Electric brushes can improve both motivation and brushing technique for everyone and they provide different benefits depending on the type of technology they apply.

According to the latest studies of microbial composition, there are more than 1,000 bacterial species in the oral cavity(1). These species are distributed in communities or biofilms, which are bacterial aggregates embedded within a matrix of polysaccharides which mainly settle on the teeth. However, some of these species may break the existing balance in health conditions and initiate the main pathologies affecting the oral cavity, including tooth decay and periodontal disease(2), as well as problems such as halitosis.

Daily oral hygiene is necessary to control biofilm and maintain good oral health and to prevent the problems and diseases that may be caused by its build up. Out of all the existing methods, brushing is the basis of oral hygiene. In fact, in a survey published in a white paper on dentistry by the Spanish Dental Association, up to 82% of Spaniards brush at least twice a day(3).

THERE IS A WIDE VARIETY OF BRUSHES, SO ONE OF THE FIRST CRITERIA TO BE TAKEN INTO ACCOUNT WHEN CHOOSING A BRUSH IS WHETHER IT WILL BE MANUAL OR ELECTRIC.

When done with skill and precision, manual brushing is very effective; however, many people fall short on issues such as technique, accuracy, accessing all areas (especially those that are difficult to reach) or the duration of brushing. In these cases, an electric brush can be of advantage.

Electric brushes can enhance both motivation and technique and bring different benefits depending on the technology used. There are two main groups of technologies: oscillating/rotating (or oscillating/pulsating) brushes, and sonic brushes. In addition, there are other types of brushes such as ionic, ultrasonic, etc.

OSCILLATING/ROTATING AND OSCILLATING/PULSATING TECHNOLOGY

Oscillating/rotating and oscillating/pulsating technologies combine circular or rotary movements in both directions (clockwise and anticlockwise). Removal of biofilm occurs through the mechanical action of the filaments on the surface of the tooth, as far as the filaments reach. The frequency of oscillation is usually between 5,600 and 8,800 strokes per minute.

In addition, oscillating/pulsating (multidimensional or 3D) technology adds pulsating transverse movements (from back to front) in the direction of the brush filaments. The speed of the pulsating movements can be between 20,000 and 40,000 pulses per minute.

In either case, the technology is based on mechanical action.

SONIC TECHNOLOGY

In contrast, sonic brushes emit high frequency acoustic vibrations from the horizontal vibration of the filaments at a speed of between 16,000 and 45,000 stokes per minute (to get an idea of what that means, a manual brush can make 300 stokes per minute). Thanks to this, sonic technology allows for two types of mechanisms that are important for oral hygiene: on the one hand, mechanical action, and on the other, acoustic vibration and the consequent fluid dynamics or hydrodynamics.

• Mechanical action. This is the main action. Acoustic vibration is produced by the high number of lateral or side-to-side movements of the filaments (up to 45,000 vibrations per minute), causing a greater disruption of the bacterial plaque (oral biofilm) on the surface of the teeth, and consequently favouring its removal in a more effective way. The most stubborn biofilm can be disaggregated on coming into contact repeatedly with the filament vibrations, which is specially useful for those with difficulties in performing dental hygiene like orthodontic patients.

• Hydrodynamic action. On the other hand, the high-speed vibration of the filaments emits acoustic waves in the fluid surrounding the filaments. These waves and the energy associated with them are transmitted through the oral fluids (primarily saliva), helping to disrupt the biofilm (fluid dynamics). There are studies that demonstrate that acoustic vibrations decrease the ability of certain bacteria (primary colonisers) to adhere to hard dental surfaces(4), and that this is even possible without contact between the filaments and the surface of the tooth (at 2-3 mm). Other studies have also shown the ability to remove bacteria attached to the acquired pellicle (salivary proteins which are deposited on the enamel and which facilitate adhesion of the bacteria that make up the bacterial plaque).

High-frequency vibration causes the formation of small bubbles of saliva containing oxygen. These bubbles can get to hard to reach places in the mouth, and can even penetrate interdental or subgingival spaces. In a subgingival space where anaerobic bacteria—which do not tolerate oxygen—have grown, the introduction of oxygen via the bubbles creates an unfavourable environment for these pathogenic bacteria, preventing their growth and even favouring their death. If brushing is carried out with toothpaste (as is usual), access is made easier as it acquires a more liquid and foamy consistency and thus conveys its properties to different parts of the oral cavity.

The efficacy of sonic brushes lies, therefore, in the combination of two actions: mechanical and hydrodynamic. This combination allows beneficial effects to reach areas that are otherwise difficult to access, including subgingival and interproximal areas, thereby achieving a greater reduction of bacterial plaque (biofilm) throughout the mouth. In addition, sonic brushing can stimulate salivary secretion, so it is beneficial in alleviating xerostomia and balancing the pH of the oral cavity(5).

Regardless of the type of brush, it is still necessary to maintain suitable brushing frequency and duration, i.e. twice a day or after meals for at least two minutes, and to brush all the sides of the teeth to make brushing effective. Interproximal and lingual hygiene should also be performed daily. 

INDICATIONS FOR THE SONIC ELECTRIC BRUSH