An examination of the rigidity of major connectors for removable partial dentures:  an in-vitro study investigating horizontal loading of mandibular connectors.
This study investigated the rigidity imparted by the dimensions and cross-sectional shape of major connectors for a range of arch-forms. Sixteen cobalt chromium castings in all were fabricated, four in the form of standardised lingual bars, four as thickened lingual bars, four as lingual plates and two as modified sublingual bars.  Arch-forms varied in length, radius of curvature and mid-sagittal angulation.  All connectors were tested in compression on an Instron machine with and without a resilient base.  The latter simulated the displacement of the periodontal membrane.  A further apparatus was constructed to record the transmission of applied loads to the contralateral side of the arch; again resilient material was used as an analogue to the periodontal ligament. Results indicated that connector deflection varied directly with its length and inversely with its radius of curvature and the minimum cross-section of the anterior third.  A 20 degrees  change in mid-sagittal angulation was not significant. The theoretical relationships between a connector's dimensions and its rigidity were not confirmed.  Regions of minimum connector dimension limited rigidity.  The lingual bars and plates did not distribute lateral stresses effectively to the contralateral side of the arch and were found to be less rigid than the modified sublingual bars.
Department of Prosthetic Dentistry, Eastman Dental Hospital and Institute of Dental Surgery, London, UK.
K D
KD
Cohen
M J
MJ
Faigenblum
D002858:Chromium Alloys; D003779:Denture Design / Q000379:methods*; D003832:Denture, Partial, Removable; D006801:Humans; D008422:Materials Testing; D008954:Models, Biological; D013314:Stress, Mechanical