Balkwill's angle, occlusal plane, mandibular shape, and curve of Spee.

OBJECTIVE: This study proposes a cephalometric method to determine an individual radius of the curve of Spee in cases of occlusal prosthetic rehabilitation. METHODS: A retrospective study was conducted on 469 lateral cephalograms. Statistical analysis was performed. Correlations were computed using simple regression, Z tests, paired t-tests, and one-way repeated measures ANOVA. RESULTS: Regression calculations supported a link between the radius of the curve of Spee and occlusal plane inclination, Balkwill's angle, mandibular parameters (MP), with MP = corpus - ramus + Bonwill height. Based on MP, data that are accessible even in the absence of teeth, a regression formula can be proposed to provide an individualized estimation of the radius of the Spee curve (RCS): RCS = 0.624 * MP + 26.583. CONCLUSION: This study proposes an individualized estimation of the RCS from only skeletal mandibular parameters: the length of the ramus, length of the corpus, and the Bonwill height.

Cone-beam CT analysis of occlusal planes between different vertical skeletal types of adult class Ⅱ malocclusions in Shandong province / 解剖学报

[Abstract] Objective To investigate the cant of the occlusal planes in Chinese adult class Ⅱ malocclusions with hypodivergent, normodivergent, and hyperdivergent facial vertical patterns using cone-beam CT. Methods The descriptive, cross-sectional study evaluated 123 cephalogram from CBCT(CCB) of patients in Department of Orthodontics, the Affiliated Hospital of Qingdao University. According to cephalometric analysis, 89 Chinese adult class Ⅱ patients were divided into three groups according to the angle between FH-MP and the angle between SN-MP. In comparison, 34 Class I normodivergent malocclusions individuals were selected as the control group. Comparing the cephalometric result between 4 groups. Results As expected,the hyperdivergent group had steeper anterior occlusal planes(14. 73±3. 76) . and posterior occlusal planes(21. 42±5. 77)., there was a significant statistical difference between the hyperdivergent group and other 2 groups in class Ⅱ patients (P<0. 05). The height of maxillary second molar increased from high angle group to low angle group (P<0. 01). Conclusion There are different characters of the occlusal planes in varied vertical facial pattern. The inclinations of anterior and posterior occlusal planes in Chinese class Ⅱ hyperdivergent group were steeper than other 3 groups. The difference of posterior occlusal plane inclination is mainly caused by the height of maxillary second molar.

Morphological measurement and analysis of the mandible in adult females with different vertical skeletal types / 中国组织工程研究

BACKGROUND: A review of previous epidemiological investigations shows that the detection rate of malocclusion is the highest in Angle I, but the classification is limited by the failure to consider the comprehensive mechanism of the formation of malocclusion in the three-dimensional direction of the length, width and height of teeth, jaws and facial structures, and the profound impact of the position of the mandible and facial bones on a person’s appearance. Therefore, the morphological characteristics of the mandible and chin should be fully considered before orthodontic treatment. OBJECTIVE: To compare the similarities and differences of the three-dimensional facial morphology in adult females with different vertical skeletal types of skeletal Class I by measuring the three-dimensional morphology of the chins and mandibles through cone-beam CT multi-planar reconstruction. METHODS: According to SN-MP angle, the cone-beam CT images of 86 females with skeletal Class I aged from 18 to 35 years were imported into MIMCS19.0 to make multi-planar reconstruction, and then the data was divided into three groups: 39° (high angle group, 26 cases). Then, the mandibular linear distance and angle were measured, and the mandibular outline was measured through the three-dimensional reconstruction. RESULTS AND CONCLUSION: With the increase of mandibular plane angle, the morphology of mandible tended to be: (1) the mandible ascending ramus became shorter, and the mandible body grew; (2) the notch of mandibular angle deepened gradually, and the opening of the mandibular angle increased gradually relative to the cranial-jaw; (3) the alveolar process of the chin became longer and the shape of chin became gentle; (4) counterclockwise rotation of the chin and compensatory inclination of lower anterior teeth towards tongue occurred. Comparing different vertical skeletal types of skeletal Class I in adult females, both the morphologies of the mandible and chin are different, and the mandibular plane angle is related to the morphology of the mandible and chin.

