This paper sheds light on retention systems using telescope crowns in fixed and removable partial denture prosthodontics. Although relatively old in concept, these procedures are enjoying renewed interest due to the considerable progress made in precision machining at the dental laboratories. The use of these rehabilitations, simple to understand, nonetheless requires absolute precision regarding their achievement. The practitioner and dental technician must bring to this kind of work a maximum of complementarity; communication must be constant for the reciprocal understanding of the problems faced by each of them. It is important to emphasize the ease of application and the number of solutions proposed by these telescope systems which, despite the ever growing quantity of new techniques must be maintained in the prosthetic and therapeutic possibilities.
The authors propose an original method for the setting of a semi-adjustable articulator based on latero-protrusive check-bites. This study compares two setting methods. The first was used as a control. It makes use of protrusion and lateral check-bites for the adjustment of the condylar path angle and Bennett's angle. The second method, adjusts the two parameters using only latero-protrusion check-bites. Recordings were taken on 15 young patients aged from 24 to 32 years old, having a healthy and complete dentition without any subjective symptomatology of T.M.J. The recordings were always made by the same operator. According to a strict methodology, the same protocole was used for the recording of the check-bites with both methods, mounting of the models on the articulator and adjustment of the angles. For the first method, the check-bites were taken with a 5 mm protrusion previously determined on the articulator. This position was reported and marked in the mouth using indelible ink. Likewise, a 5 mm lateral bites position on the working side was determined for both sides. With the second method, the lateroprotrusion bites were taken with a 3 mm displacement of the condyle on the working side and 5 mm on the non-working side. In both methods, the values of the condylar path angle and Bennett's angle were revealed and compared for all the patients. Subsequently to a statistical analysis, the authors concluded on the similarity of the results for the two methods, confirming the interest of a single latero-protrusion check-bite which is easier to obtain, is economical in terms of time, and entails a lesser number of bites to be made.
The experimental protocol developed in the previous article (4) has been modified to permit the investigation of the fluorescence of shade guides. The following will be traced out on each graphic display: a reference spectrum using full lines; a sample spectrum using dotted lines; the chromaticity triangle of the X Y Z CIE 1931 system; the chromaticity of the sample to be tested, represented by the sign +; the chromaticity of the reference, represented by the sign -. The shade guides without any rare earth have spectra in the form of wide bands; their intensity decreases when the degree of colour purity in white light of the buttons increases. The shade guides containing rare earth have spectra with both a wide band and thin lines. It has been shown that: the same shade guide can contain different fluorescence components; two shade guides from the same source can have very different fluorescences for buttons of the same reference; two shade guides from different sources can have identical fluorescent components. This study reveals: that unadapted fluorescences of shade guide may be the cause of an error in the choice of the colour of a ceramic restoration; that the comparison of spectra appears to prove that shade guides are not manufactured by the ceramic manufacturers which recommend them and are, in fact, of the same origin.
This study shows the interest of using a light cured resin for temporary restorations. The rubber like stade enables easy removable of undercuts and excess material can be trimmed easily before light irradiation. Physico-chemical properties of light cured resin are compared with those of four chemical-polymerizing resins. Exothermic reaction, transverse strengths, modulus of elasticity, and differential scanning calorimetry show the same values as the best autopolymerizing resins. The author presents an original technic, using the light cured resin with light cured composites to achieve aesthetic and strong temporary restorations.
Regardless of the schools or work habits in total prosthesis, the laboratory technician must, following the clinical session of primary imprints, prepare the latter and make models in hard plaster, on which he will develop the individual imprint constructions (IIC). By virtue of a special device developed by the author (the "Lutemat"), the IIC is equipped with two personalized occlusal rings adapted to the particular clinical case, adjusted as of the outset according to the intermaxillary relationships pre-established at the various levels. The final anatomophysiological imprint can be carried out under optimal conditions. Lutemat can be used with most current articulators. It has three principal uses: to permit the spatial orientation of maxillary and mandibular models and to pre-determine the height of the occlusal plan due to adjustable orientation points; to ensure the development of occlusal rings to a predetermined dimension and according to a privilege clinical situation on the occlusal plan, due to a "pocket" instrument; to permit the mounting, on an articulator, of models deriving from terminal anatomophysiological imprints. Following casting of the models and preparing the IIC base, the practitioner places and orients the mandibular model on the Lutemat base. The mandibular occlusal ring is shaped and modeled according to the individual criteria of the patient. The maxillary ring is then made depending on the intermaxillar relationships which were pre-established at the clinical session devoted to the primary imprints. The IIC's obtained using this technique are truly personalized and the later sessions of terminal imprints and recording of occlusion can take place with great ease and comfort.
