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PubMed2002

Evaluation of two vitallium blade-form implants retrieved after 13 to 21 years of function: a clinical report.

This article describes the clinical, radiographic, and histologic evaluation of 2 immediately loaded Vitallium blade-form implants retrieved from the posterior maxilla of 2 patients after 21 and 13 years of function. Neither implant demonstrated mobility or signs of pathosis, and both appeared to have integrated well with surrounding bone. The hydroxyapatite coating of the second implant, which was retrieved after 13 years of function, showed no dissolution. These observations suggest that immediately loaded dental implants have the potential to achieve and maintain osseointegration and that hydroxyapatite coatings can resist degradation over long-term service.

Aged↗
PubMed2002

Conversion of a complete denture to a provisional implant-supported, screw-retained fixed prosthesis for immediate loading of a completely edentulous arch.

This article describes the fabrication of a provisional implant-supported, screw-retained restoration for immediate loading of a completely edentulous arch. The technique can be applied to patients with partially edentulous arches as well. Until immediate loading of dental implants becomes a well-documented treatment modality, the described method should not be applied on a routine basis or without careful evaluation.

Aged↗
PubMed2002

Wave analysis of implant screw loosening using an air cylindrical cyclic loading device.

STATEMENT OF PROBLEM: The mechanics of implant screw loosening or fracture are well understood in the field of engineering. They have not been as widely explored in dentistry. PURPOSE: This study investigated the effects of simulated mastication on implant components and used wave analysis to document the basic mechanisms of screw loosening in a simulated oral environment. MATERIAL AND METHODS: A pneumatic cylindrical cyclic loading device was fabricated to simulate masticatory movement. Thirteen standard abutments were connected on external hexagonal implants with titanium abutment screws tightened to 20 Newton centimeters (Ncm), and single crowns were retained with gold screws tightened to 10 Ncm on each abutment, respectively. Ten single-implant crowns were loaded with the use of a cyclic loading device with 100 N of force at 30 degrees angles to the long-axis for 0.2 seconds of contact time with a frequency of 1 Hz. Three crowns were loaded vertically under the same conditions to serve as the control group. The effects of up to 1 million cyclic loads and various tightening torque forces (2, 4, 6, 8, 10, and 12 Ncm) on screw loosening were evaluated by wave analysis. A software program was written to record every wave mode and to stop the machine automatically if the amount of horizontal displacement of the crown was more than 0.5 mm, which was designated to represent perceptible loosened implant crown mobility clinically. The general wave patterns and characteristics of loosened and stable screws and the effect of various tightening torques were analyzed by comparing the differences in wave patterns. RESULTS: The wave mode was divided into 4 stages for loosened gold screws: initial displacement, initial vibration, elastic deformation, and recovery stage. However, the initial displacement and initial vibration stages were not discernible for stable gold screws. Of the 10 gold occlusal screws, 4 loosened before the 1 million cyclic loads in the 10 single crowns tested. There was no screw loosening in the control group. There was no effect of screw loosening on the elastic deformation stage. CONCLUSION: Within the limitations of this study, tightening torque had a significant effect on screw loosening. It would appear that more than 10 Ncm of tightening torque should be recommended for the gold screws in this external hexagon implant system.

Crowns↗
PubMed2002

The design and fabrication of fiber-reinforced implant prostheses.

The use of fiber composite technology in the creation of metal-free implant prostheses may solve many of the problems associated with a metal alloy substructure such as corrosion, toxicity, complexity of fabrication, high cost, and esthetic limitations. Laboratory and clinical research evaluating glass fiber-reinforced composite prostheses used to restore and replace teeth has shown that these materials exhibit excellent mechanical properties and can form a chemical bond to resin-based veneer materials such as those used in the fabrication of certain types of implant prostheses. Two different designs of fiber-reinforced composite implant prostheses have been developed and placed in human subjects. One design (screw-retained, retrievable prosthesis) is used with implant abutments that allow for screw-retained prostheses; the other design is used with abutments that retain prostheses with a luting material. Both designs are described in this article. The prostheses have functioned well in a small group of preliminary subjects, but clinical trials with larger subject populations are needed to more completely evaluate the potential of fiber-reinforced composites in implant prosthodontics.

Cementation↗
PubMed1995

The abutment transfer driver: a prosthodontic implant adjunct.

Rapid, accurate seating and cementation of permanent implant abutment heads that have been substantially altered for interocclusal clearance or parallelism requirements can be accomplished with individual, custom cast, insertion devices. The evolution and design of these devices (abutment transfer drivers) for fixed and removable prostheses are described.

