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attachment is frequently more apical
     (b) Because the possibility of fill-in of such defects is uncertain
     (c) Because the presence of vertical defects usually indicates that factors other than plaque- induced inflammation are operating. Furcation involvement can present home care problems, even after satisfactory periodontal treatment, and if the furcation lesion is related to pulp pathology, prognosis is compounded by any defects in endodontic treatment.
     4. The possibility of removing aetiological factors. The control of aetiological factor is essential to the achievement of long-term health, but control can only be exercised after these factors have been identified. Without such identification, treatment becomes symptomatic. Careful examination and an understanding of clinical features are essential. It is always necessary to ask why are these clinical features present?
     Patient cooperation is essential for satisfactory plaque control, but is also necessary for the control of predisposing and aggravating aetiological factors, e.g. The replacement of an ill fitting partial denture. Patient cooperation is more likely to be forthcoming after the patient has been given information about the nature of the problem. Time spent in providing such information and in explaining the rationale behind the treatment plan will improve the chances of achieving a good prognosis.
     5. The number, position and form of teeth present. The number of teeth and their position in the arch will determine the occlusal load on each tooth, whether prosthesis is necessary, and the amount of tooth support for an appliance. In this context, the form of the appliance is extremely important; a removable appliance makes greater demands on the tooth supporting tissues than a fixed appliance. The symmetrical distribution of the teeth in the arch is likely to provide a better prognosis than where several teeth are placed on one side of the arch. The root base can be a crucial factor in the stability and usefulness of a tooth. An upper molar with widespread roots and therefore a large root base has a much better prognosis than a conical-rooted premolar of incisor with the same amount of bone loss.
     6. General health. Although certain conditions do affect the periodontal tissue response, e. g. Diabetes, Down’ s syndrome, agranulocytosis, the general health of the patient does not usually affect the periodontal condition directly, but any debility physical or emotional, can interfere with the patient’ s oral hygiene regime.
     7. The immunological status in relation to plaque organisms. The individual’s response is critical to the development and progress of periodontal destruction, and is the subject of much recent research. A few young individuals appear to suffer some deficiency in the cell-mediated immune response to plaque antigens, which leads to an extremely poor prognosis. It seems likely that other variations in immune response will be identified in the future, and some laboratory tests may be developed which will provide a more objective guide to prognosis than is currently available.
     All the factors outlined above must be taken together to provide a periodontal prognosis for that particular individual. This exercise has to be carried out with great ca