Mechanical properties of self-drilling orthodontic micro-implants with different diameters

Objective: To compare the stability and clinical applicability of a novel orthodontic mini-implant design (N2) with the most widely used commercially available (CA) design. Materials and Methods: Two groups of mini-implants were tested: a CA design (1.5-mm diameter, 6-mm length) and N2 (3-mm diameter, 2-mm length, tapered shape). Implants were inserted in bone blocks of cortical bone simulation with varying densities (20 pounds per cubic foot [pcf], 30 pcf, and 40 pcf). A torque test was used to measure maximum insertion torque (MIT) and maximum removal torque (MRT). Compression and tension force vectors were applied at angles of 10u, 20u, 30u, and 40u using customized load pins to determine primary stability. Results: Mean MIT and MRT were higher in the N2 than the CA design at all three cortical bone densities except MRT in 20 pcf bone (not statistically significant). The mean compression force required to displace the N2 at all distances and angulations was greater for the N2 than the CA design. At all displacement distances, the highest mean tension force required for N2 displacement was at 10u angulation, whereas at 30u and 40u, the mean tension force required to displace the CA design was greater. Conclusions: The primary stability of the N2 is superior to that of the CA design and is promising for both orthodontic and orthopedic clinical applicability, especially under compression force. The short length of the N2 reduces risk of damage to anatomic structures and root proximity during placement and orthodontic treatment. The stability of the N2 may be compromised in areas of high bone density and highly angulated tension force. (Angle Orthod. 2013;83:832-841.)

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“…22 and 20-mm thick, 10-pcf trabecular bone (Table 1). A 1-mm thick acrylic sheet was used to simulate soft tissue thickness.…”

Section: Methodsmentioning

confidence: 99%

“…25 The mean MIT of the N2 reached as high as 19.3 Ncm in 40 pcf cortical bone density, exceeding the physiological limit of 14.65 Ncm. 22 Evidently, the N2 is not ideal for insertion into areas of very high bone density.…”

Section: 23mentioning

confidence: 99%

Mechanical stability and clinical applicability assessment of novel orthodontic mini-implant design

Song¹,

Hong

Banh

et al. 2013

The Angle Orthodontist

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“…The tapered and hollow interior of N2 likely diminished bone friction experienced during placement of N1 and thus further decreased insertion torque. An insertion torque range of 3.28 to 14.65 Ncm without implant breakage and bone fracture was identified, 27 and N2's mean MIT was within this physiologic limit, while N1's mean MIT exceeded this range. Insertion torque needs to be balanced as high insertion torque was found to cause tensile and compressive stress to both cortical and cancellous bone tissue, and excessive stress could cause irreversible damage to the bone.…”

Section: Discussionmentioning

confidence: 99%

Mechanical stability assessment of novel orthodontic mini-implant designs: Part 2

Hong¹,

Truong²,

Song³

et al. 2011

The Angle Orthodontist

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; Won Moon a ABSTRACT Objective: To assess the mechanical stability of a newly revised orthodontic mini-implant design (N2) compared with a design introduced in Part 1 of the study (N1) and the most widely-used commercially-available design (CA). To evaluate the mean buccal bone thickness of maxillary and mandibular posterior teeth using cone-beam computed tomography (CBCT). Materials and Methods: From the CBCT scans of 20 patients, six tomographic cross-sections were generated for each tooth. Buccal bone thickness was measured from the most convex point on the bone to the root surface. CA (1.5 mm in diameter and 6 mm in length), N1, and N2 (shorter and narrower than N1) were inserted in simulated bone with cortical and trabecular bone layers. Mechanical stability was compared in vitro through torque and lateral displacement tests. Results: The bone thickness ranged from 2.26 to 3.88 mm. Maximum insertion torque was decreased significantly in N2 compared to N1. However, force levels for all displacement distances and torque ratio were the highest in N2, followed by N1 and CA (a 5 .05). Conclusions: Both torque and lateral displacement tests highlighted the enhanced stability of N2 compared with CA. Design revisions to N1 effectively mitigated N1's high insertion torque and thus potentially reduced microdamage to the surrounding bone. The N2 design is promising as evidenced by enhanced stability and high mechanical efficiency. Moreover, N2 is not limited to placement in interradicular spaces and has the capacity to be placed in the buccal bone superficial to the root surface with diminished risk of endangering nearby anatomic structures during placement and treatment. (Angle Orthod. 2011;81:1001-1009

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“…The quality of artificial bone block represented by the different thickness of high-density polyurethane styrofoam seems to be an important factor in estimating the resistance of the mini-screw at removal. [18][19][20] Since the removal torque values of the current in vitro study were measured immediately following the insertion and did not take into account the biological effect of osseointegration of the self-tapping mini-screw, the maximum removal torque, total removal energy, and the angular momentum of removal estimated by an in vitro study will certainly be different from those estimated by an in vivo study. In addition, clinical variability factors such as difference of precession motion, rpm, the operative hand-gripping mode, and the pressure level during the insertion of mini-implants could be easily controlled in the current in vitro study.…”

Section: Discussionmentioning

confidence: 99%

The effects of different pilot-drilling methods on the mechanical stability of a mini-implant system at placement and removal: a preliminary study

Cho

Choo²,

Kim

et al. 2011

Korean J Orthod

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Objective: To investigate the effects of different pilot-drilling methods on the biomechanical stability of self-tapping mini-implant systems at the time of placement in and removal from artificial bone blocks. Methods: Two types of artificial bone blocks (2-mm and 4-mm, 102-pounds per cubic foot [102-PCF] polyurethane foam layered over 100-mm, 40-PCF polyurethane foam) were custom-fabricated. Eight mini-implants were placed using the conventional motor-driven pilot-drilling method and another 8 mini-implants were placed using a novel manual pilot-drilling method (using a manual drill) within each of the 2-mm and 4-mm layered blocks. The maximum torque values at insertion and removal of the mini-implants were measured, and the total energy was calculated. The data were statistically analyzed using linear regression analysis. Results: The maximum insertion torque was similar regardless of block thickness or pilot-drilling method. Regardless of the pilot-drilling method, the maximum removal torque for the 4-mm block was statistically higher than that for the 2-mm block. For a given block, the total energy at both insertion and removal of the mini-implant for the manual pilot-drilling method were statistically higher than those for the motor-driven pilot-drilling method. Further, the total energies at removal for the 2-mm block was higher than that for the 4-mm block, but the energies at insertion were not influenced by the type of bone blocks. Conclusions: During the insertion and removal of mini-implants in artificial bone blocks, the effect of the manual pilot-drilling method on energy usage was similar to that of the conventional, motor-driven pilot-drilling method.

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Mechanical properties of self-drilling orthodontic micro-implants with different diameters

Cited by 47 publications

References 18 publications

Mechanical stability and clinical applicability assessment of novel orthodontic mini-implant design

Mechanical stability and clinical applicability assessment of novel orthodontic mini-implant design

Mechanical stability assessment of novel orthodontic mini-implant designs: Part 2

The effects of different pilot-drilling methods on the mechanical stability of a mini-implant system at placement and removal: a preliminary study

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