All prosthetic proposals can be judged only after a lapse of time. After twelve years of clinical practice using the concept of the stress breaker framework the results have been established. The clinical results revealed concern prostheses made according to identical criteria as regards the design (stress breaker framework), kind of prosthetic teeth used, mounting of teeth, imprint technique. The clinical protocol was that used for the comparison and verification, in time, of determined criteria. The criteria used were: the presence of pillar teeth, the absence of re-lowering indication, maintenance of V-O-D. The method involved: 170 cases, 418 pillar teeth, clinical follow-up from 3 to 8 years. The results revealed: preservation of teeth 96% absence of lowering indication 95% maintenance of V-O-D. 95% The analysis of the results shows that the preservation of the tooth pillars and the limitation of resorption below the stress breakers seem to be positive elements which are obtained easily and constantly due to the use of the stress breaker framework used in a movable partial prosthesis.
Although we know that the most favourable situation for preparations margins is above gingiva, it has been proven that in numerous clinical cases, this situation is modified in an apical direction and becomes subgingival. This location of the margins then becomes unfavourable from a periodontal point of view as well as in the control of adaptation. However, the major problem arises when the impression is taken. In fact, the marginal gingiva constitutes an obstacle to the access of the impression material to these margins. Nevertheless, numerous techniques allow the free marginal gingiva to be retracted under such conditions that the principal aim can be reached without injuring the conjunctive epithelio-connection. The procedures used to retract the gingiva are either mechanical, chemico-mechanical or surgical. The mechanical techniques may use copper bands and ring collars, the latter being the procedure of choice when indicated. Another technique uses retraction cords, providing a gingival sulcus enlargement without using impregnated cords with haemostatic or astringent solutions. This last technique, nonetheless, must be avoided if there is a risk that might lead to bleeding when the cord is removed. The second retraction technique uses these same cords impregnated with haemostatic or astringent solutions. It seems that 15.5% ferric sulfate impregnated braided cords represent the procedure of choice, allowing both the retraction of the sulcus and the total absence of bleeding, since haemostasis is ensured definitively via the situ application of the pure product. The final technique is the gingival surgery. It may use Ingraham's diamonds that simultaneously finish the subgingival preparation margins and make a superficial epithelium curettage. Following this surgical retraction, haemostasis is ensured, but the rotative instrument used provides, at once, the best profile of the internal wall of the free marginal gingiva for the impression. The second procedure is electro-surgery which provides constant results when use, thereof, is well indicated. Finally, the CO2 laser can also provide another possibility for surgical retraction. Nonetheless, it seems that the CO2 laser is not the best procedure, given the difficulties in directing it. Depending on the case, all these techniques allow the expected results to be obtained, but, unfortunately, their innocuity is not absolute. In fact, it is proven that following any type of gingival retraction, a lesion is caused both by the practitioner and the equipment used, which thus, leads to a loss of about 1/10th millimeter in the height of the free marginal gingiva.
Today, it is quite easy, even to the unfamiliar practitioner in implantology, to get clear ideas of the surgical stage in treatments where implants are involved. These procedures have been well described and documented, especially by the swedish school. But things are less simple concerning the prosthetical procedures. After a personal experience of years, in this field, both, as oral surgeon and prosthodontist, we think time has come to point out several criterias, leading to long range success. We will review some major aspects of this particular prosthodontics, like: different clinical situations, according to the localisation of edentulism, connections, frameworks and cosmetics, and so on... We are convinced that the respect of these rules is one of the numerous keys of success in today's implantology.
The comparative study of the gingival aspect of dentures made from different flasking procedures, using scanning electronic microscopy, permits the differences in the surface texture of the resins to be assessed. This surface texture will show specific aspects for each technique. The Futurajet resin presents a surface texture with cracks of 100 microns to 200 microns long and 5 microns wide. The appearance of the polymer pellets reveals a good cohesion amongst them. The Futuracryl 2000 resin has an overall surface like an orange peel, with a hills and valleys revealing a rather weak attack of the monomer on the polymer. The palatal surface of the SR-Ivocap resin shows pleats and perpendicular fractures. The surface of the buccal aspect of the ridge is relatively smooth. The Lucitone resin shows a surface with very few irregularities, in which the polymer pellets are well dissolved. In conclusion, no porosities are found on the surface of the various resins. We think that the chemical composition of the resin influences this surface texture and the flasking technique being able to disturb the surface of the resin.
