PubMed Health⌕ Search

Biomedical subjects

Junji Kato

Publications and source records attributed to Junji Kato.

At least 19 recordsLinked to original sources
PubMed2007

An experimental pathologic study of gingivectomy using dual-wavelength laser equipment with OPO.

BACKGROUND AND OBJECTIVES: This study was conducted to evaluate how soft tissues respond to treatment by a tunable laser with an optical parametric oscillating (OPO) mechanism capable of simultaneously emitting two wavelengths. MATERIALS AND METHODS: Marginal gingiva of dogs was incised by a prototype laser oscillator. The oscillator was set at two wavelengths known to effectively incise tissue and arrest hemorrhage with minimal invasiveness. Four laser irradiation conditions were set based on different combinations of the 1.67 and 2.94 microm wavelengths. The animals were sacrificed immediately after surgery, 7 days after surgery, and 28 days after surgery for histological examination. RESULTS: When irradiation at 1.67 and 2.94 microm wavelengths was simultaneously applied, the former conferred an observable hemostatic effect and the latter incised the tissue. Wound healing was similar to that in conventional methods and no serious inflammation was observed. CONCLUSION: Simultaneous irradiation at wavelengths of 1.67 and 2.94 microm can be an effective method in soft tissue surgery.

Animals↗
PubMed2006

Ex vivo large-scale generation of human platelets from cord blood CD34+ cells.

In the present investigation, we generated platelets (PLTs) from cord blood (CB) CD34(+) cells using a three-phase culture system. We first cultured 500 CB CD34(+) cells on telomerase gene-transduced human stromal cells (hTERT stroma) in serum-free medium supplemented with stem cell factor (SCF), Flt-3/Flk-2 ligand (FL), and thrombopoietin (TPO) for 14 days. We then transferred the cells to hTERT stroma and cultured for another 14 days with fresh medium containing interleukin-11 (IL-11) in addition to the original cytokine cocktail. Subsequently, we cultured the cells in a liquid culture medium containing SCF, FL, TPO, and IL-11 for another 5 days to recover PLT fractions from the supernatant, which were then gel-filtered to purify the PLTs. The calculated yield of PLTs from 1.0 unit of CB (5 x 10(6) CD34(+) cells) was 1.26 x 10(11) - 1.68 x 10(11) PLTs. These numbers of PLTs are equivalent to 2.5-3.4 units of random donor-derived PLTs or 2/5-6/10 of single-apheresis PLTs. The CB-derived PLTs exhibited features quite similar to those from peripheral blood in morphology, as revealed by electron micrographs, and in function, as revealed by fibrinogen/ADP aggregation, with the appearance of P-selectin and activated glycoprotein IIb-IIIa antigens. Thus, this culture system may be applicable for large-scale generation of PLTs for future clinical use.

Antigens, CD34↗
PubMed2006

A phase I/II study of nedaplatin and 5-fluorouracil with concurrent radiotherapy in patients with esophageal cancer.

PURPOSE: To determine the recommended dose (RD) of cis-diammine-glycolatoplatinum (nedaplatin) when given concurrently with 5-FU and high dose radiation therapy in the treatment of esophageal cancer. The purpose of the phase II trial is to determine efficacy and further define the side effect profile. METHODS: Twenty-six patients with clinical stage I to IVA squamous cell carcinoma of the esophagus were enrolled in a non-surgical treatment comprised of a fixed dose of fluorouracil (400 mg/m2 administered as continuous intravenous infusion on days 1-5 and days 8-12) plus escalating doses of nedaplatin (40 mg/m2 in level 1, 50 mg/m2 in level 2, or 60 mg/m2 in level 3 on days 1 and 8), repeated twice every 3 weeks with concurrent radiotherapy (60 Gy). RESULTS: Between July 1998 and February 2004, a total of 26 patients entered this trial, all of whom were considered evaluable for toxicity assessment. In phase I of the study, 12 patients were treated in sequential cohorts of three to six patients per dose level. The maximum tolerated dose was reached at level 3 with two grade 4 neutropenia and one grade 4 thrombocytopenia. Thus, the recommended dosing schedule is level 2. Of the 20 patients treated at the RD level 2, including 6 patients of the RD phase I portion, 8 out of 20 patients (40%) had grade 3-4 neutropenia, 5 patients (25.0%) had grade 3-4 thrombocytopenia, 4 patients (20.0%) had grade 3 anemia and 4 patients (20.0%) had grade 3-4 esophagitis. Other toxicities were relatively mild and usually of grade 2 or less. Objective responses were noted in the 26 patients (overall response rate, 88.5%) including 11 (42.3%) complete remissions. The 1- and 3-year survival rates were 65.1 and 37.2%, respectively, with a median survival time of 21.2 months. CONCLUSIONS: The combination of nedaplatin and 5-FU with radiation is a feasible regimen that shows promising antitumor activity with an acceptable safety profile in patients with esophageal cancer.

