Conical Implant-abutment Connection Research Articles

In vitro assessment of internal implant-abutment connections with different cone angles under static loading using synchrotron-based radiation

BackgroundThe stability of implant-abutment connection is crucial to minimize mechanical and biological complications. Therefore, an assessment of the microgap behavior and abutment displacement in different implant-abutment designs was performed.MethodsFour implant systems were tested, three with a conical implant-abutment connection based on friction fit and a cone angle < 12 ° (Medentika, Medentis, NobelActive) and a system with an angulated connection (< 40°) (Semados). In different static loading conditions (30 N − 90º, 100 N − 90º, 200 N − 30º) the microgap and abutment displacement was evaluated using synchrotron-based microtomography and phase-contrast radioscopy with numerical forward simulation of the optical Fresnel propagation yielding an accuracy down to 0.1 μm.ResultsMicrogaps were present in all implant systems prior to loading (0.15–9 μm). Values increased with mounting force and angle up to 40.5 μm at an off axis loading of 100 N in a 90° angle.ConclusionsIn contrast to the implant-abutment connection with a large cone angle (45°), the conical connections based on a friction fit (small cone angles with < 12°) demonstrated an abutment displacement which resulted in a deformation of the outer implant wall. The design of the implant-abutment connection seems to be crucial for the force distribution on the implant wall which might influence peri-implant bone stability.

Screw preload loss under occlusal load as a predictor of loosening risk in varying dental implant designs

PurposeScrew loosening is a critical aspect of an implant design, as it can lead to implant failure. This study proposes a methodology and qualitatively assesses the potential of screw loosening risk for various types of screw heads and implant fixture-abutment connections. It is assumed that the risk of screw loosening is related to the drop in loosening moment under occlusal loads. The methodology and an assumption is verified by confronting the results with laboratory tests. MethodsNumerical simulations supplemented with semi-empirical equations were employed to estimate a loosening moment change under occlusal loads. The loosening risk was estimated by comparing the value before and after application of a compressive occlusal load of 150N. The procedure was carried out for 289 implant designs with smooth transition between flat to tapered shape of a screw head and an fixture-abutment connection. All analyses were conducted using Abaqus software. Pearson and Spearman correlation coefficients for normalised change in a screw loosening moment drop has been computed for numerical and laboratory tests. ResultsThe statistical analysis (Pearson, ρ = 0.8, Spearman, rs = 0.85) indicates very high correlation and confirms that the general tendencies observed in laboratory tests are reflected in the proposed procedure. The procedure was used for various geometries and the following results are presented: a screw loosening drop, implant stiffness and a tightening moment. The loosening moment drop achieves the extreme values of 6% and 24%. The biggest drop is an effect of a conical implant-abutment connection and a flat screw head while the lowest was recorded for a flat implant-abutment interface regardless of a screw head type. A low drop is also observed for a strongly conical screw head. ConclusionsThe proposed methodology exhibited very good correlation when confronted with laboratory tests, supporting a screw preload reduction under occlusal load as a key factor in screw loosening. Analysis across a wide spectrum of implant designs revealed geometry significantly impacts loosening potential under occlusal loads. Two key features were identified as favourable - an abutment-fixture butt joint and a tapered screw. The results also enable prediction of qualitative geometry effects on loosening risk.

Survival of Four Conical Implant Abutment Connections After Removal of the Abutment Screw and Simulated Cyclic Loading: An In Vitro Comparative Study.

