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Purpose The purpose of this study is to obtain the optimal three-dimensional (3D) printing condition through the accuracy evaluation of the protective dental splints (PDSs) produced using 3D printed dental casts under various conditions. Design/methodology/approach The dental casts of dentiform were made using the conventional method and three digital methods. The three 3D printers used one or two materials for each, and the density of the material was varied to find the appropriate printing condition. PDSs were fabricated by the same method using vacuum former on conventional dental casts, and 3D printed dental casts. PDSs were mounted on a dentiform, and the accuracy was measured according to the criteria. Findings All of the PDSs fabricated using the traditional method showed the highest accuracy, whereas the PDSs made using 3D printed casts showed accuracies that varied with the type of printer, material characteristics and printing density. Achieving the accuracy required for 3D printed dental casts to be used as protective dental devices made with a vacuum former requires appropriate materials and 3D printing density. The findings of this study can be used when making 3D printed models and individual PDSs through intraoral scanning for patients in whom it is difficult to take impressions using traditional methods. Originality/value When a digital device is applied to the fabrication of PDSs, it has the advantage of saving time and materials and preventing damage to teeth and periodontal tissue that may occur during the conventional method.

Dental clinics are exposed to various uncomfortable noises. The aim of this study was to quantify the effectiveness of active noise control devices in dental treatment conditions. Two types of commercial headsets (Airpods Pro, QC30) and two types of dental headsets (Alltalk, Quieton Dental) were used for the experiment. Three sounds (high-speed handpiece, low-speed handpiece, and suction system) were measured at three different distances from the dental teeth model, typodont. The distances of 10, 40, and 70 cm reflected the positions of the patient, assistant, and practitioner’s ears, respectively. Sound analysis was performed, and the significance of differences in the maximum noise level using each device was determined with the Kruskal–Wallis test. Dental noise was characterized by the peak in sound pressure level (SPL) at 4–5 kHz and >15 kHz frequencies. The commercial headsets efficiently blocked 1 kHz and 10 kHz of noise. The dental headsets efficiently reduced 4–6 and >15 kHz noise. Quieton had the highest maximum SPL in all situations and positions among the four devices. For a better dental clinic, however, active noise control devices more suitable for the characteristics of dental noise should be developed.

Objectives The aim of this study was to determine the effectiveness of using an access opening guide in teaching ideal access opening shape and preventing excessive tooth loss, with a focus on predoctoral dental students. Methods Ninety teeth that were mounted in a box just below the level of the cementoenamel junction using tray resin were randomly divided into two study groups. An access opening guide produced using a 3D printer (AOG-3DP) was designed using cone-beam computed tomography (CBCT). The AOG-3DP was applied in the test groups, while no aid was used in the control group. Access preparations in both groups performed by predoctoral dental students were scanned using CBCT to detect overpreparation. The preparation time and access cavity volume were evaluated. Results The mean times required for achieving access opening were 327.2 and 97.4 s in the control and AOG-3DP groups, respectively, for premolars, and 547.4 and 104.5 s for molars. The mean volumes for premolars and molars differed from the ideal cavities by 38.1 and 72.2 mm3 , respectively, in the control group, and by -2.0 and -8.7 mm3 the AOG-3DP group. Conclusions Using the AOG-3DP significantly reduced the access opening time for premolars and molars. However, there is a limitation in that CBCT DICOM images must be converted to stereolithographic .stl files in order to be printed via 3D technology. This requires additional preclinical treatment time for imaging and subsequent printing. It could be considered that this can be a useful method in difficult cases.

