Robert L. Cooley

SEM evaluation of etch patterns by three etchants on three porcelains

Three etchants (Super Etch, Stripit, and Acidulated Phosphate Fluoride Gel) were evaluated for their ability to create micromechanical retentive areas in three commercial porcelains (Ceramco II, Mirage, and Vita).

Bond strength of light-cure fluoride-releasing base-liners as orthodontic bracket adhesives

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.

Evaluation of a digital pulp tester

An evaluation of a new-generation digital pulp tester revealed some significant advantages over the conventional, manually operated type. Its automatic operation and comfortable stimulation of the tooth could make this instrument a valuable addition to the dental armamentarium.

The effect of an air-powder abrasive instrument on composite resin

Three composite resins were subjected to applications of sodium bicarbonate with an air-powder abrasive instrument. Materials tested were a microfilled, a conventional, and a light-cured composite resin. Samples were tested for surface roughness before and during applications. The applications produced significant increases in roughness. It was concluded that the light-cured composite resin should be the material used for patients undergoing a recall maintenance program in which the instrument is used.

Evaluation of potassium oxalate as a cavity liner

All dental restoratives exhibit some microleakage. Recent studies disclosed that oxalate salts were superior to Copalite varnish in reducing dentinal permeability, but inferior in reducing microleakage. This study compared the effectiveness of a potassium oxalate solution (DDS) with three other cavity liners (Copalite, Cavi-Line, Prisma Universal Bond) and a no-liner control in reducing microleakage under amalgam restorations. Under the conditions of this study, DDS solution was significantly effective in reducing microleakage under amalgam restorations.

Endodontic flap design: Analysis and recommendations for current usage

An endodontic flap design, which may be used as an alternative to the presently described endodontic flaps, is presented. This flap involves a full-thickness dissection with easily recognizable landmarks and straight-line incisions. A beveled horizontal incision is designed to incorporate the maximum amount of facial keratinized tissue into the body of the flap, while leaving the interproximal tissues untouched. The resultant flap is easily replaced with interrupted sutures to the stable interproximal papillae. Healing is rapid, with excellent esthetic results.

Dimensional stability of glass ionomer used as a core material

This laboratory study evaluated the dimensional stability of two reinforced glass ionomers (Ketac-Silver and Fuji Miracle Mix) in comparison with amalgam. Ten core build-ups were prepared with each material on extracted human teeth. Four Minim pins were placed in each tooth for retention. A gold casting was made for each core build-up. The specimens were placed in a distilled water and the distance between the casting and the tooth was measured at 1 hour, 6 hours, and then every 24 hours for 7 days. After 7 days, the measured changes were small, ranging from 1 to 63 microns. The reinforced glass ionomers were found to be dimensionally stable in moisture over a period of 7 days.

Formaldehyde emitted by chemical vapor sterilizers

Formaldehyde has been identified as a potential occupational carcinogen and is a component of chemical solutions used in chemical vapor sterilizers. This study evaluated room air for formaldehyde in rooms where chemical vapor sterilizers were in use.