Histomorphometric and mechanical analyses of the drill-free screw as orthodontic anchorage

Self Cite

Objective: To determine the histological reaction of the root and bone as a mini-implant approaches the root. Materials and Methods: Two kinds of mini-implants were inserted into the buccal alveolar bone of 4 beagles (2 males and 2 females). The specimens were classified as the near-root group, the PDL contact group, the root contact group, and the root perforation group. Cementum resorption, dentin resorption, cementum repair, cementum growth, ankylosis, root cracking, and root fracture were assessed as the implant neared the root. Results: The incidence of root resorption increased when the mini-implant was less than 0.6 mm from the root in the near-root group and PDL contact group. Root cracking and root fracture occurred in the root contact group and root perforation group. Bone resorption and ankylosis were observed in some specimens. However, some specimens of the PDL contact group and root contact group had cementum growth or little root resorption despite proximity to the root. In the root perforation group, root resorption and ankylosis occurred on the side opposite the insertion. Conclusions: There is a risk of root contact and severe tissue damage from a thick mini-implant and the drilling procedure, either of which can induce root resorption or ankylosis. Use of smaller mini-implants may reduce root contact and tissue damage. However, the small mini-implant may need enhancement of its stability. (Angle Orthod. 2010;80:452-458.)

Section: Introductionmentioning

confidence: 99%

Root and Bone Response to the Proximity of a Mini-Implant under Orthodontic Loading

Lee¹,

Kim²,

Baek³

et al. 2010

Self Cite

“…[11][12][13][14][15][16][17][18][19][20][21][22] Studies have found that the stability of OMIs is affected by age, sex, craniofacial skeletal pattern, site and side of implantation, latent period, loading protocol, dimension of OMI, angulation of OMI to bone, insertion torque, degree of OMI-bone contact, quality and quantity of the cortical bone, degree of inflammation of the peri-OMI tissue, thickness and mobility of the soft tissue, and root proximity. 6,14,15,[19][20][21][23][24][25][26] If an OMI fails, there are two options: reinstall a new one in the same area after 4 to 6 weeks or install a new one in an adjacent area immediately. 5 However, few studies have focused on the fate of the reinstalled OMI (RI-OMI).…”

Section: Introductionmentioning

confidence: 99%

Success Rate and Risk Factors Associated with Mini-Implants Reinstalled in the Maxilla

Baek

Kim

Kyung

et al. 2008

Objective: To determine the difference in the success rate for two types of oral installed miniimplants (OMIs): one type of initially installed OMI and a new implant of the same type that is reinstalled. Materials and Methods: The subjects consisted of 58 patients (19 male, 39 female; mean age ϭ 21.78 Ϯ 5.85 years) who had received at least one OMI (self-drilling type, conical shape with 2.0-mm upper diameter and 5-mm length) in the attached gingiva of the upper buccal posterior regions for maximum anchorage during en masse retraction. If an OMI failed, a new one was immediately installed in the same area after 4 to 6 weeks or in an adjacent area immediately. The total number of initially installed OMIs (II-OMI) was 109 and the total number of reinstalled OMIs (RI-OMI) was 34. Statistical analysis was performed using 2 test, Kaplan-Meier method, log-rank test, and Cox proportional hazards regression model. Results:The success rate and mean duration were 75.2% and 10.0 months, respectively, for II-OMI and 66.7% and 6.4 months, respectively, for RI-OMI. Age, vertical skeletal pattern, and site and side of implantation were not related to the success rates of II-OMI and RI-OMI. Log-rank test showed that II-OMI in males and Class III malocclusions were more prone to failure. The relative risk of II-OMI failure in Class III malocclusions as opposed to Class I malocclusions was 5.36 (95% confidence interval, 2.008 to 14.31, P ϭ .001). Conclusion:The success rate of the II-OMI was not statistically different from that of the RI-OMI. Sex and ANB angle might be more important factors for better II-OMI results.

“…6,7 The small diameter of orthodontic mini-implants leads to less stability under rotational moments, since the removal torque value is directly proportional to the square of the implant diameter. 11 Mechanical and surface treatments intended to pro- vide better osseointegration can help to increase the stability of mini-implants subjected to moments or dynamic forces. [12][13][14][15][16][17] Moreover, rotational stability will provide the clinician with additional and very useful biomechanical options.…”

mentioning

confidence: 99%

Rotational Resistance of Surface-Treated Mini-Implants

Kim

Lee

Cho

et al. 2009

Objective: To test the hypothesis that there is no difference in the stability and resistance to rotational moments of early loaded sandblasted and acid-etched (SLA) mini-implants and those of machined-surface implants of the same size and shape. Materials and Methods: A randomized complete block design was used in 12 skeletally mature male beagle dogs. Ninety-six orthodontic mini-implants were tested. Two types of implants were used: some had SLA surface treatment and some had machined surfaces without coating. After 3 weeks of healing, rotational moments of 150 g were applied. The success rates, maximum torque values, angular momentum, and total energy absorbed by the bone were compared. All values were subjected to mixed-model analysis to evaluate the influence of surface treatment, rotational force direction, and site of implantation. Results:The maximum insertion torque and angular momentum of SLA implants were significantly lower than those of machined implants (P ϭ .034, P ϭ .039). The SLA implants had a significantly higher value for total removal energy than the machined implants (P ϭ .046). However, there were no significant differences in total insertion energy, maximum removal torque, and removal angular momentum between the 2 groups. There was no significant difference between clockwise and counterclockwise rotation in all measurements. Conclusion: SLA mini-implants showed relatively lower insertion torque value and angular momentum and higher total energy during removal than the machined implants, suggesting osseointegration of the SLA mini-implant after insertion. (Angle Orthod. 2009;79:899-907.)