Objectives The purpose of the present study was to investigate which peri-transplant dental treatments were deemed necessary, and to determine retrospectively how often these treatments were actually performed, in patients who had received organ transplants. Materials and methods Medical records of the Department of Advanced General Dentistry at Yonsei University Dental Hospital were searched to identify liver or kidney transplant recipients who attended from 1st March 2014 to 31st December 2017. A total of 418 patients were identified, and their medical charts were reviewed. Sex, underlying systemic disease, oral hygiene status, dental treatment deemed necessary, dental treatment actually performed and durations of follow-up were tabulated. Results More than half (53.8%) of the liver transplant recipients had poor oral hygiene, and poor oral hygiene was statistically significantly more prevalent in the liver transplant group than in the kidney transplant group (40.3%). In liver recipients in whom scaling was deemed to be required pre-transplant, the rate of it actually being performed pre-transplant was high (83.2%). By contrast, the rates of tooth extraction and prosthetic treatment actually being performed pre-transplant were low (12.8% and 0%, respectively). In kidney recipients, the rates of scaling, tooth extraction and prosthetic treatment actually performed pre-transplant, when deemed to be required, were 93.5%, 10.0% and 0.0%, respectively. Conclusions We recommend that patients scheduled to receive an organ transplant be referred to a dental clinic as soon as possible beforehand, to remove any potential sources of oral infection. Educating physicians, as well as their patients, about the importance of early dental screening and pre-transplant dental treatment is essential.

The greater palatine artery (GPA) is one of the most important anatomical structure for free gingival grafts or connective-tissue grafts during soft tissue surgery for dental implants. Several studies have identified the approximate location of the GPA, but it is impossible to detect its exact location during surgery due to large variability between individuals. The authors, therefore, investigated the course of the GPA using intraoral ultrasonography to determine the feasibility of using real-time nonionizing ultrasonography for implant surgery.This study included 40 healthy young participants. The courses of the GPA were identified using intraoral ultrasound probes from the first premolar to the second molar. The distance from the gingival margin to the GPA (GM-GPA) and the depth of the palatal gingiva from the GPA (PG-GPA) were measured by two independent examiners. Measurements were analyzed statistically, and interexaminer reliability was determined.The distance of the GM-GPA and the mean depth of the PG-GPA were 14.8 ± 1.6 mm and 4.10 ± 0.51 mm (mean ± SD), respectively. GM-GPA decreased when the GPA ran from the second molar to the first molar, and GM-GPA was significantly shorter in females (P 0.05). PG-GPA increased when the GPA ran to the posterior teeth. Interexaminer measurement agreements were excellent, with intraclass correlation coefficient values of 0.983 and 0.918 for GM-GPA and PG-GPA, respectively.Using an intraoral ultrasound probe, real-time GPA tracking is possible, which is expected to help reduce the possibility of bleeding during surgery.

Purpose: Bone-modifying agents (BMAs) are key components in the management of cancer patients with bone metastasis. Despite their clinical benefits, the use of BMAs is associated with adverse dental events including medication-related osteonecrosis of the jaw (MRONJ). This study investigated the rate of preoperative dental surveillance to reduce the incidence of adverse dental events including MRONJ after BMA treatment in patients with bone metastasis from breast and prostate cancer. Methods: Data, including age, cancer diagnosis, administered BMAs, and adverse dental events during cancer treatment, of patients with bone metastasis from breast and prostate cancer who received at least one infusion of BMA between 2007 and 2019 were extracted from the Korean National Health Insurance Service (KNHIS) dataset. Results: Of the 15357 patients who received BMAs, 1706 patients (11.1%) underwent dental check-ups before BMA treatment. The proportion of patients receiving dental check-ups increased from 4.4% in 2007 to 16.7% in 2019. Referral for dental check-up was more frequent in clinics and primary hospitals than in tertiary hospitals, and from the departments of internal medicine and urology than from the department of general surgery, regardless of the patient's health insurance status. After BMA treatment, 3328 patients (21.6%) developed adverse dental events, including tooth extraction (73.0%), abscess (16.9%), acute periodontitis (5.3%), acute pericoronitis (2.6%), and MRONJ (2.2% of 3328, 0.5% of 15357). Conclusions: Considering the long treatment period in patients with metastatic cancer, coordination between dentists and oncologists is necessary to ensure appropriate dental treatment before the initiation of BMAs.

