Vertical Facial Pattern Research Articles

Differences in the Buccolingual Inclinations of Premolars Among Class II Division I Subjects With Different Vertical Facial Patterns

Differences in the Buccolingual Inclinations of Premolars Among Class II Division I Subjects With Different Vertical Facial Patterns

Impact of vertical facial type on alveolar bone thickness and tooth morphology: A retrospective CBCT-based clinical study

IntroductionThe relationship between vertical facial patterns and the morphology of the alveolar bone and teeth is crucial for successful orthodontic treatment planning. This study aimed to evaluate the relationship between vertical facial patterns, bone thickness, and root-crown dimensions in the maxillary anterior teeth. MethodsThis retrospective study screened 300 cone-beam computed tomography (CBCT) scans of orthodontic patients between December 2022 and November 2023, with 115 meeting the inclusion criteria. Buccal and lingual alveolar bone thickness, along with crown and root lengths of maxillary anterior teeth, were measured and compared across short, normal, and long facial types, classified according to the Frankfort-Mandibular Plane Angle. One-way ANOVA, independent-samples Kruskal-Wallis, and post-hoc tests were used for statistical analysis. ResultsSignificant differences in alveolar bone thickness were observed across facial types, with short facial types showing consistently greater thickness in the apical and mid-palatal regions compared to normal and long facial types (p < 0.05). No significant differences in crown or root lengths were found among the facial types. ConclusionFacial type significantly influences alveolar bone thickness, particularly in short facial types, which demonstrate greater bone support. These findings underscore the importance of considering facial type in orthodontic treatment planning to minimize complications.

To evaluate the cortical bone thickness for ideal placement of infrazygomatic crest (IZC) and mandibular buccal shelf (MCS) bone screws in patients with different facial pattern using cone-beam computed tomography (CBCT)

This study aimed to measure the cortical bone thickness at different anatomical sites of InfraZygomatic Crest and Mandibular Buccal Shelf region for the ideal placement of IZC and MBS screws respectively in patients with different facial patterns using CBCT.Total participants were divided into 3 groups- GROUP A: horizontal growth pattern (FMA &amp;#60;22°); GROUP B: average growth pattern (FMA 22°-28°); GROUP C: vertical growth pattern(FMA &amp;#62;28°). Sixty CBCT images were taken into consideration. They were converted into standard DICOM format. Bone thickness were measured in the InfraZygomatic Crest (IZC) of the maxilla and in the Mandibular Buccal Shelf (MBS) region of the mandible using the Kodak CareStream CS 9300 Software.The results indicate that there was a highly statistical significant difference seen in the overall cortical bone thickness of IZC and MBS at various anatomical sites. The highest mean thickness was found to be at the MB70◦ maxillary 1st molar and distal root of the mandibular 1st molar. There was no difference in the bone thickness at the IZC region and at the MBS region seen between the horizontal and vertical facial patterns whereas the average facial patterns show the highest mean thickness but was not statistically significantThe study conducted on the Indian population yielded results demonstrating the possibly appropriate position for the IZC bonescrews and MBS bonescrews suggested that placing the IZC bonescrews at the mesiobuccal root of the maxillary 1st molar at an angulation of 70◦ and the MBS bonescrews at the distal root of the mandibular 1st molar at 11mm from the cementoenamel junction irrespective of the facial patterns could provide positive results.

Dentoalveolar bone height in Class I adults with different vertical patterns: A cross-sectional study

Facial divergence during growth and development affects both the anterior and posterior alveolar bone dimensions in the maxilla and mandible, and the dentoalveolar compensation mechanism in severe vertical skeletal discrepancies remains unclear. To evaluate the: (1) difference in dentoalveolar heights among subjects with different vertical facial patterns; (2) association between the dentoalveolar bone height and other cephalometric variables; (3) effect of sex on dentoalveolar height measurements. Non-growing subjects with skeletal Class I (0°<ANB<4°), Class I canine and molar relationship and complete fully erupted dentition were included in the study. Cephalometric measurements were taken on lateral cephalograms and patients were stratified into hyperdivergent, hypodivergent, and normodivergent groups based on MP/SN angle. A two-way analysis of variance (ANOVA) was used to compare cephalometric measurements between the divergence and sex groups. Measurements on a total of 204 patients (81 males, 123 females) were analysed. At the level of the incisor and premolar regions, both dentoalveolar and alveolar bone heights were significantly larger in hyperdivergent group when compared to hypodivergent group, whereas at the level of the molar region, no difference was found among groups. Moderate to strong correlations were found between dentoalveolar bone and vertical skeletal measurements. In the maxilla and mandible, the dentoalveolar compensation mechanism in skeletal Class I subjects results in an increased vertical height in the anterior dentoalveolar segment in hyperdivergent subjects and a reduced one in hypodivergent subjects.

