Effect of adhesive system type and tooth region on the bond strength to dentin

Purpose: This study evaluated the bond strength of two etch-and-rinse adhesive systems (two- and three-step) and a self-etching system to Coronal and root canal dentin.Materials and Methods: The root canals of 30 human incisors and canines were instrumented and prepared with burs. The posts used for luting were duplicated with dual resin cement (Duo-link) inside Aestheti Plus #2 molds. Thus, three groups were formed (n = 10) according to the adhesive system employed: All-Bond 2 (TE3) + resin cement post (rcp) + Duo-link (DI); One-Step Plus (TE2) + rcp + DI; Tyrian/One-Step Plus (SE) + rcp + DI. Afterwards, 8 transverse sections (1.5 mm) were cut from 4 mm above the CEJ up to 4 mm short of the root canal apex, comprising coronal and root canal dentin. The sections were submitted to push-out testing in a universal testing machine EMIC (1 mm/min). Bond strength data were analyzed with two-way repeated measures ANOVA and Tukey's test (p < 0.05).Results: The relationship between the adhesives was not the same in the different regions (p < 0.05). Comparison of the means achieved with the adhesives in each region (Tukey; p < 0.05) revealed that TE3 (mean standard deviation: 5.22 +/- 1.70) was higher than TE2 (2.60 +/- 1.74) and SE (1.68 +/- 1.85).Conclusion: Under the experimental conditions, better bonding to dentin was achieved using the three-step etch-and-rinse system, especially in the coronal region. Therefore, the traditional etch-and-rinse three-step adhesive system seems to be the best choice for teeth needing adhesive endodontic restorations.

Surface degradation of glass ceramics after exposure to acidulated phosphate fluoride

Objective: This study evaluated the surface degradation effect of acidulated phosphate fluoride (APF) gel exposure on the glassy matrix ceramics as a function of time. Material and methods: Disc-shaped ceramic specimens (N = 120, 10/per ceramic material) were prepared in stainless steel molds (inner diameter: 5 mm, height: 2 mm) using 6 dental ceramics: 3 indicated for ceramic-fused-to-metal (Vita Omega 900, Carmen and Vita Titankeramik), 2 for all-ceramic (Vitadur Alpha and Finesse (R) Low Fusing) and 1 for both types of restorations (IPS d. SIGN). The specimens were wet ground finished, ultrasonically cleaned and auto-glazed. All specimens were subjected to calculation of percentage of mass loss, surface roughness analysis and topographical description by scanning electron microscopy (SEM) before (0 min) and after exposure to 1.23 % APF gel for 4 min and 60 min representing short-and long-term etching effect, respectively. The data were analyzed using two-way ANOVA with repeated measures and Tukey` s test (alpha=0.05). Results: Significant effect of the type of the ceramics (p=0.0000, p=0.0031) and exposure time (p=0.0000) was observed in both surface roughness and percentage of mass loss values, respectively. The interaction factor between both parameters was also significant for both parameters (p=0.0904, p=0.0258). Both 4 min (0.44 +/- 0.1-0.81 +/- 0.2 mu m) and 60 min (0.66 +/- 0.1 - 1.04 +/- 0.3 mu m) APF gel exposure created significantly more surface roughness for all groups when compared to the control groups (0.33 +/- 0.2-0.68 +/- 0.2 mu m) (p<0.05). There were no significant differences in percentage of mass loss between the ceramics at 4 min (p>0.05) but at 60 min exposure, IPS d. SIGN showed the highest percentage of mass loss (0.1151 +/- 0.11). The mean surface roughness for Vita Titankeramik (0.84 +/- 0.2 mu m) and Finesse (R) Low Fusing (0.74.+/- 0.2 mu m) was significantly higher than those of the other ceramics (0.59 +/- 0.1 mu m - 0.49 +/- 0.1 mu m) and Vita Titankeramik (p<0.05) regardless of the exposure time. A positive correlation was found between surface roughness and percentage of mass loss for all ceramic materials [(r=0.518 (Vitadur Alpha), r=0.405 (Vita Omega 900), r=0.580 (Carmen), r=0.687 (IPS d. SIGN), r=0.442 (Finesse (R) Low Fusing), r=0.572 (Vita Titankeramik), Pearson's correlation coefficient)]. The qualitative SEM analysis showed evidence of corrosive attack on all of ceramics at varying degrees. Conclusions: The ceramics indicated for either metal-ceramic or all-ceramic restorations were all vulnerable to surface texture changes and mass loss after short-term and long-term APF gel exposure.

