A Dental Filling: Step-by-step

These are pictures are a case example of a cosmetic tooth-coloured filling done here at Rosewood Dental.

A shadow of decay is confirmed under an old sealant.

The old sealant is removed. The tooth under is soft and discoloured due to decay.

Soft decay is removed and the tooth etched.

A glass liner is placed on the deepest part of the cavity. It contains fluoride to sooth the tooth.

A bonded plastic resin is placed as the final layer and polished.

The finished filling!

Types of Fillings

Minimally invasive fillings are placed on the basis that an appropriate amount of decayed tooth is removed. The tooth is repaired with a tooth-coloured restoration that bonds to and supports the remaining tooth structure. There are several different types of ‘white’ fillings.

Prior to selecting which one (or sometimes a combination), the dentist will consider the following factors:

• how the material will bond to the tooth
• how the material will seal the cavity and prevent new decay from occurring
• if the material can remineralise the surrounding tooth
• how does the material wear; its strength
• will the material protect the surrounding tooth from fracture aesthetics

Glass Ionomer Cement

First available in the early 1970s, glass ionomer cements are a highly versatile type of filling. They may be used as a cement for gluing in crowns, as a base under other filling types or an aesthetic restoration in itself. GICs have moderately-good aesthetics, maintain tooth structure and assist in the process of remineralisation.

Like our saliva, GICs contain mineral ions that can be exchanged in and out of tooth structure. Minerals from GICs diffuse into the tooth structure and form a chemical bond to dentine and enamel. In this way they are one of the few biologically active fillings. Fluoride and other tooth-strengthening mineral ions inactivate bacteria and sooth the pulp of the tooth in deep fillings. The exchange of ions also allows tooth, previously softened by decay, to re-harden. In contrast, an inert filling like composite or amalgam does nothing to change the tooth structure under the filling, and requires all soften tooth, as well as decay to be cut out. GIC acts like a reservoir or sponge; minerals that are leached out can later be recharged by brushing with fluoride tooth paste. Plaque bacteria are unable to grow well on the surface of GICs. GICs are compatible with gum tissue (due to the lack of plaque) so can be placed close to gumlines. One disadvantage of GICs is that they are relatively soft, and can wear down or dissolve over many years. They are also brittle and may fracture if placed on a corner. Due to this, we at Cornerstone dental use GICs on small fillings not under biting stresses, under most composite fillings as a sandwich fillings and on sides of teeth. They may also function as temporary fillings.

Glass ionomer is a water-based cement. It is formed from the reaction of an acid (polyalkenoic acid) with a powdered glass base (including fluoride, calcium or strontium aluminosilicate). When the dentist is ready to use this material, the tooth is first conditioned, and an assistant will mix a capsule containing the filling’s components into a tooth-coloured putty.

‘Fuji VII’, ‘Riva Protect’

This is a high fluoride releasing filling material that allows enhanced remineralisation of surrounding tooth structure. It is more of a solid white colour, so it useful as a base under deep fillings, fissure sealants, and temporary fillings to stabilize decay when many teeth are involved. It may also prevent plaque from growing around the filling itself. A pink-coloured form of this filling has added pigments that make the it heat up and set faster under blue light.

Glass ionomer is one of the best materials for a tooth with minor first-time decay on the biting surfaces.

Composite Resin

Composite resins were first developed over 40 years ago, with many advances in the material since then.

Composite Resins are ceramic-filled polymers which are set hard by blue light. The qualities of composite resin include excellent aesthetics, good physical properties like hardness. The major components inlcude a resin matrix (Bis-GMA), glass filler particles (containing aluminum, barium, strontium, zinc, zirconium or quartz), coupling agents and light activating agents. When set under blue light, composites can shrink slightly, so care must be taken to cure the filling in layers.

Composite adheres to the tooth by microscopically interlocking into the rough and jagged surface of cut, etched enamel. It does not bond as well to dentine, the living inner layer of the tooth, because it is always slightly moist, and resin is hydrophobic (similar to oil, doesn’t like water). We overcome this problem by placing glass ionomer as a base, and add the hard composite layer on top. This way the filling has the best of both worlds- the base layer releases fluoride and minerals, bonds to dentine and stops bacteria from growing. The top layer is hard and strong, bonds well to enamel, and has greater aesthetics.

Amalgam

Dental amalgam is an alloy of silver, copper, tin mixed with mercury. It is an economic, highly reliable, long-lived restoration, and still is the best filling type for high stress/load bearing areas.

Taking into the account of the principles of minimal intervention, modern restorative practice, general public health and environmental principles, we limit the use amalgam fillings in our treatment planning. However, we do not object to the use of amalgam fillings on the rare occasion where it may be the most appropriate restorative option, for example, for very large fillings when a crown is not financially viable, and where is difficult keep an area dry enough.

Unfortunately, many patients have been advised or request to have existing amalgam fillings replaced in the mistaken believe that this will improve their general health, or result in a cure for chronic afflictions. Health authorities consistently reject these reasons for removal, or avoidance for placement, citing evidence from many very large, significant studies.