Efficacy of regular professional brushing by a dental nurse for 3 months in nursing home residents—A randomized, controlled clinical trial

Abstract Objectives The oral health of nursing home residents is poor for various reasons. Many require help for oral hygiene. Regular professional brushing by a dental nurse should improve oral hygiene. This study aimed to determine the efficacy of regular tooth brushing by a dental nurse on the oral health of nursing home residents. Methods This controlled trial randomized participants (n = 50; mean age 83 ± 8 years) to brushing by a dental nurse every 2 weeks for 3 months (n = 25; test group) or oral hygiene procedures performed/controlled by nursing home staff (n = 25; control group). Personal, general and oral health, as well as various oral hygiene parameters—plaque index (PI), gingivitis index (GI), papilla bleeding index (PBI), oral hygiene index (OHI) and Volpe‐Manhold Index (VMI)—were evaluated at baseline, after initial professional dental cleaning and before last brushing. Results At baseline, oral health was impaired according to investigated indices in both groups. After professional brushing for 3 months, there were improvements in PI, GI and PBI, with significant increases compared with the control group in OHI and VMI (P = 0.017 and P < 0.001, respectively). Among the control group, the number of teeth decreased while the root caries index increased (P = 0.002 between groups). Conclusions Regular professional brushing every 2 weeks by a dental nurse can be recommended for nursing homes residents to improve oral health parameters and to help reduce root caries incidence as a basis to preserve the number of teeth. Such oral hygiene procedures will maintain and improve the oral health of nursing home residents.


| Study design and procedures
Personal health parameters were obtained and documented from the medical files of the nursing home, including care dependency level (according to German law concerning the care for the elderly, care dependency is classified into grades 1-5, from 1 = little impairment of independency to 5 = highest impairment of independency with special needs for nursing care); number of months living in the nursing home, mobility and oral hygiene practices (self-brushing with a manual toothbrush or using interdental devices (usually interdental brushes) without supervision by staff, brushing by staff with a manual toothbrush or supervision of resident's brushing with a manual toothbrush by staff); and general health parameters (including cognitive status, prescribed medications, systemic diseases). Study participants as unit of randomization were randomized to either the treatment or the control group.
A block randomization was carried out and the block size varied with a maximal number of four. Afterwards, all participants received a baseline oral examination by the cooperating dentist, followed by professional dental cleaning to reach a standardized level of oral hygiene. An additional oral examination was then performed to document cleaning success and acceptance among study participants. Subsequently, nursing home staff received in-house training regarding oral hygiene knowledge and practice guidelines for nursing home residents.
During the intervention phase, the control group received oral hygiene procedures performed or controlled by the nursing home staff (treatment as usual). In the treatment group, a dental nurse performed one brushing session every 2 weeks. Also every 2 weeks, every study participant received an oral examination; the final examination was performed after 3 months, directly before the final brushing session. A study flow chart, including dropouts, is shown in Figure 1. The dental nurse was instructed and calibrated according to the educational guidelines for dental students of the Medical Dental University of Cologne.

| In-house training
Before the start of the intervention phase and after performing professional dental cleaning for all study participants, all nursing home staff received an in-house training session regarding oral hygiene recommendations for daily practice in nursing homes. This was done to provide standardized knowledge regarding providing oral hygiene for residents, supervising resident's brushing or controlling results of self-brushing residents. Residents did not receive any additional training, since clean results were supervised by the educated staff.
First, the cooperating dentist of the nursing home held one educational session regarding the general necessity of regular oral hygiene provision to nursing home residents, and the actual oral hygiene and oral health situation in this nursing home. Second, a standardized lecture regarding oral health and oral hygiene among older people, distributed by the German Society of Gerodontology, 13 was held.
Afterwards, instructional films were shown addressing correct oral hygiene procedures, prosthetic reincorporation and replacement, and their correct cleaning procedures (https://www.bzaek.de/fuer-medien/video-audio.html, last assessed 15 November 2018). Finally, jaw models and toothbrushes were used to perform practical exercises.