The adhesive system and root canal region do not influence the degree of conversion of dual resin cement

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

Effect of Caries Infiltration Technique and Fluoride Therapy on Microhardness of Enamel Carious Lesions

Enamel white spot subsurface lesions compromise esthetics and precede cavitation; therefore, they must be halted. The aim of this study was to evaluate the effect of a caries infiltration technique and fluoride therapy on the microhardness of enamel carious lesions. Subsurface carious lesions were produced in 60 bovine specimens with polished enamel surfaces. The specimens were divided into four groups (n=15), according to the treatment used: CON, control immersion in artificial saliva; DF, daily 0.05% fluoride solution; WF, weekly 2% fluoride gel; and IC, resin infiltration (Icon). The specimens were kept in artificial saliva and evaluated for microhardness at five points: baseline, after caries production, after four and eight weeks of treatment, and a final evaluation after being submitted to a new acid challenge. The repeated-measures analysis of variance showed significant differences according to the type of treatment (TREAT; p=0.001) and time of evaluation (EV; p=0.001). The results of the Tukey test were TREAT: CON = 45.18 (+/- 29.17)a, DF = 107.75 (+/- 67.38)b, WF = 83.25 (+/- 51.17)c, and IC = 160.83 (+/- 91.11)d. Analysis of correlation between the TREAT and EV factors showed no significant differences for DF (138.63 +/- 38.94) and IC (160.99 +/- 46.13) after the new acid challenge. The microhardness results in decreasing order after eight weeks were IC > DF > WF > CON. It was concluded that the microhardness of carious lesions increased with the infiltration of resin, while the final microhardness after a new acid challenge was similar for DF and IC.

Efeitos agudos do tabagismo sobre a modulação autonômica: análise por meio do plot de poincaré

FUNDAMENTO: O tabagismo altera a função autonômica. OBJETIVO: Investigar os efeitos agudos do tabagismo sobre a modulação autonômica e a recuperação dos índices de variabilidade de frequência cardíaca (VFC) pós-fumo, por meio do plot de Poincaré e índices lineares. MÉTODOS: Foram avaliados 25 fumantes jovens, os quais tiveram a frequência cardíaca analisada, batimento a batimento, na posição sentada, após 8 horas de abstinência, por 30 minutos em repouso, 20 minutos durante o fumo e 30 minutos pós-fumo. Análise de variância para medidas repetidas, seguido do teste de Tukey, ou teste de Friedman seguido do teste de Dunn foram aplicados dependendo da normalidade dos dados, com p < 0,05. RESULTADOS: Durante o fumo, houve redução dos índices SD1 (23,4 ± 9,2 vs 13,8 ± 4,8), razão SD1/SD2 (0,31 ± 0,08 vs 0,2 ± 0,04), RMSSD (32,7 ± 13 vs 19,1 ± 6,8), SDNN (47,6 ± 14,8 vs 35,5 ± 8,4), HFnu (32,5 ± 11,6 vs 19 ± 8,1) e do intervalo RR (816,8 ± 89 vs 696,5 ± 76,3) em relação ao repouso, enquanto que aumentos do índice LFnu (67,5 ± 11,6 vs 81 ± 8,1) e da razão LF/HF (2,6 ± 1,7 vs 5,4 ± 3,1) foram observados. A análise visual do plot mostrou menor dispersão dos intervalos RR durante o fumo. Com exceção da razão SD1/SD2, os demais índices apresentaram recuperação dos valores, 30 minutos após o tabagismo. CONCLUSÃO: O tabagismo produziu agudamente modificações no controle autonômico, caracterizadas por ativação simpática e retirada vagal, com recuperação 30 minutos após o fumo.

