Laser Applications in Regenerative Endodontics: A Review.

Introduction: Developing regenerative endodontic treatment (RET) is an exciting approach to managing immature permanent teeth with pulp necrosis. RET is usually performed in two clinical steps: disinfection (first step) and tissue engineering (second step). Recently, laser therapy has entered the field of RET. This study aimed to provide an overview of the literature that employed laser therapy for root regeneration. Methods: A comprehensive search was performed on four databases, including PubMed, Web of Science, Scopus, and Google Scholar. The searched keywords were laser, regenerative endodontics, immature permanent teeth, and dental pulp necrosis, and related English-published articles were included up to October 2023. Results: Thirteen studies utilized a laser for RET. In the first step of RET, both high-power and low-level lasers (through photodynamic therapy [PDT]) may be applied for canal disinfection. In contrast, regenerative procedures in the second step of RET are just accelerated by low-power lasers (biostimulation). The literature does not support the benefit of laser-assisted irrigation in improving the clinical success of RET. There is some evidence that laser-assisted disinfection with a diode laser may provide comparable results to triple antibiotic paste in reducing bacterial counts in root canals while providing slightly better clinical and radiographic outcomes. PDT may be an effective and suitable adjunct to conventional disinfection methods in immature, necrotic teeth. Conclusion: Low-power lasers may be beneficial tools for improving the results of regenerative endodontics through chemical disinfection in the first step (PDT) or by biostimulation in the second step of RET.

Necroptosis has a crucial role in the development of chronic periodontitis.

Background and aim: Periodontitis is a non-communicable chronic inflammatory disease that affects the entire periodontium and its severe types cause irreparable destruction. The purpose of this study was to determine the type of cell death in chronic periodontitis (CP) with the expression of receptor-interacting protein kinase (RIPK) type1 and RIPK3 genes. Materials and methods: This cross-sectional study was carried out from September 2019 to 2020. The samples (38 participants) were divided into two groups: 20 recently diagnosed CP patients and 18 healthy individuals. Participants' data was collected in the periodontology Department, Dental school, Mashhad University of Medical Sciences and sent to the Immunology Lab for assessment of RIPK1 and RIPK3 expressions using quantitative real time-PCR. Results: The study sample consisted of 30 females (78.9%) and 8 males (21.1%) with a mean age of 34 ± 5 years. The expression of the genes of interest in CPs exhibited an opposite pattern. Although, RIPK3 gene expression was significantly greater in CP patients compared to the control group (P = 0.024), the expression of RIPK1 decreased (p < 0.001). Moreover, no significant correlation was observed between age and gender with these molecules in CPs. Conclusion: The RIPK3 selectively contributes to necroptosis, therefore, it seems that RIPK3-mediated necroptosis is involved in chronic periodontitis. RIPK1 also participates in necroptosis, but mostly in apoptosis. Therefore, necroptosis as an unprogrammed inflammatory cell death induced by pathogenic damages seems to be another mechanism complicated in periodontitis and could be used as a novel target for CP therapy.

Matrix Metalloproteinase-3 but Not Matrix Metalloproteinase-9, Implicated in the Manifestation of Chronic Periodontitis.

Background: Periodontal disease is an inflammatory condition affecting the tooth's supporting tissues, resulting in gradual loss of periodontal ligament (PDL), alveolar bone, and gum resorption. Neutrophil and monocyte/macrophage, destructive proteases like matrix metalloproteinase (MMP)-3 and MMP-9 play pivotal roles in such lesions in periodontitis. Therefore, this study aims to compare the level of MMP-3 and MMP-9 gene expression in patients with or without periodontitis in an Iranian population. Methods: This cross-sectional study was carried out on 22 chronic periodontitis patients and 17 healthy control subjects referred to the department of periodontology, Mashhad Dental School. In both groups, the gingival tissue was removed during surgery and transferred to the Molecular Biology Laboratory for MMP-3 and MMP-9 gene expression evaluation. The qRT-PCR, TaqMan method was used for gene expression assessments. Results: The average age of periodontitis patients was 33± 5 years, and in controls, 34.7± 6 with no significant differences. The mean MMP-3 expression in periodontitis patients was 146.67±38.7, and in controls, 63.4±9.1. The difference was statistically significant (P=0.04). The mean expression of MMP-9 in periodontitis patients and controls were 103.8± 21.66 and 87.57± 16.05, respectively. Although the target gene expression in patients was higher, the difference was insignificant. Furthermore, there was not any significant correlation between age or gender with the expression of MMP3 or MMP9. Conclusion: The study demonstrated that the MMP3 seems to have a destructive impact on the gingival tissue in chronic periodontitis, but not MMP9.