Oral Surgery – General

Oral Surgery – General

Heidi B. Lobprise

Main Street Veterinary Dental Clinic, Flower Mound, TX, USA

12.1 Introduction

Tissues other than teeth, bone, and periodontal structures require surgical intervention at times. Basic surgical skills and rules for other body systems are often applicable, with some modifications. A good aseptic technique in the clean‐contaminated environment of the oral cavity can be challenging, but should be followed when possible. Specific aspects from tissue healing to instrumentation and techniques are covered in greater detail in other texts that are good resources (see Suggested Reading).

12.1.1 Basic Surgical Principles

Tissues of the oral cavity tend to heal rapidly due to several factors, including more extensive monocytic phagocytic activity and epithelialization (compared to skin), warmer temperatures, high metabolic activity, higher mitotic rate, and an excellent blood supply [1]. The oral cavity’s excellent blood supply can prove to be both a benefit and a hindrance to surgery: while hemostasis must be provided for proper visualization, preservation of major vessels is essential. The most significant vessels and nerves typically encountered are the maxillary and palatine structures of the maxilla, and the inferior alveolar neurovascular bundle of the mandible. Where possible, vascular structures should be preserved, even incorporated into retained tissue. If resection is necessary, then vessel identification, ligation, and hemorrhage control is vital.

Smaller scalpel blades are often an advantage in the restrictive spaces of the oral cavity. Tissue handling instruments (forceps, scissors) should be selected to provide delicate handling of the gingiva and mucosa, particularly when they are friable. Smaller, curved Metzenbaum scissors with serrated blades and delicate Adson 1X2 rat‐tooth thumb forceps can be useful [2]. Right‐angled forceps can be helpful to isolate vascular bundles for ligation and non‐crushing forceps can secure tissues such as the tongue for temporary hemorrhage control during the procedure [1].

Preference for suture material may vary, but typically an absorbable product of 4‐0 to –5‐0 size with a swaged‐on needle works best. The type and size of suture can be adjusted according to the size of the patient, condition, and thickness of the tissue and goal of the procedure. For extractions, synthetic absorbable material is recommended, and products that will stay intact longer (polyglacton 910 or polyglycolic acid) are preferred with oronasal fistula repair and other complicated procedures. In thin, friable tissue, a tapered needle may be preferred while a reverse cutting needle may be needed for thicker mucosa and gingiva.

A suture technique may also be adjusted according to need, often using a simple interrupted pattern and specialized patterns where indicated. Sutures should incorporate adequate bites of tissue and be secured snugly to resist loosening due to movement of the tongue and lips. A good rule of thumb to follow is the “3 × 3 × 3” rule, where the sutures are 3 mm apart, 3 mm from the incisional border, and the ends of the sutures are cut 3 mm long. For oral surgery, five to six throws should complete the knot due to the moist environment and tongue movement. Interdental sutures should allow for good approximation of tissues, and will keep the gingiva securely against the tooth. Position knots away from the incision line to prevent an accumulation of debris in the area. It is best not to have an incision line over a defect, but, most importantly, a suture line should never be placed under tension. Any suture line with tension should be expected to fail. It is also vital to provide a fresh edge or surface for adequate healing. Any chronic area or intact epithelial surface should be debrided to provide a fresh bleeding surface to promote rapid healing.

Hard tissues also require proper handling, as it is possible to injure or burn the bone surface with inappropriate use of burs on high‐speed handpieces, lasers, or electro/radiosurgical units. All sharp and/or rough bony crests with spicules should be smoothed as in an alveoloplasty to avoid any further soft tissue damage, but excessive amounts of supportive bone should not be removed. Generally, no area of denuded bone should be left uncovered by soft tissue.

Pain management is an essential consideration with any form of surgery (see Chapter 9 – Anesthesia and Pain Management). Post‐operative patient support with nutritive care and analgesia is critical in some cases.

12.1.2 Hemostasis During Oral Surgery

Digital pressure with a moist sponge for a short period of time will often be all that is needed for minor oral surgery. When more extensive oral surgery is anticipated, other means may be used to prevent blood loss, improve visualization, and decrease surgical time. Products to aid hemostasis include bone wax, oxidized regenerated cellulose, gelatin matrix (sponge or powder), microporous polysaccharide spheres (potato starch), microfibrillar (bovine) collagen and topical thrombins in gelatin matrix [2].

