Non-linear partitioning and organic volatility distributions of urban aerosols.

Gas-to-particle partitioning of organic aerosols (OA) is represented in most models by Raoult's law, and depends on the existing mass of particles into which organic gases can dissolve. This raises the possibility of non-linear response of particle-phase OA mass to the emissions of precursor volatile organic compounds (VOCs) that contribute to this partitioning mass. Implications for air quality management are evident: a strong non-linear dependence would suggest that reductions in VOC emission would have a more-than-proportionate benefit in lowering ambient OA concentrations. Chamber measurements on simple VOC mixtures generally confirm the non-linear scaling between OA and VOCs, usually stated as a mass-dependence of the measured OA yields. However, for realistic ambient conditions including urban settings, no single component dominates the composition of the organic particles, and deviations from linearity are presumed to be small. Here we re-examine the linearity question using volatility spectra from several sources: (1) chamber studies of selected aerosols, (2) volatility inferred for aerosols sampled in two megacities, Mexico City and Paris, and (3) an explicit chemistry model (GECKO-A). These few available volatility distributions suggest that urban OA may be only slightly super-linear, with most values of the normalized sensitivity exponent in the range 1.1-1.3, also substantially lower than seen in chambers for some specific aerosols. The rather low exponents suggest that OA concentrations in megacities are not an inevitable convergence of non-linear effects, but can be addressed (much like in smaller urban areas) by proportionate reductions in emissions.

Surfactant use for premature infants with respiratory distress syndrome in three New York city hospitals: discordance of practice from a community clinician consensus standard.

OBJECTIVE: To assess concordance with a locally developed standard of care for premature infants with respiratory distress syndrome (RDS) for whom the standard recommends surfactant treatment within 2 h of birth, and to examine the association between clinical, demographic, and hospital characteristics with discordance from the standard. STUDY DESIGN: Retrospective cohort study of 773 infants weighing < or =1750 g born in any of the three New York City hospitals between 1999 and 2002. RESULT: 227 of the 773 infants (29%) met criteria for treatment according to the standard. Of these, 37% received surfactant by 2 h. By 4 h, 70% of infants who met the standard received surfactant. White infants were more likely to receive surfactant by 4 h (85%) than African American (61%) or Latino infants (67%). Multivariable logistic regression revealed significant odds ratios predicting discordance from the relaxed criteria (4 h) for African American race (4.10, 95% confidence interval: 1.30 to 13.00), 100 g of birth weight (odds ratio: 1.22, 95% confidence interval: 1.10 to 1.34), and hospital of birth. CONCLUSION: Many infants with RDS failed to receive surfactant replacement therapy at 2 and 4 h after birth. African Americans and those born larger were less likely to receive surfactant. If these data can be generalized, there is a large opportunity to reduce infant morbidity from RDS and to reduce racial/ethnic disparities in birth outcomes by increasing the rate and speed with which surfactant is delivered to these infants.

Eliciting patient preferences for hormonal therapy options in the treatment of metastatic prostate cancer.

Treatment choices for metastatic prostate cancer are complex and can involve men balancing survival versus quality of life. The present study aims to elicit patient preferences with respect to the attributes of treatments for metastatic prostate cancer through a discrete choice experiment (DCE) questionnaire. Men with recently diagnosed localized prostate cancer were asked to envisage that they had metastatic disease when completing a survey. As expected, men with prostate cancer placed considerable importance on gains in survival; however, avoiding side effects of treatment was also clearly important. Survival gains should be considered alongside side effects when discussing treatment options in metastatic disease.

Gastrointestinal-specific patient-reported outcome instruments differentiate between renal transplant patients with or without GI complications.

