Fractured tooth presents options for correction; classifications defined

When presented with a patient that has a fractured tooth, the practitioner is faced with options for care: do nothing, follow the patient with serial radiographs, place a crown on top of the fracture with or without performing root canal therapy, or extract the tooth. The decision is based on patient and client factors. This foundation article will discuss patient factors.

Photo 1: Pulpitis of a mandibular canine. Note discoloration of the crown tip which may respond to antibiotics and anti-inflammatory medication and Photo 2: Maxillary central incisor affected with pulpitis-root canal therapy is indicated.

Which part of the tooth is affected? Some fractures are limited to the enamel which require little or no therapy, others involve dentin which may or may not require endodontic care; and still other fractures expose enamel, dentin and pulp requiring endodontic care or extraction.

Pulpitis without obvious loss of tooth structure will appear as a discolored tooth. Pulpitis can be caused by direct trauma, hyperthermia from ultrasonic scaling or overly aggressive polishing. The resulting inflammation may be sufficient to cause vascular damage, hemorrhage and pulpal swelling. Since the pulp is contained within a solid unyielding chamber, the inflammatory process that is beneficial in the healing response in other body areas creates swelling leading to pulpal necrosis.

Photo 3: Worn incisor without pulpal exposure next to canine with pulpal exposure and Photo 4: Maxillary canine enamel fracture.

Treatment of choice for pulpitis is root canal therapy except for those teeth with a purple discoloration at the coronal tip. Some of these minimally affected teeth may resolve with antibacterial and anti-inflammatory medication (Photos 1, 2).

Chronic abrasion from self grooming, tennis balls or attrition from misaligned opposing teeth may result in injury to the tooth. This persistent low-grade trauma causes pulpal odontoblasts to produce tertiary dentin for repair and protection.

Worn teeth

As long as the rate of wear is gradual, reparative dentin production will keep up with loss of tooth structure without causing pulpal exposure. This appears as a shiny brown area. If the rate of wear is faster than the rate of dentin production, the pulp becomes exposed leading to irreversible pulp necrosis.

Photo 5: Near pulp exposure and Photo 6: Fractured mandibular first molar with pulpal exposure.

Probing the worn area with an explorer and radiographic examination will help evaluate the endodontic and periodontic involvement of worn teeth to see if therapy is indicated (Photo 3).

Class 1 enamel (uncomplicated) fractures occur from trauma. The dentin or pulp is not exposed in class 1 fractures. Intraoral radiographs should be taken as a baseline and to check for apical fracture. The tooth should be re-radiographed six and 12 months later for evidence of periapical pathology.

Fracture classification

Treatment of enamel fractures entails smoothing and recontouring the surface with a white stone or fine diamond bur on a water-cooled high-speed handpiece to remove sharp edges, which could cause trauma to the lips and tongue (Photo 4).

Photo 7: Periapical lucencies secondary to pulpal exposure and Photo 8: Fractured tooth treated with root canal therapy.

Class 2 (uncomplicated, near pulpal exposure) fractures extend through enamel into dentin without pulpal penetration. In class 2 fractures, bacteria have an indirect pathway to the pulp through the dentinal tubules (Photo 5, p. 1S).

Class 2b (near pulp exposure) fracture extends below the gum line. Enamel and dentin are exposed sparing the pulp.

Treatment for class 2 fractures depends on the age of the animal (younger animals have less distance between dentin and pulp), and the degree of penetration into the dentin.

If intraoral radiographs do not reveal periapical pathology and the patient is between 9 months and 6 years old, root canal therapy can be performed with predictable results. Alternatively, pulp capping with or without crown restoration can be performed with a guarded prognosis.

Photo 9: Slab fracture of the maxillary fourth premolar and Photo 10: Fractured slab removed revealing exposed pulp.

Indirect pulp capping covers exposed dentin with a layer of calcium hydroxide followed by glass ionomer cement. The tooth is restored with amalgam, acrylic composite or a cast crown.

Direct pulp capping covers the pulp (exposed with a round bur), with calcium hydroxide followed by restoration.

