Subgingival Debridement by Erythritol Powder Air-Polishing (EPAP) in Comparison With Ultrasonic Instrumentation During Periodontal Maintenance. A Randomised Clinical Trial

As a result of ongoing microbiological challenge from accumulated dental plaque, it is paramount to ensure thorough removal of such deposits from the root surface to maintain periodontal health. Mechanical instrumentation using conventional hand instrument and/or oscillating scalers is the gold standard of periodontal therapy. Patient is commonly recalled every 3-4 months interval for supportive periodontal therapy (SPT) to decrease disease recurrence and prevent further tooth loss. This repeated mechanical instrumentation, however, may cause irreversible damage to dental hard tissue. As such, the use of treatment modalities effective in removing biofilm, being time efficient, causing minimal discomfort, tissue damage, and less abrasion of root surface would be preferable during SPT.

With the advancement of technology in dentistry, air polishing (AP) was introduced to dentistry for cavity reparation in 1945. The usage then extended into periodontal debridement in SPT, by means of slurry pressurized air with a novel low abrasive powder and water. A study done by Petersilka et al. 2003 in 27 SPT patients of pockets 3-5mm depth revealed an approximately 90% reduction in all viable bacterial counts and offered greater patient comfort when compared to conventional hand instrument. It was also time saving as only 5 seconds is needed per tooth surface. Since 1980s, sodium bicarbonate has been used in AP devices and was the only powder available until 2004. It is non-toxic, water-soluble, safe for intra-oral use and is efficient in removing biofilm and staining on intact enamel surfaces. However, this conventional powder can cause substantial damage to the root cementum and dentine at area of receded gingiva, severe epithelial erosion and unpleasant perception by patients.

In order to deal with this issue, several types of AP abrasive powders with improved clinical performance and patient comfort have been produced. As early as in 2003, glycine based (amino acid) powders were produced with smaller mean particle size 45-60 µm and less chiseled shape, compared to sharp edged and up to 250 µm mean particle size of sodium bicarbonate. Due to its ≈80% less abrasiveness, studies had shown that glycine powder air-polishing (GPAP) was more efficient in plaque removal in root debridement, caused non-critical substance loss and lower the rate of increase in root surface roughness when compared to sodium bicarbonate. On the other hand, in a publication by Flemmig et al. in 2007, efficacy of GPAP was assessed in periodontal pockets of various depths. The results revealed the average debridement depth of 2mm was obtained at pockets depth of 4mm, and 60% of subgingival root surface was cleaned. In deeper pockets, the efficacy reduced to about 40% and the use of hand instruments or ultrasonic scalers may be superior.

Thus, Moёne et al. had described a newly designed nozzle in 2010 in order to extend the use of air polishing in deeper pockets. This nozzle allowed access to subgingival root surfaces and the jet spray has a lower flow and pressure compared to supragingivally applied air polishing. This new device appeared to be safe, perceived to be more acceptable by patients and was more time efficient than scaling and root planing. However, Petersilka (2010) pointed out two cases of air emphysema developed after using this jet system but fortunately the cases resolved within 4 days without additional intervention. Therefore, he remarked that emphysema cannot be completely ruled out in all other types of air-polishing systems. Since then, more studies have been carried out using this newly designed nozzle with GPAP. A 2-months trial by Wennstrӧm et al. in 20 recall patients showed no significant differences in clinical or microbiological outcomes between subgingivally applied GPAP (SubGPAP) and ultrasonic debridement of moderate deep pockets (5-8mm). They also noted there was only a short-term reduction of subgingival microflora in both modalities.

Recently, a natural sugar erythritol powder has gained its popularity as it has slightly lower abrasiveness and smaller particle size 14-31 µm compared to glycine. In 2013, Hashino et al. found that erythritol has inhibitory effect on the biofilm produced by Streptococcus gordonii and Porphyromonas gingivalis. A year after, Drago and team tested on a new formulation consisting of erythritol and chlorhexidine with the standard glycine powder. This in vitro study demonstrated that the combination of erythritol/chlorhexidine displayed a stronger antimicrobial and antibiofilm activity on titanium discs. While in a 12 months clinical trial by Müller and co-workers, repeated subgingival air polishing with erythritol containing 0.3% chlorhexidine appeared to be safe, reduced the number of pockets >4mm and induced less pain than ultrasonic instrumentation. As subgingival biofilm may not mineralise between two SPT visits, less aggressive approach with better microbiological outcome may be appropriate for residual pockets.