Primary Stability Of Implants Research Articles

Development and validation of an algorithm to determine the minimal factors needed for non-invasive measurement of the in vivo primary stability of cementless hip implants.

Aseptic loosening is a frequent cause for revision of endoprosthesis. X-ray examinations like Radio-Stereometry-Analysis (RSA) are among the most widely used in vivo methods for its detection. Nevertheless, this method is not used routinely because of bone marker and related radiation exposure. This work aims at creating a new in vivo concept to detect implant stability measuring micromotions without x-ray and to develop a corresponding algorithm. Based on the assumption of contactless measurement, the input parameters for the algorithm are the distances of each ultrasound sensor to the object (prosthesis and bone) and its position. First, the number of parameters necessary for a precise reconstruction and measurement of micromotions between objects had to be defined. Therefore, the algorithm has been tested with simulations of these parameters. Two experimental measurements, either using contact sensors or ultrasound, were used to prove the accuracy of the algorithm. Simulations indicate a high accuracy with three distances as initial parameters for each object. Contact measurements show precise representation of micromotion, and the contactless measurements show the possibility of detecting various materials with a high resolution. This work lays the foundations for non-invasive detection of micromotions between the implant-bone interface.

Efficacy of Three Different Photobiomodulation Therapies on Primary and Secondary Implant Stability in D3 and D4 Bone Type- A Research Protocol for Randomised Controlled Trial

Introduction: Osseointegration is considered one of the most important deciding factors to check for implant stability, which decides successful outcome of the implant. Photobiomodulation has been used to improve the implant stability by enhancing osseointegration. Photobiomodulation (PBM) or Low-level Laser Therapy (LLLT) causes an enhanced effect in the bone implant contact. Need for the Study: There are no definitive therapies/protocol of LLLT in cases of bone density of D3 and D4. Also There are no studies in literature which compares the different laser settings so that a standardised setting can be established. Therefore, there is need to generate evidence whether reducing the number of appointments and reducing the amount of energy given in D3 and D4(compromised) bone can help achieve early loading in patients. Aim: To evaluate and compare the effect of three different photobiomodulation therapies on primary and secondary implant stability in D3 and D4 bone type in comparison to control group to achieve early loading. Materials and Methods: This randomized controlled, double blinded study allocated 108 patients having D3 or D4 bone according to Misch classification into six groups. Three different PBM therapy which is either Therapy A, B or C(placebo) will be used. The implant stability will be measured by Ostell meter in Implant Stability Quotients (ISQ) scale, immediately after surgery, after 3 weeks, after 12 weeks and after 6 months of surgery. The bone density will be measured before surgery and 3 months after surgery. Expected Outcome: At the end of the study, an evidence will be generated whether reducing the number of appointments and reducing the amount of energy given in D3 and D4(compromised) bone can help achieve early loading in patients. Patients treated using PBM therapy either protocol A or protocol B may show enhanced implant stability.

Comparison of Primary Stability of Two Different Implants DesignsA Prospective Clinical Study

Introduction: Any implant treatment must begin with successful implant integration. The effectiveness of implant osseointegration is determined by various factors, including implant design, implant diameter and density, and surgical technique. Osseointegration is dependent on implant design. Aim: To assess the primary stability of tapered and cylindrical implants by using Resonance Frequency Analysis (RFA) and Insertion Torque Values (ITV). Materials and Methods: This in-vivo, prospective clinical study was conducted in the Department of Prosthodontics at Sibar Institute of Dental Sciences, Guntur, Andhra Pradesh, India in the month of November 2019. Twenty patients were selected for the study. Tapered Bioline implants (Bioline Dental GmbH & Co. KGGermany) were spaced in 10 patients (group 1) and cylindrical Bioline implants (Bioline Dental GmbH & Co. KG-Germany) in the other 10 patients (group 2). For both implant designs, primary stability was assessed immediately after implant placement using RFA by Osstell Mentor and ITV by a torque wrench. KolmogorovSmirnov test, Shapiro-Wilk test were used for checking normality. Mann Whitney U test, Independent t tests, Spearman correlation tests were done by using software Statistical Package for Social Sciences (SPSS) Version 23.0. Results: The mean ISQ (Implant Stability Quotient) for tapered implants was 76.6±2.3, and for cylindrical implants mean ISQ is 59.75±4.2 (p-value <0.001). The mean ITV for tapered implants was 43.5±2.58 Ncm, and for cylindrical implants, the mean ITV was 33±4.21 Ncm (p-value <0.001). The correlation between ITV and RFA was 0.928 which was highly significant (p<0.001**). Conclusion: Within the scope of this investigation, tapered implants showed better primary stability than cylindrical-shaped implants as determined by ISQ and insertion torque values. ITV and ISQ values showed a positive correlation in determining the primary stability of implants.

