Abutment Diameter Research Articles

Evaluation of crestal bone loss and MMP-8 levels around platform matched and switched implants – A quasi control study

Bone loss around an implant is an inevitable occurrence, mostly occurring during the first year of function. Various modifications have been tried to reduce this bone loss, one of them being Platform switching (PS). Present study compared the bone loss and MMP-8 levels in PISF between Platform Matched (PM) and Platform Switched (PS) implants using same implant geometry and surgical protocols and loading mechanisms in all patients. 50 implants of diameter 4.6 mm were placed crestally in selected patients. After 3 months, 25 implants were restored with platform matched abutment (Group A) and 25 with platform switched abutment (Group B). Bone loss was evaluated radiographically and MMP-8 levels were assessed in peri-implant sulcus fluid and gingival crevicular fluid of adjacent tooth by ELISA, at the time of prosthetic loading(baseline) and again after one year of loading. Prosthetic phase bone loss was calculated by subtracting baseline loss from total bone loss.After 1 year of loading, the total bone loss in platform matched group was 1.29 ± 0.39 mm and platform switched group was 1.31 ± 0.38 mm. Prosthetic phase bone loss (0.41 ± 0.14 mm and 0.48 ± 0.24 mm) and MMP-8 levels (83.6 ± 26.1 ng/ml and 78.4 ± 27.2 ng/ml) were insignificantly different between the two groups. MMP-8 levels were significantly higher in peri-implant sulcus fluid than gingival crevicular fluid in all patients at both stages. MMP-8 levels significantly correlated with bone loss. In the present study, altering the abutment diameter did not influence the extent of bone resorption within similar clinical and treatment protocols of implant supported restorations.

Marginal Bone Level and Biomechanical Behavior of Titanium-Indexed Abutment Base of Conical Connection Used for Single Ceramic Crowns on Morse-Taper Implant: A Clinical Retrospective Study.

The goal of this retrospective clinical study was to evaluate the behavior of Morse-taper indexed abutments by analyzing the marginal bone level (MBL) after at least 12 months of function. Patients rehabilitated with single ceramic crowns between May 2015 and December 2020 received single Morse-taper connection implants (DuoCone implant) with two-piece straight abutment baseT used for at least 12 months, presenting periapical radiograph immediately after crown installation were enrolled. The position of the rehabilitated tooth and arch (maxilla or mandible), crown installation period, implant dimensions, abutment transmucosal height, installation site (immediate implant placement or healed area), associated with bone regeneration, immediate provisionalization, and complications after installation of the final crown were analyzed. The initial and final MBL was evaluated by comparing the initial and final X-rays. The level of significance was α = 0.05. Seventy-five patients (49 women and 26 men) enrolled had a mean period of evaluation of 22.7 ± 6.2 months. Thirty-one implant-abutment (IA) sets had between 12-18 months, 34 between 19-24 months, and 44 between 25-33 months. Only one patient failed due to an abutment fracture after 25 months of function. Fifty-eight implants were placed in the maxilla (53.2%) and 51 in the mandible (46.8%). Seventy-four implants were installed in healed sites (67.9%), and 35 were in fresh socket sites (32.1%). Thirty-two out of these 35 implants placed in fresh sockets had the gap filled with bone graft particles. Twenty-six implants received immediate provisionalization. The average MBL was -0.67 ± 0.65 mm in mesial and -0.70 ± 0.63 mm in distal (p = 0.5072). The most important finding was the statistically significant difference comparing the values obtained for MBL between the abutments with different transmucosal height portions, which were better for abutments with heights greater than 2.5 mm. Regarding the abutments' diameter, 58 had 3.5 mm (53.2%) and 51 had 4.5 mm (46.8%). There was no statistical difference between them, with the following means and standard deviation, respectively, -0.57 ± 0.53 mm (mesial) and -0.66 ± 0.50 mm (distal), and -0.78 ± 0.75 mm (mesial) and -0.746 ± 0.76 mm (distal). Regarding the implant dimensions, 24 implants were 3.5 mm (22%), and 85 implants (78%) had 4.0 mm. In length, 51 implants had 9 mm (46.8%), 25 had 11 mm (22.9%), and 33 implants were 13 mm (30.3%). There was no statistical difference between the abutment diameters (p > 0.05). Within the limitations of this study, it was possible to conclude that better behavior and lesser marginal bone loss were observed when using abutment heights greater than 2.5 mm of transmucosal portion and when placed implants with 13 mm length. Furthermore, this type of abutment showed a little incidence of failures within the period analyzed in our study.

