Frankfort Mandibular Plane Angle Research Articles

Morphometric characteristics of cervical vertebrae in subjects with short, normal, and long faces.

The prolonged change in the head posture alters the morphological characteristics of cervical vertebrae. The difference in the head posture among subjects with short, normal, and long anterior facial heights might have a significant influence on the morphological characteristics of cervical vertebrae. Thus, the present study was conducted to evaluate the morphometric characteristics of cervical vertebrae in subjects with short, normal, and long faces. Based on Frankfort mandibular plane angle (FMA) on lateral cephalograms, 135 subjects were equally divided into three groups, i.e. Group I [Short face], II [Normal face], and III [Long face]. The angular variables like Atlas-dens angle (ADA), Pars interarticularis-dens angle (PDA), Pars interarticularis-vertebrae angle of C3 vertebrae (PVA3), Pars interarticularis-vertebrae angle of C4 vertebrae (PVA4), Lamina-Pars interarticularis angle of C2 vertebrae (LP2), Lamina-Pars interarticularis angle of C3 vertebrae (LP3), and Lamina-Pars interarticularis angle of C4 vertebrae (LP4) in the first four cervical vertebrae were measured, analyzed, and compared. Descriptive statistics, analysis of variance, Bonferroni, and Pearson's correlation coefficient tests were used. The P value of 0.05 was considered as the level of significance. All parameters except PDA and PVA3 were comparable among the groups. The PDA was 54.350 ± 1.870, 57.890 ± 1.550, and 60.290 ± 2.830 in Group I, II, and III, respectively; these differences were statistically significant [P < 0.001]. The PVA3 was 42.700 ± 5.640 in Group I, 45.850 ± 3.820 in Group II, and 45.590 ± 5.530 in Group III subjects that were also statistically significant [P < 0.01]. A fairly strong positive correlation was observed between FMA and PDA. A significant difference was found in the PDA among subjects with short, normal, and long faces. The vertical height of the face had a strong correlation with the morphology of axis vertebra.

Dental and skeletal effects after total arch distalization using modified C-palatal plate on hypo- and hyperdivergent Class II malocclusions in adolescents.

To compare the dental and skeletal treatment effects after total arch distalization using modified C-palatal plates (MCPPs) on adolescent patients with hypo- and hyperdivergent Class II malocclusion. The study group included 40 patients with Class II malocclusion (18 boys and 22 girls, mean age = 12.2 ± 1.4 years) treated with MCPPs. Fixed orthodontic treatment started with the distalizing process in both groups. Participants were divided into hypo- or hyperdivergent groups based on their pretreatment Frankfort mandibular plane angle (FMA) ≤22° or ≥28°, respectively. Pre- and posttreatment lateral cephalograms were digitized, and 23 variables were measured and compared for both groups using paired and independent t-tests. The hyper- and hypodivergent groups showed 2.7 mm and 4.3 mm of first molar crown distalizing movement, respectively (P < .001). The hypodivergent group had a slight 2.2° crown distal tipping of first molars compared with 0.3° in the hyperdivergent group. After distalization, the FMA increased 3.1° and 0.3°, in the hypodivergent and hyperdivergent groups, respectively (P < .001). SNA decreased in the hypodivergent group, while other skeletal variables presented no statistically significant differences in the changes between the groups. The hypodivergent group showed more distal and tipping movement of the maxillary first molar and increased FMA than the hyperdivergent group. Therefore, clinicians must consider vertical facial types when distalizing molars using MCPPs in Class II nonextraction treatment.

Dental and skeletal effects after total arch distalization using modified C-palatal plate on hypo- and hyperdivergent Class II malocclusions in adolescents.