Investigation to Predict Primary Implant Stability Using Frictional Resistance Torque of Tap Drilling.

The purpose of this experimental study was to investigate the correlation between the frictional resistance torque of tap drilling prior to implant placement and the primary stability after implant placement. Solid rigid polyurethane bone blocks of four different densities were used in this study. A computerized surgical implant motor device was utilized to measure the frictional resistance torque of tap drilling. After the tap torque was measured, the dental implants were inserted at the prepared sites. During the implantation, the insertion torque was recorded, and resonance frequency analysis was performed, the value of which was calculated as the implant stability quotient. Thereafter, the correlation between the tap torque and the primary stability of the implant was evaluated and compared with the standard drilling protocol. A significant positive correlation was found between the tap torque and insertion torque (Pearson's r = 0.88, P < 0.0001). Similarly, there was a positive correlation between the tap torque and implant stability quotient (Pearson's r = 0.69, P < 0.0001). These results suggest that measurement of the frictional resistance torque of tap drilling prior to implant placement could provide helpful information for implant primary stability.

Placement accuracy and primary stability of implants in the esthetic zone using dynamic and static computer-assisted navigation: A retrospective case-control study

Statement of problemBoth the placement accuracy and primary stability of implants are important to implant therapy in the esthetic zone. The effect of dynamic and static computer-assisted navigation on the primary stability of implants in the esthetic zone remains uncertain. PurposeThe purpose of this case-control study was to investigate the effect of dynamic and static computer-assisted navigation on the placement accuracy and primary stability of implants in the esthetic zone. Material and methodsPartially edentulous participants who received at least 1 implant in the anterior maxilla using either fully guided static or dynamic computer-assisted implant surgery (s-CAIS, d-CAIS) from January 2020 to February 2022 were screened. Participant demographic information, timing of implant placement, primary stability represented by the insertion torque value (ITV) in Ncm, and implant survival were collected from the treatment record. Bone quality at the implant sites was determined according to the Lekholm and Zarb classification. The accuracy of implant placement represented by the linear (platform: Dpl, mm; apex: Dap, mm) and angular deviations (axis: Dan, degree) between the planned and placed implants was evaluated based on the preoperative surgical plan and postoperative cone beam computed tomography (CBCT) data. A statistical analysis of the data was completed by using the chi-squared, Fisher exact, Student t, and Mann-Whitney U tests (α=.05). ResultsA total of 32 study participants (38 implants) were included. The groups of s-CAIS (16 participants, 18 implants) and d-CAIS (16 participants, 20 implants) were statistically comparable in sex (P=.072), age (P=.548), bone quality (P=.671), and timing of implant placement (P=.719). All implants survived during an average follow-up period of 13 months. The d-CAIS group showed close linear deviations (Dpl 1.07 ±0.57 mm, Dap 1.26 ±0.53 mm) but lower angular deviation (Dan 2.14 ±1.20 degrees) and primary stability (ITV 25.25 ±7.52 Ncm) than the s-CAIS group (Dpl 0.92 ±0.46 mm, Dap 1.31 ±0.43 mm, Dan 3.31 ±1.61 degrees, ITV 30.56 ±11.23 Ncm, PDpl=.613, PDap=.743, PDan=.016, PITV=.028). ConclusionsComparable linear positioning accuracy and higher angular deviation were found for implants placed in the esthetic zone by using s-CAIS than when using d-CAIS. Higher primary stability of implants may be achieved by using s-CAIS, as s-CAIS seemed to have higher osteotomy accuracy than d-CAIS.

