Thread Design Research Articles

Impact of Implant Diameter on Success and Survival of Dental Implants: An Observational Cohort Study

Narrow-diameter implants (NDIs) can be inserted instead of standard dental implants (SDIs) in sites with limited space and bone availability. The aim of this study was to evaluate the effect of implant diameter on peri-implant bone, attached mucosa, and on the associated probability of implant success and survival. The implants with progressive thread design and platform switching (Ankylos®, Dentsply Sirona; Mannheim, Germany) investigated were identified retrospectively and assigned to two groups based on their diameter: 3.5 mm (NDIs) and 4.5 mm (SDIs). Peri-implant bone loss was analyzed based on available radiographs. Descriptive and implant-associated factors were gathered from patient files. Data were statistically analyzed using the Kolmogorov–Smirnov–Lilliefors test and regression analyses. The level of significance was p ≤ 0.05. Results: In total, data for 415 implants in 194 patients were included in the study. Ten-year survival was 95.8% (NDIs) and 91.1% (SDIs). Implant diameter had no significant effect on peri-implant crestal bone loss (p = 0.098) or on the width of the attached gingiva (p = 0.052). Survival and success rates of NDIs were like or slightly better than those of SDIs. Because implant diameter had no effect on peri-implant tissue, NDIs can be recommended in selected cases.

Influence of dental implant/mini-implant design on stress distribution in overdentures: a systematic review.

Critically evaluate the existing literature and answer the question, "Does the dental implant/mini-implant design influence the stress distribution in prosthetic overdentures according to finite element analysis?". This systematic review was registered in the Open Science Framework (osf.io/2bquj) and followed the PRISMA protocols. The custom search strategy was applied to 4 databases. In vitro experimental studies that evaluated the influence of dental implant/mini-implant design on stress distribution in overdentures by FEM, without time and language restrictions, were included. The selection process was carried out in two stages by two reviewers independently. Risk of bias analysis was performed by a checklist of important parameters. Sixty articles were evaluated by their title and abstract, four were selected for full reading, three were relevant, and nine were included by additional search. The 12 studies have a low risk of bias. The meta-analysis could not be performed due to the heterogeneity of the data (implant type, design variation, load intensity, and direction). It can be inferred from the evaluated literature that design modifications influence the stress distribution, but as the FEM presents limitations inherent to the in vitro study, clinical trials are necessary to infer the effectiveness of the modifications. It should be noted that there is no consensus on which is the best thread design and that implants with a very narrow diameter are subject to the highest stress concentration.

Improving dental implant stability by optimizing thread design: Simultaneous application of finite element method and data mining approach

Lack of knowledge regarding the optimal design of thread configuration in dental implants, which can offer a satisfactory level of stability in the implant-bone construct, is a significant challenge in the field of dental biomechanics. The purpose of this finite element analysis study was to identify the optimal thread design by investigating the effects of thread parameters such as thread depth (TD), thread width (TW), and thread pitch (TP), as well as upper (α) and lower (β) thread angles, on the maximum principal stress in cancellous and cortical bone, maximum von Mises stress in the dental implant, and maximum shear stress at the implant-bone interface. A finite element model of an alveolar bone segment with a dental implant was developed. The Latin hypercube sampling method was used to generate a dataset of virtual experiments, which were analyzed by using the decision tree method to identify suitable thread designs that minimize mechanical stimuli. Additionally, the effectiveness of thread parameters on stress levels in the bone, implant, and their interface were assessed. The results of this study, verified by comparison with previous literature, indicated that TD, TW, and upper thread angle were the most effective parameters in promoting implant stability. By analyzing the decision trees, optimum ranges for all the thread parameters were determined as follows: 0.25<TD<0.34, 0.25≤TW≤0.28, 0.8≤TP≤0.88, 66.2≤α≤80, and β≤65.4, which led to the V-shape thread design.

