Prophylactic removal of impacted third molars is a common procedure in dentistry, but the necessity of routine extraction is still controversial. When impacted third molars caused severe apical root resorption of the second molars, orthodontic traction of the third molars after extraction of the damaged second molars could minimize alveolar bone defect and preserve the patient's natural teeth. By well-planned orthodontic treatment, functional occlusion was established avoiding extraction of the impacted teeth and eliminating the possibility of a large bone defect after extraction.
Dentistry ; Molar* ; Molar, Third* ; Orthodontic Space Closure ; Root Resorption ; Tooth ; Tooth, Impacted ; Traction*

Langerhans cell histiocytosis (LCH) is characterized by proliferation of histiocyte-like cells (Langerhans cell histiocytes) with characteristic Birbeck granules, accompanied by other inflammatory cells. Treatments of LCH include surgery, chemotherapy, and radiotherapy. One of the representative forms of chemotherapy is intralesional injection of steroids. Surgical treatment in the form of simple excision, curettage, or even ostectomy can be performed depending on the extent of involvement. Radiotherapy is suggested in case of local recurrence, or a widespread lesion. This article shows the case of repetitively recurrent LCH of a 56-year-old man who had been through surgical excision and had to have marginal mandibulectomy and radiotherapy when the disease recurred. After the first recurrence occurred, lesions involved the extensive part of the mandible causing pathologic fracture, so partial mandibular bone resection was performed from the right molar area to the left molar area followed by the excision of the surrounding infected soft tissues. The resected mandibular bone was reconstructed with a segment of fibula osteomyocutaneous free flap and overdenture prosthesis supported by osseointegrated implants.
Curettage ; Denture, Overlay ; Drug Therapy ; Fibula ; Fractures, Spontaneous ; Free Tissue Flaps ; Histiocytosis, Langerhans-Cell* ; Humans ; Injections, Intralesional ; Mandible ; Middle Aged ; Molar ; Prostheses and Implants ; Radiotherapy ; Recurrence ; Rehabilitation* ; Steroids

PURPOSE: The purpose of the present retrospective cohort study was to investigate the incidence of sinus perforation during endodontic microsurgery and to assess healing of cases with sinus perforation. MATERIALS AND METHODS: Clinical and radiographic records were collected from patients who were treated with endodontic microsurgery in the Microscope Center of the Department of Conservative Dentistry at Yonsei University College of Dentistry, Seoul, Korea, between March 2001 and January 2016. To determine the incidence of sinus perforation, all cases involving maxillary premolar and molar teeth were assessed, and cases with perforation of maxillary sinus during the procedure were counted. To assess the outcome of the endodontic microsurgery, cases with sinus perforation were recalled at least 1 year after surgery. RESULT: Two hundred and forty-nine maxillary premolars and molars were treated with endodontic microsurgery. Among these cases, 16 cases had sinus perforations. Overall incidence of sinus perforation was 6.4%. Thirteen cases with sinus perforation were followed up for 1 year after endodontic microsurgery. Outcome assessment revealed that 2 of 13 cases with sinus perforation had failed. The success rate of endodontic microsurgery with sinus perforation was 84.6%. CONCLUSION: Endodontic surgery performed using microsurgical techniques decreases the risk of sinus perforation. Predictable outcomes of endodontic microsurgeries and healing of sinus membrane can be expected with adequate treatment steps and careful periodic follow-ups in cases with maxillary sinus perforations.
Bicuspid ; Cohort Studies ; Dentistry ; Follow-Up Studies ; Humans ; Incidence ; Korea ; Maxillary Sinus* ; Membranes ; Microsurgery* ; Molar ; Retrospective Studies ; Seoul ; Tooth