BACKGROUND: Gastrointestinal (GI) complications are frequently reported postrenal transplant and are often associated with immunosuppressant regimens including mycophenolate mofetil (MMF). This study evaluated the ability of two GI-specific patient-reported outcome (PRO) instruments to differentiate between patients with and without GI complaints. METHODS: Discriminant validity of the Gastrointestinal Symptom Rating Scale (GSRS) and Gastrointestinal Quality of Life Index (GIQLI), as well as two generic instruments (Psychological General Well-Being Index (PGWB) and EQ-5D, was assessed in a multinational study of renal transplant recipients. Patients received therapy that included a calcineurin inhibitor and MMF. Both t-tests and ANOVAs were used to examine differences between patients with and without GI complaints, among levels of severity, and between patients reporting presence/absence of specific GI side effects. RESULTS: Of 96 patients recruited (56% male), 43% had none, 39% mild, 13% moderate, and 6% severe GI symptoms. All GSRS subscales and the GIQLI total and four of the five subscale scores significantly differentiated between patients with/without GI complications (P < .05). The PGWB total score and three subscales, the EQ-5D significantly differentiated between the two groups (P < .05). Only GI-specific instruments discriminated between some severity levels; for example, the GSRS abdominal pain subscale discriminated between patients at all levels of severity (P < .05). The GIQLI total score and symptoms subscale differentiated between patients with no symptoms and those with mild or moderate or severe symptoms (P < .05). CONCLUSIONS: The GSRS and GIQLI differentiated between patients with/without GI side effects and by symptom severity better than did generic instruments, demonstrating excellent discriminant ability in this population.

Acupuncture and clinical hypnosis for facial and head and neck pain: a single crossover comparison.

Despite their long histories, acupuncture and hypnosis have only recently been acknowledged as valuable by the medical establishment in the U.S. Few studies have used rigorous prospective measurement to evaluate the individual or relative merits of hypnosis and acupuncture in specific clinical settings. In this study, 25 patients with various head and neck pain were studied. Each had an initial assessment of their pain, as well as of their attitudes and expectations. All patients received acupuncture, followed by a reassessment of their pain. After a washout period they received another assessment of pain before and after hypnosis therapy. Preferences for therapy were sought following the hypnotic intervention. Both acupuncture and hypnosis were effective at relieving pain under these conditions. The average relief in pain reported was 4.2 units on a ten point scale, with hypnosis reducing pain by a mean of 4.8 units, compared to 3.7 for acupuncture (p = 0.26). Patient characteristics appeared to impact the effectiveness of treatment: patients with acute pain benefited most from acupuncture treatment, whereas patients with psychogenic pain were more likely to benefit from hypnosis. Patients with chronic pain had more variation in their results. Patients who received healing suggestions from a tape during a hypnotic trance benefited more than those who received no such suggestion, and acupuncture patients who were needle phobic benefited less than those who were not fearful of needles. This study demonstrates the benefits of well designed studies of the effectiveness of these alternative modalities. More work is needed to help practitioners identify which patients are most likely to benefit from these complementary therapies.

A comparative trial of paper-and-pencil versus computer administration of the Quality of Life in Reflux and Dyspepsia (QOLRAD) questionnaire.

BACKGROUND: Although most health-related quality of life questionnaires are self-administered by means of paper and pencil, new technologies for automated computer administration are becoming more readily available. Novel methods of instrument administration must be assessed for score equivalence in addition to consistency in reliability and validity. OBJECTIVES: The present study compared the psychometric characteristics (score equivalence and structure, internal consistency, and reproducibility reliability and construct validity) of the Quality of Life in Reflux And Dyspepsia (QOLRAD) questionnaire when self-administered by means of paper and pencil versus touch-screen computer. The influence of age, education, and prior experience with computers on score equivalence was also examined. RESEARCH DESIGN: This crossover trial randomized 134 patients with gastroesophageal reflux disease to 1 of 2 groups: paper-and-pencil questionnaire administration followed by computer administration or computer administration followed by use of paper and pencil. To minimize learning effects and respondent fatigue, administrations were scheduled 3 days apart. A random sample of 32 patients participated in a 1-week reproducibility evaluation of the computer-administered QOLRAD. RESULTS: QOLRAD scores were equivalent across the 2 methods of administration regardless of subject age, education, and prior computer use. Internal consistency levels were very high (alpha = 0.93-0.99). Interscale correlations were strong and generally consistent across methods (r = 0.7-0.87). Correlations between the QOLRAD and Short Form 36 (SF-36) were high, with no significant differences by method. Test-retest reliability of the computer-administered QOLRAD was also very high (ICC = 0.93-0.96). CONCLUSIONS: Results of the present study suggest that the QOLRAD is reliable and valid when self-administered by means of computer touch-screen or paper and pencil.

The impact of nocturnal symptoms associated with gastroesophageal reflux disease on health-related quality of life.

