Kenji Sueishi

Chronic bradykinin treatment alters 1α,25-dihydroxyvitamin D3-induced calcium current modulation in pre-osteoblasts

Bradykinin (BK) is involved in bone resorption in chronic inflammatory diseases. During bone formation, 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) plays an important role in the regulation of Ca2+. In osteoblasts, 1,25(OH)2D3 stimulates transmembrane influx of Ca2+ through voltage-sensitive Ca2+ channels (VSCCs). Voltage sensitive Ca2+ channels serve as crucial mediators of membrane excitability and many Ca2+-dependent functions, including bone growth, regulation of proliferation, enzyme activity and gene expression. The purpose of this study was to investigate the effects of BK and 1,25(OH)2D3 on VSCC currents carried by Ba2+ (IBa). Application of 1,25(OH)2D3 facilitated IBa in a voltage-dependent manner. Pretreatment with SQ22536 (an adenylate cyclase inhibitor) attenuated 1,25(OH)2D3-induced facilitation of IBa. Bradykinin and BK1 receptor agonist [Lys-des-Arg9]-BK also facilitated IBa. After 24 h or 7 days exposure to BK, that is, under chronic inflammatory conditions, application of 1,25(OH)2D3 inhibited IBa. In addition, pretreatment with PD98,059, a mitogen-activated protein kinase (MAPK) tyrosine kinase inhibitor, attenuated 1,25(OH)2D3-induced inhibition of IBa. These results indicate that, under normal conditions, 1,25(OH)2D3 acts with adenylate cyclase to facilitate VSCCs, whereas under chronic inflammatory conditions it acts with MAPK to inhibit VSCCs in pre-osteoblasts.

Orthodontic evaluation of eight cases in Beckwith-Wiedemann syndrome

Abstract Beckwith–Wiedemann syndrome is a congenital anomaly. It was reported by Beckwith [Beckwith JB. Macroglossia, omphalocele, adrenal cytomegaly, gigantism and hyperplastic visceromegaly. In: Bersma D, editor. Part II. Malformation syndromes, birth defects: original article series, vol. 5, no. 2. White Plains: The National Foundation—March of Dimes; 1969. p. 188–96] in 1969 and Wiedemann [Wiedemann HR. Familial malformation complex with umbilical Aherina and macroglossia—a “NEW SYNDROME”? Genet Hum 1964;13:223–32] in 1964, and is characterized by the triad of exomphalos, macroglossia, and gigantism and hypoglycemia in newborns. This syndrome is, therefore, also known as EMG syndrome [Niikawa N, Ishikiriyama S, Takahashi S. The Wiedemann–Beckwith syndrome: pedigree studies on five families with evidence for autosomal dominant inheritance with variable expressivity. Am J Med Genet 1986;24:41–55]. Orthodontically, open bite and reversed occlusion are often observed effects of gigantism and macroglossia, although a number of studies have found no common maxillofacial morphological characteristics between these two disorders [Kamogashira K, Itoh T, Nakagawa M. Orthodontic findings in a case of Beckwith–Wiedemann syndrome. J Jpn Orthod Soc 1984;43:564–72; Friede H, Figueroa A. The Beckwith–Wiedemann syndrome: a longitudinal study of the macroglossia and dentofacial complex. J Craniofac Genet Dev Biol Suppl 1985;1:179–87]. We analyzed intraoral findings and lateral cephalograms (cephalometric analysis) obtained at initial consultation in eight patients with Beckwith–Wiedemann syndrome who visited our department. We found the common maxillocraniofacial problem among them to occur solely in the vertical plane (increased gonial angle and open bite). There were no common anteroposterior problems. These differences in the anteroposterior growth of the mandibular body may be closely associated with whether macroglossia, as an external factor, was improved by surgery before eruption of the permanent teeth. In terms of dental problems, the only common finding observed was open bite. The position and function of the tongue and perioral muscles during speech and swallowing may differ among patients, thus resulting in maxillocraniofacial morphology characteristic to each patient.

