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In a study, the effectivity and durability of telescopic dentures on abutment teeth provided with telescope crowns were investigated. The prognosis for the prosthetic structure and for the abutment teeth were both investigated. The survival rate of 234 telescopic dentures (886 abutment teeth) in 147 patients in a general dental practice were retrospectively evaluated on the basis of a status study. The mean survival rate was calculated. This is the moment when 50% of the telescopic dentures had failed. For telescopic dentures in the maxilla, this was 22.3±2.8 years, which did not represent a statistically significant difference from the mandible (20.9±1.9 years). Of the 886 abutment teeth that were used, 127 (14.3%) were extracted after an average period of 11.7 years. Periodontal complications were the primary reason for extraction. Based on this investigation, one could conclude that telescopic dentures are also a durable and sustainable solution in the long term. Loss of abutment teeth is relatively rare and has limited influence on the survival of the prosthetic structure.In een onderzoek werden de doelmatigheid en de duurzaamheid onderzocht van telescoopprothesen geplaatst op pijlerelementen die waren voorzien van telescoopkappen. De prognose van de prothetische constructie en van de pijlerelementen werd eveneens onderzocht. Daarvoor werd van 147 patiënten in een algemene tandartspraktijk de overleving van 234 telescoopprothesen (886 pijlerelementen) retrospectief geanalyseerd aan de hand van statusonderzoek. De mediane overleving werd berekend. Dat is het moment waarop 50% van de telescoopprothesen heeft gefaald. Voor telescoopprothesen in de bovenkaak was dat 22,3 ± 2,8 jaar en niet statistisch significant (p = 0,92) verschillend van de onderkaak (20,9 ± 1,9 jaar). Van de 886 pijlerelementen werden er 127 (14,3%) geëxtraheerd na gemiddeld 11,7 jaar. Parodontale problematiek was daarvoor de voornaamste reden. Het onderzoek toont aan dat telescoopprothesen geplaatst op pijlerelementen ook op de lange termijn doelmatig en duurzaam blijken te zijn. Verlies van pijlerelementen treedt relatief weinig op en heeft een beperkte invloed op de overleving van de prothetische constructie.

The ultimate strength of a dental prosthesis is defined as the strongest loading force applied to the prosthesis until afracture failure occurs. Important key terms are strength, hardness, toughness and fatigue. Relatively prevalent complications of single- and multi-unit fixed dental prostheses are porcelain and ceramic fractures. Afactor which also plays a role is the functional loading force from the entire orofacial system. With respect to the strength of multi-unit fixed dental prostheses, the length of the arch span between the abutment teeth, the pontic with the connectors and the possible cantilevers are the critical components. Components of the configuration ofabutment teeth of single- and multi-unit fixed dental prostheses which are relevant for its strength are the convergence angle and the design of(the area above) the (cervical) outline. Finally, the thickness of the porcelain or the ceramic (veneers) ofmetal-ceramic and all-ceramic single- and multi-unit fixed dental prostheses is of importance.

The degree to which single- and multi-unit fixed dental prostheses are able to withstand loading forces is dependent, among other things, on the quality of their retention and resistance. The quality of the retention and resistance of the configuration of an abutment tooth prepared for a metal and metal-ceramic single-unit fixed dental prosthesis is determined by the configuration's convergence angle, the height, the volume, the interocclusal space, the cervical outline design, the additional preparations, the quality of the (build-up) restoration, and the surface roughness. A silicate ceramic single-unit fixed dental prosthesis is attached through adhesion using a composite cement, but the retention and resistance of an oxide ceramic single-unit fixed dental prosthesis is dependent on the abutment tooth configuration. Most types of multi-unit fixed dental prosthesis have the following additional retention and resistance determining factors: the position in the occlusal system, the number of abutment teeth and their mutual configurations, and the length of (cantilever) pontics. A resin-bonded fixed partial denture's retention and resistance are determined by its bonding as well as its enamel surface coverage and its resistance preparations.

