Primary Stability Of Mini-implants Research Articles

In-vitro investigation of primary stability of orthodontic mini implants with different lengths using resonance frequency analysis

Out of various ways of gaining anchorage, mini implants are gaining attention due to its minimum compliance and maximum curative effects.Mini implants are considered successful if they have sufficient primary stability that comes from mechanical interlocking of mini implant with the bone.Factors which influence the implant stability are bone physiology, implant size, shape and surface characteristics. Considering all other factors within anatomic constraints, what may play a role in primary stability of mini implants is length. Literature search to correlate mini implant length with primary stability was found to be insufficient and hence this study was undertaken. In this study, two goat jaws were subjected to spiral 3D CT scan and the areas with D2 bone density were identified and marked. In these D2 density marked areas, 30 implants of 1.5 x 6mm (GROUP A) and 30 implants of 1.5 x8mm (GROUP B) were placed. Their stability was measured by Radio Frequency Analysis using Osstell ISQ device with its Smart Peg. A connector was fabricated to make the fit of smart peg compatible with the head of mini implant. Readings were made in 5 different directions for each implant and their average value was considered as final reading. It was noted that primary mini implant stability is significantly higher (p 0.034) with GROUP B implants than with GROUP A implants. The increased length of mini-implants positively affects its primary stability and should be taken into consideration when implants are used as anchorage devices.

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.

Effects of a Mini Implant’s Size and Site on its Stability Using Resonance Frequency Analysis

Aim: Temporary anchorage devices (TADs) have become the preferred method of skeletal anchorage in new-age orthodontics. Despite the remarkable success of mini implants in orthodontic treatment results, mini implants’ stability remains a vital issue that has to be resolved, due to the fact that failure rates are broadly variable and might be up to 25%. Objectives: To evaluate the effect of the diameter, implant bone surface contact, thickness of cortical bone, and implant insertion sites on mini implant stability using resonance frequency analysis (RFA). Materials and Method: CBCT of the dry skull was obtained. Buccal and lingual cortical plates of the maxillary and mandibular jaws were measured at 6 mm from the coronal part of the alveolar bone. After placing the implants, the stability was measured using resonance frequency analysis. Results: In the maxillary arch, Pearson correlation showed significant correlation of instability of the implant with the width of the buccal cortical plate and lingual cortical plate and implant contact surface area. In mandibular arch, Pearson correlation showed no significant effect of buccal/lingual cortical plate width, and implant surface contact area in primary stability of varied sized, mini implants. Conclusion: Statistically significant increases in the primary stability of mini implants with an increase in the implant bone contact surface area were found in the maxilla. In the mandible, no significant increase in mini implant stability was found with an increase in the implant contact surface area.

Evaluation and Comparison of Root Proximity of Maxillary and Mandibular Interradicular Sites for Mini Implant Placement Using Orthopantomogram and Cone Beam Computed Tomography

The purpose of this study is to evaluate and compare the root proximity of maxillary and mandibular inter radicular sites using orthopantomogram (OPG) and cone beam computed tomograph (CBCT) for the primary stability of mini implants. The cone beam computed tomographic images and orthopantomographic images of 70 subjects were taken. The interdental sites from distal of canine to mesial of second molar are examined for root proximity. The root proximity was measured at four levels from cementoenamel junction in 70 CBCT and OPG images. The results showed a statistically significant difference between the values obtained from CBCT and OPG images; the root proximity was least 6mm above the cementoenamel junction in maxilla and mandible in the range of 1.09–3.62mm, 1.45–4.17 mm respectively. The study concluded that CBCT images are more accurate and reliable. At 5mm from CEJ in the region between the first molar and second premolar in maxilla and in the area between first molar to first premolar in mandible the root proximity is least and adequate for mini implant placement.

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 >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.

The effect of cortical bone thickness on the primary stability of miniscrews, using CBCT (Cross-sectional clinical trial)

Objectives: The aim of the present study was to determine the correlation between the thickness of both cortical bone thickness, total bone thickness and the primary stability of mini-implants. Methods: Twenty-six mini-screws (Absoanchor) were inserted into the buccal alveolar bone between the roots of the second premolar and first molar on the right and left side of the patient. The mobility of the mini-screws was clinically assessed using the periotest device and the buccal cortical bone thickness of the maxilla was measured on the right and left side in the inter-radicular area between the second premolar and first molar at the site of the miniscrew insertion. The patient’s head was oriented in all 3 spatial planes by adjusting the Frankfort plane horizontal and the orbital plane parallel to the floor. Results: There was a statistical significant differences between mean measurements of the cortical bone thickness penetrated by the mini-screw and the negative stability scores. (P=0.03) Conclusions: There was a weak correlation between the primary stability of the mini-screw and the cortical bone thickness. However, a minimum thickness of 1.0 mm cortical bone thickness is necessary for adequate stability.

