Primary Stability Of Orthodontic Mini-implants Research Articles

Significance of bone morphology and quality on the primary stability of orthodontic mini-implants: in vitro comparison between human bone substitute and artificial bone.

This study evaluated artificial bone models against ahuman bone substitute to assess the primary stability of orthodontic mini-implants (OMIs) at varying implant sites with different morphologies and qualities. Atotal of 1200 OMI placements of four types were inserted into four artificial bone models of different density (D1, D2, D3, D4) and into ahuman bone substitute (HB). The implants varied in diameter (2.0 and 2.3 mm) and length (9and 11 mm). Each specimen had four implant sites: no defect, one-wall defect, three-wall defect, and circular defect. The implant stability quotient (ISQ) values were measured using resonance frequency analysis (RFA) and insertion placement torque values (IPT) were assessed for primary stability. Correlation analysis was performed to evaluate the different models. The highest IPT value was registered for the 2.0 mm × 11 mm implant inserted into D1 with no defect (37.53 ± 3.02 Ncm). The lowest ISQ value was measured for the 2.3 mm × 9 mm OMI inserted into D3 with acircular defect (12.33 ± 5.88) and the highest for the 2.3 mm × 9 mm implant inserted into HB with no defect (63.23 ± 2.57). Astrong correlation (r = 0.64) for IPT values and avery strong correlation (r = 0.8) for ISQ values was found between D2 and HB. Bone defects and bone quality affected the primary stability of implants in terms of ISQ and IPT values. Results for bone model D2 correlated very well with the HB substitution material.

Impact of Implant Design and Bone Properties on the Primary Stability of Orthodontic Mini-Implants

This study investigated the correlation between bone characteristics, the design of orthodontic mini-implants, the pull-out force, and primary stability. This experimental in vitro study has examined commercial orthodontic mini-implants of different sizes and designs, produced by two manufacturers: Tomas-pin SD (Dentaurum, Ispringen, Germany) and Perfect Anchor (Hubit, Seoul, Korea). The total number of 40 mini-implants were tested. There are two properties that are common to all tested implants—one is the material of which they are made (titanium alloy Ti-6Al-4V), and the other is the method of their insertion. The main difference between the mini-implants, which is why they have been selected as the subject of research in the first place, is reflected in their geometry or design. Regardless of the type of implant, the average pull-out forces were found to be higher for a cortical bone thickness (CBTC) of 0.62–0.67 mm on average, compared to the CBTC < 0.62 mm, where the measured force averages were found to be lower. The analysis of variance tested the impact of the mini-implant geometry on the pull-out force and proved that there is a statistically significant impact (p < 0.015) of all three analyzed geometric factors on the pull-out force of the implant. The design of the mini-implant affects its primary stability. The design of the mini-implant affects the pulling force. The bone quality at the implant insertion point is important for primary stability; thus, the increase in the cortical bone thickness increases the value of the pulling force significantly.

The Effect of Insertion Angle on Primary Stability of Orthodontic Mini-implants "An Experimental in vivo Study"

The Effect of Insertion Angle on Primary Stability of Orthodontic Mini-implants "An Experimental in vivo Study"

Predicting primary stability of orthodontic mini-implants, according to position, screw-size, and bone quality, in the maxilla of aged patients: a cadaveric study.

This study aimed to evaluate the effect of implant size and bone condition on primary stability of orthodontic mini-implants with a view to predict the primary stability before insertion. Four-hundred and forty mini-implants of two different diameters (2.0 and 2.3mm) and lengths (7 and 12mm) were inserted at 11 different positions in human cadaver maxillae. Before placement of mini-implants, cone beam computed tomography (CBCT) scans were performed to measure bone density and cortical thickness and, after mini-implant placement, implant stability quotient (ISQ) values were determined by resonance frequency analysis and cofactors were analyzed to determine their influence on the primary stability. Additionally, an equation was developed to predict the expected stability based on implant size and bone quality. Bone density varied between 433(SD122) and 587(SD249) Hounsfield units (HU), and cortical thickness varied between 0.49(SD0.42) and 0.98(SD0.60)mm. The lowest ISQ value, of 15.50(SD7.29) (bone density: 531 (SD219) HU; cortical thickness: 0.65(SD0.58)mm), was found for a mini-implant of 2.0×7mm and the highest ISQ value, of 46.30(SD8.69) (bone density: 587(SD249) HU; cortical thickness: 0.98(SD0.60)mm), was found for a mini-implant of 2.3×11mm. Statistically significant influences of the cofactors on primary stability were demonstrated. To visualize the predictive power of the model, the observed values versus the predicted values of primary stability were compared and the model fit was represented by residual plots. The expected primary stability can be estimated by a linear regression model comprising the radiologically determined bone density, cortical thickness, implant length and diameter, and placement position.

