Biomedical subjects

Hideo Mitani

Publications and source records attributed to Hideo Mitani.

At least 19 recordsLinked to original sources

PubMed2006

Expression of genes for gelatinases and tissue inhibitors of metalloproteinases in periodontal tissues during orthodontic tooth movement.

Orthodontic tooth movement progresses by a combination of periodontal ligament (PDL) tissue and alveolar bone remodeling processes. Besides the remodeling of alveolar bone around the moving teeth, the major extracellular matrix (ECM) components of PDLs, collagens, are degenerated, degraded, and restructured. Matrix metalloproteinases (MMPs) and their specific inhibitors, tissue inhibitors of metalloproteinases (TIMPs), act in a co-ordinated fashion to regulate the remodeling of periodontal tissues. We hypothesized that the expression levels of the genes for MMP-2, MMP-9, and TIMPs 1-3 are increased transiently in the periodontal tissue during orthodontic tooth movement. To test this hypothesis, we employed an animal model of tooth movement using rats, as well as in situ hybridization to analyze the expression levels of Mmp-2, Mmp-9, and Timps 1-3. The expression levels of these genes increased transiently in cells of periodontal tissues, which include cementoblasts, fibroblasts, osteoblasts, and osteoclasts, at the compression side of the moving teeth. The transient increases in gene expression at the tension side were mainly limited to osteoblasts and cementoblasts. In conclusion, the expression levels of Mmp-2, Mmp-9, and Timps 1-3 increase transiently during orthodontic tooth movement at both the tension and compression sides. The expression of these genes is regulated differentially in the periodontal tissue of the tension side and compression side. This altered pattern of gene expression may determine the rate and extent of remodeling of the collagenous ECM in periodontal tissues during orthodontic tooth movement.

Animals↗

PubMed2006

Comparison of age-dependent expression of aggrecan and ADAMTSs in mandibular condylar cartilage, tibial growth plate, and articular cartilage in rats.

A disintegrin and metalloproteinase with thrombospondin motif (adamalysin-thrombospondins, ADAMTS) degrades aggrecan, one of the major extracellular matrix (ECM) components in cartilage. Mandibular condylar cartilage differs from primary cartilage, such as articular and growth plate cartilage, in its metabolism of ECM, proliferation, and differentiation. Mandibular condylar cartilage acts as both articular and growth plate cartilage in the growing period, while it remains as articular cartilage after growth. We hypothesized that functional and ECM differences between condylar and primary cartilages give rise to differences in gene expression patterns and levels of aggrecan and ADAMTS-1, -4, and -5 during growth and aging. We employed in situ hybridization and semiquantitative RT-PCR to identify mRNA expression for these molecules in condylar cartilage and primary cartilages during growth and aging. All of the ADAMTSs presented characteristic, age-dependent expression patterns and levels among the cartilages tested in this study. ADAMTS-5 mainly contributed to ECM metabolism in growth plate and condylar cartilage during growth. ADAMTS-1 and ADAMTS-4 may be involved in ECM turn over in articular cartilage. The results of the present study reveal that ECM metabolism and expression of related proteolytic enzymes in primary and secondary cartilages may be differentially regulated during growth and aging.

ADAM Proteins↗

PubMed2006

Linear and angular filipino cephalometric norms according to age and sex.

OBJECTIVE: To quantify relevant cephalometric parameters for Filipinos according to age and sex. MATERIALS AND METHODS: A total of 157 Filipino subjects (78 males, 79 females) who fulfilled specific criteria were selected from elementary, high school, and college students affiliated with Manila Central University. They were divided into comparison groups (GI, GII, GIII, and GIV) on the basis of chronological age and sex. Lateral cephalograms were taken for all subjects, and the mean and standard deviation for each parameter was recorded and compared among groups. RESULTS: The male group had a longer anterior cranial base (S-N), total facial height (N-Me), longer lower anterior facial height (N-ANS), longer ramus height (Cd-Go), longer lower posterior dentoalveolar height (Mo-Mi'), and total mandibular length (Gn-Cd) than the female group. All these linear measurements were statistically significantly different between males and females in GI, GIII, and GIV. On the other hand, SNB angle showed significant differences (P = .0271) in GIV only. In the lower third of the face, significant opposite tendencies were found in GIV. The female group showed a clockwise rotation, whereas the male counterpart had a counterclockwise rotation of the mandibular plane. The denture pattern of both groups was characterized by a proclination of both lower incisor (Ii to MP) and upper incisor (Is to SN). CONCLUSIONS: Convexity due to dentoalveolar protrusion is the naturally occurring facial profile for Filipinos. The adult females showed steeper mandibular and occlusal plane angles than the male samples.

