Effect of Simulated Annual At-home Bleaching on Susceptibility to Staining, Translucency, and Whiteness Variations of Computer-aided Design and Computer-aided Manufacturing Monolithic Materials.

The effect of annual at-home bleaching on the color, translucency, and whiteness properties of computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic materials requires investigation. The aim of the present in vitro study was to evaluate the effect of simulated annual at-home bleaching (consisting of daily applications for 10 hours a day for 14 days), for up to 3 years, on susceptibility to staining (ΔE00), translucency (ΔTP00), and whiteness (ΔWID) variations and on topography of CAD-CAM monolithic materials. Disks from the Lava Ultimate (LU), Vita Enamic (VE), IPS Empress CAD (EMP), and IPS e.max CAD (EMAX) were allocated as follows: 1) nonbleached or 2) bleached with 10% carbamide peroxide. After reading the CIE L*a*b* coordinates at baseline (R0), specimens were bleached or not and subsequently immersed for a 1-year simulated period in coffee before the next reading (R1). This process was repeated two more times, resulting in R2 and R3. The ΔE00, ΔTP00, and ΔWID between R1, R2, and R3 in relation to R0 were calculated. The surface topography was analyzed by scanning electron microscopy. In general, bleaching increased the staining susceptibility of all materials when compared to the nonbleached groups and that of the LU, VE, and EMAX over the years. Bleaching decreased the translucency of the VE in all years and over the years. When compared to the nonbleached groups, bleaching decreased the whiteness of the LU and EMAX and increased the whiteness of the EMP, while the VE was not affected. In the LU, the whiteness decreased over the years in both treatments, whereas the other materials were not affected with time. All materials showed progressive topographic changes over the years. The simulated annual at-home bleaching with 10% carbamide peroxide adversely affected the topography and the optical and/or colorimetric properties of the evaluated materials.

Effect of Successive In-office Bleaching Sessions on the Surface Properties, Substance Loss, Biaxial Flexural Strength, and Reliability of CAD-CAM Monolithic Materials.

Little is known about the effects of in-office bleaching on the surface properties and on other aspects of CAD-CAM monolithic materials, especially when successive bleaching sessions are conducted. This study evaluated the effect of up to three successive in-office bleaching sessions on the microhardness, roughness, topography, substance loss, biaxial flexural strength (BFS), and reliability of CAD-CAM monolithic materials. Disks from Lava Ultimate (LU), Vita Enamic (VE), and IPS Empress CAD (EMP) were fabricated and submitted to one, two, and three bleaching sessions. In-office bleaching was performed with 40% hydrogen peroxide and each session consisted of three applications of 20 minutes each. The analyses regarding the aforementioned parameters were assessed before and after the first, second, and third bleaching sessions, except for BFS, which was evaluated at the baseline and after the third session. Weibull modulus was calculated from the BFS data. Bleaching decreased the microhardness of LU and VE from the third and second sessions, respectively, and affected neither the roughness nor the BFS of the three materials. However, in LU, it decreased the reliability and caused topographic changes, which were accentuated by the increase in the number of sessions. In general, LU and EMP showed, respectively, the highest and the lowest substance losses. Successive in-office bleaching sessions with the use of the protocol of the present study should be avoided in LU and VE.

Effect of In-office Bleaching on Color, Translucency, and Whiteness Variations in CAD-CAM Monolithic Materials.

