Les Cahiers de prothese最新文献

The advent of osseointegrated implants has considerably influenced the treatment of the edentulism. The Brånemark's protocol allows a high enough degree of predictability for a wide variety of clinical applications. A selection of the most typical indications attempts to focus on the benefit of implant supported prosthesis, regarding the conventional prosthetic treatment. The relative indications concern single-tooth replacement and Kennedy class III situations where classical tooth supported bridge is not easily feasible. The resort to osseointegration treatment enhances the possibilities of prosthetic rehabilitation in unfavorable conditions. The greater part of the indications is represented by Kennedy class I and class II situations. Clinical examples selected show the different combinations related to the fixtures position in the maxilla where bone availability is reduced. When just one fixture can be installed, connection with adjacent tooth must be carefully indicated. With two fixtures, a bridge must be designed with a posterior cantilever. But the opposite dentition can also dictate a fixture installation in the posterior region for a good occlusal stabilization: a specific modality of fixture installation in the pterygoid region has provided a seductive alternative. The last part concerns the prosthetic rehabilitation of advanced cases involving evolutive periodontal disease. The current trends determine a flexible approach with strategic extractions and progressive fixtures installation during stabilized periods of the disease activity. This management of the treatment planning reduces the psychogenic stress related to the complete edentulism and allows a easier transition from partial implant supported-prosthesis to fully bone anchored-prosthesis.

How can almost every oral implant manufacturer claim success rate of nearly 100%, when clinicians are still in the process to include implants in their practice. Articles on long-term data are still scarce in the international Journals today. Often the different safety and effectiveness of various implant systems are based on the data that Professor Brånemark started to collect 25 years ago. To interpret an article demands knowledge about study design, statistical analyses as well as type of diagram. There are number of important aspects to consider when reading a report on success rates. To understand why some studies can show almost 100% success rates for the upper jaws and others 80%, one must be aware of the important parameters which affect the results. In order to compare the results of one study with the results of another, these parameters, and how they are applied must be taken into consideration.

Incorporating contemporary implant research and the most advanced principals of biomaterials and bioengineering puts HA-coated implant system into clinical practice. This system utilizes a streamline precision two-stage procedure similar to the swedish method and other osseointegrated systems to ensure complete fixation and an unloaded healing phase prior to the functional use of implants. The surgical concept has been theoretically improved upon by enhancing the titanium cylinders with a HA coating of 50 to 65 microns to the body. The advantages of HA have been extensively discussed. Research has shown that a biochemical reaction occurs between HA and bone and the interface between bone and ceramic is stronger than either the ceramic or bone alone. Bone adapts well to all biocompatible metals and bone will "chemically" bond to HA. An activated sintering process has been developed that enables HA to be chemically bound to the titanium cylinder using a modification of the plasma flame spray technology. This HA coating has been developed to meet the most rigorous biomechanical requirements for bonding in high stress applications of orthopedics as well as intraoral use. Biointegration is defined as "mechanochemical" clinically significant interface that predictably develops between vital load bearing bone and a bioactive calcium-phosphate ceramic metal such as HA. The design and planning of the HA-coated metal system also provides a variety of restorative choices and have been extensively discussed in this article. Clinical reports appear excellent, and the current implant system is into its fifth year of clinical use. The use of HA-coated implants has very well satisfied restorative needs as well as following sound biologic principle.

Osseo or bio-integrated implantology has become the turning point in modern dentistry and every decision regarding treatment planning should take into consideration the possibility of implant, and combine the knowledge of specialists such as periodontists, implantologists and prosthodontists. The psychological, medical and local evaluation will decide about the choice of the right patient for implant in order to resolve a unit, partial or full edentation. The periodontal therapeutic of the residual teeth will be realized before any insertion of implants and will focus more on elimination of the periodontal diseases on teeth that should be maintained, that on the maintenance on the arches of teeth with poor prognosis. The early extraction of these teeth and their immediate replacement by implants are recommended on certain conditions. The two step procedure in surgical implantology should respect the biological principles in order to obtain and maintain the osseo or bio-integration. The objectives of the post-implantology periodontal treatment will not be limited only to the elimination of the pocket around the implant, but will also create an optimal environment of keratinized attached gingiva around the collar of the implant, necessary for functional and esthetic purposes. The prosthodontic treatment on implants will be conducted with care and according to the perio-occluso prosthetic principles. It is finally essential to preserve the gingival health around the implant and to prevent a gingivitis to become a peri-implantitis, by a regular maintenance and evaluation.

The reconstruction of an edentulous maxilla with bone graft is not a challenge. It is considered when the remaining bone cannot provide a firm anchorage for implants. The grafts are harvested from the ilium, the chin or the cranial vault. According to the case, the implants are placed either simultaneously or 6 months later after control with C.T. Scan. They are uncovered after another 6 month period, as in the usual procedure, and osseointegration is checked. The percentage of success on 24 operated cases seems at least equal to the regular cases without bone graft. Longer follow-up is needed for reliable statistics.

