Ultrashort pulsed laser conditioning of human enamel: in vitro study of the influence of geometrical processing parameters on shear bond strength of orthodontic brackets.

The surfaces of 63 extracted premolar teeth were processed with intense ultrashort laser pulses (λ = 795 nm; pulse duration, 120 fs; repetition rate, 1 kHz) to produce cross patterns with different pitches (s) in the micrometer range in order to evaluate the influence of such microstructures on the shear bond strengths of orthodontic brackets to enamel. The samples were classified in nine groups corresponding to the control group (raw samples) and eight different laser-processed groups (cross patterns with s increasing from 15 to 180 µm). Brackets were luted with Transbond(TM) XT adhesive resin to all the samples; after 72 h, they all were submitted to strength test in a universal testing machine. Additionally, a third of the samples underwent morphological analysis of the debonded surface by means of scanning electron microscope microscopy and an analysis of the failure mode based on the adhesive remnant index. The results showed that enamel microstructuring with ultrashort laser pulses remarkably increase the bond strength of brackets. Dense cross patterns (s < 90 µm) produce the highest increase of bond strengths as compared to control group whereas light ones (s > 90 µm) give rise to smaller improvements of the bond strength. A strong correlation of this behavior with the predominant failure mode in both scenarios was found. So far, the best compromise between suitable adhesive efficiency, processing time minimization, and enamel surface preservation suggests the performance of cross patterns with pitches in the order of 90 µm.

Influence of Er:YAG and Ti:sapphire laser irradiation on the microtensile bond strength of several adhesives to dentin.

The aim of the present study was to evaluate the influence of erbium:yttrium-aluminum-garnet (Er:YAG) and Ti:sapphire laser irradiation on the microtensile bond strength (MTBS) of three different adhesive systems to dentin. Flat dentin surfaces from 27 molars were divided into three groups according to laser irradiation: control, Er:YAG (2,940 nm, 100 µs, 2.7 W, 9 Hz) and Ti:sapphire laser (795 nm, 120 fs, 1 W, 1 kHz). Each group was divided into three subgroups according to the adhesive system used: two-step total-etching adhesive (Adper Scotchbond 1 XT, from now on XT), two-step self-etching adhesive (Clearfil SE Bond, from now on CSE), and all-in-one self-etching adhesive (Optibond All-in-One, from now on OAO). After 24 h of water storage, beams of section at 1 mm(2) were longitudinally cut from the samples. Each beam underwent traction test in an Instron machine. Fifteen polished dentin specimens were used for the surface morphology analysis by scanning electron microscopy (SEM). Failure modes of representative debonded microbars were SEM-assessed. Data were analyzed by ANOVA, chi-square test, and multiple linear regression (p < 0.05). In the control group, XT obtained higher MTBS than that of laser groups that performed equally. CSE showed higher MTBS without laser than that with laser groups, where Er:YAG attained higher MTBS than ultrashort laser. When OAO was used, MTBS values were equal in the three treatments. CSE obtained the highest MTBS regardless of the surface treatment applied. The Er:YAG and ultrashort laser irradiation reduce the bonding effectiveness when a two-step total-etching adhesive or a two-step self-etching adhesive are used and do not affect their effectiveness when an all-in-one self-etching adhesive is applied.

In vitro analysis of femtosecond laser as an alternative to acid etching for achieving suitable bond strength of brackets to human enamel.

