Frankfort Mandibular Plane Angle Research Articles

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.

Risk factors for noncarious cervical lesions: A case-control study.

Noncarious cervical lesions (NCCLs) are multifactorial and can be caused by the anatomical structure of the teeth, erosion, abrasion and abnormal occlusion. The aim of this case-control study was to explore the risk factors for NCCLs. Cone-beam computed tomography was used to determine whether a wedge-shaped defect existed at the cementoenamel junction. We compared 63 participants with NCCLs with 63 controls without NCCLs, matched for sex, age (±1 year) and toothbrushing-related factors (e.g., type of bristle and brushing patterns, frequency and strength). All participants were asked to complete a questionnaire about self-administered daily diet habits and health condition. Univariate and multivariate logistic regression analyses were conducted to determine the risk factors for NCCLs. Significant variables in the univariate analysis (i.e., p < .2) included frequency of carbonated beverage consumption, sella-nasion-point B angle (SNB) and Frankfort-mandibular plane angle (FMA). Multivariate logistic regression demonstrated that the consumption frequency of carbonated beverages (odds ratio [OR] = 3.147; 95% confidence interval [CI], 1.039-9.532), FMA (OR = 1.100; 95% CI, 1.004-1.204) and SNB (OR = 0.896; 95% CI, 0.813-0.988) was independent influencing factors. The area under the receiver operating characteristic curve (AUC) value of regression Model 1 (established with the frequency of carbonated beverage consumption, FMA, SNB and sleep bruxism) was 0.700 (95% CI, 0.607-0.792; p < .001), and that of regression Model 2 (established using the frequency of carbonated beverage consumption, FMA and SNB) was 0.704 (95% CI, 0.612-0.796; p < .001). The consumption frequency of carbonated beverages and FMA was risk factors for NCCLs; the higher the frequency of carbonated beverage consumption and FMA, the higher was the probability of NCCLs. SNB was a protective factor for NCCL occurrence; the larger the SNB, the lower was the probability of NCCL occurrence. These findings have further clarified the aetiology of NCCLs and provided clinicians with valuable insights into strategies for preventing the loss of dental tissue.

Three-dimensional assessment of condylar morphology, position, and joint spaces in different jaw base divergences: A cone-beam computed tomography study

Objectives: The mandibular condyle being part of the temporomandibular joint complex, its volume, and shape play a pivotal role in treatment stability and outcomes in orthodontic and orthognathic patients over the long term. Different loading patterns would result in different morphology of the TMJ. The association with different facial types and understanding of the relationship between condylar morphology and jaw base divergence is limited. The objective of this study was to assess the condylar morphology, which includes condylar height, length, width, axis angulation, joint spaces, height of the fossa, and volume in different jaw base divergences. Material and Methods: A cross-sectional study was conducted in which 90 patients undergoing orthodontic treatment were selected and allocated into three groups of 30 each, namely, hypodivergent, normodivergent, and hyperdivergent based on Frankfort mandibular plane angle. Patients satisfying the inclusion criteria were subjected to lateral cephalogram and cone-beam computed tomography under standard resolution and field of view of 8 × 8 cm2 with the teeth in maximum intercuspation. On the obtained digital imaging and communications in medicine image, ten anatomical landmarks were marked and analyzed using Carestream imaging software. The condylar volume was assessed using three-dimensional Slicer software. Results were statistically analysed using analysis of variance and post hoc Bonferroni test. Results: The average values of the condylar width and volume showed statistically significant values in the hypodivergent whereas axis angulation and superior joint spaces in the hyperdivergent groups, respectively. Conclusion: Hypodivergent individuals have condyles that are larger in size and volume, whereas hyperdivergent individuals have larger axis angulation and more superiorly positioned condyles.

Three-Dimensional Evaluation of Treatment Effects and Post-Treatment Stability of Maxillary Molar Intrusion Using Temporary Anchorage Devices in Open Bite Malocclusion.

Background: We investigated treatment outcomes and post-treatment stability in 10 patients with an anterior open bite and nonsurgical orthodontics. Methods: The patients underwent maxillary molar intrusion using temporary anchorage devices (TADs) to deepen the overbite due to mandibular autorotation. Lateral cephalograms and dental cast models were obtained before treatment (T0), immediately after it (T1), and >1 year after it (T2). Skeletal and dental cephalometric changes and three-dimensional movements of the maxillary dentitions were evaluated. Results: At T0, cephalometric analysis indicated that patients had skeletal class I with tendencies for a class II jaw relationship and a skeletal open bite. During active treatment (T0 to T1), the maxillary first molar intruded by 1.6 mm, the mandibular first molar extruded by 0.3 mm, the Frankfort-mandibular plane angle decreased by 1.1°, and the overbite increased by 4.1 mm. Statistically significant changes were observed in the amount of vertical movement of the maxillary first molar, Frankfort-mandibular plane angle, and overbite. Three-dimensional (3D) dental cast analysis revealed that the maxillary first and second molars intruded, whereas the anterior teeth extruded, with the second premolar as an infection point. In addition, the maxillary molar was tipped distally by 2.9° and rotated distally by 0.91°. Statistically significant changes were observed in the amount of vertical movement of the central incisor, lateral incisor, canine and first molar, and molar angulation. From T1 to T2, no significant changes in cephalometric measurements or the 3D position of the maxillary dentition were observed. The maxillary and mandibular dentitions did not significantly change during post-treatment follow-up. Conclusions: Maxillary molar intrusion using mini-screws is an effective treatment for open bite correction, with the achieved occlusion demonstrating 3D stability at least 1 year after treatment.

