Quintessence International, 08/1995

This article reviews the uses, advantages, and disadvantages of the different types of resin-bonded prostheses. Resin-bonded prostheses can be used for tooth replacement as well as for occlusal, cosmetic, and orthodontic/periodontic therapy. Proper case selection is essential to their success. Although long-term clinical studies are not available for some of these types of prosthesis, they are generally promising and have become important elements in the provision of dental health care.

A removable partial denture with a lateral path of insertion is useful when unsightly facial clasps are objectional to the patient. Rounded rest seat preparations allow extensions of the minor connector to rotate laterally into embrasure undercuts, providing retention. Guiding planes on the contrlateral side ensure a different path of withdrawal from the retentive elements. A Kennedy Class IV arch with a long edentulous span is used to illustrate the denture design.

Seventy-four reports of emphysematous complications in ambulatory dental patients, published in the English literature between the years 1960 and 1993, are reviewed, and an additional case of subcutaneous, retropharyngeal, and mediastinal emphysema following an impression-taking procedure for a crown preparation is presented. This rare complication occurred mainly in patients in the third and fifth decades of life, after dental procedures on the third molar, in particular during mandibular extractions and treatment on the right side. The use of an air syringe, high-speed handpieces, or their combination was reported in 71% of cases. Centripetal air dissection, with retropharyngeal and mediastinal emphysema, occurred in 35% of the patients, especially following extractions.

A modified impression technique is proposed to simplify chairside procedures for the IMZ implant system. This techique saves time and reduces the need for a comprehensive stock of system components. It further facilitates the fabrication of suprastructures on convergently or divergently placed implants.

Injection of local anesthetic is not the only method of achieving complete control of pain sensation during restorative dentistry for very young patients. Transcutaneous electronic nerve stimulation, also known as electronic anesthesia, can be used solely or in combination with nitrous oxide-oxygen inhalation or auditory diversion with music to assure the comfort and safety of some youngsters. This article documents placement of a Class I resin-modified glass-ionomer restoration in a severely carious maxillary primary first molar of a 27-month-old girl. Electronic anesthesia and nitrous oxide-oxygen inhalation were used in lieu of an anesthetic injection.

A case of severe mucogingival argyria secondary to leakage around and corrosion of silver cone root canal obturations and apical amalgam restorations is presented. Following removal of the silver points and re-treatment of the root canals, periradicular surgery was performed to remove the amalgam root-end restorations and reduce the amount of dispersed metallic particles in the subctaneious tissues. Subsequent free gingival grafting created an esthetically pleasing and biologically acceptable result.

Tensile bond strengths of a resin composite-dentinal bonding system to air-abraded enamel were determined. Several cutting variables available on an air-abrasion cavity preparation system were investigated. Two tip diameters, two abrasive powder flow rates, and two air pressures were selected, producing cutting actions that ranged from themost to the lease agressive of the air abrasion system. After enamel surfaces were air abraded, they were etched for 30 seconds with 37% phosphoric acid or not etched. Tensile bond strengths of resin composite to air-abraded, acid-etched enamel were significantly greater than were those to air-abraded, unetched enamel. There was no statistically significant difference between any combination of tip diameter, powder flow rate, or air pressure.

The Marcus Gunn phenomenon and Marin Amat syndrome (inverted Marcus Gunn phenomenon) are discussed, along with their associated features. Two patients exhibiting the Marcus Gunn phenomenon only and one patient exhibiting both the Marcus Gunn phenomenon and Marin Amat syndrome are described.

The case of a patient with an additional distal root in each permanent mandibular first molar is reported. A thorough review of the dental literature failed to reveal any significant data concerning such cases because much of the literature is concerned with variation in root canal morphology rather than variations in root number. Inability to recognize these aberrations could lead to failure of endodontic treatment.

The purposes of this study were (1) to establish a methodology for determining surface strains in two locations of the same tooth under intact, prepared and restored conditions and (2) to compare the effects on stiffness of different restorative materials in a tooth subjected to cuspal loading. Two linear strain gauges were mounted n each of 30 extracted maxillary premolar teeth. Teeth were mounted in poly (methyl methacrylate) resin and randomly assigned to one of three study groups according to the restorative material and application technique to be used. Statistical analysis indicated a statistically significant interaction between restorative material and tooth condition at both proximal and buccal sites and a statistically significant difference in stiffness betwen teeth restored with Tenure/Marathon V and those restored with either amalgam or Scotchbond 2/P-50 at the proximal site. Results suggest that the methods employed provide a useful, nondestructive means of testing the same tooth under various conditions.

The objective of this study was to compare the microleakage and thermal properties of two recently introduced hybrid materials to those of a conventional glass-ionomer cement. Class V preparations were prepared at the cementoenamel junctions in freshly extracted bovine incisor and evaluated for microleakage with a 45 Ca radioisotope method. Thermal properties were evaluated with thermal mechanical analysis and differential scanning calorimetry. The degree of microleakage and the coefficient of thermal expansion of the conventional glass-ionomer cement were found to be significantly less than those of either hybrid formulation.

The microleakage of three glass-ionomer restorative materials, one chemically cured and two light cured, was evaluated. Ten restorations of each material were placed, according to manufacturer's instructions, in Class V cavities in bovine incisors. All cavities were prepared with 90-degree cavosurface margins and were located at the cementoenamel junction. Sectioning of the teeth after thermocycling and immersion in methylene blue dye revealed only occasional slight leakage and no statistically significant difference among the three materials.