Summer's here, the mercury's rising and a hot topic remains on the lips - and in patients' teeth*

So which is it? Leave the old fillings in place, or have your dentist do a wholesale makeover to tooth-colored restorations? The ADA's position is quite clear:

"removal of amalgam restorations from the non-allergic patient for the alleged purpose of removing toxic substances from the body, when such treatment is performed solely at the recommendation or suggestion of the dentist, is improper and unethical."

The above statement does not preclude taking precautions against acute mercury exposure...which is highest when old silver fillings are removed. When this occurs, dentists should make certain treatment rooms are well ventilated, that the teeth are isolated with rubber dams, and that dental assistants use high-powered evacuation systems to remove the vapors. Of late, many replacement fillings are tooth-colored composite resins, porcelain inlays, ceramo-metal crowns, or gold restorations...none of which contain mercury. Non-mercury amalgams are now available as inexpensive, suitable restorations.

Explaining the ADA's official posture, plus the fact that scientists have never been able to link mercury in dental fillings to any diseases, still does not ease many patients' concerns. "But they're ugly," they say, "I want my teeth to look white." That's a different story! As long as the patient is informed that their fillings are not falsely being removed for health reasons and that good mercury-hygiene measures are followed, changing silver fillings to more cosmetic restorations has our blessings.

*Harvard Health Letter, The Silver in Them Thar Molars 25:#5,1-3, 2000.

Decisions! Decisions! Decisions!

You've been informed you have gum disease and want help, but what's the best treatment for you? Suggestions abound. Friends and neighbors tell you one thing, your dentist something else. A periodontist is consulted and a treatment plan is presented to you. The dreaded "S" word - surgery - is uttered. Do you listen to your dentist and specialist and schedule that appointment? Or, do you think it over? Get a second opinion? Perhaps you challenge the doctor, "Surgery? Is that your final answer?" Perhaps the better questions are, "How successful will this treatment be?" "Are there any options?"

What we're talking about here is PROGNOSIS. Imagine a patient's confusion when he/she hears, "In my hands," or "I've been doing this for 25 years," or "Dentistry is more art than science." The trouble with those answers is that most patients were hoping to get Dr. DeBakey and not Vincent Van Gogh for a surgeon.

Let's look back at our therapeutic roots (no pun intended). Generations of dentists and periodontists were trained that plaque is the basis for adult gum disease, that all plaques were the same, and that every person was at risk for gum disease. Once initiated, it was a matter of time before the periodontal disease progressed. Some thought this disease process progressed in a linear fashion...like one big downhill slide to tooth loss. Based on the above assumptions, treatment modalities were developed years ago...and perpetuated to this day.

While medicine is becoming more evidence based, dentistry lags far behind in applying specific treatments to meaningful and predictable outcomes. Historically, greater focus has been placed on periodontal risk factors than on those factors that deal with prognosis. The difference is clear: risk factors contribute to how the disease develops; prognosis factors deal with what will happen once the disease is established in a person.

Here are some concrete examples. Let's consider bleeding gums, plaque accumulation, and malposed teeth. Each is associated with the onset of periodontal problems in one way or another, but their continued presence may not automatically lead to a downward spiral ending in tooth loss. Why? Because a host of modifiers exist that can alter an individual patient's response to the plaque found in their mouths. For starters, medical status, age, oral hygiene compliance, stress, quality of existing dental restorations, and genetic predisposition all influence the patient's susceptibility to progressive periodontal disease

Dr. Michael K. McGuire* studied the above factors, and more, to learn how best to predict a tooth's outcome. He learned after studying over 2500 teeth for 8 years (during which 5.2% were lost) that certain factors were clinically more important than others when trying to determine a tooth's fate. He found the following: "increasing probing depth, furcation involvement, mobility, percent of bone loss, having a parafunctional habit and not wearing a biteguard, and smoking, resulted in increased risk of tooth loss." Furthermore, when he adjusted for all other variables, the risk for tooth loss doubled when teeth became looser and the patient did not wear their biteguard to help reduce the stresses caused by parafunctional habits. Continued smoking also doubled the risk of tooth loss.

