Effect of internal hexagonal index on removal torque and tensile removal force of different Morse taper connection abutments

Evaluation of axial displacement and torque loss of Morse-type prosthetic abutments of different angular tapers to their respective implants

STATEMENT OF PROBLEM

The biomechanical stability of the implant-prosthesis assembly and its maintenance under function is a determining factor in the success of implant prosthesis rehabilitation, but studies of different angular tapers are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the axial displacement and torque loss of prosthetic abutments with Morse-type connections of different angular tapers after thermomechanical cycling by using microcomputed tomography (µCT) and a digital torque wrench.

MATERIAL AND METHODS

Eighteen Ø3.5×11.5-mm implants were embedded in polyvinyl chloride cylinders, and the 3 different types of abutments (n=6) with angular tapers of 11.5 degrees - Alvim Cone Morse (ACM-11.5), 16.0 degrees - Helix Gran Morse (HGM-16), and 24.0 degrees - Nobel Replace Conical Connection (NRC-24) were installed with the torque recommended by the manufacturers. To calculate the axial displacements of the abutments about the implants, zirconia maxillary canine crowns were fabricated using a computer-aided design and computer-aided manufacturing (CAD-CAM) system and cemented onto the abutments. Before and after thermomechanical cycling, the assemblies were scanned using microtomography (micro-CT) to assess axial displacement, and the torque losses were calculated after the abutments were finally unscrewed. A load of 100 N, frequency of 2 Hz, and 106 cycles with temperature variation of 5 °C to 55 °C were used for the thermomechanical cycling. Analysis of variance and the Tukey post hoc test (α=.05) were used for analysis.

RESULTS

A significant difference was observed between the abutments for axial displacement, measured after thermomechanical cycling (P=.002). The ACM-11.5 abutment showed the highest mean value (134.1 ±58.7 µm), different from HGM-16 (63.3 ±26.1 µm) (P=.013) and NRC-24 (42.7 ±8.7 µm) (P=.002); the 2 latter groups were similar to each other (P=.618). For the torque losses, no significant difference was found among the abutments (P=.928), but there were significant differences for the thermomechanical cycling (before and after) (P<.001) in that the loss of torque was greater after thermocycling.

CONCLUSIONS

The smaller the taper angle of the Morse-type prosthetic abutment, the greater its axial displacement, and the thermomechanical cycling significantly reduced pretorque, regardless of taper.

Effect of abutment type and creep behavior on the mechanical properties of implant restorations in the anterior region: A finite element analysis

PURPOSE

This study aimed to assess the effect of abutment variation and creep on dental implant restorations.

MATERIALS AND METHODS

Three finite element analysis (FEA) models of implant restorations were created, which were restored by conventional one-piece abutment (CA), hybrid abutment crown (HAC), and multi-unit abutment (MUA). The contacts were considered intimate (no friction), except for implant/abutment, abutment/screw, and abutment/screw/crown (HAC) attachments. The related mechanical parameters were used to improve the authenticity of the study. Instantaneous loads and constant loads (100 s) of 130 N were applied at a 30° angle to the palatal portion of the crown. Results were qualitatively and quantitatively evaluated using the equivalent von Mises stress, micro-gap distance of the implant-abutment interface (IAI), preload changes, and safety index.

RESULTS

The stress state of each component differed depending on the restoration type, from CA and HAC to MUA. Implants and screws were the structures that suffered the most stress under instantaneous loads. Each metal structure exhibited a substantial decrease in stress during a constant loading period. The screws of the MUA abutment showed more preload loss (62.1 N) after constant loads for 100 s. MUA base produced less micro-gap (0.72 μm) at the IAI when it was compared with the CA group (0.93 μm) and HAC group (3.29 μm).

CONCLUSIONS

The abutment type influences the mechanical properties and performance of implant restorations. The creep effect decreases the maximum stress level and increases the safety factors of each structure, indicating that stress-related mechanical complications may not occur more easily.

