Joe D. Beasley

Degradation rates of polymers and copolymers of polylactic and polyglycolic acids

Abstract This study has substantiated the following previously reported characteristics of these polymers and copolymers: They are biodegradable. The degradation is accomplished by capillary ingrowth and/or phagocytic foam cells. The degradation is not accompanied by inflammation. The pellets are replaced by fibrous connective tissue and/or bone and marrow tissue. Bone is deposited directly upon and within these materials, thus providing good continuing stabilization. Furthermore, this study has established that, by varying the proportions of PLA to PGA, resorption times can be varied from less than 100 days to periods in excess of 220 days. These materials degrade in the following order: 25 per cent PLA degrades first; 50 per cent PLA degrades second; 75 per cent PLA degrades third; 100 per cent PLA degrades fourth; 100 per cent PGA degrades the slowest. The fast-cooled and slow-cooled polymers with different crystal formations do not affect the degradation rates. The ranges of resorption encompass the times required for fracture fixation. Studies are presently in progress on other proportions of these polymers and on different polymers.

Histologic comparison of polylactic and polyglycolic acid sutures

Abstract Comparative studies were carried out to determine soft-tissue reactions and speeds of biodegradation of polylactic acid (PLA) and polyglycolic acid (PGA) sutures in rats. These sutures were placed in the posterior aspects of the thigh muscles, and the animals were killed intermittently through a 90-day postoperative period. The results of the experiment indicate that both PGA and PLA may be acceptable for use as a suture material.

Tissue reaction to intrabony ceramic implants

Abstract It is apparent from the present study that phosphate-bonded alumina ceramic is well tolerated by tissues, does not elicit a foreign-body reaction, is rapidly infiltrated by connective tissue and bone marrow, and forms a latticework upon which osteoid and bone and dentine are deposited. Thus, it would appear that implants of alumina ceramic can be used as bone replacements.

The effect of antibiotics and pulsating water jet lavage on contaminated wounds

Abstract It has been shown that pressure lavage with a solution of streptomycin and penicillin significantly reduces the incidence of wound infection. Such elimination of bacteria from wounds should accelerate healing and decrease tissue destruction and scar formation. It is suggested that antibiotics other than the ones used in this study may further increase the effectiveness of this method.

Pulpal response to four restorative materials.

Abstract This study deals with pulpal response to four types of restorative material. Class V cavities were prepared in seventy-eight teeth of three miniature swine and were restored with zinc oxide and eugenol, a commercially available product called IRM, a mixture of ethoxybenzoic acid with fillers called EBA, and a mixture of isobutyl cyanoacrylate and zinc phosphate called CAZI. The animals were killed after 1, 2, and 3 weeks, and the teeth were examined microscopically. This study revealed the following: 1. 1. With the exception of one tooth, which showed a micro-abscess, irreversible pulp damage was not observed. 2. 2. All three of the restorative materials appear biologically acceptable to the dental pulp. 3. 3. Odontoblastic disruption and inflammatory infiltrate were not severe in any case. They were, however, least marked in the zinc oxide and eugenol restorations and most prominent in teeth restored with cyanoacrylate-containing restorative material. 4. 4. The layer of reparative dentine formed in response to the filling materials was proportional to the degree of odontoblastic disruption and the inflammator yinfiltrate. It was more prominent in those teeth which were restored with CAZI and EBA than in teeth filled with the other materials. 5. 5. It appears from this study that any of the three experimental materials tested could be used as filling materials. However, in cases in which the therapeutic aim is to acquire a thick layer of reparative dentine, a cavity base with either the EBA or CAZI would be preferable. On the other hand, where these materials are to be used as semipermanent restorations rather than as cavity bases, their physical properties and their resistance to the oral environment should be the decisive factors.

Oral spray of isobutyl cyanoacrylate and its systemic effect

Abstract The present study on three groups of rats was undertaken to determine whether the oral spray of isobutyl cyanoacrylate would lead to aspiration or ingestion of the material. Furthermore, it included a histomorphologic analysis of the lung, liver, stomach, and kidney. This investigation revealed that when the throat of the animal is protected, an oral spray of this chemical adhesive does not result in any aspiration of the material or any discernible changes in the respiratory and gastrointestinal systems or in the vital organs. In only one of the twenty animals in which the throat was not protected with cotton did the adhesive possibly reach the upper part of the esophagus. In view of the facts that the average human dose used is only about one one-thousandth that given to the rats in this study, that the pressure of delivery is only about one third, and that in man the oropharynx is protected with gauze or other means, it seems improbable that the use of this material in the form of an oral spray could produce any abnormalities elsewhere in the body. Clinical data on 109 patients in whom 296 applications were made, fail to reveal any undesirable effects of the oral spray of isobutyl cyanoacrylate.

Blue nevus of the oral mucosa: Report of a case

Abstract A case involving previously undiagnosed tuberculosis and intraoral blue nevus of the hard palate has been reported. Excisional biopsy of intraoral blue nevus, even though it is a benign lesion, is indicated for definitive diagnosis, ruling out similarly pigmented malignant lesions.

The effect of spherical polymers and water jet lavage on oral mucosa

Abstract Studies have been undertaken to demonstrate the relative tissue damage and particle penetration that occurred when suspensions of spherical polymer beads were lavaged through a water jet device against the intact mucosa of the cheeks at various pressures. The present study revealed that an increase in local tissue damage is to be seen when the particles are used in suspension as compared to tissues lavaged with conventional tap water. Also, reliable penetration of particulate matter measuring an average of 24 microns is not seen. When the penetration is observed, it is usually limited to the epithelial layers.

Water Lavage and Tissue Calibration Study in Rats

The effect of a pulsating water jet delivered at a calibrated known force per unit area at a constant tip-to-tissue distance on oral mucosal sites of varying tissue densities was studied. The degree of tissue damage was determined by two factors: the force of the water jet and the density of the target tissue.

Induced bone formation in rat mandibles

Abstract Adult albino rats were used in a comparative study whereby selective injuries were produced on exposed bone and also on periosteum-covered bone in an attempt to induce the formation of new bone. The results of this pilot investigation favor the continuation of bone-induction studies for longer periods of time and perhaps in larger laboratory animals.