Denosumab (Dmab) has been suggested as a first-line therapy for osteoporotic patients. However, a standardized protocol for the prevention of Dmab induced medication-related osteonecrosis of the jaw (MRONJ) has not yet been established. Thus, we investigated the factors that can affect Dmab induced MRONJ (DRONJ) to elucidate the relationship between invasive dental treatment and Dmab administration in patients who underwent Dmab and invasive dental treatment (especially tooth extraction) between October 2016 and March 2020. Four of the 98 patients developed MRONJ before and after tooth extraction. Two out of 4 patients developed MRONJ regardless of invasive treatment after Dmab administration and proceeded with extraction, and one patient developed DRONJ after Dmab administration and extraction. The other patient underwent a tooth extraction without osteoporosis treatment, and spontaneous DRONJ developed after Dmab administration. All MRONJ/DRONJ cases reported in this study show that MRONJ/DRONJ can develop as chronic inflammation without invasive dental treatment, therefore, implementing preventive dental treatment before initiating Dmab treatment is necessary to reduce the likelihood of DRONJ.

Denosumab has been suggested as a first-line therapy for osteoporotic patients. However, a standardized protocol for the prevention of denosumab induced medication-related osteonecrosis of the jaw (MRONJ) has not yet been established. The purpose of this study was to report denosumab induced MRONJ cases, and investigate the factors affecting the occurrence of MRONJ in patients who underwent denosumab and invasive dental treatment (especially tooth extraction) between October 2016 and March 2020. Four of the 98 patients developed MRONJ before and after tooth extraction. The participants were divided into two groups: receiving only denosumab (n = 51) and receiving bisphosphonate as first treatment and denosumab as second treatment (n = 47). There was no significant difference between groups in the occurrence of MRONJ and factors affecting MRONJ. Two out of 4 patients developed MRONJ regardless of invasive treatment after denosumab administration and proceeded with extraction; one patient developed MRONJ after denosumab administration and extraction. The other patient underwent a tooth extraction without osteoporosis treatment, and non-identified MRONJ developed after denosumab administration. MRONJ cases reported in this study show that MRONJ can develop as chronic inflammation without invasive dental treatment; therefore, implementing preventive dental treatment before initiating denosumab treatment is necessary to reduce the occurrence of MRONJ.

The purpose of this study was to develop and validate a visually explainable deep learning model for the classification of C-shaped canals of the mandibular second molars in dental radiographs.The periapical and panoramic images of 1000 mandibular second molars were collected from 372 patients. The diagnostic performance of the deep learning system using periapical and panoramic radiographs was investigated in respect to its ability to determine whether the second mandibular molar showed a C-shaped canal configuration. The assessment of the canal configuration of cone-beam computed tomographic volumes from 372 patients (740 mandibular second molars) was used as a gold standard.The deep convolutional neural network algorithm model showed high accuracy in predicting the C-shaped canal variation among mandibular second molars in both periapical and panoramic images. The model demonstrated best results when using image patches including only the root portion of the tooth and when using both periapical and panoramic images for training (area under the curve [AUC] = 0.99). The model's diagnostic performance using only the root portion of the tooth (AUC: periapical = 0.98 and panoramic = 0.95) was similar to a specialist (AUC: periapical = 0.95 and panoramic = 0.96) and better than a novice general clinician (AUC: periapical = 0.89 and panoramic = 0.91). Both the specialist and general clinician showed better diagnostic performance when reading panoramic radiographs compared with periapical images.With further optimization of the test data using a larger data set and improvements made in the model, a deep learning system may be expected to effectively diagnose C-shaped canals and aid clinicians in practice and education.