BACKGROUND: Two types of reflux episodes have been identified: upright or daytime and supine or nocturnal. The population-based prevalence of symptoms of nocturnal gastroesophageal reflux disease (GERD) and the impact of those symptoms on health-related quality of life (HRQL) have not been established. METHODS: A national random-sample telephone survey was conducted to estimate the prevalence of frequent GERD and nocturnal GERD-like symptoms and to assess the relationship between HRQL, GERD, and nocturnal GERD symptoms. Respondents were classified as controls, subjects with symptomatic nonnocturnal GERD, and subjects with symptomatic nocturnal GERD. The HRQL was assessed using the Medical Outcomes Study Short-Form 36 Health Survey (SF-36). RESULTS: The prevalence of frequent GERD was 14%, with an overall prevalence of nocturnal GERD of 10%. Seventy-four percent of those with frequent GERD symptoms reported nocturnal GERD symptoms. Subjects with nonnocturnal GERD had significant decrements on the SF-36 physical and mental component summary scores compared with the US general population. Subjects reporting nocturnal GERD symptoms were significantly more impaired than subjects reporting nonnocturnal GERD symptoms on both the physical component summary (38.94 vs 41. 52; P<.001) and mental component summary (46.78 vs 49.51; P<.001) and all 8 subscales of the SF-36 (P<.001). Subjects with nocturnal GERD demonstrated considerable impairment compared with the US general population and chronic disease populations. Subjects with nocturnal GERD had significantly more pain than those with hypertension and diabetes (P<.001) and similar pain compared with those with angina and congestive heart failure. CONCLUSIONS: Nocturnal symptoms are commonly experienced by individuals who report frequent GERD symptoms. In addition, HRQL is significantly impaired in those persons who report frequent GERD symptoms, and HRQL impairment is exacerbated in those who report nocturnal GERD symptoms.

Instabilities in diamond under high shear stress

We investigate, through first-principles calculations, lattice instabilities induced in diamond by the application of high shear stresses. For shear stresses as low as 95 GPa a lattice instability will occur, leading to graphitelike layered structures. This effect is highly anisotropic. The reversal of the direction of the applied shear forces may cause a change of 80 GPa in the shear stress value at which the instability develops. The same reversal also causes different bonds to be broken, resulting in a drastic change in the orientation of the resulting graphitelike structures. We also find that an additional compressive stress of 50 GPa along the (111) direction does not eliminate the shear-induced instability.

Upper gastrointestinal symptoms in North America: prevalence and relationship to healthcare utilization and quality of life.

The aim of this study was to determine the prevalence of upper gastrointestinal symptoms (UGIS) in a general population and quantify the relationship of those symptoms to healthcare utilization and quality of life. In-person interviews were conducted with 2056 United States and Canadian residents selected at random. Subjects reported frequency and severity for 11 symptoms, prescription and over-the-counter medication use, primary care and specialty physician visits in prior three months, and completed the Psychological General Well-Being Scale. For analyses, subjects were classified into four mutually exclusive symptom groups: gastroesophageal reflux disease (GERD) -like, GERD plus motility-like (GERD+), ulcerlike, and motility-like. Of the total sample, 51.4% reported the occurrence of at least one UGIS in the prior three months. Subjects in the GERD+ and ulcer groups used more prescription medications and were more likely to see a physician about the symptoms (P<0.001). Subjects with symptoms demonstrated poorer quality of life compared to subjects with no symptoms. The prevalence of UGIS in the general population is high and symptoms are associated with significant health-care utilization and poorer quality of life.

Psychometric evaluation of the fatigue severity scale for use in chronic hepatitis C.

Evidence exists demonstrating that infection with hepatitis C virus impairs health-related quality of life, but less is known about the effect of fatigue, a common symptom, on everyday life. The psychometric properties of the fatigue severity scale (FSS) were explored to determine suitability as an outcome measure in clinical trials. The FSS includes nine items developed to measure disabling fatigue and a visual analog scale (VAS) to measure overall fatigue. Using baseline data from three clinical trials (n = 1225) involving chronic hepatitis C patients, scaling and psychometric characteristics of the FSS were assessed. The SF-36 was also used in the trials. Item response theory analysis demonstrated that the FSS items can be placed along a single homogenous domain, fatigue. Internal consistency reliability was 0.94. Test-retest reliability was 0.82 for the total score and 0.80 for the VAS. The total score and the VAS were significantly correlated with the SF-36 vitality subscale (r = -0.76 and r = -0.76 respectively). Correlations with other SF-36 subscales were moderate (r = -0.46 to r = -0.67, all p < 0.0001). In summary, the FSS possesses good psychometric properties.

Technical report: minor head injury in children.

