|Year : 2022 | Volume
| Issue : 3 | Page : 274-280
Comparison of dental caries experience and salivary parameters among children with Down syndrome and healthy controls in Chennai, Tamil Nadu
Sujatha Anandan1, Nagesh Lakshminarayan2, Karibasappa Gundabaktharu Nagappa3
1 Department of Public Health Dentistry, Tamil Nadu Government Dental College and Hospital, Chennai, Tamil Nadu, India
2 Department of Public Health Dentistry, Dayananda Sagar College of Dental Sciences, Bengaluru, Karnataka, India
3 Department of Public Health Dentistry, ACPM Dental College, Dhule, Maharashtra, India
|Date of Submission||17-Aug-2021|
|Date of Decision||02-Jun-2022|
|Date of Acceptance||18-Jun-2022|
|Date of Web Publication||18-Oct-2022|
Department of Public Health Dentistry, Tamil Nadu Government Dental College and Hospital, Chennai - 600 003, Tamil Nadu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Although there have been numerous studies on dental caries in children with Down syndrome, the reports are conflicting. Studies on salivary chemical composition of children with Down syndrome are limited. Aim: The study aims to evaluate and compare the dental caries experience, salivary flow rate, pH, buffering capacity, and concentration of sodium, potassium, calcium, phosphorus, total proteins, and sialic acid in children with Down syndrome and healthy controls. Settings and Design: This was a cross-sectional study. Materials and Methods: Forty subjects with Down syndrome aged 5–18 years fulfilling the eligibility criteria from six special schools were selected by snowball sampling. Sixty healthy controls from six neighborhood schools fulfilling the eligibility criteria were selected by simple random sampling by matching the age, gender, and socioeconomic status. Sociodemographic data, oral hygiene practices, diet history and dental caries experience were recorded. About 6 mL of stimulated whole saliva was collected. Salivary flow rate, salivary pH, buffering capacity, and the concentration of sodium, potassium, calcium, phosphorus, total proteins, and sialic acid were determined. Results: There was no significant difference in the mean proportional caries rate between the study and control group (P = 0.90). Salivary pH (P = 0.00) and salivary sodium concentration (P = 0.02) were significantly low in the study group than the control group. Salivary buffering capacity was significantly higher in the study group than the control group (P = 0.001). Conclusions: Dental caries experience of children with Down syndrome was similar to the healthy controls. School health programs could be implemented in special schools to improve oral and general health of special children.
Keywords: Dental caries, Down syndrome, saliva
|How to cite this article:|
Anandan S, Lakshminarayan N, Nagappa KG. Comparison of dental caries experience and salivary parameters among children with Down syndrome and healthy controls in Chennai, Tamil Nadu. J Indian Soc Pedod Prev Dent 2022;40:274-80
|How to cite this URL:|
Anandan S, Lakshminarayan N, Nagappa KG. Comparison of dental caries experience and salivary parameters among children with Down syndrome and healthy controls in Chennai, Tamil Nadu. J Indian Soc Pedod Prev Dent [serial online] 2022 [cited 2022 Nov 29];40:274-80. Available from: http://www.jisppd.com/text.asp?2022/40/3/274/358837
| Introduction|| |
According to the 2011 census, 26.11 million people in India are differently abled, accounting to 2.21% of the total population. Among them, 6% are intellectually challenged. As many as one-fourth of persons with intellectual impairment have detectable chromosome abnormality. One such syndrome associated with chromosomal abnormality is Down syndrome.
Down syndrome or Down's syndrome (U. K.), Trisomy 21, or Trisomy G, is a genetic disorder caused by the presence of an extra 21st chromosome. Worldwide, the incidence of Down syndrome varies from one in 600 to one in 1000 live births. Apart from the variable physical characteristics and intellectual impairment in Down syndrome, there are certain intraoral manifestations such as congenital oligodontia, delayed eruption of deciduous and permanent teeth, malocclusion, high-arched palate, fissured tongue, and a high prevalence of periodontal disease which are reported in the literature. However, scientific literature revealed contradictory reports related to dental caries experience in Down syndrome.