[Characteristics of mandible and mandibular dentition according to vertical facial skeletal features of adolescents].

OBJECTIVE: We aim to examine teenagers with varying vertical facial skeletal types with near-normal occlusion. We further aim to identify and study mandibular morphology and dentition characteristics to establish normal ranges and variations for future clinical reference. METHODS: According to the results of the case studies, 42 adolescents with near-normal occlusion were divided into three groups, namely, low- (7 cases), average- (23 cases) and high-angle (12 cases) groups. We used Invivo 5 software for Digital Imaging and Communications in Medicine (DICOM) data to calculate the cant of occlusal plane, axis corner of L6, ∠L1/MP, ∠L6/MP, Balkwill angle and Bonwill triangle of each group. RESULTS: Markedly, the finding shows that the cant of occlusal plane and axis corner of L6 in the low-angle group were smaller than those of the other two groups. In the average-angle group, ∠L1/MP was larger than that of the high-angle group. Lastly, in the high-angle group, ∠L6/MP was smaller than those of the two other groups. On the one hand, these differences were considered statistically significant (P<0.05). On the other hand, other measurements show that these differences were considered statistically non-significant (P>0.05). CONCLUSIONS: In the low-angle group, the parallelisation of the occlusal plane tends to be more obvious compared with the two other groups. In the coronal section of the low-angle group, the axis of the mandibular first molar is up-right, whereas it is distally tilted in the sagittal section of the high-angle group. Furthermore, a number of differences are noted in the adult groups. Factors, such as aging and development in the craniofacial region, lead to changes in functional occlusion.

Characteristics of mandible and mandibular dentition according to vertical facial skeletal features of adolescents / 华西口腔医学杂志

OBJECTIVE@#We aim to examine teenagers with varying vertical facial skeletal types with near-normal occlusion. We further aim to identify and study mandibular morphology and dentition characteristics to establish normal ranges and variations for future clinical reference.@*METHODS@#According to the results of the case studies, 42 adolescents with near-normal occlusion were divided into three groups, namely, low- (7 cases), average- (23 cases) and high-angle (12 cases) groups. We used Invivo 5 software for Digital Imaging and Communications in Medicine (DICOM) data to calculate the cant of occlusal plane, axis corner of L6, ∠L1/MP, ∠L6/MP, Balkwill angle and Bonwill triangle of each group.@*RESULTS@#Markedly, the finding shows that the cant of occlusal plane and axis corner of L6 in the low-angle group were smaller than those of the other two groups. In the average-angle group, ∠L1/MP was larger than that of the high-angle group. Lastly, in the high-angle group, ∠L6/MP was smaller than those of the two other groups. On the one hand, these differences were considered statistically significant (P0.05).@*CONCLUSIONS@#In the low-angle group, the parallelisation of the occlusal plane tends to be more obvious compared with the two other groups. In the coronal section of the low-angle group, the axis of the mandibular first molar is up-right, whereas it is distally tilted in the sagittal section of the high-angle group. Furthermore, a number of differences are noted in the adult groups. Factors, such as aging and development in the craniofacial region, lead to changes in functional occlusion.

Association of sella turcica bridging with palatal canine impaction in skeletal Class I and Class II.

