Original Abutments Research Articles

Effect of polishing process on torque loss ratio and microgap of selective laser melting abutment: an in vitro study

BackgroundThe purpose of this in vitro study was to investigate the effect of polishing post-treatment process on the torque loss ratio and microgap of Selective Laser Melting (SLM) abutments before and after mechanical cycling test through improving the surface roughness of the implant-abutment interface.Materials and methodsForty SLM abutments were fabricated, with 20 underwent minor back-cutting, designated as polishing, in the implant-abutment interface. The abutments were divided into three groups: SLM abutments (group A), original abutments (group B), and polished SLM abutments (group C), each containing 20 abutments. Surface roughness was evaluated using a laser microscope. Implant-abutment specimens were subjected to mechanical cycling test, and disassembly torque values were measured before and after. Scanning electron microscope (SEM) was used to measure microgap after longitudinal sectioning of specimens. Correlation between surface roughness, torque loss ratio, and microgap were evaluated. LSD’s test and Tamhane’s T2 comparison were used to analyze the data (α = 0.05).ResultsThe Sz value of polished SLM abutments (6.86 ± 0.64 μm) demonstrated a significant reduction compared to SLM abutments (26.52 ± 7.12 μm). The torque loss ratio of polished SLM abutments (24.16%) was significantly lower than SLM abutments (58.26%), while no statistically significant difference that original abutments (18.23%). The implant-abutment microgap of polished SLM abutments (2.38 ± 1.39 μm) was significantly lower than SLM abutments (8.69 ± 5.30 μm), and this difference was not statistically significant with original abutments (1.87 ± 0.81 μm). A significant positive correlation was identified between Sz values and the ratio of torque loss after cycling test (r = 0.903, P < 0.01), as well as Sz values and the microgap for all specimens in SLM abutments and polished SLM abutments (r = 0.800, P < 0.01).ConclusionThe findings of this study indicated that the polishing step of minor back-cutting can lead to a notable improvement in the roughness of SLM abutments interface, which subsequently optimized the implant-abutment fit. It can be seen that the application of minor back-cutting method has advanced the clinical use of SLM abutments.

Mechanical strength of stock and custom abutments as original and aftermarket components after thermomechanical aging.

The study aimed to assess the impact on the mechanical strength and failure patterns of implant-abutment complexes of choosing different abutment types, designs and manufacturers, aiding in selecting the optimal restorative solution. Stock and custom abutments from original and aftermarket suppliers were subjected to thermomechanical aging. Stock and custom abutments from the implant manufacturer (original) and a aftermarket supplier (nonoriginal) were connected to identical implants with internal connection. Custom abutments were designed in a typical molar and premolar design, manufactured using the workflow from the respective suppliers. A total of 90 implants (4 mm diameter, 3.4 mm platform, 13 mm length) equally divided across 6 groups (three designs, two manufacturers) underwent thermo-mechanical aging according to three different regimes, simulating five (n = 30) or 10 years (n = 30) of clinical function, or unaged control (n = 30). Subsequently, all samples were tested to failure. During aging, no failures occurred. The mean strength at failure was 1009N ± 171, showing significant differences between original and nonoriginal abutments overall (-230N ± 27.1, p < .001), and within each abutment type (p = .000), favoring original abutments. Aging did not significantly affect the failure load, while the type of abutment and manufacturer did, favoring original and custom-designed abutments. The most common failure was implant bending or deformation, significantly differing between original and nonoriginal abutments and screws. All failure tests resulted in clinically unsalvageable implants and abutments. Within the limitations of this study, original abutments exhibited a higher mechanical strength compared to the nonoriginal alternative, regardless of the amount of simulated clinical use. Similarly, custom abutments showed higher mechanical strength compared to stock abutments. However, mechanical strength in all abutments tested was higher than average chewing forces reported in literature, thus components tested in this study can be expected to perform equally well in clinical situations without excessive force.

Evaluation with a Coordinate-Measuring Machine of Dimensional Accuracy of the Abutment Duplication Technique in Cement- Retained Implant Restoration.

