Evaluation of the marginal fit of full contoured zirconia, lithium disilicate and metal crowns fabricated using CAD-CAM: An in vitro study.

Introduction: The marginal fit of any dental restoration is vital to its long-term success. Lack of adequate fit is potentially detrimental to both the tooth and the supporting periodontal tissues. The purpose of this study was to evaluate the marginal fit of monolithic zirconia, monolithic lithium disilicate and monolithic metal crowns and compare the three groups. Methods: The study was conducted by fabricating ten samples for each group, total of 30 samples. A premolar stainless steel die was used to standardize the preparation. PVS putty material was used to make impressions of the model and was poured using type IV die stone. The samples were all fabricated using CAD-CAM. The marginal gap was measured by SEM, and the results were analysed using SPSS software. Results: The mean marginal gap of zirconia, metal and lithium disilicate crowns was 79.49 µm, 46.83 µm and 70.79 µm, respectively. Discussion: The metal group showed the lowest marginal gap among the groups. This difference in marginal fit is due to the sintering process where the organic binders in soft metal burn out and the metallic powder particles are being sintered (caked) without creating a fused phase. Clinical Significance: Marginal fit plays a very important role in the long-term success of a crown. Discrepancy in marginal fit results in food and plaque accumulation causing caries and periodontal breakdown, eventuating the failure of the restoration. A perfect marginal fit would enhance the longevity of any indirect restoration. Knowledge about which indirect restoration has the best marginal fit is critical.

Assessment of Periodontal Disease Among the Dental Prosthetic and Nonprosthetic Wearers in an Adult Rural Population in Mangalore Taluk, South India.

BACKGROUND: Oral health as an integral part of general health. Rural population neglect oral health as they lack awareness on oral diseases and also due to inadequate availability of dental services. There is a very high prevalence of chronic inflammatory periodontal disease in the rural Indian population, which is left untreated. Hence, this cross-sectional survey was taken up in the rural area of Mangalore taluk, Karnataka, India. MATERIALS AND METHODS: A cross-sectional survey was carried out on 1312 participants aged 18 years and older. The prevalence of periodontal disease among the dental prosthetic and nonprosthetic wearers was assessed. The World Health Organization format was used to record the periodontal status and loss of attachment. Data collected were analyzed using chi-square test. P < 0.05 was considered as significant. RESULT: Of the 1312 included subjects, 520 were males (39.6%) and 792 were females (60.3%). Periodontal status showed that calculus was found to be high among all age groups. When the prevalence of periodontal disease was assessed among the prosthetic wearers, it was found that subjects wearing removable partial denture showed increased prevalence of periodontal pocket depth and attachment loss irrespective of age group, gender, and educational qualification. CONCLUSION: Lack of awareness among the individuals regarding periodontal diseases has been associated with consistently higher prevalence of periodontal diseases and treatment needs. Demographical studies need to be carried out at regular intervals, thus helping in planning the treatment needs nationwide for better oral health care in rural population.