Implant-abutment Connection Research Articles

3D EVALUATION OF MICROGAPS AT THE IMPLANT-ABUTMENT CONNECTION BEFORE AND AFTER THERMODYNAMIC CYCLING.

To analyze the microgap changes between hybrid-abutment crowns made of two materials and three internal taper connec9on implants with different connection designs before and after thermodynamic loading. A total of 30 implants-10 each of Straumann Bone Level Implant-RC (STR); GC AADVA Implant (AAD); and Astra-Tech OsseoSpeed EV (AST)-were included in this laboratory study. Each implant had an internal taper connection, but their designs were slightly different. Five hybrid-abutment crowns were fabricated using a lithium disilicate ceramic (LD), and five were fabricated using polymethylmethacrylate (PMMA) with CAD/CAM technologies for each implant system, providing six sample groups STR-LD, AAD-LD, AST-LD, STR-PMMA, AAD-PMMA, and ASTPMMA. The microgap volume was measured using micro-CT images obtained before and after thermodynamic loading equivalent to 4 months of clinical use. Student t test, one-way ANOVA, and Tukey test were used for comparisons. The greatest microgap volume increase was recorded (3.405% ± 1.567%) in the AST-LD group, and the lowest increase (0.45% ± 0.373%) was in the STR-PMMA group. A statistically significant difference in microgap increase was not detected among PMMA and LD groups: for STR-LD/STR-PMMA (t test: P = .273); for AAD-LD/AAD-PMMA (t test: P = .374); and for AST-LD/AST-PMMA (t test: P = .268). However, the difference in the microgap increase between the different implant systems was statistically significant. The microgap between hybrid-abutment crowns and implants increased after short-term thermodynamic cycling. Hybrid-abutment crowns with different elastic modulus showed similar microgap increase. The geometric shape of the connection influenced the microgap increase.

Eleven- to fifteen-year outcome for two-piece implants with an internal tube-in-tube connection: a cross-sectional analysis of 245 implants.

The aim of this retrospective study was to evaluate the outcomes of a two-piece implant system with a tube-in-tube internal connection after up to 15years of clinical use. A retrospective follow-up examination of patients treated with internal tube-in-tube implants between 2003 and 2006 was conducted. The implant survival rates, peri-implant conditions (marginal bone loss, bleeding on probing, plaque index, probing depth), and technical complications were determined. In total, 312 dental implants were placed in 152 patients. Of the original 152 patients enrolled, 245 implants in 112 patients were available for a follow-up evaluation after 11 to 15years (mean observation time, 12.9 ± 1.1years). The overall implant survival rate was 93.9%. Outcomes for MBL (1.49 ± 1.23mm), PI (24.3 ± 22.2%), BOP (18.3 ± 28.7%), and PD (2.74 ± 1.21mm) were observed. Selected parameters (time after implant surgery, smoking habits, bone augmentation (GBR)) showed an influence on MBL and PD. The internal tube-in-tube implant system showed favorable long-term results. The correlation of MBL and PD with the patient-specific factor smoking habit is in accordance with other studies. Camlog Root-Line implants with a tube-in-tube implant-abutment connection and a 1.6-mm polished neck configuration have demonstrated favorable long-term outcomes in daily clinical practice. However, it is important to note that these implants are no longer available on the market.

Early dental implant failure associated with postoperative infection: A retrospective 21‐year study