Optimization and innovative design of dental implants under dynamic finite element analysis

ABSTRACT Dental implants’ usage life and strength are critical factors for implant patients. This paper examines the optimization of dental implant threads by modifying the C-Tech implant system model to ascertain thread design’s impact on micromotion through finite element analysis (FEA). The fundamental measurements of the redesigned C-Tech implant system are established by dynamic (FEA). Six implant parameters are chosen as the control factors to be advanced. Experimental simulations are built using a uniform design (UD) method. The dynamic FEA tool ANSYS/LS-DYNA is utilized for each experimental simulation to identify the maximal micromotion in the modified C-Tech implant system. The optimum design model is acquired by minimizing the micromotion by applying the Kriging interpolation (KGI) and genetic algorithm (GA). The improved design has a micromotion of 12.19 µm, as opposed to the original design’s micromotion of 38.11 µm. The improvement rate is 68.02%. Finally, the following innovative design is to add a secondary thread to the implant body. After conducting simulations, the micromotion is reduced to 4.72 µm. Further, it shows a 61.28% improvement compared with the optimization design version and an 87.62% improvement compared with the primary implants.

Determining primary stability for adhesively stabilized dental implants

ObjectivesTo examine factors influencing the primary stability of dental implants when stabilized in over-sized osteotomies using a calcium phosphate-based adhesive cement was the objective.MethodsUsing implant removal torque measurements as a surrogate for primary stability, we examined the influence of implant design features (diameter, surface area, and thread design), along with cement gap size and curing time, on the resulting primary implant stability.ResultsRemoval torque values scaled with implant surface area and increasing implant diameters. Cement gap size did not alter the median removal torque values; however, larger gaps were associated with an increased spread of the measured values. Among the removal torque values measured, all were found to be above 32 Ncm which is an insertion torque threshold value commonly recommended for immediate loading protocols.ConclusionThe adhesive cement show potential for offering primary implant stability for different dental implant designs. In this study, the primary parameters influencing the measured removal torque values were the implant surface area and diameter. As the liquid cement prevents the use of insertion torque, considering the relationship between insertion and removal torque, removal torque can be considered a reliable surrogate for primary implant stability for bench and pre-clinical settings.Clinical relevanceAt present, the primary stability of dental implants is linked to the quality of the host bone, the drill protocol, and the specific implant design. The adhesive cement might find applications in future clinical settings for enhancing primary stability of implants under circumstances where this cannot be achieved conventionally.

Axial Push-out Resistance of Dental Implant Different Thread Designs

Axial Push-out Resistance of Dental Implant Different Thread Designs

The Effect of V-Thread and Square Thread Dental Implants on Bone Stresses

The relationship between implant thread design and dental bone arguably has an influence on the distribution of bone stresses. However, the existing data on the influence of the thread profiles on bone stresses is considerably conflicting. For example, some studies concluded that thread shape has a substantial effect on the intensity of bone stresses, while others revealed that thread shape has no effect on the intensity of bone stresses. Accordingly, this study aims to computationally investigate and compare the effect of dental implant thread design on bone stresses under axial loading using a finite element analysis (FEA) approach. A geometrical model of V-thread and square thread implants, with a fixed thread pitch of 0.8 mm and a depth of 42 mm, and the surrounding bone was developed to assess the stresses generated within the implant components and bone structure under a 114 N axial load. The simulation is primarily concerned with the von Mises stresses within the implant components and the surrounding bone. The results demonstrate that the V-thread implant causes extremely high stress on the cortical and cancellous bones compared to the square thread implant. For example, the maximum stresses induced in the cortical bone are 195.3 MPa and 68.8 MPa, while the maximum stresses created in the cancellous bone are 19.7 Mpa and 2.2 Mpa in both designs, respectively. In addition, the cortical bone stresses substantially exceed the implant body stresses in both designs, with maximum stresses of 93.18 Mpa and 41 Mpa for V-thread and square-thread implants, respectively. However, the implant thread shape doesn’t affect the stress distribution in the abutment and screw. In general, the results show that implant thread design can result in featured mechanical stresses in the implant body and bone structure.