An Optimized Dental Implant Model Using Finite Element Analysis and Design of Experiment

Purpose: To develop, analyze, and optimize a dental implant by considering square threads and varying the thread dimensions to obtain an optimal shape. Materials and Methods: For this study, finite element analysis (FEA) and numerical optimization method were integrated to develop a mathematical model. The critical parameters of dental implants were studied, and an optimized shape was obtained using response surface method (RSM) and design of experiment (DOE). The simulated results were then compared to the predicted values under optimal conditions. Results: Using the one-factor RSM design model for the dental implant and a vertical compressive load of 450 N for testing, the optimal depth to width ratio for the thread was 0.7 in order to achieve the minimum von Mises and shear stress. Conclusion: The buttress thread was found to be the optimal shape for achieving the lowest von Mises and shear stress compared to square threads, and the thread parameters were calculated accordingly, with a thread depth 0.45 times the pitch, a width 0.3 times the pitch, and a thread angle of 17 degrees. Also, due to the constant diameter of the implant, common 4-mm diameter abutments can be used interchangeably.

Marginal Bone Maintenance and Different Prosthetic Emergence Angles: A 3-Year Retrospective Study.

The aim of the present retrospective study was to assess marginal bone changes around implants restored with different prosthetic emergence profile angles. Patients were treated with implants supporting fixed dentures and were followed for 3 years. Marginal bone levels (MBL) measured at the prosthesis installation (t0) and at the 3-year follow-up visit (t1) were considered. The MBL change from t0 to t1 was investigated. Two groups were considered: Group 1 for restorations with an angle between implant axis and prosthetic emergence profile >30°, and Group 2 for those with an angle ≤30°, respectively. Moreover, peri-implant soft tissue parameters, such as the modified bleeding index (MBI) and plaque index (PI) were assessed. Seventy-four patients were included in the analysis and a total of 312 implants were examined. The mean EA in groups 1 and 2 was 45 ± 4 and 22 ± 7 degrees, respectively. The mean marginal bone level change (MBL change) of 0.06 ± 0.09 mm and 0.06 ± 0.10 mm were, respectively, in groups 1 and 2. The difference in the MBL change between the two groups was not statistically significant (p = 0.969). The MBL change does not seem to be influenced by the emergence angle for implants with a stable internal conical connection and platform-switching of the abutment diameter.

The effects of design parameters on mechanical failure of Ti-6Al-4V implants using finite element analysis

The failure of dental implant is frequently occurred as the result of mechanical complications under daily biting forces. The long-term stability and the success of a dental implant are highly depended upon developing an implant system having high fracture resistance under cyclic biting forces. The design of implant has a crucial role in improving the fracture resistance of implant by decreasing stress concentration around the implant system. In the present study, three-dimensional (3D) models of the internally connected Ti-6Al-4V implant systems were developed in different dimensions and the failure analysis of these implants was performed under real biting forces according to ISO 14801 using Finite Element Analysis (FEA). In these models, the design parameters (implant diameter, abutment diameter, taper angle of abutment, implant wall thickness, etc.) were optimized in order to prevent the failure of implants in long-term use. The implant model exhibiting the best biomechanical behavior was determined and the stress value was decreased to 170.34 MPa (von-Mises stress) in this implant under cyclic biting loads. Besides the high fracture resistance of this model, longer service life was predicted and relatively smoother stress transmission was achieved from the implant to the bone tissues under biting forces. The implant stability was also increased by optimizing implant tightening torques. Additionally, the mechanical behavior of this implant model was investigated under different biting conditions.

The Influence of Implant Neck Features and Abutment Diameter on Hard and Soft Tissues Around Single Implants Placed in Healed Ridges: Clinical Criteria for Selection.