Influence of experimental hemi-occlusion on mandibular morphology and internal structure in growing rabbit

Abstract We induced experimental hemi-occlusion in growing rabbits to investigate the effect of masticatory laterality on the morphology and internal structure of the mandible. Three-dimensional morphometric data from micro-CT were used to compare changes in mandibular morphology and internal structure. Rabbits in the experimental group were placed under general anesthesia and their left maxillary and mandibular molars cut as far as the cervical area using a rabbit molar cutter. Thereafter, the teeth were cut once every 2 weeks. Rabbits were kept until they were 17 weeks old. For morphometric analysis of the mandible, we measured mandibular body length, mandibular length, mandibular ramus height and gonial angle. To analyze cancellous bone structure, we measured total volume, cancellous bone volume, cancellous bone volume density, trabecular thickness, trabecular number, trabecular separation, and trabecular spacing. Mandibular ramus height and gonial angle were significantly greater on the occlusal side in the experimental group than on the non-occlusal side. Cancellous bone volume density, trabecular thickness and trabecular number were significantly greater on the occlusal side in the experimental group than on the non-occlusal side, whereas trabecular separation and trabecular spacing were significantly lower on the occlusal side. The results indicate that differences in mechanical stimuli during the growth phase resulting from masticatory dysfunction or parafunction affect the morphology and internal structure of the mandible.

Change in dentition over 20 years from third decade of life

Abstract Purpose Previous studies have documented long-term, age-related change in the teeth, dental arches and occlusion. However, very few studies have investigated longitudinal age-related change in the dentition using 3-dimensional (3-D) measurement. The purpose of this study was to clarify age-related change in the dentition using a laser scanner. Materials and methods We used dental casts obtained from the same subjects in their twenties and forties. Subjects were selected based on near-normal occlusion. We investigated age-related variation in the dentition using 3-D measurement. Results Age-related change in the dentition was characterized by a decrease in maxillary and mandibular width, an increase in maxillary length, and a decrease in mandibular length. Measurement of angulation revealed that the maxillary canines and molars were mesially inclined. We observed labial inclination of the maxillary incisors, and lingual inclination of the mandibular incisors, as well as the maxillary and mandibular canines and molars. Overjet, overbite, and the irregularity index all showed an increase, while occlusal vertical dimension showed a decrease. Multiple regression analysis indicated that lingual inclination of the lower central incisors was related to an increase in the irregularity index, and that lingual inclination of the upper canines and decrease in occlusal vertical dimension of the anterior teeth were related to increased overbite. Conclusion The present findings showed that age-related changes in angulation and inclination of each tooth should be taken into account when providing occlusal rehabilitation or post-orthodontic retention.

Dental pulp cells promote the expression of receptor activator of nuclear factor-κB ligand, prostaglandin E2 and substance P in mechanically stressed periodontal ligament cells

OBJECTIVE This study investigated the expression of receptor activator of nuclear factor-κB ligand (RANKL) in periodontal ligament (PDL) cells co-cultured with dental pulp (DP) cells following mechanical stress in vitro. Furthermore, the expression of prostaglandin (PG) E2 and substance P (SP) by the PDL cells and by the DP cells were also examined. DESIGN PDL and DP cells were obtained from 10 rats. The experimental group consisted of PDL cells subjected to centrifugal force as mechanical stress and co-cultured with DP cells. The 3 control groups of PDL cells were: 1) PDL cells without mechanical stress, 2) PDL cells treated with mechanical stress and 3) PDL cells co-cultured with DP cells. The 2 control groups of DP cells were: 1) DP cells without mechanical stress and 2) DP cells co-cultured with PDL cells. In each group, both cells were examined at day 1 and day 3, and mRNA levels of RANKL by PDL cells were analyzed using Real time quantitative Reverse Transcription (RT)-PCR. Furthermore, RANKL expression was observed using Immunofluorescence staining. PGE2 and SP expression levels by PDL cells and DP cells were characterized by ELISA analysis. RESULTS The expression of RANKL by PDL cells under mechanical stress increased by co-culture with DP cells. PGE2 and SP expressions were increased in the group of PDL cells subjected to mechanical stress and co-cultured with DP cells. CONCLUSION DP cells may facilitate the expression of RANKL in PDL cells under mechanical stress via PGE2 and SP.

