Biomedical subjects

Masaru Yamaguchi

Publications and source records attributed to Masaru Yamaguchi.

11 recordsLinked to original sources

PubMed2006

Low-energy irradiation stimulates formation of osteoclast-like cells via RANK expression in vitro.

Low-energy laser irradiation (Ga-Al-As semiconductor laser, output 50 mW) was applied to rat osteoclast precursor cells for 1, 3, 6, or 10 min at 24-h intervals during the culture period. The number of tartrate-resistant acid phosphatase positive multinucleate cells was increased by approximately 1.3-fold in the 3- and 6-min irradiation groups. Further, osteoclasts appeared on day 2 in the laser irradiation groups but not until day 3 in the control groups. In immunohistochemical staining for receptor activator of NF-kappaB (RANK), the laser irradiation groups showed significantly greater amounts of staining in comparison with the control group on days 2 and 3. Reverse transcription-polymerase chain reaction results also showed that the expressions of RANK were upregulated. In the pit formation assay, resorption pits were significantly more abundant in the laser irradiation groups than in the controls. The present results suggest that low-energy laser irradiation facilitates differentiation and activation of osteoclasts via RANK expression.

Animals↗

PubMed2005

Relationship between substance P and interleukin-1beta in gingival crevicular fluid during orthodontic tooth movement in adults.

Metabolism by peptidases plays an important role in modulating the levels of biologically-active neuropeptides, while that of substance P (SP), a component of gingival crevicular fluid (GCF), may potentiate the inflammatory process in orthodontic tooth movement. The aim of this study was two-fold: (1) to investigate GCF levels of SP and interleukin-1beta (IL-1beta) during human orthodontic tooth movement, and (2) to determine the correlation coefficients between SP and IL-1beta levels in the GCF. The subjects were 3 males, with a mean age of 21.3 +/- 2.8 years old, and 6 females, with a mean age of 23.1 +/- 2.4 years, undergoing orthodontic movement of a single tooth, with the contralateral tooth used as the control. GCF was sampled at the control and treatment (compression) sites before and 1, 4, 8, 24, 72, 120, and 168 hours after initiation of orthodontic treatment. Prevention of plaque-induced inflammation allowed assessment of the dynamics of mechanically stimulated SP and IL-1beta levels in the GCF, which were determined using enzyme-linked immunosorbent assay (ELISA) kits. GCF levels of SP and IL-1beta for the treated teeth were significantly higher (P < 0.001) than for the corresponding control teeth from 8 to 72 hours, and peaked at 24 hours. These results show that the amounts of SP and IL-1beta in GCF increase with orthodontic tooth movement, and indicate that such increases may be involved in inflammation in response to mechanical stress.

Adult↗

PubMed2005

Relationship between masticatory function and internal structure of the mandible based on computed tomography findings.

INTRODUCTION: The purposes of this study were to investigate bone mineral density as a part of bone construction in human skulls and to examine the relationship between dentofacial morphology and masticatory function by using computed tomography (CT) findings. Changes in bone mineral density in the mandible because of loss of masticatory function were tested in rats by experimentally producing an environment that inhibited mastication by the molars. METHODS: Data for the human study were obtained from 27 modern male Japanese skulls (mean age, 28 years) from the University of Tokyo. Cortical bone thickness (CBT) and CT value (CV) were measured by each CT scan of the first and molars. For the animal study, a metal cap was inserted between the maxillary and mandibular incisors to prevent the molars from biting in 6-week-old male Wistar rats. The rats were killed after 2, 4, or 6 weeks, and bone mineral density was measured in cancellous and cortical bone equivalent to the first molar region by using peripheral quantitative computed tomography. RESULTS: In the human skull study, significant negative correlations were observed between CV in the regions of the buccal side of the second molar and the angle between the Frankfort horizontal and mandibular planes. Significant negative correlations were also observed between the gonial angle and CV in the buccal and basal sides. In the animal study, cancellous bone mineral density began to decline 4 weeks after the start of the experiment in the masticatory hypofunction group compared with the control group. By week 6, cancellous bone density had declined by 11.6% on the buccal side, 16.7% on the lingual side, 12.3% at the bifurcation of the root, and 38.1% at the root apex. Cortical bone density declined by 8% to 12% on the lingual side. CONCLUSIONS: The results support our hypothesis that a functional adaptive response by the mandible to mechanical stress resulting from mastication occurs not only in the muscle insertion area, but also in mandibular alveolar bone in the molar region.

