Tips to Avoid Tooth Extraction Complications

September/October 2017   •   (Volume 7, Number 5)

Brenda L. Mulherin, DVM, DAVDC
Iowa State University College of Veterinary Medicine

One of the most common procedures performed by general practitioners in the oral cavity is surgical tooth extraction. The procedure is either a closed extraction, in which the tooth is extracted without a mucoperiosteal flap, or an open extraction, in which a mucoperiosteal flap is created to expose and remove alveolar bone and allow a tension-free closure.

To a client, tooth extractions may seem routine and commonplace. However, those who have experience with oral surgery are aware that even theoretically simple extractions can be difficult. This article presents some factors to consider to make surgical extractions as safe and easy as possible for both surgeon and patient.

EXTRACTION INDICATIONS AND COMPLICATIONS

The decision to extract a tooth stems from a variety of reasons, including1,2:

  • Complicated crown fracture
  • Endodontic disease
  • Periodontal disease
  • Malocclusion
  • Tooth resorption
  • Tooth nonvitality

The difficulty of an extraction can be affected by the health of the periodontium surrounding the tooth. If the periodontium is healthy, but the pulp is diseased, the tooth may be difficult to extract. Examples of teeth with healthy periodontium include those extracted to treat a malocclusion, which are healthy teeth in the wrong place. This is common in immature patients with persistent deciduous teeth, or when interceptive orthodontic procedures are performed. Other examples are recently fractured teeth with pulp exposure (Figure 1) for which endodontic therapy is not an option.1

FIGURE 1. (A) Recent crown fracture of the right maxillary canine tooth with pulp exposure. (B) An endodontic file placed in the pulp chamber of the fractured tooth to confirm pulp exposure. (C) Radiograph of the fractured tooth. The tooth was not mobile and there is no radiographic evidence of periapical lucency.

Planning ahead can help avoid complications relating to surgical tooth extraction. This includes taking intraoral dental radiographs and having the ability to interpret the radiographic findings. Knowledge of dental radiographic interpretation can help avoid some major pitfalls when surgically extracting teeth. This knowledge includes understanding what constitutes normal and abnormal anatomy as well as a general knowledge of the surrounding hard and soft tissue structures.

DENTAL DILEMMA

Avoid complications associated with surgical tooth extractions by planning carefully and having a general knowledge of canine and feline dentition and tooth root numbers.

NORMAL DENTITION AND TOOTH ROOTS

Canine Dental Formulas

The deciduous (primary) dentition of the canine oral cavity comprises 28 teeth (Table 1). The dentition is multiplied by 2 to include both right and left arcades. There are 3 incisors (i), 1 canine (c) tooth, and 3 premolars (pm) in each of the maxillary and mandibular arcades: 2 × (i 3/3, c 1/1, pm 3/3) = 28 teeth.3

The permanent (secondary) dentition of the canine oral cavity comprises 42 teeth (Table 1 and Figure 2). There are 3 incisors (I), 1 canine (C) tooth, and 4 premolars (PM) in each of the maxillary and mandibular arcades. Each maxillary arcade has 2 molars (M), and each mandibular arcade has 3 molars: 2 × (I 3/3, C 1/1, PM 4/4, M 2/3) = 42 teeth.3

Table 1 Canine and Feline Dental Formulas
DENTITION TOTAL TEETH TEETH IN EACH
MAXILLARY ARCADE
TEETH IN EACH
MANDIBULAR ARCADE
CANINE
Deciduous (primary) 28 i3, c1, pm3 i3, c1, pm3
Permanent (secondary) 42 I3, C1, PM4, M2 I3, C1, PM4, M3
FELINE
Deciduous (primary) 26 i3, c1, pm3 i3, c1, pm2
Permanent (secondary) 30 I3, C1, PM3, M1 I3, C1, PM2, M1

FIGURE 2. Radiographic images of normal canine tooth anatomy. (A) Right maxilla. (B) Central maxilla. (C) Left maxilla. (D through H) Right maxillary teeth. (I through L) Left maxillary teeth. (M) Right mandible. (N) Central mandible. (O) Left mandible. (P through T) Right mandibular teeth. (U through Y) Left mandibular teeth.

