Hydroxyapatite coated magnesium alloy for peripheral nerve regeneration

( Akram Abdo Almansoori ),( Kyung Won Ju ),( Bongju Kim ),( Soung Min Kim ),( Sung-mi Lee ),( Jong-ho Lee ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2018 Oral Biology Research (Oral Biol Res) Vol.42 No.3

Magnesium (Mg) has been used as a neuroprotective agent and for orthopedic and cardiovascular stent applications for a long time. Mg is a promising material for neural regeneration own to its metallic nature, biodegradability, and biocompatibility. To evaluate the benefit of hydroxyapatite (HA) coated Mg alloy (WE43) nerve conduit in peripheral nerve injury regeneration. In vitro cell adhesion and proliferation of PC12 cells and Schwann cells over pure Mg, WE43, HA coated pure Mg (HA-Mg), and HA coated WE43 (HA-WE43) disks were assessed using scanning electron microscope and EZ-CYTOX assay. In vivo study was also performed for sham, silicone nerve conduits, and HA-WE43 nerve conduits to evaluate rat sciatic nerve regeneration over 10 mm gap. These rats were observed for three months with weekly functional assessment using sciatic functional index. Regeneration was evaluated through retrograde neuron labeling and histomorphometric analysis at the end of the experiment. Non-coated pure Mg and WE43 conduits showed fast resorption rate and high gas formation. Higher adhesion and proliferation of PC12 cells were found in HA-WE43 disks. At the end of three months, HA-WE43 nerve conduit showed mild resorption without detectable gas formation in the surrounding tissue. However, only scanty regenerated neural tissue was found within the conduit. HA-WE43 nerve conduit showed controlled degradation and absence of gas formation with scanty regenerated neural tissue.

Digitally guided surgery and prosthesis with narrow implants in the anterior region

( Jae-seok Kang ),( Seon-a Kim ),( Yu-ri Heo ),( Mee-kyung Son ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2021 Oral Biology Research (Oral Biol Res) Vol.45 No.1

The purpose of this case report is to introduce a flapless method of securely placing a narrow implant on the upper and lower anterior teeth missing area with narrow bone width using a digitally guided surgery system and to introduce a process of prosthesis manufacturing using an oral scanner without a working model. The narrow implants in this case report remained stable for a certain period of time (12, 24, and 36 months after surgery) without loss of the surrounding bones.

Thermoluminescent dosimetry of panoramic radiography

( Yo-seob Seo ),( Sun-kyoung Yu ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2021 Oral Biology Research (Oral Biol Res) Vol.45 No.1

This study aims to calibrate a thermoluminescence dosimeter (TLD) using a diagnostic radiation device and evaluate the dose of panoramic radiography. TLD-100s were calibrated using a solid-state dosimeter (Unfors Mult-O-Meter 512L; Unfors Instruments, Billdal, Sweden) and a diagnostic radiation device (HDT-500R; Hyun Dai Medical X-ray Co., Paju, Korea). Forty eight TLDs were placed in 24 sites of a head and neck phantom of a male (ART-210; Radiology Support Devices Inc., Long Beach, CA, USA), and panoramic radiation was performed under exposure parameters of 70 kVp and 10 mA using a ProMax (Planmeca, Helsinki, Finland). Using the International Commission on Radiological Protection (ICRP) 2007 recommendation, the effective dose of panoramic radiography was calculated from the absorbed doses of the tissues of the 24 TLD sites in a head and neck phantom. The absorbed dose of the TLD site was higher in the parotid gland (right: 1854.4 µGy, left: 1788.9 µGy) and lower in the calvarium anterior (3.8 µGy). The effective dose was calculated at 28.4 µSv. The cancer and heritable risks were 1.56×10-6 and 5.67×10-8, respectively. The TLD was calibrated using a diagnostic radiographic device, and the panoramic radiographic dose was evaluated. The findings of this study could be helpful in future dose studies.

Effect of erbium-doped yttrium-aluminum-garnet laser on surface characteristics and biocompatibility of resorbable blast media titanium

( So-won Uhm ),( In-seok Lee ),( Bo-hyun Kim ),( Young-joon Kim ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2021 Oral Biology Research (Oral Biol Res) Vol.45 No.2