To evaluate the effectiveness and accuracy of a proposed duplication technique in terms of one- and three-dimensional discrepancies between an original abutment and polyurethane duplicates obtained through a conventional workflow in single-implant rehabilitation. A titanium, shoulderless abutment was chosen for a single-implant cemented rehabilitation. The master cast was made using a plastic-based die system, and the implant portion was separated. The implant section was consecutively duplicated eight times using a manual technique with polyvinyl siloxane and unfilled polyurethane resin as impression and die materials. The duplicates were analyzed with a coordinate-measuring machine (SmartScope Flash 200, Optical Gaging Products): one- and three- dimensional discrepancies were determined for each duplicate on 20 analysis points (A to T) located on the abutment surface. Changes in the abutment radius were also calculated to estimate the effects on cement thicknesses. One-dimensional discrepancies were -0.5 Å} 61.2 μm, -6.6 Å} 39.7 μm, and -19.4 Å} 47.8 μm on the X, Y, and Z axes, respectively; three-dimensional variation was -66.4 Å} 60.1 μm. Friedman test showed no significant difference between duplicates' one-dimensional variations on X (P = .059), Y (P = .156), or Z (P = .223) axes; a significant difference was found regarding three-dimensional changes (P < .001). Dunn test showed higher discrepancies on the X axis and on the abutment head. Mean variation of the abutment radius was -12.09 μm. The abutment duplication technique was shown to be an accurate and repeatable procedure for single cementable restorations.

Implant deformation and implant-abutment fracture resistance after standardized artificial aging: An in vitro study.

Zirconia abutments have been widely adopted in clinical implant practice. The unique mechanical properties of zirconia may significantly affect the long-term prognosis of implant treatments. The purpose of this study was to investigate the influence of abutment material on implant deformation and fracture resistance of internal conical connection implant-abutment complexes of two diameters after standardized artificial aging. Thirty original abutments (one-piece titanium, one-piece zirconia, zirconia with alloy base) with two diameters (regular, narrow) were connected to internal conical connection implants and subjected to a standardized artificial aging process consisting of thermal cycling and mechanical cyclic loading. Microcomputed tomography (μCT) scans of implant bodies were performed before and after aging. 3-dimensional images of implant bodies were generated from the μCT scans and aligned for before and after aging to calculate the volumetric deformation amount. Finally, fracture resistance was measured using a mechanical static loading test for the surviving aged and 30 brand-new specimens. All specimens survived artificial aging. No significant difference in implant deformation was found in the regular groups (p=0.095). In narrow groups, the one-piece zirconia group showed significantly less deformation (p < 0.0001). For fracture resistance, no significant decrease was observed after aging in any group (p > 0.05). One-piece zirconia abutments showed significantly lower strength than the other two materials for both diameters (p < 0.0001). In the regular diameter system, abutment material had no significant influence on the tested mechanical property degradation after simulated long-term oral use. The mechanical performance of narrow diameter one-piece zirconia abutments differed from the other two materials. For optimal performance, one-piece zirconia abutments should be adopted only in anterior regions.

Axial displacement of the suprastructures at the conical implant — abutment interface

BACKGROUND: The inconsistency of the congruence of the surface of the implantabutment interface leads to the impaired communication of the implant shaft with the oral cavity, breakdown of the structure, including the implant, and changes in the occlusal relationships because of axial displacement.&#x0D; AIM: This study aimed to investigate the degree of axial displacement of abutments made relative to implants and analogs. Specific tasks were as follows: (1) to make various abutments for implants with a conical connection obtained from MIS, (2) to study the value of axial displacement of abutments of each type relative to the implant with load modeling, and (3) to examine the value of the axial displacement of abutments of each type relative to the analog of the implant from the tightening force of the screw.&#x0D; MATERIALS AND METHODS: Axial displacements were tested using implants and analogs of MIS implants with conical joints. Original and non-original abutments were chosen as suprastructures. The original abutment was presented by CS-CPK62. Abutments for the conical connection C1 were made by milling, laser sintering, and casting according to burned models. The fastening of implant analogs and implants was made in a block of plaster of the 4th class. The study was conducted in a simulation complex we have developed, which creates a cyclic load within 30 kg. The study was divided into two stages. In the first stage, axial displacements on analogs from the force of screw tightening were examined. Abutments were attached with various forces: 7 Ncm (tightening force with a simple screwdriver), 15 Ncm, and 30 Ncm. After each screw tightening, vertical measurements were made with a micrometer. In the second stage, axial displacements on implants under load in the original simulation complex were assessed. The screw was tightened with a force of 30 Ncm, as recommended by the manufacturer, and load simulation was performed. Measurements were made both before and after the load simulation.&#x0D; RESULTS: The original abutments and those made by milling showed the greatest deviation (0.056 mm and 0.066 mm, respectively), and abutments obtained by casting had deviations of 0.047 mm. The smallest deviation was found in the abutment made by laser sintering (0.032 mm). The values obtained in the second stage were as follows. Original abutments and abutments obtained by milling showed the smallest axial displacement when modeling the load (0.00167 mm each). Moreover, the abutments obtained by casting and laser melting showed significant displacements (0.007 mm and 0.004 mm, respectively).&#x0D; CONCLUSIONS: A pattern was revealed: the smoother the surface of the conical parts, the stronger the axial displacement on the analog implants in the range of 730 Ncm, whereas an uneven surface gives the smallest axial displacement, and fixation according to the protocol provided resistance to chewing loads on the implants in the original and milled abutments. The use of a platform with a conical system to create high-precision orthopedic structures has certain limitations because an error in the height of the restoration is created in laboratory conditions. The use of non-original suprastructures leads to the accumulation of errors. Thus, it is necessary to further evaluate conical systems from other manufacturers and improve the accuracy of restorations based on dental implants.