Effects of cortical bone thickness and trabecular bone density on primary stability of orthodontic mini-implants

Background/purposeMini-implant screws are now routinely used as anchorage devices in orthodontic treatments. This study used synthetic bone models to investigate how the primary stability of an orthodontic mini-implant (OMI) as measured by resonance frequency (RF) is affected by varying cortical bone thickness and trabecular bone density. Materials and methodsThree synthetic cortical shells (thicknesses of 1, 2, and 3 mm) and three polyurethane foam blocks (densities of 40, 20, and 10 pound/cubic foot) were used to represent jawbones of varying cortical bone thicknesses and varying trabecular bone densities. Twenty-five stainless steel OMIs (2 × 10 mm) were sequentially inserted into artificial bone blocks to depths of 2, 4, and 6 mm. Five experimental groups of bone blocks with OMIs were examined by Implomates® RF analyzer. Statistical and correlation analyses were performed by Kruskal-Wallis test, Wilcoxon rank-sum test, and simple linear regression. ResultsAs trabecular bone density decreased, RF decreased; as cortical bone thickness decreased, RF also decreased. Simple linear regression analysis showed highly linear correlations between trabecular bone density and RF (R2 > 0.99; P < 0.0001) and between cortical bone thickness and RF (R2 > 0.98; P < 0.0001). ConclusionThe stability of an OMI at the time of placement is influenced by both cortical bone thickness and trabecular bone density. Both cortical bone thickness and trabecular bone density have strong linear correlations with RF.

Investigation of the optimal design of orthodontic mini-implants based on the primary stability: A finite element analysis.

Background. The design of an orthodontic mini-implant is a significant factor in determining its primary stability and its clinical success. The aim of this study was to measure the relative effect of mini-implant design factors on primary stability of orthodontic mini-implants. Methods. Thirty-two 3-dimensional assemblies of mini-implant models with their surrounding bone were generated using finite element analysis software. The maximum displacement of each mini-implant model was measured as they were loaded with a 2-N horizontal force. Employing Taguchi’s design of experiments as a statistical method, the contribution of each design factor to primary stability was calculated. As a result of the great effect of the upper diameter and length, to better detect the impact of the remaining design factors, another set of 25 models with a fixed amount of length and diameter was generated and evaluated. Results. The diameter and length showed a great impact on the primary stability in the first set of experiments (P<0.05). According to the second set of experiments, increased taper angle in the threaded and non-threaded area decreased the primary stability. There was also an optimum amount of 2.5 mm for threaded taper length beyond which the primary stability decreased. Conclusion. It is advisable to increase the diameter and length if primary stability is at risk. In the second place, a minimum amount of taper angle, both in the threaded and non-threaded area with an approximate proportion of 20% of threaded taper length to MI length, would be desirable for MIs with a moderate size.

Measurement of Primary Stability of Mini Implants Using Resonance Frequency Analysis

