Dental caries is the most widespread disease in the world (1). Even though a continuous decrease in caries prevalence and experience in Polish children is observed, these levels are still very high (2). This disease has a great impact on child’s life, results in lowering the quality of life, and generates many economic costs (3, 4). As caries is a lifestyle disease, the measures to prevent cavity development should be taken from the childhood. There are three main subject areas within the scope of oral health promotion, including oral hygiene, proper nutrition and the use of fluoride compounds.
Fluoride (F) has been the most efficient caries preventive agent responsible for the decline in dental caries over the last decades (5). The mechanism of its actions is multidirectional. Fluoride reduces dental plaque formation, inhibits enolase resulting in a decrease in the level of glycolytic intermediates, affects bacterial cellular membrane permeability, inhibits demineralization and increases remineralization. If F is present in the biofilm environment and the pH is not lower than 5.5, the dissolution of hydroxyapatite (HA) promotes the Fluor apatite (FA) formation. Repeated cycles of demineralization and remineralization make the outer parts of enamel more resistant to acidic environment (5, 6). Fluoride can be delivered to the organism orally and topically. Using fluoride toothpaste twice a day is considered to be a basic caries-preventive strategy. Apart from daily hygiene routine, the home-used or professionally-applied high concentration topical agents should be used in high risk populations (7). The application of a high concentration of F ions results in the calcium fluoride-like globules formation on the tooth surface. They are mineral reservoirs releasing calcium, phosphate and fluoride after acid attacks (8). For professional application the gels, foams and varnishes with a concentration between 0.5 and 5% are recommended. Currently, the indications for fluoride prophylaxis and the frequency of application depend on the individual caries risk; fluoride applications are recommended in individuals with a moderate and high caries risk (7).
Despite its positive effect on teeth, fluoride may cause an acute and chronic toxicity. An overexposure to small doses during first years of life results in enamel development disturbances named fluorosis. People living in areas where the fluoride level in drinking water is above 1.5 mg/l (1.5 ppm) are exposed to fluorosis. Currently, multiple sources of fluoride exposure, e.g. fluoride-containing dental products, fluoride enriched food and water are considered to be a reason for a growing number of children with fluorosis symptoms (9, 10). Potentially, a harmful effect may result from a daily ingestion of topical fluoride, from toothpaste or from home use gels. An acute poisoning may occur after the ingestion of one or more doses of fluoride over a short time period. First symptoms are nausea, abdominal pain, bloody vomiting and diarrhea. They are followed by headache, cardiac arrhythmia, excess salivation, collapse with paleness, weakness, wet, cold skin, shallow breathing, spasms, muscle paralysis, and tetany. The abovementioned symptoms are an effect of metabolic disorders, mainly hypocalcaemia, hyperkalemia and acidosis. Acute fluoride toxicity often results in death (11). In children, first signs of poisoning may occur after the ingestion of 1-5 mg/kg of fluorides (probable toxic dose, PTD), and the lethal dose (LD) is calculated to be between 8 and 16 mg/kg (10, 11). Even though the cases of acute fluoride poisoning are very rare nowadays (12), the possibility of overdose due to unsupervised ingestion of dental products still exists (11).
It has been proven that school/kindergarten-based programs for caries prevention with topical fluoride are cost-effective, with a high ratio of caries reduction (13-15). In Poland, since 2004, a fluoride program funded by the National Health System (NHS) for all children attending primary schools has been available. The procedures are performed in classes 1 to 6, six times in a school year (every 6 weeks) with the method of supervised toothbrushing using a 1.25% gel. The prevention is provided in areas where the fluoride levels in drinking water exceed 1 mg/l. Joining the program requires a written parental consent. The procedure is supervised by a school nurse or school hygienist. Therefore, school nurses play an important role in caries prevention with topical fluoride in Poland, but little is known about their opinions about this program as well as their knowledge in this area. The purpose of this study was to evaluate school nurses’ opinions on the topical fluoride treatment and their knowledge of acute fluoride toxicity.
Material and methods
A descriptive cross-sectional study with the use of a self-administered questionnaire was conducted from January to April 2014 on randomly selected school nurses. The survey concerned several aspects of the role of school nurse in maintaining oral health in pupils, e.g. caries prevention and first aid in dental trauma. The protocol of the study was approved by the Bioethical Committee of the Medical University of Bialystok, Poland.