Little is known about the impact of bleaching on the optical properties of computer-aided design and computer-aided manufactured (CAD-CAM) monolithic materials. The aim of the present study was to evaluate the effect of one session of in-office bleaching on stain removal, staining susceptibility, translucency, and whiteness variations of CAD-CAM monolithic materials. Disks were fabricated from Lava Ultimate (LU), Vita Enamic (VE), Vita Suprinity (VS), and IPS e.max CAD (IPS). A spectrophotometer was used to register Commission Internationale de l'Eclairage L*a*b* coordinates. For stain removal, 80 specimens from each material were assessed at baseline (R0) and after immersion in deionized water or coffee for 36.5 days followed or not by bleaching with 40% hydrogen peroxide (R1). For staining susceptibility, 80 specimens from each material were analyzed at baseline (R0'), and after having been bleached or not and immersed in deionized water or coffee (R1'). Both analyses were calculated as the color difference (ΔE00) between R1-R0 and R1'-R0', respectively. Differences in translucency (ΔTP00) and whiteness (ΔWID) between R1-R0 and R1'-R0' were also calculated. Data were analyzed by three-way ANOVA and the Games-Howell post hoc test (α=0.05). Clinical significance was based on 50%:50% perceptibility and acceptability thresholds for ΔE00, ΔTP00 and ΔWID, respectively. Surfaces were analyzed by scanning electron microscopy. Coffee increased ΔE00 in LU, VE, and VS, and decreased their translucency and whiteness, whereas the IPS had only its whiteness affected. Bleaching after immersion in coffee decreased ΔE00 in LU and VE, and increased translucency and whiteness of LU, VE, and VS. No effect was observed on IPS. Bleaching before immersion in coffee decreased translucency of LU, but within the acceptable interval, while VE exhibited lower ΔE00, and became more translucent and less dark. Both VS and IPS were not affected. One session of in-office bleaching benefited optical properties of the previously stained LU, VE, and VS, without increasing their susceptibility to staining or adversely providing clinically unacceptable variations in their translucency and whiteness. All variations exhibited by the IPS were below the perceptible threshold.

Air abrasion before and/or after zirconia sintering: surface characterization, flexural strength, and resin cement bond strength.

The purpose of this in vitro study was to evaluate the effect of air-abrasion/zirconia sintering order on the yttria partially stabilized tetragonal zirconia polycrystal (Y-TZP) surface characterization (roughness, morphology, and phase transformation), flexural strength (FS), and shear bond strength (SBS) to a resin cement. Y-TZP specimens were air abraded with 50-µm Al2O3 particles after (AS), before (BS), or before and after zirconia sintering (BAS). For roughness (Ra), 30 block specimens (12×12×3.0 mm; n=10) had their surfaces analyzed by a profilometer. Next, on the air-abraded surfaces of these specimens, composite resin discs (n=30) were bonded with RelyX ARC. The bonded specimens were stored for 24 hours in distilled water at 37°C before shear testing. Failure mode was determined with a stereomicroscope (20×). The surface morphology (n=2) was evaluated by SEM (500×). For the four-point flexural strength test (EMIC DL2000), 39 bar-shaped specimens (20×4.0×1.2 mm; n=13) were air abraded according to the three conditions proposed, and an additional group (nonabraded) was evaluated (n=13). The quantitative analysis of phase transformation (n=1) was completed with Rietveld refinement with X-ray diffraction data. Ra (µm) and SBS (MPa) data were analyzed by one-way analysis of variance (ANOVA) and the Tukey test (α=0.05). Pearson correlation analysis was used to determine if there was a correlation between roughness and SBS. For FS (MPa) data, one-way ANOVA and the Dunnett C-test (α=0.05) were used. The air-abrasion/zirconia sintering order influenced significantly (p<0.001) Ra, SBS, and FS. The BS and AS groups presented the highest (1.3 µm) and the lowest (0.7 µm) Ra. The highest SBS (7.0 MPa) was exhibited by the BAS group, followed by the AS group (5.4 MPa) and finally by the BS group (2.6 MPa). All groups presented 100% adhesive failure. A weak correlation (r=-0.45, p<0.05) was found between roughness and SBS. The air-abrasion/zirconia sintering order provided differences in the surface morphology. The nonabraded (926.8 MPa) and BS (816.3 MPa) groups exhibited statistically similar FS values but lower values than the AS (1249.1 MPa) and BAS (1181.4 MPa) groups, with no significant difference between them. The nonabraded, AS, BS, and BAS groups exhibited, respectively, percentages of monoclinic phase of 0.0 wt%, 12.2 wt%, 0.0 wt%, and 8.6 wt%. The rougher surface provided by the air-abrasion before zirconia sintering may have impaired the bonding with the resin cement. The morphological patterns were consistent with the surface roughness. Considering the short-term SBS and FS, the BAS group exhibited the best performance. Air abrasion, regardless of its performance order, provides tetragonal to monoclinic transformation, while sintering tends to zero the monoclinic phase content.