Influence of prosthetic index structures and implant materials on stress distribution in implant restorations: a three-dimensional finite element analysis

BACKGROUND

Mechanical complications affect the stability of implant restorations and are a key concern for clinicians, especially with the frequent introduction of new implant designs featuring various structures and materials. This study evaluated the effect of different prosthetic index structure types and implant materials on the stress distribution of implant restorations using both in silico and in vitro methods.

METHODS

Four finite element analysis (FEA) models of implant restorations were created, incorporating two prosthetic index structures (cross-fit (CF) and torc-fit (TF)) and two implant materials (titanium and titanium-zirconium). A static load was applied to each group. An in vitro study using digital image correlation (DIC) with a research scenario identical to that of the FEA was conducted for validation. The primary strain, sensitivity index, and equivalent von Mises stress were used to evaluate the outcomes.

RESULTS

Changing the implant material from titanium to titanium-zirconium did not significantly affect the stress distribution or maximum stress value of other components, except for the implant itself. In the CF group, implants with a lower elastic modulus increased the stress on the screw. The TF group showed better stress distribution on the abutment and a lower stress value on the screw. The TF group demonstrated similar sensitivity for all components. DIC analysis revealed significant differences between TF-TiZr and CF-Ti in terms of the maximum (P < 0.001) and minimum principal strains (P < 0.05) on the implants and the minimum principal strains on the investment materials in both groups (P < 0.001).

CONCLUSIONS

Changes in the implant material significantly affected the maximum stress of the implant. The TF group exhibited better structural integrity and reliability.

Effect of shape and design of the internal connection of tissue-level and bone-level implants on detorque values and removal forces: An in vitro study

STATEMENT OF PROBLEM

Optimal implant stability and preventing complications such as screw loosening are paramount concerns for implant-supported prostheses. However, studies examining the influence of various internal connection designs on detorque values and removal forces, critical aspects of implant success, are lacking.

PURPOSE

The purpose of this in vitro study was to assess the impact of the shape and design of the internal connection in tissue-level and bone-level implants on the detorque value and the force required for abutment removal from the implant.

MATERIAL AND METHODS

Forty dental implants were securely mounted in 10×6×20-mm acrylic resin blocks positioned perpendicular to the surface. The implants were divided into 4 groups (n=10): bone-level SM Torx, tissue-level PSI Torx, bone-level UF Hex, and tissue-level UF Hex implants. After exposure to a dynamic loading test at 31.2 N, 2 Hz and 106 cycles, measurements were made of both detorque values and removal forces. Statistical analyses, including 1-way ANOVA with a post hoc Tukey test and Kolmogorov-Smirnov test, were conducted to assess the results (α=.05).

RESULTS

The differences in detorque values among the 4 groups were statistically similar (P=.087). In terms of removal force values, tissue-level PSI implants exhibited the highest values, while bone-level UF implants had the lowest values, with significant differences in the removal forces among the 4 groups (P<.001). Pairwise comparisons revealed significant differences among the groups (P<.001), except for the comparison between tissue-level PSI and bone-level SM implants (P=.108).

CONCLUSIONS

While detorque values remain consistent across implant types, the shape and design of the internal connection of implants has a significant impact on the removal force required for abutment detachment from the implant.

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

AIM

The 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.

METHODS

A 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.

RESULTS

Finally, 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.

CONCLUSIONS

Therefore, 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.

Retrieval of a fractured implant abutment using a modified cover screw removal instrument: A clinical report

Implant abutment fractures are an uncommon mechanical complication, and the removal of the abutment fragment and replacement with a new prosthesis is the best solution. However, successful retrieval of the fractured abutment fragment from the implant is challenging, and effective rescue kits are lacking. This clinical report describes the retrieval of a fractured implant abutment in a conical connection implant using a modified manufacturer-specific instrument.

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.

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.

Abutment mechanical complications of a Morse taper connection implant system: A 1- to 9-year retrospective study

BACKGROUND

The fracture of a Morse tapered abutment connection in an osseointegrated implant is one of the most serious mechanical complications, and it is extremely hard to deal with this complication in clinical practice.

