Clinical Procedures Root Canal Treatment
The first step is to finish the root canal treatment. In the root to be treated, leave the gutta-percha below the level of future cut, and obturate the remaining canal with a definitive restorative material, as for the pulp chamber and crown access (but root resection on vital pulp can also be done as an emergency during periodontal surgery, most often in maxillary molars).
Burs with extra long cutting surfaces are recommended for root resectioning. However, care must be exercised to prevent deep cutting into a root surface without proper visualization of the root anatomy. Although flapless procedures are always better in terms of bone crest maintenance, raising a flap is recommended for visualization of the root anatomy, to help to prevent damage to the remaining roots and furca and for covering the alveolus by the flap at the end of the procedure.
A flapless procedure is typically used in root resectioning of teeth with loss of periodontal support, and flap access is used for teeth with normal periodontal support.
Resectioning must always be at the expense of the root to be removed as opposed to the structure to be retained:
- If the final cutting point is visualized, the cut can be made in only one shot with irrigation.
- If the final cutting point is not visualized, alternating cuts with a wide bur and a thinner fissure bur with irrigation and periodic stops for rechecking and removing accumulated debris is recommended. Wider burs allow the microscope light to enter deeply.
Radiographic examination, transillumination, or passing a wire through the furca, helps in directional adjustments, but the best guidance is direct vision of the anatomy provided by the microscope.
Radectomy, in maxillary molars, is when the root and the overlying segment of the crown are removed. It is used in extraction of buccal or palatal roots due to fracture, resorption, or bone loss.
Before surgery it is extremely difficult to evaluate the furca level between the buccal and palatal halves, so the presurgical crown-contouring method described by Kirchoff and Gerstein is useful.
For better visualization, removal of a small piece of bone around the final cutting point can help ("small periodontal defect creation"). However, osseous recontouring will probably be required in most cases in addition to refining the resected tooth margins to facilitate the restoration procedure.
To make sure a complete cut is made:
- Direct vision is provided by the microscope. Radiographs used to be very important, but nowadays they are less important with the use of the microscope.
- Mobility should be of the root and not the remaining tooth by elevators.
- Tactile sensitivity distinguishes a cut on root or bone.
Elevators must be used with care in order to luxate the root without damaging the bone housing or remaining roots. Never apply the instrument in the bifurcation between the roots. Root extractor forceps, primary teeth forceps, or hemostats can be used to extract the resected root. If it breaks deeply, a non-surgical approach can be taken by using magnification.
After root removal, a final view with the operating microscope is taken to make sure no undercuts, foreign bodies, or root fragments are present, and to smooth the cut surface by using a long finishing diamond or carbide tungsten bur. The composite layer should cover the coronal cut in order to prevent contamination of the exposed dentin.
If a bone graft is used it must be packed down into the alveolus, then covered by the rotated or displaced flap that is sutured to the lingual or palatal papilla. It is easily covered when the distobuccal root of a maxillary molar has been removed, then the mesiobuccal, then the mesial or distal of hemisectioned mandibular molar, and then the palatal root of maxillary molar. Bone grafting prevents bone collapse and food impactation, and facilitates oral hygiene.
If some osteotomy is necessary to equalize bone crestal heights, a round tungsten bur and bone chisels and files can be used for this.
The final restoration of a root-resected tooth will depend on the nature of the resection, the amount of remaining viable tooth structure, and the patient's occlusion and periodontal status.
In the typical case of a first or more distal mandibular molar, instead of extraction of mesial root and a bridge between distal and second premolar, a more successful option is extraction of the distal root and a single crown on the mesial root.
Many resected roots can serve as abutment or support for overdentures. Because surgical resectioning techniques invite food impaction, excellent oral hygiene is required for the success of these procedures.