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Introduction: Researchers who study the problems of Internet addiction point out that this dependence is often co-morbid with symptoms of a variety of pathological disorders, including anxiety, depressive, somatization, and obsessive-compulsive disorders. The goal of this study was to compare the severity of psychopathological symptoms in individuals at risk of Internet addiction (according to Young's criteria) and those not at risk of developing this addiction with respect to gender and place of residence (urban vs. rural)., Material and Methods: The study included a group of 692 respondents (485 females and 207 males). The average age of the participants was 20.8 years. 56.06% of them lived in urban areas and 43.94% in rural areas. The following instruments were used: a sociodemographic questionnaire designed by the authors, Young's 20-item Internet Addiction Test (IAT, Polish translation by Majchrzak and Ogińska-Bulik), and the "O" Symptom Checklist (Kwestionariusz Objawowy "O", in Polish) by Aleksandrowicz., Results: Individuals at risk of Internet addiction showed significantly more severe pathological symptoms than the individuals who were not at risk of this addiction. There were differences in the severity of psychopathological symptoms between people at risk of Internet dependence living in urban and rural areas., Conclusions: Individuals at risk of Internet addiction were found to be characterized by a significantly higher severity of obsessive-compulsive, conversion, anxiety, and depressive symptoms. Persons at risk of Internet addiction who lived in rural areas had significantly more severe psychopathological symptoms, mainly obsessive-compulsive, hypochondriac and phobic, compared to their urban peers.

Introduction and Objective: Obstructive sleep apnea (OSA) is characterized by at least 5 ten-second-long episodes of apnea or hypopnea, per hour of sleep. This disease may lead to severe, life-threatening complications. Therefore, risk analysis and its influence on disease intensity is crucial for proper implementation of preventive treatments., Objective: To determine the relation between the intensity of OSA expressed in Apnea-Hypopnea Index (AHI), and the anterior-posterior diameter of upper airways at the levels of soft palate and tongue base., Material and Method: Medical records of 41 patients with sleep apnea (AHI>4) diagnosed through polysomnographic examination obstructive were used for the study. The data consisted of: age and gender, polysomnographic examination results (AHI), lateral cephalogram with cephalomertic analysis, together with measurements of the upper and lower pharyngeal depth according to McNamara. Statistical analysis was carried out in accordance with Pearson's r correlation coefficient test (Statistica 8.0 software package)., Results: Analysis of the influence of upper airways diameter on the intensity of OSA showed that the value of upper Airways diameter at the tongue base level had no statistically significant impact on the value of AHI (p=0.795). However, a statistically significant impact of the value of upper airways diameter on the AHI value (p=0.008) at the soft palate level was observed. Patients with OSA have narrowed upper airways diameter. The value of AHI increases with the decrease of upper diameter and is not dependent on a lower diameter value. Patients with a decreased upper airways diameter should be informed about potential breathing disorders during sleep.

Epidemiological studies of tick-borne encephalitis (TBE) conducted in the Swietokrzyskie province (south- eastern Poland) in 1996-2006 demonstrated an increase in the number of registered TBE cases in the last 6 years of the study. The highest risk of TBE virus infections occurs in the summer-autumn period (seasonality factors 96.55% and 248.28%), i.e. in periods of the highest Ixodes ricinus activity in this region. An increased number of registered TBE cases were noted in the regions which provide ticks with favourable habitats and, simultaneously, where the TBE diagnosis and treatment for the inhabitants are more efficient. The increasing tendency in TBE incidence observed even in the non-endemic regions of the Swietokrzyskie province indicates the necessity of education in tick-borne disease prophylaxis and the need to elevate the level of public health care. Differences in the density and activity of various developmental Ixodes ricinus stages were observed in 4 localities in diverse biotopes located at different altitudes a.s.l. This justifies the necessity of environmental monitoring of the threats posed by ticks in various habitats, especially in those frequently visited by humans.

