A case study approach to high-containment laboratory workflows promoting sustainability, networking and innovation.

Advances in information technologies (ITs) and operational technologies (OTs) offer high-containment laboratories opportunities to evolve scientific and operational approaches, while increasing efficiency. Emerging technologies steadily introduce changes in data generation and management practices. United States (US) government agencies and partners operate high-containment laboratories that rely on ITs/OTs to provide critical scientific functions that support prevention, detection, response and recovery for catastrophic events. These unique operating environments provide an opportunity for implementation of ITs/OTs that can facilitate both efficiency and deeper or parallel study of disease and associated biological phenomena. Operational study by subject matter experts can aid in identification of requirements and challenges pertaining to emerging ITs/OTs, examination of use cases, refinement of technical specifications and optimisation of workflows. The National Bio and Agro-Defense Facility (NBAF) in the United States of America (USA), slated to be fully operational by 2023, will be a state-of-the-art research and diagnostic facility with Biosafety Level 2, 3 and 4 laboratories for the study of high-consequence transboundary animal pathogens and zoonotic diseases impacting public health. The NBAF will support the diagnosis of emerging diseases, development of countermeasures and transboundary animal disease training. Given the rapid emergence of IT/OT solutions, the authors used a case study approach to analyse and assess real-world, high-containment laboratory functions to help maximise efficiency in mission delivery for the NBAF and the broader high-containment laboratory network. The case study approach described here could be widely adapted to diverse situations characterised by a high rate of change to provide accurate, relevant workflow analyses and optimised recommendations.

Les progrès enregistrés dans les domaines des technologies de l'information (IT) et des technologies opérationnelles (OT) offrent aux laboratoires de confinement à haute sécurité la possibilité de faire évoluer leurs approches scientifiques et opérationnelles tout en gagnant en efficacité. Grâce à ces technologies émergentes, les pratiques de production et de gestion des données sont régulièrement affinées. Les organismes gouvernementaux étatsuniens et leurs partenaires exploitent des laboratoires de confinement à haute sécurité qui font appel aux IT/OT pour mettre en oeuvre des fonctionnalités scientifiques cruciales en appui de la prévention, la détection, l'intervention et le rétablissement en cas de catastrophes. Ces environnements opérationnels uniques offrent la possibilité d'introduire des applications IT/OT afin de faciliter aussi bien l'efficacité des opérations que l'étude plus approfondie ou concomitante d'une maladie et des phénomènes biologiques qui lui sont associés. Des études opérationnelles menées par des spécialistes peuvent contribuer à identifier les exigences et les défis liés aux IT/OT émergentes, à vérifier leurs utilisations concrètes, à affiner les spécifications techniques et à optimiser l'ordonnancement des opérations. Le National Bio and Agro-Defense Facility (NBAF) des états-Unis d'Amérique, qui devrait être pleinement opérationnel d'ici 2023, sera une institution de recherche et de diagnostic de pointe dotée de laboratoires de niveaux de biosécurité 2, 3 et 4 pour l'étude des agents pathogènes responsables de maladies animales transfrontalières à haut risque et des agents zoonotiques à fort impact sur la santé publique. Le NBAF contribuera au diagnostic des maladies émergentes et à l'élaboration de mesures de lutte ; il dispensera également des formations sur les maladies animales transfrontalières. Compte tenu du développement rapide des nouvelles solutions IT/OT, les auteurs ont mis au point une méthode d'études de cas pour l'analyse et l'évaluation des fonctionnalités concrètes des laboratoires de confinement à haute sécurité, destinée à maximiser l'efficacité des prestations du NBAF et du réseau plus large de laboratoires de confinement à haute sécurité. La méthode par études de cas décrite ici pourrait être largement adaptée à diverses situations caractérisées par un niveau élevé de changement, afin de fournir des analyses précises et pertinentes de l'ordonnancement des opérations et d'élaborer des recommandations optimisées.