Objectives The purpose of this study was to determine the effect of administering intermittent parathyroid hormone 1-34 [teriparatide, (PTH)] on the maxillary sinus lift and bone grafting in osteoporotic rabbits induced by ovariectomy and glucocorticoid. Materials and methods Ovariectomies were performed on 20 female New Zealand white rabbits that were randomly divided into two groups: (a) the PTH group (n = 10), in which 10 μg kg-1 day-1 PTH was injected subcutaneously 5 days a week for 5 weeks (from 1 week before until 4 weeks after sinus surgery), and (b) the saline group (n = 10), in which saline substituted PTH at the same dose, mode of administration, and duration. Bone grafting with bovine bone mineral was augmented into 13 sinuses, and bone grafts and implants were simultaneously performed in seven sinuses, in both groups. Animals were sacrificed at 4 weeks after surgery. To determine whether PTH was an effective treatment for osteoporosis, we measured the bone mineral density (BMD) of the right femur using micro-computed tomography and performed radiographic and histometric analyses of the maxillary sinus surgery site. The Mann-Whitney test was used for statistical analysis. Results It was found that BMD increased in the femur, whereas none of the radiographic and histometric parameters differed significantly between the groups in the sinus, while there were large interindividual variations within groups. Conclusions These findings suggest that intermittent PTH does not promote new bone formation in the augmented maxillary sinus of ovariectomized rabbits.

Objective. In this study, we evaluated changes in bone remodeling in an irradiated rat calvarial defect model according to duration of hyperbaric oxygen therapy. Materials and Methods. The 28 rats were divided into four groups. Radiation of 12 Gy was applied to the skull, and 5-mm critical size defects were formed on both sides of the skull. Bone grafts were applied to one side of formed defects. From the day after surgery, HBO was applied for 0, 1, and 3 weeks. At 6 weeks after bone graft, experimental sites were removed and analyzed for radiography, histology, and histomorphometry. Results. Micro-CT analysis showed a significant increase in new bone volume in the HBO-3 group, with or without bone graft. When bone grafting was performed, BV, BS, and BS/TV all significantly increased. Histomorphometric analysis showed significant increases in %NBA and %BVN in the HBO-1 and HBO-3 groups, regardless of bone graft. Conclusion. Hyperbaric oxygen therapy was effective for bone regeneration with only 1 week of treatment.

BACKGROUND Schoolchildren are in a developmental period whose permanent teeth replace primary dentition. It is also a period with a high incidence of gingivitis and caries, which can be improved with correct tooth brushing. Advances in information technology have led to the development of smart health devices that assist in tooth brushing. OBJECTIVE To compare the effectiveness of computer-assisted toothbrushing using a toothbrushing instruction (TBI) method called the smart toothbrush and smart mirror (STM) system with that of conventional TBI for plaque control in schoolchildren. METHODS This randomized controlled clinical trials analyzed and compared the reduction of the modified Quigley-Hein plaque index between the two methods in 42 schoolchildren. The participants were randomly assigned to an STM system group (n=21) or a conventional-TBI group (n=21). The plaque indexes were evaluated at baseline, immediately after TBI (day 0), and 1 week and 1 month after TBI. RESULTS The STM system and conventional TBI led to an average reduction of 40.50% and 40.57%, respectively, in whole mouth plaque. Reductions in the plaque indexes in each time period tested were observed in both groups (P CONCLUSIONS The computer-assisted STM system showed a similar efficacy for dental plaque control in children compared with conventional TBI. The STM system may be beneficial for maintaining oral hygiene by improving tooth brushing ability. CLINICALTRIAL ClinicalTrials.gov NCT04627324； https://clinicaltrials.gov/ct2/show/NCT04627324

Mucormycosis is a rare fungal infection with high morbidity and mortality and a very poor prognosis. However, aggressive medical and surgical management can result in survival rates exceeding 80%. The most common sites involved in mucormycosis infection are the sinus, lung, skin and soft tissues, gastrointestinal system, central nervous system, and rarely the mandible. Systemic risk factors for mucormycosis are diabetes mellitus (DM), neutropenia, corticosteroid use, hematologic malignancies, organ transplantation, metabolic acidosis, deferoxamine use, and advanced age. Local risk factors are a history of trauma, burns, surgery. We report on two patients with mucormycosis of the jaw. While one case presented as mucormycois involving the maxillary sinus in a patient with uncontrolled DM, the other was a rare case of mandibular mucormycosis in a patient with acute myeloid leukemia.