Few studies have shown that there is no difference in dental caries experience between children with and without Down syndrome., However, other studies have shown that the prevalence of dental caries in children with Down syndrome is relatively low compared with normal children.,,, Living environment, dietary and oral hygiene habits, oligodontia, delayed eruption, and different salivary components have been proposed as the causes for low prevalence of dental caries in Down syndrome, when compared with normal children.,,,,,,
However, it is clearly evident that intellectual capacity of children with Down syndrome limits the dexterity for maintenance of good oral hygiene, posing a greater risk for the development of dental diseases.
Although there have been numerous studies on dental caries in Down syndrome subjects, the reports are conflicting to arrive at concrete conclusions. Studies on salivary chemical composition of subjects with Down syndrome are also limited. Thus, the aim of the present study was to evaluate and compare the dental caries experience, salivary flow rate, pH, buffering capacity, and chemical composition between children with Down syndrome and healthy controls.
| Materials and Methods|| |
Ethical clearance was obtained from the institutional review board. Based on the results obtained from a study conducted by Yarat et al., level of significance (α) at 5%, and power of the study (1–β) at 80%, the required sample size for the study was approximately 40. More controls were selected to minimize the dispersion in the variables and to maximize the power of the study.
Finally, 40 children with Down syndrome (5–18 years) were selected by snowball sampling method from six special schools in Chennai city. Sixty healthy controls (5–18 years) were selected by simple random sampling (lottery method) from six neighborhood schools, which were in proximity to the selected special schools. Controls were matched for age, gender, and socioeconomic status. Children under antibiotics, anticholinergics, antihistaminics, and antipsychotic therapy for 2 weeks prior to saliva collection were excluded.
Written informed consent was obtained from parents or legal guardians of the selected participants. The required and relevant sociodemographic information, oral hygiene practices, and 24-h diet history were obtained. The total number of teeth present in the oral cavity was recorded. Decayed-Missing-Filled Teeth (DMFT) and Decayed-Missing-Filled Surfaces (DMFS) indices were used to record dental caries in permanent teeth. Decayed-extracted-filled teeth (deft) and decayed-extracted-filled surfaces (defs) indices were used for recording dental caries in primary teeth. Proportional caries rate was calculated as dental caries experience divided by total number of teeth present in the oral cavity and multiplied by 100 and expressed in percentage.
Saliva collection was always scheduled between 9 and 11 am to standardize saliva collection time and minimize the effect of circadian rhythm. Just before the start of saliva collection, lemons were cut into two halves; the juice was extracted by squeezing and finally collected in a container. A commercially available dropper with 0.5 cm diameter was used to dispense the lemon drops. This was done to standardize the quantity of lemon drops. About 3–4 drops were dropped on the dorsum of the tongue with the help of dropper. During this period, subjects were advised to swallow saliva, so that the constituents of lemon do not get collected into the salivary samples and bias the parameters analyzed in the saliva.
After 30 s, commercially available preformed braided cotton rolls of 3.8 cm × 0.95 cm (Star rolls, New Stetic, Colombia) were placed in the oral cavity to collect saliva. One cotton roll was placed on either side of the upper buccal vestibule near the opening of parotid duct and the other one on the anterior floor of the mouth near the opening of submandibular and sublingual salivary ducts. Subjects were instructed to keep their mouth open when the cotton rolls were placed in their oral cavity.
Approximately after 1 min, all three cotton rolls were removed. A 5 mL syringe was taken; the plunger of it was removed, and the cotton rolls were placed inside the syringe. Saliva was squeezed out of the cotton rolls with the plunger of the syringe and collected into a graduated plastic tube. About 6 mL of saliva was collected in a plastic tube with an airtight cap. The salivary samples were transported within 1 h in a thermocol box containing ice packs. The samples were stored at –40°C at the Center for Toxicology and Developmental Research, Sri Ramachandra University, Porur, Chennai.
