=0.000).

Most patients are concerned about the anticipated length of service and reasons of replacement of fixed dental prostheses (FPDs). This study tried to find out relationship among various factors causing failures in fixed dental prostheses. Patients treated with fixed dental prostheses were examined clinically and radiographically. A group of 106 patients were evaluated for unsatisfactory restorations. These groups of patients produced records of initial treatment to ascertain the length of service of restoration. The mean survival period of fixed dental prostheses was 7.5 years. This investigation helped find causes for failures and survival period of various FPDs. Among the reasons of failures, caries was the most frequently observed (24.2%), followed by defective margin (18.2%), unsatisfactory esthetics (15.2%), retention problem (11.7%), periodontal disease (8.8%), fractured tooth (10.6%), periapical lesion (5.8%), porcelain fracture (4.2%) and others (1.3%). Causes of failures were also grouped into two groups (Mechanical & Oral diseases) for comparison. The Mechanical group showed higher failure percentage (59.9%) as compared to Oral diseases group (38.8%).

Driven colloids are out of equilibrium systems, which self-organise into diverse complex structures, and have been one of the major driving themes in materials science. We report experimental studies on the evaporation driven self-assembly of colloidal nanoplatelets of montmorillonite and laponite. The sol-gel transition is studied using a rheometer and imaging by confocal laser scanning fluorescence microscope and an electron microscope to probe the microstructures. Evaporation driven thin films prepared from the bicontinuous gel state show increasing transparency and decreasing surface roughness with increasing concentration of laponite. Polarising optical microscope shows a microstructure with string-like birefringent domains. The scanning electron microscope reveals nacre-like structure of the films and decreasing inter-layer spacing with increasing concentration of laponite. The composite films showed superior flame-shielding property compared to the films made of individual components.

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Aim:The aim of the present study was to evaluate the effect of acidic agents on microhardness and surface morphology of two metal ceramic materials at various intervals. Materials and methods: A total of 120 metal ceramic disks were prepared and divided into two categories with 60 each. Each category was divided into two groups, group I (Made of IPS d.SIGN) and group II (made of VITA VMK), containing 30 samples each, which was subdivided into three subgroups each containing 10 samples A(i) B(i) acting as control, A(ii) B(ii) immersed in 0.5% HCl, and A(iii) B(iii) immersed in soft cola drink. Group I was tested for microhardness with Vickers microhardness testing machine at an interval of 0 minute, 24 hours, and 168 hours after immersing in acidic agents. Group II was observed for surface morphology changes with scanning electron microscope before immersion, and at an interval of 24 hours and 168 hours after immersing in acidic agents. The results were analyzed statistically, tabulated, and compared. Results: Results revealed that there was a significant decrease in microhardness of IPS d.SIGN and VITA VMK when immersed in acidic agents at an interval of 0 minute, 24 hours, and 168 hours. There were significant surface morphological changes too of both the ceramics before and after immersing in acidic agents at 24 hours and 168 hours. Conclusion: Acidic agents evaluated in the present study affected microhardness and surface morphology of both the ceramics, and IPS d.SIGN is the most suitable and would be recommended in people who consume acidic beverages. Clinical significance: Durability of dental ceramics is very good, but degradation occurs when exposed to acidic agents. All the properties of ceramics are to be known in depth as they are widely used to construct various types of prostheses, and this has to be considered especially in people who consume acidic foods and drinks.