This in vitro study evaluated the mechanical behavior of different conical connection implant systems after abutment screw withdrawal. Four conical connection systems were selected based on different conical half-angles: Ankylos (5.7°), Cowell (7.0°), Straumann (7.5°), and Astra (11.0°). In each system, 5 implants and abutments were used (n = 5). According to the recommended value, each abutment screw was torqued to settle the abutment and then withdrawn through a predesigned hole of the cemented crown. The retentiveness of the abutment was evaluated by the following mechanical testing. All specimens were subjected to cyclic loading of 20-200 N, 30°, and 4-mm off-axis to the implant axis, for 106 cycles. The pullout forces and axial displacements of the abutments were measured. The data of the Cowell system was obtained from our previous work. All groups other than Astra group, in which abutment loosened after abutment screw withdrawal, passed the cyclic loading test. Straumann group demonstrated a significantly lower pullout force (27.4 ± 21.1 N) than Ankylos (160.1 ± 41.4 N) and Cowell (183.7 ± 30.5 N) groups. All groups showed abutment rebound after screw withdrawal except Straumann group. In addition, Ankylos, Cowell, and Straumann groups demonstrated axial displacement after cyclic loading. In terms of the retentiveness of the abutment after abutment screw withdrawal examined in this study, Ankylos and Cowell groups had much higher retentiveness than Straumann group, while Astra group had none. Conical angle could be a key design parameter to make abutment screw withdrawal after conical abutment settlement feasible, but more studies must be conducted for clinical application.

Fatigue and Fracture Resistance Testing of Polyether Ether Ketone (PEEK) Implant Abutments in an Ex Vivo Chewing Simulator Model.

Polyether ether ketone (PEEK) has been introduced into implant dentistry as a viable alternative to current implant abutment materials. However, data on its physico-mechanical properties are still scarce. The present study sought to shed light on this topic utilizing an ex vivo chewing simulator model. A total of 48 titanium two-piece implants were allocated into three groups (n = 16 per group): (1) implants with PEEK abutments and an internal butt-joint connection (PBJ), (2) implants with PEEK abutments and an internal conical implant–abutment connection (PC), and (3) implants with zirconia abutments and an internal butt-joint connection (ZA). All abutments were restored with a non-precious metal alloy crown mimicking the upper right central incisor. A dynamic chewing simulation of half (n = 8) of the specimens per group was performed with 5 × 106 cycles and a load of 49 N at a frequency of 1.7 Hz with thermocycling between 5 and 55 °C. The other eight specimens served as unloaded controls. Surface roughness, implant–abutment connection microgaps (IACMs), and the titanium base–abutment interface microgaps (TAIMs) in the loaded groups were evaluated. Finally, a quasi-static loading test was performed in a universal testing machine with all samples to evaluate fracture resistance. Overall, 23 samples survived the artificial chewing process. One abutment screw fracture was observed in the PC group. The ZA group showed higher surface roughness values than PEEK abutments. Furthermore, ZA revealed lower TAIM values compared to PEEK abutments. Similarly, ZA was associated with lower IACM values compared to PBJ. Fracture loads/bending moments were 1018 N/704 N cm for PBJ, 966 N/676 N cm for PC, and 738 N/508 N cm for ZA, with no significant differences compared to the unloaded references. Artificial loading did not significantly affect fracture resistance of the examined materials. PEEK abutments were associated with better load-bearing properties than zirconia abutments, although they showed higher microgap values. PEEK abutments could, therefore, be feasible alternatives to zirconia abutments based on the present ex vivo findings resembling 20 years of clinical service.

A Finite Element Stress Analysis of a Concical Triangular Connection in Implants: A New Proposal.

Conical implant–abutment connections are popular for their stability; however, in other conditions, such as excessive force, implants and abutments can absorb all the stress. Some connections with three points of support can resist more than conical connections. In recent years, different studies has shown that the design of a connection affects its stability. The aim of this study was to analyze and compare the stresses in finite elements (FEs) in a newly proposed conical triangular connection in implants with hexagonal and conical connections. A nonlinear 3D FE parametric model was developed using SOLIDWORKS 2017®. All the connections, i.e., external and internal hexagons, morse taper, conical connection, and the new conical triangular proposal were compared when axial forces of 150, 250, and 350 N were applied to the occlusal. The maximum stress was found in the external hexagon. The maximum stress was concentrated at the level of the neck of the abutment, implant, and bone, except for the morse taper; at the level of the crown and abutment, the lowest stress occurred in the new proposal. Conclusions: The new conical triangular (CT) connection and the conical connection (CC) generate similar stress in the implant, abutment, and crown. However, the CT connection improves the CC by reducing stress at the bone level, adding an advantage to having three retention points.

