The hands of dental personnel are the first factor for the transmission of pathogens and, accordingly, for the cross-transmission of infections associated with dental care. This requires their meticulous hygienic and/or surgical disinfection according to the procedure performed and is a basic and mandatory component of infection control in dental practice.

The specificity of dental manipulations is such that extremely close contact with the mucous membrane of the patient’s oral cavity, oral secretions, aerosols formed during treatment, etc., is inevitable. Blood mixed with oral secretions such as saliva and gingival fluid is present in almost every manipulation. Through their hands, dental personnel, in the absence of standard precautions and rules for interrupting the cross-transmission of infections, unintentionally transfer microorganisms from the patient’s mouth to surrounding surfaces and vice versa. Only strict adherence to hand disinfection protocols for each procedure and for each patient would be important in preventing cross-contamination from dental staff to patients, from patients to dental staff, and between patients themselves. It is important to note that dental staff also includes dental assistants, dental technicians, administration, hygienists, etc.^[1-5]

To reduce the risk of infection transmission, strict hand hygiene, including washing, drying, and disinfection with alcohol-based skin antiseptics, must be carried out before and after patient contact as well as before putting on and taking off gloves for each patient.^[6]

Interestingly, a study reported that the risk of healthcare-associated infections in developing countries varies from 2 to 20 times greater than in developed countries. This alerts the need to improve infection surveillance and control practices in our country/region/city by taking effective measures.^[7]

Through contaminated hands, respectively, gloves, microorganisms can be transferred to dental equipment, to other surfaces in the dental external environment, instruments, and contaminate the eyes, nose, or mouth of the patient or dentist/staff. By properly disinfecting hands, we also interrupt the indirect transmission of microorganisms to the various epidemiological factors for the transmission of healthcare-associated infections.^[8,9] In Bulgaria, the standard for combating nosocomial infections also pays due attention to infections related to dental care, but only data from practice through regular inspections, observations, epidemiological and microbiological studies can give us up-to-date feedback on the application of the standard in daily practice.^[8]

The global guidelines^[1,2] and the standard for combating nosocomial infections, which is also being implemented in Bulgaria, do recommend hygienic hand disinfection in dental practice:

The aim of the present study was to determine the presence of resident and transient skin microbiota on the hands of dentists after performing hygienic hand disinfection.

We conducted a prospective epidemiological and microbiological study among 60 dentists from the city of Plovdiv, Bulgaria during the period spanning May to June of 2025. The purpose of the study was explained in detail to the participants, and they agreed to be involved by signing an informed consent form. A short interview-type survey was also conducted regarding compliance with basic practices for hygienic hand disinfection. Dentists were asked to perform hygienic hand disinfection as they usually do with alcohol containing any antiseptic used in their practice. All skin antiseptics used by them are combined alcohol-based preparations that are registered for use as disinfectants for medical purposes in Bulgaria and meet standards for hand disinfection such as EN 1500. In dental practice, products with a 70% ethanol concentration are commonly used, but all alcohol-based preparations containing 60 to 95% ethanol or isopropanol for hygienic hand disinfection are effective. When explaining the procedure, the importance of the six steps for hygienic hand disinfection and the rubbing time of 20 to 30 seconds, for which it should be performed, were emphasized. The skin antiseptics used by dentists are mainly Zhivasept E80 and Skinsept Color. The samples were collected from their hands before they put on gloves and performed a therapeutic or prophylactic manipulation.

In 53.3% (n=32), no growth was observed on blood agar plates. However, we detected Gram-positive bacteria – coagulase-negative Staphylococcus spp. (CoNS) at 10⁵ colony-forming units (CFU) or more in 20% (n=12), and CoNS below 10⁵CFU in 26.7 (n=16) (Fig. 1).

We observed no bacterial growth on eosin-methylene blue agar in 85% (n=51) of the samples. Bacterial growth was present in the rest 15% (n=9). Both lactose-positive and lactose-negative bacteria in association were demonstrated in all nine samples, below 10⁵CFU in 13.3% (n=8) and in one sample at 10⁵CFU, representing 1.7% (Fig. 2).

Fungal growth was present in just 3.3% (n=2) of samples, represented only by molds but not yeasts. Based on these results, Gram-positive bacteria predominate over Gram-negative bacteria.

During the short interview, we found the following. The gender distribution is as follows: 31.7% (n=19) are men, and 68.3% (n=41) are women. According to the work experience, the dentists are divided into the following groups: those with experience up to 5 years are 10.0% (n=6), those with experience between 5 and 15 years are 48.3% (n=29), and those with experience more than 15 years are 41.7% (n=25). Regarding hand washing before disinfection, we get an unsatisfactory distribution: 36.7% (n=22) wash their hands before disinfection, but 63.3% (n=38) do not, which contradicts the recommendations, especially if the hands are visibly dirty. After washing, hands should be dried with disposable tissues and discarded, thus interrupting the risk of cross-infection. However, our results show that a small proportion of dentists dry their hands, which leads to dilution of the disinfectant and a decrease in its effectiveness: 8.3% (n=5) dry their hands, and 91.7% (n=55) do not dry them. 58.3% (n=35) perform hygienic hand disinfection before and after each patient and for the optimal 20-30 seconds, and 1.7% (n=1) for one minute. However, it is worrying that 40.0% (n=24) practice hand antisepsis for only 5 seconds, which is extremely insufficient, and in reality, they do not comply with the minimum recommended duration (20–30 seconds). This is a prerequisite for insufficient disinfection effectiveness. When asked whether they change gloves during decontamination, only 11.7% (n=7) gave a positive answer, and this was the only correct answer. 88.3% (n=53) used the same ones, thereby contaminating surrounding surfaces and equipment. 31.7% (n=19) worked in a team with a nurse, who was an undoubted help in carrying out the decontamination, but 68.3% (n=41) carried out the decontamination independently, which in turn required them to change the gloves used during the treatment. 73.3% (n=44) worked in individual practice, and 26.7 (n=16) in a group.