This study aims to evaluate the effect of laser irradiation and orthophosphoric acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel. Three groups (n = 20) of extracted premolar teeth were randomly established depending on the laser treatment performed on the buccal surfaces: (1) no laser (control); (2) Er:YAG laser (2,940 nm, 0.8 W, 100 µs/pulse, 10 Hz) and; (3) Ti:Sapphire laser (795 nm, 1 W, 120 fs/pulse, 1 kHz). Each group was divided into two subgroups according to whether 37%-orthophosphoric acid etching was made after laser irradiation or not. Brackets were randomly luted with Transbond(TM) XT adhesive resin. After 72 h, a SBS test was developed in a universal testing machine (crosshead speed, 0.5 mm/min). Representative specimens from each experimental subgroup were examined by means of scanning electron microscopy. Cement residuals remaining on the premolar surfaces were assessed using the adhesive remnant index. ANOVA, post-hoc tests for intergroup comparisons, chi-square test and linear regression were run for data analyses (α = 0.05). After acid etching, SBS values did not differ regardless the laser treatment. When phosphoric acid was not applied, the SBS values of the femtosecond laser group were significantly higher than for the other groups. Femtosecond laser without acid seems to be the most suitable method to improve bond strengths at the bracket/enamel interface, thus avoiding the disadvantages inherent to acid etching.

Contributions of dental colour to the physical attractiveness stereotype.

Dental appearance may play a key role on the way we develop a first impression of another person. To test whether relatively minor changes in the lightness of tooth colour would influence the perceived social appeal (social, intellectual, psychological and relational abilities) of an unknown male and unknown female, this cross-sectional study was performed on 555 Spanish adults. The two major independent variables related to the photograph were tooth lightness (computer-derived), divided into three levels that included lightened teeth, natural teeth and darkened teeth, and the gender of the observed face. Moreover, six independent variables related to the observer were assessed (age, gender, educational level, place of residence, frequency of brushing and self-reported health status). The dependent variables were scored on five-point Likert scales designed to quantify four domains (social, intellectual, psychological and relationship competences) of the Social Appeal Scale (SAS). Tooth lightness influences the perception of social appeal in all dimensions, as darkened smiles received significantly poorer scores than natural-colour smiles, but these were also worse than lightened smiles. A logistic regression analysis revealed that the major predictor of social appeal was tooth lightness, and for each increment in lightness (from darkened to lightened smiles), the odds ratio (OR) of positive values being perceived increased significantly in all items (from 2·3 in Popularity to 6·9 in Happiness). A perceptible change in dental lightness is the strongest factor associated with the dental attractiveness stereotype, affecting significantly the 12 traits assessed, but mainly the Happiness, Social Relations and Academic Performance.

Anesthetic considerations in the perioperative management of the patient with Jarcho-Levin Syndrome.

Jarcho-Levin syndrome is an eponym used to describe a spectrum of small thoracic skeletal dysplasias with variable involvement of vertebrae and ribs. Initially considered lethal, it is currently compatible with life in its mildest forms. Bone alterations that lead to a restrictive respiratory pattern, recurrent respiratory infections and particular phenotype, can make perioperative anesthetic management difficult. The proper assessment of the airway is of special interest because it presents predictors of a difficult airway, as well as the prevention, early diagnosis and adequate treatment of respiratory failure. We present the case of a patient with Jarcho-Levin Syndrome who underwent vertebral distraction surgery, with its most notable implications in anesthetic management.

[Intense icterus in the course of EBV infectious mononucleosis]. / Intensa ictericia en el curso de una mononucleosis infecciosa por EBV.

Infectious mononucleosis induced by the Epstein Barr Virus (EBV) is a benign illness that is frequently accompanied by a slight hepatic disfunction. On occasion it may be accompanied by autoimmune hemolytic anemia of little clinical importance. Nevertheless, this association can cause a serious set of symptoms that can put the patient's life in danger if it is not treated quickly. We present the case of a 21-year-old male with infectious mononucleosis and severe jaundice (total bilirubin 40 mg/dl) due to the combination of diseased liver and secondary autoimmune hemolytic anemia, caused by the EBV infection.

A six-year experience with anal cytology in women with HPV in the lower genital tract: utility, limitations, and clinical correlation.

