In-vitro and in-vivo assessment of the Periotest M device as a means of measuring temporary anchorage device stability: a pilot study

Introduction

One of the many challenges of orthodontic treatment is the unwanted movement of anchor teeth due to the presence of reciprocal forces. Temporary anchorage devices (TADs), or orthodontic mini-screws, are a relatively new tool used to obtain skeletal anchorage and mitigate undesirable tooth movements. These small screws are quite versatile and can be placed in many anatomical locations of both the upper and lower jaw to facilitate tooth movement. Despite their potential and versatility, premature failure of TADs has long been one of the greatest challenges and frustrations for providers as it interrupts orthodontic treatment and may require alternative treatment modalities. The purpose of this study is to establish a protocol by which TAD stability can be measured via the Periotest M device, to investigate the validity of such data, and to begin gathering clinical data to support its efficacy.

Materials and Methods

For the in-vitro portion of this study, a single TAD from the Bioray TAD system was placed into a Sawbones synthetic bone mandible, following standard insertion protocol. The synthetic mandible was then affixed to the benchtop with a table clamp. A series of ten measurements were then recorded by eleven calibrated operators. Each operator followed the same protocol, including: a horizontal angulation of the Periotest M device, a perpendicular tapping of the TAD, and a finger rest to stabilize the hand recording the measurements. A two-way ANOVA test was utilized to determine if there was a statistically significant difference between measurements both within each operator and amongst all operators.

For the in-vivo portion of this study, each TAD was placed following standard clinical protocol and in accordance with the orthodontic needs of each patient. After initial placement and at each subsequent visit, each TAD was measured three times by two calibrated operators, each of whom participated in the in-vitro portion, following the previously mentioned measurement protocols.

Results

For the in-vitro portion of this study, no statistically significant difference was found for measurements recorded within each operator or between all operators. No statistical calculations were recorded for the in-vivo portion of this study due to the small amount of data collected thus far and the lack of achievable statistical power.

Conclusions

Data collected within the in-vitro portion of this study indicate that the Periotest device may be useful for assessing the stability of TADs in-vivo. However, more clinical data will need to be collected before making a final determination on the clinical efficacy of using the device in a clinical scenario.