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At least 127 records · Page 7Linked to original sources
PubMed2006

A technique for locating implant abutment screws of posterior cement-retained metal-ceramic restorations with ceramic occlusal surfaces.

With the increased use of cement-retained implant-supported restorations for the replacement of missing teeth, clinicians may choose to use a definitive cement to lute the definitive restoration. A complication that may occur, especially for a single-tooth replacement, is loosening of the abutment screw. In those situations, it may be difficult to locate the abutment-screw access to remove the restoration. The purpose of this article is to describe a technique that may facilitate the clinician's ability to locate the abutment-screw access in the event of abutment-screw loosening, thus reducing the need for refabricating the restoration.

Cementation↗
PubMed2006

Physical and metallurgical considerations of failures of soldered bars in bar attachment systems for implant overdentures: a review of the literature.

The purpose of this literature review was to identify the etiological factors of failure of soldered bars in bar attachment systems for removable implant overdentures. A search of MEDLINE using the key words "bar attachment systems" was performed of English language peer-reviewed journals published between 1975 and 2005. Clinical studies of implant overdentures with prosthodontic maintenance complications of bar attachment systems were identified to establish the perceived etiology of failure. A further search of MEDLINE using the key words "solder joint" was also performed of the fixed prosthodontic literature to identify specific factors affecting the strength, fatigue resistance, and quality of gold solder joints used for bar attachment systems. The first search on bar attachment systems produced evidence of low failure rates of interabutment bars, but higher failure rates of bars where distal cantilever extensions were used. There were no explanations or descriptions of the nature of those failures in the clinical studies reviewed. The second search on fixed prosthodontic literature identified multiple factors that could potentially relate to the failed solder joints with bar attachments. Two potential sites of failure in bar attachments with distal cantilevers were identified, and a simple estimate of the tensile stresses at the solder joints was performed. The values found are comparable to the fatigue failure stresses reported in the searched literature.

Dental Prosthesis Retention↗
PubMed1995

Comparison of screw loosening, rotation, and deflection among three implant designs.

A common problem associated with single tooth implant restorations is abutment screw loosening. Manufacturers of implants have attempted to overcome this problem by incorporating antirotational design characteristics into their systems. Micromovement and torque levels required to loosen abutment screws for straight and angled antirotational screw-retained abutment/implant combinations from three different manufacturers were examined in this in vitro investigation. A custom-built machine was used and each sample was subjected to compressive horizontal reciprocal movements over a 25-degree incline for a simulated 1-month period. Data were generated that showed movements of the crown/abutment complex during force application. The amount of torque necessary to loosen the abutment screws before and after testing was also recorded and compared for each system. The results indicated no significant differences (p < 0.05) among all the straight and angled abutments for the variables studied.

Analysis of Variance↗
PubMed1995

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.

Aged↗
PubMed1995

Mechanical considerations for the implant tooth-supported fixed partial denture.

The implant tooth-supported fixed partial denture presents a biomechanical design problem, because the implant is rigidly fixed within the alveolus, and the tooth is surrounded by a periodontal ligament that allows movement. Nonrigid fixed partial denture designs are advocated by some dentists as a method of compensating for this differential movement. Rigid fixed partial denture designs, however, are advocated by many clinicians. Studies have failed to show the advantage of one design over the other. This study developed an in vitro method for testing such prosthesis designs and measured movement of a natural tooth abutment during simulated function. The movement of the natural tooth abutment was not found to change substantially with the fixed partial denture designs tested.

Alveolar Process↗
PubMed1995

Geometric comparison of five interchangeable implant prosthetic retaining screws.

Eight geometric parameters of five interchangeable prosthetic retaining screws (#1-3i Implant Innovation-gold, #2-Impla-Med-gold, #3-Nobelpharma-gold, #4-3i Implant Innovation-titanium, and #5-Implant Support Systems-titanium) were recorded with an Amray 1000-B scanning electron microscope at x20 to x200 magnification. Five screws of each type were measured and eight parameters were evaluated: (A) diameter of head, (B) screw length, (C) thread pitch, (D) major diameter, (E) neck diameter (F) length of neck, (G) crest width, and (H) root width. The Nobelpharma-gold prosthetic retaining screws served as controls. The results revealed significant differences between the control and test screws in all parameters except parameters C and G (ANOVA, p < 0.05) and Duncan's multiple range test (significance level 0.05). On the basis of these differences, it was concluded that interchanging prosthetic retaining screws can introduce unknown variables in treating patients.

Analysis of Variance↗
PubMed1997

Theoretical study of the effects of tooth and implant mobility differences on occlusal force transmission in tooth/implant-supported partial prostheses.