Cementation↗
PubMed1996

Ultimate tensile strength of five interchangeable prosthetic retaining screws.

Implant prosthetic retaining screws have been reported to serve as built-in safety factors to protect against overload in the implant's "vertical stack," although loosening and fracture of retaining screws are often considered complications. Manufacturers have responded by introducing interchangeable prosthetic retaining screws, which can give the clinician the impression that interchanging screws will not have an adverse effect on the remainder of the implant complex and/or the integration of the implant itself. The objective of this investigation was to measure the ultimate tensile strength of four retaining screws from three manufacturers and two alloy types (gold and titanium) using the Nobelpharma gold prosthetic retaining screws as a standard for the comparisons. Five screws of each type were loaded in tension in an Instron Universal Testing Machine until fracture occurred. A Tukey-Kramer Test (significance level = .05) analysis of the data showed that all of the interchangeable prosthetic retaining screws were significantly different from the control screws in respect to ultimate tensile strength. The data suggest that interchanging prosthetic retaining screws will influence their built-in safety feature.

Dental Prosthesis Design↗
PubMed1996

Repair of implant overdenture clip attachments: technical note.

A technique is described for repositioning the clip attachments of implant overdentures during repair or relining procedures using a direct method. During maintenance procedures, clip attachments must be repositioned correctly to prevent torquing of the bar and abutments and precautions taken to avoid locking the prosthesis to the undercut areas of the bar. This technique ensures proper positioning of the attachments and decreases the amount of polymerization shrinkage.

Dental Clasps↗
PubMed1996

Load distribution on implants with a cantilevered substructure: an in vitro pilot study.

The forces distributed on six Nobelpharma implants were analyzed by strain gauges fixed to various implant combinations that were placed in a replica of a human edentulous mandible and connected to a cast gold alloy superstructure. The mandible was supported on its lower border and the superstructure loaded in different locations. Although force distribution was found to be asymmetrical, statistical analysis revealed no significant differences. Loads applied to one side of the superstructure were largely carried by the implants on that side, demonstrating torquing of the casting in the midline. Loads applied to the cantilever resulted in large extension forces in implants on the opposite side of the fulcrum. The magnitudes of the loads distributed on the screw varied as a result of the combinations, inter-implant spaces, and implant locations.

Dental Implantation, Endosseous↗
PubMed1996

The effect of soldering, electrowelding, and cast-to procedures on the accuracy of fit of cast implant bars.

The effect of three different connecting procedures on the accuracy of fit of cast implant bars over their supporting abutments was investigated. Thirty Hader implant bars were waxed on a master cast over two abutment analogs and cast in a type IV gold alloy. The bars were sectioned and divided into three groups of ten implant bars according to the connecting procedure that was to be followed. Group 1 bars were connected by soldering, Group 2 bars were connected by electrowelding, and Group 3 bars were connected with the cast-to procedure. The accuracy of fit of each group of bars was measured at the gold cylinder-abutment interface in microns using a stereomicroscope. The use of the cast-to procedure resulted in a more accurate fit as compared with the soldering and the electrowelding techniques.

Analysis of Variance↗
PubMed1996

The use of casting investments for soldering gold implant bars: a pilot study.

The use of gypsum- and phosphate-bonded casting investments for soldering gold implant bars was investigated. Eighteen gold implant bars were sectioned and divided into two groups of nine specimens each. One group of bars was invested with gypsum-bonded investment and the other group invested with phosphate-bonded investment. The accuracy of fit of each group was measured at the gold cylinder-abutment interface in microns using a stereomicroscope. The use of gypsum-bonded investment resulted in a more accurate fit as compared with phosphate-bonded investment.

Analysis of Variance↗
PubMed1996

Efficacy of threaded hydroxyapatite-coated implants in the anterior mandible supporting overdentures.

A data subset from an ongoing prospective multicenter clinical study of threaded hydroxyapatite-coated implants was evaluated to assess safety and efficacy of the implants when placed in the anterior mandible to support overdentures. Observations were recorded before surgery, at first-stage surgery, at second-stage surgery, at loading, and at quarterly postrestoration prophylactic exams and annual comprehensive patient visits. Implant failure criteria included mobility, radiographic evidence of bone loss greater than one-third the length of the implant or peri-implant radiolucency, fracture, exfoliation, removal for any reason, and patient reported pain upon palpation. Soft tissue indices were monitored as part of the study. Postrestoration implant performance was analyzed using life-table methodology. From the 2,062 implants restored in 720 patients in the parent study, a total of 660 implants in 174 patients were included in the anterior mandibular overdenture data subset. Twelve implants in 8 patients failed at or before second-stage surgery for a surgical success rate of 98.2 percent. Five implants failed during an observation period extending up to 72 months after completion of prosthodontic treatment. The Cutler-Ederer life table success rate after 5 years was 97.8 percent. No significant adverse events were reported during the observation period. Results of this investigation suggest that threaded hydroxyapatite-coated implants are effective when placed in anterior mandibular regions in support of overdentures.

