Spectrophotometric analysis of the effectiveness of different dentin tubule occlusion techniques in preventing discoloration caused by photosensitizers used in photodynamic therapy

In this study, the efficacy of Copal Varnish (CV), dentin bonding agent (DBA), Nd: YAG laser and Er: YAG laser, which occlusion dentin tubules by different mechanisms, was investigated in order to prevent undesirable coloration caused by methylene blue (MM) and phthalocyanine used in photodynamic therapy (FDT). 165 upper incisors with single root and single canal were included in the study. After the standard access cavity was opened in all teeth, root canals were prepared up to size 30/0.6 using Protaper Next (Dentsply Maillefer, Ballaigues, Switzerland) rotary files. Then the teeth were randomly divided into 2 main groups (n=60); MM and phthalocyanine. Then, each main group was divided into 4 subgroups according to the dentin tubule occlusion technique (n=15); Positive control, DBA, CV, Er: YAG and Nd: YAG. Then, after applying the related dentin tubule occlusion method to the groups, the root canals were filled with the relevant photosensitizers (FS) and a preirradiation period of 5 minutes was applied and activated with LED (CMS Dental, Denmark, Korea) for 1 minute. Then, the residual FSs were removed by irrigation with 2.5% sodium hypochlorite (NaOCl; Wizard, Lider Kimya, istanbul, Turkey). After all procedural procedures, color measurements of the samples in the study were performed in accordance with the standards of the Commission International de I'Eclairage (CIELab) in 5 different time periods: before the treatment, after the treatment, after the dyes are removed, on the 30th day and 90th day. VITA Zahnfabrik, Bad Sackingen, Germany) was carried out using a spectrophotometer device. Color measurements were repeated three times from the same point by placing the tip of the spectrophotometer on the frame on the labial surfaces of the teeth under white light. ΔE values were calculated by taking the average of the L*, a* and b* values obtained in each measurement. The clinical detectability threshold of the color change was accepted as 3.3 units. The obtained data were analyzed statistically. Clinically detectable color change was observed in all groups except the negative control group (ΔE>3.3). It was determined that MM caused more undesirable coloration on the 30th day and 90th day in the positive control group than in the CV group on the 90th day compared to phthalocyanine (p<0.05). While none of the dentin tubule occlusion methods were superior to each other in preventing undesirable coloration caused by phthalocyanine, Er: YAG caused less undesirable coloration than CV only on the 90th day in preventing undesirable coloration caused by MM (p<0.05). All dentin tubule occlusion methods used in the present study were effective in preventing some degree of unwanted discoloration. However, it was found that no technique could completely prevent unwanted coloration.