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Precision of In Vivo Quantitative Tooth Wear Measurement Using Intra-Oral Scans
Published on: July 12, 2022
Telescopic crowns: extra-oral and intra-oral retention force measurement--in vitro/in vivo correlation
Stefan Bayer1, Helmut Stark, Lina Gölz
1Department of Prosthodontics, Preclinical Education and Dental Materials Science, University of Bonn, Bonn, Germany. sbayer@uni-bonn.de
Objective:
This study deals with the determination of the retentive forces of telescopic crowns measured extra- and intra-orally and the correlation of these values.
Background:
The telescopic denture is a well-documented solution for prosthetic rehabilitation for a partially edentulous jaw. Acceptable retention forces are needed to avoid inadvertent removal of the denture during movement of the jaws. Recent literature suggests 3-7 N per attachment to be acceptable. These values are only supported by in vitro studies. In vivo data are scarce, and a correlation of the in vitro and in vivo values is lacking.
Material And Methods:
Twenty-five combined fixed-removable prostheses with a total of 72 double crowns were used for extra-oral retention force measurement prior to cementation (in vitro). The intra-oral measurement was performed at 72 defined measuring points of the dentures 4-6 weeks after prosthetic rehabilitation (in vivo). A specifically designed measuring device was used.
Results:
The rank correlation showed that the in vitro and in vivo values correlate with each other (Spearman's ρ = 0.5052). Additionally, it was found that the median values measured before (1.97N) insertion of the dentures were significantly lower than after (4.70N) insertion (Mann-Whitney test, p ≤ 0.0001).
Conclusion:
The retention forces measured before and after insertion of the denture correlate with each other although their dimension is significantly higher after insertion. The reason for this behaviour might be some tilting during removal. Nevertheless, the correlation allows a prediction of the clinically relevant forces by a measurement of the extra-orally measured retentive values.
