Il Young Jung

Continued development of the root separated from the main root.

INTRODUCTION Endodontic infection or physical trauma of a developing tooth might lead to unusual situation for root development. METHODS Two cases are presented. Both cases involved immature mandibular second premolars with infected pulps. In the first case, the tooth was treated by apexification, whereas revascularization procedures were performed in the second case. Interestingly, a separated root tip was observed with the main root at the initial presentation of case 2. RESULTS At recall after apexification, a separate root tip was observed apically to the main root end, and root development continued in case 1. In the second case, the separate root displayed continuing root formation, but the main root did not gain root thickness or length. CONCLUSIONS These cases revealed that Hertwigs epithelial root sheath and stem cells from the apical papilla can be separated from the main tooth structure by an external force or iatrogenic factors and thereafter produce a separate root tip.

Failure of orthograde MTA filling: MTA wash-out?

Mineral trioxide aggregate (MTA), which was originally developed for repair of root perforations, is a biocompatible material with numerous clinical applications in endodontics. MTA must be allowed to set in the presence of moisture to optimize the material’ s physical and chemical properties. In the clinic, occasionally unset MTA has been detected after application of MTA on the tooth, and the reason has been unclear. This case report presents MTA washed-out for several years after placement at the root apex as an apical plug, and discusses the reason and things to consider in clinics. [J Kor Acad Cons Dent 2011;36(6):510514.]

The effect of canal filling with gutta-percha or resilon on Enterococcus faecalis in bovine dentinal tubules

The purpose of this study was to observe the effect of canal filling on the bacteria left in the dentinal tubules and to compare the sealing ability between Gutta-percha and Resilon. The bovine dentin block models were prepared E. faecalis was inoculated to dentin blocks and incubated. The dentin blocks were divided into 5 groups. Group 1 was the negative control. Group 2 was the positive control. Group 3 was filled with ZOE based sealer and Gutta-percha, Group 4 with resin based sealer and Gutta-percha, and Group 5 with resin based sealer and Resilon. After 24 hour, the blocks were incubated at for 1, 2, 3 and 4 weeks on BHI agar plates. The internal dentin portion of the blocks was removed using ISO 027, 029, 031, 035 round burs and the dentin chips were incubated at for 24 hour Following incubation, the optical density of the medium was measured. The data were statistically analysed using repeated measures ANOVA and one-way ANOVA. The results were as follows, 1. There. was statistically significant reduction in the number of E. faecalis of the group where dentinal tubules were completely sealed with nail varnish in comparison with the groups obturated with gutta-percha or resilon (p 0.05). 3. Under the conditions of this experiment, E. faecalis survived up to 4 weeks after obturation with gutta-percha or resilon (p > 0.05).

Proteome Expression in Human Periodontal Ligament after Delayed Hypothermic Preservation

Introduction Previous occasional successes after delayed replantation suggest that the presence of viable cells may not be the only factor for successful periodontal regeneration in delayed replantation. Various other factors such as proteins or the extracellular matrix (ECM) may play a role in this process. The purpose of this study was to characterize changes in the proteome components of periodontal ligament (PDL) tissue after hypothermic preservation of the tooth. Methods Extracted teeth were divided into 4 groups: immediate sampling, sampling after 1 week of preservation at 4°C, sampling after 2 weeks of preservation at 4°C, and sampling after 1 week of dry storage at room temperature as a negative control. PDL tissues were collected from the root and stored immediately in liquid nitrogen. The tissues were subjected to 2‐dimensional gel electrophoresis, and spot selection was executed. Selected spots that maintained the protein volume were then processed with matrix‐assisted laser desorption and ionization time‐of‐flight mass spectrometry to identify the nature of the proteins. Results Thirty‐five selected spots were analyzed. Sixteen spots were identified as vimentin, and 3 spots were type VI collagen. The size of the 16 vimentin spots decreased gradually with increasing storage time, from 0 to 2 weeks, and decreased rapidly after dry storage. However, only the dry storage group differed significantly from the immediately sampled group. Conclusions Vimentin was the most prominent protein followed by type VI collagen in volumetrically maintained protein spots. Although these proteins are known to be closely related with ECM integrity, the role of these proteins in delayed replantation is beyond the scope of this study. Further studies are needed to elucidate the possible role of these proteins for periodontal healing of delayed replantation. HighlightsVimentin and type VI collagen were the most prominent proteins in the periodontal ligament after delayed hypothermic preservation of teeth.The total size of the vimentin spots decreased gradually with increasing storage time, from 0 to 2 weeks, and decreased rapidly after dry storage.Only the dry storage group differed significantly from the immediately sampled group.