A single- or multi-unit fixed dental prosthesis can be attached to the abutment teeth through mechanical retention and gap sealing or by adhesion. For sealing the gap, water-soluble cements are appropriate, such as zinc phosphate, polycarboxylate, and (resin-modified) glasionomer cement. Attachment through adhesion can be performed with composite cement. If the hard tooth tissue is prepared adequately, composite cement provides sufficient adhesion, but self-adhesive composite cement is now also available. For the adhesion of the composite cement to the restorative materials of the single- or multi-unit fixed dental prosthesis, surface sandblasting, silanizing, and tin coating and the application of a metal primer or chemically active composite are available. Cementing a single- or multi-unit dental prosthesis involves 3 phases: 1. Cleansing the single- or multi-unit dental prosthesis and the abutment tooth/teeth; 2. Preparing the hard tooth tissue, mixing the cement and placing the single- or multi-unit dental prosthesis; 3. Removing the excess cement.

An occlusal system that does not function well, has a negative impact on the functional level of the oral system and the orofacial system. In purely mechanical terms, a limited anatomical reduction of the occlusal system has limited implications for the functional level since the occlusal system has several forms of adaptation, reserve, and compensation. However, following the loss of (parts of) teeth, an occlusal system may be anatomically reduced to such an extent that restoration of the functional level is required, for instance by the use of implant-supported single- and multiple-unit fixed dental prostheses. The mechanical strength of a tooth and a single-tooth fixed dental prosthesis on a similar tooth type is not essentially different. But the same cannot be said of the mechanical strength of a multiple-unit fixed dental prosthesis, because the strength is controlled by the mechanoreceptors in the periodontal ligaments of the abutment teeth. This control system is disturbed by the insufficiency of or, when oral implants are involved, the absence of mechano-receptors. It is unknown whether this is causing noticeable problems.

A resin-bonded fixed partial denture is a prosthetic construction which can replace I or several teeth in an occlusal system and which comprises a pontic element which is adhesively attached to 1 or more abutment teeth. To compensate for the limited shear strength of the adhesive layer, the Jixed partial denture is occlusally supported by the abutment(s). A direct resin-bonded fixed partial denture is made of composite, reinforced or not by a frame of flexible metal or fiber material. For an indirect resin-bonded fixed partial denture, a metal, fibre-reinforced composite or ceramic substructure is fabricated in a dental laboratory. The basic principle of a resin-bonded fixed partial denture is minimal invasiveness. However, a restoration in an abutment tooth requires a certain occlusal space which is realized by tooth preparation. Resistance preparations may be performed to improve the longevity of resin-bonded fixed partial dentures. Both financially and biologically, a resin-bonded bridge is a cost-effective prosthetic construction. The longevity is limited, but when the construction fails the negative consequences for the abutments are generally limited, which leaves open several types of other treatments.

A single fixed prosthesis replaces parts of a tooth. However, a single fixed prosthesis may also be implant supported and in such a case it replaces in combination with the oral implant an entire tooth. A multi-teeth fixed prosthesis replaces 1 or more teeth using pontics and can be fixed on teeth, oral implants, or both. Materials applied are metal, metal fused with porcelain, and ceramic. After indicating a fixed prosthesis, the intended function is determining the appropriate type. Intended functions of single fixed prosthesis are: improvement of aesthetics, limitation of tooth fracture, acting as an abutment tooth for a removable metal frame partial denture, and splinting of mobile teeth. In addition, single fixed prostheses may be characterized by the number of replaced tooth surfaces and by the peripheral extension of the tooth preparation. The intended functions of a multi-teeth fixed prosthesis are improvement of aesthetics, chewing function, and occlusal as well as mandibular stability. Specific types of fixed prosthesis are used as temporary restorations and in case of evaluating preliminary treatments preceding a final treatment.