Effects of tightening torque on screw stress and formation of implant-abutment microgaps: A finite element analysis

Statement of problemThe mechanical behavior of the conical connection implant with different torque levels requires evaluation. PurposeThe purpose of this finite element analysis study was to investigate the impact of abutment screw torque on the formation of microgaps at the implant-to-abutment interface of a conical connection under oblique loading. This is important because it is thought that bacteria can invade the internal implant space through the abutment-implant microgaps, causing peri-implantitis. Material and methodsThree-dimensional finite element analyses of the conical implant-abutment connection were performed by using screw torques of 20 Ncm and 30 Ncm. Oblique loads from 10 N to 280 N were applied to the prosthesis placed on the implant. The maximum von Mises stress in the abutment screw, the microgap formation process, and the critical load for bridging the internal implant space were evaluated. ResultsThe stresses in the abutment screw under oblique loading had limited sensitivity to the screw torque. However, the residual stress in the screw with a 30-Ncm torque was 35% higher than that with a 20-Ncm torque in the absence of an external load. The area in contact at the implant-to-abutment interface decreased with increasing load for both torque values. The critical load for bridging the internal implant space was 160 N for a screw torque of 20 Ncm and 220 N for a screw torque of 30 Ncm. The maximum gap size was approximately 470 μm with all the loads. ConclusionsIncreasing the screw torque can reduce the formation of microgaps at the implant-to-abutment interface. However, this will result in higher mean stress in the abutment screw, which may reduce its fatigue life and consequently that of the prosthesis. Further research is needed to evaluate the relationship between the abutment screw torque and microleakage in implant-supported restorations.

Internal Hexagon vs Conical Implant-Abutment Connections: Evaluation of 3-Year Postloading Outcomes.

Different types of internal implant-abutment connections, namely hexagon and conical, have been used for implant restoration. However, data regarding the benefits of these internal connections in terms of clinical outcomes are scarce. Accordingly, the aim of this study was to compare radiographic marginal bone loss (RMBL) and associated implant complications between implants with internal hexagon (IH) connections and those with internal conical (IC) connections. Forty-nine patients with 98 implants (2 per patient) placed in the posterior mandible were recruited. All implants were inserted in pairs into solid D2 bone according to a randomized sequence; the first patient received an IH connection implant on the mesial side, while the second patient received an IC connection implant on the mesial side. Each patient received 1 implant with an IH connection and 1 with an IC connection, placed side by side. Four months after placement, all implants were loaded with single screw-retained ceramic restorations with IH or IC connections. RMBL and complications, including implant/prosthesis failure, were recorded at the time of implant loading (baseline) and at 6, 12, and 36 months after loading. The results revealed no significant between-group differences in RMBL (P = .74), gingival bleeding on probing (P = .29), and complications (P = .32). Thus, the type of internal implant-abutment connection did not affect clinical outcomes, including RMBL and implant/prosthesis failure. Future studies should additionally evaluate long-term prosthesis-related complications, such as screw loosening and fracture, between the 2 types of internal connections.

Clinical and patient-reported outcome of implant restorations with internal conical connection in daily dental practices: prospective observational multicenter trial with up to 7-year follow-up

BackgroundThe interpretation of the results of randomized clinical trials is often questioned in relation with daily circumstances in practices. This prospective observational multicenter study was instigated to reflect the need for information in real-life situations with dental implants with internal conical implant-abutment connection (Conelog implant system). The implants were followed up at least 5-year post-loading; survival analysis (Kaplan-Meier), changes of soft tissue, and bone level over time, as well as patient satisfaction were evaluated.ResultsIn total, 130 dental implants were placed in 94 patients (64 female, 30 male). Mean age of patients was 50.4 ± 13.7. At 5-year post-loading, 104 implants in 76 patients were available for evaluation. The cumulative implant survival rate was 96.6%. After an initial bone remodeling process post-surgery (bone loss of − 0.52 ± 0.55 mm), the bone level change remained clinically stable from loading to 5-year post-loading (− 0.09 ± 0.43 mm). Patient satisfaction surveyed by questionnaire (comfort, ability to chew and taste, esthetics, general satisfaction) steadily increased towards the end. At the last study follow-up, all the patients rated their general satisfaction as either very satisfied (87.5%) or satisfied (12.5%).ConclusionThe study implants have shown to be highly effective with reliable peri-implant tissue stability over the 5 to 7 years of observation for both single tooth restorations and fixed partial dentures while used in standard conditions in daily dental practice. The results obtained are comparable with those obtained in controlled clinical trials.

