Polishing Procedures

Dental hygienists share the responsibility of proper care and maintenance of amalgam and esthetic restorations. Clinicians must have a comprehensive knowledge of the various instruments and products that are safe to use during polishing procedures because they cause minimal damage to the surface integrity of the restoration. In my experience, the ability of the dental hygienist to identify different types of esthetic restorations in the patient’s mouth is as significant as detecting subgingival calculus or adequately measuring pocket depths with a periodontal probe.

Identifying esthetic restorations can be a challenging task because some tooth colored restorations are not easy to recognize clinically. These restorations closely resemble the natural tooth color. Dental hygienists must be able to differentiate between tooth structure and restorative materials by carefully examining the margins and outline of the tooth surface with an explorer and by relying on tactile sensitivity. Radiographs and transillumination with the mouth mirror can also aid in identifying the location of the restoration.

THE SIGNIFICANCE OF POLISHING

The purpose of polishing is to create a smoother finish on the restoration or the tooth surface.¹ Once a restoration has been placed in the mouth, recontouring, finishing, and polishing the surface are all necessary. By restoring normal contours, smoothing margins, and creating a high luster shine, the overall appearance and longevity of the restoration itself are increased.² All three procedures are key to improving and safeguarding the health of the gingival tissues and supporting structures. A smooth surface reduces the amount of adhesion so that plaque, stain, and calculus are less likely to retain in those areas. An overhang left on an interproximal surface due to excess amalgam can also be a potential site for plaque retention. This can lead to increased susceptibility to decay and periodontal disease.³

One of the goals of polishing is to produce a smooth surface on both natural tooth structure and restorative materials because less plaque and debris will accumulate on smooth surfaces.⁴ Unpolished restorations are also not as esthetically appealing as those that are smooth and have a luster-like appearance. Not only are finished and polished amalgams less prone to plaque retention, but they also have a greater resistance to the effects of corrosion and tarnish.³ Patients are often more comfortable when the surface of a permanent restoration feels smooth in their mouth. Selecting an appropriate polishing procedure is also important. Recommended pastes are those with high polish and low abrasion levels.⁵

Polishing creates an abrasion on the tooth surface or restoration to reduce scratches or smooth surfaces roughened by finishing abrasives.⁶ This abrasion process is done until the surface appears shiny. Devices used to abrade the surface are cups and points, disks, and powders. The rate of abrasion is determined by the size and hardness of the particles and how they are applied to the surface. During the polishing procedure, contamination can be prevented by changing the prophy cups or brushes in between use. This technique involves moving from more abrasive to less abrasive. Each cup should be changed and the area rinsed thoroughly before applying the next agent to further prevent abrasive particles from scratching or roughening the polished surface.

STANDARD PROTOCOLS

The armamentarium used for polishing an amalgam restoration begins with brown and green rubber cups and points with a low-speed hand piece. Each color denotes a different degree of abrasiveness. They are sometimes referred to as brownies, greenies, and super greenies.³ Brown cups and green cups are used first and are more abrasive, followed by the polishing points, which are finer. Cups are used on convex areas, such as proximal surfaces, and points are used on occlusal surfaces or concavities. Points are impregnated with polishing agents and eliminate the use of liquids and powders.⁴

When polishing an amalgam restoration, light, intermittent strokes with a fine pumice or fine silex in a slurry mix can be used but it is important not to overpolish. To avoid over-polishing, rinse and evaluate the restoration frequently.⁷ The surface should be wet to avoid dry polishing, which will produce heat on the tooth. Overheating may damage the pulp of the tooth and the amalgam surface by driving mercury from the amalgam.⁸ The least abrasive cleaning agent should be used, one that is specially formulated for polishing restorations (see Table 1). Most amalgam restorations can be polished at least 24 hours after placement. This allows sufficient time for the amalgam to set. However, the current use of high copper amalgams can be polished about 8-12 minutes after placement because they set much faster.6 The dental hygienist should discuss with the dentist which procedure is best for the patient prior to polishing the amalgam restoration.