Adolescent↗

PubMed2006

Morphologic analyses of mandible and upper airway soft tissue by MRI of patients with obstructive sleep apnea hypopnea syndrome.

STUDY OBJECTIVES: To evaluate the morphological features of the mandible and the volume of the upper airway soft tissues in determining the anatomical risk factors for the upper airway in Japanese male patients with obstructive sleep apnea hypopnea syndrome (OSAHS). METHODS: Five morphological parameters of the mandible at the mandibular base plane and three volumetric parameters of the upper airway soft tissue were analyzed using three-dimensional (3D) magnetic resonance imaging software in 31 OSAHS and 20 controls. RESULTS: There were no significant differences between the two groups in mandibular internal width (the distance between the internal right and left gonia [IRG and ILG]) and mandibular bony thickness. However, the patients with OSAHS had a significantly wider mandibular divergence (the angle between the spina mentalis (SM)- IRG line and SM- ILG line), a smaller mandibular internal length (the perpendicular distance from SM to the RG- LG line), and a smaller area than the normal subjects at the mandibular base plane. There were no significant differences in these morphological parameters for the mandible between obese and nonobese OSAHS patients. The volumes of the tongue, soft palate, and lateral pharyngeal walls were not significantly different between the OSAHS and the control groups. CONCLUSIONS: Japanese male OSAHS patients had specific anatomical features in the bottom part of the mandible; however, obesity seemed to be a less significant risk factor. Investigators and clinicians must realize that ethnicity may modify the effects of obesity and abnormal craniofacial anatomy as risk factors for the pathogenesis of OSAHS.

Asian People↗

PubMed2006

Effects of growth hormone on craniofacial growth.

OBJECTIVE: This study determined the effects of growth hormone (GH) therapy on craniofacial growth in idiopathic growth hormone deficiency (GHD). MATERIALS AND METHODS: Fifty-seven patients (33 boys and 24 girls; age range 4.5 to 16.7 years) with GHD were investigated and categorized into three groups according to the duration of GH therapy: the untreated group, the short-term therapy group, and the long-term therapy group. Their lateral cephalometric radiographs were studied, and craniofacial measurements were assessed by age and sex by using matched standard deviation scores. RESULTS: In the untreated group, the anterior cranial base, total facial height, maxillary length, mandibular total length, mandibular body length, and ramus height were smaller than the standard values. In comparison with the untreated group, the long-term therapy group had a significantly larger upper facial height (P < .05), maxillary length (P < .01), and ramus height (P < .01) measurements. CONCLUSIONS: Children who received long-term GH replacement therapy showed increased growth of the craniofacial skeleton, especially the maxilla and ramus. These findings suggest that GH accelerates craniofacial development, which improves occlusion and the facial profile.

Adolescent↗

PubMed2006

Effects of gradually increasing force generated by permanent rare earth magnets for orthodontic tooth movement.