When compared to a conventional attachment, a (semi)precision attachment for a cast metal frame removable partial denture can perform a number of functions better. Proper assessment of the condition of the abutment teeth is needed for an adequate indication. Selecting the type of (semi-)precision attachment is primarily determined by the available maxillomandibular space, the crown length as well as the possibility of adequate oral self-care. With regard to technical characteristics, (semi-)precision attachments are classified according to measures of freedom. The distinct types are cast intra- and extra-coronal, adhesive and overdenture (semi-)precision attachments. With the lapse of time, some wear of the different parts of an attachment may occur, requiring specific subsequent care. Whether or not in combination with oral implants, (semi-)precision attachments often offer patients improved self-confidence and self-image. However, the relatively high cost is a barrier to apply (semi-)precision attachments widely.

Oral health care providers have the full responsibility for designing metal frame removable partial dentures and making all of the necessary preparations. Important principles of design are that the denture should hamper natural cleaning and daily oral hygiene as little as possible and that it should have good stability and retention. The designing process follows several phases without a strict chronological sequence. If it is necessary to return to a previous phase, the process follows a circular sequence. The usual phases are evaluating dental arch study casts, examining diagnostic set-ups, selecting abutment teeth, surveying dental arch study casts, selecting the major connector, selecting minor connector and clasp types, selecting artificial teeth, modifying the denture design from theoretically ideal towards practically optimal, and carrying out the intended tooth preparations in a dental arch study cast. Tooth preparations in the working cast together with a denture design prescription will provide the dental technician with the information needed for manufacturing the metal frame removable partial denture.

When considering prosthetic replacement of absent teeth, a treatment plan is necessary. In evaluating whether replacement of teeth is sensible, the causes and consequences of tooth loss must be considered. This concerns information about problems having to do with the patient, potential complications, purely prosthodontic problems, and specific problems. The patient-related problems require collecting data through patient history as well as a clinical and radiologic examination. Complications are risk-factors which negatively influence the prognosis of general health or of a treatment. Potential complications should be eliminated as much as possible through a preliminary treatment. Purely prosthodontic problems are conditions in the area of absence of several teeth or parts of them, and in the area of occlusal and mandibular stability and articulation. Specific problems may be related to inadequate interocclusal space and the quality of the abutment teeth. A cast metal frame removable partial denture may be a relatively inexpensive and minimally treatment alternative for an expensive and complicated treatment with 1 or more fixed partial dentures.

Mechanical and biological criteria have to be met in retaining the metal frame of a removable partial denture. Additionally, a removable partial denture is part of the occlusal interface by the clasps and the denture teeth. With respect to mechanical aspects, all rigid parts of the removable partial denture are of importance. However, as clasp arms tend to loose retention during long-term function, it is primarily the minor connectors and rigid clasp arms that provide stability and retention by friction with the guiding planes of the abutment teeth. With respect to biological aspects, comfort and cleansing ability are most important. Their functioning is enhanced by a low number of components crossing the marginal gingiva, such as minor connectors and infrabulge clasps. In the occlusal interface, occlusal interferences both in occlusion and during articular excursions should not be introduced by retainers or denture teeth.

A proposal for restorative treatment is based on the expected efficiency of the treatment. Efficiency is determined by measuring the investment, such as the monetary and biological cost, against what is gained, such as functional restoration and durability. If one's goal is to save tooth tissue in the restorative process, it is interesting to compare the conventional fixed partial denture with the adhesive fixed partial denture. The mean survival rate of conventional fixed partial dentures clearly exceeds the mean survival rate of adhesive fixed partial dentures but there are biological risks. Loss of vitality of the abutment teeth and the occurrence of caries are more prominent with conventional fixed partial dentures than with adhesive fixed partial dentures. Consequently, the possibility of replacing a conventional fixed partial denture with a new conventional fixed partial denture is limited. Because this and other clinical aspects can not easily be expressed numerically, the patient should be informed qualitatively about the advantages, disadvantages and uncertainties of the various types of fixed partial dentures.