The clinician's selection of an implant system is influenced by many variables. Ideally, the decision should be based on scientific evidence, but often these decisions are based on economic considerations or influenced by the experience of a trusted peer. The purpose of this paper is to describe the influence of implant neck features (shape and surface) and abutment connection (diameter that matches or is smaller than the implant's platform) on hard and soft tissues around single-tooth implants placed into healed ridges with adequate hard and soft tissue thickness. In an effort to reduce the number of variables, only two-piece implants fully placed at bone level or beneath were taken into consideration. The goal is to provide additional guidance for clinicians on the decision-making and implant-selection processes.

The reliability of Anycheck device related to healing abutment diameter.

PURPOSEThe purpose of this in vitro study was to examine the reliability of the Anycheck device and the effect of the healing abutment diameter on the Anycheck values (implant stability test, IST).MATERIALS AND METHODSThirty implants were placed into three artificial bone blocks with 10 Ncm, 15 Ncm, and 35 Ncm insertion torque value (ITV), respectively (n = 10). (1) The implant stability was measured with three different kinds of devices (Periotest M, Osstell ISQ Mentor, and Anycheck). (2) Five different diameters (4.0, 4.5, 4.8, 5.5, and 6.0 mm) of healing abutments of the same height were connected to the implants and the implant stability was measured four times in different directions with Anycheck. The measured mean values were statistically analyzed.RESULTSThe correlation coefficient between the mean implant stability quotient (ISQ) and IST value was 0.981 (P<.01) and the correlation coefficient between the meant periotest value (PTV) and IST value was −0.931 (P<.01). There were no statistically significant differences among the IST values with different healing abutment diameters.CONCLUSIONThere was a strong correlation between the Periotest M and Anycheck values and between the ISQ and IST. The diameter of the healing abutment had no effect on the Anycheck values.

Effect of Abutment Design Parameter on Mechanical Properties for Dental Implant System

Abutments, as the intermediate connection between implant and crown vary on external characters decided by design parameters in order to suit for multiple clinical cases with the development of prosthodontics. The various angle, groove height (GH) and diameter of abutment brought different magnitude of stress to the dental implant system. Excessive stress concentration lead to fatigue fracture failure. Thus, in this study, parametric design and Finite Element Analysis (FEA) were combined to understand the effects of angled-abutment GH and diameter on the mechanical properties of the implant system. 30 models of abutment with varying angles (15° and 25°), diameters (4, 5 and 6mm) and GH (1, 2, 3, 4 and 5mm) were simulated and the values of Mises the equivalent stresses were analyzed by two-way ANOVA. The results demonstrated that the three design parameters had no influence on the area where stress concentration occurred and the diameter had no effect on the maximum stress while the GH had a significant influence (P<0.05).

Comparison of the Effect of Two Different Abutment Diameters on Detorque Value Using Cyclic Loading and Thermocycling

Comparison of the Effect of Two Different Abutment Diameters on Detorque Value Using Cyclic Loading and Thermocycling

The Notion of Platform-Switching in Implants: A Review

Platform switching implies to the mismatch in diameter of the abutment and that of the implant collar or in particular, use of the abutments with lesser diameter on a greater diameter implant collar. Platform switching was proposed as a process to improve long-term bone maintenance around implants. The clinical applications of platform switching are multiple, and all indicate better long-term predictability in implant therapy by allowing preservation of the peri-implant hard and soft tissue with time. In this review the influence of platform switching on various other factors affecting crestal bone loss around implants has been discussed.

Effects of abutment diameter, luting agent type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments.

