Alternative uses of a visible light-polymerized material.

Three different procedures that involve the use of Triad gel are described. This light-polymerized resin material is versatile and easy to use in the dental clinic and laboratory. The procedures described include the transfer of ridge topography for ovate pontic sites, implant lab analog fixation, and solid/soft tissue cast fabrication.

Alternative uses of a visible light-polymerized material.

Three different procedures that involve the use of Triad gel are described. This light-polymerized resin material is versatile and easy to use in the dental clinic and laboratory. The procedures described include the transfer of ridge topography for ovate pontic sites, implant lab analog fixation, and solid/soft tissue cast fabrication.

Comparison of interface relationships between implant components for laser-welded titanium frameworks and standard cast frameworks.

With the introduction of new techniques for the fabrication of frameworks for implant-supported prostheses comes the need to understand how the components used compare to those used for conventional cast frameworks. The relationship of measured machining tolerances between conventional implant components and those components used for stereo laser-welded implant frameworks was determined using a standardized protocol. Statistically significant differences in the horizontal interface relationship were found between paired implant components, which had a mean range from 23.1 to 51.7 microns. From a laboratory and clinical perspective, machining tolerances of implant components represent a variable associated with their manufacturing, which can ultimately affect the fit of a completed prosthesis.

Problems associated with the atrophic mandible.

A range of treatment options has been presented regarding the use of dental implants to rehabilitate patients who otherwise have compromised function using conventional tissue-borne prostheses. This patient population offers significant challenges to both the surgeon and the prosthodontist. Generally speaking, IODs retained on two or more endosteal osseointegrated implants; transosteal, subperiosteal, ramus frame implant-supported and implant-retained prostheses, and a totally implant-supported design offer options to treat the severely atrophic mandible. When bone support or volume is so lacking that augmentation procedures are required, bone grafting can be considered as a treatment option. The state-of-the-art of implant treatment for the atrophic mandible offers to the dental professional and patient a variety of options. Thus far, it is too early to make specific recommendations as to which treatment offers the best option for each patient. It is fair to say that the ISP remains the gold standard against which other treatments can be compared.

Ten-year results for Brånemark implants immediately loaded with fixed prostheses at implant placement.

This investigation was initiated to develop a method to provide patients with a fixed provisional prosthesis placed at the time of implant placement. Sixty-three standard 3.75-mm Nobel Biocare implants of varying lengths were placed into mandibular sites in 10 patients and followed for up to 10 years. Twenty-eight implants were immediately loaded at implant placement, providing support for fixed provisional prostheses, while 35 adjacent implants were allowed to heal submerged and stress-free. Following a 3-month healing period, the submerged implants were exposed and definitive reconstruction was accomplished. All 10 prostheses supported by 28 implants placed into immediate function at the time of implant placement were successful during the 3-month healing period. Of these 28 implants placed into immediate function, 4 ultimately failed. Of the 35 submerged implants, all are osseointegrated and in function to date. Life-table analysis demonstrates an overall 10-year survival rate of 93.4% for all implants. The 10-year life-table analysis of survival is 84.7% for immediately loaded implants and 100% for submerged implants. Statistical analysis of the submerged versus immediately loaded implants demonstrates failure rates for immediately loaded implants to be significantly higher (P = .022 by the log rank test). These data demonstrate that although mandibular implants can be successfully placed into immediate function in the short term to support fixed provisional prostheses, long-term prognosis is guarded for those implants placed into immediate function distal to the incisor region.

Tolerance measurements of various implant components.

Machining tolerance, an intrinsic characteristic that exists between machined implant components, identifies the amount of horizontal shift possible between paired components. Machining tolerances between implant components (abutment, gold, cylinder, impression coping, and brass abutment replicas) were measured with a coordinate measuring machine. The measured tolerances ranged from 22 to 100 microns. Machining tolerances between implant components should be included in future studies of accuracy, because it is an inherent characteristic of the component itself.

A multicenter longitudinal clinical trial of a new system for restorations.

