Utility of a haemoglobin test of gingival crevicular fluid: A multicentre, observational study.

OBJECTIVE: The purpose of this study was to verify the accuracy and utility of clinical parameters (plaque index, gingival crevicular fluid volume, probing depth, clinical attachment level, bleeding on probing and gingival index) and biochemical parameters (aspartate aminotransferase, protein and haemoglobin) in a longitudinal analysis during the supportive periodontal therapy period. SUBJECTS AND METHODS: A total of 279 test sites of 128 patients were investigated clinically and biochemically. After the first examination of clinical and biochemical parameters, periodontal support treatments were administered immediately and performed once every three months up to the second examination. RESULTS: All of the clinical and biochemical parameters were significantly lower at the second examination than at the first, except for the plaque index and bleeding on probing. Of these parameters, in particular, aspartate aminotransferase and haemoglobin in the gingival crevicular fluid were significantly reduced compared to those of the first examination in both the ≤4 and ≥5 mm probing depth groups, and they clearly suggested that periodontitis tended to recover. CONCLUSION: Adding the haemoglobin test to the bleeding on probing test strongly improves the accuracy of measurement of clinical parameters after periodontal treatment.

Effect of health locus of control on physical activity in stable patients with chronic obstructive pulmonary diseases.

[Purpose] A strong correlation exists between low physical activity and the prognosis of patients with chronic obstructive pulmonary disease (COPD). The interaction between psychological factors and low physical activity remains unclear in patients with COPD. Here, we investigated the impact of the health locus of control (HLOC) on the response to an education program in patients with COPD. [Participants and Methods] We assessed the physical activities and HLOC in participants with COPD before and after a five-month education program. We assessed physical activity using the Japanese version of the International Physical Activity Questionnaire (IPAQ). We evaluated the HLOC using the Japanese version of the HLOC scales. We provided an identical educational program to all participants after the initial evaluation. [Results] The total activity and walking scores were significantly elevated after the intervention. We observed a significant negative correlation between the IPAQ Total score after the intervention and the supernatural HLOC. We also observed significant negative correlations between the IPAQ Vigorous score after the intervention and Family HLOC and Chance HLOC. [Conclusion] The response of patients with COPD to self-care educational programs was influenced by the HLOC.

Non-contact acquisition of brain function using a time-extracted compact camera.

A revolution in functional brain imaging techniques is in progress in the field of neurosciences. Optical imaging techniques, such as high-density diffuse optical tomography (HD-DOT), in which source-detector pairs of probes are placed on subjects' heads, provide better portability than conventional functional magnetic resonance imaging (fMRI) equipment. However, these techniques remain costly and can only acquire images at up to a few measurements per square centimetre, even when multiple detector probes are employed. In this study, we demonstrate functional brain imaging using a compact and affordable setup that employs nanosecond-order pulsed ordinary laser diodes and a time-extracted image sensor with superimposition capture of scattered components. Our technique can simply and easily attain a high density of measurement points without requiring probes to be attached, and can directly capture two-dimensional functional brain images. We have demonstrated brain activity imaging using a phantom that mimics the optical properties of an adult human head, and with a human subject, have measured cognitive brain activation while the subject is solving simple arithmetical tasks.

Useful immunochromatographic assay of calprotectin in gingival crevicular fluid for diagnosis of diseased sites in patients with periodontal diseases.

BACKGROUND: Calprotectin, an inflammation-related protein, is present in gingival crevicular fluid (GCF), and the determination of calprotectin is useful for diagnosing periodontal diseases. The authors have recently developed a novel immunochromatographic (IC) chip system to determine calprotectin levels in GCF. In the present study, the usefulness of this diagnostic system is investigated in patients with periodontal diseases. METHODS: Thirty-six patients with periodontal diseases participated in this clinical test at multiple centers. Periodontitis sites (n = 118) and non-periodontitis (healthy) sites (n = 120) were selected after periodontal examination. GCF collection and periodontal examination were performed at baseline, after supragingival and subgingival scaling and root planing. Calprotectin levels in GCF were determined using a novel IC chip system and evaluated as a visual score and an IC reader value. Correlations between GCF calprotectin levels, clinical indicators, and changes in calprotectin levels by periodontal treatments were investigated. Receiver operating characteristic (ROC) analysis of IC reader value for GCF calprotectin was performed to predict periodontal diseases. RESULTS: The visual score of GCF calprotectin was highly correlated with the IC reader value. IC reader values of GCF calprotectin in the periodontitis group were higher than those of the healthy group at three dental examination stages, and they significantly decreased with periodontal treatments. Visual scores and IC reader values of GCF calprotectin were correlated to levels of clinical indicators. ROC analysis for GCF calprotectin showed an optimal cutoff value to predict periodontal diseases. CONCLUSION: Determination of GCF calprotectin using a novel IC chip system is useful for diagnosis of periodontal diseases.