PURPOSE: Based on the evidence of the embryonic origin of the sella turcica and the teeth, this retrospective study evaluated the association between sella turcica bridging and palatal canine impaction in skeletal Class I and Class II orthodontic patients. METHODS: Sixty-two orthodontic patients with palatally impacted canines and 54 controls with erupted canines (aged 12-25 years) were classified into skeletal Class I and Class II (according to ANB angle and Wits analysis). The length, depth, and diameter of the sella turcica were measured, and the shape was described. The difference in linear dimensions between the study and control groups was calculated using two-way analysis of variance and Student's t-test. The interrelationship of the variables, subject groups, skeletal type, and age, with the linear dimensions of sella turcica, was tested using regression analyses. The association between sella turcica, bridging and palatally impacted canines was determined in skeletal type using a chi-square test. RESULTS: Highly significant differences were found in the length, diameter, and depth of the sella turcica between the study sample and the control (P<0.001, P=0.015, P<0.0001, respectively). There was a highly significant frequency of bridging in cases with palatally impacted canines (P<0.0001). An increasing incidence of bridging was found in subjects with palatally impacted canines and skeletal Class I (P<0.0001) and Class II (P=0.044) relationships. Regression analysis showed that the age was significantly related to a change in length (P=0.025), diameter (P<0.0001), and depth (P<0.0001). The normal sella turcica morphology was present in most subjects (56.4%), and no significant association was found in subjects with palatally impacted canines in terms of the shape of the sella turcica. CONCLUSION: Sella turcica bridging is frequently seen in patients with impacted canines. The findings suggest that careful monitoring of canine eruption is required in patients diagnosed with sella turcica bridging at an early age.

[Characteristics of mandible and mandibular dentition in patients with near-normal occlusion and different vertical facial skeletal types].

Objective The aim of our work is to characterize individual normal occlusions to establish appropriate treatment standards for different vertical facial types. Methods A total of 30 patients with near-normal occlusion were grouped into high-angle group (eight cases), medium-angle group (12 cases), and low-angle group (10 cases) according to vertical facial skeletal type. Invivo5 software was used and digital imaging and communications in medicine data were rebuilt to measure the ∠L1/MP, ∠L6/MP, axis corner of L6, cant of occlusion plane, Balkwill angle, and Bonwill triangle of each group. Results Among the groups, the low-angle group had the smallest ∠L6/MP (P<0.05) and largest cant of occlusion. No significant difference was observed among the three groups with regard to the other parameters (P>0.05). Conclusion Patients with low-angle vertical facial skeletal type requires a modified treatment standard. In this group, the treatment standard must ensure that the cant of occlusion plane is more parallel to the Frankfurt horizontal plane compared with those of the other groups, and the axis of L6 is tilted distally relative to the mandibular plane.

Characteristics of mandible and mandibular dentition in patients with near-normal occlusion and different vertical facial skeletal types / 华西口腔医学杂志

Objective The aim of our work is to characterize individual normal occlusions to establish appropriate treatment standards for different vertical facial types. Methods A total of 30 patients with near-normal occlusion were grouped into high-angle group (eight cases), medium-angle group (12 cases), and low-angle group (10 cases) according to vertical facial skeletal type. Invivo5 software was used and digital imaging and communications in medicine data were rebuilt to measure the ∠L1/MP, ∠L6/MP, axis corner of L6, cant of occlusion plane, Balkwill angle, and Bonwill triangle of each group. Results Among the groups, the low-angle group had the smallest ∠L6/MP (P<0.05) and largest cant of occlusion. No significant difference was observed among the three groups with regard to the other parameters (P>0.05). Conclusion Patients with low-angle vertical facial skeletal type requires a modified treatment standard. In this group, the treatment standard must ensure that the cant of occlusion plane is more parallel to the Frankfurt horizontal plane compared with those of the other groups, and the axis of L6 is tilted distally relative to the mandibular plane.

Inclination of lower incisors among the female patients with beautiful profiles in different vertical skeletal types / 实用医学杂志

Objective To study the differences in the inclination of lower incisors among the female patients with beautiful profiles in different vertical skeletal types so as to provide the clinical treatment design for a certain guiding. Methods 137 cephalometric films of female patients with beautiful profiles were selected and divided into three groups based on the vertical facial types(∠SNMP):small degree(n = 31),average degree(n = 89) and larger degree groups(n=17). The angles of∠L1/MP and∠L1/A-Pog were measured and treated with covari-ance analysis for detecting the differences between the groups. Results The index of L1-MP(°)was the smallest in the larger degree group,the largest in the small degree group and average in the average group,with significant differences between the three groups(F = 17.38,P 0.05). Conclusion Lower incisors have compensatory inclined lingually in the group of higher mandible angle,but labially in the group of lower mandible angle.

