Nigel G. Clarke

The effects of intra-arterial epinephrine and nicotine on gingival circulation

The purpose of this study was to test the hypothesis that acute necrotizing ulcerative gingivitis (ANUG) was the result of ischemia resulting from three predisposing factors. Vascular stasis, stress, and smoking were said to combine and induce severe vascular constriction at the end arterial locations of the gingivae, resulting in necrosis of the part. The experimental animal used was the rabbit; clinical doses of epinephrine and nicotine were infused intraarterially and the gingival circulation was monitored by the heat-diffusion principle. It was found that the chemicals caused a severe reduction in flow rates in spite of greatly increased pressure within the system. The finding supports the hypothesis that ischemia could play an important role in the initiation of ANUG.

Periodontitis and angular alveolar lesions: A critical distinction

Modern anthropologic and epidemiologic studies reveal that the incidence of periodontitis is low in both ancient and modern populations. The distribution of plaque and gingivitis has little or no correlation with the distribution of pathologic alveolar bone loss or with periodontitis. The assumption that a distance from cementoenamel junction to alveolar crest (CEJ-AC distance) greater than 2 mm equates with disease overlooks the interrelationship between the CEJ-AC distance and continuous eruption in compensation for tooth wear and growth of the lower face height. Anatomic, physiologic, and pathologic factors increasing CEJ-AC distances are reviewed. Where horizontal periodontitis does result from gingivitis, it is usually of minimal significance and probably occurs when the host defenses have been diminished by environmental factors commonly associated with other chronic diseases. A pulpal-alveolar explanation for localized angular alveolar lesions better fits the clinical features of this form of periodontal bone loss than does the conventional hypothesis of primary periodontal infection by specific oral bacteria.

Capacity of Buffers to Inhibit Acid Production within Dental Plaque

An oral radiotelemetric technique was used to determine whether a range of efficient buffers had the capacity to control the levels of hydrogen ions within dental plaque in the presence of sucrose. It was found that the buffers failed to control both the intensity and duration of the acid produced.

Juvenile periodontitis — A new perspective

Juvenile periodontitis (JP) is a severe disease of the periodontium in adolescents. It is usually localized to the first permanent molars and (less commonly) the central incisors. The bacteria Actinobacillus actinomycetemcomitans (Aa) is currently implicated in the aetiology of JP since its numbers are high in JP pockets and low in subjects with healthy periodontal conditions or with adult periodontitis. However, Aa harvested from JP pockets and transferred to healthy sites in the same mouth are unable to colonize these areas or initiate disease (17). The conflicting evidence implicating intrinsic or induced impairment of host defence is reviewed. It is hypothesised that JP lesions are primarily of endodontic origin. By-products of an inflammatory process in the pulp enter the periodontium via dentinal tubules, lateral or furcation canals and drain through the periodontium into the mouth. The environmental conditions of the sinus select for bacteria such as Aa which secondarily infect the site and exacerbate the clinical situation by their potent virulence factors. Localized deep defects involving only one side of an interproximal space in an otherwise periodontally healthy mouth result. Studies of the pulpal status of JP teeth are indicated.

Treatment planning for fixed and removable partial dentures: A periodontal view

1. Chronic occlusal trauma of partial denture abutments may be observed in radiographs before other clinical symptoms are noticed. 2. Evaluation methods can determine when teeth are unsuitable to serve as abutments, but these methods may not be reliable to predict the capacity for some essentially normal teeth to accept additional stresses. 3. Whenever a potential abutment is tilted so that axial loading is questionable, no restoration should be made.