Luís Pires Lopes

Biodegradation of acrylic based resins: A review

OBJECTIVESnThe development of different types of materials with application in dentistry is an area of intense growth and research, due to its importance in oral health. Among the different materials there are the acrylic based resins that have been extensively used either in restorations or in dentures. The objective of this manuscript was to review the acrylic based resins biodegradation phenomena. Specific attention was given to the causes and consequences of materials degradation under the oral environment.nnnDATA AND SOURCESnInformation from scientific full papers, reviews or abstracts published from 1963 to date were included in the review. Published material was searched in dental literature using general and specialist databases, like the PubMED database.nnnSTUDY SELECTIONnPublished studies regarding the description of biodegradation mechanisms, in vitro and in vivo release experiments and cell based studies conducted on acrylic based resins or their components were evaluated. Studies related to the effect of biodegradation on the physical and mechanical properties of the materials were also analyzed.nnnCONCLUSIONSnDifferent factors such as saliva characteristics, chewing or thermal and chemical dietary changes may be responsible for the biodegradation of acrylic based resins. Release of potential toxic compounds from the material and change on their physical and mechanical properties are the major consequences of biodegradation. Increasing concern arises from potential toxic effects of biodegradation products under clinical application thus justifying an intensive research in this area.

Evaluation of left ventricular outflow tract gradient during treadmill exercise and in recovery period in orthostatic position, in patients with hypertrophic cardiomyopathy

Background-Left ventricular outflow tract obstruction is an independent predictor of adverse outcome in hypertrophic cardiomyopathy (HCM). The classical quantification of intraventricular obstruction is performed in resting conditions in supine position, but this assessment does not reflect what happens in HCM patients (pts) in their daily activities, neither during effort nor during orthostatic recovery.Aim-To assess intraventricular gradients with echocardiography during treadmill exercise and in the recovery period in upright position, in HCM pts.Methods-We studied 17 HCM pts (9 males, mean age 53 ± 16 years, 11 with obstructive HCM). Each pt had 2 echocardiographic evaluations at rest (left lateral decubitus (LLD) and orthostatic position). The pts then underwent a treadmill exercise test and intraventricular gradients were measured at peak exercise and during recovery in orthostatic position.Results-3 pts with non-obstructive HCM at rest developed intraventricular gradients during exercise. 1 pt developed this gradient only during orthostatic recovery. The mean intraventricular gradient in LLD was 49 ± 24 mmHg; in orthostatic position was 62 ± 29 mmHg (p < 0.001 versus in LLD); at peak exercise was 83 ± 35 mmHg (p < 0.001 versus supine rest); during recovery it was 96 ± 35 mmHg (p < 0.001 versus peak exercise)Conclusion-In HCM pts the intraventricular gradient increases in orthostatic position, increases significantly during treadmill exercise and continues increasing in the recovery period in orthostatic position. This type of evaluation can help us to better understand the physiopathology, the symptoms and the efficacy of different therapeutic modalities in this disease and should be routinely used in the assessment of HCM pts.

Echocardiographic assessment of right ventricular contractile reserve in patients with pulmonary hypertension

INTRODUCTION AND AIMnRight ventricular function is a major determinant of prognosis in pulmonary hypertension. The aim of this study was to assess and compare right ventricular contractile reserve in healthy subjects (controls) and in subjects with pulmonary hypertension (cases).nnnMETHODSnIn this prospective study of seven cases and seven controls undergoing treadmill stress echocardiography, right ventricular S-wave velocity, tricuspid annular plane systolic excursion (TAPSE), right ventricular fractional area change (RVFAC) and stroke volume index were assessed at rest and with exercise. The increase in each parameter between rest and exercise for cases and controls was analyzed and the magnitude of change in each parameter with exercise between cases and controls was compared.nnnRESULTSnA significant increase in S-wave velocity was observed in cases (rest: 9.4 ± 3.1; exercise: 13.7 ± 4.8 cm/s [p < 0.05]). In controls there was a statistically significant increase in S-wave velocity (12.9 ± 2.3 to 23.0 ± 7.2 cm/s [p < 0.005]), TAPSE (25.7 ± 2.4 to 31.0 ± 3.5 mm [p < 0.05]) and RVFAC (53.8 ± 14.7% to 64.4 ± 9.9% [p < 0.005]). The magnitude of change in S-wave velocity (cases: 4.3 ± 3.3; controls: 10.1 ± 5.5 cm/s [p < 0.05]), TAPSE (cases: 0.6 ± 2.5; controls: 5.3 ± 3.8 mm [p < 0.05]) and RVFAC (cases: -0.4 ± 11.8; controls: 10.6 ± 5.9% [p < 0.05]) was significantly different between cases and controls.nnnCONCLUSIONSnS-wave velocity, TAPSE and RVFAC increased significantly with exercise in controls. S-wave velocity was the only parameter that showed a significant increase in cases, although the magnitude of this increase was significantly less than in controls.