Feline Dental Formulas

The deciduous dentition of the feline oral cavity comprises 26 teeth (Table 1). There are 3 incisors, 1 canine, and 3 premolars in each maxillary arcade. Each mandibular arcade has 3 incisors, 1 canine, and 2 premolars: 2 × (i 3/3, c 1/1, pm 3/2) = 26.3,4

The permanent dentition of the feline oral cavity comprises 30 teeth (Table 1 and Figure 3). There are 3 incisors, 1 canine, 3 premolars, and 1 molar on the right and left maxillary arcades. Each mandibular arcade has 3 incisors, 1 canine, 2 premolars, and 1 molar: 2 × (I 3/3, C 1/1, PM 3/2, M 1/1) = 30.3,4

FIGURE 3. Radiographic images of normal feline tooth anatomy. (A) Right maxilla. (B) Central maxilla. (C) Left maxilla. (D and E) Right maxillary teeth. (F and G) Left maxillary teeth. (H) Right mandible. (I) Central mandible. (J) Left mandible.

Tooth Root Structure

A standard number of roots are associated with each tooth (Table 2). The number of roots helps determine the type of extraction necessary; therefore, it is important to know the root structure of the tooth or teeth being treated. However, abnormal tooth and root structures do occur, making presurgical radiographs essential (see Tooth Root Abnormalities). For example, canine maxillary second and third premolars and mandibular second, third, and fourth premolars each have 2 roots within the normal structure; however, many of these teeth have an accessory root.5

Cats appear to have more variations in normal root structures than dogs. The feline mandibular third and fourth premolars and the mandibular first molar teeth all should have 2 roots.5 One study found that the feline maxillary second premolar is absent in 7.9% of cats, has a single root in 27.7% of cats, has partially fused roots in 55.1% of cats, and has 2 fully formed roots in 9.2% of cats.6 This study also found that the feline maxillary first molar is absent in 2.3% of cats, has a single root in 35% of cats, has partially fused roots in 34.7% of cats, and has 2 fully formed roots in 28% of cats.6

Table 2 Standard Number of Tooth Roots of Canine and Feline Permanent Teeth
ARCADE ARCADEINCISOR TEETH CANINE TEETH PREMOLAR TEETH MOLAR TEETH
CANINE
Maxillary 1 root each 1 root each 1st: 1 root

2nd: 2 roots

3rd: 2 roots

4th: 3 roots (2 mesial, 1 distal)

1st: 3 roots (2 buccal, 1 palatal)

2nd: 3 roots (2 buccal, 1 palatal)

Mandibular 1 root each 1 root each 1st: 1 root

2nd: 2 roots

3rd: 2 roots

4th: 2 roots

1st: 2 roots

2nd: 2 roots

3rd: 1 root

FELINE
Maxillary 1 root each 1 root each 2nd: 1 or 2 roots

3rd: 2 roots

4th: 3 roots (2 mesial, 1 distal)

1st: 1 or 2 roots
Mandibular 1 root each 1 root each 3rd: 2 roots

4th: 2 roots

1st: 2 roots

TOOTH ROOT ABNORMALITIES

Dental radiography is necessary to assess whether there are root abnormalities that can affect an extraction.

Supernumerary Roots

A supernumerary (extra) root can make a seemingly straightforward extraction more difficult, especially if not identified on dental radiography. The feline maxillary second premolar and first molar can have 1 to 3 roots.6 Dogs can also have supernumerary roots (Figure 4). One study reported that 15.2% of large mesaticephalic-breed dogs have at least 1 supernumerary root within the oral cavity.7

FIGURE 4. (A) Radiographic image of the maxillary third premolar tooth with a supernumerary root (arrows) in a dog. The maxillary fourth premolar has radiographic evidence of a periapical lucency indicative of endodontic disease. (B) Photographic image of the maxillary premolars of the same dog.

Development Abnormalities

Some abnormalities can make an extraction easier. These usually involve teeth that normally have 2 roots, but have developed only a single root. These teeth may be affected by fusion, gemination, or concrescence. Identification of these teeth on dental radiographs allows the surgeon to eliminate sectioning during extraction.