Electrosurgery or radiosurgery can provide either a cutting or hemostatic action, depending on the type of current used [3]. Fully rectified current provides easy cutting of most oral soft tissue, providing a good degree of hemostasis (50% cutting, 50% coagulation). It is useful for gingivectomy, gingivoplasty, palatal soft tissue surgery, frenectomy, and small soft tissue mass removal. A fully filtered current is the least traumatic of the four types and is used for delicate cutting, but little hemostasis is afforded (90% cutting, 10% coagulation). Any surgery close to cementum or bone benefits from this type of current, as well as biopsy specimens, gingival grafting, or even widening of the gingival sulcus for crowns. Partially rectified currents coagulate soft tissues for hemostasis where bleeding is a problem (90% coagulation, 10% cutting). The spark gap technique used at high power settings to produce the fulgurating current is the most destructive of the four and should be used cautiously. A variety of tip shapes and techniques (cutting action, point application) provide options for the practitioner.

12.1.3 Surgical Suction

Suction is an important part of maintaining good visualization and hemostasis during oral surgery. With the often times excellent blood supply, visualization to identify the source of bleeding can be difficult. Suction provides a dynamic means of visualizing bleeders and it is also very beneficial when searching for fractured roots. Bone generally bleeds when cut but a retained root does not, allowing for the surgeon to distinguish between bone and tooth root. “Look for the white pearl in the red sea.”

12.1.4 Laser Surgery

Laser techniques in the oral cavity have been recommended with a variety of surgical applications including correction of elongated soft palates [4], tonsillectomy, and gingivectomy or gingivoplasty. Proliferative tissue can be removed in an alternating ablate and wipe technique, often as one part of multimodal therapy, and repeated as necessary. CO2 lasers interact with water molecules in soft tissue, resulting in shallow thermal necrosis zones, while diode lasers penetrate deeper. Lower level laser therapy can be used as adjunctive therapy for analgesia and wound healing [3].

12.2 Palatal Defects

12.2.1 Repair Techniques for the Palate

When palatal defects disrupt the separation of the oral and nasal cavities, proper surgical techniques are essential for reconstruction. Surgical sites can be under constant stress due to the relative inelasticity of palatal mucosa and constant movement from both respiratory efforts and constant movement of the tongue. Two goals in flap design include tension‐free flaps and the incorporation of an adequate blood supply. All tissue edges and any intact epithelial surface in the surgical field should be freshly debrided. Any flap design should be at least 1.5–2 times the size or width of the defect to be covered to allow for contracture of tissue, and sutures should not lie directly over the defect.

12.2.2 Congenital Defects

Primary and secondary palatal cleft (with accompanying lesions) are some of the more common defects seen in newborn puppies. Some advocate surgical repair by six to eight weeks of age, with any delay contraindicated as the defect is likely to get larger [5]. Other guidelines recommend supporting the patient with alternate feeding (orogastric tubes) until they reach 8–12 weeks of age [6]. Surgery can interfere with the growth of the palatal and maxillary tissues if performed any time prior to 16 weeks of age [7]. Custom‐made nursing teats have proven successful in research‐based puppies, with removable, flexible prosthetic plugs placed at the time of weaning [8]. In one case, the patient was maintained on dry kibble and a suspended water bottle and surgery was performed finally at 14 months of age, at which time the defect had partially closed spontaneously [6]. Additional craniomaxillofacial abnormalities are often seen in these patients, and the extent of the osseous lesion is often greater than the soft tissue defect and is hidden [9].

