Clinical analysis of orthodontic traction of impacted upper incisors / 口腔疾病防治

Objective@#To study the effect of orthodontic traction on the roots and periodontal soft and hard tissues of buried obstructed upper incisors.@*Methods@#This study was reviewed and approved by the ethics committee, and informed consent was obtained from the patients. From January 2018 to December 2022, 40 patients who underwent orthodontic traction on impacted upper incisors were selected; those whose contralateral homonymous apical foramen was not developed were placed in group A (23 cases), and those whose contralateral homonymous apical foramen was developed were placed in group B (17 cases). Software was used to measure the root length of the impacted upper incisors in groups A and B on cone beam CT (CBCT) images before and after traction and compare the changes in alveolar bone (alveolar bone width, labral bone plate thickness, and horizontal height of alveolar bone) and keratinized gingival width between each impacted upper incisor and the corresponding contralateral tooth immediately and one year after traction@*Results@#The root length of the impacted upper incisors increased after traction compared to before traction (P<0.05). The width of the alveolar bone at the completion of traction in group A was similar to that of the contralateral homonymous tooth (P>0.05), whereas the width of the alveolar bone at the completion of traction in group B did not reach that of the contralateral homonymous tooth, with a significant difference in width (P<0.05). Neither the labial bone plate height or width in group A or B reached that of the contralateral homonymous tooth after traction (P<0.05). The keratinized gingival width on the affected side was also significantly smaller than that on the contralateral side (P<0.05), but it was increased significantly in group A at the one-year follow-up visit (P<0.05).@*Conclusion@#Tooth traction is conducive to impacted upper incisor root growth, alveolar bone reconstruction and keratinized gingival growth but cannot produce complete symmetry with respect to the contralateral side.

Study of dental arch width in patients with idiopathic condylar resorption / 临床耳鼻咽喉头颈外科杂志

Objective:To investigate the relationship between idiopathic condylar resorption （ICR） and arch width disorder. Methods:Thirty-two patients with ICR and twenty patients without condylar resorption were enrolled according to the same inclusion criteria. They were divided into experimental group and control group. The experimental group was divided into unilateral ICR group and bilateral ICR group according to the affected side of condylar resorption, and then experimental group was divided into subgroups ICR Ⅰ, ICRⅡand ICR Ⅲ according to the degree of condylar resorption. Patients with no condylar resorption were used as a control group. The width of anterior, middle and posterior segments of dental arch on cone beam computed tomography（CBCT） was measured and the two groups of measured values were statistically analyzed. Results:Compared with the control group, the width of maxillary anterior, middle and posterior segments in ICR group was significantly reduced, and the difference was statistically significant（P<0.01）. But the width of mandibular segment was not significantly different from that in control group（P>0.05）. There was no significant difference in the width of anterior, middle and posterior dental arch between subgroups（P>0.05）. Conclusion:Almost all patients with ICR have malocclusion of maxillary and mandibular arch width, but there is no significant correlation between the malocclusion width and the severity of condylar resorption.

Clinical effect of platelet-rich fibrin combined with bone substitute in alveolar ridge preservation / 口腔疾病防治

Objective@#To study the clinical outcomes of implanting platelet rich fibrinogen (PRF) mixed with Bio-Oss® in the extraction socket for alveolar ridge preservation and to provide evidence for clinical application. @*Methods@#Thirty-six patients who underwent alveolar ridge preservation were enrolled. Thirty-six extraction sites were divided into two groups: PRF mixed with Bio-Oss® group (test group) and Bio-Oss® alone (control group). Bone dimensional changes in height and width were measured by CBCT before and 6 months after surgery, and early soft tissue healing and postoperative pain sensation were evaluated clinically 1 week after surgery.@* Results @# There was no significant difference in the alveolar bone height (-1.48 ± 0.40) mm between the test group and the control group. The difference in the alveolar bone width between the test group (-1.09 ± 0.42) mm and the control group (-1.35 ± 0.22) mm was statistically significant (z=-2.63, P=0.01). The postoperative pain score of the test group was 2.39 ± 1.20, and that of the control group was 3.39 ± 1.65, the difference was statistically significant (t=-2.083, P=0.045). There was no significant difference in soft tissue healing between the test group and the control group.@*Conclusion @#The use of PRF mixed with Bio-Oss ®in the alveolar ridge preservation procedure can reduce alveolar bone absorption and postoperative pain.

Comparison of mandibular anterior alveolar bone thickness in different facial skeletal types / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to determine differences of mandibular anterior alveolar bone thickness and symphysial cross sectional area in 9 different horizontal and vertical facial types. METHODS: By using the initial cephalometric radiographs of 270 adult patients (male 135, female 135), the authors measured the buccolingual thickness of anterior alveolar bone on the basis of the root axis and symphysial cross sectional distance. RESULTS: The high angle group showed significantly thinner buccolingual alveolar bone width except for the CEJ area and lingual alveolar bone width (p 0.05). CONCLUSIONS: The results of this study found that Class III high angle patients have thinner mandibular anterior alveolar bone thickness; therefore, more attention will be needed to determine the incisor position during orthodontic treatment for this group of patients.

Stress analysis of supporting tissues according to implant fixture diameter and residual alveolar bone width / 대한치과보철학회지

STATEMENT OF PROBLEM: The cumulative success rate of wide implant is still controversial. Some previous reports have shown high success rate, and some other reports shown high failure rate. PURPOSE: The aim of this study was to analyze, and compare the biomechanics in wide implant system embeded in different width of crestal bone under different occlusal forces by finite element approach. MATERIAL AND METHODS: Three-dimensional finite element models were created based on tracing of CT image of second premolar section of mandible with one implant embedded. One standard model(6mm-crestal bone width, 4.0mm implant diameter, central position) was created. Varied crestal dimension(4, 6, 8 mm), different diameter of implants(3.3, 4.0, 5.5, 6.0mm), and buccal position implant models were generated. A 100-N vertical(L1) and 30 degree oblique load from lingual(L2) and buccal(L3) direction were applied to the occlusal surface of the crown. The analysis was performed for each load by means of the ANSYS V.9.0 program. CONCLUSION: 1. In all cases, maximum equivalent stress that applied 30.oblique load around the alveolar bone crest was larger than that of the vertical load. Especially the equivalent stress that loaded obliquely in buccal side was larger. 2. In study of implant fixture diameter, stress around alveolar bone was decreased with the increase of implant diameter. In the vertical load, as the diameter of implant increased the equivalent stress decreased, but equivalent stress increased in case of the wide implant that have a little cortical bone in the buccal side. In the lateral oblique loading condition, the diameter of implant increased the equivalent stress decreased, but in the buccal oblique load, there was not significant difference between the 5.5mm and 6.0mm as the wide diameter implant. 3. In study of alveolar bone width, equivalent stress was decreased with the increase of alveolar bone width. In the vertical and oblique loading condition, the width of alveolar bone increased 6.0mm the equivalent stress decreased. But in the oblique loading condition, there was not a difference equivalent stress at more than 6.0mm of alveolar bone width. 4. In study of insertion position of implant fixture, even though the insertion position of implant fixture move there was not a difference equivalent stress, but in the case of little cortical bone in the buccal side, value of the equivalent stress was most unfavorable. 5. In all cases, it showed high stress around the top of fixture that contact cortical bone, but there was not a portion on the bottom of fixture that concentrate highly stress and play the role of stress dispersion. These results demonstrated that obtaining the more contact from the bucco-lingual cortical bone by installing wide diameter implant plays an important role in biomechanics.