Preclinical study probing primary stability of dental implants in synthetic and natural bones

AbstractThe natural bone is a biological example of a polymer–ceramic composite with a higher volume fraction of nanosized ceramic (around 65% hydroxyapatite) dispersed in polymer (collagenous) matrix. The loading of a dental implant involves the biomechanical interactions of the implant with such natural composites in the jaw bones of human subjects. In particular, the insertion torque responses of the dental implant are related to the implant design, in particular the external thread morphology, which influences the primary stability of the implant. In this study, the effect of the bone properties (polyurethane‐based synthetic bone, porcine and human cadaver lumbar bone) and clinically relevant implant driving protocols on the insertion and removal torques of newly designed implant variants (hybrid threads with macro‐ and micro‐threads) were assessed, quantitatively and qualitatively. It was observed that torque response increased with an increase in bone density, irrespective of the implant designs. The torque response of the implants in both synthetic and natural bones was benchmarked with the commercially available implant. The implants with bone cutting partial macro‐threads at the apical end without inter thread gap exhibited comparable clinically relevant results with respect to control implants and were found to be most suitable for implantation into natural bone.

Measurement of bone damage caused by quasi-static compressive loading-unloading to explore dental implants stability: Simultaneous use of in-vitro tests, μ-CT images, and digital volume correlation

Primary stability of dental implants is the initial mechanical engagement of the implant with its adjacent bone. Implantation and the subsequent loading may cause mechanical damage in the peripheral bone, which ultimately reduces the stability of the implant. This study aimed at evaluating primary stability of dental implants through applying stepwise compressive displacement-controlled, loading-unloading cycles to obtain overall stiffness and dissipated energy of the bone-implant structure; and quantifying induced plastic strains in surrounding bone using digital volume correlation (DVC) method, through comparing μCT images in different loading steps. To this end, dental implants were inserted into the cylindrical trabecular bones, then the bone-implant structure was undergone step-wise loading-unloading cycles, and μCT images were taken in some particular steps, then comparison was made between undeformed and deformed configurations using DVC to quantify plastic strain within the trabecular bone. Comparing stiffness reduction and dissipated energy values in different loading steps, obtained from the force-displacement curve in each loading step, revealed that the maximum displacement of 0.16 mm can be deemed as a safe threshold above which damages in peri-implant bone started to increase considerably (p < 0.05). In addition, it was found here that peri-implant bone strain linearly increased with decreasing bone-implant stiffness (p < 0.05). Moreover, strain concentration in peri-implant bone region showed that the plastic strain in trabecular bone spread up to a distance of about 2.5 mm away from the implant surface. Research of this kind can be used to optimize the design of dental implants, with the ultimate goal of improving their stability, also to validate in-silico models, e.g., micro-finite element models, which can help gain a deeper understanding of bone-implant construct behavior.

Macrogeometric Differentiation of Dental Implant Primary Stability: An In Vitro Study