Er:YAG laser irradiation can modify the surface characteristics of titanium surface. This study aimed to evaluate the influence of Er:YAG laser irradiation on mechanical, chemical, and biological characteristics of resorbable blast media (RBM) titanium surfaces. RBM disks were divided into 4 groups. Control groups were nonirradiated RBM disks. Laser irradiated groups were divided into the RBM-50, RBM-100, and RBM-250 group which irradiated Er:YAG laser at energy level 50, 100, and 250 mJ/pulse, respectively. In scanning electron microscopy (SEM) images, whereas the RBM-50 group showed slightly melted surface area, RBM-100 and RBM- 250 groups showed broken areas caused by Er:YAG laser. Laser irradiated groups had significantly higher roughness than the control group. The roughness of the RBM-50 group was comparable with the RBM-100 group and significantly lower than the RBM-250 group (p<0.05). In X-ray diffractometer analysis of the laser irradiated group, Ti (002) (rutile) proportion to Ti (101) (anatase) was decreased according to energy level. In X-ray photoelectron spectroscopy analysis, RBM-50 and RBM-100 groups show the crystal change from acidic Ti-OH to basic Ti-OH. MC3T3-E1 cells of all groups adhered and proliferated well on the surfaces and their morphology was not different between groups in SEM images. The alkaline phosphatase activity levels of RBM-50 and RBM-100 groups showed higher than those of the control group (p<0.05). Therefore, within the limitations of this study, Er:YAG laser irradiation at low energy levels can modify mechanical and chemical characteristics of the RBM surface, leading to improve the biological responses of osteoblastic cells on the surface.

Comparison of various activation methods of root canal irrigants for soft-tissue removal

( Kun-hwa Sung ),( Tae-young Park ),( Ho-keel Hwang ),( Hyoung-hoon Jo ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2021 Oral Biology Research (Oral Biol Res) Vol.45 No.1

The aim of this study was to evaluate the effects of various activation methods on the efficiency of soft-tissue removal in the artificial root canal system. The artificial root canal system, including the isthmus, was fabricated using poly (methyl methacrylate). Grounded pork was filled in the isthmus, soaked with NaOCl for 5 minutes, and followed by various irrigation and activation procedures. Group 1 performed irrigation using a side-vented needle and syringe, and group 2 performed sonic activation using an activator. Furthermore, group 3 performed ultrasonic activation using EndoSonic PS tip with EMS scaler engine. Subsequently, the time taken for the complete removal of grounded pork from the isthmus was measured. The sonic and ultrasonic activation groups showed significantly higher irrigation efficacy than those without activation. The ultrasonic activation group showed a higher efficiency when compared with the sonic activation group. In conclusion, additional activation of irrigants can improve the efficiency of soft-tissue removal in anatomical structures, such as the isthmus.

Analysis of reasons for extracting permanent teeth among Korean adults with oral diseases

( Jae-joon Byun ),( Eun-sun Jang ),( Dae-ryong Kong ),( Gyeong-je Lee ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2021 Oral Biology Research (Oral Biol Res) Vol.45 No.1

This study aimed to analyze the main reasons for the extraction of permanent teeth among Koreans with oral diseases. The electronic medical record data for past 10 years was used in a target population comprising of 26,795 adults diagnosed with oral disease and scheduled to undergo permanent tooth extraction. The oral diseases were classified into periodontal disease, dental caries, impacted teeth, prosthodontic treatment, orthodontic treatment, tooth fracture, trauma, and others. The relationship between these diseases and permanent tooth extraction was analyzed. Permanent teeth were extracted due to periodontal disease (34.5%), dental caries (26.6%), and tooth impactions (22.3%). Permanent teeth were extracted as the cause of dental caries (28.6%) and periodontal disease (45.9%) from patients in 26-35 and 46-55 years of age respectively. The mandibular first molars (17.2%), mandibular second molars (16.0%), maxillary first molars (14.7%), and maxillary second molars (14.3%) were extracted due to dental caries. The incidence of periodontal disease was highest in the mandibular central incisor (72.6%; p<0.05). These findings indicated that periodontal disease was the chief cause of extraction of permanent teeth among Korean adults.

Clinical application of a superficial layer of the mylohyoid muscle during bone augmentation: A case report

( Min-cheol Yang ),( Seong-joong Park ),( Won-pyo Lee ),( Byung-ock Kim ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2020 Oral Biology Research (Oral Biol Res) Vol.44 No.4

Guided bone regeneration is a reliable technique used to augment deficient alveolar bone defects. Soft tissue management is one of the several critical factors involved in the bone augmentation procedure. It is very dangerous to extend the lingual flap without creating tension owing to the presence of anatomical structures, particularly in the lower posterior region. Here, we report a method, where the lingual flap is advanced further using the mylohyoid muscle for primary wound closure in the augmented area (lower posterior edentulous region).

