The goal of this project is to increase our knowledge of the nature and behavior of dental amalgam which will serve as a basis for improving the clinical performance of this restorative material. To achieve this goal, several areas of activity will be undertaken; (1) characterizing clinical behavior, (2) identifying in vitro property tests for predictability of clinical behavior, (3) relating composition and phase structure to clinical behavior, and (4) developing a new amalgam system. In the area of clinical behavior, the efficacy of bonding amalgam to tooth structure will be assessed by comparing marginal fracture of restorations that have been placed with and without a bonding adhesive. If bonding is effective crevice corrosion will be eliminated and marginal degradation will be reduced. The microstructural nature of gamma2-free amalgams in clinical service for at least 10 years but requiring replacement will be retrieved and characterized. The availability of these restorations is a result of a clinical study in our facility for the past 24 years in which 20 gamma-2-free amalgams have been investigated. This will serve as a model in the development of an in vitro conditioning environment for laboratory test specimens. The results of physical property tests on specimens stored in this conditioning environment will then be compared to our clinical performance data to assess test predictability. Of particular emphasis will be to identify tests that relate to the reported differences in clinical performance of the gamma2-free amalgams. Composition and phase structure of in vitro specimens will be determined by microprobe analysis to identify relationships to the clinical performance of these same alloys. An amalgam system utilizing and Ag3Sn/Cu3Sn admixture alloy will be investigated to provide a new approach to dental amalgam systems. In this system, other elements which may provide significant improvements can be efficiently introduced and tested for merit.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE002936-24
Application #
3218818
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Project Start
1977-03-01
Project End
1995-09-29
Budget Start
1992-09-30
Budget End
1993-09-29
Support Year
24
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Oregon Health and Science University
Department
Type
Schools of Dentistry
DUNS #
009584210
City
Portland
State
OR
Country
United States
Zip Code
97239
Mahler, D B; Engle, J H (2000) Clinical evaluation of amalgam bonding in Class I and II restorations. J Am Dent Assoc 131:43-9
Mahler, D B; Engle, J H; Simms, L E et al. (1996) One-year clinical evaluation of bonded amalgam restorations. J Am Dent Assoc 127:345-9, quiz 391
Mahler, D B; Adey, J D; Fleming, M A (1994) Hg emission from dental amalgam as related to the amount of Sn in the Ag-Hg (gamma 1) phase. J Dent Res 73:1663-8
Mahler, D B; Adey, J D (1991) Factors influencing the creep of dental amalgam. J Dent Res 70:1394-400
Mahler, D B; Engle, J H; Adey, J D (1990) Effect of Pd on the clinical performance of amalgam. J Dent Res 69:1759-61
Nelson, L W; Mahler, D B (1990) Factors influencing the sealing behavior of retrograde amalgam fillings. Oral Surg Oral Med Oral Pathol 69:356-60
Mahler, D B; Adey, J D (1988) Sn in the Ag-Hg phase of dental amalgam. J Dent Res 67:1275-7
Mahler, D B; Adey, J D; Marshall, S J (1987) Effect of time at 37 degrees C on the creep and metallurgical characteristics of amalgam. J Dent Res 66:1146-8
Bryant, R W; Mahler, D B (1986) Modulus of elasticity in bending of composites and amalgams. J Prosthet Dent 56:243-8