Sachio Tamaoki

Evaluation of effects of activator treatment on mandibular growth by analyzing components of condylar growth and mandibular rotation

Abstract Purpose The objective of this study is to clarify the effects of activator treatment on mandibular growth in relation to condylar growth and total rotation of the mandible, and to investigate the relationships between the treatment responses and pretreatment facial morphology. Materials and methods Thirty Japanese girls with Class II division 1 malocclusion treated with activator were examined. Mean age at the start of treatment was 9.6 ± 1.6 years. Mean treatment duration was 19 ± 4 months. Lateral cephalograms obtained before and after treatment were used to analyze skeletal changes during treatment. Regional superimposition analysis was performed to evaluate activator effects by decomposing the mandibular growth into condylar growth and mandibular total rotation. Results The changes in intermaxillary relationships were significantly correlated with vertical condylar growth and mandibular total rotation (P < 0.05 and P < 0.01). The changes in the forward displacement of the mandible were significantly correlated with sagittal condylar growth and mandibular total rotation (P < 0.05 and P < 0.01). Vertical condylar growth and mandibular total rotation were significantly correlated with pretreatment mandibular morphology (P < 0.05 and P < 0.01). Conclusion Both the sagittal condylar growth and counterclockwise mandibular total rotation attributed to activator treatment contribute to forward displacement of the mandible. The activator effects are expected greater in patients with flat mandibular plane, small gonial angle, backwardly inclined mandibular ramus and long posterior facial height.

Oxygen saturation and electromyographic changes in masseter muscle during experimental chewing of gum with harder texture

Abstract Objective. The purpose of this study was to clarify the relationship between changes in masseter muscle oxygenation measured by near-infrared spectroscopy (NIRS) and changes in the electromyographic (EMG) power spectrum during experimental chewing of gum with harder texture, to improve the understanding of the use of NIRS in assessing masseter muscle fatigue. Material and methods. Ten female volunteers with normal occlusion were examined. Mean age (standard deviation) was 28.4 (3.8) years. Mean fracture stress of gum was 12.5 × 104 N/m2. Subjects were instructed to chew gum for 60 s (75 strokes) on the voluntary chewing side at a pace of 1.25 strokes/s. Simultaneous recordings of NIRS and EMG signals from masseter muscle were performed during gum chewing. Results. Oxygen saturation levels decreased from the start of chewing, then stabilized with a break point between the two phases. The normalized EMG amplitude increased and the mean frequency of the EMG power spectrum decreased during gum chewing. The timing of break point appearance was related to the timing of a significant decrease in median frequency, but no clear relationships were found between break point appearance and increased EMG amplitude. Conclusions. These results suggest that the break point of the oxygen saturation curve, as obtained from NIRS measurements, could be used as an indicator of masseter muscle fatigue as assessed by a shift in the EMG power spectrum to lower frequencies.

Characteristics of maxillofacial morphology of Angle Class II patients with temporomandibular disorders involving crepitus

Abstract Purpose To clarify the characteristics of maxillofacial morphology of Angle Class II orthodontic patients with temporomandibular disorders (TMD) involving crepitus suggesting osseous changes in the condyle, compared to Class II patients without TMD. Materials and methods Twenty-four Japanese females accompanied by Angle Class II malocclusion with crepitus and 24 females accompanied by Class II malocclusion without TMD were examined. Pretreatment panoramic radiographs were used to measure condylar ratio (condylar height/ramus height). Pretreatment lateral cephalograms were used to analyze skeletal and dental morphology. Angular and linear measurements were compared between groups. Multiple linear regression analysis was used to identify associations of overjet with other cephalometric measurement values in both groups. Results Class II patients with crepitus showed significantly smaller condylar ratio as compared to Class II patients without TMD. Class II patients with crepitus exhibited significantly greater clockwise rotation of the mandible, shorter ramus height, more retruded mandible, less labially inclined upper incisors, and smaller overjet. Overjet of Class II patients with crepitus was significantly associated with inclination of upper incisors and ramus height, whereas that of patients without TMD was significantly associated with inclination of both upper and lower incisors and sagittal intermaxillary relationship. Conclusion Significant smaller condylar ratio of Class II patients with crepitus suggested osseous changes in the condyle. Significant differences existed between morphological maxillofacial characteristics of Class II patients with and without crepitus. Overjet in Class II patients with crepitus correlated significantly with ramus height, attributed to resorbed deterioration and dysfunctional remodeling of the condyle.

