Universal pre-mixing dry-film stickers capable of retrofitting existing microfluidics.

Integrating microfluidic mixers into lab-on-a-chip devices remains challenging yet important for numerous applications including dilutions, extractions, addition of reagents or drugs, and particle synthesis. High-efficiency mixers utilize large or intricate geometries that are difficult to manufacture and co-implement with lab-on-a-chip processes, leading to cumbersome two-chip solutions. We present a universal dry-film microfluidic mixing sticker that can retrofit pre-existing microfluidics and maintain high mixing performance over a range of Reynolds numbers and input mixing ratios. To attach our pre-mixing sticker module, remove the backing material and press the sticker onto an existing microfluidic/substrate. Our innovation centers around the multilayer use of laser-cut commercially available silicone-adhesive-coated polymer sheets as microfluidic layers to create geometrically complex, easy to assemble designs that can be adhered to a variety of surfaces, namely, existing microfluidic devices. Our approach enabled us to assemble the traditional yet difficult to manufacture "F-mixer" in minutes and conceptually extend this design to create a novel space-saving spiral F-mixer. Computational fluid dynamic simulations and experimental results confirmed that both designs maintained high performance for 0.1 < Re < 10 and disparate input mixing ratios of 1:10. We tested the integration of our system by using the pre-mixer to fluorescently tag proteins encapsulated in an existing microfluidic. When integrated with another microfluidic, our pre-mixing sticker successfully combined primary and secondary antibodies to fluorescently tag micropatterned proteins with high spatial uniformity, unlike a traditional pre-mixing "T-mixer" sticker. Given the ease of this technology, we anticipate numerous applications for point-of-care devices, microphysiological-systems-on-a-chip, and microfluidic-based biomedical research.

Gentamicin binding to serum and plasma proteins.

Gentamicin binding to serum proteins was studied by equilibrium dialysis at 37 degrees C and pH 7.4 in the presence of both physiologic and adjusted concentrations of ionized calcium and magnesium. The percentage of bound drug was inversely related to the concentration of these two divalent cations, raning from 27% bound with no calcium and magnesium present to 17% bound in the presence of four times physiologic concentrations. No significant difference in the extent of drug-protein binding was noted in a comparison of sera from healthy and uremic subjects. Heparin also was found to affect gentamicin binding. Increasing heparin concentration in serum increased apparent gentamicin-protein binding to 34% in the presence of physiologic amounts of calcium and magnesium. Buffered heparin solutions without plasma proteins bound up to 65% of total drug concentration. Gentamicin-protein binding may have implications regarding pharmacokinetics and renal cortical uptake.

The role of race and ethnic status on the psychosocial correlates of smokeless tobacco use in adolescent males.

From a stratified, random sampling of non-urban high schools in the Southeast, survey data were obtained from 5374 adolescent males. Over half reported trying smokeless tobacco, and approximately one third of these reported a regular, substantial level of use. The average age at initial use was 12.2 yr. and was negatively correlated with the level of use. Factor analysis of the psychosocial items resulted in four factors: substance use/deviant style, modeling, perceived negative consequences, and health behavior. Discriminant analysis of initial use indicated that substance use and modeling influences were the strongest predictors of trying smokeless tobacco. Regression analysis of level of smokeless tobacco use indicated that substance use, modeling, and perceived negative consequences were equivalent in their contribution. Separate analyses were performed for American Indian, Black, and White males. Although predictors of initial use were similar, level of smokeless tobacco use was most associated with the use of other substances in Blacks and with modeling influences in Whites.

Marital disturbance and child problems: a cautionary note regarding hyperactive children.

In previous work, investigators have found a relationship between marital discord and childhood conduct problems (aggression) in clinic samples. Given the wide variability of aggression found among hyperactive children, it would follow from previous work that child aggression may be associated with marital discord in a hyperactive population. This hypothesis was tested in a sample of 23 boys (ages 5 to 8) diagnosed as attention deficit with hyperactivity. Aggressive behaviors were tracked by the children's teachers for 12 school days. Parental and teacher ratings of conduct problems were also obtained. Additionally, the auditory version of the laboratory Continuous Performance Test was administered. Marital adjustment, overt hostility, and conflict tactics, as reported by the mothers, were not significantly correlated with any of the measures of aggression or conduct problems. In other words, marital discord in families with a hyperactive boy did not explain differential rates of aggressive behavior despite definite variability in both the marital and child behavioral measures. Marital discord was marginally related to severity of attentional deficit on the Continuous Performance Test. The results underscore the need for caution in attempting to extend findings from a general population (i.e., undifferentiated clinic-referred children) to a specific diagnostic subgroup (i.e., attention-deficit hyperactive children).

