Far back in history, humans had a habit of filling the decayed teeth with inert substances, from the gold fillings found in ancient Chinese civilization to the present day composites, we have evolved a lot when it comes to restorative materials. Different kinds of materials have been used to restore a cavity, the most popular one from the late 1960s to 2000s is amalgam. History of amalgam: Dental amalgam is a mixture of silver and other metals with mercury. Silver amalgam was developed in Europe in the 1820s, but amalgam entered the USA market in the 1830s. Different compositions of amalgam were used till 1960 when G.V. Black officially standardized the composition of amalgam. Composition of amalgam: It is available as powder and liquid. The powder is an alloy of silver with other metals. Powder composition consists of- ● Silver ● Tin ● Copper ● Zinc ● Indium ● Palladium Liquid composition consists of- ● Mercury Though mercury is deemed to be harmful, many studies showed that mercury content in dental amalgams is not harmful and can be safely used. However, care must be exercised while manipulating amalgam in the dental clinic and disposing of amalgam waste.

Since the evolution of many inert and esthetic restorative materials in modern-day dentistry, amalgam replacement has been in the mind of many adults who got their silver fillings back in the day. Many factors need to be considered for judging whether the person needs amalgam replacement. 1) The lifespan of amalgam: Like any other restorative material, amalgam also has a limited lifetime of 8-10 years. When wear out of old restorations is observed, or fracture of old amalgam restorations is seen, it is better to remove and restore with modern-day composites. 2) Bonding to the tooth: Modern-day dental restorative materials are designed to bond to the tooth by using bonding agents. But amalgam is completely mechanically retained in the cavity. There is no chemical bonding of amalgam to the tooth structure. Hence there is a possibility of dislodgement of the restoration when the cavity preparation is poor. When such a scenario is observed, it is better to replace amalgam with composites. 3) Galvanic shock: When two dissimilar metals come in contact, it leads to galvanic shock. When amalgam is opposing a gold crown, a similar phenomenon is observed, which might lead to sensitivity in the patient’s teeth. Recent restorative materials completely eliminate this phenomenon as they are resin-based and do not corrode or react with other metals or materials. 4) Marginal leakage: Over a period of time, amalgam undergoes leaching, tarnish, and corrosion, which leads to marginal leakage. This leads to the formation of a marginal gap between the restoration and tooth structure. This allows bacteria and saliva to creep into the space between amalgam and tooth, and tooth decay follows. This is called secondary caries beneath the restoration. Hence it is advisable to replace such restorations with composites, as they help bond better with teeth. 5) Creep: Time-dependent plastic deformation of a material under dynamic loading forces is called creep. Amalgam exhibits this property. As a result, the material expands over time, and stress on the tooth increases, making the tooth structure weak. 6) Esthetics: Amalgam is the least aesthetic restorative material. It was preferred for the restoration of cavities in posterior teeth because of its strength. In the anterior region, it is hardly preferred as it has the property of staining the tooth and gums around the filling. If you have amalgam restorations in esthetic zones, it is better to replace them with composite restorations.

Which filling is better composite or amalgam? Modern restorative materials or composites are resin-based materials. They are inert in nature and exhibit strengths equal to that of amalgam. They are very esthetic and bond to the tooth structure chemically. However, they also have a similar life span as that of dental amalgam, around 10 years. Is it safe to have amalgam fillings removed? It is not always necessary to replace amalgam fillings. A perfectly prepared cavity with good amalgam filling serves a long time. The amount of mercury content in the dental amalgam fillings is deemed to be harmless. However, if you are cautious about esthetics or if your old silver filling is falling in the esthetic zone, you can always ask your dentist to replace the silver filling with a composite. Replacement of old amalgam restorations with composites helps achieve better tooth anatomy, less creep, more strength, and improved function./;luiytrsa