Evaluation of Buccolingual Inclinations of First Molars Among Different Vertical Facial Patterns in Class II Division I Subjects.

Background Knowing the characteristics of vertical patterns is crucial to provide the best orthodontic treatment. Cone beam computed tomography (CBCT) offers a valuable tool for evaluating true buccolingual inclinations. The current study investigates the buccolingual inclination of first molars in adult subjects with different vertical facial patterns. Methods CBCT scans of 66 adult patients (31 males, 35 females) with a mean age of 31.6 years (SD: 6.4 years) exhibiting skeletal class II division I maxillomandibular relationships were employed. Participants were categorized into three groups based on linear and angular measurements: normodivergent group (n=22), hypodivergent group (n=22), and hyperdivergent group (n=22). The independent samples t-test and Mann-Whitney U-test were conducted to investigate statistical differences in terms of buccolingual inclination between the three vertical patterns. Results Statistically significant differences were observed in the buccolingual inclinations of both maxillary and mandibular first molars in the hypodivergent group compared to the other groups (p<0.05). Conclusions In patients with class II division I sagittal relationships, the buccolingual inclinations of the first molars exhibit similarities between normodivergent and hyperdivergent groups. However, these inclinations differ significantly in hypodivergent adult subjects.

Comparison of Soft Tissue Chin Thickness in Adult Patients With Various Mandibular Divergence Patterns.

Objective This study aimed to compare the soft tissue chin (STC) thickness at different levels in patients presenting for orthodontic treatment with different vertical facial types. Materials and methods This comparative cross-sectional study was conducted at Sharif Medical & Dental College, Lahore, Pakistan, on 195 subjects. Patients presenting for orthodontic treatment, both genders, aged from 18 to 32 years, and Pakistani nationals were included. Patients with any craniofacial deformity, syndrome, cleft lip and palate, previous orthodontic or orthognathic treatment, and multiple missing teeth and prostheses in edentulous areas were excluded. Vertical facial patterns and STC thickness were recorded from pre-treatment lateral cephalograms. One-way analysis of variance (ANOVA) was applied to compare STC among various vertical facial patterns. Post-hoc analysis was done using the Tukey test. Results There were 126 females (64.62%) and 69 males (35.38%). The mean age was 21.66 ± 3.44 years. All three soft tissue chin thickness distances significantly differed among vertical facial patterns (p<0.001). Multiple comparisons show that the distance between soft and hard tissue pogonion was insignificant between low and normal anglefacial heights (p=0.5). Similarly, no significant difference was observed for the distance between softand hard tissue menton in low and normal angle subjects (p=0.4). The rest of the multiple comparisons were statistically significant (p<0.05). Conclusion The STC thickness is significantly associated with vertical facial divergence. While planning orthognathic surgery or genioplasty of the mandible, due consideration should be given to vertical divergence of the face to avoid unwanted facial changes.

Basal and dentoalveolar transverse parameters in different sagittal and vertical malocclusions in adults: a comparative study.

