Straumann Tissue-level Implants Research Articles

Assessment of the efficacy of posterior extra-short implant support for an interforaminal implant-supported fixed full-arch mandibular prosthesis

Aim The purpose of the present study was to determine whether it is useful to support a fixed full-arch prosthesis supported by interforaminal implants, with extra-short implants (4 mm) in the posterior region in order to eliminate the cantilever extensions, in posterior atrophic mandible cases. Methods Six different models including three or four interforaminal implants with or without support of posterior extra-short implants were formed. Straumann tissue-level implants (4.1x12mm and 4.1x4mm) were modeled for this study. Spherical loadings from canine and molar regions were applied to evaluate tension, compression, and von Mises stresses by implementing finite element analysis. Results In most conditions, four interforaminal implant supports provide balanced stress distributions, on the other hand, only three interforaminal implants were found to be insufficient biomechanically. The support of interforaminal implants with extra-short implants in the posterior region did not show the expected contribution, especially against the forces in the canine region. Also, the placement of four posterior extra-short implants does not make significant difference compared to the placement of two extra-short implants. Conclusions Implant-supported fixed prosthetic rehabilitation with cantilever extension of an edentulous mandible supported by four implants in the interforaminal region reached the best biomechanical results of the present study.

Retrospective comparison of posterior fixed dental prostheses supported by two different titanium abutments on tissue level implants

Statement of problemClinical studies comparing compatible computer-aided design and computer-aided manufacturing (CAD-CAM) titanium abutments (CAs) and original prefabricated 1-piece titanium abutments (PAs) for posterior fixed dental prostheses (FDPs) on Straumann Tissue Level (STL) implants are sparse. PurposeThe purpose of this retrospective clinical study was to compare the performance of posterior FDPs supported by CAs and PAs on STL implants after a mean observation period of 7.2 years. Material and methodsPatients who received STL implants and posterior FDPs by using CAs or PAs between January 2002 and December 2012 and returned for follow-up between January 2017 and September 2018 were included in this study. Technical and biological complications of FDPs were examined and recorded. Radiographs were used for the measurement of marginal bone loss (MBL) of each implant. Variables, complication rates, and MBL of the 2 groups were analyzed by using a generalized estimating equation and multivariable linear mixed model. ResultsNinety-nine patients with 195 implants in the CA group and 75 patients with 143 implants in the PA group were included. The mean functional time of FDPs was 6.5 ±1.1 years for the CA group and 8.1 ±2.6 years for the PA group. No implant failure was noted in either group. The technical complication rate was 20.8% in the CA group and 26.3% in the PA group. Abutment screw loosening (ASL) was noted in the CA group (8.5%). The decementation rate was significantly higher in the PA group (14.1%) than that in the CA group (3.1%) (adjusted odds ratio=4.40, confidence interval=1.41 to 13.69, P=.011). No significant differences were found between the 2 groups in terms of the rates of ceramic chipping, peri-implantitis, peri-implant mucositis, or mean MBL. ConclusionsUsing CAs or PAs to support posterior FDPs on STL implants has no significant effect on the incidence rate of biological complications. However, a higher ASL rate and a lower decementation rate were noted with CAs than with PAs.

Cyclic loading impact on screw loosening of internally connected implants: an experimental study

Objective The aim of this study was to assess impact of cyclic loading on screws attached to four different abutments to internally connected implants. Materials and methods Four groups (seven implants each) of dissimilar abutments were included in this study. Abutments were connected to Straumann tissue-level implants. Each implant was rigidly secured in a stainless steel cylindrical jig. A torque controller was used to tighten the abutments at 35 N cm. A 150 N cyclic load for 1 million cycles was applied to the implant at a 30° angle to the long axis to the implants. Periotest values (PTVs) were measured before and after cyclic loading and a digital torque gauge used to detect the removal torque values (RTVs) of abutments. The data were analyzed statistically using SPSS and Kruskal–Wallis tests and one-way analysis of variance were used to compare RTVs and PTVs after application of equal loads for each group. The Spearman correlation coefficient was applied to compare RTVs and PTVs after loading. Results The Straumann solid abutment and the Southern solid abutment showed no mechanical failures. Screws fracture was noted in nearly 85% of Implant Direct abutment, and 55% of the Blue Sky Bio abutments. The final mean PTV of the Blue Sky Bio abutments, the Southern Implants, and Implant Direct straight abutment was considerably higher than the final mean PTVs of Straumann solid abutment. Conclusion Abutments from the different manufacturers have different physical and chemical characteristics. So there was a potential risk of mechanical failure when the interchangeable abutments are used. Thus, the use of an abutment manufactured by the same implant company is highly recommended for the avoidance of loosening of the abutment screws.

Osteointegration of Tissue-Level Implants With Very Low Insertion Torque in Soft Bone: A Clinical Study on SLA Surface Treatment.

