Pulsed Nd:YAG laser welding of Ni-alloy Hastelloy C-276 foils

In this study a pulsed Nd:YAG laser was used to join Hastelloy C-276 thin foil with 100 microns thickness. Pulse energy was varied from 1.0 to 2.25 J at small increments of 0.25 J with a 4 ms pulse duration. The macro and microstructures of the welds were analyzed by optical and electronic microscopy, tensile shear test and microhardness. Sound laser welds without discontinuities were obtained with 1.5 J pulse energy. Results indicate that using a precise control of the pulse energy, and so a control of the dilution rate, it is possible to weld Hastelloy C-276 thin foil by pulsed Nd: YAG laser. (C) 2012 Published by Elsevier B. V. Selection and/or review under responsibility of Bayerisches Laserzentrum GmbH

Microdissecção e captura a laser na investigação do gene TP53 em tecidos incluídos em parafina

INTRODUÇÃO: Microdissecção e captura a laser (MCL) é uma técnica de desenvolvimento recente que permite a coleta de células individuais ou pequeno conjunto de células para análise molecular. Atualmente, no Brasil, há raros microscópios para MCL, de modo que a divulgação dos procedimentos inerentes a essa técnica é oportuna para destacar seu amplo potencial para diagnóstico e investigação. OBJETIVO: Este trabalho descreve a padronização dos procedimentos de MCL e de extração de DNA de material fixado em formalina e incluído em parafina. MATERIAL E MÉTODOS: Foram estudados o éxon 8 do gene TP53 e o gene da ciclofilina em amostras de tecido normal e de neoplasias de fígado e rim provenientes de modelo de carcinogênese química induzida em rato. A extração do DNA foi comprovada por reação em cadeia da polimerase (nested-PCR). RESULTADOS: Foram padronizados os procedimentos de preparo dos cortes histológicos, de microdissecção e captura a laser e de obtenção de seqüências gênicas pela reação de nested-PCR para tecidos incluídos em parafina. Obtivemos amplificação de 48,3% das amostras para o éxon 8 do gene TP53 e 51,7% para o gene da ciclofilina. Considerando pelo menos um dos dois segmentos gênicos, foram amplificadas 79,3% das amostras. DISCUSSÃO E CONCLUSÃO: A extração de DNA de tecidos fixados em formalina e incluídos em parafina e a técnica de nested-PCR foram adequadamente padronizadas para produtos gênicos de interesse, obtidos de material coletado por MCL. Esses procedimentos podem ser úteis para a obtenção de seqüências de DNA de arquivos para análise molecular.

Comparative analysis of root surface smear layer removal by different etching modalities or erbium:yttrium-aluminum-garnet laser irradiation. A scanning electron microscopy study

The purpose of this study was to evaluate the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mu m) irradiation on the removal of root surface smear layer of extracted human teeth and to compare its efficacy with that of citric acid, ethylenediamine tetra-acetic acid (EDTA), or a gel containing a mixture of tetracycline hydrochloride (HCl) and citric acid, using scanning electron microscopy (SEM). Thirty human dentin specimens were randomly divided into six groups: G1 (control group), irrigated with 10 ml of physiologic saline solution; G2, conditioned with 24% citric acid gel; G3, conditioned with 24% EDTA gel; G4, conditioned with a 50% citric acid and tetracycline gel; G5, irradiated with Er:YAG laser (47 mJ/10 Hz/5.8 J/cm(2)/pulse); G6, irradiated with Er:YAG laser (83 mJ/10 Hz/10.3 J/cm(2)/pulse). Electron micrographs were obtained and analyzed according to a rating system. Statistical analysis was conducted with Kruskal-Wallis and Mann-Whitney tests (P < 0.05). G1 was statistically different from all the other groups; no statistically significant differences were observed between the Er:YAG laser groups and those undergoing the other treatment modalities. When the two Er:YAG laser groups were compared, the fluency of G6 was statistically more effective in smear layer removal than the one used in G5 (Mann-Whitney test, P < 0.01). Root surfaces irradiated by Er:YAG laser had more irregular contours than those treated by chemical agents. It can be concluded that all treatment modalities were effective in smear layer removal. The results of our study suggest that the Er:YAG laser can be safely used to condition diseased root surfaces effectively. Furthermore, the effect of Er:YAG laser irradiation on root surfaces should be evaluated in vivo so that its potential to enhance the healing of periodontal tissues can be assessed.