Stretch stimuli increase fibulin-5/EMILIN-1 complex on oxytalan fibers in human periodontal ligament cells

Abstract Periodontal ligaments (PDLs) are continuously exposed to various functional forces, such as tooth movement and occlusal loading. Human PDLs comprise elastic system fibers as well as collagen fibers. The elastic system fibers in turn comprise oxytalan, elaunin and elastic fibers, which differ in their relative microfibril and elastin contents. Human PDLs contain oxytalan fibers (pure microfibrils), which are composed mainly of fibrillin-1 (the major component of microfibrils). We have previously reported that bundles of oxytalan fibers in cultured PDL cells coalesce in response to mechanical strain, and that this coalescence is controlled by fibulin-5. However, the relationship between fibulin-5 and other fibrillin-1-binding molecules is unclear. In the present study we investigated whether fibulin-5 and EMILIN-1 (both of which are fibrillin-1-binding molecules) contribute to the formation of oxytalan fibers upon exposure to mechanical strain. We subjected PDL cells to stretching in order to examine the role of fibulin-5 and EMILIN-1 in the formation of oxytalan fibers in cell/matrix layers. We examined the relationship between fibulin-5 and EMILIN-1 in PDL cell cultures using immunofluorescence and immunoprecipitation assay. Immunofluorescence showed that fibulin-5 and EMILIN-1 were colocalized on fibrillin-1-positive oxytalan fibers. Fibulin-5 formed a complex with EMILIN-1, and stretching increased the amount of this complex relative to cells that were not subjected to stretching. These results suggest that the expression of the fibulin-5/EMILIN-1 complex is upregulated in response to tension strain, and may control the formation of oxytalan fibers in PDLs.

Quantitative evaluation of myofibroblast apoptosis during wound healing in rat palate after post-operative administration of basic fibroblast growth factor (bFGF)

Abstract Objective. Excessive wound contraction apparently inhibits maxillary growth; thus, myofibroblast apoptosis needs to be accelerated in mucoperiosteal denudation after palatoplasty. The aim of this study was to evaluate myofibroblast apoptosis during wound healing in mucoperiosteal denudation of rat palates immediately after post-operative administration of basic fibroblast growth factor (bFGF). Materials and methods. A total of 100 male Wistar rats aged 20 days were divided into control, scar, sham and bFGF groups (n = 25 each). In the scar, sham and bFGF groups, mucoperiosteum was removed from the palate and fibrin glue was applied to the exposed bone surface immediately after surgery. In the bFGF group, 10 μL of 2 μg/μL bFGF solution was injected into the operated area beneath the fibrin glue. At 2, 5, 7, 14 and 28 days post-operatively, myofibroblast apoptosis during the wound healing process was investigated by double immunofluorescence staining. The apoptotic area of myofibroblasts was measured using image software. Results. In the bFGF group, at 2 days, apoptosis of myofibroblasts in the lamina propria and submucosa was marked, as compared with the other three groups and apoptosis of myofibroblasts was scarcely seen at 5 days. At 5 and 7 days, the apoptotic area of myofibroblasts in the bFGF group was statistically significantly smaller when compared to the scar and sham groups. Conclusion. The results confirmed that bFGF injection immediately after surgery accelerated apoptosis of myofibroblasts in mucoperiosteal denudation of rats. This may reduce maxillary growth retardation due to excessive wound contraction.

TRPV2 channel inhibitors attenuate fibroblast differentiation and contraction mediated by keratinocyte-derived TGF-β1 in an in vitro wound healing model of rats

BACKGROUND Keratinocytes release several factors that are involved in wound contracture and scar formation. We previously reported that a three-dimensional reconstruction model derived from rat skin represents a good wound healing model. OBJECTIVE We characterized the role of transient receptor potential (TRP) channels in the release of transforming growth factor (TGF)-β1 from keratinocytes and the differentiation of fibroblasts to identify possible promising pharmacological approaches to prevent scar formation and contractures. METHODS The three-dimensional culture model was made from rat keratinocytes seeded on a collagen gel in which dermal fibroblasts had been embedded. RESULTS Among the TRP channel inhibitors tested, the TRPV2 inhibitors SKF96365 and tranilast attenuated most potently keratinocyte-dependent and - independent collagen gel contraction due to TGF-β signaling as well as TGF-β1 release from keratinocytes and α-smooth muscle actin production in myofibroblasts. Besides the low amounts detected in normal dermis, TRPV2 mRNA and protein levels were increased after fibroblasts were embedded in the gel. TRPV2 was also expressed in the epidermis and keratinocyte layers of the model. Both inhibitors and TRPV2 siRNA attenuated the intracellular increase of Ca2+ induced by the TRPV agonist 2-aminoethoxydiphenyl borate in TGF-β1-pretreated fibroblasts. CONCLUSION This is the first study to show that compounds targeting TRPV2 channels ameliorate wound contraction through the inhibition of TGF-β1 release and the differentiation of dermal fibroblasts in a culture model.