This study sought to three-dimensionally (3D) evaluate the maxillomandibular basal bone and dentoalveolar widths using cone-beam computed tomography (CBCT) scans in adult Chinese populations with different vertical and sagittal facial skeletal patterns whilst no apparent posterior dental crossbite. The retrospective cross-sectional comparative study enrolled CBCT images of 259 adult patients (125 males and 134 females). The subjects were divided into the hyperdivergent(n = 82), hypodivergent(n = 88), and normodivergent(n = 89) groups based on the Jarabak ratio (S-GO/N-Me), which were further divided into three subgroups of skeletal Class I, II and III, based on both the ANB angle and AF-BF parameters. ANOVA was used to analyze the extracted data of the studied groups. The intra- and inter-observer reliability was analyzed using the intra-class correlation coefficient (ICC). In all three vertical facial skeletal patterns, the skeletal Class II had significantly smaller mandibular basal bone width compared to skeletal Class I and Class III, both at the first molar and first premolar levels. The skeletal Class III seemed to have smaller maxillary basal bone width compared to skeletal Class I and Class II malocclusions; however, a significant difference was found only in the normodivergent pattern. As for the dentoalveolar compensation, it was most notable that in the hypodivergent growth pattern, the skeletal Class II had significantly smaller maxillary dentoalveolar width compared to the Class I and Class III groups, both at the first molar and first premolar levels. Based on the sample in the present study, skeletal Class II has the narrowest mandibular basal bone regardless of the vertical facial skeletal pattern. For Chinese adults with no apparent transverse discrepancy, the maxillomandibular basal bone and dentoalveolar widths are revealed in specific categories based on different vertical and sagittal facial skeletal patterns. In diagnosis and treatment planning, particular attention should be paid to skeletal Class II for possibly existing mandibular narrowing.

Relationship between dental arch width and vertical facial morphology in untreated Indian population

Introduction: Facial growth pattern is an important factor in planning orthodontic treatment properly. Knowledge of arch forms is important for an orthodontist, as it is related to future treatment outcome. Factors such as age, sex, and ethnicity are also important. The purpose of present study was to evaluate the dental arch dimensions in a different facial pattern in regional population, to evaluate correlation in the facial pattern with dental arch width to evaluate the differences in dental arch width between male and female subjects. Materials: The present study was conducted on 120 untreated subjects comprising of 60 males and 60 females aged between 16 to 38 years. The Jarabak’s ratio (posterior facial height/anterior facial height) was measured on cephalograms of each patient. Maxillary and mandibular inter-canine, first inter-premolar, second inter-premolar and first inter-molar widths were measured on study models of each patient. Results: There was no significant correlation between dental arch width and vertical facial pattern in regional population. In males, arch width is greater in canine, premolar and molar region than females. Conclusion: It was concluded that dental arch width is not associated with the vertical facial pattern but it is associated with gender. Thus, using individualized arch wires according to gender is suggested during orthodontic treatment. Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S26-S31

Correlation Between Cephalometric Values and Soft Tissue Profile in Class I and Class II Adult Patients based on Vertical Patterns.

To compare soft tissue profile variations between Class I and Class II adult patients due to three vertical skeletal facial patterns (normodivergent, hypodivergent and hyperdivergent) and determine which skeletal variation has the most significant impact on soft tissue profile. Retrospective soft tissue profile analysis was performed on lateral cephalograms of 131 adult patients. The analysis was divided into two categories correlated with subnasal and general soft tissue profiles. The sample was divided based on two sagittal skeletal patterns (Class I and II) and three vertical groups. In addition, comparisons were made between males and females. Viewbox 4 was used for the analysis. Descriptive, comparative, and correlation statistics were performed using SPSS software. Statistically significant inter-gender differences were found at the subnasal profile level, but not at the general profile level. No significant differences were observed when comparing subnasal profiles for the sagittal groups. However, significant differences were observed at the level of the general profile, especially at the level of Z-angle, lower lip, and chin prominence. In the vertical groups, hyperdivergent facial patterns had significant differences at the level of subnasal and general profiles compared with other vertical facial patterns. Females had more convex subnasal profiles than males. Hyperdivergent facial patterns had an impact on both general and subnasal soft tissue profiles. The sagittal dimension affected only the general soft tissue profile. Therefore, changes in the vertical dimension had the greatest impact on facial esthetics.

Evaluation of the anterior dentoalveolar relationship in skeletal Class III malocclusion patients with different vertical facial patterns using cone-beam computed tomography.

To measure and compare labiolingual inclinations of the teeth and alveolar bone and the anterior dentoalveolar inclination in patients with skeletal Class III malocclusions with different vertical facial patterns using cone-beam computed tomography (CBCT). Based on the inclusion and exclusion criteria, 84 CBCT images of patients with untreated skeletal Class III malocclusion were selected. There were 28 patients each in the hypo-, normo-, and hyperdivergent groups. The labiolingual inclinations of the teeth, the corresponding alveolar bone, and the anterior dentoalveolar inclinations were measured and analyzed statistically. The inclinations of the mandibular canine and corresponding alveolar bone were smaller in the hypodivergent group than in the hyperdivergent group. The inclination of the alveolar bone and the maxillary dentoalveolar inclination were smaller in the hyperdivergent group than in the hypodivergent group. There were differences in the inclination of the teeth, corresponding alveolar bone, and dentoalveolar inclinations at different positions among skeletal Class III patients with different vertical facial patterns. The roots were generally located on the labial side of the alveolar bone.

