Biomedical subjects
Publications and source records attributed to S A Manning.
The tenets of root-canal treatment are the preparation, cleaning, and sealing of the root canals. An understanding of the variations in root-canal anatomy is necessary by those carrying out treatment. Recognition of a variation when it occurs is the first and most frequent step in completing successful treatment for these teeth.
Currently there is no large animal model of dilated cardiomyopathy. The smaller animal models of cardiomyopathy, such as the Syrian hamster, cannot be studied with echocardiography and cardiac catheterization, and the relevance of these models to human dilated cardiomyopathy is open to question. On the basis of some initial observations in Doberman pinschers, it was speculated that these dogs could have occult left ventricular dysfunction. Accordingly, studies were performed in 46 apparently healthy Doberman pinschers and in 41 mongrel dogs: two-dimensional echocardiography (30 dogs in each group), cardiac catheterization (16 Doberman pinschers and 12 mongrels) and coronary blood flow studies (13 Doberman pinschers and 6 mongrels). In the awake, unsedated dogs studied with echocardiography, left ventricular wall thickening was significantly less in the Dobermans than in the mongrels (28% versus 36%, p = 0.0003). In the anesthetized dogs undergoing cardiac catheterization, left ventricular ejection fraction was significantly lower in the Dobermans than in the mongrels (0.38 versus 0.63, p = 0.0001). Rest coronary blood flow and coronary blood flow reserve were similar in the two groups. It is concluded that apparently healthy Doberman pinschers have occult left ventricular dysfunction. These dogs may serve as a large animal model of dilated cardiomyopathy and should not be used experimentally to study normal cardiac physiology.
The root canal anatomy of 149 mandibular second molars was studied using a technique in which the pulp was removed, the canal space filled with black ink and the roots demineralized and made transparent. Of the 149 teeth, 22 per cent had single roots, 76 per cent had two roots and 2 per cent had three roots. In the single-rooted teeth, three canals were most common, while in the mesial root of the two-rooted teeth, two canals that joined near the apex and one canal in the distal root were most frequent. Round canals were most common in two-rooted teeth and C-shaped canals in single-rooted teeth. Transverse anastomoses were found in 33 per cent of roots, most commonly in the middle third of the root. Lateral canals were found in 72 per cent of roots, most commonly in the apical third of the root. The apical foramen was positioned at the apex in only 33 per cent of roots, and apical deltas were found in 35 per cent. The patient's age and race affected canal shape, with more round canals present in patients over 35 years of age, and more C-shaped canals in Asians. The sex of the patient and the side of the mouth affected the presence of apical deltas, with more being found in males and on the left side. Single-rooted teeth had more complex root canal systems than two-rooted teeth, with more lateral canals, transverse anastomoses, apical deltas and C-shaped canals.
The root canal anatomy of 19 mandibular second molars with C-shaped canals was investigated by rendering the roots transparent and allowing the canal system to be observed by black ink infiltration. The presence of three root canals was most frequent, and lateral canals were found in all roots. Transverse anastomoses were found in 15 of the 19 roots. The apical foramen was most commonly situated away from the apex, and apical deltas were found in 16 of the 19 roots. The C-shaped canals were found more frequently in Asians than in other racial groups (P less than 0.02). The formation of C-shaped roots and their racial predilection is discussed. A case report of the root canal treatment of a C-shaped canal is included and suggestions are made concerning suitable procedures for use in root canal treatment of these complex canal systems.
Tests of the catharsis hypothesis involving viewed violence have led to conflicting results. It was suggested that the inconsistencies were due in part to the use of two different types of response measures, aggressive responses and hostile responses. This study involved a direct comparison of the two types of responses under conditions of instigation versus no instigation and aggressive versus neutral film. It was hypothesized that viewing an aggressive film would lead to a decrease in hostile responses (catharsis) and an increase in aggressive responses (stimulation) when compared with a neutral film condition. It was also hypothesized that both stimulation and catharsis effects would be enhanced under instigation conditions. A main effect of instigation was found with subjects in the instigation condition having higher scores than those in the noninstigated condition. A main effect of film was found with subjects having lower scores in the aggressive film condition than in the neutral film condition. A significant Film times Response Outlet interaction was found which offered support for the predicted catharsis effect on the hostility measure. There was no support for the predicted stimulation effect on the aggression measure. The results of the study offer support for the main thesis that in examining the effects of viewed violence, separation of hostile responses and aggressive responses is necessary for full understanding.