The loss of a maxillary incisor is traditionally treated with a three-unit bridge. The progress made in dental implantology since the demonstration of osseointegration by Brånemark and al. allows the overall replacement of the missing tooth. Furthermore, the use of osseointegrated implants makes the replacement of a single maxillary incisor reliable and aesthetic, even in cases of moderate gingival and bone recession. In respect of the rules set forth by Brånemark and al., it is essential to make a wax-up and a surgical stents. For anterior teeth, the single tooth abutment marketed by Nobelpharma allows the aesthetic margins of the prosthesis to be placed in a sub-gingival position. Once this component is positioned on the fixture, the achievement of the prosthesis is practically identical to traditional metal ceramic crown. The abutment is maintained on the fixture by a screw which can be easily removed and avoids an excess of subgingival cement. Nonetheless, its diameter means that it is reserved for relatively wide teeth. This type of treatment involves the development of a reliable and proven surgical planning for bone grafts, especially in cases of facial traumatism.
The prosthetic treatment of edentulous patients must be carried out with the dual objective of preserving the residual ridges and re-establishing the functional activities of the masticatory system. The authors propose to investigate the subjective efficiency of the prosthesis by an interview of the patients, and the objective efficiency by clinical testing, after one year of use. In this study, a group of 41 patients, males and females, are supplied with bimaxillary full dentures according to GERBER's technique. Special attention is given to the teeth position in relation to the base stabilisation surface. The teeth likely to unbalance the prostheses were not mounted. The inter-maxillary relationship at the horizontal level was obtained by using a gothic arch recording. After one year of use, the following results were obtained: patients very satisfied with their upper denture: 43.9%; patients very satisfied with their lower denture: 39%; satisfied: 51% for the upper denture; satisfied: 56.1% for the lower denture; not satisfied: 4.9% for the two dentures. Only 12 patients (29.2%) had all of their posterior teeth put in. The decrease in the number of teeth did not reveal any significant decrease in the mastication efficiency, according to the patients opinion (2.4%). The original occlusion was restored in 78% of the cases. The authors emphasized the importance of the occlusal relationship and of the posterior teeth for stability and efficiency in the treatment of edentulous patients.
The patient presented an important bone loss in the edentulous area 21 to 23. The 11 had a temporary crown and a removable prosthesis has replaced the anterior missing teeth. The orthodontic treatment of this class II division 1 was to be undertaken in order to reduce the maxillary proalveolie and to line up the mandibular incisors. The difficulty of the orthodontic treatment was due to the importance of the anterior edentulous area which did not allow a continuous multiring treatment but a bilateral one and a succession of anterior removable prosthesis as anchoring points. The temporary crowns on osseointegrated fixtures replacing 22 and 23 were used to obtain the final orthodontic movements needed in the orthodontic preprosthetic treatment. However, if the fixtures had been placed at the beginning of the treatment in order to use them among other anchoring points, the complete orthodontic treatment would have been faster and much easier. At that time, our major handicap was to determine the ideal position of the fixtures which would allow the orthodontic application as well as a successful cosmetic fixed prosthesis. The use of scanner, three dimensional reconstruction Scanlam, surgical stents and fixed prosthesis with inlay cores would have brought the solution to this problem. Today, the use of osseointegrated fixtures can be applied in much more complex orthodontic movements.
Removing an anatomical cast post requires many precaution and, in most situation, gives very good results. Nevertheless, this procedure can be dangerous for the tooth or the surrounding tissues and must be considered only in case of absolute necessity. Two techniques are described using a little hole made in the coronal part of the core. A threaded wire is driven through this hole making possible the use of a crown remover. For the second technique the use of an original appliance, the ATD bridge remover, is demonstrated with very good results too.