To evaluate an alternative cutting, progressive thread design to increase primary stability in low-density bone. Four different implants with different macrogeometries (Nobel Biocare Active [NA] Internal RP implants [4.3 × 11.5 mm], Straumann BLX Roxolid RB implants [4.5 × 10 mm], Astra Tech Implant EV implants [4.2 × 11 mm], and PrimeTaper [PT 4.2 × 11 mm]) were placed in simulated osteotomies and extraction sockets in synthetic bone (Sawbones) according to the manufacturers' protocol. Insertion torque and ISQ values were measured using Implantmed Plus motor and Ostell IDX, respectively. Insertion time was recorded. Average values were calculated and compared using ANOVA and Tukey test. Insertion torque (range: 5 to 44 Ncm) increased with increasing synthetic bone density for all implants. Different ISQ values in synthetic low-density bone were not observed in higher-density synthetic bone. Insertion torque of all implants was reduced when implants were placed in simulated sockets compared to simulated osteotomies. In both low-density and higher-density synthetic bone, the primary stability of PrimeTaper implants with cutting and progressive thread design was equivalent to that of the Nobel Biocare NobelActive implant with compressive thread design and greater than the BLX implant with compressive thread design. Different implant macrogeometries obtain relatively high primary stability in low-density bone when measured by ISQ. Doublethread implant designs reduce insertion times in higher-density bone. A cutting and progressive compressing thread design provides density-sensing performance compared to aggressive condensing thread designs. This macrogeometry can achieve high primary stability associated with modest insertion torque compared to aggressive threaded implant designs known to attain the highest insertion torque. The presence of multiple cutting threads may offer advantages in obtaining primary stability in low-density bone.

Comparative Evaluation of Osseodensification Versus Conventional Osteotomy Technique on Dental Implant Primary Stability: An Ex Vivo Study.

Purpose One of the commonest treatment options for replacing missing teeth is a root-form implant. Clinically, the key mechanical factor in achieving success is primary stability. This ex vivo study aims to evaluate whether osseodensification method will achieve good primary stability or the conventional drilling protocol. Methods Fresh iliac bone of the sheep was selected similar to D3 and D4 bone densities. A total of 22 osteotomy sites were prepared in the bone sample, of which 11 were prepared by osseodensification method (test group) and other 11 by conventional undersized drilling (control group). Primary stability was measured using insertion torque (IT), resonance frequency analysis (RFA), and reverse torque values (RTVs) by measuring implant stability quotient (ISQ). The recorded data were statistically analyzed using Statistical Package for the Social Sciences (SPSS) Version 22.0. The differences between groups were compared using the Mann-Whitney U test and independent t-test. The Pearson correlation coefficient test was performed to measure the linear relationship between two variables. The statistical significance level was established at p<0.05. Results When the correlation among IT, RTV, and ISQ was measured, a statistically significant correlation between IT and RTV (p=0.001) and between IT and ISQ (p=0.0001) was observed. A statistically significant (p=0.014) correlation between RTV and ISQ was also found. Conclusion Osteotomy prepared by osseodensification method showed higher IT, RTV, and ISQ values than the conventional undersized group.

Understanding the thrust force evolution and primary stability for dental implantation - An in-vitro experimental investigation.

The dental implant is challenging due to the unstable quality of the surrounding bone. This study aimed to explore the feasibility of using thrust force characteristics to identify different bone types and the influencing mechanisms of spindle speed and feed rate on primary stability of dental implants through in-vitro experiments. 13 groups of osteotomy experiments were performed on mandibles and maxillae of pigs with different bone types (I, II, and III) under different spindle speeds (600 and 800 rpm) and feed rates (20 and 60 mm/min). The thrust force evolution under different conditions was extracted and analysed to elaborate the distribution and thickness of the cortical and trabecular bone layers on different bone types. Dental implant placements were performed, and corresponding primary stabilities were obtained. Furthermore, histologic observation was conducted to reveal the bone/implant contact morphology. From the results, the amplitude and trend of thrust force show a regular variation during drilling different bone types. The highly dynamic information of thrust force can be analysed to characterise the distribution and thickness of the cortical and trabecular bone layers, hence effectively detecting different bone types. Since a lower feed rate and resulting bone temperature elevation lead to more thermal damages, primary stability decreases with the decrease of feed rate. Spindle speed has no significant effect. This study establishes a more in-depth understanding into the thrust force evolution and also provide a clinical option for reducing the complexity of bone type and drilling parameters determination in osteotomy.

Primary Stability of Trabecular Metal Implant in Comparison to Fully Threaded Implants: In Vitro Study Simulating Immediate Implant Placement.