PURPOSEThe aim of this study was to evaluate the effects of abutment diameter, cement type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments.MATERIALS AND METHODSSixty abutments with two different diameters, the height of which was reduced to 3 mm, were vertically mounted in acrylic resin blocks with matching implant analogues. The specimens were divided into 2 diameter groups: 4.5 mm and 5.5 mm (n=30). For each abutment a CAD/CAM metal coping was manufactured, with an occlusal loop. Each group was sub-divided into 3 sub-groups (n=10). In each subgroup, a different cement type was used: resin-modified glass-ionomer, resin cement and zinc-oxide-eugenol. After incubation and thermocycling, the removal force was measured using a universal testing machine at a cross-head speed of 0.5 mm/min. In zinc-oxide-eugenol group, after removal of the coping, the cement remnants were completely cleaned and the copings were re-cemented with resin cement and re-tested. Two-way ANOVA, post hoc Tukey tests, and paired t-test were used to analyze data (α=.05).RESULTSThe highest pulling force was registered in the resin cement group (414.8 N), followed by the re-cementation group (380.5 N). Increasing the diameter improved the retention significantly (P=.006). The difference in retention between the cemented and recemented copings was not statistically significant (P=.40).CONCLUSIONResin cement provided retention almost twice as strong as that of the RMGI. Increasing the abutment diameter improved retention significantly. Re-cementation with resin cement did not exhibit any difference from the initial cementation with resin cement.

A comparative evaluation of stress distribution between conventional and platform switched implant supported crown in different densities of bone: A three dimensional finite element analysis

Purpose: To analyze and compare the stress distribution in 3D FEA models of Implant supported mandibular crown in different densities of bone with platform switched abutment and another with a conventional matching diameter abutment.

Retention Strength of Conical Welding Caps for Fixed Implant-Supported Prostheses.

This study evaluated the retention strength of welding caps for Ankylos standard abutments using a pull-out test. Each sample consisted of an implant abutment and its welding cap. The tests were performed with a Zwick Roell testing machine with a 1-kN load cell. The retention strength of the welding caps increased with higher abutment diameters and higher head heights and was comparable or superior to the values reported in the literature for the temporary cements used in implant dentistry. Welding caps provide a reliable connection between an abutment and a fixed prosthesis without the use of cement.

Fracture Strength of Standard and Small Diameter Prosthetic Abutments for Full-Arch Implant-Supported Restorations.

This study tested the fracture strength of prosthetic abutments with different sizes and combinations to support a 5-implant milled framework with distal extension. Prosthetic abutments with different dimensions (4.8-mm diameter mini conical abutment and 3.5-mm diameter microconical abutment) were screwed to 5 threaded implants. The following groups were divided (n = 3): G1 with 5 miniconical abutments (standard size), G2 with 5 microconical abutments (small sized), G3 with a combination of 3 small sized abutments and 2 standard sized abutments, and G4 with a combination of 2 small sized abutments and 3 standard sized abutments. Standardized titanium frameworks for full-arch fixed dental prosthesis were milled with equidistant holes for each of the 5 implants and abutments. A loading point was selected at 18 mm away from both distal implants. A universal testing system was used for the fracture strength tests and load was applied at a crosshead speed of 0.5 mm/min on the previously described loading points until component fracture. Mean fracture strength for each group was statistically compared (α = 0.05). Prosthetic screws were the only fractured components for all tested groups. Mean fracture strength was: G1, 1130.22 N; G2, 1031.36 N; G3, 757.9 N; and G4 792.03 N (P < .05). All prosthetic abutments and combinations that were tested provide adequate fracture strength for clinical use. However, the combination of standard and small diameter abutments leads to lower fracture strength compared with when only standard sized prosthetic abutments were used, irrespective of the abutment diameter (4.8- or 3.5-mm).

Evaluation of periimplant bone level around implants with platform-switched abutments inserted using computed tomography-based software planning and computer-aided design/computer-aided manufacturing guided surgical template

