This series on oral care and dental disease is provided by Eric M. Davis, DVM, a Diplomate of the American Veterinary Dental College.  Dr. Davis is the former Director of the Dental Referral Service at the Cornell University Hospital for Animals, and is currently the Director of Animal Dental Specialists of Upstate New York, a referral clinic for veterinary dentistry and oral surgery located in Fayetteville, New York. Dr. Davis can be contacted at emdavisdvm@gmail.com or at 315-445-5640.

THE FLAP OVER FLAPS

As I think back to my early years as a veterinarian, placing sutures in the oral cavity was rarely called for, perhaps with the rare exceptions of suturing lacerations or occasionally following removal of an oral tumor. In my discussions with veterinary practitioners regarding their approaches to oral disease, oral surgery is still an infrequently performed method of diagnosis or treatment. Yet in my opinion, most oral diseases can only be solved by surgical intervention and can rarely (if ever) be treated by medication alone.  For the patient with a "carnasial tooth abscess", chronic periodontal disease, feline chronic gingivostomatitis, etc, I find that many practitioners dispense antibiotics firstand then wait. Of course, the hope is that the swelling, the pain, the odor will go away.  It almost never does...it almost always comes back when the pills run out.  So when the patient is presented a second time, I will often hear in the history, that a second antibiotic, a "stronger one", was dispensed, again with the same result. Even the misguided concept of "pulse therapy", to treat chronic dental disease has been shown to provide little benefit for the patient other than temporarily decreasing oral malodor. The clinic may be selling pills, but the disease persists and the patient suffers. The only effective way to manage most dental problems is by surgical intervention.  So where does one begin?

Surgical incisions in the mouth are used to facilitate dental extractions, to enable thorough cleansing of periodontal pockets, can be used to mobilize tissue to cover defects over bone or teeth, and to remove masses in the oral cavity. As I discussed in the last article, certain surgical principals rise to prominence in oral surgery.  First and foremost, oral tissues MUST NOT be closed under tension. In addition, tissue edges should be handled gently, flaps should have wide bases so as to insure that adequate blood flow to the flap is maintained, sutures should not be placed over a void, and tissues to be closed together should have freshly incised edges, preferably beveled. As in other surgery, incisions should be made not only to enable diagnosis and treatment, but with consideration given to how the wound is to be closed.  And therein lies the flap over flaps.

Traditionally, most dental text books show placement of vertical releasing incisions at the mesial (rostral) and distal (caudal) edges of a tooth, referred to as "line angles", so as to permit the mucoperiosteum to be reflected away off the underlying alveolar bone.  This maneuver would be useful for cleaning the root surfaces of a tooth with a periodontal pocket deeper than 4-6 mm, or to permit sectioning of a tooth for extraction.  Once the extraction or root planing is completed, the vertical flap can be replaced and sutured into position using absorbable suture material. Many times, by undermining extensively, or incising the periosteum on the inside aspect of the flap, additional tissue mobility can be achieved to facilitate tension-free closure. 

The exact placement of a vertical releasing incision referable to the tooth in need of treatment requires planing and forethought.  The line angle incision should be made on the tooth adjacent to the tooth or teeth for which surgery is intended.1 The idea is to avoid damaging the interdental papilla, that small amount of attached gingiva which is present between adjacent teeth, on the gingival margin. By leaving the interdental papilla intact, soft tissue remains available for placement of sutures when the flap is replaced.

However, there are some potential problems associated with making vertical releasing incisions.  First, once you have made a vertical releasing incision, it can not be moved forward nor backward, so if you decide that an adjacent tooth needs treatment, another vertical releasing incision may be necessary.  Secondly, although oral tissues are very well vascularized, there is a risk of vascular compromise to the edges or corners of a flap as vertical releasing incisions sever the vasculature transversely. Consequently, a different flap design has been proposed, which many veterinary dentists, myself included, are finding to be useful and in fact, favored. An "envelope" flap design does not involve making vertical incisions in the attached gingiva.  Rather than making one or two vertical releasing incisions, an envelope flap consists of a single, horizontal incision made linearly in the gingival sulcus and in the interdental papilla on the gingival margin, one or two teeth rostral, and one to two teeth caudal to, the tooth requiring treatment. Once the gingiva is elevated and undermined off the bone, excellent visualization and avoidance of soft tissue damage can be easily accomplished.  The envelope flap is usually started on the buccal side of the dentition, but the flap can be easily developed on the lingual aspect of the dentition as well.  The chief advantages of the envelope flap are the avoidance of severing vasculature and the ability to start with a small flap and extend it if necessary to provide additional exposure.  Also, fewer sutures are necessary to close an envelope flap compared to closing a flap with a vertical releasing incision, because sutures can be placed interdentally with the former.  It is true that by incising the gingival sulcus of healthy teeth in order to gain exposure to an operative site, the periodontal health of the teeth involved in the flap is compromised.  However, provided the tissues are handled gently and sutured carefully, little permanent damage occurs.

1 Ramsey DT, Marretta SM, Hamor RE, et al.  Ophthalmic manifestations and complications of dental disease in dogs and cats. J Am Anim Hosp Assn 1996: 32 (3), 215-234.

2 Smith MM, Smith EM, LaCroix N, Mould J. Orbital penetration associated with tooth extraction.  J Vet Dent  2003; 20 (1), 8-17.

3 Holmstrom SE, Fitch PF, Eisner ER.  Exodontics.  In: Veterinary Dental Techniques for the Small Animal Practitioner, 3^rd ed. Philadelphia: WB Saunders, 2004; 291-338.