Introduction In the last decade, anchorage control with mini-implants has gained enormous credibility in maintaining orthodontic anchorage. Resonance frequency analysis (RFA) has proven to be an adequate method to measure the stability of these mini-implants because of its non-invasiveness and contactless measurement method. Materials and Method Tomas and S.K surgical mini-implants were tested. For this purpose custom fabricated attachment was fabricated to attach the smart peg on orthodontic mini-implant head, and 45 mini-implants were inserted in fresh swine pelvic bone in the density matched sites to that of most common sites where mini-implants are placed in human mandible. Mini-implants of two different lengths with diameter constant were also placed to assess the effect of length on primary stability. Results The mean ISQ of Group 1 (Tomas 10 mm) was 55.53±3.39 while that of Group 2 (S.K Surgical 10mm) was 56.63±3.48 and that of Group 3(S.K Surgical 8 mm) was 55.90±3.48. Difference among the groups were not statistically significant when ANOVA test was used (P &gt;0.05). Conclusion The resonance frequency analysis is applicable to comparatively assess the primary stability of orthodontic mini-implants. There was no difference in primary stability of Tomas and S.K Surgical mini-implant and primary stability was not affected by the length of the mini-implant.

Er:YAG laser, piezosurgery, and surgical drill for bone decortication during orthodontic mini-implant insertion: primary stability analysis\u2014an animal study

It is important to identify factors that affect primary stability of orthodontic mini-implants because it determines the success of treatment. We assessed mini-implant primary stability (initial mechanical engagement with the bone) placed in pig jaws. We also assessed mini-implant insertion failure rate (mini-implant fracture, mini-implants to root contact). A total of 80 taper-shaped mini-implants (Absoanchor® Model SH1312-6; Dentos Inc., Daegu, Korea) 6 mm long with a diameter of 1.1 mm were used. Bone decortication was made before mini-implant insertion by means of three different methods: Group G1: Er:YAG laser (LiteTouch®, Light Instruments, Yokneam, Israel) at energy of 300 mJ, frequency 25 Hz, fluence 38.2 J/cm2, cooling 14 ml/min, tip 1.0 × 17 mm, distance 1 mm, time of irradiation 6 s; Group G2: drill (Hager & Meisinger GmbH, Hansemannstr, Germany); Group G3: piezosurgery (Piezotom Solo, Acteon, NJ, USA). In G4 group (control), mini-implants were driven by a self-drilling method. The primary stability of mini-implants was assessed by measuring damping characteristics between the implant and the tapping head of Periotest device (Gulden-Medizinteknik, Eschenweg, Modautal, Germany). The results in range between − 8 to + 9 allowed immediate loading. Significantly lower Periotest value was found in the control group (mean 0.59 ± 1.57, 95% CI 0.7, 2.4) as compared with Er:YAG laser (mean 4.44 ± 1.64, 95% CI 3.6, 5.3), piezosurgery (mean 17.92 ± 2.73, 95% CI 16.5, 19.3), and a drill (mean 5.91 ± 1.52, 95% CI 5.2, 6.6) (p < 0.05). The highest failure rate (33.3%) during mini-implant insertion was noted for self-drilling method (G4) as compared with G1, G2, and G3 groups (p < 0.05). The small diameter decortication by Er:YAG laser appeared to provide better primary stability as compared to drill and piezosurgery. Decortication of the cortical bone before mini-implant insertion resulted in reduced risk of implant fracture or injury of adjacent teeth. The high initial stability with a smaller diameter of the mini-implant resulted in increased risk of fracture, especially for a self-drilling method.

Influence of different implant materials on the primary stability of orthodontic mini-implants

This study evaluates the influence of different implant materials on the primary stability of orthodontic mini-implants by measuring the resonance frequency. Twenty-five orthodontic mini-implants with a diameter of 2 mm were used. The first group contained stainless steel mini-implants with two different lengths (10 and 12 mm). The second group included titanium alloy mini-implants with two different lengths (10 and 12 mm) and stainless steel mini-implants 10 mm in length. The mini-implants were inserted into artificial bones with a 2-mm-thick cortical layer and 40 or 20 lb/ft3 trabecular bone density at insertion depths of 2, 4, and 6 mm. The resonance frequency of the mini-implants in the artificial bone was detected with the Implomates® device. Data were analyzed by two-way analysis of variance followed by the Tukey honestly significant difference test (α = 0.05). Greater insertion depth resulted in higher resonance frequency, whereas longer mini-implants showed lower resonance frequency values. However, resonance frequency was not influenced by the implant materials titanium alloy or stainless steel. Therefore, the primary stability of a mini-implant is influenced by insertion depth and not by implant material. Insertion depth is extremely important for primary implant stability and is critical for treatment success.