Los adelantos de las tecnologías de la información (TI) y las tecnologías operativas (TO) ofrecen a los laboratorios de alta contención la posibilidad de transformar sus lógicas y procedimientos de trabajo científico y al mismo tiempo ganar en eficiencia. Progresivamente, a la estela de las nuevas tecnologías, los métodos empleados para generar y gestionar datos van evolucionando. Ciertos organismos públicos estadounidenses administran, junto con entidades colaboradoras, laboratorios de alta contención que dependen de las TI/TO para cumplir una serie de cometidos científicos fundamentales en apoyo de la prevención y detección de sucesos catastróficos, de la respuesta a ellos y de los subsiguientes procesos de recuperación. Estos excepcionales entornos de trabajo ofrecen la posibilidad de implantar TI/TO que a la vez aporten más eficiencia y faciliten un estudio más a fondo o en paralelo de as enfermedades y los fenómenos biológicos asociados a ellas. La realización de estudios operativos a cargo de especialistas en el tema puede ayudar a determinar las necesidades y dificultades que plantean las nuevas TI/TO, a examinar ejemplos de utilización, a afinar las especificaciones técnicas y a optimizar los procesos de trabajo. El órgano nacional de defensa biológica y agrícola (National Bio and Agro-Defense Facility, NBAF) de los Estados Unidos de América, que según las previsiones funcionará a pleno rendimiento en 2023, constituirá un avanzado dispositivo de investigación y diagnóstico al que estarán adscritos laboratorios de nivel 2, 3 y 4 de seguridad biológica para el estudio de agentes patógenos de los animales y enfermedades zoonóticas de carácter transfronterizo y de gran repercusión que afecten a la salud pública. El NBAF secundará el diagnóstico de enfermedades emergentes, la preparación de medidas de lucha y la formación sobre enfermedades animales transfronterizas. Teniendo en cuenta la velocidad a la que surgen soluciones de TI/TO, los autores recurrieron al estudio de ejemplos concretos para analizar y evaluar las funciones que cumplen en el mundo real los laboratorios de alta contención con el objetivo de ayudar al NBAF y a la red general de laboratorios de alta contención a ejercer su cometido con la máxima eficiencia. El método de trabajo aquí descrito, basado en el estudio de casos concretos, podría ser adaptado a diversas situaciones que se caractericen por un alto ritmo de transformaciones para efectuar análisis precisos y pertinentes de los procesos de trabajo y formular recomendaciones optimizadas.

Pelvic positioning in the supine position leads to more consistent orientation of the acetabular component after total hip arthroplasty.

AIMS: This study aims to: determine the difference in pelvic position that occurs between surgery and radiographic, supine, postoperative assessment; examine how the difference in pelvic position influences subsequent component orientation; and establish whether differences in pelvic position, and thereafter component orientation, exist between total hip arthroplasties (THAs) performed in the supine versus the lateral decubitus positions. PATIENTS AND METHODS: The intra- and postoperative anteroposterior pelvic radiographs of 321 THAs were included; 167 were performed with the patient supine using the anterior approach and 154 were performed with the patient in the lateral decubitus using the posterior approach. The inclination and anteversion of the acetabular component was measured and the difference (Δ) between the intra- and postoperative radiographs was determined. The target zone was inclination/anteversion of 40°/20° (± 10°). Changes in the tilt, rotation, and obliquity of the pelvis on the intra- and postoperative radiographs were calculated from Δinclination/anteversion using the Levenberg-Marquardt algorithm. RESULTS: The mean postoperative inclination/anteversion was 40° (± 8°)/23° (± 9°) with Δinclination and/or Δanteversion > ± 10° in 74 (21%). Intraoperatively, the pelvis was anteriorly tilted by a mean of 4° (± 10°), internally rotated by a mean of 1° (± 10°) and adducted by a mean of 1° (± 5°). Having Δinclination and/or Δanteversion > ± 10° was associated with a 3.5 odds ratio of having the acetabular component outside the target zone. A greater proportion of THAs that were undertaken with the patient in the lateral decubitus position had Δinclination and/or Δanteversion > ± 10° (35.3%, 54/153) compared with those in the supine position (4.8%, 8/167; p < 0.001). A greater number of acetabular components were within the target zone in THAs undertaken with the patient in the supine position (72%, 120/167), compared with those in the lateral decubitus position (44%, 67/153; p < 0.001). Intraoperatively, the pelvis was more anteriorly tilted (p < 0.001) and more internally rotated (p = 0.04) when the patient was in the lateral decubitus position. CONCLUSION: The pelvic position is more reliable when the patient is in the supine position, leading to more consistent orientation of the acetabular component. Significant differences in pelvic tilt and rotation are seen with the patient in the lateral decubitus position. Cite this article: Bone Joint J 2018;100-B:1280-8.

