The Secret Behind Electric Toothbrushes

The first electric toothbrush was presented in Harper’s Weekly on February 13, 1886, but the true pioneer in home dental care is considered to be the Sonicare (Optiva Corporation) high-frequency sonic toothbrush introduced at the Chicago Midwinter Meeting in February 1993.

While mechanical toothbrushes are the popular standard for home dental care, and electrical toothbrushes were initially recommended for people with disabilities and children, sonic technology is now one of the most efficient and valued technologies in the oral-care world.

A 2019 SHIP (Study of Health in Pomerania) cohort study carried out over 11 years found that people using a powered toothbrush experienced less attachment loss. At the 11‐year follow‐up, electric brush users had an average of 0.36 more teeth than their manual-toothbrush using counterparts.¹

The Hydrodynamic Effect

It has been proven that toothbrushes with >30,000 movements per minute are capable of cleaning in two different ways.² The first is mechanical, by direct contact of the bristles with the tooth, and the second is hydrodynamic, functioning without the bristles even touching the surface of the teeth and gingiva.² It has been shown that the hydrodynamic effect removes bacteria in gingival pockets up to 6mm.²

During brushing, a slurry of saliva, water and toothpaste is created, and the sonic toothbrush turns this mixture into an active hydrodynamic vortex.² As the sonic toothbrush generates a strong turbulence in the mixture, the liquid washes over, and in between, the teeth at high speeds. This turbulence removes plaque even from relatively inaccessible spaces. This cleansing is very effective against biofilm, while very gentle on the teeth and gingiva.²

Marginal plaque is where the biofilm first starts to develop. The removal of marginal plaque with a mechanical brush is limited to its mechanical action. (Fig 1) The Curaprox Hydrosonic Pro (available through Oral Science, Longueuil QU, manufactured by Curaden, Kriens, Switzerland) demonstrates the hydrodynamic effects of the hydrosonic toothbrush. (Fig 2) The longer outer bristles clean mechanically, and they move across the tooth surface with slight pressure as the brush is moved manually. The inner, shortened bristles do not touch the tooth surface at all, and thanks to the fact that these bristles are not hindered in their movement, they create a targeted hydrodynamic effect in the direction of the tooth. They clean recesses, interdental spaces, and around orthodontic brackets.³

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Comparison Between Sonic and Oscillating Toothbrushes

The main differences between a sonic and oscillating toothbrush are brush movement direction, brush head shape, and cleaning coverage. Oscillating toothbrushes do not reach the interdental spaces, and the turbulence they create is directed mainly to the sides. The vibrations present in sonic technology, on the other hand, have the power to reach interdental spaces due to the hydrodynamic effect.

The overall cleaning impact on gingival health – removing bacteria out of pockets and thus reducing inflammation – is therefore more effective with sonic toothbrushes,² particularly in the neglected sulcular areas. Sonic brushes offer tactile feedback to the margins of the gingiva. Curaprox Hydrosonic Pro brushes have much softer filaments than oscillating and other sonic toothbrushes. An oscillating movement in toothbrushes can be damaging. Gentle cleaning is safe, because the bristles are very fine, and the side-to-side movements of sonic toothbrushes cause few soft tissue injuries.³

The Curaprox Hydrosonic Pro is designed with a unique water-drop shaped head. This makes it easier for patients to optimally adapt their toothbrushes to both buccal and lingual tooth surfaces. The brush angulation and the rubberized back of the handle are also helpful. Other sonic toothbrushes have solid hard plastic brush handles. This vibration can be uncomfortable and even hurt the oral soft tissues. The Curaprox Hydrosonic Pro’s special bristles and design minimize these problems.

