Bonded composite restoration
6A–6D. The chief steps in bonded composite restoration on a right mandibular canine tooth in a dog. In 6A, the uncomplicated
enamel fracture is seen, and the white arrow points to the exposed dentin. Note that the pulp chamber is not exposed. In 6B,
a dentin-bonding agent is being applied to an already-acid-etched surface. In 6C, a light-activated, low viscosity composite
is being introduced to the prepared surface. In 6D, an ultraviolet light is curing the composite.
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Dental composite is a filled organic resin that closely mimics the color and strength of natural teeth. Dental composite can
be bonded to the tooth surface (enamel or dentin) to restore defects, seal dentin tubules, and protect the underlying tooth
structure. The bonding procedure involves treating the tooth with phosphoric acid to remove some of the hydroxyapatite crystals
found in enamel and dentin and then placing a bonding agent that flows into the pits left by the crystal removal, which results
in a micromechanical lock. The composite, made of a resin matrix and inorganic filler, is placed over the bonding agent, shaped,
and polymerized into its solid form. Finally, the composite can be polished (Figures 6A-6D).
Crown restoration
Crown restoration is the placement of a manufactured crown or cap over the injured and repaired tooth. Any endodontic treatment
should be performed before crown placement. A margin is cut around the tooth for the crown to sit in, and the remaining tooth
is shaped following the natural taper toward the cusp. Impressions of the tooth and the complete dentition, including a wax
registration of the occlusion, are made and submitted to a dental laboratory. The laboratory creates the new crown through
a process called the lost wax technique.
After the crown has been sent back to the clinician and evaluated, it is bonded to the tooth with resin cement. The crown
may be made of metal, ceramic, or porcelain fused on metal. Of these materials, metal is the most durable and the most commonly
used. In a study investigating the long-term results of crown therapy in dogs, 17 of 19 crowns were intact and functional
at a mean follow-up time of 32 months.15
Extraction
Although it is preferable to salvage teeth, it may not be possible because of extensive trauma, financial restrictions, or
other circumstances. Successful extraction depends on your having the proper equipment and skills.
TREATING ENAMEL FRACTURES
Enamel fractures do not expose dentin, and as enamel is essentially impermeable, the pulp should not become infected or sensitive.
Obtain dental radiographs to look for other pathology. Additionally, if an enamel fracture is present, pulpitis may occur
from the concussive trauma, so yearly radiographs are recommended. Because the enamel layer in dogs and cats is relatively
thin, true enamel fractures in these species are rare. Treatment options for enamel fractures include either bonded composite
restoration or no treatment with frequent (every six to 12 months) monitoring.
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