UNLABELLED: Minor head trauma affecting children is a common reason for medical consultation and evaluation. In order to provide evidence on which to base a clinical practice guideline for the American Academy of Pediatrics, we undertook a systematic review of the literature on minor head trauma in children. METHODS: Medline and Health databases were searched for articles published between 1966 and 1993 on head trauma or head injury, limited to infants, children, and adolescents. Abstracts were reviewed for relevance to mild head trauma consistent with the index case defined by the AAP subcommittee. Relevant articles were identified, reviewed, and abstracted. Additional citations were identified by review of references and expert suggestions. Unpublished data were also identified through contact with authors highlighting child-specific information. Abstracted data were summarized in evidence tables. The process was repeated in 1998, updating the review for articles published between 1993 and 1997. RESULTS: A total of 108 articles were abstracted from 1033 abstracts and articles identified through the various search strategies. Variation in definitions precluded any pooling of data from different studies. Prevalence of intracranial injury in children with mild head trauma varied from 0% to 7%. Children with no clinical risk characteristics are at lower risk than are children with such characteristics; the magnitude of increased risk was inconsistent across studies. Computed tomography scan is most sensitive and specific for detection of intracranial abnormalities; sensitivity and specificity of skull radiographs ranged from 21% to 100% and 53% to 97%, respectively. No high quality studies tested alternative strategies for management of such children. Outcome studies are inconclusive as to the impact of minor head trauma on long-term cognitive function. CONCLUSIONS: The literature on mild head trauma does not provide a sufficient scientific basis for evidence-based recommendations about most of the key issues in clinical management. More consistent definitions and multisite assessments are needed to clarify this field.

Serum anion gap in the differential diagnosis of metabolic acidosis in critically ill newborns.

OBJECTIVES: To determine in critically ill newborn infants (1) the range of the serum anion gap without metabolic acidosis and (2) whether the serum anion gap can be used to distinguish newborns with lactic acidosis from those with hyperchloremic metabolic acidosis. STUDY DESIGN: Umbilical arterial blood gases and serum electrolyte and lactate concentrations were measured simultaneously in 210 samples from 63 infants over the first week of life. Metabolic acidosis was defined as a blood base deficit (BD) >4 mmol/L. The anion gap was calculated as [Na(+)] - [C1(-)] - [TCO (2)]. Lactic acidosis was defined as a serum lactate concentration >2 SD above the mean serum lactate concentration in samples without metabolic acidosis. RESULTS: In 89 blood samples with BD <4 mmol/L, serum lactate concentration decreased with postnatal age (r = 0.51). The upper limit of serum lactate concentration was 3.8 mmol/L at less than 48 hours, 2.4 mmol/L between 48 and 96 hours, and 1.5 mmol/L for infants greater than 96 hours of age. The mean serum anion gap +/- 2 SD in 174 samples without lactic acidosis was 8 +/- 4 mmol/L; in 36 samples with lactic acidosis it was 16 +/- 9 mmol/L (P <.0001). Serum anion gap and lactate concentration were poorly correlated for samples without lactic acidosis (r = 0.04) but highly correlated in those with lactic acidosis (r = 0.81, P <.0001). None of the 85 samples with metabolic acidosis but without lactic acidosis had an anion gap >16 mmol/L; only 4 of 36 samples with lactic acidosis had an anion gap <8 meq/L. However, 25 of 36 samples with lactic acidosis had serum anion gaps of 8 to 16 mmol/L. CONCLUSION: In the presence of metabolic acidosis, a serum anion gap >16 mmol/L is highly predictive of lactic acidosis; a serum anion gap <8 is highly predictive of the absence of lactic acidosis; an anion gap = 8 - 16 mmol/L has no use in the differential diagnosis of metabolic acidosis in the critically ill newborn.

Psychometric validation of a constipation symptom assessment questionnaire.

BACKGROUND: Clinical management of constipation is complicated by the lack of a gold standard for evaluation of symptoms. A constipation symptom assessment instrument, the PAC-SYM, was developed to address the patient perspective on the disorder. Instrument content was based on literature review and results of focus groups. METHODS: Two hundred and sixteen patients at nine sites participated in a 6-week psychometric evaluation of the PAC-SYM. The final instrument contained 12 items assigned to 3 subscales: stool symptoms, rectal symptoms, and abdominal symptoms. The psychometric properties of this final instrument were assessed. RESULTS: Internal consistency and test-retest reliability of the final instrument was high (Cronbach's alpha = 0.89; intraclass correlation = 0.75). Concurrent validity was supported by the correlation with both subject and investigator constipation severity ratings (r= 0.68 and 0.72, respectively; P < 0.0001). Scores were moderately correlated with instruments measuring quality of life. Comparison of treatment responders with nonresponders showed the ability of the instrument to differentiate between groups on the basis of clinical severity (t = -6.12, P < 0.0001 ). Scores changed significantly over time among responders, indicating instrument responsiveness. CONCLUSIONS: The PAC-SYM is internally consistent, reproducible under stable conditions, valid, and responsive to change and provides a comprehensive means to assess the effectiveness of treatment for constipation.