Settling effect of abutment and torque loss in different types of abutment after cyclic loading.

This study aimed to evaluate and compare the settling effect of implant-abutment assembly and the torque loss before and after cyclic loading in three types of abutments. Thirty internal hexagon fixtures were randomly divided into three groups (n=10). Group A used original abutments, group B used pre-machined cast abutments, and group C used compatible abutments. In addition, the abutment morse taper angle was measured using an image measuring instrument. Removal torque values (RTVs) were recorded using a digital torque meter before and after cyclic loading. All samples were tested in a universal testing machine with a vertical load between 0 and 250 N for 100 000 cycles of 10 Hz. The settling effect was measured after cyclic loading. Paired t test was performed for intragroup analysis of removal torque loss before and after cycling and one-way ANOVA. Subsequently, Tukey's honestly significant difference test was used for intergroup comparison (α=0.05). The paired t-test showed signi⁃ficant differences in the intragroup RTVs before and after cycling (P<0.001). ANOVA showed significant differences in the mean of removal torque loss after cycling (P=0.009), the abutment morse taper angle (P<0.001), and the settling values (P=0.01) among different groups. However, no significant difference was found between compatible abutments and pre-machined cast abutments. The screw removal torque was significantly reduced for all groups in this study after cyclic loading. Differences could be found in the internal accuracy of implant-abutment assembly among different groups. Within the limitations of this study, the results showed the original abutments exhibited lower percentages of torque reduction after cyclic loading than the casting abutments and the compatible abutments.

Accuracy of Original vs. Non-Original Abutments Using Various Connection Geometries for Single Unit Restorations: A Systematic Review.

To ascertain whether the compatibility of non-original abutments (NOAs) with dental implants is influenced by the type of implant connection, i.e.- internal or external, and whether certain combinations of componentry may be as compatible as the original components. A structured literature search was conducted using 3 electronic databases (MEDLINE® , The Cochrane Library, and Web of Science Core Collection) for studies reporting on the use of non-original abutments published between 1995 and 2020. This was supplemented with hand searching in relevant journals and references, as well as searching grey literature. Relevant studies were selected according to specific inclusion criteria. Data was collected for the following parameters: precision of fit, microleakage, micromorphological differences, micromotion, rotational misfit, screw loosening, maximum load capacity, fracture resistance, tensile strength, compressive strength and invivo implant and prosthesis outcomes. The electronic search and hand search yielded titles and abstracts of 5617 studies following de-duplication; based on the eligibility criteria, 40 studies were finally selected. Overall, original abutments showed better precision of fit, ability to resist microleakage, prevention of rotational misfit and micromotion, and fatigue strength compared with non-original abutments. Some non-original abutments on external connections were comparable with original abutments in terms of precision of fit and resistance to screw loosening and may be associated with less catastrophic failures than those on internal connections. Original abutments present more predictable outcomes than non-original abutments with regards to the parameters investigated. However, it seems that external connections can provide some level of compatibility in terms of precision of fit and may also exhibit less catastrophic failures than NOAs on internal connections. This may be due to the increased rotational freedom external connections provide. There is a lack of information regarding the influence of connection geometry on many aspects of compatibility and therefore the current clinical recommendation should be to use original abutments. More laboratory studies comparing non-original abutments on different implant connections are required. In addition, there is a need for long-term in vivo studies providing data on the clinical performance of non-original abutments.