Fusion is when 2 tooth buds have joined, resulting in a single-rooted tooth with 2 root canals.7,8 Gemination is the incomplete development of 2 teeth from 1 tooth bud, which usually results in a tooth with 2 crowns but only a single root.7,8 Concrescence is the joining of adjacent teeth by the cementum only.7,8

Often, these developmental abnormalities cannot be differentiated without the aid of histopathology (Figures 5 and 6). In many instances, these teeth can remain in the mouth if crowding, periodontal disease associated with the tooth, or radiographic evidence of disease is not present. Regardless of which developmental condition has occurred, if the tooth needs to be extracted, knowing how many roots need to be removed is the most important consideration.

FIGURE 5. Crown abnormalities of incisor teeth in a dog.

FIGURE 6. Radiographic image of root fusion (arrows) that may affect extraction.

Dilacerated Roots

Dilacerated roots are roots that bend at sharp angles, which can make extracting them in their entirety difficult (Figures 7 and 8). Dilacerated roots can curve toward the caudal or rostral aspect of the mouth. In one study, 34.4% of dogs had evidence of tooth root dilacerations.8

Again, presurgical dental radiographs are necessary to identify dilacerated roots and their direction. Without the knowledge of whether dilaceration is present, surgical extraction can fracture dilacerated roots. Of even greater concern is when the dilacerated root is positioned close to the ventral mandibular cortex. If the surgeon is not careful, extraction technique or fractured root tip retrieval can result in a mandibular jaw fracture.

FIGURE 7. Dilacerated mandibular tooth roots with evidence of periodontal disease shown by severe horizontal and vertical bone loss.

FIGURE 8. Dilacerated mandibular tooth roots with evidence of periodontal disease shown by vertical bone loss associated with the distal root of the first molar.

PLANNING FOR TOOTH EXTRACTIONS

Schedule Adequate Time

Scheduling the appropriate amount of procedure time alleviates additional stress, allows ideal surgical technique, and permits the procedure to be performed without time constraints. The most important aspect of tooth extraction is patience. When applying pressure to the tooth root, using slow, gentle, consistent pressure to extract the root is better than forceful, jerky, sudden movements. Rushing through an extraction procedure often leads to an audible crack that signifies the fracture of the tooth root or, more seriously, of the surrounding bone.

Gently controlling the elevation of the gingiva and mucosa of the tooth to be extracted allows exposure of the underlying alveolar bone and encourages adequate postoperative healing of the extraction site. Traumatic and rapid elevation of the mucoperiosteal flap can tear tissue, delay healing, and, if severe enough, reduce flap size.10

Adequate bone removal over the tooth roots allows root exposure and visualization of the structures to be extracted and helps reduce the time needed for the extraction. Gentle, consistent pressure applied to the roots during elevation weakens the periodontal ligament. This allows for increased mobility of the root to eventually facilitate removal.

Use Proper Equipment

Proper equipment ensures smoother surgical extractions. Important items include:

  • Sharp, appropriately sized elevators for reflecting the soft tissues (Figure 9) and winged elevators or luxators for elevation of the roots in question
  • Root tip picks, if needed
  • Extraction forceps (Figure 10)
  • New, appropriately sized dental burs for tooth sectioning, removing alveolar bone, and smoothing the bone following tooth removal (Figure 11)

FIGURE 9. Sharp periosteal elevator for reflecting soft tissue

FIGURE 10. Extraction forceps for tooth root removal.

FIGURE 11. New pear carbide bur for alveolar bone removal.

Having clean and sterile surgical packs made specifically for dental extractions can ensure all of the hand instruments are ready for use, if needed. Sharpen hand instruments after each use to help maintain their shape, sharpness, and tactile sensitivity (Figure 12).

Proper equipment also includes dental radiography. Regardless of whether the dental radiographs are film or digital, radiographic assessment of teeth is the most important diagnostic information needed to make the surgery as straightforward as possible.

