The Journal
Distal Tooth Movement
Root resorption of Posterior Teeth , may often be neglected as a sequel to distal tooth movement . Literature shows that Cervical Traction causes little resorption of molar roots [ Hixon ]. Forces applied in cervical traction are relatively high and may be continued for long periods [ Graber T . M .]. Both magnitude and duration are factors which influence various tissue reactions , ncluding root resorption [ Reitan ]. Position and influence of adjacent structures , notably unerupted , developing second molars , may be overlooked or misjudged in the evaluation of the clinical situation .
Ÿ Orthodontic tooth movement may cause root surface resorption of posterior permanent teeth , which is not readily detected on radiographs .
Ÿ Distal movement of upper molar roots against adjacent unerupted teeth could cause resorption . Eruption path of upper 2nd Molars may be responsible partially or totally for their impingement against first molar roots . Posterior teeth are not immune from resorption . Distal movement had devastating effects on the prognosis of the affected tooth . 9,13,14
Intermaxillary Elastics
Linge and Linge found significantly more root resorption on the side where elastics were used . Jiggling forces combined with elastics are responsible for the incisors root resorption . Class III elastics used for anchorage preparation increased mandibular first molar distal root resorption . 8
Extraction versus Nonextraction
McFadden and VonderAhe found no difference in the extent of root resorption in patients treated with or without extractions . 13
Serial Extractions Serial extractions without orthodontic treatment gave the least root resorption compared with serial extractions with orthodontic treatment . 9
Magnitude of applied forces
Harry and Sims found
Ÿ Distribution of resorbed lacunae - Directly related to the amount of stress on the root surface .
Ÿ Rate of lacunae development -More rapid with increasingly applied forces .
Ÿ Concluded - Higher stress causes more root resorption . 15
Continuous versus Intermittent forces
The pause in treatment with intermittent forces allows the resorbed cementum to heal and prevents further resorption . 15
Direction of tooth movement
It seems that there is no safe tooth movement . Intrusion is probably the most detrimental to roots . Tipping , torque , bodily movement , and palatal expansion can also be implicated . According to Reitan , stress distribution along roots during bodily movement is less than stress concentration at the apex resulting from tipping . Therefore risk of root resorption that is due to bodily movement should be less than that of tipping . 10,11
Amount / Extent of tooth movement
Many believe that root resorption is directly related to the distance moved by the roots . Maxillary incisor roots are moved more often than the roots of other teeth . Therefore , it is not surprising to detect greater apical root loss in these teeth . 16 However , Phillips who examined several tooth movement types and Dermaut who examined intrusion did not find any relationship between the extent of root movement and the amount of root loss . 17
45 Vol . 14 No . 1 Jan-Apr 2018