| Professional dental cleaning (initial preintervention procedure)
At the cleaning appointment, all participants were visited in their rooms by the dental nurse. First, the nurse prepared the necessary F I G U R E 1 Study flow chart  Were asked to parƟcipate in the study and agreed equipment (scaler, brushes, ultrasonic cleaning device, interdental brushes) in a central bathroom. Afterwards, participants walked or were transported to the central bathroom where they were seated and the oral examination was completed. Professional dental cleaning was performed with brushes, ultrasonic cleaning, scalers and interdental brushes until a macroscopic clean situation was reached controlled and documented by the cooperating dentist. If participants refused to continue the procedure, the nurse would stop immediately (nobody did).

| Control group
Among study participants in the control group, besides in-house training of nursing home staff and pretreatment in form of the professional dental cleaning session, no other parameters were changed regarding their oral hygiene practices from before study participation. Oral hygiene practice in the control group was self-brushing with a manual toothbrush or using interdental devices (usually interdental brushes) without supervision by staff, brushing by staff with a manual toothbrush or supervision of resident's brushing with a manual toothbrush by staff.

| Brushing group
One mouth mirror, the toothbrush (Oral B Pro-Expert CrossAction, Schwalbach, Germany) and the toothpaste (Elmex Caries Prevention Professional; GABA, Hamburg, Germany) were prepared prior to the brushing session. Because of its mild taste, we assumed it would be well accepted by the participants, and 1450 ppm provided sufficient fluoride supply. Additionally, interdental brushes were available in different sizes. First, removable dentures were taken out of the mouth and cleaned. In advance, participants rinsed their mouth with water to remove food debris. The dental nurse placed residents on a chair and performed brushing from behind, supporting the resident's head with her arm. Occlusal surfaces were brushed first. For cleaning of the other surfaces, the modified Bass technique was applied. 14 After again rinsing the mouth with water, interdental brushes adapted to interdental spaces were used. The length of denture brushing did not exceed 3 minutes, and dental brushing did not exceed 3 minutes according to timeframes specified from the nursing director of this nursing home for self-brushing, while the use of interdental brushes did not exceed an additional 2 minutes.

| Oral examination
The total number of teeth and prostheses prevalence were documented before professional dental cleaning, before the first dental brushing session, and before and after the last tooth brushing session. The periodontal status according to the community periodontal index of treatment needs (CPITN) 15 should also be documented at these timepoints; because of missing participants' compliance, CPITN was only documented before professional dental cleaning.

| Dementia status
The exact diagnosis of dementia was inconsistently documented in the nursing home. For some residents, information on dementia type and grade was documented, but often this information was missing.
In this nursing home, on the day of moving in, residents are assigned to rooms according to the information "dementia yes/no," based on the available diagnoses made by a neurologist. When planning this study, we decided to use this available binary assignment for all participating residents.

| Indices
Plaque index (PI), 16 gingivitis index (GI), 17 Quigley-Hein index (QHI) 18 and the papilla bleeding index (PBI) 19 were obtained as described in detail elsewhere. The root caries index (RCI) was graded on a scale from RC1 (hard surface) to RC5 (soft surface), 20 and the dental nurse was calibrated according to earlier approaches. 21 Oral hygiene was documented by the oral hygiene index (OHI) 22 and the amount of calculus by the Volpe-Manhold Index (VMI). 23 Indices were obtained before professional dental cleaning, before the first brushing and before the last brushing session.

| Xerostomic visual analogue scale (VAS)
All participants were asked "How dry is your mouth?" independent from their cognitive status, and answers were recorded as continuous variables from 0 cm = "not dry at all" to 10 cm = "no saliva at all." 24 No objective salivation rates were investigated.

| Food debris (vestibulum, upper prostheses, lower prostheses)
Food debris in the vestibulum was documented after rinsing once with water via a six-grade scale. For participants without prostheses, the scale contained from 1 = no food debris, 2 = smallest singular pieces of food debris, 3 = vestibulum covered up to one-third with food debris, 4 = vestibulum covered up to two thirds with food debris, 5 = vestibulum covered completely with food debris and 6 = vestibulum covered up to occlusal surface with food debris. If participants had prostheses, food debris was also documented via a six-grade scale from 1 = no food debris, 2 = smallest singular pieces of food debris not reaching prosthetic teeth, 3 = prosthetic teeth covered up to 25% with food debris, 4 = prosthetic teeth covered up to 50% with food debris, 5 = prosthetic teeth covered up to 75% with food debris and 6 = prostheses completely covered with food debris up to occlusal surfaces. The maximum reached index number was documented and taken for statistical analysis.