Ethanol Postpolymerization Treatment for Improving the Biocompatibility of Acrylic Reline Resins

Objective. To evaluate the effect of postpolymerization treatment based on ethanol-aqueous solutions on the residual monomer (RM) content, flexural strength, microhardness, and cytotoxicity of hard chairside reline resins (Kooliner, Ufi Gel Hard). Methods. After polymerization, specimens were immersed in water, 20%, 50%, or 70% ethanol solutions at 23°C or 55°C for 10 minutes. Controls were left untreated. HPLC was used for the determination of RM content. Specimens were submitted to Vickers microhardness and 3-point loading flexural strength tests. Cytotoxicity of resin eluates was determined on human fibroblasts by assessing cellular mitochondrial function and lactate dehydrogenase release. Results. Higher concentrations of ethanol promoted lower RM content at 55°C in both materials. The mechanical properties were maintained after 50% and 20% ethanol treatments in Kooliner and Ufi Gel Hard, respectively. Specimens submitted to those treatments showed significant reduction on cytotoxicity compared to immersion in hot water, the treatment of choice in the recent literature. Significance. Immersion of relined dentures in specific ethanol solutions at 55°C for 10 minutes can be considered an effective postpolymerization treatment contributing to increase materials biocompatibility. The proposed protocol is expeditious and easy to achieve with simple equipment in a dental office.

What Is Really a Nonobstructive Hypertrophic Cardiomyopathy? The Importance of Orthostatic Factor in Exercise Echocardiography

The authors report the case of a 23-year-old girl with nonobstructive hypertrophic cardiomyopathy evaluated by resting echocardiography. The patient complained of syncope after playing basketball. The patient was submitted to treadmill exercise echocardiogram, and she exercised for 9 minutes in standard Bruce protocol. The left ventricular outflow gradient did not occur at peak workload; however she developed intraventricular gradient greater than 100u2009mmHg after exercise in orthostatic position. There was fall in arterial pressure, and the patient was then put in supine position. The authors suggest the possible role of exercise stress echo in symptomatic patients with no significant gradient at baseline, as well as maintenance in orthostatic position after exercise, as an important stress factor. This can disclose the occurrence of left ventricular outflow tract obstruction that should not be detected in other way and has potential relevance in the patients symptoms understanding.

Adhesion of dental sealants to enamel with self-etching adhesives in salivary contamination conditions: Influence of the light curing protocol

Purpose: To evaluate the influence of the light curing protocol in the shear bond strength of a sealant to enamel treated with two self-etching adhesive systems, in salivary contamination conditions. Materials and Methods: The dental sealant (Delton, Dentsply) was applied, after saliva contamination, onto the vestibular enamel of sixty human incisors treated with Xeno III (Dentsply) or Prompt-L-Pop (3M/Espe). These two groups were further divided into two subgroups (n = 15) according to the curing time: 1) the adhesive system was cured with the sealant (co-polymerization), and 2) adhesive and sealant were light cured independently (independent polymerization). After the adhesive procedures, specimens were stored in water (37 °C-24 h) and thermal-cycled. Shear bond strength tests were done in an universal testing machine. Data was analyzed with two-way ANOVA. Results: There were no statistical differences (p = 0.267) between the adhesive systems tested. The co-polymerization groups (33.3 ± 9.4 MPa) yielded statistically higher shear bond strength values than the independent polymerization groups (28.2 ± 4.7 MPa). Even with saliva contamination, the self-etching adhesive systems used yielded high shear bond strength values. Conclusions: In the conditions tested, the co-polymerization of the adhesive systems with the sealant led to higher bond strength values to enamel than the independent polymerization.

