Biofilm Management Technology: Air Polishing a Safe, Effective Modality

Due to their stickiness and ability to multiply on surfaces, biofilms are highly resistant to both the host's defense system and traditional antimicrobials. As a result, the study and understanding of biofilm and resulting management technology have come a long way with novel methods to combat the formation and accumulation of bacterial biofilms on teeth and oral surfaces. Over the years, significant advancements have greatly improved the prevention and treatment of oral diseases caused by biofilms.

In dentistry, scaling and root planing (SRP) is universally accepted as the "gold standard" procedure for periodontal treatment.² The procedure involves two parts: the removal of plaque, calculus, and bacterial biofilm from the teeth surfaces and roots, followed by the smoothing and decontamination of root surfaces. Currently available methods for supra- and subgingival biofilm removal include the use of hand instruments, such as manual, sonic, and ultrasonic scalers, and air-powder procedures.

The earliest ultrasonic scaling devices, first introduced in the 1950s, used magnetostrictive technology, which produced high-frequency vibrations that caused the instrument tip to move in an elliptical pattern.³ In the 1980s, piezoelectric ultrasonic devices were introduced, using a ceramic crystal to produce ultrasonic vibrations. The emergence of thinner, probe-like ultrasonic tips facilitated efficient supra- and subgingival biofilm removal. Offering greater precision and control, this technology has been widely adopted in dental practices globally.

Air-powder polishing arrived in the 1970s as a method for removing surface stains from teeth. Early air-polishing devices used sodium bicarbonate powder, which could cause damage to tooth enamel and soft tissues if not used carefully. In the 1990s, newer air-polishing devices using less-abrasive powders, such as glycine or erythritol, became commonplace, reducing the risk of damage and improving overall patient comfort.

Ultrasonic scaling and air-powder polishing have significantly advanced in sophistication. Newer ultrasonic devices, for instance, can selectively remove calculus while preserving healthy tooth structure, eliminating the need for more invasive procedures. Air-polishing devices have also become more precise and effective, with the ability to remove biofilms and surface stains while minimizing damage to surrounding tissues.

In recent years, a shift has occurred toward air-polishing devices as an attractive alternative to traditional manual and ultrasonic scalers.⁴ Compressed air containing water and abrasive powder particles like glycine, trehalose, erythritol, and sodium bicarbonate are sprayed onto the tooth surface using an air-polishing device, removing biofilm in less time and improving patient comfort. Characteristics of air polishing include the following:

Mechanism of action: The high-pressure air stream, combining pressurized air, water, and low-abrasive powders to remove biofilm, helps to break up biofilm and dislodge it from the tooth surface. Water helps to wash away the dislodged fragments, while the fine powder particles physically scrub the remaining debris. This mechanism of action makes air powder highly effective in removing biofilm.

Accessibility: Air powder can reach areas that are difficult to access with traditional debridement methods like hand scaling. The fine powder particles penetrate deep into the crevices and grooves of teeth and gingiva, removing biofilm in hard-to-reach areas.

Speed: This modality is efficient and completed in minutes, making it much faster than traditional debridement methods.⁵

Comfort: As a gentle and non-invasive biofilm removal method, air polishing typically does not cause discomfort or pain. The speed of completion also makes it a more comfortable experience for patients.

Less-Abrasive Powders: Glycine and Erythritol

Powders are an integral component of air polishing, with sodium bicarbonate powder having been used since the 1980s.⁶ Many powders are now available, including less-abrasive options for subgingival biofilm removal with minimal abrasion to oral surfaces. By comparison, traditional powders sodium bicarbonate, calcium bicarbonate, and aluminum trihydroxide can comprise of particle sizes of up to 250 microns.⁷ Newer powders such as glycine are composed of significantly smaller particles, with micron sizes between 25 to 65, and erythritol has a micron size of 14. Regarding abrasiveness, traditional powders rank between 2.5 and 4 on the Mohs hardness scale, whereas glycine and erythritol measure at 2.

Because of these characteristics, a more comprehensive range of applications is possible with air polishers, such as safer biofilm removal supra- and subgingivally and the ability to penetrate deeper into periodontal pockets or furcations.

Glycine, a nonessential amino acid, was introduced to the dental market in 2003.⁸ Its crystals are odorless, colorless, and highly water-soluble. Glycine powder is suitable for supragingival applications, but its main application area is for cleaning root surfaces where it can remove plaque without damaging cementum or dentin.

Research shows that glycine powder is 80% less abrasive than sodium bicarbonate and causes less trauma to the gingival tissue than hand instruments or air polishing using sodium bicarbonate.⁹Glycine powder has proven more effective than hand instruments at removing subgingival plaque in periodontal sites with 3 mm to 5 mm probing depths.¹⁰ However, no difference was detected when comparing outcomes to ultrasonic scalers. Glycine has a light, sweet taste, which does not cause any unpleasantness to patients during the procedure.

Erythritol is a finer powder than glycine, useful for subgingival application. One study compared the effectiveness of erythritol with other powders used for air polishing and found that it had the lowest abrasivity while still effectively removing plaque and stains.¹¹Erythritol's antimicrobial and antibiofilm activity is higher than that of glycine. Moreover, it has exhibited inhibitory effects toward Streptococcus gordonii and Porphyromonas gingivalis. Erythritol has also shown the ability to suppress biofilm regrowth while enhancing cell attachment, cell viability, and proliferation of osteoblasts.¹²

Types of Units: Handheld or Stand-Alone

Air-polishing machines come in two forms: smaller, handheld devices with a powder chamber connected directly to a dental unit, or stand-alone units with a handpiece.¹³ For units that use glycine and erythritol powders, two types of nozzles are included with the handpieces: one for supragingival biofilm removal and one for subgingival biofilm removal.

Handheld air-powder polishing machines are lightweight, compact, and portable, which makes them easy to maneuver and use in hard-to-reach areas of the mouth. They are also relatively inexpensive compared to stand-alone units. While favorable for smaller offices with fewer patients, handheld devices may be less powerful or unsuitable for high-volume use in busy dental clinics.

Stand-alone air-powder polishing units are typically larger and are well-suited for large, busy dental offices. They are also generally more powerful, durable, and long-lasting than handheld units, which may need replacing more frequently. Nevertheless, stand-alone units can be expensive and take up more space in a dental clinic, which may be impractical for smaller offices.

Manual and ultrasonic scalers have proven to be time-consuming and technically demanding and are designed for hard deposits, not necessarily soft deposits like biofilm. Although an ultrasonic scaler works well for biofilm removal, it is used only on hard tissue versus air-powder procedures that are for hard and soft tissue. Additionally, root surface damage may occur with repeated use of ultrasonic scalers. Hypersensitivity caused by hard-tissue loss during tooth surface scaling is another common side effect of these procedures, occurring both during and after treatment.

When used with the correct technique and powders, air polishing is a safe and effective method of biofilm management. It is less aggressive than traditional methods, could allow for shorter chairtime, and offers patients a more comfortable experience.

Employing this technique has been associated with better patient acceptance, leading to better long-term compliance while improving overall results. With its many advantages, it is exciting to see air polishing's ongoing research and clinical novelties in transforming patient treatment outcomes.