Effect of maximal and slow versus recreational muscle contractions on energy expenditure in trained and untrained men.

AIM: The primary purpose of this study was to compare energy expenditure among resistance exercise protocols using maximally explosive or slow contractions versus recreational in trained and untrained men. METHODS: Seven trained (21.9±2.1 yrs) and seven untrained men (20.1±2.2 yrs) performed three nearly identical exercise protocols, and a no-exercise (CONTROL) session in a randomly assigned, counterbalanced order. Subjects performed three sets of squats, dumbbell-row, deadlift, bench press, lat-pulldown, shoulder press, arm curls and dips using either recreational (REC), 2s (SLOW) or maximally explosive contractions (MAX). Expired air was collected continuously for 15 min before, ~37-43 min during, and 2 hr postexercise. Finger prick samples (25 µL) were collected and analyzed for blood lactate (BL) (mmol.L-1) before, immediately after, and during 120 min of recovery. RESULTS: Rates of energy expenditure were significantly (P≤0.05) greater for MAX than SLOW and REC during all exercises and +5 min after exercise in trained men, and MAX was greater than REC during all exercises except deadlift in untrained men. In trained men, total kcal were significantly greater (P≤0.05) with MAX (507±48) compared to REC (431±47), but not in untrained. Conversely, BL was significantly greater (P≤0.05) after SLOW compared to REC in trained and untrained men, while BL was only greater after MAX versus REC in trained men. CONCLUSION: For whole-body resistance exercise programs, maximally explosive contractions optimize energy expenditure in trained men, but slow contractions are recommended for untrained exercisers. Therefore, contraction intensity should be considered a program design variable for exercise prescriptions aimed to improve general health and fitness.

Importance of methicillin-resistant Staphylococcus aureus eradication in carriers to prevent postoperative methicillin-resistant Staphylococcus aureus surgical site infection.

Although infrequent, postoperative methicillin-resistant Staphylococcus aureus (MRSA) surgical site infection (SSI) is associated with significant morbidity and cost. Previous studies have identified the importance of MRSA screening to diminish the risk of postoperative MRSA SSI. The current study quantifies the importance of eradication of the MRSA carrier state to prevent MRSA SSI. Beginning February 2007, all admissions to an 800-bed tertiary care hospital were screened for MRSA by nasal swab using rapid polymerase chain reaction-based testing. Patients found to be nasal carriers of MRSA were treated with 2 per cent mupirocin nasal ointment and 4 per cent chlorhexidine soap before surgery. The subset of patients undergoing procedures that are part of the Surgical Care Improvement Project (SCIP) were followed for MRSA SSI (n = 8980). The results of preoperative MRSA screening and eradication of the carrier state were analyzed. Since the initiation of universal MRSA screening, 11 patients undergoing SCIP procedures have developed MRSA SSI (0.12%). Of these, six patients (55%) had negative preoperative screens. Of the five patients with positive preoperative screens, only one received treatment to eradicate the carrier state. In patients who develop MRSA SSI, failure to treat the carrier state before surgery results in MRSA SSI.

Active surveillance screening of MRSA and eradication of the carrier state decreases surgical-site infections caused by MRSA.

