In vitro effect of load cycling on metal-ceramic cement- and screw-retained implant restorations

J Prosthet Dent. 2007 Mar;97(3):137-40. doi: 10.1016/j.prosdent.2007.01.001.

Abstract

Statement of problem: In implant prosthodontics, restorations can either be cement- or screw-retained. Aside from passivity of fit, esthetics, and retrievability, the occlusal opening of the screw-access hole (SAH) is a major difference between the 2 types of restorations. In veneered fixed partial dentures (FPDs), the SAH forms a discontinuity of the ceramic layer and may be an origin for chipping fractures.

Purpose: The objective of this study was to investigate whether more chipping fractures occur during dynamic loading on the occlusal surface of screw-retained ceramic-veneered implant FPDs than in cement-retained restorations.

Material and methods: Ten cement-retained and 10 screw-retained ceramic veneered 5-unit FPDs were manufactured for a 3-implant situation. A masticatory simulator was used for loading the occlusal surface of the FPDs to the implant positions for 20,000 cycles with a force of 100 N applied for 1 second followed by 1 second of no loading. For analysis, 3 clinicians evaluated the FPDs using a light microscope and a dental probe. The numbers of chipping fractures found were analyzed by means of a generalized linear model with Poisson response (alpha=.05).

Results: The investigators found significantly more chipping fractures in the group of screw-retained FPDs, the rate ratio of screw-retained FPDs versus cement-retained FPDs being greater than 1 with a P value of .0023.

Conclusion: The SAH of screw-retained implant FPDs forms a weak point of the ceramic layer.

Publication types

  • Comparative Study

MeSH terms

  • Cementation
  • Dental Prosthesis Retention / instrumentation
  • Dental Prosthesis Retention / methods*
  • Dental Prosthesis, Implant-Supported*
  • Dental Restoration Failure*
  • Dental Stress Analysis*
  • Denture, Partial, Fixed*
  • Linear Models
  • Metal Ceramic Alloys*
  • Models, Dental

Substances

  • Metal Ceramic Alloys