In vivo evaluation of accuracy and consistency of two electronic apex locators

Objectives: To evaluate the accuracy and consistency of two different apex locators at both the Apex and0.5 marks.Materials and Methods: Twenty-six root canals was scheduled for extraction for periodontal or prosthodonticreasons. Thirteen canals were measured using Root ZX and the rest by i-ROOT. The root canal length wasmeasured both the at 0.5 mark and the Apex mark. The file was t hen fixed to the tooth, and the distancefrom the file tip to the major foramen of each canal was measur ed after removing the root dentin under themicroscope so that the major foramen and the file tip were seen.Results: 1. When the Apex mark was used, 100% of both the Root ZX and i- ROOT groups were within 0.5 mm ofthe major foramen.2. When 0.5 mark was used, 100% of the Root ZXgroup and 77% of the i-ROOT group were within 0.5mm of the major foramen.3. In terms of standard deviation and quartile value, the Apex mark was more consistent than 0.5 mark inthe Root ZX group, and 0.5 mark was more consistent in the i-RO OT group, but there was no statisti-cally significant difference when compared with t-test.4. The root canal length difference between the Apex mark and 0.5 mark was 0.22 mm and 0.46 mm inthe Root ZX and i-ROOT groups, respectively.Conclusions: In this study, the Apex mark was the more consistent mark. Ther efore, it is recommended tosubtract 0.5 mm, which is the average length between the apex and apical constriction, from the root canallength at the Apex mark to obtain the working length clinically.

Scanning electron microscopic examination of resected root apices obtained from endodontic microsurgery.

This study was designed to examine the morphological features of the resected root apices obtained from endodontic microsurgery using a scanning electron microscope (SEM) as well as their anatomical effect on the clinical outcome of the surgical treatment. One-hundred-six resected root apices from 91 patients/surgeries were obtained by endodontic microsurgery, and fixed immediately for storage. The resected apices were prepared for SEM to examine their morphological features, such as the number and size of the apical foramina. The patients were periodically checked up at least 1 year and the clinical outcome of the microsurgery was judged as a success or failure according to the Molvens criteria. The SEM findings and the clinical outcome of apical surgery were evaluated to see any potential correlation between them. The SEM examination revealed that 60.4% of specimens had more than two portals of exit on the resected root apices and the size of the major foramen was at least 386 micrometer and 334 micrometer from maxillary and mandibular molar, respectively. With a recall rate of 72.9%, 91.9% of the surgical cases were decided to have successful outcomes. Based on this SEM study, a relatively high frequency of multiple portals of exit was existed and the sizes of major foramina were bigger than that were reported in previous reports. The clinical outcomes of endodontic microsurgery were not correlated with the anatomical features of resected apical root apices. SCANNING 38:455-461, 2016.

Partial pulp necrosis caused by excessive orthodontic force

As the dental pulp is encased with a rigid, noncompliant shell, changes in pulpal blood flow or vascular tissue pressure can have serious implication for the health of pulp. Numerous studies have demonstrated that orthodontic force application may influence both blood flow and cellular metabolism, leading degenerative and/or inflammatory responses in the dental pulp. The aim of this case report is to present a case about tooth with chronic periapical abscess which showed normal vital responses. Excessive orthodontic force is thought to be the prime cause of partial pulp necrosis. Owing to remaining vital tissue, wrong dianosis can be made, and tooth falsely diagnosed as vital may be left untreated, causing the necrotic tissue to destroy the supporting tissuses. Clinician should be able to utilize various diagnostic tools for the precise diagnosis, and be aware of the endodontic-orthodontic inter-relationship. [J Kor Acad Cons Dent 2011;36(2):149-153.]