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Can Vet J. 2010 April; 51(4): 416–420.
PMCID: PMC2839835

Extraction of a mandibular first molar tooth (409) in a dog

Fractured teeth with pulpal exposure necessitate treatment. This is a painful condition and the open canal provides direct communication between the oral cavity and supporting alveolar bone (1). Acute pulpal exposure goes from reversible hyperemia to irreversible pulpitis and chronic suppurative pulpitis and necrosis ensue (2). The fracture site allows food debris and bacteria to enter the canal and travel to the supporting tooth structure, leading to periapical granulomas and abscesses, osteitis, and bone loss, periapical periodontitis or “retrograde periodontitis” (3), external root resorption, and possibly to systemic diseases.

Options for treating fractured teeth with pulpal exposure consist of extraction or endodontics. Endodontics is the treatment of the pulp of the tooth with the objective of maintaining a vital tooth, or eliminating pain and infection from a dead tooth and the supporting tooth structures (4). Extraction would be recommended if root canal therapy were deemed to be unsuccessful because of extensive periapical abscessation, with extensive structural damage, or if the tooth were experiencing external resorption (4). Owners may elect extraction if it is the least expensive option to treat the diseased tooth.

Signalment and history

A 13-year old, male, border collie was presented from a referring veterinarian because of a fractured mandibular right first molar tooth, (409), found at the time of the annual physical examination. The owner requested extraction of this tooth.

Physical examination

The patient was bright, alert, and responsive, and his general appearance was normal. Upon presentation, his weight was 14.8 kg, his temperature was 39.0°C, and he had a heart rate of 100 beats per min, and a respiratory rate of 32 breaths per min. A complete, thorough physical examination revealed bilateral immature cataract formation as the only pathology other than that found on oral examination.

On oral examination he had a moderate amount of calculus and plaque, and moderate gingival reaction. The lower right first molar, tooth 409, had a transverse fracture across the central and mesial cusp and a mesial vertical crown fracture on the lingual aspect (Figure 1). The pulp was exposed, and the openings to the canals at the fracture sites were discolored brown. When probed, the probe fell into the canals. The patient appeared sensitive to probing.

Figure 1
Lower right first molar, tooth 409, with transverse fracture across the central and mesial cusp, and a mesial vertical crown fracture on the lingual aspect. The pulp is exposed.

Diagnosis

The diagnosis, based on oral examination, was moderate calculus, plaque, and gingivitis; fractured mesial and central cusp of tooth 409 with pulpal exposure.

Therapeutic plan

Tooth 409 is a strategic tooth; however, its structure had been greatly damaged by the fracture. While standard root canal therapy was discussed with the owner to alleviate patient discomfort and infection and to maintain tooth function and the remaining structure, the owner requested extraction of this tooth. Osseoconductive implants to promote bone healing were recommended to the owner.

The owner declined this therapy for financial reasons. A routine dental prophy and daily oral home care to control periodontal disease were discussed with the owner. A therapeutic plan was formulated and staged as follows: a complete blood (cell) count (CBC)/General Health Profile was to be obtained immediately. If the analysis was unremarkable, under general anesthesia, a local nerve block of the right inferior alveolar nerve would be administered.

An intraoral radiograph of tooth 409 would be obtained and evaluated to assess the health of the alveolar bone, the visibility of the periodontal ligament, root anatomy, root ankylosis or resorption (4). A buccal gingival flap would be created, alveolar bone removed to facilitate extraction of the tooth with minimal trauma, the tooth sectioned into its 2 halves, then elevated from the alveolar sockets. The alveoli would be debrided and any bony projections smoothed. After lavaging the area and taking a postoperative radiograph, the gingival margins would be approximated and sutured. The client had been advised previously on fasting the patient for anesthesia by withholding food after midnight the night before and water from 6 am the day of surgery.

Follow-up appointments were to be scheduled in 2 wk and 1 mo to assess healing. The owner, living several hundred miles away, declined the 2-wk follow-up appointment.