To compare the dental and skeletal treatment effects after total arch distalization using modified C-palatal plates (MCPPs) on adolescent patients with hypo- and hyperdivergent Class II malocclusion. The study group included 40 patients with Class II malocclusion (18 boys and 22 girls, mean age = 12.2 ± 1.4 years) treated with MCPPs. Fixed orthodontic treatment started with the distalizing process in both groups. Participants were divided into hypo- or hyperdivergent groups based on their pretreatment Frankfort mandibular plane angle (FMA) ≤22° or ≥28°, respectively. Pre- and posttreatment lateral cephalograms were digitized, and 23 variables were measured and compared for both groups using paired and independent t-tests. The hyper- and hypodivergent groups showed 2.7 mm and 4.3 mm of first molar crown distalizing movement, respectively (P < .001). The hypodivergent group had a slight 2.2° crown distal tipping of first molars compared with 0.3° in the hyperdivergent group. After distalization, the FMA increased 3.1° and 0.3°, in the hypodivergent and hyperdivergent groups, respectively (P < .001). SNA decreased in the hypodivergent group, while other skeletal variables presented no statistically significant differences in the changes between the groups. The hypodivergent group showed more distal and tipping movement of the maxillary first molar and increased FMA than the hyperdivergent group. Therefore, clinicians must consider vertical facial types when distalizing molars using MCPPs in Class II nonextraction treatment.

Incisor mandibular plane angle (IMPA), Frankfort mandibular plane angle (FMA) and lower incisor to A-Pog distance, and their relation in different skeletal classes

Introduction: Tweed’s cephalometric analysis has its beginning in clinical orthodontics where he found that the cases of malocclusion with pleasing outcome, harmonious profiles and stable occlusion following orthodontic treatment had a common consistent feature of occlusion: their mandibular incisors were upright on their skeletal bases. So the correct position of incisors is essential for achieving stable end results and establish harmony and balance of facial aesthetics. Aims and objectives: The purpose of this study was to evaluate the linear and angular position of mandibular incisors over the basal bone and their relationship with frankfort mandibular plane angle in different skeletal classes.Materials and Methods: A total of 60 lateral cephalograms in the age group of 18-30 years of Class I, Class II, Class III subjects were selected and traced as per inclusion criteria. All the linear and angular measurements were done in each group and their relationship and comparison was done in each group by using ANOVA test and Student’s independent t-test.Results: Descriptive statistical analysis was first carried out to find the means of IMPA, FMA angle and lower incisor to A-pog distance. On doing intergroup comparison with ANOVA test and Student’s independent t-test, statistically significant difference was found only in IMPA and lower incisor to A-pog line distance between Class I and III groups and Class II and Class III groups.Conclusion: There appears to exist a demonstrable relationship between the axial inclination of the mandibular incisors and the incisor mandibular plane angle, the greater the procumbency of the mandibular incisors, the greater the incisor mandibular plane angle in excess of 90 degree and vice versa. There also appears to exist a relationship between the incisor mandibular plane angle and the contour of the lower third of the face. The lower incisors tend to be more upright in subgroups with prognathic mandible than subgroups with normal or retrognathic mandible.

Thickness change of masseter muscles and the surrounding soft tissues in female patients during orthodontic treatment: a retrospective study

BackgroundFacial esthetics is a major concern of orthodontic patients. This study aims to evaluate orthodontic treatment-related thickness changes of the masseter muscles and surrounding soft tissues and the potential factors that would influence these changes during orthodontic treatment in female adults.MethodsForty-two female adult patients were included in this retrospective study and were divided into extraction (n = 22) and nonextraction (n = 20) groups. Pretreatment and posttreatment cone-beam computed tomography (CBCT) images were superimposed and reconstructed. The thickness changes of the masseter area of facial soft tissue (MAS), masseter muscles (MM) and surrounding fat tissue (FT) were measured. Pretreatment age, treatment duration, sagittal relationship (ANB), and vertical relationship (Frankfort-mandibular plane angle, FMA)-related MAS, MM and FT changes were compared between extraction and nonextraction groups. Spearman’s correlation coefficient was calculated between the above variables. Regression analysis was conducted to confirm the causal relations of the variables.ResultsThe thickness of MAS and MM significantly decreased in both groups, with larger decreases (> 1 mm) in the extraction group. There were strong correlations (r > 0.7) between the thickness decrease in MAS and MM in both groups and moderate correlations (r > 0.4) between MAS and FT in the nonextraction group. A significantly greater decrease of MAS and MM were found to be moderately correlated with a smaller FMA (r > 0.4) in the extraction group. Scatter plots and regression analysis confirmed these correlations.ConclusionsMasseter muscles and the surrounding soft tissue exhibited a significant decrease in thickness during orthodontic treatment in female adults. Low-angle patients experienced a greater decrease in soft tissue thickness in the masseter area in the extraction case. But the thickness changes were clinically very small in most patients.