AbstractAimThere are several causes related to early dental implant failure, and infection is one of the most common risk factors in the initial phase of osseointegration. The aim of this retrospective study was to evaluate early dental implant failure associated with postoperative infection and identify the factors associated with such failure.Materials and MethodsA retrospective study was conducted, and the main predictor variable was early dental implant failure. The main cause of failure was postoperative infection, including factors related to early loss due to infection, such as installation site, type of implant–abutment connection used and presence of previous bone graft. Appropriate descriptive and multivariate statistics were computed, and Chi‐square tests and logistic binary regression were used to identify the factors related to early failure.ResultsThe study sample consisted of 1674 patients, who had 4886 implants installed and were selected for statistical analysis. A total of 3219 implants were inserted in women and 1667 in men. The main outcome variable was early implant failure due to infection. There were 164 early failures in the study, accounting for 3.3% of the sample. Of those failures, 35 were a consequence of postoperative infection, resulting in 21.34% of early failures. The main risk factor identified was the presence of infection (odds ratio [OR] = 53.67, with 95% confidence interval [CI]).ConclusionsThe study's results suggest that infection may be considered a risk factor for early failure of osseointegrated implants.

Silver coating on dental implant-abutment connection screws as potential strategy to prevent loosening and minimizing bacteria adhesion.

Introduction: One of the main problems for the long-term behavior of dental implants are loosening of the implant-abutment connection screws and bacterial infiltration. The aim of this work is to increase the screw fixation by silver coating, providing superior mechanical retaining and antibacterial effect. Methods: Eighty dental implants with their abutments and screws have been studied. Twenty screws were not coated and were used as a control while the rest of screws were silver coated by sputtering, with three different thickness: 10, 20 and 40μm and 20 screws per each thickness. Coating morphology and thickness were determined by scanning electron microscopy using image analysis systems. The screws were tightened for each of the thicknesses and the control with two torques 15 Ncm and 20 Ncm and tested under mechanical fatigue simulating oral stresses up to a maximum of 500,000 cycles. The remaining torques at different cycles were determined with a high-sensitivity torquemeter. Cell viability assays were performed with SaOs-2 osteoblasts and microbiological studies were performed against Streptococcus gordonii and Enterococcus faecalis bacteria strains, determining their metabolic activity and viability using live/dead staining. Results: It was observed a decrease in torque as cycles increase. For a preload of 15 Ncm at 100,000 cycles, the loosening was complete and, for 20 Ncm at 500,000 cycles, 85% of torque was lost. The silver coatings retained the torque, especially the one with a thickness of 40μm, retaining 90% of the initial torque at 500,000 cycles. It was observed that osteoblastic viability values did not reach 70%, which could indicate a slight cytotoxic effect in contact with cells or tissues; however, the screw should not be in direct contact with tissue or living cells. Silver coating induced a significant reduction of the bacteria metabolic activity for Streptococcus gordonii and Enterococcus faecalis, around 90% and 85% respectively. Discussion: Therefore, this coating may be of interest to prevent loosening of implant systems with a worthy antibacterial response.

Effect of repeated autoclaving on implant abutments from genesis and bredent dental implant systems.

The effect of repeated autoclaving on the implant-abutment connection of titanium abutments from Genesis and Bredent dental implant systems is of interest to dentists. 40 screw-retained titanium implant abutments from Genesis and Bredent were divided into four groups of ten. Each implant was secured with an abutment using screws. Abutments were prepared for the first 30-minute autoclave cycle at 121°C. After the first autoclave cycle, the abutments were fitted onto their implant systems and examined under a scanning electron microscope (SEM). Intra-group comparison between marginal gaps of Genesis and Bredent groups at 1st autoclave and 2nd autoclave observed statistically significant differences respectively (p<0.05). Genesis group showed highest mean values for buccal and mesial sides (2.7) and lingual and distal sides (2.8) with statistically significant differences. Marginal gap and surface roughness increased with autoclaving for both Genesis and Bredent group of implant abutment systems.

Evaluation of stress distribution in and around dental implants using three different implant-abutment interfaces with platform-switched and non-platform-switched abutments: A three-dimensional finite element analysis.