PURPOSE: Laser treatment has become a popular method in implant dentistry, and lasers have been used for the decontamination of implant surfaces when treating peri-implantitis. This study was performed to evaluate the effects of an Erbium-doped:Yttrium-Aluminum-Garnet (Er:YAG) laser with different settings on machined (MA), sand-blasted and acid-etched (SA), and resorbable blast media (RBM) titanium surfaces using scanning electron microscopy and confocal microscopy. MATERIALS AND METHODS: Four MA, four SA, and four RBM discs were either irradiated at 40 mJ/20 Hz, 90 mJ/20 Hz, or 40 mJ/25 Hz for 2 minutes. The specimens were evaluated with scanning electron microscopy and confocal microscopy. RESULT: Four MA, four SA, and four RBM discs were either irradiated at 40 mJ/20 Hz, 90 mJ/20 Hz, or 40 mJ/25 Hz for 2 minutes. The specimens were evaluated with scanning electron microscopy and confocal microscopy. Result: The untreated MA surface demonstrated uniform roughness with circumferential machining marks, and depressions were observed after laser treatment. The untreated SA surface demonstrated a rough surface with sharp spikes and deep pits, and the laser produced noticeable changes on the SA titanium surfaces with melting and fusion. The untreated RBM surface demonstrated a rough surface with irregular indentation, and treatment with the laser produced changes on the RBM titanium surfaces. The Er:YAG laser produced significant changes on the roughness parameters, including arithmetic mean height of the surface (Sa) and maximum height of the surface (Sz), of the MA and SA surfaces. However, the Er:YAG laser did not produce notable changes on the roughness parameters, such as Sa and Sz, of the RBM surfaces. CONCLUSION: This study evaluated the effects of an Er:YAG laser on MA, SA, and RBM titanium discs using confocal microscopy and scanning electron microscopy. Treatment with the laser produced significant changes in the roughness of MA and SA surfaces, but the roughness parameters of the RBM discs were not significantly changed. Further research is needed to evaluate the efficiency of the Er:YAG laser in removing the contaminants, adhering bacteria, and the effects of treatment on cellular attachment, proliferation, and differentiation.
Bacteria ; Decontamination ; Dentistry ; Depression ; Freezing ; Lasers, Solid-State ; Methods ; Microscopy, Confocal* ; Microscopy, Electron, Scanning* ; Peri-Implantitis ; Surface Properties ; Titanium*

PURPOSE: Wnt signaling plays an essential role in the dental epithelium and mesenchyme during tooth morphogenesis. Deletion of the Wntless (Wls) gene in odontoblasts appears to reduce canonical Wnt activity, leading to inhibition of odontoblast maturation. However, it remains unclear if autonomous Wnt ligands are necessary for differentiation of dental pulp cells into odontoblast-like cells to induce reparative dentinogenesis, one of well-known feature of pulp repair to form tertiary dentin. MATERIALS AND METHODS: To analyze the autonomous role of Wls for differentiation of dental pulp cells into odontoblast-like cells, we used primary dental pulp cells from unerupted molars of Wls-floxed allele mouse after infection with adenovirus for Cre recombinase expression to knockout the floxed Wls gene or control GFP expression. The differentiation of dental pulp cells into odontoblast-like cells was analyzed by quantitative real-time polymerase chain reaction. RESULT: Proliferation rate was significantly decreased in dental pulp cells with Cre expression for Wls knockout. The expression levels of Osterix (Osx), runt-related transcription factor 2 (Runx2), and nuclear factor I-C (Nfic) were all significantly decreased by 0.3-fold, 0.2-fold, and 0.3-fold respectively in dental pulp cells with Wls knockout. In addition, the expression levels of Bsp, Col1a1, Opn, and Alpl were significantly decreased by 0.7-fold, 0.3-fold, 0.8-fold, and 0.6-fold respectively in dental pulp cells with Wls knockout. CONCLUSION: Wnt ligands produced autonomously are necessary for proper proliferation and odontoblastic differentiation of mouse dental pulp cells toward further tertiary dentinogenesis.
Adenoviridae ; Alleles ; Animals ; Dental Pulp* ; Dentin ; Dentinogenesis ; Epithelium ; Ligands ; Mesoderm ; Mice* ; Molar ; Morphogenesis ; NFI Transcription Factors ; Odontoblasts* ; Real-Time Polymerase Chain Reaction ; Recombinases ; Tooth ; Transcription Factors

