As your dentist will tell you, the mouth is an indicator of overall health. Poor oral health is linked to heart disease and other chronic health conditions in humans and our companion animals. The finding that a portion of a wild dolphin population in Louisiana was missing most of their teeth prompted the desire to investigate the oral health of wild dolphin populations in general.
It is common practice and standard care to not only examine the mouth, but also to take radiographs (x-rays) of the majority portion of the teeth that anchor them into the jawbone and are out of view to the eye. Radiographs may help understand the reasons underlying tooth loss, determining if it was just broken off, or if it is really completely missing. For dolphin mouth x-rays, a digital film plate is inserted within a holder and placed gently into a dolphin’s mouth. A very low dose of x-rays is used with dolphins because the digital plate is very sensitive; the plate is then put through a small digital laser scanner to produce the image.
Dolphins have 76-108 teeth. They are all the same shape and they are born with their adult set of teeth. They are used to grab food only, not for chewing. Typically observed wearing down of teeth in bottlenose dolphins has even led to their name Tursiops truncatus, because their teeth seemed short or truncated compared to other toothed cetaceans. With radiography we have discovered that this typical wear does not affect the supporting bone and even teeth worn down to the gum-line remain vital and healthy. Also it is common for teeth to be broken, sometimes with the gum tissue growing over the roots of the teeth. Most of these roots stay vital and sometimes they remain dead and mildly diseased in the bone. Our radiographic findings also include pocketing around worn teeth especially in the front of the mouth. This is known as periodontal disease and is usually mild, mostly in older dolphins with less than 25% of the supporting bone affected. Occasionally the jawbone loss around teeth throughout the mouth is more severe, affecting a greater number of teeth and loss of greater than 75% of the supporting bone. It is diseased bone or a severe form of periodontal disease that is suspected to be the reason for extensive tooth loss, not normal wear and tear. This has only been confirmed by radiographs in one Sarasota Bay dolphin over the past 3 years, compared to multiple dolphins in other populations.
It will be interesting to be able to link oral disease to other health information being collected by projects on the same dolphins in order to provide a more complete health assessment of our wild dolphin populations. Another potential use for dental radiology will be to provide age information. Dental radiography is used for age determination in human forensics and archeology and I would like to extend this technique to wild dolphins. It would provide a non-invasive tool to age dolphins in health assessments, stranding events, and rehabilitation efforts. The Sarasota Bay population is an important contributor to health and age assessments since most of their life histories and ages are well-known.
This article appeared on page 19 in the December 2015 issue of Nicks n Notches.