Associations between the 3D position of the mental foramen with sagittal skeletal relationships (classes I, II, and III) and vertical facial growth patterns (normal, long, and short faces) in different ages and sexes: a retrospective cohort study of 360 CBCTs

BackgroundThe 3D position of the mental foramen (MF) is of significant clinical value in dental implantology and mandibular surgeries or in local anesthesia. Despite its importance, it is not clearly known how the position of MF can alter in different individuals, since the literature on the associations between the MF position with vertical growth patterns is non-existent and those on links between the MF position and skeletal malocclusions are scarce. Therefore, we aimed to investigate these, for the first time, on cone-beam computed tomographies (CBCTs).MethodsArchival CBCTs of 9 sub-groups (i.e., 3 skeletal Classes I, II, and III × 3 vertical growth patterns ‘long face, short face, normal face’) were collected by evaluating patients’ SNA, SNB, ANB, facial angle, lower facial height, and FMA (n = 9 × 40 = 360). Included cases were older than 17 years and without any history of orthodontic/orthognathic treatments (243 women, 117 men, mean age: 22.28 ± 2.80 years). Perpendicular distances between the MF and 3 fixed bony structures (the mandibular symphysis [S/width], the mandibular ramus [R/length], and the mandibular lower cortex [C/height]) were measured on different sectional planes on both hemimandibles. Left- and right-side measurements were combined. Data were analyzed using the 3-way ANCOVA, Bonferroni, one-way ANOVA, Tamhane, Pearson, and t-test (α = 0.05).ResultsWidth was the smallest in Class II and greatest in Class III cases (all P values < 0.000001, Bonferroni). It was the shortest in long faces and longest in short faces (all P values ≤ 0.00008). The inferior-superior height was larger in Class III than both Classes I and II (both P values ≤ 0.003); there was no significant difference between Classes I and II in terms of height (P = 0.684). Height was the largest in long faces and smallest in short faces (all P values < 0.000001). The anterior-posterior length was the largest in Class III and smallest in Class II (all P values < 0.000001). Length was larger in short-face people versus normal- or long-face individuals (P ≤ 0.00003); nevertheless, long and normal faces did not differ in terms of length (P = 0.448). Subjects’ age was not correlated with their MF positions (P ≥ 0.579, Pearson coefficient). Sex dimorphism existed only for height (P = 0.009, t-test) but not for length or width.ConclusionsThe MF position may considerably differ in various horizontal or vertical growth patterns and sexes. This should be noted in mandible surgeries.

Assessment of mandibular cortical bone thickness for miniscrew placement in relation to the vertical facial patterns using CBCT: A cross-sectional Study

Introduction: The need of more anchorage in the orthodontic daily practice has introduced the use of temporary anchorage devices (TADs). Cortical bone thickness has been one of the major factors on the success rate of the stability of TADs. Different vertical dimension patterns can be found among orthodontic patients with potentially variable cortical bone thickness. Aim of the study: to assess the cortical bone thickness in the posterior region of the mandible in relation to different vertical facial patterns using Cone-beam computed tomography (CBCT) and to evaluate the progressive change in the thickness of cortical bone from 4,6 to 8 mm from the crest of the alveolar bone toward the apical region. Methods: Thirty-six participants were selected and their cephalometric x-rays and CBCTs were analyzed and compared. Vertical facial pattern was measured with the use of the mandibular plane angle and participants were grouped in 3 categories according to the measures. On the CBCTs, buccal and lingual cortical bone thickness were measured from 4,6 and 8 mm from the alveolar crestal bone and compared. All analyses were conducted using IBM SPSS Statistics for Windows, v.26 (IBM Corp., Armonk, NY, USA). The significance level was set at α = 0.05 for all statistical analyses. Results: There was no statistically significant differences were observed between the vertical dimensions groups in terms of buccal and lingual measurements at 4, 6, and 8 mm from cemento-enamel junction (CEJ) between 44/45, 45/46, and 46/47 (P&gt;0.05). Conclusions: There was a progressive increase in cortical bone thickness in most of the studied groups from the alveolar crest to the apical region.

