Extrusion bond strength and disinfection of E. faecalis from canal dentin using synchronized microbubble photodynamic activation and photon-induced photoacoustic streaming.

OBJECTIVE: This study aimed to assess the antimicrobial effectiveness of a new disinfection regimen Curcumin photosensitizer (CP), Synchronized Microbubble Photodynamic Activation (SYMPA), Photon-induced photoacoustic streaming (PIPS), and its impact on the extrusion bond strength (EBS) of root filling material to canal dentin. MATERIALS AND METHODS: Root canal treatments of sixty mandibular incisors were performed, and an overnight culture of E. faecalis was cultivated in the BHI medium. A volume of 1 mL was introduced into twenty root canals. All the samples were randomly allocated into 4 groups based on the irrigation used: -Group 1: 2.5% NaOCl+17% EDTA (Control), Group 2: CP+17% EDTA, Group 3: SYMPA+17% EDTA, and Group 4: PIPS+17% EDTA. The viable bacterial count was estimated, and 15 specimens from each group were obturated, followed by sectioning in 1-mm thick slices. The EBS was measured using a universal testing machine, and failure modes were analyzed using a stereomicroscope at 40x magnification. Means and standard deviations (SD) of the survival rate of E. faecalis and EBS of root filling to the dentin were analyzed using ANOVA Tukey multiple comparison t-tests (p=0.05). RESULTS: Group 1 (2.5% NaOCl+17% EDTA) demonstrated the highest survival rate of E. faecalis. Group 3, in which SYMPA+17% EDTA was used to sterilize the canal, unveiled the lowest survival rate (1.55±0.11 CFU/mL). Similarly, the coronal section of Group 3 specimens (8.67±0.43MPa) demonstrated the highest EBS. However, an apical section of Group 1 samples (2.81±0.11MPa) displayed the lowest outcome of bond integrity. Intergroup comparison analysis revealed that Group 4 (PIPS+17% EDTA) and Group 2 (CP+17% EDTA) samples demonstrated comparable values of bond integrity and bacterial survival. CONCLUSIONS: Canal disinfection using the synchronized microbubble photodynamic activation (SYMPA) technique proved to be a promising alternative technique in decreasing the count of E. faecalis and improving extrusion bond strength of gutta percha to canal dentin.

Adjunctive use of different lasers Er, Cr: YSGG, femtosecond, potassium titanyl phosphate and photodynamic therapy on radicular disinfection bonded to glass fiber post.

OBJECTIVE: The aim of this study was to evaluate and compare the effect of different laser prototypes [Er, Cr: YSGG laser (ECYL), potassium titanyl phosphate laser (KTP), and Femtosecond laser (FSL)]and curcumin photosensitizer (CP) activated by Photodynamic therapy (PDT) on the bond strength of Pre-fabricated fiber reinforced composite (PFRC) post-bonded to radicular dentin. MATERIALS AND METHODS: A total of fifty mandibular single-rooted closed apex teeth were extracted carefully, assembled, and decoronated up to the cementoenamel junction. The working length of all specimens was determined by using a 10 K patency file and later, were cleaned and shaped with Protaper NiTi system using the crown down approach, dried, and obturated with gutta-percha using an AH Plus sealer. Post space was prepared by guiding peeso-reamer. Based on the method of disinfection, the samples were allocated to five groups (n=10) at random: samples in group 1: curcumin photosensitizer (CP) activated by PDT, samples in group 2 disinfected using 5.25% NaOCl+17% EDTA, samples in group 3 disinfected using 5.25% NaOCl+17% EDTA+FSL, specimens in group 4 sterilized using 5.25% NaOCl+17% EDTA+KTP and samples in group 5 cleaned with 5.25% NaOCl+17% EDTA+ECYL. The fiber post was cemented via self-etch resin cement into the post space. All specimens with posts were dissected perpendicularly into apical, middle, and coronal dentin and subjected to the universal testing machine for push-out bond strength (PBS) testing. Statistical analysis was performed using a One-Way analysis of variance and Post Hoc Tukey multiple comparison tests. RESULTS: The highest PBS was corroborated when the radicular canal was disinfected with 5.25% NaOCl +17% EDTA+ ECYL at all three root levels (coronal, middle, and apical) and the lowest was adjudicated by decontamination with CP activated by PDT at all inspected root levels. Intergroup comparison presented that specimens in group 2: 5.25% NaOCl+17% EDTA (control) and group 4: 5.25% NaOCl+17% EDTA+KTP revealed comparable PBS outcome to group 5 (p>0.05) while samples in group 3 revealed the equivalent PBS values to group 1 (p<0.05) at all three root levels. CONCLUSIONS: Er, Cr: YSGG laser and potassium titanyl phosphate laser when used in combination with the conventional canal disinfection 5.25% NaOCl and 17% EDTA demonstrated the highest push-out bond strength values at coronal, middle, and apical levels of the root.

Immunohistochemical expression of PCNA, STRO-1 and CD 44 in the healing of experimentally induced periapical lesions in rats.

OBJECTIVE: The aim of the study was to determine the expression of cell proliferating marker, anti-proliferating cell nuclear antigen (anti-PCNA) and mesenchymal stem cell (MSC) markers (anti-STRO-1 and anti-CD44) in periapical periodontitis and their role in the healing of periapical lesion in periapical periodontitis. MATERIALS AND METHODS: Ninety Sprague-Dawley male rats (100 g) were divided into 3 groups: Experimental group I (EG I: n = 30), experimental group II (EG II: n=30) and control group (CG: n = 30). Periapical lesions were experimentally developed by leaving the dental pulp of maxillary first molars mesial root open to oral environment for 4 weeks. Conventional root canal treatment was performed in EG II. Maxillary first molars along with alveolar bone were resected and fixed. The processed samples were stained with routine hematoxylin and eosin (H&E), and evaluated immunohistochemically using antibodies against anti-PCNA, anti-STRO-1, and anti-CD44 polyclonal antibodies. Data were analyzed using Chi-square test and a p-value of <0.05 was considered significant. RESULTS: Immunostaining of anti-PCNA showed 30%, 70% and 53.3% positive staining in CG, EG I, and EG II, respectively (p<0.001). Moreover, the CD44 staining was 20% in CG in contrast to 63.6% in EG I and 43.3 in EG II. STRO-1 staining in CG was 10%, 50% in the EG I and 36.6% in the EG II (p<0.001). CONCLUSIONS: Periapical inflammatory tissues expressed significant proliferative cell marker PCNA and mesenchymal stem cell markers STRO-1, and CD44. These findings further reaffirm the promising role of mesenchymal stem cells in the healing of periapical periodontitis.