STATEMENT OF PROBLEM: A new method for fabrication of crowns and fixed partial dentures (Procera system) that involves electric discharge machining and copy milling has been developed. The metal used is unalloyed titanium, which can be processed as a single coping or multiple units joined to a pontic by laser welding. PURPOSE: The single-unit coping or the fixed partial denture (FPD) substructure is then veneered with a low-fusing porcelain. MATERIAL AND METHODS: In this article the clinical application of this technique was evaluated by six major universities in the United States. A total of 114 patients participated in this study, which involved 126 restorations (55 maxillary and 71 mandibular prostheses). There were 179 abutments, of which 73 were crowns and 53 were three-unit FPDs. Surface and color, anatomic form, and margin integrity were assessed 1 month after cementation and at 1 year with the California Dental Association (CDA) quality assessment evaluation system. RESULTS: No statistically significant differences in CDA scores between the 1 month evaluations and the 1 year assessments were found for surface and color (p = 0.68), anatomic form (p > 0.99), or margin integrity (p = 0.57). By use of the lowest ranking in the three categories as the overall quality of the restoration, only 3.3% (two crowns and two FPDs) were not acceptable at the 1-month visit and 4.5% (two crowns and three FPDs) were not acceptable at the 1-year evaluation. At-the 1-month visit 96.6% (114) of the restorations were considered to be satisfactory, whereas 95.5% (107 restorations) were evaluated similarly at the 1-year evaluation. CONCLUSIONS: The Procera system demonstrated, by use of the CDA criteria, its capability to produce quality prostheses that were rated satisfactory more than 95% of the time after insertion and maintained this high rating at least for 1 year.

Measuring fit at the implant prosthodontic interface.

Four centers in the United States and Sweden have been working for 2 years to develop systems and methods for measuring fit at the prosthodontic interface. Two systems are based on stylus contact techniques, one system uses a laser as its reader source, and one system is photogrammetric. All the systems are capable of providing data as three-dimensional x, y, and z axes coordinate values that can be transformed into linear and angular data that characterize the bearing surfaces of abutments or abutment replicas and their mating components in the prosthesis framework. The centroid, a single point computed from the collected data, was the measurement unit, derived for these bearing surfaces, that was used to compare the systems. All four methods can most likely detect misfits that are relevant in the clinical setting; however, only one system can be used intraorally. When any measurement system is assessed, the data should always be examined for repeatability to establish the reliability of the system. This investigation made comparisons among the measurement methods used at the four centers. It was apparent from this study that comparisons of data from measurement systems should be rounded to the nearest 10 microns. The SDs determined in the comparisons were larger than 5 microns and therefore misfits should be calculated in terms smaller than 10 microns. This final point is important to the clinician who relies on research reports about precision of fit when selecting treatment approaches in caring for the implant prosthodontic needs of their patients.

Stereo laser-welded titanium implant frameworks: clinical and laboratory procedures with a summary of 1-year clinical trials.

A new technology for implant framework fabrication (Procera) has been introduced to North America after initial clinical trials in Sweden. This technique is unique because it eliminates the conventional approach to framework fabrication with the lost wax casting technique. Clinical and laboratory procedures associated with the Procera technique are described in this article, as are the most recent developments in this rapidly emerging technology. A report of 1-year results of the first 10 patients treated with the Procera technique at the University of Washington is described. Treatment outcome has been favorable, with no clinical evidence of prosthodonic or soft-tissue complications noted. All 50 of the implants placed in the 10 patients remain integrated after 1 year of service. The Procera technology offers an alternative to current conventional framework fabrication techniques. Continued follow-up of this patient series is pursued to explore the treatment outcome for a longer interval of time.

Attachments used for implant-supported facial prostheses: a survey of United States, Canadian, and Swedish centers.