BACKGROUND: Surgical-site infections (SSI), because of MRSA, are a challenge for acute care hospitals. The current study examines the impact of best practices and active surveillance screening for MRSA on reduction of MRSA SSIs. STUDY DESIGN: Beginning February 2007, all admissions to a 761-bed tertiary care hospital were screened for MRSA by nasal swab using polymerase chain reaction-based testing. Positive nasal carriers of MRSA were treated before operation. The subset of patients undergoing procedures that are part of the Surgical Infection Prevention Project were followed for MRSA SSIs. SSI rates (per 100 procedures) were determined using the National Nosocomial Infection Surveillance definitions. MRSA SSI rates were compared before and after the MRSA screening intervention. Differences were analyzed using Fisher's exact test and chi-square with Yate's continuity correction. Where specimens were available, genotyping of MRSA was performed using a commercially available assay. RESULTS: After universal MRSA surveillance, 5,094 patients underwent Surgical Infection Prevention Project procedures. The rate of MRSA SSI decreased from 0.23% to 0.09%. The reduction was most pronounced in joint-replacement procedures (0.30% to 0%; p = 0.04). No other differences were statistically significant. Of the seven patients in whom MRSA SSI developed after universal screening, four had positive MRSA screens; none had received preoperative eradication of MRSA. In two of these patients, the genotype of MRSA detected on screening and in SSI was genetically indistinguishable. CONCLUSIONS: Surveillance for MRSA and eradication of the carrier state reduces the rate of MRSA SSI.

The effect of calcitriol on fasting urine calcium loss and renal tubular reabsorption of calcium in patients with mild renal failure--actions of a permissive hormone.

AIM: Renal production of 1,25-dihydroxycholecalciferol is attenuated in early renal failure. Renal tubular reabsorption of calcium is diminished in moderate renal failure and we wished to see if this were true in the early stages and whether supplementary calcitriol would bring about correction. We were interested in the idea of 1,25-dihydroxycholecalciferol being a permissive agent, operating indirectly. METHODS: We measured calcium-related variables, including calculated ultrafiltrable serum calcium, before and after calcitriol 0.5 microg daily for six days in 34 subjects with stable mild renal failure. RESULTS: The mean serum creatinine was 0.21 (+/- 0.08) mmol/l. The mean serum Ca++ was normal (1.18 mmol/l) but nine patients had values outside the normal range and in six cases, with low-normal serum Ca++ levels, there was a diminished tubular reabsorption. In five cases, basal serum Ca++ was mildly elevated. The coefficient of variation for serum Ca++ was 4.4%. PTH (1-84) levels were mildly elevated and 1,25-dihydroxycholecalciferol levels low-normal. The urine Ca/Cr, representing net bone resorption, was elevated in six cases. After calcitriol, the mean serum Ca++ level rose slightly and the coefficient of variation decreased to 3.6%. Changes in Ca++ whether upward or downward were accounted for by minor alterations in tubular reabsorption and a tendency to less net bone resorption. The initial Ca++ predicted (negatively) the magnitude of the correction. Neither the prevailing PTH nor the 1,25-dihydroxycholecalciferol levels explained any of the observed changes. CONCLUSION: In early renal failure, there may be impaired regulation of serum Ca++. Despite elevated PTH, mild hypocalcemia may exist in the presence of increased net bone resorption relative to GFR. Hypocalcemia was accounted for by reduced renal tubular reabsorption of calcium which corrected after calcitriol. Net bone resorption tended to fall after calcitriol. Mild hypercalcemia, when present, was corrected by a reduction in tubular reabsorption. Calcitriol did not have a simple unidirectional effect but instead contributed to efficiency of the homeostatic mechanisms controlling the serum Ca++ set-point.

Fetal heart rate decelerations during ECT-induced seizures: is it important?

Electroconvulsive therapy (ECT) is sometimes indicated during pregnancy and may offer advantages over pharmacotherapy for the patient and the fetus (1,2). However, very little data is available on the impact of epileptic or ECT-induced seizures on the fetus. We report a case of brief fetal heart rate decelerations in a fetus associated with maternal ECT-induced convulsions.

