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Biomedical subjects

Thomas D Taylor

Publications and source records attributed to Thomas D Taylor.

15 recordsLinked to original sources
PubMed2005

Static implant loading caused by as-cast metal and ceramic-veneered superstructures.

STATEMENT OF PROBLEM: The passive fit of superstructures for implant-supported restorations is affected by each step of the fabrication process. In this context the question arises whether ceramic veneering would increase static implant loading. PURPOSE: The purpose of this study was to quantify the strain development of various fixed partial dentures (FPDs) both in the as-cast condition and after ceramic veneering. MATERIAL AND METHODS: Four different types (n = 10) of 5-unit FPDs (cementable, screw retained/plastic cylinder, screw retained/gold cylinder, screw retained/cemented) representing commonly used types of FPDs were investigated before and after ceramic veneering. Three implants were placed in a model simulating a patient situation, and strain gauges were mounted mesially and distally adjacent to the implants. The strain development was recorded during cement setting (provisional cement) and screw fixation. The data were analyzed statistically using multivariate 2-sample tests (alpha=.1). RESULTS: All FPDs revealed measurable amounts of strain. Neither the type of retention nor the mode of fabrication for conventional screw-retained FPDs had a significant influence on strain development. Ceramic veneering caused an increase in strain development for the conventional fixed partial dentures tested. The lowest strains were found in FPDs cemented to gold cylinders on the model for the metal frames and the ceramic-veneered FPDs. CONCLUSION: Conventional procedures were unable to produce superstructures with absolute passive fit. Ceramic veneering appeared to increase strain development and, thus, inaccuracy of the fit. The technique of cementing superstructures to prefabricated components directly on the implants may compensate for dimensional errors caused by impression making and superstructure fabrication.

Cementation↗
PubMed2005

Strain situation after fixation of three-unit ceramic veneered implant superstructures.

The passive fit of superstructures used in implant prosthodontics is affected by several variables. The objective of this study was to quantify the strain development in various fixed partial dentures (FPDs), both in the condition as cast and after ceramic veneering. Five different types of three-unit FPDs (cementable/repositioning technique impression; cementable/pick-up technique impression; screw-retained/plastic cylinder; screw-retained/gold cylinder; screw-retained/bonded) with 10 samples each, representing commonly used FPD-types, were investigated before and after ceramic veneering. Two ITI implants were anchored in a measurement model simulating a real-life patient situation and strain gauges were mounted close to the implants. The strain development was recorded during cement setting and screw fixation. For statistical analysis, multivariate two-sample tests were performed with the level of significance set at P = 0.1. All FPDs revealed measurable amounts of strain. Neither the impression technique nor the fabrication modes for conventional screw-retained FPDs had a significant influence on strain development. Ceramic veneering caused an increase in strain development for the conventional bridge types. Furthermore, cementing appears to be able to compensate fabrication inaccuracies better than screw retention. The lowest strains were found in FPDs bonded to gold cylinders on the measurement model for metal frames and ceramic-veneered FPDs. Conventional procedures are unable to produce superstructures with an absolute passive fit. The technique of bonding superstructures to prefabricated components in the oral cavity seems to compensate for various shortcomings in superstructure fabrication.

Cementation↗
PubMed2005

Effect of implant angulation upon retention of overdenture attachments.