Effects of facial mask treatment are attributed to accelerated maxillary growth and inhibited counter-clockwise total rotation of the mandibular corpus: A structural superimposition study

Abstract Purpose To test the hypothesis that facial mask treatment influences maxillary sutural growth, condylar growth, and total rotation of mandibular corpus, using a structural superimposition analysis by Björk et al. Materials and methods Subjects consisted of 28 girls with Angle Class III malocclusion treated with facial mask (FM group). Eleven girls with pseudo-Class III malocclusion (pseudo-III group) were also examined. Pre- and posttreatment lateral cephalograms were analyzed to evaluate skeletal changes. Cephalometric structural superimposition analysis was also performed. Results The FM group exhibited significantly larger forward maxillary growth and negative total rotation of the mandibular corpus as compared to the pseudo-III group. In the FM group, forward maxillary skeletal growth correlated significantly with maxillary counter-clockwise rotation. Negative mandibular total rotation correlated significantly with inhibition of the forward position of the mandible. Conclusion Accelerated maxillary sutural growth and inhibited counter-clockwise total rotation of mandibular corpus growth attributed to facial mask treatment may contribute to improvements in Class III malocclusion. The greater the acceleration of maxillary sutural growth due to facial mask treatment, the greater the increase in maxillary counter-clockwise rotation.

The promotion of nephropathy by Porphyromonas gingivalis lipopolysaccharide via toll-like receptors

BackgroundRecently, we reported that toll-like receptor (TLR)2 and TLR4 localized on the glomerular endothelium in the glomeruli of streptozotocin (STZ)-induced type 1 diabetic mice and high fat diet feed-induced type 2 diabetic mice, and that periodontal pathogen Porphyromonas gingivalis LPS (Pg-LPS) administration lowered the survival rate of diabetic mice. The present study aims to examine the effect of TLR4 blocking on the suppression of Pg-LPS-induced diabetic nephropathy.MethodsThe survival rate and morphological/biochemical features for streptozotocin-induced diabetic mice with Pg-LPS and TLR4 blocker eritoran administration were investigated by reporter gene assay, urine and blood analysis, immunohistochemistry, and real time-PCR.Results and ConclusionsAll of the diabetic mice administered Pg-LPS were euthanized within the survival period of almost all of the diabetic mice. The blood urea nitrogen and creatinine, expression of TLR2 and TGF-b, and type 1 collagen accumulation, in the diabetic mice increased significantly with the Pg-LPS administration. In spite of the limited TLR4 activation with Pg-LPS, the TLR4 blocker eritoran decreased blood urea nitrogen and creatinine, and raised the survival rate of the Pg-LPS-administered diabetic mice slightly. The high expression levels of TLR2, TGF-b, and type 1 collagen in Pg-LPS-administered diabetic mice decreased with eritoran. Nuclear STAT3 which enhances TLR2 expression was detected in the TLR2-expressing glomeruli of diabetic mice. The TLR2 and STAT3 gene expression increased by the Pg-LPS administration but decreased with eritoran. These may suggest that Pg-LPS-induced diabetic nephropathy is mainly dependent on TLR2 signaling on glomerular endothelial cells, and that TLR4 blocker eritoran may play a role to slow the progress of diabetic nephropathy.

Analysis of dental compensation in cases with mandibular lateral deviation using three-dimensional measurement of gnathostatics models

values were calculated for canine (deciduous canine) cusp, first premolar buccal cusp, second premolar buccal cusp, and first molar mesiobuccal cusp. Moreover, the width was measured between the mandibular and the maxillary palate in the buccal segment and the first molar mesiobuccal cusp, and the improvement and exacerbation groups were compared. Subsequently, the following results were obtained. (1) In the improvement group, the dental arch width increased when the first molars or second premolars made mesial movements after the loss of the deciduous molars. Moreover, in the improvement group, canines, first premolars, second premolars, and first molars for grade 6 children, compared to the exacerbation group, moved significantly to the buccal side. With regard to canines and first premolars, significant distal movement was observed. (2) At grade 6, the arch width was significantly wider compared to children in the exacerbation group. Especially, the width between the first molars was significantly wider in the improvement group in grade 3 than in the exacerbation group. (3) No significant differences were observed between the improvement and exacerbation groups in a leeway space amount, timing of the loss of the deciduous canines and the first primary molars, as well as the eruption timing of the canines, the first premolars, and the second premolars. From the findings, we conclude it is apparent that the crowding of the mandibular incisal region shows improvement. The reasons for this improvement are twofold: (1) an increase in the distal movement of the canines and first premolars; (2) an increase in the dentition width of the buccal segment and first molar in the exchange timing.

Assessment of masseter muscle oxygenation during mastication by near-infrared spectroscopy

The purpose of this study was to investigate the effects of gum chewing intensity on masseter muscle oxygenation and blood flow using near-infrared spectroscopy. Subjects comprised 15 adult men with normal occlusion. Two types of gum with different hardnesses were used as test foods. Chewing included four patterns: S1, chewing commercially available gum (soft gum) once per second; S2, chewing soft gum twice per second; H1, chewing a harder training gum (hard gum) once per second; and H2, chewing hard gum twice per second. Chewing was performed by each subject using the habitual chewing side, and the time of the appearance of a break point and 1/2 recovery time were calculated. In S2, H1, and H2, oxygen desaturation was found while the gum was being chewed, and the appearance of a break point at which oxygen saturation later became almost constant was also observed. In H2, with the largest exercise load, a break point appeared significantly earlier than in S2 and H1. These results suggest that masseter muscle oxygenation is influenced by gum chewing intensity. doi: 10.1016/j.odw.2009.12.002 1344-0241/