Abstract
Background: Children with Down Syndrome have poorer oral health status, higher frequency of occurrence of periodontal pathogens, A. actinomycetmcomitans and P. gingivalis, and salivary sIgA deficiencies compared to children from the general population. Previous studies have employed culture techniques or molecular methods such as End-Point Polymerase Chain Reaction (EP-PCR) for the detection of the periodontal pathogens A. actinomycetmcomitans and P. gingivalis, in children with DS. Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), a more recent molecular method, has a lower limit of detection for A. actinomycetmcomitans and P. gingivalis compared to culture technique and EP-PCR. The levels of salivary sIgA in children with DS compared with children from the general population are being debated.
Objectives: The aims of this study were to compare (i) the caries experience, (ii) prevalence of gingivitis, (iii) the total salivary flow rates, (iv) the levels of total sIgA in the whole saliva and (v) the occurrence of the periodontal pathogens A. actinomycetmcomitans and P. gingivalis, in children with Down Syndrome with a sibling (of closest age without DS) and a parent.
Methods: Twenty families that had a child with DS were recruited and the study participants comprised of 20 children with DS, 20 parents and 10 siblings of closest age without DS. Caries experience was determined using the dmft and DMFT scores. The prevalence of gingivitis was determined using the Gingival Index (GI) scores. Stimulated whole saliva samples were collected by chewing on Salivette® swabs. A pooled sample of supragingival plaque was collected using sterile interproximal brushes. The occurrence of the periodontal pathogens A. actinomycetmcomitans and P. gingivalis was determined using EP-PCR and qRT-PCR. The measurement of sIgA was carried out using an Indirect Competitive Enzyme-Linked Immunosorbent Assay.
Results: The mean caries experience in children with DS was higher than in the siblings but the difference was not statistically significant. The mean GI recorded in the children with DS was statistically significantly higher than that found in the siblings. The mean total sIgA in the stimulated whole saliva was higher in children with DS than in the siblings, with a statistically significant difference between the two groups of children. P. gingivalis and A. actinomycetemcomitans were found to occur in a greater percentage of children with DS, siblings and parents when analysed using qRT-PCR compared with EP-PCR. Using the more sensitive qRT-PCR, the detection frequencies of both P. gingivalis and A. actinomycetemcomitans were similar across all groups.
Conclusions: The present study has shown statistically significantly higher levels of total sIgA in the stimulated saliva, and higher mean GI as well as a higher caries experience, albeit not statistically significant, in children with DS compared with their siblings. It has also demonstrated that the total sIgA levels in children with DS are more similar to those of their parents than their siblings. This further supports the understanding that the immune response in individuals with DS is different from that of individuals from the general population of similar age.