Focus Meeting on Dentistry Charlotte, NC, USA Aug. 4-6, 2013

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1 Proceedings of the American Association of Equine Practitioners Focus Meeting on Dentistry Charlotte, NC, USA Aug. 4-6, 2013 Next Meeting: Annual Convention Dec. 7-11, Nashville, TN, USA Resort Symposium Feb. 6-8, Rio Grande, Puerto Rico, USA Reprinted in the IVIS website with the permission of the AAEP

2 Review of Surgical Extraction of Mandibular Cheek Teeth Jennifer Rawlinson, DVM, Diplomate AVDC Take Home Message Successful surgical extraction of all mandibular cheek teeth is possible, and a variety of surgical approaches are available. Choosing an appropriate approach depends heavily on the experience of the surgeon, the condition of the tooth, and the clinical presentation of the horse. Author s address C3 512 Clinical Programs Center, Department of Clinical Sciences, Cornell University College of Veterinary Medicine, Ithaca, NY Phone: (607) ; jee2@cornell.edu. P I. INTRODUCTION athology associated with equine cheek teeth has been well documented by many research veterinarians and scientists from around the world. 1 Dental fractures leading to significant crown loss and pulp exposure, apical infection, periodontal disease, dental malformation, supernumerary teeth, and maloccluded teeth are all potential pathologies that would necessitate extraction of a cheek tooth. Patient age and health, severity of disease, tooth positioning, severity of clinical signs, and owner s financial and physical capabilities all play a role in determining if extraction is the best therapeutic option. Extraction of equine cheek teeth, especially of those that are not already mobile, is a demanding undertaking for both horse and veterinarian, and it should be undertaken with serious thought, preparation, and conviction. Before attempting any extraction proper sedation, anesthesia, analgesia, visualization, equipment, and assistant help should be ready for use. The surgeon undertaking the extraction should also be prepared to handle any complication that arises as a result of the procedure however minor or major. In all published studies to date, intraoral extraction of teeth has provided the highest success rate and the lowest complication rate of any extraction technique; therefore, intraoral extraction of cheek teeth in the horse should always be considered prior to surgical extraction options. 2 When intraoral extraction is either impossible or suboptimal, surgical extraction techniques can be utilized. The fact that there are so many different approaches to the extraction of equine cheek teeth highlights that no one technique is appropriate for every case. The more techniques a surgeon masters, the more positive the outcome for the horse. The ideal surgical procedure is always the one that poses the least amount of risk for major complication and disturbs the least amount of soft and hard tissue while providing adequate visualization and access to perform the extraction. Indications for these procedures are loss or severe damage to clinical crown, crown-root fractures, apical infection of young teeth, impacted teeth, open-mouth restriction, very small patient size, radicular/odontogenic cyst formation, and dental malformation. The following extraction techniques have been previously described in the literature, and a summary of each technique is presented. II. MATERIALS AND METHODS **An in-depth knowledge of equine maxillofacial and dental anatomy is paramount to perform these surgical procedures successfully.** All surgical descriptions are quoted directly from the articles indicated. Immediate Pre-surgical Preparation: A complete oral exam was performed and intraoral dental treatments were performed as necessary. Preoperative radiographs were acquired to ensure the appropriate tooth for extraction and to evaluate regional and dental anatomy/pathology. Procedures were performed by either general anesthesia or standing with a CRI depending on the procedure and the disposition of the horse. The head was supported either by table or suspended with dental halter or like equipment. Sites were clipped and aseptically prepped. The site was draped, partially draped, or undraped depending on the technique. Procedure A: Lateral Buccotomy Technique as described by O Neil 3 All performed under general anesthesia. a. The clinical crown and gingival margin of the tooth to be extracted. b. The junction of the buccal mucosa and the alveolar mucosa (vestibule or buccal reflection) adjacent to the tooth extracted. Incision 75