This study assessed the utility and limitations of anal cytology as a screening method for women infected with human papilloma virus (HPV) in the lower genital tract. Furthermore, this study aimed to establish risk factors for pathological anal cytology/biopsy findings, the prevalence of anatomopathological lesions associated with positive anal brushings, and the frequency of concomitant lesions of the lower genital tract. A cross-sectional, retrospective, descriptive study in 207 women with HPV-associated lesions of the lower genital tract and 25 women with immunosuppression was carried out. Anal cytology, high resolution anoscopy, and biopsy of suspicious lesions were performed. In total, 232 anal brushings were performed: 184 (79.3%) were negative, 24 (10.34%) showed atypical squamous cells of undeterminated significance, 18 (7.7%) showed low-grade squamous intraepithelial lesions, and 6 (2.6%) showed high-grade squamous intraepithelial lesion. Cytohistological correlation was obtained for 70 cases. The sensitivity of anal cytology in detecting intraepithelial lesions was 70%, whereas the specificity was 93%. The sensitivity of the method for detecting high-grade lesions (84%) was higher, than that for detecting low-grade lesions (66%). The most frequently associated pathology was vulvar lesion. It is important to perform anal brushings in women who have had lower genital tract biopsies for HPV-associated lesions due to the high prevalence of anal lesions in such patients. Anal cytology is useful for detecting high-grade lesions but the sensitivity for detecting low-grade lesions is low. It is of the utmost importance to perform high-resolution anoscopy and biopsy in women with suspicious lesions in order to confirm the pathology.

Electrically induced release of amino acids formed from (U14C) glucose in rat brain cortex slices, studied by a simplified dansylation procedure.

The nonessential amino acids glutamate, aspartate, glutamine, gamma-aminobutyrate (GABA), alanine, glycine, and proline present in rat thin brain cortex slices were labeled by in vitro incubation of these with [U-14C]glucose, and the efflux of such endogenous radioactive amino acids and of lactate was studied in a superfused system, under control conditions or when the slices were depolarized by varous procedures. When electrical stimuli known to induce selective neurotransmitter release (1 or 1.5 volt, sine wave 60 Hz) were applied for 10 sec to the slices, no significant increase in amino acid efflux was found. When more intense stimuli (4 volt, 60 Hz) were applied for 60 sec, or extracellular potassium was raised to 56 mM, both conditions being known to induce nonselective substance release, the efflux of essentially all amino acids and of lactate was markedly increased. Increases in efflux were proportionately larger for glutamate, aspartate, and gamma-aminobutyrate, and this could be accounted for by their greater intracellular chemical (or electrochemical) potentials, but not because of a selective release mechanism for them. Amino acids were analyzed as their 1-dimethylaminoaphthalene-5-sulfonyl (dansyl) derivatives, by a modification of existing procedures in which the dansyl (DNS) derivatives were efficiently extracted from acidified incubation fluid into an organic phase. This rapidly desalted the derivatives and allowed their concentration and chromatographic separation on thin-layer silica gel sheets with little loss.

Polymeric membranes for hybrid liver support devices: the effect of membrane surface wettability on hepatocyte viability and functions.

Extracorporeal therapies based on membrane hybrid liver support devices using primary hepatocytes are an interesting approach to the treatment of acute hepatic failure. In such devices, semipermeable polymeric membranes are effectively used as immunoselective barriers between a patient's blood and the xenocytes in order to prevent the immune rejection of the graft. The membranes may act also as the substratum for cell adhesion, thus favouring the viability and functions of anchorage-dependent cells such as the hepatocytes. Membrane cytocompatibility is expected to depend on the surface properties of the polymer, such as its morphology and its physico-chemical properties. In this paper, we report our investigation on the effect of the surface wettability of membranes on hepatocyte viability and functions. Polypropylene microporous membranes were modified to increase their surface wettability and were used as substrata for rat hepatocyte adhesion culture. Isolated hepatocytes were also cultured on collagen as a reference substratum. Hepatocyte viability generally improved as the cells were cultured on more wettable membranes. In agreement with the viability data, the increasing wettability of the membrane surface also improved some metabolic functions.