Composite fillings: Composition, Types And Procedure

composite fillings

Composite fillings are the tooth-coloured fillings given in the teeth that show signs and symptoms of tooth decay. They are also used for cosmetic improvements of the smile by changing the colour of the teeth or reshaping disfigured teeth.

What are composite fillings made of?

Composite fillings are composed of hard, filler particles (finely ground glass, quartz or silica), surrounded by a set matrix of another material that bind the filler particles together.

Fillers in the composite fillings are obtained from large rocks and are processed into a microscopically fine powder. There are different varieties of dental composites available based on the filler content, shape (spherical, fibres or flakes) and size of filler particles.

The filler content and the variety of filler particles present in the composite determines the properties of the material. In other words, different types of composite materials are used for the restoration of front and back teeth based on the specific requirements.

The matrix of composite fillings are generally composed of monomers of resin that lack strength and are therefore mixed with filler to provide strength to the material. These monomers polymerise into long chains of polymers on exposure to UV radiation.

Composite is available in syringes that contain a thick paste of resin monomers, fillers, catalysts and initiators. Most composites used in dental practice are light activated. On exposure to the UV light, the material sets into a hard solid. Before turning the light on, the matrix is pressed into the cavity and carved to the desired shape. 

types of dental composites

Two commonly used composite fillings for the front and back teeth:

Micro-hybrid composites

Micro-hybrid composites use up to three distinct particle sizes for more efficiency. They also include a small size range of large particles (0.6 – 0.7 microns). Their particle size is smaller than the hybrid composites and hence the name micro-hybrid composites.

They are more polishable but suffer from low particle density due to the small size of the largest particles in the mix. This enables them to achieve superior colour optics. Additionally, small filler particles fill in-between large particles and help maintain a surface polish during prolonged use. 

Micro-hybrids have unique colour-reflecting characteristics which makes them ideal for front tooth restorations. They are not recommended for molars and premolars because of their low particle density. 

 Hybrid composites 

Hybrid composites contain different particle sizes, ranging from 1-3 microns (75%) to 0.02 – 0.04 microns (8%). 

Hybrid composites do not retain a high polish for long, because large particles pop out from tooth surfaces. However, they are easy to work with and are resistant to wear. They include smaller and sub-micron sized particles which are more difficult to dislodge than large particles.

Hybrid composites can be filled more densely with glass particles than the ones containing one particle size. 

Large particles maintain the paste consistency and sub-micron-sized particles take up space between large particles. The highest particle density attained with hybrids is 90% by weight. Because of high particle density, hybrids were the first composites used for molars and premolars.

Why do you need a dental composite?

You will need a composite filling in the following situations:  

  • Cavity on the front or back tooth due to tooth decay. 
  • Fracture of the tooth due to trauma. Children with buck teeth or forward positioned upper teeth often fall and fracture their front incisor. 
  • After root canal therapy, the lost dentin is replaced with a composite filling. The tooth is then cut for crown preparation.
  • Dental composite is also used to make temporary crowns or veneers. 
  • Composite Inlays or Onlays can be fabricated in the laboratory according to the size of the cavity and bonded to the prepared tooth.

Composite filling procedure 

The process of composite filling is technique sensitive and requires good moisture control for the longevity of filling. 

  • This is the first step of filling and involves selecting the composite shade from the shade guide with your tooth colour.
  •  You may or may not require anaesthesia to numb the tooth. Deep cavities require anaesthesia to numb the tissues. 
  • The next step is the removal of decay with a motorised drill. The tooth is thoroughly rinsed with water and dried with the triple syringe. 
  • Rubber dam or cotton pellets are placed around the treated tooth to isolate the tooth from any moisture contamination. 
  • An etchant is applied to the enamel and exposed dentin for 30 seconds. The etchant is then washed and the tooth is dried. A bonding agent is then applied and cured with UV light. 
  • The final step is the placement of a composite filling. The filling is placed in thin sections and adapted to the walls of the cavity with an instrument. Every increment is cured individually due to its ability to contract on curing and producing voids and leaving tiny space between tooth and filling. 
  • The last step is checking the bite. You will be asked to bite on an articulating paper that leaves marks on the points that need trimming. In the end, you will be asked how you feel about it biting, and tell your dentist if it feels high for you. 

Composite filling Aftercare and precautions

  • The filling is fully set when you leave the office, unlike amalgam which requires 24 hours to gain its full strength. Please be careful eating until the anaesthetic wears off so you don’t bite your lips, cheeks, or tongue.
  • Children should be kept under observation until the anaesthetic wears off. Due to the unusual feeling of the anaesthetic, the children may chew the inside of their lips, cheeks, or tongue which can cause serious damage.
  • The finished restoration has a varied texture than the original tooth. Your tongue detects this small difference and it will take time to get accustomed to this change.
  • After leaving the office, if you feel that you are unable to bite properly and the filling feels high on biting, call the dentist’s office. This problem can be solved with a quick adjustment to the filling.
  • If filling is placed on the front tooth, make sure not to bite on hard foods with the filling. Yet, you can bite on soft foods. The filling in most fracture cases is supported from one side only and biting on hard foods can dislodge it. 
  • Restored or filled tooth requires the same oral hygiene measures as other teeth in the mouth. 

Conclusion 

Composite fillings are white fillings that are use to restore front or back teeth destroyed as a result of tooth decay. They are superior and most accepted by the patients due to their colour matching property and increase strength unlike the other filling materials. 

Composite placement is technique sensitive and requires adequate moisture control for the bonding and longevity of the filling. Once the filling is cured, you can start eating from the same side on the same day. 

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