Nan-Sim Pang

Effect of EDTA on Attachment and Differentiation of Dental Pulp Stem Cells

INTRODUCTION In regenerative endodontics, it is believed that EDTA induces odontoblast differentiation by releasing growth factors from the dentin matrix. The aim of this study was to evaluate the effect of EDTA on the attachment and differentiation of dental pulp stem cells (DPSCs). We also investigated whether the behavioral changes of DPSCs could be caused by biochemical components released from EDTA-treated dentin. METHODS Cells were obtained from human third molars, and the stem-like nature of the cells was investigated by flow cytometric analysis. DPSCs were seeded on EDTA-treated and untreated dentin slices. After 3 days of culture, cell attachment was evaluated by cell density, fibronectin 1 gene expression level using quantitative real-time polymerase chain reaction, and scanning electron microscopy. After 21 days of culture, the expression of differentiation genes was investigated by quantitative real-time polymerase chain reaction, and calcification was observed using alizarin red S staining. To investigate the EDTA-induced growth factor release, DPSCs were cultured with or without direct contact with the EDTA-treated dentin surface. RESULTS After 3 days of culture, both the cell density and fibronectin expression level were significantly higher in the EDTA-treated dentin group. After 3 weeks, the DPSCs on the EDTA-treated dentin surfaces showed higher expression levels of dentin sialophosphoprotein and dentin matrix protein 1, whereas the DPSCs cultured without direct contact with the EDTA-treated dentin surfaces did not exhibit these findings. CONCLUSIONS Our results showed that EDTA induced cell attachment and odontoblastic/osteoblastic differentiation, which was observed only in the group in which the DPSCs were placed in direct contact with the EDTA-treated dentin surfaces. These findings suggest that EDTA is beneficial for achieving successful outcomes in regenerative endodontics.

Implant displacement into the mandible: an unusual complication during implant surgery.

In contrast with problems regarding initial stability of dental implants in the posterior maxilla, heat generation during bone drilling is one of the complications that can occur in the mandible which is usually composed of dense bone. This report presents an unusual case of implant displacement into the mandibular posterior area of a middle-aged woman. This problem was presumably caused by poor bone density, loss of cortical bone engagement, and differences in bone quality between the alveolar bone and the basal bone.

Autotransplantation of an ectopic impacted premolar with sinus lift and allogenic bone graft

AIM This article presents a case report of autogenous tooth transplantation to a site which had insufficient bone volume using a sinus lift and allogenic bone graft. SUMMARY An ectopic, fully impacted premolar tooth was autotransplanted from its ectopic impaction site into its original site, where there was insufficient recipient vertical bone volume because of sinus expansion. The deciduous tooth was extracted from the recipient site, and the sinus membrane detached and elevated via the alveolar socket. Allogenic bone grafting was performed, and the impacted premolar was transplanted into the prepared site. To improve adaptation, the recipient site was prepared using a rapid prototype tooth model, a replica tooth which allowed complete socket preparation in advanced of the actual removal of the donor tooth. The donor tooth was fixed with sutures and maintained for 17 days to allow physiologic movement. Root canal treatment was initiated 24 days after autotransplantation, and an intra-canal medicament was used for 4 months. Canal filling was completed 5 months after autotransplantation. There was no root resorption of the transplanted tooth, and the grafted bone was well preserved and had no signs of infection. KEY LEARNING POINTS When the recipient bone volume is insufficient, autotransplantation can be preceded by bony augmentation. The preparation of the recipient tooth socket using a tooth replica from CBCT reduces the extra-oral time of the actual tooth and promotes better periodontal ligament healing. Careful evaluation of the pulp status of the donor tooth is important in advance of timely endodontic treatment.

Endodontic and Surgical Treatment of Root Damage Caused by Orthodontic Miniscrew Placement

INTRODUCTION Miniscrews are being increasingly used for anchorage control in orthodontics. Despite the concern over root damage caused by miniscrews, there are few reports of precise clinical evaluations and appropriate management of that damage. In the case presented herein, the root damage caused by the placement of miniscrews was repaired by root canal treatment and surgical intervention. METHODS A 44-year-old man received orthodontic treatment for intrusion of the left maxillary first molar with a miniscrew anchorage system. During that treatment, the miniscrews had fallen out and had to be reinserted more than 6 times in the same area. Two years later, the patient complained of a spontaneous pain in the maxillary left molar region. Although the patient received root canal treatment, intraoral sinus tracts could still be detected, and the patients discomfort persisted. Periradicular surgery revealed that the persistent infection was related to root surface damage caused by orthodontic miniscrew placement. Healing was achieved by a combination of root canal treatment and surgical intervention. RESULTS Scanning electron microscopy of the damaged distobuccal root apex revealed a mature biofilm consisting of a network of matrix that contained mostly rod-like and spherical bacteria. At a 12-month recall checkup, the patient was free of pain. A repeat periapical radiograph revealed reduction of the pretreatment radiolucent lesion. CONCLUSIONS More careful planning of miniscrew placement is necessary to lessen the danger of root damage. Furthermore, a precise evaluation of both root and pulpal damage and careful consideration of the choice of optimal treatment modality are needed.

Assessment of sterilization effect and the alteration of surface texture and physical properties of gutta-percha cone after short-term chemical disinfection

The purposes of this study were firstly to identify the microbial species on gutta-percha (GP) cones exposed at clinics using polymerase chain reaction, and secondly to evaluate the short-term steril- ization effect of three chemical disinfectants. It also evaluated the alteration of surface texture and physical properties of GP cones after 5-min soaking into three chemical disinfectants. 150 GP cones from two endodontic departments were randomly selected for microbial detection using PCR assay with universal primer. After inoculation on the sterilized GP cones with the same microorganism identified by PCR assay, they were soaked in three chemical disinfectants: 5% NaOCl, 2% Chlorhexidine, and ChloraPrep for 1, 5, 10, and 30 minutes. The sterilization effect was evaluated by turbidity and subculture. The change of surface textures using a scanning electron microscope and the tensile strength and elongation rate of the GP cones were measured using an Instron 5500 (Canton). Statistical analysis was performed. Four bacterial species were detected in 29 GP cones (19.4%), and all the species belonged to the genus Staphylococcus. All chemical disinfectants were effective in sterilization with just 1 minute soaking. On the SEM picture of NaOCl-soaked GP cone, a cluster of cuboidal crystals was seen on the cone surface. The tensile strength of NaOCl-soaked group was significantly higher than the oth- er groups (p < 0.05). Also, all disinfectants significantly increased the elongation rate of GP cones compared to the fresh GP cone (p < 0.05). Present data demonstrate that three chemical disinfec- tants are useful for rapid sterilization of GP cone just before obturation. (J Kor Acad Cons Dent