A comparison of root resorption between Invisalign treatment and contemporary orthodontic treatment

The purpose of the study was to compare the incidence and severity of External Apical Root Resorption (EARR) in patients treated with different orthodontic appliances. The definition of EARR can be that of blunting or shortening of the root apex, a condition often associated with orthodontic treatment. In previous studies it have been found that the teeth most susceptible to root resorption are the maxillary and mandibular incisors, with the maxillary lateral incisors have the greatest incidence and degree of resorption. A number of studies have evaluated the role of variables such as age, sex, malocclusion, dental root anatomy, appliance type, type of orthodontic force, and treatment time in the development of external apical root resorption. Few studies have dealt with the effects of different orthodontic bracketing systems on EARR. Standard edgewise, straight-wire, and Begg appliances, as well as the newer self-ligating bracket systems, have began to be investigated. The introduction and popularity of Invisalign in treating more and more complex orthodontic malocclusions provoked the investigation of its effect on external apical root resorption. Only a few clinical studies have been published with regards to Invisalign and very few studies have been completed that analyzed the effects of the Invisalign aligners. A further aim was to analyze the degree of EARR in different tooth groups in patients presenting with root resorption. The sample consisted of 90 female patients aged 10--58 years at the beginning of orthodontic treatment. A conventional edgewise appliance (MBT prescription, 0.22-inch slot) and the Invisalign appliance were used. Root resorption in all anterior tooth groups, (canines, lateral incisors, central incisors), of both maxilla and the mandible were evaluated from pre- and post-treatment panoramic radiographs. Of the tooth groups, maxillary lateral incisors showed EARR most frequently, followed by the maxillary central incisors and then the mandibular incisors. Root resorption was significantly correlated with the conventional edgewise appliance treatment and not with the Invisalign treatment. The most severe resorption was seen in the maxillary lateral incisors. It is concluded that with the fixed conventional edgewise appliance, the risk of EARR is higher than when malocclusions are treated with the Invisalign appliance. In this study there was not any recordable external apical root resorption present when the malocclusions were treated with the Invisalign clear removable aligners.