Sensory dysfunction is the most serious complication that occurs after extracting lower third molars in close proximity to the inferior alveolar nerve (IAN). Even experienced surgeons have difficulties in avoiding nerve damage when the root is anatomically adjacent to the nerve canal. A useful method for reducing nerve damage during extraction is to perform orthodontic extrusion, in which the distance between the nerve and the root increased after applying an orthodontic force on the third molar while extruding the tooth. Here, we report the case of a 37-year-old female who presented with a partially erupted left lower third molar and risk of IAN nerve damage because of close anatomical proximity between the nerve and root. She underwent extraction using a miniscrew placed in the maxilla and a routine orthodontic mechanism using a cross-arch elastic band that induced a 3-mm vertical eruption in the impacted third molar without using complex orthodontic devices. In addition, tilting the dental axis to the lingual side resolved the proximity between the IAN and the tooth, thereby allowing extraction to proceed without major complications.

Nerve injury especially inferior alveolar nerve (IAN) is the one of the complications that occur when the mandibular third molar (M3) is extracted and in case of high risk patients, coronectomy might be an alternative to tooth extraction. The purpose of this retrospective study was to analyze root migration and its influencing factors at 6 months after coronectomy in both 2- and 3-dimensions using periapical view and cone-beam computed tomography (CBCT). We analyzed 33 cases of root remnant after coronectomy and measured the amount of migration in CBCT. The following factors that could possibly affect root migration were also analyzed: age, gender, number of M3 roots, shape of M3s, Pell, and Gregory classification, mesiodistal (MD) angulation, buccolingual (BL) angulation, contact point with the second molar, root curvature, and complete removal of the coronal portion. Migration of greater than 2 mm was found in 64% of the roots in the 2-dimensional (2D) analysis, and the average root migration was 4.11 mm in the 3-dimensional (3D) analysis. The factors affecting migration were the root morphology, complete removal of the coronal portion, impaction depth, and MD angulation in the 2D analysis, and MD and BL angulation in the 3D analysis. Ensuring sufficient space for root migration especially considering angulation, depth and complete removal of the coronal portion might be important factors after coronectomy of the M3. Root remnant after coronectomy of M3 may migrate in young patients who has sufficient empty coronal space and this may reduce the nerve damage by the separation of IAN and M3.

Objective: This retrospective study investigated the incidence rate of accidental foreign body aspiration and ingestion according to patient sex and age and the dental department. This study was aimed to verify the risk factors for accidental foreign body aspiration and ingestion in dental practice. Methods: Accidental foreign body aspiration and ingestion cases were collected by searching the electronic health records and the Safety Report System of Yonsei University Dental Hospital from January 2011 to December 2017. The collected data comprised the patient age, sex, and medical condition, treatment procedure, and foreign objects that were accidentally aspirated or ingested. The incidence rate was calculated as the number of accidental foreign body aspirations and ingestions relative to the total number of patient visits, and differences according to the patient sex and age and the dental department were identified statistically. Results: There were 2 aspiration and 37 ingestion cases during the 7-year analysis period. The male-to-female incidence ratio was 22.7:8.1. The incidence rate trended upward with age and increased rapidly among those aged 80 or older. Seven of the 39 patients had intellectual disability, Lou Gehrig’s disease, dystonia, or oral and maxillofacial cancer. The incidence rate was the highest in the Predoctoral Student Clinic and the Department of Prosthodontics. The most frequently swallowed objects were fixed dental prostheses and dental implant components. Conclusion: The incidence rate of accidental foreign body aspiration and ingestion is higher in men than in women and the highest in patients aged 80 or older. The most frequently aspirated or ingested objects are fixed dental prostheses and dental implant components. Dental practitioners need to identify high-risk patients and apply various methods to prevent accidental foreign body aspiration and ingestion in dental clinics. Inexperienced dentists should be especially careful. Keywords: accidental foreign body aspiration and ingestion, incidence rate, dental treatment

