Clinical factors of importance to successful implant therapy. Preface.
Explore the source record for details and available documents.
Clinical Trials as Topic↗
Biomedical subjects
H F Morris
Publications and source records attributed to H F Morris.
The need for well-controlled clinical studies.
Explore the source record for details and available documents.
Controlled Clinical Trials as Topic↗
Assessment of implant mobility at second-stage surgery with the Periotest: DICRG Interim Report No. 3. Dental Implant Clinical Research Group.
Many of the presently used methods of evaluating osseointegration at implant uncovering are highly subjective. The Periotest is claimed to offer a more objective means to assess osseointegration by means of microcomputer-controlled percussion. Investigators involved in a long-term clinical study of dental implants being conducted by the Dental Implant Clinical Research Group used the Periotest to evaluate the mobility associated with all study implants at second-stage surgery and correlate the Periotest values with various bone densities. The Periotest values for 1,838 root form implants ranged from -8 to +25. Implants that appeared to be osseointegrated at uncovering recorded a mean Periotest value of -3.37 +/- 3.25, while nonosseointegrated implants had a mean Periotest value of +13.87 +/- 14.27. Mean Periotest values were -3.82 +/- 3.04 for quality 1 bone, -3.70 +/- 3.06 for quality 2 bone, -3.31 +/- 3.18 for quality 3 bone, and -1.29 +/- 3.57 for quality 4 bone. The Periotest has the potential of being a valuable instrument for assessing the status of osseointegration at second-stage surgery.
Alveolar Process↗
The influence of implant type, material, coating, diameter, and length on periotest values at second-stage surgery: DICRG interim report no. 4. Dental Implant Clinical Research Group.
Many of the presently used methods of evaluating osseointegration at second-stage surgery are highly subjective. The Periotest is claimed to offer a more objective means to assess osseointegration by means of microcomputer-controlled percussion. In 1991 the Dental Implant Clinical Research Group initiated a long-term clinical study in cooperation with the Department of Veterans Affairs to investigate the influence of implant design, application, and site of placement on clinical performance and crestal bone height. As part of this investigation, the Periotest values for 1,565 root form implants were determined at second-stage surgery and correlated with type, material, coating, diameter, and length. Hydroxyapatite-coated implants and increased implant diameter and length produced Periotest values that indicated a greater extent of stability as compared with noncoated implants with shorter diameters and lengths. Hydroxyapatite-coated cylinder-type implants yielded the most favorable Periotest readings. Not only does the Periotest have the potential of being a valuable instrument for assessing implant mobility at second-stage surgery, but it also appears to have the capability of determining slight differences in the implant-bone complex.
Dental Alloys↗
The effect of smoking on implant survival at second-stage surgery: DICRG Interim Report No. 5. Dental Implant CLinical Research Group.
Smoking has been reported to have a deleterious effect on the oral cavity. Research has associated smoking with oral cancer, periodontal disease, leukoplakia, stomatitis nicotina, and impaired gingival bleeding. In 1991 the Dental Implant Clinical Research Group initiated a prospective, randomized clinical study in cooperation with the Department of Veterans Affairs to investigate the influence of implant design, application, and site of placement on long-term clinical performance and crestal bone height. Over 70 dental and medical history variables and exclusion factors were analyzed to determine relationships, if any, with implant failure at the time of second-stage surgery. The variables were analyzed separately for individual implants, cases (prostheses), and patients. The cases ranged from one to five implants each, and more than one case from a single patient could be included in the investigation. At this interim analysis, 2,066 implants have been placed representing 433 cases in 310 patients. With regard to implant failure rates, possible exclusion variable (9) and medical history variables (39) were not found to be statistically significant. For the dental history variables (23), only the question related to smoking was statistically significant on an implant, case, and patient basis (P < 0.007). Results of this interim analysis suggest that smoking is detrimental to implant success.
Chi-Square Distribution↗
Patient demographics and implant survival at uncovering: Dental Implant Clinical Research Group Interim Report No. 6.
Implant prognoses for healthy elderly patients have been found to be comparable with those reported for younger patients. In 1991, the Dental Implant Clinical Research Group initiated a prospective, randomized clinical study in cooperation with the Department of Veterans Affairs to investigate the influence of implant design, application, and site of placement on long-term clinical performance and crestal bone height. As a result of the large sample size and wide range of patient ages, the study provided an opportunity to determine if age correlates with implant survival. Interim analysis of 2,132 root form implants at uncovering on an implant, case, and patient basis suggests that implant survival does not appear to be influenced by age in the largely white, male sample.
Adult↗
Second-stage failures related to bone quality in patients receiving endosseous dental implants: DICRG Interim Report No. 7. Dental Implant Clinical Research Group.
