Surgical technique

Surgical exposure techniques may vary depending on the location of the impacted canine, whether it is on the palatal side or the buccal side.

Two authors, Dr Vincent G. Kokich from the University of Washington in Seattle and Dr Robert L. Vanarsdall from the University of Pennsylvania in Philadelphia have greatly published on surgical exposure techniques of impacted canines. They are two world famous leaders on the matter.

Dr Kokich recommends open and preorthodontic exposure of palatally impacted canines. This facilitates eruption and orthodontic traction.

Dr Vanarsdall recommends open exposure with a repositioned gingival flap (pediculated connective tissue graft) above the impacted canine. This allows a better gingival architecture around the canine once the orthodontic treatment is finished.

Surgical techniques are thus divided into 2 main categories:

• Open exposure and eruption (open eruption technique)

• Closed exposure and eruption

Historically, in the Quebec City area, the closed exposure and eruption approach has been more often used. Orthodontists from Quebec City are lucky to be able to rely on an excellent group of specialists in oral and maxillofacial surgery and they have great ability in manipulating soft tissues and they bond the cleat to the tooth and put in place the metal ligature wire.

Open exposure and eruption

Palatally impacted canine

• The palatal flap must have the right size.

• Meticulous ostectomy of the bone covering the canine crown must be performed.

• The soft tissues (follicular envelope surrounding the permanent tooth crown) must be removed down to the cementoenamel junction.

• Reposition the flap in its former place and make an opening in the flap to expose the crown and the bonded cleat.

• Put a periodontal pack (dressing). This allows healing without having the tissue cover the tooth again during healing.

• Wait 6 to 9 months before initiating orthodontic therapy.

Kokich VG. Surgical and orthodontic management of impacted maxillary canines. Am J Orthod Dentofacial Orthop 2004;126:278-283.

Kokich VG. Preorthodontic Uncovering and Autonomous Eruption of Palatally Impacted Maxillary Canines, Semin Orthod 2010; 16: 205-211

A colleague from Ontario provided me with a few examples of canine exposure. Notice the eruption of canines within 7 months. However, due to the severe lack of space (no space available between the lateral incisor and the premolar), the following is a legitimate question to ask: Wouldn’t it have been preferable to extract both first premolars and thus offer the canines space that would have allowed eruption in the arch rather than in the middle of the palate?

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Surgical technique to expose palatally impacted canine

The current series of pictures show the exposure technique as it is generally performed by oral surgeons from Quebec City.

• The full-thickness palatal flap (including the periosteum) is wide, spreading from the papilla anteriorly to the second premolar posteriorly. The vasculo-nervous bundle of the nasopalatine duct (under the nasopalatine papilla) is preserved.

• An ostectomy allows the exposure of the crown of the canines.

• The follicular envelope is removed down to the cementoenamel junction. No remnants of the follicular envelope must be left in place, because it could prevent bone healing and reattachment of the ligament to the tooth.

• Cleats are bonded to the exposed and most accessible surface of the tooth. On the right, the cleat was bonded to the lingual surface. On the left, the cleat was bonded to the buccal surface. To distinguish right from left, you have to know that you look at the patient in front of you, which means that his right is on your left.

• The palatal flap is closed and sutured in place with absorbable thread (sutures).

• An opening is made in the flap to allow the metal ligature wire to pass (twisted 0.01 orthodontic ligature wire). The opening in the flap on the left side of the image is not wide enough. During healing, the remaining palatal tissue will cover the canine too much and will slow down its eruption (see following page entitled Mechanotherapy).

• The ligature wire is bonded to the cleat.

• The ligature wire surrounds the orthodontic arch until the orthodontic traction is activated.

• At this stage, a periodontal pack could or should be placed to prevent the covering of the transmucosal openings during healing (healing by second intention).

• Orthodontic traction is initiated 7 to 10 days after the surgery.

Note that since the anchor point is different on canines, we have to expect that the right canine will rotate and that its lingual surface will be visible first due to the fact that the cleat is bonded to the lingual surface. For the left canine, the buccal surface should erupt first since the cleat is bonded to the buccal surface.

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Surgical exposure technique on an impacted canine in vestibular position

When the canine is located on the vestibular side (black circle), it is recommended to use an apically repositioned flap to bring an adequate band of keratinized gingiva to the neck of the tooth.

Keratinized gingiva is pinkish and attached more firmly to the subjacent bone than the alveolar mucosa. The black arrows indicate the line of the mucogingival junction between the mucosa and the gingiva. The keratinized gingiva under this line must be above the erupting tooth. Usually, the tooth breaks through the gingiva at the crest of the ridge and keratinized gingiva will cover the neck of the tooth.

The surgical exposure of the case of the canine on the opposite side is illustrated in the series of pictures below.

• The initial incision is made at the crest of the ridge. Two loosening vertical counter-incisions go back up to the oral vestibule. The gingival flap is dissected from the periosteum which stays in place. We say that it is a half-thickness flap because it does not contain the periosteum. The periosteum is that nutritious membrane covering the bone and composed of bone-forming cells.

• An ostectomy (removal of layer of bone) allows exposure of the canine crown.

• A cleat is bonded to the surface of the tooth and a metal ligature wire is fixed around the head of the cleat.

• The keratinized gingiva which was located at the crest of the ridge (black rectangle on the left) is apically moved (green arrow) to the top of the bone opening (black rectangle on the right).

• The flap is sutured in place.

• The exposed periosteum changes into granulation tissue and allows healing by second intention. Healing by second intention means that the wound closes by proliferation of healing tissues around the wound. Healing by first intention occurs when the wound edges can touch and reseal. A skin incision that necessitates stitches to reseal the wound is an example of healing by first intention.

Vanarsdall RL. Efficient Management of Unerupted Teeth: A Time-tested treatment modality, Semin Orthod 2010;16:212-221

Vanarsdall RL, Soft-tissue management of labially positioned unerupted teeth, AJODO 2004; 125:284-293

Healing takes place quickly and with very little pain. The young patient told us that she had had more problems with her pain medications which contained codeine than with the exposed wound. One of codeine known side effects is constipation…

After 12 days, the site is closed. Granulation tissue covers the centre of the wound. Keratinized gingiva covers the crown. Traction on the metal ligature wire is initiated. An elastomeric chain ensures a vertical traction force posterior to the impacted canine.

Healing after 44 days shows keratinized gingiva reappearing in the former site (green arrow) and the apically repositioned band of gingiva (blue arrow) healed well. The elastomeric chain was replaced by a new one and the metal ligature wire was shortened and bent.

When the flap is replaced to its former position, traction is done blindly and the metal ligature wire or the cleat can come out through the mucosa or through the gingiva gradually as healing and traction occur as shown in the figure on the opposite side. This perforation of the gingiva determines the quantity of keratinized gingiva that will cover the neck of the tooth.

The image on the opposite side shows well the difference between the bands of keratinized gingiva comprised between the blue and black arrows when the canine erupts normally on the left, compared to when the ligature cleat perforates the mucosa right below the mucogingival junction. The right canine shows only a little gingival festoon and little or no keratinized gingiva at the neck of the tooth. A free autogenous graft will likely be necessary in the medium term. The length of the left canine is different from the right one because keratinized gingiva covering it has not finished its migration upward. The patient is only 14 years old. The right canine, however, should not get any longer because the gingival attachment is located at the cementoenamel junction.

An open surgical approach with pediculated connective tissue graft (apically repositioned flap) as recommended by Vanarsdall (Sem.Orth. 2010) would have resulted in a better band of keratinized gingiva at the neck of the left canine.