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There are few published studies that directly assess the quality of impressions for crowns and bridges in the UK. This paper considers aspects of impression quality with particular attention to factors causing potential occlusal discrepancies in the final restoration. To this end three dental laboratories were visited over a 3-month period. All impressions for conventional crown and bridgework that arrived on the days of the visits were examined and assessed against criteria defined on a custom-designed assessment form. A total of 206 impression cases were considered in this study. Flexible impression trays were used for 65% of working impressions. Their use was more common for NHS work than for private work. 31.9% of all alginate impressions examined were not adequately fixed to the tray. Visible contamination of impressions was not uncommon.

The literature is limited in studies directly assessing the quality of impressions for crowns and bridges in the UK. The aim of the study was to assess the quality of impressions for conventional crown and bridgework received by commercial dental laboratories. Three dental laboratories were visited over a 3-month period. All impressions for conventional crowns and bridges that arrived on the days of the visits were examined prior to any laboratory processing. A total of 206 impression cases were examined and assessed against criteria laid out in a custom-designed assessment form. Defects were commonly found in the recording of prepared teeth. Overall, 44.2% of impression cases were unsatisfactory. NHS impressions were more than twice as likely to be unsatisfactory compared to private impressions. If the results of this survey are typical then the general quality of impressions for fixed crown and bridgework is unacceptable. This is particularly true for work completed under the NHS contract.

The average number of visits for the construction of metal-based and acrylic dentures by junior hospital staff was 10 visits. Our hypothesis was that supervision would optimise the number of visits and reduce any need for remakes. The first audit cycle was retrospective and included all patients treated by SHOs in the Prosthodontics Department. The standard of care was compared to the British Society for the Study of Prosthetic Dentistry. The re-audit showed that the time taken to completion was reduced by 2 visits for both denture types and the average length of time was reduced from 31 weeks to 22 weeks. These improvements were directly related to improved supervision by senior staff.

The aim of this study was to retrospectively analyse the clinical performance of hybrid bridges and their effect on periodontal health. All the bridges in this study were delivered by undergraduate dental students at the University Dental School and Hospital Cork. The recall protocol took the form of a questionnaire and a full clinical examination of the abutments, retainers and contra lateral control teeth. In all, 22 patients with 25 bridges were examined. The periodontal response was generally favourable and soft tissue alteration was minimal. The outcome of the performance hybrid bridges is not encouraging, as 32% (8) of the bridges failed and 68% (17) were in service with a mean duration of clinical service of 48 months.

An increasingly frequent dilemma in restorative dentistry is the question of whether to retain a badly damaged tooth and restore it, or to remove and possibly replace it. Given the ethical difficulties inherent in testing this question, it is unlikely that we will ever see a properly designed clinical trial that will provide an answer. One of the most strongly debated components of this question is whether endodontic treatment and restoration can compete with a dental implant-borne prosthesis in terms of longevity and success. In the current paper, the authors will attempt to: (i) answer this question based on our current understanding of the dental literature; and (ii) provide practitioners with guidelines that might be applied to their daily practices.

Objective: To assess the quality of dental casts used in crown and bridge construction., Design: Observational cross-sectional study of dental casts., Setting: Commercial dental laboratories and a university dental hospital laboratory in the UK., Materials and Methods: A sample (n = 150) of working and opposing casts used for crown and bridgework prescribed by general dental practices and a dental hospital were sampled from two commercial dental laboratories and an 'on-site' university dental hospital laboratory respectively. A simple '3 point' assessment scale of quality (good, fair and poor) was used to categorise the casts depending on the clarity of reproduction of soft and hard tissues., Results: The quality of opposing casts used for articulation purposes was significantly better (P<0.001) than that of the working casts. In addition it was found that for working casts the quality in the preparation area(s) was significantly better (p<0.001) than that in areas remote from preparation(s) in the same arch. In general, the quality of casts in the incisal or occlusal surfaces was better than the buccal and lingual surfaces., Conclusions: This study has demonstrated that variation exists in the quality of casts used in crown and bridgework, specifically those used in the construction of indirect restorations and also those used for articulation purposes. This study highlights the need for clinicians to exercise continued vigilance with crown and bridge impressions, and casts, particularly in areas away from the prepared teeth.

Today's dental reconstructive therapeutic concepts require restoration of high esthetic quality and excellent biocompatibility. Full ceramic reconstructions accomplish these requirements but only for anterior teeth and premolars. For all-ceramic bridges the mechanical strength was insufficient to withstand the posterior chewing forces. Frequently the interdental connectors cracked, and the only way to prevent these fractures was to overconture the connectors to a size of approx. 16 mm2. The high-tech ceramic zirconia is a potential alternative for three-to five-unit full ceramic bridges in the functionally loaded posterior segments. Experimental zirconia bridges which were fabricated using the DCM system (Direct Ceramic Machining System at the ETH Zurich, were tested in vitro. The frameworks were digitally enlarged by 20% and were easily milled from a presintered yet porous zirconia blank. After the milling process, the framework was densely sintered and shrank to its original size. Due to these positive in-vitro results a clinical investigation was started. 22 veneered zirconia bridges were luted; 19 molars and 25 premolars were prepared. The connectors, max. 7 mm2, of all these bridges, have been functionally loaded by antagonists. After a mean observation time of 385 days (307 days to 488 days), all 22 bridges did not show any cracks in the framework or in the veneering porcelain. The patients commented particularly on the low heat conduction rate of zirconia. The only endodontic problem which occurred could not be directly connected to the type of bridge framework. The reliability of zirconia bridges in this investigation was connected to the DCM-Process. No statement about other zirconia-systems can be made on the results of this study.