Main Advantages of Sonic Toothbrushes Over Manual Toothbrushes

Many people place far too much pressure on their teeth and gums with manual brushes, making home cleaning damage inevitable, particularly with hard-bristled brushes. Over time, this can cause gingival recession and eroded and abraded enamel.⁴ Sonic brushing is accomplished without forced pressure. The Curaprox Hydrosonic Pro has a very powerful motor that provides up to 84,000 brush strokes per minute, more than any other sonic toothbrush. It is designed to be guided and gently applied to the teeth with light pressure. It is advisable to not rest the brush completely on the teeth, but to make localized circular movements, benefiting all dental structures, the longer bristles mechanically cleaning the teeth, and the freely oscillating shorter bristles providing hydrodynamic cleaning. The brush should be inclined 45⁰ to the teeth to optimize sulcular cleaning, preventing gingivitis and periodontitis. The angling of the brush head ensures that all parts of the mouth can be easily reached. The 90⁰ brush position offers the best cleaning of the hard surfaces and the interdental spaces. The mouth should be closed during a sonic toothbrush cleaning.

Bristles: Quality and Quantity are Important

The bristles of the Curaprox Hydrosonic Pro are made of very soft, yet rigid, Curen® filaments. Curen® filaments do not absorb water, retaining rigidity and effectiveness even when wet. The bristles’ softness ensures they are very gentle on teeth and gingivae.

Curaprox Hydrosonic Pro has both longer and shorter rounded bristles. The longer bristles access the niches and interdental spaces, while the shorter bristles vibrate freely providing the desired hydrodynamic effect. The raised tufts of longer bristles ensure that the distance between the tooth surface and the vibrating bristles is sufficiently large for unencumbered vibration.⁴ The sonic brush can prevent teeth discoloration and minimize the development of tartar.³

Conclusion

The three major requirement for sonic toothbrushes are:

1. No pressure
2. Precise adaptation to the dental surfaces (soft and hard tissues)
3. Slow cleaning of the entire tooth surface

Very rapid bristle oscillation disrupts the biofilm by both direct contact and hydrodynamically, effectively cleaning both hard and soft dental tissues. The Curaprox Hydrosonic Pro is an ideal professional recommendation for optimal sonic technology toothbrushing.

Oral Health welcomes this original article.

Authors Disclaimer: Prof. Dr. Ulrich P. Saxer was scientific advisor for the development of the latest generation of sonic toothbrushes made by Curaden AG.

References

1. Pitchika V, Pink C, Völzke H, Welk A, Kocher T, Holtfreter B. Long-term impact of powered toothbrush on oral health: 11-year cohort study. J Clin Periodontol. 2019;46:713–722. https://doi.org/10.1111/jcpe.13126
2. Delaurenti M, Ward M, Souza S, Jenkins W, Putt MS, Milleman KR, Milleman JL. The Effect of Use of a Sonic Power Toothbrush and a Manual Toothbrush Control on Plaque and Gingivitis. J Clin Dent. 2017 Mar;28(1 Spec No A): A1-6. PMID: 28422459.
3. Schmidt JC, Astasov-Frauenhoffer M, Waltimo T, Weiger R, Walter C. Efficacy of various side-to-side toothbrushes and impact of brushing parameters on noncontact biofilm removal in an interdental space model. Clin Oral Investig. 2017 Jun;21(5):1565-1577. doi: 10.1007/s00784-016-1969-y. Epub 2016 Oct 19. PMID: 27757550.
4. Danser MM, Timmerman MF, IJzerman Y, Bulthuis H, van der Velden U, van der Weijden GA. Evaluation of the incidence of gingival abrasion as a result of toothbrushing. J Clin Periodontol. 1998 Sep;25(9):701-6. doi: 10.1111/j.1600-051x.1998.tb02510.x. PMID: 9763324.

---

About the Author

Prof. Dr. Ulrich P. Saxer graduated in Zurich, Switzerland specialized in periodontology and oral prevention. He has set up dental hygiene schools in Geneva, Bern and Zurich dedicated to preventive oral health. Prof. Saxer is a KOL in oral prophylaxis and has given >120 lectures and published >150 scientific papers. He is a Board Member of Toothfriendly International, an organization working for better oral health.