Evaluation of Discrepancy in Margin Adaptation of Metal Copings Fabricated by Conventional Casting, CAD/CAM And Direct Metal Laser Sintering- A Comparartive In-Vitro Study.

Abstract

Objectives:To evaluate the marginal fit of metal copings fabricated by casting, to evaluate the marginal fit of metal copings fabricated by CAD/CAM, to evaluate the marginal fit of metal copings fabricated by Direct Metal Laser Sintering and To compare the marginal fit of metal copings fabricated by  casting, CAD/CAM and Direct Metal Laser Sintering.

Methodology:A total 30 copings were fabricated on a CAD milled die which was received by scanning a prepared mandibular 1^st molar typhodont tooth. Out of the 30 copings ,10 copings were obtained by casting, 10 copings by direct metal laser sintering and 10 copings by CAD/CAM. The 30 copings that were obtained from three different fabrication technique were then evaluated for marginal discrepancy. The copings were not cemented on the master die model to obtain standardization for all copings. The marginal discrepancy were then evaluated and calculated with help of image analyzer attached to the stereomicroscope on four sides that is  mesial, distal, buccal and lingual. 

Results: The statistical analysis revealed that the maximum discrepancy was seen  in Group A which were copings fabricated by casting with mean marginal discrepancy value of 56.875 mm, then followed by CAD/CAM with mean marginal discrepancy value of 31.175 mm and the least marginal discrepancy value were seen in group C which were copings fabricated by Direct Metal Laser Sintering with mean marginal discrepancy value of 24.4 mm. There was not much difference between Group B and Group C which were copings fabricated by CAD/CAM  and Direct Metal laser Sintering with the difference being 6.775 mm between the two groups. However in contrast the mean marginal discrepancy value between Group A and group B were statistically significant with mean difference of 25.7 mm and also between group A and group C with mean difference of 32.475 mm.

Conclusion: The mean marginal discrepancy observed in all the three groups were within the clinical accepted range (100-120 mm) but it can be concluded that in order to have optimum results we can opt for Direct Metal Laser Sintering technique or CAD/CAM as a technique for fabrication of metal copings.