Correlation Between Gingival Crevicular Fluid Hemoglobin Content and Periodontal Clinical Parameters.

BACKGROUND: Probing depth (PD) and bleeding on probing (BOP) are essential clinical parameters used for periodontal diagnosis. This study investigated whether detection of hemoglobin (Hb) in gingival crevicular fluid (GCF), along with PD and BOP, would improve diagnostic accuracy. METHODS: After plaque index (PI) was measured, GCF was collected from the gingival sulci of 401 anterior teeth in the maxilla and mandible from 184 patients who had entered periodontal maintenance therapy. Clinical parameters (gingival index [GI], PD, clinical attachment level [CAL], and BOP) were recorded. Hb values in GCF were assessed by immunochromatography. Moreover, cutoff values for PI, GI, and CAL based on the degree of PD and amount of GCF were created and analyzed. RESULTS: Hb was detected in 64.8% of GCF samples in 105 BOP-negative (-) sites in the periodontally stable group out of 107 sites that were less than all cutoff values. There were 71 BOP(-) sites in the periodontal-management-required group out of 122 sites that were more than all cutoff values, although no improvement in periodontal disease was observed. Hb was detected in 88.7% of GCF samples from these 71 BOP(-) sites. CONCLUSIONS: Hb was observed in more than 60% of GCF samples in BOP(-) gingival sulci in both periodontally stable and periodontal-management-required groups. These results suggest inspection of Hb derived from microbleeding in gingival sulci may serve as an index for preclinical diagnosis.

Comparative study on morphologic changes and cell attachment of periodontitis-affected root surfaces following conditioning with CO2 and Er:YAG laser irradiations.

OBJECTIVE: Clinical application of lasers in periodontal therapy has continued to expand in last decades; however there are still some controversies. The present study aimed to compare the conditioning effects of the carbon dioxide (CO2) or erbium-doped: yttrium, aluminum and garnet (Er:YAG) laser on periodontally diseased root surfaces following scaling and root planing (SRP) in terms of the alteration of morphologies as well as the attachment of periodontal ligament cells. METHODS: Forty-five periodontally affected root specimens were prepared and randomly assigned into three groups: I control (untreated diseased), II. SRP+CO2 laser (pulsed, noncontact mode), and III. SRP+Er:YAG laser (slight contact mode). After treatment, five specimens in each group were used for surface topographic examination. The remaining 10 specimens in each group were incubated with human periodontal ligament cell suspension. All the specimens were finally evaluated by scanning electron microscopy. RESULTS: The control specimens showed the lowest number of cultured cells, mostly in oval shape, with no tightly attached cells. The CO2 lased specimens showed a significant increase in the number of attached cells compared with controls, but demonstrated some major thermal alterations on the surfaces. The Er:YAG lased specimens showed the significantly highest number of attached cells, mostly in flat form, and did not show distinct thermal damage. CONCLUSIONS: The present study suggests that compared with the CO2 laser, the Er:YAG laser may constitute a more useful conditioning tool for enhancing periodontal cell attachment to periodontally diseased root surfaces, with fewer undesirable thermal side effects.

Association of untreated metabolic syndrome with moderate to severe periodontitis in Thai population.