| Data analysis
Absolute and relative frequencies are given for qualitative variables, and mean ± standard deviation (SD) are given for quantitative variables. Group differences were tested using unpaired t test or Fisher's exact test, respectively. According to the analysis pre/ post-mean and SD, mean difference with 95% confidence intervals (CI) or P-values are presented. Regarding index differences between baseline examination, examination before first brushing and examination before last brushing, Wilcoxon signed rank test and Friedmann's test with alpha adjustment were performed. All reported P-values are two-sided and considered statistically significant if lower than 5%; at Friedmann's test after alpha adjustment, P-values were considered statistically significant if lower than 1.7%. All calculations were done with SPSS Statistics 24 (IBM Corp., Armonk, NY, USA). Data were entered twice and reconciled in case of inconsistencies.

| Clinical characteristics
Fifty nursing home residents or their legal advisors provided written informed consent and participated in the study (Table 1).
Of the participants, 68% were female, the mean age was 83 (SD: 8) years, and the mean time spent living in the nursing home was 8 (SD: 8) months, with a care dependency level of 3 (SD: 1). All residents had medical and dental health insurance. Dementia was diagnosed by their neurologist in 70% of participants, 84% were mobile, and they used 8 (SD: 5) prescribed daily medications, while 5 (SD: 2) comorbidities were documented from the medical files. Overall, 81% of study participants reported that they would brush their teeth by themselves, 73% with and 100% without diagnosed dementia. However, participants with dementia received help or supervision by the nursing home staff.
Regarding the dental clinical examination, participants had 17 (SD: 9) remaining teeth, the RCI was 1.5 (SD: 1.6), and 78% suffered from periodontitis. The mean xerostomic VAS value was 1 (SD: 2). 14% of participants had total removable prostheses of the upper or lower jaw, 48% had partial removable dentures, and 84% had fixed prosthodontics (Table 1). In demented residents, the mean PI was 2.7 (SD: 0.4), without any difference compared to non-demented residents 2.4 (SD: 1). There were no differences in clinical characteristics between intervention and control group.

| Differences between residents with and without dementia
Residents with and without dementia showed differences in base-   Table 2 illustrates the changes observed in oral health over 3 months.

| Oral health indices
At baseline, mean indices were high in all patients. Two weeks after professional dental cleaning in all participants, but before the first interventional brushing, the indices were similar or had been reduced.
After 3 months of professional brushing, there were significant reductions compared with baseline in PI (P = 0.027), GI (P = 0.008), OHI (P < 0.001) and VMI (P < 0.001). In the control group, significant reductions compared with baseline were recorded for GI (P = 0.013), OHI (P < 0.001) and VMI (P < 0.001). Significant between-group differences were noted for OHI before last brushing (P = 0.017) and VMI before last brushing (P < 0.001), in favour of the intervention group ( Figure 2).

| Vestibulum index
Regarding the investigated food debris values, no differences could be shown between treatment and control groups, nor between different time points during the study (Supplementary file 1). TA B L E 2 Investigated oral health indices at baseline, before first brushing and before the last brushing session Brushing group, mean (SD)

F I G U R E 2 Mean Oral health index (OHI) and Volpe-Manhold
Index (VMI) values at baseline, before first brushing and before the last brushing session. *P < 0.017 after alpha adjustment; BFB, before first brushing; BL, Baseline; BLB, before last brushing