Original vs compatible stock abutment- implant connection: An in vitro analysis of the internal accuracy and mechanical fatigue behaviour.

To assess the internal accuracy and mechanical behaviour under cyclic loading after artificial aging of implant-supported crowns restored with original stock abutments and two compatible non-original stock abutments. Forty-eight original internal hexagon connection implants were connected to different stock abutments. The samples were divided into three groups depending on the manufacturer of the abutment components (one original, two non-originals).Firstly, samples were cross-sectioned and observed by using Scanning Electron Microscope (SEM) to evaluate the internal accuracy in three different implant-abutment interface locations (platform, internal and screw).Further, cyclic fatigue loading was carried out according to the ISO Norm 14801 using dynamic testing machine under sinusoidal loads for 2,000,000 cycles at test frequencies of 2 Hz in air after thermocycling with 10,000 cycles at 5 °C and 55 °C in artificial saliva for aging simulation. Original abutment components presented the highest percentage of surface with tight contact with the implant in the three implant-abutment interfaces studied. Additionally, original configuration showed highest fatigue limit value and fatigue strength exponent (280 N and -0.054) than non-original 1 (225 N and -0.109) and non-original 2 (200 N and -0.101). Original abutment components provide better fit and mechanical results under cyclic loading than non-original configurations. The results obtained in this study seem to suggest that the use of the original stock abutments to implants leads to a more homogeneous load distribution between the components that can influence the long-term success of the restorations.

Comparison of original and universal screwdrivers: Damage to the surface of the socket within the screw head of the abutment screw

The aim of the study was to investigate the potential damage the usage of universal screwdrivers could cause to the abutment screw. In this study the original versus the universal screwdriver have been compared. 26 original abutment screws, 13 from Straumann and 13 from BEGO, were screwed in with the original and the universal screwdriver. For optical evaluation, the potential damage to the screw head was documented in two different areas. For this purpose, photos were taken with a scanning electron microscope. At Straumann, surface damage was only seen in area 1 (top of the screw head) when using the universal screwdriver. BEGO showed surface damage in area 1 regardless of which screwdriver was used and in area 2 (bottom of the screw head) when using the universal screwdriver. It can be assumed that the use of the original screwdriver might cause little or no damage to the screw heads. In contrast, based on the SEM images, it can be assumed that the surface can be damaged when using the universal screwdriver.

Original versus nonoriginal cast-to-gold abutment-implant connection: Analysis of the internal fit and long-term fatigue performance

Statement of problemRestoring implants with nonoriginal abutments is common. However, studies that evaluated compatible abutments with long-term fatigue performance are lacking. PurposeThe purpose of this in vitro study was to assess the internal fit and the cyclic fatigue life after artificial aging of 3 implant-abutment configurations restored with 1 original and 2 compatible nonoriginal cast-to-gold abutments. Material and methodsForty-eight original internal hexagon connection implants were connected to 3 different brands of abutments (n=16): 1 original to the implant system and the other 2 with nonoriginal abutments. Internal fit and the percentage of surface with tight contact were assessed by scanning electron microscopy in 12 cross-sectioned specimens (n=4) at 3 different areas (platform, internal, and screw). Thirty-six implant-abutment-crown specimens (n=12) were immersed in artificial saliva and thermocycled for 10 000 cycles between 5 °C and 55 °C. Subsequently, a cyclic load test, as per International Organization for Standardization (ISO) Standard 14 801, was completed in a universal testing machine at 2 Hz in air. ResultsThe original abutments presented the best fit and highest percentage of tight contact in the internal areas. In addition, the original abutments showed the lower cyclic fatigue strength degradation and the highest long-term success. ConclusionsOcclusal loads are transferred more homogenously through the system when original abutments are used because of the better fit between the internal components, leading to increased fatigue resistance.