Topical 1% Nalbuphine on corneal sensivity and epitheilization after experimental lamellar keratectomy in rabbits

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

Diurnal variation in oral temperature, sleepiness and performance of high school girls

Evaluation of rhythmic fluctuations cf physical and mental variables should be of special significance for the understanding of students' performance and setting the schedules of school activities. The present study investigated the pattern of diurnal variation in oral temperature, sleepiness and performance of a group of adolescents undergoing a daytime school schedule. Eighteen girls (mean age 16 years-old), who attended the same class from 0715h to 1645h, were tested on seven days. They measured their oral temperature, quantified their sleepiness level by means of a visual analogue scale, and completed the following tests: letter cancellation test, addition test, and a simple motor task. One-way ANOVA statistics for repeated measures was used in order to verify the effect of test time on oral temperature,sleepiness and performance. Possible correlations between the level of sleepiness and performance were investigated by means of Spearman rank correlation. The results revealed significant time of day effect cn all variables, except for the number of addition errors. Oral temperature values showed an increase from morning to afternoon. Letter cancellation, motor task and addition scores increased from early morning to late afternoon, showing rapid fluctuations throughout the day. Sleepiness level was negatively correlated with letter cancellation scores during the first three tests of the day. In agreement with other work, the diurnal variation of oral temperature, letter cancellation and addition test showed an improvement as the day progressed. Sleepiness, on the other hand, decreased throughout the day, with the highest level associated with the first test of the day, suggesting a circadian pattern of variation rather than a cumulative effect due to school activities.

The pre-emptive effect of epidural ketamine on wound sensitivity in horses tested by using von Frey filaments

Objective To evaluate the pre-emptive analgesic effect of pre-incisional epidural ketamine.Study Design A blinded, randomized experimental study.Animals Sixteen mixed breed mares, 17.6 +/- 2.8 years old, weighing 352 +/- 32 kg.Methods In a pilot study, an incision was made on one lateral thigh using a lidocaine block and no further analgesics, and it was verified that the nociceptive threshold was lower on the incised side than nonincised side (p < 0.05), and that von Frey filaments evoked a pain response. The 16 animals were divided into group A (ketamine, n = 9) and B (saline, n = 7). An epidural catheter was inserted 24 hours before the trials, the thigh was shaved bilaterally, and the right side was blocked (incised side) using lidocaine. Twenty-five minutes later, ketamine (A) or saline (B) was administered epidurally. Five minutes later, a 10-cm. skin incision was made on the right side, and then sutured. Nociceptive threshold was determined with von Frey filaments at 1, 3, and 5 cm. around the incision at 15-minute intervals for 2 hours, then at 4, 6, and 8 hours. Behavioral alterations, heart and respiratory rates were recorded. Nociceptive thresholds from these points were averaged to obtain mean values at each time, converted to a logarithmic scale, and submitted to a nonparametric analysis (Mann-Whitney and one-way repeated measures anova test,p less than or equal to 0.05).Results After 8 hours, the global range score revealed reduced hyperalgesia (p < 0.01) around the incision in 92% (4.65-4.27) of evaluated intervals in group A (ketamine). There were no significant changes in behavior, heart and respiratory rates,Conclusions It was concluded that pre-emptive epidural ketamine reduced post-incisional pain in the horse, and that von Frey filaments were able to quantify cutaneous sensitivity after tissue damage.Clinical relevance Epidural ketamine injection can reduce post-incisional sensitivity in the horse.

