Abstract
An adult male false killer whale (Pseudorca crassidens), approximately 11 years old is presented with nearly all teeth crowns being reduced. This animal in particular has 8 and 10 teeth in each upper and lower jaw, respectively with all teeth eroding. The etiology of loss in tooth mass and dental erosion is unknown but hypothesized to be associated with frequent gastric regurgitation and perhaps an individual reduced capacity of the enamel withstand acidic fluid exposure.
False killer whales normally have large conical teeth. However, this animal was initially observed to have the tips, distal, palatal and lingual surfaces of his teeth flattened as early as July 2004. The erosion progressed very slowly at first until the first quarter of 2006 with a marked increase in the rate of erosion resulting in 30-50% of tooth mass lost. The erosion of the teeth reshaped the teeth smaller, with sharp fragile edges, and commonly a narrowed tooth cervical region, increasing the likelihood of whole tooth fractures. Concerns for continued erosion included the fracture of the teeth, exposure of the pulp, increased likelihood of infection and exacerbating dental problems of teeth and jaws and associated pain.
The treatment plan focused on maintaining the existing teeth and restoration of stable tooth structure. Tooth maintenance included daily brushing with fluoride toothpaste containing 1,500 ppm fluoride and application of fluoride gel containing 1.23 fluoride ions every two weeks to replace lost minerals from the teeth and strengthen it. Daily application of tooth mousse containing RecaldentTM CPP-ACP (Casein Phosphopeptide-Amorphous Calcium Phosphate) provided additional protection for the teeth and helped neutralize acids in the teeth. The animal was trained to voluntarily position and open its mouth for the manipulation of the teeth for easy daily application.
Direct and indirect composite resin restorations were placed. Indirect tooth restoration involved voluntary taking of impressions of the teeth from which onlays were fabricated. Direct application of resin composite was done on the areas not covered by the onlays and on some teeth in the front that did not need onlays. Glass ionomer liner/base was used for the upper rows of teeth prior to application of onlays and direct composite resin since the erosion has already reached the dentin layer and has close proximity to the pulp of the teeth. Attention to contamination of the pulp cavity and unwanted air spaces under the treatment areas addressed the concerns of encapsulation of potentially harmful bacteria and compressible air space as the animal routinely dives to 20+ meters in its holding pen. The involuntary dental procedures were done quickly at appropriate time intervals to minimize problems associated with being out of the water and controlled to allow work in the oral cavity. Therefore, choice of restorative materials prioritized minimal technique sensitivity, required shortened duration and steps in application, cured quickly and durable at the same time.
A total of eleven involuntary dental procedures were done from August 22, 2006 to February 12, 2007 to attach onlays, apply direct composite resin and glass ionomer liner/base. Of the 36 teeth affected and treated, 26 of these had a combination of indirect composite resin or onlays and direct composite resin, 15 on the upper row had glass ionomer and the rest had the direct composite resin. Six months after the first onlay application, only two minor fractures of the restorations were readily repaired. It is our collective expectation that without the restorations, most of the teeth would have been lost to erosion and dissolution, while others would have likely fractured, exposing the animal to more serious consequences of exposed pulp, associated pain and more invasive treatments.