Inside Dental Assisting
Cindy Schroeder-Drucks, MA, RDH, CDA
During patient care, as part of preventive procedures, the appointment usually ends with a handpiece, a rubber cup, and prophylactic paste being used to remove bacterial biofilm and stain from the tooth surface. As dental auxiliaries, we learned the term selective polishing and that, as part of patient care, it should be practiced. Upon certification, do we practice it?
Dental biofilm (plaque) consists of microorganisms that form in layers. Acquired pellicle, rich in proteins and glycoproteins, forms on tooth surfaces and restorations within minutes after biofilm removal.1 Biofilm forms and bacteria proceed from gram-positive to gram-negative bacteria, which are associated with bacteria remaining on tooth surfaces and restorations for longer periods of time.2 As calculus forms (mineralized biofilm), its removal along with stain can be accomplished effectively with hand instrumentation or ultrasonics.2 Selective polishing refers to polishing only those patients who present a need.2
Polishing procedures should be performed on the enamel surface as part of the dental care plan only if stain is present and cannot be removed with instrumentation. During coronal polishing, the dental auxiliary can select specific teeth to be polished using a prophylactic angle and rubber cup with a fine paste, and can brush the remaining teeth with a toothbrush to remove bacterial biofilm on tooth surfaces.
According to the American Academy of Periodontology3 and other sources,4 polishing for approximately 30 seconds with a prophylactic paste containing pumice can remove between 0.6 µm and 4 µm of the outer enamel. The outer surface of the enamel contains a natural component of fluoride, with the highest amount of fluoride concentrated on its surface. When using a prophylactic angle with a prophylactic cup on this enamel- rich surface, the dental assistant may not only remove the fluoride layer, but also introduce a rough surface and/or scratches on the tooth surface, which can contribute to the further harboring of bacteria on these surfaces.5
Prophylactic paste contains abrasive material that can harm the enamel surface. The particles within the paste contain irregular shapes with sharp edges, which can affect the surface of the enamel by introducing irregularities. The particle size (grit) of pastes is also the main culprit in removing the fluoride-rich layer of the enamel.2 The larger the grit, the more abrasive the paste is to the teeth; therefore, assistants should seek a fine paste with minimal abrasiveness when paste is necessary.
The pressure and speed of application of the handpiece must also be taken into consideration. The greater the speed and heavier the pressure placed on the handpiece, the greater threat of damage to the enamel and gingiva, which can cause further patient discomfort.6
A study administered at the University of São Paulo, School of Dentistry aimed to illustrate the effects of polishing on enamel surfaces. The study highlighted the concern of creating rough surfaces on the teeth, which increases the risk of the surface harboring biofilm, calculus, and exogenous stain.7
Three groups of extracted third molars were used in the assessment. The extracted molars were subjected to three types of prophylactic treatment: sodium bicarbonate, pumice paste, and whitening paste. Water–powder ratios and rinsing with water after treatment was standardized for all techniques to eliminate bias. Surfaces were examined using a scanning electron microscope. The results revealed that the teeth treated with only pumice paste had rougher surfaces on the cementum and dentin than the teeth treated with the other treatments (sodium bicarbonate or whitening paste). The study also concluded that the enamel surfaces exposed to treatment with the whitening paste and sodium bicarbonate still resulted in roughness but had a smoother surface than those in the control group and those exposed to prophylactic paste.
In another study, when there was a loss of fluoride to the enamel-rich layer, a prophylactic paste containing sodium fluoride was administered, which resulted in a slight increase of fluoride concentration in the enamel surface than when a nonfluoride paste was used.8 In addition, the study showed that when a topical fluoride treatment was applied immediately after polishing with a rubber cup, it was beneficial to participants.
In addition to practicing selective polishing, dental auxiliaries should also consider any contraindications to rubber-cup polishing as it relates to patient care. Contraindications include no staining, rampant caries, thin enamel and demineralization, and patients who are undergoing radiation therapy and/or exhibiting xerostomia. In addition, contraindications also may include respiratory difficulties, such as asthma and emphysema, newly erupted teeth, and restorations. If restorations require polishing, a prophylactic paste designed for restorations should be used.2
On the other hand, if the need arises to polish with a rubber cup and/or patients insist on having this procedure, use a cleaning agent rather than prophylactic paste because these agents do not contain harsh abrasives.9 When indications for a dental prophylaxis including a rubber-cup polish exist, the American Academy of Pediatric Dentistry recommends using the least abrasive paste with light pressure followed by a topical fluoride treatment.3 In addition, assistants should operate a handpiece during a polishing procedure at a speed no greater than 3,000 rpm10 and average approximately 2,500 rpm. By implementing a selective polishing protocol into patient care and following it with careful consideration, rubber-cup polishing can be accomplished without causing harm. Using a cleaning agent or a polishing paste with minimal abrasiveness can not only clean the tooth surface more efficiently, but also result in a smooth tooth surface. These results can decrease the chance of plaque, calculus, and stain adhering to the surface.11
In addition, a study designed to evaluate root curvature of extracted teeth and compare curvature before and after mechanical instrumentation concluded that while instrumentation caused a change in curvature of the root, polishing did not modify root convexity but did alter the enamel surface.12
By practicing selective polishing during patient care, assistants treat patients based on scientific knowledge. Many states are incorporating coronal polishing into functions that dental assistants can perform. Educating patients on selective polishing goes hand in hand with practicing the procedure. After thorough explanation to patients, some patients still may insist on having the polishing procedure. In these cases, use a cleaning agent or a low-abrasive paste followed by a fluoride treatment.6 If the need arises to polish restorations, use a cleaning agent designed specifically for the type of restorations present. Dental auxiliaries must use good judgment when considering coronal polishing and practice preventive procedures as the standard of care, which means that treatment must be individualized. Patients may not be aware of the effects of rubber-cup polishing on the enamel, so it is the job of the dental assistant to educate patients on the philosophy of polishing based solely on need.
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About the Author
Cindy Schroeder-Drucks, MA, RDH, CDA
University of Medicine and Dentistry of New Jersey
School of Health-Related Professions
Department of Allied Dental Education
Newark, New Jersey