Background: The maintenance of periimplant bone is a major factor in the prognosis of prosthetic rehabilitation supported by implants. In an attempt to improve long-term bone maintenance around dental implants, a new implant-to abutment connection referred to as “platform switching” has been proposed.1Lazzara R.J. Porter S.S. Platform switching: a new concept in implant dentistry for controlling postrestorative crestal bone levels.Int J Periodontics Restorative Dent. 2006; 26: 9-17PubMed Google Scholar Objectives: To compare the crestal bone height changes around dental implants with platform- and nonplatform-switched abutment inserted using computed tomography-based software planning and computer-aided design/computer-aided manufacturing (CAD/CAM) guided surgical template. Methods: A total of 14 implants were placed and patients were divided into two groups. Seven implants with a diameter of 4.6 mm and restored with platform-switched abutments (3.5 mm) served as the test group. Seven implants with a diameter of 4.6 mm and restored with a horizontally matching abutment diameter served as the control group. Standardised digital panoramic images were obtained for evaluation of marginal bone levels at the time of placements of prosthesis (baseline), 6 and 12 months follow-up. All implants were placed with CAD/CAM-generated surgical guides after virtual planning of implant placement. Findings: The platform-switched implants exhibited statistically significant less bone loss at time of insertion of the definitive prosthesis (0.93 ± 0.10 mm versus 1.40 ± 0.26, P < 0.05) and at one year (1.47 ± 0.15 versus 2.19 ± 0.15 mm, P < 0.05) when compared to the nonplatform-switched implants. Conclusion: It can be concluded that platform switching is capable of reducing or eliminating crestal bone loss.

Crestal Bone Preservation with Platform Switching

AbstractNew implant designs have appeared in the literature which claim that certain modifications may be helpful for maintaining crestal bone levels and consequently preserving normal soft tissue contours. Maintenance of soft tissue has been shown to depend on preservation of bone surrounding the implant. In order to achieve this goal, each step of the treatment must be managed carefully. This requires knowledge of pre-surgical treatment planning, site development, implant positioning, soft tissue management, provisionalization and prosthetic management.Placement of a smaller diameter abutment on a large diameter implant platform (platform switching) has been proposed as an effective way to control circumferential bone loss around dental implants. The purpose of this paper is to evaluate the literature from an evidence based point of view regarding implant design modifications for preserving soft and hard tissue around implants.

Stress distribution in the transitional peri-implant bone in a single implant-supported prosthesis with platform-switching under different angulated loads.

A 3D finite element analysis was conducted to evaluate and compare the stress distribution in the peri-implant bone (transitional cortical and trabecular bone) of one single implant-supported crown with platform switching and another without platform switching, under a vertical and an oblique load. Two models were created, simulating an osseointegrated implant (4×13mm, platform 4.1mm) embedded in the jaw bone. One model simulated a 4.1-mm diameter abutment connection (conventional model) and the other a 3.8-mm diameter abutment connection (platform-switching model). A crown with a Co-Cr alloy framework and feldspathic porcelain veneering was applied over the titanium abutment. Static, vertical and oblique loads (0°, 15°, 30°, 45°) with a maximum value of 150N were applied to the crown. For any inclination of the applied load, the stress values in the transitional cortical bone were lower in the platform-switching model than in the conventional model. However, the stress in the transitional trabecular bone was higher in the platform-switching model than in the conventional model. Stress values increased when the load was more oblique at the transitional cortical bone in both models and was slightly reduced at the transitional trabecular bone of the conventional model. The platform-switching technique reduces the stress at the transitional cortical bone. In both models, this stress gradually increases as the load becomes more inclined. The transitional trabecular bone shows lower stress values than the transitional cortical bone. The location of stress is similar in both models.

Comparison of the fracture resistance of dental implants with different abutment taper angles

To investigate the effects of abutment taper angles on the fracture strength of dental implants with TIS (taper integrated screwed-in) connection. Thirty prototype cylindrical titanium alloy 5.0mm-diameter dental implants with different TIS-connection designs were divided into six groups and tested for their fracture strength, using a universal testing machine. These groups consisted of combinations of 3.5 and 4.0mm abutment diameter, each with taper angles of 6°, 8° or 10°. 3-Dimensional finite element analysis (FEA) was also used to analyze stress states at implant–abutment connection areas. In general, the mechanical tests found an increasing trend of implant fracture forces as the taper angle enlarged. When the abutment diameter was 3.5mm, the mean fracture forces for 8° and 10° taper groups were 1638.9N±20.3 and 1577.1N±103.2, respectively, both larger than that for the 6° taper group of 1475.0N±24.4, with the largest increasing rate of 11.1%. Furthermore, the difference between 8° and 6° taper groups was significant, based on Tamhane's multiple comparison test (P<0.05). In 4.0mm-diameter abutment groups, as the taper angle was enlarged from 6° to 8° and 10°, the mean fracture value was increased from 1066.7N±56.1 to 1241.4N±6.4 and 1419.3N±20.0, with the largest increasing rate of 33.1%, and the differences among the three groups were significant (P<0.05). The FEA results showed that stress values varied in implants with different abutment taper angles and supported the findings of the static tests. In conclusion, increases of the abutment taper angle could significantly increase implant fracture resistance in most cases established in the study, which is due to the increased implant wall thickness in the connection part resulting from the taper angle enlargement. The increasing effects were notable when a thin implant wall was present to accommodate wide abutments.