A number of defects can also be seen in the soft palate, with or without hard palate involvement [10]. These could include an extension of a secondary cleft to an asymmetric unilateral defect, or bilateral soft palate hypoplasia [11]. With unilateral hypoplasia, two‐ or three‐layer appositional repair with ipsilateral tonsillectomy may be adequate if there is minimal tension at closure. In bilateral hypoplasia, where the small caudal portion on the midline looks like a uvula, repair of one side can be followed with repair of the other side four to six weeks later. However, if there is considerable tension, then a nasopharyngeal mucosal flap may be needed [11]. Sager describes using two buccal mucosal flaps, each based on a palatoglossal arch (harvested rostrally – finger shaped), with the first positioned and sutured so its mucosa faces the nasal cavity and the second rotated for its mucosa to face the oral cavity [12]. In a feline case, one flap from the hard palatal mucosa and two lateral pharyngeal flaps were required [13]. A similar case in a dog with bilateral hypoplasia and no pseudouvula utilized an initial split thickness hinged soft palate flap. When released, the flap expanded the length of the palate caudally. Bilateral U‐shaped rotational flaps from the adjacent buccal mucosa were placed over the opened palatal flap, with less tension than a pharyngeal flap would have caused [14]. If full function cannot be returned, treatment for palatal hypoplasia may be reconsidered [15].

Nasopharyngeal stenosis due to dysplasia of the palatopharyngeal muscles in the Dachshund is not amenable to surgery in most cases [16, 17]. In one case of nasopharyngeal stenosis due to soft palate dysplasia, the caudal portion adhered dorsally to the pharyngeal mucosa, and anti‐inflammatory medication decreased the edema sufficiently to relieve the dyspnea [18]. In a separate feline case, a mucosal flap for correction and release of the laryngeal webbing avoided the complication of recurrence that has been seen in other cases [19].

By far the most common soft palate defect is an extension of a secondary cleft into the hard palate. If the defect is small to moderate in size, and the two edges can be gently apposed without extensive tension, then a simple two‐ or three‐layer closure may be sufficient [10, 20]. Once the edges are excised, the nasal mucosa should be sutured from a caudal to rostral direction in a simple interrupted pattern with the knots facing the nasal cavity. While some elect not to close the muscle layer to minimize suture material, a continuous pattern can provide additional closure. The final oral mucosa layer is then closed, with knots facing the oral cavity. Tension‐releasing incisions may be made laterally and the tissues can be separated from the pterygoid hamulus.

The more complicated bilateral overlapping mucosal single‐pedicle flaps may be performed if simple closure would result in excessive tension [21]. On one side of the defect, a mucosal flap is harvested with an initial incision 5 mm away from the defect edge, for the length of the defect (Figure 12.1a). Two incisions are made to the midline at the caudal and rostral edges of the initial incision. The oral mucosa is undermined to harvest a flap that will be “flipped” on the hinge formed by the edge of the defect on that side. This flap is positioned dorsal to the soft palate on the other side of the defect, with the mucosa facing the nasal cavity (Figure 12.1b). The mucosal flap on the other side is harvested in a similar manner from the nasal aspect of the tissue, and when undermined and opened and flipped, will be placed on the ventral aspect of the two flaps, with the mucosa facing the oral cavity (Figure 12.1c). The initial flap can be sutured to the lateral‐most aspect of the second flap harvest site to secure the mucosa facing the nasal cavity. The second flap is also sutured to secure its edge facing the oral cavity (Figure 12.1d). This technique was successful in a number of cases with suture lines placed away from the defect and tissue closure over the harvest sites [21].

Image described by surrounding text.

Figure 12.1 Secondary cleft extending into soft palate closed with two layers – bilateral overlapping mucosal single‐pedicle flaps which are cut and rotated 180° and closed.

Source: Courtesy of Josephine Banyard. Adapted from reference [15].

Elongated soft palates are a common finding in brachycephalic breeds, along with a combination of lesions including stenotic nares, everted tonsils, and laryngeal ventricles, known as Brachycephalic Airway Obstruction Syndrome (BAOS) [2225]. Correction of an elongated soft palate may be accomplished with cold steel (scissors), electrocautery, low‐temperature, high‐frequency radiotherapy [26], carbon dioxide laser, a bipolar sealing device, or harmonic scalpel. In one study, a CO2 laser and electrocautery had favorable outcomes, with the laser having a shorter surgical time and less bleeding, while diode laser therapy had more complications [27]. The bipolar sealing device provides firm compression and electrothermal energy that is feedback controlled, without the safety precautions necessary for laser devices [28]. The ultrasonic motion of the blades of the harmonic scalpel are purported to cause less post‐operative pain and swelling, and a decrease in bleeding [29].

