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Steven E Eckert

Publications and source records attributed to Steven E Eckert.

At least 19 recordsLinked to original sources
PubMed2006

Cyclic loading of implant-supported prostheses: comparison of gaps at the prosthetic-abutment interface when cycled abutments are replaced with as-manufactured abutments.

STATEMENT OF PROBLEM: Implant-supported prostheses are mechanically connected to implants. When this connection is a screw joint, it is likely that the fit will be imperfect. Previous studies demonstrate that deformation can occur at the interface between the prosthesis and implant following cyclic loading. This deformation alters the fit of components. If implant connection components, abutments, were to be reoriented or replaced, it is likely that deformed surfaces would no longer approximate each other. Likewise, it is possible that the deformation may deleteriously alter the fit to replacement components. PURPOSE: This study evaluated the changes in prosthesis-implant abutment fit when gold cylinders that have been cyclically loaded are mated to as-manufactured abutments. MATERIAL AND METHODS: Fifteen implant-supported frameworks were fabricated using conventional casting techniques and were cyclically loaded under 3 different loading conditions: anterior region, unilaterally on posterior cantilever, and bilaterally on posterior cantilever. A cyclical load of 200 N was applied to each framework for 200,000 cycles. The abutments and frameworks were returned to the definitive casts for measurements. Linear measurements (microm) of the gap between the prosthetic cylinder and the implant-supported abutment at 4 predetermined reference points were made. The cycled abutments were replaced with as-manufactured abutments, and the gaps were measured at the same reference points. The Mann-Whitney rank-sum test was applied to the 2 sets of data to determine whether significant changes in fit were observed following component replacement (alpha = .05). RESULTS: Although minor changes in component fit were seen, the data failed to show that gaps at the prosthetic-abutment interface of cycled abutments were significantly different from those of as-manufactured abutments. CONCLUSIONS: Within the limitations of this study, differences in the fit between the implant-supported prosthesis and the abutments were not significantly different when abutments worn through loading were replaced with new as-manufactured abutments.

Dental Abutments↗
PubMed2006

Repair of a milled cantilevered implant overdenture bar: a clinical report.

This clinical report of a fractured cantilevered substructure bar describes an alternative treatment to the proposed refabrication of the substructure bar and overdenture prosthesis. This report outlines the clinical and laboratory procedures to repair the fractured bar, eliminating the time and expense of fabricating a new bar and prosthesis.

Aged↗
PubMed2005

Osseointegrated craniofacial implants in the rehabilitation of orbital defects: an update of a retrospective experience in the United States.

STATEMENT OF PROBLEM: Since their introduction, craniofacial implants have been used in prosthetic rehabilitation of facial defects. The literature, however, indicates marked variability in outcomes using implants for the retention of orbital prostheses. PURPOSE: A multicenter report updating the experience in the United States with the use of craniofacial implants for prosthetic rehabilitation of orbital defects is presented. MATERIAL AND METHODS: Surveys were sent to clinicians at 25 centers where maxillofacial prosthetic treatment is provided to obtain retrospective data regarding patients who completed implant-retained orbital prosthetic rehabilitation. Data on implant placement location, radiation treatment history, and use of hyperbaric oxygen therapy were collected and assessed in relationship to implant survival over time. The Kaplan-Meier life table and Wilcoxon analyses (alpha = .05) were used to assess the significance of the findings. RESULTS: Ten centers responded, providing data suitable for statistical analysis on 153 implants placed to retain 44 orbital prostheses and followed for a mean period of 52.6 months. Forty-one implant integration failures occurred during this follow-up period, resulting in an overall integration survival rate of 73.2%. No significant relationship was found between radiation treatment history, hyperbaric oxygen therapy history, or implant placement location and implant survival. Individual responses revealed large variability between reporting centers in treatment outcomes. CONCLUSION: Craniofacial implants may offer marked benefits in the prosthetic rehabilitation of orbital defects when compared to conventional adhesive retention designs. However, questions remain regarding long-term predictability and the impact specific factors may have on treatment outcomes. Insufficient data is currently available from which to draw statistically meaningful conclusions. The establishment of a national database designed to acquire adequate data to assess treatment outcomes is recommended.

Adolescent↗
PubMed2005

Influence of platelet-rich plasma added to xenogeneic bone grafts in periimplant defects: a vital fluorescence study in dogs.

