Erythritol Powder Air Polishing as an Adjunct in Non-surgical Periodontal Therapy in the Management of Periodontitis: a Randomised Clinical Trial

Periodontal disease is an infection that causes inflammation of the tooth supporting structures, which results in the destruction of the periodontal ligament and alveolar bone, and eventually, tooth loss. The aetiology of the disease is oral biofilm. Therefore, the regular mechanical removal of biofilm, among others, is necessary to prevent and stop the disease progression. Biofilm and biofilm retentive calculus are removed via periodontal debridement. Subgingival debridement is an important procedure that is initially performed in the non-surgical periodontal therapy phase. According to the first European Workshop on Periodontology, subgingival debridement involves gently instrumenting subgingivally to disrupt and/or remove the biofilm. Various techniques are involved in subgingival debridement, with hand instruments and ultrasonic or sonic instruments being the most common, while modalities like air polishing are gaining momentum.

Mechanical periodontal debridement using hand instruments like curettes, sickles, hoes or files, and power driven instruments such as sonic or ultrasonic scalers, is generally known as root surface debridement (RSD). This modality is considered to be the gold standard of periodontal therapy. The usage of hand instruments has been advocated for their efficiency and the fact that it allows tactile sensation and operator control. However, various drawbacks from these instruments have been noted. Hand instruments and scalers are both technique sensitive, time consuming, and may cause irreversible hard tissue damage when used regularly. Besides, anatomical variations such as grooves, concavities and enamel pearls as well as deep pockets and furcation involvement, can influence debridement quality. Since periodontal therapy is performed regularly, being time efficient, acceptable to patient, and causing minimal tissue damage are important determinants. As such, treatment that causes minimal abrasion to root surface while being highly effective in biofilm removal would be a preferable choice.

One such treatment is air polishing. Air polishing was introduced in 1945 for the purpose of cavity preparation. Over time, its use expanded to periodontal debridement. Stain and biofilm are removed by the abrasive "slurry" which is formed by mixing together pressurised air, a jet of water and a stream of small particles. Sodium bicarbonate was the only abrasive powder available from the late 1970s until 2004. It is non-toxic and water soluble, with a mean size of up to 250μm. It has been shown to be safe and efficient to be

used on intact enamel surfaces. However, due to its abrasiveness, it could not be used on demineralised enamel surfaces. A study showed that regardless of parameters such as working time, powder and water setting, working distance, and angulation of the handpiece, substantial damage to the root occurs from sodium bicarbonate, concluding that it is contraindicated for use in exposed root surfaces. In order to overcome this problem, glycine based powders were then produced. In the in vitro study showed that glycine powder proved to have low abrasiveness towards cementum and dentine, while being efficient at plaque removal. The powder had a mean particle size of 45μm - 60μm, and was 80% less abrasive compared to sodium bicarbonate. More recently, erythritol powders have been used in air polishing. Erythritol is a sugar alcohol that is non-toxic, chemically neutral, and water soluble, and has been widely used as an artificial sweetener and food additive. Due to comparable physical properties to glycine and chemical characteristics allowing binding of antiseptic substances, it has been suggested for subgingival biofilm removal. Moreover, a recent study has shown erythritol to have an inhibitory effect on some periodontal bacteria, including P. gingivalis.

Advancements in air polishing devices have also occurred, mainly involving a disposable nozzle design to access the periodontal pocket directly, thus allowing the abrasive slurry to be delivered into moderate-to-deep periodontal pockets. The nozzle has a thickness of 0.7mm, which is within the diameter range of most periodontal probes, thereby allowing it to be inserted to the base of the pocket with minimal force. Besides, the new design resulted in a drop of pressure of the jet spray by 1 bar, thus reducing the risk of emphysema and allowing the nozzle to be used subgingivally.