Aged↗
PubMed2006

Ex vivo expansion of G-CSF-mobilized peripheral blood CD133+ progenitor cells on coculture with human stromal cells.

OBJECTIVE: The pentaspan molecule CD133 has been shown to be a marker of more primitive hematopoietic progenitors in mobilized peripheral blood (PB). Our objective was to assess the efficacy of PB CD133(+) cells in our coculture system using human telomerized stromal (HTS) cells. METHODS: Five thousand PB CD133(+) cells or conventional cord blood (CB) CD34(+) cells were expanded with or without HTS cells in the presence or absence of stem cell factor, thrombopoietin, and Flk-2/Flt-3 ligand. RESULTS: The coculture was significantly superior in expanding PB clonogenic cells as compared with the stroma-free culture (CFU-C, 2 +/- 0 vs 111 +/- 15-fold of initial cell number, p < 0.01), and the fold increase of PB clonogenic cells was comparable to that for CB cells after two weeks of coculture (BFU-E, 54 +/- 3 vs 56 +/- 4-fold; CFU-GM, 156 +/- 26 vs 83 +/- 9-fold; CFU-Mix, 30 +/- 11 vs 80 +/- 36-fold). However, proliferation of CFU-Mk from PB on coculture with HTS cells was modest as compared with stroma-free culture. Concomitantly, multiple hematopoietic cells transmigrated below the stromal layer and formed cobblestone areas (CAs). The production of hematopoietic progenitor cells from CAs after coculture with PB was significantly lower than that seen in cells cocultured with CB for four weeks (CFU-Mix, 0 +/- 0 vs 9 +/- 5-fold on day 28, p < 0.01), although a similar number of CAs derived from PB and CB were observed. CONCLUSION: PB CD133(+) cells proliferated efficiently above the stromal layer, while the characteristics of PB CD133(+) cells underneath the human stromal layer were likely to be maintained, even after long-term hematopoietic-stromal interaction.

AC133 Antigen↗
PubMed2006

Resin bonding to dentin irradiated by high repetition rate Er:YAG laser.

OBJECTIVE: This study evaluated the influence of laser irradiation with a high pulse repetition rate on dentin bonding. BACKGROUND DATA: Although resin bonding to erbium:yttrium-aluminium-garnet (Er:YAG) laserirradiated dentin has frequently been investigated, the effects of a high pulse repetition rate have not yet been sufficiently investigated. METHODS: Four groups treated under different laser conditions were evaluated in this study: 100 mJ/pulse-10 pulses per second [pps], 50 mJ/pulse-20 pps, 33 mJ/pulse-30 pps, and the unlased condition as a control. The total energy used to irradiate each group was adjusted to 1.0 W. After bovine dentin specimens were irradiated by an Er:YAG laser, acid conditioners (10% citric acid/3% ferric chloride) were applied to the lased surface. Thereafter, a PMMA rod was bonded to the lased dentin using 4- META/MMA-TBB resin, and mini-dumbbell-shaped specimens were prepared. These specimens were then tested under tensile mode and fractured surfaces were observed under scanning electron microscopy (SEM). RESULTS: The bond strength of the unlased control was significantly higher than those of the three lased groups. Among the three lased groups, irradiation with higher output energy and lower pulse repetition rate tended to affect the higher bond strength. Upon SEM observation of the fractured surface, the lased groups showed the mixture of failure in the hybrid layer in almost part. There was no significant difference among the three lased groups. CONCLUSION: It can be concluded from the results of this study that a higher pulse repetition rate is not effective for resin bonding to laser-irradiated dentin.

Animals↗
PubMed2006

Criteria for a diagnosis of caries through the DIAGNOdent.