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.

Histomorphometric analysis of microcrack healing after the installation of mini-implants

The goal of this study was to investigate the histomorphometric characteristics of the healing process of microcracks in the cortical bone after the installation of mini-implants (MIs). Self-drilling MIs were inserted into the tibial diaphysis of twelve adult male New Zealand rabbits. Four MIs per rabbit were placed randomly. The animals were divided into four groups according to the length of the healing period: group A was sacrificed immediately, group B was sacrificed after one week, group C was sacrificed after two weeks, and group D was sacrificed after four weeks. Cortical bone thickness was measured using micro-computed tomography, and histomorphometric analyses of the cumulative length of the microcracks (CLCr) and the total number of microcracks (NCr) were performed using hematoxylin and eosin staining. The microcracks were radially and concentrically aligned in the peri-MI bone. The CLCr decreased significantly one week after the surgery, mainly due to healing of the concentrically aligned microcracks. The CLCr showed another significant decrease from two weeks after the surgery to four weeks after the surgery, mainly reflecting healing of the radially aligned microcracks. A statistically significant decrease in the NCr occurred as the microcracks healed from zero weeks to two weeks. However, no significant difference in the NCr was found between groups C and D. In order to improve the primary stability of MIs, delayed loading and a healing period of a certain length are recommended to ensure the optimal healing of microcracks and bone remodeling.

Does cortical thickness influence the primary stability of miniscrews?:A systematic review and meta-analysis

To investigate whether there is evidence to support the association between cortical thickness (CtTh) and the primary stability of mini-implants (MI). A search was performed including articles published until September 2013. The inclusion criteria comprised observational clinical studies conducted in patients who received monocortical MI for orthodontic anchorage and in vivo or ex vivo experimental studies performed to evaluate the primary stability of MI, studies that evaluated the association between CtTh and MI primary stability, CtTh measurement performed numerically, and MI primary stability evaluated by implant stability quotient value, Periotest value , pull-out strength, or insertion torque. Studies conducted exclusively in artificial bone or finite elements were excluded. Abstract and title reading identified 15 possible articles to be included. After reading the complete text, three were excluded. One article was found by hand searching and another excluded for an overlapping sample. Finally, 12 articles were selected. A positive correlation was found between primary stability and CtTh when studies that evaluated primary stability through PS were grouped (r = .409) and when studies that evaluated stability in humans were grouped (r = .338). There is a positive association between MI primary stability and CtTh of the receptor site. However, there is still a lack of well-designed clinical trials.

Accelerated Tooth Movement and Temporary Skeletal Anchorage Devices (TSADs).

Accelerated Tooth Movement and Temporary Skeletal Anchorage Devices (TSADs).

Is trabecular bone related to primary stability of miniscrews?

To compare the primary stability of miniscrews inserted into bone blocks of different bone mineral densities (BMDs) with and without cortical bone, and investigate whether some trabecular properties could influence primary stability. Fifty-two bone blocks were extracted from fresh bovine pelvic bone. Four groups were created based on bone type (iliac or pubic region) and presence or absence of cortical bone. Specimens were micro-computed tomography imaged to evaluate trabecular thickness, trabecular number, trabecular separation, bone volume density (BV/TV), BMD, and cortical thickness. Miniscrews 1.4 mm in diameter and 6 mm long were inserted into the bone blocks, and primary stability was evaluated by insertion torque (IT), mini-implant mobility (PTV), and pull-out strength (PS). Intergroup comparison showed lower levels of primary stability when the BMD of trabecular bone was lower and in the absence of cortical bone (P≤.05). The Pearson correlation test showed correlation between trabecular number, trabecular thickness, BV/TV, trabecular BMD, total BMD, and IT, PTV, and PS. There was correlation between cortical thickness and IT and PS (P≤.05). Cancellous bone plays an important role in primary stability of mini-implants in the presence or absence of cortical bone.

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.

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.