Hiroshi Kato

Hokkaido University, Sapporo-shi, Hokkaido, Japan

Are you Hiroshi Kato?

Claim your profile

Publications (23)9.58 Total impact

  • Journal of Periodontal Research 06/2006; 27(6):599 - 603. DOI:10.1111/j.1600-0765.1992.tb01742.x
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to evaluate the clinical effects of closed debridement with an ultrasonic furcation tip in degree II furcation involvement of mandibular molars. Fifteen patients with degree II furcation involvement in mandibular first and/ or second molars participated in the study. All patients were given oral hygiene instruction. Plaque score, probing depth, probing attachment level and bleeding on probing were recorded at baseline, 1, 4, 8 and 12 weeks. Following a baseline examination, a single episode of supra- and subgingival debridement was provided using an ultrasonic furcation tip in the test group, and an ultrasonic conventional tip and hand scalers under local anesthesia in the control group. At baseline, the mean horizontal probing depth in the test group was 6.35 mm and in the control group 6.06 mm. These values decreased to 4.88 mm and 5.29 mm respectively after 12 weeks. There were horizontal probing attachment gains of 1.29 mm in the test group and 0.59 mm in the control group after 12 weeks (P < 0.01). The bleeding scores were 1.0 in the test group and 0.88 in control group at baseline. These scores were improved to 0.12 in the test group and 0.59 in the control group after 12 weeks (P < 0.01). The results suggest that ultrasonic debridement with a furcation tip has a significantly better potential in treating degree II furcation involvement of mandibular molars.
    Journal of the International Academy of Periodontology 11/2002; 4(4):138-42.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to compare an ultrasonic furcation tip with an ultrasonic conventional tip and a hand scaler on accessibility to furcation areas of mandibular first and second molars. The study was conducted on 360 artificial molars that were replicated from 30 mandibular first molars and 30 second molars with silicone impression material and resin. The furcation areas of each molar were coated with red nail colour for artificial calculus. The root areas from the cement-enamel junction apically were covered with silicone rubber simulating gingival tissue. Then the models were instrumented on the buccal or lingual aspects by an experienced operator with each of the following instruments: an ultrasonic furcation tip, an ultrasonic conventional tip and a hand scaler. After instrumentation the percentage of the furcation area with residual artificial calculus was assessed using a computerised imaging system. Results showed that when the horizontal pocket depth was less than 2mm, all three instruments showed good accessibility. When the horizontal pocket depth was more than 2mm, the ultrasonic conventional tip and the hand scaler showed less removal of artificial calculus than the ultrasonic furcation tip (P < 0.01). Efficiency of the ultrasonic furcation tip was fairly satisfactory for the horizontal pocket up to the ridge of the furcation roof.
    Journal of the International Academy of Periodontology 11/2002; 4(4):132-7.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to evaluate whether hard tissue might be formed on dentin surfaces applied with recombinant human bone morphogenetic protein-2 (rhBMP-2) in palatal connective tissue. Fifty-eight dentin blocks were prepared from rat roots, demineralized with 24% EDTA (pH 7.0), applied with 0, 50 and 100 microgram/ml rhBMP-2, and labeled as groups 0, 50 and 100. The dentin blocks were then transplanted into palatal connective tissue of rats, and specimens were prepared at two and four weeks after surgery for histologic and histomorphometric examinations. The results showed that the percentage of newly formed hard tissue in relation to the total dentin block surface length in groups 0, 50 and 100 was 0.0%, 2.8% and 4.4% at two weeks, and 0.0%, 1.6% and 12.8% at four weeks, respectively. New hard tissue formation in groups 50 and 100 was significantly promoted as compared to group 0 (p < 0.01). These findings thus indicate that rhBMP-2 application to dentin enhanced new hard tissue formation on dentin surfaces in the connective tissue of the palate.
    Journal of Periodontal Research 06/2002; 37(3):204-9. DOI:10.1034/j.1600-0765.2002.01611.x
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purposes of this study were to develop and verify the a portable nocturnal bruxism monitoring and analysis device equipped with a microcomputer, and to clinically apply the device to know the actual conditions of bruxism patients. EEPROM was installed in the device for the data recording, and after the data collection, the recorded data was entered into a personal computer via serial port. After confirming the accuracy of the device, a total of 30 subjects were enrolled in this study to monitor their bruxism activities for 3 nights. Bruxism self-aware group consisted of 14 subjects, 7 males and 7 females, and unaware group consisted of 16 patients, 8 males and 8 females. Most of the subjects reported that the new device was easy to handle. The average bruxism time per hour and the average bruxism lasting time were 223.8 +/- 112.0 and 3.9 +/- 2.9 s in the self-aware group, and 49.3 +/- 38.3 and 0.8 +/- 0.7 s in the unaware group, respectively. The bruxism self-aware group showed statistically longer average bruxism time per hour and the average bruxism lasting time. It was confirmed that the new bruxism monitoring and analysis device is practical for clinical application to monitor and analyze the electromyographic activities.