Yhe aim of the study was the investigation of the dynamics of LB prevalence in central Europe over a 12-year period and estimation of its dependence on the environmental factors and on the level of medical services. Epidemiological studies of LB were conducted in the years 1996-2007 in 9 regions of the Świętokrzyskie province in south-eastern Poland (Central Europe). On the basis of patient registry, the incidence, prevalence in various months of the year, the mean number of cases in various seasons and the seasonality factors (SF) of LB were calculated. Between 2000-2007, an increased borreliosis incidence was observed in the study area. During the entire study period, the highest incidence (25.93 and 30.66) was observed in the regions with the highest density of Ixodes ricinus ticks - vectors of Borrelia burgdorferi spirochetes, and where the inhabitants are offered the best available LB diagnosis and treatment due to a sufficient number of doctors (r = 0.74) and all medical personnel (doctors, nurses and diagnosticians) (r = 0.89). The highest LB incidence was present in the summer and autumn seasons (SF = 113.25 and 155.18%) in the areas with the highest density of nymphs and adult I. ricinus ticks (> =19/1 h of sampling). Improved standards of public medical care as well as environmental monitoring of tick threat may contribute to a decrease in prevalence of LB and to its better detection.

The investigations were conducted in the Lublin province (south-eastern Poland) in areas of high agricultural and recreational value. Among the 418 patients admitted to medical clinics due to arthropod bites in the years 2003-2005, 184 people (44%) had been bitten by ticks. As shown by the research, high-risk groups include people whose stay in tick habitats is connected with their occupational work (54.5%) as well as recreation and tourism (45.5%). As many as 78.7% of the patients were attacked by Ixodes ricinus ticks in forests, and much fewer (31.3%) in other habitats located in urban and rural areas. In one case, a Dermacentor reticulatus female was attached to the skin. Ticks were most commonly located on the upper (28.8%) and lower (27.2%) extremities, and on the abdomen (15.8%). Local skin reactions (57.6%) with predominance of erythema were the most prevalent. Combined local and systemic symptoms were reported less frequently (20.1%). The general symptoms were headache (10.8% of patients), fever (5.4%), lymphadenitis (5.9%) and arthralgia (4.3%). No lesions produced by tick bites were reported in 22.3% of the patients. Field studies conducted in 2003-2004 demonstrated that I. ricinus is a common species in the southern part of the Lublin province, where the density of nymphs and adult forms in various localities during the period of peak seasonal activity (in May) ranges from 18.5-26 specimens/1 h of collection. Two tick species, I. ricinus and D. reticulatus, occur in the northern part of the province. The density of I. ricinus nymphs and adult forms as well as D. reticulatus adults is in the range of 2.5-42 specimens/1 hr of collection and 19.5-64.0 speciments/1 hr of collection, respectively. Due to the high risk of tick attacks in the study area, there arises the necessity to permanent the monitoring of ticks numbers and tick-borne diseases.

Infection with T. gondii is particularly dangerous for pregnant women as it may lead to the transplacental passage of the parasite. Currently, congenital toxoplasmosis is the second most frequent intrauterine infection. The risk of transmission of T. gondii to the foetus varies throughout the world and ranges from 0.6-1.7/1,000 of pregnant women. The consequences of congenital toxoplasmosis are multifarious. On the basis of current literature review, the authors discuss the epidemiological and clinical aspects of toxoplasmosis in pregnant women, the influence of climatic and environmental factors that may lead to an increase in T. gondii infections in humans, particularly in pregnant women, and the principles of prophylactics against T. gondii infections in those women.

Lyme disease (borreliosis) is an infectious disease caused by the Borrelia spirochaetes, usually transmitted to humans by the Ixodes ticks. It is manifested by a wide spectrum of clinical symptoms varying according to the time elapsed from the infection. The paper describes orofacial symptoms of the disease in a woman who has suffered from a chronic borreliosis for 3 years. Multiorgan clinical manifestations of borreliosis might occur in the masticatory organ and this fact should be taken into consideration in the differential diagnosis of pain by medical and dental practitioners.

