Effect of preparation design on the fracture resistance and fracture patterns of 3D printed one-piece endodontic crowns

J Prosthet Dent. 2024 Sep;132(3):592.e1-592.e7. doi: 10.1016/j.prosdent.2024.06.004. Epub 2024 Jul 3.

Abstract

Statement of problem: The impact of various preparation designs on the fracture resistance and fracture type of mandibular premolars restored with 3 dimensionally (3D) printed, 1-piece endodontic crowns remains unclear.

Purpose: The purpose of this study was to investigate the effect of different preparation designs on the fracture resistance and fracture patterns of mandibular premolars restored with 3D printed 1-piece endodontic crowns after thermal aging.

Material and methods: Forty-five freshly extracted mandibular premolars received 3 different preparation designs: with at least 2 intact cuspal walls (2CW), with only 1 intact cuspal wall (1CW), and no cuspal wall present (NoCW). One-piece endodontic crowns were designed by using a computer-aided design (CAD) software program, 3D printed, cemented to the prepared teeth with self-adhesive resin cement, and thermocycled between 5 °C and 55 °C in artificial saliva. Subsequently, all specimens were subjected to a fracture test. The results were statistically analyzed using 1-way ANOVA (α=.05), and fracture types of all specimens were examined using a light microscope.

Results: The analysis of fracture resistance values across separate designs revealed no statistically significant differences (P>.05). Mean fracture resistance values were 724.5 N in 2CW, 713 N in 1CW, and 861 N in NoCW. In 2CW and 1CW, the 1-piece endodontic crowns mostly displayed Type III fractures, whereas those in NoCW exhibited a combination of Type II and Type III fractures.

Conclusions: The mandibular premolar 1-piece endodontic crowns tested in this study exhibited similar fracture resistance and type of fracture with different preparation designs.

MeSH terms

  • Bicuspid*
  • Computer-Aided Design*
  • Crowns*
  • Dental Prosthesis Design*
  • Dental Restoration Failure
  • Dental Stress Analysis*
  • Humans
  • Printing, Three-Dimensional*
  • Tooth Fractures