Evidence shows lower percentage of osteointegration when implants are placed without sufficient primary stability. The present work tested the hypothesis that implants unstable at insertion could achieve osteointegration with proper implant surface treatment. Eleven Straumann tissue-level implants with sandblasted, large-grit, acid-etched (SLA) surface treatment were placed in soft bone unfavorable to primary stability, as indicated by insertion torque lower than 10 N/cm and slight mobility on the application of a lateral load of 250 g. After 4 to 6 months of healing, a reverse torque of 35 Ncm was applied to assess osteointegration. All implants appeared to be clinically osseointegrated and were successfully restored and loaded with fixed partial dentures or single crowns. After 28.5 months, all implants remained functional. Within the limitations of the low number of implants analyzed, it can be concluded that tissue-level implants with sand-blasted and acid-etched surface treatment can achieve osteointegration, even in the absence of primary stability.

Micromorphological differences of the implant-abutment junction and invitro load testing for three different titanium abutments on Straumann tissue level implants.

The aim of this study was to investigate the micromorphological differences among three commercially available titanium abutments on Straumann implants. Furthermore, the possible impact of functional loading on the micromorphology and potential complications was investigated with the use of invitro testing. Three groups of Titanium abutments (A: Straumann Variobase n=5, B: EBI best Duo n=5, and C: Implant Direct n=5) were torqued on Straumann RN implants, as according to each of the manufacturer's instructions. The implant-abutment units were scanned with Micro-CT. Three units of each group were directly sliced in the microtome and photographed under different magnifications (10×-500×) through a Scanning Electron Microscope. Six units (two from each group) were restored with cement-retained crowns, subjected to 2000,000 load cycles with loads between 30 and 300N at 2Hz, examined through Micro-CT and finally sliced and photographed as described above. The micromorphology of each unit was studied, and the total length of tight contact (<3μm) was calculated between the implant, abutment and screw contact areas. Major morphological differences were identified between the three units, as well as differences in the extent of tight contact in all areas examined. Despite the morphological differences, the 2M cycles of loading via invitro test did not result in any noticeable complications although some changes in the micromorphology were observed. The examined implant-abutment units presented with major morphological differences. Two million cycles of invitro loading did not appear to affect the stability of the units despite the micromorphological changes. These results need to be interpreted however under the limitations of the small sample size and the specific set-up of the invitro testing.

An In Vitro Evaluation of the Loosening of Different Interchangeable Abutments in Internal-Connection-Type Implants.

The aim of this study was to compare the loosening of interchangeable one-piece abutments connected to internal-connection-type implants after cyclic loading. Four implant abutment groups (n = 7 in each group) with Straumann tissue-level implants were assessed: Straumann solid abutment (group S), Southern Implants solid abutment (group SI), Implant Direct straight abutment (group ID), and Blue Sky Bio regular platform abutment (group BSB). The implant was firmly held in a special jig to ensure fixation. Abutment screws were tightened to manufacturers' recommended torque with a digital torque gauge. The hemispherical loading members were fabricated for the load cell of a universal testing machine to evenly distribute the force on the specimens and to fulfill the ISO 14801:2007 standard. A cyclic loading of 25 N at 30 degrees to the implant's long axis was applied for a duty of a half million cycles. Tightening torques were measured prior to the loading. Removal torques were measured after cyclic loading. The data were analyzed with one-way analysis of variance (ANOVA), and the significance level was set at P < .05. The mean removal torques after cyclic loading were 34.0 ± 1.1 Ncm (group S), 25.0 ± 1.5 Ncm (group SI), 23.9 ± 2.1 Ncm (group ID), and 27.9 ± 1.3 Ncm (group BSB). Removal torques of each group were statistically different in the order of group S > group BSB > groups SI and ID (P < .05). The mean reduction rates were -2.9% ± 3.2% (group S), -21.9% ± 4.8% (group SI), -20.2% ± 7.2% (group ID), and -6.9% ± 4.3% (group BSB) after a half million cycles, respectively. Reduction rates of groups S and BSB were statistically lower than those of groups SI and ID (P < .01). The standard deviation of group S was lower than group BSB. The removal torque of the original Straumann abutment was significantly higher than those of the copy abutments. The reduction rate of the groups S and BSB abutments was lower than those of the other copy abutments.