Pullout Strength of Pedicle Screws Inserted Using Three Different Techniques: A Biomechanical Study on Polyurethane Foam Block

Pullout strength is an important indicator of the performance and longevity of pedicle screws and can be heavily influenced by the screw design, the insertion technique and the quality of surrounding bone. The purpose of this study was to investigate the pullout strength of three different pedicle screws inserted using three different strategies and with two different loading conditions. Three pedicle screws with different thread designs (single-lead-thread (SLT) screw, dual-lead-thread (DLT) screw and mixed-single-lead-thread (MSLT) screw) were inserted into a pre-drilled rigid polyurethane foam block using three strategies: (A) screw inserted to a depth of 33.5 mm; (B) screw inserted to a depth of 33.5 mm and then reversed by 3.5 mm to simulate an adjustment of the tulip height of the pedicle screw and (C) screw inserted to a depth of 30 mm. After insertion, each screw type was set up with and without a cyclic load being applied to the screw head prior to the pullout test. To ensure that the normality assumption is met, we applied the Shapiro–Wilk test to all datasets before conducting the non-parametric statistical test (Kruskal–Wallis test combined with pairwise Mann–Whitney-U tests). All screw types inserted using strategy A had a significantly greater pullout strength than those inserted using strategies B and C, regardless of if the screw was pre-loaded with a cyclic load prior to testing. Without the use of the cyclic pre-load, the MSLT screw had a greater pullout strength than the SLT and DLT screws for all three insertion strategies. However, the fixation strength of all screws was reduced when pre-loaded before testing, with the MSLT screw inserted using strategy B producing a significantly lower pullout strength than all other groups (p &lt; 0.05). In contrast, the MSLT screw using insertion strategies A and C had a greater pullout strength than the SLT and DLT screws both with and without pre-loading. In conclusion, the MSLT pedicle screw exhibited the greatest pullout strength of the screws tested under all insertion strategies and loading conditions, except for insertion strategy B with a cyclic pre-load. While all screw types showed a reduced pullout strength when using insertion strategy B (screw-out depth adjustment), the MSLT screw had the largest reduction in pullout strength when using a pre-load before testing. Based on these findings, during the initial screw insertion, it is recommended to not fully insert the screw thread into the bone and to leave a retention length for depth adjustment to avoid the need for screw-out adjustment, as with insertion strategy B.

Influence of design implant and apical depth in post-extraction sockets: an in vitro simulated study

BackgroundImplant design and apical stability are principal parameters involved in achieving successful primary stability. Using polyurethane models to simulate post-extraction sockets, we investigated the effects of using differing blade designs on the primary stability of tapered implants and the impact of apical depth.MethodSix polyurethane blocks were used to simulate post-extraction pockets. One of the implants presented self-tapping blades (Group A), while the other (Group B) did not. Seventy-two implants were placed at 3 different depths (5 mm, 7 mm, and 9 mm), and a torque wrench was used to measure the stability of the implants.ResultsWhen evaluating the implants (placed at 5 mm, 7 mm, and 9 mm apical to the socket), we observed that the torque of the Group B implants was higher than that of Group A implants (P < 0.01). At the 9-mm depth, there was no difference between the groups (Drive GM 34.92 Ncm and Helix GM 32.33 Ncm) (P > 0.001), and considering the same implant groups, those placed at 7-mm and 9-mm depths presented higher torques (p < 0.01) than those placed at 5-mm (p > 0.01).ConclusionConsidering both groups, we concluded that an insertion depth of greater than 7 mm is needed for initial stability, and in situations involving reduced supportive bone tissue or low bone density, a non-self-tapping thread design improves implant stability.