Polymerization shrinkage: effects of boundary conditions and filling technique of resin composite restorations

Objective: To evaluate the linear polymerization shrinkage (LPS) and the effect of polymerization shrinkage of a resin composite and resin-dentin bond strength under different boundary conditions and filling techniques.Methods: Two cavities (4 x 4 x 2 MM) were prepared in bovine incisors (n = 30). The teeth were divided into three groups, according to boundary conditions: In group TE, the total-etch technique was used. In group EE, only enamel was conditioned, and in group NE, none of the watts of the cavities were conditioned. A two-step adhesive system was applied to all cavities. The resin composite was inserted in one (B) or three increments (1), and tight-cured with 600 mW/cm(2) (80 s). The LPS (%) was measured in the top-bottom direction, by placing a probe in contact with resin composite during curing. Enamel and total mean gap widths were measured (400 x) in three slices obtained after sectioning the restorations. Then, the slices were sectioned again, either to obtain sticks from the adhesive interface from the bottom of the cavity or to obtain resin composite sticks (0.8 mm(2)) to be tested for tensile strength (Kratos machine, 0.5 mm/min). The data was subjected to a two-way repeated measures ANOVA and Tukey's test for comparison of the means (alpha = 0.05).Results: the highest percentage of LPS was found for the TE when bulk fitted, and the lowest percentage of LPS was found in the Hand NE when incrementally fitted. The resin dentin bond strength was higher and the total mean gap width was tower for TE group; no significant effect was detected for the main factor fitting techniques. No difference was detected for the tensile strength of resin composite among the experimental groups.Conclusions: the filling technique is not able to minimize effects of the polymerization shrinkage, and bonding to the cavity watts is necessary to assure reduced mean gap width and high bond strength values. (C) 2004 Elsevier Ltd. All rights reserved.

Comparison of accuracy between compression- and injection-molded complete dentures

Statement of problem. A clinically significant incisal pin opening may occur after processing complete dentures if a compression molding technique is used. To recover the proper vertical dimension of occlusion, a time-consuming occlusal adjustment is necessary that often destroys the anatomy of the artificial teeth. A new injection molding process claims to produce dentures that require few, if any, occlusal adjustments in the laboratory after processing.Purpose. This laboratory study compared incisal pin opening, dimensional accuracy, and laboratory working time for dentures fabricated by this new injection system with dentures constructed by the conventional compression molding technique.Material and methods. Two groups of 6 maxillary and 6 mandibular dentures were evaluated as follows: group 1 (control), Lucitone 199, compression molded with a long cure cycle; and group 2, Lucitone 199, injection molded with a long cure. Incisal pin opening was measured with a micrometer immediately after deflasking. A computerized coordinate measuring machine was used to measure dimensional accuracy of 3-dimensional variations in selected positions of artificial teeth in 4 stages of denture fabrication. Analysis of variance (ANOVA) and t tests were performed to compare the groups.Results. A significant difference was found in pin opening between groups (t test). Horizontal dimensional changes evaluated with repeated measures ANOVA revealed no significant differences between groups. However, analysis of vertical dimensional changes disclosed significant differences between the groups. There was no appreciable difference in laboratory working time for flasking and molding denture bases between the injection and compression molding techniques when polymethyl methacrylate resin was used.Conclusion. The injection molding method produced a significantly smaller incisal pin opening over the standard compression molding technique. The injection molding technique, using polymethyl methacrylate, was a more accurate method for processing dentures. There were no appreciable differences in laboratory working time between the injection and compression molding techniques.

Growth, carcass and meat quality traits of straightbred and crossbred Botucatu rabbits

