Occlusal reconstruction of a patient with ameloblastoma ablation using alveolar distraction osteogenesis: a case report

Background Ameloblastoma is one of the most common benign odontogenic neoplasms. Its surgical excision has the potential to lead to postoperative malocclusion. In this case report, we describe the successful interdisciplinary orthodontic treatment of a patient with ameloblastoma who underwent marginal mandibulectomy. Case presentation A woman of 20-year-old was diagnosed with ameloblastoma, and underwent marginal mandibulectomy when she was 8 years of age. She had an excessive overjet (11.5 mm) and a mild open bite (- 1.5 mm) with a severely resorbed atrophic edentulous ridge in the area around the mandibular left lateral incisor, canine and first premolar. An alveolar bone defect associated with tumor resection was regenerated by vertical distraction osteogenesis (DO). Subsequently, 3 dental implants were placed into the reconstructed mandible. Orthodontic treatment using implant-anchored mechanics provided a proper facial profile with significantly improved occlusal function. The occlusion appeared stable for a 7-year retention period. Conclusions These results suggest that surgically assisted and implant anchored-orthodontic approaches might be effective for the correction of such malocclusions

Orthodontic Treatment of a Patient with Bilateral Congenitally Missing Maxillary Canines: The Effects of First Premolar Substitution on the Functional Outcome

Permanent canines are thought to play a pivotal role in obtaining an ideal occlusion. Dentists occasionally encounter patients who lack canines and are therefore missing a key to harmonious guidance during functional mandibular excursions. This case report describes the substitution of maxillary first premolars for congenitally missing canines in the context of an orthodontic treatment plan. A boy, age 10 years and 11 months, with a chief complaint of crooked teeth was diagnosed with Class II division 2 malocclusion associated with a high mandibular plane angle and deep overbite. A stable occlusion with a satisfactory facial profile and functional excursions without interference were achieved after a comprehensive two-stage orthodontic treatment process. The resulting occlusion and satisfactory facial profile were maintained for 12 months. These results indicate that substituting the first premolars for the canines is an effective option in treating patients with missing canines while maintaining functional goals

Primary cultures of chick osteocytes retain functional gap junctions between osteocytes and between osteocytes and osteoblasts

The inaccessibility of osteocytes due to their embedment in the calcified bone matrix in vivo has precluded direct demonstration that osteocytes use gap junctions as a means of intercellular communication. In this article, we report successfully isolating primary cultures of osteocytes from chick calvaria, and, using anti-connexin 43 immunocytochemistry, demonstrate gap junction distribution to be comparable to that found in vivo. Next, we demonstrate the functionality of the gap junctions by (1) dye coupling studies that showed the spread of microinjected Lucifer Yellow from osteoblast to osteocyte and between adjacent osteocytes and (2) analysis of fluorescence replacement after photobleaching (FRAP), in which photobleaching of cells loaded with a membrane-permeable dye resulted in rapid recovery of fluorescence into the photobleached osteocyte, within 5 min postbleaching. This FRAP effect did not occur when cells were treated with a gap junction blocker (18 alpha-glycyrrhetinic acid), but replacement of fluorescence into the photobleached cell resumed when it was removed. These studies demonstrate that gap junctions are responsible for intercellular communication between adjacent osteocytes and between osteoblasts and osteocytes. This role is consistent with the ability of osteocytes to respond to and transmit signals over long distances while embedded in a calcified matrix. </p

Modification of Dentofacial Growth Associated with Goldenhar Syndrome

The rare developmental defect, Goldenhar syndrome is characterized by complex craniofacial and dentofacial anomalies. Here we describe the successful orthodontic treatment of a 5-year-old Japanese Goldenhar syndrome patient with mild facial asymmetry, right microtia, right-side hearing loss, and tongue-thrusting by a modification of dentofacial growth using a non-surgical orthopedic treatment approach. Improvement of the vertical discrepancies on the affected side and canted occlusal plane as well as mandibular deviation were achieved with a functional orthopaedic approach. Stable and acceptable occlusion were obtained over the 32-month post-retention period. A non-surgical orthodontic treatment approach offers satisfactory facial aesthetic outcomes in Goldenhar syndrome

Intraoral Vertical Ramus Osteotomy Improved the Stomatognathic Function in an Elderly Patient with Mandibular Protrusion:A Case Report

This article reports the successful surgical-orthodontic treatment of an elderly patient with dentofacial deformity and signs and symptoms of temporomandibular disorder (TMD). The patient was a 63-year-old woman with a concave profile due to mandibular protrusion. To correct skeletal deformities, the mandible was posteriorly repositioned by employing intraoral vertical ramus osteotomy (IVRO) following presurgical orthodontic treatment. After active treatment for 31 months, the facial profile was significantly improved and satisfactory occlusion was achieved. In addition, TMD symptoms of clicking sounds on the left side and difficulty in mouth opening were resolved. Regarding the findings of magnetic resonance imaging, anterior disc displacement in the opening phase was improved in the temporomandibular joint on the left side. Furthermore, stomatognathic functions were also improved without any aggravation of age-related problems. In conclusion, surgical repositioning of the mandible using IVRO leads to both morphological and functional improvements even in elderly patients

Role of intracellular Ca2+–based mechanotransduction of human periodontal ligament fibroblasts

