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Fillings, Inlays & Onlays


Fillings are materials placed in the teeth to replace parts of a natural tooth. Fillings are used to repair cracked or broken teeth that have been worn down from misuse. The most common cause is dental decay.. However, other causes exist which include erosion and abrasion caused by mechanical wearing of the teeth.

If you require a filling in your tooth, a cosmetic option would be to choose a white filling material that matches the shade of your surrounding natural teeth. You can also have any existing metallic fillings replaced with tooth-coloured or 'white' fillings. This will allow you to smile without a metallic glint in sight, giving your teeth a more natural appearance overall. Here is how white fillings work:

  • This is a safe procedure that entails the removal of any decay from your tooth, and taking out the metal or amalgam fillings if you are having them replaced.
  • The new filling is made from a very hard tooth-coloured substance and will withstand the forces in your mouth when you bite and chew over a long period of time.
  • The restoration is completed in one visit and your fillings will not be visible when you smile.
Life benefits
  • Natural-looking restoration.
  • Improved cosmetic appearance of filled teeth while still being able to bite and chew as usual.
  • Hard-wearing restorative solution.
Various materials are used as fillings:
  • Amalgam: This is the oldest and still most commonly used material for replacing large amounts of tooth substance in back teeth. It is an amalgamation of various metals such as silver and copper with mercury. There has been a great deal of concern about the use of amalgam over the years particularly because of the mercury content. There is currently no proven risk to patients from the use of this material and it remains a good material for large cavities. There have however been some reports of allergy to the material or its constituents.
  • The advantage of this material is that it has a proven record for lasting many years and is relatively easy for the dentist to use. The disadvantages are that it is grey in colour and does not stick to the tooth unlike some of the other materials.
  • Composite: Dental composite is made from acrylic and quartz and is tooth coloured. Considerable advances have been made in the composition of dental composites and in certain circumstances they can bond to the tooth, which is an advantage. They are generally more difficult to place than dental amalgam and in large cavities can cause stress within the tooth, which might cause some pain after they have been placed. This usually passes after a few days.
  • Dental composites are particularly good for filling front teeth because of their ability to match tooth colour and may also be used to change the shape of teeth. The bonding of the material to tooth may allow for the material to be used in small cavities within teeth.
  • The material is set hard [cured] by a blue light, which allows the dentist time to place it. It is very sensitive to moisture before it has cured and the dentist will need to use techniques to prevent contamination before it is set.
  • Glass ionomer: This material is tooth coloured and is made from a glass. It sticks to tooth and can be used in small shallow cavities but it has poor strength. It is very useful in children's teeth and can leach fluoride, which helps prevent further decay. It is sometimes used with dental composite to help the sealing of the tooth. Like composite it is very sensitive to moisture before it has set. Setting occurs by mixing the powder and liquid together although the material can also be mixed with composite during manufacture to allow it to be cured with a light.
  • Glass ionomer cements have also been mixed with metals to improve their strength.
  • Cements: Dental cements are used as temporary fillings [e.g. in cases of emergency] when several fillings have to be done in a short period of time and when further treatment to a tooth may be required. They are made of zinc oxide and eugenol or similar materials and may last for a few weeks to many months. Some patients are allergic to eugenol and so non-eugenol cements are used.

Composite bonding is an increasingly popular cosmetic dental treatment that is used to improve the shape, colour and overall appearance of patients' teeth. It uses the same resin material used for white fillings, and is most frequently used on the front teeth – those that show when you smile.

There have been huge advances in the materials used in bonding dentistry in recent years, meaning composite bonding can be used for disguising minor imperfections in the front teeth, closing small gaps and hiding minor tooth rotations, with no damage to your teeth.

Composite bonding is a pain-free experience that requires, in most cases, just one visit to the practice. Your dentist will be able to choose a shade of resin that closely matches the colour of your teeth, meaning that the results will look entirely natural.