INTRODUCTION: Overdentures supported and retained by endosteal implants depend upon mechanical components to provide retention. Ball attachments are frequently described because of simplicity and low cost, but retentive capacity of these components may be altered by a lack of implant parallelism. PURPOSE: The aim of this in vitro study was to investigate the retention of gold and titanium overdenture attachments when placed on ball abutments positioned off-axis. METHODS AND MATERIALS: Four ball abutments were hand-tightened onto ITI dental implants and placed in an aluminum fixture that allowed positioning of the implants at 0 degrees, 10 degrees, 20 degrees, and 30 degrees from a vertical reference axis. Gold and titanium matrices were then coupled to the ball abutments at various angles and then subjected to pull tests at a rate of 2 mm/second; the peak loads of release (maximum dislodging forces) were recorded and subjected to statistical analyses. A balanced and randomized factorial experimental design testing procedure was implemented. RESULTS: Statistically significant differences in retention of gold matrices were noted when ball abutments were positioned at 20 degrees and 30 degrees , but not at 0 degrees and 10 degrees. Statistically significant differences were noted among the titanium matrices employed for the testing procedure, as well as for the 4 ball abutments tested. Angle was not a factor affecting retention for titanium matrices. CONCLUSIONS: (1) The gold matrices employed for the testing procedures exhibited consistent values in retention compared to titanium matrices, which exhibited large variability in retention. (2) Angle had an effect upon the retention of gold matrices, but not for titanium matrices.

Analysis of Variance↗
PubMed2004

Simplified complete dentures.

Complete denture fabrication can be an enjoyable and profitable facet of a dental practice. The key to success is a thorough diagnosis, understanding the patient's desires and expectations, and following a standardized sequence of treatment. This article describes a modified complete denture technique designed to minimize chair time but maintain sound principles of denture construction.

Dental Impression Technique↗
PubMed2004

A selective-pressure impression technique for the edentulous maxilla.

This article describes a selective-pressure impression technique for the edentulous maxilla that is intended to compensate for the polymerization shrinkage of heat-polymerized polymethyl methacrylate resin and provides improved palatal adaptation of the definitive denture base.

Dental Impression Materials↗
PubMed2004

Cement fixation and screw retention: parameters of passive fit. An in vitro study of three-unit implant-supported fixed partial dentures.

It is generally assumed that passively fitting superstructures are a prerequisite for long-lasting implant success. In the study presented, the strain development of three-unit implant fixed partial dentures (FPDs) was evaluated at the bone surrounding the implant and on the superstructure using a strain gauge technique. Six groups of three-unit FPDs representing the commonly used techniques of bridge fabrication were investigated with 10 samples each, in order to quantify the influence of impression technique, mode of fabrication and retention mechanism on superstructure fit. Two ITI implants (Straumann, Waldenburg, Switzerland) were anchored in a measurement model according to a real-life patient situation and strain gauges were fixed mesially and distally adjacent to the implants and on the bridge pontics. The developing strains were recorded during cement setting and screw fixation. For statistical analysis, multivariate two sample tests were performed setting the level of significance at P=0.1. None of the investigated bridges revealed a truly passive fit without strains occurring. About 50% of the measured strains were found to be due to impression taking and model fabrication, whereas the remaining 50% were related to laboratory inaccuracies. The two impression techniques used did not reveal any significant differences in terms of precision. Both modes of fixation--i.e. cement and screw retention--provoked equally high stress levels. In the fabrication of screw-retained FPDs, similar results were obtained from the use of burn-out plastic copings and the technique of casting wax moulds to premachined components. Bonding bridge frames onto gold cylinders directly on the implants significantly reduces strain development.

Aged↗
PubMed2002

Continuous pH monitoring in a perfused bioreactor system using an optical pH sensor.

Monitoring and regulating the pH of the solution in a bioprocess is one of the key steps in the success of bioreactor operation. An in-line optical pH sensor, based on the optical absorption properties of phenol red present in the medium, was developed and tested in this work for use in NASA space bioreactors based on a rotating wall-perfused vessel system supporting a baby hamster kidney (BHK-21) cell culture. The sensor was tested over three 30-day and one 124-day cell runs. The pH sensor initially was calibrated and then used during the entire cell culture interval. The pH reported by the sensor was compared to that measured by a fiber optically coupled Shimadzu spectrophotometer and a blood gas analyzer. The maximum standard error of prediction for all the four cell runs for development pH sensor against BGA was +/-0.06 pH unit and for the fiber optically coupled Shimadzu spectrophotometer against the blood gas analyzer was +/-0.05 pH unit. The pH sensor system performed well without need of recalibration for 124 days.