FIGURE 12. Dull winged elevator; note the rough and irregular surfaces at the edges. At minimum, this instrument needs sharpening, but it may need to be replaced.

Expose the Tooth Extraction Site

For a successful extraction, make sure to expose the alveolar bone and tooth root(s). When removing alveolar bone over selected roots, a rule of thumb is to remove one-half to two-thirds of the bone covering the root surface.

Ultimately, the goal is to remove as much bone as necessary to remove the tooth roots without being overly aggressive. Removing too much bone can compromise the surrounding hard and soft tissue structures associated with the tooth.

Surgical extraction of the selected tooth can be facilitated by:

  • Creating a mucoperiosteal flap
  • Removing an adequate amount of bone
  • Ensuring appropriate sectioning of the tooth over individual roots, when necessary

Consider an appropriate mucoperiosteal flap design with either a single releasing incision or a double releasing incision. The releasing incisions should be divergent to allow exposure of the alveolar bone, but the incision should not be created directly over the area where the bone is removed. This design also helps allow for tension-free closure over the extraction site.

An extraction attempted with limited exposure of bone can damage surrounding soft tissue structures, the mucoperiosteal flap, and the bone adjacent to the selected tooth.10 Limited exposure also increases the risk of root fracture during elevation.

SUMMARY

Avoid complications associated with surgical tooth extractions by planning carefully and having a general knowledge of canine and feline dentition and tooth root numbers. Using dental radiographs to assess the root structure and surrounding bone is vital to planning an appropriate approach to tooth extraction.

With enough time scheduled for the procedure and proper equipment, including sharp instruments and new burs, the surgeon can surgically extract teeth as safely as possible. Carefully preparing the mucoperiosteal flap over the selected tooth provides the visibility needed to remove an appropriate amount of alveolar bone, elevate the tooth roots, extract the roots from the oral cavity, and create a tension-free closure.

References

  1. Holmstrom SE, Fitch PF, Eisner ER. Exodontics. In: Holmstrom SE, Fitch PF, Eisner ER, eds. Veterinary Dental Techniques for the Small Animal Practitioner. 3rd ed. Philadelphia: Saunders; 2004:291-338.
  2. Wiggs RB, Lobprise HB. Oral surgery. In: Wiggs RB, Lobprise HB, eds. Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:232-258.
  3. Wiggs RB, Lobprise HB. Oral anatomy and physiology. In: Wiggs RB, Lobprise HB, eds. Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:55-86.
  4. Lewis JR, Reiter AM. Anatomy and physiology. In: Niemiec BA, ed. Small Animal Dental, Oral & Maxillofacial Disease. Boca Raton: Manson; 2013:9-38.
  5. Wiggs RB, Lobprise HB. Oral examination and diagnosis. In: Wiggs RB, Lobprise HB, eds. Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:87-103.
  6. Verstraete FJ, Terpak CH. Anatomic variations in the dentition of the domestic cat. J Vet Dent 1997;14:137-140.
  7. Pavlica Z, Erjavec V, et al. Teeth abnormalities in the dog. Acta Vet Brno 2001;70:65-72.
  8. Wiggs RB, Lobprise HB. Dental and oral radiology. In: Wiggs RB, Lobprise HB, eds. Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:140-166.
  9. Evans HE. Systemic arteries, aortic arch. In: Evans HE, ed. Miller’s Anatomy of the Dog. 3rd ed. Philadelphia: Saunders; 1993:602-645.
  10. Peterson LJ. Prevention and management of surgical complications. In: Peterson LJ, Ellis III E, Hupp HR, Tucker MR, eds. Contemporary Oral and Maxillofacial Surgery. 4th ed. St. Louis: Mosby; 2003:221-235.

Brenda L. Mulherin, DVM, DAVDC, currently practices at Iowa State University College of Veterinary Medicine (CVM). She received her DVM from Iowa State University and later returned to Iowa State to fill a position in primary care. Dr. Mulherin completed a dual appointment with Iowa State University CVM and the University of Wisconsin-Madison School of Veterinary Medicine in a dentistry and oral surgery residency. She is currently developing the dentistry and oral surgery program at Iowa State University CVM.

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