Ticks are very important vectors of pathogenic microorganisms (viruses, bacteria, protozoans), which may induce serious contagious diseases in humans and in farm animals. The aim of the study was to determine the coincidence of 3 pathogens: Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Babesia microti in Ixodes ricinus ticks in south-eastern Poland and to estimate the degree of infection with each of the examined pathogens depending on the developmental stage of ticks (nymph, female, male). The study material were 1,620 Ixodes ricinus ticks collected at 5 sites in the Lublin macroregion, showing the presence of various forest biotopes. The PCR method was used to identify DNA for B. burgdorferi and A. phagocytophilum, and the nested-PCR - for B. microti. In 1,368 (84.44%) of the 1,620 examined ticks no infections were found. Single infections were noted in 217 ticks (13.4%) and coinfections were detected in 35 specimens (2.16%). The most common was the coincidence of A. phagocytophilum with B. microti (17 infected specimens, 1.05% of the total number). A similar result was obtained for the coincidence of B. burgdorferi s. l. with A. phagocytophilum (15 infected specimens, 0.93% of the total number). Only 2 cases of the coinfection of B. burgdorferi s. l. with B. microti, which equals 0.12% of the total number, were found. Infection with all 3 pathogens was identified in only 1 female tick (0.06% of the total number).

The specific structure of dental units favours the presence of biofilm and microbial contamination of the dental unit waterlines (DUWL) water. The ability of bacteria to colonize surfaces and to form biofilm in water supply tubes, including DUWL, is a common phenomenon, which has been well documented, just as with difficulties in biofilm removal and prevention of its regrowth. Microorganisms from contaminated DUWL are transmitted with aerosol and splatter, generated by working unit handpieces. On the basis of the detailed literature review, the state-of-the art knowledge of the microflora of dental unit waterlines is presented. Most of the microorganisms isolated from DUWL are of low pathogenicity. Nevertheless, the public health significance of many of the microorganisms found in DUWL is unknown. According to current knowledge, it is not the mere presence of bacteria that is important in DUWL contamination monitoring, but their number, the presence of potential pathogens, and patients' oral cavity microflora. Numerous studies emphasize the need for effective mechanisms to reduce the microbial contamination in DUWL and highlight the risk for cross-infection in general practice, especially in view of the ever-increasing number of immunocompromised persons who present at outpatient dental clinics.

Work-related respiratory symptoms, including dyspnoea, cough, fever, tiredness and malaise, were recorded in two customs officers employed in 2 depositories of confiscated cigarettes, of which one showed signs of dampness. Microbiological sampling of the air and the cigarettes stored in a damp depository revealed the presence of potentially pathogenic fungi and bacteria and the biochemical markers of bacterial lipopolysaccharide and fungal biomass. The Penicillium species (P. simplicissimum, P. inflatum, P. commune) dominated in the damp depository, while in the other one Aspergillus fumigatus was prevalent. The patients under study did not show a specific sensitization to microbial allergens in the precipitin test, the test for inhibition of leukocyte migration and the bronchial provocation challenge, except for a weak reaction to fungal allergens in the test for inhibition of leukocyte migration. Moreover, one patient responded with subjective symptoms after exposure to inhalation of increased doses of Penicillium simplicissimum antigen. Both cases were diagnosed as a specific form of organic dust toxic syndrome (ODTS). It is hypothesized that the symptoms were evoked most probably by the non-specific action of low molecular fungal metabolites, such as mycotoxins or VOCs (volatile organic compounds), with the possible contribution of bacterial endotoxin. However, as there is no a direct proof to support this presumption, and the effects of nicotine and other tobacco constituents cannot be excluded, further studies are needed to elucidate etiopathogenesis of the disorders associated with the exposure to stored tobacco.

