Clinical evaluation of Class V restorations using a total etch technique: 1-year results.

The clinical performance of All Bond 2 and Bis-Fil M used with a total etch technique is being monitored in adult patients with erosion/abrasion lesions. 78 restorations were placed among 36 patients. After a prophylaxis, a short bevel was placed on the enamel margin. Using cotton roll isolation, both enamel and dentin were conditioned with 10% phosphoric acid for 20 seconds. Both tissues were moist at the time of primer application in which several applications of the latter resulted in a shiny surface upon gentle air drying. Bonding agent was added, brush thinned and polymerized for 20 seconds. The restoration was completed with the appropriate shade of composite placed in two increments and finished with fine grit diamonds and polishing paste. Evaluation criteria according to Ryge included retention, color match, visual and tactile margin integrity, secondary caries and postoperative sensitivity. A 1-year recall of 73 restorations showed 98.6% retention with 95.8% Alfa color match and stain-free margins. Tactile integrity was 83.1% Alfa. There was no secondary caries nor postoperative sensitivity. It was concluded that these preliminary findings offer cautious optimism for this system and the total etch procedure.

Strength of amalgam restorations bonded with Amalgambond.

The objective of this study was to determine the strength of bonded amalgam restorations involving an entire cusp. Four groups were established, each containing 13 caries-free, recently extracted molar teeth of similar size and anatomic form. The teeth were stored in 70% alcohol prior to the removal of a cusp and the cutting of a conventional preparation with an occlusal lock. Group A were restored with amalgam only, Group B with amalgam and a pin, Group C with amalgam and Amalgambond (4-META) and Group D with amalgam, a pin and Amalgambond. The teeth were blocked in stone and stored for 7 days in water at 37 degrees C. Using an Instron, a force was delivered at right angles to the inclined cuspal plane of the amalgam at its midcuspal point at a crosshead speed of 5 mm per minute. The load at failure was recorded and the assemblies recovered for fracture analysis using SEM. Group A failed at 33.61 +/- 15.17 Kg, Group B at 32.28 +/- 12.10 Kg, Group C at 48.53 +/- 21.93 Kg and Group D at 47.84 +/- 14.79 Kg. No statistically significant difference existed between Groups A and B, and Groups C and D. A significant difference (P < 0.002) existed between Groups A and C and B and D. Failure commonly occurred between cusp and occlusal lock or within the cusp when a pin was used. Bonded restorations with a pin incurred cohesive root failure. It was concluded that the strength of the amalgam restorations benefitted significantly from bonding but the Amalgambond system may be contraindicated for use with pins due to root fracture.

Polymeric sealing of dentinal tubules to control sensitivity: preliminary observations.

The purpose of this study was to evaluate the effectiveness of a hydrophilic dentin primer to eliminate dentinal hypersensitivity to thermal stimuli. Eight patients enrolled in the study, with a total of 42 teeth having cervical sensitivity caused by erosion, abrasion, or periodontal therapy. All teeth were sensitive to cold air and tactile exploration. All test sites were rinsed with water, air-dried, and rubbed with a moist cotton pledget. Several coats of a dentin primer, consisting of N-tolylglycine-glycidyl methacrylate and bisphenyl dimethacrylate, were then applied with a brush to the exposed dentin and light-cured. All patients reported a complete absence of pain when the sites were retested with thermal stimuli immediately after treatment. After a 9-month period, seven patients remained symptomless, and one patient indicated slight sensitivity to ice. It was concluded that a single application of a hydrophilic dentin primer is highly effective in reducing or eliminating dentinal hypersensitivity to thermal stimuli for at least 9 months.

Transplantability and biological behavior of a rapidly growing secondary Morris hepatoma.

Transplantable hepatomas have a special importance in cancer research because most are well-differentiated and grow at widely differing rates. A simple and reproducible technique was developed to transplant the rapidly growing Morris hepatoma 9618A2 from a subcutaneous to an intrahepatic site. The tumor has been maintained for over 80 successive transplant generations by inoculating Buffalo rats subcutaneously. The hepatoma, transplanted many times from the subcutaneous site to the liver, was examined histologically on various occasions. By varying inoculum size, growth of the hepatocarcinoma could be controlled. Throughout transplantation, the donor animals were bled without causing the death of the animal. Histological studies revealed that the tumor, when transplanted intrahepatically, remains a highly differentiated neoplasm with no observable morphological changes.