Laminate veneer restoration of permanent incisors.

Direct bonding of composite resins to fractured or discolored teeth has been shown to be a practical and effective method for restoring teeth. Previously, lack of uniform shade matching and excessive bulkiness of material have been associated with full veneer bonding. The ultraviolet light (Nuva-Lite) in our studies penetrates veneers as thick as 2 mm and effectively cures the filler material. We also have used cold-curing bonding materials (Concise and Adaptic) and they seem to be equally effective, although working time is shortened. We have had no clinical problems with this technique and after two years the veneers are intact (Fig 6). A technique has been presented that requires no tooth reduction, except where necessary for caries removal, or time-consuming contouring and color shading. Laminate veneers enable the dental practitioner to obtain consistent esthetics with minimal chair time. Further evaluation of this technique to restore malformed, fractured, or discolored permanent incisors is being conducted.

Analyzing dental procedures performed by an HIV-positive dental student.

No evidence of HIV transmission was found between an HIV-positive dental student and 163 treated patients.

Distribution of 14C-formaldehyde after pulpotomy with formocresol.

Pulpotomies were performed on rhesus monkeys with use of formocresol to determine if there was uptake of 14C-formaldehyde into the systemic circulation after formocresol pulpotomies. Five-minute exposure of pulpal tissue to the 14C-formocresol resulted in the systemic absorption of approximately 1% of the dose. Two hours of exposure of pulp tissue to the 14C-formocresol did not increase the systemic absorption. Multiple sequential pulpotomies resulted in proportionately higher systemic absorption of 14C-formaldehyde. Application of 131I to pulpotomy sites indicated that formocresol compromises the microcirculation of the dental pulp. Autoradiography disclosed extensive concentrations of 14C-formaldehyde in the pulp, dentin, periodontal ligament, and bone.

Clinical performance of sealed composite restorations placed over caries compared with sealed and unsealed amalgam restorations.

The 2-year clinical evaluations of paired occlusal restorations are presented. Each study participant received a sealed composite restoration placed over a carious lesion and either a traditional outline-form (unsealed) amalgam or an ultraconservative sealed amalgam restoration. Caries was removed before placement of both types of amalgam restorations. No important clinical differences developed among the three groups of restorations.

Dental radiology for children.

The benefit for the child from the judicious use of diagnostic dental radiography is improved dental health. The risk to the child from dental diagnostic radiation exposure appears to be extremely low. Despite the low risk, the dentist must minimize the child's exposure to ionizing radiation by using sound clinical judgment to determine what radiographs are necessary and to provide children with optimal protection from ionizing radiation.

Cementoblastoma associated with a primary tooth: a rare pediatric lesion.

An intraosseous, slightly painful swelling was noted upon clinical examination of an eight-year-old girl. The swelling was of an unspecified duration and slow growing in nature. A radiopaque mass with a radiolucent periphery attached to the roots of the mandibular right second primary molar was noted on a periapical radiograph. The diagnosis of cementoblastoma was verified by the histologic assessment.

Dentists' perceptions of selected characteristics of their child patients.

The purpose of this project was to examine the perceptions of both general and pediatric dentists regarding selected characteristics of the children they treat. A survey including questions on patients' ages, caries activity estimates, and types of patients treated was mailed once to a national random sample of 2,000 general and 1,000 pediatric dentists. The respondents provided a reasonable distribution by age and location, with the majority (69%) in practice more than 10 years. The pediatric dentists who responded perceive that they treat a younger population of child patients with more caries activity (P < 0.001), except in those patients older than 12 years. They also perceive that their patients pools include a larger percentage of patients with handicapping conditions (P < 0.01), behavior problems (P < 0.001) and patients who require treatment with general anesthesia (P < 0.001) than do the general dentists.

The influence of practice type, region, and age on treatment recommendations for primary teeth.