Human periodontal ligament (hPDL) fibroblasts are thought to receive mechanical stress (MS) produced by orthodontic tooth movement, thereby regulating alveolar bone remodeling. However, the role of intracellular calcium ([Ca2+]i)‐based mechanotransduction is not fully understood. We explored the MS‐induced [Ca2+]i responses both in isolated hPDL fibroblasts and in intact hPDL tissue and investigated its possible role in alveolar bone remodeling. hPDL fibroblasts were obtained from healthy donors' premolars that had been extracted for orthodontic reasons. The oscillatory [Ca2+]i activity induced by static compressive force was measured by a live‐cell Ca2+ imaging system and evaluated by several feature extraction method. The spatial pattern of cell‐cell communication was investigated by Moran's I , an index of spatial autocorrelation and the gap junction (GJ) inhibitor. The Ca2+‐transporting ionophore A23187 was used to further investigate the role of [Ca2+]i up‐regulation in hPDL cell behavior. hPDL fibroblasts displayed autonomous [Ca2+]i responses. Compressive MS activated this autonomous responsive behavior with an increased percentage of responsive cells both in vitro and ex vivo . The integration, variance, maximum amplitude, waveform length, and index J in the [Ca2+]i responses were also significantly increased, whereas the mean power frequency was attenuated in response to MS. The increased Moran's I after MS indicated that MS might affect the pattern of cell‐cell communication via GJs. Similar to the findings of MS‐mediated regulation, the A23187‐mediated [Ca2+]i uptake resulted in the up‐regulation of receptor activator of NF‐κB ligand (Rankl) and Sost along with increased sclerostin immunoreactivity, suggesting that [Ca2+]i signaling networks may be involved in bone remodeling. In addition, A23187‐treated hPDL fibroblasts also showed the suppression of osteogenic differentiation and mineralization. Our findings suggest that augmented MS‐mediated [Ca2+]i oscillations in hPDL fibroblasts enhance the production and release of bone regulatory signals via Rankl/Osteoprotegerin and the canonical Wnt/β‐catenin pathway as an early process in tooth movement–initiated alveolar bone remodeling.—Ei Hsu Hlaing, E., Ishihara, Y., Wang, Z., Odagaki, N., Kamioka, H. Role of intracellular Ca2+‐based mechanotransduction of human periodontal ligament fibroblasts. FASEB J. 33, 10409–10424 (2019)

Changes in the intra- and peri-cellular sclerostin distribution in lacuno-canalicular system induced by mechanical unloading

Introduction Mechanical stimuli regulate Sclerostin (Scl), a negative regulator of bone formation, expression in osteocytes. However, the detailed Scl distribution in osteocytes in response to mechanical unloading remains unclear. Materials and methods Twelve-week-old male rats were used. The sciatic and femoral nerves on the right side were excised as mechanical unloading treatment. A sham operation was performed on the left side. One week after neurotrauma, the bone density of the femora was evaluated by peripheral quantitative computed tomography, and immunofluorescence was performed in coronal sections of the femoral diaphysis. The mean fluorescence intensity and fluorescent profile of Scl from the marrow to the periosteal side were analyzed to estimate the Scl expression and determine to which side (marrow or periosteal) the Scl prefers to distribute in response to mechanical unloading. The most sensitive region indicated by the immunofluorescence results was further investigated by transmission electron microscopy (TEM) with immunogold staining to show the Scl expression changes in different subcellular structures. Results In femur distal metaphysis, neurotrauma-induced mechanical unloading significantly decreased the bone density, made the distribution of Scl closer to the marrow on the anterior and medial side, and increased the Scl expression only on the lateral side. TEM findings showed that only the expression of Scl in canaliculi was increased by mechanical unloading. Conclusions Our results showed that even short-term mechanical unloading is enough to decrease bone density, and mechanical unloading not only regulated the Scl expression but also changed the Scl distribution in both the osteocyte network and subcellular structures

Loading history changes the morphology and compressive force-induced expression of receptor activator of nuclear factor kappa B ligand/osteoprotegerin in MLO-Y4 osteocytes

Background In this study, we investigated the effect of the mechanical loading history on the expression of receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) in MLO-Y4 osteocyte-like cells. Methods Three hours after MLO-Y4 osteocytes were seeded, a continuous compressive force (CCF) of 31 dynes/cm2 with or without additional CCF (32 dynes/cm2) was loaded onto the osteocytes. After 36 h, the additional CCF (loading history) was removed for a recovery period of 10 h. The expression of RANKL, OPG, RANKL/OPG ratio, cell numbers, viability and morphology were time-dependently examined at 0, 3, 6 and 10 h. Then, the same additional CCF was applied again for 1 h to all osteocytes with or without the gap junction inhibitor to examine the expression of RANKL, OPG, the RANKL/OPG ratio and other genes that essential to characterize the phenotype of MLO-Y4 cells. Fluorescence recovery after photobleaching technique was also applied to test the differences of gap-junctional intercellular communications (GJIC) among MLO-Y4 cells. Results The expression of RANKL and OPG by MLO-Y4 osteocytes without a loading history was dramatically decreased and increased, respectively, in response to the 1-h loading of additional weight. However, the expression of RANKL, OPG and the RANKL/OPG ratio were maintained at the same level as in the control group in the MLO-Y4 osteocytes with a loading history but without gap junction inhibitor treatment. Treatment of loading history significantly changed the capacity of GJIC and protein expression of connexin 43 (Cx43) but not the mRNA expression of Cx43. No significant difference was observed in the cell number or viability between the MLO-Y4 osteocyte-like cells with and without a loading history or among different time checkpoints during the recovery period. The cell morphology showed significant changes and was correlated with the expression of OPG, Gja1 and Dmp1 during the recovery period. Conclusion Our findings indicated that the compressive force-induced changes in the RANKL/OPG expression could be habituated within at least 11 h by 36-h CCF exposure. GJIC and cell morphology may play roles in response to loading history in MLO-Y4 osteocyte-like cells