A survey was conducted of one Swedish, three Canadian, and 24 United States centers that provide implant-supported facial prosthetic treatment. All centers responded to the survey. A total of 357 patients began treatment. Of those, 338 completed treatment: 165 in Sweden, 131 in the United States, and 42 in Canada. The incidence of facial sites treated with implant-supported prostheses indicated that the auricular (72%) region was the most common site, followed by the orbital (20%), nasal (6%), and combination (2%). Clips were the predominant mechanism used to retain auricular prostheses. Orbital prostheses were fabricated with a wider variety and combination of attachments. Nasal and combination prostheses were too few to elicit any specific trends of attachment use. A variety of manufacturers' attachments were used for clip, magnet, and miscellaneous attachments to retain implant-supported facial prostheses. Results of this survey indicate a need for further investigation regarding the most efficacious attachment method to serve patients treated with implant-supported facial prostheses.

Three-dimensional analysis of the casting accuracy of one-piece, osseointegrated implant-retained prostheses.

The three-dimensional distortions of implant frameworks of two designs, reflecting the early "Toronto" U-shaped design and a current L-shaped design, were measured. A conventional commercial laboratory one-piece casting method, using a silver-palladium alloy, was used. Distortion was defined by five displacement variables for the centroids of each of five gold cylinders incorporated in each casting: three orthogonal translational displacements (dx, dy, and dz) and two rotational displacements (d theta x and d theta y). A computerized coordinate measuring machine was used. Overall translational displacements measured were -17.4 +/- 15 microns for dx, 6.1 +/- 7.1 microns for dy, and -0.1 +/- 1.7 microns for dz. The overall global translational displacement, dR, was 20.2 +/- 14.5 microns. Overall rotational displacements were -0.098 +/- 0.109 degrees for d theta x and -0.020 +/- 0.097 degrees for d theta y, giving an average absolute angular change, d theta R, of 0.158 +/- 0.077 degrees. No significant differences were found between U- and L-shaped castings, except for dy values for cylinders 2, 3, and 4, and d theta x values for cylinder 1. Cylinder location within the arch was associated with a specific direction and magnitude of translational and rotational displacement. Even small rotational displacements may manifest large gap appearances with the one-screw test because of the "moment arm" effect. However, other rotational displacements may be hidden, depending on the direction of tilt and the moment arm length.

Accuracy of the acrylic resin pattern for the implant-retained prosthesis.

An in vitro study was conducted to determine the accuracy of fit of the acrylic resin pattern for the implant-supported prosthesis to the implant abutments. A master model containing five Nobelpharma titanium implants was fabricated using Ivocap acrylic resin. Using this model, five standardized acrylic resin patterns were fabricated from the three test dental acrylic resins. The fabricated patterns remained on the master model for 24 hours before removal and subsequent measurement. To compute the accuracy of each pattern, three special measuring points were firmly attached to each gold cylinder prior to pattern fabrication and the x, y, and z coordinates of these measuring points were determined. Measurements were made prior to pattern fabrication, with the cylinders on their respective abutments and after pattern fabrication, when the pattern had been removed from the master model. The results of this study showed that there was a significant difference in accuracy between the test acrylic resins and that none of these materials was completely accurate.

Immediate fixed interim prostheses supported by two-stage threaded implants: methodology and results.

Restoring patients with implant-supported fixed-detachable bridges according to the protocol established by Brånemark necessitates a period of several months when complete dentures must be worn to allow for a stress-free healing period of the implants. For many patients, especially when they still have some natural teeth remaining, this is unacceptable. An approach was developed that overcomes these limitations, offering an alternative to the transitional removable approach. Five or six Nobelpharma fixtures were placed between and two additional fixtures were placed distolingual to the foramina. Abutments were connected at implant insertion to these two fixtures and to one fixture in the symphyseal region. The remaining fixtures were allowed to heal in the conventional manner. A previously constructed mandibular denture was converted to a fixed bridge supported by these three implants. This method was successfully applied in seven patients who were reconstructed with mandibular fixed-detachable bridges without ever wearing a removable prosthesis. The overall, long-term implant therapy was not adversely affected by this technique.