BACKGROUND: The use of platelet-rich plasma (PRP) has been suggested in order to increase the rate of bone deposition when sites are augmented prior to or in conjunction with dental implant placement. PURPOSE: The goal of this study was to investigate whether the addition of PRP to xenogeneic bone grafts would increase the rate of bone formation in dogs. MATERIALS AND METHODS: Ninety endosseous dental implants were inserted in the mandibles of nine hound dogs. Subsequently, mesial and distal three-wall periimplant defects were surgically created. Defects were randomly assigned to three groups: demineralized freeze-dried bone graft plus platelet-rich plasma (DFDBG plus PRP), demineralized freeze-dried bone graft alone (DFDBG), and no treatment. Postsurgically each dog received a series of three fluorescent labels for estimation of bone cell activity at baseline and during different stages of healing, with particular attention to the bone formation rate per tissue volume (BFR/TV). Animals were sacrificed at 1 month, 2 months, and 3 months, and specimens were subjected to analysis by fluorescence microscopy. Treatment effects were evaluated with analysis of variance models. RESULTS: Overall, the average BFR/TV differed by treatment although this difference approached only minimal statistical significance (p = .057). The largest difference occurred between periimplant defects treated with DFDBG only and defects that were not treated (mean percentage BFR/TV, 0.0720% vs 0.0994%). There was no evidence of an overall treatment effect (p = .27) for the mineral apposition rate (MAR) values. The data also suggest a consistent variability in the bone formation parameters among the three groups at different healing points. CONCLUSION: In this animal model the addition of PRP to xenogeneic bone grafts did not demonstrate evidence of faster bone formation during healing. However, limitations of the histologic technique possibly played a negative role in the assessment of bone formation parameters.

Alveolar Ridge Augmentation↗
PubMed2005

Regenerative potential of platelet-rich plasma added to xenogenic bone grafts in peri-implant defects: a histomorphometric analysis in dogs.

BACKGROUND: The purpose of this investigation was to evaluate the regenerative influence of platelet-rich plasma (PRP) added to xenogenic bone grafts on bone histomorphometric parameters in a dog model. METHODS: Ninety endosseous dental implants were inserted in the mandibles of nine hound dogs. Mesial and distal 3-wall peri-implant defects were surgically created adjacent to the implants. Defects were randomly assigned to three groups: demineralized freeze dried bone with platelet-rich plasma (DFDB + PRP), DFDB alone, and no treatment (NT). Animals were sacrificed at 1, 2, and 3 months according to a previously established randomization schedule, and specimens were subjected to histomorphometric analysis. Percentages of bone area inside the implant threads (BiIT), bone-to-implant contact (BIC), and bone area outside implant threads (BoIT) were recorded. Treatment effects were evaluated using analysis of variance models. RESULTS: The effect of the three treatments on the outcome measures did not differ significantly by healing time (P > 0.05 for the healing time by treatment interaction). However, the average (standard deviation) percentage of BIC and BoIT was significantly different between the treatment groups. In particular, the average percentage of BIC differed between peri-implant defects treated with DFDB + PRP (33.8% [11.0]) and those treated with DFDB alone (28.5% [10.8]; P = 0.042), as well as those in the NT group (27.9% [11.0]; P = 0.024). Furthermore, the average percentage of BoIT differed significantly between defects treated with DFDB + PRP compared to defects in the NT group (51.6% [12.2] versus 43.3% [10.3]; P = 0.005). There was borderline evidence to suggest that the average percentage of BiIT and BIC was significantly different depending on the length of the healing time (P = 0.054 and P = 0.085, respectively). CONCLUSION: This study found that the addition of PRP to xenogenic bone grafts demonstrated a low regenerative potential in this animal model.

Alveolar Bone Loss↗
PubMed2004

Implant-retained maxillary overdentures.

Overdentures supported by osseointegrated implants overcome many of the complications observed with overdentures supported by natural teeth. Dental implants are free of biologic consequences associated with natural teeth, such as dental caries and periodontal disease. Bone undercuts adjacent to implants do not mimic those found adjacent to natural tooth roots. Implants are used to provide predictable retention, support, and stability for overdenture prostheses. When lip or facial support is required, the overdenture is the treatment of choice. Likewise the overdenture may improve phonetic deficiencies associated with alveolar bone loss.

Dental Implants↗
PubMed2004

Nasal stent fabrication involved in nasal reconstruction: Clinical report of two patient treatments.