Comparing Original and Universal Screwdrivers in Terms of Torque Loss in the Abutment Screw

Objective: The aim of this study was to examine whether tightening or loosening the abutment screw results in torque loss and whether there is a difference in this respect between original screwdrivers and universal screwdrivers. Materials and Methods: For the purpose of the study, two groups were formed, with the original screwdriver used in group 1 and the universal screwdriver used in group 2. One Straumann implant and one BEGO implant were each inserted into a stationary torque transducer. The next step was to screw 13 abutments into each implant with 13 original abutment screws, using the screwdriver assigned to the group with the torque specified by the manufacturer. To establish whether the torque transmitted to the abutment screw via the screwdriver is also transmitted to the implant rather than causing deformation of the screw head or being transmitted to the surrounding area, the actual torque transmitted from the screw to the implant was measured and recorded electronically during the experiment. Results: There was no loss of torque in the transmission of the tightening torque to the Straumann implant with either screwdriver (P &gt; 0.05). There was a loss of torque in the transmission of the tightening torque to the BEGO implant when using the universal screwdriver but not with the original screwdriver (P &lt; 0.01). Relative to the previously applied tightening torque, a loss of torque when loosening the screw was found with both screwdrivers, both Straumann (P &gt; 0.05) and BEGO (P &lt; 0.05). Conclusion: Using universal screwdrivers can result in loss of torque. The loosening torque is thus decreased, which in turn increases the likelihood of complications such as screw loosening.

Biomechanical effects of original equipment manufacturer and aftermarket abutment screws in zirconia abutment on dental implant assembly

The use of aftermarket computer-aided design/computer-assisted manufacturing (CAD/CAM) prosthesis components in dental implants has become popular. This study aimed to (1) compare the accuracy of aftermarket CAD/CAM screws with that of original equipment manufacturer (OEM) abutment screws and (2) examine the biomechanical effects of different abutment screws used with zirconia abutment in an implant fixture by using three-dimensional finite element analysis (FEA). Significantly different measurements were obtained for the aftermarket CAD/CAM and OEM screws. The FEA results indicated that under the same loading condition, the maximum stress of the aftermarket CAD/CAM screws was 15.9% higher than that of the OEM screws. Moreover, the maximum stress position occurred in a wide section of the OEM screws but in the narrowest section of the aftermarket screws. The stress of the OEM zirconia abutment was 14.9% higher when using the aftermarket screws than when using the OEM screws. The effect of the manufacturing differences between aftermarket and OEM screws on the clinical effect of aftermarket screws is unpredictable. Therefore, aftermarket screws should be cautiously used clinically.

Great Western electrification programme, UK: Bridge Street overbridge reconstruction

Bridge Street overbridge next to Newport station in south Wales was replaced to enable electrification of the Great Western main line railway between London and Cardiff. The former 120-year-old steel truss bridge was too low and in poor condition, so a half-through weathering steel–concrete composite bridge deck with a smaller structural depth was lifted onto the existing abutments. The new bridge requires minimal maintenance, reducing overhead-line hazards and whole-life costs. This paper describes the key considerations and challenges associated with the strengthening and removal of the existing superstructure, the modifications that were required to the original abutments, and the design and construction of the new superstructure.

Compatibility of Nonoriginal Abutments With Implants: Evaluation of Microgap at the Implant-Abutment Interface, With Original and Nonoriginal Abutments.

The purpose of this study was to evaluate the fit of nonoriginal abutments to implants at the implant abutment junction. Twenty titanium implants from a single manufacturer were randomly divided into 2 groups of ten each. Ten titanium premachined original abutments (group I) and ten titanium premachined nonoriginal abutments (from different manufacturer-group II) were connected to the implants with the recommended manufacturer torque level and then embedded into autopolymerizing clear acrylic resin blocks. After overnight curing, these blocks were vertically sectioned using water jet sectioning machine and evaluated under scanning electron microscope following the sequential cleaning procedures. The microgap at the implant-abutment interface for all the samples was measured using pixel counting software and subjected to statistical analysis using nonparametric Mann-Whitney U test. The mean microgap at the implant-abutment interface at the external, middle, and internal points was 1.597, 1.399, and 1.831 µm, respectively, for group I and 2.395, 2.488, and 3.339 µm, respectively, for group II samples. Nonparametric Mann-Whitney U test showed statistically significant difference between 2 groups at the midpoint for the nonoriginal abutments compared with the original ones. Within the limitations of the study, the mean microgap at the implant-abutment interface at the platform level at the external, middle, and internal points for both original abutments and nonoriginal abutments was found to be within clinically acceptable limits.

Mechanical Outcomes, Microleakage, and Marginal Accuracy at the Implant-Abutment Interface of Original versus Nonoriginal Implant Abutments: A Systematic Review of In Vitro Studies.