WITHDRAWN: Synchrotron-based Radiography of Conical- vs. Butt-joint Implant Abutment Connections.

Ahead of Print article withdrawn by publisher.

The Effect of Two Implant-Abutment Connections on Maximum Bite Force, Prosthetic Maintenance and Peri-Implant Sulcular Fluid in Mandibular Implant Supported Telescopic Overdenture: A Split-mouth study

Purpose: The aim of this study was to evaluate and compare two different implant-abutment connections (conical and trilobe connection) in mandibular implant supported telescopic overdenture. The parameters of evaluation were the maximum bite force, prosthetic maintenance and peri-implant sulcular fluid. Materials and method: Twelve completely edentulous patients received new complete dentures. After 3 months of adaption to the new denture, 24 implants (12 implants with conical implant-abutment connection (group A) and 12 implants with trilobe implant-abutment connection (group B). The Insertion of each type of implant was randomly assigned between the two contralateral sides intraorally for each patient using a statistical software. Each patient was treated according to split mouth design. The implants were inserted in the canine region of the mandible using two-stage surgical technique and conventional loading protocol. After 3 months, implants were exposed and a telescopic overdenture was constructed. The maximum bite force, prosthetic maintenance and peri-implant sulcular fluid for each group of implants were evaluated at loading time, after 6 and 12 months.Results: There was no statistically significant difference in maximum bite force between group A and B the at loading time, but there was a statistically significant difference at 6 and 12 months follow up visits. The prosthetic maintenance events in group A were 1 event compared to 5 events in group B. There was no statistically significant difference between group A and B in the peri-implant sulcular fluid at loading time, 6 and 12 months follow up visits. Conclusion: Within the limitations of this study, it can be concluded that the conical implant- abutment connection is associated with increased maximum bite force compared to the trilobe Implant-abutment connection. Conical implant-abutment connection can provide a stable implant system with fewer prosthetic complications and maintenance services compared to trilobe implant -abutment connection.

Dynamic and static load performance of dental biomaterial systems with conical implant-abutment connections.

The stability of the implant-abutment interface is an important factor that influences load distribution on the marginal bone. In this study, three dental implants with the same connection were subjected to different dynamic loading cycles. The fracture strengths and the horizontal compatibility of implants were assessed. Eighty four implant specimens were embedded in a polyacetal cylinder as simulated bone loss of 3 mm from the implant platform. Three of the implants were used to determine the endurance limit. The other specimens were subdivided into four subgroups (n = 6): three for dynamic + static loading, and one for static loading (control group). The tests were performed by applying a compression load. The dynamic loading experiments included three different cycles with endurance upper limit loads at a frequency of 10 Hz. The differences between the fracture strength values of the implant brands were found to be statistically significant. However, there were no meaningful differences between the fracture strength values of implants of the same brand. The specimens of the DTI implant system had the lowest strength (647.9 ± 41.5N) and the SEM analysis indicated that the Implantium implant system had the shortest horizontal gaps. There was a negative correlation between the fracture strengths and size of the microgaps. The importance of these in vitro results needs to be validated by clinical trials because the loads in the mouth can be applied from various angles.

Abutment screw withdrawal after conical abutment settlement: A pilot study.