Salivary parameters were analyzed by a single trained and calibrated laboratory technician who was blinded about the details of the study to avoid investigator bias. Salivary pH together with concentration of sodium, potassium, and calcium were analyzed by an electrolyte analyzer (Acculyte-5P). Salivary buffering capacity was calculated by Ericsson method, phosphorus by Thermo Scientific multiscan spectrophotometer, total proteins by Biuret method, and sialic acid by thiobarbiturate assay.
Statistical analysis was done using a computer with the aid of Statistical Package for the Social Sciences (SPSS) Version 22 (Released 2013, IBM Corp, Armonk, NY). Comparisons of demographic data, oral hygiene practices, and the pattern of sugar consumption were done between the study and control groups with Chi-square test. Comparison of dental caries experience and salivary parameters between the study and control groups was done with unpaired t-test. Proportional caries rate was analyzed by Mann–Whitney U-test since it was non-normal in distribution.
| Results|| |
[Table 1] demonstrates the sociodemographic data, oral hygiene practices, and sugar consumption patterns. The sociodemographic characteristics analyzed in the present study were not statistically significant between the study and control groups except for the frequency of sugar consumption (P = 0.03). There was no statistically significant difference in the mean dental caries experience and the mean proportional caries rate between the study and control groups [Table 2]. Salivary pH (P = 0.00) and salivary sodium concentration (P = 0.02) were significantly low in the study group than the control group. Salivary buffering capacity was significantly higher in the study group than the control group (P = 0.001) [Table 3].
|Table 2: Dental caries experience and proportional caries rate of study and control group|
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| Discussion|| |
The present study compared the dental caries experience, proportional caries rate, and salivary parameters between children with Down syndrome and healthy controls. There was no statistically significant difference in the mean dental caries experience between the study and control groups (P = 0.96), which is in concordance with the previous studies.,,, This would probably be due to (a) well-matched study and control group based on age, sex, and socioeconomic status; (b) selection of neighborhood controls making the local environmental factors similar; and (c) oral hygiene practices were found to be similar in both study and control group. However, the frequency of sugar consumption is statistically significant between the study and control groups. This could be attributed to the effect of institutionalization in the Down syndrome group.
While majority of previous studies have reported low caries experience,,,,,, a very few studies have reported high caries experience in Down syndrome.,, According to a study reported in 2008, the prevalence of dental caries in children with Down syndrome at Chennai, Tamil Nadu, was 70.6%. Supporting evidence from an Indian study indicated that 56% of children with intellectual impairment have dental caries. Evidence from Indian studies revealed that children with Down syndrome exhibited the highest DMFT scores when compared with other type of mental disabilities.,
There is convincing evidence in the literature that children with Down syndrome have masticatory dysfunction due to poor neuromuscular control. As a result, they tend to eat softer food, often high in carbohydrate content. In addition, food in spite of being solid, semisolid, or puree is normally held in the mouth for a longer period. It was also reported that children with Down syndrome were more likely to be weaned off at an older age or given syrup-based medications for repeated infections because of swallowing problems. Hence, these reasons may be hypothesized for increased susceptibility to dental caries. However, studies which have reported low prevalence of dental caries in Down syndrome have not considered the total teeth present in the oral cavity.,,,,, As a result, whether such individuals have less susceptibility to dental caries or an underestimation has been done by the previous authors due to congenital oligodontia is uncertain. Other reasons for the varied results quoted in the literature are inconsistent research designs, effect of institutionalization, and poor matching between the study and control groups that would have confounded the study results.
The results showed that the study group had slightly higher mean proportional caries rate [Table 2] than the control subjects, but the difference was not statistically significant (P = 0.90), which is in agreement with the previous studies.,, However, in the present study, only three individuals in the study group presented with congenitally missing teeth. This would mean that the total teeth present in the study and control groups (denominator component) was more or less similar, thereby making the difference in proportional caries rate statistically not significant.