Open versus endoscopic saphenous vein harvesting: wound complications and vein quality.

BACKGROUND: The saphenous vein is an important conduit for coronary artery bypass grafting. Wound complications from traditional open vein harvesting occur often. Minimally invasive endoscopic saphenous vein harvesting may decrease wound complications. Vein quality may be an issue with endoscopic harvesting. METHODS: We reviewed 568 patients who had bypass grafting and saphenous vein harvesting either endoscopic (group A, n = 180) versus open (group B, n = 388). Both groups were demographically similar and management identical. Wound complication was defined by the need for intervention and included lymphocele, hematoma, cellulitis, edema, eschar, and infection. Multiple vein segments were obtained from 8 patients, 4 from each group, and examined histologically. RESULTS: Wound complications were significantly less in group A (9/180, 5%) versus group B (55/388, 14.2%), p value equal to or less than 0.001. Open harvesting (p< or =0.001), diabetes (p< or =0.001), and obesity (p< or =0.02) were risk factors for wound complication by univariate analysis. By multiple logistic analysis, open harvesting (p< or = 0.0007) and diabetes (p< or =0.0001) were independent risk factors for wound infection. Histologic evaluation of vein samples showed that there was no difference between the groups and vascular structural integrity was maintained. CONCLUSIONS: Endoscopic saphenous vein harvesting was associated with fewer wound complications and infections. Vein quality was not adversely effected because of endoscopic harvesting.

Minor head injury in children: current management practices of pediatricians, emergency physicians, and family physicians.

OBJECTIVE: To describe variation in the clinical management of minor head trauma in children among primary care and emergency physicians. DESIGN: A survey of pediatricians, family physicians, and emergency physicians drawn from a random sample of members of the American Academy of Pediatrics, the American Academy of Family Physicians, and the appropriate American Medical Association specialty listings, respectively. Physicians were given clinical vignettes describing children presenting with normal physical examination results after minor head trauma. Different clinical scenarios (brief loss of consciousness or seizures) were also presented. Information was gathered on initial and subsequent management steps most commonly used by the physician. RESULTS: Surveys were returned by 765 (51%) of 1500 physicians. Of these, 303 (40%) were pediatricians, 269 (35%) family practitioners, and 193 (25%) emergency physicians. For minor head trauma without complications, observation at home was the most common initial physician management choice (n = 547, 72%). Observation in office or hospital was chosen by 81 physicians (11%). Head computed tomographic (CT) scan was chosen by 7 physicians (1%) and skull x-ray by 24 physicians (3%) as the first management option. Most physicians (n = 445, 80%) who initially chose observation at home would obtain a CT scan if the patient showed clinical deterioration. In the original scenario, if the patient had also sustained a loss of consciousness, 383 physicians (58%) altered management. Of these, 120 (18%) chose CT, 13 (2%) chose skull x-ray, 1 (1%) chose magnetic resonance imaging, 141 (21%) chose inpatient observation, and 125 (19%) chose a combination of CT scanning and observation. With seizures, 595 (90%) altered management, with 176 physicians (27%) choosing CT scan, 5 (1%) skull x-ray, 60 (9%) inpatient observation, and 299 (45%) a combination of radiological evaluation and observation. CONCLUSIONS: Most physicians surveyed chose clinic or home observation for initial management of minor pediatric head trauma. Clinical management was more varied when patients had sustained either loss of consciousness or seizures. Further study of the appropriate management of minor head trauma in children is needed to guide physicians in their care.

Improving the quality of care for children in health systems.