Upper airways evaluation in young adults with an anterior open bite: A CBCT retrospective controlled and cross-sectional study

To compare the dimensions of the upper airway in young adults with anterior open bite versus matched individuals with an adequate overbite (control group) using different measurement approaches (linear, area, and volume measures). The sample included 137 cone-beam computed tomographies (CBCTs) of young adults (74 men and 63 women) divided into two groups: 47 CBCTs of individuals (mean age 27.89) with open bite (overbite depth indicator (ODI) 56.84°±9.48° and Frankfort mandibular plane angle (FMA) 31.21°±6.44°) and 90 CBCTs of individuals (mean age 26.87) without an open bite (ODI 62.24°±9.47°, FMA 26.79°±5.81°). Two trained and calibrated orthodontists made all linear, area, and volume measurements on the CBCT records of the upper airways using Planmeca Romexis software. The Mann-Whitney U-test, chi-squared test, and multiple linear regression were applied. Significance was set at P<0.05. There were no differences in linear or volume measurements between groups, but there was a greater area in the open bite group (greater mean difference between groups 928.3 mm2) than the control group. No variable influenced nasopharyngeal airway volume, but ANB angle affected oropharyngeal airway volume (β=-623.87) and total airway volume (β=-651.48). Orthodontists should be aware that the airways diagnosis can vary depending on the measurement approach used, the volumetric method being the gold standard. The pharyngeal airway volume was similar in individuals with vs. without an open bite and is mainly influenced by ANB angle in both groups.

A study of cervical vertebra anomalies among individuals with different sagittal and vertical facial growth patterns.

Objective:The objective was to evaluate the prevalence of cervical vertebra anomalies (CVA) in individuals with different sagittal and vertical skeletal growth patterns of jaws and also to establish the associations of anomalies with the type of growth, if any.Materials and Methods:A total of 293 lateral cephalograms were evaluated for CVA. Based on the Frankfort mandibular plane angle, cephalograms were categorized into three groups: Group I, II, and III. Based on the ANB angle, cephalograms were classified into three classes, Class 1, 2, and 3. Six types of CVA such as partial cleft (PC), block fusion (BF), dehiscence (D), fusion between C2 and C3 (F23), occipitalization (OC), and spina bifida (SB) were identified on lateral cephalograms. Descriptive statistics were applied along with multinomial logistic regression analysis. P = 0.05 was considered as the level of statistical significance.Results:PC was most common in the overall samples (36%). BF was the least common (3.2%) CVA. The frequency of various CVA was comparable between males and females in all the three classes of individuals. The association of vertical growth patterns with CVA was found to be statistically nonsignificant (P > 0.05). Class 2 malocclusion was found to be statistically significantly associated with the D (P = 0.043).Conclusions:PC, fusion, and D were the most frequently found CVA, and SB was found only among the hypodivergent growth pattern individuals. The association of CVA with vertical facial growth patterns was not significant, somewhat influenced by age, sex, and sagittal skeletal malocclusions.

Distribution of Various Maxilla-Mandibular Positions and Cephalometric Comparison in Chinese Skeletal Class II Malocclusions

To obtain the distribution of different maxilla-mandibular characteristics in Chinese skeletal class II mixed dentition patients and to compare the differences of cephalometric variables among different maxilla-mandibular types. A cross-sectional study was conducted among 310 skeletal class II patients in mixed dentition. The patients were divided into 6 groups according to SNA and SNB angle of the cephalogram. A total of 38 cephalometric measurements were measured on their cephalograms. Differences among groups were tested by one-way analysis of variance. There were 34 (10.97%) patients in group I, 10 (3.23%) in group II, 4(1.29%) in group III, 69 (22.26%) in group IV, 133 (42.90%) in group V, and 60 (19.35%) in group VI. In all, 14.19% of the patients exhibited maxillary protrusion (MxP), and 62.26% exhibited mandibular retrusion (MnR) with either normal or retruded maxilla. Groups II and III were excluded for statistical comparison due to a limited sample size. Statistical differences were found in 25 cephalometric measurements among the other 4 groups. Patients with MnR (groups V and VI) exhibited bigger sella angle, gonial angle, Frankfort mandibular plane angle, and smaller mandibular body length and ramus height than patients without MnR (p value < 0.05). The most common etiology forming skeletal class II malocclusion in Chinese children was MnR, which was mainly caused by the small size and hyperdivergent growth direction of mandible. The study presents various cephalometric characteristics of Chinese skeletal class II malocclusions. The results indicated that for the early orthodontic treatment of Chinese class II children with mixed dentition, orthodontists might emphasize more importance to mandibular length augmentation and growth direction change in mandible.

