| 3424 Dimensional Change of Restorative Materials and Cements Over Two Years | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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C.B. HERMESCH, Univ. of Texas Health Science Center, San Antonio, USA, and B.S. WALL, Univ. of Texas Health Science Center -San Antonio, TX, USA While the problem of polymerization shrinkage in some restorative materials is well recognized, the problem of dimensional expansion is less well studied. If the net expansion exceeds shrinkage as has been reported by some clinicians, the tooth or restorative material may be at risk of fracturing. Purpose: To measure the linear dimensional change of dental restorative materials and cements stored in water from immediately post-cure to 2 years. Method: Five cylindrical specimens (5mm x 12mm) for each of 20 materials were made, according to manufactures’ recommendations. Stainless steel orthodontic mesh buttons were incorporated into the specimen ends to provide stable reference points for linear measurement. Longitudinal measurements were made with a micrometer over 2 years. The mean of three measurements for each specimen was recorded. Linear dimensional change (%) was calculated from the formula=([specimen length after storage/initial length]-1) x 100. Results: % Linear dimensional change of some of the materials were:
Conclusion: All the above materials linearly expanded during 2 years of water storage. Volumetric expansion would be approximately three times the linear expansion reported here. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Seq #312 - Cements, Bond Strength, Marginal Adaptation 11:00 AM-12:15 PM, Saturday, 9 March 2002 San Diego Convention Center Exhibit Hall C | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Back to the Dental Materials: III - Ceramics and Cements Program
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