Purpose Instead of original abutments, compatible abutments are often selected for financial reasons. The present study aimed to evaluate mechanical outcomes, microleakage, and marginal accuracy at the implant-abutment interface of original versus nonoriginal implant abutments. Study Selection Search strategy encompassed literature from 1967 up to March 2017 to identify relevant studies meeting the inclusion criteria. The following electronic databases were consulted: PubMed database of the U.S. National Library of Medicine, Embase (Excerpta Medica dataBASE), and the Grey Literature Database (New York Academy of Medicine Grey Literature Report). Quality assessment of the full-text articles selected was performed. Abutments were classified in original (produced by the same implant manufacturer), nonoriginal certified (produced by a third-party milling center, certified by implant companies), and nonoriginal compatible (produced by a third-party milling center for similar connections). Results A total of 16 articles fulfilled inclusion criteria and quality assessment and were selected for the qualitative analysis. All of the included studies were in vitro research with high or moderate risk of bias and reported data from 653 implant abutments. Original and nonoriginal certified abutments showed better results in terms of mechanical outcomes, microleakage, and marginal accuracy compared to nonoriginal compatible abutments. Conclusions Following the clear warnings coming from the present systematic review, clinical suggestions regarding the effect of a nonoriginal abutment can be drawn. However, in vivo, long-term, randomized controlled trials are needed to provide definitive clinical conclusion about the long-term clinical outcomes of original and nonoriginal abutments.

In Vitro Characterization of Original and Nonoriginal Implant Abutments.

In addition to original componentry, clinicians can choose to restore an implant using third-party parts claimed to be compatible with the original implant system. The goal of these in vitro experiments was to evaluate the performance of a selection of original and clone titanium abutments available for a widely used implant system with an internal conical connection. Six groups of original and clone abutments compatible with NobelActive implants were compared based on the following parameters: dimensional accuracy, gap formation, circumferential strain, abutment screw preload, micromotion, abutment settling, median fatigue limit (MFL), and bacterial leakage. Each parameter was analyzed separately and compared with the original (reference) abutment applying a variety of statistical tests (α = .05). Overall, the results obtained in the different experiments showed considerable deviation from the reference abutment. Deviations in interface geometry of the abutments were inconsistent and reached up to 56.26%. Gap measurements performed on cross sections of implant-abutment assemblies were not sensitive enough for detecting consistent differences. Development of circumferential strain at the implant shoulder reached up to 1,389.30 μm/m. Abutment screw preload ranged from 285.25 N to 397.70 N, while micromotion at the implant-abutment interface ranged from 61.68 μm to 79.69 μm. Abutment settling resulting from screw fixation was greater compared with settling caused by dynamic loading, reaching up to 0.09 mm. The MFL ranged from 246.00 N to 344.00 N. All implant-abutment combinations showed bacterial leakage after 6 days of incubation. While clone abutments may look similar to the original component, they display considerable differences and variations in their physico-mechanical characteristics detectable by advanced testing methods. How much these differences affect reliability and longevity of the restoration's clinical performance should be investigated in clinical studies.

Stratification of prosthetic complications by manufacturer in implant-supported restorations with a 5 years' follow-up: systematic review of the literature.

Prosthetic complications on implant-supported restorations have been documented in several papers published in the literature. Several manufacturers are present on the market but results are often cumulated and may thus be misleading. The objective of the present review is to assess the prosthetic complications of implant-supported restorations with particular interest of the results obtained with prostheses from different manufacturers. A manual search of Medline/PubMed was carried out up to June 2016, yielding a total of 6832 articles, which were narrowed down to 1450, then 347 abstracts to include 55 papers after full text reading. Papers with at least 5 years of follow-up reporting on prosthetic complications of single and fixed partial prosthesis were included. Prosthetic complications were divided into mechanical and technical complications, and reported in a table. Overall 14.4% of prosthetic complication was found for a total of 6623 restorations followed for an average of 7.4 years (range 5-16 years). Results where then sorted and compared. Single crowns were affected by 1.4% of mechanical complications and 10.9% of technical complications after a mean of 7.4 years. Fixed partial prosthesis were affected by 2.5% of mechanical complications and 18% of technical complications. Screw-retained and cemented restorations were calculated to have a 5 years rate of complications of 21.2% and 9.3%, respectively, which demonstrated a statistically difference with fisher exact test with P<0.1. Only 3 manufacturers presented more than 10 articles and were directly compared with Fisher's exact test with P<0.1. The incidence of overall complications was estimated to be after 5 years of 11.2%, 10.8% and 13.8% for Straumann, Nobel, and Astratech, respectively, but dividing results in mechanical and technical complications, gave different results. Straumann was estimated to have less mechanical complications after 5 years in respect to Nobel and Astratech, but the three were similar for technical complications. although studies present very different material and methods and do not report all data, some conclusions can be made. The difference between mechanical complications lead the authors to suppose that there might be a difference in results obtained by different implant abutment connections. It is also noticed that all papers were published by expert clinicians and universities research centers that apply rigid surgical and prosthetic protocols and use original abutments.

