The Journal of Indian Prosthodontic Society (Jan 2018)

A comparative evaluation of vertical marginal fit of provisional crowns fabricated by computer-aided design/computer-aided manufacturing technique and direct (intraoral technique) and flexural strength of the materials: An in vitro study

  • Ishita Dureja,
  • Bhupender Yadav,
  • Puja Malhotra,
  • Nupur Dabas,
  • Akshay Bhargava,
  • Ripul Pahwa

DOI
https://doi.org/10.4103/jips.jips_306_17
Journal volume & issue
Vol. 18, no. 4
pp. 314 – 320

Abstract

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Background: With the advent of new provisional crown materials, it has become imperative to evaluate their marginal fit and strength to select the ideal provisional crown material. Aim: The purpose of this in vitro study was to evaluate and compare the vertical marginal fit and flexural strength of provisional crowns prepared using computer-aided design-computer-aided manufacturing (CAD-CAM) temporary material versus those fabricated using bis-acrylic composite-based autopolymerizing resin material. Materials and Methods: Eighty samples were divided into two equal Groups (I and II). Group I consisted of forty samples that were evaluated for flexural strength and Group II consisted of forty samples that were evaluated for their vertical marginal fit. Group I was subdivided as Group IA, i.e., bis-acrylic composite-based autopolymerizing resin material (Protemp™ 4) blocks and Group IB, i.e., CAD/CAM provisional material blocks. Similarly, Group II was subdivided as Group IIA, i.e., bis-acrylic composite-based autopolymerizing resin material (Protemp™ 4) crowns and Group IIB, i.e., CAD/CAM provisional material crowns. Marginal adaptation was evaluated using stereomicroscope and image analyzing software to measure the amount of marginal gap. For flexural strength, all specimens were subjected to a standard compression load in the universal testing machine until fracture occurred. Data were analyzed using Student's t-test (P = 0.001). Results: CAD/CAM provisional crowns showed better marginal adaptation (34.34 μm) as compared to bis-acrylic composite-based autopolymerizing resin material (Protemp™ 4) crowns (63.42 μm) (P 0.001). Conclusion: Protemp™ 4 and CAD/CAM provisional materials have comparable flexural strength. However, the marginal fit of temporary crowns fabricated by CAD/CAM was found to be superior to the ones fabricated using bis-acrylic composite-based autopolymerizing resin material (Protemp™ 4).

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