HIF-1α Overexpression Using a Protein Transduction Domain to Increase the Osteogenic Potential of SHED

Background: Hypoxia-Inducible Factor 1 (HIF-1) alpha (HIF-1α) is known to be expressed in hypoxia and affects stemness and bone differentiation. Protein Transduction Domains (PTDs) safely and effectively deliver proteins into cells. This study combined HIF-1α delta Oxygen-Dependent Degradation Domain–Transcription Modulation Domain (ntHIF-1α-ΔODD-TMD) with the PTD and then used it to treat Stem cells from Human Exfoliated Deciduous teeth (SHED) to determine its effect on stemness and bone differentiation. Methods: The SHED were treated using PDT-conjugated ntHIF-1α-ΔODD-TMD, and its effects on STRO-1 expression, cytotoxicity, stemness-related gene expression, and osteogenic differentiation were confirmed. These were also transferred to 5-week-old mice in order to confirm the effects in vivo after recellularization of SHED treated using ntHIF-1α-ΔODD-TMD on decellularized tooth specimens. After 9 weeks, they were sacrificed to confirm the expression of genes related to bone differentiation and angiogenesis. Results: ntHIF-1α-ΔODD-TMD increased the expression levels of STRO-1, HIF-1α-related genes, and stemness-related genes in SHED. Osteogenic differentiation was also increased both in vitro and in vivo. Conclusion: These results suggest that ntHIF-1α-ΔODD-TMD maintains or increases the stemness of SHED and also increases the osteogenic potential. SHED have previously been found to have excellent proliferative but low differentiation capacities compared with other cells. However, properly using ntHIF-1α-ΔODD-TMD increases the osteogenic potential of SHED, indicating the potential of using SHED as a useful source for hard-tissue regeneration.ope

Effect of Noise Cancelling Devices on Dental Handpieces Using Ear Model

This study intended to evaluate noise level of dental handpieces and the effects of noise cancelling devices. An ear model was designed to measure the level of the noise delivered to the inner ear during dental handpiece operation. The level of noise was measured in various conditions using the ear model and the portable noise meter. Noise level was measured again after applying of 4 different noise cancelling devices to the model ear. The noise level of dental handpieces was 82.5 - 84.4 dB. When 4 types of noise canceling devices were applied, the noise level reduced to 67.4 - 73.8 dB. All 4 devices had statistically significant effect in reducing the noise of the handpiece. Considering the intensity and exposure time, noise in dental clinics can cause hearing damage to dentists. For protection from the risk of occupational hearing damages, noise canceling devices can be recommended.ope

Pulp treatment for immature permanent teeth

For dental pulp treatment of immature permanent teeth, direct pulp capping or partial/cervical pulpotomy (apexogenesis) procedures can be used if the dental pulp is vital. MTA (Mineral Trioxide Aggregate) is regarded as the first choice dressing material for these procedures because its higher success rate. It can be also used successfully for devitalized dental pulp which has been treated by calcium hydroxide. This apexification procedure with MTA has a few advantage such as short treatment period and increase of resistance against root fracture. Recently, regenerative endodontic treatment was introduced for devitalized immature pulp. It can maintain pulp vitality and lead to continuing root development although the dental pulp was devitalized.ope

Psychological / recognitive development of children and adolescents

Psychological and cognitive development in child and adolescent periods is key knowledge for understanding children and adolescents’ behavior and inducing their actions. So far, psychoanalytic approaches have been primarily researched by Freud’s analytical tools and Piaget’s analysis on cognitive developments have been mainly employed to explore children and adolescents’ psychological developments. In addition, other various theories have been suggested in order to explain children and adolescents’ psychological developments. However, in reality, it is difficult to integrate diverse theoretical lens to investigate children and adolescents’ psychological developments. Considering this constraint, in clinical dentistry, the conventional theoretical instruments have been still widely employed to guide children and adolescents’ behavior.ope

Identification of Antimicrobial Peptide Hexamers against Oral Pathogens through Rapid Screening of a Synthetic Combinatorial Peptide Library

A positional scanning synthetic peptide combinatorial library (PS-SCL) was screened in order to identify antimicrobial peptides against the cariogenic oral bacteria, Streptococcus mutans. Activity against Streptococcus gordonii and Aggregatibacter actinomycetemcomitans was also examined. The library was comprised of six sub-libraries with the format O(1-6)XXXXX-NH2, where O represents one of 19 amino acids (excluding cysteine) and X represents equimolar mixture of these. Each sub-library was tested for antimicrobial activity against S. mutans and evaluated for antimicrobial activity against S. gordonii and A. actinomycetemcomitans. The effect of peptides was observed using transmission electron microscopy (TEM). Two semi-mixture peptides, RXXXXN-NH2 (pep-1) and WXXXXN-NH2 (pep-2), and one positioned peptide, RRRWRN-NH2 (pep-3), were identified. Pep-1 and pep-2 showed significant antimicrobial activity against Gram positive bacteria (S. mutans and S. gordonii), but not against Gram negative bacteria (A. actinomycetemcomitans). However, pep-3 showed very low antimicrobial activity against all three bacteria. Pep-3 did not form an amphiphilic alpha-helix, which is a required structure for most antimicrobial peptides. Pep-1 and pep-2 were able to disrupt the membrane of S. mutans. Small libraries of biochemically-constrained peptides can be used to generate antimicrobial peptides against S. mutans and other oral microbes. Peptides derived from such libraries may be candidate antimicrobial agents for the treatment of oral microorganisms.ope

