What is sectional matrix in dentistry?

October 05, 2023

The most common dental problem globally is dental caries. Caries or cavity is when one or more surfaces of the teeth are attacked by certain bacteria that degrade the tooth's layers. If not approached at an early stage, the severity of caries may increase and the tooth might radiate painful stimuli. Caries is diagnosed clinically by moving a hand-held sharp instrument on the tooth's surface. If the instrument gets stuck and a catch is felt in a discolored area, a cavity is detected.

Early diagnosis of caries results in very good prognosis later on. In order to treat a carious tooth, a dentist removes the discolored infectious part with the help of a dental drill. This is followed by application of a suitable restorative material which rebuilds the lost tooth structure in an aesthetic manner. Many times, the carious lesion is spread across two surfaces. These surfaces are the chewing surface (occlusal) and one of the side walls (proximal) of the tooth that contacts the adjacent tooth. In these cases, placing a restorative material can be challenging as a clinician needs to maintain the proper contours of the tooth. It is important that the tooth's contact with the adjacent tooth is respected else it might result in improper bite or food entrapment.

In dentistry, in order to place the restoration such that the occlusal and proximal surfaces are covered with the needed adjacent contacts, materials like matrices are used. These are thin, flexible and sturdy strips of material or any other material that are placed at the contact point of two teeth. The placement of the matrix band ensures that when a restoration material would be placed, it would follow the curvature of the matrix band and hence lead to a proper contoured shape of the restoration.

There are many types of matrix bands in dentistry. These may or may not come with a holder. This holder is called a retainer. It retains the band in a way that it remains fixed between the two teeth when the restoration material is being placed. Matrix bands In this article we will talk about the sectional matrix system that is used in dentistry.

Before using a matrix band, a dentist will remove all the carious portions from the tooth. The dentist is careful and ensures that while removing the carious structure in the proximal region, no harm is done to the adjacent tooth in the process. The next step would be to place the matrix band. Unlike conventional systems that have straight matrix band strips, sectional matrix has precontoured strips. This means that the bands are already curved (kidney-shape) to the shape of the proximal wall that needs to be built. A sectional matrix band is placed with the help of a plier. The plier ensures that the matrix band is placed accurately. Next, a retainer holds the sectional matrix. The retainer used is called the G-Ring. It is a minimal circular ring that holds the retainer in its place. Moreover, the G-Ring also asserts some force on the underlying ligament which can help create some space between two teeth. In some cases, in order to achieve some tooth separation a wedge can also be placed. The wedge is a small triangular or circular shaped wooden or plastic instrument that is placed between two teeth to gain some space. The correct position of the sectional matrix is ensured when the matrix touches the adjacent tooth, is placed at a needed height and the G-Ring is in place.

After the sectional matrix system has been placed, a composite or any other suitable material is placed. The sectional matrix stays in place until the material sets completely in the oral cavity. Once the restoration is complete, the G-Ring and the wedge are removed first followed by the removal of the matrix band with a plier. The dentist will later use a thin paper and ask the patient to bite on it. The paper is dyed with a certain color that leaves some color on the tooth once the patient bites. The areas where the colour is seen are the high points that need to be removed. If there is no color marking, the restoration's height is appropriate.

Sectional matrix systems in dentistry are both dentist and patient friendly. Unlike previous matrix systems, these are less bulky, pre-shaped, conservative and are sturdy in function.

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