PURPOSE: The aim of this study was to evaluate the rat periodontal ligament cell viability under 0℃/2 MPa condition up to one week using in vivo 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide (MTT) assay. MATERIALS AND METHODS: As soon as 110 upper molar teeth of rats were extracted, they were stored in Hartman's solution under 0℃/2 MPa condition for 1, 2, 3, 4, and 7 days each. All specimens were treated with in vivo MTT assay and the value of optical density was measured by ELISA reader. These values were statistically analyzed by one-way ANOVA. RESULT: There was no statistical difference on MTT value between immediate and 1 day storage group. There were statistically significant differences between 1 day and 2 days tsorage, 2 and 3 days storage groups, respectively. Teeth of 3,4, and 7 days storage groups showed significantly lower MTT valuesc ompared with shorter period storage groups. CONCLUSION: When the MTT values were substituted in standard curve, 1 day storage group at 0℃/2 MPa condition showed 68% cell viability when compared with immediate group. It dropped to 13% at 2 days, and to less than 5% at 3 days or more.
Animals ; Cell Survival ; Enzyme-Linked Immunosorbent Assay ; Methods* ; Molar ; Periodontal Ligament* ; Rats* ; Tooth

Even though a conventional metal ceramic restoration is widely in use, its laboratory procedure is still technique-sensitive, complex, and time-consuming. A ceramic-pressed-to-metal restoration (PTM) can be a reliable alternative. However, simplified laboratory procedure for a PTM is still necessary. The article is to propose a technique that reduces time and effort to fabricate a PTM with the aid of computer-aided design, computer-aided manufacturing and selective laser sintering technologies.
Ceramics ; Computer-Aided Design*

Fibrous dysplasia is a bone disorder characterized by progressive replacement of normal bone by fibrous bone tissue. Common involving sites of fibrous dysplasia are the skeletal system including long bones, ribs, craniofacial bones and the pelvis. If maxilla were affected by fibrous dysplasia, antrum is almost always involved. And fibrous dyplasia in maxillary sinus were followed the shape of bone. In our case, the lesion involves antrum but, its shape was different from typical fibrous dysplasia pattern of maxillary sinus. Therefore we report a case of monostotic pediculated fibrous dysplasia in the maxillary sinus with a review of literature.
Bone and Bones ; Maxilla ; Maxillary Sinus* ; Pelvis ; Ribs

PURPOSE: To investigate the influence of crown margin design on the stress distribution and to localize critical sites in maxillary canine under functional loading by using three dimensional finite element analysis. MATERIALS AND METHODS: The bite force of 100 N, 150 N, and 200 N was applied with an angulation of 45degrees to the longitudinal axis of tooth. Six models were restored with IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) with a different margin design. With lingual ledge and various thicknesses, three different core ceramics were designed in each model. RESULT: In the core ceramic, the maximum tensile stresses were found at the labiocervical region. In the veneering ceramic the maximum tensile stresses were found at the area where the force was applied in all models. CONCLUSION: Shoulder and chamfer margin types are acceptable for all-ceramic rehabilitations. A ledge on the core ceramic at cervical region may affect the strength of all-ceramic crowns.
Axis, Cervical Vertebra ; Bite Force ; Ceramics ; Crowns* ; Finite Element Analysis* ; Shoulder ; Tooth

PURPOSE: The purpose of this study was to evaluate the correlation between the clinical symptoms of temporomandibular disorder and findings in the magnetic resonance imaging (MRI). MATERIALS AND METHODS: Clinical data and MRI images were collected from a total of 240 German patients. Clinical symptoms were briefed as joint clicking, crepitus and pain. MRI findings were further defined according to the condyle position, condyle degeneration, disc positon, disc degeneration and the presence of osteophyte/sclerosis/synovitis. Hypermobility was separately recorded. Correlation analysis between parameters was performed. RESULT: Joint clicking had a positive correlation with unilateral disc degeneration, osteophyte, sclerosis and synovitis. Crepitus had a significant correlation with bilateral osteophyte. Pain was not correlated with any MRI findings except hypermobility. CONCLUSION: Selective correlations between the MRI findings and clinical symptoms were elucidated. The results of this study imply that condyle-disc deformities could be advanced without pain, and that joint clicking and crepitus could be clinical symptoms of condyle-disc degeneration.
Congenital Abnormalities ; Humans ; Intervertebral Disc Degeneration ; Joints ; Magnetic Resonance Imaging* ; Osteophyte ; Sclerosis ; Synovitis ; Temporomandibular Joint Disorders ; Temporomandibular Joint*