Marvin F. Grower

Biodegradable ceramic implants in bone. Electron and light microscopic analysis.

Abstract The main purpose of a biodegradable ceramic implant is to fill a bone space as well as to eliminate the need for a metallic implant. Although the biodegradable ceramic does stimulate bone formation and does disappear from the implanted site, it does not have the same initial strength as a metal or nondegradable ceramic implant. When completely replaced by bone, however, it should prove superior to the latter two. Additional studies comparing degradable ceramic with various other types of ceramic material and with unfilled bone defects are in progress.

Evaluation of a new thermoplastic gutta-percha obturation technique using 45CA

This study evaluated the leakage after in vitro gutta-percha obturation of 60 root canals, using three techniques, both with and without sealer. The techniques were lateral condensation, warm (vertical) condensation, and the new mechanical compaction (McSpadden) technique. The techniques were compared by evaluating horizontal sections of the teeth by radioautography after soaking the teeth in 45 Ca. The difference between techniques was not statistically significant. Additionally, at the 1.4-mm level in only one technique (compaction) did sealer show an improvement in seal at a statistical level of even P

Characterization of Osseous Tissues by Thermogravimetric and Physical Techniques

Changes in osseous tissue after injury were studied in monkeys with the use of thermogravimetric analysis (TGA) and mechanical strength measurements. An exponential relationship was found to exist between strength and weight loss for repair tissues 3 to 8 weeks old. The quantitative techniques investigated seem promising for the improved characterization of mineralized tissue.

Effect of water lavage on removal of tissue fragments from crush wounds

Abstract One of the main objects of wound debridement is to separate viable tissue from dead and dying tissue fragments. At the present time, most debridement is done by surgically cutting out and scraping away areas of necrotic or questionable tissue. The object of this study was to determine the quantitative effect of pulsed water-jet lavage on wound debridement, with the idea of eventually determining the optimal conditions so that water lavage could be used to perform wound debridement in a faster and less traumatic manner.

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.

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.

Effect of Pulsating Water Jet Lavage on Radioactive Contaminated Wounds

A radioisotope of zinc was introduced into facial wounds of rats to stimulate natural contamination. The quantitative effects of a bulb syringe, single pulsed water jet, and a multiple pulsed water jet on decontamination of the wounds were determined by counting the radioactivity that remained in the wounds after treatment. The water jet devices were shown statistically to reduce contamination more than the bulb syringe.

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).

Comparison of the flushing effectiveness of four different types of needles after root canal preparation

Abstract A gel containing radioactive 125 I-albumin was used to determine the effectiveness of four different types of irrigating needles in the removal of contamination in vitro from the root canals of 40 endodontically treated single-rooted human teeth. All of the needles tested were equally effective in removal of the radioactive tracer from the root canals. Regardless of needle design, more tracer remained in the apical 4- and 8-mm segments of the canal after irrigation than was present before irrigation.