Extraction of Partially-erupted mesio-angular lower third molar

November 14, 2012 | By | Reply More

Operation procedure: Removal of Partially-erupted mesio-angular lower third molar

17-year-old student, had an episode of pericoronitis related to his lower left third molar, which was treated successfully with antibiotic and with warm saline mouthwashes.The treatment plan involved extraction of this tooth, and prophylactic removal of the other third molars. He agreed to have the teeth removed, one side at a time, under local anaesthesia. The symptomatic side, the left, was treated first, but the operation on the right side is illustrated.

Radiographic assessment

The lower right third molar has a moderately large, sound crown, and the roots are straight with a large interradicular space. There is marked mesio-angular inclination, and the mesial point of application is level with the upper third of the second molar root. The second molar roots are
tapered and its crown is intact, apart from a small buccal amalgam filling. The inferior dental canal is close to the mesial root apex and the distal bone is level with the neck of the third molar. Since the tooth will be delivered upwards and backwards, pressure from the mesial root on the
canal contents is unlikely.


Operation site

The partially-erupted third molar is surrounded by a gingival cuff of variable thickness, free of inflammation. The mesial part of the crown is directly in contact with the distal surface of the second molar crown.


The first incision is made to bisect the gingival margin distally, and the second started with the blade against the distal surface of the second molar, cutting across the attached gingivae and turning forward for a short distance into the sulcus, to end level with the mesial surface of the second molar. No attempt is made to incise around the crown of the third molar since the tissues will strip off easily.


The flap is reflected with a Howarth’s periosteal elevator, starting in the mesial incision. A second Howarth’s can be used to hold the flap open while the distal tissues are reflected cleanly off the bone. It is essential that the subperiosteal plane is identified, especially over the internal
oblique ridge distally to the third molar crown, so that a guard instrument can be inserted to protect the lingual tissues during distal bone cutting. The lingual tissues must either be opened gently but widely or else left completely undisturbed. Compromise risks lingual nerve damage.

Bone removal

The tooth is in clear view and a natural mesial point of application already exists. It is therefore necessary only to relieve the impaction by removal of a gutter of bone distally so that the tooth may be uprighted.

Elevation and delivery

A Warwick-James’ elevator is inserted mesially and turned in order to upright and elevate the tooth. If necessary, it can also be elevated using buccal application at the bifurcation of the roots. Only moderate force should be used. If there is resistance, then further distal bone removal will overcome the problem.


The socket is free of debris, and the flap lies in position.


Two sutures are used. The first advances corner across the socket, and the second distal incision.


A week later the wound has closed, though the tissue margins are still oedematous. Frequent warm saline mouthwashes are advised and, if necessary, a disposable syringe may be given to the patient to be used for irrigation.

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Category: Dental, Oral Surgery

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