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Although brushing teeth seems like a simple act, it is based on an ancient physical principle: friction. The friction between the toothbrush bristles and the teeth removes food debris and bacterial biofilms present in the mouth, a method used by humanity since the 15th century.

Even modern electric toothbrushes use this principle, where the internal motor creates rapid movements in the bristles, mechanically removing dirt through physical contact with the tooth surface.

However, researchers from Peking University in China may have advanced this ancient technique. They created a brush that operates not only through mechanical friction but also through an electrical charge generated during brushing. The purpose of this electricity is to eradicate bacteria that promote plaque formation and prevent its invasion into the teeth.

Preliminary results showed that after a three-month period of use, individuals who used the experimental brush presented significantly lower levels of bacterial plaque, gum inflammation, and bleeding compared to users of nylon bristles. It is important to note that aspects such as cost and long-term safety have not yet been evaluated. This study was published in the journal Science Advances.

Frank Scannapieco, a dentist from the University of Buffalo in New York, commented that the device may be more effective at removing plaque than usual manual brushes, but emphasized the need for more tests to confirm its safety and efficacy. He described the innovation as a 'new approach to an old concept.'

The experimental brush uses bristles made of polyvinylidene fluoride (PVDF), a plastic material capable of generating electricity when bent. As they flex during brushing, these bristles produce an electrical charge that subsequently causes chemical reactions in saliva and water. These reactions release reactive oxygen species (ROS), highly reactive molecules that have the potential to damage bacterial cells and absorb charges.

In laboratory tests conducted with isolated germs, the electrified bristles managed to eliminate more than half of Streptococcus mutans bacteria, which are responsible for cavities. In contrast, nylon bristles removed only 9% of these bacteria. Additionally, the experimental brush reduced Porphyromonas gingivalis levels—a bacterium linked to gum problems—by up to 78%, while nylon bristles reduced them by only 8%.

Materials capable of generating energy, such as PVDF, are classified as piezoelectric. Their everyday applications are known, including electric lighters, hydrophones, pressure and force sensors, and ultrasounds, all generating electrical charge under pressure or mechanical deformation.

To investigate this invention, the research team applied the brush to 115 volunteers who had gum inflammation or dental caries. Participants were randomly assigned to use the new brushes or traditional nylon brushes twice a day for one quarter. The study did not specify whether participants noticed any change in the sensation when using the electric brushes.

At the end of the experiment, volunteers who used the electric brushes demonstrated less bacterial plaque, less gum inflammation, and less bleeding compared to those who used common brushes. Analyses of the plaque samples also indicated that PVDF users had lower levels of bacteria related to oral diseases and higher levels of bacteria associated with oral health.

However, experts point out flaws in the study. Thomas Flemmig, a scientist from the University of Hong Kong, warned Live Science that despite being innovative, the way the data was presented by the researchers makes it difficult to compare the results with other studies on toothbrushes.

Modern homes are equipped with washing machines for laundry. However, if instead of a fresh scent, a musty or dirty odor appears after washing, the fault may not lie only with the detergent or the clothes themselves. The washing machine itself might be the cause. This problem arises because when using the machine, we focus on washing but pay insufficient attention to its cleaning. Over time, residues of detergent, water, and dirt accumulate inside the machine. Constant moisture promotes mold growth in certain parts of the appliance, which causes the unpleasant smell.

Often, the machine looks clean externally, but contamination can hide inside. This dirt can transfer to the clothes during the wash cycle, making them smell. Therefore, simply cleaning the drum is not enough; other components must also be addressed. Below is a guide to cleaning four important parts of the washing machine.

It is necessary to regularly clean the rubber seal around the door of a front-loading washing machine. Water, detergent, and fine fibers from clothing get into this rubber strip. If cleaning is not done in a timely manner, mold begins to form in this area, causing an unpleasant odor. To clean it, turn off the machine, carefully open the folds of the rubber, and wipe them with a damp soft cloth. The process should be completed by thoroughly drying with a dry cloth to prevent residual moisture.