OBJECTIVE: The aim of this study was to investigate the correlation between the demineralization depth measured by dental computed tomography (CT) and the measured value from a non-destructive dental caries diagnosis with a laser. METHODS: Optimal cut-off points were obtained for enamel and dentin caries, from the measured levels from a dental caries diagnosis with a laser, to investigate the clinical usefulness of a diagnosis using a laser. Using human teeth, the demineralization depth was measured and the caries were diagnosed by a dental caries diagnosis with a laser. RESULTS: The optimal cut-off point was investigated for accuracy, sensibility, and specificity, which were calculated from the results. These results demonstrated the correlation between the measured values and demineralization depth in both the pit and fissure caries and smooth surface caries. The optimal cut-off points were found to be 16-21 in the fissure caries and 9-11 in the smooth surface caries.

Dental Caries↗
PubMed2006

Pathological study of pulp treated with chemicals after Er:YAG laser preparation.

OBJECTIVE: The aim of this study was to clarify pulp reaction following cavity preparation with an Er:YAG laser and subsequent treatment with topically applied chemicals to achieve a high resin bond strength. BACKGROUND DATA: The application of chemicals has been found to effectively remove or reform the denatured layer produced by Er:YAG laser irradiation and has been proposed as a new strategy for improving resin bond strength. However, very little is known about pulp reaction to chemical procedures. METHODS: Class 5 dentin cavities were prepared with an Er:YAG laser in 128 teeth in nine adult dogs. The teeth were then coated with glutaraldehyde (GA group), or phosphoric acid and sodium hypochlorite (PA group) to reform or remove the denatured layer. All the cavities were then restored with composite resin. In the control group, no chemical application was carried out prior to restoration. The animals were sacrificed immediately after, and at 7 and 90 days following treatment. The treated teeth were then extracted for histopathological examination of the pulp. RESULTS: Pathological evaluation of the pulp indicated a good condition in each group at each of the three observation time points. No bacterial growth was observed on the cavity walls or bacterial invasion into the dentinal tubules or pulp chambers in any of the groups at any of the observation periods. CONCLUSION: Our findings suggest that the application of chemicals to remove or reform denatured layers is effective in obtaining better composite resin restoration with no pulp damage.

Animals↗
PubMed2006

Amelioration of murine dextran sulfate sodium-induced colitis by ex vivo extracellular superoxide dismutase gene transfer.

BACKGROUND: Although the etiology of inflammatory bowel disease has not been fully clarified, reactive oxygen species is speculated to be involved. Extracellular superoxide dismutase (EC-SOD), an isozyme of SODs, is known to function mainly in body fluids. We investigated the efficacy of an ex vivo EC-SOD gene transfer into dextran sulfate sodium (DSS)-induced colitis mice. MATERIALS AND METHODS: Experimental colitis was induced by providing Balb/c mice with DSS in sterile distilled water provided as desired. The syngenic fibroblasts were obtained from Balb/c mice embryos and retrovirally transduced with the hEC-SOD gene. These engineered cells were confirmed to secrete EC-SOD in culture medium by enzyme-linked immunosorbent assay and were inoculated subcutaneously in the backs of DSS-treated mice. Mucosal injury of the colon was evaluated by the disease activity index (DAI: body weight, rectal bleeding, and stool consistency), grading of histologic disease severity, and levels of cytokine (tumor necrosis factor-alpha, interleukin-1beta) production. 8-Hydroxydeoxyguanosine (8-OHdG) levels in the mucosal tissue were assessed by immunohistochemical staining. Malondialdehyde (MDA) was measured using a colorimetric assay. RESULTS: A significant improvement was observed in DAI score and histologic severity as well as in mucosal tissue levels of inflammatory cytokines, 8-OHdG, and MDA of mice treated with the EC-SOD gene as compared with those without gene therapy, not only in a mild colitis model but also in a severe colitis model. Survival of treated mice in these models was significantly prolonged. CONCLUSIONS: Ex vivo transfer of the EC-SOD gene was feasible for treatment of DSS-induced colitis.

Animals↗
PubMed2006

[Enteropathy-type T-cell lymphoma with CD8 and CD56 expression].

A 54-year-old male presented at a previous hospital with abdominal pain, where the patient was diagnosed as having abdominal and retroperitoneal lymphadenopathies by CT scan, then, he was referred to our hospital for further examination. Upper gastrointestinal endoscopy showed a tumor formation in the second portion of the duodenum, and there were medium sized atypical lymphocytes in biopsy specimens of the tumor. Since the atypical lymphocytes in the biopsy specimens were positive for CD3, CD8, CD56 and CD103 by immunostain, and had a rearrangement of the T-cell receptor 7-chain, the patient was diagnosed as having enteropathy-type T-cell lymphoma (ETL). Although ETL usually occurs as a complication of celiac disease, malabsorption and anti-gliadin antibodies, which are normally present in celiac disease, were not observed in this patient.

