The Appeal CommissionThe Workers Compensation Act of Manitoba

Background:

In addition to his compensable back injury, the worker was diagnosed at a later date with a psychological condition. On September 27, 2002, Review Office determined that this condition was not a direct result of his 1981 compensable accident and denied responsibility for any associated treatment such as medication, psychotherapy, assessments, etc.

Medical reports:

In a report dated June 27, 2005, the pain clinic physician indicated the worker had been experiencing considerable dryness in his mouth and was having concerns regarding dental problems due to dryness. He suggested to the worker that he drink as much as he could and that hopefully this would help to alleviate the problem. He outlined an extensive list of drugs that the worker was taking at that time.

A report from the worker’s dentist dated May 31, 2006, indicated that the worker was taking two drugs related to his workplace injury that produced a reduced salivary flow leading to dry mouth, and stated that the reduced salivary flow can lead to serious dental complications. He said the worker lost several teeth recently because of “rapidly advancing decay process as a result of his reduced salivary flow.” The two medications listed by the dentist were Fentenyl Duragesic Patch 75mg. and Gabapentin 300 mg.

Information obtained from the worker’s wife via e-mail correspondence dated July 11, 2006 indicated that her husband had always gone for dental treatment on a regular basis and that the worker took no medications until he hurt his back.

Another report from the dentist dated August 8, 2006, showed that the worker had been attending his office for a variety of dental procedures since 1981. He observed over the past six years an increase in the number and severity of cavities that the worker developed. When seen in hygiene, he only required one unit of scaling once per year but there were usually several teeth with extensive decay. The type of decay that the worker developed was seen in individuals with a reduced salivary flow. The dentist identified two medications in particular that he felt had contributed to the worker’s accelerated tooth decay.

On August 25, 2006, the WCB’s dental consultant stated that in his opinion, the WCB should not accept responsibility for preventive dental treatments or products. He stated that improved teeth brushing would counteract any dry mouth caused by medication.

Prior to rendering Decision No. 212/2007, Review Office sought and obtained the following information:

• A March 4, 2007 report from the treating dentist outlining the worker’s dental appointments starting in 1981 through to October 31, 2006;

• A February 2007 hand written report from the treating psychiatrist outlining a list of medications prescribed to the worker from 2001;

• On March 23, 2007, the Review Officer documented that she discussed the case with the WCB’s dental consultant. He stated that in approximately 1998, the worker appeared to have an acceleration in his treatment requirements although it was not clear as to the reasons for this.

• On March 29, 2007, the Review Officer provided a file summary pertaining to the worker’s medication usage.

• On March 26, 2007, the Review Officer asked a WCB medical advisor to review the worker’s medication usage and answer certain questions. The medical advisor conducted a literature review and provided a detailed and thorough analysis of all the medications taken by the worker, including the likelihood they caused his dry mouth. The medical advisor concluded the medications most likely to cause the worker’s dry mouth were prescribed for non-compensable conditions.

Following its review meeting, the panel requested information from the treating dentist. In his report of July 22, 2007 he stated,

“Since 1999, I would say that all his cavities were specifically related to his dry mouth condition. He was getting decay in areas where someone with hygiene as good as [the worker] would not normally get cavities. It has been well researched that there can be a marked increase in dental cavities with this condition. Saliva has a cleansing action which keeps food from sticking to the teeth and washes the food away. Saliva also clears the mouth of the acid that plaque (bacteria) make. This acid eats holes into the tooth enamel. Saliva has enzymes and antibodies which fight bacteria and infections. It acts as a buffer against the bacterial acid attacks on the tooth enamel, keeping the mouth’s pH above 5.5. Because saliva contains calcium and other minerals, it helps remineralize tooth structure throughout the day.

[the worker’s] dental hygiene practices are quite good, he only needs a minimal amount of scaling when he comes in for his cleanings. His dental hygiene practices have little relevance to his increased rate of decay due to the reduced salivary flow.” [emphasis his]

The panel also received and considered a prescription printout of the medication taken by the worker between June 1997 and June 2007.

Analysis:

To accept the worker’s appeal, we must find on a balance of probabilities that his deteriorating dental condition is causally related to the medication that was prescribed for his compensable injury. Based on the evidence before us, we are unable to make that finding.

Since his compensable injury, the worker has been prescribed multiple medications for both compensable and non-compensable reasons. The memorandum of the WCB’s PMU medical advisor and the list provided by a government pharmacare program list these medications in detail, as well as when they were prescribed. The memorandum also lists the side effects of these medications.

It is apparent from the documentation on file that many of the medications taken by the worker have dry mouth as a common side effect, while others either do not list this condition as a side effect or list it as a less common or a rare side effect.

The panel accepts what appears to be a common position between the worker’s dentist, the WCB dentist consultant, and the WCB PMU medical advisor, that dry mouth caused by medications can lead to accelerated dental decay. The panel notes that under WCB Policy 44.10.80.10 - Further Injuries Subsequent to a Compensable Injury, if the medications causing the dry mouth were prescribed as a result of the worker’s compensable injury, then the accelerated dental issues would be a compensable sequela of the injury, as it arose of the delivery of medical treatment for the injury.

The question then turns on which medications was the worker taking during the critical periods of time; which ones likely caused his dry mouth, and if so, were they prescribed for his compensable medical condition?

The panel notes that the worker was injured in 1981 and has taken a variety of medications for an extended period of time. However, as noted in the letters from the worker’s dentist, the worker experienced a significant deterioration in his teeth since 1999, and his cavities from that point on were specifically related to his dry mouth condition. The panel therefore considers the worker’s medications in 1998 and earlier to be the prime “suspects” in the causation of the worker’s dental problems, and has focused its analysis on that period of time.

In this regard, the panel was greatly assisted by the list of medications provided by the Manitoba Health, Provincial Drug Program. The panel notes that the following medications were taken by the worker from mid-1997 to the end of 1998, (with information in brackets describing whether the medication is related to compensable or non-compensable conditions, and the literature position on frequency of dry mouth as a side effect of that particular medication):

• Oxycodan, Demerol, Oxycontin (compensable, each prescribed once, “not one of the most common side effects”)
• Tylenol 3 (compensable, prescribed in August 1997, then May 1998 and forward, “not one of the most common side effects”)
• Amitryptiline (non-compensable, taken for 7 years, “exhibits strong anticholinergic activity…The more common adverse reactions involve anticholinergic effects such as dry mouth…”

In reviewing this list, we note that the medication most likely to cause a dry mouth condition and subsequent dental treatment is amitryptiline, which the worker took for a non-compensable condition. The worker was on this medication for approximately seven years, until the end of 1998 when he switched to other medications that also show similar side effects.

While the listed medications in 1997 and 1998 show varying degrees of side effects related to dry mouth, the test before us is based on a balance of probabilities. In other words, what medication is more likely than not to cause dry mouth. Based on the evidence before us, we find that the non-compensable medication, amitriptyline, more likely than not caused the worker’s dry mouth condition; it had been used for some considerable period of time, and is described as having dry mouth as its most common side effect. We therefore find that this particular drug is most likely to have created the environment in the worker’s mouth, over a period of time, leading to an accelerated dental decay and the consequent need for more dental work in 1999 and beyond.

The panel notes that the worker’s treating dentist identified two specific medications as the cause of the worker’s accelerated tooth decay in 1999: Fentenyl Patch and Gabapentin. The panel notes, however, that the Fentenyl is a Duragesic patch first prescribed in 2000, well after the documented acceleration in dental treatment in 1999. In the case of Gabapentin, it was first prescribed in 2001.