    Frontiers of Medical & Biological Engineering 02/2002; 11(4):295-306. DOI:10.1163/156855701321138941
  • [Show abstract] [Hide abstract]
    ABSTRACT: Vertical root fractures lead to advanced periodontal breakdown with deep periodontal pockets and vertical bone defects. The purpose of this study is to evaluate clinically the periodontal healing of root fracture treatment using adhesive resin cement. In 22 patients, 23 teeth with vertical root fractures were treated with 4-META/MMA-TBB resin cement. Eleven fractured roots were bonded through the root canal (group A) and 12 fractured roots were bonded extra-orally and replanted (group B). All teeth were then restored with full cast crowns (n=20) or coping (n=3). Mean probing depth was 6.6 mm at pre-treatment and 4.4 mm 6 months after the treatment in group A, and 7.4 mm and 4.6 mm, respectively, in group B. Bleeding scores were 100% at pre-treatment and 36.4% after 6 months in group A and 91.7% and 8.3%, respectively in group B. Radiographic bone level was 56.8% at pretreatment and 59.1% after 6 months in group A, and 18.8% and 29.2%, respectively, in group B. Two roots of group A and three roots of group B were extracted due to refracture, deterioration of periodontal inflammation, mobility, and luxation. The remaining roots (n=18) presented no discomfort to the patients and there was no deterioration of periodontal conditions over a mean period of 33 months (range 14-74 months) in group A and over a mean period of 22 months (range 6-48 months) in group B. There was no ankylosed teeth nor was any root resorption detected. The results suggested that the treatment of vertical root fracture using 4-META/MMA-TBB resin has good prognostic possibilities.
    Dental Traumatology 09/2001; 17(4):174-9. DOI:10.1034/j.1600-9657.2001.170407.x
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of the study was to evaluate periodontal healing after replantation of intentionally rotated teeth with healthy and denuded root surfaces. Ten teeth with hopeless prognoses because of extensive alveolar bone loss and deep pockets extending to the apexes only on one or two surfaces, but with a healthy periodontal apparatus on the other surfaces, were selected. A mucogingival flap was elevated and the teeth were extracted carefully so as not to damage the healthy remnant of the periodontal membrane remaining on the root surfaces. Thorough extra-oral debridement was performed on the contaminated root surface and the remnant was carefully conserved. Retrofilling was also done to eliminate an endodontic cause of attachment loss. The teeth were horizontally rotated and then replanted so that the healthy root would face the connective tissue at the initially periodontally involved sites, and the root planed surfaces, which had been periodontally involved, would face the surfaces of the alveolar sockets at initially healthy sites. The teeth were splinted with adjacent teeth. Clinical parameters and radiographic examination were performed pre-operatively, and at 3 or 6 months, 1, 2, and 3 years postoperatively. One tooth was extracted 1.5 years postoperatively due to reduced support and the treatment strategy of the patient. The other nine teeth were well maintained without any discomfort for the whole maintenance period of 3 years. In all teeth, areas that previously had no pocketing but were now against denuded root surfaces maintained the previous pocket depth readings. In areas where a deep pocket was present but now had a root surface with healthy periodontium, a distinct decrease of mean pocket depth was observed at the first reexamination 3 months postoperatively. The mean radiographic alveolar bone level increased from 0.3% to 45.3% in 2 years and was thereafter maintained for the entire observation period. Loss of periodontal space and possible root resorption were observed in only one case without other ankylotic symptoms. These results suggest that the healing without ankylosis of an extensive denuded root surface may occur by mechanisms other than the maintenance of a viable periodontal ligament on the root surface.
    Dental Traumatology 07/2001; 17(3):127-33. DOI:10.1034/j.1600-9657.2001.017003127.x
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study aimed to evaluate quantitatively the migrated, attached, and oriented human periodontal ligament cells (HPLC) to periodontally diseased cementum and dentin after demineralization with low and neutral pH etching solution. Human teeth, extracted due to periodontal diseases, were scaled and root planed so that cementum remained on one longitudinal half of the root and dentin was exposed on the other half. Forty root slices of 200 microm thickness, obtained from the mid-third of these roots, were divided into four groups: group 1, demineralized with a saturated solution of citric acid (pH 1.20); group 2, with 24% EDTA (pH 7.04); group 3, with tetracycline HCl 100 mg/ml (pH 2.00); and group 4, only scaled and root planed (control). Root slices were placed over the confluent HPLC in 35 mm culture dishes and