The durability of parylene coatings on neodymium-iron-boron magnets.
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A parylene coating is frequently used to prevent corrosion of neodymium-iron-boron magnets when they are used intra-orally. This in vitro study was designed to test the durability of parylene coating in a simulated oral environment. Single and double parylene-coated magnets were subjected to grinding and crushing forces in an industrial ball mill. The results demonstrate that abrasion and wear was visible around the edges after 1 hour of testing, with a breach of the coating noted under high magnification scanning electron microscopy (SEM). The conclusion of the study is that parylene coating is unlikely to withstand intra-oral forces. The shape of the magnets, the manufacturing process involved in their production, and the thickness of the parylene coating are important factors to consider with respect to the durability of magnets used in the mouth. (+info)
The use of resin cements in restorative dentistry to overcome retention problems.
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The use of resin cements in combination with dentin bonding agents can result in superior attachment of prostheses to tooth structure. This paper describes four clinical cases in which dentin-bonded resin cements were used to overcome retention problems. In the first case, a detached fixed partial denture, which was in good condition when separated, was recemented to abutment teeth prepared with less-than-ideal angle of convergence. In the second case, a detached all-porcelain crown was recemented with a dentin-bonded resin cement after appropriate surface treatment. In the third case, a porcelain-fused-to-metal crown made for a molar tooth was cemented to a short clinical crown, avoiding crown-lengthening surgery. In the fourth case, a 3-unit fixed partial denture was recemented to abutments with less-than-ideal supporting features. Dentin-bonded resin cements can help to extend the life of detached prostheses until the patient is financially prepared for replacement or it can help to avoid crown-lengthening surgery. (+info)
Esthetic option for the implant-supported single-tooth restoration -- treatment sequence with a ceramic abutment.
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A single implant-supported restoration is one treatment alternative to consider for the replacement of a missing tooth. Technological advances in materials and machining have led to the development of a densely sintered aluminum oxide ceramic abutment, designed and machined using CAD/CAM technology. This manufacturing method improves management of the subgingival depth of the crown/abutment interface and enhances the esthetic qualities of the restoration. However, since this ceramic abutment has less mechanical resistance than metal abutments, its use should be confined to the restoration of incisors and premolars not subjected to excessive occlusal forces. (+info)
A multi-centre study of Osseotite implants supporting mandibular restorations: a 3-year report.
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This multi-centre study evaluated the performance of the Osseotite implant in the mandibular arch. Osseotite implants (n = 688) were placed in 172 patients; 43.5% were placed in the anterior mandible and 66.5% in the posterior mandible. Fifteen per cent of the implants were placed in soft bone, 56.9% in normal bone and 28.1% in dense bone. During placement, 49.9% of the implants were identified as having a tight fit, 48.6% a firm fit and 1.5% a loose fit. About one-third of the implants (32.4%) were short (10 mm in length or less). After 36 months, only 5 implants had been lost, for a cumulative survival rate of 99.3%. The 3-year results of this study indicate a high degree of predictability with placement of Osseotite implants in the mandibular arch. (+info)
Molar restorations supported by 2 implants: an alternative to wide implants.
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The single-tooth restoration has become one of the most widely used procedures in implant dentistry. Improvements to the abutment implant interface design, wider implant platforms and the increased use of cemented restorations have greatly enhanced this procedure. Nonetheless, limitations in the volume of underlying bone and heavy occlusal loads, with or without parafunctional habits, still contribute to occasional disappointments in restoration stability. The use of 2 implants to restore a molar has been shown to eliminate problems associated with bone volume and prosthetic stability. One of the most significant barriers to the widespread use of this concept has been the limitation of the size of implants and their associated prosthetic components. This paper presents the use of 2 implants to replace a single molar using implants and prosthetic components in the Astra Tech Dental Implant System. (+info)
Implant prosthodontic management of anterior partial edentulism: long-term follow-up of a prospective study.
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OBJECTIVE: This paper reports on the long-term outcome of patients with Kennedy Class IV partial edentulism treated in the Implant Prosthodontic Unit (IPU) at the University of Toronto, Toronto, Ontario. METHODS: The information for this paper was gathered from the charts of the first 30 consecutive, partially edentulous patients treated at the IPU. These patients all had Class IV edentulism and formed part of the original prospective clinical studies that were initiated in 1983. The patients' dental history suggested maladaptive experiences with traditional removable prostheses or a reluctance to have intact or quasi-intact teeth prepared as retainers for fixed prostheses. Fifteen men and 15 women treated with 94 Br nemark dental implants, supporting 34 prostheses, were followed until June 2000 (25 patients) or until they were lost to follow-up (5 patients). The multiple missing teeth occurred in 19 maxillae and 15 mandibles. RESULTS: The original prosthodontic treatments were intended to result in 33 fixed partial prostheses and 1 overdenture. At the time of this report, 25 patients with 86 implants supporting 31 fixed prostheses and 3 overdentures had been followed for an average of 12 years (range 7 16 years). The overall survival of implants was 92%. The difference between men (94%) and women (89%) was not statistically significant. CONCLUSIONS: This report is an interim update on an ongoing long-term prospective study. The results so far demonstrate a high survival rate for Br nemark implants supporting tissue-integrated prostheses for the management of anterior partial edentulism. (+info)
A 5-year prospective study of implant-supported single-tooth replacements.
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OBJECTIVE: Because osseointegration has been successful in the management of completely edentulous patients, it is tempting to extrapolate these results and infer the success of single-tooth replacement. Yet there are major clinical differences between edentulous and partially edentulous patients. This prospective study is a follow-up to one started at the University of Toronto in 1986. The purpose of this study was to continue longitudinal assessment of implant-supported single-tooth replacements. METHODS: The original study comprised 42 consecutively treated patients with a total of 49 implants. The patient group consisted of all University of Toronto patients treated with single Br nemark implants whose treatment had been completed more than 5 years previously (i.e., before 1994). No exclusion criteria applied. One implant was not osseointegrated at the time of stage 2 surgery, and 6 patients with reportedly successful osseointegrated implants were not available for recall. For the preparation of this report, 30 of the remaining 42 implants were assessed during recall examinations. Assessment of success was based on published criteria. In addition, soft-tissue appearance, implant immobility, occlusal contacts in centric occlusion and excursions, proximal contacts, tightness of crown and abutment screws, and patients' responses on satisfaction questionnaires were evaluated. RESULTS: The criteria defining success of treatment in implant prosthodontics were met by all 30 of the single-tooth implants, which had been in place for 5 or more years. Each implant was immobile, and each had a mean vertical bone reduction of less than 0.2 mm annually. CONCLUSION: Stable long-term results can be achieved with single Branemark implant-supported crowns. (+info)
Implant prosthodontic management of posterior partial edentulism: long-term follow-up of a prospective study.
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OBJECTIVE: This paper reports on the long-term outcome of implant-supported posterior-zone prostheses in the first 35 consecutive, partially edentulous patients treated in the Implant Prosthodontic Unit (IPU) at the University of Toronto, Toronto, Ontario. METHODS: A total of 106 Branemark dental implants were placed in 46 posterior edentulous spans in 35 patients for the management of multiple missing teeth; the patients were followed prospectively. Treatment planning principles involved a minimum of 2 or 3 implants at each edentulous site and scrupulous occlusal prosthodontic designs. RESULTS: The overall survival of posterior implants was 94%. No factors in the patients' history adversely affected implant survival. CONCLUSIONS: This clinical update suggests that the use of Branemark implants in the rehabilitation of patients who are partially edentulous in the posterior zone is highly effective and that survival of the implants is excellent. (+info)