Bacteriological air sampling was conducted at 25 dental units during restorative treatment sessions before and after disinfection of dental unit waterlines (DUWL) with hydrogen peroxide. Air samples for determining the concentration and species composition of aerobic and facultatively anaerobic bacteria were collected with the portable Reuter Centrifugal Sampler (RCS Plus) in the dental operation area close to patient's mouth. Large concentrations of airborne bacteria in the range of 0.35-40.08 x 10(3) cfu/m(3) (median = 1.63 x 10(3) cfu/m(3)) were recorded before DUWL disinfection. After disinfection, the concentrations were significantly lower (p<0.05), ranging from 0.51-3.82 x 10(3) cfu/m(3) (median = 0.9 x 10(3) cfu/m(3)). Streptococci were most numerous among airborne bacteria before DUWL disinfection, forming 79.23 % of total isolates. The remaining isolates were staphylococci/micrococci (15.7 % ), corynebacteria (2.3 % ), endospore-forming bacilli (1.45 % ), Gram-negative bacteria (1.31 % ), and actinomycetes (0.01 % ). After DUWL disinfection, a significant decrease in the numbers of streptococci (p<0.05) and Gram-negative bacteria (p<0.01) was noted, while the numbers of other types of bacteria were unaffected. Altogether, 50 species or genera of bacteria were identified in the examined air samples before and after DUWL disinfection. Of these, 36 species or genera are considered potentially pathogenic, as a potential cause of infection, allergic disease or intoxication. In conclusion, the high pollution of dental operation area with bacteria indicates a need for use of preventive measures protecting dental staff and patients, such as DUWL disinfection that proved efficient in decrease of exposure in the present study.

Many-year studies on aerosols as an infection vector, despite their wide range, ignored dental aerosol. All procedures performed with the use of dental unit handpieces cause the formation of aerosol and splatter which are commonly contaminated with bacteria, viruses, fungi, often also with blood. Aerosols are liquid and solid particles, 50 microm or less in diameter, suspended in air. Splatter is usually described as a mixture of air, water and/or solid substances; water droplets in splatter are from 50 microm to several millimetres in diameter and are visible to the naked eye. The most intensive aerosol and splatter emission occurs during the work of an ultrasonic scaler tip and a bur on a high-speed handpiece. Air-water aerosol produced during dental treatment procedures emerges from a patient's mouth and mixes with the surrounding air, thus influencing its composition. Because air contained in this space is the air breathed by both dentist and patient, its composition is extremely important as a potential threat to the dentist's health. According to the author, insufficient awareness of health risk, working habits, and economic factors are the reasons why dentists do not apply the available and recommended methods of protection against the influence of bioaerosol and splatter. Behaviour protecting a dentist and an assistant from the threat resulting from the influence of dental aerosol cannot be limited to isolated actions. The author, on the basis of the literature and own research, characterizes bioaerosol and splatter in a dental surgery and reviews a full range of protective measures against these risk factors.

The aim of this study was bacteriological assessment of water in dental unit reservoirs--concentration and composition of the aerobe and facultative anaerobe bacterial microflora. Reservoir water samples were taken from 25 units. Bacterial flora were determined with the plate culture method. Bacteria were identified with biochemical microtests: API 20E, API 20NE (bioMérieux, France) and GP2 MicroPlateTM (BIOLOG, USA). The concentration of total bacteria isolated from one site was 201,039 cfu/ml, on average; the minimum was 22,300 cfu/ml, and the maximum - 583,000 cfu/ml. The following bacteria were identified: Gram-negative bacteria--Brevundimonas vesicularis, Moraxella lacunata, Moraxella spp., Ralstonia pickettii, Sphingomonas paucimobilis, Stenotrophomonas maltophilia; Gram-positive cocci--Micrococcus luteus, Micrococcus lylae, Staphylococcus cohnii, Staphylococcus hominis ss novobiosepticus, Staphylococcus spp., Streptococcus spp.; actinomycetes--Streptomyces albus. The prevailing bacteria were: Ralstonia pickettii (96.46%), found in all the units. Sphingomonas paucimobilis (1.32%) and Brevundimonas vesicularis (1.07%) were the next most frequently occurring bacteria. Bacteria concentration in dental unit reservoirs reached excessive values, and the bacterial flora were composed of the bacteria characteristic for water supply systems, opportunistic pathogens, and bacteria of the oral cavity flora. Continuous microbiological monitoring of the DUWL water, including application of a disinfecting procedure, is necessary.