Compatible CAD-CAM titanium abutments for posterior single-implant tooth replacement: A retrospective case series

Statement of problemIn addition to the original abutments provided by implant companies, compatible computer-aided design and computer-aided manufacturing (CAD-CAM) abutments are also available from different manufacturers. However, the combination of abutments and implant systems from different manufacturers may lead to mechanical problems between components. Little has been reported on the clinical performance of this treatment option. PurposeThe purpose of this retrospective case series was to evaluate the outcome of compatible CAD-CAM titanium abutments (TiAs) for posterior single-implant tooth replacement (PSITR) up to 6 years after insertion. Material and methodsEighty-one patients (34 men, 47 women) who received PSITR restored with compatible CAD-CAM TiAs and had a final recall examination between May 2014 and April 2015 were included in this study. Clinical and radiographic examinations were documented. Retrospective evaluation of the patient records was also performed. Correlations between bone-level changes and variables were calculated using the Spearman correlation. ResultsImplant and prosthesis survival rates were 100%. Twenty technical complications were observed, including 9 decementations of the crown, 6 screw loosenings, and 5 ceramic fractures. Periimplant mucositis was diagnosed in 36 patients (44.4%) and periimplantitis in 6 patients (7.4%). Correlation analysis showed a significant effect of the extent of periodontal bone loss of the remaining teeth on the marginal bone-level changes around implants (r=0.548, P<.001). ConclusionsCompatible CAD-CAM TiAs provide a viable treatment option for PSITR. However, in light of relatively high screw-loosening and decementation rates, choosing appropriate cements and abutment manufacturers is essential to improve the clinical performance of this treatment option.

EVALUATION OF THE ACCURACY OF ABUTMENT LEVEL IMPRESSION IN “ALL ON FOUR” IMPLANT CASES

Objectives: A lack of parallelism among the implants, and that between the implants and the teeth is a common finding in clinical situations. The aim of the following study was to evaluate the accuracy of abutment level impression in “All On Four” cases. Materials and methods: Five completely edentulous patients restored with “All On Four” distribution of implants in the lower arch were recruited in this study. Prior to restoration two impressions were made for each case. The first impression utilized a specific abutment level impression (recommended by the manufacturer) and poured into a stone cast; trans-mucosal abutments were then screwed onto the implant analogues. The second impression was in a form of a simple impression of the trans-mucosal abutments, and poured into a stone cast. This group was considered as the control group. Both casts were photographed and using the Digimizer® Software V. 4.3.1 linear measurements and surface areas were measured on the casts and compared. Results: Using independent t-test, there was a significant difference between the linear measurements and surface areas measured on the casts produced by both impression techniques, where (P-value < 0.05). Conclusion: In angulated implant cases (All On Four), the position of abutments on a cast produced by the abutment level impressions used showed statistically significant difference from the original abutments’ position in the patients’ mouth.

Diagnostic Assessment of One of the First Generation of Prestressed Concrete Bridges in Slovakia

The first generation of precast prestressed girder bridges have been used in Czechoslovakia in the 1950s. Nowadays, many of this bridges are in insufficient condition and require extensive rehabilitation. Concrete bridge No. 59-090 on the important international route I/59 connecting Slovakia to Poland, was in failure condition before collapse. After visual inspection it was necessary to definitely eliminate traffic on the bridge. The diagnostic survey has confirmed the necessity to replace the superstructure of the bridge and repair the original abutments and bridge pier. The bridge was closed and the traffic was redirected on temporary bridge during the reconstruction time. This paper focuses on the diagnostic survey of this type of prestressed concrete bridge.