Segmental neogenesis of the dog esophagus utilizing a biodegradable polymer framework.

This study evaluated the ability of biodegradable implants fabricated from polymers and co-polymers of polylactic acid (PLA) and polyglycolic acid (PGA) to induce regeneration of surgically created defects in the dog esophagus. The study utilized 12 mongrel dogs that had a 5 cm segment of the esophagus removed. Implants were fabricated by spray casting the polymers on a spinning Teflon mandril. The defects were repaired by suturing the biodegradable implants to the proximal and distal ends of the esophagus. Ten of the dogs were sacrificed from 3 days to 8 weeks after surgery while 1 of the dogs died after 3 years and 1 dog was sacrificed 4 years after graft placement. Endoscopic and histologic examination of the grafts 3 days after placement showed minimal inflammatory response and an apparent seal between the esophagus and implant at the suture lines. Two weeks after surgery a fibrous connective tissue sheath, continuous with the proximal and distal segments of the esophagus, could be seen surrounding the graft. One month after placement, the implants were partially degraded leaving a connective tissue repair continuous with the proximal and distal ends of the esophagus. The repair area was lined with epithelium and enabled the dogs to drink freely and eat semisolid foods. In conclusion, it has been shown that it is possible to fabricate a biodegradable implant which can stimulate regeneration of a hollow organ and which is compatible with long term survival.

The comparative efficiency of final endodontic cleansing procedures in removing a radioactive albumin from root canal systems.

Fifty-six teeth were initially instrumented, with the use of seven irrigants or irrigant combinations, and filled with radioactive albumin. The study then showed the relative ability of three final endodontic procedures (copious reirrigation with saline solution, drying with paper points, and reassuring patency of the canal with the final instrument) to remove the albumin. Even after copious irrigation, each additional procedure removed statistically significant amounts of albumin. Alternating an organic solvent and an inorganic solvent did appear to leave the canal system in the optimal condition for final cleansing procedures. The study then correlated the relative efficiency of irrigation alone versus instrumentation plus irrigation in removing the remaining albumin from the canal systems. Reinstrumentation plus copious irrigation removed significantly more albumin than copious irrigation alone.

Effects of local anesthesia on gingival cAMP levels.

The basal levels of cAMP in the attached gingiva of Rhesus monkeys and the changes in tissue cAMP levels produced by infiltration anesthesia with lidocaine and lidocaine containing 1:100,000 epinephrine were studied. The basal level of cAMP in uninjected monkey gingiva ranged from 12 to 20 picomoles of cAMP per mg of gingival protein. This level was 75 times greater than the cAMP content of monkey blood plasma. Infiltration of the attached gingiva with saline or plain lidocaine for 5 minutes did not produce any significant changes in tissue cAMP levels. Infiltration of the gingiva with lidocaine containing 1:100,000 epinephrine, on the other hand, caused a very marked increase in tissue cAMP levels. Thirty seconds after infiltration with lidocaine with 1:100,000 epinephrine there was a 250% increase in cAMP content of the anesthetized tissue versus the uninjected control tissues. The maximal increase in tissue cAMP levels was observed 5 minutes after infiltration when the cAMP content of the gingiva was 1000 to 1100% above the control level. It is proposed that regulation of tissue cAMP levels by epinephrine or other agents may prove of therapeutic usefulness in regulating inflammation and healing of tissues after surgery or other trauma.

Solubility of injectable Valium in intravenous solutions.

A study of the solubility of Valium in commonly used intravenous solutions showed Valium to be equally insoluble in 5% dextrose in normal saline, 5% dextrose in water, normal saline, and Ringer's lactate. However, the precipitate which was formed became completely resuspended when mixed with as little as 39-42% plasma in vitro. This would indicate that the chalky precipitate seen in the I. V. tubing when Valium is injected into a running I. V. near the venipuncture site becomes resuspended when mixed with plasma in vivo. If one elects to inject Valium into the tubing of a running I. V., it is recommended that the drug be administered slowly to assure adequate mixing with blood plasma in order to prevent the circulation of particulate matter.Valium is currently one of the most popular drugs used in the psychosedative management of the apprehensive dental patient. Various techniques are advocated for its administration from direct injection into a vein to injection of the drug into a running I. V. However, the manufacturer states that the drug should not be added to I. V. fluids or other solutions or drugs. Presumably this is because of the formation of a cloudy precipitate immediately upon addition to aqueous solutions. Grower et al. have shown that saturated aqueous solutions of Valium in normal saline redissolve when added to plasma; however, they presented no data on the behavior of solutions of Valium added to other commonly used intravenous fluids. The present study was, therefore, undertaken to study the behavior of Valium when added to lactated Ringer's solution, 5% dextrose solutions, and normal saline; and to see how human blood plasma affects the solubility of Valium in these solutions.