BACKGROUND: Metabolic syndrome (MetS) correlates with systemic inflammation. A relation of MetS to periodontitis has been reported. This study aims to evaluate whether periodontitis is associated with untreated MetS, plasma adiponectin, and leptin among Thai people. METHODS: One hundred twenty-five participants (aged 35 to 76 years) were recruited. Demographic and biologic data, bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL) of all teeth were examined. Plasma adiponectin and leptin levels were measured. RESULTS: Forty-four participants (35.2%) were healthy, and 81 (64.8%) had MetS. All periodontal conditions (BOP, PD, and CAL) were significantly worse in patients with MetS than healthy participants. After adjustment for confounders, MetS was strongly associated with severe periodontitis (odds ratio [OR] = 3.60, 95% confidence interval [CI]: 1.34 to 9.65). MetS with four to five components had a higher association with periodontitis than did MetS with three components (OR = 5.49, 95% CI: 1.75 to 17.19), whereas each separate component had no association with periodontitis, except for high diastolic blood pressure. Periodontitis was also associated with age (OR = 1.08, 95% CI: 1.01 to 1.14) and education (OR = 3.76, 95% CI: 1.05 to 13.40). The risk of MetS was predicted by body mass index and plasma adiponectin (OR = 1.90, 95% CI: 1.24 to 2.92 and OR = 0.93, 95% CI: 0.88 to 0.98, respectively). CONCLUSIONS: There may be a relationship between untreated MetS and periodontitis in Thai people. Periodontal diagnosis should be regularly conducted in patients with MetS.

Comparison of salivary and plasma adiponectin and leptin in patients with metabolic syndrome.

BACKGROUND: The relationship of saliva with plasma protein levels makes saliva an attractive diagnostic tool. Plasma levels of adiponectin and leptin in healthy individuals or diabetes mellitus patients have been previously reported. Nevertheless, salivary levels of these adipocytokines in patients with metabolic syndrome (MS) have never been investigated. This study was aimed to determine adiponectin and leptin levels in saliva and plasma from patients with metabolic syndrome, and evaluate any correlation of these levels with MS. METHODS: Forty-six healthy and 82 MS patients were enrolled. Demographic data and blood biochemistries were recorded. Saliva and plasma adiponectin and leptin levels were analyzed by enzyme-linked immunosorbent assay (ELISA). RESULTS: Adiponectin and leptin were higher in plasma than in saliva (p < .001). Plasma adiponectin was decreased and plasma leptin increased in patients with MS (p < .001). Salivary adiponectin and salivary leptin were not different between healthy subjects and MS patients (p = .619 and p = .523). Correlation between salivary and plasma adiponectin showed significant association (r = .211, p = .018) while salivary and plasma leptin had no correlation (r = -.161, p = .069). Significant correlation was observed between the salivary adiponectin/salivary leptin ratio and plasma adiponectin (r = .371, p < .001), but not with any component of MS. Increased triglyceride and waist circumference were associated with risk of having a low level of plasma adiponectin (OR = 1.009; 95% CI 1.002-1.015 and OR = 1.125; 95% CI 1.029-1.230). For leptin, body mass index and high-density lipoprotein cholesterol (HDL-C) were associated with a high level of plasma leptin (OR = 1.621; 95% CI 1.212-2.168 and OR = .966; 95% CI .938-.996). The OR for MS as predicted by plasma adiponectin was .928 (95% CI .881-.977). CONCLUSIONS: This study showed that salivary adiponectin and leptin do not correlate with MS. Although correlation between salivary and plasma adiponectin was observed, no association with MS was observed. Only plasma adiponectin may be useful for the prediction of MS.

Evaluation of bleeding on probing and gingival crevicular fluid enzyme activity for detection of periodontally active sites during supportive periodontal therapy.

This study aimed to analyze the enzyme activity in gingival crevicular fluid (GCF) and its association with clinical parameters, especially bleeding on probing (BOP), and thus reconsider the significance and accuracy of recording BOP. A total of 184 patients who had entered supportive periodontal therapy were selected and GCF was collected from 401 sites before recording the clinical parameters, probing pocket depth (PPD), BOP, clinical attachment level, gingival index and plaque index. The enzyme activity of neutrophil elastase and aspartate aminotransferase and amount of protein in GCF were also analyzed. In the clinical parameters for biochemical data, amount of GCF showed the most correlation. A cut-off value for BOP and PPD were determined by the ROC curve and Youden index. Analysis was performed with all clinical parameters and biochemical data. Of the 401 sites, 51 were less than the cut-off value and were BOP-negative. On the other hand, 29 sites had values more than the cut-off value, with 14 BOP-negative sites and 15 BOP-positive sites. A conclusion is as follows: twenty-nine sites with values more than the cut-off value were diagnosed as sites requiring periodontal management, however, 14 of these were BOP-negative. These results suggest that combining other biochemical tests with examination of BOP and PPD may improve the validity of periodontal disease diagnosis. In future studies, it will be essential to find a marker that can precisely detect periodontal disease activity, and to develop a diagnostic tool for chair-side use.

