To conclude discussion on immediate dentures and how youu would analyse the model for the denture design to allow comfortable insertion of the denture in the mouth by the dentist

When  preparing a model for an immediate denturre and considering comfortable insertion of the denture, the technician needs to consider the undercut present and avalaible for retention. When the undercut is less than 1 to 2mm it is of no great significance because of the compressibility of the soft  tissue and this compressibility will allow for the insertion of the denture. Undercuts composed entirely of soft tissue, as in the tuberosity areas, can be utilised for retention and will still be able to be inserted comfortably into the patients mouth.

With undercuts greater than 2mm, analysis of the model would indicate where the flange should be relieved or shortened. Vertical relief refers to the shortening ofthe flange (half flange) to avoid it entering the undercut area. Horizontal relief  refers to a modification of a fully extended flange so that the  degree  of horizontal undercut engaged is reduced. A shortened or part flange is indicated  in the anterior region where in the interests of conservation of alveolar bone it is considered undersirable to create room for a complete flange by alveoloplasty. Provided a part flange gives adequate retention of the denture it is in general to be preferred to excessive horizontal relief of a flange in order to allow the denture to reach the sulcus beyond a deep undercut area. As a result of  horizontal relief of the border becomes thin and sharp,this could cause trauma to the sulcus. This situation is particularly so in the case of the mandibular denture, where the foundation is triangular when cross-sected. In this situation the denture tends to sink as a result of bone resorbtion during the first few months of extraction.

When creating horizontal relief the dental technician would need  to block out the appropriate areas on the model with plaster, after surveying. When doing this the technician might be required to thicken the flange in order to avoid the flange becoming a knife-edge.

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