Effect of low-level laser therapy on bone repair: Histological study in rats

Background and Objectives: Bone remodeling is characterized as a cyclic and lengthy process. It is currently accepted that not only this dynamics is triggered by a biological process, but also biochemical, electrical, and mechanical stimuli are key factors for the maintenance of bone tissue. The hypothesis that low-level laser therapy (LLLT) may favor bone repair has been suggested. The purpose of this study was to evaluate the bone repair in defects created in rat lower jaws after stimulation with infrared LLLT directly on the injured tissue.Study Design/Materials and Methods: Bone defects were prepared on the mandibles of 30 Holtzman rats allocated in two groups (n = 15), which were divided in three evaluation period (15, 45, and 60 days), with five animals each. control group-no treatment of the defect; laser group-single laser irradiation with a GaAlAs semiconductor diode laser device (lambda = 780 nm; P = 35 mW t = 40 s; circle minus = 1.0 mm; D = 178 J/cm(2); E = 1.4 J) directly on the defect area. The rats were sacrificed at the preestablished periods and the mandibles were removed and processed for staining with hematoxylin and eosin, Masson's Trichrome and picrosirius techniques.Results: the histological results showed bone formation in both groups. However, the laser group exhibited an advanced tissue response compared to the control group, abbreviating the initial inflammatory reaction and promoting rapid new bone matrix formation at 15 and 45 days (P < 0. 05). on the other hand, there were no significant differences between the groups at 60 days.Conclusion: the use of infrared LLLT directly to the injured tissue showed a biostimulating effect on bone remodeling by stimulating the modulation of the initial inflammatory response and anticipating the resolution to normal conditions at the earlier periods. However, there were no differences between the groups at 60 days.

Effect of Er : YAG and diode laser irradiation on the root surface: Morphological and thermal analysis

Background: the aim of the present study was to compare the effects of Er:YAG and diode laser treatments of the root surface on intrapulpal temperature after scaling and root planing with hand instruments.Methods: Fifteen extracted single-rooted teeth were scaled and root planed with hand instruments. The teeth were divided into 3 groups of 5 each and irradiated on their buccal and lingual surfaces: group A: Er:YAG laser, 2.94 mum/100 mJ/10 Hz/ 30 seconds; group B: diode laser, 810 nm/1.0 W/0.05 ms/30 seconds; group C: diode laser, 810 nm/1.4 W/0.05 ms/30 seconds. The temperature was monitored by means of a type T thermocouple (copper-constantan) positioned in the pulp chamber to assess pulpal temperature during and before irradiation. Afterwards, the specimens were longitudinally sectioned, and the buccal and lingual surfaces of each root were analyzed by scanning electron microscopy.Results: In the Er:YAG laser group, the thermal analysis revealed an average temperature of -2.2 +/- 1.5degreesC, while in the diode laser groups, temperatures were 1.6 +/- 0.8degreesC at 1.0 W and 3.3 +/- 1.0degreesC at 1.4 W. Electronic micrographs revealed that there were no significant morphological changes, such as charring, melting, or fusion, in any group, although the specimens were found to be more irregular in the Er:YAG laser group.Conclusions: the application of Er:YAG and diode lasers at the utilized parameters did not induce high pulpal temperatures. Root surface irregularities were more pronounced after irradiation with an Er:YAG laser than with a diode laser.

Short-term clinical and immunologic effects of scaling and root planing with Er : YAG laser in chronic periodontitis

Background: Recently, the erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser has been used for periodontal therapy. This study compared Er:YAG laser irradiation (100 mJ/pulse, 10 Hz, 12.9 J/cm(2)) with or without conventional scaling and root planing (SRP) to SRP only for the treatment of periodontal pockets affected with chronic periodontitis.Methods: Twenty-one subjects with pockets from 5 to 9 mm in non-adjacent sites were studied. In a split-mouth design, each site was randomly allocated to a treatment group: SRP and laser (SRPL), laser only (L), SRP only (SRP), or no treatment (C). The plaque index (PI), gingival index (GI), bleeding on probing (BOP), and interleukin (IL)-1 beta levels in crevicular fluid were evaluated at baseline and at 12 and 30 days postoperatively, whereas probing depth (PD), gingival recession (GR), and clinical attachment level (CAL) were evaluated at baseline and 30 days after treatment. A statistical analysis was conducted (P<0.05).Results: Twelve days postoperatively, the PI decreased for SRPL and SRP groups (P<0.05); the GI increased for L, SRP, and C groups but decreased for the SRPL group (P<0.05); and BOP decreased for SRPL, L, and SRP groups (P<0.01). Thirty days postoperatively, BOP decreased for treated groups and was lower than the C group (P<0.05). PD decreased in treated groups (P<0.001), and differences were found between SRPL and C groups (P<0.05). CAL gain was significant only for the SRP group (P<0.01). GR increased for SRPL and L groups (P<0.05). No difference in IL-1 beta was detected among groups and periods.Conclusion: Er:YAG laser irradiation may be used as an adjunctive aid for the treatment of periodontal pockets, although a significant CAL gain was observed with SRP alone and not with laser treatment.

