Dr. Charlier brings to dentistry continuing education more than 35 years of small animal practice, specialty practice, and ownership experience. She has received the Peter Emily Outstanding Candidate Award and the Fellow of the Year award. In 2004, she created VDENT (Veterinary Dental Education, Networking & Training) to educate the entire veterinary healthcare team about the value of oral health and its effects on all of our patients. In 2017, she was named the NAVC Small Animal Speaker of the Year.Read Articles Written by Cindy Charlier
A thorough intraoral examination must be part of every physical examination, beginning with a puppy’s first visit. Early diagnosis of fractured deciduous teeth, deciduous malocclusions, and persistent deciduous teeth allows for immediate treatment, thus preventing pain for the patient and potential pathology of the developing permanent teeth.
This article describes the anatomy of the deciduous tooth and its relationship to the developing permanent tooth, proper technique and appropriate instrumentation for removing deciduous teeth, and tips for minimizing complications during extraction.
Tooth Development and Eruption
Eruption of a permanent tooth is a continuous process that begins with formation of the tooth bud and stops only when the tooth is lost or the dog dies.1 In the developing fetus, deciduous and permanent tooth buds form at approximately the same time. The dental lamina of the permanent tooth normally splits off from the deciduous tooth lamina. If a deciduous tooth is missing because the dental lamina failed to form, then the permanent tooth will also be missing. Remember that dogs have no deciduous precursors to the first premolar or molar teeth.
Exfoliation of deciduous dentition is a complex function and is not fully understood. As the permanent tooth root begins developing, its crown contacts the deciduous root. The pressure of the crown on the deciduous tooth root stimulates resorption of the deciduous tooth. After sufficient root support is lost, the deciduous tooth crown is exfoliated.1 If no permanent tooth is present or if the permanent tooth does not erupt in the correct location, the deciduous tooth root does not resorb and may remain in place for years.
Although eruption times vary according to the breed and size of animal, all permanent teeth are usually erupted by the time a dog is 5 to 7 months of age.2 Permanent teeth erupt on the lingual or palatal side of their deciduous precursors except for the permanent maxillary canine teeth, which erupt on the mesial side of deciduous maxillary canine teeth (FIGURE 1).
Indications for Deciduous Tooth Removal
Fractured Deciduous Teeth
Active, chewing puppies easily fracture their long, thin, fragile deciduous canine teeth, resulting in pulp exposure (FIGURE 2). Similar to fractured permanent teeth, pulp exposure leads to pain, bacterial infection, and pulp necrosis (FIGURE 3). Extension of the resulting infection through the apex of the deciduous tooth may damage the adjacent developing permanent tooth bud(s). Periapical inflammation from a fractured deciduous tooth may interfere with development of the permanent tooth and lead to focal enamel hypoplasia, hypomineralization, or crown malformation of the developing permanent tooth.3 For these reasons, a fractured deciduous tooth should be extracted as soon as possible.
Deciduous Tooth Malocclusions
For any puppy with a traumatic occlusion in which the deciduous teeth are causing trauma to the soft tissues of the mouth, the most appropriate treatment is considered to be selective extraction of the deciduous dentition.4 Removing the deciduous tooth or teeth provides the potential for the dog to achieve full growth via relief of any dental interlock that may prevent mandibular growth.5 An additional benefit of interceptive orthodontics is elimination of pain created by deciduous tooth contact with the palate. Because continued treatment is often required during eruption of permanent dentition, referring patients with deciduous malocclusions to a board-certified veterinary dentist (avdc.org/find-a-veterinary-specialist) should be considered.
Persistent Deciduous Tooth
The term “persistent deciduous tooth” is used to describe a deciduous tooth that is not shed when its permanent tooth counterpart erupts. A deciduous tooth and its permanent counterpart should never be present at the same time (FIGURE 4). Persistent deciduous teeth are particularly common in toy breed dogs; the most commonly affected teeth are the incisors and canines.6
The potential consequences of a persistent deciduous tooth are increased risk for periodontal disease, malocclusion, and palatal trauma. A permanent tooth in contact with a deciduous tooth is often deprived of normal periodontal tissues.7 Plaque and calculus accumulate between the crowded teeth and predispose the permanent tooth to periodontal disease (FIGURE 5).