CD3 Complex↗
PubMed2006

[Peripheral T-cell lymphoma presenting with eosinophilia due to interleukin-5 produced by lymphoma cells].

A 72-year-old male was admitted to our hospital to determine the cause of neck lymphadenopathies. He was diagnosed pathologically by a lymph node biopsy as having peripheral T-cell lymphoma (PTCL). He also had developed eosinophilia and his serum concentration of Interleukin-5 (IL-5) was extremely high. Immunostaining of a resected lymph node revealed that there were lymphoma cells which were stained with anti-IL-5 antibody. After 2 courses of CHOP therapy, the lymphadenopathies and eosinophilia disappeared and the concentration of serum IL-5 was normalized. It was suggested that IL-5 produced by lymphoma cells had induced his eosinophilia.

Aged↗
PubMed2006

[Anaphylactic reaction to oxaliplatin--a case of colon cancer].

Oxaliplatin (L-OHP) is a new third-generation platinum which is efficacious in treating advanced unresectable recurrent colorectal cancer as a first-line regimen. The marketing authorization was given in Japan in March, 2005. Its increased use has resulted in rare serious adverse effects, including anaphylactic shock. We experienced a case that developed anaphylactic shock by L-OHP. We report a 69-year-old man who was treated for recurrent colorectal cancer who underwent systemic chemotherapy with FOLFOX 4. After eight cycles he developed severe L-OHP associated neuropathy and lung metastases was a progressive tendency. The FOLFOX 4 regimen was discontinued and another modality, FOLFIRI regimen, was used. After eight cycles of FOLFIRI regimen, lung and liver metastases showed progressive disease for response assessment by RECIST criteria. Although a patient was stopped L-OHP for neurotoxicity, neuropathy was disappeared after 4 months interval. Therefore, we reintroduced L-OHP, FOLFOX 4 regimen. Anaphylactic shock occurred in the second cycle of reintroduction of the FOLFOX 4 regimen (total 10 cycles), 30 minutes after infusion of L-OHP. L-OHP infusion was immediately withdrawn and he was treated with intravenous hydroxyzine hydrochloride and methylprednisolone. The anaphylaxis symptoms resolved in 30 minutes. Chemotherapy based on L-OHP for unresectable recurrence colorectal cancer causes anaphylactic shock as a rare severe complication. The prediction factor is not proved. We should take steps for early detection of anaphylactic reaction and perform the appropriate treatment.

Adenocarcinoma↗
PubMed2005

Proposal of a novel method to evaluate anastomotic tension in esophageal atresia with a distal tracheoesophageal fistula.

Anastomotic tension with the potential to lead to post-operative complication is usually evaluated using gap length before anastomosis in patients with esophageal atresia and a distal tracheoesophageal fistula (EA with a TEF). However a uniform, accurate measurement of gap length is not possible and estimation of the length the delicate distal esophageal stump is stretched by the anastomosis may have greater utility. The aim of this paper was to propose a novel method to evaluate the anastomotic tension in EA with a TEF. Forty consecutive patients having EA with a TEF were studied. Primary anastomosis without gastrostomy was performed in all cases. When the TEF was cut off, the most proximal site of the tracheal side was marked using a tiny metallic clip. When anastomosis was completed, the distance from the clip to the anastomotic site was measured as the stretched length. On the esophagram taken subsequently, the same distance was measured, together with the distance from the clip to the esophago-cardiac junction as the original distal esophageal length. The stretching ratio was calculated by dividing the former by the latter. The stretched length on esophagram (median: 3.0 mm, range: -12 to 21) was significantly correlated with that measured during surgery (median: 2.3 mm, range; -14 to 15) (r = 0.96, P < 0.0001). The median of original distal esophageal lengths was 60.0 mm (range: 35-80). The stretching ratio was significantly correlated with the stretched length, and the number of the stretching ratio as a percentage corresponded to about double the number of the stretched length on esophagram in millimeters (y = 1.91x + 0.58, r = 0.98, P<0.0001). Anastomotic leakage and recurrence of TEF were not experienced. In patients complicated with gastroesophageal reflux (GER), the site of TEF was significantly more distal as compared with the other cases [median (range): 5.0th (4.0-6.0) vs 3.5th (1.5-5.0) thoracic vertebral level, P<0.009]. The stretched length and the stretching ratio were also longer and larger, respectively [median (range): 10.0 mm (6-21) vs 2.0 (-12 to 14) mm, P<0.008, 17.3% (12.7-47.7) vs 2.9% (-16.4 to 29.8)%, P<0.018). Similar tendencies were observed for patients complicated with stricture. Estimation of the stretched length of the distal esophageal stump is useful to evaluate the anastomotic tension. If the stretched length is more than 10 mm, it will be necessary to consider the possibility that stricture or GER may arise afterwards.