The quality of bone plays an important role in the long-term clinical success of dental implant treatment. An interim evaluation of the relationship between bone quality and the incidence of failure at second-stage surgery is presented. The data include 2,131 root form implants placed by the Dental Implant Clinical Research Group over the past three years. Trends to date suggest differences in the rates of osseointegration among the various bone qualities. Quality 1 bone experienced the greatest failure rate, whereas quality 2 and quality 3 bone had the lowest failure rates.
Alveolar Bone Loss↗
Fracture surface characterization of clinically failed all-ceramic crowns.
The goal of this study was to establish a protocol for the retrieval and fractographic analysis of failed restorations, and to compare the fracture surface features of clinically failed ceramic restorations and with those of controlled laboratory test specimens fabricated from the same materials. Ten fractured Dicor crowns and 12 fractured Cerestore crows were retrieved and analyzed. Optical microscopy of the failed crowns revealed that the critical segments of nine of the 10 (90%) Dicor crowns and nine of the 12 (75%) Cerestore crowns were acceptable for fractographic analysis. Twelve disks of each material were fabricated as controls and fractured by bi-axial flexure for analysis of the similarities and/or differences between the fractographic features of fractured clinical crowns and the disks. Each of the 10 Dicor crowns was observed to fail along the internal surface. For 78% of the Cerestore crowns, failure initiation occurred at the porcelain/core interface or inside the core material. Critical flaw sizes of the failed Dicor crowns ranged from 127 to 272 microns. Failure stresses of the Dicor crowns, estimated by fractographic techniques and fracture mechanics relationships, ranged from 65 to 94 MPa. Estimated failure stresses for two of the Cerestore crowns which had failure initiation sites in the porcelain layer were 15 and 68 MPa. It is concluded that the fracture initiation sites of dental ceramics are controlled primarily by the location and size of the critical flaw, and not by specimen thickness.
Aluminum Oxide↗
Comparison of the performance on prosthodontic criteria of several alternative alloys used for fixed crown and partial denture restorations: Department of Veterans Affairs Cooperative Studies project 147.
In a 10-year, multicenter, double-blind clinical trial, comparisons of the clinical behavior of crown and fixed partial denture restorations were made between a gold alloy and four less costly alternative alloys. The endpoints of interest were (1) the development of unacceptable ratings on any of 11 individual prosthodontic criteria and an overall rating, (2) the removal of the restoration, and (3) an event combining unacceptable overall rating and restoration removal. Each of 630 patients had two restorations completed, one from gold-palladium alloy and the other from one of four alternative alloys. The patients were enrolled during a period of 3 1/2 years, with some patients followed up as long as 10 years after restoration. Analysis of the endpoints showed that one of the alternative alloys was significantly poorer than the other materials for certain criteria.
Adult↗
Department of Veterans Affairs Cooperative Studies Project number 147: level of examiner reliability over seven years.
In 1980 the Veterans Administration Cooperative Studies Program No. 147 initiated a multicenter, multidisciplinary clinical study to evaluate the use of alternative alloys for porcelain-fused-to-metal restorations. An investigation of interexaminer agreement was conducted after seven years utilizing three measures of reliability: percentage of exact agreement using a five-point scale, percentage of agreement using a dichotomous (satisfactory-unsatisfactory) scale, and [kappa], a statistic which is intended to measure agreement beyond what would be expected to occur by chance. Exact agreement on the five-point scale ranged from 77 to 99 percent. Percent agreement on the dichotomous scale was above 99 percent for all of the criteria. Kappa ranged from 0.56 to 0.91, indicating moderate to near perfect agreement among examiners. Reliability of the study evaluations reinforced the validity and significance of the findings.
Clinical Trials as Topic↗
Department of Veterans Affairs Cooperative Studies Project No. 242. Quantitative and qualitative evaluation of the marginal fit of cast ceramic, porcelain-shoulder, and cast metal full crown margins. Participants of CSP No. 147/242.
The primary objective of Veterans Administration Cooperative Studies Program No. 242 was to evaluate, in vitro and in vivo, the suitability of new dental materials and techniques used in making crowns and fixed partial dentures. Because inaccurate margins can lead to changes in the periodontal tissues and/or to recurrent caries, it is important to assess the accuracy of margins resulting from the use of new, improved materials or techniques. This segment of the project compared the marginal fit associated with the use of Dicor Crowns, Cerestore crowns, and porcelain-shoulder metal ceramic full coverage restorations using both quantitative and qualitative methods. Statistically significant differences were found among these materials following analysis of the quantitative data. The ranking in mean marginal opening from smallest to largest was: metal margins (27.5 microns), Dicor crowns (63.5 microns), porcelain shoulder restorations (66 microns), and Cerestore crowns (75 microns). The rank order based on the qualitative evaluation method was the same.
Aluminum Oxide↗
The influence of implant design, application, and site on clinical performance and crestal bone: a multicenter, multidisciplinary clinical study. Dental Implant Clinical Research Group (Planning Committee).