OBJECTIVE: To examine the effects of gradually increasing force generated by permanent rare earth magnets for orthodontic tooth movement by using a novel experimental rat model and computer simulation. MATERIALS AND METHODS: Fifty-five male rats (age 18 weeks) were used as animal experiments. Magnetic (experimental groups) or titanium (control group) cuboids (1.5 x 1.5 x 0.7 mm) were bonded to the lingual surface of the maxillary first molars. The initial distance between materials was 1.0 mm, generating 4.96 gf (experimental group I), or 1.5 mm, generating 2.26 gf (experimental group II). Tooth movement was measured and periodontal structures were observed with microfocus x-ray computed tomography radiographs. RESULTS: The distance between the magnets decreased with time in experimental groups I and II (P < .001), whereas there was no tooth displacement in the control group. Experimental group I showed rapid tooth movement in the initial phase followed by slower tooth movement. Experimental group II showed gradual tooth movement. Horizontal sections on microfocus computed tomgraphy radiographs revealed no pathological changes, such as root resorption, on the compressed side in the experimental groups. CONCLUSIONS: The initial light force and gradual increasing force in magnetic attractive force induced effective tooth movement in rats without inducing any pathological changes.

Analysis of Variance↗

PubMed2006

Orthodontic buccal tooth movement by nickel-free titanium-based shape memory and superelastic alloy wire.

OBJECTIVE: To examine the mechanical properties and the usefulness of titanium-niobium-aluminum (Ti-Nb-Al) wire in orthodontic tooth movement as compared with nickel-titanium (Ni-Ti) wire. MATERIALS AND METHODS: The load deflection of expansion springs was gauged with an original jig. The gradient of the superelastic region was measured during the unloading process. Expansion springs comprising the two types of alloy wires were applied to upper first molars of rats. The distance between the first molars was measured with micrometer calipers. RESULTS: The force magnitude of the Ti-Nb-Al expansion spring was lower than that of the Ni-Ti expansion spring over the entire deflection range. The initial force magnitude and the gradient in the superelastic region of the Ti-Nb-Al expansion springs were half those of the Ni-Ti expansion springs. Thus, Ti-Nb-Al expansion springs generated lighter and more continuous force. Tooth movement in the Ni-Ti group proceeded in a stepwise fashion. On the other hand, tooth movement in the Ti-Nb-Al group showed relatively smooth and continuous progression. At 17 days after insertion of expansion springs, there were no significant differences between the Ti-Nb-Al and Ni-Ti groups in the amount of tooth movement. CONCLUSIONS: These results indicate that Ti-Nb-Al wire has excellent mechanical properties for smooth, continuous tooth movement and suggest that Ti-Nb-Al wire may be used as a practical nickel-free shape memory and superelastic alloy wire for orthodontic treatment as a substitute for Ni-Ti wire.

Animals↗

PubMed2005

Age-related changes in the expression of gelatinase and tissue inhibitor of metalloproteinase genes in mandibular condylar, growth plate, and articular cartilage in rats.

Mandibular condylar cartilage acts as both articular and growth plate cartilage during growth, and then becomes articular cartilage after growth is complete. Cartilaginous extracellular matrix is remodeled continuously via a combination of production, degradation by matrix metalloproteinases (MMPs), and inhibition of MMP activity by tissue inhibitors of metalloproteinases (TIMPs). This study attempted to clarify the age-related changes in the mRNA expression patterns of MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-3 in mandibular condylar cartilage in comparison to tibial growth plate and articular cartilage using an in situ hybridization method in growing and adult rats. MMP-2 and MMP-9 were expressed in a wide range of condylar cartilage cells during growth, and their expression domains became limited to mature chondrocytes in adults. The patterns of TIMP-1 and TIMP-2 expression were similar to those of MMP-2 and MMP-9 during growth, and were maintained until adulthood. TIMP-3 was localized to hypertrophic chondrocytes throughout the growth stage. Therefore, we concluded that TIMP-1 and TIMP-2 were general inhibitors of MMP-2 and MMP-9 in condylar cartilage, while TIMP-3 regulates the collagenolytic degradation of the hypertrophic cartilage matrix.

Aging↗

PubMed2005

Relationship between the direction of mandibular growth and masseter muscle conduction velocity.