STATEMENT OF PROBLEM: Despite their mobility differences under occlusal loads, a natural tooth and an implant are often used together to support fixed prostheses. In some situations, tooth/implant-supported partial prostheses include cantilever extensions, especially in the posterior region where the bone is inadequate for placement of an additional implant. PURPOSE: In this study, engineering beam theory was used to study the effects of the mobility differences between the implant and the tooth on the force and moment distribution, due to occlusal loads in tooth/implant-supported prostheses. METHODS: The prosthesis was treated as a linear elastic beam and the supports were modeled as springs with (vertical) translational and rotational stiffness. The bending moments and forces on the supports were calculated as functions of the parameters that describe the geometry, position of the occlusal load, and stiffness ratios (namely, implant or tooth) of the springs. RESULTS: Bending moments on the supports were more sensitive to the relative rotational mobility between the supports and their individual values than to the relative translational mobility. The moment at the implant was minimized when the supports had similar mobilities. A preliminary design concept was introduced and eliminated the moment at the implant without significantly increasing the magnitude of the moment at the tooth. Cantilevering the prosthesis resulted in moderately increased bending moments and considerable tensile forces on the supports for a broad range of the parameters that describe the geometry and loading. CONCLUSIONS: From this simulation, it is suggested that cantilever extensions should be avoided or supported by a short implant, which will only restrain the vertical movement of the cantilever end.

Algorithms↗
PubMed1997

The precision of fit at the implant prosthodontic interface.

STATEMENT OF PROBLEM: Percussion, visual observation, and conventional periapical radiographs are the methods most frequently used clinically to evaluate the accuracy of implant component assemblies, whereas methods to measure the precision of fit are limited. PURPOSE: In this study the Periotest instrument was used to evaluate the stability of the interfaces between the implant and the abutment, along with the abutment and the gold cylinder under a series of assembly conditions. The hypothesis tested is that a more negative Periotest value (PTV) would indicate an accurate fit and a more positive value PTV would correlate with an inaccurate fit. MATERIAL AND METHODS: To investigate this hypothesis in vitro, two bovine ribs were used as patient simulation models. Each model contained three self-tapping Brånemark implants placed approximately 7 to 10 mm apart and arranged in a reasonable curvature. A series of component assembly conditions were created as accurate and inaccurate with thickness gauges of 25.4 microns, 50.8 microns, and 101.6 microns. RESULTS: The mean Periotest values and SDs for accurately assembled abutments and gold cylinders were -6.0 +/- 0.32 and -3.4 +/- 0.68, respectively. Periotest value data of the assembly conditions were statistically analyzed with multiple regression analysis. The misfit in the implant to abutment interface resulted in a more negative Periotest value trend (r = 0.54) with increases in gauge thickness. However, the same magnitudes of misfit at the abutment to gold cylinder interface produced a more positive Periotest value trend (r = 0.72). CONCLUSION: The PTV trends were consistent with increased stability at the abutment to implant interface from the increasing magnitude of misfit created with the thickness gauges. In contrast, the measurement trends observed for the abutment to gold cylinder interface were consistent with decreased stability with each increase in gauge thickness inserted at the interface.

Acceleration↗
PubMed1997

A comparative prospective clinical study of two single-tooth implants: a preliminary report of 102 implants.

STATEMENT OF PROBLEM: Treatment of tooth loss in the anterior maxilla can involve difficult functional, esthetic, and psychologic problems, especially in young patients with otherwise good dentition. PURPOSE: The purpose of this study was to provide a preliminary comparative evaluation of two implants (ITI and Astra) in single-tooth restorations. MATERIAL AND METHODS: This prospective study of 102 single-tooth replacements with 56 ITI and 46 Astra dental implants was performed in 82 patients at the Finnish Student Health Service Foundation. One Astra implant was lost before loading. The overall survival rate of the implants was 97.8% for Astra implants and 100% for the ITI system. After the initial healing period of at least 6 months, the remaining 101 implants (56 ITI, 45 Astra) were free of periimplant infection and revealed no detectable mobility. Radiographs did not reveal signs of periimplant radiolucencies. All 101 implants received single-tooth crowns. RESULTS: Periimplant parameters and acceptable implant function were examined and demonstrated satisfactory results with preestablished clinical parameters and radiographs at 1 year. During the observation time the mean marginal bone loss was 0.13 mm with Astra implants and 0.11 mm with ITI implants. Subjectively all patients were satisfied with their single-tooth restorations supported by either ITI or Astra dental implants. CONCLUSION: The favorable results of this short-term study support the application of the two implant systems for single-tooth restorations, especially in the anterior region of the maxilla.

Adolescent↗
PubMed1997

Tooth intrusion in implant-assisted prostheses.

STATEMENT OF PROBLEM: Numerous reports and surveys have been published on natural tooth abutment intrusion with implant-connected fixed partial dentures. The consensus of these publications was that the cause of intrusion was multifactorial, with causative factors such as disuse atrophy, debris impaction, impaired rebound memory, and mechanical binding. It was also believed that the process was irreversible. PURPOSE: In this article, the limitations with these theories are discussed, and two patient reports of tooth intrusion reversal are reviewed. A review of the current literature is discussed, as well as the current theory of tooth movement in response to dynamic mechanical stimulus, a brief discussion of current experimental procedures and results, and the current recommendations for reversal of intrusion.