The effect of implant and abutment diameter on peri-implant bone stress: A three-dimensional finite element analysis

Introduction: Load transfer mechanisms from the implant to surrounding bone and failure of osseointegrated implants are affected by implant geometry and mechanical properties of the site of placement as well as crestal bone resorption. Estimation of such effects allows for a correct design of implant geometry to minimize crestal bone loss and implant failure. Objectives: To evaluate the effect of implant and abutment diameter on stress distribution in the peri-implant area. Materials and Methods: Three-dimensional finite element models created to replicate completely osseointegrated endosseous titanium implants and were used for the purpose of stress analysis. Two study groups that consisting of a regular platform (RP) group and narrow platform (NP) group were used with a standard bone density and loaded using the ANSYS Workbench software to calculate the von Mises and Principal (maximum tensile and minimum compressive) stress. Results: The von Mises, compressive, and tensile stresses in the peri-implant bone were lower in the RP model compared to the NP model. Conclusion: RP model yielded a positive result with regard to lowering of peri-implant bone stress levels, in healthy as well as compromised bone qualities when compared to NP designs.

EFFECT OF IMPLANT PLATFORM SWITCHING ON STRAIN DEVELOPED AROUND IMPLANTS WITH STRAIGHT AND ANGLED ABUTMENTS

Statement of the problem. Implant placement in an ideal position where stresses are transmitted vertically along the long axis of the implant rarely if ever coincides with the most esthetically pleasing position dictated by prosthetic planning. This situation could be dealt with by placing the implant at an angle in the most favourable position surgically and using angled abutments to compensate for the deviation from the previously planned prosthetic site of the final restoration. This may lead to excessive stresses on the inclined side of the implant which could cause bone resorption. Purpose. The aim of this study was to evaluate the effect of implant platform switching on strain developed around implants with straight and angled abutments. Materials and Methods. Twenty root-form titanium implants were inserted in epoxy resin blocks. According to the direction of implant insertion in the epoxy resin block, the twenty implants were divided into two main groups: Group I: (n=10) Straight implants with straight abutments. Group II :( n=10) Inclined implants with angled abutments (15 degrees). Each group was sub-divided into two sub-groups according to the abutment diameter in relation to the implant diameter: Sub-group A :( n=5) 4.5 mm diameter Implants received 4.5 mm diameter abutments. Sub-group B:(n=5) 4.5 mm diameter Implants received smaller 3.75 mm diameter abutments (platform switching). The 20 implant abutments received Ni-Cr full metal crowns. The blocks were trimmed to 1mm thickness around the implant then each sample received four strain gauges to represent the mesial, distal, buccal and lingual surfaces around the implant. A computerized universal testing machine was used for loading the implants by 300N, at a rate of 1 N/Sec. The load was applied progressively starting from zero to 300 N during which readings from the strain meter were recorded on the computer. Results. It was found that Group II (Angled abutments) with matching diameter Sub-group A showed statistically significantly (P ≤ 0.05) highest mean micro-strains (435.1± 215.7) followed by Group I (Straight abutment) with matching diameter Sub-group A (346.2 ± 175.3) followed by Group II (Angled abutments) with platform switching Sub-group B (307.1 ± 135.0). Group I (Straight abutment) with platform switching Sub-group B showed statistically significantly lowest mean micro-strains (239.0± 165.4) . Conclusions. Straight implants with straight platform-switched abutments were associated with the least micro-strain values.