Finite element analysis of stress distribution around a short implant according to a horizontally reduced bone in the mandible

( Kyeong-ok Lim ),( Kyung-min Kim ),( Min-cheol Yang ),( Hee-jung Kim ),( Won-pyo Lee ),( Byung-ock Kim ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2021 Oral Biology Research (Oral Biol Res) Vol.45 No.1

This study evaluates the stress distribution around a short implant supporting a bone with various horizontally reduced levels using a three-dimensional finite element stress analysis. A three-dimensional finite element model was designed by placing a short implant in a jaw model with a 2-mm-thick cortical bone. Horizontal bone loss was employed at 1-mm intervals from 0 to 3 mm, and a 400- N load was applied to the central fossa in a 0° vertical direction and 30° inward-inclined direction to the implant axis. Furthermore, the maximum principal stress generated in the short implant supporting the bone was calculated using a three-dimensional finite element stress analysis. As a result of the finite element analysis, the maximum principal stresses in a 0° vertical direction according to horizontal bone loss from 1 mm to 3 mm in the cortical bone were 45.13, 79.44, and 75.53 (MPa), respectively, and in the cancellous bone were 7.63, 9.28, and 9.60 (MPa), respectively. The maximum principal stresses in a 30° inward-inclined direction according to horizontal bone loss from 1 mm to 3 mm in the cortical bone were 132.34, 172.07, and 216.26 (MPa), respectively, and in the cancellous bone were 16.34, 27.43, and 26.37 (MPa), respectively. Within the limitations of this study, the authors concluded that the bone stress values tended to be higher around the implant neck under a 30° inward load and in the cortical bone according to the horizontally reduced bone level.

The incidence of oral and maxillofacial lesions in children over a 10-year period (2010-2020) in East Azerbaijan

( Amirala Aghbali ),( Negin Arianpour ),( Sepideh Vosough Hosseini ),( Maedeh Vakili Saatloo ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2020 Oral Biology Research (Oral Biol Res) Vol.44 No.4

This study aimed to investigate pediatric patients aged < 12 years who had oral and maxillofacial lesions and were referred to the Tabriz Pediatric Hospital during the 10-year period of 2010-2020. In this prospective, cross-sectional study, documents with final diagnosis were separated, and the demographic data of the patients, including age, sex, and location of lesions, were collected from the records. Microscopic slides of each case were reviewed by two pathologists. The lesions were classified into the following five categories: developmental lesion, benign tumors, malignant tumors, infectious lesions, and inflammatory lesions. One-way ANOVA was applied to compare the frequency of the lesions using SPSS Statistics for Windows, Version 17.0 (SPSS Inc., Chicago, IL, USA). Overall, 9,314 biopsy records of pediatric patients aged ≤12 years were studied. We identified and analyzed 8,993 cases with inflammatory lesions, 171 with developmental lesions, 71 with reactive lesions, 64 with benign tumors, and 15 with malignant tumors. Furthermore, the most common lesion site was the neck ( >98.5%), and the most uncommon site was the nasal area, accounting for only two lesions. Moreover, among inflammatory lesions, follicular hyperplasia and tonsillitis were the most common with a frequency of 99.1% (8,916 cases) observed in 3,656 (40.7%) female and 5,337 (59.3%) male. Sixty-nine (40.4%) female and 102 (59.6%) male had developmental lesions. The present results showed that the most common type was inflammatory lesion whereas the least common type was malignant lesion.

Characterization of the hemin-binding property of Porphyromonas endodontalis

( Eun Jeong Kim ),( Si Young Lee ) 조선대학교 치의학연구원(구 조선대학교 구강생물학연구소) 2021 Oral Biology Research (Oral Biol Res) Vol.45 No.2

Porphyromonas endodontalis, found in the root canal of teeth, requires iron for growth. However, the mechanism of iron uptake in P. endodontalis remains unclear. The ability of bacteria to utilize heme compounds to acquire iron for growth has been reported in some pathogenic bacteria. In the present study, we analyzed the ability of P. endodontalis to obtain iron from heme compounds. Further, we investigated the hemin-binding characteristics of P. endodontalis and the relationship between hemin binding and Congo red binding. To confirm the bacterial growth in hemin-supplemented medium, iron was removed from the medium with an ironchelator, and hemin was supplemented to an iron-free medium. The hemin-binding characteristics of P. endodontalis were analyzed by incubating bacteria with hemin and measuring the optical density of the supernatant obtained via centrifugation, using hemin concentration standard curve. Although growth of P. endodontalis was not observed in the iron-depleted medium, it was observed in a hemin-supplemented medium. Further, hemin binding was dependent on the concentrations of hemin and bacteria. Hemin binding proceeded quickly in P. endodontalis, and the incubation temperature had no effect on this binding. Similar to hemin binding, Congo red binding of P. endodontalis was dependent on Congo red and bacterial concentrations. In addition, Congo red binding of P. endodontalis was inhibited by hemin prebinding. Hemin-agarose beads and SDS-PAGE were used to identify a 40-kDa protein that could be involved in hemin binding. The results showed that P. endodontalis could bind to and use hemin to obtain the iron required for growth.