This is how the treatment works:
  • Your dentist picks a shade of resin that matches the natural colour of your teeth.
  • The resin is carefully applied to your teeth, with no need for any work or damage to them.
  • Your dentist then carefully shapes and smooths the resin to hide any imperfections, for a result that looks entirely natural.
  • Once the resin has been shaped, it is hardened very quickly with the help of a special light.

Although composite bonding treatment does not last as long as veneers, many patients find the treatment is highly cost-effective. It can also be repeated with no damage at all to your teeth.

Life benefits
  • A natural, healthy smile that you are proud to show off.
  • No preparation of your teeth is required, meaning they remain strong.
  • Treatment can usually be completed in one short visit to the practice.

When cavities become too large, an ordinary filling is not strong enough to cope with the normal biting forces. The dentist will need to have stronger fillings made in a laboratory or use a CEREC machine. An inlay is used for this purpose and as the name suggests it fits inside the tooth. An onlay covers the top of the tooth and is used for worn teeth, or where the remaining tooth needs strengthening to prevent it breaking away. Sometimes a combination of both is used. They are either cemented or bonded to the natural tooth.

They can be made of gold, non precious metals, porcelain or special plastics. The choice depends on the position in the mouth in which they are to be placed, the strength of the bite, whether the patient grinds their teeth, and to some extent the wish to have a tooth coloured filling.

As there are two stages and some quite complex laboratory work they are more expensive than ordinary fillings but less than crowns. They last between ten and fifteen years, which is probably longer than ordinary fillings and about the same as crowns.

Dental Onlay

To treat a cavity your dentist will remove the decayed portion of the tooth and then "fill" the area on the tooth where the decayed material was removed.

Fillings are also used to repair cracked or broken teeth and teeth that have been worn down from misuse.

What Steps Are Involved in Filling a Tooth?

First, the dentist will use a local anesthetic to numb the area around the tooth to be filled. Next, a drill or excavation hand tool.will be used to remove the decayed area.

Next, your dentist will probe or test the area to determine if all the decay has been removed. Once the decay has been removed, the dentist will prepare the space for the filling by cleaning the cavity of bacteria and debris. If the decay is near the root, your dentist may first put in a liner made of glass ionomer, composite resin, or other material to protect the nerve. Generally, after the filling is in, your dentist will finish and polish it.

Several additional steps are required for tooth-colored fillings and are as follows. After your dentist has removed the decay and cleaned the area, the tooth-colored material is applied in layers. Next, a special light that "cures" or hardens each layer is applied. When the multilayering process is completed, the dentist will shape the composite material to the desired result, trim off any excess material, and polish the final restoration.

What Types of Filling Materials Are Available?

Today, several dental filling materials are available. Teeth can be filled with porcelain; silver amalgam (which consists of mercury mixed with silver, tin, zinc, and copper); or tooth-colored, plastic, and glass materials called composite resin fillings. The location and extent of the decay, cost of filling material and your dentist's recommendation assist in determining the type of filling best for you.

Tooth-colored Composites
Advantages of composites:
  1. Aesthetics -- the shade/color of the composite fillings can be closely matched to the color of existing teeth. Composites are particularly well suited for use in front teeth or visible parts of teeth.
  2. Bonding to tooth structure -- composite fillings actually chemically bond to tooth structure, providing further support.
  3. Versatility -- in addition to use as a filling material for decay, composite fillings can also be used to repair chipped, broken, or worn teeth.
  4. Tooth-sparing preparation -- sometimes less tooth structure needs to be removed compared with amalgam fillings when removing decay and preparing for the filling.
Disadvantages of composites:
  1. Lack of durability -- composite fillings wear out sooner than amalgam fillings (lasting at least five years compared with at least 10 to 15 for amalgams); in addition, they may not last as long as amalgam fillings under the pressure of chewing and particularly if used for large cavities.
  2. Increased chair time -- because of the process to apply the composite material, these fillings can take up to 20 minutes longer than amalgam fillings to place.
  3. Chipping -- depending on location, composite materials can chip off the tooth.
  4. Expense -- composite fillings cost more than amalgam fillings.