The objective was to evaluate the effects of genetic group and age on growth, carcass, and meat traits of rabbits. A total of 144 straightbred Botucatu and White German Giant x Botucatu crossbred rabbits were involved. Rabbits were weaned at 35 d and sequentially, slaughtered, four per genetic group x sex combination, at: 42, 49, 56, 63, 70, 77, 84 and 91 d. A 2x2 factorial arrangement was employed in a completely randomized design with repeated measures for growth traits, and a split-plot for carcass and meat traits. Crossbred rabbits were heavier (2032 vs. 1962 g; P < 0.01), consumed more feed (143.5 vs. 131.0 g/d; P < 0.01), and presented higher slaughter weight (2169 vs. 2093 g, P=0.02) and dressing percentage (59.0 vs. 58.2%; P=0.07) than straightbreds throughout the experiment. No difference between genetic groups was detected for feed conversion and empty gastrointestinal weight corrected for slaughter weight (SW). Crossbreds showed higher skin weight (308.2 vs. 299.7 g, P = 0.06) and distal parts of leg weight (75.7 vs. 71.4 g; P < 0.01), both corrected for SW. No genetic group effect was detected on dissectible fat and hind part weights. Chilled commercial carcass (1284 vs. 1229 g: P=0.02), chilled reference carcass (1036 vs. 1000 g, P=0.06), fore part (297.9 vs. 283.3 g; P=0.01) and loin (308.7 vs. 295.5 g; P=0.05) were heavier in crossbreds than in straightbreds, but these differences were attributed to differences in SW. Uncorrected weights of head, kidneys, liver and thoracic viscera were higher in the crossbred group, but only head (116.6 vs. 113.6 g; P=0.06) and thoracic viscera (30.4 vs. 28.6 g; P=0.01) were, in fact, proportionately heavier in crossbreds than in straightbreds. No effect of genetic group was detected on meat to bone ratio, muscle ultimate pH and chemical composition of the Longissimus dorsi muscle. All traits, except for ash and fat contents of the Longissimus muscle, showed age effects (P < 0.01). Crossbreeding may be recommended for the production of whole commercial carcasses, but it is not clearly advantageous for the production of retail cuts. Slaughter should take place between 63 and 70 d of age for both genetic groups.

The influence of study schedules and work on the sleep-wake cycle of college students

College students usually exhibit an irregular sleep-wake cycle characterized by great phase delays on weekends and short sleep length on weekdays. As the temporal organization of social activities is an important synchronizer of human biological rhythms, we investigated the role played by study's schedules and work on the sleep-wake cycle. Three groups of female college students were investigated: (1) no-job morning group, (2) no-job evening group, (3) job evening group. The volunteers answered a sleep questionnaire in the classroom. The effects of day of the week and group on the sleep schedules and sleep length were analyzed by a two way ANOVA for repeated measures. The three groups showed delays in the wake up time on weekends. No-job evening and morning groups also delayed bedtime, but the job evening group slept at the same time on weekdays as on weekends. Sleep length increased on weekends for morning group and job evening group, whereas the no-job evening group maintained the amount of sleep from weekdays to weekends. This survey showed that the tendency of phase delay on weekends was differently expressed according to study's schedules and work.

Evaluation of intraocular pressure in association with cardiovascular parameters in normocapnic dogs anesthetized with sevoflurane and desflurane

The objective of this study was to determine intraocular pressure (IOP) and cardiac changes in normocapnic dogs maintained under controlled ventilation and anesthetized using sevoflurane or desflurane. Sixteen healthy adult mixed-breed dogs, seven males and nine females, weighing 10-15 kg were used. The dogs were randomly assigned to one of two groups composed of eight animals anesthetized with sevoflurane (SEVO) or desflurane (DESF). In both groups, anesthesia was induced with propofol (10 mg/kg), and neuromuscular blockade was achieved with rocuronium (0.6 mg/kg/h IV). No premedication was given. Ventilation was adjusted to maintain end-tidal carbon dioxide partial pressure at 35 mmHg. Anesthesia was maintained with 1.5 minimum alveolar concentration (MAC) of sevoflurane or desflurane. In both groups IOP was measured by applanation tonometry (Tono-Pen) before induction of anesthesia. IOP, mean arterial pressure (MAP), heart rate (HR), cardiac index (CI) and central venous pressure (CVP) were also measured 45 min after the beginning of inhalant anesthesia and then every 20 min for 60 min. A one-way repeated measures ANOVA was used to compare data within the same group and Student's t-test was used to assess differences between groups. P < 0.05 was considered statistically significant. Measurements showed normal IOP values in both groups, even though IOP increased significantly from baseline during the use of desflurane. IOP did not differ between groups. CI in the desflurane group was significantly greater than in the sevoflurane group. Sevoflurane and desflurane have no clinically significant effects on IOP, MAP, HR, CI or VCP in the dog.

