An accurate bimaxillary repositioning technique using straight locking miniplates for the mandible-first approach in bimaxillary orthognathic surgery.

Bimaxillary orthognathic surgery has been widely performed to achieve optimal functional and esthetic outcomes in patients with dentofacial deformity. Although Le Fort I osteotomy is generally performed before bilateral sagittal split osteotomy (BSSO) in the surgery, in several situations BSSO should be performed first. However, it is very difficult during bimaxillary orthognathic surgery to maintain an accurate centric relation of the condyle and decide the ideal vertical dimension from the skull base to the mandible. We have previously applied a straight locking miniplate (SLM) technique that permits accurate superior maxillary repositioning without the need for intraoperative measurements in bimaxillary orthognathic surgery. Here we describe the application of this technique for accurate bimaxillary repositioning in a mandible-first approach where the SLMs also serve as a condylar positioning device in bimaxillary orthognathic surgery.

U-shaped Osteotomy Around the Descending Palatine Artery to Prevent Posterior Osseous Interference for Superior/Posterior Repositioning of the Maxilla in Le Fort I Osteotomy.

In maxillary orthognathic surgery, superior repositioning of the maxilla is sometimes difficult, and removal of bony interference, especially around the descending palatine artery (DPA), is very time-consuming in cases of severe maxillary impaction. Posterior repositioning of the maxilla for removal of bony interference between the posterior maxilla and the pterygoid process is also technically difficult. Because the most common site of hemorrhage in Le Fort I osteotomy is the posterior maxilla, this bone removal is a source of frustration for surgeons in DPA injury. When the DPA is injured during bone removal and ligation is performed, aseptic necrosis of the maxilla may occur. Therefore, a simple and safe method for maxillary superior/posterior repositioning is required to remove osseous interference around the DPA. The authors describe here U-shaped osteotomy around the DPA to prevent posterior osseous interference for superior/posterior repositioning of the maxilla in Le Fort I osteotomy.

Vital staining of palatal soft tissue in horseshoe Le Fort I osteotomy for superior repositioning of the maxilla.

In maxillary orthognathic surgery, superior repositioning of the maxilla is sometimes difficult, and removal of the bony interference, especially around the descending palatine artery, is very time-consuming in cases of severe maxillary impaction. A useful method introduced for superior repositioning of the maxilla is horseshoe-shaped osteotomy combined with Le Fort I osteotomy (horseshoe Le Fort I osteotomy). However, injury to the palatal soft tissue during horseshoe-shaped osteotomy may cause aseptic complications of the maxilla. Therefore, a safe method is required to prevent such injury to reduce the risk for aseptic necrosis. We describe here vital staining of palatal soft tissue in horseshoe Le Fort I osteotomy for safer superior repositioning of the maxilla.

Efficient collection and sensitive detection using conducting magnetic microbeads.

Conducting magnetic microbeads were successfully fabricated through a simple procedure that involves coating magnetic microbeads with gold nanoparticles. The formation of a gold layer on the bead enabled the simple introduction of a biotin probe onto the bead, resulting in the binding capacity with streptavidin being 10 times greater than that of commercially available biotin-binding magnetic beads. In addition to the high recovery via magnetic forces and high dispersibility in the sample solution, the accumulation of highly conductive beads on the electrode resulted in the amplification of the electrochemical response of the detection system. This paper reports the efficient collection and highly sensitive detection of target biomolecules using Au-coated magnetic microbeads.

[Utility of the Method for Calculating the Heart to Contralateral Ratio for Cardiac Amyloidosis by Using Ray-summation Images in 99mTc-pyrophosphate Scintigraphy].

PURPOSE: The purpose of this study was to avoid the influence of background activity in the calculation of heart to contralateral ratio (H/CL) in 99mTc-pyrophosphate (PYP) scintigraphy for diagnosis of cardiac amyloidosis. Therefore, we investigated the utility of the H/CL calculation method using ray-summation (ray-sum) images created by multi-planar reconstruction and summing slices of the heart range from single-photon emission computed tomography (SPECT) images. METHODS: The subjects were 33 patients who underwent 99mTc-PYP planar and SPECT/CT at 3 hours after injection. Ray-summation axial (ray-sum axial) and ray-summation coronal (ray-sum coronal) images were created and H/CL was calculated. We compared the differences in sensitivity, specificity, accuracy, and area under the curve (AUC) between the conventional method and our method, and calculated the cutoff values. RESULTS: Comparison of the conventional method and our method showed no significant difference in sensitivity and AUC, while specificity was significantly improved to 97% (p=0.003) of ray-sum axial image and 90% (p=0.01) of ray-sum coronal image, and accuracy was significantly improved to 94% (p=0.02) of ray-sum axial image. CONCLUSION: The H/CL calculation method using ray-sum images had higher diagnostic performance than the conventional method, with optimal cutoff of ray-sum axial images 3.07 and ray-sum coronal images 2.77.