INTRODUCTION: The purpose of this study was to investigate the relationship between muscle conduction velocity (MCV) of the masseter muscle and the direction of mandibular growth. METHODS: Longitudinal cephalometric X-rays taken at the prepubertal and postpubertal periods of 16 Japanese girls were analyzed. MCV was calculated from the delay in myoelectric signals obtained by using multiple surface electrode arrays placed along the fibers of the left masseter muscle in the postpubertal period. The direction of mandibular growth was evaluated by superimposition of the lateral cephalometric X-rays at the prepubertal and postpubertal periods. The relationship between MCV and the direction of mandibular growth was analyzed statistically. RESULTS: MCV was significantly correlated with the vertical facial height at the postpubertal period and the direction of mandibular condyle growth. CONCLUSIONS: If the relationship between prepubertal and postpubertal of MCV is clarified, it might be possible to predict the direction of mandibular growth and the vertical facial proportions at the postpubertal period from MCV of the masseter muscle at the prepubertal period.

Action Potentials↗

PubMed2005

Stepwise mechanical stretching inhibits chondrogenesis through cell-matrix adhesion mediated by integrins in embryonic rat limb-bud mesenchymal cells.

Biomechanical forces are major epigenetic factors that determine the form and differentiation of skeletal tissues, and may be transduced through cell adhesion to the intracellular biochemical signaling pathway. To test the hypothesis that stepwise stretching is translated to molecular signals during early chondrogenesis, we developed a culture system to study the proliferation and differentiation of chondrocytes. Rat embryonic day-12 limb buds were microdissected and dissociated into cells, which were then micromass cultured on a silicone membrane and maintained for up to 7 days. Stepwise-increased stretching was applied to the silicone membrane, which exerted shearing stress on the cultures on day 4 after the initiation of chondrogenesis. Under stretched conditions, type II collagen expression was significantly inhibited by 44% on day 1 and by 67% on day 2, and this difference in type II collagen reached 80% after 3 days of culture. Accumulation of type II collagen protein and the size of the chondrogenic nodules had decreased by 50% on day 3. On the other hand, expression of the non-chondrogenic marker fibronectin was significantly upregulated by 1.8-fold on day 3, while the up-regulation of type I collagen was minimal, even by day 3. The downregulation in the expression of chondrogenic markers was completely recovered when cell-extracellular matrix attachment was inhibited by Gly-Arg-Gly-Asp-Ser-Pro-Lys peptide or by the application of blocking antibodies for alpha2, alpha5 or beta1 integrins. We conclude that shearing stress generated by stepwise stretching inhibits chondrogenesis through integrins, and propose that signal transduction from biomechanical stimuli may be mediated by cell-extracellular matrix adhesion.

Alcian Blue↗

PubMed2005

Measurement techniques predicting the effectiveness of an oral appliance for obstructive sleep apnea hypopnea syndrome.

The purpose of this study is to determine the measurement techniques that can predict the effectiveness of an oral appliance (OA) for the treatment of patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Split-night polysomnography and esophageal pressure (Pes) were recorded, and cephalometric tracings were superimposed for 25 OSAHS patients. The patients were classified into good and poor responders according to their apnea hypopnea index (AHI) and mean nadir Pes. When the degree of anterior displacement of the mandible was expressed by vector resolution, it was significantly different between the good and poor responders, whereas there was no significant difference in downward and total mandibular displacement between the two groups. Among the good responders evaluated on the basis of mean nadir Pes, their apnea index, hypopnea index, and mean nadir Pes were significantly different. However, AHI alone cannot predict the effectiveness of OA treatment. Good responders defined by mean nadir Pes also had short soft palates and a wide pharyngeal airway space. Conversely, no significant differences were observed in these parameters when good responders and poor responders are defined by AHI. Logistic regression analysis revealed that the degree of anterior displacement of the mandible showed a significant odds ratio of 1.97. In conclusion, evaluations based on Pes and analyses of the mandibular displacement expressed by vector resolution using a cephalometric superimposition technique can provide important clinical information in evaluation measurements and may be useful for the prediction of the efficacy of OA treatment for patients with OSAHS.

Cephalometry↗

PubMed2004

Distal movement of mandibular molars in adult patients with the skeletal anchorage system.