Several novel oral anticoagulants (NOACs) are currently prescribed for patients suffering from atrial fibrillation, pulmonary thromboembolism, and venous thrombosis. However, there is no clinical guideline for dental treatment in patients taking NOACs. This study investigated bleeding events related to various dental treatments. This retrospective study included 120 patients (153 cases) who were prescribed NOACs and received dental procedures in the Department of Advanced General Dentistry at Yonsei University Dental Hospital from January 2014 to June 2017. The indication for NOACs, initiation of NOACs, duration of discontinuance, creatinine clearance, and type of dental treatment were investigated. Bleeding events were assessed at a follow-up visit to the clinic. Postoperative bleeding occurred in only 9 of the 153 included cases; they comprised 2 cases of scaling, 3 cases of simple extraction, 3 cases of the first stage of implant surgery, and 1 case of resin filling. The creatinine clearance (P = .111) and duration of discontinuance (P = .222) did not differ significantly between the groups with and without bleeding events. Our data indicate that most dental treatments may be performed in patients taking NOACs without an increased likelihood of bleeding events regardless of the discontinuance duration. Moreover, any postoperative bleeding can be stopped by applying compressive pressure or local hemostatic agents. Our study suggests that patients taking NOACs who need dental treatments may have a bleeding tendency based on our retrospective data. Preoperative history taking and treatment modification should therefore be considered before performing dental surgery.

This retrospective study investigated the incidence rate of accidental foreign body aspiration and ingestion according to patient sex, age, and dental department. This study aimed to verify whether the incidence rate is higher in geriatric than in younger patients and whether it is different among dental departments.Accidental foreign body aspiration and ingestion cases were collected from electronic health records and the safety report system of Yonsei University Dental Hospital from January 2011 to December 2017. The collected data included patients' age, sex, medical conditions, treatment procedures, and foreign objects that were accidentally aspirated or ingested. The incidence rate was calculated as the number of accidental foreign body aspirations and ingestions relative to the total number of patient visits. Differences depending on the patients' sex, age, and dental department were statistically identified.There were 2 aspiration and 37 ingestion cases during the 7-year analysis period. The male to female incidence ratio was 2.8:1. The incidence rate increased with age and increased rapidly among those aged 80 years or older. Seven of the 37 patients with accidental foreign body ingestion had intellectual disability, Lou Gehrig's disease, dystonia, or oral and maxillofacial cancer. The incidence rate was highest in the Predoctoral Student Clinic and the Department of Prosthodontics. The most frequently swallowed objects were fixed dental prostheses and dental implant components.The incidence rate of accidental foreign body aspiration and ingestion differed according to patient sex, age, and dental department. Dental practitioners must identify high-risk patients and apply various methods to prevent accidental foreign body aspiration and ingestion in dental clinics. Inexperienced practitioners should be particularly careful.