This study investigated the effects of abutment screw withdrawal after conical abutment settlement on the stability of the implant-abutment connection. Twenty implants of a conical connection system were used. Two two-piece abutment designs were used: cone only (n=10; NI) and cone plus octagonal index design (n=10; I); for each design, five samples were used with (S) and without (NS) abutment screw withdrawal before a cyclic test. Finally, four groups, namely Gr S(NI), Gr S(I), Gr NS(NI), and Gr NS(I), were included. The cyclic test included cyclic loading of 20-200N, 30°, and 4-mm off-axis to implant axis at 10Hz for 106 cycles, simulating a clinical time interval of 40months. The fatigue cycles were recorded. The axial displacement of the conical abutments during abutment settlement, screw withdrawal, and cyclic loading were measured. Abutment morphology was examined through scanning electron microscopy (SEM). Only Gr NS(NI) failed the test, indicating that without the index design and abutment screw withdrawal, and connection stability seriously deteriorated. Gr NS(I) exhibited significantly higher axial displacement into the implant after abutment settlement than did Gr NS(NI). It also exhibited continuous axial displacement into the implant after cyclic loading. SEM after cyclic testing in Gr NS(I) revealed marked burnishing on lateral edges of the index, indicating that the index design provides an antitorsional ability. Although this study has few limitations, abutment screw withdrawal is feasible in this conical implant-abutment connection system with index design.

Mechanical performance of conical implant-abutment connections under different cyclic loading conditions

ObjectivesConical implant-abutment connections are popular for its anti-bending performance; on the other hand, the torsional and axial forces also play important roles in occlusion. However, so far there were scarce studies on their effects on connection stability. Therefore, this study seeks to investigate the mechanical performance of conical connections under different cyclic loading conditions. Methods15 conical implant-abutment assembles (Cowell Medi, Busan, South Korea) were divided into 3 groups according to different cyclic loadings. In group BTA, the loading condition of the posterior occlusion was simulated (20–200 N, 30° off-axis and 4 mm eccentric to implant axis), generating a bending moment, a torsional moment, and an axial loading. In group BT, a bending moment and a torsional moment of the posterior occlusion were applied (10–100 N, 90° off-axis and 4 mm eccentric to implant axis). In group B, only a bending moment was applied (10–100 N, 90° off-axis and through implant axis). The fatigue testing machine ran at 10 Hz until failure, or to the upper limit of 106 cycles. The fatigue cycles and failure modes were recorded. Besides, the value of the torque loss of the abutment screw, the difference between initial torque and post-load reverse torque, was calculated. The data were statistically analyzed. Morphologies of the abutment conical surface were examined by scanning electron microscopy. ResultsIn group B and BTA, all samples passed the test (106 cycles). While, in group BT, all abutments generated rotation within 140 cycles, showing significant differences compared to the other two groups (p < 0.001). However, from SEM observations, both group B and BT showed marked fretting wear, indicating obvious micromotion in the connection. Whereas group BTA showed indentation of tight contact, attributed to the axial loading. In terms of the torque loss of the abutment screw, the torque loss in group BT was much more than the other two groups with statistically significant differences (p < 0.05). ConclusionOwing to the effect of the bending moment, marked fretting wear was generated in the conical connections and further led to loss of the anti-torsional ability. However, adding an axial loading could improve their anti-torsional ability significantly.

Validation of finite-element simulations with synchrotron radiography – A descriptive study of micromechanics in two-piece dental implants

State-of-the art, two-piece dental implants made from titanium alloys exhibit a complex micromechanical behavior under dynamical load. Its understanding, especially the formation of microgaps, is of crucial importance in order to predict and improve the long-term performance of such implants. Microgap formation in a loaded dental implant with a conical implant-abutment connection can be studied and quantified by synchrotron radiography with micrometer accuracy. Due to the high costs and limited access to synchrotron radiation sources, alternative approaches are needed in order to depict the microgap formation. Therefore, synchrotron radiography is used in this article to validate a simple finite element model of an experimental conical implant design. Once validated, the model is in turn employed to systematically study the microgap formation developed in a variety of static load scenarios and the influence of the preload of abutment screw on the microgap formation. The size of the microgap in finite element analysis (FEA) simulations is consistent with that found in in-vitro experiments. Furthermore, the FE approach gives access to more information such as the von-Mises stresses. It is found that the influence of the abutment screw preload has only a minor effect on the microgap formation and local stress distribution. The congruence between FE simulations and in-vitro measurements at the micrometer scale underlines the validity and relevance of the simple FE method applied to study the micromovement of the abutment and the abutment screw preload in conical implant-abutment connections under load.