Biomechanical Analysis of Mandibular Bone-Implant Construct With Three Implant Screw Design: A Finite Element Study

Abstract Temporomandibular joint replacement (TMJR) is a surgical procedure that relies heavily on the biomechanical properties of the implant-bone interface for success. In this study, we investigated the effects of three commonly used implant screw thread designs (buttress, square, and triangle) on the biomechanical performance of the mandibular bone-implant construct, with the aim of improving osseointegration. Using finite element analysis, we simulated the mechanical behavior of the prosthesis and mandible and examined the biomechanics of the temporomandibular joint. We considered five coefficients of friction ranging from 0.1 to 0.5 in our analyses. Our hypothesis was that changing the screw thread shape while keeping the pitch, height, and depth constant could enhance the biomechanical environment at the peri-implant bone. Our results indicate that the square thread design produced the highest stress concentration, while the triangle thread design exhibited the most favorable distribution of stress around the implant. Furthermore, increasing the coefficient of friction led to an increase in stress concentration in the implant and surrounding bone. Our findings offer valuable insights into the biomechanical performance of different screw thread designs in the mandibular bone-implant construct. They highlight the significance of considering screw thread shape and coefficient of friction in TMJR implant design. Future studies should incorporate the viscoelastic properties of bone to improve the accuracy of finite element analysis. This research contributes to the optimization of TMJR implants and ultimately enhances patient outcomes.

Configurations of implant threads: A Review

The dental implants are used for replacement of missing teeth, and it’s have been widely used for restore the function, esthetic, speech, and patient confidence. It forms the contact between the implant and the bone. The implant threads are altered to improve the initial contact, primary stability, increase the surface area, and facilitate dissipation of loads at the implant and bone surface. Implant thread design is one of the key factors it determines the primary stability and stress distribution during osseointegration, the threaded implants are reduced both stress on bone and sliding distance between the implant and bone. The primary stability is play a important role in less bone quality, double and triple threaded implant increases the primary stability than single threaded implant, the implant threads distribute mechanical stress equally at bone implant interface, lead to stability of dental implants and less bone resorption and also higher thread profile improve the primary stability, the success or failure of implants depend on the thread designs and quality of bone.

Comparative Evaluation of Two Implant Designs Based on Bone Loss and Stability with Early Loading Method.

The study evaluated the implant bone loss and stability of implant changes with diverse designs with early placement at eight weeks and eight months' time. The subjects for the current study had partial tooth loss in the posterior mandibular arch. A total of 30 samples were split into two groups of 15, one with a flared crest module and a buttress thread design, the other with a parallel crest module and a V-shaped thread design. Ostell assessed each subject's implant stability four times, at baseline, eight weeks, four months, and eight months. At intervals of eight weeks, four months, and eight months, intraoral periapical radiographs were examined using ImageJ software to measure crestal bone loss. When Group I and Group II's implant stability quotient (ISQ) values at baseline, eight weeks, four months, and eight months were compared; Group I's ISQ values at each of the four measured time periods were statistically significant. At eight weeks in Group I, the ISQ value was very considerable. At eight weeks, four months, and eight months, there was a statistically significant bone loss in Group II in comparison to Group I. At eight months, Group II's bone loss value was very considerable. In contrast to Group II implant designs, it was found that Group I implants demonstrated enhanced implant-less bone loss and stability.

Are Implant Threads Important for Implant Stability? An In Vitro Study Using Low-Density Polyurethane Sheets