Orthodontically, a persistent deciduous canine tooth forces the permanent canine tooth to deviate from its normal pathway and erupt in an abnormal location. Retention of a deciduous tooth for as short a period as 2 weeks after eruption of the permanent tooth can result in occlusal defects in the permanent dentition.7
A persistent deciduous maxillary canine tooth results in mesial displacement of the permanent maxillary canine tooth, moving it into the interdental space that the permanent mandibular canine tooth would normally occupy. As a result, the permanent mandibular canine tooth is forced rostrally and lingually to maintain its position rostral to the maxillary canines. The displaced permanent mandibular canine tooth may contact the gingival or palatal soft tissues, the maxillary canine tooth, or maxillary incisor, resulting in abnormal tooth–tooth or tooth–soft tissue contact and discomfort for the dog.
A persistent deciduous mandibular canine tooth causes the permanent mandibular canine tooth to erupt in an abnormal position lingual to the deciduous tooth. Continued eruption of the permanent mandibular canine tooth in this position impinges on the hard palate, leading to pain and possible development of an oronasal fistula.
A persistent deciduous tooth should be removed as soon as the crown of the permanent tooth is visible above the gingival margin.5 Early removal of persistent deciduous canine teeth may allow the erupting permanent teeth to move into normal occlusion (FIGURE 6). Waiting until the puppy is older to “see if the tooth falls out” is not an appropriate treatment decision.
Potential Complications of Deciduous Canine Tooth Removal
Understanding dental anatomy, knowing the location of the permanent tooth relative to the deciduous tooth, and using proper, sharp instruments in the appropriate manner and with patience will help you remove a deciduous canine tooth and minimize risk of damaging the permanent tooth or fracturing the tooth root. The best way to avoid surgical complications is through adequate preparation, evaluating the circumstances of each case, and following a mental checklist during the procedure.8
The deciduous canine tooth is long, narrow, and thin-walled with a very long root, making it susceptible to fracture during extraction (FIGURE 7). If the root of the deciduous tooth fractures, it needs to be removed. A retained deciduous tooth root may potentially cause problems, including infection and difficulty with eruption of the permanent tooth.4 As with extraction of permanent teeth, if the root tip fractures, extend the buccal bone “window” to be able to visualize the root tip. Use a small elevator or root tip elevator to elevate the root tip through the window. Never dig blindly for root tips;8 always visualize a root tip before attempting to remove it. When elevating a deciduous tooth root tip, avoid the area of the developing tooth.
Damage to Permanent Teeth
The developing permanent canine tooth has a very thin layer of dentin, a large pulp cavity, and an open apex, which makes it susceptible to damage by improper use of the elevator or luxator during deciduous canine tooth removal. Damage to the permanent tooth may result in focal enamel hypoplasia3 (FIGURE 8), an endodontically diseased permanent tooth (FIGURE 9), structural defects, and/or relocation of the permanent tooth (FIGURE 10). Disturbances early in the process of tooth development will result in more extensive involvement and abnormality in the clinical appearance of the tooth than disturbance later in this process when certain aspects of the tooth will have already developed normally.3
When removing deciduous teeth, client education is crucial. Clients should understand that you will do everything to minimize the potential for complications but that occasionally, removal of a deciduous canine tooth may result in damage to the developing permanent tooth.
Steps for Removing Deciduous Canine Teeth in the Dog
- Administer a regional nerve block.9
- Obtain a preoperative radiograph to evaluate the deciduous tooth root structure and to document the location of the developing permanent canine tooth. If the root of the deciduous tooth is being resorbed and the tooth is mobile, you can use a closed extraction technique (no flap creation and no bone removal) (FIGURE 11). If the long, thin root of the deciduous tooth is visible radiographically, it is best to use an open extraction technique (create a flap and remove buccal bone) (FIGURE 12).
- Incise the gingival attachment around the deciduous tooth with a scalpel blade.