The concentration and composition of fungal flora in dental unit waterlines (DUWL) were evaluated. For this purpose, water samples from unit reservoirs and high-speed handpieces, and biofilm samples from the waterline walls from units were collected. Subsequently, analogous samples from DUWL were taken before and after disinfection using agent containing hydrogen peroxide. In the examined samples, the yeast-like fungi Candida albicans and Candida curvata were found. The following species of mould were also identified: Aspergillus amstelodami, Aspergillus fumigatus, Aspergillus glaucus group, Aspergillus (=Eurotium herbariorum) repens, Citromyces spp., Geotrichum candidum, Penicillium (glabrum) frequentans, Penicillium pusillum, Penicillium turolense and Sclerotium sclerotiorum (Sclerotinia sclerotiorum). Before disinfection, Candida curvata and Candida albicans constituted the greatest proportion of the total fungi in the reservoirs water; in the water of handpieces--Candida albicans and Aspergillus glaucus group; and in the biofilm samples--Aspergillus glaucus group and Candida albicans. After disinfection, in all 3 kinds of samples, Candida albicans prevailed, constituting from 31.2-85.7 % of the total fungi. The application of agent containing hydrogen peroxide caused a significant decrease both in the number of total fungi and individual fungal species, which confirms the product effectiveness in fungal decontamination of DUWL.

The aim of the study was a mycological assessment of bioaerosol forming during conservative dental treatment, taking into account concentration and type of fungal microflora, and evaluation of the influence of DUWL disinfecting protocol on the fungal contamination of the bioaerosol. The research was conducted on 25 operative sites located in public dental clinics. The air contained in the space between a patient and a dentist during conservative dental treatment with the use of a high-speed handpiece was examined. Air samples were taken using the portable RCS PLUS Air Sampler (BIOTEST AG, Dreieich, Germany) and ready-to-use agar YM Strips for yeast and mould fungi culture. The volume of the sampled air was 100 litres. Before disinfection, the concentration of fungi in the collected air samples at individual operative sites ranged from 4 x 10(1) cfu/m3 to 34 x 10(1) cfu/m3. The most common species was Penicillium herquei (62.17% of the total count), followed by other fungi: Alternaria alternata - 12.68%, Penicillium roseopurpureum - 9.41%, Rhizopus nigricans - 5.93%, Aspergillus terreus - 3.89%, Geotrichum candidum - 2.25%, Aspergillus glaucus group - 2.04%, Cladosporium cladosporoides - 1.23% and Penicillium diversum - 0.41%. The concentration of Penicillium herquei at individual operative sites ranged from 0 to 34 x 10(1) cfu/m3, mean 121.6 cfu/m3, Penicillium roseopurpureum - from 0 to 11 x 10(1) cfu/m3, mean 18.4 cfu/m3 and Alternaria alternata - from 0 to 18 x 10(1) cfu/m3, mean 24.8 cfu/m3. After disinfection, like before disinfection procedures, the prevailing species of fungi were: Penicillium herquei, Penicillium reseopurpureum and Alternaria alternata, which amounted to 62.6%, 18.28% and 11.36% of the isolated fungi, respectively. The recorded levels of total airborne fungi were lower after DUWL disinfection compared to those before disinfection.

The aim of this study was bacteriological assessment of the dental unit waterlines (DUWL) biofilm - concentration and composition of the aerobe and facultative anaerobe bacterial microflora, and evaluation of the influence of a disinfecting product, Oxygenal 6, on the biofilm composition. Tubing fragments were taken from 25 units twice, before and after disinfection, and bacterial suspension of the biofilm was obtained from the samples. The bacterial flora was determined with the plate culture method. Bacteria were identified with biochemical microtests: API 20E, API 20NE (bioMerieux, France) and GP2 MicroPlate(TM) (BIOLOG, USA). Before disinfection, the following bacteria were identified: Gram-negative bacteria - Ralstonia pickettii, Pseudomonas vesicularis, Sphingomonas paucimobilis, Xanthomonas maltophilia; Gram-positive cocci - Micrococcus luteus, Micrococcus lylae, Staphylococcus cohnii, Staphylococcus lentus, Staphylococcus spp., Streptococcus spp.; Actinomycetes - Streptomyces albus. The prevailing bacteria were: Ralstonia pickettii (78.62%), found in all the units, and Sphingomonas paucimobilis (20.45%). After DUWL disinfection, Sphingomonas paucimobilis (88.79%) dominated in the biofilm, Staphylococcus spp. - 5.61% and Pseudomonas spp. - 3.74% were next most frequently occurring bacteria, and in more than a half of the biofilm samples 100% reduction of the bacterial microflora occurred. This study confirms effectiveness of Oxygenal 6 in bacterial decontamination of the DUWL biofilm.

