Creep as a Mechanism for Sealing Amalgams

Abstract

SUMMARY INTRODUCTIONMicroleakage in dentistry has been studied for more than 50 years (Buchanan, 1951;Massler & Ostrovsky, 1954). Through the use of varied techniques and different test media, such as dyes and radioactive materials, microleakage is one of the most widely studied phenomena (Cochran & others, 2004). Kidd (1976) defined microleakage as the passage of bacteria, fluids, molecules or ions along the interface of a dental restoration and wall of the cavity preparation. Hilton (2002a,b) reports that biofilm between the tooth and restoration has been associated with staining at the margins, secondary caries and a general failure mechanism of the restoration. The two papers by Hilton (2002a,b) examine the background, current status and methodology for accomplishing reduced microleakage. Part I (Hilton 2002a) specifically discusses dental amalgam and its microleakage patterns.Studies by Phillips (1961, 1962) indicated that restorative materials exhibited microleakage and showed that the amalgam had an unusual ability to seal itself over time. A few years later, the sixth edition of Skinner and Phillips' Essentials of Dental Materials (1967) Creep may be a major factor in amalgam sealing from microleakage. Creep expansion causes amalgam to fill in the tooth/amalgam interface gap and causes the restoration to extrude out of the preparation.

Preliminary Evidence That Bioactive Cements Occlude Artificial Marginal Gaps

“…[11][12][13][14][15] The limited protective properties of current restoratives underscore the significant challenge that secondary caries still presents as a failure mode for restorative materials. Notwithstanding the long-standing observation that dental amalgam occludes marginal defects by either deposition of metallic corrosion products and/or material creep mechanisms; 16,17 no other currently available direct or indirect dental material has demonstrated an analogous ability to seal or reseal marginal defects. 18 Clearly, additional functionalities added to dental restorative materials could augment fluoride release to improve longevity of dental restorations, especially by improving long-term marginal stability of dental restorations.…”

Microleakage of Repaired Amalgam

“…Amalgam alloy show reduce in the microleakage overtime, this reduction has been explained by corrosion products filling the interface gap in order to seal the restoration. (20) Amalgam restoration is still the best material used for amalgam repair even without bonding material. From clinical point, repair cause less damage than complete replacement of amalgam and it is therefore preferred.…”

A timeline of biological assessments: Our nonspatial continuum

“…In 1983, Lin demonstrated that low-copper amalgam had a greater potential for corrosion-ultimately reducing microleakage along the restorative interface [107] [108]. However, due to an almost phenomenological hyperbole regarding mercury toxicity & the rapid emergence of glass ionomers & adhesive restorations since the 1970's, caused a decline in amalgam placement.…”