PURPOSE

The aim of this study was to explore the cumulative mechanical complications focus on abutment of a platform switching Morse taper connection implant system after loading, and to perform a retrospective, approximately 1- to 9-year follow-up study to identify the predisposing factors.

MATERIALS AND METHODS

A total of 495 patients with 945 fitted implants were enrolled in this study with a follow-up from January 2012 to January 2020. The data of mechanical complications of the abutment, including abutment fracture (AF) and abutment screw loosening (ASL), and possible causative factors were extracted and evaluated statistically.

RESULTS

A total of 25 out of 945 (2.65%) cumulative abutment mechanical complications occurred. AF was the most common complication (n = 13, 1.38%), followed by ASL (n = 12, 1.27%). For AF, gender, type of prosthesis, abutment design, and implant diameter were identified as the causative factors. AF was mostly observed in the single crown of males in molar areas, while ASL was more likely to occur on an angled abutment than on a non-angled abutment. Moreover, the abutment with the positioning index (/X) had a higher incidence of fracture than the abutment without the positioning index (C/).

CONCLUSIONS

This study shows that the Morse taper connection is a safe abutment connection. AF occurs more frequently within single crowns in molar area of males, especially with the positioning index (/X), while ASL is more likely to occur in an angled abutment.

Effect of the prosthetic index on stress distribution in Morse taper connection implant system and peri-implant bone: a 3D finite element analysis

Background

The combination of a prosthetic index with Morse taper connection was developed, with the purpose of making prosthetic procedures more precise. However, the presence of the index may compromise the mechanical performance of the abutment. The aim of this study is to evaluate the effect of prosthetic index on stress distribution in implant–abutment-screw system and peri-implant bone by using the 3D finite element methodology.

Methods

Two commercial dental implant systems with different implant–abutment connections were used: the Morse taper connection with platform switching (MT-PS) implant system and the internal hex connection with platform matching (IH-PM) implant system. Meanwhile, there are two different designs of Morse taper connection abutment, namely, abutments with or without index. Consequently, three different models were developed and evaluated: (1) MT-PS indexed, (2) MT-PS non-indexed, and (3) IH-PM. These models were inserted into a bone block. Vertical and oblique forces of 100 N were applied to each abutment to simulate occlusal loadings.

Results

For the MT-PS implant system, the maximum stress was always concentrated in the abutment neck under both vertical and oblique loading. Moreover, the maximum von Mises stress in the neck of the MT-PS abutment with index even exceed the yield strength of titanium alloy under the oblique loading. For the IH-PM implant system, however, the maximum stress was always located at the implant. Additionally, the MT-PS implant system has a significantly higher stress level in the abutment neck and a lower stress level around the peri-implant bone compared to the IH-PM implant system. The combined average maximum stress from vertical and oblique loads is 2.04 times higher in the MT-PS indexed model, and 1.82 times for the MT-PS non-indexed model than that of the IH-PM model.

Conclusions

MT-PS with index will cause higher stress concentration on the abutment neck than that of without index, which is more prone to mechanical complications. Nevertheless, MT-PS decreases stress within cancellous bone and may contribute to limiting crestal bone resorption.