A key factor for the success or failure of an implant is how the stresses are transferred to the surrounding bone. The implant‒abutment connection (IAC) is paramount for implant success. The purpose of this finite element analysis (FEA) study was to evaluate the stress distribution in and around three different implant‒abutment interfaces with platform-switched and platform-matched abutments using the finite element method (FEM). Three distinct types of IAC were selected: tri-channel internal connection, conical connection, and internal hex connection. Six models were generated, three in platform-switched and three in non-platform-switched configuration. Computer-Aided Three-Dimensional Interactive Application (CATIA) V5 R20 software was used to generate virtual models of the implants and the mandible. The models were transferred to Analysis of Systems (ANSYS) 15.0 software, in which the models were meshed and underwent FEA. On the crestal bone, the highest von Mises stresses in platform-switched abutments were noticed in the internal hex implant‒abutment system (370 MPa), followed by the tri-channel implant‒abutment system (190 MPa) and conical implant‒abutment system (110 MPa). On the implant and the abutment screw, the highest von Mises stresses were observed in the internal hex implant‒abutment system, followed by the conical implant abutment system and tri-channel implant‒abutment system. Platform-switched implants had a more favorable stress distribution on crestal bone. Within the constraints of the current study, the internal hex connection exhibited the highest stress. In contrast, the conical abutment connection with platform switching configuration had more favorable stress distribution in crestal bone than other implant abutment systems.

Comparative Analysis of Microbial Leakage in Implant Recess of Three Different Internal Implant Abutment Connections: An In Vitro Study

Comparative Analysis of Microbial Leakage in Implant Recess of Three Different Internal Implant Abutment Connections: An In Vitro Study

Assessment of Microgap and Bacterial Leakage of Two Types of Internal Implant-Abutment Union.

The current research was done to assess microbial seepage of two types of internal implant-abutment connections. Twenty dental implants are categorized into two groups. Group A fixtures with an internal hexagonal geometry and group B fixtures with a tri-lobe internal connection. All implant-abutment assemblies underwent a three-week incubation period at 37°C in sterile tubes containing 5 mL of Staphylococcus aureus broth culture. Through the use of Gram stain and biochemical processes, the resultant colonies were recognized. The mean Log10 colony forming unit (CFU) in group A was 8.4 and in group B was 7.2. The variation between both groups was found to be considerable (P < 0.05). Microgap was more in group B compared to group A. Bacteria may infiltrate the small area between the implant and the abutment. Compared to dental implant fixtures with a tri-lobe internal connection, there was a noticeably higher Log10 CFU in dental implant fixtures with an internal hexagonal geometry.

Crestal and Subcrestal Placement of Morse Cone Implant-Abutment Connection Implants: An In Vitro Finite Element Analysis (FEA) Study.

The issue of dental implant placement relative to the alveolar crest, whether in supracrestal, equicrestal, or subcrestal positions, remains highly controversial, leading to conflicting data in various studies. Three-dimensional (3D) Finite Element Analysis (FEA) can offer insights into the biomechanical aspects of dental implants and the surrounding bone. A 3D model of the jaw was generated using computed tomography (CT) scans, considering a cortical thickness of 1.5 mm. Subsequently, Morse cone implant-abutment connection implants were virtually positioned at the model's center, at equicrestal (0 mm) and subcrestal levels (-1 mm and -2 mm). The findings indicated the highest stress within the cortical bone around the equicrestally placed implant, the lowest stress in the -2 mm subcrestally placed implant, and intermediate stresses in the -1 mm subcrestally placed implant. In terms of clinical relevance, this study suggested that subcrestal placement of a Morse cone implant-abutment connection (ranging between -1 and -2 mm) could be recommended to reduce peri-implant bone resorption and achieve longer-term implant success.

Comparison of Screw Loosening and Fracture Resistance in Different Hybrid Abutment Crown Restorations After Thermomechanical Aging.

