Antimicrobial effects of Photodynamic and high-power laser endodontic therapy on patients with necrotic pulp and periapical lesion

The aim of the present study was to test the combination of conventional endodontic therapy followed by antimicrobial Pothodynamic Therapy (PDT) or high-power laser in a clinical trial in patients requiring endodontic treatment. 50 patients were recruited for this study. For each patient a single tooth with clinical symptoms of pulp necrosis and periapical periodontitis was selected. The samples were randomly allocated into two experimental groups (n = 25 per each): group 1 (n = 25): high-power diode laser and group 2 (n = 25): photodynamic therapy (PDT). All samples of the two groups were treated with an intermediate dressing with calcium hydroxide and provisionally filled; after one week the dressing was removed and they underwent further PDT and high frequency laser treatment. After each step, a microbiological sample was taken. Finally, the elements were filled using the MicroHeat root canal filling technique. The culture method was chosen for the microbial count of common aerobes, facultative anaerobes, and microaerophilic bacteria. During the process, specific microbial flora was not identified, but general microbial count of colony forming units (CFU) was performed. The count of the number of CFU indicates a very wide range for the different samples. The tested photodynamic laser treatment shows positive and clinically relevant results when used as an adjuvant to traditional mechanical and chemical cleansing. There is a further reduction after a second treatment with photodynamic therapy. The decrease in CFU post photodynamic treatment is similar before and after dressing with calcium hydroxide. Photodynamic endodontic treatment as an adjuvant to traditional mechanical and chemical cleansing has shown greater efficacy in controlling the contamination of the treatment with diode laser. The first photodynamic treatment causes a reduction in the microbial count, and the second, after intermediate dressing, is comparable to the first. This is probably due to a lower complexity of the biofilm created after the intermediate dressing with calcium hydroxide compared to the initial intracanal biofilm. This therapeutic adjuvant is, therefore, more suitable in clinical situations where an intermediate dressing is necessary.