OBJECTIVE: To summarize the state of the art in quality improvement, review its application to care for children, and define the information that will be needed so that care for children can be further improved. PRINCIPAL FINDINGS: Health services for children exhibit numerous deficiencies in quality of care. The deficiencies cross all major domains of pediatric care--preventive services, acute care, and chronic care--and provide the opportunity for creative application of improvement strategies with a potential to benefit the health and well-being of children. Approaches to quality improvement have changed over the past two decades from those emphasizing the inspection of structural aspects of care and the imposition of sanctions to more dynamic strategies that emphasize measurement and comparison to motivate change; the use of evidence to specify aims for improvement; and the adoption of a variety of management strategies adapted from business and the social sciences to achieve these aims. These modern approaches to quality improvement have rarely been subjected to rigorous testing of their effectiveness. Moreover, their application in pediatrics has been less widespread than in adult healthcare. For children, several aspects about health services, such as the relative rarity of chronic illness, the important effects of social factors on health, and the limited cost, make some of these approaches even more challenging and may require new approaches or meaningful modifications. RECOMMENDATIONS: Research to understand better the general process of improvement will benefit improvement efforts for children. Research that builds the base of knowledge about best practices for children--effectiveness research--will also result in an enhanced capacity for improvement of those systems that care for children's health. Quality of care for children would be enhanced by targeted research examining ways both to foster improvement across segments of society, and to make recommendations for care more sensitive to children's development and environmental context. Research that supports incorporating the child's perspective into care is both uniquely challenging to perform and central to improving pediatric care.

Prevention and primary care research for children. The need for evidence to precede "evidence-based".

Medical care in the United States continues to face tremendous financial pressures. Public and private health policy claim to encourage primary care and preventive services, but also discourage services that have not been demonstrated to be effective and/or cost-effective. This article suggests a model to illustrate the conceptual relationship between traditional American medical care and "evidenced-based" medicine. It further examines how the lack of an adequate research base makes a move to purely evidence-based care premature for primary care and prevention services. The paper defines a new conceptual statistic, the uncertainty index, as the proportion of non-refuted current practice that is also not corroborated by research evidence. The greater the uncertainty index, the less appropriate is a clinical model restricted to evidence-based care. Specific theoretical barriers to outcomes research in prevention are discussed and simple criteria to determine the desirable components of care are suggested. The need for theoretical and empirical research into primary care and prevention, especially for children, is emphasized. Care that is of low risk, not of extremely high cost, and that is generally believed useful by the community of practitioners is particularly desirable in the absence of data refuting its value.

Termociclado en la microfiltración de restauraciones cervicales de resina compuestas y vidrio ionomeros / Termocicling in the microleakage of cervicals restorative of resin composites and glass ionomers

En este estudio se analizó comparativamente el comportamiento de 5 procedimientos restauradores, al ser someddos a fluctuaciones de temperatura. Se usaron 65 incisivos permanentes de bovino. Las piezas fueron depulpadas y apicectomizadas. Sus ápices fueron sellados con vidrio ionómero y fueron incluidas en un zócalo de acrílico. Se mantuvieron en suero fisiológico, a temperatura ambiente, durante el transcurso de toda la fase experimental. Las piezas dentarias se dividieron en 5 grupos de 13 especímenes cada uno, los cuales se obturaron con vitremer, Fuji IILC, Fuji II de autoendurecimiento, Z 100 y LC 1000 respectivamente. Cada material de obturación se manipuló de acuerdo a las indicaciones del fabricante. A los 7 días de obturadas la piezas dentarias, fueron termocicladas en fucsina básica al 0.5 porciento. Se realizaron 100 ciclos de 30 segundos; 15 segundos, a 5ºC y 15 segundos a 50'C, con intervalos de 5 segundos. Las piezas fueron posteriormente cortadas con discos de carburundum, de grano grueso, en sentido vestíbulo palatino, y fueron observadas bajo aumento con una lupa. Las observaciones demostraron distinto grado de filtración marginal en los 5 procedimientos restauradores. Los grupos obturados con vidrio ionómero presentaron menor grado de microfiltración que los obturados con resina compuesta. El menor grado de microfiltración marginal lo obtuvo el grupo obturado con Vitremer, en segundo lugar el grupo obturado con Fuji II LC, en tercer lugar el grupo obturado con Fuji II de autoendurecimiento, en cuarto lugar el grupo obturado con Z100 y el mayor grado de filtración marginal lo presentó el grupo obturado con LC 1000. En todos los grupos hubo mayor filtración marginal en la pared cervical. Se sugiere realizar un estudio para analizar la eficacia de los distintos procedimientos clínicos como la hibridación, para reducir la brecha formada entre el material restaurador y el tejido dentario y consecuentemente la microfiltración marginal