Do sand blasted with large grit and acid etched surface treated mini-implants remain stationary under orthodontic forces?

Control of anterior segment using an antero-posterior lingual sliding retraction system: a preliminary cone-beam CT study

BACKGROUND

This study was performed to evaluate the treatment effects of the antero-posterior lingual retractor (APLR), focusing on the 3-dimensional (3D) tooth movement of the maxillary anterior teeth and their alveolar bone levels.

METHODS

En masse retraction was performed using either the C-lingual retractor (CLR, C-group, n = 9) or the antero-posterior lingual retractor (APLR, AP-group, n = 8). We evaluated 3D movement of the maxillary anterior teeth and alveolar bone levels, root length of the central incisors, long axes of the maxillary canines, and occlusal plane changes from CBCT images.

RESULTS

After retraction, the central incisors were more significantly intruded and their root apex was more retracted in the AP-group. The long axis of the canine was well maintained in the AP-group. There were no differences in the steepness of occlusal plane and the incidence of alveolar bone loss or of root resorption during en masse retraction with the two retractors.

CONCLUSIONS

The clockwise bowing effect of the anterior segment was less with the APLR, which prevented unwanted canine movement.

Bone anchors--can you hitch up your wagon?

The purpose of this review was to address and understand the current status of mini-screw implants (MSI) that are used in orthodontics. Understanding the biologic adaptation of MSI to its adjacent bone is one of the critical factors to their success. The review explores factors that are associated with failure of MSI, with special focus on an understanding of osseointegration as it relates to MSI. The rationale and importance of measuring bone contact and dynamic bone remodeling in animal studies are outlined. The utility of microcomputed tomography (μCT) as a substitute for conventional histomorphometry is debated. Finally, alveolar physiology and rigidity of implants are explored to understand potential reasons for the high failure rate of MSI when compared to endosseous implants.

A new method to evaluate the positional stability of a self-drilling miniscrew

OBJECTIVES

To evaluate the positional stability of miniscrews during orthodontic treatment change in cone-beam computed tomography (CBCT).

SETTING AND SAMPLE POPULATION

Twenty adult volunteers were enrolled.

METHODS

In all participants, at least two maxillary first premolars were extracted because of protrusion. Each volunteer received six miniscrews in the maxilla, including two loaded miniscrews to retract anterior teeth and four unloaded miniscrews. CBCT scans were obtained at the beginning of space closure (T1) and approximately 11.8 months later (T2). Three-dimensional miniscrew models were constructed at T1 and T2, and the central axes were calculated using a principal component analysis (PCA) technique. Finally, we measured and compared the angle change of all the miniscrews from T1 to T2.

RESULTS

The angle change values of the unloaded and loaded miniscrews were 1.64 ± 1.25° and 1.67 ± 1.15°, respectively. No significant differences in the angle change were observed.

CONCLUSION

Cone-beam computed tomography images revealed both the unloaded and loaded miniscrews to be positionally stable during en-masse retraction in this study.