Procedure

The patient was admitted. The preoperative blood work was unremarkable. The patient was pre-medicated with 3 mg butorphenol tartrate (Torbugesic; Fort Dodge Animal Health, Fort Dodge, Iowa, USA) and 0.15 mg acepromazine male-ate (Acepromazine; Ayerst Laboratories, Montreal, Quebec) intra-muscularly. A cephalic intravenous catheter (Terumo Sur-Flo IV Catheter; Terumo Medical Corporation, Oakville, Ontario) was placed and lactated ringers (Lactated Ringer’s: Baxter Corporation, Toronto, Ontario) at a rate of 150 mL/h was administered through a volumetric infusion pump (Baxter Flo-Gard 6200: Baxter Diagnostics, Deerfield, Illinois, USA). Anesthesia was induced with 1.5 mL of a 50/50 mixture of ketamine hydrochloride (100 mg/mL) (Ketalean 100 mg/mL; Bimedia-MTC Animal Health, Cambridge, Ontario) and diazepam (5 mg/mL) (Diazepam 5 mg/mL; Sabex, Boucherville, Quebec) injected slowly and to effect, intravenously. Intubation was performed with an 8-mm endotracheal tube (Endotracheal Tube: Rusch, Germany) and the cuff was inflated to prevent inhalation of foreign matter and fluids. Anesthesia was maintained with 2% isoflurane (Isoflurane: Bimeda-MTC Animal Health) and 1 L/min oxygen. A heat pump (Gaymar T/Pump: Gaymar Industries, Orchard Park, New York, USA), hot water bottles, and blankets were used throughout the procedure to maintain body temperature at 37.5°C to 38°C. Throughout anesthesia, the patient’s heart rate, respiratory rate, saturation of peripheral oxygen (SPO2) and systolic blood pressure were monitored and recorded every 5 min.

A local anesthetic nerve block of the right alveolar nerve was administered using approximately 0.5 mL bupivacaine (5 mg/mL) with epinephrine 1:200 000 (Marcaine: Abbott Laboratories, North Chicago, Illinois, USA) (9) via a dental syringe (Self-Aspirating Syringe: Miltex Instrument Company, Bethpage, New York, USA) and a 27-gauge long dental needle (Monoject UltraSharp Dental Needles 27G Long, 1 1/2”): Sherwood Medical, St. Louis, Missouri, USA). This would provide pre-emptive analgesia. The intraoral radiograph demonstrated a periapical lucency or “halo” of the alveolar bone around the mesial and distal root, a fractured central and mesial crown cusp, and a horizontal loss of bone (Figure 2).

Figure 2
Intraoral radiograph of tooth 409. Note the periapical lucency or “halo” of the alveolar bone around the mesial and distal root, a fractured central and mesial crown cusp, and horizontal loss of bone.

At this point the isoflurane concentration was reduced and maintained at 1.5%. A full-thickness muco-periosteal flap was created. First a #15 scalpel blade was inserted into the sulcus until meeting resistance with the alveolar crestal bone. This crevicular incision was extended around the tooth, severing the epithelial attachment. Apically diverging releasing incisions were made at the mesial and distal line angles of tooth 409, from the free gingival margin to just distal to the mucogingival junction (3) (Figure 3). The flap was gently elevated from the buccal bone of tooth 409 with a periosteal elevator (Cislak EX-7 Feline Periosteal Elevator: Cislak Manufacturing, Glenview, Illinois, USA). The lingual tissue was elevated as an envelope flap to expose the alveolar crest. Once the flap was created, approximately 3 mm of buccal alveolar bone was detached from the rest of the buccal bone along the buccal surface of tooth 409 with a #6 round bur (Round Trimming & Finishing Bur: Henry Schein Arcona, St. Catharines, Ontario) on a high-speed handpiece with water coolant. The freed bone was removed with a bone chisel (Cislak FEDI-1 Perio & Bone Chisel: Cislak Manufacturing). This exposed the coronal aspect of the roots including the furcation (Figure 4). A 699 cross-cut bur (u #699-009 Carbide Cross Cut Tapered Fissure Bur:Brasseler Canada, Montreal, Quebec) on a high-speed handpiece with water coolant was used to section the tooth into 2 sections, starting at the furcation and proceeding coronally (Figure 5). A variety of elevators (#3&4 “Winged” Elevators; Dentalaire, Fountain Valley, CA; Miltex 34 Elevator; Miltex Instrument Company; Cislak EX-# Large Surgical Elevator: Cislak Manufacturing) were used to sever the periodontal ligament. These were gently pressed along the periodontal ligament space between the tooth and socket. Steady pressure was held on the elevator for 10 s with a slight twisting action. The elevator used was advanced apically repeating the process, stretching, and tearing the periodontal ligament and causing hemorrhage within the ligament space. This process was repeated circumferentially around the tooth until the tooth was loosened from the socket. Extraction forceps (VetCare Large Extraction Forceps; Dentalaire, Fountain Valley, California, USA) were used to grasp the tooth apically and extract the loosened sections (Figure 6).

Figure 3
Apically diverging releasing incisions made at the mesial and distal line angles of tooth 409, from the free gingival margin to just distal to the mucogingival junction.
Figure 4
Tooth 409 and osteoplasty of the alveolar bone to expose the coronal portion of the roots and furcation.
Figure 5
Tooth 409 sectioned into 2 sections from the furcation to the tip of the crown, through and through.
Figure 6
Extracted tooth 409.