Anastomosis, Surgical↗
PubMed2005

Augmentation of antitumor effects of p53 gene therapy by combination with HDAC inhibitor.

We have previously shown that the HDAC inhibitors (HDACI) activate the p53 molecule through acetylation of 320 and 373 lysine residues, upregulate PIG3 and NOXA and induce apoptosis in cancer cells expressing wild and pseudo-wild type p53 genes (Terui T, et al. Cancer Res 2003; 63:8948-54). It has also been reported that expression of the Coxsackie adenovirus receptor and subsequent transfection efficiency of the adenovirus in cancer cells were enhanced by HDACI treatment. In this study, we extended these observations to explore the combination effect of adenoviral vector carrying wild type p53 (Ad-p53) gene therapy with a HDACI, sodium butyrate (SB), on xenografted human gastric cancer cells (KATO-III) and hepatocellular carcinoma cells (HuH7) in nude mice. We first confirmed an increased expression of Coxsackie adenovirus receptors with an associated increment of transgene (X-gal) expression by SB treatment in KATO-III cells. We then injected Ad-p53 into subcutaneous tumors of KATO-III and HuH7 combined with intraperitoneal administration of SB and found a significantly higher growth suppressive effect than single treatments of each. Even a complete regression of tumors was observed in three of five mice treated with this combination while with single treatment no tumor regression was observed. Tumors treated with the combination showed higher numbers of TUNEL positive cells than those treated with a single modality. Moreover, necrotic changes were more evident in tumors treated with the combination than separately, a compatible finding to the observation that vascularity revealed by CD34 staining was poorer in tumors treated with the combination than those treated with p53 gene or SB alone. This was further supported by the finding that BAI-1 (brain specific angiogenesis inhibitor-1), an inhibitor of vascularization, was induced by SB treatment in KATO-III and HuH7 cells transfected with Ad-p53. Thus SB was shown to be an efficient potentiator of p53 gene therapy for cancer.

Adenoviridae↗
PubMed2005

Human mesenchymal stem cells xenografted directly to rat liver are differentiated into human hepatocytes without fusion.

Hepatic transdifferentiation of bone marrow cells has been previously demonstrated by intravenous administration of donor cells, which may recirculate to the liver after undergoing proliferation and differentiation in the recipient's bone marrow. In the present study, to elucidate which cellular components of human bone marrow more potently differentiate into hepatocytes, we fractionated human bone marrow cells into mesenchymal stem cells (MSCs), CD34+ cells, and non-MSCs/CD34- cells and examined them by directly xenografting to allylalcohol (AA)-treated rat liver. Hepatocyte-like cells, as revealed by positive immunostaining for human-specific alpha-fetoprotein (AFP), albumin (Alb), cytokeratin 19 (CK19), cytokeratin 18 (CK18), and asialoglycoprotein receptor (AGPR), and by reverse transcription-polymerase chain reaction (RT-PCR) for expression of AFP and Alb mRNA, were observed only in recipient livers with MSC fractions. Cell fusion was not likely involved since both human and rat chromosomes were independently identified by fluorescence in situ hybridization (FISH). The differentiation appeared to follow the process of hepatic ontogeny, reprogramming of gene expression in the genome of MSCs, as evidenced by expression of the AFP gene at an early stage and the albumin gene at a later stage. In conclusion, we have demonstrated that MSCs are the most potent component in hepatic differentiation, as revealed by directly xenografting into rat livers.

Albumins↗
PubMed2005

Telomerized human bone marrow-derived cell clones maintain the phenotype of hematopoietic-supporting osteoblastic and myofibroblastic stromal cells after long-term culture.

