title: 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.
authors.affiliation: Department of Prosthodontics, Preclinical Education and Dental Materials Science, Welschnonnenstr.17, 53111 Bonn, Germany. sbayer@uni-bonn.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Bayer
authors.forename: Helmut
authors.initials: H
authors.lastname: Stark
authors.forename: Lina
authors.initials: L
authors.lastname: Gölz
authors.forename: Ludger
authors.initials: L
authors.lastname: Keilig
authors.forename: Dominik
authors.initials: D
authors.lastname: Kraus
authors.forename: Anja
authors.initials: A
authors.lastname: Hansen
authors.forename: Norbert
authors.initials: N
authors.lastname: Enkling
mesh_terms: D001696:Biomechanical Phenomena; D003442:Crowns; D003799:Dental Stress Analysis / Q000295:instrumentation; D003779:Denture Design; D003781:Denture Retention; D003828:Denture, Overlay; D003830:Denture, Partial, Fixed; D003832:Denture, Partial, Removable; D005500:Follow-Up Studies; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000534:rehabilitation; D013314:Stress, Mechanical
chemical_list: D006047:Gold Alloys