A Comparative Evaluation of the Marginal and Internal Fit of Laboratory-fabricated Monolithic Zirconia Crowns using Direct and Indirect Methods of Scanning: An in vitro Study

Abstract

ABSTRACTAimTo evaluate the marginal and internal fit of laboratoryfabricated monolithic zirconia crowns using direct and indirect methods of scanning.Materials and methodsA stainless steel master model was selected, which included stainless steel die, outer cap, and inner cap. The study was divided into two groups. In group I, direct method of scanning was carried out in which the stainless steel die was scanned directly with chairside scanner, and in group II, impression of the stainless steel die was made and gypsum die was fabricated, which was then subjected to scanning. Zirconia blanks or blocks were milled, sintered, and polished to obtain 10 zirconia crowns of each group. Replica technique was used to evaluate fit of crowns by using light body as cement analog. The crowns were then sectioned, viewed under a stereomicroscope, and each predetermined region was measured and evaluated for marginal and internal fit.ResultsThe descriptive statistics showed that the mean marginal fit for indirect method was higher compared with that for direct method. The results of paired-sample t-test revealed that mean marginal and internal fit for indirect method was on the upper side of the scale, whereas the mean for the direct method is on the lower side of the scale. Thus, the difference in the means of two methods was quite large and likely to be significant.ConclusionThe results did show better marginal and internal fit in crowns fabricated by the direct method; however, the crowns fabricated by the indirect method had more discrepancy, but were in the clinically acceptable limit.Clinical significanceThe present study would serve as a useful guide in deciding which method of scanning would give a better marginal and internal fit of monolithic zirconia crowns for longevity of restorations.How to cite this articleGandhi KN, Ram SM. A Comparative Evaluation of the Marginal and Internal Fit of Laboratory-fabricated Monolithic Zirconia Crowns using Direct and Indirect Methods of Scanning: Anin vitroStudy. J Contemp Dent 2017;7(1):22-27.