Performance of different abutment/implant joints as a result of a sealing agent

Purpose This in vitro study aimed to evaluate the effectiveness of a sealing agent in sealing the abutment/implant interface and the preload maintenance of retaining screws after mechanical cycling.Methods Six groups (n = 12) were evaluated according to the abutment/implant system (external-hexagon implant and UCLA abutments, EHU; Morse taper implant and UCLA abutments, MTU; and Morse taper implant and flexcone abutments, MTF) and the presence of an anaerobic gel sealing agent (control group, no sealing agent; experimental group, sealing agent). Toluidine blue (0.7 μL) was inserted into each implant and the abutments were attached to the implants using a digital torque wrench to evaluate the sealing of the abutment/implant interface. The specimens were tested through mechanical cycling (1 × 10⁶ cycles, 2 Hz, and 130 N). Dye release from the abutment/implant interface was analyzed using a spectrophotometer, and the reverse torque values were obtained using a digital wrench. Reverse torque and dye release data were measured after mechanical cycling and analyzed using ANOVA and Tukey's test (α =.05).Results All experimental groups showed higher reverse torque values than the control groups (P <.05). In general, the MTU and MTF experimental groups, as well as the MTF control group, showed no significant dye release at different periods (P >.05).Conclusions The use of a sealing agent improved the preload maintenance of screw-retained implant-supported prostheses. The sealing agent was effective in sealing the Morse taper connection.

Screw stability of CAD-CAM titanium and zirconia abutments on different implants: An in vitro study

BACKGROUND

Limited information is available regarding the removal torque values (RTVs) of screws of different abutment materials when used with different implants.

PURPOSE

To evaluate the effect of implant type and abutment material (zirconia; Zir and titanium; Ti) on the RTVs of abutment screws after cyclic loading.

MATERIALS AND METHODS

Internal conical connection implants (CC, OsseoSpeed TX) and modified internal conical connection implants (MCC, OsseoSpeed EV) (n = 10) were clamped in resin dies. Zir and Ti (N = 20) custom abutments were tightened to implants (20 Ncm for CC and 25 Ncm for MCC) as specified by their manufacturers. The abutments were cyclically loaded by using a sequentially increased loading protocol; 2-million cycles under 100 N, 3-million cycles under 200 N, and 2-million cycles under 300 N loads with 2 Hz. After 7 million cycles, RTVs (Ncm) were measured by using a torque gauge. The data were analyzed with ANOVA by using the restricted maximum likelihood estimation method. Tukey-Kramer adjustment was used for any significant interaction of implant-abutment pairs (α = 0.05).

RESULTS

Two CC implants, 1 with Ti and 1 with Zir abutment, fractured during cyclic loading (under 300 N loads within the 6th and 7th million cycles) and discarded for statistical analysis. Only implant type had a significant effect on RTVs (p <0.001). Screws of Ti abutments on MCC implants had significantly higher RTVs than the screws of Ti (p = 0.003) and Zir (p = 0.005) abutments on CC implants.

CONCLUSIONS

Implant type affected the RTVs, however, the RTVs were higher than the initial torque values for all groups. Screws of Ti abutments on implant, which required greater initial torque values had higher RTVs than the screws of Ti and Zir abutments on the implant that required smaller initial torque values. RTVs were similar for Zir and Ti abutment screws within each implant type.

Effect of Serrating Abutment-Implant Mating Surface on Torque Stability of Implant-Abutment Connection, Before and After Cyclic Loading

This study evaluated the effect of adding serration to the abutment-implant connection on torque maintenance before and after loading. Two implant systems with the same dimensions and connection design (internal 8° Morse taper octagon) were selected: one with nonserrated abutments (Simple line II) and the other one with serrated abutments (F & B). The removal torque value (RTV) was measured in 2 groups for each system: one group with one-piece abutments and the other group with 2-piece abutments, before and after cyclic loading (n = 10 in each group). The initial RTV of the abutment screw was measured with a digital torque meter. Each abutment received a cement-retained metal crown with 30° occlusal surface. Cyclic axial peak load of 75 ± 5 N was applied to the implants for 500 000 cycles at 1 Hz. The post-load RTV was then measured. Two-way and repeated-measures analysis of variance (ANOVA), and independent t test were applied to assess the effects of cyclic loading, connection design, abutment type, and their interaction on the percentage of torque loss (α = .05). Two-way ANOVA showed that serration of mating surfaces had a significant effect on torque maintenance before (P < .001) and after (P = .004) cyclic loading. Repeated-measures ANOVA also showed that loading had a significant effect on the torque loss percentage (P < .01). Comparison of the groups with t test showed that the torque loss of the serrated groups was lower than that of non- serrated groups. Despite the limitations of this study, the stability of the implant-abutment connection in the serrated design was higher than that of non-serrated group.

