Factors in Coronal Polishing
Evidence-based research prompts new approaches to a standard procedure
Coronal polishing is a procedure used to remove stain and plaque from the enamel surfaces of the teeth, after the removal of hard deposits such as calculus from the tooth surfaces.1 This process requires the use of a dental handpiece, a polishing agent, and a rubber cup/brush.2
For many years, coronal polishing had been in the hands of the dental hygienists or dentists, but recently many states have allowed dental assistants who have had the required training to perform this procedure. At the time of publication, 43 states allowed dental assistants to perform coronal polishing, and more states may be changing their practice acts to include dental assistants.3
The Dental Assisting National Board (DANB) testing center is offering a new Certified Preventive Functions Dental Assistant Certification (CPFDA certification), which includes coronal polishing. The test includes four components: coronal polishing, sealants, topical fluoride, and topical anesthetic. These procedures may be performed by the registered or expanded function dental assistant. Dental auxiliaries should refer to their state’s dental practice act or rules to determine if one or more of the procedures may be performed by dental assistants, and what the requirements are.4
Fundamentals of Coronal Polishing
Coronal polishing produces a smooth surface on the tooth, whereby the dental plaque, extrinsic stain, and calculus adherence on the tooth surface is reduced.5 The major benefit of coronal polishing is the removal of unsightly extrinsic stains from the external surface of the tooth. Extrinsic stains, which develop on the outside of the tooth structure, are caused by substances such as tobacco, coffee, tea, red wine, certain drugs, chromogenic bacteria, and metallic materials. These stains are categorized by color, such as black line stain, green stain, gray green stain, and orange stain. They directly attach to the surface of the tooth by adhering to the acquired pellicle, and can be embedded within the calculus and plaque.6
Plaque (dental biofilm) is a soft deposit formed in layers from microorganisms that build upon the tooth structure in a continuous cycle of development. Research has determined that even after the biofilm is removed through tooth brushing and flossing, plaque will begin to develop within 24 hours. There are several stages to plaque formation. The acquired pellicle, consisting of protein and glycoproteins, attaches to the tooth surface within several minutes following biofilm removal. Bacteria that are present in the oral cavity and saliva will then incorporate into the plaque. As plaque continues to develop and mature, its microbiologic composition changes from Gram-positive to a Gram-negative substance. As components in saliva are brought in contact with the plaque biofilm, it begins to mineralize and calcify. Calculus is then formed, developing from the deposition of mineral salts in the plaque. The removal of calculus and stain can be effectively accomplished by the use of hand instrumentation and an ultrasonic during the recall appointment, before using polishing agents.1
Polishing agents include prophylactic pastes specifically designed to be used on the surface of the tooth. Abrasives, binders, humectants, water, colorings, and fluoride are incorporated into the pastes, each with a specific role. The most common abrasive agents are silex (silicon dioxide) and pumice. Only superfine silex should be used for stain removal from enamel. Prophy pastes are composed of 50% to 60% abrasive particles. Humectants such as glycerin and sorbitol are used as moisture retainers and stabilizers, constituting approximately 20% to 25% of the mixture. Binders prevent separation of the mixture and splatter, examples include agar and sodium silicate powder, at 1.5% to 2.0%. Artificial sweeteners are used to prevent caries formation, and flavoring and coloring agents are incorporated in low amounts. Fluoride pastes are also used, but research has shown both minimal and moderate caries preventive effects.1
It is important to remember that no one type of polishing agent is intended for every tooth surface, and it should not be used on restorative materials that are softer than the abrasive agent. When polishing restorative materials, dental assistants should use a prophylactic paste that is specifically designed for restorations. The most common materials used for esthetic restoration are porcelains, composites, and glass-ionomer cements. Porcelain is a very translucent material used for crowns and veneers, but it is also very brittle and subject to fracturing, causing excessive wear on the opposing tooth structure. The most widely used restorative materials are composites, comprising several different types. Due to their low Mohs hardness ranking, they are more susceptible to damage by prophylaxis polishing pastes (which are 10 times rougher than the composite material). This damage causes the restoration to be much more likely to harbor bacteria. Most manufacturers of composite restorative materials have their own polishing product that can be used on their composite materials. Glass-ionomers are subject to cracking and premature deterioration of the restoration, and therefore polishing products specifically designed by the manufacturer should be used. Additionally, restorations may be lubricated prior to polishing with petroleum jelly or water.7
Patients may view coronal polishing as an integral part of the prophylaxis appointment and therefore essential to patient satisfaction. Polishing provides some patients with an improved esthetic appearance, and they are convinced that their teeth have been thoroughly cleaned. Wanting to satisfy patients, dental professionals have continued this procedure as part of every recall appointment.1 This expectation may cause a conflict between the provider and patient, and dental auxiliaries should be aware of this issue.
