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The influence of individual bone patterns on peri-implant bone loss: Preliminary report from a 3-year randomized clinical and histologic trial in patients treated with implants restored with matching-diameter abutments or the platform-switching concept
No full textPurpose: This study sought to determine whether there was a correlation between bone resorption and individual bone patterns in patients treated with implants restored conventionally or using the platform-switching concept. Materials and Methods: Ten patients (24 implants) were randomly assigned to receive implants with different platform diameters (3.8, 4.3, 4.8, or 5.5 mm), all of which were restored with standard 3.8-mm-diameter abutments. Biopsy specimens were obtained prior to implant placement, and histologic and immunohistochemical analyses were performed. Standardized radiographs were made at each site after implant placement and at 36 months after prosthetic loading and bone levels were determined. Results: One patient dropped out, resulting in a total of 9 patients and 22 implants. Mean bone resorption was 1.358 mm for non-platformswitched implants; mean resorption was 0.832, 0.486, and 0.375 mm for implant platforms of 4.3, 4.8, and 5.5 mm, respectively. After standardization of peri-implant bone remodeling values, a borderline direct correlation between peri-implant bone changes and levels of biglycans was found. At the same time, a borderline indirect correlation between bone changes and levels of tumor necrosis factor-a was found. Conclusions: Within the limit of this study, which was conducted in a small patient sample over a short observation period, an individual resorption trend was detected and paralleled by immunohistochemical findings. Individual local bone structure and quality seemed to be correlated to peri-implant bone resorption. Correlations between biglycan and tumor necrosis factor-a and bone resorption should be confirmed by a larger patient sample. © 2011 by Quintessence Publishing Co Inc
Matrix-metalloproteinases and bone loss at implants restored according to the platform switching concept: a randomized controlled trial on the influence of different mismatching
No full textBackground and Aim: Matrix metalloproteinases (MMPs) are important mediators of tissue degradation. This randomized controlled clinical trial aimed to evaluate bone responses to implants restored with different implant/abutment mismatching and to assess the correlation between peri-implant bone remodeling and peri-implant sulcular fluid levels of matrix metalloproteinases.
Materials and Methods: A total of 80 implants (Global®, Sweden & Martina, Italy) were divided according to platform diameter in 4 groups: 3.8 (ControlGroup), 4.3 (TestGroup1), 4.8 (TestGroup2) and 5.5mm (TestGroup3), 20 implants each group. They were randomly placed in the posterior maxilla of 30 patients. Two months later, all implants were connected to a 3.8mm diameter abutment and definitive prosthetic rehabilitation was performed. Radiographic bone levels were measured independently by two calibrated examiners immediately after implant placement (baseline) and every six months after loading using an image analysis software. Patients were followed up for 30 months after prosthetic loading. At the last follow-up visit, in addition to a standard clinical and radiographic exam, peri-implant sulcular fluid samples were obtained. Activated matrix metalloproteinase-8 (aMMP-8) was quantified by ELISA (Dentognostics, Jena, Germany).
Results: Five patients were lost to follow up after 33 months. A total of seventy implants remained in the study and all of them were clinically osseointegrated. Radiographic analysis showed a mean bone loss of 0.97mm (SD = 0.42mm) for TestGroup1, 0.77mm (SD = 0.43mm) for TestGroup2, 0.64mm (SD = 0.32mm) for TestGroup3. These values were statistically significant lower (p < 0.005) than the ControlGroup mean values (1.48mm, SD = 0.42mm). There was an inverse correlation between the amount of bone loss and the degree of mismatching (-0.63, p < 0.001). For MMP-8, the respective mean values were: 4.139ng (SD: 3.25ng) for the ControlGroup; TestGroup1: 2.894ng (SD: 3.17ng); TestGroup2: 3.534ng (SD: 3.64ng), TestGroup3: 3.278ng (SD: 3.25) and 2.80ng (SD: 4.45ng) for samples from adjacent control teeth (probing depth ≤ 3 mm). No significant differences between the groups and no significant correlation between MMP-8 levels and the extent of past bone loss at individual sites was observed.
Conclusion This study confirmed an inverse correlation between that extent of implant/abutment mismatching and the amount of peri-implant bone loss. Longitudinal monitoring of peri-implant sulcular levels of MMP-8 may be warranted to determine their suitability as predictors for future peri-implant attachment loss
Microscopical and chemical surface characterization of the gingival portion and connection of an internal hexagon abutment before and after different technical stages of preparation
No full textAim: This study was aimed to assess contaminants on the abutment surface close to the implantabutment interface and the connection, after common technical protocols.
Materials and methods: A total of 40 abutments were divided into four groups: control group
(abutment removed from the plastic envelop), test group1 (milled), test group2 (milled and
polished), test group3 (milled, polished and steamed). Groups were subjected to scanning electron
microscope (SEM) analysis. Pollution particles were counted and measured. Mean values and
standard deviation (SD) were calculated. To evaluate any difference between groups Wilcoxon
Signed Rank Test was conducted. In addition, contaminant chemical characterization was
investigated by Energy-dispersive X-ray spectroscopy (EDX).
Results: Control group presented minimal amount of pollution (mean value of 2.1 spots [SD: 1.66]
covering 0.004% of the surface). On the other hand, SEM analysis revealed on the abutment
surface a mean value of 115.9 (SD: 32.27), 162 (SD: 21.17), and 32.5 (SD: 9.73) spots, respectively, in
Test group 1, 2, and 3. Micro-particles covered the 0.025%, 0.057%, 0.0404% of the surface,
respectively, in Test group 1, 2, and 3. On the connection, SEM analysis revealed a mean value of
61.9 (SD: 9.07), 39 (SD: 12.35), 42.1 (SD: 8.59) spots, respectively, in Test group 1, 2, and 3. Microparticles covered the 0.0774%, 0.0869%, and 0.0392% of the surface, respectively, in Test group 1,
2, and 3. Spots were identified by EDX as micro-particles of lubricant and titanium smear layer. All
differences were statistically significant.
Conclusions: After technical procedures, presence of contaminants on the abutment surface in
contact with the peri-implant tissues was confirmed. To prevent that such debris could interfere
with biological stability of peri-implant tissues and, thus, enhance the implant-prosthesis
integration, different cleaning protocols should be evaluated
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