Adaptation, Physiological↗

PubMed2005

Levels of t-PA and PAI-2 in gingival crevicular fluid during orthodontic tooth movement in adults.

BACKGROUND: The regulation of plasminogen activation is a key element in controlling proteolytic events in the extracellular matrix. OBJECTIVE: The aim of this study was to investigate gingival crevicular fluid (GCF) levels of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI -2) during orthodontic tooth movement in adults. METHODS: Five male subjects (Mean age: 22.5 +/- 2.8 years) and five female subjects (Mean age: 23.4 +/- 3.9 years) were used. Each subject had one upper canine retracted into an extraction space. The contralateral and opposing canines, which were not moved, served as controls. GCF was collected at the distal cervical margins of the experimental and control teeth 0, 1, 24, and 168 hours after a retracting force was placed. GCF levels of t-PA and PAI-2 were determined by commercially available ELISA kits. RESULTS: After 24 hours of tooth movement the levels of t-PA and PAI-2 in the GCF were significantly higher from the experimental canines compared with the control teeth. There were no significant experimental-control differences at 0, 1, and 168 hours. There were no differences in the total protein levels up to 168 hours after orthodontic tooth movement. CONCLUSIONS: These results indicate that the amounts of t-PA and PAI-2 in the GCF increase with orthodontic tooth movement, and suggest that such increases may be involved in extracellular matrix degradation in response to mechanical stress. Failure to detect elevated levels of t-PA and PAI-2 at 168 hours was attributed to decay of the force retracting the canines.

Adult↗

PubMed2004

Cathepsins B and L increased during response of periodontal ligament cells to mechanical stress in vitro.

Cathepsin is a typical and well-characterized lysosomal cysteine protease that, under pathological conditions, is involved in tissue destruction. A recent immunocytochemical study demonstrated that cathepsins B (CAB) and L (CAL) were localized in the periodontal ligament (PDL) of the rat molar, and they were expressed in compressed sites during experimental tooth movement. Further, we demonstrated previously that the levels of CAB and CAL in gingival crevicular fluid increased during orthodontic tooth movement. Therefore, CAB and CAL may play important roles in the process of collagen degradation during orthodontic tooth movement, and our in vitro study examined the secretion of CAB and CAL in PDL cells following mechanical stress. PDL cells were subjected to 0.5, 1.0, 2.0, or 3.0 g/cm2 of compression force or an increase in surface area by tension force of 0.28%, 0.95%, 1.72%, or 2.50% for 24 hr. For detection of CAB and CAL in conditioned medium, commercially available ELISA kits were used. We found compression and tension significantly increased the secretions of both CAB and CAL in PDL cells, which were exhibited in a time- and force magnitude-dependent manner. The compression-stimulated secretion of CAB was increased approximately 3-fold and that of CAL 4-fold, as compared with the control. Further, tension-stimulated secretion of CAB was increased by 1.5-fold and that of CAL 2-fold compared with the control. When analyzed using a semiquantitative polymerase chain reaction assay, CAB and CAL mRNA were increased in response to both compression and tension forces. These findings demonstrated that mechanical stress (compression and tension forces) causes an increase in secretion of CAB and CAL in PDL cells in vitro.

Adolescent↗

PubMed2004

Prediction and causes of open gingival embrasure spaces between the mandibular central incisors following orthodontic treatment.

