Current evidence on clinical performance of miniscrew implants in orthodontic treatment

The effects of cortical bone thickness and miniscrew implant root proximity on the success rate of miniscrew implant: A retrospective study

OBJECTIVE

To investigate the effects of cortical bone thickness (CBT), miniscrew implant root proximity (MRP) and other related factors on the success rate of miniscrew implant (MSI).

MATERIALS AND METHODS

Four hundred and five MSIs placed in 171 patients were analysed in this retrospective study. The primary predictor variables were CBT and MRP at MSI insertion sites. The predictor variables also included patient, location, MSI design and procedure related factors. The outcome variable was the survival of MSI. The differences in measurement data between success group and failed group were evaluated by the analysis of variance and independent samples t tests. Patient, location, MSI design and procedure related factors associated with the MSI prognosis were analysed by survival analysis with Cox proportional hazard regression model. The P value was set at .05. And the survival curves of independent factors were plotted.

RESULTS

The overall success rate of MSI was 82.7%. The age of MSI host, CBT, interdental root distance (IRD) and MRP at MSI sites showed no significant differences between failed group and success group. CBT and insertion jaws were independent prognosis factors screened out by Cox proportional hazard regression model. Failure risk (hazard ratio) of MSI with CBT <1 mm was 4.72. The failure risk in the mandible was 3.80 times as high as that in the maxilla.

CONCLUSION

Inadequate CBT (<1 mm) contributed to the failure of MSI. MSI placed in the maxilla showed better prognosis compared to the mandible. MRP had no significant effect on the prognosis.

Palatal temporary skeletal anchorage devices (TSADs): What to know and how to do?

OBJECTIVES

Since palatal temporary skeletal anchorage devices (TSADs) have become important tools for orthodontic treatment, this narrative review was aimed to provide an updated and integrated guidelines for the clinical application of palatal TSADs.

SETTING AND SAMPLE POPULATION

A narrative review article including researches on palatal TSADs in orthodontics related to anatomy, success rate and clinical application.

MATERIALS AND METHODS

The anatomical characteristics, success rate and its consideration factors and clinical application of palatal TSADs based on the direction of tooth movement were evaluated.

RESULTS

To improve the stability of TSADs, hard tissue factors such as bone depth, cortical bone thickness, bone density and soft tissue thickness were evaluated. Anatomically risky structures, including the nasopalatine foramen, canal and the greater palatine foramen, nerve, vessel need to be identified before placement. The success rate of palatal TSADs was greater than that of the buccal inter-radicular space. Palatal TSADs have been used for various purposes because they can control tooth movement in all directions and, three-dimensionally; their applications include the retraction of anterior teeth, protraction of posterior teeth, distalization, intrusion, expansion and constriction. They can be applied directly or indirectly to the lingual arch or transpalatal arch. Design modifications using splinted 2 miniscrews have been suggested.

CONCLUSION

Palatal TSADs allow clinicians to perform minimally invasive and easy placement with good stability by understanding the anatomical characteristics of the palatal region, and they show good control over 3-dimensional tooth movements in various clinical cases.

Mandibular molar uprighting using orthodontic miniscrew implants: a systematic review

The purpose of this systematic review was to identify studies and present the use of miniscrew implants (MIs) as an alternative treatment to mandibular molar uprighting. An electronic search and handsearching were conducted by two independent reviewers to identify relevant articles, published up to January 27, 2017. In order to methodologically assess the eligible studies, a pilot checklist consisting of 22 items was also implemented. After exclusion of all the irrelevant papers, only 17 studies were included, presenting 27 cases of mandibular molar uprighting in all planes using both direct and indirect force traction by MIs. Regarding the quality evaluation, the mean score of the included studies was 13.2, indicating a rather poor methodology implemented in the majority of the included cases. Due to many advantages, MIs provide a unique treatment alternative and constitute a reliable solution for treating tipped or impacted molars. Regarding the force application, a direct method is simpler, as it requires one MI and a single bracket or button, minimizing the patient's discomfort and also reducing chair time compared to more complex indirect anchorage. It also eliminates the possibility of unwanted movement of the anchorage unit, which can occur even with indirect anchorage as a result of technical errors. However, direct anchorage has limitations in cases of lingually tipped or rotated molars because a single force may be insufficient to upright the tooth.

Individual scoring and mapping of hard and soft tissues of the anterior hard palate for orthodontic miniscrew insertion

AIM

The aim of the present study was to introduce a scoring system to select optimal sites to insert a miniscrew in a hard palate.

METHODS

The present study consisted of 37 adult patients (21 females and 16 males) aged between 20 and 50 years, with a mean age of 34.81 (±9.52) years. Hard and soft tissues of the anterior hard palate were assessed using cone-beam computed tomography. The scoring system was as follows: mucosal thickness: 0-2 mm (2 points), 2-4 mm (1 point), and 4-6 mm (0 points); total bone vertical height: ≥5 mm (1 point) and <5 mm (0 points); and palatal cortical thickness: ≥1 mm (1 point) and <1 mm (0 points).

RESULTS

Significant variability was found between the individuals. Total vertical bone height decreased posteriorly and laterally. Mucosal thickness decreased posteriorly, but increased laterally. Palatal cortical thicknesses were higher than the nasal cortical thicknesses. The most balanced sites (highest point) were the midpalatal suture, followed by paramedian points located 3 mm lateral to the midline and 4 mm posterior to the incisive canal.

CONCLUSIONS

Considering that both hard and soft tissue parameters are crucial to obtain the best possible success rates, careful investigation is recommended prior to clinical decisions being made.