Influence of occlusal stimuli on the microvasculature in rat dental pulp.

OBJECTIVE: To examine the influence of occlusal stimuli on the vasculature in the dental pulp, using an occlusal hypofunction model. MATERIALS AND METHODS: Twenty 7-week-old male Sprague-Dawley rats were divided into two groups. To produce occlusal hypofunction, the appliances were attached to the maxillary and mandibular incisors. Untreated rats served as controls. Serial horizontal paraffin sections of the mandibular first molar were processed by conventional methods. To evaluate the microvasculature in the dental pulp, sections of each specimen were stained with hematoxylin-eosin. RESULTS: In the experimental group, the arterioles in the tooth pulp tissue ran convergently, and their inside diameter was significantly smaller than that of the control group. CONCLUSION: This study suggests that occlusal stimuli influence the periodontal ligament throughout the microvasculature of the dental pulp.

The chemokine receptor type 4 antagonist, AMD3100, interrupts experimental tooth movement in rats.

OBJECTIVE: The aim of this study was to clarify the role of the stromal cell-derived factor-1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4) axis in osteoclast accumulation, and the influence of orthodontic tooth movement (OTM) under mechanical force application to periodontal tissues, by administration of the CXCR4 antagonist AMD3100. DESIGN: The upper right first molar (M1) of rats was moved mesially with a 10-g force titanium-nickel closed coil spring. Rats were treated with phosphate-buffered saline or AMD3100 (5mg/kg), which is a SDF-1 antagonist. After 0, 1, 3, and 7days, alveolar bones in all groups were examined at each time point by micro-computed tomography and histological analysis. RESULTS: Tooth movement was decreased significantly in the AMD3100-treated group at 1, 3, and 7days after beginning OTM. The numbers of tartrate-resistant acid phosphatase-positive multinucleated cells in the periodontal ligament around the maxillary M1 were decreased significantly in the treated as compared to the control group on Days 1 and 3. CONCLUSION: Administration of AMD3100 decreases OTM and osteoclast accumulation in rat molars under orthodontic force application. These findings suggest that the SDF-1/CXCR4 axis plays an important role in alveolar bone metabolism during OTM.

Low-intensity pulsed ultrasound reduces periodontal atrophy in occlusal hypofunctional teeth.

OBJECTIVE: To clarify whether low-intensity pulsed ultrasound (LIPUS) exposure has recovery effects on the hypofunctional periodontal ligament (PDL) and interradicular alveolar bone (IRAB). MATERIALS AND METHODS: Twelve-week-old male Sprague-Dawley rats were divided into three groups (n = 5 each): a normal occlusion (C) group, an occlusal hypofunction (H) group, and an occlusal hypofunction group subjected to LIPUS (HL) treatment. Hypofunctional occlusion of the maxillary first molar (M1) of the H and HL groups was induced by the bite-raising technique. Only the HL group was irradiated with LIPUS for 5 days. The IRAB and PDL of M1 were examined by microcomputed tomography (micro-CT) analysis. To quantify mRNA expression of cytokines involved in PDL proliferation and development, real-time reverse transcription quantitative PCR (qRT-PCR) was performed for twist family bHLH transcription factor 1 (Twist1), periostin, and connective tissue growth factor (CTGF) in the PDL samples. RESULTS: Micro-CT analysis showed that the PDL volume was decreased in the H group compared with that of the C and HL groups. Both bone volume per tissue volume (BV/TV) of IRAB was decreased in the H group compared with that in the C group. LIPUS exposure restored BV/TV in the IRAB of the HL group. qRT-PCR analysis showed that Twist1, periostin, and CTGF mRNA levels were decreased in the H group and increased in the HL group. CONCLUSION: LIPUS exposure reduced the atrophic changes of alveolar bone by inducing the upregulation of periostin and CTGF expression to promote PDL healing after induction of occlusal hypofunction.