Sphere-plane methodology to evaluate the wear of titanium of dental implants: a research proposal

ObjectiveTitanium is the most commonly used material to manufacture dental implants and abutments. Recently, zirconia abutments have been manufactured with better aesthetic properties. However, zirconia abutments are harder than titanium implants; therefore, they could wear the implant surface. Therefore, this article aims to describe a sphere-plane system that can be used to assess the wear that different abutment materials cause in the titanium of dental implants when submitted to cyclic loading. This method can be used to simulate the oral cavity, where the abutment (sphere) applies loads onto the implant (titanium plane). The spheres were made of different materials (titanium and zirconia), and the specimens were loaded for 4,000,000 cycles. The scar size and area on titanium planes were measured with stereoscopic images and analysed through profilometry.ResultsThe wear of titanium planes was similar when tested against zirconia or titanium spheres. The sphere-plane system is a method that can be used to evaluate and quantify the wear of the titanium of dental implants, and compared with methods that use real implants, this system is simpler and less expensive. This method could facilitate further research to evaluate the wear of titanium against different materials and under different testing conditions.

A Very Complicated Inferior Myocardial Infarction: The Role of Multimodality Imaging Approach.

A 47-year-old male presented with a subacute inferior myocardial infarction (MI) complicated by inferobasal ventricular septal rupture (VSR) and underwent emergency surgical repair of VSR with a pericardial patch. In the postoperative period he remained hypotensive, with low exercise tolerance and a holosystolic murmur was present. Echocardiography showed persistence of VSR with left-right shunt (Figure 1A) and revealed an aneurysmatic region at the inferobasal wall of the left ventricle (LV), suggestive of a true aneurysm due to its large neck and smooth transition from normal myocardium to the aneurysm (Figures 1A and u200band1B).1B). Cardiac magnetic resonance confirmed the VSR (Figures 1C and u200band1D)1D) with significant shunt (Qp/Qs of 2.3), showed transmural necrosis of the basal and mid segments of the inferior and free wall of the right ventricle with moderate systolic dysfunction and also revealed that the aneurysmatic inferobasal region of LV was actually a pseudoaneurysm, without myocardial tissue but with a sessile and adherent thrombus within it (Figures 1E and u200band1F1F). n n n nFigure 1 n nEchocardiographic mid-ventricular short axis view showing VSR with left-to-right shunt (A). Echocardiographic two-chamber view showing an inferobasal aneurysmatic region (B). Cardiac magnetic resonance (CMR) cine-imaging with a ventricular short axis ... n n n n n nIn conclusion, this patient presented with an inferior MI complicated by right ventricular infarction, inferobasal VSR and inferior pseudoaneurysm with organized thrombus inside. Mechanical complications are rare nowadays due to early revascularization. The multimodality imaging approach is essential for their correct diagnosis.

Retorno venoso pulmonar anómalo parcial

A 51-year-old man with no cardiovascular symptoms was referred for cardiac magnetic resonance imaging (CMRI) for further investigation of alterations observed on previous exams. CMRI revealed biventricular dilatation and paradoxical septal motion compatible with volume overload. Balanced steady-state free precession sequences in axial planes showed an anomalous vein oriented vertically and lateral to the aortic arch, communicating with the innominate vein (Figure 1), and a normal-sized coronary sinus. Three-dimensional angiographic reconstruction of the heart and great vessels showed an anomalous pulmonary vein draining into the innominate vein (Figures 2 and 3), causing partial anomalous pulmonary venous return (PAPVR) from the left upper pulmonary lobe (Qp:Qs of 1.4:1). PAPVR is a venous anomaly in which some pulmonary veins drain into the right atrium, directly or indirectly through a systemic vein. It has an overall incidence of 0.5% and most frequently involves the right lung. Anomalous left pulmonary veins generally drain the upper lobe into the innominate vein. PAPVR causes a left-to-right shunt that is usually insignificant and asymptomatic.

Dispneia na estenose aórtica: nem tudo o que parece é

Valvular aortic stenosis is the most common valvular disorder in Europe. Although recommended, stress exams are still underused in its evaluation. We report the case of a 60-year-old man who, following a routine electrocardiogram with abnormal ventricular repolarization, underwent stress testing, which was positive for myocardial ischemia, and an echocardiogram that revealed moderate aortic stenosis. Cardiac catheterization showed no angiographic coronary lesions and an intraventricular gradient of 45 mmHg. In view of the latter, stress echocardiography was performed, which documented an increase in the intraventricular gradient from 30 mmHg to 131 mmHg. Repeat stress echocardiography under treatment with bisoprolol showed an increase in test duration and a maximum intraventricular gradient at peak exercise of 36 mmHg. Stress exams may have an important role in the diagnostic and therapeutic management of patients with aortic stenosis.