The treatment success of a removable partial denture is conditioned by the respect of the base structures, tooth abutments and hard and soft tissues. In order to achieve this goal, the prosthesis should be in accordance with the following fundamentals: tissue duality (STEIGER diagram); visco-elastic behaviour of the mucous membrane (TURK, KYDD, DALY, PICTON WILLS); JORES, LERICHE and POLICARD principles. The proposed prosthetic solution, the stress breaker framework allows the disconnexion between the saddle and the framework as well as between the different saddles. The originality of the concept is due to the particular design of the framework, which permits the disconnexion of the saddle. Due to its principle, the displacement of the saddle takes place only when mastication forces are applied on the prosthetic teeth. These movements stimulate the bony tissues. The clinical construction of a stress breaker framework can be adapted to all types of edentation, as well as to sub-total dentures. The clinical results shown that, after twelve years of experience, the stress breaker framework allows the preservation of the abutments as well as the conservation of osseo-mucous tissues (no need of rebase). Several experimental research investigations have been carried out. Work on trial banks have revealed that, compared with the semi-rigid framework, the stress breaker framework lays less stress on the abutment and provides a better base surface beneath the saddle. Other studies have dealt notably with the displacement of the saddle as well as with fatigue tests of the prosthetic system. These studies have led to the development of specific preformed systems.

The possibility of placing fixtures between periodontically compromised teeth enables the immediate conversion from a fixed prosthesis supported by natural abutments to a temporary one supported by osseo-integrated fixtures. During the second surgical stage, the bridge on natural teeth is removed, the abutments are placed on the osseo-integrated fixtures and a new temporary bridge is prepared out of acrylic resin and gold cylinders screwed on the titanium abutments after the extraction of the residual teeth. The temporary bridge is realised for one side of the arc and then the other in order to control at all time the occlusion as well as the cosmetic aspect of the bridge. This approach avoids the passage by a mobile denture, shortens the healing period from 18 to 6 months and enables the prosthodentist to foresee the potential problems with the permanent fixed prosthesis.

With the "In-Ceram" system ceramic constructions are made without any metallic support. The cosmetic ceramic (Vitadur N) is reinforced by an aluminous oxide framework made with a bio-ceramic containing 85% aluminium. The nature of this bio-ceramic and its use provide the originality of this procedure. In order to make this framework, a replica in special porous plaster is made based on the working model. This replica is plunged into a "barbotine" (aluminous oxide grains in suspension in water) which is deposited on the surface. After modeling this paste with a brush, the totality is dehydrated and brought to 1, 100 degrees C for 2 h without. This still fragile calcination is infiltrated by coloured glass. This second thermal treatment is carried out, after dehydration, at 1,080 degrees for 2 to 4 h, still vacuum. The second heating allows the calcination to become coloured and fill in the porosities. The conventional feldspar ceramic is then placed onto this very resistant (more than 580 MPa flexural strength) and exceptionally well adapted framework. This procedure is remarkable regarding the marginal adaptation, the quality of the aesthetic result, its biocompatibility and its ease in positioning. Moreover, the minimal thickness of the aluminium coping is 4/10 mm on the lingual and 3/10 mm for other sides, which therefore do not require any more laboratory work than what is required for making a ceramo-metallic crown. Clinical follow-up over four years allows it to be stated that the mechanical and aesthetic qualities of the procedure permit the making of: single anterior and posterior units which can be made splinted; anterior maxillary small bridges (3 or 4 units) under normal occlusal conditions; posterior small bridges, under favourable occlusal conditions.

Dental porcelain emits some fluorescence under the action of ultra-violet rays. This emission may be at the origin of errors in the choice of the colour of a crown. In order to study this fluorescence phenomenon, the following experimental protocol has been developed: 363.8 nm exciting radiation isolated from the emission by an Argon laser; Fluorescence emitted by the sample and dispersed via a spectrometer, protected by a stop-U.V. filter; Influx collected by a photomultiplier, then directed, after passage in a picoamperemeter, toward a mini-computer programmed to print the spectra; Correction of the spectra by a tungsten lamp used at the 2,600 K colour temperature; Use of reference spectra. On the same graph, the sample spectra are represented in solid lines, while the spectrum of the enamel used as a reference is shown as a dotted line. The results show that: Enamel has a fluorescence spectrum which has the shape of a wide band, with a maximum of 450 nm (characteristic of a blue-green shade) and a slow decrease up to 680 nm. The enamel fluorescence does not depend on the colour of the tooth; Dentine has a distribution spectrum which is similar to that of enamel but is three times fuller; The spectra of the ceramic samples reveal: a wide band due to transition metals, fine lines due to rare earth (terbium and europium). When the saturation degree of the ceramic increases, its fluorescence colour varies due to the relative increase in the amplitude of the lines in relation to the bands. Thus, when the sample colour progresses from B1 to B4, its fluorescence colour becomes greener.(ABSTRACT TRUNCATED AT 250 WORDS)