Animals↗
PubMed2002

Twenty years of progress in implant prosthodontics.

Prosthodontic focus on the restoration of osseointegrated dental implants has evolved dramatically in the last 20 years. Many of the original guiding principles for restoring implants have changed and/or disappeared altogether, and new ideas have taken their place. It is appropriate that this evolution be examined with a 2-fold focus. First, the art and science of prosthodontics as it relates to dental implants today is the result of very real and important lessons learned during the past 2 decades. Second, an appreciation of the history of implant prosthodontics as it relates to osseointegration gives insight into the future direction of research and clinical exploration aimed at continually improving the state of the art and, ultimately, the quality of care provided to patients. This article reviews what the authors consider the most important aspects of the evolution of osseointegrated implants. Pertinent literature was selected for citation, but the discussion does not represent a comprehensive review of the literature.

Cementation↗
PubMedDate not supplied

Removal torques of conical, tapered implant abutments: the effects of anodization and reduction of surface area.

PURPOSE: To examine the effects of anodization (surface coating) and reduction of internal Morse taper surface area on the reversal torque values of Straumann ITI dental implants and abutments. MATERIALS AND METHODS: Eighty ITI solid screw implants were mated with corresponding 5.5-mm solid abutments. The assemblies were divided into 4 test groups of 20 specimens. All abutments were torque tightened into the implant to 35 Ncm. Half of the abutments were anodized and half were in their as-machined state. Each of these 2 groups included half of the implants with the standard internal Morse taper configuration and half with the synOcta (Straumann USA, Waltham, MA) internal positioning interface (indexed). Torque removal testing was then performed on the assemblies. The 4 groups were compared statistically to examine the effect of the 2 variables (anodization and reduction in surface area). Scheffe's test for multiple comparisons was used to compare groups at an adjusted significance level of < or = .05. RESULTS: Torque removal of all specimens revealed that the indexed implant with the non-anodized abutment demonstrated superior removal torque. DISCUSSION: The indexed and standard implants with anodized abutments, and the standard implant with the non-anodized abutment had lower reversal torque values. CONCLUSION: The addition of the indexed internal surface to the ITI implant did not have deleterious effect on the resistance to loosening of standard solid abutments.

Coated Materials, Biocompatible↗
PubMedDate not supplied

Patient self-reported satisfaction with maxillary anterior dental implant treatment.

PURPOSE: Dental implants are accepted as a successful alternative to conventional fixed and removable prostheses for the treatment of partial or complete edentulism. However, there have been few studies of the success of implants from the patients' perspective. The purpose of this study was to assess patient overall satisfaction with the outcome of treatment with maxillary anterior implants. MATERIALS AND METHODS: A self-administered mailed questionnaire, which was developed for this project, and a data abstraction form, which was designed based on information available from the corresponding dental records of 123 eligible subjects, were utilized to survey implant patients. RESULTS: Seventy-eight of 123 eligible subjects responded to the mailed, self-administered, structured questionnaire. Twelve of the 24 questionnaire variables demonstrated statistically significant bivariate associations with the dependent variable "overall patient satisfaction." Five variables--implant position, definitive restoration shape, appearance, effect on speech, and chewing capacity--were strongly associated with overall satisfaction. No demographic or treatment-related, dental record-abstracted variable, of the 25 that were examined, was statistically significant. DISCUSSION: The practitioner who provides implant restorations should be aware of the multidimensional aspects of patient satisfaction with implant treatment. This study suggests that patient satisfaction with key elements influences the overall acceptance of maxillary anterior implant prostheses, which are esthetically critical. Communication between dentist and patient is important to achieve optimal results that will be satisfactory to both. Discussion of treatment limitations may also help patients to develop realistic expectations of the final result. CONCLUSIONS: In this limited investigation, patient satisfaction with implant position, restoration shape, overall appearance, effect on speech, and chewing capacity were critical for patient overall acceptance of the dental implant treatment.