Limited effect of recombinant porcine interleukin-12 on porcine lymphocytes due to a low level of IL-12 beta2 receptor.

The cytokine interleukin-12 (IL-12) is a key molecule in the regulation of CD4 + T cell development and specifically potentiates T helper 1 responses in mouse and man. However, biological effects mediated by IL-12 have not been well defined in pigs. Herein, recombinant porcine IL-12 (rPoIL-12) was expressed in a swine poxvirus system as a biologically active heterodimer and used to stimulate bovine or swine lymphoblast cells. After 3 days of incubation, only bovine blasts were responsive to the rPoIL-12 treatment as monitored by cell proliferation in several independent trials. Similarly, i.m. administration of rPoIL-12 in the hind leg of 3-week-old pigs indicated a reduction in the number of interferon-gamma (IFN-gamma) producing lymphocytes isolated from inguinal lymph nodes. The porcine IL-12R beta2 (IL-12Rbeta2) sequence was cloned and results generated by reverse transcriptase polymerase chain reaction (RT-PCR) demonstrated that the expression of IL-12R on porcine blasts as measured by the relative levels of IL-12Rbeta2 mRNA was less than that in bovine blasts and are in agreement with the reduced proliferation response of swine blast cells to rPoIL-12 treatment. Real time PCR analysis demonstrated that after PBMC stimulation, bovine blasts had an 11-fold increase in IL-12Rbeta2 mRNA levels while porcine blasts had almost no change. These data support a mechanism for IL-12 stimulation in swine inconsistent with that observed in conventional models.

Technique on restoring cervical lesions.

This paper describes a technique of placing a semi-rigid cervical matrix slightly past the cervical border of a lesion that extends below (apical to) the gingival crest and inserting the glass ionomer cement through an opening cut in the matrix above the soft tissue level.

Degradation of bleaching gels in vivo as a function of tray design and carbamide peroxide concentration.

This study determined the degradation of nine bleaching agents with different concentrations after two hours in vivo following the manufacturers' recommendations. The nine carbamide peroxide products are 10%, 15% and 20% Opalescence, 10%, 15% and 22% Rembrandt and 10%, 16% and 22% Nite White Excel 2. Each subject wore the tray with the bleaching agent for two hours on three separate occasions. The amount of remaining carbamide peroxide was determined after each use. Evaluation of remaining amount of carbamide peroxide was calculated by the US Pharmacopeia method. The study showed that the total carbamide peroxide percent recovered was significantly higher for Opalescence products (47% to 54%) compared to Nite White (22% to 25%) and Rembrandt bleaching gels (15% to 16%). It concluded that this difference was mostly due to the use of facial reservoirs with Opalescence products, and also that whitening gel in trays with reservoirs and trays without reservoirs degraded at the same rate.

A clinical evaluation of a bleaching agent used with and without reservoirs.

This in vivo study evaluated the variation of tray fabrication (trays constructed with or without reservoirs) on the degree of color change of teeth and sensitivities associated with using a 15% carbamide peroxide bleaching agent for two hours once daily for 14 days. Patients returned in one, two, three, six and 12 weeks. Color changes were evaluated by subjective shade matching, comparing clinical photographs and through measurements obtained using a color-measuring device. Subjects were asked to keep a daily record of any tooth and gingival sensitivity on the right and left side of their maxillary dental arch for three weeks. Colorimeter data showed that teeth lightened with agent with reservoirs were significantly lighter than teeth lightened with the same agent without reservoirs. However, the amount of lightening was below the threshold of visual differentiation. Shade guide and slide photography data showed no significant differences between teeth lightened with agent with reservoirs compared to teeth lightened with the same agent without reservoirs. In addition, no significant differences in tooth and gingival sensitivity were found between the tray side with reservoirs and those without reservoirs.

Advances in cooled semen technologies: seminal plasma and semen extender.