An in vitro study of factors affecting the primary stability of orthodontic mini-implants

To evaluate the effects of mini-implant features (length, design, core diameter), insertion technique (insertion angle, cortical punch), and cortical bone depth and density on mini-implant primary stability. The effect of mini-implant reinsertion was also investigated. Two hundred and sixty Infinitas mini-implants of two lengths (9 mm and 6 mm), two core diameters (0.8 mm and 0.9 mm) for an external diameter of 1.5 mm, and four designs (two tapered, external diameter 1.5 mm; two cylindrical, external diameters 1.5 mm and 2.0 mm) were inserted into synthetic bone blocks, and the maximum insertion torque (MIT) was recorded. The cortical layer of the blocks varied in density (30 and 50 lb per cubic foot) and depth (1 mm and 2 mm). Three angles of insertion (90°, 75°, and 60°) and two methods of insertion (direct and cortical punch) were tested. Forty mini-implants were also removed and reinserted. A significant increase in the average MIT occurred when cortical bone density increased and when mini-implants were reinserted. The 1.5 mm diameter cylindrical design had significantly lower MIT than the 1.5 mm tapered and the 2.0 mm cylindrical designs. The other variables did not have a significant effect on MIT. Mini-implants achieved greater primary stability in higher-density cortical bone, and the 1.5 mm diameter tapered and 2.0 mm cylindrical designs offered greater primary stability than the 1.5 mm cylindrical design. Reinserting mini-implants resulted in significantly increased MIT, possibly because of blunting of the threads.

Primary stability of orthodontic mini-implants inserted into maxilla and mandible of swine

The objective of this study was to assess the primary stability of different orthodontic mini-implants inserted into different maxillary and mandibular regions of swine. One hundred eighty orthodontic mini-implants produced by 5 different manufacturers, all presenting several shapes, were divided into 5 groups: Mondeal (M), Neodent (N), SIN (S), INP, and Titanium Fix (T). Fifteen pigs (Sus scrofa piau) were used for study and 12 mini-implants were inserted into 3 mandibular and maxillary regions. After insertion, the animals were killed and osseous blocks containing the mini-implants were obtained for mechanical pullout tests to be performed by a universal test machine at cross-head speed of 0.5 mm/s. Maximum force values (N/cm) for insertion were recorded and submitted to both analysis of variance and Tukey's test. The primary stability provided by cylindrical mini-implants (groups M and I) was statistically significantly superior to that of conical mini-implants (groups N and S). On the other hand, screw-type mini-implants were shown to be statistically inferior compared with the others (P < .05). Statistical differences between pullout forces at different oral cavity regions were also found (P < .05). The mini-implants inserted into palatal suture had lesser stability, whereas those inserted into upper molar and premolar regions were shown to be more stable. The shape of mini-implants, in association with location of insertion, is directly related to primary stability.

Impact of Insertion Depth and Predrilling Diameter on Primary Stability of Orthodontic Mini-implants

To test the hypothesis that the impact of the insertion depth and predrilling diameter have no effect on the primary stability of mini-implants. Twelve ilium bone segments of pigs were embedded in resin. After implant site preparation with different predrilling diameters (1.0, 1.1, 1.2, and 1.3 mm), Dual Top Screws 1.6 x 10 mm (Jeil, Korea) were inserted with three different insertion depths (7.5, 8.5, and 9.5 mm). The insertion torque was recorded to assess primary stability. In each bone, five Dual Top Screws were used as a reference to compensate for the differences of local bone quality. Both insertion depth and predrilling diameter influenced the measured insertion torques distinctively: the mean insertion torque for the insertion depth of 7.5 mm was 51.62 Nmm (+/-25.22); for insertion depth of 8.5 mm, 65.53 Nmm (+/-29.99); and for the insertion depth of 9.5 mm, 94.38 Nmm (+/-27.61). The mean insertion torque employing the predrill 1.0 mm was 83.50 Nmm (+/-33.56); for predrill 1.1 mm, 77.50 Nmm (+/-27.54); for the predrill 1.2 mm, 61.70 Nmm (+/-28.46); and for the predrill 1.3 mm, 53.10 (+/-32.18). All differences were highly statistically significant (P < .001). The hypothesis is rejected. Higher insertion depths result in higher insertion torques and thus primary stability. Larger predrilling diameters result in lower insertion torques.

