This study investigates the remediation of black-stained tooth surfaces using antimicrobial photodynamic therapy. In this crossover trial, a cohort of patients received standard dental prophylactic cleaning to remove the black stain. Later, following the washout period, (reappearance of the black stain) received photodynamic therapy in addition to the standard cleaning. Stain-free period in each of the arms was the main outcome variable. Additional microbial plaque testing was also carried out.

The standard treatment practice for black dental stain is dental prophylaxis, however this is often harmful to the enamel surface and can result in tooth sensitivity. In this study we aim to explore the application of antimicrobial photodynamic therapy (aPDT) for the treatment of adult black dental stain. aPDT has demonstrated positive results in the treatment of periodontitis.

Patients received an oral examination and the extent of black stain was scored (score 1, pigmented spots or incomplete lines parallel to the gingival margin, score 2: solid lines pigmented, readily observable and limited to the cervical third of the tooth surface, score 3: pigmentation extending beyond the cervical third). The patients' oral cavity was photographed in sextants, along with a complete picture of the jaw (lingual plane) and the maxillary arch (palatal plane). For bacterial analysis, 1mg of black plaque was collected by scraping with a plastic scaler from buccal tooth surfaces taking care to avoid unnecessary removal of enamel hydroxyapatite. The first dental prophylaxis was performed to remove the black stain.

Patients were reviewed monthly and in each visit, were photographed as previously described, and the level of pigmentation scored according to the mentioned criteria. The monthly visits were continued until the black stain score returned to the initial value. The period between the first and the last appointment was noted. At this point, each volunteer received dental prophylaxis once again, followed by the application of aPDT. Antimicrobial photodynamic therapy was applied to 31 orally healthy volunteers with black stained teeth, using the GLO home whitening device (GLO™ Science LLC, New York, USA) in 2 cycles of 8 minutes. Outcome variables were area, color and time taken to reappearance of black stain following dental prophylaxis with and without antimicrobial photodynamic therapy. Differences in bacterial composition of black stain (specifically Aggregatibacter actinomycetemcomitans, Tannerella forsythia and Porphyromonas gingivalis) were analyzed DNA extracted from plaque samples. Following the application of aPDT, patients were reviewed monthly until the black stain score returned to the initial value.

Inclusion Criteria:

• Volunteers with black stained (plaque on) teeth

Exclusion Criteria:

• Children
• Pregnant women
• Volunteers having completed antibiotic therapy during 15 days prior to the start of the study