Are you compelled to polish every tooth? Dental researchers advise a re-evaluation of methods, materials, and modalities.
by Shirley Gutkowski, RDH, BSDH
We have identical goals — dentists and hygienists — healthy patients. Removal of the enamel by polishing is nowhere in the top 10 things to worry about during a prophy appointment. It isn't earth shattering; people don't die from it, but it isn't totally harmless. With few exceptions, hygienists are uncomfortable with the prospect of eliminating polishing from their sequence of patient care. "It is the finish," they'll argue. They like to have their patients leave with that "clean" feeling. Polishing is the final activity hygienists do to help their patients.
"Mmmm, I love to have my teeth cleaned. They feel so good," patients say, and "Ahh, the perfect end to a prophy appointment." The patients are happy; their minds are on what a good hygienist you are. Their teeth feel clean. Their teeth feel clean.
Hygienists have major occupational physical distress, including back pain, wrist pain, and loss of sensation or tingling in their hands. Patients think the polish is the reason they came to see the dentist. We're killing ourselves removing calculus, repetitively applying many hundreds of pounds of force per day removing calculus with some of the smallest muscles in the body. We're using leverage that incorporates the sternocleidomastoid, deltoids, trapezius, and latissimus dorsi muscles of the back as well as some lesser-known deep muscles. We twist, angle, and work in a dark, often bloody field. We expose ourselves and our families to infections, all so our patients can run their tongues across their teeth after we polish and say with satisfaction, "Mmmm, that feels great."
Patients' total appreciation for that feeling is overrated. Should the patient's perceived need for polished teeth override the science of polishing? Our quest for that goal is attainable in various ways. How or why we get there is the topic of this article. The science of polishing has become counterintuitive to many hygienists. Outside influences and motivators perpetuate the impulsive self-enslavement that dental hygienists have towards polishing. So ingrained is this procedure into a hygienist's every day practice, that selective polishing may never be accepted as the norm.
Economics of the hygiene appointment
Dental hygiene schools around the country teach polishing as a means to remove plaque and stain. Plaque is an infectious agent; stain is an entity with no impact on health or disease. In comparison, dental students — future dental-practice owners — are taught certain myths about polishing that eventually influence the way hygienists are expected to perform in those future dentists' practices. Prophy pastes — or abrasives, as they are taught — are used to remove acquired pellicle and stains. A 1994 textbook for dental students instructs students that fluoride in the prophylaxis paste decreases thermal sensitivity. Another textbook lists polishing as an essential procedure to periodontal therapy.
As future business owners, dental students may be reminded that patients may feel cheated if their teeth aren't polished. They may be taught that the small amount of enamel removed is inconsequential to the customer's wants and perceived needs. They are advised that the work the dentist provides looks better when stains are removed. Generally, hygienists are not as concerned about stain removal as dentists (a.k.a. business owners) are. The end goals appear to be very different: health vs. esthetics.
Not all business owners are unaware, however. Dr. Raymond Thurow, an orthodontist, founder and president emeritus of the College of Diplomates of the American Board of Orthodontists, was very much against polishing teeth. His perspective on the matter — 20 years ago — was that keeping orthodontic bands on teeth for as long as possible would protect them from the ravages of the hygienist's polishing paste.
What's in prophy paste?
Let's start with some mundane facts about polishing:
- Most prophy paste made is sold in the United States
- Most is sold in 2-gram unit-dose cups
- Generally, the ingredients are the same: pumice, feldspar, or diatomaceous earth (in some companies' fine paste formulas); glycerin; flavoring oils; binders (to hold down splattering); and fluoride.
Product characteristics and usage facts:
- One company sells more than 60 percent of all paste sold in the United States
- Abrasiveness is determined by particle size and substance — there is no standardization
- Less than 10 percent of polishing is done with air polishing units
- The FDA regulates the fluoride content and safety of prophy paste
- The most common paste sold is coarse
- Approximately 50 percent of hygienists use coarse as their primary paste
- Most dental hygiene schools teach students to use "fine" paste
- Approximately 15 percent of hygienists use fine as their primary paste
The last four pieces of information are intriguing. Hygienists are educated to use fine paste; however, the most popular paste is coarse. What happens between school and the office? Production goals for the hygiene department are heavily time-dependent. In many practices, the hygiene department is under scrutiny to get the job done quickly and efficiently. If that means rubbing off some enamel, well, so be it. And yet, it doesn't have to be that way.