incubated. Phase contrast microscopic photographs of attached and oriented refractile HPLC to root surfaces were taken at days 1, 3, and 7. Quantitative analysis of attached and oriented HPLC from these photographs was done using special software. The results showed no significant difference in the attachment and orientation index of HPLC to cementum compared to dentin in any method of demineralization at each time point (P >0.05), although there was a significantly higher cell attachment and orientation index to demineralized dentin with EDTA and citric acid than to non-etched dentin and to all 3 demineralized cementum surfaces compared to non-etched cementum (P<0.05). EDTA and citric acid demineralization may enhance HPLC attachment and orientation to the root surface, and it is not always necessary to remove excessive cementum when the demineralizing procedure is used.
    Journal of Periodontology 08/2000; 71(7):1094-9. DOI:10.1902/jop.2000.71.7.1094
  • Ryuji Sakagami, Hiroshi Kato
    [Show abstract] [Hide abstract]
    ABSTRACT: The purposes of this study were to evaluate the geometric and densitometric reproducibility of a newly developed standardized X-ray system and to examine the radiographic changes after scaling/root planing as shown by this device. The system was comprised of three parts: an acrylic bite piece for the individual patient, an aluminum wedge-equipped holder, and a holder-connecting device. The experiment was performed at 32 sites of premolar and molar areas in 19 patients. Radiographs were retaken 6 weeks after scaling/root planing and the reproducibility and radiographic changes were examined. The vertical and horizontal geometric reproducibility of the system at 32 sites in 19 patients were 1.0% and 1.8%, respectively. Of 351 scaled sites, 39 (11.1%) exhibited bone regeneration, and 6 (1.7%) exhibited bone loss. These results indicate that the newly developed system has high accuracy and clinical usefulness. Early bone remodeling can be observed radiographically after 6 weeks with our standardized X-ray system.
    Oral Radiology 05/2000; 16(1):1-7. DOI:10.1007/BF02490156
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/2000; 42(4):282-297. DOI:10.2329/perio.42.282
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/2000; 42(4):267-281. DOI:10.2329/perio.42.267
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/2000; 42(2):114-121. DOI:10.2329/perio.42.114
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/2000; 42(4):255-266. DOI:10.2329/perio.42.255
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/2000; 42(4):247-254. DOI:10.2329/perio.42.247
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/2000; 42(3):182-191. DOI:10.2329/perio.42.182
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/1999; 41(4):436-449. DOI:10.2329/perio.41.436
  • Tomoomi Odajima, Okito Hongo, Hiroshi Kato
    Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/1999; 41(4):392-408. DOI:10.2329/perio.41.392
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the proliferation and mineralization activity of the human gingival and periodontal ligament cells in relation to the nature of the dentin surface. Three types of bovine dentin blocks were used: 1) Rp group: dentin block was root planed by hand scaler, 2) CA group : dentin block was treated by citric acid pH 1 for 3 mins and 3) Na group : citric acid treated block was further exposed to 10% Na0Cl for 3 mins. Besides this, hydroxyapatite (HA) blocks were taken as 4 th group. Human gingival cells (HGC) and periodontal ligament cells (HPLC) were seeded on the blocks and cultured. Alkaline phosphatase (ALP) activity and protein concentration of the attached cells on blocks were measured at the 1, 3, 5, 7, 10 and 14 days interval. Furthermore, HGC and HPLC were cultured in DMEM and the blocks were kept on the cell sheet after becoming confluent, media was changed to a-MEM supplemented with 100 nM dexamethasone and 10 mM β-glycerophosphate. Mineralized nodules were stained weekly for 3 weeks by von-Kossa method and the area was measured in relation to the margin of blocks.The results of the protein concentration of the HGC was higher than the HPLC in the 4 groups. Among the 4 groups, protein concentration of HPLC increased at a faster rate in CA group and in HGC, protein concentration increased at a slower rate in Na group. HGC expressed very low ALP activity and was significantly lower than the HPLC. HPLC showed the highest activity in relation to CA group, and lowest activity was observed in relation to Na and HA group. Regarding the mineralized nodule; HPLC formed larger area of nodule than HGC. CA group formed the largest area of nodule in HPLC but there was no difference among the 4 groups in the HGC. The results suggest that the nature of the dentin surface could influence the cellular proliferation and mineralization activity of HPLC, and also the proliferation of HGC. As HGC are able to show mineralization activity in this study though it is very low, it can be suggested that HGC have the potentiality to torm calcitied tissue.
    Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/1998; 40(4):411-420. DOI:10.2329/perio.40.4_411
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/1997; 39(4):513-519. DOI:10.2329/perio.39.513
  • Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology) 01/1996; 38(4):522-528. DOI:10.2329/perio.38.522