Relationship between vertical facial morphology and dental arch measurements in class II malocclusion: a retrospective study.

To evaluate the relationship between dental arch measurements and the vertical facial pattern determined in skeletal Class II untreated patients. Lateral cephalograms and plaster models were obtained from 124 untreated female adults (average age: 17.6 ± 3.8 years). Class I (CI), Class II Division 1 (CII/1) and Class II Division 2 (CII/2) malocclusions were divided into three subgroups according to their vertical morphology as hypodivergent, normodivergent and hyperdivergent. The multivariate variance analysis (MANOVA) method was used in the comparison of measurement values according to vertical and sagittal morphology. The relationship between both A point-Nasion-B point (ANB) and Frankfurt-mandibular plane (FMA) angles and dental arch measurements was examined by Pearson correlation analysis. The significance level was received as p < 0.05. While vertical morphology has a statistically significant effect on mandibular arch length, sagittal morphology affects maxillary arch depth. The parameters influenced by both morphologies are maxillary and mandibular arch length, as well as maxillary intermolar width. The mandibular arch length was significantly shorter in hyperdivergent-CII-2 malocclusion (50.5 ± 7.4 mm). Larger values were obtained in both mandibular arch length and maxillary arch depth measurements in CII-1 malocclusion compared to CII-2 malocclusion. The maxillary intermolar width was significantly shorter in hypodivergent-CII-1 malocclusion (46.8 ± 3.4 mm), while it was higher in hypodivergent-CI malocclusion (51.1 ± 3.4 mm). The maxillary arch length was the lowest in hyperdivergent-CI malocclusion (63.1 ± 13.3 mm) and the highest in hypodivergent-CI malocclusion (72.8 ± 7.6 mm). Additionally, a positive but weak correlation was found between ANB and FMA angles. Dental arch measurements have been found to be affected by both vertical facial morphology and skeletal sagittal relationship. A positive correlation was found between ANB and FMA angles.

Association of Anterior and Posterior occlusal planes with skeletal class I, class II and class III malocclusion

Introduction: The occlusal plane is a very vital in stomatognathic system and the association between anterior occlusal planes and posterior occlusal plane plays an important role during orthodontic treatments. Methods: Lateral cephalometric radiographs of 270 adult patients of the different classes of malocclusion were used. Several angular measurements were measured and compared among all study groups to evaluate the existence of relationship between AOP and POP with skeletal and vertical patterns. Results: The skeletal patterns showed a significant difference in anterior occlusal plane angle relative to both SN plane and FH plane among all classes of malocclusion (p-value =0.001**) having a steeper inclined plane in Class II and flat inclined plane in Class III. POP in relation to FH plane and SN plane showed lowest angle in skeletal Class III and highest in Skeletal Class I patients. Conclusion: The occlusal planes were found to have an impact on the jaw base where the variation in its angulation of different occlusal planes had affected both sagittal and vertical facial patterns. AOP relative to SN and FH were steeper in Class II and flat in Class III, while the POP relative to FH showed the same value in Classes II and III. Keywords: Anterior occlusal plane, Posterior occlusal plane, Malocclusion, Skeletal patterns, Vertical pattern, Lateral cephalometric radiograph.

Customized planning of the visible maxillary arch width in harmony with interparopia width and smile width for female facial aesthetics.

The visible maxillary arch width (VAW) is an important aesthetic-determining feature. To date, there is no well-established methodology to determine the aesthetically optimal VAW in customized treatment planning. In this study, the common traits of the dentofacial configuration were investigated in most attractive Asian and Caucasian female smiles. The smiling photo of a subject was digitally modified based on combined variations of VAW, smile width (SW), transverse facial dimensions (TFD), and vertical facial dimensions. These modified photos were assessed for aesthetics. The aesthetically essential parameters were identified, and their mathematic correlations and reference ranges were determined for different vertical facial patterns. Using the obtained results, a mathematic guidance was constructed for customized smile designing. The applicability of this guidance was tested in Asian females. The most attractive Asian and Caucasian female smiles have intraracial and interracial commonalities in the VAW-to-TFD ratios. The interparopia width (IPD) predominated over facial widths in determining well-matched VAW and SW. For optimal smile aesthetics, the VAW and SW were correlated as simulated by the formula 1.92 IPD ≤ VAW + 2.3 SW ≤ 2.17 IPD, plus the VAW-to-IPD ratio within 0.54 to 0.62 and the SW-to-IPD ratio within 0.61 to 0.71, ranges tailored to vertical facial patterns. This constitutes a mathematic guidance for customized planning of the aesthetically optimal VAW. This guidance was preliminarily validated to be applicable to Asian females. The VAW-to-TFD ratios were essential for Caucasian and Asian female smile aesthetics. The mathematic guidance could serve as a reference for customized smile designs for Asian females.

