Effect of restorative procedures and materials on cusp deflection of human premolars in-vitro
Date
1997
DOI
Authors
Mansouri, Nawaf Abdul-Aziz
Version
OA Version
Citation
Abstract
Tooth fracture is a common clinical problem and has been implicated as a major reason for replacement of up to 13% of amalgam restorations and for 5 % of restorations placed in posterior teeth. A controversy exists about the strengthening effects of bonded versus non-bonded restorations on the tooth structure and to what degree the bonded restorations recover the original stiffness of the sound tooth. The objectives of this study are to assess the effects of 1) restorative methods (bonded vs. non-bonded), 2) different bonding systems and 3) size of cavity preparation on cuspal deflection in human teeth in vitro.
Thirty sound maxillary premolar teeth were mounted 2 millimeters below the CEJ with cold cure acrylic (Jet Repair Acrylic, Lang Dental Mfg., Wheeling, IL) onto aluminum cylinders. Two strain gages (S.G.) # EA-06-031-CE-350 (Micro-Measurements, Vishay) were bonded just above the CEJ of the buccal and lingual surface of each tooth. An Instron machine (Instron Corp.) was used to force a 3.8-millimeter metal ball against the tooth with maximum loads of 55 and 111 Newtons.
The test was done in two phases. In the first phase, teeth received successive preparations and restorations. In the second phase, teeth were restored with simultaneous restorations. The teeth were tested (A) sound (control), (B) prepared unrestored 1st MOD, (C) amalgam (Caulk, Milford, DE.) restoration, 2nd MOD, (D) bonded amalgam with amalgambond (Parkell, Famingdale, NY.) restoration, 3rd MOD, (E) Z-100 (3M, St. Paul, MN.) restoration, 4th MOD, (F) Tetric (Vivadent, Amherst, NY.) restoration, 5th MOD, (G) TPH (Caulk, Milford, DE.) restoration, 6th MOD and (H) Aelitefil (Bisco, Itasca, IL.) restoration (first phase). After removing the Aelitefil restoration (7th MOD) teeth were divided into six groups (second phase) each group received one of the previous restorations (C-H). All restorations were stored in water for at least 24 hours before being tested.
Average strains of both buccal and lingual surfaces were used to calculate the stiffness ratio (C= stiffness of restoration / stiffness of sound tooth). Results were analyzed with ANOVA, followed with Fisher’s pair-wise comparison with level of significance p [less than or equal to] 0.01. All bonded restorations recovered tooth stiffness significantly more than MOD and amalgam restorations in both phases (p [less than or equal to] 0.01) even with oversized cavity preparations. In the first phase, bonded restorations showed some differences that were due to the change in cavity sizes. But in the second phase with equal cavity sizes there was not any significant difference among the bonded restorations (P [less than or equal to] 0.01). There was a proportional relation between the size of the cavity and cuspal deflection. As cavity size increases cuspal deflection increases; this supports the conservative cavity preparation approach. The results of this study support the theory that bonded restorations reduce cuspal deflection under loading significantly better than non-bonded restorations.
Description
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Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 1997 (Operative).
Includes bibliographical references (leaves 109-119).
Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Dental Medicine, 1997 (Operative).
Includes bibliographical references (leaves 109-119).
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This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.