Microorganisms associated with black tooth stain and contemporary strategies for their management

Introduction : Black stain is an extrinsic tooth discoloration, characterized by dark lines or incomplete pigmentation along the gingival margin in the cervical third of the tooth. They can affect both primary and permanent dentitions. Aim : To investigate the microbial composition of black tooth stains in children and explore potential preventive and therapeutic strategies. Materials and methods : Supragingival plaque samples were collected from 60 children (30 with and 30 without black stain). Bacterial identification was performed using 16S rRNA gene sequencing. Isolates were classified by morphology and biochemical characteristics. Based on microbial profiles, photodynamic therapy and probiotic supplementation were proposed as adjunctive management strategies. Data were analyzed statistically using the Fisher test. Results : Children with black stain showed distinct oral microbiota changes compared to controls. Actinomyces sp. increased more than three times, while Streptococcus sp. significantly decreased three times. Treponema sp. and Eikenella sp. showed similar relative abundances, whereas Selenomonas sp. and Veillonella sp. were absent in the group with black stain. Burkholderia sp. and Neisseria sp. were detected exclusively in black stain samples but were undetected in controls. Morphologically, filamentous rods remained predominant, while the composition of cocci shifted, reflecting a specific microbial profile associated with black stain formation. Conclusion : Black tooth stain in children is associated with a unique bacterial community structure. Targeted treatments, such as natural antimicrobials, photodynamic therapy and probiotics may help control recurrence and maintain oral microbial balance.