Biomedical subjects
Publications and source records attributed to J W McCourt.
We report on a newborn girl with multiple congenital anomalies, whose G-banded chromosome analysis showed complete trisomy 22. Chromosome painting using a whole-chromosome painting probe for chromosome 22 confirmed that neither chromosome 22 was involved in a cryptic translocation.
The purpose of this project was to test the in vitro bond strength of three dentinal bonding agents to primary dentin. Scotchbond 2, All-Bond, and Amalgambond were applied to 63 teeth according to manufacturer's instructions. Valux composite resin was placed in a cylindrical matrix and light cured to the treated dentin. After they were thermocycled for approximately 800 cycles between 6 degrees C and 60 degrees C, the specimens were mounted in stone and placed in an Instron universal testing machine. They were placed under continuous load until failure. Fracture was at the dentin-bonding agent interface for all materials tested. Incisor bond strength was significantly stronger than molar bond strength for all three materials. Materials analysis revealed that the mean bond strength for Scotchbond 2 (6.99 MPa) was significantly different from those of All-Bond (13.01 MPa) and Amalgambond (13.03 MPa).
Fluoride-releasing bracket adhesives are desirable for their ability to minimize the potential for subsurface enamel demineralization adjacent to a bonded bracket. Self-applications with topical fluoride rinses, pastes, and gels have been documented to minimize and eliminate subsurface caries adjacent to bonded brackets. However, the success of these mediums are limited by patient compliance. A urethane with fluoride (TimeLine) and a glass ionomer with methyl methacrylate (Vitrabond), both of which are light cured and exhibit sustained fluoride ion release, were compared with a non-fluoride-releasing light-cured bracket adhesive (Transbond). Premolar brackets with mesh pads (A-Company) were positioned on the buccal surface of the premolars and placed in a PVC ring with polymethyl methacrylate. Two groups of 10 samples each of the tested material were prepared and immersed in distilled water immediately after in vitro bonding. Samples of each material were evaluated for enamel shear strength (Instron) at 24 hours and at 30 days. Bond strengths to enamel at 24 hours measured in megapascals (MPa) were 5.98 for TimeLine, 11.58 for Vitrabond, and 11.35 for Transbond. Bond strength to enamel at 30 days was found to be significantly less for TimeLine and Vitrabond: 3.05 for TimeLine, 5.39 for Vitrabond, and 10.80 for Transbond. The two fluoride-releasing, light-cured materials tested have low bond strengths after 30 days and are not acceptable as orthodontic bracket bonding agents. However, for patients with high caries risk, these materials may be placed around already bonded brackets.
We describe evolving dermatologic findings in a male with progeria from age 1 month to 21.5 months. At 18 months of age, irregular pigmentary changes of the abdomen, early occipital alopecia, superficial scalp veins, glyphic nasal tip, absent ear lobules, coarse hair that stands on end, crowded dentition with delayed tooth development, and dystrophic nails permitted the diagnosis of progeria. Radiographs showed evidence of resorption of the distal ends of the clavicles, attenuation of the terminal phalanges, diffuse osteopenia, and fishmouth vertebral bodies, which are typical of this syndrome. Appreciation of the evolution of early dermatologic findings may permit earlier diagnosis of this condition in infants with skin changes.
Coxsackie virus infections are highly contagious and can occur at epidemic levels within low socioeconomic populations. Since these diseases spread by contact, summer and fall occurrences increase significantly. A low grade fever and malaise are often related to non-specific viral infections. Hand-foot-and mouth disease (HFMD) is specifically caused by coxsackie virus.
A method was developed to give removable appliances a fluoride-releasing capability. Visible light-cured glass-ionomer cement inserts were made, placed in resins commonly used for removable appliances, and evaluated for fluoride release over a 2-month period. Fluoride release was measured daily for 7 days, weekly for 4 weeks, and monthly for 1 month. All specimens released fluoride at every time period. There was a "burst effect" in which more fluoride was released the first day, but the amount released decreased significantly on the second day. The amount of fluoride released decreased at each of the daily and weekly measurements, but became relatively stable after 7 days. All specimens were still releasing fluoride at the end of the 2-month test period.
Five new visible light-curing cavity liners/bascs that contain fluoride were evaluated for fluoride release over a 17-week period. Fluoride was released from all the materials, but the level of fluoride release decreased significantly (P less than .01) over the test period. There was also a statistically significant (P less than .05) difference among the materials in the amount of fluoride released.
A fluoride-containing sealant (FluroShield) was evaluated in vitro and compared to a sealant without fluoride (Helio-Seal). Both materials were applied to the occlusal surface of extracted teeth and microscopically evaluated for their ability to penetrate pits and fissures. Additional specimens were subjected to dye immersion and evaluated for resistance to microleakage. Disc-shaped samples of the fluoride-containing sealant were immersed in distilled water and analyzed daily for seven days for fluoride release. All specimens of FluroShield released fluoride during the evaluation period, but there were differences between the materials in resistance to microleakage.
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Five new visible light-cure cavity liners/bases that contain fluoride were evaluated for fluoride release over an 8-month period. Fluoride was released from all the materials but decreased significantly over the test period. There was also a significant difference in the amount of fluoride released between the materials. At 8 months, only XR Ionomer and Vitrabond were releasing detectable fluoride, with XR Ionomer releasing significantly more.
A method for fabrication of a fluoride-releasing retainer is described. The insert releases low levels of fluoride, which should promote remineralization and reduce caries potential. Previous research on the amount of fluoride release is also discussed.
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Survey results on the subject of child abuse from the American Society of Dentistry for Children membership are reported. The survey results reflected the need of a documentation protocol for the dental office. A protocol is proposed which reviews the need of thorough assessment of orofacial lesions before concluding that child abuse exists. A data- and diagnostic-assessment form has been made using guidelines of the American Dental Association and other related referenced articles. The diagnostic-assessment form is presented to guide the practitioner through the documentation process and to develop a step-by-step decision on the probability of child abuse in any individual case.