The aim of this study was to evaluate primary stability of 3.7-mm diameter porous tantalum Trabecular Metal (TM) implant, and compare it to fully threaded implants, in the in vitro model of immediate implant placement in the anterior maxilla. A total of 60 implants were placed into bovine ribs using surgical guides. Implants were divided in 3 groups of 20 according to the design: TM, Tapered Screw-Vent (TSV), and NobelReplace. To simulate immediate placement in anterior maxilla, implants were placed under a sharp angle toward the ribs, not fully submerged. Placement angle of 20.7° was calculated after analysis of 148 virtually planned implants on cone beam computerized tomography scans of 40 patients. No statistically significant difference in implant stability quotient (ISQ) was found between TM (65.8 ± 2.6), TSV (64.7 ± 2.7), and NobelReplace (64.6 ± 2.7). TSV implants achieved higher insertion torque (37.0 ± 4.8 Ncm) than TM (32.9 ± 5.2 Ncm) and NobelReplace (23.2 ± 3.3 Ncm). TSV had the shortest insertion time of 13.5 ± 1.0 seconds, compared to 15.2 ± 1.2 seconds for TM, and 19.7 ± 1.7 seconds for NobelReplace. Pearson correlation analysis showed significantly correlated insertion torque and ISQ values for TM group (P = .011, r = .56), a nonsignificant correlation was found for TSV and NobelReplace. The results of the present study indicate that TM implant can achieve good primary implant stability in insertion torque and resonance frequency analysis.

Oblique Cutting Based Mechanical Model for Insertion Torque of Dental Implant

The insertion torque of a dental implant is an important indicator for the primary stability of dental implants. Thus, the preoperative prediction for the insertion torque is crucial to improve the success rate of implantation surgery. In this present research, an alternative method for prediction of implant torque was proposed. First, the mechanical model for the insertion torque was established based on an oblique cutting process. In the proposed mechanical model, three factors, including bone quality, implant geometry and surgical methods were considered in terms of bone-quality coefficients, chip load and insertion speeds, respectively. Then, the defined bone-quality coefficients for cancellous bone with the computed tomography (CT) value of 235–245, 345–355 and 415–425 Hu were obtained by a series of insertion experiments of IS and ITI implants. Finally, the insertion experiments of DIO implants were carried out to verify the accuracy of developed model. The predicted insertion torques calculated by the mechanical model were compared with those acquired by insertion experiments, with good agreement, the relative error being less than 15%. This method allows the insertion torque for different implant types to be quickly established and enhances prediction accuracy by considering the effects of implants’ geometries and surgical methods.

Densification of cancellous bone with autologous particles can enhance the primary stability of uncemented implants by increasing the interface friction coefficient

Sufficient primary stability is one of the most important prerequisites for successful osseointegration of cementless implants. Bone grafts, densification and compaction methods have proven clinically successful, but the related effects and causes have not been systematically investigated. Postoperatively, the frictional properties of the bone-implant interface determine the amount of tolerable shear stress. Frictional properties of different implant surfaces have been widely studied. Less attention has been paid to the influence of host bone modifications. The purpose of this study was to investigate the influence of densification of cancellous bone with bone particles on the interface friction coefficient.Cancellous bone samples from femoral heads were densified with bone particles obtained during sample preparation. The densification was quantified using micro-Ct. Friction coefficients of the densified and paired native samples were determined.Densification increased the BV/TV in the first two millimeters of the bone samples by 10.5 ± 2.7% to 30.5 ± 2.7% (p < 0.001). The static friction coefficient was increased by 10.5 ± 6.1% to 0.43 ± 0.03. The static friction coefficient increased with higher BV/TV of the bone interface, which is represented by the top 2 mm of the bone.The increase in contact area, intertrabecular anchorage and particle bracing could be responsible for the increase in friction. Optimization of particle shape and size based on the patient’s individual bone microstructure could further increase frictional resistance. Bone densification has the potential to improve the primary stability of uncemented implants.

The Importance of Correlation between CBCT Analysis of Bone Density and Primary Stability When Choosing the Design of Dental Implants-Ex Vivo Study.

