ABSTRACT
@#A cemental tear is defined as an incomplete or complete detachment of the cementum along the dentino-cemental junction (CDJ) or the incremental line within the body of the cementum, which can also involve part of the root dentine adjacent to the cementum. The pathogenesis of cemental tears is not fully elucidated. From the literature review, possible predisposing factors were identified, including tooth type, sex, age, periodontitis, previous periodontal treatment or root canal treatment, history of dental trauma, and occlusal trauma or excessive occlusal force. The morphology of cemental tears can be either piece-shaped or U-shaped, which usually contributes to periodontal and periapical breakdown. Clinically, cemental tears have a unitary periodontal pocket and present with symptoms mimicking localized periodontitis, apical periodontitis, and vertical root fractures. Imaging examination is of great significance for the clinical diagnosis of cemental tears, which often manifest as thin ‘prickle-like’ radiopaque masses located longitudinally adjacent to the affected root surface. Exploratory surgery is needed in some cases. Although intraoperative cemental fragments and cemental lines on the root surface can assist in the diagnostic process, histopathology examination is the gold standard for the diagnosis of cemental tears. The treatment methods vary depending on the timing of the correct diagnosis and the clinical or radiological manifestations. With the development of regenerative biomaterials and the development of intentional replantation, an increasing number of affected teeth can survive for a long time. The aim of this review is to systematically describe the biological basis and predisposing factors, clinical features, radiographic and histological characteristics, diagnosis and clinical management of cemental tears, and treatment outcomes to help make a clear diagnosis and develop a personalized treatment plan.
ABSTRACT
Abstract Human periodontal ligament stem cells (hPDLSCs) are promising cells for dental and periodontal regeneration. Objective This study aimed to develop novel alginate-fibrin fibers that encapsulates hPDLSCs and metformin, to investigate the effect of metformin on the osteogenic differentiation of hPDLSCs, and to determine the regulatory role of the Shh/Gli1 signaling pathway in the metformin-induced osteogenic differentiation of hPDLSCs for the first time. Methodology CCK8 assay was used to evaluate hPDLSCs. Alkaline phosphatase (ALP) staining, alizarin red S staining, and the expression of osteogenic genes were evaluated. Metformin and hPDLSCs were encapsulated in alginate-fibrinogen solutions, which were injected to form alginate-fibrin fibers. The activation of Shh/Gli1 signaling pathway was examined using qRT-PCR and western blot. A mechanistic study was conducted by inhibiting the Shh/Gli1 pathway using GANT61. Results The administration of 50 μM metformin resulted in a significant upregulation of osteogenic gene expression in hPDLSCs by 1.4-fold compared to the osteogenic induction group (P < 0.01), including ALP and runt-related transcription factor-2 (RUNX2). Furthermore, metformin increased ALP activity by 1.7-fold and bone mineral nodule formation by 2.6-fold (P<0.001). We observed that hPDLSCs proliferated with the degradation of alginate-fibrin fibers, and metformin induced their differentiation into the osteogenic lineage. Metformin also promoted the osteogenic differentiation of hPDLSCs by upregulating the Shh/Gli1 signaling pathway by 3- to 6- fold compared to the osteogenic induction group (P<0.001). The osteogenic differentiation ability of hPDLSCs were decreased 1.3- to 1.6-fold when the Shh/Gli1 pathway was inhibited, according to ALP staining and alizarin red S staining (P<0.01). Conclusions Metformin enhanced the osteogenic differentiation of hPDLSCs via the Shh/Gli1 signaling pathway. Degradable alginate-fibrin hydrogel fibers encapsulating hPDLSCs and metformin have significant potential for use in dental and periodontal tissue engineering applications. Clinical Significance Alginate-fibrin fibers encapsulating hPDLSCs and metformin have a great potential for use in the treatment of maxillofacial bone defects caused by trauma, tumors, and tooth extraction. Additionally, they may facilitate the regeneration of periodontal tissue in patients with periodontitis.