Adult↗
PubMed1997

The abutment seating jig: a prosthodontic implant adjunct.

Rapid, accurate seating of screw-retained implant abutment heads, where timing is controlled by internal or external hex designs, can be readily accomplished with individual, custom-cast abutment head location devices. The devices are especially useful when the abutment head-implant body complex is to be permanently cemented. The use and design of abutment seating jigs for single tooth implants and completely implant or implant and natural tooth-supported prostheses are described.

Dental Abutments↗
PubMed1998

The replacement of a unilateral partial denture with an implant-supported fixed prosthesis: a clinical report.

Various treatment options have been advocated to restore short span edentulous spaces. For a single edentulous space, some clinicians have advocated the use of a unilateral removable partial denture because this design has certain advantages for the patient, and it does not require the preparation of adjacent teeth for the fabrication of a fixed partial denture. However, potentially serious consequences associated with this design type have been reported. The unilateral partial denture can become dislodged, swallowed, or aspirated, which can result in hospitalization, perforation of the gastrointestinal tract, possibly followed by surgical intervention to retrieve the prosthesis. Although an implant-supported single tooth replacement has been widely accepted and documented as a predictable treatment alternative, few clinical cases present have been presented in which potential severe iatrogenic damage can be so easily avoided. A treatment alternative that avoids potential hazards inherent in the design of a unilateral partial denture has been presented in this article.

Aged↗
PubMed1998

Implant and provisional crown placement: a one stage protocol.

Most endosseous implant systems are placed using a two-stage surgical procedure. The surgical stages are separated by a period of 4 to 6 months to allow osseointegration. At Stage-I surgery, the implant is fixed in bone and submerged under mucosa, while at Stage-II surgery, the implant is exposed and the transmucosal abutment is connected to the implant. The one-stage nonsubmerged surgical procedure with immediate transmucosal extension using traditional two-stage implant systems is being used to treat partial and complete edentulism. This is a case report of 10 patients treated with endosseous implants in the maxillary anterior region with immediate provisionalization using a one-stage surgical procedure. The investigators found that all patients experienced minimal discomfort from complications after the one-stage surgery and immediate placement of the provisional restoration. No signs of inflammation or mobility were observed during the first 6 months. The partially edentulous anterior maxilla can be restored to an esthetic form in a single clinic visit.

Adult↗
PubMed2001

The significance of passive framework fit in implant prosthodontics: current status.

The clinical and laboratory procedures employed for framework fabrication are inadequate to provide an absolute passive fit for implant-supported fixed superstructures. Although some prosthetic complications are attributed to the lack of passive fit, its effect on implant success is questionable. Nevertheless, the clinical results of increasing applications of advanced technology to improve framework fit seem promising. This article reviews the clinical significance of passive fit and the factors that affect the final fit of implant-supported frameworks.

Dental Prosthesis Design↗
PubMed2001

Computer analysis of titanium implants in atrophic arch and poor quality bone: a case report.

The oral implantologist usually uses a panoramic radiograph for the evaluation of bone tissue around implants. The development of computed tomography combined with computer software has allowed for the bone-to-implant interface to be illustrated in greater detail with cross-sectional and pseudo-color images. An implant patient has titanium fixtures in an atrophic arch and poor quality bone four years after implantation. The implants were loaded with fixed metal/resin restorations seven days after surgery. Integration of the implants and the anatomic structures near the implant sites are described with an imaging technique.

Alveolar Bone Loss↗
PubMed2002

Rehabilitation of the edentulous maxilla and mandible with fixed implant-supported restorations applying immediate functional loading: a treatment concept.

The rehabilitation of the complete edentulous arch with fixed implant-supported bridges can be a particular challenge for the practitioner. In the treatment concept presented, each jaw is provided with sufficient implants to realize fixed restorations under immediate (2-3 days after surgery) functional loading. After a healing time of 40 to 60 days, the metal/resin transitionals are exchanged for definitive metal/porcelain bridgework under gnathological aspects. Fixed implant-supported bridges correspond to the arches of natural teeth and can reveal better results in function, phonation, and aesthetics than removable prostheses.

Cementation↗