This study evaluated motility and fertility of uncentrifuged and centrifuged equine semen following dilution in a skim milk-glucose extender with or without supplemental Tyrode's medium. In addition, the effect of seminal plasma addition to each extender was evaluated. For Experiment 1, motility of 48h cooled, stored spermatozoa was evaluated following eight dilution treatments: uncentrifuged and diluted 1:4 (v/v) in skim milk-glucose extender (EZ Mixin CSTJ; CST-1:4) or in CST supplemented 65:35 (v/v) with modified Tyrode's medium (KMT-1:4); uncentrifuged and diluted to 25x10(6) spermatozoa/ml in CST (CST-1:9) or in KMT (KMT-1:9); centrifuged and diluted in CST with 0% seminal plasma (CST-0) or 20% seminal plasma (CST-20) or centrifuged and diluted in KMT containing 0% seminal plasma (KMT-0) or in KMT containing 20% seminal plasma (KMT-20). Sperm motility parameters evaluated included percentage of total motile sperm (% TMOT), percentage of progressively motile sperm (% PMOT), curvilinear velocity (VCL) and straight-line velocity (VSL). Mean % PMOT was lower (P<0.05) for spermatozoa extended in CST-1:4 compared to CST-1:9, whereas, all motility parameters were reduced (P<0.05) in KMT-1:4 compared to KMT-1:9. Spermatozoa extended in CST-1:4 had greater % TMOT, % PMOT and VSL (P<0.05) than in KMT-1:4. Spermatozoa extended in CST-1:9 had greater (P<0.05) % PMOT than in KMT-1:9, however, VCL was greater (P<0.05) in KMT-1:9. Mean VCL and VSL were lower (P<0.05) for spermatozoa extended in CST-0 compared with CST-20, whereas, spermatozoa extended in KMT-0 had greater (P<0.05) % TMOT, % PMOT and VSL compared to spermatozoa extended in KMT-20. Mean % TMOT and % PMOT were greater (P<0.05) in CST-20 compared to KMT-20, however, KMT-0 increased (P<0.05) velocity measures (VCL and VSL) compared to CST-0. In Experiment 2, fertility of centrifuged spermatozoa diluted in either CST-20 or KMT-0 was similar (P>0.05). We conclude that modified Tyrode's medium was not detrimental to establishment of pregnancy. Use of modified Tyrode's medium may improve spermatozoal motility and pregnancy rates for cooled transport of semen from stallions in which all seminal plasma must be removed because of suspected toxic effects of seminal plasma on spermatozoal viability, however, Tyrode's medium may be detrimental to sperm motility when seminal plasma is present.

Effect of monthly intravenous cyclophosphamide in rapidly deteriorating multiple sclerosis patients resistant to conventional therapy.

Fourteen consecutive clinically definite relapsing-remitting multiple sclerosis (MS) patients were treated with monthly intravenous cyclophosphomide (CTX) for 6 months. All had experienced severe dinical deterioration during the 12 months prior to treatment with CTX despite treatment with conventional immunomodulating agents and intravenous methylprednisolone. Treatment with CTX led to improvement and neurologic stability within 6 months which was sustained for at least 18 months after the onset of treatment with CTX. Therapy with CTX was well tolerated. CTX may be of benefit in MS patients who experience rapid clinical worsening and are resistant to conventional therapy.

Stroke after bone marrow transplantation: frequency, aetiology and outcome.