A minimum of 6 mL saliva was required for sialochemistry. It was not feasible to collect 6 mL of unstimulated saliva form children with Down syndrome. Parents of subjects with Down syndrome refused to give consent for stimulating saliva using paraffin wax or citric acid. Parents believed that their children might swallow the given paraffin wax due to poor neuromuscular control. The use of citric acid, being a laboratory chemical reagent, was also denied. Finally, lemon drops were used to collect stimulated saliva. This method is similar to the work of Jara et al., in which the composition of parotid saliva in Chilean children with Down's syndrome was determined.
Children with Down syndrome were not competent to expectorate saliva by themselves into the test tubes. Moreover, usage of suction apparatus was impractical in the study setting. Thus, two sterile cotton rolls were placed on the either side of buccal vestibule near the opening of parotid salivary gland ducts and one on the anterior floor of the mouth near the opening of submandibular and sublingual salivary gland ducts.
The method of saliva collection in the present study is different from that of other studies. Some studies have collected stimulated whole saliva,,,,, a few stimulated parotid saliva, and a very few unstimulated whole saliva.,, Majority of the studies have used paraffin wax,,,, and a very few used 2% citric acid on the dorsum of tongue for stimulating saliva. In the previous studies, stimulated saliva was collected either by asking patients to expectorate or by using suction apparatus. In the present study, lemon drops containing citric acid were used as a stimulant and saliva was collected by placing commercially available preformed cotton rolls in the oral cavity.
There was no significant difference in the mean stimulated salivary flow rate between the study and control groups (P = 0.66), which is in agreement with a study conducted by Cogulu et al. Low salivary flow rate was reported by Siqueira and Nicolau, Siqueira et al., and Chaushu et al. Comparing parotid salivary flow rates, Chaushu et al. and Cutress reported low salivary flow rates, while Jara et al. and Winer et al. reported no difference between subjects with Down syndrome and controls. However, Cutress et al. compared the difference in salivary flow rate between persons with Down syndrome and those who were mentally disabled for reasons other than trisomy. Yarat et al. found significantly low salivary flow rate in the Down syndrome group than that of healthy controls, but the study collected unstimulated whole saliva.
Few studies have reported drooling in persons with Down syndrome and the authors have suggested few procedures for its correction., However, drooling of saliva is not the result of hypersalivation. It is due to factors such as open mouth posture, large protruded tongue, everted lower lip, relative lack of mastication, and deglutition caused by hypotonic orofacial musculature.
In the present study, salivary pH was lower in the study group than the control group, which was statistically significant (P = 0.00), agreeing with the previous studies.,, However, Cogulu et al. found no difference in salivary pH between Down syndrome group and healthy controls. In another study, Jara et al. did not find a significant difference in stimulated parotid salivary pH between Down syndrome, mentally retarded, and normal people. Considering unstimulated saliva, while Davidovich et al. reported low mean salivary pH from four intraoral sites in the Down syndrome group, no difference was reported by Yarat et al. and Siquiera et al. Yazeed et al. reported a comparatively higher salivary pH in Down syndrome children than the healthy control group; the type of saliva collected (unstimulated/stimulated) has not been addressed by the authors.
Buffering capacity was significantly higher in study group than the control group (P = 0.001), which is in line with the reports of Jara et al. and Siquiera et al. However, Cogulu et al. found no difference in the buffering capacity between children with Down syndrome and normal children. Comparing unstimulated whole saliva, Yarat et al. found no difference in the buffering capacity between Down syndrome group and control group. According to Castilho et al., 44% of the samples had low buffer capacity, 39% had limited buffer capacity, and 17% had normal buffer capacity. The authors recruited a smaller sample size of wide age group from 1 to 48 years with no control group.
