Les Cahiers de prothese最新文献

During the tooth preparation for root posts, all must be attempted to avoid weakening of the root. This "must" is rather easy for straight roots, but the same is not true of curved roots. The authors have used the method described by BRAMANTE et al. to study the effects of various techniques of instrumental sequences of endodontic preparation, and of two instrumental sequences of root post preparation. From this studies, it results that: --the respect of the canal path during the endodontic phase conditions the respect of the internal wall of the curvature, during drilling. --among the four endodontic techniques studied: MM 3000, Step-Back, Anti Curvature Filling and Canal Finder System, the last two seem to allow more respect of the canal path. --the instrumental sequence using Largo drills to prepare a canal, presents two types of drawbacks: * Excessive abrasion of the convex (internal) wall of the canal system. It seems that the blunt point rests against the concave portion of the canal and pushes the drill toward the internal wall, therefore weakening it. * Inadequate match between the size of the drill and that of the prepared canal. --the Parapost drills, on the contrary, respect the endodontic path, and may even be used beyond the curvature (2 mm). Besides, the diameter of the prepared canal is similar to that of the instrument used. These two factors permit to obtain a better retention of the post as well as a lesser weakening of the root.

With the introduction of metallic alloys based on rare earth, the dental prothesis disposes of new magnets as a method of denture retention whose retentive force is 20 to 50 time superior to the conventional magnets. There are two main types of magnets: the open field magnets as the Dyna and the closed field magnets as the Gillings and the Jackson. The latters have been devised to avoid propagation of the magnetic field in the living tissues, the harmlessness of this propagation being argued by the researchers. The magnets present several advantages tied to the conservation of the roots as the maintenance of the proprioception, the conservation of the socket bone, the strengthening of the remaining teeth and the psychological comfort for the patient, others tied to the technique itself as the simplicity of realization, the easiness of insertion and removal of the prothesis and the absence of wear. As far as terminology is concerned, we consider a magnet as a magnetic axial attachment.

Analysis of implant failure in the maxilla has showed that these failures were predominant on bone that had remained toothless for a period exceeding 2 years. Histological and osseostructural studies demonstrate that the loss of maxillary teeth has an essential effect on its vascularisation, more than on the bone loss; this vascularisation is absolutely necessary in order to obtain an adequate and lasting osseointegration. When, after surgical preparation of the receiver bony site, no bleeding is noted, insertion of the implant is postponed. Six weeks later, the new socket is curetted and the scar tissue removed; this showed that, systematically, the vascularisation was markedly increased. Results at 2 years of this "endostal stimulation", applied to Brånemark and I.M.Z. implants, are: 95.5% success in the maxilla, compared to 83% with osseointegration during the same period. This technique may be applied in the posterior mandibular area, when there is a marked resorption and the short implant is only inserted in cortical bone, minimally vascularized, because of the presence of the mandibular canal; the results of this latter technique are actually poor.

Among 500 C.T. scan of temporomandibular joint (T.M.J.), examined since 1982 by bilateral direct sagittal method (Department of Radiology, Pr. A. TREHEUX, C.H.U. Nancy-Brabois), the authors have retained 14 cases of patients with symptoms related to dysfunction of the T.M.J. cured by surgery (Department of Maxillo Facial Surgery, Pr. STRICKER, C.H.U. Nancy). These cases were chosen among hundred patients annually examined by C.T. scan, for various diseases (dysfunctions of the T.M.J., traumatisms, infections, inflammatory diseases...). These correlations between radiology and surgery about 26 T.M.J. (2 patients underwent surgery only on one side) were: an accuracy with surgical findings for 19 cases (76%); in 6 cases (23%), a meniscus anteriorly displaced, non detected by C.T. scan was found by surgery; 2 cases of meniscus perforations (one in the frontal plane, the other sagittal) were surgical findings; in 1 case, a displacement was under-valued by C.T. scan; in 3 cases, arthrosic changes (1 case of REITER syndroma) were characterized by C.T. scan. The authors emphasize the value and the limits of evaluation of the internal derangements of the T.M.J. with direct sagittal C.T.

It is generally accepted that some anatomical sites, facial as well as oral, remain stable throughout the life of a human being. In this study, a population of 191 dentulous subjects without clinical symptoms and a mean of 21 years and 4 months, was selected. The first part attempts, from facial landmarks, stable with time, to establish statistics that could provide norms for subjects without teeth and aid clinicians in evaluating the Vertical Dimension, in the treatment of edentalous patients. Mac GEE conducted a similar study without, however, any detail concerning the number and the age group of the sample population. Our conclusions do not contradict the study of this author and give additional details, namely: -14% of the population studied presents the following identical distances: . interpupillary distance, . distance: nasal spine/submental region (in maximum intercuspation), . distance: glabella/nasal spine, . distance: bipupillary line/stomion. -69% of the population studied presents three measurements out of four, which are identical.

According to the osteopathic and chiropractic concepts, facing a TMJ problem, the practitioner has to determine if the trouble observed in the stomatognatic apparatus is the cause or the effect of the structural problems present anywhere else in the body. The postural examination allows to answer this question. Tow techniques can be used. First a static and dynamic posture test proposed by Bricot. The level of the cranium, the eyes, the shoulders, the wrists, the pelvis and the ankles is analysed, from a front view; from the side, the gravity line is inspected: vertex, auditory meatus, shoulder, hip joint, anterior side of the tibia, ankle joint. The vertical posture can be studied from the front: the arms are held straight and the antero-posterior length between the fingers is measured. From the back, one notes the recoil of the buttocks on one side. An ocular convergence test is performed. Then one uses a Romberg test (oscillation of the body when the eyes are closed), and a Fukuda stepping test. The patient is then asked to bite on a compress, and the same exams are redone. If no change occurs, we are dealing with an ascending problem: the origin of the problem is not the stomatognathic system. The second technique is the Meerssemann test that needs the practice of Applied Kinesiology muscle testing. The patient is lying supine and one tests: the dental occlusion, the two TMJs, the temporal muscles, masseters, pterygoids, sterno-cleido-mastoids, upper tapezius, left and right sacro-iliac joints, psoas muscles bilaterally.(ABSTRACT TRUNCATED AT 250 WORDS)