Total or near-total rhinectomy during tumor ablative surgery creates a large postsurgical defect. Surgical or prosthetic reconstruction may be considered. Surgical reconstruction of such a defect depends on support of the reconstructive tissues to prevent collapse. Without support, the esthetic results and airway patency are compromised. The purpose of this clinical report is to present the use of a nasal stent to support soft and hard tissues for the reconstruction of near-total rhinectomy in 2 patients.

Adult↗
PubMed2003

Cyclic loading of implant-supported prostheses: changes in component fit over time.

STATEMENT OF PROBLEM: Dental literature suggests that an implant-supported prosthesis must exhibit a passive fit to prevent implant fracture, component breakage, and screw loosening. From a practical standpoint, passive fit is impossible to achieve; instead, minimal misfit may be the clinical goal. To date no specific range of misfit (below which problems are minimal and above which catastrophic failure occurs) has been established. PURPOSE: The purpose of this study was to determine whether the fit of an implant-supported prosthesis changes through cyclic loading and to quantify the amount of change between the gold cylinder and implant abutment over time. MATERIAL AND METHODS: Fifteen implant-supported frameworks were fabricated with conventional casting techniques and were cyclically loaded under 3 different loading conditions. Five frameworks were loaded on the anterior portion of the framework, 5 were loaded on the left unilateral posterior cantilever, and 5 were loaded bilaterally on the posterior cantilevers with a servohydraulic testing machine. A cyclical load of 200 N was applied to each framework for up to 200,000 cycles. Linear measurements were made in micrometers of the gap between the prosthetic cylinder and the implant-supported abutment at 4 predetermined reference points. These measurements were recorded before the application of the cyclical load, after 50,000 cycles, and after 200,000 cycles. A repeated measures of variance model was fit separately to the data for each load location (P<.05). RESULTS: There was a significant (P=.024) decrease in gap dimensions at individual reference points and a significant (P=.031) decrease in the average gap when the load was applied to the anterior portion of the framework. When the load was applied unilaterally or bilaterally on the posterior cantilever, significant gap closure was not observed (P=.33 and P=.35, respectively). CONCLUSION: Within the limitations of this study, the fit between the prosthetic superstructure and the implant-supported abutment changed when simulated functional loading of the anterior portion of the prosthesis was performed. Simulated functional loading applied unilaterally or bilaterally to the posterior cantilever portion of the prosthesis did not result in changes in the measured gap sizes.

Analysis of Variance↗
PubMed2003

The implant-supported overdenture as an alternative to the complete mandibular denture.

BACKGROUND: Approximately one-third of Americans older than 65 years of age are fully edentulous, requiring replacement of missing teeth. While the conventional denture may meet the needs of many patients, others require more retention, stability, function and esthetics, especially in the mandible. The implant-supported prosthesis is an alternative to the conventional removable denture. METHODS: This article describes the strengths of the implant-supported mandibular overdenture. The authors also outline the risks of this approach. They performed a review of recent literature to summarize the reported success rate of implants used to support a mandibular overdenture. RESULTS: The literature review indicates that implants placed in the anterior mandible (anterior to the foramen) have a success rate better than 95 percent. Patients have reported a high degree of satisfaction with the implant-supported overdenture. CONCLUSIONS: The literature indicates that implant-supported overdentures in the mandible provide predictable results with improved stability, retention, function and patient satisfaction compared with conventional dentures. Implants placed in the anterior mandible have a success rate equal to or greater than 95 percent. CLINICAL IMPLICATIONS: When planning treatment for patients with edentulous mandibles, clinicians should consider the implant-supported prosthesis.

Aged↗
PubMed2002

Survey of implant experience by prosthodontists in the United States.

PURPOSE: The paper presents results of a survey of members of the American College of Prosthodontists (ACP) conducted to determine experiences and practices with dental implants. MATERIALS AND METHODS: Preliminary survey questions regarding the prosthetic and surgical use of dental implants were developed. The master list of questions was distributed to communities of interest to establish the most pertinent items of interest. The final questionnaire was distributed to all members of the ACP living or practicing in the United States and members engaged in the U.S. armed services. Responses were compiled and analyzed to determine correlation of responses using the chi-squared test for count data (level of significance alpha = 0.05). Fisher's exact test was applied to all significant responses. RESULTS: Surveys were distributed to 1815 ACP members. A total of 554 (31%) surveys were completed. On the basis of age distribution of survey respondents, it was determined that the respondents were representative of the ACP membership. The majority of the respondents (82%; CI, 79% to 85%) treat patients with implant-supported prostheses, while 12% (CI, 10% to 15%) surgically place implants. Of those not placing implants, 24% reported a desire to place implants, while 43% of all respondents expressed a desire for an ACP-sponsored course in implant placement. Increased age of the prosthodontist correlated negatively with a desire to place implants (p < 0.0001). Dissatisfaction with implant placement by others correlates with willingness to surgically place implants (p < 0.0001). CONCLUSIONS: Most prosthodontists (82%) use implant-supported prostheses in their practices, but most of the implants are placed by non-prosthodontists. There is general satisfaction with implant placement regardless of the specialty of the practitioner placing the implants. Younger prosthodontists expressed a greater desire to surgically place implants but were not statistically more likely to do so.

