Les Cahiers de prothese最新文献

A two-dimensional finite element partial mandibular model allows a first comparison between two types of titanium cylindrical implants, one full, the other hollow. The study cases correspond to a distal edentulous rehabilitated with a three-unit bridge supported mesially by a healthy second premolar and distally by one of the two concerned implants. The model includes the mandible from the canine region to the condyle, and allow to investigate the interactions between implants and bone tissue, under a normal biting load (100 N) distributed over the different teeth of the model. On a general way, the highest stresses magnitudes are in the implants, so there are no pathologic actions in bone, even if the distal cervical region of the implants are more stressed than any place else of the alveolar bone. It is well known that bone resorptions are often found in that region. Furthermore the bone trunk of the hollow implant is no more stressed than the rest of the mandibular, that is good for bone affixing. The outcome of this work, over the first results exposed, is that it gives the opportunity to understand the complexity of such a problem.

Implant supported posterior restorations must be constructed following established prosthetic principles. The need for screw-retained abutments and the narrow diameter of root form implants dictate additional treatment protocols that fail beyond the scope of conventional prosthetics. Cemented restorations offer simplicity and good control of morphology, but can only be considered if no reservicing and removal of the restoration are anticipated. Screw retained restorations allow for reservicing on remediation but necessitate centering of the fastening screw within the occlusal anatomy. In case of implant misalignment, axis problems are solved with preangled or customized copings, or double frameworks. The diameter of root form implants is significantly smaller than posterior natural teeth and the emergence of the restorations must be progressively flared to achieve proper anatomy. Limited interocclusal space and implant placement may dictate restoring posterior teeth as premolars selecting a short abutment or a UCLA abutment, or overlapping the crowns over the soft tissues. The final selection is best assisted with a diagnostic waxing and with provisional restorations anticipating the completed treatment.

The edentulous distal extension area has generally been restored with a removable partial denture. Some clinicians report long term success with a fixed partial denture containing distal cantilever pontic(s). Conversely, other clinicians find that the aforementioned is suspect at best due to the unusual stress demands placed on the abutment teeth by the pontic(s). When a tooth borne fixed partial denture is used to restore a long edentulous span, reports vary relative to long term success. The advent of osseointegrated implants as tooth substitutes may reduce and often eliminate particular compromised fixed or removable partial denture designs. Disregarding other problems that may or may not coexist with any remaining natural teeth in the same arch is a fallacious overview. It is paramount that future problems must be incorporated in any and all treatment plans at the same time the initial plan is formulated. Recent surveys reveal that a fewer percent of the population are becoming completely edentulous. Therefore, it is apparent that an increase in the treatment of the partially edentulous implant patient is a realistic consideration for all restorative dentists. However, it is ironic that those patients with the most severely debilitated conditions may often not be candidates for implant procedures. It is mandatory that a detailed explanation of any compromises and drawbacks to the final result must accompany the initial diagnostic presentation to the patient. It is quite evident that the dentist is confronted with a paradox that is difficult to resolve.(ABSTRACT TRUNCATED AT 250 WORDS)

Thanks to the combined evolutions of surgery and of the concept of implantology it is now possible in the case of prosthetical rehabilitation to associate function, aesthetics and phonetics. The pre-prothetical analysis makes it possible to determine the various stages of an all-inclusive treatment namely: periodontics, surgery, prosthetics and occlusal equilibration, so as to obtain the appropriate results. The surgical problems caused by bone resorption in the toothless places are worsened by mechanical ones due to a deficiency in the parallelism of implants. Nevertheless the post-implants will be placed in the prosthetical corridor chosen before surgery. The aim of this article is to study the different types of junctions, permitting to link the implants to the prosthesis, whether it will be cemented of screwed. Depending on the clinical case, the choice of a connector, hence of a system of implants is determined by a number of questions such as: will it be easy to place the post-implants in the prosthetical corridor and to parallel them? Will it be possible to use systems permitting ductility or not? Is there any risk of the connector going loose? To what extent will the aesthetic function be respected? (Screw heads in the case of removable prostheses as well as gingival finishing lines of the superstructures).

Occlusion plays a significant role in the successful restoration of natural teeth and in replacing missing teeth. Over the decades, standards for occlusion have been established. Implants, osseointegrated, have provided a rigid, usable abutment for restorations of occlusion and for the replacement of missing teeth. The natural tooth, due to it's mobility dynamics, presents problems related to occlusion. The osseointegrated, rigid implant, due to it's lack of mobility, presents in many respects problems related to occlusion. Substantial amounts of research has been presented on implants as it relates to success of osseointegration and acceptance by bone, and the acceptance of oral mucosal tissues to penetration of the implant. Failures of implant fixtures and their parts have been experienced. Not much information has been presented on the causes of failures. The question becomes obvious What is the role of the forces of occlusion? The purpose of this article is to present some aspects of occlusion that are important in restoring natural teeth and complete dentures. The problems in applying these aspects to the osseointegrated, rigid implant will be presented. The factors to consider in the control of the forces of occlusion in using implants will be established. It is not possible to cover all the possibilities of occlusion for implantation. However, the factors to consider in making intelligent choices will be presented.