In clinical practice, the prognosis seems, with some reservations, to be comparable for tooth-implant and implant-implant supported bridges in the middle-long term.This conclusion seems particularly valid for tooth-implant bridges in free-end situations, where a single implant is connected with a tooth. Prerequisites are a healthy tooth abutment, a pontic length not exceeding the width of a bicuspid, a rigid connection between implant and tooth and the use of strong cement.

Fracture of the implant abutment screws is a complication which can render an implant useless. The prevalence of abutment screw fracture does not exceed 2.5% after 10 years. Causes are loosening of implant abutment screw, too few, too short or too narrow implants, implants not inserted perpendicular to the occlusal plane, improper suprastructure, too long free-ending parts of the suprastructure, improper occlusion concept, premature occlusal contacts, parafunctions, inadequate skills of the dentist, and fabrication failures. Methods of removing a fractured implant abutment screw piece are, among others, the use of a self-made screwdriver and the use of a service set available for the specific implant system.

Since twenty years adhesive dentistry plays a certain role in the design of removable partial dentures. With the use of adhesive attachments the esthetics and retention of a removable partial denture can be improved. To apply these attachments successfully the contour of a sound abutment has to be corrected by grinding to provide retention and resistance. The procedures for constructing removable partial dentures with adhesive attachments are described. It is recommended to apply adhesive attachments in the general dental practice.

Conventional resin-bonded bridges are designed with adhesive surfaces on both sides of the dummy. As a consequence both abutment teeth are rigidly connected to each other. Loading of the abutment teeth or dummy will lead to wringing forces in the cement. Adhesive bridges with one adhesive surface are actually cantilever bridges. Theoretically this type of bridges will be less prone to wringing forces due to loading. However, long term research into the performance of cantilever resin-bonded bridges (RBBs) is hardly available. The results of research into the longevity of conventional RBBs differ remarkably between Europe, and the United States and Japan. These difference are discussed in this article. This article compares the fixed-fixed design RBBs with the cantilever RBBs. The differences are discussed based on eight articles, the earliest being published in 1991, which are dedicated, completely or partially, to the subject of cantilever adhesive bridges. One can conclude that in The Netherlands RBBs are wrongly considered to be unreliable. On the contrary, they appear to be reliable and predictable restorations provided their preparations meet the right standards. Although a number of authors conclude that cantilever RBBs are performing better than their fixed-fixed design counterparts in similar situations, further research is needed concerning the longevity of this type of adhesive bridges.

Single-tooth implants have become a predictable treatment option. Acceptable esthetics are an important factor for success. The emergence profile of the crown in the cervical region is complicated by the discrepancy between the round shape and the small diameter of the implant and the desired anatomical shape of the crown. An abutment on an implant has to provide this natural looking emergence profile and has to support the crown. Custom-shaped abutments are the best option for this task. Many items influence the design. This article discusses a set of guidelines for the design of custom-shaped abutments for single-tooth implants.

The present study reports the final analysis of a randomized controlled clinical trial in which different designs of posterior resin-bonded bridges were evaluated for a period of at least 5 years. The operational hypothesis was that the bonding system and the preparation design used in posterior resin-bonded bridges have an influence on the survival and clinical functioning of these restorations. Survival in this study was defined at two levels: (1) 'primary' survival (survival without any debonding), and (2) 'functional' survival (survival including loss of retention on one occasion and successful rebonding of the original resin-bonded bridge without further debonding). Preparation of grooves in abutment teeth for posterior resin-bonded bridges appeared to be beneficial to their chance of survival. Resin-bonded bridges placed in the maxilla have a better prognosis than those made in the mandible. The bonding systems used in this study (etching/Clearfil F2, sand blasting/Panavia EX and silica-coating/Microfill Pontic C) appear to have no influence on the chance of failure with regards to the 'primary' survival. In rebonded posterior resin-bonded bridges, the bonding system silica coating/Microfill Pontic C was more retentive than the other systems tested.