Adult↗
PubMedDate not supplied

The influence of mandibular dentition on implant failures in bone-grafted edentulous maxillae.

PURPOSE: To evaluate the influence of mandibular dentition on the performance of maxillary implants prior to definitive prosthesis attachment in maxillae that have been reconstructed with autogenous bone grafts. MATERIALS AND METHODS: A retrospective review of 90 consecutive patients, 31 men and 59 women, with a mean age of 57.4 years, was conducted. All patients underwent treatment planning to receive endosseous implants in the edentulous maxilla in conjunction with autogenous bone grafting. During the time from implant and/or bone graft placement until placement of the definitive restorations in the maxillae, the mandibular dentitions were recorded and categorized into 6 groups based upon the presence and distribution of teeth. RESULTS: Of 643 implants placed, 118 (18.4%) were lost between implant placement and definitive prosthesis placement. The type of mandibular dentition was significantly associated with implant failure during this time interval (P < .001). In particular, the patients with implants opposing unilateral occlusal support showed the highest rate of implant failure (43.8%, or 28 of 64 implants). Implants that opposed a mandibular implant-supported fixed prosthesis demonstrated an implant failure rate of 14.3% (10 of 70), and in patients with a removable mandibular denture, the implant failure rate was 6.2% (4 of 65 implants failed). The overall mean patient follow-up was 64.2 months. At 60 months, the cumulative implant failure rate based on the Kaplan-Meier method was 20.2%. DISCUSSION: Unfavorable concentration of forces on the maxilla may contribute to increased risk of implant failure. CONCLUSION: Effort should be made to create a favorable occlusion in the mandible, with attention being paid to broad distribution of occlusal contacts.

Adult↗
PubMedDate not supplied

Retrospective cohort study of the clinical performance of 1-stage dental implants.

PURPOSE: To evaluate long-term clinical performance of 1-stage dental implant prostheses at a single clinic, emphasizing clinical and demographic characteristics that affect implant survival. MATERIALS AND METHODS: Dental records of all 308 patients (674 implants) treated with 1-stage implants at Mayo Clinic from October 1993 through May 2000 were reviewed from implant placement to last visit. Exposure and outcome variables affecting performance were collected separately to control bias in the data collection process. Additional confounding factors (age and sex) were adjusted with the stratified Cox proportional hazards model. Implant survival was determined by means of a Kaplan-Meier survival estimate. The log-rank test was used to determine the role of clinical and demographic variables in implant survival. The relative risk associated with the possible effect of clinical and demographic variables on implant survival was estimated with the Cox proportional hazards model. RESULTS: The implant survival rate (n = 654 implants) was 97% (mean +/- SD follow-up, 21.0 +/- 18.8 months; range, 1 to 78 months). Performance bias was limited because nearly all patients were treated by 1 prosthodontist. Two implants failed after loading (6 and 9 months). The incidence of complications was less than 4%. Among the implant failures, use of heterogeneous bone graft was associated with 4.8 times more failures than was use of autogenous bone graft (P = .04). After augmentation, delaying implant placement for 5 to 6 months resulted in 8.6 times more failures than the rate after earlier placement (P < .001). DISCUSSION: Retrospective review of the clinical performance of a 1-stage dental implant system yielded a 97% survival rate, with no failures noted after 13 months. Prosthetic complications were low, especially for fixed implant prostheses. CONCLUSION: Clinical performance of 1-stage dental implant prostheses between 1993 and 2000 demonstrated a high level of predictability.

Adolescent↗
PubMedDate not supplied

Methods for comparing the results of different studies.