Class 3 (complicated) fractures penetrate enamel, dentin and the pulp chamber. The pulp usually appears as a red or brown spot on the cut surface of the fracture. When pulp is exposed, there is direct communication between the oral bacterial environment and the vascular system. The initial bacterial pulpitis eventually leads to pulpal necrosis, apical granuloma formation, periapical abscessation, pain and possible compromise of distant organs. The process may occur within a month or may be prolonged, smoldering for three to five years.

Photo 11: Radiograph of fractured central incisor root and Photo 12: Dentinal bridge formation during apexogenesis.

When exposure exists, endodontic therapy (vital pulpotomy, conventional or surgical root canal) should be performed or the tooth extracted (Photos 6, p. 1S, 7 and 8).

If the practitioner chooses to do nothing with a tooth affected with pulpal exposure, the exposed pulp will necrose eventually leading to periapical pathology and patient pain. Extraction or repair of the fractured tooth are the only sound treatment options. Leaving the tooth untreated to "watch and see what happens" is unjustifiable.

Class 3b (complicated crown and root) fractures have enamel, dentin and pulp chamber exposure with extension below the gum line.

Slab fractures occur when a slice of the crown separates from the buccal or lingual/palatal surface of a tooth. Once the fracture segment is removed and discarded, pulpal exposure may be visualized. The fracture often extends subgingivally. Slab fractures commonly occur on the buccal surface of the maxillary fourth premolar in a dog that has been chewing bones or cow hooves.

Treatment options include root canal therapy with gingival surgery to eliminate the pocket to save the tooth or extraction (Figures 9, 10).

Class 4 (root) fractures involve dentin, cementum and pulp. Root fractures are classified by the anatomic location of the fracture (coronal, middle or apical third). Coronal root fractures often present with a highly mobile crown (Figure 11).

Treatment consists of either root extraction or removal of the fractured coronal segment and root canal therapy. Fractures located in the apical third of the tooth often will heal without intervention by deposition of fibrous connective tissue and between the fragments. Teeth affected by middle third root fractures causing minimal crown mobility should be splinted to adjacent teeth for six weeks for stability. Follow-up radiographs are recommended. Coronal third fractures are usually extracted with the root, or the crown removed and root treated endodontically.

Photo 13: Radiographs show periapical bone loss secondary to chronic infection and Photo 14: After infection controlled, root canal therapy and crown restoration performed.

Age of the fracture will influence the endodontic treatment. In acute fractures, the pulp appears pink or red at the fracture surface. The pulp of a long-standing fracture will appear brown or black. Shortly after pulpal exposure, inflammation occurs less than 2 millimeters from the exposure site. Healthy pulpal tissue can be found several millimeters deeper within the pulp, which may respond to vital conservative pulp procedures.

Partial coronal pulpectomy (vital pulpotomy) is an endodontic procedure in which the vitality of the pulp is preserved and tooth maturation is allowed to continue. The procedure involves removal of a portion of the pulp in the chamber of the crown, leaving the pulp in the root undisturbed. Partial coronal pulpectomy can be performed if the fracture is less than 48 hours old in the patient older than 9 months, or less than 2 weeks in the patient younger than 9 months.

Age of the patient is also important when choosing therapy options. Teeth of patients younger than 9 months have open apices. Conventional root canal therapy is not performed on these animals because sealing the apex cannot be assured. Treatment options include partial coronal pulpectomy (vital pulpotomy) to promote apexogenesis or an apexification procedure based on the pulp health. Patients older than 9 months with pulpal exposure should be treated with conventional root canal therapy.

Consider patient's age

Apexogenesis is the desired outcome when vital pulp tissue is exposed in a young dog or cat less than 9 months old. Once the apex is closed, conventional root canal therapy can be performed (Photo 12).

Apexification is the desired result of the procedure undertaken on an immature permanent tooth where pulpal inflammation and necrosis have occurred to the point where preservation of the pulp is no longer possible. Calcium hydroxide is used to stimulate the periapical tissues to bring a bony closure to the apex. Once this has been accomplished, conventional endodontics can be performed (Photos 13, 14).