Orthodontic Management of the Edentulous Space Caused by Surgical Removal of a Large Dentigerous Cyst.

Herein, we report the orthodontic management of a patient with excessive bone and permanent tooth loss after surgical cyst removal. The patient was a 13-year-old Japanese boy who was referred to our department by an oral surgeon. He had an edentulous space with alveolar bone loss and loss of 2 permanent molars in the left mandibular region, following surgical removal of a large dentigerous cyst. We decided to close this space orthodontically. First, we moved the left mandibular second premolar into the edentulous region and autotransplanted the left maxillary lateral incisor in the adjacent distal space. We then performed comprehensive orthodontic treatment to establish stable occlusion. Following treatment, functional and stable occlusion of all permanent teeth was achieved without any spaces. The findings from this case suggest that orthodontic treatment is effective in growing patients with edentulous spaces and alveolar bone loss.

Development of Innovative Contra-angle Handpiece Device with Piston Movement for Root Canal Preparation.

INTRODUCTION: The purpose of this study was to assess the optimal amplitude and weight of the newly developed contra-angle handpiece. The handpiece uses piston movement without using an endodontic motor and enables a safe, quick, and reliable canal preparation. METHODS: A prototype handpiece was designed. Instrumentation was performed on root canal resin blocks by 20 operators in 3 groups: the prototype handpiece with an H file (a stainless steel #25 manual H file, the piston group), a manually standardized technique with a K file (stainless steel #15-25 K files, the manual group), and a nickel-titanium (NiTi) reciprocating file with an endodontic motor (Reciproc Blue R25 [VDW, Munich, Germany], the NiTi group). Transportation of the canal center line and the time required for preparation were measured and statistically analyzed. RESULTS: The optimal condition was an amplitude of 1.35 mm and a weight of 61.0 g. Transportation of the canal center was observed in all groups. A statistically significant difference was found at 2.0-3.0 mm from the apical foramen between the piston or NiTi group and the manual group, but no significant difference was found between the piston and NiTi groups. The least transportation was found in the NiTi and piston groups. The handpiece with a #25 H file demonstrated a good centering ability, similar to the NiTi file, which enabled speedy preparation. The time required for preparation between the piston or NiTi group and the manual group was statistically different. No significant difference was observed between the piston and NiTi groups (P < .05). CONCLUSIONS: We concluded that the newly designed handpiece achieved efficient canal preparation and negotiation. The handpiece could avoid endodontic accidents, including ledge formation, instrument separation, and perforation.

Enamel surface changes caused by hydrogen sulfide.

BACKGROUND: Volatile sulfur compounds (VSCs) produced inside the mouth are a well-known cause of halitosis. Recent studies have suggested that VSCs modify the pathology of periodontitis by encouraging the migration of bacterial toxins associated with increased permeability of gingival epithelia, and enhancing the production of matrix metalloproteinases in gingival connective tissue. Nonetheless, the effects on the enamel of direct exposure to VSCs within the oral cavity remain unclear. In the present study, we observed the effects of VSCs in the form of hydrogen sulfide (H2S) on enamel surfaces and determined their effects on restorations. MATERIALS AND METHODS: Extracted human tooth and bovine tooth samples were divided into the H2S experimental side and the control side. We observed the effects of H2S on enamel surfaces using electron microscopy and conducted a shear test. RESULTS: We found that exposure to H2S obscured the enamel surface's crystal structure. The surface also exhibited coarseness and reticular changes. Shear testing did not reveal any differences in bond strength. CONCLUSIONS: Our findings suggested that H2S occurring inside the mouth causes changes to the crystal structure of the enamel surface that can lead to tooth wear, but that it does not diminish the effects of dental bonding in adhesive restorations.

Detection of a secondary mesio-buccal canal in maxillary first molar: A comparative study.

AIM: The purpose of this study was to clarify detection characteristics of the secondary mesio-buccal canal in maxillary first molars using various methods. MATERIALS AND METHODS: The root canal system of 86 extracted human maxillary first molars was inspected using micro-focus-computed tomography to accurately determine the number of canals. Radiographs or floors of the pulp chamber for all samples were observed for the secondary mesio-buccal canal with computed tomography for dentistry, digital dental radiography, magnifier, or the naked eye. Sensitivity, specificity, positive, and negative predictive values and diagnostic accuracy for these four methods were investigated using the results from the micro-focus-computed tomography inspection as the gold standard. All samples of each method were observed by 10 endodontists. Using these results, the χ(2) test was used to compare and analyze differences between the various conditions (P<0.05). RESULTS: The secondary mesio-buccal canal could be recognized in 60.9% of samples with the micro-focus-computed tomography. No significant difference was seen between efficiencies of the computed tomography for dentistry and the micro-focus-computed tomography. The computed tomography for dentistry was superior to the other three methods. CONCLUSION: Detectability of the secondary mesio-buccal canal in the maxillary first molar was superior using dental-computed tomography compared to digital dental radiography, magnification telescope, and the naked eye.

Growth factors and proliferation of cultured rat gingival cells in response to cyclosporin A.

OBJECTIVE: The prominent side-effect of cyclosporin A, an immunosuppressive drug, in oral tissues is gingival outgrowth, although the exact mechanism underlying this side-effect is unclear. The main purposes of the present study were to determine whether cyclosporin A induced the gingival outgrowth by promoting proliferation of gingival cells and whether growth factors such as transforming growth factor-betas (TGF-betas), fibroblast growth factor-2 (FGF-2), platelet-derived growth factors (PDGFs), and insulin-like growth factors (IGFs) are involved in the possible changes in the proliferation of gingival cells induced by cyclosporin A. METHODS: Cells isolated from rat gingival tissues were cultured with cyclosporin A or IGF-I for 3 days. The effects of cyclosporin A or IGF-I on the proliferation of cultured rat gingival cells were analyzed with a CellTiter 96 proliferation assay kit. The mRNA expression levels for TGF-betas, FGF-2, PDGFs, IGFs, insulin-like growth factor receptors (IGFRs), and insulin-like growth factor binding proteins (IGFBPs) in the rat gingival cells treated with cyclosporin A were measured using competitive reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Cyclosporin A induced 23-25% (p < 0.001) increases in the proliferation of rat gingival cells and approximately 130% (p < 0.05) and 60% (p < 0.05) elevations in the mRNA expression levels for TGF-beta1 and FGF-2, respectively. On the other hand, exogenous IGF-I induced 8-11% (p < 0.05) increases in the proliferation, but cyclosporin A induced 30-80% (p < 0.05-0.01) reductions in the mRNA expression levels for endogenous IGF-I, IGFR1, IGFBP2, IGFBP3, IGFBP5, and IGFBP6. CONCLUSIONS: Cyclosporin A stimulates the proliferation of rat gingival cells. TGF-beta1 and FGF-2 could be involved, but IGFs, IGFRs and IGFBPs could not be directly involved in this cyclosporin A induced-stimulation of the gingival cell proliferation.