BACKGROUND: An open gingival embrasure space (OGES) between the mandibular incisors, also known as a "black triangle" (BT), can be an undesirable outcome of adult orthodontic treatment. OBJECTIVES: The purpose of this study was to determine the parameters that contributed most to the occurrence of an OGES between the mandibular central incisors, the area with the highest incidence of BT in the lower arch following orthodontic treatment. METHODS: A stepwise regression model was used to identify the variables (age, crowding, treatment duration, alveolar bone height, and six variables describing crown morphology) related independently to OGES score. Intra-oral photographs taken before and after orthodontic treatment, study models and intra-oral radiographs of 60 patients were used. Embrasures between the mandibular central incisors were measured and classified into three types: papilla filling, pinpoint, and BT. RESULTS: Age at the first consultation, length of active treatment and maximum crown width were larger in the BT group than in the normal group. In contrast, incisal edge - centre of the contact point, upper contact point - lower contact point, mesial CEJ - distal CEJ, and mesial CEJ - distal CEJ / maximum crown width were smaller in the BT group than in the normal group. Variation in OGES score was explained by the independent contributions of age at the first consultation, duration of active treatment, maximum crown width, and mesial CEJ - distal CEJ width. The multiple regression coefficient was 0.98, and the regression coefficient square was 96 per cent. CONCLUSION: We conclude that age at the first consultation, duration of active treatment, and crown morphology are involved in OGES manifestation. We suggest also that BT occurrence may be predictable prior to treatment.

Adolescent↗

PubMed2003

The level of cathepsin B in gingival crevicular fluid during human orthodontic tooth movement.

This investigation examined gingival crevicular fluid (GCF) levels of lysosomal cystein protease, cathepsin B (CAB), during human orthodontic tooth movement. The study included 10 patients (five males, mean age 22.5 +/- 2.8 years and five females, mean age 23.4 +/- 3.9 years), each having one tooth undergoing orthodontic movement, while the contralateral and antagonist teeth were used as the controls. The GCF was sampled at the control and treatment (compression) sites before activation and at 1, 24, and 168 hours. Prevention of plaque-induced inflammation allowed this study to focus on the dynamics of mechanically stimulated CAB levels in GCF. The CAB levels in GCF were determined by fluorospectrometry, using Z-Arg-Arg-MCA as the substrate and by Western blotting analysis. The GCF levels of CAB for the treated teeth were significantly (P< 0.001) higher than those of the control teeth at 24 hours. At the control sites, CAB levels at 24 hours did not change significantly with time. At the experimental site where orthodontic forces were applied, Western blot analysis demonstrated that the molecular forms were 29 kDa mature enzymes. These results indicate that the amount of CAB in GCF is increased by orthodontic tooth movement. This increased CAB may be involved in extracellular matrix degradation in response to mechanical stress.

Adult↗

PubMed2003

Some factors associated with open gingival embrasures following orthodontic treatment.

Open gingival embrasures or "black triangles" can be an undesirable outcome of adult orthodontic treatment. The aims of the present study were to determine the prevalence of open gingival embrasures in a group of orthodontic patients, and to determine if open gingival embrasures were related to: age at the start of treatment, the severity of pretreatment crowding of the mandibular incisors, the duration of treatment or changes in alveolar bone height. The subjects were 80 orthodontic patients (33 males, 47 females) between 15 and 31 years of age. Open gingival embrasures were found in 43.7 per cent of all subjects, while in subjects over 20 years of age the prevalence was 66.7 per cent. In relation to the amount of crowding 42.8 per cent of the subjects with less than 4 mm crowding had open gingival embrasures, 41.2 per cent of those with between 4 and 8 mm crowding had open gingival embrasures, and 50 per cent of those with more than 8 mm crowding had open gingival embrasures. The groups were not significantly different. Approximately 42 per cent of the subjects in the shorter treatment group had open gingival embrasures, and 44.4 per cent of those whose treatment took longer than 3 years had open gingival embrasures. This difference was not statistically significant. Cephalometric measurements of mandibular alveolar bone height indicate that open gingival embrasures were more likely to be due to resorption of the alveolar crest rather than extrusion of the mandibular incisors. In conclusion, open gingival embrasures were more frequently found in patients over 20 years of age than in younger patients, and were associated with resorption of the alveolar crest.