The purpose of this study was to investigate dentists' treatment recommendations for interproximal surfaces of primary molars based on the type of practitioner (general dentist or pediatric dentist), geographic location, and age of practitioner. Simulated cases, which included histories and pictures of bite-wing radiographs, were mailed to a random sample of 2000 general dentists and 1000 pediatric dentists. Dentists were asked to select their treatment recommendations for eight cases involving the interproximal surface of a specified primary molar. The return rate was 42% (1245) overall, with 36% (723) from general dentists and 52% (522) from pediatric dentists. An amalgam restoration was recommended most often for these eight cases. Dentists in the age 60+ category and pediatric dentists were more likely to recommend treatment for smaller interproximal lesions. Composite resins were recommended infrequently; however, dentists in the 60+ age category and dentists in the Northeast and Southwest were somewhat more likely to recommend composite resin than younger dentists, or dentists in other geographic locations. Dentists in the 40-49 age range, pediatric dentists, and dentists in the Southwest were the most likely to recommend stainless steel crowns. These simulated cases demonstrate differences and similarities in the treatment recommendations for interproximal lesions on primary molars based on age, practice type, and region.

Method of payment for children's dental services by practice type and geographic location.

The purpose of this project was to evaluate practice type and geographical differences in methods of payment accepted for children's dental services. A survey was mailed to 2000 general dentists and 1000 pediatric dentists randomly selected to provide representation from the 50 United States. Dentists were asked to specify the type of practice and the state in which they primarily practice. The survey included Medicaid, dental insurance, preferred provider organizations (PPO), and self-payment as payment options. Dentists were asked to indicate whether they never, occasionally, or frequently accepted each option of payment for children's dental services. Responses were received from 1245 (42%) dentists, including 723 general dentists and 522 pediatric dentists. Chi-square statistical analysis revealed significant practice type and regional differences in the acceptance of Medicaid for payment. Pediatric dentists accept Medicaid more frequently than general dentists (P < 0.001). Most dentists accept dental insurance and self-payment, while few indicate involvement with a PPO. The study revealed significant practice type differences only in the acceptance of Medicaid as payment for children's dental services. On a geographic basis, there were significant differences in the acceptance of Medicaid and dental insurance.

A comparison of general dentists' and pediatric dentists' treatment recommendations for primary teeth.

A survey which included a series of demographic questions, a brief clinical history, and pictures of eight radiographs was mailed to 2000 general dentists and 1000 pediatric dentists. Usable responses were received from 1369 (45%) dentists--765 (38%) general dentists, and 604 (60%) pediatric dentists. The dentists were asked to select the optimal treatment for a specified tooth in each radiograph. The results of this survey indicate that there were differences in the treatment recommendations of general and pediatric dentists. Whether or not pulp therapy was recommended, general dentists frequently recommended restoring teeth with amalgam. Pediatric dentists more frequently recommended restoring primary teeth with stainless steel crowns. There were differences in treatment recommendations within each group of practitioners, as well as between the two groups.

Performance of sealants applied to first permanent molars in a dental school setting.

PURPOSE: The purpose of this study was to assess the performance of sealants placed by senior dental students as part of a comprehensive dental care program that included periodic patient recall. METHODS: The dental records of 100 patients ranging in age from 6 to 13 years were selected for review to determine the treatments provided for first permanent molars over time. Criteria for inclusion were: 1) at least five documented recall examinations and 2) all four first permanent molars had to have been treated with an occlusal pit and fissure sealant. The data collected included: 1) the age of the patient at the time of initial sealant placement; 2) the subsequent treatment provided to the first permanent molars, including retreatment with sealant or restoration and the date the services were provided; 3) the last date of follow-up examination in the pediatric dental program. RESULTS: A total of 400 molars were followed for an average of 54 months. Fifty-two percent of all molars received no further treatment after initial placement of sealant. Approximately 35% received retreatment with sealant only. The total number of molars receiving sealant material only was 343 (86%). The total number of teeth that were judged to require restoration was 57 (14%). No relationship was noted between the patient's age at placement of the occlusal sealant and sealant performance. CONCLUSION: In a dental school clinic, occlusal sealants were effective at preventing caries in a comprehensive care program that included periodic recall.

Comparing treatment options for occlusal surfaces utilizing an invasive index.