Socket Preservation Using Xenograft Does Not Impair Implant Primary Stability in Sheep: Clinical, Histological, and Histomorphometric Study

Implant primary stability, which depends mainly on the amount and quality of bone, is important for implant survival. Socket preservation aims to reduce bone volumetric changes after tooth extraction. This animal study aims to examine whether preserving a ridge by using xenograft impairs the primary stability of the implant. Eighteen artificial bone defects were prepared in 4 sheep (5- and 8-mm length). Defects were randomly grafted with xenografts: Bio-Oss (BO), Bio-Active bone (BB), or left for natural healing (control). After 8 weeks, bone biopsy was harvested and dental implants installed. During installation, peak insertion torque (IT) was measured by hand ratchet, and primary stability by the Osstell method. Histomorphometric analysis showed a higher percentage of new bone formation in the naturally healed defects compared to sites with xenograft (control: 68.66 ± 4.5%, BB: 48.75 ± 4.34%, BO: 50.33 ± 4.0%). Connective tissue portion was higher in the BO and BB groups compared to control (44.25 ± 2.98%, 41 ± 6%, and 31.33 ± 4.5%, P < .05, respectively). Residual grafting material was similar in BO and BB (7 ± 2.44%, 8.66 ± 2.1%, respectively). Mean IT and implant stability quotient (ISQ) values were not statistically different among the groups. A positive correlation was found between IT and ISQ (r = 0.65, P = 0). In conclusion, previously grafted defects with xenograft did not influence primary stability and implant insertion torque in delayed implant placement. These results may be attributed to a relatively high bone fill of the defect (∼50%) 2 months after grafting.

Comparison of CAD/CAM abutment and prefabricated abutment in Morse taper internal type implant after cyclic loading: Axial displacement, removal torque, and tensile removal force

PURPOSE

The purpose of this study was to compare computer-aided design/computer-aided manufacturing (CAD/CAM) abutment and prefabricated abutment in Morse taper internal connection type implants after cyclic loading.

MATERIALS AND METHODS

The study was conducted with internal type implants of two different manufacturers (Group Os, De). Fourteen assemblies were prepared for each manufacturer group and divided into 2 groups (n=7): prefabricated abutments (Os-P, De-P) and CAD/CAM abutments (Os-C, De-C). The amount of axial displacement and the removal torque values (RTVs) were measured before and after cyclic loading (10⁶ cycles, 3 Hz with 150 N), and the tensile removal force to dislodge the abutments was measured after cyclic loading. A repeated measures ANOVA and a pattern analysis based on the logarithmic regression model were conducted to evaluate the effect of cyclic loading on the axial displacement. The Wilcoxon signed-rank test and the Mann-Whitney test was conducted for comparison of RTV reduction% and tensile removal forces.

RESULTS

There was no significant difference between CAD/CAM abutments and prefabricated abutments in axial displacement and tensile removal force; however, significantly greater RTV reduction% after cyclic loading was observed in CAD/CAM abutments. The correlation among the axial displacement, the RTV, and the tensile removal force was not significant.

CONCLUSION

The use of CAD/CAM abutment did not significantly affect the amount of axial displacement and tensile removal force, but presented a significantly greater removal torque reduction% than prefabricated abutments. The connection stability due to the friction at the abutment-implant interface of CAD/CAM abutments may not be different from prefabricated abutment.

In vitro comparison of resonance frequency analysis devices to evaluate implant stability of narrow diameter implants at varying drilling speeds in dense artificial bone blocks

BACKGROUND

There are no studies that have assessed the implant stability quotient (ISQ) values of narrow diameter implants placed in artificial dense bone blocks at varying drilling speeds (DSs).

PURPOSE

The aim of the present in vitro experiment was to compare the performance of OSSTELL and Penguin devices to evaluate implant stability at DSs of 800 and 2000 rpm.