No matter what method is used, the basic approach is similar: using lateral stay sutures caudal to the level of the tonsils, retracting the tissue carefully, and resecting enough so the new edge will be positioned just caudal to the epiglottis. With scissors, a cut is made a third of the way across at a time, closing the nasopharyngeal and oropharyngeal mucosal layers for each section, but not incorporating the muscle layer [14]. Crushing the tissues may cause excessive edema and improper use of electrocautery can be damaging.

12.2.3 Midline Defect Repair – Acquired Narrow Defect, Acute – Primary Appositional Closure

With minor midline defects (<1 mm), whether due to congenital cleft or trauma (high‐rise syndrome in cats) [30], primary closure of the narrow space is often simple [10]. After debriding the soft tissue to freshen the edges, and using digital pressure to realign any displaced osseous structures, the mucosal edges can often be closely reduced and repositioned for simple interrupted suture closure. Narrow to Medium Defect – von Langenbeck Technique

This technique has also been called the medially repositioned double flap or sliding bipedical flap technique [31, 32]. In some moderate midline lesions, a releasing flap at the lateral aspect by each dental arch can provide enough flexibility to bring the two medial edges together at the midline. The lateral releasing incisions often must be fairly long, should incorporate the palatine arteries, with the medial edges freshened before suturing. Full thickness releasing incisions may allow the most flexibility, but partial thickness flaps have been shown to minimize the scar tissue that could potentially affect maxillary growth in the young patient [33]. This is best used if there is minimal tension, though the sutures are placed over a defect (Figure 12.2a to c).

Illustrations of the palatal surface of the maxillary teeth in dogs depicting narrow vertical cuts in the middle (a), broad cuts with 2 narrow cuts at both sides (b), and suture lines (middle) with hatch lines at both sides (c).

Figure 12.2 Medially repositioned double flap or sliding bipedicle flap technique (von Langenbeck Technique).

Source: Courtesy of Josephine Banyard. Adapted from reference [31]. Wide Defect (Linear) – Overlapping Flap ± Releasing Incision

After making an incision palatal to the maxillary teeth on one side, releasing incisions are made at the rostral and caudal extents, toward the cleft defect, perpendicular to the first incision and incorporating the palatal artery into the flap [10]. The defect margin on the opposite side is incised to elevate the mucoperiosteum off the underlying palatal bone, preserving the artery on that side as well. Once the original flap is raised, it is flipped on the hinge of tissue at the edge of the defect and is secured with vest‐over‐pants sutures under the mucoperiosteum on the other side (Figure 12.3a to c). This is best used with wider defects, as the suture line has underlying bone for support. This can be paired with a two‐ or three‐layer closure of the soft palate if the defect extends distally.

Illustrations of the palatal surface of the maxillary teeth depicting a vertical cut (a), flap tissue at the right side of the cut (b), and overlapping of the flap tissue to the vertical cut with suture lines (c).

Figure 12.3 Overlapping flap – “vest over pants” technique to close a midline palatal defect.

Source: Courtesy of Josephine Banyard. Wide Defect – Midline Caudal Hard Palate – Advancement Flap

Once the site around the defect is prepared (edges freshened), incisions are made caudally at each side of the defect [20]. The advancement flap is elevated, starting with full thickness over the hard palate and transitioning to partial thickness over the soft palate. Once sufficient tissue is released to provide closure without tension, the flap is advanced rostrally and sutured to the prepared margins. This allows the suture line to be supported by underlying bone.

12.2.4 Asymmetrical Defect Repair – Acquired

The size and position of the defect, as well as the available vascularized tissue for repair, will help determine the type of surgical technique for a variety of palatal defects. Small, Circular Defects – Transposition (Rotation) Flap

Smaller defects rostral to the level of the maxillary fourth premolars can be covered with a U‐shaped flap, incorporating the palatal artery, from the opposite side. Design the rostral edge of the flap to align with the rostral extent of the defect. Once released, the flap is positioned into the prepared area of the defect. Incisions extended back into the soft palate should be adjusted from a full thickness flap to partial thickness in this region to provide a mobile caudal base for rotation. The flap is secured by sutures over the prepared defect site, with some sutures preplaced in small holes drilled into the palatal bone on the donor side. The harvest site is allowed to heal by second intention. This flap allows large coverage with sutures supported by underlying bone. Central Defect at Level of Maxillary Fourth Premolars – Split Palatal U‐Flap