The relationship between body composition, training and race performance in a group of Thoroughbred flat racehorses.

REASONS FOR PERFORMING STUDY: Few noninvasive measures associated with performance assessment are available for racehorse trainers. Evaluation of body composition of superior human sprinters has revealed a lower fat mass (FM), percentage (%) fat and greater fat-free mass (FFM), but to date there have been few studies evaluating this in racehorses. OBJECTIVES: To determine the effects of age, gender and training on body composition and the relationship between body composition, physiological measurements and performance in Thoroughbred racehorses. METHODS: At 2, 5 and 8 months of training, rump fat thickness (RFT) was ultrasonographically measured in 1-, 2- and 3-year-old Thoroughbreds (n = 148), with FM, % fat and FFM calculated. Speed, heart rate, plasma lactate and serum creatine kinase concentrations were recorded during each fast work session. Training duration (number of training days) and intensity (number of fast work sessions) were collated for each training period. Retrospective racing performance was used to categorise horses as elite or nonelite. RESULTS: FFM was greater in males (P = 0.006) at all training stages. There were no interactions between training duration, intensity, gender and age (P>0.05); all effects were linear. Training duration had a negative effect on RFT (P = 0.0002), FM (P<0.0001) and % fat (P<0.0001) and a positive effect on FFM (P = 0.01). Training intensity had a negative effect on RFT (P = 0.009), FM (P<0.0001), % fat (P<0.0001) and FFM (P<0.0001). FFM was greater for elite vs. nonelite horses at all training stages (P = 0.003), for males (P = 0.05) and females (P = 0.04) and for 2- (P = 0.002) and 3-year-olds (P = 0.02). CONCLUSIONS: While age and training affect body composition, FFM is associated with performance. POTENTIAL RELEVANCE: Body composition assessment may assist fitness and performance evaluation.

The association of various speed indices to training responses in Thoroughbred flat racehorses measured with a global positioning and heart rate monitoring system.

REASONS FOR PERFORMING STUDY: Fitness assessment can be challenging. The use of global positioning systems (GPS) with heart rate (HR) monitors has been promising; however, evaluation of speed parameters during training has not been reported. OBJECTIVES: To evaluate speed indices during training in Thoroughbreds using a GPS-HR monitor. METHODS: Thoroughbreds (n = 102) were assessed during training with data collected each work day (WD; sprinting). Speed indices evaluated included maximal velocity (V(max)), duration at V(max) (V(maxt)), acceleration rate (m/s(2)) from 800 m to V(max) (Acc800-V(max)), the distance (m) 6 (V(maxD6)) and 12 (V(maxD12)) s before (acceleration [a]) and after (deceleration [d]) V(max) and the deceleration rate from V(max) to the finish (V(maxDFd)). Blood for plasma lactate ([LA]) and creatine kinase ([CK]) measurements were taken before (T(0)), 5 mins (T(1)) and 6 h after exercise (T(2)). WD accumulation, jockey, gallop condition, horse gender, age, total distance covered (DistT), maximum HR (HR(max)), velocity at 200 beats/min (V(200)) and velocity at maximum HR (VHR(max)) for each WD were evaluated for associations with [LA], [CK], speed indices and racing performance. Data were analysed by repeated measures ANOVA with P < 0.05 significant. RESULTS: No speed parameter clearly changed with training. Gallop condition affected V(max), V(maxt) and all distances covered with V(max) and distances increasing and V(maxt) decreasing as gallop surface became firmer. Jockey influenced V(max), V(maxD6a) and all decelerations, while DistT was inversely associated with Acc800-V(max), HR(max) and V(200) and positively associated with V(max), all accelerations and decelerations. [LA] at T(1) was positively associated with DistT and V(maxDFd). CONCLUSIONS: Speed parameters did not change with training but were affected by jockey, gallop condition and exercise distance. This information may help to modify training to maximise fitness, minimise injury and choose distances best suited for individuals.

Moderate and high intensity sprint exercise induce differential responses in COX4I2 and PDK4 gene expression in Thoroughbred horse skeletal muscle.

