Biomedical subjects
Publications and source records attributed to D G MacDonald.
An investigation has been carried out into the nature of the black pigment in black extrinsic tooth stain. The results suggest that the black material is a ferric salt, probably ferric sulfide, formed by the reaction between hydrogen sulfide produced by bacterial action and iron in the saliva or gingival exudate.
Explore the source record for details and available documents.
Actinomycosis is often considered to be a rare disease in the oral region. A retrospective study of the Routine Diagnostic Services in Glasgow Dental Hospital revealed 39 cases in which actinomyces were detected, indicating that this organism is not infrequent in oral infections and may be seen in a variety of lesions.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The patterns of spread of squamous cell carcinoma within the mandible were investigated in 43 nonirradiated (33 edentulous and 10 partially dentate) and 16 irradiated mandibles. Two modes of spread were identified: (1) spread in relation to the inferior alveolar nerve, and (2) spread in spaces between cancellous bony trabeculae. Although nerve-related spread was significantly more frequent in the edentulous than in the partially dentate nonirradiated mandible, the difference in incidence between all nonirradiated mandibles and irradiated mandibles was not significant. The patterns of spread in cancellous bone in irradiated and nonirradiated mandibles differed little. Spread of tumor within the medulla, deep to an intact cortex beyond the extent of extraosseous soft tissue tumor, was seen infrequently.
Patterns of spread of squamous cell carcinoma to the ramus of the mandible have been studied. In nonirradiated mandibles, tumor in the ramus was found to have spread in continuity from tumor within the body. In 22 of 27 specimens (81.5%) with established invasion of the molar region of the body, tumor spread was either confirmed to the body or to the body and the anterior part of the ramus. The remaining five cases showed extensive spread within the ramus. It was concluded that a more conservative approach to resection of the ramus may be safe on pathologic grounds in the nonirradiated mandible. In postirradiation mandibles, direct invasion through cortical bone was seen in addition to direct spread from the body. Tumor spread to the ramus was seen in nine of 12 specimens (75%), and in each case was both diffuse and extensive. It was concluded that a conservative approach to resection of the ramus is not safe on pathologic grounds after radiotherapy.
The sources of periosteal blood supply to the mandible have been investigated by dissection, histology, and injection studies. The facial artery has been identified as a major extraosseous source of blood supply to the body. The study confirms the importance of preserving the soft tissue attachments on the buccal aspect and lower border of the mandible during lateral mandibular osteotomy.
The improved stability that results from the combination of K-wire transfixion of a mandibular osteotomy with direct wiring has made it possible to use a straight, as opposed to a stepped, bone cut and to avoid the invariable need for dental extractions. It has also made possible an alternative osteotomy site, immediately anterior to the mental foramen. The use of this site allows mandibular swing to take place after division only of mucous membrane and mylohyoid. It is best combined with a modified lip-splitting incision which has been found to improve ultimate cosmesis.
The changes in the mandible and in its relationship to surrounding soft tissue structures after loss of the teeth are described; the regular presence of deficiencies in the cortical bone along the line of the occlusal ridge is emphasized. Resection specimens of squamous carcinoma of the oral cavity not treated by radiotherapy were examined where there was mandibular involvement by tumor, and showed that the main route of tumor entry into the bone was through the occlusal ridge. Subsequent perineural spread along the inferior alveolar nerve has been found to be a regular occurrence.