Influence of the growth pattern on cortical bone thickness and mini-implant stability.

ABSTRACTIntroduction: Controversial reports suggest a relationship between growth pattern and cortical alveolar bone thickness, and its effect in the use of mini-implants. Objective: The main purpose of this study was to assess the influence of the growth pattern on the cortical alveolar bone thickness and on the stability and success rate of mini-implants. Methods: Fifty-six mini-implants were inserted in the buccal region of the maxilla of 30 patients. These patients were allocated into two groups, based on their growth pattern (horizontal group [HG] and vertical group [VG]). Cortical thickness was measured using Cone Beam Computed Tomography. Stability of mini-implants, soft tissue in the insertion site, sensitivity during loading and plaque around the mini-implants were evaluated once a month. Intergroup comparisons were performed using t tests, Mann-Whitney tests, and Fisher exact tests. Correlations were evaluated with Pearson’s correlation coefficient. Results: The cortical bone thickness was significantly greater in the HG at the maxillary labial anterior region and at the mandibular buccal posterior and labial anterior regions. There was a significant negative correlation between Frankfort-mandibular plane angle (FMA) and the labial cortical thickness of the maxilla, and with the labial and lingual cortical bone thicknesses of the mandible. No significant intergroup difference was found for mini-implant mobility and success rate. No associated factor influenced stability of the mini-implants. Conclusions: Growth pattern affects the alveolar bone cortical thickness in specific areas of the maxilla and mandible, with horizontal patients presenting greater cortical bone thickness. However, this fact may have no influence on the stability and success rate of mini-implants in the maxillary buccal posterior region.

Assessment of airway dimensions in skeletal Class I malocclusion patients with various vertical facial patterns: A cephalometric study in a sample of the Saudi population.

OBJECTIVE:To compare airway widths among skeletal Class I malocclusion patients with different vertical facial patterns.MATERIAL AND METHODS:A total of 103 lateral cephalograms of skeletal Class I patients (mean age of 20 ± 2.3 years) with no history of orthodontic treatment, trauma, facial syndromes, or nasopharyngeal dysfunction were included. Based on the Frankfort–mandibular plane angle measurements, the sample was divided into three groups: low-angle, high-angle, and normal-angle groups. Upper and lower pharyngeal airway widths were measured as described by McNamara. The analysis of variance test was performed to compare the means of groups. Pairwise comparisons were performed using Tukey's post-hoc test. Differences were considered statistically significant at P < 0.05.RESULTS:ANOVA showed a significant mean difference between the groups for both the upper and lower airway widths with P values of 0.011 and 0.003, respectively. Tukey Pairwise comparisons showed the upper airway width to be significantly narrower in the high-angle group compared to the normal-angle (P = 0.021) and low-angle groups (P = 0.013). Furthermore, the lower airway width in the high angle group was significantly narrower than the normal angle (P = 0.020) and low-angle groups (P = 0.017). There were no statistically significant differences between normal and low angle groups.CONCLUSIONS:The upper and lower pharyngeal widths in the Class I high-angle group were significantly narrower than those in the normal-angle and low-angle groups.

Cephalometric Evaluation of Vertical Dimension of Occlusion in Varying Malocclusions

Abstract Introduction The aim of modern cephalometrics is to evaluate the relationship of skeletal and dental functional units of the face and to implement treatment to establish the position of the units horizontally and vertically. Establishing a correct occlusal vertical dimension is considered one of the most important aspects of facial esthetics for patients in need of orthodontic treatment. Aim The aim of this study is to evaluate the vertical dimension of occlusion in varying dental malocclusions in Solan population. Materials and Methods The sample consisted of pretreatment lateral cephalograms of 100 patients (50 Class I and 50 Class II div 1), aged 15 to 30 years; six angular and one linear parameters were measured to determine the vertical dimension of occlusion. Results All the parameters (Frankfort-mandibular plane angle [FMA], Occl/Frankfort horizontal plane [FHA], angle of Y-axis, Occl/SN, GoGn/SN, and ANS-Me) were found to be decreased in Class I than in Class II div 1 malocclusion except (ANS-Xi-Pm). All the parameters were found to be statistically significant (p &lt; 0.05) when compared between groups. When cephalometric norms of the present study were compared with Moroccan population, all parameters (ANS-Xi-Ptm, FMA, Occl/FH, Occl/SN, GoGn/SN, and ANS-Me) were found to be decreased in Solan population except angle of Y-axis. All the parameters were clinically significant (p &lt; 0.05) except ANS-Xi-Pm and FMA that were found to be clinically nonsignificant (p &gt; 0.05). Conclusion Solan population has distinct cephalometric characteristics, which should be used as the reference in future orthodontic treatments.