Assessment of brachial plexus blockade in chickens by an axillary approach

Objective To assess the brachial plexus block in chickens by an axillary approach and using a peripheral nerve stimulator.Study design Prospective, randomized, double-blinded study.Animals Six, 84-week old, female chickens.Methods Midazolam (1 mg kg(-1)) and butorphanol (1 mg kg(-1)) were administered into the pectoralis muscle. Fifteen minutes later, the birds were positioned in lateral recumbency and following palpation of the anatomic landmarks, a catheter was inserted using an axillary approach to the brachial plexus. Lidocaine or bupivacaine (1 mL kg(-1)) was injected after plexus localization by the nerve stimulator. Sensory function was tested before and after blockade (carpus, radius/ulna, humerus and pectoralis muscle) in the blocked and unblocked wings. The latency to onset of motor and sensory block and the duration of sensory block were recorded. A Friedman nonparametric one-way repeated-measures ANOVA was used to compare scores from baseline values over time and to compare the differences between wings at each time point.Results A total of 18 blocks were performed with a success rate of 66.6% (12/18). The latency for motor block was 2.8 +/- 1.1 and 3.2 +/- 0.4 minutes for lidocaine and bupivacaine, respectively. The latencies for and durations of the sensory block were 6.0 +/- 2.5 and 64.0 +/- 18.0 and 7.8 +/- 5.8 and 91.6 +/- 61.7 minutes for lidocaine and bupivacaine, respectively. There was no statistical difference between these times for lidocaine or bupivacaine. Sensory function was not abolished in nonblocked wings.Conclusions and clinical relevance The brachial plexus block was an easy technique to perform but had a high failure rate. It might be useful for providing anesthesia or postoperative analgesia of the wing in chickens and exotic avian species that have similar wing anatomy.

Muscle Activation During Four Pilates Core Stability Exercises in Quadruped Position

Queiroz BC, Cagliari MF, Amorim CF, Sacco IC. Muscle activation during four Pilates core stability exercises in quadruped position. Arch Phys Med Rehabil 2010;91: 86-92.Objective: To compare the activity of stabilizing trunk and hip muscles in 4 variations of Pilates stabilizing exercises in the quadruped position.Design: Repeated-measures descriptive study.Setting: A biomechanics laboratory at a university school of medicine.Participants: Healthy subjects (N=19; mean age +/- SD, 31 +/- 5y; mean weight +/- SD, 60 +/- 11 kg; mean height +/- SD, 166 +/- 9cm) experienced in Pilates routines.Interventions: Surface electromyographic signals of iliocostalis, multifidus, gluteus maximus, rectus abdominis, and external and internal oblique muscles were recorded in 4 knee stretch exercises: retroverted pelvis with flexed trunk; anteverted pelvis with extended trunk; neutral pelvis with inclined trunk; and neutral pelvis with trunk parallel to the ground.Main Outcome Measures: Root mean square values of each muscle and exercise in both phases of hip extension and flexion, normalized by the maximal voluntary isometric contraction.Results: The retroverted pelvis with flexed trunk position led to significantly increased external oblique and gluteus maximus muscle activation. The anteverted pelvis with trunk extension significantly increased multifidus muscle activity. The neutral pelvis position led to significantly lower activity of all muscles. Rectus abdominis muscle activation to maintain body posture was similar in all exercises and was not influenced by position of the pelvis and trunk.Conclusions: Variations in the pelvic and trunk positions in the knee stretch exercises change the activation pattern of the multifidus, gluteus maximus, rectus abdominis, and oblique muscles. The lower level of activation of the rectus abdominis muscle suggests that pelvic stability is maintained in the 4 exercise positions.