3 a. The skin incision was centered directly over the tooth to be extracted. b. Dorso-ventrally the incision was centered between the gingival margin and the buccal reflection (vestibule). c. A 5-10 cm long skin incision directed ventrally approximately 30 degrees in a caudo-dorsal to rostro-ventral direction. d. If parotid salivary duct in surgical field, it was either retracted or transected and subsequently repaired. Access to Tooth a. Buccal part of buccinator muscle was incised. b. Care was given to identify and avoid facial nerve. c. Sharp and blunt dissection was performed through underlying connective tissue and glandular layer. d. Buccal venous plexus was encountered deep to glandular tissue in caudal mandible resulting in significant bleeding. Electrocautery and ligation used for hemostasis. e. Buccal mucosa was sharply incised, and the incision extended rostro-caudally to expose the full width of the clinical crown. Identity of tooth confirmed. f. A dorso-ventral gingival incision made rostral and caudal to the affected tooth from the free gingival margin to the buccal reflection (vestibule). g. Gingiva and mucosa elevated off tooth and lateral alveolar bone plate using periosteal elevator. h. Bone plate partially removed by chiseling. a. With part of reserve crown exposed, the periodontal ligament was broken down with use of small gouge around tooth edges in attempt to remove tooth en bloc. b. Most teeth required splitting either longitudinally or latero-medially using a chisel and mallet and the tooth was removed piecemeal. Procedure B: Transcortical Osteotomy and Buccotomy as described by Tremaine 4 All teeth were impacted or partially erupted, and all procedures were performed under general anesthesia. a. Using fluoroscopic guidance, the osteotomy site was marked with skin staples. Incision a. A curvilinear skin incision was made with its base orientated coronally, so that skin reflection exposed tissues overlying the unerupted tooth. The buccinator muscle was bluntly sectioned, and the ventral branch of the facial nerve was identified and atraumatically reflected. b. The periosteum was identified, incised, and reflected. Access to Tooth a. Positioning confirmed by fluoroscopy and an osteotomy was made through mandibular cortex using a sharp osteotome or an airpowered bur parallel with the rostral margin of the apical component of the tooth. b. A second parallel osteotomy was made 2 cm more caudal (level with the caudal extremity of the tooth) and was extended to the level of the gingival attachment to the bone at the gingival sulcus. c. The buccal mucosa was sharply incised at its mucoperiosteal attachment. d. The section of lateral mandibular cortex and dental alveolus was elevated in a coronal to apical direction to expose the unerupted tooth, until the remaining apical side of the cortical flap fractured and the bone was discarded. e. If needed, the osteotomy was enlarged with bone rongeurs or a sharp osteotome. Tooth Extraction a. Periodontal ligaments around the dental apex and on the mesial and distal aspects were disrupted with a sharp elevator and a gouge. b. The tooth was sectioned longitudinally or transversely using a bur or sharp chisel. c. The apical dental fragments were separated and elevated through the osteotomy site and any coronal fragments were repulsed into the oral cavity if the path was unobstructed by adjacent teeth. Procedure C: Transcutaneous Lateral Alveolar Ostectomy as described by Rawlinson 5 as modified from Tremaine 6 All performed with either standing sedation or under general anesthesia. a. The junction of the buccal mucosa and the alveolar mucosa (vestibule) adjacent to the tooth to be extracted. b. The clinical crown of the tooth to be extracted. Incision a. The skin incision was placed directly over the tooth to be extracted. b. Premolar: a curvilinear, horizontal incision extending in a rostrocaudal direction with the base oriented apically was created. The most ventral portion of the incision was placed directly over the tooth midway between the vestibule (previously marked) and the root apices of the tooth. 76

4 c. Molar: a vertical incision running in a dorsoventral direction was created. This incision was slightly tilted in the rostrodorsal to caudoventral plane to mimic the angle of the tooth in the mandible. The incision ran from just ventral to the vestibule to the region of the root apices. d. The reason for centering the incision ventral to the vestibule was to avoid penetration into the oral cavity via the cheek. e. Facial anatomy was dissected carefully in routine fashion providing hemostasis during progression until the periosteum of the bone was encountered. Access to Tooth a. The periosteum was incised and elevated. The periosteum was elevated from the root apices to the attached gingiva of the tooth to be extracted. b. The attached gingiva was elevated off the bone to allow access into the oral cavity. The gingival opening was extended rostral and caudal so the mesial and distal aspects of the tooth to be extracted could be visualized. This allowed for confirmation of the position of the diseased tooth. c. A Hohman retractor was used to dorsally retract tissue and a Weitlaners retractor was used to retract tissue in the rostrocaudal direction. d. A high-speed surgical drill with a carbide bur and irrigation was used to carefully and precisely remove the alveolar