Few data exist on the frequency, aetiology and outcome of cerebrovascular complications of bone marrow transplantation (BMT). We reviewed all patients undergoing BMT at the Fred Hutchinson Cancer Research Center, Seattle, Wash., USA (a large referral institution) over 3 years. We reviewed ICD-9 (International Classification of Diseases) codes for ischaemic stroke, seizure, intracranial haemorrhage and brain infection. Using standardized forms, we paid detailed attention to clinical features and demographics, oncological diagnosis, conditioning regimens, neurological history, comorbidities, time from BMT to ictus, stroke subtype, radiological and pathological features, and outcomes. We identified 36 patients with stroke from 1245 patients who had BMT (2.9%) over 3 years. These patients' median age was 35 (range 5-60, interquartile range 25-45) years. The most common causes of stroke were intracranial haemorrhage related to thrombocytopenia (38.9%) and infarction or haemorrhage secondary to fungal infection (30.6%). Twenty-five patients (69.4%) died from their stroke; none survived without disability. Using a logistic regression model, we found that neither demographic (e.g. age, gender) nor clinical (e.g. oncological diagnosis, type of BMT, time of stroke after BMT) factors predicted outcome. Stroke occurs relatively frequently (incidence almost 3%) after BMT, has a relatively high frequency of infection-triggered events, has a neurological outcome not easily predicted from available data and is often fatal.

Microleakage of posterior packable resin composites with and without flowable liners.

The use of flowable composites as liners in Class II packable composites has been suggested by some manufacturers. However, the contributions of this technique are unproven. This study evaluated marginal microleakage in Class II packable composite restorations with and without the use of a flowable composite liner. A conventional microhybrid composite was used as a control. Microleakage at occlusal and gingival margins of Class II cavities was evaluated using 45Ca and autoradiographs. Fifty non-carious, restoration-free human molar teeth were used. Separate mesio-occlusal and disto-occlusal Class II cavity preparations were made in each tooth. Gingival margins of all cavities were placed 1 mm apical to the cementoenamel junction (CEJ). Four Packable composites (Alert, Surefil, Pyramid and Solitaire) and one conventional microhybrid composite (Renew) with their respective manufacturer's bonding agents were used to restore the cavities. One side of each tooth was restored with composite alone, while the other side was restored with the composite lined with that manufacturer's flowable liner. The restored teeth were thermally stressed and 45Ca was used to evaluate microleakage. Two independent evaluators scored leakage based on the autoradiographs. The results showed flowable composites helped reduce microleakage at gingival margins of Class II restorations (p < 0.05). Gingival margins had higher microleakage than occlusal margins (p < 0.05). Without flowable liners, three packable composites (Alert, Pyramid and Surefil) showed higher leakage (p < 0.05) than the microhybrid control. Only Solitaire packable composite without liner showed no significant difference in microleakage to the control (p > 0.05). Although the flowable liners help reduce microleakage, Alert and Pyramid packable composites with liners still showed higher leakage than the control (p < 0.05). Surefil and Solitaire packable composites with flowable liners showed no significant difference in microleakage (p > 0.05) to the control.

A clinical evaluation of carbamide peroxide and hydrogen peroxide whitening agents during daytime use.

BACKGROUND: Vital tooth bleaching for esthetic reasons has gained in popularity during the last few years. However, few studies have investigated the efficacy of daytime bleaching products. The purpose of this double-blind in vivo study was to evaluate the efficacy of 20 percent carbamide peroxide, or CP, and 7.5 percent hydrogen peroxide, or HP, during daytime use. The degree of color change, any color relapse, and tooth or gingival sensitivity were evaluated. METHODS: Twenty-four patients participated in this study. The bleaching gels were randomly applied to the right and left maxillary anterior teeth. Patients were shown how to place the two bleaching agents in a custom tray for one hour, twice a day for two weeks. Patients returned in one, two, three, six and 12 weeks for color evaluation with the colorimeter and shade guides as well as to have color slide photographs taken. The authors evaluated sensitivity by asking the patients to record daily for 21 days any tooth or gingival sensitivity they experienced. RESULTS: Use of the 20 percent CP resulted in significantly more lightness than the 7.5 percent HP during the first 14 days of the study, but at the end of the study, there was no significant difference between products with regard to tooth lightness. In addition, the authors found no statistically significant difference between products with regard to gingival or tooth sensitivity. CONCLUSIONS: Both CP and HP are effective at-home bleaching agents when daytime bleaching is preferred. CLINICAL IMPLICATIONS: Dentists who choose to use daytime bleaching can select either CP or HP.