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An Urban Experience
B.A. Niemiec1
1Southern Califormia Veterinary Dental Specialties, Dentistry, San Diego, USA
Challenging extractions are best performed via a surgical approach. Canine and carnassial (maxillary fourth premolar and mandibular first molar) teeth are typically considered “difficult”. However, it is also beneficial
for teeth with root malformations or pathology (ie.e ankyloses) and retained roots. A surgical approach allows the practitioner to remove buccal cortical bone, promoting an easier extraction process.
A surgical extraction is initiated by creating a gingival flap. This can be a horizontal flap along the arcade (an envelope flap) or a flap with vertical releasing incisions.
Envelope flaps are created by incising the interdental gingiva and then releasing the gingival attachment with
a periosteal elevator along the arcade including one to several teeth on either side of the tooth or teeth to be extracted. The flap is created by incising the gingiva
in the interdental spaces gingiva along the arcade and then releasing the tissue to or below the level of the mucogingival junction (MGJ). The advantages to this flap are
• Decreased surgical time
• Blood supply is not interrupted
• Less suturing.
• Less chance of dehiscence
The more commonly used flap includes one or two vertical releasing incisions. This method allows for
a much larger flap to be created, which (if handled properly) will increase the defects which can be
covered. Classically, the vertical incisions are created at the line angle of the target tooth, or one tooth mesial and distal to the target tooth. Line angles are theoretic edges of teeth. However, if there is space between the teeth, either a naturally occurring diastema or from previous extraction, the incision can be made in the space rather than carrying to a healthy tooth.
The incisions should be made slightly apically
divergent. It is important that the incisions be created full thickness and in one motion. A full thickness incision is created by incising all the way to the bone, and the periosteum is thus kept with the flap. Once created,
the entire flap is gently reflected with a periosteal elevator. Care must be taken not to tear the flap, especially at the muco-gingival junction.
Following flap elevation, buccal bone can be removed. Again, this author favors a cross cut taper fissure
bur. The amount is controversial, with some dentists removing the entire buccal covering. However, this author prefers to maintain as much as possible and starts by removing 1/3 of the root length of bone on the mandible and 1/2 for maxillary teeth. This should only be performed on the buccal side. If this does not allow for extraction after a decent amount of time, more can be removed. If ankylosis is present, a significant amount of bone removal may be required.
Following bone removal, multirooted teeth should be sectioned. Then follow the steps outlined for single root extractions for each piece. After the roots are removed (and radiographic proof obtained) the alveolar bone should be smoothed before closure. Closure is initiated with a procedure called fenestrating the periosteum. The periosteum is a very thin fibrous tissue which attaches the buccal mucosa to the underlying bone. Since the periosteum is fibrotic, it is inflexible and will interfere with the ability to close the defect without tension. The buccal mucosa however, is very flexible and will stretch to cover large defects. Consequently, incising the periosteum takes advantage of this attribute. The fenestration should be performed at the base of the flap, and must be very shallow as the periosteum is very thin. This step requires careful attention, as to not cut through or cut off the entire flap. This can be performed with a scalpel blade, however a LaGrange scissor allows superior control.
After fenestration, the flap should stay in desired position without sutures. If this is not the case, then tension is still present and further release is necessary prior to closure. Once the release is accomplished, the flap is sutured.
Maxillary fourth premolar
The first step when extracting this tooth is to create a gingival flap. Classically this is a full flap with one or two vertical releasing incisors. This will allow good exposure, as well as providing sufficient tissue for closure. However, an envelope flap is sufficient for small and toy breed dogs, as well as cats.
Full flaps are created by making full thickness, slightly divergent incisions at the mesial and distal aspect of the tooth. These incisions should be carried to a point a little apical to the mucogingival junction. Be careful to avoid cutting the infraorbital bundle as it exits the foramen above the third premolar. The flap is then gently elevated with a periosteal elevator.

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