Gram-negative bacteria concentration in water effluent from a dental unit, and in dental aerosol forming during the work of a dental handpiece, was assessed. The study was conducted on 25 dental units before and after a 2-week period of using a disinfecntant for water in dental units waterlines (DUWL). The contamination of water with Gram-negative bacteria before disinfection was 18-398 x 10(3) cfu/ml, and after disinfection, bacteria were not found. The concentration of Gram-negative bacteria in the air before disinfection was 0-23 x 10(1) cfu/m(3), and after disinfection - 0-8 x 10(1) cfu/m(3). Simultaneously, the water and air were sampled to determine bacterial endotoxin. The statistical analysis did not show correlation between endotoxin concentration and Gram-negative bacteria concentration for the water before disinfection, and for the air before and after disinfection of DUWL water. Because the number of bacteria in the water after disinfection dropped to zero, statistical methods could not be used. The performed analysis suggests that bacterial endotoxin concentration is not indicative of Gram-negative bacteria contamination. Thus, bacterial endotoxin determination is not recommended as a method of monitoring the microbiological quality of DUWL water and dental aerosols.

The quality of dental unit water is of great importance since patients and dental staff are regularly exposed to water from aerosols generated during work. The main purpose of this investigation was mycological evaluation of dental unit waterlines (DUWL). The author determined the number and species of fungi present in the water from a unit reservoir which is the source of water for a dental unit, in the water flowing from a high-speed handpiece of a unit, and in the swab sample collected from the wall of a waterline connecting a unit reservoir and dental handpieces. The following mould fungi were identified: Aspergillus amstelodami, Aspergillus fumigatus, Aspergillus spp. from Aspergillus glaucus group, Aspergillus repens, Citromyces spp., Geotrichum candidum, Penicillium aspergilliforme, Penicillium pusillum, Penicillium turolense, Sclerotium sclerotiorum; yeast-like fungi: Candida albicans, Candida curvata and other yeasts. Some of them, in certain circumstances, especially in people with immunological disorders, may be a cause of opportunistic infections. Thus, it is necessary that the DUWL should be submitted to a decontamination protocol and to routine microbial monitoring to guarantee an appropriate quality of water used in dental treatment.

Using the transmission electron microscope, the ultrastructural examination was conducted to detect the presence of bacterial biofilm on the inner surfaces of the tubing in dental unit waterlines (DUWL). Samples for examination were taken from the tubes providing water to high-speed and slow-speed handpieces, and to an air-water syringe before application of a disinfection procedure. The microscopic analysis made it possible to find the biofilm in all the tubes in the dental unit which were not pre-disinfected. In these samples, no significant differences were found between high-speed, slow-speed and air-water lines.

Dentists belong to a professional group potentially exposed to harmful biological factors which most often are infectious microorganisms, less frequently - allergenic or toxic microorganisms. The fundamental routes of spreading harmful microorganisms in a dental surgery are: blood-borne, saliva-droplet, direct contact with a patient and with infected equipment, and water-droplet infections. In this paper, the current status of knowledge on microbiological hazards in a dentist's work is presented. Groups of microorganisms, such as prions, viruses, bacteria, fungi and protozoa, to which a dentist is, or may be exposed, are discussed. Epidemiological assessment of microbiological hazards in a dentist's work was performed and the basic principles of prevention formulated. Special attention was given to microflora in dental unit waterlines, and the biofilm persisting in them, as a source of occupational hazards specific for a dentist's workplace.