A Cone Beam Computed Tomography Analysis of Bone Volume Variations of Extra-alveolar Region Based on Sex, Age, Vertical and Sagittal Facial Patterns.

The goal of this study is to measure mandibular buccal shelf (MBS) concerning angulation, bone volume, and cortical bone volume as well as bone depth and cortical bone depth of infrazygomatic crest (IZC) via cone beam computed tomography and evaluate the measurements according to sex, age, vertical, and sagittal facial types. This study collected lateral cephalograms and cone beam computed tomography scans from 100 individuals, which were used to observe angulation, bone and cortical bone volume entailing width and depth of MBS as well as the depth of IZC. FH-MP (mandibular plane angle) and A point-Nasion-B point were adopted to determine vertical and sagittal facial patterns respectively. Bone widths at 6mm and 11mm to cementoenamel junction (CEJ) and cortical bone width at 6mm to CEJ in MBS showed significant sex differences, while bone depths and cortical bone depths in IZC show significant age difference( P <0.05). Bone width and cortical bone width at 6mm to CEJ at the mesial root and 11mm to CEJ at both roots as well as angulations of MBS in the mandibular first molar region, bone depth and cortical bone depth at the maxillary first molar distal buccal root, and the proximity region were all correlated to FH-MP ( P <0.05). Short-faced individuals of Asian ethnicity tend to have greater bone width, greater projection in MBS, and greater bone depth in the posterior region of IZC. The optimal implant sites are 11mm apical to CEJ at the mandibular second molar distal root and 65° at the maxillary first molar mesial root.

Automated diagnostic classification with lateral cephalograms based on deep learning network model

Objective: To establish a comprehensive diagnostic classification model of lateral cephalograms based on artificial intelligence (AI) to provide reference for orthodontic diagnosis. Methods: A total of 2 894 lateral cephalograms were collected in Department of Orthodontics, Capital Medical University School of Stomatology from January 2015 to December 2021 to construct a data set, including 1 351 males and 1 543 females with a mean age of (26.4± 7.4) years. Firstly, 2 orthodontists (with 5 and 8 years of orthodontic experience, respectively) performed manual annotation and calculated measurement for primary classification, and then 2 senior orthodontists (with more than 20 years of orthodontic experience) verified the 8 diagnostic classifications including skeletal and dental indices. The data were randomly divided into training, validation, and test sets in the ratio of 7∶2∶1. The open source DenseNet121 was used to construct the model. The performance of the model was evaluated by classification accuracy, precision rate, sensitivity, specificity and area under the curve (AUC). Visualization of model regions of interest through class activation heatmaps. Results: The automatic classification model of lateral cephalograms was successfully established. It took 0.012 s on average to make 8 diagnoses on a lateral cephalogram. The accuracy of 5 classifications was 80%-90%, including sagittal and vertical skeletal facial pattern, mandibular growth, inclination of upper incisors, and protrusion of lower incisors. The acuracy rate of 3 classifications was 70%-80%, including maxillary growth, inclination of lower incisors and protrusion of upper incisors. The average AUC of each classification was ≥0.90. The class activation heat map of successfully classified lateral cephalograms showed that the AI model activation regions were distributed in the relevant structural regions. Conclusions: In this study, an automatic classification model for lateral cephalograms was established based on the DenseNet121 to achieve rapid classification of eight commonly used clinical diagnostic items.