In addition to tooth-colored, composite resin fillings, two other tooth-colored fillings exist -- ceramics and glass ionomer.

Other Filling Types
  1. Ceramics. These fillings are made most often of porcelain, are more resistant to staining than composite resin material but are also more abrasive. This material generally lasts more than 15 years and can cost as much as gold.
  2. Glass ionomer is made of acrylic and a specific type of glass material. This material is most commonly used for fillings below the gum line and for fillings in young children (drilling is still required). Glass ionomers release fluoride, which can help protect the tooth from further decay. However, this material is weaker than composite resin and is more susceptible to wear and prone to fracture. Glass ionomer generally lasts five years or less with costs comparable to composite resin.
Silver Fillings (Amalgams)
Advantages of silver fillings:
  1. Durability -- silver fillings last at least 10 to 15 years and usually outlasts composite (tooth-colored) fillings.
  2. Strength -- can withstand chewing forces
  3. Expense -- is less expensive than composite fillings
Disadvantages of silver fillings:
  1. Poor aesthetics -- silver fillings don't match the color of natural teeth.
  2. Destruction of more tooth structure -- healthy parts of the tooth must often be removed to make a space large enough to hold the amalgam filling.
  3. Discoloration -- amalgam fillings can create a grayish hue to the surrounding tooth structure.
  4. Cracks and fractures -- although all teeth expand and contract in the presence of hot and cold liquids, which ultimately can cause the tooth to crack or fracture, amalgam material -- in comparison with other filling materials -- may experience a wider degree of expansion and contraction and lead to a higher incidence of cracks and fractures.
  5. Allergic reactions -- a small percentage of people, approximately 1%, are allergic to the mercury present in amalgam restorations.
What Are Indirect Fillings?

Indirect fillings are similar to composite or tooth-colored fillings except they are made in a dental laboratory and require two visits before being placed. Indirect fillings are considered when not enough tooth structure remains to support a filling but the tooth is not so severely damaged that it needs a crown.

During the first visit, decay or an old filling is removed. An impression is taken to record the shape of the tooth being repaired and the teeth around it. The impression is sent to a dental lab that will make the indirect filling. A temporary filling is placed to protect the tooth while the restoration is being made. During the second visit, the temporary filling is removed, and the dentist will check the fit of the indirect restoration. Provided the fit is acceptable, it will be permanently cemented into place.

There are two types of indirect fillings -- inlays and onlays.

inlays and onlays.

Inlays are similar to fillings but the entire work lies within the cusps (bumps) on the chewing surface of the tooth.

Onlays are more extensive than inlays, covering one or more cusps. Onlays are sometimes called partial crowns.

Inlays and onlays are more durable and last much longer than traditional fillings -- up to 30 years. They can be made of tooth-colored composite resin, porcelain, or gold. Inlays and onlays weaken the tooth structure, but do so to a much lower extent than traditional fillings.

Another type of inlay and onlay -- direct inlays and onlays -- follow similar processes and procedures as the indirect, but the difference is that direct inlays and onlays are made in the dental office and can be placed in one visit. The type of inlay or onlay used depends on how much sound tooth structure remains and consideration of any cosmetic concerns.

What's a Temporary Filling and Why Would I Need One?
    Temporary fillings are used under the following circumstances:
  1. For fillings that require more than one appointment -- for example, before placement of gold fillings and for certain filling procedures (called indirect fillings) that use composite materials
  2. Following a root canal
  3. To allow a tooth's nerve to "settle down" if the pulp became irritated
  4. If emergency dental treatment is needed (such as to address atoothache)

Temporary fillings are just that; they are not meant to last. They usually fall out, fracture, or wear out within a month. Be sure to contact your dentist to have a temporary filling replaced with a permanent one. If you don't, the tooth could become infected or you could have other complications.

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