Clinical retention force development of double crowns

Abstract

This study deals with the development of the retentive forces of double crowns intraorally measured. Twenty-five combined fixed-removable prostheses with a total of 84 double crowns were included in the study. The intraoral measurement was performed at 72 defined measuring points directly adjacent to the double crowns of the dentures. The measurement was performed 4-6 weeks (baseline), 6 months (recall 1), and 18 months (recall 2) after the insertion of the restoration. A specifically designed measuring device was used. The median values for the single measuring points reached 4.705 N at the baseline, 5.190 N after 6 months, and 3.740 N after 18 months. The measured values were analyzed according to differences between the median retention forces at the three defined points in time. The statistical analysis of the median values showed no statistical difference for the retention force change after 6 months but for the decrease until the second recall (Mann-Whitney test). The retention force per denture was calculated by a summation of the single measuring points. At the baseline, 12.9 N was reached. The forces did only decrease slightly and were not statistically significant. The results indicate that retention force values of double crowns, measured intraorally at the patient, do not relevantly change clinically within the first 1.5 years. Within the limitations of this study, it can be stated that wear does not influence the retentive forces of double crowns within the first 18 months. After this period the retention force should be still sufficient for denture retention.

Evaluation of the Retention Force of Double Conical Crowns Used in Combination with a Galvanoforming and Casting Fabrication Technique

“…The absence of an intermediary agent causes significant changes in frictional wear. Bayer et al 16 also reported that the effects of saliva can be determined by analyzing the surface structures and the changes in retention force. We used saliva for the wear test in the present study to simulate clinical conditions.…”

“…The more sophisticated “double‐crown” retainer system has higher technical failure rates 3 . As reported by Becker 14 for telescopic systems and Körber 15 for conical double crowns, retention forces of 3.5 to 7 N per attachment should achieve adequate denture retention 16 . Restoration casting and fit problems due to casting shrinkage have been discussed in evaluations of the double‐crown manufacturing process 1,3 .…”

Clinical performance of non-precious metal double crowns with friction pins in severely reduced dentitions

“…In vitro studies have shown a loss of retention in telescopic and conical crowns after simulated artificial aging [1,[14][15][16]. Often, the only clinical treatment option in such cases is the fabrication of a new prosthesis.…”

Comparison of Retention Forces of Different Fabrication Methods of Co-Cr Crowns: Pre-sintered and Milled, Cast and Electroforming Secondary Crowns with Different Taper Angles

“…15,17] and few complications [17], confirm the usage of Co-Cr alloy for RDPs. Especially double crown systems, consisting of a cemented primary crown on the abutment tooth and a precisely fitted secondary crown as the removable part [12,16] have been established [12] since reliable retention forces got verified [18]. Among other things, the retention forces are influenced by the taper angle as well as the fitting of the secondary crown [13].…”