Drooling and Dental Caries in Children with Cerebral Palsy - Is There Any Link?

Introduction

Drooling is an involuntary or unintentional loss of saliva and oral contents, commonly seen in infants; however, it typically subsides by the age of two years.¹ Persistent drooling is often seen in children with intellectual disabilities or neuromuscular disorders like cerebral palsy (CP), and is considered abnormal beyond the age of four years.^2,3

Drooling is not always the result of excessive saliva production (i.e., sialorrhea).⁴ According to International consensus statements on drooling, a distinction should be made between anterior and posterior drooling for better understanding its cause and impact. Anterior drooling is defined as ‘saliva spilled from the mouth that is clearly visible’, while posterior drooling is described as ‘saliva spilling through faucial isthmus creating a risk of aspiration’.¹

Neurologically impaired children often experience excessive salivation due to inadequate oral motor control or swallowing dysfunction.⁵ Persistent drooling can lead to significant hygienic and psychosocial challenges. Maceration of the skin around the mouth and neck may result in secondary bacterial infections. In addition, drooling contributes to socially embarrassing and disabling problems. Factors that predispose drooling in children affected with CP include the degree of spasticity, reduced swallowing frequency, diminished intra-oral tactile sensitivity, and constant tongue thrusting.⁶

Drooling has been reported as a significant problem in approximately 10% to 37.5% of patients with cerebral palsy.⁷ Many interventions like oral motor stimulation, medicines, surgical procedures, have been employed to reduce drooling.^8,9,10

The severity and impact of drooling can be assessed using both subjective and objective measures.¹¹ Subjective assessment tools include Drooling Frequency and Severity Scale, and the Drooling Impact Scale, while the objective methods involve measuring salivary flow, direct observation of saliva drooling from the mouth, and the Drooling Quotient, among others.^12,13,14,15

With regard to the association between dental caries and drooling, only a few studies have investigated the relationship between the two.^2,16 Hence, the present study intended to document the relation between drooling and dental caries among children with CP.

Materials and Methods

This cross-sectional study was conducted among seventy-six children diagnosed with cerebral palsy, selected through convenient sampling from institutions and schools providing facilities for Children with Special Health Care Needs (CSHCN). The participants included both male and female children between four and fourteen years of age.

Ethical approval was obtained from Institutional Ethical Committee of Dental Institutions [GDCRI/IEC-ACM(2)/9/2018-19] [SRGCDS/2021/129] abiding to Helsinki Declaration and Clinical Trial Registration- India [CTRI/2021/03/031990], procured as part of a larger research study protocol. Both consent and assent (when possible) were taken.

Inclusion Criteria

Children diagnosed with cerebral palsy, certified by a physician or specialist aged four to fourteen years, exhibiting one or more orofacial and/or oral sensory/ motor function difficulties, as reported by caregivers and whose parents/caretakers provided written informed consent, and assent from the children whenever possible were included in the study.

Exclusion Criteria

Children who did not meet the inclusion criteria and were unable to cooperate during the oral examination were excluded from the study.

A single trained examiner, experienced in administering drooling assessments, conducted the screening of the children and interpreted the results. Based on the 1990 consortium consensus on drooling, which concluded that objective methods for assessing drooling are inadequate and that objective quantification is not required for clinical management or research, a simple subjective method - the ‘Drooling Severity and Frequency Scale’ (DSFS), was used for assessment.^2,3,12

Based on the criteria advocated by the World Health Organisation (WHO, 1997), dental caries assessment was carried out. To minimize examiner fatigue bias, approximately eight to ten children were examined per day, with assistance from parents and school teachers.¹⁷

Brief Description of DSFS¹²

A commonly used semi-quantitative tool for assessment of drooling is the Drooling Severity and Frequency Scale (DSFS). It was originally developed to measure the frequency and severity of drooling in individuals with CP and has since been applied to other populations as well. The DSFS comprises of two domains. The first domain is a five-point scale (1-5: dry, mild, moderate, severe, and profuse) that assesses the severity of drooling. The second domain is a four-point scale (1-4: never drools, occasionally, frequently, and constantly) that evaluates its frequency. The total drooling score is obtained by summing the severity and frequency subscores (ranging from 2 to 9). The DSFS is simple to administer and requires minimal time to complete.

Statistical Analysis

Descriptive statistics like mean and standard deviation for continuous variables, and frequencies and percentages for categorical data, were calculated. Spearman’s correlation coefficient was used to compare the drooling scores with the mean deft/DMFT scores [deft - decayed, extraction needed, filled teeth in primary dentition, DMFT - decayed, missing, filled teeth in permanent dentition], as the data were not normally distributed. Statistical Package for Social Sciences or SPSS (IBM SPSS Statistics for Windows, version 25. Armonk,NY:IBM Corp) was used to analyse the data, and a P value ≤0.05 was deemed to be statistically significant.

Results

The mean age of children in this study was 10.51±2.58, while the male to female ratio was 2:1. Children with spastic quadriplegia were highest in number as compared to other forms of cerebral palsy. Caries scores for both the primary and permanent dentitions, along with other demographic variables are shown in Table 1. The mean drooling scores of the study participants, as measured by the DSFS, are presented in Table 2. Tables 3 and 4 depict the correlation between drooling and caries scores in the primary and permanent dentitions, respectively.