The alveoli were curetted with a spoon curette (Cislak EN-9 Excavator; Cislak Manufacturing), removing any granulation tissue or debris within. A #4 round bur (4-014 Round Carbide Bur; Brasseler Canada) on a high-speed handpiece was used to smooth any rough bony edges (Figure 7). The alveoli were lavaged with a 0.12% chlorhexidine solution (Nolvadent Oral Cleansing solution; Fort Dodge Laboratories).

Figure 7
Alveolar sockets of tooth 409. Note the smooth edges and blood clot in the alveolar sockets.

A post-operative radiograph was obtained. All roots were entirely removed and there were no sharp bony projections noted. No alveolar or mandibular fractures were present, and the adjacent teeth appeared unharmed on the radiograph (Figure 8).

Figure 8
A post-operative radiograph of extracted tooth 409. Both roots are entirely removed and there are no sharp bony projections noted. No alveolar or mandibular fractures are present, and the adjacent teeth appear unharmed.

With the flap elevated, a #15 scalpel blade was applied to the underside of the flap, incising the inelastic periosteal layer. This allowed a release of tension in the flap. The flap margins were approximated and an interrupted suture pattern of 4-0 absorbable monofilament suture material (4-0 Monocryl: Ethicon Inc, Somerville, New Jersey, USA) was placed over the bone for support. The corners were sutured first, with additional sutures placed approximately 3 mm apart and approximately 3 mm from the gingival edges. When finished, the flap was tensionless (Figure 9).

Figure 9
The sutured, tensionless flap.

Following the extraction a complete dental prophy was performed. All teeth were scaled with an ultrasonic scaler, and a variety of hand scalers and curettes, and then polished with a fine prophy paste with fluoride (Prophylaxis Paste With Fluoride: A.R. Medicom, Montreal, Quebec). A sulcular flush of 0.12% chlorhexidine solution was performed on each tooth, and then a 1-minute gel (Professional Care Products One Minute Acidulated Phosphate Fluoride; Challenge Dental Canada, Delta, British Columbia) applied, and then wiped off using a gauze square. A dental examination was performed and each tooth was probed. The sulcus depths were normal at a depth of 2–3 mm.

The patient was given 3 mg butorphenol tartrate intramuscularly and 300 000 IU penicillin G procaine intramuscularly, then taken off the isoflurane anesthesia and allowed to breathe oxygen for 1 min, then taken off oxygen. Once his swallowing reflex returned, the cuff was deflated, and the endotracheal tube removed. His recovery was uneventful and he was discharged the same day.

The patient was sent home on 187.5 mg amoxicillin and clavulanate potassium (Clavamox: Pfizer Canada, London, Ontario) every 12 h for 10 d and 150 mg acetaminophen with 15 mg codeine phosphate (Novo-Gesic C; Novopharm, Toronto, Ontario) (5,6) QID for 3 d. The owners were instructed to rinse the sutures twice daily with a 0.12% chlorhexidine oral solution and to feed the dog canned food for 2 wk while the sutures were in the mouth. They were counseled on appropriate chew toys to be given. They were instructed to brush his teeth and gums twice daily with a veterinary toothpaste (C.E.T. Enzymatic dentifrice: VRX Products, Harbour City, California, USA).

Follow-up

A follow-up phone call the next day and a week later confirmed the patient was bright, energetic, and eating well. The owner was following discharge instructions. An office examination was scheduled in 1 mo to assess healing of the tissues.

Discussion

While tooth preservation is desired, owners may elect other options for treatment. These options must produce an acceptable outcome and be performed in the least traumatic manner for our patients. Both extractions and endodontic therapy have potential complications. Specific complications for root canal treatment in this patient may include further weakening of the tooth, which may lead to possible continued tooth fracture by removal of structure to access pulp canals and by increased brittleness of a dead tooth, perforation of the pulp cavity when tissues are diseased, perhaps requiring surgical endodontics, or any type of instrumentation errors (7). In order to assess healing after root canal treatment, follow-up radiographs, generally under anesthesia for veterinary patients, is required. This owner lived several hundred miles away from veterinary care and was unwilling to have the patient re-anesthetized for follow-up. The client was also unwilling to accept or deal with any potential endodontic therapy complications.

