Bienvenido Perez

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.

Tissue reaction to nitinol wire alloy.

Abstract The reaction of tissue to 55-nitinol wire suture placed subcutaneously in forty-five rats was followed for 9 weeks. The tissue reaction was minimal at all time periods. The reparative process was initiated within 1 to 2 weeks and formed a dense, relatively avascular fibrous connective tissue capsule by 5 to 6 weeks, with little change beyond this time. When compared to stainless steel in previous experiments, the nitinol was indistinguishable from the stainless steel at similar time periods. Therefore, on the basis of the results of this experiment, it appears that 55-nitinol compares favorably with stainless steel and could be used in the deep tissues.

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.

Controlled cryotherapy in the treatment of inflammatory papillary hyperplasia

Abstract Cryosurgery is an effective, painless method for the removal of inflammatory papillary hyperplasia. It requires no local anesthetic, and there is no offensive odor or postoperative or operative bleeding. The method is attended by little postoperative discomfort. Total healing occurs from 3 to 5 weeks postoperatively. The palatal mucosa has a normal appearance and is soft and nontender. A method employing a Freon-cooled probe has been used effectively on twelve patients with inflammatory papillary hyperplasia.