Optimization of the Conical Angle Design in Conical Implant-Abutment Connections: A Pilot Study Based on the Finite Element Method.

Conical implant-abutment connections are popular for their excellent connection stability, which is attributable to frictional resistance in the connection. However, conical angles, the inherent design parameter of conical connections, exert opposing effects on 2 influencing factors of the connection stability: frictional resistance and abutment rigidity. This pilot study employed an optimization approach through the finite element method to obtain an optimal conical angle for the highest connection stability in an Ankylos-based conical connection system. A nonlinear 3-dimensional finite element parametric model was developed according to the geometry of the Ankylos system (conical half angle = 5.7°) by using the ANSYS 11.0 software. Optimization algorithms were conducted to obtain the optimal conical half angle and achieve the minimal value of maximum von Mises stress in the abutment, which represents the highest connection stability. The optimal conical half angle obtained was 10.1°. Compared with the original design (5.7°), the optimal design demonstrated an increased rigidity of abutment (36.4%) and implant (25.5%), a decreased microgap at the implant-abutment interface (62.3%), a decreased contact pressure (37.9%) with a more uniform stress distribution in the connection, and a decreased stress in the cortical bone (4.5%). In conclusion, the methodology of design optimization to determine the optimal conical angle of the Ankylos-based system is feasible. Because of the heterogeneity of different systems, more studies should be conducted to define the optimal conical angle in various conical connection designs.

Utrata kości wokół implantów z łącznikiem stożkowym lub heksagonalnym – przegląd piśmiennictwa

Based on a review of topical literature, the paper presents the results of studies concerning marginal bone loss around dental implants. The paper provides a detailed description of the process of bone loss around dental implants with conical implant-abutment connection generally used in implant prosthetic treatment. The reviewed articles reported experimental studies involving animals, as well as clinical research in humans. The results concerning bone loss around the hexagonal implant-abutment interface are cited only to provide the historical background, as implants with internal connections are generally available and currently used in oral implantology. The research on bone loss around implants conducted over the years has allowed for the assessment of the relationships between various factors that may affect the process of bone loss around implants and, consequently, influence the final result of the treatment and therapeutic success. The researchers focused on the effect of such factors as: differences in implant structure, types of surfaces, shapes and materials. In addition, bone loss is dependent on prosthetic treatment: implants may be placed at different locations in the alveolar process bone and at different levels in the hard bone; open or closed methods of healing are used; types of prosthetic restorations loaded after implantation vary, as also varies the time from implantation to loading (early or late loading), types of cementing material and cementing techniques. The paper discusses also the presence of a microgap and its colonization by microorganisms as factors that negatively affect the process of osseointegration.

Comparison of 3D displacements of screw-retained zirconia implant crowns into implants with different internal connections with respect to screw tightening

Statement of problemInternal conical implant-abutment connections without horizontal platforms may lead to crown displacement during screw tightening and torque application. This displacement may affect the proximal contacts and occlusion of the definitive prosthesis. PurposeThe purpose of this in vitro study was to evaluate the displacement of custom screw-retained zirconia single crowns into a recently introduced internal conical seal implant-abutment connection in 3D during hand and torque driver screw tightening. Material and methodsStereolithic acrylic resin models were printed using computed tomography data from a patient missing the maxillary right central incisor. Two different internal connection implant systems (both ∼11.5 mm) were placed in the edentulous site in each model using a surgical guide. Five screw-retained single zirconia computer-aided design and computer-aided manufacturing (CAD-CAM) crowns were fabricated for each system. A pair of high-resolution digital cameras was used to record the relationship of the crown to the model. The crowns were tightened according to the manufacturers’ specifications using a torque driver, and the cameras recorded their relative position again. Three-dimensional image correlation was used to measure and compare crown positions, first hand tightened and then torque driven. The displacement test was repeated 3 times for each crown. Commercial image correlation software was used to extract the data and compare the amount of displacement vertically, mesiodistally, and buccolingually. Repeated-measures ANOVA calculated the relative displacements for all 5 specimens for each implant for both crown screw hand tightening and after applied torque. A Student t test with Bonferroni correction was used for pairwise comparison of interest to determine statistical differences between the 2 implants (α=.05). ResultsThe mean vertical displacements were statistically higher than the mean displacements in the mesiodistal and buccolingual directions for both implants (P<.001). Mean displacements in all directions were statistically significant between iterations for both implants (P<.001). No statistically significant differences were found for displacements between implants at different directions and at different iterations (P>.05). ConclusionsWithin the limitations of this in vitro study, screw-retained zirconia crowns tended to displace in all 3 directions, with the highest mean displacement in the vertical direction at iteration 1. However, the amount of displacement of crowns between the 2 different implants was statistically insignificant for all directions and iterations.