COMPOSITE RESTORATIONS

Unlike amalgam restorations, composites are generally more esthetic in appearance but have less resistance to abrasion. The more recent types of composite materials consist of polymerized resins with glass powder fillers and an additive that gives them an opaque look.⁷ Regular prophy paste is generally not recommended for polishing most esthetic restorations, additionally, air powder polishing and ultrasonic scalers should be avoided.⁹ Most composite restorations are finished and polished at the time of placement by the dentist.⁹ Aluminum oxide-coated discs can be used on the facial surfaces from most to least abrasive to create a high luster. These tools are usually followed by the use of cups and points for polishing.⁹ Typically, polishing can be accomplished with a submicron aluminum oxide-based polishing paste applied with a soft disposable rubber cup.² However, dental hygienists should always review and follow the manufacturers suggestions regarding polishing of esthetic restorations.¹⁰

GOLD, PORCELAIN, AND AIR POLISHING

Brown and green polishing points and cups can be used on gold with the same technique as when polishing amalgam restorations. This procedure is followed by the use of polishing powders such as silex, tin oxide, or submicron aluminum oxide.

A variety of prophy pastes can be used for polishing porcelain veneers and crowns (Table 1). Polishing powders are not recommended because they set into a very hard material. It is best to use specially formulated porcelain polishing paste.

During air polishing, a combination of sodium bicarbonate, air, and water or aluminum trihydroxide at a pressure of approximately 40 psi is used to remove stains from enamel tooth surfaces. Some dental restorative materials such as cements, composite resins, and other nonmetallic materials may be removed or pitted by the use of air polishing. Therefore, caution should be used near restorations, composites, and porcelain surfaces when using this technique.⁴ Another concern is the aerosols created, which can be a source for disease transmission. Personal protective eyewear should always be worn by both clinician and patient to avoid the risk of eye damage from splatter and abrasive air particles.

IMPLANT RESTORATIONS

When preparing to polish a dental implant, the dental hygienist must know which type of instruments and products to use to avoid damaging or altering the surface integrity of the titanium of the implant abutment. A rubber cup can be used to polish the implant prosthesis with a nonabrasive paste or tin oxide. Only plastic or teflon instruments should be used.

Understanding the relevancy and benefits of finishing and polishing restorations and knowing the process required to achieve a desired result are essential for providing comprehensive care to patients. Dental hygienists are responsible for learning as much as possible about various types of materials used for polishing so that the most appropriate method and armamentarium are selected when preparing to polish an amalgam or esthetic restoration.

REFERENCES

1. Barnes CM, Covey DA, Walker MP, Johnson WW. Essential selective polishing: the maintenance of aesthetic restorations. The Journal of Practical Hygiene. 2003;12(5):18-24.
2. Hatrick CD, Eakle SW, Bird WF. Abrasion, finishing and polishing. In: Dental Materials: Clinical Applications for Dental Assistants and Dental Hygienists. St Louis: Saunders; 2003:155-165.
3. Gladwin M, Bagby M. Amalgam finishing and polishing. In: Clinical Aspects of Dental Materials Theory, Practice, and Cases. Baltimore, Md: Williams & Wilkins, 2004:300.
4. Gladwin M, Bagby M. Clinical detection and management of dental restorative materials during scaling and polishing. In: Clinical Aspects of Dental Materials Theory, Practice, and Cases. Baltimore, Md: Williams & Wilkins; 2004:185-190.
5. Gladwin M, Bagby M. Polishing materials and abrasion. In: Clinical Aspects of Dental Materials Theory, Practice, and Cases. Baltimore, Md: Williams & Wilkins; 2004:203-212.
6. Craig RG, Powers JM, Wataha JC. Finishing, polishing and cleansing materials. In: Dental Materials: Properties and Manipulation. St Louis: Mosby; 2004:110-128.
7. Gibson-Howell, JC. Care of dental restorations. In: Wilkins EM, ed. Clinical Practice of the Dental Hygienist. Baltimore, Md: Williams & Wilkins; 2005:742-756.
8. Craig RG, Powers JM, Wataha JC. Dental amalgam. In: Dental Materials: Properties and Manipulation. St Louis: Mosby; 2004:103-105.
9. Gibson-Howell JC. Care of dental restorations. In: Wilkins EM, ed. Clinical Practice of the Dental Hygienist. Baltimore, Md: Williams & Wilkins; 2005:742-756.
10. Barnes CM. Care and maintenance of aesthetic restorations. The Journal of Practical Hygiene. 2004;13(4):19-22.

From Dimensions of Dental Hygiene. June 2006;4(6): 22, 24.