Inhibitory effect of aqueous spinach extract on degranulation of RBL-2H3 cells.

The inhibitory effect of an aqueous extract from spinach on degranulation of RBL-2H3 cells is herein reported. The extract significantly suppressed antigen-induced degranulation in a dose-dependent manner without affecting cell viability. Active substances in the extract were heat-stable and trypsin-resistant with molecular weights ranging from 500 Da to 14 kDa. The extract inhibited elevation of the intracellular Ca(2+) concentration caused by stimulation by antigen, while not suppressing degranulation induced by a calcium ionophore A23187. Immunoblot analysis revealed that the inhibitory effect results from downregulation of phosphorylation of both Syk kinase and phosphatidylinositol 3-kinase in the signalling pathways involved in degranulation caused by the antigen-antibody interaction. Taken together, these findings suggest that aqueous spinach extract has an anti-allergic activity that controls degranulation.

Effect of PDGF-BB combined with EDTA gel on adhesion and proliferation to the root surface.

Periodontal regeneration using EDTA or PDGF showed promising results, but the effect of combined application was still unclear. This study aimed to verify the effect of EDTA and/or PDGF application on root adhesion and proliferation of PDL fibroblast cells. Eighty specimens were prepared from forty periodontitis teeth and made five groups: (1) diseased (untreated), (2) SRP (scaling root planing), (3) EDTA (24%), (4) PDGF (25 ng/ml) and (5) Combined application of EDTA and PDGF. Periodontal ligament cells were cultured on the above conditioned dentin plate, and SEM examination was preformed and cells were counted within a representative standard area for both cell morphology and density. All groups including untreated showed significantly increase of adhered cells from baseline to 7 days. Among them, rate of increase was much higher in EDTA, PDGF, and combined groups. ANOVA test indicated that the number of cells in PDGF and combined groups was significantly higher than diseased group at 1 day. On day 7, PDGF and combined groups showed significantly higher number of adhesion cells than that found in the diseased, SRP and EDTA groups. Thus, root conditioning with EDTA enhanced cell adhesion more than SRP alone. There was no significant difference of cell number between PDGF and combined group. Combined application of EDTA and PDGF increased significantly PDL cell adhesion than EDTA alone. PDGF alone, however, also showed comparable effect to combined application at all periods. Thus, synergistic effect between PDGF and EDTA was not observed.

Effect of human beta-defensin-3 on the proliferation of fibroblasts on periodontally involved root surfaces.

Human beta-defensin-3 (HBD-3) has versatile antibacterial activity against oral bacteria and can promote the proliferation of fibroblasts. The goal of the present study was to investigate the effect of HBD-3 on attachment and proliferation of periodontal ligament cells (PDL) onto the periodontitis affected root surfaces. PDL cells were seeded onto healthy and diseased root specimens with scaling and root planing (SRP), SRP & HBD-3 (100 ng/ml), or SRP & HBD-3 (200 ng/ml) treatment for 1, 3, and 7 days incubation. The results showed that HBD-3, especially in the 200 ng/ml group, significantly promoted fibroblast attachment and proliferation onto the diseased root surfaces. The cell number in the HBD-3 group was much greater than in the group treated with SRP alone. On day 7, the cells in the HBD-3 were well-spread and formed a network similar to those on the surfaces of the healthy root specimens. These results suggest that HBD-3 could play an important role in antibacterial activity and fibroblast proliferation, thus promoting periodontal regeneration. Meanwhile, HBD-3 might act as a potent regeneration-promoter in infectious diseases.

Long-term histologic analysis of bone tissue alteration and healing following Er:YAG laser irradiation compared to electrosurgery.

BACKGROUND: The erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser is reportedly useful for periodontal therapy. However, the potential thermal damage that Er:YAG laser irradiation can produce on bone tissue has not been fully clarified. The purpose of this study was to histologically examine the effects of the Er:YAG laser on bone tissue and subsequent wound healing compared to electrosurgery in a long-term study. METHODS: Calvarial bone from 30 rats was exposed to contact and non-contact Er:YAG laser irradiation (115 mJ/pulse, 10 Hz) without water coolant, or electrode contact. The treated surfaces were analyzed by scanning electron microscopy (SEM), and the healing process was histologically observed until 12 months post-surgery. RESULTS: Contact irradiation resulted in substantial bone ablation, whereas non-contact irradiation produced slight tissue removal. Histologic and SEM analyses of the lased surface showed no severe thermal damage, except for the production of a superficially affected layer with a microstructured surface. The layer did not inhibit new bone formation, and the ablated defect was repaired uneventfully. Although the thickness of the layer gradually decreased, it generally remained in the cortical bone through the observation period. Electrosurgery produced a large area of thermal necrosis without ablation, and the damaged area was not replaced with new bone. CONCLUSIONS: Unlike electrosurgery, Er:YAG laser irradiation without water coolant easily ablated bone tissue, and thermal alteration in the treated surface was minimal. The superficially affected layer did not interfere with the ensuing bone healing, resulting in favorable repair of the defect.

Intralesional laser treatment of voluminous vascular lesions in the oral cavity.

OBJECTIVE: In laser treatment of voluminous vascular lesions, there are many cases in which submucosally located angioma remnants cannot be reached by noncontact superficial laser application. To diminish these remnants we used intralesional photocoagulation (ILP) in treatment of oral vascular lesions, because this approach is effective in treatment of voluminous vascular lesions of the skin. STUDY DESIGN: Four cases of voluminous vascular malformation in the oral cavity were treated by ILP using a potassium-titanyl-phosphate (KTP) laser. In 1 case, treatment was carried out under ultrasound and manual control. RESULTS: All lesions showed more than 70% regression after the first ILP session, and the treatment outcome was satisfactory. There were no serious complications, such as bleeding or invasive infection. Ultrasonography was useful for guiding laser treatment in the oral cavity. CONCLUSION: Intralesional photocoagulation treatment with a KTP laser is effective and safe for treatment of a vascular lesion in the oral cavity.

Submucosal glycerol injection-assisted laser surgical treatment of oral lesions.

Recently, we modified laser surgery for superficial lesions in the oral cavity by using submucosal glycerol injection. This procedure was based on a technique for endoscopic mucosal resection (EMR) in the gastrointestinal tract. The aim of this study was to evaluate the effectiveness of the modified laser surgery assisted by a submucosal glycerol injection. Eleven superficial oral lesions in ten patients were treated with diode laser (continuous wave mode, 3 W) after a submucosal injection of glycerol solution. Injection of glycerol solution created mucosal expansion, which enabled the procedures to be done without bleeding, over cutting, over coagulation and unintended irradiation. The surface of the wounds showed little carbonization, resulting in good healing. Submucosal glycerol injection for laser treatment in the oral cavity is a promising technique for treating superficial oral lesions by virtue of less invasion and good results.

Molecular effects of the tissue-nonspecific alkaline phosphatase gene polymorphism (787T > C) associated with bone mineral density.

Based on studies of hypophosphatasia, which is a systemic skeletal disorder resulting from tissuenonspecific alkaline phosphatase (TNSALP) deficiency, TNSALP was suggested to be indispensable for bone mineralization. Recently, we demonstrated that there was a significant difference in bone mineral density (BMD) among haplotypes, which was lowest among TNSALP (787T [Tyr-246Tyr]) homozygotes, highest among TNSALP (787T > C [Tyr246His]) homozygotes, and intermediate among heterozygotes. To analyze protein translated from the TNSALP gene 787T > C, we performed the biosynthesis of TNSALPs using TNSALP cDNA expression vectors. TNSALP (787T) and TNSALP (787T > C) were synthesized similarly as a high-mannose-type 66-kDa form, becoming an 80-kDa form. Expression of the human 787T > C TNSALP gene using the cultured mouse marrow stromal cell line ST2 demonstrated that the protein translated from 787T > C exhibited an ALP-specific activity similarly to that of 787T. Interestingly, the Km value for TNSALP in ST2 cells transfected with the 787T > C TNSALP gene was decreased significantly compared to that of cells carrying the 787T gene (P < 0.01). These results suggest that the significant difference in Km values between the proteins translated from 787T > C and 787T may contribute to regulatory effects on bone metabolism.

Functional polymorphisms of the FPR1 gene and aggressive periodontitis in Japanese.