Detergent and conditioner residues can accumulate in the dispenser drawer. Constant moisture in this drawer also promotes the development of dirt and mold, leading to a smell coming from the machine. To perform this procedure, you need to remove the drawer according to the manufacturer's instructions. Then, it should be washed with warm water and a soft brush. Before putting it back, ensure that the drawer is completely dry.

During multiple wash cycles, particles of detergent and powder can accumulate in the drum. Furthermore, using excessive amounts of detergent or prolonged washing at low temperatures also contributes to the formation of a layer of dirt. To clean the drum, it is recommended to run a special self-cleaning program (Tub Clean or Drum Clean) provided in the machine. If such a function is unavailable, follow the instructions in the user manual.

If the door or lid of the machine is closed immediately after removing the laundry, moisture remains inside, which can lead to musty odors and mold. To prevent this, wipe the door and the interior with a dry cloth after washing. It is also recommended to leave the front door and the top machine lid open for some time so that internal moisture can evaporate.

These small details should also be paid attention to.

In addition to cleaning the floors and walls in the house, it is extremely important to regularly clean the water reservoir installed on the roof. People usually clean the tank every few months to remove accumulated dirt, moss, and sediment, ensuring clean water in the house. However, often even after thorough tank cleaning, the water starts to emit an unpleasant smell when the tap is opened, and people do not understand what the exact problem is.

In fact, the cause of the water odor is not always a dirty tank. Sometimes the contamination in the household piping system, water filter, water heater, or sink drain can be to blame. Therefore, instead of constantly cleaning the tank, it is necessary to find the true cause of the odor. Below are discussed the causes of water odor after tank cleaning and methods to eliminate it.

Even after cleaning the tank, old water may remain in the pipes. If the water remains stagnant for a long time, it can acquire a musty or damp smell. In this case, you should leave all taps in the house open for some time so that the old water drains from the pipes. If the smell persists, it is recommended to check the entire piping system.

If the smell is present only in hot water but not in cold water, the probable cause is the water heater. Due to prolonged water stagnation and lack of maintenance in the boiler, sulfide bacteria can develop, which gives the water a strong unpleasant odor. In such a situation, it is correct to clean and maintain the water heater.

Sometimes when an odor appears near the sink or washbasin, it seems that the water is spoiled, whereas the real reason lies in drainage contamination. The accumulation of soap, oil, and food residues in the drain pipe promotes the development of bacteria and mold. To check this, fill a glass with water from the tap and take it away from the sink to smell it. If the water in the glass does not smell, the problem is most likely in the drain. If the water in the glass smells, the water supply system needs to be checked.

Taking care of the water filter is as important as cleaning the tank. With prolonged use without replacement, filtering elements can accumulate dirt and various organic substances, which worsens the taste and smell of the water. Therefore, it is necessary to replace the filters of water purification systems, such as reverse osmosis or other types of filters, on time according to the manufacturer's instructions.

Even after cleaning the tank and pipes, the water may have an earthy or swampy smell. This may be related to the water source. The growth of algae and organic substances in sources such as rivers or lakes can change the taste and smell of the water. If the water smell suddenly changes, you should notify the local water utility and request a water quality check.

The choice of a suitable filter or purification method should only be made after determining the root cause of the odor. There is no universal filter that suits all types of odors.

Activated carbon: Can help reduce the content of many organic substances and chlorine in water, improving its taste and reducing unpleasant odors.

Reverse osmosis (RO) filter: Used to reduce the concentration of various dissolved contaminants in water, but it is not the only solution for all types of odors.

Grinsand filter: Can be effective if the rotten egg smell is caused by hydrogen sulfide. It helps oxidize this gas, turning it into particles that can then be filtered out.

Degasifier: Used to remove gases, such as hydrogen sulfide, from water.