Adolescent↗
PubMedDate not supplied

Prosthodontic complications in a prospective clinical trial of single-stage implants at 36 months.

PURPOSE: The present material reports on prosthodontic complications in a trial of 51 patients with prostheses supported by single-stage implants over a period of 36 months. MATERIALS AND METHODS: One hundred eighty-six single-stage implants were placed in 51 patients over a 3-year period in 2 carefully controlled prospective clinical trials. Nineteen of the patients (103 implants) were completely edentulous and restored with a maxillary complete denture and a mandibular fixed-detachable complete prosthesis. Single metal-ceramic crowns or fixed partial dentures were fabricated for the remaining 32 patients (83 implants). The fixed restorations were either screw-retained or cemented. RESULTS: All patients/implants were followed for a minimum of 3 years. Complications in the edentulous patients included fracture of denture teeth, fracture of the maxillary denture, and occlusal screw loosening. Occlusal screw loosening and loss of the resin composite access plug were the only complications observed in the patients treated with screw-retained restorations. No complications were found in the patients restored with cemented restorations on solid abutments. DISCUSSION: Problems with prostheses were very common in the completely edentulous patients (13 of 19 patients encountered complications), possibly a result of increased bite force or inadequate laboratory technique. Tooth fractures were seen more frequently in men than in women. Complications occurred in only 5 of the 32 partially edentulous patients. CONCLUSION: Complications were associated with laboratory-related procedures rather than the implant system itself.

Adult↗
PubMedDate not supplied

In vitro study on passive fit in implant-supported 5-unit fixed partial dentures.

PURPOSE: Fabrication and retention methods have an influence on the passivity of superstructure fit. The objective of the study was to quantify the strain development of various cemented and screw-retained fixed partial dentures (FPDs). MATERIALS AND METHODS: Forty samples of 4 different types of FPDs (10 of each type) were investigated. Each sample had 3 ITI implant abutments and 2 pontics. The 3 implants were anchored in a straight-line configuration in a measurement model simulating a real-life patient situation. Strain gauges were mounted close to the implants and on the pontics. The developing strains were recorded during cement setting and screw fixation. For statistical analysis, multivariate 2-sample tests were performed, with the level of significance set at P = .1. RESULTS: All FPDs investigated revealed a considerable amount of strain, with no significant difference between cement and screw retention. Furthermore, no significant difference was found between the conventional fabrication modes for screw-retained FPDs. The lowest strains were found in prostheses that were intraorally bonded onto gold cylinders. DISCUSSION: Because bonding of the superstructure in the oral cavity may compensate for impression and laboratory variables, restorations with the best possible passive fit can result from this retention technique. Before this technique can be recommended, the long-term stability of the adhesive layer should be investigated. CONCLUSIONS: As an absolute passive fit of superstructures is not possible using conventional clinical and laboratory procedures, and as clinical fit-evaluation methods often do not detect "hidden" inaccuracies, the more sensitive strain-gauge technique should be utilized for an objective accuracy test. Reference strain values from implant-supported prostheses that have served without complications could help define a "biologically acceptable fit.

Aged↗
PubMedDate not supplied

Early wound healing around endosseous implants: a review of the literature.

The knowledge base of information related to early wound healing around endosseous dental implants is rapidly changing and expanding. Unless one is directly involved with creating this pool of information or has an extraordinary interest in the literature of the field, it is difficult to keep up to date with the flow of information. This article is intended to provide the clinician with a state-of-the-art review of the current literature related to early wound healing and the creation of an osseointegrated interface between living and nonliving structures. While some literature dealing with basic laboratory studies including tissue culture is discussed, the primary focus of the article is the in vivo literature, ie, animal and human studies.

Animals↗