To investigate the screw loosening and fracture resistance of different hybrid abutment crown restorations after thermomechanical aging. Restorations were produced from zirconia, lithium disilicate, and hybrid ceramics with a CAD/CAM system (n &#61; 10). Restorations and titanium bases (Ti-bases) were cemented, and the abutment screws were torqued to 30 Ncm. They were retorqued after 10 minutes, and then the removal torque values (RTVs) were measured. After 250,000 and 500,000 cycles of thermomechanical aging were completed, the RTVs were measured again, and removal torque loss (RTL) ratios were calculated. The specimens were subjected to a fracture resistance test after 750,000 cycles of thermomechanical aging, and the load at failure was recorded as the fracture resistance (N). The results were statistically analyzed (α &#61; .05). Aging was effective on the RTVs and RTL ratios (P < .001). The highest RTV was observed before aging; however, the RTVs significantly decreased and RTL ratios significantly increased after aging (P < .05). The fracture resistance values significantly differed among the ceramic materials. All lithium disilicate and hybrid ceramic specimens showed restoration fracture and most of the zirconia specimens showed Ti-base-related failure. Hybrid abutment crowns made of zirconia, lithium disilicate, and hybrid ceramics can withstand the average occlusal forces in the molar region; however, the ceramic type may affect the failure type. Retightening of the abutment screws after 10 minutes following the first tightening and annually may be beneficial to prevent the adverse effects of screw loosening on the integrity of the implant-abutment connection.

The mechanical and clinical influences of prosthetic index structure in Morse taper implant-abutment connection: a scoping review

AimThe implant-abutment connection is a crucial factor in determining the long-term stability of dental implants. The use of a prosthetic index structure in the Morse taper implant-abutment connection has been proposed as a potential solution to improve the accuracy of this connection. This study aimed to provide a scoping review of the mechanical and clinical effects of the prosthetic index structure in the Morse taper implant-abutment connection.MethodsA systematic scoping review of articles related to "dental implants," "Morse taper," and "index" was conducted using PubMed/MEDLINE, Web of Science, Cochrane, and Scopus databases, as well as a comprehensive literature search by two independent reviewers. Relevant articles were selected for analysis and discussion, with a specific focus on investigating the impact of prosthetic index structure on the mechanical and clinical aspects of Morse taper implant-abutment connections.ResultsFinally, a total of 16 articles that met the inclusion criteria were included for data extraction and review. In vitro studies have demonstrated that the use of a prosthetic index structure in the Morse taper implant-abutment connection can affect stress distribution, biomechanical stability, and reverse torque values, which may reduce stress within cancellous bone and help limit crestal bone resorption. However, retrospective clinical studies have shown that this structure is also associated with a higher risk of mechanical complications, such as abutment fracture and abutment screw loosening.ConclusionsTherefore, the clinical trade-off between preventing crestal bone resorption and mechanical complications must be carefully considered when selecting appropriate abutments. The findings suggest that this structure can improve the accuracy and stability of the implant-abutment connection, but its use should be carefully evaluated in clinical practice.

Biomechanical Analysis of Titanium Dental Implants in the All-on-4 Treatment with Different Implant-Abutment Connections: A Three-Dimensional Finite Element Study.

The type of implant-abutment connection is one of the factors influencing the distribution of occlusal forces. This study aims to investigate the biomechanical performance of the mandibular all-on-4 treatment with different implant-abutment connections. Two connection types with 30° abutments and 18-mm implant fixtures were chosen for the posterior implants of the all-on-4 assembly. For the external hexagon connection (EHC) group, the implants with 4 mm in diameter were used. For the internal hexagon connection (IHC) group, we selected implants with 4.3 mm in diameter. A vertical force of 190 N was applied to the cantilever region. The FEA results indicated that the most stressed region in the two groups was prosthetic screws, followed by multi-unit abutments (MUAs). The lowest values of von Mises stress were both observed on the bone. The peak stress value of the implant screw and implant fixture in the EHC group were 37.75% and 33.03% lower than the IHC group, respectively. For stress distribution patterns, the load force tended to be concentrated at locations where components were interconnected. The EHC and IHC are clinically durable under the tested loading conditions, but the prosthetic screws and MUAs can be the weak point on the posterior implant within the mandibular all-on-four assembly. The peak stress values of implant screw and implant fixture in the EHC groups were lower than the IHC group.