| D ISCUSS I ON
Our hypothesis was that regular professional brushing would be efficient in maintaining or improving individual oral health status.
Accordingly, we have shown the beneficial effects of regular professional brushing every 2 weeks by a dental nurse for 3 months on oral health parameters such as plaque index, gingivitis index, oral hygiene index and Volpe-Manhold Index. We even provide some evidence of effects on long-term parameters such as the number of teeth and the incidence of root caries. Our findings agree with those from other studies, which show that regular application of oral hygiene methods, possibly combined with fluoride application, can be successful among nursing home residents to improve oral health. 1,25,26 In a study by Ekstrand et al 27  oral hygiene, independent of whether remotivation was performed by a dentist or staff educated in dental hygiene and even when no remotivation was performed. In our study, there was also improvement in oral hygiene parameters in the control group, and there is a question whether the success in oral hygiene parameters might be due to the Hawthorne effect 28 or at least be influenced in both groups: that is knowing they are involved in a study might lead to better brushing/supervising by staff but also by residents during the 2 weeks between brushing sessions. Also, the implementation of in-house training-if seen as another intervention-may partly explain these improvements among the control group. However, the staff's interest in this training was very low; only one training session with a study duration of 3 months took place, and there were no changes regarding other parameters such as daily workflow and available time slots for oral hygiene or responsibilities. Thus, we doubt that these effects might have had an impact on the results.
Our findings suggest a small difference regarding root caries development, shown by the RCI, and number of teeth over the short study duration of 3 months, a finding that seems surprising and might be regarded as coincidental due to the small number of teeth lost in the whole population. On the other hand, tooth loss while living in a nursing home is a well-known, quickly-occurring event and our result might cautiously be considered evidence of long-term effects of oral hygiene on parameters such as the number of teeth and root caries incidence. Regularly performed oral hygiene provision not only helps to maintain good oral hygiene but ensures regular supervision of oral health. This additional effect might also lead to reduced tooth loss by early detection of teeth with treatment needs. Certainly, one might ask if it is necessary to have additional staff to brush teeth.
Other studies have reported that in-house-solutions might include greater time provision and better training for care staff. 29  We therefore conclude that with high amounts of oral biofilm in this special patient population, the QHI might be an unnecessary parameter for future studies.
In our study, the xerostomic burden was very low, especially compared to other older populations. 30 and 27%-30% in medicated people (a statistically significant higher proportion than in non-medicated populations), 33,34 these results do not seem reliable in light of the high number of residents diagnosed with dementia in our study. In addition, even though statistically significant differences between groups were reached, results were not of clinical relevance. However, when planning the study, it was unknown how many participants would be diagnosed with dementia, and therefore, this VAS was included. If we assume that more participants suffered from xerostomia or hyposalivation, this might also have influenced the differences in root caries that could be reported in our 3-month study period.
There is and will be much discussion regarding the topic of delegation and task reallocation, both issues that have become increasingly relevant in medicine and dentistry. 35 with an oral health assessment that can control oral health and any problems that may occur. Obviously, quality assurance by a dentist in Germany is mandatory since the responsibility of the dentist cannot be delegated.
There are limitations to our study. Firstly, the 3-month study duration is insufficient to provide results regarding long-term efficiency. Furthermore, only one dental nurse provided all services to the nursing home residents. Regarding the external validity of this data, there might be person-dependent differences in quality regarding the treatment success achieved. On the other hand, with the same dental nurse performing all examinations, inter-examiner differences were eliminated. Although the dental nurse in the whole-study procedure was not blinded, the dentist performing all clinical oral examinations was supposed to be blinded.
However, due to possible conversation with the residents before and after the examinations, blinding could not always be guaranteed, which is a considerable risk of bias. Also, there might be differences between the test and control groups that were not investigated in this study, such as equipment, practices, outcome quality and daily cognitive condition of residents, which may be a potential risk of bias that should be taken into account when interpreting results. Practical experience in our study showed that residents or their caregivers or legal advisors were very positive about the study and all but one person that we asked to participate gave written informed consent. At almost every session, the first question raised was regarding costs. If residents had to pay for the procedures, there might be less enthusiasm to participate in these cleaning sessions; therefore, regarding the external validity we described an optimal scenario that might not be transferrable to a real-life situation. There is a need for further prospective longitudinal research to better evaluate oral hygiene strategies, including different approaches regarding their feasibility and effectiveness to maintain the best possible oral health in residential care setting.

| CON CLUS IONS
Regular additional professional brushing every 2 weeks by a dental nurse may be recommended for nursing homes residents to maintain and improve oral hygiene parameters as possible basis to preserve the number of teeth and reduce root caries incidence. Such oral hygiene procedures may help to maintain and improve oral health of nursing home residents.

| Scientific rationale for study
The oral health of nursing home residents is poor for various reasons. Many require help for oral hygiene.

| Principal findings
Regular additional professional brushing every 2 weeks by a dental nurse can be recommended for nursing homes residents to improve short-term oral health parameters and to help reduce root caries incidence as a basis to preserve the number of teeth.

| Practical implications
Such oral hygiene procedures will maintain and improve the oral health of nursing home residents.

ACK N OWLED G EM ENTS
We thank Dr. S. Kottmann as the attending dentist in the nurs-