One of the founding principles of a dental hygiene visit is plaque removal. Plaque removal can be attained by:
- Toothbrushing — the most time-consuming, least damaging, and most instructive of all
- Hand instruments
- Power scalers
- Fine paste used in a conventional manner with angle and cup
- Self-adjusting prophy paste
Prophy pastes generally feature grades of increasing coarseness, signifying larger and larger pieces of cooled, crushed, volcanic lava, called pumice. Some prophy pastes contain abrasives other than pumice; however, pumice is the leader by far.
The size, hardness, and shape of the abrasive particle determines the manufacturer's labeling: extra coarse, coarse, medium, fine, and extra fine. The smaller or softer the particles, the finer the paste. Larger, sharper, or harder particles do remove more stain faster than smaller particles, but at the expense of restorative materials, enamel, and, more notably, dentin.
Through the decades, different studies have shown that anywhere from one to 12 microns of enamel can be removed. The cause for concern has been that the fluoride-rich layer of enamel — the part that is most resistant to acid attack — is the top 4 microns.
The way researchers study polishes raise very interesting questions with even more interesting answers. In reading research, it's important to look at the whole picture. For example, one study measured a polishing agent at 3.5 times the load usually employed by practitioners. That change, in and of itself, is neither bad nor good. When one variable is magnified as this one is, it's safe to carry the information over to practice. What made the information useless to daily practice, however, is that the research team polished 15 times as long and only 25 percent as fast as hygienists do in normal practice!
Some researchers looked at the qualities of the polish itself vs. its stain removal qualities. As prophy paste is used, the abrasive particles break down. The larger or harder the abrasive particles are, the longer it takes and more difficult they are to break down. Some pastes never break down.
The newest paste, called "self-adjusting," uses perlite as the abrasive medium. Perlite, it was found, can start out with a particle size consistent with medium paste particles. Perlite particles are sheet-like in shape and are of volcanic glass. During clinical use, the particles become aligned and the sharp, pointed grains crush rapidly and become dull. This transformation takes seconds and converts a medium paste into a polishing compound safe for use on esthetic restorations. It is half as abrasive, or aggressive, on tooth structures as a coarse prophy paste.
Another research topic concerns the potential damage that prophy paste does to restorative dentistry. From amalgams to fancy composites, shards of lava rock and other abrasive choices erode, dull, and decrease the life of many types of dental restorations.
Microflora is another aspect of interest to researchers. Does the simple act of polishing affect the amount and quality of the bacteria residing in the mouth? Some say "yes;" others disagree.
Dental professionals speak
Dr. Esther Wilkins, author of Clinical Practice of the Dental Hygienist, sees the automatic use of abrasives during a prophylaxis as overkill and harmful to tooth structures. The outer surface of the enamel contains the greatest deposit of fluoride to protect against demineralization. Moreover, the act of polishing cementum and dentin opens the dentinal tubules increasing thermal sensitivity. Dr. Wilkins recommends only toothbrushing during the OHI portion of the hygiene appointment to remove plaque.
Dr. Wilkins points out that every pass of an instrument removes plaque. In the course of removing calculus and stain with hand and powered instruments, clinicians are disturbing bacterial colonies and removing unsightly non-pathogenic stain as well as plaque. Any roughness remaining on a tooth is likely calculus that cannot be removed by polishing. It is understood that there is a cosmetic obligation for polishing teeth. To satisfy patients, she advocates selective polishing with the finest possible paste — even over-the-counter toothpaste is a good choice.
Dr. Wilkins also muses on the inconsistency of polishing as part of a prophylaxis at no additional cost vs. topical fluoride treatments at what she considers to be shamefully high fees in some practices. Instead, dental practices should charge extra for polishing as a potentially harmful non-health-beneficial procedure, and do topical fluoride treatments routinely at no additional cost.
In tests at the CRA laboratory in Provo, Utah, Dr. Rella Christensen and her colleagues tested different abrasives in commercially available prophy pastes obtainable in the late 1980s. Her research shows less than a 1-micron loss of enamel regardless of the abrasives used. Using impressions, photography, scanning electron microscope, and assays, her team determined that whatever effect to the enamel had occurred from the abrasive was resolved in 90 days. The mild arching or semicircular pattern of erosion unique to spinning abrasives became less and less as time wore on.
