Relationship of the maxillary posterior teeth and maxillary sinus floor in different skeletal growth patterns: A cone-beam computed tomographic study of 1600 roots

Purpose@#This study evaluated the distance from the posterior root apices to the maxillary sinus floor (MSF) and the frequency of roots touching or protruding through the MSF using cone-beam computed tomography (CBCT). @*Materials and Methods@#This study included 100 subjects divided into different vertical and anteroposterior skeletal growth patterns. On CBCT images, the distance from the posterior root apices to MSF was measured and the frequency of roots touching or protruding through the MSF was evaluated using NNT software (version 5.3.0.0; ImageWorks, Elmsford, NY, USA). @*Results@#No statistically significant differences were found in the distance from the posterior root apices to the MSF among vertical skeletal groups (P>0.05). The palatal roots of the first molar and the palatal, mesio-buccal and disto-buccal roots of the second molars had significantly less distance from MSF in skeletal class II than in class III (P<0.05). The high-angle group had the highest frequencies of roots touching or protruding into the maxillary sinus (49.8%); the lowest proportion of these roots was found in skeletal class III (28.3%) and the highest proportion in class II (50.3%). Males had shorter distances from the posterior root apices to the MSF and higher frequencies of roots protruding through or touching the MSF than females. @*Conclusion@#Anteroposterior skeletal growth patterns and sex affected the distances from the maxillary posterior roots to the MSF. The frequency of roots protruding into or touching the sinus was affected by both vertical and anteroposterior skeletal groups and sex. These findings have implications for dental practice.

Rapid canine distal movement through distraction osteogenesis of the periodontal ligament* / 中国组织工程研究

BACKGROUND:Distraction osteogenesis applied in patient’s canine distal movement, can greatly improve the speed of tooth movement, and protect the molar anchorage. But the researches on the traction rate, canine pulp vitality, canine periodontal tissue remodeling and the biological mechanisms of the technology are rare recently. OBJECTIVE:To evaluate the feasibility of rapid canine retraction through distraction osteogenesis of the periodontal ligament in adult patients and to monitor the pulp vitality, root resorption and periodontal remodeling of the canine. METHODS:Nine malocclusion patients were selected, and the bilateral maxil ary canine in adult patients were rapidly retracted and moved to the scheduled position using modified distraction devices. The canine distal movement distance, anchorage loss, root resorption and alveolar interval alterations were measured through intraoral radiographs, and lateral cephalograms. The pulp and periodontal of canine were mointrored. RESULTS AND CONCLUSION:The canines could be rapidly retracted to the schedualed position through distraction osteogenesis of the periodontal ligament in 12-16 days, the average amount of retraction was 7.18 mm and the canines tipped distal y (13.24±2.87)°. The anchorage loss was 0.5 mm. There was no obvious root resorption and periodontal tissue loss. The pulp vitality of the canines was decreased significantly right after distraction, but it recovered significantly after 3 months. The results indicated that periodontal ligament distraction osteogenesis can significantly accelerate canine movement speed, shorten treatment time, while protecting the molar anchorage;there was no significant adverse reaction of root resorption, loose teeth, pulp necrosis and loss of periodontal tissue. Indcating that distraction osteogenesis of periodontal ligament can move canines rapidly and effectively.

Initial stress distribution of the maxillary anterior teeth, periodontal ligament and alveolar bone by different intruding loadings A three-dimensional finite element analysis / 中国组织工程研究

BACKGROUND: It is very important to explore an optimal loading force that can both allow effective intrusion and cause no damage to the teeth.OBJECTIVE: To investigate the optimal loading conditions, including loading force values and directions, in the intruding mechanics of maxillary anterior teeth.METHODS: A three-dimensional finite element model (3D FEM) of the maxillary anterior teeth was constructed to include the periodontal ligament (PDL), alveolar bone, and appliance (brackets and wire). The initial stress distribution and force of the maxillary anterior teeth were analyzed when the 3D FEM was loaded with different intruding force values and directions. RESULTS AND CONCLUSION: The optimal value of the intruding force for 6 anterior teeth fell within the range from 0.5 N to 1.0 N. The maximum stress was detected at the distal cervical level of the lateral incisor, and a relatively even distribution of initial stress was observed at 20° palatal deviation to the Y axis. The results suggest that using mini-screw implants at the labial region between the canine and lateral incisor and a combined 0.5-1.0 N intruding force with a distal force could be an optimal intrusion force system by which patients with normal occlusion could obtain a pure intrusion of anterior teeth.

Clinical Research of a New Movable Molar Distalization Appliance / 中山大学学报(医学科学版)

[Objectives]This study was designed to evaluate the treatment effects of a new movable molardistalization appliance for distal movement of maxillary first molars on Angle's Class Ⅲ malocclusion adolescence patients with the second premolar crowded.[Methods]Sixteen patients were treated by a new movable molardistalization appliance.Cephalometric analysis and model measurement was carried out before and after the treatment.Data were analyzed by paired t-test.[Results]The molars were distalized 5 mm during an average time of 3.8 months.There were significant increases in the Angle SNA and A-NPg(P ＜0.05).[Conclusion]it was a effective way to get space and improve patient's profiles on Angle's Class Ⅲ malocclusion adolescence patients with the second premolar crowded by the new movable molardistalization appliance.It was also conducive to patient's oral hygiene.

Cephalometric analysis for Angle's class Ⅲ malocclusion patient with maxillary front traction / 中华医学美学美容杂志

Objectives To study the changes of hard tissue before and after orthodontic treatment for Angle's class Ⅲ malocclusion adolescence patient with maxillary front traction. Methods 20 cases of Angle's class Ⅲ malocclusion adolescence patients were treated by front traction in maxilla, while there were 20 cases of Angle's class Ⅰ malocclusion adolescence patients as the control group. Cephalometric a-nalysis was carried out before and after the treatment. Data were analyzed by SPSS11.0 system using paired t-test. Results There were significant increases in the length, anteroposterior diameter and thick-ness of maxillary sinus (P<0.05), while there was no significant differences in the site and central point of maxillary sinus(P>0.05). Conclusions It is a effective approach to change the hard tissue after ortho-dontic treatment for Angle's class Ⅲ malocclusion adolescence patient with front traction in maxillary area.