Implant treatment in case of a single missing tooth can potentially lead to a well functioning and aesthetically pleasing single crown on an implant. However, in order to achieve an optimal treatment result, a long road has to be travelled since usually resorption defects have to be repaired and soft tissue corrections are frequently necessary. This paper provides information regarding commonly observed situations and their consequences for the prognosis of implant treatment. It is concluded that a single tooth implant can be an elegant solution, though not an easy one. It requires a high degree of experience and surgical and prosthetic capabilities of the dentist. The natural situation can only be mimicked if all stages of treatment are adequately planned and conducted and if no major complications occur in the process. To prevent disappointments, both dentist and patient should be well aware of all conditions required for an optimal result.

Aim of the study was to evaluate the Computer Integrated Ceramic Reconstruction (CICERO)-system and the Ceramic Reconstruction (CEREC)-system for the production of all ceramic copings for partial coverage. Posterior teeth were prepared and the stone dies were made. Accuracy analyses were performed on ceramic restorations made by means of the CICERO and by means of the CEREC technique. The marginal gaps were compared to that of a control cast metal restoration. The results demonstrate that the marginal gaps of the CICERO and CEREC copings varied respectively for the premolar 58-80 microns (mean 69 microns) and 71-91 microns (mean 81 microns). For the upper molar 63-92 microns (mean 78 microns) and 68-110 microns (mean 89 microns) and for the lower molar 54-98 microns (mean 76 microns) and 73-99 microns (mean 86 microns). Control cast metal partial coverage restorations showed marginal gaps of 33, 49 and 41 microns. It is concluded that computers can produce copings for partial coverage preparations on stone dies with a mean marginal gap for CICERO copings of 74 microns and for CEREC copings of 85 microns. These values were obtained before optimizing the marginal fit by means of porcelain veneering.

To prevent caries and periodontal disease in overdenture abutment teeth, daily application of chlorhexidine gel is recommended. In order to get insight into the use of the gel, 29 overdenture wearing patients were interviewed. In addition the patients were requested to show the use of the gel. It was concluded that at any time the patients were instructed about the use of the gel. Nevertheless, a majority of the patients did not use the gel daily and in accordance with the instructions given. Application of the gel in the abutment depressions of the overdenture appeared to be a heavy task.

A study of immediately fabricated composite-etch bridges by using the crown of the extracted tooth as a pontic or by using a full-composite pontic is presented. The teeth to be replaced were to be extracted because of severe periodontal problems. The lifespan, the need for repair and possible advantages of this semi-permanent bridgework are discussed. The results indicate a favorable prognosis for this type of treatment in cases where there is a wish for postponing the insertion of removable partial dentures or extensive crown and bridgework.

The problems involved in the loss of anterior teeth differ essentially from those in the premolar/molar region. Firstly, missing anterior teeth result in unacceptable changes in appearance and speech, making treatment mandatory. Secondly, the dentist has to consider specific aspects, such as aesthetics, resorption of the alveolar bone, loading of the abutment teeth, form of the clinical crown and incisal guidance. Treatment options comprise orthodontic closure, periodontally supported removable and fixed appliances and appliances supported by implants. The advantages and disadvantages of the different options are indicated.

Although modern developments in dentistry constrict the indication of removable partial dentures, there is still a number of situations in which a partial denture may contribute to the re-establishment of function, esthetics included. Thereto it is a necessity that all parts of the construction are carefully designed, with special attention for color and form. Choice of the artificial teeth (material), the handling of the acrylic and an adequate anchoring are all important factors in reaching an optimal result.

A study undertaken in a general dental practice shows post-operatively a beneficial effect of regular subgingival scaling. A relative short time investment, once to thrice a year, appears to stabilize the periodontal situation of abutment teeth, even periodontally weak ones.