REASONS FOR PERFORMING STUDY: The role of molecular signalling pathways in the phenotypic adaptation of skeletal muscle to different exercise stimuli in the Thoroughbred horse has not been reported previously. OBJECTIVE: To examine CKM, COX4I1, COX4I2 and PDK4 gene expression following high intensity sprint and moderate intensity treadmill exercise stimuli in skeletal muscle of Thoroughbred horses. MATERIALS AND METHODS: Two groups of trained 3-year-old Thoroughbred horses participated. Group A (n = 6 females, n = 3 males) participated in an incremental step test (moderate intensity) to fatigue or HR(max) on a Sato high speed treadmill (distance = 5418.67 m ± 343.21). Group B (n = 8 females) participated in routine 'work' (sprint) on an all-weather gallop (distance = 812.83 m ± 12.53). Biopsy samples were obtained from the gluteus medius pre-exercise (T(0)), immediately post exercise (T(1)) and 4 h post exercise (T(2)). For physiological relevance venous blood samples were collected to measure plasma lactate and creatine kinase concentrations. Changes in mRNA expression were determined by quantitative real-time RT-PCR for creatine kinase muscle (CKM), cytochrome c oxidase subunit IV isoform 1 (COX4I1), cytochrome c oxidase subunit IV isoform 2 (COX4I2) and pyruvate dehydrogenase kinase, isozyme 4 (PDK4) genes. Statistical significance (α < 0.05) was determined using Student's t tests. RESULTS: COX4I2 mRNA expression decreased significantly in Group A and remained unchanged in Group B between T(0) vs. T(2) (-1.7-fold, P = 0.017; -1.0-fold, P = 0.859). PDK4 mRNA expression increased significantly in Group B but not in Group A between T(0) vs. T(1) (3.8-fold, P = 0.039; 1.4-fold, P = 0.591). There were no significant changes in the expression in CKM or COX4I1 mRNA abundance in either group. CONCLUSIONS: Different exercise protocols elicit variable transcriptional responses in key exercise relevant genes in equine skeletal muscle due to variation in metabolic demand.

Comparison of the effects of barbiturate, benzodiazepine and ketamine on visual evoked potentials in rabbits.

The aim of this study was to compare the effects of barbiturate, benzodiazepine and ketamine on flash-evoked potentials (F-VEP) in adult rabbits. A total of 36 animals were studied, 16 after pentobarbital endovenous (EV) infusion, 10 after midazolam EV administration, and 10 after ketamine EV infusion. Pentobarbital induced triphasic F-VEP, first negative (N1), second positive (P1), third negative (N2) waves, all with large amplitudes and P1 with well-defined morphology. Mean P1 latency was 33ms. Midazolam induced similar but less defined triphasic waves, with mean latency of 27ms. Ketamine induced poliphasic and poorly defined F-VEP, with mean first positive (P1) latency of 27ms. Statistical analysis showed more elongated latency for the pentobarbital group than the midazolam and ketamine groups. The results of this study suggest that the pharmacological effects of pentobarbital and midazolam on GABA neurotransmission in rabbit visual cortex may be different; another neurotransmission system, possibly cholinergic, may be involved. The ketamine effect seen in rabbit visual cortex seems to be different from pentobarbital and midazolam.

Intercostal nerve mononeuropathy: study of 14 cases

This retrospective study describes 14 cases of intercostal nerve mononeuropathy (INM) found in 5,560 electromyography (EMG) exams performed between January 1991 and June 2004 in our University Hospital. Medical charts of all patients with history of thoracic pain and EMG diagnosis of intercostal mononeuropathy were reviewed. INM was detected in 14 patients; etiology was thoracic surgery in 6 (43%), post-herpetic neuropathy in 4 (28%), probable intercostal neuritis in 2 (14%), lung neoplasia in 1 (7%), and radiculopathy in 1 (7%). From this study, trauma and infection were the main etiologies in intercostal neuropathic pain development. Tricyclic antidepressants and anticonvulsants were the most common therapeutic drugs used.

