K. Tsoutis

The rehabilitation of the edentulous maxilla with fixed implant-supported restorations is a challenging task for the clinician but very frequently demanded by patients. Prosthetically driven implant placement simplifies the design of the restoration, but severe bone resorption may prohibit the ideal positioning of implants. Bone grafting is often required to improve the bone substrate and to allow proper implant placement. The posterior maxilla can be treated by sinus floor elevation, while alveolar ridge atrophy in the anterior jaw may be improved by horizontal augmentation. The restoration must replace the missing soft and hard tissue, so the use of gingiva-coloured polymer material is often required. The objective of this article is to describe the clinical and laboratory stages of the rehabilitation of a completely edentulous patient with a fixed implant-supported prosthesis. A bilateral sinus lift and horizontal augmentation of the maxilla with bone graft from the iliac crest was performed. The prosthetic rehabilitation is also described in detail, consisting of a combination of screw-retained frameworks and cemented fixed restorations.

Occlusion of complete dentures has been a concern since many years. From the beginning of the 20th century, several dental pioneers were the developers of numerous posterior tooth forms and arrangements. Some of them are used until nowadays and in many of them a lot of changes have been made. It is interesting, however, that none of these occlusal schemes is accepted universally. All of them have advantages and disadvantages and there is very little longterm scientific research to demonstrate the advantages of one over another.\nIn this review, the occlusal schemes for complete dentures that are used today are described.

The restoration of patients with severe bone loss is a difficult clinical procedure as the team of health professionals has to restore the missing teeth and the soft and/or hard tissues. The bone loss is usually caused on the alveolar processes and it is usually caused by periodontal disease. In cases of trauma the bone loss may be extended. In such cases the initial treatment is focused on the trauma and the prosthetic treatment is adapted to the clinical situation. The main goal of the treatment is the restoration of the patient in order to improve their quality of life. Patients with trauma show often a low self-esteem and the prosthetic restoration may contribute to a sense of self-confidence and improve function and esthetic result.

Passive fit of metal frameworks has been a major concern for the researchers because of its possible contribution in the development of complications that could endanger the prognosis of implant-supported prosthesis. The transmission of forces from a non passive metal framework, through the abutment, to the underlying bone has raised concerns about the possible complications. The extend of the problem is enhanced by the fact that achieving passive fit with current know-how seems not feasible. The uneven distribution of forces combined with their increased values, related to the lack of passive fit, have been related to both biological and mechanical problems concerning bone-abutment-superstructure system. In literature, loss of\nosseointegration, pain and inflammation, loosening or fracture of screw joints, abutments, metal framework or even implants, comprise the possible complications attributed to the misfit. At the same time, the term misfit is not completely clarified and the variety of clinical methods that are used to identify it, display many restrictions. Apart from lack of determining with specific criteria the fit of the framework clinically, the confusion concerning the degree of misfit that is biologically accepted merely perplexes the problem. Current bibliography has not yet achieved to document a clear correlation between those complications and misfit of metal framework. On the other hand, the presence of unfavorable forces cannot be underestimated.\nTherefore in order to prevent this phenomenon in the laboratory a great number of techniques and different alloys have been developed so as to achieve passive fit of superstructures if possible. However, this has not been accomplished for the time being.