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Necessary restorative requirements for full coverage are adequate axial wall height of the preparation for retention as well as sufficient vertical width of sound tooth structure cervically for the crown margins. In cases where adequate healthy tooth structure does not exist coronally to the epithelial attachment due to various crown damages, the margins of the crown might traumatize the periodontal attachment and the periodontium will be jeopardized iatrogenically. Teeth with inadequate axial Reight of the clinical crown, subgingival caries, vertical or horizontal fractures will require surgical crown lengthening procedures before prosthetic treatment is performed. These procedures may either involve only the soft tissues or bone remodeling as well. Irrespective of the procedure, crown lengthening must be performed with the objective of at least 3 mm. of healthy tooth structure coronally to the bone. This width will permit the formation of a new dentinogingival junction and the existence of 1-2 m.m. of sound tooth structure coronally to the new attachment line for the construction of a biologically acceptable crown margin. The purpose of this article is to discuss the clinical problem and underline the importance of crown lengthening procedures as a preparatory step for prosthetic treatment in fixed partial dentures.

The already known surgical interventions for absolute induction of extensive mandibular atrophy, cannot be suggested as routine standardized methods. Use of Hydroxylapatite-ceramic for restoration of the atrophic alveolar process, shows several advantages; among those, simplicity of the operation use of local anesthesia, as well as very low percentage of unsuccessful interventions are taken into consideration. The clinical results of 102 cases are shown and discussed. Through the addition of H.A. ceramic in the field of preprosthetic surgery, there is a broadening of the spectrum of the therapeutic possibilities of patients with prosthetic problems to be expected.