bone plate clearly exposing the most mesial and distal aspects of the reserve crown. e. The alveolar bone plate was removed to the level of the furcation of the roots. Tooth Extraction a. The tooth was sectioned using the drill to make a V-cut into the tooth from the clinical crown ventral to the furcation. The V allows for visualization at the bottom of the cut. b. The lingual periodontal ligament was not penetrated during drilling. c. Once the tooth was sectioned longitudinally, the tooth fragments were tested for mobility with a dental elevator. If no mobility is detected, the reserve crown was sectioned in a mesiodistal manner. d. The dental fragments were elevated from the surgical site. The dental elevators were used to elevate these fragments. Procedure D: Repulsion as described by Coomer 7 All performed with standing sedation after attempts at oral extraction had failed. a. A hypodermic needle was inserted into the skin at estimated location for repulsion. b. Radiograph obtained to confirm position of trephine hole. Incision and Access to Tooth a. The size and position of tooth fragment determined the size of the skin incision and ostectomy. b. Intact teeth: a 16-mm-diameter circular Galt trephine was used to remove bone in preparation for a 9-mm- diameter punch. c. Dental fragments: an 8-mm-diameter tungsten carbide tipped metal drill bit was used to remove bone in preparation for a 5 mm punch. d. Axial alignment of punch controlled visually by surgeon standing in front of horse and viewing clinical crown in mouth using headlamp. Rostrocaudal direction of punch determined by surgeon with one hand on punch and other hand on clinical crown of tooth. Extraction of Tooth a. A nonsterile assistant hammered the dental punch using a heavy nonsterile mallet. b. Punch repositioned on tooth using triangulation method described above if necessary. Intraoperative radiographs were obtained periodically to verify correct seating of punch. c. Hammering continued until tooth loosening was palpated within the mouth and was continued until the tooth fragment could be removed manually. Immediate Post-Extraction Alveolus and Surgical Wound Management The alveolus was thoroughly debrided and flushed either intraorally or through the surgical site depending on approach. Take an intra-operative radiograph to ensure all dental and pathologic material has been removed. A variety of packing materials can be used to fill the alveolus: impression material, wax, plaster, antiseptic soaked gauze, etc. The author utilizes medium weight impression material, polyvinyl siloxane. Surgical sites were closed in a routine manner usually involving poliglecaprone (Monocryl) in a two to three layer closure. In some cases, a facial pressure wrap was used to minimize swelling within first 24 hours. Not all authors utilized a facial bandage. Post-operative pain management and antibiotics were provided as needed. 77

5 III. RESULTS Procedure A: Lateral Buccotomy Technique as described by O Neil One hundred and fourteen horses presented for surgery (77 maxillary and 37 mandibular) with a total of 134 teeth extracted in the manner described. Procedure-related complications were documented in 34 horses (30%). The majority of complications arose from partial wound dehiscence following extraction (47%). Maxillary skin incisions were more commonly involved than mandibular incisions, and all healed by secondary intention. A total of nine horses had evidence of trauma to the facial nerve, and three had permanent trauma to the facial nerve involving the lower lip. Four horses developed myositis in the immediate post-operative procedure related to general anesthesia. An oroantral fistula was inadvertently created in 4 horses, and five horses developed a persistent sinusitis following surgery, 2 of which were related to a dental remnant or packing material found in the maxillary sinus. One horse required a second course of antibiotics and alveolar curettage of an infected mandibular alveolus 6 weeks post-operative which resulted in complete healing. Overall, 92% of all horses returned to their previous level of work after >2 months with no complications. Procedure B: Transcortical Osteotomy and Buccotomy as described by Tremaine Eleven horses were treated with the above described procedure. Only one horse had an impacted maxillary cheek tooth. All other horses had impacted +/- infected mandibular cheek teeth. Following surgery, 2 horses had incisional dehiscence after removal of alveolar packing, and two horses had a prolonged draining tract necessitating further evaluation which demonstrated a fissure in the granulating alveolus but not sequestrae. These fissures were curetted and resolved. No facial nerve deficits were observed in any horse. All horses had marked nonpainful swelling of the mandible after surgery that gradually remodeled but was still present after 6 months in three horses. Long-term follow-up (median range 9 months) found all horses in work with