Three hundred and thirty-three school nurses were selected from the internet database of the Central Statistical Office of Poland. The following assumptions were made to establish the minimum sample size for the evaluation of the role of school nurses in caries prevention: the number of school nurses based on data from the Polish Ministry of Health to be about 8,000, the percentage of nurses whose duties include the application of topical fluoride (estimated sample size) based on a pilot study to be 95%, the confidence level 95%, maximum error 5%. The minimum sample size was estimated to be 72 nurses. All participants received a questionnaire with a pre-paid return envelope, notes on the aim of the study and a participation consent form.
A structured self-administrative questionnaire was tested in a pilot study on 37 school nurses. After the pilot study, one question about the time of eruption of primary and permanent teeth was removed because it was not relevant to the study. The final questionnaire comprised questions concerning the duration of employment as school nurse, the education level, the work location type, previous training on caries prevention, actions taken at school, and cooperation with dentists. The questionnaire contained also a part concerning the topical fluoride application program; this part was completed by the nurses who accomplished the NHS program. Questions regarded the percentage of pupils having fluoride prophylaxis, their opinion about the effectiveness and safety of fluoride application and 5 questions evaluating nurse’s knowledge of fluoride toxicity. The knowledge was assessed by counting points for every correct answer. Due to two questions in multiple response type, the maximum number of points was 12.
Since 164 nurses responded to the survey, the response rate for this study was 49.25%. The duration of employment as school nurse varied (from 1 year to 43 years), but the majority of nurses had a long experience, with the average period of 23±9.1. A large number of respondents had secondary education; only 39 (23.8%) persons had a university degree - there were 20 nurses with a Bachelor’s degree and 19 with a Master’s degree. The location of nurses’ working place was as follows: city over 100 000 – 45 (27.4%), town up to 100 000 – 70 (42.7%), town up to 20 000 – 28 (17.1%) and village – 14 (8.5%). Six nurses did not answer the question about their education and seven missed the question about the working place.
Only 10 (6.1%) nurses declared that oral health was not included in their duties and for 71 (43.3%) subjects dental issues took a substantial part of their practice. They were as follows: lectures on caries prevention (135, 81.8%), topical fluoride applications (134, 81.2%), oral hygiene instructions (124, 75.1%), lectures on dental trauma prevention and screening for caries and malocclusion (7, 4.2%). A statistical analysis revealed that nurses working at schools located in big cities and villages more often than those from towns provided lectures on caries prevention and topical fluoride applications (respectively p=0.033 and p=0.021, chi2 test). Almost all respondents (95.6%) declared that pupils asked them for advice in the case of such dental problems as toothache, gum bleeding or halitosis. The statistical analysis showed that children from schools located in villages more often asked for such help than their colleagues from towns and cities (p= 0.025, chi2 test). Only 40 nurses (24.4%) established the cooperation with a dentist. Such cooperation was most frequently declared by nurses from small towns (31.4%) and most seldom by respondents from villages (10.9%), however, the results were not statistically significant. More than a half of the respondents (86, 52.4%) never attended any training concerning caries prevention. There were no differences depending on nurse education and location of school.
In the evaluated group, 134 (81.7%) nurses accomplished the NHS program for topical fluoride application in pupils. They assumed the percentage of children taking part in this program to be from 40% to 100%, on average 90.25%. Generally, nurses had a positive opinion on the effectiveness of fluoride application: 39 (29.1%) of them noticed a great value of such program and 84 (62.7%) considered its effects to be sufficient. Only 7 (5.2%) subjects thought the program did not have any influence on pupils’ dentition, and 4 (3%) nurses did not have any opinion. They also had a positive opinion on the safety of topical fluoride application. 99 (73.9%) respondents correctly answered that this method was safe subject to proper procedures and (20.2%) considered it to be totally safe. There were only 6 (4.4%) subjects who had any doubts about it, and 4 (3%) nurses were convinced that the methods involved a great risk of overexposure to fluoride.
The evaluation of nurses’ knowledge of fluoride acute toxicity revealed some gaps (Table 1). They had problems with choosing all symptoms of fluoride poisoning and proper first aid measures in acute fluoride toxicity. Only a half of the respondents knew the probable toxic dose of fluoride and almost one fifth of the respondents did not know the concentration of fluoride in gel they used. The average number of points obtained by the nurses was 6.29±2.6. The statistical analysis showed that the nurses with secondary education had a significantly lower level of knowledge (5.9±2.55) than the respondents with higher education, respectively Bachelor’s and Master’s degree, 7.29±3 and 7.6±2.16 (p=0.019, the Kruskal-Wallis test). There were no differences in the level of knowledge depending on location of school and participation in training on caries prevention (Tab. 2). However, the knowledge was associated with nurses’ opinions about the effectiveness and safety of fluoride treatment. Nurses who were not aware of a potential harmful effect of fluoride and those with a negative opinion about the effectiveness of the fluoride program at school had a statistically significantly lower level of knowledge (Table 2).