Este trabalho apresenta estudo retrospectivo de 14 pacientes com mononeuropatia de nervo intercostal (MNI), obtidos dentre 5.560 exames eletromiográficos, realizados de janeiro de 1991 até junho de 2004, em nosso Hospital Universitário. MNI foi encontrada em 14 pacientes, tendo como causas prováveis intervenções cirúrgicas torácicas em 6 (43%), neuropatia por herpes-zoster em 4 (28%), provável neurite de nervo intercostal em 2 (14%), neoplasia pulmonar em 1 (7%) e radiculopatia em 1 (7%). As principais causas de MNI de nosso Serviço são similares às da literatura. Os antidepressivos tricíclicos e anticonvulsivantes foram os fármacos mais utilizados no controle da dor.

Mononeuropathy of the suprascapular nerve: study of 3 South American cases.

In this work 3 new cases of suprascapular nerve mononeuropathy are described. ENMG diagnosis criteria were: a) normal sensory conduction studies of the ipsolateral ulnar, median and radial nerves; b) bilateral suprascapular nerve latencies with bilateral compound muscle action potential, obtained from the infraspinatus muscle with symmetrical techniques; and c) abnormal neurogenic infraspinatus muscle electromyographic findings, coexisting with normal electromyographical data of the ipsolateral deltoideus and supraspinatus muscles. These 3 cases of suprascapular mononeurpathy were found in 6,080 ENMG exams from our University Hospital. For us this mononeuropathy is rare with a 0.05% occurrence.

Comparison of the tensile bond strengths of cast metal crowns luted with resin cements.

The limitation of photoactivation of dual-polymerized resin cements along the margins of metal restorations may adversely affect the mechanical properties of these cements, thus impairing the retention of restorations. The aim of this study was to assess the bond strength of cast metal crowns cemented with three dual-polymerized resin cements, using a chemically-activated resin cement and zinc phosphate as controls. Fifty nickel-chromium alloy crowns were cast and randomly assigned to five groups of equal size. Castings were cemented on their corresponding metal dies with one of the tested luting agents: Scotchbond Resin Cement, Enforce and Panavia F (dual-polymerized resin cements), Cement-It (chemically-activated resin cement) and Zinc Phosphate Cement (zinc phosphate cement). Specimens were stored in distilled water at 37 degrees C for 24 h and then loaded in tension until failure. Panavia F and Zinc Phosphate Cement provided the highest and lowest bond strength means, respectively. Scotchbond Resin Cement, Enforce and Cement-It cements exhibited similar intermediate values, but with statistically significant difference compared to the other materials (P < 0.05). Even with the restriction or absence of light activation, all tested dual-polymerized resin cements produced significantly higher bond strength than did the zinc phosphate cement and yielded similar or better results than the chemically activated cement. It should be pointed out that the findings of this study relate to a test scenario which does not mimic clinical circumstances and that further work is required to identify the clinical significance of the reported tensile bond strength differences between the different luting materials.

The natural history of carpal tunnel syndrome. A study of 20 hands evaluated 4 to 9 years after initial diagnosis.

Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy. In the last decade several papers have been published on epidemiology, clinical aspects, diagnosis, and treatment, but little is known about its natural history. The objective of this work was to study the natural history of CTS syndrome. From 358 patients with clinical and conduction study diagnosis of CTS, 12 cases were identified that had refused surgical treatment, had not used anti-inflammatory medications, and had not undergone orthopaedic procedures, such as immobilization or anaesthetic infiltration. These 12 patients have 20 compromised hands which have been followed up for between 4 and 9 years. In all cases sensory and motor conduction studies were performed on the median nerve, at the beginning and end of follow-up period. Electrical improvement was marked in 5 hands and slight in 3; there was no significant change in 10, and deterioration in 2. As 8 hands (7 patients) showed improved clinical symptoms and conduction studies over several years, this brings the universally accepted procedure of surgical treatment into doubt.

Effect of disinfectant agents on dimensional stability of elastomeric impression materials.

STATEMENT OF PROBLEM: Difficulties in sterilizing impressions by traditional methods have led to chemical disinfection as an alternative, and some studies have shown that disinfectants may adversely affect impressions. PURPOSE: This study investigated the effect of disinfection methods on the dimensional stability of 6 elastomeric materials. MATERIAL AND METHODS: Impression materials were submitted to the following treatments: immersion in 5.25% sodium hypochlorite solution for 10 minutes, immersion in 2% glutaraldehyde solution for 30 minutes, and no immersion (control). After treatments, impressions were poured, and respective stone casts were measured with a Nikon Profile projector and compared with the master model. RESULTS: The elastomeric materials had different reproduction capacities, and the disinfecting treatments did not differ from the control.