ObjectiveThe purpose of this study was to evaluate the effects of miniscrew insertion angle and vertical facial type on the interradicular miniscrew-root distance available for molar distalization.Materials and methodsCone-beam computed tomography images of 60 adults with skeletal Class I occlusion exhibiting hyperdivergent (n = 20), normodivergent (n = 20), and hypodivergent (n = 20) facial types were used. Placement of a 6-mm long, 1.5-mm diameter, tapered miniscrew was simulated at a site 4 mm apical to the cementoenamel junction, with insertion angles of 0°, 30°, 45°, and 60° relative to the transverse occlusal plane. The shortest linear distance between the miniscrew and anterior root at four interradicular sites was measured: maxillary second premolar and first molar (Mx 5-6), maxillary first and second molars (Mx 6-7), mandibular second premolar and first molar (Mn 5-6), and mandibular first and second molars (Mn 6-7).ResultsMiniscrew-root distance significantly increased as the insertion angle increased from 0° to 60°. In the mandible, the distances significantly differed among vertical facial types, increasing in the following order: hyperdivergent, normodivergent, and hypodivergent. The minimum mean distance was found in the Mx 6-7 (30°; 0.86±0.35 mm), and the maximum mean distance was found in the Mn 5-6 (60°; 2.64±0.56 mm). The rates of miniscrews located buccally outside the root distalization path were up to 70% and 55% when the miniscrews were placed at 60° insertion angles in the Mx 5-6 and Mn 5-6 regions, respectively.ConclusionsMiniscrew-root distance increased significantly with the increased insertion angle, and the amount of increase was affected by the miniscrew placement site and vertical facial type. To ensure adequate distalization of the posterior segment, the miniscrew should be inserted at an angle in the interradicular area between the second premolar and first molar.

BACKGROUND High-quality photos are critical for the remote diagnosis of dental trauma and thus are beneficial to the prognosis. The quality of the images obtained using a cell phone depends on the level of dental and photography knowledge of the person who is taking the photos. OBJECTIVE This study aimed to determine the efficacy of photography education in improving images used for the remote diagnosis of dental trauma. METHODS The subjects comprised 30 laypeople and 30 dentists who were randomly assigned to 15 subgroups with 2 subjects in each. Each subject was asked to take photos of their own anterior teeth and those of their partner on the assumption that an accident occurred using both an iPhone 4s and iPhone 6. Education about how to take an appropriate photo of the anterior teeth for teleconsultation purposes was then provided, after which photos were taken again. Photos were assessed by a dentist for their usefulness in diagnosis. RESULTS This study analyzed 965 photos: 441 taken by laypeople and 524 taken by dentists. Photos taken after providing education had significantly higher scores for all assessment items than those taken before education (PP CONCLUSIONS Both laypeople and dentists might find photography education useful for when they are taking photos to be used in teleconsultations. The type of cell phone does not significantly affect the usefulness of such photos.

Regeneration of peripheral nerve injury remains a major clinical challenge. Recently, mesenchymal stem cells (MSCs) have been considered as potential candidates for peripheral nerve regeneration; however, the underlying mechanisms remain elusive. Here, we show that human gingiva-derived MSCs (GMSCs) could be directly induced into multipotent NPCs (iNPCs) under minimally manipulated conditions without the introduction of exogenous genes. Using a crush-injury model of rat sciatic nerve, we demonstrate that GMSCs transplanted to the injury site could differentiate into neuronal cells, whereas iNPCs could differentiate into both neuronal and Schwann cells. After crush injury, iNPCs, compared with GMSCs, displayed superior therapeutic effects on axonal regeneration at both the injury site and the distal segment of the injured sciatic nerve. Mechanistically, transplantation of GMSCs, especially iNPCs, significantly attenuated injury-triggered increase in the expression of c-Jun, a transcription factor that functions as a major negative regulator of myelination and plays a central role in dedifferentiation/reprogramming of Schwann cells into a progenitor-like state. Meanwhile, our results also demonstrate that transplantation of GMSCs and iNPCs consistently increased the expression of Krox-20/EGR2, a transcription factor that governs the expression of myelin proteins and facilitates myelination. Altogether, our findings suggest that transplantation of GMSCs and iNPCs promotes peripheral nerve repair/regeneration, possibly by promoting remyelination of Schwann cells mediated via the regulation of the antagonistic myelination regulators, c-Jun and Krox-20/EGR2.

