Diversity of Lactobacillus species in primary dental pulp and clinical signs and symptoms

Aims: bacteria are one of the main factors involved in the process of tooth decay.  They play an important role in the onset and progression of tooth decay and are the main cause of pulp and periapical diseases. Their presence in the crown pulp and dental canal causes symptoms in the teeth; therefore, the aim of this study was to molecular study of anaerobic bacteria in primary and necrotic teeth of children and to determine the relationship between these bacteria and clinical signs and symptoms. Materials and Methods: In this analytical cross-sectional study, 90 children aged 4-12 years were divided into five equal groups (n=18) including: reversible pulpitis without irritant pain, reversible pulpitis with irritant pain, irreversible pulpitis, necrosis with abscess and necrosis without abscess. Clinical symptoms of the patient such as history of pain, luxation, and sensitivity to percussion, status of the dental pulp and presence of swelling were recorded and samples were taken from coronal pulp tissue and root canals during pulp treatment using sterile paper points. To identify anaerobic bacteria, clinical samples were cultured under anaerobic conditions. The 16srRNA sequencing was used for molecular identification of anaerobic bacteria at species level. Finding: Totally in 90 (100%) of patients, 9 different Lactobacillus spp were identified which among them L. fermentum (37.8%), L. rhamnosus (15.6%), L. salivarius (10%) and L. Gasseri (5.6%) were the most prevalent. L. fermentum was the most common species found in all clinical samples that had relationship with pain. (P=0.034) Conclusion: L. fermentum was the most common bacterium in all clinical symptoms. There is need to consider this bacterium in determining antiseptic, irrigation and treatment of root canal in patients with pulpitis.