Dialysis patients are often found to have less saliva and alterations of the composition, often resulting in hyposalivation or xerostomia (Jover Cerveró, 2008; Kaushik et al., 2013). Under dialysis, not only systemic infections but also oral diseases such as caries, gingivitis and periodontitis are favored (Ariyamuthu et al. 2013). At the onset of dialysis, dental and periodontal status is comparable to systemically healthy individuals but worsens with increasing duration of dialysis (Bayraktar et al., 2007). Periodontal diseases and poor oral hygiene status are found more frequently than in healthy controls (Bhatsange & Patil, 2012). In hemodialysis patients, saliva production is decreased with and without salivary stimulation (Kaushik et al., 2013). A recent meta-analysis showed that chronic kidney disease patients presented a lower salivary flow rate, and it was also verified that hemodialysis can increase the salivary flow rate of these patients. It is concluded that there is a need for customized clinical planning of dental care (Rodrigues et al., 2022).
All patients we studied reported xerostomia, and sialometry did not measure normal saliva secretion in a single patient. Out of 139 patients initially interviewed, 53 patients (38.1%) reported that they suffered from dry mouth, which is very consistent with data from the literature (Cunha et al., 2007). Of these, 44 patients gave informed consent to participate in this study.
The overall dental health of dialysis patients is rather poor and requires greater attention. Common findings include gingivitis and increased dental plaque accumulation (Klassen & Krasko 2002).
Sufficient dentures of the maxilla were present in 39.5% and of the mandible in 23.8% of the patients in both examined groups. All of them exhibited poor denture hygiene.
Mouth dryness favors the occurrence of other problems in the oral cavity. In both peritoneal dialysis and hemodialysis, an increased dental plaque index is found (Bayraktar et al., 2008; Altamimi et al., 2018), which worsens with the duration of dialysis (Atassi, 2002). Under hemodialysis, increased tongue coating is observed in addition to dry mouth, often associated with taste changes (Kho et al., 1999).
A high frequency of periodontitis teeth with a high severity of periodontitis has been documented in hemodialysis patients (Altamimi et al., 2018). Patients with chronic periodontitis during hemodialysis showed a generally higher mortality than those without this concomitant disease, although this was not confirmed in multivariate statistical analysis, possibly due to insufficient patient numbers (de Souza et al., 2014; Palmer et al., 2015; Almeida et al. 2017).
In any case, we observed a regression of inflammatory changes only in the verum group, which may be due to the long-lasting coating effect of the oral hygiene gel on mucosal irritation and gingival inflammation. The number of teeth exhibiting gingivitis and shallow periodontitis dropped from 7.56 to 4.76 (gingivitis) and from 9.00 to 8.35 (P1 shallow pocketing) because of the improved plaque control by the subjects and the mechanism of action (MOA) of the gel lasting for hours at tooth surfaces and at oropharyngeal mucosal surfaces as a protective bio-layer.
In long-term haemodialysis of 6.7 +/- 5.6 years, gingival and periodontal inflammatory reactions correlate with quality of life, both from physical and psychological aspects. Oral health-related quality of life, assessed with the Short Form 36-Item Health Survey, could be improved by targeted intervention with periodontal treatment (Veisa et al., 2017).
Hemodialysis seems to discourage patients from visiting their dentist, resulting in a high need for treatment (Xie et al., 2014). The majority of patients only visit their dentist when they have complaints, and not all dentists are aware of the oral health-related needs of dialysis patients (Ziebolz et al., 2012).
Patients with chronic renal failure on dialysis and with the symptom of dry mouth often also present with other oral diseases. Therefore, a detailed medical and dental history is required. The measurement of the saliva flow rate is useful, and corrective measures of hyposalivation may prevent oral diseases (Plemons et al., 2014).
Strategies for treating xerostomia are aimed at alleviating symptoms and their consequences. They include stimulant pharmaceuticals and saliva replacement therapy with oral moistening agents (Daladom et al., 2016; Yu et al., 2016). Rinses with licorice water (Yu et al., 2016) or Aloe vera (Bin Mohsin et al., 2017) were also reported to be beneficial in hemodialysis patients.
The patients in the present study showed a very beneficial effect of the oral care gel application, as the dry mouth that initially existed in more than half of the patients during dialysis was significantly reduced after four weeks. The study showed that consistent dental care and oral hygiene with suitable products led to a highly significant reduction in xerostomia, plaque accumulation and the number of gingivitis teeth. Not only objective parameters such as dental plaque index SLI, number of gingivitis teeth and shallow pocketing according to the index GPM/T, denture hygiene index DHI or tongue coating but also subjective perceptions such as frequency of dry mouth, dry mouth on dialysis or oral health-related quality of life (OHIP-14) were significantly improved. Thus, even in chronic and terminally ill patients, dental care and oropharyngeal gel improve oral health-related quality of life.
Xerostomia is a common problem in end-stage renal disease. It has also been demonstrated in the present study that this subjective feeling of dry mouth is often associated with hyposalivation in dialysis patients. Factors that are important for the development but cannot be influenced are gender, possibly age and type of dialysis. Medication - dry mouth is a major side effect of many medications - can also only be adjusted within a narrow range. The performance of dialysis is associated with considerable psychological problems for the patient and requires an adjustment of the entire lifestyle, including a restriction of the amount of drinking. The problems associated with xerostomia are usually not considered significant by the dialysis team and are also not considered a priority by the patient. Therefore, the willingness to consistently perform and optimize oral hygiene is also not too high. Daily oral care should also be better monitored by the dialysis team, with a specially organized collaboration between the dialysis facility and dental institutions producing favorable results (Yoshioka et al. 2015).
The rather low impact of oral health on quality of life according to the OHP-14 data with 7 items and 14 questions is mainly due to the psychological status of patients under hemodialysis. They are under the permanent supervision of nephrologists, and consequently, their health behavior is dominated by chronic kidney disease. However, a professional oral hygiene programme contributes to a slight increase in OHIP-14-related quality of life. Even more importantly, the motivation of taking more self-care using a long-lasting, saliva-stimulating and fluoride-containing oral hygiene gel under the umbrella of dental professionals’ devotion contributes to psychological comfort and to the prevention of gingival and mucosal inflammation and dental caries progression.
The intention of this study was to improve the oral hygiene status of all patients. However, the instruction and training of oral hygiene alone resulted in a limited improvement of the dental and psychological parameters. With alternative oral care products such as a gel with long mucosal adhesion and, therefore, prolonged bioavailability and a special nursing toothbrush, it was demonstrated for the first time that a significant influence on xerostomia, plaque accumulation and the number of gingivitis teeth can be achieved within a short period of time in a vulnerable group of long-term patients requiring intensive care, without the need for additional measures. The results of this study probably also apply to other vulnerable patient groups with oropharyngeal inflammatory reactions.