no signs of continued dental disease. Procedure C: Transcutaneous Lateral Alveolar Ostectomy as described by Rawlinson as modified from Tremaine Short-term and long-term results of an ongoing study will be presented. Procedure D: Repulsion as described by Coomer A total of 18 horses and 20 teeth were extracted as described by Coomer. Teeth in 13 horses involved the maxillary arcade and 5 the mandibular. The median number of intraoperative radiographs was 6. No intraoperative complications were experienced. Median follow-up time was 13 months. Ten of 17 horses (59%) had complete resolution of clinical signs whereas 41% required follow-up medical or surgical treatment (50% [6/12] maxillary and 20% [1/5] mandibular) to resolve signs. Follow-up treatments involved ongoing drainage of the mandible and sinusitis. IV. DISCUSSION The following summary of the most recent publications regarding surgical extraction of mandibular cheek teeth demonstrates that when intraoral extraction attempts are either impossible or suboptimal a number of viable strategies remain for extraction. The high success rate for intraoral extraction is well-documented in the literature 2 and should be pursued when primarily possible. All procedures presented report minimal serious complications regarding extraction. Coomer s article does not reflect previously reported complication rates regarding repulsion. This may be due to either the small number of patients reported or improved efforts in triangulating the punch. The only major complications reported in all four studies were secondary to general anesthesia and unrelated overall systemic health issues. The term buccotomy is defined as a surgical incision through the cheek to gain access to an intraoral procedure. 8 Not all the procedures described should be considered buccotomies. Only O Neil s procedure describes a true buccotomy where access is made through the cheek to perform an intraoral procedure. All the other three procedures have transcutaneous approaches to perform surgery on a portion of the tooth not within the oral cavity. Entrance into the oral cavity is a secondary effect of these procedures, not the sole purpose for it. This distinction though minor is important as it changes the nature of significant adjacent regional anatomy and the need to provide as aseptic a working field as possible. Although the final outcome may be extracting the tooth through the mouth in some cases, the surgical procedure was performed within the mandible or maxilla. This point is important when reflecting upon the body of literature describing buccotomies and surgical complications resulting from these procedures. Potential operative and post-operative complications for the above described surgeries are: osseous bleeding in the region of the root apices, temporary or permanent paralysis of the ipsilateral buccal nerve, surgical site infection, displacement of the packing material, laceration of the mandibular artery, destruction of major regional arteries, veins, and nerves, laceration of parotid duct, tongue laceration, mandibular fracture, damage to adjacent teeth, and displacement of packing into irretrievable position. 9 With good surgical techniques, experienced drill skills, careful planning, and patience the author believes the majority of these possible complications can be avoided. The results reported by all four papers demonstrate that with careful and knowledgeable execution of the procedures described, resulting complications can be minimal with little significant impact on the overall health and performance of the horse. 78

6 In conclusion, surgical extraction of equine cheek teeth especially on the mandible can be performed in a very precise, controlled manner that has the potential to reduce the number of operative complications experienced by surgeons and dentists in the past. REFERENCES 1. Tremaine W, Schumacher J. Exodontia. In: Easley J. Dixon P, Schumacher J ed. Equine dentistry 3 rd ed. London: Saunders Elsevier, 2011; Dixon P, Dacre I, Dacre K, et. al. Standing oral extraction of cheek teeth in 100 horses ( ). Equine Vet J 2005;37(2): O Neil H, Boussauw B, Bladon B, Fraser B. Extraction of cheek teeth using a lateral buccotomy approach in 114 horses ( ). Equine Vet J 2011;43(3): Tremaine W, McCluskie L. Removal of 11 incompletely erupted, impacted cheek teeth in 10 horses using a dental alveolar transcortical osteotomy and buccotomy approach. Vet Surg 2010;39: Rawlinson JE. Surgical extraction of mandibular cheek teeth via alveolar bone removal. Proceedings of the American Association of Equine Practitioners Focus Meeting, 2011; Tremaine WH, Schumacher J. Exodontia. In: Easley J, Dixon PM, Schumacher J, ed.. New York: Saunders, 2011; Coomer RP, Fowke GS. Repulsion of maxillary and mandibular cheek teeth in standing horses. Vet Surg 2011;40: Dorland s Medical Dictionary. New York: Saunders Company, Dixon P, Hawkes C, Townsend N. Complications of oral surgery. Vet Clin Equine 2009;24: