Confocal laser scanning microscopy is appropriate to detect viability of Enterococcus faecalis in infected dentin

The purpose of this study was to explore the potential of confocal laser scanning microscopy (CLSM) for in situ identification of live and dead Enterococcus faecalis in infected dentin. Eight cylindrical dentin specimens were infected with Enterococcus faecalis in BHI for 21 days. After the experimental period, the specimens were stained with fluorescein diacetate (FDA) and propidium iodide (PI) or acridine orange (0.01 %) and analyzed by CLSM. Two noninfected dentin specimens were used as negative controls. CLSM analysis shows that the discrimination between viable (green) and dead (red) bacteria in infected dentinal tubules could be observed after staining with FDA/PI. Acridine orange was able to show metabolic activity of the E. faecalis cells inside the dentinal tubules showed by its red fluorescence. The viability of bacteria in infected dentin can be determined in situ by CLSM. FDA/PI and acricline orange are useful for this technique.

Comparison of visual inspection, radiographic examination, laser fluorescence and their combinations on treatment decisions for occlusal surfaces

Purpose: To compare visual inspection (VI), radiographic examination (RX) and the laser fluorescence device DIAGNOdent (L), as well as their combinations in vitro regarding treatment decisions for occlusal surfaces. Methods: 72 extracted human permanent teeth (molars and premolars) were used. Treatment decisions were recorded by three calibrated examiners, and the options available were fissure sealant and conservative restoration. For validation of treatment decisions, the teeth were sectioned and examined in a stereomicroscope. Thereafter, dental slices were scanned and the images were edited to facilitate classification of existing carious lesions. Intra and inter-examiner reproducibility for the determination of treatment plans were calculated using Cohen`s kappa test (95%-CI). Sensitivity, specificity, positive and negative predictive values, and the area under the ROC curve were also calculated. Results: VI and L provided on average the greatest intra- and inter-examiner reproducibility, respectively. Although the combination of diagnostic methods may decrease both intra- and inter examiners reproducibility, combination of VI, L and RX resulted in the greatest sensitivity, being statistically superior to RX and L. There was more inter-examiner agreement for the option of restorative treatment, while the use of sealants as a treatment option yielded the lowest values. Negative predictive values were numerically inferior to positive predictive values, indicating that the examiners preferred not to restore a carious tooth than to proceed operatively in an intact tooth. The combination of the three methods studied showed the best results in determining treatment plans for occlusal surfaces, when compared to the other types of exams. On the other hand, radiographic examination and laser fluorescence were less efficient when used alone.

Effect of laser phototherapy on the release of fibroblast growth factors by human gingival fibroblasts

The effects of laser phototherapy on the release of growth factors by human gingival fibroblasts were studied in vitro. Cells from a primary culture were irradiated twice (6 h interval), with continuous diode laser [gallium-aluminum-arsenium (GaAlAs), 780 nm, or indium-gallium-aluminum-phosphide (InGaAlP),_660 nm] in punctual and contact mode, 40 mW, spot size 0.042 cm(2), 3 J/cm(2) and 5 J/cm(2) (3 s and 5 s, respectively). Positive [10% fetal bovine serum (FBS)] and negative (1%FBS) controls were not irradiated. Production of keratinocyte growth factor (KGF) and basic fibroblast growth factor (bFGF) was quantified by enzyme-linked immunosorbent assay (ELISA). The data were statistically compared by analysis of variance (ANOVA) followed by Tukey`s test (P a parts per thousand currency signaEuro parts per thousand 0.05). The characterization of the cell line indicated a mesenchymal nature. KGF release was similar in all groups, while that of bFGF was significantly greater (1.49-times) in groups treated with infra-red laser. It was concluded that increased production of bFGF could be one of the mechanisms by which infra-red laser stimulates wound healing.

Surgical planning for resection of an ameloblastoma and reconstruction of the mandible using a selective laser sintering 3D biomodel

Ameloblastoma is a benign locally aggressive infiltrative odontogenic lesion. It is characterized by slow growth and painless swelling. The treatment for ameloblastoma varies from curettage to en bloc resection, and the reported recurrence rates after treatment are high; the safety margin of resection is important to avoid recurrence. Advances in technology brought about great benefits in dentistry; a new generation of computed tomography scanners and 3-dimensional images enhance the surgical planning and management of maxillofacial tumors. The development of new prototyping systems provides accurate 3D biomodels on which surgery can be simulated, especially in cases of ameloblastoma, in which the safety margin is important for treatment success. A case of mandibular follicular ameloblastoma is reported where a 3D biomodel was used before and during surgery.

Noradrenaline Involvement in the Negative-Feedback Effects of Ovarian Steroids on Luteinising Hormone Secretion

Noradrenaline has been shown to modulate the ovarian-steroid feedback on luteinising-hormone (LH) release. However, despite the high amount of evidence accumulated over many years, the role of noradrenaline in LH regulation is still not clearly understood. The present study aimed to further investigate the involvement of noradrenaline in the negative-feedback effect of oestradiol and progesterone on basal LH secretion. In experiment 1, ovariectomised (OVX) rats received a single injection of oil, oestradiol, or progesterone at 09.00-10.00 h and were decapitated 30 or 60 min later. Levels of noradrenaline and its metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), were determined in microdissections of the preoptic area (POA) and medial basal hypothalamus-median eminence (MBH-ME) and correlated with LH secretion. Basal LH levels were decreased 30 and 60 min after oestradiol or progesterone injection, and this hormonal response was significantly correlated with a reduction in POA MHPG levels, which reflect noradrenaline release. In addition, noradrenaline levels in the POA were increased, whereas noradrenaline turnover (MHPG/noradrenaline ratio) was decreased 60 min after the injection of both hormones. No effect was found in the MBH-ME. In experiment 2, i.c.v. administration of noradrenaline (60 nmol), performed 15 min before oestradiol or progesterone injection in jugular vein-cannulated OVX rats, completely prevented the ovarian steroid-induced inhibition of LH secretion. The data obtained provide direct evidence that LH secretion in OVX rats is positively regulated by basal noradrenergic activity in the POA, and its reduction appears to play a role in the negative-feedback effect of ovarian steroids on LH secretion in vivo.

The application of electron microscopy and microanalysis in conjunction with organic petrology to further the understanding of organic-mineral association: examples from Mount Isa and McArthur Basins, Australia

Organic petrology supported by electron microscopical and micro-analytical techniques was applied to organic matter in Proterozoic sediments to better understand hydrothermal processes responsible for ore-grade mineralisation. It was shown that organic maturation was not only closely linked to the geological history of the sediments, but also highlighted heat transfer by convection as differentiated from conduction solely through sediment burial and step-wise subsidence. Water-rock ratios effect organic maturation in hydrothermal systems, and erratic reflectance profiles are indicators of convective heat transfer. Identification and characterisation of organic materials in terms of source rock and migrated hydrocarbons was shown to be a powerful tool in reconstructing the thermal history of sediments, identifying hydrothermal episodes, fluid pathways and heat source in the northern Australian Proterozoic basins. Higher reflectance of organic matter towards the central parts of the Mount Isa Basin and some of the most northerly parts point to proximity to higher heat flow at times, in contrast to relatively low temperatures prevailing in the western parts of the basin, next to the Murphy Inlier. A close correlation shown between peak organic reflectance values and super-sequence boundaries farther highlighted the valuable information to be gained from organic petrology, by allowing the separation of processes responsible for metal dissolution and transportation from those inducing precipitation. (C) 2001 Elsevier Science B.V All rights reserved.

Influence of the irradiation distance and the use of cooling to increase enamel-acid resistance with Er:YAG laser

Objectives: The aim of this study was to assess the influence of irradiation distance and the use of cooling in the Er:YAG laser efficacy in preventing enamel demineralization. Methods: 84 enamel blocks were randomly assigned to seven groups (n = 12): G1: control group - no treatment, G2-G7: experimental groups treated with Er:YAG laser (80 mJ/2 Hz) at different irradiation distances with or without cooling: G2: 4 mm/2 mL; G3: 4 mm/no cooling; G4: 8 mm/2 mL; G5: 8 mm/no cooling; G6: 16 mm/2 mL; G7: 16 mm/no cooling. The samples were submitted to an in vitro pH cycles for 14 days. Next, the specimens were sectioned in sections of 80-100 mu m in thickness and the demineralization patterns of prepared slices were assessed using a polarized light microscope. Three samples from each group were analyzed with scanning electronic microscopy. Analysis of variance and the Fisher test were performed for the statistical analysis of the data obtained from the caries-lesion-depth measurements (CLDM) (alpha = 5%). Results: The control group (CLDM = 0.67 mm) was statistically different from group 2 (CLDM = 0.42 mm), which presented a smaller lesion depth, and group 6 (0.91 mm), which presented a greater lesion depth. The results of groups 3 (CLDM = 0.74 mm), 4 (CLDM = 0.70 mm), 5 (CLDM = 0.67 mm) and 7 (CLDM = 0.89 mm) presented statistical similarity. The scanning electronic microscopy analysis showed ablation areas in the samples from groups 4, 5, 6 and 7, and a slightly demineralized area in group 2. Conclusions: It was possible to conclude that Er:YAG laser was efficient in preventing enamel demineralization at a 4-mm irradiation distance using cooling. (C) 2010 Elsevier Ltd. All rights reserved.

Effect of erbium:yttrium-aluminum-garnet laser energies on superficial and deep dentin microhardness

This study evaluated the microhardness of superficial and deep dentin irradiated with different erbium:yttrium-aluminum-garnet (Er:YAG) laser energies. Seventy-two molars were bisected and randomly assigned to two groups (superficial dentin or deep dentin) and into six subgroups (160 mJ, 200 mJ, 260 mJ, 300 mJ, 360 mJ, and control). After irradiation, the cavities were longitudinally bisected. Microhardness was measured at six points (20 A mu m, 40 A mu m, 60 A mu m, 80 A mu m, 100 A mu m, and 200 A mu m) under the cavity floor. Data were submitted to analysis of variance (ANOVA) and Fisher`s tests (alpha = 0.05). Superficial dentin presented higher microhardness than deep dentin; energy of 160 mJ resulted in the highest microhardness and 360 mJ the lowest one. Values at all points were different, exhibiting increasing microhardness throughout; superficial dentin microhardness was the highest at 20 A mu m with 160 mJ energy; for deep dentin, microhardness after irradiation at 160 mJ and 200 mJ was similar to that of the control. The lowest energy increased superficial dentin microhardness at the closest extent under the cavity; deep dentin microhardness was not altered by energies of 160 mJ and 200 mJ.

Low Level Laser Effects On Pain to Palpation and Electromyographic Activity in TMD Patients: A Double-Blind, Randomized, Placebo-Controlled Study

The purpose of this study was to evaluate the effect of diode laser (GaAlAs - 780 nm) on pain to palpation and electromyographic (EMG) activity of the masseter and anterior temporalis muscles. The laser was applied on the temporalis and masseter muscles twice a week (four weeks). Forty-eight (48) patients with myofascial pain were randomly assigned between actual and placebo treatments and between the energetic doses of 25 J/cm(2) and 60 J/cm(2), and were evaluated using VAS before, immediately after the final application, and 30 days after the laser treatment. Surface electromyography was performed with maximum dental clenching before and after laser therapy. The results show there were no significant statistical differences in the EMG activity between the groups before and after laser treatment. With regard to the pain at palpation, although both groups presented a significant difference in the symptoms before and after the treatment, only the active doses showed statistically significant reductions in pain level in all the regions of the palpated muscles. However, there was no significant statistical difference between groups (experimental and placebo). In conclusion, low level laser did not promote any changes in EMG activity. The treatment did, however, lessen the pain symptoms in the experimental groups.

Composite filling removal with erbium:yttrium-aluminum-garnet laser: morphological analyses

Considering the increase in esthetic restorative materials and need for improvement in unsatisfactory restoration substitution with minimal inadvertent removal of healthy tissues, this study assessed the efficacy of erbium:yttrium-aluminum-garnet (Er:YAG) laser for composite resin removal and the influence of pulse repetition rate on the morphological analyses of the cavity by scanning electron microscope. Composite resin fillings were placed in cavities (1.0 mm deep) prepared in bovine teeth, and the 75 specimens were randomly assigned to five groups according to the technique used for composite filling removal (high-speed diamond bur, group I, as a control, and Er:YAG laser, 250 mJ output energy and 80 J/cm(2) energy density, using different pulse repetition rates: group II, 2 Hz; group III, 4 Hz; group IV, 6 Hz; group V, 10 Hz). After the removal, the specimens were split in the middle, and we analyzed the surrounding and deep walls to check for the presence of restorative material. The estimation was qualitative. The surfaces were examined with a scanning electron microscope. The results revealed that the experimental groups presented bigger amounts of remaining restorative material. The scanning electron microscopy (SEM) analyses showed irregularities of the resultant cavities of the experimental groups that increased proportionally with increase in repetition rate.

Morphological Alterations of Radicular Dentine Pretreated With Different Irrigating Solutions and Irradiated With 980-nm Diode Laser

Background: The topographical features of intraradicular dentine pretreated with sodium hypochlorite (NaOCl) or ethylenediamine tetraacetic acid (EDTA) followed by diode laser irradiation have not yet been determined. Purpose: To evaluate the alterations of dentine irradiated with 980-nm diode laser at different parameters after the surface treatment with NaOCl and EDTA. Study design: Roots of 60 canines were biomechanically prepared and irrigated with NaOCl or EDTA. Groups were divided according to the laser parameters: 1.5 W/CW; 1.5 W/100 Hz; 3.0 W/CW; 3.0 W/100 Hz and no irradiation (control). The roots were splited longitudinally and analyzed by scanning electron microscopy (SEM) in a quali-quatitative way. The scores were submitted to two-way Kruskal-Wallis and Dunn`s tests. Results: The statistical analysis demonstrated that the specimens treated only with NaOCl or EDTA (control groups) were statistically different (P < 0.05) from the laser-irradiated specimens, regardless of the parameter setting. The specimens treated with NaOCl showed a laser-modified surface with smear layer, fissures, and no visible tubules. Those treated with EDTA and irradiated by laser presented absence of smear layer, tubules partially exposed and melting areas. Conclusions: The tested parameters of 980-nm diode laser promoted similar alterations on dentine morphology, dependent to the type of surface pretreatment. Microsc. Res. Tech. 72:22-27, 2009. (C) 2008 Wiley-Liss, Inc.

Coronal resistance to fracture of endodontically treated teeth submitted to light-activated bleaching

Objectives: The aim of this study was to assess the fracture resistance of endodontically treated teeth submitted to bleaching with 38% hydrogen peroxide activated by light-emitting diode (LED)-laser system. Methods: Fifty maxillary incisors were endodontically treated, received a zinc phosphate barrier and were embedded in acrylic resin until cemento-enamel junction. The specimens were distributed into five groups (n = 10) according to the number of bleaching sessions: GI, no treatment (control); GII, one session; GIII, two sessions; GIV, three sessions and GV, four sessions. The whitening gel was applied to the buccal surface of the tooth and inside the pulp chamber for three times in each session, followed by LED-laser activation. Specimens were submitted to the fracture resistance test (kN) and data were submitted to the Tukey-Kramer multiple comparisons test. Results: No significant difference (p > 0.05) was found between GI (0.71 +/- 0.30) and GII (0.65 +/- 0.13), which presented the highest strength values to fracture. Groups III (0.35 +/- 0.17), IV (0.23 +/- 0.13) and V (0.38 +/- 0.15) showed lower resistance to fracture (p < 0.01) when compared to GI and GII. Conclusions: The fracture resistance of endodontically treated teeth decreased after two sessions of bleaching with 38% hydrogen peroxide activated by LED-laser system. (c) 2008 Elsevier Ltd. All rights reserved.

Low Intensity Laser Therapy in Temporomandibular Disorder: a Phase II Double-Blind Study

The purpose of this study was to evaluate the analgesic effect of Low Intensity Laser Therapy (LILT) and its influence on masticatory efficiency in patients with temporomandibular dysfunction (TMD). This study was performed using a random, placebo-controlled, and double-blind research design. Fourteen patients were selected and divided into two groups (active and placebo). Infrared laser (780 nm, 70 mw, 60s, 105J/cm(2)) was applied precisely and continuously into five points of the temporomandibular joint (TMJ) area: lateral point (LP), superior point (SP), anterior point (AP), posterior point (PP), and posterior-inferior point (PIP) of the condylar position. This was performed twice per week, for a total of eight sessions, To ensure a double-blind study, two identical probes supplied by the manufacturer were used: one for the active laser and one for the inactive placebo laser. They were marked with different letters (A and B) by a clinician who did not perform the applications. A Visual Analogue Scale (VAS) and a colorimetric capsule method were employed. Data were obtained three times: before treatment (Ev1), shortly after the eighth session (Ev2), and 30 days after the first application (Ev3). Statistical tests revealed significant differences at one percent (1%) likelihood, which implies that superiority of the active group offered considerable TMJ pain improvement. Both groups presented similar masticatory behavior, and no statistical differences were found. With regard to the evaluation session, Ev2 presented the lowest symptoms and highest masticatory efficiency throughout therapy. Therefore, low intensity laser application is effective in reducing TMD symptoms, and has influence over masticatory efficiency [Ev2 (0.2423) and Ev3 (0.2043), observed in the interaction Evaluations x Probes for effective dosage].

Bond strength of AH Plus and Epiphany sealers on root dentine irradiated with 980 nm diode laser

Aim To evaluate the bond strength of AH Plus and Epiphany sealers to human root canal dentine irradiated with a 980 nm diode laser at different power and frequency parameters, using the push-out test. Methodology Sixty canine roots were sectioned below the cementoenamel junction to provide 4-mm-thick dentine discs that had their root canals prepared with a tapered bur and irrigated with sodium hypochlorite, ethylenediaminetetraacetic acid and distilled water. The specimens were assigned to five groups (n = 12): one control (no laser) and four experimental groups that were submitted to 980 nm diode laser irradiation at different power (1.5 and 3.0 W) and frequency (continuous wave and 100 Hz) parameters. Half of specimens in each group had their canals filled with AH Plus sealer and half with Epiphany. The push-out test was performed and data (MPa) were analysed statistically by ANOVA and Tukey`s test (P < 0.05). The specimens were split longitudinally and examined under SEM to assess the failure modes after sealer displacement. Results The specimens irradiated with the diode laser and filled with AH Plus had significantly higher bond strength values (8.69 +/- 2.44) than those irradiated and filled with Epiphany (3.28 +/- 1.58) and the nonirradiated controls (3.86 +/- 0.60). The specimens filled with Epiphany did not differ significantly to each other or to the control (1.75 +/- 0.69). There was a predominance of adhesive failures at Epiphany-dentine interface (77%) and mixed failures at AH Plus-dentine interface (67%). Conclusions The 980 nm diode laser irradiation of root canal dentine increased the bond strength of AH Plus sealer, but did not affect the adhesion of Epiphany sealer.