AMALGAM FILLING REPLACEMENT
The Dental Mercury Controversy
While there is no disputing the toxicity of mercury to human tissue and its cumulative degenerative effects on neural and brain tissue, there exists no universally accepted scientific data to date to substantiate the claim that mecury in dental fillings have an adverse effect on your health. The main reason today for removal of old amalgam filings is to remove recurrent decay and improve dental aesthetics.
The primary reason for using dental amalgam (a compound of mercury approximately 50% and silver, copper, zinc and tin 50%) is that it is cheap and easy to use even in the hands of less skillful clinicians. For this reason dental amalgam remains the filling material of choice today in third world countries.
Dental amalgam corrodes and turns from silver to black after a few years. This causes dark discoloration and staining of the tooth and eventual recurrence of caries (tooth decay). Amalgam fillings depend upon mechanical preparation and expansion for their retention in the tooth. This expansion of the metal alloy results in internal fractures of the tooth and frequent shearing loss of cusps. The fractured tooth then requires a crown and possible a root canal treatment. In some cases periodontal crown lengthening procedures to access a supra-bony margin or even extraction is required.
Gold remains the most durable, serviceable and tissue compatable restorative material in dentistry. Gold has three drawbacks. It is expensive, requires high levels of clinical skills and is not aesthetic for restoring anterior teeth. Very few dentists in the UK provide gold inlays despite a revival in North America and Europe.
Until about fifteen years ago, composite fillings had a shorter service life than amalgam. Whilst the dentine bonding techniques and composites have improved, the service life of composite fillings varies directly with the clinical skills and knowledge of the restorative dentist. A similar situation occurs with porcelain inlays and onlays. These are harder more durable restorations that are fabricated in the dental laboratory or in a milling machine and bonded to the cavity preparation.
All too often teeth with failing dental amalgam fillings have to be re-treated with crowns. Not infrequently the residual teeth are so dark and badly stained that they can not be restored with porcelain crowns as the colour would shine through. Metal ceramic crowns are usually required to mask out this black discoloration. Metal ceramic crowns can never look as natural as an all-porcelain alternative. More recent ceramic-porcelain veneer restorations can mask out moderately discolored teeth with pleasing aesthetic results.
Today, in the 21st century, there can be very justification other than economic reasons for placing amalgam fillings in patient's teeth. I, personally, have not placed an amalgam filling in a patient's tooth for more than ten years and never will.
