Document Type: Original Articles


1 Neuroscience Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran.

2 Bone and Joint Diseases Research Center, Department of Physical Medicine and Rehabilitation, Shiraz University of Medical Sciences, Shiraz, Iran. Shiraz Geriatric Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.

3 Department of Operative Dentistry, School of Dentistry, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran.

4 Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran.


Background: The tongue controls the bolus during mastication, keeps the bolus in the oral cavity and generates pressure to direct the bolus through the hypopharynx. A decrease in tongue movement and strength can increase the oral and pharyngeal food residues. Food residues have the potential to increase the risk of dental caries. The aim of this study was to investigate the correlation between tongue strength and the prevalence of dental caries in individuals with Down syndrome. 
Methods:  Sixteen children with Down syndrome participated in this cross sectional study; none of them had dysphagia and they had normal diet. The tongue strength was measured using the Iowa Oral Performance Instrument (IOPI) and dental caries were assessed by Decayed – Missing –Filled Teeth Index (DMFT). A speech therapist measured and investigated tongue strength and a dentist did the dental examination and filled out the DMFT form.
Results: The mean age of participants was 11.06 (SD=2.83). Most of the participants were female (n=14, 87.50%). All of the subjects had mixed dentition. The mean of tongue strength was 10.23KPas (SD= 7.08). There was no correlation between tongue strength and the total number of DMF plus dmf, according to Pearson correlation (p=0.96; r= -0.01).
Conclusion: Tongue strength was very low in these children compared with reports in the literature. There was no correlation between the tongue strength and number of DMF and dmf; the main reason is that the development of dental problems such as caries are multi factorial. In other word there are additional factors apart from poor tongue strength that can cause caries.