OBJECTIVE: Gene transfer of the telomerase catalytic subunit (TERT) into primary human stromal cells prolonged their lifespan. However, primary human stromal cells are actually composed of adipocytes, myofibroblasts, osteoblasts, etc. Our objective was to investigate the phenotype and hematopoietic-support of the human telomerized stromal cell (HTS) in clonal level. MATERIALS AND METHODS: We established HTS clones (HTS-1 to HTS-9) from a parental population of HTSs by limiting dilution. Hematopoietic-supporting activity of the HTS clones was examined by coculturing with CD34(+) cells. RESULTS: HTS-1 to HTS-3 contained alkaline phosphatase (ALP)(+) cells, and HTS-4 to HTS-9 were composed of both ALP(+) and alpha-smooth muscle actin-positive cells. Although all HTS clones exhibited normal growth kinetics, one of the HTS clones exhibited a chromosomal abnormality. Moreover, the parental population of the HTS cells acquired an increased growth rate and anchorage independence after 4 years of culturing. Expression of hematopoietic growth factors, such as stem cell factor, angiopoietin-1, and hedgehog mRNA was detected in all HTS clones. The degree of hematopoietic progenitor support differed between the HTS clones, and the expansion level of CD34(+) cells was the highest in HTS-8. CONCLUSION: Human telomerized stromal cell clones exhibited the phenotype of hematopoietic supporting osteoblastic and myofibroblastic cells after long-term culture. Clinical application of HTS cells should be limited because of their potential for neoplastic transformation after hTERT gene transfer. HTS cells may be useful for analyzing the molecular mechanism of hematopoietic support of human stromal cells.

Bone Marrow Cells↗
PubMed2005

Variations in aganglionic segment length of the enteric neural plexus in Mowat-Wilson syndrome.

BACKGROUND/PURPOSE: Patients with zinc finger homeo box 1B (ZFHX1B) mutations or deletions develop multiple congenital anomalies including Hirschsprung disease, known as Mowat-Wilson syndrome (MWS). In this study, we investigated variations in the enteric neural plexus abnormalities in MWS using morphometry-based histopathologic analysis. METHODS: Seven patients with MWS (3 with mutations in exon 8 of ZFHX1B and 4 with deletions) who had undergone modified Duhamel's operations for Hirschsprung disease were examined. Surgically resected rectosigmoid specimens were analyzed morphometrically. RESULTS: The length of the aganglionic segment was longer than 3 cm in all the patients with deletions. In 3 patients with mutations, the aganglionic region was not detected in the surgically resected specimens; however, the parameters of the ganglions and plexus were significantly smaller than those of controls (cloaca and aproctia), indicative of a transitional zone. Variation in the severity of pathological changes among the 3 patients with mutations was also noted. CONCLUSIONS: The variations in myenteric plexus pathologies in MWS appear to be caused by both variations in ZFHX1B abnormalities and epigenetic factors.

Anthropometry↗
PubMed2005

Effects of laser irradiation on tensile strength of bovine dentin.

OBJECTIVE: The purpose of the present study was to investigate the tensile strengths of dentin after laser irradiation using three kinds of dental lasers to elucidate the laser-irradiation effect on dentin properties. BACKGROUND DATA: Different kinds of laser devices have been developed in dentistry. The characteristics of each laser are determined by its original wavelength; however, one common feature is to generate heat in irradiated tissues, and such heat possibly affects dentin collagen, which contributes to tensile strength of the tissues. MATERIALS AND METHODS: Er:YAG, CO2, and diode (GaAlAs) lasers were used to irradiate bovine dentin. Subsequently, tensile test specimens were made from the irradiated dentin and tensile tests were conducted. The tensile strengths were analyzed using the paired-t test and Weibull analysis. Irradiated dentin was also observed transversally using light microscopy. RESULTS: The tensile strengths of the lased dentin and the control group for the Er:YAG, CO2, and diode lasers were 73.1 and 78.5, 70.3 and 74.3, and 64.3 and 71.0 MPa, respectively. The tensile strength of the dentin had a tendency to decrease with laser irradiation. Weibull analysis indicated that the laser influence was different among the three kinds of laser apparatuses and seemed to correspond to the depths the laser beam reached, which were suggested by light microscopy observation. CONCLUSION: Laser irradiation could possibly decrease dentin tensile strength, which suggests the importance of careful use of laser for hard tissue treatment, considering its energy-transforming characteristics.

Animals↗