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.

Fabrication of a reverse-engineered custom scan body as a digital solution for recording implant position: A dental technique

A technique for the reverse engineering of the implant-abutment connection to fabricate a custom scan body is described. The implant-abutment connection was designed using the exocad software program, the scan body with screw channel was designed with the Blender software program, and the file was either 3-dimensionally printed in definitive tooth-colored resin with ceramic filler material or milled in polyetheretherketone (PEEK). This technique offers an accurate, cost-effective digital solution for implant optical scanning that can replace prefabricated scan bodies that may not be available for all implants. (J Prosthet Dent xxxx;xxx:xxx-xxx).

Evaluation of different debridement strategies for implant-abutment connections: An in vitro study

Statement of problemTechnical complications, including abutment fracture, are a clinical reality. After retrieving failed components, re-establishing a reliable implant-abutment connection is essential, but recommendations on how to clean the interface are lacking. PurposeThe purpose of this in vitro study was to evaluate different clinical debridement strategies for removing titanium powder from an implant-abutment interface with regard to their efficacy and associated risk of damaging the interface. Material and methodsSpecimens (n=5) were assembled from previously cut implant halves, which were then contaminated by placing titanium powder inside the implant-abutment connection. Activated rinsing, airflow, and an ultrasound scaler, as well as combinations thereof, were then used to clean the implant-abutment connections. Both parts of each specimen were rated under a light microscope with respect to contamination and damage. In addition, abutments were placed in intact implants (n=10), which had previously been contaminated and cleaned, to record torque curves and abutment stability. Statistical analysis of ratings was based on Kruskal-Wallis tests and the Nemenyi All Pairs test with single-step P value correction, while abutment stability and torque were analyzed using analysis of variance and Tukey HSD tests (α=.05). ResultsErythritol as an abrasive medium led to significantly greater contamination than the scaler (P=.002), activated rinsing (P=.021), and airflow with sodium bicarbonate combined with either conventional (P=.002) or activated rinsing (P=.007). Greater damage was also observed with erythritol because of accumulations of the abrasive media, while scratches were seen after scaler application. Airflow using sodium bicarbonate in combination with activated rinsing showed the lowest level of damage (versus scaler P=.030). Using conventional (P=.010) or activated (P=.029) rinsing, airflow treatment led to a significant reduction in contamination. The scaler led to a significant decrease in abutment stability (P=.048), while activated rinsing and the combination of airflow and activated rinsing did not significantly affect abutment stability. Abutments placed in implants previously contaminated and cleaned required greater torque as compared with original implants (versus activated rinsing, P=.009). ConclusionsActivated rinsing constituted the best technique for cleaning implant-abutment connections. Cleaning efficiency can be enhanced with airflow using sodium bicarbonate as an abrasive medium.

EBD spotlight: Bio-mechanical efficiency of different implant-abutment connections

EBD spotlight: Bio-mechanical efficiency of different implant-abutment connections

Systemic observation and measurement of microgap formation in dental implant–abutment connection interface under fatigue

Abstract Today, a variety of implant designs with different attachment types are widely used in dental implant systems to eliminate connection problems. However, there are still design issues that can significantly affect the long-term success of dental implants. One of these problems is the formation of a microgap in the abutment–implant interface, which can lead to abutment screw loosening, screw fracture, and abutment fracture under masticatory loading. In this in vitro study, the effects of gingival height, dental implant diameter, and abutment type (solid, digital, and ball) on microgap formation were observed after repetitive fatigue tests using an experimental design. After the tests, the optimal design factors were determined to minimize microgap formation. According to the results of the experimental design, the abutment type was found to be the most influential parameter on microgap formation. An implant diameter of 4.1 mm, the smallest gingival height of 0.5 mm, and a digital attachment combination were identified as the optimal design parameters based on the statistical approach (R 2 = 85.3 %).