The purpose of this project was to develop an invasive index to: 1) compare the treatments recommended by dentists for the occlusal surfaces of molars; 2) compare the invasive index score of each tooth with the extent of the carious lesion as determined by electrical resistance and histological examination; and 3) compare the relative extent of the total crown destruction resulting from the carious lesion and the cavity preparation. Twenty dentists examined 19 extracted permanent molar teeth using a #23 explorer and selected the most appropriate treatment from the following options: no treatment (score 0), occlusal sealant (score 1), preventive resin (score 2), occlusal amalgam (score 3). The invasive index scores determined for each dentist and each tooth were compared using an analysis of variance. The electrical conductivity of each tooth was measured with an electronic caries detector (Vanguard). Electrical resistance scores were compared to the invasive index scores and to a histological examination. The results demonstrate that the invasive index is a useful means to compare treatments recommended by different dentists. The invasive index suggests there is considerable variation among dentists in the treatment they recommend for occlusal surfaces. Electrical resistance testing did not provide helpful information for treatment planning of questionably carious occlusal surfaces.

Radiographic recommendations for the primary dentition: comparison of general dentists and pediatric dentists.

A survey which included brief case histories and intraoral photos of four primary dentitions ranging from healthy to severely carious was mailed to a random sample of 2000 general dentists and 1000 pediatric dentists. Radiographic options were listed, from which the dentist was to indicate all films needed for each child's examination. Surveys were received from 1273 (43%) dentists, including 713 (36%) general dentists and 560 (56%) pediatric dentists. The pediatric dentists recommended significantly more diagnostic radiographs than did the general dentists across all four primary dentition cases. This trend was apparent in the absence of clinically visible caries. When radiographs were recommended, bite-wing radiographs were the most frequently ordered films. The most frequently ordered combination among all respondents was bite-wing radiographs plus anterior periapical films. The results suggest that, frequently, neither general dentists nor pediatric dentists prescribe radiographs for the primary dentition patient that conform to the USDHHS guidelines for radiographic examination (1987).

Radiographic recommendations for the transitional dentition: comparison of general dentists and pediatric dentists.

A survey which included brief case histories and intraoral photos of four transitional dentitions, including examples of ectopic and delayed eruption, as well as carious lesions, was mailed to a random sample of 2000 general dentists and 1000 pediatric dentists. Radiographic options were listed, from which each dentist was to indicate all films needed for each child's examination. Surveys were returned by 1273 (43%) dentists, including 713 (36%) general dentists and 560 (56%) pediatric dentists. The pediatric dentists took significantly more diagnostic radiographs than did the general dentists for each of the four transitional dentition cases. Pediatric dentists were more likely than the general dentists to take panoramic films and combinations which included panoramic films, bite-wing radiographs and periapical films. The most frequently ordered combinations were bite-wing radiographs plus panoramic films and bite-wing radiographs plus anterior periapical films. General dentists recommended bite-wing radiographs films only more frequently than did pediatric dentists. In view of the results of this study and the USDHHS guidelines for radiographic examinations, (1987) education must be provided for both general dentists and pediatric dentists regarding appropriate radiographic examinations for transitional dentition patients.

The use of behavior management techniques by dentists across practitioner type, age, and geographic region.

The purpose of this project was to describe the behavior management procedures employed for child dental patients based on practitioner type (general dentist vs. pediatric dentist), age, and geographic location. A survey of practice characteristics, which included questions relating to child behavior management, was mailed once to a national random sample of 3000 dentists--2000 general dentists and 1000 pediatric dentists. The pediatric dentists who responded employed a broader spectrum of management techniques than did the general dentists. Significant regional and practitioner age differences were reported in the use of behavior management techniques. The use of sedation and general anesthesia was reported more frequently in the western regions. Of the five age groups, the 40- to 49-year-old age group reported using the broadest spectrum of behavior management techniques. The survey revealed practitioner type, age, and regional differences in the child behavior management procedures employed by dentists.

An outcomes assessment of 15 years of patient care experiences in predoctoral pediatric dentistry.

The purpose of this study was to examine the trends in numbers, demographic characteristics, and treatment history of pediatric dental patients under the care of dental students over the period 1980 through 1994. Data were collected for: exams, sealants, surfaces of amalgam, composite resin surfaces, pulpotomies, stainless steel crowns, and extractions. Correlations were done across the 15-year period to determine significant trends over time. During the 15-year period, the average number of patient visits required for each student to complete the requisite number of patients, declined from 45 appointments to complete 10 patients in 1980, to 35 visits to complete 13 patients in 1994. Over time, the numbers of amalgam surfaces, pulpotomies, extractions and stainless steel crowns decreased significantly, while the number of composite resin surfaces increased (P < 0.05). Based on a previous outcome assessment that indicated declining numbers of procedures performed between 1980 and 1985, the required number of patients treated per student was raised from 10 to 13, beginning with the 1986 class.