[Video-polygraphic-EEG study in the full-term newborn with low birthweight for their gestational age]. / Estudo vídeo-polissonográfico em recém-nascidos de termo pequenos para a idade gestacional.

Video-polygraphic-EEG studies were performed in the first 24 life-hours of 26 healthy full-term newborns without perinatal injuries. The neurological examination and cranial ultrasonography were normal. The newborns were divided into two groups: one, with full-term appropriate--birth weight 11 newborns (control group) and the other with full-term low-birth weight 15 newborns. Thirteen newborns of the second group had video-polygraphic-EEG study abnormalities. The most frequent abnormalities were found in 11 cases, as far as sleep architecture is concerned. Also, when compared with the control group, 8 cases of an excessive amount of startles and 2 cases of low behavior activities were found. The results demonstrate the usefulness of video-polygraphic-EEG study in the full-term newborns with intra-uterine growth retard. This examination was sensitive to detect behavior, sleep architecture and EEG standard differences in the low birth-weight newborns as to the control group.

O EEG na induficiência renal crônica: I Atividade de fundo em repouso e durante ativaçäo / EEG in chronic renal failure: I background activity in rest and during activation

Examinamos o eletroencefalograma (EEG) de 88 pacientes com insuficiência renal crônica, sendo 80 adultos e 8 crianças, submetidos a diferentes tipos de tratamento como hemodiálise, diálise peritoneal, transplante renal e seguimento em ambulatório. A principal alteraçäo observada foi desorganizaçäo difusa da atividade de fundo. Encontramos, em ordem decrescente de frequência, EEG de baixa voltagem, ondas trifásicas, reaçöes anormais do despertar e ritmo alfa paradoxal. As crianças mostraram um ritmo alfa anormal, e, em nossos pacientes, as alteraçöes induzidas por fotoestimulaçäo intermitente foram mínimas, sendo esta a principal diferença em relaçäo aos outros autores que estudaram o EEG na uremia crônica

O EEG na insuficiência renal crônica: II. atividades paroxísticas / EEG in chronic renal failure: II. paroxismal epileptiform

Os autores descrevem atividades paroxísticas no EEG de pacientes com insuficiência renal crônica. Um paciente apresentou paroxismos epileptiformes na regiäo parietal direita, que precederam crises parciais motoras óculo-clônicas e, depois, acidente vascular cerebral isquêmico localizado na mesma regiäo. Essa foi a principal correlaçäo eletro-clínica encontrada que, entretanto, näo pôde ser observada em outros pacientes. As sessöes de diálise podem melhorar ou piorar os paroxismos epileptiformes

O EEG na insuficiência renal crônica: III. valor prognóstico / EEG in chronic renal failure: III. prognosis

Em 1983 e 1984 realizamos seguimento longitudinal, durante 1 ano, de 15 pacientes com insuficiência renal crônica, sendo 8 em hemodiálise e 7 em diálise peritoneal. As anormalidades do EEG foram catalogadas e arquivadas, e 5 anos depois estudamos os prontuários dos pacientes, para analisar as evoluçöes clínicas que eles apresentaram. Os achados do EEG do idoso, em pacientes jovens com insuficiência renal crônica, ocorreram em pacientes que vieram a falecer. Concluímos que os achados do EEG do idoso na insuficiência renal crônica, em qualquer idade, significam mau prognóstico. Por outro lado, assincronias no EEG estäo associadas a encefalopatia urêmica grave, porém reversível, porque uma paciente com assincronias foi transplantada posteriormente e suas alteraçöes clínicas e eletroencefalográficas reverteram

Chronic motor neuron disease possibly related to intoxication with organochlorine insecticides.

We report on two patients with a history of chronic exposure to organochlorine insecticides who developed clinical and electromyographic signs and symptoms of chronic motor neuron disease. Measurements of aldrin, lindane and heptachlor confirmed the intoxication. We emphasize the importance of searching for toxic and environmental factors in cases of motor neuron disease especially in Third World countries, where workers usually wear no adequate protective equipment.