Three-dimensional assessment of the temporo-mandibular joint in skeletal class II malocclusion females with high vertical pattern / 实用口腔医学杂志

Objective:To study the morphological characteristics of temporo-mandibular joint with high angle vertical skeletal pattern in adult females with class II skeletal type.Methods:41 CBCT films of adult females (20 normal controls;21 skeletal class II high angle subjects)were collected.The position of and form of condyle,form of fossa and joint spaces were measured by Mimics 17.0 soft-ware.Results:Compared with the control group the condyles in high angle patients located more posterior.The joint fossae were lower. The angles of posterior joint node bevels were smaller.The condyles were shorter,thinner and tipped more anteriorly.The position of the conyles were more anteriorly.Conclusion:Class II skeletal type adult females with high vertical skeletal patterns have different forms of fossae,different positions and forms of condyle compared with the normal controls.

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.

Analysis of dentoalveolar compensation and discrimination of skeletal types / 대한치과교정학회지

The purpose of this study is to analyze dentoalveolar compensation in normal occlusion samples previously classified into 9 skeletal types, and to provide clinically applicable diagnostic criteria for individual malocclusion patients. Cephalometric measurements of the 294 normal occlusion samples previously divided into 9 types were analyzed. The descriptive features of dentoalveolar variables were compared for the 9 types using analysis of variance, followed by post hoc multiple comparisons. In addition, the correlation between skeletal and dentoalveolar variables were analyzed. Discriminant analysis with a stepwise entry of variables was designed to find out several potential variables for use in skeletal typing. The dentoalveolar compensation pattern of the skeletal types varied, especially with regards to the variables that indicated the inclination of incisors and the occlusal plane. Stepwise variable selection identified four variables: AB- MP, SN-AB, PMA and ANB. Discriminant analysis assigned a classification accuracy of 87.8% to the predictive model. On the basis of these results, this study could provide rudimentary information for the development of diagnostic criteria and treatment guidelines for individual skeletal types.

Relationship between CO-CR discrepancy and facial skeletal type / 대한치과교정학회지

The present study was performed to prove the relationship between CO-CR discrepancy and facial skeletal type. In this study, 242 subjects were randomly selected and devided into 9 groups(devided into class I, Il, 111 by ANB and each one devided into dolicho-, brachy mesofacial skeleton by Ricketts' vertical index). Lateral cephalometric radiographs with the mandible in centric occlusion were taken and measured and CO and CR bites were registered on all subjects. Diagnostic casts were mounted on Panadent articulator using an estimated face-bow and centric relation bite registration. The amount and direction of CO-CR discrepancy present was recorded using a Condylar Position Indicator(CPI) and a centric occlusion wax bite registration. CPI measurements and cephalometric measurements were statistically analyzed. The finding of this study can be summerized as follows: 1. There is little correlation between right and left sides for magnitude or direction. of CO-CR discrepancies. The correlation between the magnitude of CO-CR discrepancy of left A-P and right A-P is higher than that of left S-I and right S-I. 2. Correlation of Class H malocclusion group was higher than that of the other groups between the magnitude of CO-CR discrepancy of left CPI and right CPL 3. There is no difference between the pattern of CO-CR discrepancy of 9 malocclusion groups. 4. There is very little, if any, correlation between Skeletofacial measurements and CO-CR discrepancy. 5. In Class II brachyfacial skeleton and Class IIl mesofacial skeleton there was Lateral cephalometric measurements by that we predict CPI measurements was detected. That was overbite, overjet, upper gonial angle, lower gonial angle, saddle angle, articular angle, convexity of point A, ANS-Me/Na-Me, PCBL/I3H, Posterior FH/anterior FR