A statistically significantly higher proportion of men in the study had a positive result in a blood agar test and growth above 10⁵CoNS compared to women (36.8% in men compared to 12.2% in women), and an associative relationship was established for this indicator (χ²=6.662, p=0.036).

For the other media (eosin-methylene blue and Chrome agar), no statistically significant dependence on the sex of the dentists studied was established (p>0.05).

Candida Chrome agar shows almost complete lack of growth (only 2 cases with molds), which makes the statistical analysis less indicative.

The results obtained by our team are far from optimal, and unfortunately, are by no means an isolated case. Studies show that even with good awareness among healthcare personnel, actual compliance with hand hygiene protocols is inadequate and needs constant updating. Handwashing practices among dental practitioners and their attitudes and knowledge towards compliance with hand hygiene guidelines were analyzed. A campaign with posters and educational materials was conducted to adopt, reinforce, and support hand hygiene behavior and resulted in an overall improvement in compliance with hand hygiene guidelines (51-83%, p<0.001).^[10] Our study found that gloves are always worn after disinfection, which greatly reduces the risk of transmission of infections; however, this protection is not absolute. Gloves do not replace the mandatory recommendations for prior hand disinfection.^[1,2,8] A survey of dental hygiene students was conducted by other authors to assess their attitudes towards infection control protocols and handwashing practices. It found high awareness of the need for handwashing, but low awareness of other infection control methods and their application in practice.^[11] The results we obtained are similar to those described in the literature.

Among the most common nosocomial pathogens is methicillin-resistant Staphylococcus aureus (MRSA), and its transmission occurs through both direct and indirect contact. The likelihood of infection increases with the length of stay of patients in healthcare facilities. In dental practice, the contact time between patients and dentists is relatively short (usually within hours), and transmission of MRSA is expected to be low. The risk of transmission increases with contamination of hands, surfaces/equipment with MRSA, and given its high resistance in the external environment. Interestingly, a study from Mexico showed that the incidence of MRSA and S. aureus among dental patients in Mexico City was higher than in Europe. Once infected, dentists would become a risk to their patients and non-professional contacts.^[12] Another study from India showed that the incidence of MRSA carriage increases with years of clinical practice.^[13] A literature review found that eight studies reported a significant sex difference in handwashing compliance (women > men). We also found significantly better knowledge and compliance with disinfection practices among women.^[14] All these data point to the serious contamination of the dental office with a wide variety of microorganisms and the possibility of their transmission between patients and dental personnel. Proper hand disinfection, as the first factor for the transmission of microorganisms in health care facilities, is a key element in interrupting the transmission of nosocomial infections and in achieving a safe working environment for patients and personnel.^[9,15-17]

Recovering Gram-negative bacteria from dentists’ hands after disinfection is worrying and indicates that current hygiene measures may be insufficient to eliminate potentially pathogenic or resistant organisms. Their persistence suggests shortcomings in technique, disinfectant efficacy, or environmental contamination, and highlights a risk of cross-infection that warrants review of hand-hygiene protocols.

Aspergillus spp. spores are ubiquitous in nature. They are common in air, dust, and damp areas like sinks, drains, and even ventilation, which means re-contamination may occur quickly after disinfection. Aspergillus spp. pose a significant risk to immunocompromised individuals, potentially causing invasive disease. These molds can also induce respiratory reactions in sensitive individuals.

There are a number of microbiological studies that report the presence of both enteric (Enterobacteriaceae) and opportunistic fungi (e.g. Candida spp.) on the hands, gloves, and work clothes of dentists and dental students.

Common factors leading to a higher incidence of contamination include improper hand washing/disinfection technique, wearing rings or other jewelry under gloves, and incomplete adherence to glove change protocols between patients.^[18,19]

Although coagulase-negative staphylococci, which belong to the resident skin microbiota, are the main isolates in the majority of samples, their presence in a high microbial count is undesirable. This is especially important for patients with immunosuppression. The high microbial count is also an indicator of insufficiently effective hygienic hand disinfection. Gram-negative enteric bacteria were also isolated, which is absolutely unacceptable. It indicates a serious misunderstanding or non-adherence to the specific steps and exposure time for performing hygienic hand disinfection by some of the samples from the hands of dentists that we studied.

The obtained suboptimal results point us to the need to increase the knowledge and commitment of dental personnel in the decontamination of hands before manipulations – a basic component in the complex of the “standard precautions”.

Some dentists do not strictly follow the established rules for hygiene and hand disinfection. Suboptimal disinfection practices create prerequisites for the persistence of microorganisms on the skin. Teamwork with a dental nurse is of crucial importance for the prevention of microbial contamination of the hands of dentists.

Good dental practice requires training and control of knowledge regarding decontamination, disinfection, the correct use of personal protective equipment, etc., key elements in the prevention of infections associated with dental care.^[20,21] Postgraduate training in the prevention and control of dental care-related infections should be made mandatory, as at present it is more of a recommendation, and the emphasis of the training is mainly on students. Only through regular inspections by the authorities can the actual quality of the disinfection carried out be taken into account. In case of violations, sanctions should be imposed by the relevant regulators.