Effect of the vertical facial pattern on the developmental relationship between the nasal bone and maxillary central incisors

BackgroundThis study aimed to investigate the effect of vertical facial patterns on the developmental relationship between the nasal bone and maxillary central incisors.MethodsIn this retrospective comparative study, the lateral cephalograms of 213 subjects (51 Males, 162 Females) with skeletal Class I malocclusion (aged 18–32 years) were classified into three equal groups: (1) hyperdivergent, (2) normodivergent, and (3) hypodivergent facial patterns based on the mandibular plane inclination (S–N/Go-Me). Several sets of measurements were extracted: (1) gradient and length of the nasal bone and maxillary central incisor, (2) the distance from apex and root of the nasal bone, and (3) maxillary central incisor to the true perpendicular from the digitized lateral cephalograms. The significance level was considered at P < 0.05.ResultsThe inclination angle and length between nasal bone and maxillary central incisor were positively correlated independent of vertical facial type. The inclination angle of the nasal bone in the hypodivergent group was significantly larger than the other two vertical facial patterns. The inclination angle of the maxillary central incisor increased successively in the hyperdivergent, normodivergent, and hypodivergent groups. The length of the nasal bone in the hyperdivergent group was significantly longer than that in the hypodivergent and normodivergent groups. The maxillary central incisor length in the hyperdivergent group was significantly longer than in the hypodivergent group.ConclusionA correlation between nasal bone and maxillary central incisors during the growth and development of the maxillofacial region was found. In Class I malocclusion subjects, hypodivergent patients were more likely to have a prominent and relatively short nasal bone and maxillary central incisors and vice versa.

Clinical-statistical study on the use of articulators in orthodontic practice

Dental-maxillary anomalies are accompanied by changes in the interbasal maxillary ratio in all reference planes, with influences on the functionality of articular structures. These joint changes not detected in time and not included in the treatment plan may worsen while wearing fixed appliances, as orthodontic treatment changes the cranio-mandibular position and causes cranio-mandibular reshaping. The articulator is an instrument that reproduces more or less all mandible movements. TMJ characteristics of skeletal dento-maxillary anomalies, especially class II sagittal pattern mainly reflected in condylar position rather than morphology. TMJ of different vertical patterns differed more in joint spaces, position of condyle and glenoid fossa than in morphologic measurements. Vertical position of glenoid fossa and proportion of posterior condyle increased gradually from hypodivergent to hyperdivergent. Highest glenoid fossa position, maximum ratio of posterior positioned condyle, smallest joint spaces, shallowest glenoid fossa depth, and narrowest condylar long axis diameter were found in skeletal class. The patients with high angle have considerable joint instable factors, and we should especially pay attention when orthodontic treatment is carried out on them. The condyle-fossa position and morphology differ with various vertical facial patterns in individuals with skeletal Class II mandibular retrognathism. These differences could be considered during temporo-mandibular diagnosis and orthodontic treatment

A CBCT Evaluation of the Proximity of Mandibular Molar Roots and Lingual Cortical Bone in Various Vertical Facial Patterns and Factors Related to Root-Cortical Bone Contact

The objective of this study was to assess the proximity of the mandibular molar roots and the lingual cortical bone in patients with various vertical facial patterns and determine factors related to root-cortical bone contact. A total of 145 patients (84 males, 61 females, mean age: 22.0 ± 1.76 years) were assigned to hypodivergent (36 patients), normovergent (80 patients) and hyperdivergent (29 patients) groups based on their facial height ratio. Cone-beam computed tomography (CBCT) images were used to measure the distance between the mandibular molar roots and the lingual cortical bone, and any instances of root-cortical bone contact were identified. The study investigated the correlation between the contact of the mandibular molar roots with the lingual cortical bone and several variables, including sex and cephalometric measurements. The distance between the mandibular molar roots and the lingual cortical bone was significantly shorter in the hyperdivergent group than in the hypodivergent group (p &lt; 0.05). Of the total root-cortical bone contact, 87.6% was observed in the mandibular second molars, and the distal roots of the mandibular second molars had the highest contact rate at 43.1% in the hyperdivergent group (p &lt; 0.05). Among the evaluated variables, only the distance between the distal root apex of the mandibular second molar and the mandibular plane was found to be associated with contact of the mandibular molar roots with the lingual cortical bone. An increase of 1 mm in this distance was associated with a 22% decrease in the likelihood of contact between the mandibular second molar roots and lingual cortical bone (p &lt; 0.001). Given the proximity and high contact ratio between the mandibular molar roots and lingual cortical bone, it is recommended that these structures be evaluated using CBCT before planning molar distalization or intrusion in hyperdivergent patients.