The influence of instrument taper on root canal treatment

The cleaning and shaping of the root canal system is a key step in the process of root canal treatment. Root canal preparation can effectively remove infectious materials in the root canal through the mechanical movement of the instrument, and at the same time form a conical space that maintains the initial anatomical shape and orientation of the root canal, so that the irrigation fluid can reach the area inaccessible to the instrument, and ultimately promote the root canal Seal.

The shaping of the root canal system follows different instrument techniques. In 1974, the technique of flaring (fixed cone preparation) was proposed to improve the shape of the prepared root canal system. In 2000, Buchanan proposed the concept of a variable taper file for root canal preparation. The diameter of the root canal gradually increases toward the crown. With the continuous development of endodontic technology, nickel-titanium alloy (NiTi) files were introduced and continuously improved. McSpadden proposed 2% cone files, 4% cone files and 6% cone files in 1992.

NiTi files also have both fixed and variable taper. The fixed taper nickel titanium files have a constant diameter increase angle along the file body, and the variable taper nickel titanium files have different (increased or decreased) diameter increase angles along the file body.

Studies have shown that the taper of the root canal file has an impact on the preparation of the root canal system and the final filling of the root canal.

A study comparing the sealing quality of three different taper root canal files (4%, 6% and 8%) after forming the root canal found that the greater the taper, the better the sealing effect. There is no significant difference in the sealing effect of the root canal after three-dimensional filling with root canal files with taper of 6% and 8%, but both are significantly better than the formed root canal of the 4% taper file. With the increase of the taper of the tube file, the quality of root canal filling is better. At the same time, keeping the root canal taper relatively constant and continuing the current study found that when the taper is large enough (greater than 6%), there is no obvious root canal filling after the fixed taper root canal file and the variable taper root canal file are formed. difference.

Another study using two different root canal file systems to perform root canal preparation on the amount of filler extrusion during root canal filling shows that a fixed taper can produce more gutta-perchas during filling than a root canal prepared with a variable taper. An earlier study by Allison et al. (1979) showed that there is a strong correlation between the taper of the root canal and the quality of the obturator. A root canal with a larger taper has a better obturator.

The continuous cone shape of the root canal will produce apical resistance, so that the filling material will not easily exceed the apical hole. The extrusion of the filling material will cause failure and reduce the cure rate. From the histological point of view, it is located 0.5 from the outer surface. The apical constriction at mm is the apical limit of the root canal, and both instrument work and filling should be limited to this area.

At the same time, the excess of root canal filling is related to the filling material itself and root canal filling technology. In root canal preparation, the root canal system should be prepared to at least the maximum size of 30. Large taper files will increase the risk of root fracture during the process of mechanical movement to expand the root canal system. For example, due to the small mesial root size of maxillary premolars, root fracture is a common finding.

Dentin cracks are related to endodontic treatment, and attention should always be paid to avoid excessive root canal expansion. Therefore, large taper files are generally designed with variable taper to avoid excessive dentin cutting and root fractures, while ensuring maximum Cutting efficiency. V-Taper Gold is a large taper machine file with a unique design of variable taper, which is suitable for cutting large and medium root canals in root canal preparation. At the same time, the convex triangular cross-section design further provides the clinical effect of efficient cutting!