英语论文网

     Alveolar bone loss
     Resorption of alveolar bone and the associated destruction of periodontal ligament are the most important feature of chronic periodontitis, and the one, which leads to tooth loss. There is considerable variation in both the form and rate of alveolar bone resorption and in constructing a treatment plan the amount of bone loss, the rate at which resorption is progressing and the pattern of bone loss need to be accurately established. Radiographic examination is an essential part of periodontal diagnosis and with certain limitations provides evidence of the alveolar bone height, the form of bone destruction, the width of the periodontal ligament space and the density of cancellous trabeculation. Serial radiographs taken over a period of time can provide information about the rate of bone loss. However, radiographic examination without careful clinical examination can be very misleading. A periodontal diagnosis cannot be made from radiographs alone as there is no way of distinguishing on the radiograph past bone destruction from current bone resorption.
     Because the images of the facial and lingual plates of bone are largely obscured by the dense image of the tooth, diagnosis depends upon obtaining a clear image of the interdental bone. Careful angulation of the X-ray beam and a standardized routine of exposure and processing the radiographic film is essential.
     The first radiographic sign of periodontal destruction is loss of density of the alveolar margin. This is most clearly seen between posterior teeth where in health the broad interdental septum projects a dense and well-defined image of the alveolar margin. The image of the narrow interdental septa between anterior teeth is less well defined in health and early pathological changes are less easy to see. With continuing bone resorption the height of the alveolar bone is further reduced.
     Even correctly angulated the radiographs may not disclose the true state of interdental resorption, e. G. An interdental crater between molars can be masked by the images of the facial and lingual walls of the defect. Bone defects, which lie over the facial or lingual aspects of the teeth, e. G. Marginal gutters, may be completely obscured and revealed only when flaps are raised at surgery.
     Moreover, distinguishing between facial and lingual defects may not be possible from radiographic evidence alone. Two radiographs taken at slightly different angles often reveal defects undetected by one. This is especially true in the diagnosis of furcation defects. These are usually revealed by radiographic examination but the exact form of the defect may not be discernible. The thick palatal root of an upper molar may mask a trifurcation defect. Widening of the periodontal space in the furcation provides evidence of an early lesion. Widening of the periodontal space on one side or all around a tooth frequently indicates excessive occlusal stress. This is sometimes accompanied by widening or funnelling of the coronal aspect of the socket.
     All departures from the normal radiographic appearance must be checked against other clinical features, in particular pocket depth and mobility patterns, and if the本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。