Damage to dentin is another matter. The devastation to the CEJ was not isolated to the use of any abrasive in any prophy paste. Improper angulation of the prophy cup at the CEJ did enormous damage — much more so and longer lasting than the effect on enamel. The photograph of the damage looked suspiciously like an abfraction. Root surfaces remained disfigured, thus creating a niche for further plaque accumulation. Unfortunately, this damage can happen without the clinician knowing it in the sulcus. The research team surmised that the niche might not become evident until the gingiva becomes recessed.
Earlier that same decade, a study used a split-mouth design with 15 subjects to show professional polishing as statistically superior to tooth brushing. One half of the mouth was polished with zirconium silicate polish until no plaque remained as evidenced by disclosing solution. The other half of the mouth was self-brushed by the subjects using the Bass technique and zirconium silicate polish with the same goal of negative disclosing solution evidence. Then, the subjects refrained from oral self care for the three-day duration of the study. At the end of the time period, the researchers found that the polished teeth had statistically significant lower plaque scores.
That sounds good; but there's a downside. In tests to determine if incorporating stannous fluoride into pastes was helpful, the pastes with silicate and silicone as abrasives apparently blocked uptake of the stannous fluoride. The researchers surmised that the silicone in the paste formed an anti-wetting film that blocked fluoride uptake.
Inconsistency in data is difficult to handle. Since there are so many variables, it's difficult to gather similar results when testing polishes. Many textbooks, including those for dental assistants and dentists, as well as the American Dental Hygienists' Association's (ADHA) position on polishing simply state that polishing should not be done as a matter of course. Each individual tooth should be evaluated with the idea that polishing is a damaging procedure with very few positive qualities. The ADHA and textbook authors, therefore, put the decision to polish into the hands of individual clinicians.
Dental hygiene schools teach selective polishing as a means to remove extrinsic stain. Students are instructed to use their clinical judgment to select, tooth by tooth, which ones need polishing and which level of coarseness to use. This method combines the science of dental hygiene with the perceived patient want/need for cosmetic polishing. One drawback to selective polishing is that it does not address the clinicians' deep, inaccurate longing to provide quality care for the whole mouth, and not skip anything.
Anne Guignon, RDH, MPH, has developed a unique way of achieving old goals. Guignon has advanced what she calls "stealth polishing." She addresses the science of plaque removal and the patients' esthetic needs by removing plaque and stain with a tunable ultrasonic scaler. Then she addresses the patients' psychological need (OK, hers too) by using a self-adjusting polish.
Guignon selects the teeth patients know about: The facials of the upper anteriors, facials and linguals of the lower anterior teeth, and perhaps a few other selected sites. Then she polishes the selected teeth quickly and lightly using soft cups and minimal contact with the teeth using far less than the two grams of paste available in the unidose cup. The perlite in the self-adjusting paste immediately breaks down from a medium paste for stain removal to a polishing compound, resulting in improved luster of the enamel.
With "stealth polishing," patients get the physical and psychological feeling of having had their teeth polished. This method may well be the best answer to the polishing issue.
What do patients think?
Not much has been written about patients' perceptions of polishing. Clinical observations and mind reading are the two major ways dentists and dental hygienists determine patients' desires with respect to polishing.
One recent study targeted patients' ideas on skipping polishing completely. Before the hygienists began the prophys, the patients were instructed on the rationale for polishing as well as its contraindications. The presentation was five to six minutes long. Then, patients were asked if they would object to a prophylaxis that did not include polishing. The majority of newly educated patients did not object.
In an atmosphere of hurried appointments, however, it may not seem practical to engage patients in a five or six minute conversation on the cost: benefit analysis of polishing. Yet, some argue that when something is beneficial, it is imperative that hygienists take the time.
The concept of another recent survey was to compare patients' knowledge and attitudes with what dental hygienists think patients want. Twenty-two oral health care providers from an Internet discussion group responded to a request for help with a survey. The providers sent responses from over 200 patients. Each patient was asked to respond to a short list of statements before treatment was initiated. The statements were designed to prompt "yes" or "no" responses and to determine what patients knew about polishing
Eighty-one percent of the patients responding said they liked to have their teeth polished. Seventy-five percent think it is necessary. This implies that patients may say they like it, but in reality, they think they need it. If the majority of patients think it's necessary, they would likely not decline even if they hated it. Ninety-five percent of dental hygienists think patients expect it.
