Dental enamel defects in dogs

Developmental enamel defects represent not only a cosmetic alteration of the crown of teeth in dogs, but, more important, the brown-to-tan discoloration indicates that the underlying dentin may be exposed to the oral environment (Photo 1). This exposure can lead to pulpitits and death of the affected tooth or teeth. Dentin sensitivity is a concern, especially if multiple teeth are affected.

Photo 1: A developmental enamel defect in the right mandibular first molar in a dog. Note the tan-to-brown discoloration. (Photos courtesy of Dr. Brett Beckman)

Root aberrations may also occur that may require treatment (Photo 2). Dental radiography, therefore, is paramount in assessing all teeth with enamel defects, regardless of cause.

Photo 2: Concurrent alterations in the dentin formation in teeth with enamel defects may result in root abnormalities. Note the shortened and apically thin mesial root of the right mandibular first molar in this dog.

Classification

Developmental enamel defects can be categorized based on compromise of quality or quantity. Defects in quality (hypocalcification) cause a less inorganic matrix, and the resulting enamel is softer than normal enamel. It's often possible to remove hypocalcified enamel with ultrasonic scaling.1 Defects in quantity (hypoplasia) result in a much thinner than normal enamel.1 Pitting may be present in the surface. Both types of defects can be found concurrently, and differentiation is not necessary because, therapeutically, the approach is the same.

Many teeth with developmental enamel defects also will have variations in developmental root abnormalities. Roots may appear long and thin toward the apex (Photo 3,) or have blunt attenuated roots (Photo 4).

Photo 3: Thinning at the apex is present in this dog’s left mandibular canine tooth.

In addition, amelogenesis imperfecta is an inherited maturation disorder of the enamel. This condition appears to be uncommon in dogs, although standard poodles may have a genetic predisposition.2

Photo 4: Attenuation and blunting are present in this dog’s left first and second molar teeth.

Causes

Enamel formation occurs in dogs between 2 weeks and 3 months of age.3 Trauma during enamel development is a common cause of enamel defects in dogs. However, in general, a history of oral trauma is nonexistent but, occasionally, can be traced to altercations with other pets or accidental drops, falls, etc. The result is generally seen in one or several teeth in a regional distribution. A febrile event that occurred during enamel development may be responsible for cases in which most or all of the dentition is affected.

Systemic insults that may result in enamel defects include nutritional deficiencies, infection, fever, metabolic abnormalities, toxins and parasites. Distemper viral infections and other Morbillivirus species infections are classically recognized as causes of enamel hypoplasia or hypocalcification.4

Treatment

Eliminating unsound enamel while conserving tooth structure forms the groundwork for bonding dentin to eliminate oral microbe exposure and sensitivity. Ultrasonic scaling and polishing removes loosely adhered and diseased enamel.

After cleaning, odontoplasty and cavity preparation, the remaining diseased enamel should be removed, and the tooth should be prepared for bonding and restoration. Case selection should be based on the extent of the lesion or lesions. Minor, localized defects may be bonded or restored by practitioners equipped and skilled in performing minor restorations. Deep defects and widespread involvement should be referred to a veterinary dental specialist.

Generalized cases are time-consuming and should be reserved for specialists skilled and efficient in performing these procedures. Although aesthetics is not the ultimate goal of this therapy, removal of diseased enamel and restoration result in a more pleasing appearance (Photos 5 and 6).

Photo 5: Generalized enamel hypoplasia and hypocalcification in a dog before therapy.

Every tooth involved must be radiographed before restoration to determine viability, and sound root structure should be documented before proceeding. Consider endodontic repair for mild to moderately affected teeth that are nonviable but have structurally sound roots. Extraction is an alternative. Teeth with severely attenuated roots should be considered candidates for extraction to prevent endodontic and periodontal involvement.

Photo 6: Generalized enamel hypoplasia and hypocalcification in a dog after therapy.

Finally, consider prosthetic crown placement in large teeth with marked defects. Under these circumstances, I recommend crown placement on the carnassial and canine teeth (Photo 7). Not only does this protect the crown from tooth or composite breakdown, it lessens the plaque and tartar-retention capacity of the affected crown.

Photo 7: A cast metal alloy crown protects the crown of a dog’s left mandibular first molar that is affected by a developmental enamel defect.

Follow-up

Teeth with developmental enamel defects that have been restored still have plaque and tartar-retentive properties that predispose the surrounding tissue to periodontal disease. Home care and periodic cleaning in the hospital are part of the commitment to manage these patients.

Keep in mind that changes noted on radiography may be present at the time of the initial therapy, although endodontic disease may already be present. And with time, the composite breakdown may re-expose the dentin and provide a source for endodontic compromise. Therefore, radiographic evaluation every six to 18 months is indicated.

Dr. Beckman lectures internationally on veterinary dentistry and sees patients at Affiliated Veterinary Specialists, Orlando, Fla.; Florida Veterinary Dentistry and Oral Surgery, Punta Gorda, Fla.; Animal Emergency Center of Sandy Springs, Atlanta, and Dallas Veterinary Dentistry and Oral Surgery, Dallas. Find out more at veterinarydentistry.net.

References

1. Wiggs RB, Lobprise HB. Veterinary dentistry: principles and practice. Philadelphia, Pa: Lippincott-Raven Publishers, 1997;107.

2. Mannerfelt T, Lindgren I. Enamel defects in standard poodle dogs in Sweden. J Vet Dent 2009 26(4):213-215.

3. Gorrel C. Veterinary dentistry for the general practitioner. Elsevier Health Sciences, 2004;69-86.

4. Dubielzig RR, Higgins RJ, Krakowka S. Lesions of the enamel organ of developing dog teeth following experimental inoculation of gnotobiotic puppies with canine distemper virus. Vet Pathol 1981;18(5):684-689.