The aim of the study was to determine bacterial endotoxin concentration in the water flowing from a high-speed handpiece of a dental unit and in the air contained in the bioaerosol formed during dental conservative treatment. The air was collected in the space between the patient and dentist. The study was conducted on 25 operative sites (units) and had two stages: before application of a dental unit waterline (DUWL) disinfectant and after a 2-week application of disinfection procedure. The research showed that the mean concentration of bacterial endotoxin in the water flowing from high-speed handpieces was significantly reduced after the use of a disinfectant. The mean concentration of bacterial endotoxin in the air was similar at both stages - before and after application of waterline decontamination procedure. The study showed that in dental air-water aerosol, water is the main source of bacterial endotoxin contaminating the aerosol during the work with dental handpieces. Application of a user-friendly water disinfectant to significantly decrease endotoxin concentration in the DUWL water and in the aerosol, is one of recommended methods to reduce health risk.

Microbial quality of water in a dental unit is of considerable importance since patients and dental staff are regularly exposed to water and aerosol generated by the unit. Water delivered to a dental unit by the so-called independent water system is the water coming from a reservoir which, at the same time, is an initial part of dental unit waterlines (DUWL). Thus, microbiological quality of this water is extremely important for the quality of water flowing from dental handpieces. The aim of the study was to assess microbiologically the water contained in dental unit reservoirs. Water samples were collected aseptically from the water reservoirs of 19 dental units. Results concerning microbial contamination: potable water quality indices, and detection and isolation of Legionella species bacteria, were presented. Over a half of the samples did not comply with the norms for potable water. In 63.1% of the cases, the number of colony forming units (cfu/ml) and of coliform organisms significantly exceeded acceptable values. Enterococcus was not detected in the samples of examined water. Similarly, no Legionella were found in the samples of dental unit reservoirs water. Reservoirs as water supplies and initial segment of DUWL should be subject to protocol to eliminate microbial contamination and routine monitoring to guarantee an appropriate quality of water used in dental treatment.

The profession of dentist exposes them during their work to many burdensome and harmful factors. The irrational posture adopted by dentists during their work causes discomfort and disorders of the musculoskeletal system and the peripheral nervous system. The methods and organization of the work of Polish dentists were evaluated from the aspect of ergonomics, with regard to reported by them painful disorders connected with the musculoskeletal system, with the aim of applying proper methods of treatment and prophylaxis. The study showed that dentists worked in conditions which generally produced disorders of the musculoskeletal system. As a result, the long working time in the course of a day was used irrationally from the point of view of ergonomics, which over the years of work consequently increased the number of disorders of the musculoskeletal system. Dentists must make use of various forms of treatment. The effectiveness of prophylaxis concerning the musculoskeletal system were only partly assessed by the respondents through questionnaire. Most dentists are convinced of the effectiveness of physical activity in prophylaxis which they carry out themselves.

Nitrous oxide may be used to alleviate dental anxiety and to diminish or eliminate dental pain. The benefit of nitrous oxide sedation is a cooperative and satisfied patient. By reducing the patient's perception of pain it allows them to relax and cooperate during dental procedures. However, the dental surgery personnel, chronically exposed to N2O, are at serious risk. The chronic effects of occupational exposure to nitrous oxide have long been the subject of debate. Safety standards have been established in the United States and Europe since many years. The potential detrimental action on the reproductive, neurological, haematological, hepatic and renal systems, plus the possibility of increased cancer risk have been the subject of active research, although absolute occupational effects are still uncertain. To provide a safer work-place for those at risk of exposure to waste anesthetic gases, preventive measures are recommended.

Among the numerous threats to the dentist's health there is one relating to the eye. The paper discusses the impact of selected adverse factors on the eye in connection with dental practice in the surgery.

Dental professionals are susceptible to a number of occupational hazards. Relying on relevant literature, the present paper discusses selected occupational hazards - occupational biohazards, stressful situations, and latex hypersensitivity, as well as factors leading to the musculoskeletal system diseases and diseases of the peripheral nervous system.

Using the literature on the subject, an assessment was made of the state of the oral health in rural population: dental state, periodontal diseases, state and needs for prosthetic rehabilitation. The articles presents possible causes of this state of things.