The research trends of papers in the Journal of Korean Association for Disability and Oral Health

The purpose of this study was to examine the state of the articles in the Journal of Korean Association for Disability and Oral Health. All the papers in the Journal of Korean Association for Disability and Oral Health of 2005 to 2018 were analyzed. A total of 181 papers were classified according to its type, field of the study, school, the number of authors, references, and written language. According to the type of the paper, 38 (21.0%) were original articles, 12 (6.6%) were review articles, 124 (68.5%) were case reports and 7 (3.9%) were others. In relation to the field, the most were pediatric dentistry. According to author’s school, some schools showed preponderances. As to the number of researchers, the most common number of researchers was four (39 articles, 21.5%), and the number of the articles written by six (37, 20.4%) was similar to that of the articles written by three and five (28, 15.5%). As for the number of references, this number ranged from minimum 0 to maximum 40, and the average was 14.8. Regarding the language of the articles, English was used in 5 articles (2.8%), and Korean was used in 176 articles (97.2%). Thirty-nine (21.5%) papers were done in collaboration with workers of the other field. The efforts of this study was to provide useful information of the journal and the development of research in Special care dentistry.restrictio

Novel 3D Printed Resin Crowns for Primary Molars: In Vitro Study of Fracture Resistance, Biaxial Flexural Strength, and Dynamic Mechanical Analysis

This study evaluated the fracture resistance, biaxial flexural strength (BFS), and dynamic mechanical analysis (DMA) of three-dimensional (3D) printing resins for the esthetic restoration of primary molars. Two 3D printing resins, Graphy (GP) and NextDent (NXT), and a prefabricated zirconia crown, NuSmile (NS), were tested. GP and NXT samples were 3D printed using the workflow recommended by each manufacturer. Data were collected and statistically analyzed. As a result of the fracture resistance test of 0.7-mm-thick 3D printed resin crowns with a thickness similar to that of the NS crown, there was no statistically significant difference among GP (1491.6 ± 394.6 N), NXT (1634.4 ± 289.3 N), and NS (1622.8 ± 323.9 N). The BFS of GP was higher for all thicknesses than that of NXT. Both resins showed high survival probabilities (more than 90%) when subjected to 50 and 150 MPa. Through DMA, the glass transition temperatures of GP and NXT were above 120 °C and the rheological behavior of GP and NXT according to temperature and frequency were analyzed. In conclusion, GP and NXT showed optimum strength to withstand bite forces in children, and 3D printed resin crowns could be an acceptable option for fixed prostheses of primary teeth.ope

Surgical Treatment of Heavy Mandibular Labial Frenum in Pre-school Childwith a History of Syndactyly Suregery : a Case Report

The lower labial frenum attached to the free gingival margin can promote local tension, resulting in tissue ischemia, promoting the development of gingival recession, as well as complicating oral hygiene, resulting in chronic inflammation. In this case, early diagnosis and surgical treatment is recommended. This is the case about surgical treatment of heavy mandibular labial frenum in pre-school child with a history of syndactyly surgery. A 5-year-old girl visited the clinic with the chief complaint of high labial frenum of the mandible. Hyperplastic lower labial frenum was attached to the free gingival margin on the primary mandibular lateral incisor area. After fifteen month follow-up, right after the eruption of the permanent lower right lateral incisor, 6 years old patient received lower labial frenectomy to prevent periodontal diseases in permanent teeth and to reestablish normal anatomic characteristics. After 2 years of follow-ups, there were no marked complications.ope

Dental Complications Associated With Neonatal Intubation in Preterm Infants

This paper describes the potential oral complications in preterm infants who have undergone orotracheal intubation. Neonatal intubation may have adverse effects on the developing deciduous teeth, oral soft tissues, and even the permanent teeth. However, endotracheal intubation may be essential for the survival of premature infants, owing to incomplete tracheal development. Excessive pressure to the oral tissue must be avoided, in cases where orotracheal intubation is inevitable. Moreover, the potential oral complications must be considered when neonatal intubation is performed for the patient's survival, and subsequent reevaluation and proper oral health care are needed.ope

Masticatory Performance and the Related Factors in Korean Children and Adolescents

This study aimed to evaluate the masticatory performance of Korean children and adolescents and to investigate related factors. Early loss of primary molars, degree of occlusion of first molars, occlusal relationship of first molars, and presence of anterior crossbite were considered. From March 2020 to July 2021, 56 children and adolescents between the ages of 6 and 12 were included. The mixing ability index (MAI) was calculated to evaluate the masticatory efficiency of children and adolescents. The subjects were classified into three groups according to the number of early lost primary molars; normal dentition, 1 - 2 teeth lost, more than 3 teeth lost. The number of participants are 23, 18, and 15, respectively. There was no difference in the MAI values between the normal dentition group and the group has 1 - 2 teeth lost. However, when 3 or more primary molars were lost, the MAI value decreased and a significant difference was observed. This study is the first study to evaluate the masticatory performance of children and adolescents in Korea, and it will be helpful to pediatric dentists who evaluate the masticatory performance of children and adolescents and strive to improve the masticatory efficiency of children and adolescents in clinical practice.ope