Correlation Between Cephalometric and Photographic Results of Determining the Lower Anterior Facial Height

Background: Today, the most commonly used instrument for determining the inferior face height is lateral cephalometry; however, due to the fact that some lateral cephalometric radiographs are given to the patient while taking radiation, and with regard to the overlaps and distortions of structures in this radiograph. Objectives: The purpose of this study was to study the inferior height of the face based on the one-third of the face in photography and then compare its correlation with the results of cephalometry. Methods: This descriptive-analytical study was carried out with photographic and lateral cephalometric radiographs of 75 randomly selected participants (38 women and 37 men) from among patients consulting the orthodontic clinics in Bandar Abbas in 2012 - 2013. All participants had all their permanent teeth (without third molar involvement). Patients signed an informed consent form for participation. There was no history of head and face trauma, orthognathic surgery, previous orthodontic treatment, and congenital anomalies. The anterior height of the face was evaluated based on the one-third of the face on photography according to the results of FMA (Frankfort-mandibular plane angle), Sn-GoGN, Bjork, and Jarabak, and the correlations of these values with each other were determined. Data were analyzed by SPSS software using chi-square test, kappa coefficient, and Pearson coefficient. Results: No significant correlation was found between the photographic and cephalometric data of face height (r = -0.03, P &gt; 0.05). There was a significant inverse correlation between the results of FMA and Jarabak index (r = -0.6, P &lt; 0.05). There were significant direct relationships between the results of FMA and those of Bjork (r = 0.8, P &lt; 0.05) and Sn-GoGn (r = 0.7, P &lt; 0.05). There was no statistically significant relationship between the facial form and class I and II skeletal occlusions (P &gt; 0.05). There was nomeaningful relationship between the results of FMA angle and facial form in class 1 and 2 occlusion subjects (P &gt; 0.05). However, this association was found stronger in class I than in class II occlusion. Conclusions: There is no meaningful correlation between photographic and cephalometric measurements of facial height, and we always need lateral cephalometrics for the correct orthodontic treatment plan and as a golden standard. Cephalometric variables are correlated with each other for determining the vertical growth pattern, and each can be used for diagnosis alternatively.

Assessment of incisor positions in Yemeni population with different skeletal patterns

Objectives: This study aimed to determine the position of the incisors and its effects on the profile, identify any possible gender differences, and compare the maxillary and mandibular anterior teeth positions between participants of short, average, and long faces. Materials and Methods: This study comprised cephalometric radiographs of 82 participants (male: 42, female: 40) with a mean age of 21.9 ± 2.8 years. The participants were divided into three groups: short face group: Frankfort mandibular plane angle (FMA) <25°, average face group: FMA ≥25°–<30°, and long face group: FMA ≥30°. Seven linear and eight angular measurements were measured and compared between the three groups. Results: No gender differences were found. The short face participants tend to have more proclined lower incisors, more protruded chin, more mandibular incisor display, and more retrusive upper lip position than the average and long face groups. Conclusions: The short face participants tend to have more proclined lower incisor, more protruded chin, a more mandibular incisor display, and more retrusive upper lip position than the average face and long face groups.