Here a large full‐thickness U‐shaped flap is created rostral to the defect, extending to the level of the first premolars [34]. The flap is divided at the midline and the rostral extent of the palatine artery is ligated, with preservation of the rest of the artery for vascularization of the flap. The first half of the flap is rotated 90° so the medial border is sutured to the caudal aspect of the defect. The second flap is then rotated to suture the now rostral extent of the first flap (Figure 12.4a and b). This is best used when there is minimal tension or wound contraction in the harvested tissue.

Illustrations of the palatal surface of the maxillary teeth depicting a dashed U-shaped with 2 equal parts divided by a vertical dashed line (a) and solid U-shape with suture lines on top forming an inverted S-shaped (b).

Figure 12.4 Split palatal U flap to correct a central caudal palatal defect.

Source: Courtesy of Josephine Banyard. Large Caudal Defects – Island Axial Pattern Flap

In areas where there is less viable tissue on one side to harvest for a flap, a variation of the split palatal U‐flap can utilize healthier tissue on the other side, incorporating the palatal artery [35]. The caudal extent of the flap will extend to the level of the second maxillary molar, with full thickness release of the mucoperiosteum from the underlying palatal bone. This preserves the major palatine neurovascular bundle as the pedicle of the flap. This flap can be rotated up to 180° to be positioned at the prepared defect site. Large Rostral Defects

For extensive palatal defects with limited tissue from which to harvest a flap, the dorsum of the tongue can be incorporated to cover the defect. The tongue surface is incised and undermined to use the cut surfaces as flaps, sutured to the palatal defect edges once rotated 180°. After four weeks of assisted feeding, the tongue is separated from the palate, with enough tissue left to close the defect permanently. This procedure is not tolerated well and should be used if other techniques have proven unsuccessful. Large Defects – Complicated – Previous Surgical Attempts Unilateral or Bilateral Vestibular Mucosal (Overlapping) Flap(s)

If there is a lack of healthy, tension‐free tissue for flap development, premolars and molars are first extracted unilaterally or bilaterally [10, 36]. This can provide a wide section of tissue that can be released up into the vestibular buccal mucosa once the extraction sites have healed sufficiently. With a lateral defect, just one arch may be needed for harvesting a flap, but with an extensive defect, both sides can be developed to create a bilateral overlapping flap [10]. Angularis Oris Axial Pattern Buccal Flap (APBF)

An axial flap can be harvested from the caudal buccal mucosa on the affected side, incorporating the angularis oris branch of the facial neurovascular branch [37, 38]. After skin preparation, the vessel is located by palpating the buccal mucosa of the cheek, finding the pulse of the artery, or by transillumination. A skin incision is made, extending caudally from the commissure of the lips, reflecting the skin ventrally and dorsally. A full thickness (except for the skin) rectangular flap is harvested, ligating the vessels at the rostral aspect, and continuing the flap caudally to the extent at which the artery travels deep to the masseter muscle. This base is maintained for rotation of the flap to allow its positioning over the defect, with the buccal mucosa facing the oral cavity and secured with sutures. Depending on the patient’s size, this flap could reach rostrally to the extent of the maxillary canines. The submucosa and mucosa are closed with two layers, and the skin is closed externally. Reports of complications of distal tip necrosis could be attributed to trauma from the upper molars if they are not extracted [38]. Early intervention with repositioning of the flap if the rostral extent fails has been shown to result in eventual flap success. Superficial Cervical Axial Pattern Skin Flap Variation

While previously used for extensive head and neck reconstruction procedures, the axial skin flap harvested with the superficial cervical artery (prescapular branch – SCA) has been proposed as a possible palatal defect flap [39]. However, since this procedure requires the use of a pneumatic dermatome and would need an extended (bilateral) flap to reach the oral cavity, it is unlikely to be used widely. Myoperitoneal Free Flap [40, 41]

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Aug 15, 2020 | Posted by in GENERAL | Comments Off on Oral Surgery – General
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