The search strategy covered 1,014 articles: 689 from Pubmed and 325 from Cochrane Library. After applying the eligibility criteria, five articles were selected for our review (Fig. 1).
According to these criteria, the articles selected for our systematic review had the following levels of evidence and degrees of recommendation (table 2).
Of the 5 studies selected for this systematic review, two were carried out in Europe 9, 20, two in Asia 21, 22, and one in Australia 23.
All the works have a very significant sample size: Poisson et al., 9 159 patients, Gerritsen et al., 20 355, Chen et al., 21 120, and that smallest, Murray et al. 23 and Nakayama et al., 22 with 89 and 50 patients, respectively, making a total of 773 patients.
Although only two studies 20, 21 specified the age range of the patients, the average age of all participants in the studies was older than 70.
In three studies 9, 20, 21 the proportion of women in the sample was higher than that of men. If look at the total number of participants in the papers included in the review, the proportion of women who participated in the studies was higher (1:1.6 male to female ratio), which can be explained by the greater life expectancy that often accompanies the female sex.
The study of Gerritsen and co-workers 20, took as sample a group of elderly subjects from three retirement homes, while Chen et al. 21 studied subjects from a geriatric medical centre and Murray et al. 23 3 rehabilitation centres for patients who had suffered a cerebrovascular accident (CVA). Poisson et al. and Nakayama et al. 9, 22 developed their studies in hospitals; while Poisson et al. (Poisson et al., 2014) worked in the geriatrics area of a hospital. Nakayama et al. 22 focused on patients suffering ALS (Amyotrophic Lateral Sclerosis) with nasogastric and artificial respiration. None of the selected studies specify whether they were in public or private centers.
3.2. Causes Of Admission Of Patients
Except for Murray et al. 23 and Nakayama et al. (Nakayama et al., 2017), who worked with very specific types of patient (patients in rehabilitation after CVA and patients with ALS, respectively), none of the studies specified the reason for admission to the centres, although Gerritsen et al. 20 and Chen et al. 21 gave a general outline. In particular, Gerritsen et al. 20 specified that 47% were in the residence for somatic reasons and 53% for psychogeriatric reasons, while Chen et al. 21 pointed out that the main diagnoses at admission of their sample were pneumonia, sepsis, idiopathic fever and infection of the urinary tract.
Two of the studies 22, 23 did not specify the length of the stay in the institution, but, from the information provided in the articles we understand that all studied patients stayed for at least 7 days 21, 23, while the longest times were by those mentioned by Gerritsen et al. (Gerritsen et al., 2015) (more than two years). Therefore, the longest stays were those mentioned in the only study carried out in retirement homes.
Three of the 5 studies 9, 21, 23 specify at least part of the systemic pathology that participants had. The remaining two 20, 22 did not mention whether the patients in their studies suffered any other pathologies beyond those specified as the time of admission: somatic or psychogeriatric reasons in the case of Gerritsen et al. 20, and ALS in the case of Nakayama et al. 22. In the study of Poisson et al. 9, 74.2% of the patients suffer from some sort of cognitive problem; Murray et al. 23 mentioned only comorbidities derived from the CVA suffered by patients (aphasia, apraxia, dependency...) and Chen et al. 21 describes the degree of dependence of their patients (total dependence (45%), severe (35%) and a slight (20%)), along with the more common pathologies such as Diabetes Mellitus (58.3% of patients) and high blood pressure (77.5%). However, the most striking thing in these studies was the number of patients who had some sort of cognitive problem or degree of dependence that made them vulnerable to not receiving good oral care (Table 3).
None of the studies evaluated the medication that the participants were taking, which could be associated with the state of their oral health. Nakayama et al. 22, who measured the salivation index of their participants, only took into account that none of the patients in the study were following any treatment that would affect their salivary flow (radiotherapy or botulinum toxin).
Oral Health And Hygiene
Regarding the oral health of the participants of the various studies, it is concluded that, despite using different rates of assessment, only Poisson et al. 9 and Nakayama et al. 22 used the DMFT index (Decayed, Missing, Filled Teeth). However, the vast majority of patients in all the studies have poor oral health and, although only Gerritsen et al. 20 specified so, we understand that they are also in great need of treatment.
As regards oral care measures, only one study 9 does not mention that subjects follow any kind of oral hygiene protocol. Gerritsen et al. 20, mention that patients in the caring homes have dental care 16 hours a week and 8 hours of oral hygiene. This is probably why new patients had greater need of treatment than long standing residents (although this relationship was only clear in the group of edentulous patients admitted for psychogeriatric reasons, possibly because having no teeth would make it quicker and easier care for them, while the same patients could receive special attention because of their mental condition). Nakayama et al. 22 describe the protocol followed by nurses twice a day, in which they paid attention to both the hard and soft tissues. However, we should not forget that, patients who participated in the study by these authors suffered from ALS, which, probably meant that they followed a special protocol – even though such care should be considered normal and minimum for anyone. Chen et al. 21 indicated that patients’ oral hygiene is the responsibility of the nursing staff, but does not specify any guidelines or frequency of the same. What it does mention is the improvement shown with the intervention: hygiene measures twice a day (brushing and rinsing) for the three parameters which were taken into account (halitosis, plaque and state of mucous membranes), without significant differences between the three types of rinses used for the different groups (chlorhexidine, saline solution and boiled water), except in case of halitosis during examination on the 7th day, when the best result was seen in the group that used boiled water as a rinse.
In the case of Murray et al. 23 it seems that patients only receive brushing in the morning but that, due to the hygiene guidelines applied during the study (brushing with toothpaste after breakfast and dinner, and rinses with water after the main meal, with assistance of the staff if necessary), most of the patients with dysphagia improved their oral situation (patients without dysphagia also improved, but not significantly). In addition, the authors established a relationship between being independent and better oral situation. Therefore, there was an improvement in the oral health of patients in the two only studies which followed new oral hygiene guidelines during the study and reassessed the oral situation of patients 23.
Only the studies of Poisson et al. and Gerritsen et al. 9, 20 were supervised by dentists (Table 4).
In general, in the studies included in the systematic review 9, 20-3 we see that the attention that should be paid to hygiene and oral care of patients is simply not carried out and that by implementing measures which, at present, are considered basic to maintain good oral health, the staff of these facilities could improve oral conditions of much of this population group.