In Vitro Analysis of Post-fatigue Reverse-Torque Values at the Dental Abutment/Implant Interface for a Unitarian Abutment Design

This study analyzed baseline and post-fatigue reverse-torque values (RTVs) for a specific brand control abutment relative to a third party compatible abutment. The purpose of this study was to compare the abutments' fatigue resistance to simulated function, using RTVs as an indication of residual preload at the implant/abutment interface. Forty Straumann tissue-level implants were mounted in resin and divided into four groups (n = 10). Forty abutments were seated, 20 control and 20 third-party abutments, according to manufacturer guidelines. Ten abutments from each manufacturer were evaluated for RTV without fatigue loading, using a calibrated digital torque gauge to provide a baseline RTVs. Fatigue loading was carried out on the remaining ten specimens from each manufacturer according to ISO 14801 guidelines. A moving-magnet linear motor was used to load one specimen per sequence, alternating from 10 to 200 N at 15 Hz for 5×10(6) cycles. RTV was recorded post-fatigue loading. The results were subjected to two-sample t-testing and two-way ANOVA. Scanning electron microphotography was carried out on three specimens from both manufacturers at baseline and post-fatigue cycling to visualize thread geometry and the abutment/implant interface. The data indicated that mean post-fatigue RTV observed for the control group was significantly higher than the third-party group (RTV 42.65 ± 6.70 N vs. 36.25 ± 2.63 N, p= 0.0161). Visual differences at the macro/microscopic level were also apparent for thread geometry, with third-party abutments demonstrating considerably greater variation in geometrical architecture than control specimens. Within the limitations of this in vitro model, the effect of component manufacturer resulted in a significantly higher RTV in the control group (two-way ANOVA, p= 0.0032) indicating greater residual preload; however, there was no significant decrease in post-fatigue RTV for either manufacturer compared to baseline.

Factors influencing resonance frequency analysis assessed by Osstell™mentor during implant tissue integration: I. Instrument positioning, bone structure, implant length

To monitor longitudinally the development of implant stability of SLA Straumann tissue-level implants using resonance frequency analysis (RFA) and to determine the influence of instrument positioning, bone structure and implant length on the assessment of RFA. Thirty-two healthy adult patients received either 8 mm, v4.1 mm Straumann Standard Plus tissue-level implants (n=16: Group A) or 10 mm, v4.1 mm Straumann Standard Plus tissue-level implants (n=16: Group B). During healing, RFA was performed on Weeks 0,1, 2, 3, 4, 5, 6, 8 and 12. The implants were restored after 10 weeks (impression taking) and 12 weeks. In addition, probing depth, presence of plaque and bleeding on probing were assessed. Implant stability quotient (ISQ) values of Groups A and B were compared using unpaired t-tests and longitudinally applying paired t-tests between Week 0 and the subsequent time points. Positioning of the Osstell mentor device did not affect the ISQ values. Generally, ISQ values increased continuously during healing from a mean of 65.1 (SD 16.97) to 74.7 (SD 5.17) (significantly from Week 0 to Weeks 6, 8 and 12). Lower bone density (Type III or IV) resulted in significantly lower ISQ values up to Week 8. Implant length affected the increase in ISQ values over time. While no significant increase was observed with 10 mm implants, ISQ values of 8 mm implants increased significantly from Week 0 to Weeks 6, 8 and 12. Using Osstell mentor, ISQ values are reproducible irrespective of instrument positioning. ISQ values are affected by the bone structure and implant length. Hence, no predictive values can be attributed to implant stability.

Factors influencing resonance frequency analysis assessed by Osstell™mentor during implant tissue integration: II. Implant surface modifications and implant diameter

To monitor the development of the stability of Straumann tissue-level implants during the early phases of healing by resonance frequency analysis (RFA) and to determine the influence of implant surface modification and diameter. A total of twenty-five 10 mm length implants including 12 SLA RN v4.1 mm implants, eight SLActive RN v4.1 mm implants and five SLA WN v4.8 mm implants were placed. Implant stability quotient (ISQ) values were determined with Osstell mentor at baseline, 4 days, 1, 2, 3, 4, 6, 8 and 12 weeks post-surgery. ISQ values were compared between implant types using unpaired t-tests and longitudinally within implant types using paired t-tests. During healing, ISQ decreased by 3-4 values after installation and reached the lowest values at 3 weeks. Following this, the ISQ values increased steadily for all implants and up to 12 weeks. No significant differences were noted over time. The longitudinal changes in the ISQ values showed the same patterns for SLA implants, SLActive implants and WB implants. At placement, the mean ISQ values were 72.6, 75.7 and 74.4, respectively. The mean lowest ISQ values, recorded at 3 weeks, were 69.9, 71.4 and 69.8, respectively. At 12 weeks, the mean ISQ values were 76.5, 78.8 and 77.8, respectively. The mean ISQ values at all observation periods did not differ significantly among the various types. Single ISQ values ranged from 55 to 84 during the entire healing period. Pocket probing depths of the implants ranged from 1 to 3 mm and bleeding on probing from 0 to 2 sites/implant post-surgically. All ISQ values indicated the stability of Straumann implants over a 12-week healing period. All implants showed a slight decrease after installation, with the lowest ISQ values being reached at 3 weeks. ISQ values were restored 8 weeks post-surgically. It is recommended to monitor implant stability by RFA at 3 and 8 weeks post-surgically. However, neither implant surface modifications (SLActive) nor implant diameter were revealed by RFA.