It refers to all the techniques to restore missing tooth structure with filling, inlays, onlays, etc.
A cavity or tooth decay occurs when the enamel (and dentin in some instances) on a tooth gets de-mineralised and infected with bacteria. Filling then, needs to be done, where the infected and de-mineralised part of the tooth/teeth is removed and the space filled with filling material.
Dentists have an array of filling material to choose from today to repair missing, worn, damaged or decayed teeth – thanks to advances in this field – and are able to create pleasing and natural-looking smiles using ceramics and polymer compounds that mimic natural teeth.
Several factors influence the performance, durability, longevity and cost of dental restorations. These include the patient’s oral and general health, components used in the filling material, where and how the filling is placed, the chewing load that the tooth will have to bear, and the duration and number of visits needed to prepare and adjust the restored tooth.
Types of Dental Restorations (fillings)
Dentists have used Amalgam Fillings for more than a century. Dental amalgam is the most researched and tested restorative material among all in use. It is durable, easy to use, highly resistant to wear and tear, is relatively inexpensive compared to other materials, and remains a valued treatment option for dentists and their patients. It is a stable alloy made by combining elemental mercury, silver, tin, copper and some other elements.
Amalgam fillings can withstand very high chewing loads and are particularly useful for restoring molars in the back of the mouth where the chewing load is greatest. They are also used in areas where a cavity preparation is difficult to keep dry during the filling replacement, such as in deep fillings below the gum line. Amalgam fillings, like other filling materials, are considered biocompatible and are well tolerated by patients.
There are a few disadvantages of amalgam – there could be some short-term sensitivity to heat or cold after the filling is done. It is silver coloured and does not look natural. Furthermore the dentist may need to remove more tooth structure to accommodate an amalgam filling than other types.
Composite Fillings (Tooth Coloured)
When glass or quartz filler is mixed in a resin medium, it produces a filling that is tooth-coloured. This is a composite or filled resin. Composite fillings are durable and are fracture-resistant in small and mid size restorations in teeth that handle moderate chewing pressure. Less tooth structure is removed during preparation, resulting in a smaller filling than that of an amalgam. Composites can also be “bonded” or adhesively held in a cavity, often allowing the dentist to make a more conservative repair to the tooth.
The cost is moderate and depends on the size of the filling and technique used by the dentist to place it in the prepared tooth. It generally takes longer to place a composite filling than an amalgam filling.
Glass ionomers are translucent, tooth-coloured materials made of a mixture of acrylic acids and fine glass powders, and are used to fill cavities on the root surfaces of teeth. Glass ionomers release a small amount of fluoride, which is beneficial to patients at risk of decay. Very little tooth structure needs to be removed when a dentist prepares a tooth for a glass ionomer.
Glass ionomers are primarily used in teeth that are not subject to heavy chewing pressure, as they have a low resistance to fracture. They are mainly used in small non-load bearing fillings or on the roots of teeth. Resin ionomers also are made from glass filler with acrylic acids and acrylic resin and are used for very small, non-load bearing fillings on the root surfaces of teeth, and have low to moderate resistance to fracture.
Ionomers experience high wear and tear when placed on chewing surfaces. They mimic natural teeth as far as the colour is concerned but lack the natural translucency of enamel. There have been very few instances of allergies to this – and are normally well tolerated by patients.
Indirect Restorative Dental Materials ( Two or more visits)
Sometimes the best dental treatment for a tooth is a restoration made in a lab from a mould. These custom-made restorations, which require two or more visits, can be a crown, an inlay or an onlay. A crown covers the entire chewing surface and sides of the tooth, while an inlay is smaller and fits within the contours of the tooth.
An onlay is similar to an inlay, but is larger and covers some or all the chewing surfaces of the tooth. The cost of indirect restorations is generally high due to the number and length of visits required, and the additional cost of having the restoration made in a dental laboratory. Materials used to fabricate these restorations are porcelain (ceramic), porcelain fused to a metal-supporting structure, gold alloys and base metal alloys.
All – Porcelain (Ceramic) Dental Materials
All-porcelain (ceramic) dental materials such as porcelain, ceramic or glasslike fillings and crowns, are used as inlays, onlays, crowns and aesthetic veneers. A veneer is a very thin shell of porcelain that can replace or cover part of the enamel of the tooth. All-porcelain (ceramic) restorations are particularly desirable because their colour and translucency mimic natural tooth enamel.
All-porcelain restorations require a minimum of two visits or more. They are prone to fractures when placed under tension or on impact. The strength of this type of restoration depends on an adequate thickness of porcelain and the ability to be bonded to the underlying tooth. They are highly resistant to wear and tear.
Porcelian – fused-to-Metal
Another type of restoration is the porcelain-fused-to-metal, which provides strength to a crown or bridge and is very strong and durable.
Porcelain bonded to a supporting structure of metal creates a stronger restoration than using porcelain used alone. But, much of the existing tooth needs to be removed to accommodate the restoration. Although they are highly resistant to wear and tear themselves, porcelain restorations can wear out opposing natural teeth if the porcelain surface becomes rough.
Gold alloys contain gold, copper and other metals and are a strong, effective filling, crown or a bridge. They are primarily used for inlays, onlays, crowns and fixed bridges and are highly resistant to corrosion and tarnishing.
Gold alloys are strong and tough and can resist fracture and wear and tear. Very little of the healthy tooth structure needs to be removed when preparing for restoration. Gold alloys are also gentle to opposing teeth and are well tolerated by patients. However, the only down side is that they do not look like natural teeth.
Base Metal Alloys
Base metal alloys are silver-coloured, non-noble metals and are used in crowns, fixed bridges and partial dentures. They are resistant to corrosion and tarnishing and are strong and tough. Their metallic colour is their only problem, as they do not look like natural teeth.
Crowns, inlays and onlays can be made in labs using dental composites. These materials are similar to those used in direct fillings, are tooth-coloured and do not excessively wear out opposing teeth. Their strength and durability is not as high as porcelain or metal restorations and they are prone to wear and tear and discoloration