The Migration and the Fate of Dental Pulp Stem Cells

Overexpression of programmed cell death ligand 1 reduces LPS-induced inflammatory cytokine upregulation and enhances osteo/odontogenic-differentiation of human dental pulp stem cells via upregulation of CCCTC-binding factor

OBJECTIVE

The aim of this study was to explore the effect and mechanism of programmed cell death ligand 1 (PD-L1) in promoting the proliferation and osteo/odontogenic-differentiation of human dental pulp stem cells (hDPSCs) by mediating CCCTC-binding factor (CTCF) expression.

DESIGN

The interaction between PD-L1 and CTCF was verified through co-immunoprecipitation. hDPSCs transfected with PD-L1 overexpression and CTCF knockdown vectors were treated with lipopolysaccharide or an osteogenic-inducing medium. Inflammatory cytokines and osteo/odontogenic-differentiation related genes were measured. Osteo/odontogenic-differentiation of hDPSCs was assessed using alkaline phosphatase (ALP) and alizarin red S staining.

RESULTS

Overexpression of PD-L1 inhibited LPS-induced pro-inflammatory cytokine upregulation, cell proliferation, ALP activity, and calcium deposition in hDPSCs and elevated the expression of osteo/odontogenic-differentiation related genes; however, such expression patterns could be reversed by CTCF knockdown. Co-immunoprecipitation results confirmed the binding of PD-L1 to CTCF, indicating that PD-L1 overexpression in hDPSCs increases CTCF expression, thus inhibiting the inflammatory response and increasing osteo/odontogenic-differentiation of hDPSCs.

CONCLUSION

PD-L1 overexpression in hDPSCs enhances the proliferation and osteo/odontogenic-differentiation of hDPSCs and inhibit the inflammatory response by upregulating CTCF expression.

An innovative cell-based transplantation therapy for an immature permanent tooth in an adult: a case report

BACKGROUND

Immature teeth with necrotic pulps present multiple challenges to clinicians. In such cases, regenerative endodontic procedures (REPs) may be a favorable strategy. Cells, biomaterial scaffolds, and signaling molecules are three key elements of REPs. Autologous human dental pulp cells (hDPCs) play an important role in pulp regeneration. In addition, autologous platelet concentrates (APCs) have recently been demonstrated as effective biomaterial scaffolds in regenerative dentistry, whereas the latest generation of APCs-concentrated growth factor (CGF), especially liquid phase CGF (LPCGF)-has rarely been reported in REPs.

CASE PRESENTATION

A 31-year-old woman presented to our clinic with the chief complaint of occlusion discomfort in the left mandibular posterior region for the past 5 years. Tooth #35 showed no pulp vitality and had a periodontal lesion, and radiographic examination revealed that the tooth exhibited extensive periapical radiolucency with an immature apex and thin dentin walls. REP was implemented via transplantation of autologous hDPCs with the aid of LPCGF. The periodontal lesion was managed with simultaneous periodontal surgery. After the treatment, the tooth was free of any clinical symptoms and showed positive results in thermal and electric pulp tests at 6- and 12-month follow-ups. At 12-month follow-up, radiographic evidence and three-dimensional models, which were reconstructed using Mimics software based on cone-beam computed tomography, synergistically confirmed bone augmentation and continued root development, indicating complete disappearance of the periapical radiolucency, slight lengthening of the root, evident thickening of the canal walls, and closure of the apex.

CONCLUSION

hDPCs combined with LPCGF represents an innovative and effective strategy for cell-based regenerative endodontics.

Determination of the Ideal Tooth Surface and Pain Threshold to Improve the Efficacy of an Electric Pulp Tester in the Diagnosis of Pulp Sensitivity and Vitality in Premolar and Molar Teeth: A Cross-Sectional Study

Introduction The electric pulp tester (EPT) is an extensively used diagnostic tool in endodontics. However, several factors, especially the location and thickness of the tooth structures, such as enamel and dentine, can affect the result of an electric pulp test. Further, these factors also alter the pain threshold, which may lead to an inaccurate diagnosis. Hence, it is crucial to ascertain the optimal tooth surface that requires minimal time to elicit a response and pain threshold to enhance the effectiveness of the electric pulp tester for diagnosing the status of the pulp. Methods Fifty volunteers (36 males and 14 females) aged 18 to 32 years without any prior experience with the EPT were recruited. The EPT was placed on the seven premolar sites, and molar teeth with an appropriate electrolyte as a conducting medium were tested. The pain threshold values were recorded using the stopwatch, whereas pain assessment was carried out using the Memojis pain scale. An independent sample t-test and descriptive statistics were used to analyze the data statistically. Results The buccal occlusal third in males (27.3±8.6 seconds) and the buccal middle third in females (28.5±8.2 seconds) showed lower response times than other sites in premolar teeth. The mesiobuccal cusp showed a lower response time for males (21.3±6.6 seconds) and females (21.5±6.2 seconds) in molar teeth. Of all the various sites tested, the majority of the individuals chose pain scores of 0 (36 in premolars, 84 in molars), two (138 in premolars, 180 in molars), and four (96 in premolars, 42 in molars) in both the premolars and molars. Conclusion The ideal sites for placing the EPT in premolars for males and females are the buccal occlusal third and the buccal middle third. At the same time, the mesiobuccal cusp is the ideal site for molars in both males and females, as it is responded to the quickest by the electric current. Most individuals have experienced a score of two (hurts a little bit) for the perceived pain using EPT for both the molars and premolars.