- For a mobile deciduous tooth, carefully use a small dental elevator to sever the remaining periodontal ligament fibers and remove the tooth.
- For a deciduous tooth that is not mobile (FIGURE 13A), consider using an open extraction technique. The open extraction technique for removing a deciduous maxillary or mandibular canine tooth is very similar. A critical difference is the need to avoid the lingual side of the deciduous mandibular canine tooth during elevation where the permanent tooth is developing.
- Begin by elevating a mucoperiosteal flap. Make an incision along the distal edge of the deciduous canine tooth (FIGURE 13B). Use a periosteal elevator to elevate the flap and expose the alveolar bone (FIGURE 13C AND 13D). Similar to permanent tooth extraction, elevation of a mucoperiosteal flap facilitates exposure.
- Carefully remove the buccal bone over the root of the deciduous tooth. This is best accomplished by using a very small periosteal elevator to elevate the soft, thin layer of buccal bone (FIGURE 14). Remove only buccal bone over the root of the deciduous tooth; do not remove buccal bone beyond the borders of the deciduous tooth. Using a periosteal elevator instead of a small round bur in a highspeed handpiece decreases the chance for iatrogenic trauma to the deciduous tooth root, which may lead to fracture, and decreases the chance of damaging the closely adjacent developing permanent tooth. As with permanent tooth extraction, removing the buccal bone facilitates extraction by creating a window through which to visualize the deciduous tooth and identify the periodontal ligament space (FIGURES 15 AND 16). Visualization is crucial!
- To sever the periodontal fibers, insert an appropriately sized small dental elevator, luxator, or periotome into the periodontal ligament space along the root of the deciduous canine tooth. Keep the elevator in the periodontal space of the deciduous tooth. Do not allow the tip of the elevator or luxator to stray in the direction of the permanent tooth root, and always use a short finger stop (FIGURE 17). Remember that the permanent tooth root with its thin layer of primary dentin and very wide pulp cavity can be easily damaged by an inappropriately placed dental instrument. Do not use the permanent tooth as a fulcrum to lever against during the extraction, and do not twist the deciduous tooth with extraction forceps; doing so can lead to root fracture. Avoid the area of the developing permanent tooth, especially if the permanent tooth is not erupted. FIGURE 17. Sever the periodontal fibers by inserting a small dental elevator or luxator into the periodontal ligament space along the root surface of the deciduous canine tooth. (A) Small dental luxator inserted into the periodontal ligament space on the distal side of the tooth.
- After cutting and breaking down the periodontal ligament, when the tooth is very mobile, use a small elevator to gently elevate the tooth out of the alveolus (FIGURE 17C). Remember that patience and slow steady pressure are key to successful extraction of any tooth, especially deciduous teeth (FIGURE 18).
- Take a postoperative radiograph to document removal of the entire deciduous tooth root (FIGURE 19).
- Remove any loose bone spicules, lavage the surgical site, and close the mucoperiosteal flap with absorbable suture material (FIGURE 20).
To prevent patient discomfort and pathology of developing permanent teeth resulting from problems with deciduous canine teeth in the dog, diagnosis and extraction of the appropriate deciduous tooth/teeth should be performed as early as possible.
Indications for extracting deciduous canine teeth are
- Fractured deciduous teeth
- Deciduous malocclusions
- Persistent deciduous teeth
Complications of deciduous canine tooth removal include fracture of the deciduous tooth root and damage to the developing permanent tooth.
To avoid fracturing the deciduous tooth root
- Use an open extraction technique if the root is visible on the intraoral radiograph.
- Carefully elevate the deciduous tooth until it is very mobile and easily removed from the alveolus with minimal effort.
- Avoid twisting the deciduous tooth with extraction forceps.
To avoid damaging the developing permanent tooth
- Obtain a preoperative radiograph to identify the location of the developing permanent tooth relative to the deciduous tooth.
- Keep the small elevator or luxator in the periodontal ligament space closely adjacent to the deciduous tooth. Do not allow the elevator or luxator to stray in the direction of the developing permanent tooth. If possible, avoid elevating on the side of the developing permanent tooth.
- Avoid levering against the developing permanent tooth.
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