Coronal Polishing Decisions
While wanting to meet the expectations of their patients, oral healthcare practitioners are fundamentally concerned with providing current evidence-based procedures for biofilm and stain removal. Recent research has prompted discussion about the value of coronal polishing after a dental prophylaxis. Today, polishing decisions are being revised based upon information that is replacing the concept of rubber-cup coronal polishing as the standard of every prophylactic appointment.3
Research has shown that polishing for 30 seconds with a prophylactic paste that contains pumice can remove between 0.6 μm and 4 μm of the outer surface of the enamel, which includes the fluoride-rich layer. When this fluoride layer is removed, the tooth is exposed to many destructive forces, which may cause permanent damage. Polishing over demineralized areas will result in three times more surface enamel being removed than intact enamel. During polishing with a prophylactic angle and paste, materials incorporated into the pastes can cause scratching on the enamel surface, which then becomes a reservoir for harboring bacteria.1
Factors that will affect abrading the tooth surface during polishing include pressure, speed, quality of paste, and shape, size, and hardness of the abrasive particles. Cleaning and polishing abrasive agents incorporated into the prophylaxis paste contain different shapes and edges that scratch the surface of the enamel. The grit or size is the main factor.
Cleaning agents do not contain abrasive agents; they use naturally occurring agents that do not abrade the surface characterization of tooth structures or esthetic restorations. On the other hand, polishing agents contain abrasive particles. Using a coarse abrasive polishing agent with large particle size leaves deep irregular scratches in the surface of the enamel. Using fine grit pastes will leave fine scratches. Therefore, utilizing a medium grit paste followed by a fine grit paste will leave the smoothest surface. Additionally, to prevent the transfer of different grit sizes onto the enamel, the prophy cup must be changed between the different paste applications during the procedure, or otherwise the rubber cup or brush can potentially harbor the coarser grits and achieving the desired results will present greater difficulty.1
A study on the effects of polishing on the enamel surface of the teeth, conducted at the University of San Paulo, School of Dentistry, demonstrated the need for eliminating rough surfaces on the teeth, which create a risk for increased accumulated of biofilm, calculus, and exogenous stain.8 Additionally, recent literature has shown that thorough tooth brushing and flossing produced the same effect as polishing, without damage to the tooth surface.9
Dental auxiliaries must be knowledgeable about contraindications and cautions to coronal polishing. By doing a complete medical history review of each patient and recording in the treatment plan which areas of the teeth are to be polished, adverse treatment can be avoided. Factors that may be controlled by the practitioner include the speed and pressure of the electronic handpiece: a light pressure and slower speed will reduce the abrading effects of polishing.2
Contraindications for polishing include6:
• No extrinsic stain present
• Exposed root surfaces
• Newly erupted teeth
• Patient sensitivity
• Inflamed or bleeding gingival tissue
• Respiratory problems
• Allergic reaction to pastes
For dental assistants this is an exciting time, as they take on new areas of patient care. Being knowledgeable and aware of the latest developments in evidence-based research helps them to convey these findings to their patients. Should some patients insist on having a polishing procedure although there is no visible extrinsic stain present, a cleaning agent should be used. This contains the least abrasive agents and is the best alternative to a polishing agent. Auxiliaries should record polishing in the dental treatment plan, along with which type of paste is recommended and the patient’s preferences.
1. Wilkins EM. Extrinsic stain removal. In: Wilkins EM, ed . Clinical Practice of the Dental Hygienist. 8th ed. Philadelphia: Lippincott William and Wilkins; 1999:603-611.
2. Barnes CM. Protocol for polishing. Dimensions of Dental Hygiene. 2004;2(6):26-32.
3. Horlak DJ, Lyon LJ, Watson PD. Critically thinking about coronal polishing. Inside Dental Assisting. July 26, 2009. Accessed January 21, 2011.
4. Dental Assisting National Board. 2011 Exam Application, Certified Preventive Dental Assistant Certification. Dental Assisting National Board web site. http://www.danb.org. Accessed May 22, 2011.
5. Schroeder-Drucks C. Selective polishing. Inside Dental Assisting. November/December 2009. http://www.dentalaegis.com/ida/2009/12/selective-polishing. Accessed May 11, 2011.
6. Francis B, Barnes CM. Cosmetic and therapeutic polishing. In: Harfst DS, Wilder R, eds. Mosby’s Dental Hygiene Concepts, Cases and Competencies. 2nd ed. St. Louis, Missouri: Elsevier; 2008: 600-622.
7. Barnes CM. Polishing esthetic restorative materials; the successful maintenance of esthetic restorations. Dimensions of Dental Hygiene. January 2010. http://www.dimensionsofdentalhygiene.com/ddhright.aspx?id=6894. Accessed May 11, 2011.
8. Salami D, Luz MA. Effect of prophylactic treatments on the superficial roughness of dental tissues and of two esthetic restorative materials. Pesqui Odontol Bras. 2003:17(1):63-68.
9. Position on polishing. American Dental Hygienists’ Association web site. http://www.adha.org/profissue/polishingpaper.htm. Accessed February 2, 2010.
About the Authors
Lois Dondiego, BASDH, RDH, CDAInstructor
University of Medicine & Dentistry of New Jersey
Scotch Plains, New Jersey
Karen Finnerty, BA, CDA, RDH
University of Medicine & Dentistry of New Jersey
Scotch Plains, New Jersey