Relationship between dentofacial morphology and mandibular movement from rest position to maximum intercuspation in Class II division 1 malocclusion patients

BACKGROUND: The objective of this study was to determine the relationship between dentofacial morphology and mandibular movement from rest position to maximum intercuspation in Class II division 1 malocclusion patients. MATERIALS AND METHODS: The sample comprised of 45 patients who were 10–14 years old and had Class II division 1 malocclusions. Eighteen cephalometric variables were evaluated to determine the dentofacial morphology using lateral cephalograms. Mandibular movements were recorded from mandibular rest position to maximum intercuspation using mandibular kinesiography. Spearman's correlation coefficient was used to analyze the relationships between mandibular movement and other dentofacial variables. RESULTS: Mandibular movement in the anteroposterior dimension was significantly negatively correlated with the curve of Spee (COS) (r = −0.45) and freeway space (r = −0.44) and positively correlated with the sella-nasion-mandibular plane (SN-MP) angle (r = 0.47) and the Frankfort-mandibular plane angle (FMA) angle (r = 0.44). Two types of mandibular movement in the anteroposterior dimension were observed. Twenty-six of 45 patients (57.8%) exhibited posterior mandibular movement from rest position to maximum intercuspation (backward group) and 19 subjects (42.2%) presented anterior movement (forward group). COS and freeway space were greater in the backward group. The SN-MP and FMA angles were higher in the forward group. CONCLUSIONS: COS, freeway space, and mandibular plane angle may relate to mandibular movement from rest position to maximum intercuspation in Class II division 1 malocclusion. Patients with deep COS combined with a large freeway space and smaller mandibular plane angle tend to present posterior mandibular movement from rest position to maximum intercuspation.

Comparative evaluation of Tweed's analyses in Class I, Class II, and Class III participants of Central India: A pilot study

Objective: Comparative evaluation of Tweed's analyses in Class I, Class II, and Class III participants of Central India in two different age groups. Materials and Methods: Sample size comprised 240 participants belonged to Central India. Participants were divided into two main groups: Group I comprised 120 young children in the age group of 12–16 years and Group II comprised 120 young adults in the age group of 18–22 years. Tweed's analysis was performed from the collected sample. Results: The lower incisor inclination (incisor-mandibular plane angle [IMPA]) in Central India participants was higher (100.13°) compared to the original Tweed norm of IMPA 90°. Statistically higher value of IMPA was found in young male children compared to young female children in Class II div 1 and Class II div 2 participants and opposite trend was seen in Class III young adults. The Frankfort-mandibular plane angle was found to be significantly more in young adult females (24.93°) than males (18.07°) in Class III participants. Angle IMPA was found to be significantly higher in Class I compared to Class III participants and significantly higher in Class III compared to Class II div 2 participants. Conclusion: The differences of Tweed's parameters in this pilot study indicate that Caucasian norms cannot be truly adhered to Central India participants during orthodontic treatment. Lower incisors were normally more proclined in Central Indian participants and their over retraction during orthodontic treatment would cause prominent chin. Proclination of lower incisor was more in young male children compared to young female children in Class II div 1 and Class II div 2 participants and opposite trend was seen in Class III young adults. Class III female adults show tendency toward vertical growth pattern compared to males. Proclination of lower incisor was found to be more in Class I compared to Class III participants and more in Class III compared to Class II div 2 participants.

Evaluation of the Relationship Between Morphology, Volume, and Density of the Mandible and Dentofacial Vertical Dimension Using Cone Beam Computed Tomography

Objective: To evaluate the relationship between mandibular shape, mandibular bone density, cortical bone thickness, and condylar volume and facial height using a cone-beam computed tomography (CBCT). Material and Methods: Fifteen female patients (16-25 years old) were included in this study. The following measurements were performed on CBCT radiographs; inter-canine and inter-molar width of the mandible at three vertical points (alveolar crest, apex and basal bone), mandibular cortical bone thickness in disto molar and canine sections, bone density of the mandibular body and condylar volume. Afterward, subjects were divided into short face, normal and long face groups according to the Frankfort-mandibular plane angle (FMA) measured on lateral cephalograms obtained from CBCTs. Data were analyzed using Pearson correlation, one-way ANOVA, and post-hoc analysis. Results: The inter-canine width of the mandible at the apical point in long face subjects was greater than in the other groups. Likewise, the cortical bone thickness was significantly higher in long face patients compared to the short face and normal subjects. There was no statistically significant difference in mandibular density or condylar volume between patients with various vertical heights (p>0.1). Conclusion: Vertical growth pattern is correlated with mandibular morphology to some extent.

Three-dimensional treatment outcomes in Class II patients with different vertical facial patterns treated with the Herbst appliance.