The skeletal anchorage system (SAS) consists of titanium anchor plates and monocortical screws that are temporarily placed in either the maxilla or the mandible, or in both, as absolute orthodontic anchorage units. Distalization of the molars has been one of the most difficult biomechanical problems in traditional orthodontics, particularly in adults and in the mandible. However, it has now become possible to move molars distally with the SAS to correct anterior crossbites, maxillary dental protrusion, crowding, and dental asymmetries without having to extract premolars. This study evaluated the treatment and posttreatment changes during and after distalization of the mandibular molars. In 15 adult patients (12 women and 3 men), a total of 29 mandibular molars were successfully distalized with SAS. The amount of distalization and relapse and the type of tooth movement were analyzed with cephalometric radiographs and dental casts. The average amount of distalization of the mandibular first molars was 3.5 mm at the crown level and 1.8 mm at the root level. The average amount of relapse was 0.3 mm at both the crown and root apex levels. Of 29 mandibular molars, 9 were tipped back, and the others were translated distally in accordance with the established treatment goals. SAS is a viable modality to move mandibular molars for distally correcting anterior crossbites, malocclusions characterized by mandibular anterior crowding, and dental asymmetries.

Adult↗

PubMed2004

Effects of local administration of clodronate on orthodontic tooth movement and root resorption in rats.

Clodronate, a non-N-containing bisphosphonate, strongly inhibits bone resorption and also has anti-inflammatory properties. The purpose of this study was to examine the effect of the local administration of clodronate on orthodontic tooth movement. Both the right and left upper first molars of 26 7-week-old male Wistar rats were moved buccally with a standardized expansion spring. Clodronate solution was injected into the sub-periosteum area adjacent to the left upper molar every third day during the experimental period. The right first molar served as the control. Local injection of clodronate caused a significant (P < 0.001) and dose-dependent reduction in tooth movement in the rats. The number of osteoclasts on the clodronate-injected side was significantly less (P < 0.01) than on the control side. Local clodronate also inhibited root resorption incident to tooth movement. These results suggest that localized use of clodronate could be a useful therapeutic adjunct in orthodontic treatment.

Alveolar Process↗

PubMed2004

Alveolar ridge notching as a predictor for secondary bone grafting in incomplete alveolar clefts.

OBJECTIVES: To clarify the need for secondary alveolar bone grafting (ABG) in incomplete alveolar clefts identified clinically from its appearance and test the usefulness of alveolar ridge notching in the edentulous stage as a predictor for ABG. DESIGN: A prospective, cross-sectional study comparing three groups of patients at two stages. PATIENTS: Twenty-four patients with unilateral incomplete cleft of primary palate who underwent either no surgery or cheiloplasty only. METHODS: Cleft severity was assessed at two stages. Initially, the appearance of untreated clefts was assessed before cheiloplasty or at 3 months of age in the patient without cheiloplasty and graded by severity into three groups. Later alveolar bone defects were assessed with computed tomography in the primary or mixed dentition period. A decision regarding the requirement for ABG was then made. Finally, the relationship between untreated clefts and the need for ABG was determined. MAIN OUTCOME MEASURES: Nine (75%) of 12 patients with alveolar ridge notching in the edentulous stage were diagnosed as fulfilling the criteria for ABG. RESULTS: The alveolar bone defects correlated with the severity of untreated cleft conditions (Spearman r = 0.65, p =.002). The need for ABG was greater in patients with alveolar ridge notching, compared with those without notching (9/12 versus 0/12, p =.00034). CONCLUSIONS: Most patients with incomplete alveolar clefts clinically identified in the edentulous stage required ABG, and alveolar ridge notching in the edentulous stage could therefore serve as a predictor for ABG.

Alveolar Process↗

PubMed2004

Mandibular widening by distraction osteogenesis in the treatment of a constricted mandible and telescopic bite.

