The hidden iceburg: Dental Disease

We just recently had an interesting case that brought home to me how important dental radiographs are when doing a proper dental cleaning.  Tao is a 12 year old Retriever mix with numerous problems.  She has many problems including epilepsy and blindness which made her person hesitate to do anesthesia.  Yes she had really bad breath, but her teeth really didn't look all that bad.

As you can see the back teeth (premolars and molars) are somewhat covered in calculus, but the gums aren't red and bleeding and there is no obvious major disease.  Because her gums are pigmented (black in color) it makes detecting gingivitis more difficult.  In Tao's case instead of the gums receding back they became inflamed and thickened, but it isn't very obvious to the casual glance. 
Once Tao was under anesthesia we took some radiographs and found some major periodontal disease.  There were many teeth where the bone was eaten away by infection and I was able to pull several teeth, some with 3 roots, without having to section them.  (Normally you have to cut the teeth apart and pull each root separately).
Below is a radiograph of a normal adult molar (right) and premolar (left).  The red arrow points to the crown of the tooth.  The blue arrow points to the root tip.  The yellow arrow points to the pulp cavity and the green arrow points to the think dark line going around the root tip.  This is the periodontal ligament.  Both of these teeth have two roots and notice how there is bone (the mottled white material) all the way up to where the roots join at the top.  The line around the roots is thin and uniform.

Now here is a radiograph of the same teeth on Tao.  Notice the yellow arrow points to where the bone should be up to.  The black is air on an radiograph.  The bone on this premolar has been eaten away. This was one of the teeth I was able to remove without cutting.

 This next radiograph is of the maxillary teeth (upper) right behind the canines.  The blue arrows are pointing to the edge or a root abscess.  If you notice the area around the tooth is a darker grey than the rest of the bone.  There is no longer ANY bone around this tooth.  It has been completely eaten away.  The green and red arrows point to defects in the actual teeth.  The roots on these two teeth have actually been "eaten through" (darker areas) by bacteria.  Compare them to the radiograph of the normal teeth above.

Once we were done poor Tao was left with only 15 teeth in her mouth.  We had to remove all 26 molars and premolars and one incisor. Adult dogs have 42 teeth.  Adult cats have 30.

 That being said her breath was instantly better and her mouth probably hurt less than before and within a few days she should be feeling so much better.  Since her teeth were already so bad she probably wasn't chewing on anything, including her food so she won't miss the teeth.