Evaluation of the effectiveness of passiveultrasonic irrigation on removal of tooth discoloringcaused by photodynamic therapy

The aim of this study is to evaluate whether the irrigation solutions used after the use of photosensitizer dyes in PDT can be reduced by the passive ultrasonic irrigation system, and whether the discoloration on the teeth can be reduced. 182 maxillary incisors were used. Root canals were prepared up to X4 size with ProTaper Next rotary instruments. The initial colors (T0) of all teeth after preparation were measured from the composite frame made in the middle of the vestibular surface of each specimen of the crowns. After creating 1 negative control group (n = 14), the teeth were divided into 3 groups according to the photosensitizer dyes used (n=56): 1) Methylene Blue (MB), 2) Toluidine Blue (TB), 3) Indocyanine Green (ICG). Then, each group was divided into 4 subgroups according to the technique and solution to be used in removing the dyes: A) Saline combined with standart needle irrigation (SNI) B) Saline combined with passive ultrasonic irrigation (PUI) C) 5% NaOCl combined with SNI D) 5% NaOCl combined with PUI (n = 14 for each group). Then the teeth were exposed to PDT with the specified photosensitizer dyes. Root canals were washed with saline and dried, and color measurements were made after laser and the values were recorded (T1). Samples were irrigated with the use of saline or 5% NaOCl together with SNI or PUI according to the subgroups they were divided into to remove photosensitizing dyes. After dye removal, color measurements were made and the values were recorded (T2). Calculations of ΔL1, ΔL2, ΔE1, ΔE2, Δa1, Δa2, Δb1, Δb2 values were made with the obtained L * a * b * values. In the statistical analysis of the obtained values of ΔL1, ΔL2, ΔE1, ΔE2, Δa1, Δa2, Δb1, Δb2, the Kruskal Wallis test was used to compare the control group with all other subgroups. For the correlation between variables, 3-factor factorial variance analysis model was used. When the obtained data were evaluated, the ΔE1 was found to be significantly higher in all 3 dyes compared to the control group. However, no significant difference was found between the dyes. Regardless of technique or dyes, in dye removal, ΔE2 values of saline solution were found to be significantly higher than NaOCl solution. No significant difference was found in the use of saline solution with SNI or PUI techniques. The use of NaOCl solution with PUI, regardless of the dye, was found to be significantly higher than the SNI technique. It was observed that the PS dyes MB, TB and ICG cause discoloration on the teeth after PDT and 5% NaOCl can remove the dye more effectively from saline regardless of technique or dye. In addition to this, it was concluded that activation of 5% NaOCl with PUI system could be suggested to remove the discoloration that occurs in the teeth after the use of PS dye in PDT. However, these results should be supported by other future researches.