Discussion

The assessment of drooling or sialorrhea, can generally be categorized into two main purposes: first, to distinguish children based on the severity of drooling and second, to evaluate its impact on the lives of children and their parents. Thus, interventions aimed at managing drooling should be considered effective not only when they reduce the severity of drooling, but also when they lessen its burden on parents or caregivers and improve the child’s quality of life.^2,3,11

In our study, children with spastic quadriplegia were highest in number as compared to different variants of cerebral palsy, while those with spastic ataxia were least in number. However, as this was a cross-sectional study employing a convenient sample, these findings cannot be interpreted from a prevalence point of view. In a recent study conducted among children in Pune, India, the frequency of drooling was reported to be highest in the quadriplegic CP variant, followed by diplegic and hemiplegic types.¹⁸ The severity of drooling was also pronounced in the quadriplegic group, with a significant proportion exhibiting moderate to profuse drooling. In contrast, the mean drooling severity in our study was 1.42±1.49 (dry to mild range), while the mean drooling frequency was 1.34±1.40 (never to occasionally drooling range).

A study by Erasmus CE et al., supported earlier findings that hypersalivation is not present in children with CP who experience drooling.¹⁹ The underlying cause of saliva overflow was found to be dysfunctional oral muscle control, while hyperkinetic oral movements were considered responsible for drooling in children with dyskinetic CP. Another study reported a significant negative correlation between age and both the frequency and severity of drooling.²⁰ Significant reduction in drooling frequency and severity has been achieved with tried and tested non invasive methods like oral motor exercises, oral motor facilitation with kinesiotaping, repeated muscle vibration.^21,22,23 These methods may be considered before pursuing more invasive therapeutic approaches.

Dental caries is a multifactorial disease influenced by both past and current caries experience, the presence of cariogenic bacteria, diet, fluoride exposure, salivary status, and sociodemographic factors.²⁴ Additional contri-buting factors include high-sugar beverage consumption, long-term use of oral medications with xerostomic potential, soft consistency of diet, oro-motor dysfunction, and difficulties in maintaining adequate oral hygiene.²⁵

In the present study, the mean dmft score was 1.30±3.0, and the mean DMFT score was 1.21±1.7, with the decayed component contributing more than the missing and filled components in both the indices (Table 1). No significant correlation was observed between any of the drooling parameters - drooling severity and drooling frequency and deft scores of the primary dentition as well as DMFT scores of the permanent dentition (P >0.05) (Table 3 and 4). These findings are consistent with those of a previous study in which drooling was assessed using the index developed by Blasco PA et al.,who reported that drooling itself may not predispose children with CP to dental caries.^2,3 Instead, the poorer oral hygiene seen among children who drooled, compared to those who did not, was identified as the primary contributing factor. Another study also showed no significant difference in dental caries status between children with and without drooling.²⁶

A study by Hallett KB et al., reported that children with CP who underwent sialodochoplasty had an increased risk of developing dental caries compared with those treated non-surgically for drooling.²⁷ Although no caries risk predictors were outlined in the study, an alteration to the caries-protective role of saliva was considered the likely cause. The authors recommended that children undergoing this procedure receive intensive pre and postsurgical preventive dental therapy, highlighting the importance of dental awareness as well as the protective role of saliva.²⁷ Similarly, a review article emphasized the pivotal role of dental awareness in reducing the incidence of dental caries among children with CP, regardless of the underlying cause.²⁸

Limitations of the Study

Although CP is a complex group encompassing various functional irregularities associated with muscle co-ordination, the present study focused solely on the assessment of dental caries and drooling. Other probable confounding variables like oral hygiene practices, feeding history were not considered.

Future Prospects

Conducting more prevalence studies on dental caries within our country, along with frequent use of diverse drooling scales in this specific population, may provide futuristic insights into the association between potential causative variables and contribute to the development of effective management protocols.

Conclusion

The cause and effect relation or any positive/negative correlation between dental caries and drooling could not be established in this study. However, future studies with larger populations and research focusing on the impact of therapies addressing oral motor dysfunctions, including drooling, are recommended to further benefit children with cerebral palsy.

Oral health is an integral part of holistic health, yet it remains one of the most unattended health need, especially in children with CP, who often exhibit poorer oral hygiene compared to normal children. Thus efforts should be made for timely provision of preventive and therapeutic dental care for this vulnerable population.

Conflict of Interest

The authors declare that they have no conflict of interest.

Ethics Statement

The research study was approved by Institutional Ethical Committees of two institutions - Governmentental College & Research Institute, Bengaluru and Sri Rajiv Gandhi College of Dental Sciences & Hospital, Beng-aluru. It has also been registered (considering it as a part of PhD study) in Clinical Trial Registry - India (CTRI number: CTRI/2021/03/031990; URL: https://ctri.nic. in/Clinicaltrials/login.php). Participants were informed about the purpose of the research and written consent was taken.

Funding

The present study hasn’t received any financial support from outside.

Acknowledgement

The authors are grateful to the parents for their kind co-operation, school management and teachers for their willingness to mediate, and most importantly the children on whose experiences this research study was conducted.