The reader of oral and maxillofacial implant literature is challenged to be cognizant of the quality of clinical research data. The large variety of possible study designs utilized by clinical researchers requires the reader to have a fundamental awareness of the advantages, disadvantages, and limitations of commonly utilized study designs. This article aims to provide the reader with information to make an informed decision regarding the quality of a clinical research paper, so that he or she can judge whether the information presented in any given manuscript was obtained in a manner that truly minimizes bias, in the form of systematic or random errors, and whether it warrants serious consideration for clinical decision making. Special consideration is given to scientific literature pertaining to the use of oral and maxillofacial implants. In addition, the reader is presented with a method for placing any single manuscript within a "hierarchy of evidence" enabling an "estimate of confidence" in a particular therapy. By utilizing such methods to appraise the quality of research data, clinicians and patients will be better informed when making treatment-planning decisions.

Bias↗
PubMedDate not supplied

Cross-sectional study of the factors that influence radiographic magnification of implant diameter and length.

PURPOSE: To study the factors that influence radiographic magnification of implant diameter and length. MATERIALS AND METHODS: The dental records and panoramic radiographs of 80 patients with 210 dental implants treated with implant-supported prostheses at Bundang Jesaeng Hospital in South Korea from January 2000 through February 2003 were reviewed. The panoramic radiographs were developed under standardized conditions. The patient's gender and the anatomic locations of implants were identified from the dental records. To prevent bias, a blinded investigator measured implant diameter and length on a panoramic radiograph. To evaluate intra-examiner variability, the intraclass correlation coefficient (R(I)) was calculated. The Mann-Whitney rank-sum test and the Kruskal-Wallis test were used to determine the statistical significance of the difference between actual length and radiographic length. RESULTS: The intraclass correlation coefficients (R(I)) were 0.83 for diameter and 0.87 for length. There was no statistically significant difference in length in regard to gender (P = .08). Magnification of diameter did differ on the basis of gender (P = .03; 25% magnification in radiographs of women; 20% in men). No difference in diameter was found in regard to anatomic location (P = .51), however, while evidence of difference in length in regard to anatomic location was found (P = .01). DISCUSSION: Radiographic magnification of implant dimensions in diameter and length can have different influencing factors. CONCLUSIONS: This study found that radiographic magnification of implant diameter was influenced by gender, whereas radiographic magnification of implant length was influenced by anatomic location. Each anatomic location had a different amount of radiographic magnification for implant length.

Adolescent↗
PubMedDate not supplied

Finite element analysis of effect of prosthesis height, angle of force application, and implant offset on supporting bone.

PURPOSE: This finite element analysis was conducted to determine the magnitude of stress in the supporting bone when implants were arranged in either a straight-line or an offset configuration. In addition, the effects of axial and nonaxial loading and changes in prosthesis height were assessed. MATERIALS AND METHODS: An 8-node hexahedral solid-element 3-dimensional finite element analysis model of the mandible was created using PATRAN software. Three titanium endosseous implants were placed in the model 7 mm apart. The center implant was placed on the line from the centers of the terminal implants (no offset), 1.5 mm lateral to this line (1.5-mm offset), or 3.0 mm lateral to this line (3.0-mm offset). Forces of 200 N were applied to a point corresponding to the center of the middle implant when the implants were in a straight-line configuration. Forces were applied in a straight vertical direction or in 15-degree increments to the vertical to a maximum of 60 degrees. Simulated type IV gold prostheses were made to simulate heights of 6 and 12 mm. RESULTS: The least stress in the supporting bone was found with vertical loading of the no-offset implants with the 6-mm prosthesis (3.12 MPa) followed by the same alignment with the 12-mm prosthesis (3.86 MPa). Changing the angle of force application by 15 degrees resulted in increased stress to the underlying bone, and the creation of an offset did not fully compensate for this increased stress. DISCUSSION: In contrast to previous studies, this study examined 3 elements not previously studied together in a single finite element analysis, using the maximum offset defined by normal anatomic contours of mandibular premolar and molar teeth, thereby describing the relative importance of clinically relevant methods for stress reduction. CONCLUSIONS: Vertical loading of an implant-supported prosthesis produced the lowest stress to the supporting bone. Changes in the angle of force application resulted in greater stress to supporting bone. Reduction in prosthesis height or use of an offset implant location for the middle implant reduced stress, but the reduction did not compensate for the increase found with off-axis loading.

Alveolar Process↗
PubMedDate not supplied

Value in dentistry.

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Decision Making↗