This paper describes the rationale as well as some of the therapeutic tools which may be used during simple preprosthetic orthodontic movements. First a typical bracket is examined: the overall design, the base, the slot and the tie-wings. All those components allow mechanical force transmission from the archwire to the tooth in all three orders of movement. In the classic "edgewise" form of treatment, final placement of the teeth is determined by the bends incorporated into the archwire. Conversely, in the more recent "straight-wire" approach, the angulation of the slot relative to the bracket base provides for an optimal positioning of each individual tooth on the dental arch. Mesio-distal angulation of the roots being referred to as "tip" and bucco-lingual angulation as "torque". The bracket also allows bodily bucco-lingual tooth placement relative to the dental arch as a whole (in-out). Prior to a comprehensive treatment, brackets are placed on teeth according to a standard set of criteria. They must be located midway mesio-distally on the buccal aspect in accordance with the true anatomic longitudinal axis of the root. Its occluso-gingival position however can be slightly adjusted according to the individual needs of the case. In more limited situations, where only a few teeth are moved, those rules have to be adapted since the anchorage teeth are kept stable. Examples are presented which illustrate the key features of limited orthodontic movements. Archwires present themselves in various sections and alloys. The most commonly used metals are stainless steels and the more recently introduced nickel-titanium superelastic alloys.(ABSTRACT TRUNCATED AT 250 WORDS)
First the various physical factors involved in retention are discussed. Adhesion is designed by the Gibert formula: [formula: see text] bringing the notion of interfacial surface delimited by the fluid meniscus (epsilon) and the thickness of the salivary film at the site of formation of the meniscus (h). Atmospheric pressure plays a role by the formation of a periphery seal ensuring the creation of a depression of the interfacial fluid in order to oppose the forces of pulling. As a summary, it is important to achieve the formation of a salivary meniscus: with the smallest curvature; continuous despite the mobility of the mucosa; beyond the limit between the free mucosa and the attached mucosa and the "farthest" possible from this area. The purpose of recording the periphery borders is to obtain the highest and widest possible denture flanges without any over-extension or over-thickness. The authors then propose performing a comparative study of the various materials available for recording the periphery of maxillary full dentures, in order to determine which best responds to the criteria of quality mentioned. Several recording techniques are possible, depending on the material used: either a segmented border recording (widely described); or a recording of the periphery seal in one or several stages which is then illustrated by the use of Impregum. For each patient, recordings of the periphery was made according to a protocol always identical and precise; only the material used for this purpose (Kerr compound, regular Neo-Plex and Impregum) varied. The measure taken from these recordings showed that Impregum demonstrates the highest and thickness borders as opposed to Neo-Plex and Kerr compound which provided intermediary results. Thus, Impregum appears to be the material of choice for the optimal recording of the functional periphery seal in maxillary full dentures.(ABSTRACT TRUNCATED AT 400 WORDS)
Balanced occlusion is the occlusal concept used in full dentures. In this article, which describes the technique for mounting teeth according to LUDWIGS, the authors present a very typical equipment (guide punch, tooth guide, positioning and mounting plates...). This provides the dental technician with all the possibilities to create occlusal curves which are individualised for each case in order to achieve a balanced and rational mounting of artificial teeth.
The purpose of these clinical cases is to show the advantages of coping abutments in fixed and removable partial denture reconstructions. These cases try to gather the largest indications for this technique. The emphasis is put on many positive points of this type of reconstruction: control and easy maintenance via an optimal accessibility to the abutments; may be used in complex rehabilitations combined with other types of attachments; easy insertion of the removable partial denture by the patient; improvement in the prognosis for cases that cannot be treated with fixed prosthodontics and precision attachments. A good aesthetic result can be achieved and gives expectation for an encouraging future for this type of well-made reconstruction.
In the technique described, the search for the peripheral joint and the final impressions are really functional and rely on adapted silicone impression materials. The vertical dimension is investigated physiologically (speech/swallowing). The recording of the centric relation is confirmed graphically with a centric pin. Thus, the patient transcribes his "occlusal signature" and provides both the practitioner and the dental technician with precise data for the mounting of denture teeth.
The complexity of this type of restoration comes from the numerous clinical and laboratory steps required. Achievement of these prosthodontic restoration is based on a careful clinical examination, models mounted on an articulator, in centered relation and adequate vertical dimension. The models allow the surveyor examination, the teeth set up and/or wax up. Duplication of the teeth set up in acrylic will reduce the number of patient's appointments, and thus, the potential errors will be minimized. This acrylic teeth set up (A.T.S.) will allow: to keep the decided occlusal relationships; to visualize the teeth grinding to be made; to guide the tooth preparation; to take the abutment impression, in occlusion. Therefore: the final model; the vertical dimension; occlusal relationship; the aesthetic; and, the removable partial denture design will be available for the dental technician. Furthermore, in close to full denture cases (class I and large class IV), the A.T.S. can be used to take the impression, to achieve the framework, and to transfer the occlusal registration.
The long term success of any bonded prosthesis mainly depends on the quality of the marginal adaptation. Its degradation has been noted both at the clinical and the experimental levels. It may be due to biological, chemico-physical, mechanical and clinical factors. Improving the marginal gap closure is based on some principles: the type of preparations on which depends the stabilisation and the good positioning of the restorations; the quality of the clinical isolation which will avoid any humidity on the bonded surfaces (saliva, blood, gingival fluids); the chemical and physical type of the bonding polymer and the quality of its polymerisation; the finishing and final surface condition directly related to the kind of finishing burs used. The understanding and application of these few clinical principles enable the practitioner to expect a better clinical result as regards the bonding of aesthetic restorations.
