Posing the Polishing Question

While scaling teeth with instruments to remove calculus and other oral debris was mentioned in early Greek and Roman writings, removing dental stains by polishing the dentition with various abrasive compositions made of finely ground coral, egg shells, ginger, or salt wasn’t introduced until years later by the father of modern dentistry, Pierre Fauchard.¹ This early version of tooth polishing with prophylaxis (prophy) paste has evolved into one of today’s most widely performed dental hygiene procedures.

The widely accepted focus of polishing today is:

1. To remove bacterial plaque biofilm and extrinsic stains from the exposed tooth surface.
2. To give teeth a highly polished and esthetic appearance.²

Not unlike the procedure first developed by Fauchard, dental hygienists today use a rotating rubber cup to apply prophy pastes with varying levels of coarseness to remove stains from the tooth surface.

CHOOSING A PROPHY PASTE

Most practicing dental hygienists choose prophy pastes based on how efficiently they remove extrinsic dental stains. However, more attention should be given to the incidental damage that can be caused to the tooth surface when polishing with prophy pastes. While prophy pastes with a larger particle size, ie, coarse or medium, are very efficient in extrinsic stain removal, they can also cause the most abrasion and damage to the tooth surface. In fact, excessive abrasion scratches the enamel, resulting in a less polished appearance and, ultimately, contributing to an increased rate of exogenous stain reformation and bacterial plaque retention.³

In contrast, prophy pastes with a smaller particle size, such as those found in fine pastes, will increase tooth surface cleanliness, luster, and smoothness, making the surface more resistant to subsequent stain, plaque, and calculus formation.³ But polishing with fine prophy paste is considered by some professionals to be less efficient as the dental hygienist may have to apply more pressure and invest more time to remove the same stains than when using coarse prophylaxis pastes.

EFFICIENT EXTRINSIC STAIN REMOVAL

The factors that contribute to the overall efficiency of extrinsic stain removal from tooth surfaces include:

1. Rotations per minute (rpm) of the rubber cup polisher,
2. Prophy paste coarseness,
3. Rubber cup-to-tooth pressure or load, and
4. The time spent polishing each stained area.⁴

Unfortunately, each of these factors also contributes directly to tooth enamel and dentin damage via abrasion.
Rpm is often difficult to determine without specific equipment and there is significant inconsistency in the literature regarding recommended handpiece speed during polishing procedures. Manufacturers of disposable prophy angles recommend that their devices operate at 3,000 rpm for optimal results.⁵ Nonetheless, current literature recommends that dental hygienists should always use the lowest settings possible to reduce friction and heat when polishing teeth.⁶ In a study of rpm, time, and load used in tooth polishing, Stookey and Schemehorn demonstrated in vitro that increased abrasion of enamel and dentin is directly related to increased rpm settings.⁴

Prophy pastes range in grit abrasivity from low abrasive fine grit (2 µm) to coarse grit (5 µm), the most abrasive.⁶ According to Putt, professional polishing agents are 10 times more abrasive to dentin and 20 times more abrasive to enamel than the polishing agents found in commercial toothpastes.³ Because of this, some professionals recommend the use of toothpaste alone to polish teeth.⁷ This strategy may also be an effective method of accommodating patients who insist on polishing without causing unnecessary abrasion to their teeth.

Therefore, dental hygienists should attempt to use just enough pressure to flare the ridges of the rubber cup and only enough necessary to polish away stain.⁷

One study demonstrated that up to 4 µm of outer enamel can be removed after a single 30-second polishing with a pumice paste, with cumulative loss of tooth structure becoming evident over several years of repeated polishing.⁸ While typical polishing contact times range between 5 and 30 seconds per tooth surface, less contact time reduces friction, heat generation, and tooth surface abrasion.²

POSITION ON POLISHING

Because of the known irreversible damage associated with prophylaxis polishing, the American Dental Hygienists’ Association (ADHA) published a statement outlining its position on polishing. The ADHA makes a distinction between polishing, which makes the tooth surface smooth, and cleaning, which removes debris and extraneous matter from the teeth, and stipulates that polishing should only be performed as needed.⁹ This is an important proclamation because it requires that dental hygienists assess patients according to need for polishing, rather than polishing routinely.

Dental hygienists must apply what they learned in school regarding selective polishing and remember that polishing is actually contraindicated for a number of reasons on a variety of different surfaces such as restorations, newly erupted teeth, and sensitive tooth surfaces.⁷ This contraindication is due to the abrasive nature of polishing, which can scratch restorations and wear incompletely mineralized tooth surface from newly erupted teeth.⁷ Polishing sensitive root areas is contraindicated because abrasive polishing agents remove protective mineral layers from root surfaces, thereby exposing the ends of dentinal tubules in cementum and dentin.⁷ Dental hygienists should remember that polishing is never a substitute for calculus removal and root debridement as a means for making the tooth surfaces smooth.⁷

Because of the removal of fluoride-rich enamel and the abrasion of the tooth surface, dental hygienists must revaluate their approach to rubber cup polishing as a routine part of prophy treatment and assess which stains can be removed through scaling and which stains may require polishing with prophy paste. When polishing is indicated, suggest a fluoride treatment as a means to remineralize the enamel after polishing.¹⁰ Most important, dental hygienists should become familiar with and be able to clearly articulate the ADHA policy to their patients and provide relevant articles and other information to help them understand current standards of care and why polishing may not be indicated in their dental hygiene care.

REFERENCES

1. Ring ME. History of dental prophylaxis. J Am Dent Assoc. 1967;75:892-895.
2. Hunter EL, Biller-Karlsson IR, Featherstone MJ, Silverstone LM. The prophylaxis polish: a review of the literature. Dent Hyg. 1981;55:36-42.
3. Putt MS, Kleber CJ, Muhler JC. Enamel polish and abrasion by prophylaxis pastes. Dent Hyg. 1982:38-43.
4. Christensen RP, Bangerter VW. Determination of rpm, time, and load used in oral prophylaxis polishing in vivo. J Dent Res. 1984;63:1376-1382.
5. Hodsdon KA. What color is your DPA: here’s the “need to know” and “good to know” about why your prophy head spins. RDH Magazine. 2005;25(9):86-90.
6. Anusavice KJ. Phillips’ Science of Dental Materials. 11th ed. St Louis: Saunders; 2003:352-358.
7. Wilkins EM. Extrinsic stain removal. In: Wilkins EM, ed. Clinical Practice of the Dental Hygienist. 8th ed. New York: Lippincott, Williams, & Wilkins; 2003:603-618.
8. Gutmann ME. Extrinsic and intrinsic stains and their management. In: Darby M, Walsh MM, eds. Dental Hygiene Theory and Practice. 2nd ed. St Louis: Saunders; 2003:440-456.
9. American Dental Hygienists’ Association Position on Polishing Procedures. Available at: www.adha.org/profissues/polishingpaper.htm. Accessed May 29, 2007.
10. O’Hehir TE. The definition of polishing: science, myth, and new technology. Hygienetown. 2007;19(3):10-13.

From Dimensions of Dental Hygiene. June 2007;5(6): 20, 22-23.