The Impact of Force Transmission on Narrow-Body Dental Implants Made of Commercially Pure Titanium and Titanium Zirconia Alloy with a Conical Implant-Abutment Connection: An Experimental Pilot Study.

The purpose of this study was to visualize the mode and impact of force transmission in narrowdiameter implants with different implant-abutment designs and material properties and to quantify the displacement of the abutment. Narrow-diameter implants from two manufacturers were examined: Astra 3.0-mm-diameter implants (Astra OsseoSpeed TX; n = 2) and Straumann Bone Level implants with a 3.3-mm diameter made of commercially pure titanium (cpTi) Gr. 4 (n = 2) and 3.3-mm TiZr-alloy (n = 2; Bone Level, Straumann) under incremental force application using synchrotron radiography (absorption and inline x-ray phase-contrast) and tomography. During loading (250 N), Astra 3.0 and Bone Level 3.3- mm implants showed a deformation of the outer implant shoulder of 61.75 to 95 μm independent of the implant body material; the inner implant diameter showed a deformation of 71.25 to 109.25 μm. A deformation of the implant shoulder persisted after the removal of the load (range, 42.75 to 104.5 μm). An angulated intrusion of the abutment (maximum, 140 μm) into the implant body during load application was demonstrated; this spatial displacement persisted after removal of the load. This study demonstrated a deformation of the implant shoulder and displacement of the abutment during load application in narrow-diameter implants.

The survival of dental implants with different implant-abutment connection systems

Abstract The aim of the study was to evaluate the survival of implants with different implant-abutment connection systems, in patients who had two kinds of implants implanted. In total, 240 implants were implanted - 91 implants with conical abutment Morse connection, and 149 with an internal hexagonal connection. During the follow-up period of 3 years and 10 months, the percentage of lost implants with a conical implant-abutment connection was 1.1%. Regarding the implants with hexagonal implant-abutment connection, this figure was 0.7%. Our work shows that there is a need for further research on the survival of dental implants. In this, the influence of other factors should be explored that are related both to the specific implant treatment, as well as to socio-demographic factors

Fatigue induced changes in conical implant–abutment connections

ObjectivesBased on the current lack of data and understanding of the wear behavior of dental two-piece implants, this study aims for evaluating the microgap formation and wear pattern of different implants in the course of cyclic loading. MethodsSeveral implant systems with different conical implant–abutment interfaces were purchased. The implants were first evaluated using synchrotron X-ray high-resolution radiography (SRX) and scanning electron microscopy (SEM). The implant–abutment assemblies were then subjected to cyclic loading at 98N and their microgap was evaluated after 100,000, 200,000 and 1 million cycles using SRX, synchrotron micro-tomography (μCT). Wear mechanisms of the implant–abutment connection (IAC) after 200,000 cycles and 1 million cycles were further characterized using SEM. ResultsAll implants exhibit a microgap between the implant and abutment prior to loading. The gap size increased with cyclic loading with its changes being significantly higher within the first 200,000 cycles. Wear was seen in all implants regardless of their interface design. The wear pattern comprised adhesive wear and fretting. Wear behavior changed when a different mounting medium was used (brass vs. polymer). SignificanceA micromotion of the abutment during cyclic loading can induce wear and wear particles in conical dental implant systems. This feature accompanied with the formation of a microgap at the IAC is highly relevant for the longevity of the implants.