Insertion Torque (IT) and Implant Stability Quotient (ISQ) Assessment in Dental Implants with and without Healing Chambers: A Polyurethane In Vitro Study

Primary Stability (PS) depends on different factors, such as bone structure (quality and density), implant characteristics (macro and micro), and the relationship between thread shape and implant insertion hole size. PS is crucial for the prognosis and success of dental implants. The use of healing chambers, which create empty spaces between the implant and peri-implant bone, helps reduce the risk of compressive bone necrosis. High Insertion Torque (IT) values could potentially lead to the deterioration of the implant-abutment connection. However, the optimal implant macro-structure and IT values remain unknown. In this study, implants with healing chambers (Test) and without (Control) were inserted into polyurethane blocks with densities of 10, 20, 30, and 40 pounds per cubic foot (PCF). In blocks with densities of 30 and 40 PCF, Control implants had significantly higher IT values than Test implants. Additionally, Control implants exhibited significantly higher Removal Torque (RT) values than Test implants, but only in the 30 PCF density block (p &lt; 0.0001). However, no differences were found between the implants in the 10, 20, and 40 PCF density blocks. Similarly, no significant differences were observed in the Implant Stability Quotient (ISQ) values between the Test and Control implants. The results of the present study confirm that adding healing chambers to the macro-structure of dental implants can significantly reduce IT values without affecting ISQ values. This suggests the potential for avoiding compression and damage to peri-implant bone while maintaining consistent levels of PS.

Prosthetic rehabilitation in the Posterior Mandible with Tissue Level Implant: A Case Report

Implant is becoming the most appropriate option nowadays for replacement of single or multiple missing teeth which offers the predictable long-term results. Continuous innovations in implant design and approaches for placement have been proposed to achieve good osseointegration, esthetics and predictable soft tissue contour. Soft tissue level (STL) implants are placed trans-mucosally with platform away from alveolar bone crest so the microbial deposits in the micro-gap at implant abutment connection has less effect on alveolar bone. This type of implant has a rough surface placed subcrestally to facilitate osseointegration and a polished coronal part to facilitate soft tissue adaptation. This case report highlights about soft tissue level implant, its advantages and clinical success on replacing single missing posterior tooth.

Effect of internal connection type and screw channel angle on the screw stability of anterior implant-supported zirconia crowns.

To investigate the effect of implant-abutment connection and screw channel angle on screw stability by comparing a newly introduced and an established connection, before and after cyclic loading. Implants (N = 44) with Torcfit (TF) or Crossfit (CF) connection were divided to be restored with a straight (CFS and TFS) or an angled screw access channel (CFA and TFA) titanium-base abutment (n = 11). CFA and TFA received screw-retained crowns, whereas CFS and TFS received hybrid zirconia abutments and cement-retained crowns. The initial torque value (ITV) of each complex (ITVI ) and removal torque value (RTV) after 24 h (RTVI ) were measured. Screws were replaced with new ones, ITVs were recorded again (ITVF ), and crowns were cyclically loaded (2.4 million cycles, 98 N) to measure RTVs again (RTVF ). Percentage torque loss was calculated. Data were analyzed (α = 0.05). ITVs were similar among groups (p ≥ .089). CF led to higher RTVs (p ≤ .002), while CFS had higher RTVI than CFA (p = .023). After 24 h, CFS had lower percentage torque loss than TF, while CFA had lower percentage torque loss than TFA (p ≤ .011). After cyclic loading, CF led to lower percentage torque (p < .001). The implant-abutment connection affected the removal torque values. However, no screw loosening occurred during cyclic loading, which indicated a stable connection for all groups. Screw access channel angle did not affect screw stability after cyclic loading.