Using Absorbent Paper Strips for the Collection of Cell-Free DNA in Patients with Periodontal Diseases

The cell-free DNA in gingival crevicular fluid (GCF) is a recent interesting diagnostic marker in patients with periodontal disease. The methods used to collect GCF are very important to get the proper specimen. There are several techniques used for sample collection, such as gingival washing or using a capillary tube, however, these methods are not practical to perform in the clinic since they need well-trained examiner. This study aimed to use absorbent paper strips to collect cell-free DNA fragment in GCF of patients as a diagnostic measure for periodontal diseases comparing to conventional washing technique. Thirty-nine periodontitis and 26 gingivitis teeth were selected from 26 patients according to clinical parameters. The GCF sample was randomly collected from each tooth by either paper strips or washing technique. Then, after one week, the collection of samples from the same tooth was repeated with another technique. The samples were centrifuged to get cell-free DNA in the supernatant and extracted by InstaGene Matrix. The concentration and purity of extracted DNA were determined by NanoDrop spectrophotometer. Three sets of specific primers to the human b-globin gene were used to evaluate the DNA fragment lengths, by amplifying 110 base pair (bp), 536 bp, and 2000 bp products in the polymerase chain reaction (PCR). The results showed no significant differences in the cell-free DNA fragment concentrations and the prevalence of PCR products between using absorbent paper strips and washing technique in either gingivitis or periodontitis groups. Therefore, with the ease and rapidity of the technique, using the absorbent paper strips for the quantitative and qualitative investigation of cell-free DNA fragment in patients with periodontal diseases instead of washing technique is recommended. Further studies are still required to confirm this finding in a large group of patients as well as in patients with other systemic health problems.