Alveolar Process↗
PubMed1998

Rigidly splinted implants in the resorbed maxilla to retain a hinging overdenture: a series of clinical reports for up to 4 years.

STATEMENT OF PROBLEM: The results of the implant overdenture treatment in the maxilla remains inferior to those in the mandible. Different reasons have been alluded to, such as bone quality and quantity, number of implants, as well as the prosthesis design. PURPOSE: To investigate the latter, a new design for the rehabilitation of the resorbed maxillae was set up. MATERIAL AND METHODS: Thirteen patients were selected and provided with four endosseous maxillary implants, splinted with a rigid-cast bar. RESULTS: After a mean loading time of 3 years, six implants were lost; three at abutment and another three shortly after abutment connection, resulting in a cumulative success rate of 88.6% at year 4. A mean marginal bone loss of 0.3 mm was observed within the first year. After the first year, the marginal bone level, the attachment level, and the Periotest scores hardly changed. The main prosthetic complication was the frequent need to renew or to activate the attachments. A strong improvement in patient satisfaction was observed when compared with the old conventional denture. CONCLUSIONS: Within the limits of this study, the outcome confirmed that, on a medium-term base, implant-retained hinging overdentures on four implants were promising.

Adult↗
PubMed1998

Treatment of patients with extreme maxillary atrophy using sinus floor augmentation and implants: preliminary results.

Twenty consecutive patients with extreme maxillary atrophy underwent bilateral sinus floor augmentation, either with autogenous bone from the iliac crest or with a combination of autogenous bone and hydroxyapatite. One patient was treated using autogenous bone from the chin region. After a period of three to eight months, three to four implants were placed in each posterior maxilla. Only 10 out of 155 inserted implants were located in the anterior non-augmented maxilla. During the observation period of one to six years, four implants (one of them located in the anterior maxilla) had to be removed prior to prosthetic treatment. Another three implants were lost during the follow up period. This corresponds to a Kaplan-Meier survival probability of 95.4% after 70 months. No statistically significant difference in implant success was observed between women and men (P=0.16). All prosthetic suprastructures are still in function despite these implant losses. Mean peri-implant bone resorption was 1.34 mm with no statistically significant difference between implants placed more mesially and those placed more distally in the augmented area, though a trend could be observed (P=0.058) for a more pronounced bone resorption around implants placed in the premolar region. When a mean mesial and distal bone resorption of >2 mm was considered in the calculation of the success prognosis, the survival probability dropped to 74.7% after 70 months.

Adult↗
PubMed1998

Randomized prospective clinical trial of two implant systems for overdenture treatment: a comparison of the 2-year and 5-year results using the clinical implant performance scale.

In a prospective randomized clinical trial, edentulous patients were treated with dental implants and overdentures. The results of treatment with two IMZ implants connected by a Dolderbar, and a transmandibular implant (TMI) were compared. By using the clinical implant performance scale, the clinical and radiographic data were evaluated and compared after a two-year and five-year follow up. After the five-year follow up, significantly less problems and complications were recorded in the IMZ group than in the TMI group (Wilcoxon, P=0.03). When compared to the two-year follow up, there was, however, a gradual increase of scores on the clinical implant performance scale in the IMZ group, while in the TMI group only a slight increase was recorded.

Adult↗
PubMed2006

Retrospective evaluation of temporary cemented, tooth and implant supported fixed partial dentures.

INTRODUCTION: The aim of this study was to examine the clinical performance of this method, and determine which temporary cement was the most appropriate. METHODS: Dental fixtures (Tiolox implants GmbH, Germany) were implanted and crown and bridgework applied in a private practice between 1998 and 2003. Copings made of pure gold or titanium were permanently cemented onto the prepared teeth. The bridges were attached with either conventional temporary cements (Zinc oxide/ calcium hydroxide based) or acrylic/urethane cement (IMProv) both to the copings and to the implant abutments. Complications were evaluated by a retrospective review in January 2006. RESULTS: A total of 47 patients (response: 81%) with 65 fixed partial dentures could be evaluated. Removal and re-attaching without damage of the dentures was undertaken for the following reasons: for follow-up examinations (n = 31), colour corrections (n = 15), cleaning of the dentures (n = 12), treatment of peri-implantitis (n = 2), repair following ceramic fractures (n = 5), implant failure (n = 1), tooth extractions (n = 2), root canal treatments (n = 2), occlusal corrections (n = 2), or in the case of abutment loosening (n = 4). Accidental detachments with conventional temporary cements occurred more frequently and more rapidly than with IMProv (15% versus 88.7% survival rate after four years). CONCLUSIONS: This method for dental implant supported fixed partial dentures is successful and efficient.

Adult↗