Stress distribution in the mini-screw and alveolar bone during orthodontic treatment: a finite element study analysis

Objective This study aimed to investigate the reason for high failure rates of mini-screws during orthodontic treatment. We hypothesized that decreasing the length of the mini-screw outside the bone relative to the length inside the bone (outside/inside length ratio) and equalising it to the tooth crown/root ratio would lead to increased stability of the mini-screw against lateral loading when assessed using finite element analysis. Methods We analysed stress distribution of mini-screws in the cortical and trabecular bone and von Mises stress levels when a 2-N force was applied to the head of four mini-screws of 6, 8, 10 and 12 mm in length. The direction of the force was perpendicular to the major axis of the screws. Results Stress levels of screws in cortical bone increased in proportion to the length of mini-screws outside the bone. The length of mini-screws inside the bone did not affect stress levels in the cortical bone. Conclusions The results of this finite element analysis indicate that to stabilize the mini-screw, controlling the screw length outside the bone is more important than controlling the outside/inside length ratio.

Targeted reversion of induced pluripotent stem cells from patients with human cleidocranial dysplasia improves bone regeneration in a rat calvarial bone defect model

BackgroundRunt-related transcription factor 2 (RUNX2) haploinsufficiency causes cleidocranial dysplasia (CCD) which is characterized by supernumerary teeth, short stature, clavicular dysplasia, and osteoporosis. At present, as a therapeutic strategy for osteoporosis, mesenchymal stem cell (MSC) transplantation therapy is performed in addition to drug therapy. However, MSC-based therapy for osteoporosis in CCD patients is difficult due to a reduction in the ability of MSCs to differentiate into osteoblasts resulting from impaired RUNX2 function. Here, we investigated whether induced pluripotent stem cells (iPSCs) properly differentiate into osteoblasts after repairing the RUNX2 mutation in iPSCs derived from CCD patients to establish normal iPSCs, and whether engraftment of osteoblasts derived from properly reverted iPSCs results in better regeneration in immunodeficient rat calvarial bone defect models.MethodsTwo cases of CCD patient-derived induced pluripotent stem cells (CCD-iPSCs) were generated using retroviral vectors (OCT3/4, SOX2, KLF4, and c-MYC) or a Sendai virus SeVdp vector (KOSM302L). Reverted iPSCs were established using programmable nucleases, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-derived RNA-guided endonucleases, to correct mutations in CCD-iPSCs. The mRNA expressions of osteoblast-specific markers were analyzed using quantitative reverse-transcriptase polymerase chain reaction. iPSCs-derived osteoblasts were transplanted into rat calvarial bone defects, and bone regeneration was evaluated using microcomputed tomography analysis and histological analysis.ResultsMutation analysis showed that both contained nonsense mutations: one at the very beginning of exon 1 and the other at the initial position of the nuclear matrix-targeting signal. The osteoblasts derived from CCD-iPSCs (CCD-OBs) expressed low levels of several osteoblast differentiation markers, and transplantation of these osteoblasts into calvarial bone defects created in rats with severe combined immunodeficiency showed poor regeneration. However, reverted iPSCs improved the abnormal osteoblast differentiation which resulted in much better engraftment into the rat calvarial bone defect.ConclusionsTaken together, these results demonstrate that patient-specific iPSC technology can not only provide a useful disease model to elucidate the role of RUNX2 in osteoblastic differentiation but also raises the tantalizing prospect that reverted iPSCs might provide a practical medical treatment for CCD.