Intermittent Hypoxia Influences Alveolar Bone Proper Microstructure via Hypoxia-Inducible Factor and VEGF Expression in Periodontal Ligaments of Growing Rats.

Intermittent hypoxia (IH) recapitulates morphological changes in the maxillofacial bones in children with obstructive sleep apnea (OSA). Recently, we found that IH increased bone mineral density (BMD) in the inter-radicular alveolar bone (reflecting enhanced osteogenesis) in the mandibular first molar (M1) region in the growing rats, but the underlying mechanism remains unknown. In this study, we focused on the hypoxia-inducible factor (HIF) pathway to assess the effect of IH by testing the null hypothesis of no significant differences in the mRNA-expression levels of relevant factors associated with the HIF pathway, between control rats and growing rats with IH. To test the null hypothesis, we investigated how IH enhances mandibular osteogenesis in the alveolar bone proper with respect to HIF-1α and vascular endothelial growth factor (VEGF) in periodontal ligament (PDL) tissues. Seven-week-old male Sprague-Dawley rats were exposed to IH for 3 weeks. The microstructure and BMD in the alveolar bone proper of the distal root of the mandibular M1 were evaluated using micro-computed tomography (micro-CT). Expression of HIF-1α and VEGF mRNA in PDL tissues were measured, whereas osteogenesis was evaluated by measuring mRNA levels for alkaline phosphatase (ALP) and bone morphogenetic protein-2 (BMP-2). The null hypothesis was rejected: we found an increase in the expression of all of these markers after IH exposure. The results provided the first indication that IH enhanced osteogenesis of the mandibular M1 region in association with PDL angiogenesis during growth via HIF-1α in an animal model.

Occlusal hypofunction causes periodontal atrophy and VEGF/VEGFR inhibition in tooth movement.

OBJECTIVE: To examine changes in microvasculature and the expression of vascular endothelial growth factor A (VEGF-A) and VEGF receptor 2 (VEGFR-2) in rat hypofunctional periodontal ligament (PDL) during experimental tooth movement. MATERIALS AND METHODS: Twelve-week-old male Sprague-Dawley rats were divided into normal occlusion and occlusal hypofunction groups. After a 2-week bite-raising period, rat first molar was moved mesially using a 10-gf titanium-nickel alloy closed coil spring in both groups. On days 0, 1, 2, 3, and 7 after tooth movement, histologic changes were examined by micro-computed tomography and immunohistochemistry using CD31, VEGF-A, VEGFR-2, and the terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) method. RESULTS: Hypofunctional molars inclined more than normal molars and did not move notably after day 1 of tooth movement. Blood vessels increased on the tension side of the PDL in normal teeth. Immunoreactivities for VEGF-A and VEGFR-2 in normal teeth were greater than those in hypofunctional teeth during tooth movement. Compressive force rapidly caused apoptosis of the PDL and vascular endothelial cells in hypofunctional teeth, but not in normal teeth. CONCLUSIONS: Occlusal hypofunction induces vascular constriction through a decrease in the expression of VEGF-A and VEGFR-2, and apoptosis of the PDL and vascular cells occurs during tooth movement.

Effect of sympathetic nervous activity on alveolar bone loss induced by occlusal hypofunction in rats.

OBJECTIVE: To elucidate the effect of sympathetic nervous activity on alveolar bone loss induced by occlusal hypofunction in rat molars. DESIGN: Occlusal hypofunction in the molar area was produced by attaching appliances to rat maxillary and mandibular incisors. In addition, a non-selective ß-adrenergic receptor antagonist, propranolol, was administered orally to rats in drinking water to pharmacologically suppress sympathetic nervous activity. After 1 week, alveolar bones in all groups were examined by micro-CT, histomorphometry and histology to determine their trabecular bone phenotypes and histological changes. RESULTS: The marrow spaces of the interradicular alveolar bone of rat mandibular first molars (M1) increased in the occlusal hypofunction group (Group H) but not in the control group (Group C), whilst these decreased in rats in the occlusal hypofunction group that were administered propranolol (Group HB). Bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th) and trabecular number (Tb.N) for interradicular alveolar bone in M1 in Group H were significantly lower than those in Group C, whereas those in Group HB remained as high as those in Group C. The number of TRAP-positive cells in Group H increased compared to that in Group C, whereas it significantly decreased in Group HB. CONCLUSIONS: These results suggest that sympathetic nervous activity may influence the alveolar bone loss induced by occlusal hypofunction.