Insertion Angle Impact on Primary Stability of Orthodontic Mini-Implants

To analyze the impact of the insertion angle on the primary stability of mini-implants. A total of 28 ilium bone segments of pigs were embedded in resin. Two different mini-implant sizes (Dual-Top Screw 1.6 x 8 mm and 2.0 x 10 mm) were inserted at seven different angles (30 degrees , 40 degrees , 50 degrees , 60 degrees , 70 degrees , 80 degrees , and 90 degrees ). The insertion torque was recorded to assess primary stability. In each bone, five Dual-Top Screws were used to compensate for differences in local bone quality. The angle of mini-implant insertion had a significant impact on primary stability. The highest insertion torque values were measured at angles between 60 degrees and 70 degrees (63.8 degrees for Dual-Top 1.6 mm and 66.7 degrees for Dual-Top 2.0 mm). Very oblique insertion angles (30 degrees ) resulted in reduced primary stability. To achieve the best primary stability, an insertion angle ranging from 60 degrees to 70 degrees is advisable. If the available space between two adjacent roots is small, a more oblique direction of insertion seems to be favorable to minimize the risk of root contact.

Impact of Implant Design on Primary Stability of Orthodontic Mini-implants

Skeletal anchorage with mini-implants has greatly broadened the treatment possibilities in orthodontics over the last few years. To reduce implant failure rates, it is advisable to obtain adequate primary stability. The aim of this study was to quantitatively analyze the impact of implant design and dimension on primary stability. Forty-two porcine iliac bone segments were prepared and embedded in resin. To evaluate the primary stability, we documented insertion torques of the following mini-implants: Aarhus Screw, AbsoAnchor, LOMAS, Micro-Anchorage-System, ORLUS and Spider Screw. In each bone, five Dual Top Screws were inserted for reference purposes to achieve comparability among the specimens. We observed wide variation in insertion torques and hence primary stability, depending on mini-implant design and dimension; the great impact that mini-implant diameter has on insertion torques was particularly conspicuous. Conical mini-implants achieved higher primary stabilities than cylindrical designs. The diameter and design of the mini-implant thread have a distinctive impact on primary stability. Depending on the region of insertion and local bone quality, the choice of the mini-implant design and size is crucial to establish sufficient primary stability.

Parameters Affecting Primary Stability of Orthodontic Mini-implants

Treatment options in orthodontics have been expanded by skeletal anchorage via mini-implants over the last few years. Sufficient primary stability is imperative to minimize implant loss rate. The aim of this study was to quantitatively analyze the factors influencing primary stability: bone quality, implant-design, diameter, and depth of pilot drilling. Thirty-six pelvic bone segments (ilium) of country pigs were dissected and embedded in resin. To determine the primary stability, we measured the insertion torque of five different mini-implant types (tomas-pin [Dentaurum, Ispringen, Germany] 08 and 10 mm, and Dual Top [Jeil Medical Corporation, Seoul, Korea] 1.6 x 8 and 10 mm plus 2 x 10 mm). Twenty-five or 30 implants were inserted into each pelvic bone segment following preparation of the implant sites using pilot drill diameters of 1.0, 1.1, 1.2 and 1.3 mm and pilot drill depths of 1, 2, 3, 6 and 10 mm. Five implants were inserted for reference purposes to establish comparability. Thicknesses of bone compacta were measured via micro-computer tomography. Insertion torques of orthodontic mini-implants and therefore primary stability varied greatly, depending on bone quality, implant-design, and preparation of implant site. Compared with the tomas-pin, the Dual Top screw showed significantly greater primary stability. Torque moments beyond 230 Nmm caused fractures of 9 Dual Top screws. Compacta thickness, implant design and implant site preparation have a strong impact on the primary stability of mini-implants for orthodontic anchorage. Depending on the insertion site and local bone quality, the clinician should choose an optimum combination of implant and pilot-drilling diameter and depth.