MATERIALS AND METHODS

A total of 360 osteotomies were created in dense artificial bone blocks at DSs of 800 and 2000 rpm. Dental implants from three manufacturers (group-1: NobelActive implants, Nobel Biocare, Yorba Linda, California; group-2: Zimmer, Eztetic-Zimmer implants, Zimmer Biomet Dental, Palm Beach Gardens, Florida; and group-3: Astra Tech implant system, Dentsply Sirona, York, Pennsylvania) were randomly placed in these osteotomies using an insertion torque of 15 Ncm (60 implants/group). Implant stability in all bone blocks immediately following implant placement was evaluated using the OSSTELL and Penguin devices. ISQ values were presented as means ± SD. Statistical significance was set at P < .05.

RESULTS

There was no significant difference in the ISQ values obtained from the OSSTELL and Penguin devices for implants in groups 1, 2, and 3. There was no significant difference when ISQ values obtained from the OSSTELL device were compared with the Penguin device for narrow diameter dental implants placed in dense bone blocks with osteotomies performed at 800 and 2000 rpm. ISQ values showed statistically significant higher values for OSSTELL compared to Penguin device.

CONCLUSION

The OSSTELL and Penguin devices are reliable for the assessment of implant stability in dense artificial bone. Implant design and site-DS does not seem to have a significant impact of implant stability in artificial dense bone blocks.

The compressive strength of implant-abutment complex with different connection designs

Background/purpose

Implant-abutment connection is the component responsible for the transmitting of occlusal force from the crown down to the implant fixture. Different connection geometric structure will lead to different mechanical performance. The purpose of this study was to compare the stability of internal hex Implant -abutment connection with internal hex with Morse taper implant-abutment connection by testing their compressive strength.

Materials and methods

This was an in vitro study. The test group and the control group had 8 specimens separately. The test group was internal hex combined with Morse taper implant connection design, and the control group was internal hex connection design. Static force was applied to the specimens at a 30° angle until failure. The testing protocol was designed according to ISO14801 regulations. We compared the compressive strength of both groups.

Results

The control group showed significantly higher compressive strength than the test group (p < 0.0001).

Conclusions

For the compressive strength of implant abutment complex, incorporating Morse taper design into internal hex connection failed to enhance its mechanical performance. According to this study, internal hex connection has higher compressive strength than internal hex connection combined with Morse taper design.

Maximum insertion torque of a novel implant-abutment-interface design for PEEK dental implants

Frequent reports attest to the various advantages of tapered implant/abutment interfaces (IAIs) compared to other types of interfaces. For this reason, a conical IAI was designed as part of the development of a PEEK (polyetheretherketone)-based dental implant. This IAI is equipped with an apically displaced anti-rotation lock with minimal space requirements in the form of an internal spline. The objective of this study was the determination of the average insertion torque (IT) at failure of this design, so as to determine its suitability for immediate loading, which requires a minimum IT of 32Ncm. 10 implants each made of unfilled PEEK, carbon fiber reinforced ("CFR") PEEK (> 50vol% continuous axially parallel fibers) as well as of titanium were produced and tested in a torque test bench. The average IT values at failure of the unfilled PEEK implants were measured at 22.6 ± 0.5Ncm and were significantly higher than those of the CFR-Implants (20.2 ± 2.5Ncm). The average IT values at failure of the titanium specimens were significantly higher (92.6 ± 2.3Ncm) than those of the two PEEK variants. PEEK- and CFR-PEEK-implants in the present form cannot adequately withstand the insertion force needed to achieve primary stability for immediate loading. Nevertheless, the achievable torque resilience of the two PEEK-variants may be sufficient for a two-stage implantation procedure. To improve the torque resistance of the PEEK implant material the development of a new manufacturing procedure is necessary which reinforces the PEEK base with continuous multi-directional carbon fibers as opposed to the axially parallel fibers of the tested PEEK compound.