Evaluation of marginal/internal fit of chrome-cobalt crowns: Direct laser metal sintering versus computer-aided design and computer-aided manufacturing

Niger J Clin Pract. 2016 Sep-Oct;19(5):636-44. doi: 10.4103/1119-3077.188699.

Abstract

Background and purpose: The purpose of this study was to evaluate the internal and marginal fit of chrome cobalt (Co-Cr) crowns were fabricated with laser sintering, computer-aided design (CAD) and computer-aided manufacturing, and conventional methods.

Materials and methods: Polyamide master and working models were designed and fabricated. The models were initially designed with a software application for three-dimensional (3D) CAD (Maya, Autodesk Inc.). All models were fabricated models were produced by a 3D printer (EOSINT P380 SLS, EOS). 128 1-unit Co-Cr fixed dental prostheses were fabricated with four different techniques: Conventional lost wax method, milled wax with lost-wax method (MWLW), direct laser metal sintering (DLMS), and milled Co-Cr (MCo-Cr). The cement film thickness of the marginal and internal gaps was measured by an observer using a stereomicroscope after taking digital photos in ×24.

Results: Best fit rates according to mean and standard deviations of all measurements was in DLMS both in premolar (65.84) and molar (58.38) models in μm. A significant difference was found DLMS and the rest of fabrication techniques (P < 0.05). No significant difference was found between MCo-CR and MWLW in all fabrication techniques both in premolar and molar models (P > 0.05).

Conclusion: DMLS was best fitting fabrication techniques for single crown based on the results.The best fit was found in marginal; the larger gap was found in occlusal.All groups were within the clinically acceptable misfit range.

MeSH terms

  • Bicuspid
  • Chromium Alloys
  • Cobalt
  • Computer-Aided Design*
  • Crowns*
  • Dental Casting Technique
  • Dental Cements
  • Dental Marginal Adaptation*
  • Dental Prosthesis Design / methods*
  • Humans
  • Lasers
  • Molar

Substances

  • Chromium Alloys
  • Dental Cements
  • Cobalt