This study aims to determine the correlation between the mean value of bone density measured on the CBCT device and the primary stability of dental implants determined by resonant frequency analysis. An experimental study was conducted on a material of animal origin: bovine femur and pig ribs. Two types of implants were used in this study: self-tapping and non-self-tapping of the same dimensions. Results of the experimental study showed a statistically significant correlation between bone density expressed in HU units and the primary stability of self-tapping and non-self- tapping dental implants expressed in ISQ units in bovine femur bones and self-tapping implants and pig rib bones. There was no statistically significant correlation between non-self-tapping dental implants in pig rib bones. Self-tapping and non-self-tapping implants did not show statistical significance in the primary stability in bones of different qualities. The analysis of bone density from CBCT images in the software of the apparatus expressed in HU units can be used to predict the degree of primary stability of self-tapping and non-self-tapping dental implants in bones of densities D1 and D2, and self-tapping dental implants in bones of the lower quality D4.

Is Resonance Frequency Analysis a Reliable Evaluation for Primary Stability of Implants Without Apical Contact?

The primary stability of dental implants is one of the most crucial factors for providing long-term success of osseointegration. Vertical deficiencies, such as those due to maxillary sinus pneumatization, may cause a severe vertical limitation to residual bone height. This study aimed to examine the primary stabilization of implants without apical contacts. Eighty bone-level implants (4.1-mm diameter/10-mm length) were placed into polyurethane test blocks without apical contacts. According to coronal bone-to-implant contact, groups were set as 4, 6, 8, and 10 mm, respectively. Resonance frequency analysis (RFA) using a SmartPeg was performed separately toward the transversal and horizontal axes by two independent researchers. Data were statistically compared for interobserver and among groups. Interobserver reliability varied from moderate to excellent (intraclass correlation coefficient [ICC]: 0.629 to 0.985). There were no significant differences among the 6 mm, 8 mm, and 10 mm groups, although the 4 mm group showed the significantly lowest stability (P < .001). Transversal and longitudinal measurements of the same groups did not show a parallel correlation statistically. RFA values may be affected by the finger torque in tightening of the SmartPeg among different researchers. Fully placed implants did not significantly show the highest stability among various apically contactless groups. Consequently, RFA should not be used alone to evaluate primary stability for implants without an apical contact.

Evaluation of the Osseodensification Technique in Implant Primary Stability: Study on Cadavers.

The objective of this study was to compare the osseodensification drilling technique used with Densah implant drills (Versah) to standard drilling by evaluating their contribution to primary implant stability. A total of 21 mandibles dissected from cadavers were selected. Axiom drills (Anthogyr) were used for 29 standard drilling (SD) protocols in the control group. In the test group, the Densah profile drills were used to perform 29 osteotomies (OD). Implant placement was performed for 58 of these procedures. The insertion torque (IT) and implant stability quotient (ISQ) were recorded. High-resolution CBCT allowed for a postoperative analysis of the peri-drilling bone tissue. For 16 osteotomies without implant placement, Mann-Whitney U test was used for comparison of IT and ISQ values between groups. Spearman rank correlation coefficient was used between IT and ISQ values. The significance level was α = .05. The IT values for OD and SD were, respectively, 34.9 Ncm ± 19.1 and 23.6 Ncm ± 9.8. The IT was significantly higher in the OD group compared to the SD group (P = .036). A moderate positive correlation (ρ = 0.527) between IT and ISQ was observed, as well as a significant increase (P = .026) in bone density. There was a significant increase in IT and bone density following an osseodensification procedure compared to standard drilling.