Clinical and Microbiologic Follow-Up Evaluations After Non-Surgical Periodontal Treatment With Erbium:YAG Laser and Scaling and Root Planing

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influence of Er,Cr: YSGG laser on bond strength of self-adhesive resin cement

The purpose of this study was to investigate the bond strength of fiber post previously laser treated root canals. Forty single-rooted bovine teeth were endodontically treated, randomly and equally divided into two main groups according to the type of pretreatment: G1: 2.5% NaOCl (control group); and G2: Er,Cr:YSGG laser. Each group was further subdivided into 2 groups based on the category of adhesive systems/ luting materials used: a: an etch-and-rinse resin cement (Single Bond/RelyX ARC; 3M ESPE), and b: a self-adhesive resin cement (Rely X Unicem; 3M ESPE). Three 1.5 mm thick slabs were obtained per root and the push-out test was performed at a crosshead speed of 0.5 mm/min until post dislodgement occurred. Data were analyzed by ANOVA and post-hoc Tukey's test at a pre-set alpha of 0.05. Analysis of variance showed no statistically significant difference (p > 0.05) among the groups G1a (25.44 ± 2.35) and G1b (23.62 ± 3.48), G2a (11.77 ± 2.67) and G2b (9.93 ± 3.37). Fractures were observed at the interface between the dentin and the resin in all groups. The Er,Cr:YSGG laser irradiation did not influence on the bond strength of the resin cements and the etch-and-rinse resin cement had better results on bond strength than self-adhesive resin cement.

Microtensile bond strength of different adhesive systems in dentin irradiated with Er : YAG laser

The objective this study was to evaluate in vitro the bond strength of two etch-and-rise and one self-etching adhesive system after dentin irradiation with Er:YAG (erbium: yttrium aluminum garnet) laser using microtensile test. The results revealed that the groups treated with laser Er:YAG presented less tensile bond strength, independently to the adhesive system used. The prompt L-pop adhesive presented less microtensile bond strength compared to the other adhesives evaluated. There was no difference between single bond and excite groups. The adhesive failures were predominant in all the experimental groups. The Er:YAG laser influenced negatively bond strength values of adhesive systems tested in dental substrate.

Evaluation of Ultrasonic and ErCr:YSGG Laser Retrograde Cavity Preparation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bond strength of an adhesive system irradiated with Nd : YAG laser in dentin treated with Er : YAG laser

The purpose of this in vitro study was to verify through micro tensile bond test the bond strength of an adhesive system irradiated with Nd:YAG laser in dentine previously treated with Er:YAG laser. Twenty caries free extracted human third molars were used. The teeth were divided in four experimental groups (n = 5): (G1) control group; (G2) irradiation of the adhesive system with the Nd:YAG laser; (G3) dentin treatment with Er:YAG laser; (G4) dentin treatment with Er:YAG laser followed by the irradiation of the adhesive system with Nd:YAG laser. The Er:YAG laser fluency parameter for the dentin treatment was of 60 J/cm(2). ne adhesive system was irradiated with the Nd:YAG laser with fluency of 100 J/cm(2). Dental restorations were performed with Adper Single Bond 2/Z250. One tooth from each group was prepared for the evaluation of the adhesive interface under SEM and bond failure tests were also performed and evaluated. The statistical analysis showed statistical significant difference between the groups G1 and G3, G1 and G4, G2 and G3, and G2 and G4; and similarity between the groups G1 and G2, and G3 and G4. The adhesive failures were predominant in all the experimental groups. The SEM analysis showed an adhesive interface with features confirming the results of the mechanical tests. The Nd:YAG laser on the adhesive system did not influence the bond strength in dentin treated or not with the Er:YAG laser.

Nd:YAG Laser Irradiation of Etched/Unetched Dentin Through an Uncured Two-step Etch-and-Rinse Adhesive and its Effect on Microtensile Bond Strength

Purpose: To evaluate whether Nd:YAG laser irradiation of etched and unetched dentin through an uncured adhesive affected the microtensile bond strength (pTBS).Materials and Methods: Flat dentin surfaces were created in 19 extracted human third molars. Adper Single Bond (SB) adhesive was applied over etched (groups 1 to 3) or unetched dentin (groups 4 to 6). The dentin was then irradiated with a Nd:YAG laser through the uncured adhesive, using 0.75 or 1 W power settings, except for the control groups (groups 1 and 4). The adhesive was light cured and composite crowns were built up. After 24 h, the teeth were sectioned into beams, with cross-sectional areas of 0.49 mm(2), and were stressed under tension. Data were statistically analyzed using two-way ANOVA and Tukey's test (alpha = 5%). Dentin surfaces of fractured specimens and the interfaces of untested beams were observed under scanning electron microscopy (SEM).Results: Acid etching, laser irradiation, and their interaction significantly affected bonding (p < 0.05). Laser irradiation did not improve bonding of etched dentin to resin (p > 0.05). However, higher pTBS means were found on unetched lased dentin (groups 5 and 6), but only in comparison to group 4, where neither lasing nor etching was performed. Groups 4 to 6 showed the lowest pTBS means among all groups tested (p < 0.05). Laser irradiation did not change the characteristics of the hybrid layers created, while solidification globules were observed on lased dentin surfaces under SEM.Conclusion: Laser irradiation of dentin through the uncured adhesive did not significantly improve the pTBS in comparison to the suggested manufacturer's technique.

