A lot of resources has been spent on developing vaccicines against S.mutans (caries) but mechanichal cleaning opportunities has been overlooked.
During ultrasonic scaling the cavitation in the end of the ultrasonic tip helps in disrupting the biofilm. Ultrasonic scalers are used daily in the dental practices by dentists and dental hygienists. Nina V. et al. suggest that in future no-contact ultrasonic scaler tips may be developed (1). While invention is not a scaler tip it has a lot of merits of the invention that researchers are looking for.
Nina V. et al. have provided further research on scaler tips in non-contact mode disrupting biofilms in complex materials to suggest that it may be viable to be used in peri-implantitis and perimucositis (for inflammation around dental implants) (2)
Also Burleson A. et al. showed proof that cavitation provides great advantages in extremely difficult places such as inside of a tooth providing significantly greater results in cleanliness while using ultrasound. In vivo, prospective, randomized, single-blinded study histologically compared biofilm/necrotic debridement efficiency for human mandibular molars showed showed cleanliness of 91% with 1 min ultrasonic treatment compared to 45% for group without ultrasonic treatment, in 3-mm depth. The teeth in both groups were obturated first with hand and rotary files. (3)
While not directly comparable, removal of bacterial biofilm from water filled tubes using axially propagated ultrasound was proven efficient by (Mott, I.E.C. et al.). The result was comparable to conventional ultrasonic bath. While the composition of bacteria in the said tubes were different, it still provides further proof of the efficacy of the ultrasound (4)
Nishikawa T, et al. demonstrated in his study that ultrasonic wave exposure in a non-contact mode effectively removed adherent biofilms composed of S. mutans in vitro. (5)
Patrícia Costa Cruz et al. showed that when cleaning dentures with ultrasonic cleaner even without alkaline agent was superior over brushing the dentures with water. (6)
To demonstrate the superior qualities of ultrasonic cleaning over other methods. When removing blood from contaminated dental instruments decontamination in an ultrasonic cleaner was more effective than hand washing, resulting in greater than a 100-fold reduction of blood contamination. (7)
Periodontal disease is associated with heart disease, stomach ulcers and ulcers on feet with people suffering from Diabetes.
Is there anything else in common? Could there be?
As ulcers have many similarities to etiology of periodontal disease, they are historically treated in somewhat similar ways. Mechanical cleaning of the area leads to healing. With teeth this has been done by flossing and brushing and with feet ulcers surgical debridement and other debriding methods.
Low-Frequency Ultrasound Shown to Significantly Improve Healing of Leg Ulcers
Ultrasound has been utilizing in debriding the wound area with great success in healing process. The control group showed a mean decrease of 11% in the ulcerated area after 8 weeks, in the ultrasound group the mean ulcerated area decreased by 41% (p < 0.05) (12.)
This serves as the basis of the hypothesis that even without cavitation the biofilms are dispersed that is likely one of the maine cause for the healing. Various other benefits are described as well in the research that suggests that ultrasound should be utilized more often.
The results above were achieved using low frequency.
Are there any real reason why we should not apply ultrasonic cleaning in the oral cavity if the results elsewhere suggest that we should do it?
Taking it to the extreme
But if we make hypothesis that removing biofilms of dental surfaces requires less energy and exposure than extracorporeal lithotripsy, we may have an idea of how harmful it may be if we used extreme exposure and intensity.
Darzi A et. al concluded that the effects to soft tissues were minimal when using low dosage. Obviously we do not need to remove calculus from gall bladder with our device. (8.) If we look at the methods of utilizing piezoelectric shock-wave lithotripsy when removing salivary gland stones Iro H. et al. concluded that: “The piezoelectric lithotripsy of salivary stones caused no serious side effects which could be proven by clinical, biochemical, sonographic, and magnetic resonance imaging (MRI) examinations.” (9.)
Now we have some idea of the potential problems. However, something even more comforting might be around the corner. Zips A et. al colonized a reverse osmosis membrane with fast adhering bacteria and were able to detach 95% of the bacteria utilizing 2W power without damaging the said membrane. (10.)
Obviously the bacteria were a monolayer and the structure of biofilm in oral cavity is different. But for me this confirms that acoustic pressure changes in aqueous solutions even without cavitation might be enough to eradicate most of the biofilms. If you wanted to remove calculus or tartar the risk of the soft tissue damage is potentially higher. But still likely something that is in the scope that we can manage.
Last, introducing fluid kinetics helps the detachment of the biofilms. Also, if the water is not degassed the air bubbles increase the removal of the biofilm as air bubbles in the water collide the biofilm. If we truly want to avoid the cavitation altogether. These applications are –to my best knowledge– also in the scope of the patent application I filed (11.).