The effects of length of surgery on healing of full and partial thickness flaps.

Partial and full thickness flaps which were were made in the facial gingiva of 10 dogs were reflected for 15 or 90 min. Specimens were examined histologically and biochemically from 3 to 28 days after initial surgery. The results indicate that flaps refelected for 15 min exhibited faster epithelial closure than those reflected for 90 min. Partial thickness flaps reflected for both 15 and 90 min showed less inflammation than full thickness flaps at 3 and 7 days post surgery and healed faster in respect to epithelial closure, mesenchymal healing, and bone regeneration. Biochemical analysis of the collagen concentration of the tissure flaps revealed similar collagen content in full and partial thickness flaps reflected for 15 min; however, the collagen concentration of partial thickness flaps opened for 90 min was higher than that in full thickness flaps.

Histocompatibility of polyvinyl acetate, an ingredient of chewing gum.

The histocompatibility of polyvinyl acetate (PVA), an ingredient of chewing gum, was evaluated from both a direct irritant (toxic reaction) and an allergic (antigen-antibody) standpoint. Subcutaneous injections in rats and topical application of hamster pouches were utilized. Polyvinyl acetate was shown to cause a moderate to severe inflammatory reaction when injected subcutaneously, which peaked at day 7 and was minimal at day 42. The histologic appearance of the hamster cheek pouch was not significantly altered by the PVA. Although PVA has been used as a plasticizer in chewing gum, it was not possible to induce any histologic changes in tissues which resembled the specific changes present in atypical gingivostomatitis (plasma-cell gingivostomatitis).

Cyclic AMP content of gingival fluid in women taking oral contraceptives.

Gingival fluid samples were collected from 12 healthy adult women who ranged in age from 19 to 34 years. Seven subjects with normal menstrual cycles who received no medications acted as controls while five subjects who had been using oral contraceptives for a minimum of 17 months constituted the experimental group. The women using birth control pills showed a 53% increase in the gingival fluid volume versus the controls. Radioimmunoassay revealed a mean concentration of cyclic adenosine monophosphate (cAMP) in the gingival fluid of 3.8-10(-6)M in the controls and 1.9-10(-6)M in subjects using oral contraceptives, although the total amount of cAMP present in the fluid from both groups was equal. These gingival fluid cAMP levels were a hundredfold higher than those measured in serum and saliva.

PIP: Dental literature showing that ovarian hormones and oral contraceptives (OCs) can alter the physiologic state of gingival tissues has led to an investigation in which gingival fluid samples were collected from 12 healthy adult women ranging in age from 19 to 34 years. 5 subjects who had been using OCs for at least 17 months constituted the experimental group while 7 received no OCs and formed the control group. Those using OCs exhibited a 53% increase in gingival fluid volume vs. the controls. Radioimmunoassay revealed a mean concentration of cyclic adenosine monophosphate (cAMP) in the gingival f luid of 3.8-10-6M in the controls and 1.9-10-6M in the subjects using OCs although the total amount of cAMP present in the fluid from both groups was the same. These gingival fluid cAMP levels were 100 times higher than those measured in serum and saliva. An association between the amount of cAMP found in the gingival fluid and the duration of OC use has been apparently absent.

Differences in cAMP levels in the gingival fluid of diabetics and nondiabetics.

Gingival fluid from eight control subjects and ten diabetics was collected and the content of cAMP and protein in the fluid was assayed to determine the nature of the biochemical changes occurring in the gingival fluid due to diabetes. The gingival fluid of the control subjects had a cAMP concentration of 2.4 X 10(-6) M, which was a hundredfold greater than that seen in serum, thus suggesting that the cAMP in the fluid resulted from active synthesis by the gingival cells and was not merely a transudate from the blood. The gingival fluid of the diabetics contained only one-seventh the level of cAMP seen in the control group. It is suggested that the decreased level of cAMP seen in the givgival fluid of diabetics may be a manifestation of a defect in the cAMP forming mechanism of the gingival tissue, which may reflect the systemic etiology of diabetes. It was also found that in the control subjects the content of cAMP in the gingival fluid was in inverse proportion to the volume of exudate in the gingival crevice. No such relationship was seen in the diabetic group. It appears that the level of cAMP present in the gingival fluid of normal individuals without any generalized endocrine deficiencies may be used as an additional indicator of the inflammatory status of the gingival tissues, along with the clinical evaluation based on gingival index.