Aggressive periodontitis (AgP), a severe and early onset type of periodontitis, is thought to be subject to significant genetic background effects. Formyl peptide receptor 1 (FPR1) is a gene strongly implicated in AgP. To determine whether variations in this gene are associated with AgP, we performed an association study with 49 AgP patients and 373 controls using 30 variations identified by sequencing the 21.1-kb gene region. Five polymorphisms (-12915C>T, -10056T>C, -8430A>G, 301G>C, and 546C>A) showed significant association with AgP. Polymorphonuclear neutrophils from subjects carrying the -12915T allele expressed significantly lower levels of FPR1 transcripts than those homozygous for the -12915C allele. Furthermore, the -12915T allele decreased activity of transcriptional regulation in a luciferase assay. Haplotype association analysis with three SNPs (-12915C>T, 301G>C, and 546C>A) revealed that one haplotype (-12915T-301G-546C) was significantly represented in AgP patients (p=0.000020). Thus, altered FPR1 function might confer increased risk to AgP.

Effect of Er:YAG laser combined with rhPDGF-BB on attachment of cultured fibroblasts to periodontally involved root surfaces.

BACKGROUND: The use of the erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser in periodontal therapy has been the focus of much research. Recombinant human platelet-derived growth factor-BB (rhPDGF-BB) is suggested as a potent stimulator and strong mitogen for human periodontal ligament cells. The present study tested the direct effects of Er:YAG laser irradiation, alone or with rhPDGF-BB application, on the biocompatibility of periodontally diseased roots through fibroblast attachment and proliferation. METHODS: The study examined five healthy and 15 periodontally involved teeth, prepared from proximal surfaces, which were divided randomly into four groups (10 specimens each): group 1: healthy; group 2: untreated diseased; group 3: Er:YAG laser irradiation (60 mJ/pulse, 10 Hz); and group 4: Er:YAG laser irradiation (60 mJ/pulse, 10 Hz) plus rhPDGF-BB application (50 ng/ml). Three subgroups per group (three specimens each) were incubated for three periods (1, 3, or 7 days). The remaining specimen was used to determine surface topography. Fibroblasts were pooled on root specimens and incubated. Results were evaluated using scanning electron microscopy. Repeated cell counts were performed within a representative standard area. RESULTS: Using paired t tests, all experimental groups (except group 2 diseased) showed statistically significant differences between 1- and 3-day and between 1- and 7-day incubation periods, but not between 3- and 7-day incubation periods. Using analysis of variance, the intergroup comparison showed significant differences favoring group 1 over groups 2 and 3 and group 4 over group 2 at the 1-day incubation period; group 1 was favored over groups 2, 3, and 4 and groups 3 and 4 were favored over group 2 at the 3- and 7-day incubation periods. Comparable effects were shown between groups 3 and 4 for all incubation periods and between groups 2 and 3 and groups 1 and 4 for the 1-day incubation. CONCLUSIONS: Er:YAG laser used alone or in combination with rhPDGF-BB application may offer a promising periodontal therapy for conditioning root surfaces, although the combined application seemed to be slightly more effective. However, testing laser use in intervals and with parameters <60 mJ/pulse and 10 Hz is required to verify the minimum threshold values necessary to obtain complete root debridement and clarify optimal conditions for fibroblast cell attachment and growth. Further studies are needed to determine ideal parameters for creating the best environment for successful periodontal treatment.

Effect of low-level Er:YAG laser irradiation on cultured human gingival fibroblasts.

BACKGROUND: Low-level laser irradiation has been reported to enhance wound healing. Activation of gingival fibroblasts (GF) has a potential for early wound healing in periodontal treatment. The present study aimed to investigate the direct effect of low-level Er:YAG laser irradiation on gingival fibroblasts proliferation in order to clarify the laser effect on healing. METHODS: Cultured human gingival fibroblasts (hGF) were exposed to low-power, pulsed Er:YAG laser irradiation with different energy densities ranging from 1.68 to 5.0 J/cm(2). The cultures were analyzed by means of trypan blue staining and counted under a light microscope. The effect of Er:YAG laser on hGF was also evaluated using a transmission electron microscope (TEM). RESULTS: Cultures irradiated with Er:YAG laser presented faster cell growth when compared with untreated controls. This difference was statistically significant. Transmission electron microscopy revealed rough endoplasmic reticulum, prominent Golgi complexes, and mitochondria after laser irradiation. CONCLUSIONS: Our results showed that the low-level Er:YAG laser irradiation stimulates the proliferation of cultured gingival fibroblasts. The optimal stimulative energy density was found to be 3.37 J/cm(2). This result suggests that Er:YAG laser irradiation may be of therapeutic benefit for wound healing.