Different strategies are known to improve implant primary stability (PS) and the bone-to-implant contact in post-extractive conditions, such as the macro-geometry of screws and apical threads, which can enhance the mechanical characteristics. In any case, the role of the apical area design in maintaining or improving the PS, especially in low-quality bone, still remains unclear. Thus, the present study aimed at evaluating in vitro the Insertion Torque (IT), Removal Torque (RT), and Resonance Frequency Analysis (RFA) of different implant apical threads in a cylindrical (EE) and in three conical implants (T3, TAC, Intra-lock) inserted in simulated post-extraction conditions on low-density polyurethane foams of 10 and 20 pounds per cubic foot (PCF), with and without the addition of a cortical sheet of 30 PCF in density. The IT, RT, and RFA values of all the implants tested were directly proportional to the polyurethane density and to the presence of the cortical sheet, but TAC and Intra-lock implants, which had the latest-generation thread design, always showed significantly higher values (e.g., IT: 18.6 and 18.6 Ncm, RT: 10.8 and 13.7 Ncm, RFA mean: 46 and 43 ISQ, in the 20 PCF density with the cortical sheet for TAC and Intra-lock, respectively). In particular, TAC implants also reached the highest RFA values in the lowest-density foam (19 ISQ). In conclusion, the present in vitro study demonstrated that TAC and Intra-lock apical designs and macro-geometries could play a key role in determining the PS and the polyurethane-implant contact in simulated post-extraction conditions in low-density artificial bone.

Comparison of insertion torque, implant stability quotient and removal torque, in two different implant designs with and without osseodensification. - An ex vivo bench top study.

Primary stability is an important factor in influencing the outcome of dental implants. Osteotomy modification techniques mentioned, include osteotomes for bone condensation, under-preparation of osteotomy and Osseodensification (OD). The objective of our twin arm study was to assess how two different implant designs respond to conventional osteotomy drilling and how these values obtained compare with OD. The study comprised a total of 80 implants inserted in pig tibia bone. Group 1a (n=20) consisted of tapered internal implants and group 1b (n=20) consisted of tapered pro implants, both inserted with conventional drilling. Group 2a (n=20) consisted of tapered internal implants and group 2b (n=20) consisted of tapered pro implants, both inserted with OD. Each implant inserted was measured for implant stability quotient (ISQ), insertion torque and removal torque. Group 1a showed a significantly lower ISQ, mean insertion and removal torque and as compared to Group 1b. Group 2a and 2b had comparable mean values for all the three parameters. Inter-group comparison showed a higher ISQ and insertion torque value for group 2 than group 1. Intra-group assessment showed a significantly lower value for all parameters for sub-group a than b. OD enhances primary stability of implants in bone; but when no OD is used, the tapered pro implant design offers a better primary stability. This may be attributed to the active thread design.

Optimization of thread configuration in dental implants through regulating the mechanical stimuli in neighboring bone

Background and objectiveThe threads, as the most critical component of dental implants, transfer the imposed occlusal loads to the adjacent bone. Moreover, regulation of the mechanical stimuli in the implant adjacent bone is crucial to maximize the bone-implant construct stability. An optimal thread design can be resulted when the distribution of mechanical stimuli within the bone, and at the implant-bone interface, lie in an advised confined range. In this work, with the goal of finding the optimal thread design, which can provide the maximum level of stability, the effects of thread parameters, namely, thread depth, thread width, and thread pitch, together with upper and lower thread angles, on maximum principal strain within the cortical and cancellous bone, and shear strain at the implant-bone interface, were investigated. MethodsIn this study, the response surface methodology (RSM), due to the central composite design (CCD), was employed to obtain a set of 53 experiments. Following that, they were numerically simulated using the finite element method (FEM). The polynomial regression model was then used to predict the response functions based on the magnitude of thread parameters. The effectiveness of each thread parameter was also evaluated through statistical tools. Moreover, the non-dominated sorting genetic algorithm (NSGA-II) was performed to find the optimum dimensions of the thread. ResultsThrough comparing the results obtained from analyzing initial and optimized configuration of threads, it was shown that the latter causes a reduction in the maximum principal strains in cancellous and cortical bones by about 25% and 30%, respectively, which is in favor of making a higher quality bone, and thus greater stability in dental implant-bone construct. Moreover, the maximum shear strains at the implant-bone interface in different planes were reduced by about 40%, in the optimized thread, compared with the initial design. ConclusionsThe optimized design found in this study is a buttress thread with a fine pitch, but deep thread, which keeps the mechanical stimuli in a safe range to grant an acceptable level of stability.