The aims of this study were to evaluate, using 3-dimensional superimposition techniques, the skeletal changes in Class II subjects with different vertical facial patterns treated with the Herbst appliance and to compare these skeletal changes to those of Class II controls treated with elastics. Sixteen Herbst patients who met the inclusion criteria were divided into 2 equal groups based on vertical facial pattern as determined by the Frankfort mandibular plane angle (brachyfacial,≤22°; mesofacial, 23°-29°) and had cone-beam computed tomographs taken before treatment, 8weeks after Herbst appliance removal, and after subsequent fixed appliance treatment. Eleven Class II control patients treated with fixed appliances and elastics had cone-beam computed tomographs taken before and after treatment. Three-dimensional models were generated from the cone-beam computed tomography images, registered on the anterior cranial bases, and analyzed using color maps and point-to-point measurements. There were minimal differences in treatment response between the 2 Herbst groups across all skeletal parameters measured. The Herbst subjects showed a greater inferior displacement of anterior nasal spine compared with the Class II controls (Herbst brachyfacial, -1.44mm; Herbst mesofacial, -1.95mm) with other maxillary changes being clinically insignificant. The Herbst subjects showed greater inferior displacement of B-point compared with the Class II controls (Herbst brachyfacial, -2.59mm; Herbst mesofacial, -2.75mm). There were no statistically significant differences in mean linear mandibular measurements. All groups showed a trend toward posterior displacement of the condyles and glenoid fossae from the start to the end of treatment, with no significant differences across the 3 groups. There were minimal differences in the changes in gonial angle and Frankfort mandibular plane angle across all groups. Approximately 2years after Herbst treatment, the Herbst subjects with different vertical facial patterns showed similar patterns of skeletal change compared with the Class II controls treated with elastics.

Assessment of hyoid bone position among different skeletal patterns

PurposeTo determine the hyoid bone position in subjects with various skeletal patterns. Materials and methodsConventional pre-treatment lateral cephalograms of 100 subjects aged 18–25 years were selected from the files of orthodontic patients based on anteroposterior skeletal pattern and facial divergence pattern. Subjects with Class I skeletal pattern (ANB 1–4°) were categorized into group A and group B depending on the measurements of Frankfort Mandibular Plane Angle (FMA) of 22–30° (normo divergence) and greater than 30° (hyper divergence) respectively. Likewise subjects with Class II skeletal pattern (ANB >4°) were categorized into group C and D, based on the above same divergence. The angular and linear measurements were recorded and measured. Statistical assessments include unpaired Student t-test and one-way analysis of variance (ANOVA). ResultsThe vertical position of hyoid bone was not affected by nature of horizontal or vertical growth pattern of the face. The mean anteroposterior position of the hyoid bone among the 4 groups of subjects was statistically significant (p<0.05). The position of hyoid bone in group D was significantly backward compared with the subjects in group A (p<0.05) or group C (p<0.05). The mean hyoid axis angle among subjects in the hyper divergent group (group B and group D) was high but insignificant. ConclusionThe position of hyoid bone was most posterior in subjects with skeletal Class II malocclusion associated with mandibular retrognathism.

Cephalometric Profile of Bangladeshis: Tweed’s Analysis

Introduction Tweed’s diagnostic triangle is simple yet provides a definite guideline in treatment planning. The aim of the present study was to establish the Tweed’s norms for Bangladeshi people. Methods The study was conducted for 89 Bangladeshi young adults (45 males and 44 females), aged 19–27 years, having balanced and harmonious facial profiles. Lateral cephalograms taken of these subjects were used for a series of morphometric analyses. Results All three angular parameters Frankfort-mandibular plane angle (FMA), Frankfort-mandibular incisal angle (FMIA), incise mandibular plane angle (IMPA)were measured and found to be 24.52°, 54.60°, and 100.88°, respectively. The mean FMA has been found to be 24.52° (with a range of 14°–36°) which is quite close to Tweed’s norm and found to be statistically insignificant. However, IMPA and FMIA values of Bangladeshis found to be statistically significantly different from that of the Caucasians. The linear regression equation of IMPA on FMA was fitted, and the estimated value of IMPA was computed for a given FMA. Conclusion The results support the idea that treatment objectives of IMPA should be considered according to the facial pattern, i.e., FMA. Ethnic variations of norms cannot be overlooked while outlining goals and planning the treatment.

Residents’ journal review

Residents’ journal review