Post-treatment Stability in Angle Class III Cases

The purpose of this study was to compare post-treatment stability in Angle Class III cases grouped by treatment modality into extraction, non-extraction, or surgical. Twenty-seven Angle Class III patients (9 men, 18 women) were selected from among the records of qualified retention cases treated at the Department of Orthodontics, Tokyo Dental College. The patients were divided into the following groups: Group 1, extraction (n=10); Group 2, non-extraction (n=9); and Group 3, surgery (n=8). Lateral cephalograms, panoramic X-rays, and study casts were obtained at baseline (T0), after active treatment (T1), and after retention (T2). The ABO Model Grading System (ABO) and Gottliebs Grading Analysis (GGA) were used as indices of occlusion, and the scores at each stage and differences in scores at T1 and T2 (|T1-T2|), defined as post-retention stability, recorded. Littles Irregularity Index (IRI) from the study casts and the ANB from lateral cephalograms at T0, T1, and T2 were also recorded to assess post-treatment stability from a different perspective. The Kruskal-Wallis test was performed for statistical comparisons. Mean ranking according to the ABO and Kruskal-Wallis test at T1, T2, and |T1-T2| was lowest in Group 1 and highest in Group 3, and the mean amount of change in the ABO score after active treatment was also the same. This suggests that post-treatment stability is highest in non-extraction cases and lowest in surgical cases. This result correlated with change in the ANB from T0 to T1. This indicates that amount of change in the ANB affects post-treatment stability and that relapse will tend to be greater in surgical cases. However, the amount of change in IRI after active treatment was highest in Group 2 and lowest in Group 3, suggesting that relapse of the lower incisors is greatest in non-extraction cases.

Hard palate thickness for temporary anchorage devices placement: Differences in sex and ethnicity

Abstract Purpose The purpose of this study is to determine variations in hard palate thickness among sexes and four ethnic groups to identify optimum area for temporary anchorage devices (TADs) placement. Materials and methods Cone-beam computed tomography (CBCT) volume data on 160 patients were selected. Patients belonged to one of four ethnic groups (Asian, African-American, Caucasian or Hispanic; 20 men and 20 women in each group, 16–45 years old). Hard palate thickness from the incisor fossa to the palatal root of the maxillary first molar was determined on each image and compared between sexes and ethnic groups. Results The data revealed that thickness was greatest at the paramedian area in the incisive canal zone (C-zone) and the median area posterior to the incisive foramen. A significant difference in thickness of palate was confirmed between sexes, and was approximately 0.5 mm and 1 mm greater in men at the median and paramedian, respectively. Among ethnic groups, a trend of decreasing thickness was as follows: Caucasian > Hispanic > African-American > Asian. Conclusion The anterior (incisive canal zone) paramedian and posterior median areas of the hard palate were thicker and suggest that these areas are appropriate for TADs placement. Some differences were also observed local to the paramedian in the C-zone among ethnicities. This indicates that sex and ethnicity should be taken into consideration in selecting sites for placement of TADs.

Crown inclination measured by laser scanner

Abstract We developed the computer measurement procedure to measure crown inclination of three-dimensional (3D) dental images scanned by laser scanner to reduce human error. 20 study models with normal occlusion were scanned by laser scanner. Crown inclinations of each tooth of scanned 3D dental images were measured according to Andrews’ method. Results: The mean value measured by our method and that measured by manual procedure in the same sample did not detect significant differences. In the variances of the measurements, the results of measurement by our method were larger than that by manual procedure for almost all teeth. Compared to other data, the results of our procedure tended to show large variances than that of other report with manual method. On the other hand, compared to non-manual procedure, the data and that of variances tended similar. Our procedure could objectively measure inclinations with less prejudice and or human error of examiner. This procedure would be useful in research and in the clinic.