A study of actinic cheilitis treatment by two low-morbidity CO(2) laser vaporization one-pass protocols

Therapeutic approaches to chronic actinic cheilitis focus on the removal or destruction of diseased epithelium. The CO(2) laser has become an important therapeutic alternative, achieving clinical resolution in around 90% of patients. Although many laser physical parameters have been reported, some are known for their low potential for scar induction without compromising the success of the results. The aim of this clinicohistological study was to compare the therapeutic responses to two low-morbidity protocols involving a single laser pass. A total of 40 patients with chronic multicentric and microscopically proven disease were randomly submitted to two conservative CO(2) laser protocols using a bilateral comparative model. The degree of histological atypia of the epithelium was determined in 26 patients both pre- and postoperatively for both protocols. Other histological phenomena were assessed in addition to this central analysis parameter. Clinical recurrence occurred in 12.5% of patients for each protocol, together with a significant reduction in the degree of epithelial atypia (p < 0.001), which was occasionally complete. However, no difference was found between the protocols (p > 0.05). Using these morphological parameters it was not possible to determine whether postoperative epithelial atypias in part of the sample were reactive or residual in nature. A few patients may show minor postoperative lesions. Due to their potential to achieve clinical and importantly microscopic resolution, the studied protocols may be used for mild through moderate dysplastic epithelium and clinically diffuse disease.

Influence of prior 810-nm-diode intracanal laser irradiation on hydrophilic resin-based sealer obturation

Dentin wall structural changes caused by 810-nm-diode laser irradiation can influence the sealing ability of endodontic sealers. The objective of this study was to evaluate the apical leakage of AH Plus and RealSeal resin-based sealers with and without prior diode laser irradiation. Fifty-two single-rooted mandibular premolars were prepared and divided into 4 groups, according to the endodontic sealer used and the use or non-use of laser irradiation. The protocol for laser irradiation was 2.5W, continuous wave in scanning mode, with 4 exposures per tooth. After sample preparation, apical leakage of 50% ammoniacal silver nitrate impregnation was analyzed. When the teeth were not exposed to irradiation, the Real Seal sealer achieved the highest scores, showing the least leakage, with significant differences at the 5% level (Kruskal-Wallis test, p = 0.0004), compared with AH Plus. When the teeth were exposed to the 810-nm-diode laser irradiation, the sealing ability of AH Plus sealer was improved (p = 0282). In the Real Seal groups, the intracanal laser irradiation did not interfere with the leakage index, showing similar results in the GRS and GRSd groups (p = 0.1009).

Dentin bond strength: Influence of laser irradiation, acid etching, and hypermineralization

Objective: the purpose of the present study was to investigate the effects of ND:YLF laser irradiation (1.31 J/cm(2); 250 mJ per pulse), acid etching, and hypermineralization on the shear bond strength (SBS) of the Scotchbond Multi-Purpose Plus (3M Dental Products) bonding system. Summary Background Data: Previous studies had shown that the pretreatment of the dentin substrate with laser irradiation can influence the SBS, Methods: Sixty bovine incisors were selected and stored at -18 degrees C, Dentinal buccal surface was exposed and radiographs were taken to control dentin thickness, the specimens were separated into 2 groups: (1) the control, which was kept in distilled water at 4 degrees C; (2) the hypermineralized, which was kept in hypermineralizing solution at 4 degrees C for 14 days, Each group was divided into 3 subgroups according to the type of dentin pretreatment used: M (acid etching + primer + bond); AL (acid etching + primer + bond + laser); and LA (laser + acid etching + primer + bond). A standard composite resin cylinder (Z100-3M) was bonded to the dentinal surface and the SBS performed on an Instron machine (500 Kg load cell at 0.5 mm/min), followed by scanning electron microscopy (SEM) and x-ray diffraction analysis. Results: Analysis of variance (ANOVA) determined that the pretreatments influenced the SBS values (p < 0.05): AL (9.96 MPa), M (7.28 MPa), and LA (4.87 MPa), the interaction between the group and pretreatment factors also influenced the SBS (p < 0.05). The highest values were obtained for the interaction control/AL (11.64 MPa), Conclusion: the results suggested that dentin treatment with laser after the application of the adhesive system is efficient in achieving higher bond strength and is promising as a possible new adhesive substrate.