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Biomedical subjects

R J Oswald

Publications and source records attributed to R J Oswald.

14 recordsLinked to original sources
PubMed1993

The injury response of pulpal NPY-IR sympathetic fibers differs from that of sensory afferent fibers.

Light microscopic immunocytochemistry demonstrated that neuropeptide Y (NPY) containing sympathetic fibers in rat molars did not change morphology or staining characteristics after pulp exposure injury. This result, in combination with recent findings concerning NGF synthesis in injured pulp and NGF-receptor localization on pulpal sensory fibers, suggests that small diameter sensory fibers in pulp may be under NGF control, but NPY containing sympathetic efferent fibers are not. Thus, sympathetic fibers in tooth pulp have a different response to NGF compared to those in many other tissues.

Adrenergic Fibers↗
PubMed1992

A radiographic comparison of two root canal instrumentation techniques.

The ability of two instrumentation techniques to negotiate and enlarge small curved canals was com-compared radiographically. Fifty canals in extracted human molar teeth were instrumented by the progressive enlargement (PE) technique, a form of step-back preparation using standard K files, or by the balanced force (BF) technique using K files whose tips had been specially modified. By using drawings and projected radiographic images of the files, the position of the largest file used in the apical preparation, #30 or #35 for the PE technique and #45 for the BF technique, was compared with the position of a small file placed in the canal before instrumentation. The PE and BF techniques were equally capable of instrumenting small curved canals to their respective largest apical preparation sizes. However, at sizes equivalent to the largest apical preparation sizes used in the PE technique, the BF technique produced significantly less deviation from the center of the original canal.

Dental Cavity Preparation↗
PubMed1989

A clinical and roentgenological study of 55 cases of root perforation.

The treatment outcome of 55 root perforations in man were related to pretreatment conditions and various treatment procedures used, with a mean recall period of 3 years 5 months. In this study maxillary teeth were perforated three times more often (74.5 per cent) than mandibular teeth (25.5 per cent); 47 per cent of the perforations were due to endodontic and 53 per cent due to prosthodontic treatment. The buccal and mesial root surfaces as well as the midroot areas were most often perforated. In 25 per cent, radiographic changes were directly related to the perforated areas. Twenty-eight perforations were repaired by orthograde fillings with gutta-percha and Kloro-percha N-phi; eight received a combined orthograde and surgical repair, and in only three cases a surgical approach was used. Four cases received no treatment but were recalled, and twelve perforations showed a size and location hopeless for repair; the teeth were therefore extracted. Five failures of the primary orthograde treatment group later underwent surgical treatment and were followed up for 3 years 3 months. The overall success rate in the primary treatment group of teeth was 56 per cent while 36 per cent became failures. Five failures were retreated, and four of these became successful. A combined orthograde and surgical repair of the perforations provided the most favourable outcome with 92 per cent successful. The study stresses the importance of preventing this type of treatment complication.

Humans↗
PubMed1980

Ankylosed teeth as abutments for palatal expansion in the rhesus monkey.

The maxillary permanent lateral incisors of three rhesus monkeys were intentionally ankylosed by a replantation and splinting technique. A 1-pound expansion force was applied to the ankylosed teeth for 5 to 15 weeks. The intermaxillary and interpremaxillary sutural expansion was monitored radiographically during the experimental period. Two animals were killed for histologic examination after 13 and 23 weeks, and the third animal was monitored radiographically for 21 weeks. Skeletal expansion of the maxilla was achieved without concomitant buccal tipping of the abutment teeth. Osteoid tissue was deposited on localized areas of the resorbed cementum and dentin of the ankylosed teeth. The periodontal ligament showed atrophic and degenerative changes similar to those found with increased age in human beings.

Animals↗
PubMed1980

Periapical response to dentin filings. A pilot study.

Vital maxillary canines of mature cats were intentionally instrumented through the foramen with No. 50 K-files. Dentin chips were packed into the apical opening in one tooth of each animal. In the contralateral tooth a dentin plug was not formed. Both root canals were then filled with gutta-percha. The animals were sacrificed at 3, 5, and 8 months. The results showed quicker healing characterized by minimal inflammation and cementum deposition in the specimens where dentin fillings were packed.

Animals↗