Evaluation of instrumentation and pedicle screw design for posterior lumbar fixation: A pre-clinical in vivo/ex vivo ovine model.

Stabilization procedures of the lumbar spine are routinely performed for various conditions, such as spondylolisthesis and scoliosis. Spine surgery has become even more common, with the incidence rates increasing ~30% between 2004 and 2015. Various solutions to increase the success of lumbar stabilization procedures have been proposed, ranging from the device's geometrical configuration to bone quality enhancement via grafting and, recently, through modified drilling instrumentation. Conventional (manual) instrumentation renders the excavated bony fragments ineffective, whereas the "additive" osseodensification rotary drilling compacts the bone fragments into the osteotomy walls, creating nucleating sites for regeneration. This study aimed to compare both manual versus rotary Osseodensification (OD) instrumentation as well as two different pedicle screw thread designs in a controlled split animal model in posterior lumbar stabilization to determine the feasibility and potential advantages of each variable with respect to mechanical stability and histomorphology. A total of 164 single thread (82 per thread configuration), pedicle screws (4.5× 35 mm) were used for the study. Each animal received eight pedicles (four per thread design) screws, which were placed in the lumbar spine of 21 adult sheep. One side of the lumbar spine underwent rotary osseodensification instrumentation, while the contralateral underwent conventional, hand, instrumentation. The animals were euthanized after 6- and 24-weeks of healing, and the vertebrae were removed for biomechanical and histomorphometric analyses. Pullout strength and histologic analysis were performed on all harvested samples. The rotary instrumentation yielded statistically (p= 0.026) greater pullout strength (1060.6N ± 181) relative to hand instrumentation (769.3N ± 181) at the 24-week healing time point. Histomorphometric analysis exhibited significantly higher degrees of bone to implant contact for the rotary instrumentation only at the early healing time point (6 weeks), whereas bone area fraction occupancy was statistically higher for rotary instrumentation at both healing times. The levels of soft tissue infiltration were lower for pedicle screws placed in osteotomies prepared using OD instrumentation relative to hand instrumentation, independent of healing time. The rotary instrumentation yielded enhanced mechanical and histologic results relative to the conventional hand instrumentation in this lumbar spine stabilization model.

Impact of implant thread design on insertion torque and osseointegration: a preclinical model.

Successful osseointegration of endosteal dental implants has been attributed to implant design, including the macro-, micro- and nano- geometric properties. Based on current literature pertaining to implant design, the resultant cellular and bone healing response is unknown when the thread thickness of the implants is increased, resulting in an increased contact area in implants designed with healing chambers. The aim of this study was to evaluate the effect of two implant designs with different thread profiles on the osseointegration parameters and implant stability at 3- and 6-weeks in vivo using a well-established preclinical dog model. A total of 48 type V Ti alloy implants were divided in two groups according to their thread design (D1= +0.1x/mm and D2= +0.15x/mm) and placed in an interpolated fashion into the radii of six beagles. Insertion torque was measured at time of placement, radii were extracted for histological processing following 3- and 6-week healing intervals. Histologic and histomorphometric analyses were performed in terms of bone to implant contact (%BIC) and bone area fraction occupancy within implant threads (%BAFO). Statistical analyses were performed through a linear mixed model with fixed factors of time and implant thread design. Surface roughness analysis demonstrated no significant differences in Sa and Sq between D1 and D2 implant designs, which confirmed that both implant designs were homogenous except for their respective thread profiles. For insertion torque, statistically significant lower values were recorded for D1 in comparison to D2 (59.6 ± 11.1 and 78.9 ± 10.1 N⋅cm, respectively). Furthermore, there were no significant differences with respect to histological analysis and histomorphometric parameters, between D1 and D2 at both time points. Both thread profiles presented equivalent potential to successfully osseointegrate in the osteotomies, with D2 yielding higher mechanical retention upon placement without detrimental bone resorption.

Transformative Learning and Critical Consciousness: A Model for Preclerkship Medical School Substance Use Disorder Education.