The prevalence of thyroid disease, particularly hyperthyroidism, has rapidly increased in Korea in the past 10 years. Therefore, it is important to consider the complete medical history including thyroid disease in patients under dental treatment. Both the drugs used for dental treatment and psychological symptoms associated with treatment can induce emergencies in hyperthyroid patients. This case report considers emergency situations during dental treatment for hyperthyroid patients, and discusses risk factors and related concerns.

There is no genetic activity information with the functions of dental pulp and periodontal ligament in human. The purpose of this study was to identify the gene-expression profiles of, and the molecular biological differences between periodontal ligament and dental pulp obtained from human permanent teeth. cDNA microarray analysis identified 347 genes with a fourfold or greater difference in expression level between the two tissue types 83 and 264, of which were more plentiful in periodontal ligament and dental pulp, respectively. Periodontal ligament exhibited strong expression of genes related to collagen synthesis (FAP), collagen degradation (MMP3, MMP9, and MMP13), and bone development and remodeling (SSP1, BMP3, ACP5, CTSK, and PTHLH). Pulp exhibited strong expression of genes associated with calcium ions (CALB1, SCIN, and CDH12) and the mineralization and formation of enamel and dentin (SPARC/SPOCK3, PHEX, AMBN, and DSPP). Among these genes, SPP1, SPARC/SPOCK3, AMBN, and DSPP were well known in dental research. However, the other genes are the newly found and it may help to find a good source of regenerative therapy if further study is performed.

Background High-quality photos are critical for the remote diagnosis of dental trauma and thus are beneficial to the prognosis. The quality of the images obtained using a cell phone depends on the level of dental and photography knowledge of the person who is taking the photos. Objective This study aimed to determine the efficacy of photography education in improving images used for the remote diagnosis of dental trauma. Methods The subjects comprised 30 laypeople and 30 dentists who were randomly assigned to 15 subgroups with 2 subjects in each. Each subject was asked to take photos of their own anterior teeth and those of their partner on the assumption that an accident occurred using both an iPhone 4s and iPhone 6. Education about how to take an appropriate photo of the anterior teeth for teleconsultation purposes was then provided, after which photos were taken again. Photos were assessed by a dentist for their usefulness in diagnosis. Results This study analyzed 965 photos: 441 taken by laypeople and 524 taken by dentists. Photos taken after providing education had significantly higher scores for all assessment items than those taken before education (P Conclusions Both laypeople and dentists might find photography education useful for when they are taking photos to be used in teleconsultations. The type of cell phone does not significantly affect the usefulness of such photos.

Background Emergencies in dentistry can be classified as medical and dental. Medical emergencies occur mainly during dental treatment in patients with a systemic disease. Dental emergency departments are largely divided into dental emergency rooms located in dental college hospitals and medical emergency rooms located in medical institutions. This study aimed to analyze the characteristics of and provide help to dental emergency patients in a dental hospital. Methods Overall, 1806 patients admitted to a dental emergency room at Yonsei University Dental Hospital for 1 year were included. The data collection period was from October 1, 2014 to September 30, 2015. An investigator reviewed medical records from the electronic medical record (EMR) system and radiographs. Results The patients were 1,070 men and 736 women. The sex ratio was 1.45:1. The commonest age group was of 0-9 years, including 451 (25.0%) patients, followed by 20-29 years, including 353 (19.5%) patients, and 30-39 years, including 277 (15.3%) patients. Of the 108 patients transferred to the Severance emergency department, 81 had trauma, 19 were in pain, 4 were bleeding, and 4 had other complaints. Among chief complaints, 1,079 patients (60.3%) had trauma, 564 (31.5%) had pain, and 75 (4.2%) had bleeding. Twenty-three cases (1.3%) were caused by temporomandibular disorder (TMD). Conclusion Dentists should be able to adequately assess patients in a dental emergency room and treat trauma, pain, and bleeding.