This investigation is designed to provide scientific data that is directly relevant to the placement of dental implants. The study is concerned with the influence of implant design, application, and location on long-term clinical performance and crestal bone response over 5 years of function. It involves approximately 700 patients at 30 Veterans Administration Medical Centers from various geographic regions. Patients are being entered into the study over an 18-month period and monitored (post-loading) over 5 years. The participating centers were randomly assigned to one of two separate, independent study groups. Complications and adverse responses associated with the placement and use of the implants will be evaluated and all failures thoroughly documented. The experimental design and sample size are based on the primary hypothesis that an implant-supported prosthesis will be successful/functional over a 5-year period in at least 90 percent of the cases treated. Secondary hypotheses to be tested are (1) the success rate among implant designs are the same over a 5-year period; (2) the success rate among implant applications are the same over a 5-year period; (3) the success rate of individual implants are the same with regard to jaw location over a 5-year period; (4) the loss of crestal bone at the individual implant sites are the same among the implant designs over a 5-year period; and (5) the complications and adverse responses experienced with the different implant designs are the same over a 5-year period. The experimental design of this multicenter, multidisciplinary, randomized investigation is a cooperative effort of the Department of Veterans Affairs and several United States dental schools.
Alveolar Bone Loss↗
An evaluation of the Periotest system. Part II: Reliability and repeatability of instruments. Dental Implant Clinical Research Group (Planning Committee).
Investigators involved in a clinical study on dental implants being conducted by the Dental Implant Clinical Research Group participated in a two-part in vitro evaluation of the Periotest system. The first part involved each of 35 investigators taking three readings for each of 16 models designed to simulate an implant in place in the oral cavity and to cover most of the effective measuring range of the instrument. The second part, with which this article is concerned, was conducted by three study investigators to determine the level of agreement in readings for six different Periotest instruments. Readings were taken according to the manufacturer's instructions until two coincident readings were obtained. The readings were compared to evaluate inter- and intrainstrument reliability. Instrument repeatability was evaluated by examining the number of attempts required to obtain the two coincident readings. The Periotest system generally demonstrated a high degree of repeatability and reliability, with higher variability associated with specific model samples.
Dental Implants↗
Evaluation of the interprobe electronic periodontal probe.
The Interprobe is designed to provide measurements of pocket depths and attachment loss. Investigators involved in a clinical study on dental implants being conducted by the Dental Implant Clinical Research Group participated in an in vitro evaluation of the variability of repeated measurements made with the Interprobe. Measurements were made on holes drilled to predetermined depths in metal blocks. Three readings by investigators for each of nine test holes were in agreement 75.2 percent of the time. At least two of three readings were in agreement in 98.1 percent of the attempts. Either two of three or three of three readings were within 0.5 mm of the actual depth of the holes over 99 percent of the time. No correlation was noted for accuracy of measurements with hole depth or present clinical duties of the investigators. Although slight initial improvement in measurement accuracy was observed, it was not statistically significant in time over the three measurement sequence.
Analysis of Variance↗
Casting alloys: the materials and "The Clinical Effects".
Explore the source record for details and available documents.
Cobalt↗
An evaluation of the Periotest system. Part I: Examiner reliability and repeatability of readings. Dental Implant Clinical Group (Planning Committee).
The clinical success of endosseous dental implants is related to the extent of osseointegration. Many of the presently used methods of evaluating osseointegration are highly subjective. The Periotest is claimed to offer a more objective means to assess osseointegration and supporting bone stability of implants by means of microcomputer-controlled percussion. Investigators involved in a clinical study on dental implants being conducted by the Dental Implant Clinical Research Group participated in a two-part in vitro evaluation of the Periotest system. The first part, with which this article is concerned, involved each of 35 investigators taking three readings for each of 16 models designed to simulate an implant in place in the oral cavity and to cover most of the effective measuring range of the instrument. The Periotest system generally demonstrated a high degree of reliability and repeatability, with higher variability associated with specific model samples. Further evaluation of the Periotest as a research instrument will be conducted within the clinical environment of the Dental Implant Clinical Research Group study.
Dental Implants↗
Doses and residues of acephate baits used to eradicate undesirable honey bees: a hazard assessment.
Explore the source record for details and available documents.
Animals↗
Veterans Administration Cooperative Studies Project No. 147. A precementation comparison of metal ceramic restorations made with a gold-containing alloy or alternative alloys.
This analysis compared the precementation quality of metal ceramic restorations made from different alternative alloys after they had been returned from the central dental research laboratory. Ticon, Micro-Bond N/P2, Ceramalloy II, and W-1 materials were evaluated by use of 11 well-defined criteria and for overall performance. The evaluations were compared with those of Olympia, a gold-containing alloy, which served as the control. The results showed statistically significant differences between Olympia alloy and some of the alternative alloys for six of the 11 criteria. These differences, however, were not sufficient to be considered clinically significant (clinically detectable). In the comparison of their overall performances no statistically significant differences were found.
Corrosion↗