Dr. McGuire went on to study the genetic inheritance that seemed to make certain patients more vulnerable to periodontal disease. He tested a subset of his large group - 42 Caucasian patients - to determine to what extent genetic polymorphisms contributed to their tooth loss. In other words, did one's periodontal genetic "heritage" contribute to future periodontal problems? Skipping to the punch line, his answer was a definite, "Yes." Dr. McGuire found that patients who had a genetic marker for periodontal disease were 2.9 times more likely to lose teeth than those that didn't have this marker. (In his study, 38% of the 42 patients had the marker). Worse yet, smokers who tested positive for the marker increased their likelihood of tooth loss to 7.7 times. In other words, genotype and smoking were better predictors of future periodontal risk than plaque, calculus, and crooked teeth.

How should we use this information? Treatment plans should render predictable results. Patients with loose teeth should wear biteguards. Parafunctional habits (like grinding and bruxing) should be moderated. Smoking should be discouraged in the strongest terms. When significant periodontal problems exist in young patients (under the age of 40), definitive treatment plans will benefit them most, especially if their parents experienced extensive dental problems and significant tooth loss.

* McGuire M.K.: Prognosis vs. Outcome: Predicting Tooth Survival. Compendium 21:217-228, 2000.

More decisions More confusion!

We're on a roll, so let's keep periodontal treatment on the analyst's couch with this next article, too. Eliminating factors that contribute to periodontal disease has always been a valued goal. This is especially difficult to accomplish for molars and may help explain why molars are known to be the first teeth lost (in most studies) as a result of periodontal disease.

Why are molars so tough to treat? For starters, they're in the back of the mouth where many patients develop ten thumbs when trying to use dental floss. They are multi-rooted with lots of concavities and places for the bacteria to hide. All studies show that single-rooted teeth are easier to clean and maintain, and consequently last longer. (Let's not forget they're closer to the front of the mouth, too).

But what about those multi-rooted molars? When pockets extend into the juncture where the roots diverge from the clinical crown (mandibular molars usually have two roots and maxillary molars usually have three), the area - known as a furcation - is susceptible to plaque accumulation. It's difficult to clean. To that end, what "predictable" treatments should be considered when pockets and bone loss reach molar furcations?

Drs. Svärdström and Wennström tried to answer these questions. They studied 1,313 molars in 222 patients, analyzing treatment decisions when bone loss occurred in molar furcations. Of the original patients in the study, 162 agreed to be studied 8-12 years after the active phase of treatment had been completed.

Many factors went into analyzing how best to treat a molar with a furcation problem. In addition to the depth of the pocket, they considered tooth mobility, tooth position, and lack of an occlusal antagonist. Teeth with shallow furcation problems were maintained with scaling and not surgery. Deeper furcation defects were treated via regenerative procedures (bone grafts), root resection/separation (removing a particularly bad root but leaving the rest of the tooth), tunnel preparations (widening the furcation for easier cleaning access), or by extraction. It is important to note that the authors extracted 28% of the molars, while 68% were treated non-surgically with scaling and root planing (including furcal odontoplasty (tooth reshaping with a bur). They acknowledged that the deeper the furcation problem, the more likely they were to extract the tooth.

Other factors went into their decision process such as tooth mobility, root morphology, endodontic condition of the tooth, tooth position, and occlusal contact, not to mention the patient's age, and their functional and esthetic demands. They also considered the patient's economic situation. Of all these factors tooth mobility was found to have the greatest influence on deciding if a tooth should be extracted.

Following their criteria for treating the molars, the authors discovered that 96% of the molars subjected to non-surgical scaling and root planing were still in function after ten years. Eighty-nine percent of resected molars and those with separated roots remained in function at the 10-year follow-up mark.

So what are Drs. Svärdström and Wennström trying to say? That they have a handle on predicting which treatments should be applied to molars with bone loss into their furcations? The article would lead you to believe that; to some extent they do. However, their mean patient age was 44.9 years, ranging from 14-73 years. In light of McGuire's preceding article, two observations need to be made. Firstly, the factors that McGuire ascribes as being most important - genetic markers and smoking - were not considered in this study. Secondly, they extracted 28% of the problems in the beginning of the study. Were all these teeth loose? By eliminating a preponderance of disease, the authors left their patients with healthier dentitions. The greater challenge would have been to treat all the "hopeless" teeth and see which ones lasted. From our vantage point, maintaining healthier teeth does not pose the same clinical challenge, and their treatment outcomes must be viewed with care.

Svärdström G. and Wennström J.L.: Periodontal Treatment Decisions for Molars: An Analysis of Influencing Factors and Long-Term Outcome. J Perio 71:579585, 2000.

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