The mean differences in all the salivary chemical constituents analyzed between the study and control group were not significant except for sodium (P = 0.02). Sodium and potassium are the major cations in the buffer system. However, the exact role of these ions in dental caries has not been investigated so far. In the present study, sodium concentration is significantly low (P = 0.02) in subjects with Down syndrome than the controls, while there is no difference in potassium concentration (P = 0.26). This can be attributed to the slightly low salivary flow rate seen in the Down syndrome group. However, Siqueira et al. found high sodium and low potassium concentration in children with Down syndrome. They believed that there could be an anomaly in sodium and potassium transport. Further, Jara et al. also reported high sodium and low potassium levels with respect to stimulated parotid saliva. Working with unstimulted saliva, Davidovich et al. found significantly high sodium and potassium levels in Down syndrome children with caries than caries-free Down syndrome children. These reports revealed lack of agreement in the literature regarding salivary sodium and potassium. It is speculated that there might be some genetic defect manifested in salivary glands, leading to the alterations in the salivary electrolyte levels, which needs further investigation.
Salivary calcium and phosphorus are known to be protective against dental caries by inhibiting demineralization and promoting remineralization. In the current study, salivary calcium (P = 0.17) and phosphorus (P = 0.51) levels in the test group were not different from that of controls, which matches with the report of Siqueira et al. With respect to unstimulated whole saliva, Davidovich et al. reported significantly high calcium in the Down syndrome group than healthy controls, although Siqueira et al. found no difference.
The present study demonstrated no difference in total proteins (P = 0.37), whereas Siquiera and Nicolau reported 36% increment in salivary total protein concentration in the Down syndrome group than controls. When unstimulated whole saliva was compared, Siquiera et al. found significantly higher salivary total proteins in the Down syndrome group than healthy controls.
Sialic acid, known as pH rising factor, has a beneficial action against dental caries. Sialin is converted into ammonia and putrescine, eventually converts into pH rising factor. There was no significant difference in the levels of sialic acid between the study and control groups (P = 0.56) in the present study, agreeing with the findings of Siqueira and Nicolau. Comparing unstimulated saliva, Yarat et al. found significantly high levels of sialic acid in the Down syndrome group than healthy controls.
Overall, the reported inconsistencies in the various salivary parameters analyzed may be partly due to difference in the stimulant used (paraffin wax/citric acid/lemon), duration of stimulation, method used for collection of saliva (expectoration/suction/cotton swabs), and method of salivary analysis. Moreover, sample size disparity and/or difference in the sampling method would be the probable reasons for the varied results.
The present study includes the following limitations:
- Study group selection was not done by random sampling method as it was practically difficult to identify Down syndrome population from the general population. Thus, subjects with Down syndrome were selected from special schools by snowball sampling till the required sample size was achieved, constraining the generalizability of the present findings
- Saliva was collected by placing cotton rolls in the oral cavity leading to adsorption and precipitation of salivary proteins on to the cotton rolls resulting in underestimation. However, saliva collection method was similar in both the study and control groups, justifying the relative comparison of salivary proteins.
| Conclusions|| |
We conclude that dental caries experience and proportional caries rate in children with Down syndrome were similar to the healthy controls in the present study. Majority of salivary parameters analyzed in Down syndrome demonstrated an insignificant effect on dental caries.
Our study findings signify that children with Down syndrome are equally susceptible to develop dental caries when compared to normal children, contradicting the previously published literature, where congenital oligodontia would have probably confounded the results. We would recommend using proportional caries rate when measuring dental caries experience in populations presenting with congenital oligodontia to ensure valid comparisons.
Frequent consumption of soft, refined carbohydrate-rich diet due to masticatory dysfunction coupled with limited manual dexterity to maintain good oral hygiene may be considered contributing factors for dental caries in Down syndrome. Recognizing their special needs, dental auxiliaries could be mobilized to every special school to support their oral self-care to prevent oral diseases and thereby promote general health and well-being.
We are indebted to the study participants and the school authorities for their support and cooperation. We thank Dr. Rangarajan for his assistance in saliva collection and Dr. Saravana Babu Babu for analyzing salivary parameters. We would also extend our gratitude to Biostatistician, Mr. Sangam for data management. We would like to appreciate the efforts of Ms. Smitha Dasan for editing and reviewing the manuscript.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]