Evaluation of different osteotomy techniques on primary stability of implants using RFA

Primary stability of implant is based on its mechanical engagement to the surrounding bone at the time of installation. It can be affected by patient- related factors like the bone quality and quantity and underlying systemic diseases and the surgical technique. Among various methods available for measuring primary implant stability, the most recommended method is the use of Resonance Frequency Analysis (RFA) due to its versatility. The aim of this study was to evaluate the influence of 4 different osteotomy techniques on the primary stability of implants using RFA. Forty implants of same size and system were installed on goat's mandible under four osteotomy approaches 1) undersized (two-step down) 2) subcrestal 3) osteotome technique 4) bicortical anchorage. Primary stability of all the implants placed was measured using RFA test. The results were statistically analyzed and highest mean ISQ value was observed when implants were placed under bicortical anchorage. Implants when placed under bicortical anchorage achieved better primary stability and hence this osteotomy approach can be followed in areas where primary stability is expected to be compromised.

Primary Implant Stability Analysis of Different Dental Implant Connections and Designs-An In Vitro Comparative Study.

Primary implant stability can be evaluated at the time of placement by measuring the insertion torque (IT). However, another method to monitor implant stability over time is resonance frequency analysis (RFA). Our aim was to examine the effect of bone type, implant design, and implant length on implant primary stability as measured by IT and two RFA devices (Osstell and Penguin) in an in vitro model. Ninety-six implants were inserted by a surgical motor in an artificial bone material, resembling soft and dense bone. Two different implant designs—conical connection (CC) and internal hex (IH), with lengths of 13 and 8 mm, were compared. The results indicate that the primary stability as measured by RFA and IT is significantly increased by the quality of bone (dense bone), and implant length and design, where the influence of dense bone is similar to that of CC design. Both the Osstell and Penguin devices recorded higher primary implant stability for long implants in dense bone, favoring the CC over the IH implant design. The CC implant design may compensate for the low stability expected in soft bone, and dense bone may compensate for short implant length if required by the anatomical bone conditions.

Wedge Shaped vs Round Implants: Bone Strain During the Insertion Process.

A novel implant system resembling the shape of a wedge and employing piezosurgery for implant bed preparation has been introduced with the aim of solving the problem of horizontal bone deficiency. This in vitro study compared emerging bone strain during insertion of a conventionally round implant vs the wedge implant. Adhering to the manufacturers' protocols, implant surgery was performed in polyurethane foam blocks equipped with strain gauges attached to the buccal and occlusal surfaces. Five implants per group were placed while strain development during insertion was recorded. Primary implant stability was determined using resonance frequency analysis. Statistical analysis was based on Welch's 2-sample tests (α = 0.05). In general, greater strain development was found on the buccal aspect of bone compared to the occlusal aspect with an overall range between -724 μm/m and 9132 μm/m. A stepwise increase in strain development was seen in the wedge implants while, in the round implants, a continuous increase in strain development was recorded. Absolute strain development on the buccal aspect of bone was significantly greater in wedge implants (P = .0137) while, on the occlusal aspect, significantly lower strain development was seen for wedge implants (P = .0012). Primary stability of wedge implants was significantly lower compared to round implants (P = .0005). Wedge implants differ from round implants with respect to the insertion process characterized by a stepwise increase in bone deformation. High strain development in buccal bone may constitute a risk factor for bone resorption and should be avoided by reducing the degree of underpreparation of the implant site.

Orthodontic mini implant and their primary stability: A comparative study

Background: Mini implants has been widely used now a days as anchorage for achieving best orthodontic outcome. Good primary stability of mini implants is key for their success. Two type of mini implant (one single threaded and other double threaded) were used for this study, insertion torque and removal torque was evaluated.Material and Method: 40 patients were selected and two equal (n=20) groups were formed. In first group (group1) single threaded mini implants were used, in second group (group 2) double threaded mini implants were used. Maximum insertion torque (m.i.t) and removal torque (m.r.t) were recorded for two groups. Statistical analysis was done.Results: Torque was compared in both group. Max. Insertion torque (mit) was found higher than max. Removal torque (mrt) for both the groups and between the groups. Higher values for m.i.t than m.r.t was found in intergroup comparison.Conclusion: Mini screws are effective for temporary anchorage device. Double threaded mini implants has more insertion and removal torque, so they have better primary stability.