Adolescent↗

PubMed2002

Enhancement of lipopolysaccharide-stimulated cyclooxygenase-2 mRNA expression and prostaglandin E2 production in gingival fibroblasts from individuals with Down syndrome.

It is well known that Down syndrome (DS) is a premature ageing syndrome. Periodontal disease in individuals with DS develops rapidly and extensively in a relatively younger age bracket compared with that in healthy controls. The mechanisms involved in the periodontal inflammatory processes in DS patients are not fully understood. In the present study, the non-inflamed gingival fibroblasts isolated from seven patients with DS (DGF) and seven healthy controls (NDGF) were stimulated with lipopolysaccharide (LPS) derived from Actinobacillus actinomycetemcomitans (A. a.). We measured the level of prostaglandin E2 (PGE2) production by DGF and NDGF by radioimmunoassay, and also measured the mRNA expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) by using the real-time PCR method. We found the higher levels of LPS-stimulated COX-2 mRNA expression and PGE2 production in DGF when compared with those in NDGF. This study may indicate that overexpression of LPS-stimulated COX-2 induced a greater ability of DGF to produce PGE2, and that these phenomena may be responsible for the severer periodontal disease in DS patients.

Adolescent↗

PubMed2002

Laser irradiation inhibition of open gingival embrasure space after orthodontic treatment.

The purpose of this study was to investigate the inhibitory effect of low-energy laser irradiation on an incidence of open gingival embrasure space after orthodontic treatment. The patient was a 20-year, 7-month-old Japanese female with an Angle Class I malocclusion and crowding in the mandible. Treatment consisted of extraction of maxillary and mandibular first premolars and use of the Edgewise technique. A Ga-Al-As diode laser was used to irradiate an area of 0.5 cm2 at the labial and lingual gingival papilla between the canines. The time of exposure was 6 minutes for 3 days, carried out between the relevelling and en masse stages of movement. The total energy corresponding to 6 minutes of exposure varied from 1.90 J/cm2. There was no further evidence of open gingival embrasure space, except at the mandibular central incisor. Further: an improvement in the gingival inflammation caused by a periodontal disease was observed, and periodontal pocket depth was maintained. These results suggest that low-energy laser irradiation may inhibit the incidence of open gingival embrasure space after orthodontic treatment.

Adult↗

PubMedDate not supplied

Inflammation in periodontal tissues in response to mechanical forces.

Orthodontic forces are known to produce mechanical damage and inflammatory reactions in the periodontium and dental pulp, as well as inflammatory mediators, e.g. prostaglandins, interleukin (IL)-1, IL-6, tumor necrosis factor alpha, and receptor activator of nuclear factor kappaB ligand, in the periodontal ligament (PDL) and dental pulp. We have studied the effects of aging on the production of inflammatory mediators in the PDL using in vitro and in vitro methods and found that aging of PDL tissues may be an important factor in the severity of periodontal disease through a higher production of inflammatory mediators in response to mechanical forces. Further, the levels of inflammatory mediators in gingival crevicular fluid, an osmotically mediated inflammatory exudates found in the gingival sulcus, have been shown to be significantly elevated during orthodontic treatment. In order to reduce inflammation, low-level laser therapy has been recently studied in vitro and in vitro by many investigators as a substitute for anti-inflammatory drugs. Clinical and experimental studies have shown that low-level laser irradiation reduces orthodontic post-adjustment inflammation. We believe that orthodontic forces (mechanical forces) may play an important role in periodontal inflammation and that low-level laser therapy may be useful for its inhibition.

Aging↗