OBJECTIVE: Documentation of the application of mandibular widening by distraction osteogenesis and orthodontics. PATIENTS: Three patients with telescopic bite resulting from an extremely constricted mandible related to hypoglossia-hypodactyly syndrome. INTERVENTION: Mandibular widening by distraction osteogenesis using an extraoral device and subsequent orthodontic treatment. RESULTS: The extremely constricted mandible and telescopic bite were dramatically improved by mandibular widening using distraction osteogenesis and subsequent orthodontics. Two of the three patients had transient complications; one reported temporomandibular joint pain and the other showed evidence of periodontal damage. CONCLUSION: Mandibular widening by distraction osteogenesis is an effective technique for the treatment of telescopic bite resulting from an extremely constricted mandible.

Child↗

PubMed2004

Positional and morphologic changes of the mandibular condyle after mandibular distraction osteogenesis in skeletal class II patients.

AIM: Mandibular distraction osteogenesis has been used to correct the skeletal problems in patients with severe mandibular deficiency. Short-term effects of mandibular distraction osteogenesis on condylar position, condylar morphology, and temporomandibular joint symptoms in patients with severe skeletal Class II malocclusions were evaluated. MATERIAL AND METHODS: The records of 13 patients who had undergone bilateral mandibular lengthening and/or midline mandibular widening were analyzed. Pre- and postoperative positional changes of the mandibular condyle in the glenoid fossa, the axial rotation of the condylar head, and the temporomandibular joint symptoms were evaluated. RESULTS: Most of the condyles were displaced in an upward and backward direction in the glenoid fossa; the amount correlated with the amount of mandibular lengthening. Resorption was observed in 20% of condyles; the incidence of the resorption correlated with incidence of preoperative articular disc displacement and with the amount of condylar displacement. CONCLUSION: Distraction protocols should be performed with particular attention when patients with articular disc displacement require a large amount of distraction.

Adolescent↗

PubMed2003

Asymmetry of the sphenoid bone and its suitability as a reference for analyzing craniofacial asymmetry.

The purposes of this study were to evaluate the asymmetry of the sphenoid bone and to determine its suitability as a reference for analyzing asymmetry of the skull. Thirty-seven dry skulls from India were divided into group A (n = 18), with a right-left length discrepancy of less than 2 mm for both the external acoustic meatus-frontozygomatic suture and external acoustic meatus-subspinale, and group B (n = 19), with a right-left length discrepancy of more than 2 mm for either of these 2 parameters. The skulls were then examined with regard to the percentage of asymmetry of the sphenoid bone, the angles between the cranial base and the facial axis, and the distance between reference surfaces of the sphenoid bone and facial landmarks by 3-dimensional measurement system. The following results were obtained: 1. Asymmetry of the sphenoid bone, while slight, was found in both groups. There were no significant differences between the 2 groups. 2. The cranial base and the facial axis did not form a right angle in group A, and there were no significant differences between the 2 groups. 3. The distances between reference surfaces of the sphenoid bone and the lower landmarks of the facial bone were greater than those of the upper landmarks. 4. The external acoustic meatus was the most suitable reference for analysis of craniofacial asymmetry.

Cephalometry↗

PubMed2003

Predicting mandibular growth potential with cervical vertebral bone age.

This study assessed the possibility of using cervical vertebral bone age determined from cephalometric radiographs to predict mandibular growth potential. The subjects were 2 groups of 20 Japanese girls and young women: one group to derive a formula for predicting mandibular growth potential, the other to compare predicted values with actual values. Each group included subjects in the initial stage of the pubertal growth period and the final stage of growth in early adulthood. A formula for predicting mandibular growth potential that included cervical vertebral bone age and the actual growth of the mandible (condylion-gnathion) was determined with regression analysis. Cervical vertebral bone age, bone age on hand-wrist radiographs, and chronological age were inserted into the formula, and actual values and values predicted with these parameters of the formula for mandibular growth potential were compared. The formula found mandibular growth potential (in millimeters) = -2.76 x cervical vertebral bone age + 38.68. The average error between the value predicted by cervical vertebral bone age and the actual value (1.79 mm) was significantly less (P <.001) than that between the actual value and the value predicted by chronological age (3.48 mm) and approximately the same as that between the actual value and the value predicted by bone age (2.09 mm). The formula derived from this study might be useful for treating orthodontic patients in the growth stage.

Adolescent↗