* multiple-response question.
* Kruskal-Wallis test
Apart from home, healthy behaviors should also be introduced and developed at school. A motivating influence of school with regard to oral health also reaches, through children, the families and local communities. School nurses may be promoters of oral health behaviors and providers of caries prophylaxis (16). Almost all investigated nurses included oral health topics in their duties. They discussed the role of hygiene and diet in caries development, instructed pupils how to brush teeth and provided the fluoride topical treatment. Moreover, almost a half of the respondents declared that caries prevention took a substantial part of their work time with pupils. Also children, especially from rural locations, felt that the school nurse was the appropriate person to ask for an oral health consultation.
The school-based oral hygiene programs may be effective in improving oral health (17, 18). Extensive evidence points to a high effectiveness in dental caries prevention by a regular use of fluoride preparations in the school environment, which was confirmed by the opinion of evaluated nurses. The advantages of such prevention include primarily an easy accessibility to the children and the possibility to regularly perform the procedures. The Polish school-based fluoride program is addressed to all children attending primary schools. However, the latest research by the Mother and Child Institute (19) revealed that a large group of school nurses (above 1/3) had difficulties in performing the fluoridation in pupils. Nurses most frequently report the reluctance of pupils to take part in the procedures (68.8%), difficulties in obtaining toothbrushes (52.9%), difficulties related to excusing pupils from class for the time of fluoridation (29.4%), difficulties resulting from the lack of place for the storage of toothbrushes (17%) (19). In our study, the mean percentage of pupils taking part in the program constituting more than 90% of the school population was significant. However, in several cases the nurses declared that less than a half of the pupils took part in the fluoridation. The refusal of parents to give consent to the participation of their child in caries preventions procedures at school may be due to numerous reasons: the lack of indication for fluoridation in individuals with a low risk of caries, the lack of parents’ awareness of advantages of this procedure, the lack of trust in public healthcare as well as the avoidance of preparations containing fluoride. According to the study of Hendaus et al. (20), many parents are not sure of the safety of fluoride preparations used in children. Therefore, it is important that the nurses are convinced of the safety of using fluoride prevention and are able to give explanations to parents being anxious about such procedures. It is particularly important in the context of numerous movements against the use of fluoride (21). In our study, less than 6% of nurses themselves had doubts about the safety of high concentration of fluorides. The majority of nurses correctly believed that the proper procedure guaranteed its safety.
In fact, the risk of hazardous effects of fluoride ingestion is very low in school-based programs, but the staff responsible for the application of gels or varnishes should be familiar with the symptoms of acute toxicity. We revealed the gap existing in this area. Many respondents did not know the level of fluoride in drinking water despite the fact that it is an important aspect of indications for the topical application of fluorides. In areas where the optimal level of fluoride in drinking water (0.8-1.2 ppm) is exceeded, there is no indication to apply fluorides topically. An acute fluoride poisoning has many symptoms, but evaluated nurses were not able to identify all of them. Moreover, less than a half of the respondents knew that the administration of milk is the first aid for a victim.
It has to be stressed that such gaps in knowledge could be expected. Golinveaux et al. (22) found that pediatric nurses were not able to correctly answer the questions related to the hazardous effect of fluoride ingestion. The lack of knowledge of fluorides was also found in dental staff, even in dentists (23, 24). It is obvious that nurses need to acquire knowledge to become competent and skilled to take action against caries. A study on pediatric nurses showed that gaps were improved by the interdisciplinary, multifaceted education (22). We found that the level of knowledge was dependent on education, to the disadvantage of respondents who did not have a university diploma. Unfortunately, most Polish school nurses have only secondary education. The lack of knowledge corresponded with the conviction of complete safety of fluorides in children, which may result in less supervision of the children during the procedure.
Our study revealed that the cooperation between school nurses and local dentists was insufficient and there was no obligatory training for them with regard to the application of topical fluorides and other aspects of caries prevention. It seems that it is time to call for action to prepare an educational program for school nurses to help them with their role as oral health promoters. New media such as the Internet can be used for the communication with nurses to save their time and effort.