While extraction rids the patient of a diseased tooth, there are potential complications. The lower first molar tooth is near the mandibular canal; therefore, careful instrument handling is necessary to prevent instrument slippage that may result in hemorrhage or trauma to the mandibular nerve, or loss of tips into the canal space. The shaft of the instrument, close to the working end, must be stabilized with the index finger to avoid slippage (4). The mesial root of tooth 409 is large and fracture of the mandible may result unless elevation of the tooth is gently done with precision (7). Cradling the lower jaw with the free hand neutralizes pressure applied during extraction to prevent jaw fracture (4). Fracture of a root with the tip retained in the alveolus is common. Patience, avoiding excessive torque, and holding the tension on the periodontal ligament for at least 10 s will help avoid this complication (2). Fracturing the buccal bone may be avoided by adequate removal of alveolar bone (4).

Local nerve block anesthesia, placed under general anesthesia, prevents sensitization of pain pathways (8). It reduces intra-operative pain, thereby lessening the need for deep anesthesia, reduces vagally mediated reflex bradycardia, hypotension, and hypoventilation noted with higher gas concentrations (9). Local anesthesia allows for pain control with a lower total dose of analgesics, and provides post-operative analgesia for 6 to 8 h after administration (8). It makes for a safer anesthetic and a faster, less eventful recovery. Bupivacaine is administered 5 min prior to the painful procedure as it requires this length of time to take effect (9). Epinephrine with bupivacaine reduces hemorrhage and prolongs the activity of bupivacaine (10).

A full-thickness flap includes all soft tissues and the periosteum (3). It is reflected to expose the underlying bone and root surfaces. This helps to improve visibility, speeds access to and removal of the tooth, and allows for osteoplasty of the alveolar bone. Vertical releasing incisions are made at the line angles of the tooth (7). These line angles are the theoretical intersection of 2 of the tooth’s external walls. A tensionless flap is required to avoid flap breakdown and to be able to reposition the flap to cover all bone. This is accomplished by osteoplasty and incising the inelastic periosteum on the underside of the flap, providing greater movement of the flap (7).

Osteoplasty to recontour the bone edges and remove any sharp bony projections will allow the gingival tissues to heal atraumatically and reduces discomfort to the patient post-operatively.

Osseoconductive products to help in osseous healing benefit sites where a large defect remains. The mandibular first molar tooth in the dog is a large tooth with large roots. The loss of this tooth may weaken the remaining bone (7). For economic reasons, the owner declined this therapy.

In summary, teeth should not be sacrificed unnecessarily. Maintaining tooth function and structure whenever possible is always the desired focus. However, circumstances of the diseased tooth or client decisions may place extraction of the tooth as the only option. When this is so, the extraction technique needs to be atraumatic to the remaining tissues, allow expedient healing, and minimize patient discomfort post-operatively. Knowledge of oral anatomy; gentle, steady pressure with appropriately sized elevators; and patience are required. This will result in roots being removed in their entirety leaving a non-traumatized extraction site.

Footnotes

Use of this article is limited to a single copy for personal study. Anyone interested in obtaining reprints should contact the CVMA office ( gro.vmca-amvc@nothguorbh) for additional copies or permission to use this material elsewhere.

References

1. Shipp AD. Fahrenkrug. Beverly Hills, California: Dr. Shipp’s Laboratories; 1992. Practitioners’ Guide to Veterinary Dentistry; pp. 77–79.
2. Harvey CE, Emily PP. Small Animal Dentistry. Vol. 321. St. Louis, Missouri: Mosby-Year Book; 1993. p. 159.
3. Carranza FA, Newman MG. Clinical Periodontology. Philadelphia: WB Saunders; 1996. pp. 592–597.pp. 649
4. Holmstrom SE, Frost P, Eisner ER. Veterinary Dental Techniques for the Small Animal Practitioner. Philadelphia: WB Saunders; 1998. pp. 216–218.pp. 256
5. Matthews KA. Non-steroidal anti-inflammatory analgesics. Indications and contraindications for pain management in dogs and cats. Vet Clin North Am Small Anim Pract. 2000;30:783–804. [PubMed]
6. McLaughlin R. Management of chronic osteoarthritic pain. Vet Clin North Am Small Anim Pract. 2000;30:933–949. [PubMed]
7. Wiggs RB, Lobprise HB. Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997. pp. 213pp. 214pp. 238pp. 310pp. 320pp. 325–335.
8. Matthews NS. Peri-Operative Analgesia Proceedings 13th Annual Veterinary Dental Forum; Baltimore, Maryland. 1999. p. 83.
9. Rochette J. Local Anesthetic Nerve Blocks and Oral Analgesia. Proc World Small Anim Vet Assoc, 26th World Congress. 2001:250–252.
10. Tholen MA, Hartsfield S. Concepts in Veterinary Dentistry. Edwardsville, Kansas: Veterinary Medicine Publ Co; 1983. pp. 23–31.

Articles from The Canadian Veterinary Journal are provided here courtesy of Canadian Veterinary Medical Association