Preparing medical students to provide compassionate person-centered care for people with substance use disorders (SUD) requires a re-envisioning of preclerkship SUD education to allow for discussions on stigma, social determinants of health, systemic racism, and healthcare inequities. The authors created a curricular thread that fosters the development of preclerkship medical students' critical consciousness through discussion, personal reflection, and inclusion of lived experiences. The authors used transformative learning theories to design and implement this thread in the 2021-2022 academic year in the Duke University School of Medicine preclerkship curriculum. Content included lectures, person-centered workshops, case-based learning, motivational interviewing of a standardized patient, and an opioid overdose simulation. Community advocates and people with SUD and an interdisciplinary faculty were involved in the thread design and delivery and modeled their lived experiences. Students wrote a 500-word critical reflection essay that examined their personal beliefs in the context of providing care for people with SUD. One hundred and twenty-two students submitted essays and 30 (25%) essays were randomly selected for a qualitative analysis. Seven major themes emerged: race/racism, systemic barriers, bias and stigma, personal growth/transformation, language or word usage, future plans for advocacy, and existing poor outcomes. Students were able to link material with prior knowledge and experiences, and their attitudes towards advocacy and goals for future practice were positively influenced. By aligning the thread design with the principals of transformative learning, students developed their critical consciousness toward people with SUD and cultivated a holistic understanding of SUD.

Structural Optimization of a Circular Symmetric Threaded Connection System Based on the Effect of the Upper Stabbing Flank Corner Radius

In order to boost shale gas drilling efficiency, oil and gas exploration and drilling distances have risen along with the number of horizontal definitions and directions. As a result, the joints of oil wells and core gas pipes are under continual stress and compression, internal and external pressures, and extreme bending stresses. This will negatively impact the drilling system’s sustainability and the performance requirements are therefore reinforced. Good thread design is crucial because premium threaded connections are typically employed in joints, and the construction of reliable premium connections to external limitations is closely related to the choice of pertinent parameters as optimal values. In this article, new premium connection systems will be created and constructed that can show good vibration and durability under such stressful conditions. The amount of von Mises stress that is received from the threaded connection depends on how each parameter is changed. In particular, the values of the “upper stabbing flank corner radius” were used to examine the von Mises stress variations in the entire structure. An optimized design for the premium connection system is proposed with the best value of upper stabbing flank corner radius according to minimized stress on the teeth of the premium connection against compressive forces. The study’s findings suggest that it is feasible to create a premium connection that can lower stress following the genuine demand of the industry.

Clinical performance of immediately placed and restored progressive-type implants in the esthetic zone: a prospective observational study

PurposeTo assess implant success and survival of immediately placed and restored progressive-type implants in the esthetic zone.Material and methodsA total of n = 21 patients (21 implants) had received an immediate placement of a tapered, two-part implant with a progressive thread design (PL) for a single tooth replacement in the anterior maxilla. An immediate ‘non full-functional loaded’ restoration was provided upon adequate primary stability on a final patient-specific abutment (one abutment-one time concept). The final restoration was provided at 12 weeks (baseline). Implant survival and success (e.g. bleeding on probing—BOP, probing pocket depth—PD, mucosal recession—MR, pink esthetic score—PES) as well as patient- reported outcomes (PROM`S) were recorded at 6 and 12 months.ResultsAn adequate primary implant stability (i.e. insertion torque > 35 Ncm) was obtained at all but one sites. At 12 months, implant survival (n = 20 patients) amounted to 100%. Non-significant changes to baseline were noted for mean BOP (2.5 ± 28.2%), PD (− 0.26 ± 0.73 mm), and MR (0.0 ± 0.4 mm) values. PES values amounted to 12.9 ± 1.14 and 13.2 ± 0.84 at 6 and 12 months. Technical and mechanical complications were not observed. Patients expressed an overall high satisfaction.ConclusionsThe presented immediacy protocol was associated with high survival and success rates on the short-term.Graphical