Objective: To evaluate the accuracy of working casts for crown and bridge restorations made from twin mix putty/wash silicone elastomeric impression materials using different types of stock tray., Design: A master cast was made from ivorine teeth in a mandibular model. Three teeth were prepared for full crown restorations to simulate a single unit and a three unit bridge. Impressions were taken using four different types of impression tray and two different viscosities of silicone putty, together with a wash. Full metal crowns were constructed and seated on duplicate master casts and measurements made of the marginal discrepancies., Setting: The work was carried out in a dental technology laboratory in a university department of restorative dentistry in 1995/1996., Results: Metal and rigid plastic impression trays showed the least discrepancy (about 50 microns), the latter slightly greater with the normal putty than the soft one. Impressions taken with flexible plastic trays produced considerable discrepancy with both putties, approximately 210 microns and 180 microns respectively., Conclusions: Metal and rigid plastic stock trays give greater accuracy in the putty/wash silicone twin mix impression technique compared with flexible plastic ones for crown and bridge work. Those using the latter should be aware of their shortcoming in this respect.

Objective: To determine the quality of impressions for crown and bridge work made in general dental practice., Design and Setting: All impressions for crown and bridge work which had been sent to four commercial dental laboratories in the UK were assessed by two examiners, each laboratory being visited on two occasions., Materials and Methods: 290 cases which had been received by the laboratories on the days of the visits were assessed for a number of factors related to quality. There was no selection or rejection--all impressions received were examined., Results: Flexible plastic trays were used for the majority of working impressions for crown and bridge work in general dental practice (72%), many had been re-used (> 13%), defects in the recording of the prepared teeth were common, and cross infection control was not routine., Conclusions: Quality standards for impressions for crown and bridge work in general dental practice in the UK are a cause for concern if the sample of cases seen in this study is typical.

It is generally accepted that one should minimize horizontal forces or horizontal components of more vertically directed forces when loading dental implants. This has its implications for the choice of the occlusion concept. In this article various occlusal concepts aimed at different types of fixed prostheses on dental implants are discussed. When possible canine guided articulation or group function must be strived for. It is stressed that detailed pre-implantological diagnostics and treatment planning are essential to achieve high treatment standards.

The authors report on the state of oral health, dental knowledge and behaviour and prosthodontic care in 304 people. Based on these results the prosthodontic care need in all more than 60 years old inhabitants of Stralsund/Land is estimated.

Over the past few years, preparation and insertion of a dental bridges have been considerably modified and rationalized due to new methods and techniques. The former requirements the shape of pontics hat to meet are no longer fully valid. The behavior of the various materials (metals, resins, ceramics) in the mouth and especially towards the gingiva has been tested sufficiently. Knowledge regarding the functional conditions (flushing of the gingiva underneath bridges, turgor, abutment mobility, pulsation) has considerably increased in the past few years. Therefore recommendations regarding the shaping of pontics can be formulated that meet the anatomic, physiologic, and hygienic conditions as well as the esthetic wishes of the patients.

The requirements for a cast partial denture with a serviceability of many years (6-8 years) are: finding-oriented therapy, exact preparation of the remaining teeth, periodontal-prophylactic shaping of the base and appropriate after-care. The different criteria are presented.

53 clinically prepared bridges were examined with regard to the resting position of the bridge body on the alveolar ridge, before they were finally cemented. It was to be tested whether the ideal requirements of punctate or linear pressure-less resting was met and if not, how big the portion of the base resting on the gingiva was as compared to the total base. All bridge bodies were resting on the alveolar ridge without exerting pressure but with a more or less broad base. In 42 out of the 66 examined cases, the bridge body was in a 50 to 100% contact with the mucosa.

Follow-ups in class C 1 patients who underwent prosthetical treatment seemed indicated since little was known about the chances of success. It was possible to examine 20 patients of this groups mainly with regard to objective functional efficiency of the dental replacement worn from 1 to 8 years. Furthermore, articulation occlusion, relationship of upper and lower jaws, and frequency of required repairs were checked. Purely gingivally borne prostheses as well as periodontally supported and gingivally borne dentures had the same rate of success. The mixed form, i.e. gingivally borne in the upper jaw and periodontally supported and gingivally borne in the lower jaw, seemed to be less favorable due to differing load tolerances.