The Journal during growth . In a less dense alveolar bone , there are more marrow spaces . Tooth movement , as a result of bone resorption , is facilitated by the formation of active resorptive cells , the number of which increases according to the number of marrow spaces .
According to Reitan , a strong continuous force on less dense alveolar bone causes the same root resorption as a mild continuous force on highly dense alveolar bone . Lamellar bone is more difficult to resorb with orthodontic pressure than bundle bone . Direct contact between roots and cortical bone can precipitate root resorption , especially during the second stage of Begg treatment as a result of high stress pattern at the apex . Wainwright reported that bone density affects the tooth movement rate but has no relation to the extent of the root resorption . 9,10,11
Habits
Nail-biting , tongue thrust associated with open bite , and increased tongue pressure have been statistically related to increased root resorption .
Specific tooth vulnerability to root resorption
Different teeth have different tendencies to root resorption . All examined teeth after orthodontic treatment showed evidence of root resorption . Most studies report that maxillary teeth are more sensitive than mandibular teeth .
The maxillary incisors are the teeth most affected by root resorption . The extent of movement in these teeth is usually greater than in others because of malocclusion , function , and esthetics . Their root structure and relationship to bone and periodontal membrane tend to transfer the forces mainly to the apex . 11
Others have found the mandibular incisors to be more affected . It is believed that if there is no apical root resorption seen in maxillary and mandibular incisors , then significant apical resorption in other teeth is less likely to occur . The most frequently affected teeth , according to severity , are the 12
Maxillary Laterals . Maxillary Centrals . Mandibular Incisors . Distal Root Of Mandibular First Molars . Mandibular Second Premolars . Maxillary Second Premolars .
43 Vol . 14 No . 1 Jan-Apr 2018