Today, several prosthetic options can be used with osseointegrated implants. Fixed bridges may be retained by screws or cemented. Detachable bridges may be screwed on cylindrical, conical, straight or angulated abutments. In certain cases, they will be placed directly in contact with the implants. Cemented bridges may be placed over screwed, cemented or transfixed copings. They also may be cemented over transfixed metallic structures already splinting the implants. Removable prosthesis may be stabilized with bars, stud attachments or magnets. All these different options are discussed, and their advantages and disadvantages presented.

The incorporation of the Brånemark root-form osseointegrated implant into the practice of Prosthodontics has opened up a new range of treatment options previously unavailable to our patients. No longer limited to their original use in restoring the completely edentulous arch, the role of implants now includes the replacement of one or more missing teeth in partially edentulous situations. Implants may also be incorporated into periodontal prostheses as supplemental support where the number or strength of existing natural abutments is inadequate, and used as a means of salvaging prostheses which have failed as a result of the loss of strategically important abutments. These newer applications, however, combined with patient demands for the optimum in esthetics as well as function, have served to challenge our ingenuity and resourcefulness in this rapidly evolving field. The objective of this paper is to provide an overview of the evolution of our implant experiences in recent years, and to illustrate the ways in which the Brånemark system has been utilized and adapted as the number and complexity of clinical situations have increased. Simply stated, the technical aspects of prosthetic treatment, those involving impression techniques, materials, etc., have remained fairly constant throughout our implant experience. The more dramatic changes have occurred through the utilization of newer components as they have become available, as well as through a growth in our application of the system and in our approach to treatment planning. The Brånemark system has been in use for just over 25 years at this point in time and has proven itself to be reliable, predictable and at the same time versatile enough to admirably meet the challenges placed on us by the new and varied clinical situations we are now undertaking to treat. It is by using our imaginations to stretch the limits of the system without overstepping its boundaries that we have reached the point where osseointegration is truly becoming a part of our basic armamentarium in the practice of Prosthodontics.

The first dental prostheses used on Branemark implants were aesthetically disappointing both for the dentists and their patients. Therefore the authors will consider the various aesthetic problems encountered when treating loss of teeth with implant systems. The problems related to resorption are numerous: large bone losses are resolved by adapting removable acrylic, carrying out bone transplants immediately fixed by the implants, using filling materials, or complete dentures fixed with attachments supported by the implants. Periodontal surgery often provides a solution to the problem of gum visibility at the level of the maxillary anterior teeth. The problems related to the site where implants emerge can often be avoided by consultation between the surgeon and the prosthodontist and by flexing a surgical guide compiled from a pre-prosthetic analysis of the clinical situation. The aesthetic problems related to the actual implant systems are dependent on three factors: When the prosthesis is directly screwed onto the implant, the axis of the implant determines the axis of the dental prosthesis and can lead to the emergence of the screw on the buccal surface; With angulated cores, orientated screws provide the required solution. The implant material, when metallic leads to an unsightly border at the gingival level. Ceramic implants, or the "ceraming" of titanium, provide a solution to this problem. In case of diastema the use of an implant system gives the best choice in comparison to the more conventional treatments. In conclusion, the authors point out the importance of pre-implant analysis which must give an evaluation of the aesthetic result. The fragility of the aesthetic evaluation should encourage dentists to obtain the "clear and written consent" of their patients, accepting the risks run by treatment of this kind.

In the past decade, the technique of osseointegration has elicited three general responses in the dental profession. The first and major response has been an enormous clinical satisfaction to resolve difficult prosthetic problems, as well to expand the scope and range of routing prosthetic therapy. A second, if minor, response has been an attempt to deny the documented apparent superiority of the osseointegrated method. The third response has been a very active marketing one, which led to the rapid proliferation of a large number of implant systems, all claiming osseointegration and comparable success to the originally introduced Swedish system. The purpose of this paper is to describe and analyze those clinical criteria which can be used by dentist and researcher to determine the long term success or failure of functioning dental implants. Some attempts had been made to identify criteria which reflected sound scientific consideration of long term host acceptance of functioning implants. However, these criteria where a reflection of the state of the art information as perceived by the authors at the time. It is therefore fair to add that the principle of osseointegration did not feature in our colleagues recommendations. Since it is an axiom that host response must be analyzed and understood if a clinical technique is to be successfully prescribed, we regarded our own and other's published data on clinical results with osseointegration as pivotal in the grouping of criteria which would comprise a reliable yardstick, easy to identify and apply, and which reflected assessment experiences in dental practice and research, mainly in the disciplines of periodontics and prosthodontics.(ABSTRACT TRUNCATED AT 400 WORDS)