Correlation between characteristics of saliva and caries resistance

Down syndrome (DS) is a genetic disorder caused by a trisomy of chromosome 21 with an incidence of 1: 800 to 1:1000 births. In India, it has been reported that the incidence of Down’s syndrome occurs in 1 per 700 births. The syndrome is characterized mainly by mental retardation, cardiovascular, hematopoietic, and musculoskeletal and nervous system anomalies, as well as other phenotypic abnormalities. Numerous oral manifestations have been describedin DS individuals including low incidence of dental caries, high incidence ofperiodontal diseases, mouth breathing resulting in dry mouth, fissured tongueand lips, high incidence of mucosal ulcers, candidiasis and acute necrotizingulcerative gingivitis. Children with Down syndrome may have different dental characteristics such as congenitally missing teeth and microdontia. Often, the teeth are in Angle’s class III relationship with posterior cross bites due to underdeveloped midfacial region. 

The tongue has deep fissures and appears large with a short and narrow maxilla. Based on literature review worldwide caries prevalence in Down syndrome is low compared with other individuals. This may be due to factors such as delay in eruption of teeth, changes in saliva composition, teeth morphology with less pronounced pits and fissures and different in microbiota associated to dental biofilm.One of the major functions of human saliva is to protect dentition against dental caries. The saliva pH level is ranged between 6.3 and 6.9. Flow rate and buffering capacity of saliva play an important role in the organization of oral microbiota because they maintain the saliva pH. However, in Down syndrome individuals, there may be physiological alterations in the saliva flow rate and its composition which are fundamental to colonization of the microorganisms. These changes will reduce the protective function of saliva on the tooth surfaces. Read more..........