In-office topical fluoride
Initial studies showed that polishing was a necessary part of topical fluoride application so it could bond with the enamel by removing the surface pellicle. Pre-application polishing increases the cost of providing topical fluoride in the public health arena. To see if it really was important to polish teeth before applying fluoride, public health studies were designed to find out.
Numerous researchers concluded that brushing the teeth with a regular toothbrush and flossing was more beneficial to fluoride uptake than polishing with abrasive prophy paste. Prophy pastes with fluoride, without fluoride, and a control were compared to toothbrushing (without toothpaste!), and toothbrushing was clearly superior.
The results of numerous similar studies freed up public health dental teams to apply topical fluoride after a toothbrushing demonstration thus lowering the financial and time expenses. The findings also nudge the traditional model of dental health professionals who insist that polishing before topical fluoride application is essential.
An early study on the addition of fluoride to prophy paste supported its inclusion as a means to incorporate fluoride into the enamel. The idea was to replace the fluoride from the rich outer layer of enamel that was removed by prophy paste.
Now we know that fluoride in prophy paste is not effective as a replacement or an adjunct. Manufacturers today include it to satisfy the paradigm of dental hygienists.
Changing your own traditions
Sometimes, although information is thought through and used, time wears on it and, like the self-adjusting paste, the edges become dull. The information becomes effective in a different way. Keeping current on changes in science is time consuming but not impossible. Dental hygiene colleges, dental schools, and medical schools have mountains of information available to us.
The Internet also may be helpful. The more information available for clinicians to use, the more important it is that they get off of "auto pilot" and do what is right for their patients, not just what seems right.
All dental health care providers know that brushing and flossing are vital parts of proper oral health. Patients do not do it often enough or properly, as evidenced daily in private practice and research. The five minutes that hygienists spend polishing teeth could be much better spent on oral hygiene instructions that include disclosing solution and toothbrushing; better yet, an oral cancer screening.
For some reason, polishing is a hot button for hygienists and dentists, and making a change may require a staff meeting! Nevertheless, true selective polishing, stealth polishing, or asking patients/clients if they'd like to have their teeth polished is a first step that may be more palatable to both clinicians and patients/clients.
References available upon request.
Author's note: Clinpro™, by 3M ESPE, is a self-adjusting prophy paste.
Shirley Gutkowski, RDH, BSDH, has been a full time practicing dental hygienist in Madison, Wis., since 1986. Ms. Gutkowski is published in print and on Internet sites, and speaks to groups through Cross Links Presentations. She can be contacted at [email protected]
Here are a few more basic facts to baffle friends at your next party:
- Average polishing time per tooth surface is 4.5 seconds
- The prophy cup spins at an average speed of 2,571 rpm
- The load applied is 1.42 N. (Remember N? This is where your college chemistry courses come in handy. N is a newton. A newton is a unit of force required to move one kilogram of mass one meter per second per second. I know that explanation clears up your confusion.)
- The load is inversely related to visibility and access, which means that the harder it is to see, the shorter time and less pressure is spent polishing that tooth
- The presence of stain increases time, load, and rpm
- Enamel is nearly 20 times more resistant to abrasion than dentin
Contraindications to polishing
- Lack of extrinsic staining
- Newly erupted teeth
- Areas of demineralization
- To remove heavy plaque
- Inflamed pockets or sulci
- After perio therapy with inflammation still present
- To smooth after ultrasonic use
- Any restorative material subject to scratching: porcelain, gold, acrylics, silicates, sealants
- Patient has communicable disease
- Exposed cementum
- Patient reports sensitivity
The position paper of the ADHA can be seen in its entirety at www.ADHA.org. The paper concludes: "Polishing should not be considered a routine part of the oral prophylaxis. The licensed dental hygienist or dentist is best qualified to determine the need for polishing. The ability to judge appropriately which patients/clients should or shouldn't be polished is compromised if a practitioner is not knowledgeable. ADHA believes that licensed dental hygienists and dentists are the best qualified to perform polishing procedures."