Factors influencing root resorption in retained mandibular second deciduous molars with congenital absence of second premolars: a cross-sectional study

BackgroundThere are currently no studies that quantitatively compare the relationship of root resorption to the patient’s systemic history or craniofacial and intraoral morphology, especially in relation to possible host factors. Thus, this study aimed to clarify the factors associated with root resorption in retained mandibular second deciduous molars with the congenital absence of second premolars and predict the prognosis of retained mandibular second deciduous molars.MethodsA cohort of 5547 patients who visited the orthodontic clinic at Tokyo Medical and Dental University Dental Hospital between 2013 and 2022 was screened. Lateral cephalometric radiographs, panoramic radiographs, upper and lower dental models, and orthodontic treatment questionnaires were used as reference materials to apply the inclusion and exclusion criteria. Ultimately, 111 patients were included in the analyses. The patients were divided into two groups based on the root resorption levels of the retained mandibular second deciduous molars. Those with less root resorption were classified under the good condition (GC) group, whereas those with more root resorption were classified under the poor condition (PC) group. Demographic, clinical, and cephalometric parameters were compared between the groups. A multivariate logistic regression model was used to predict the probability of root resorption.ResultsThe prevalence of congenitally missing mandibular second premolars with persistent mandibular second deciduous molars was 2.0%. In a total of 111 patients, eighty-three teeth (53.2%) were classified into the GC group, whereas 73 teeth (46.8%) were classified into the PC group. The Frankfort-mandibular plane angle (FMA) [odds ratio (OR): 0.87], Frankfort-mandibular incisor angle (FMIA) (OR: 0.93), overbite (OR: 1.38), adjacent interdental space (OR: 1.46), distance from occlusal plane (OR: 0.80), and caries treatment (OR: 7.05) were significantly associated with the root resorption of the retained mandibular second deciduous molars.ConclusionsOur findings suggest that skeletal morphology, oral morphological patterns, and history contribute to root resorption in retained mandibular second deciduous teeth with congenital absence of subsequent permanent teeth.

Comparative Assessment of Various Cephalometric Parameters Used for Determining Vertical Skeletal Dysplasia.

The aim of the study is to assess and correlate the different cephalometric parameters used to determine the vertical jaw relationship. Cephalometric radiographs from 148 patients were assessed and comparison was made using all eight parameters. Statistical analysis was performed using mean, standard deviation and coefficient of variance. A correlation was found between different variables using the Pearson's correlation coefficient. In the entire sample, the basal plane angle displayed the most variable distribution, while the R angle displayed the most homogeneous distribution. There was a significant correlation found between the Jarabak ratio, Steiner's mandibular plane angle (SN-GoGn), Frankfort mandibular plane angle (FMA), R angle, and DR angle. There was a moderate to weak correlation between the Y-axis, basal plane angle, and facial height ratio with other skeletal analyses. Among angular variables DR angle, R angle, SN-GoGn and FMA can be used and among linear variables Jarabak ratio could be used reliably to assess the growth pattern. It suggested that in order to obtain an accurate evaluation of the vertical jaw relationship, a variety of measurements should be combined.

An evaluation of cephalometric predictors of anterior open bite; An assessment of dental and skeletal parameters in an orthodontic population.

Anterior open bite (AOB) malocclusion is one of the highly challenging malocclusions. Cephalometric radiographs have been used for the diagnosis of occlusal anomalies in the vertical and anteroposterior directions. This study aims to compare skeletal and dental features in open and non-open bite subjects to identify factors that help predict and categorize open bites in a Nigerian population. Pretreatment cephalometric radiographs of 82 patients were recruited into this study. This study comprised 41 AOB patients and 41 (Class 1 malocclusion) patients (control group). The radiographs were obtained from the orthodontic unit, Department of Child Dental Health of the Lagos University Teaching Hospital, Idi-Araba Lagos. Cephalometric tracing and analysis of the obtained radiographs were used to identify and compare the skeletal and dental differences between the two groups. The mean age of the participants was 20.47 ± 8.05 years. The patients consisted of 26 (31.7%) males and 56 (68.3%) females. There was a significant difference in the open bite depth indicator (ODI) of the open bite (P value < 0.001). There was a statistically significant increase in the vertical skeletal parameters - lower facial height (LFH), total facial height (TFH), posterior facial height (PFH), Frankfort-mandibular plane angle (FMA), mandibular-maxillary angle (MMA), and gonial angle in the AOB group compared to the control group. The vertical height of the dentoalveolar segments measured was all significantly increased in the open bite group compared to the control group. The results suggest that the skeletal and dental vertical parameters, including ODI of the open bite subjects, varied compared with the non-open bite subjects in the Nigerian population studied and could be used to predict AOB tendency.

3D analysis of condylar and mandibular remodeling one year after intra-oral ramus vertical lengthening osteotomy.

Among the existing techniques for the correction of mandibular posterior vertical insufficiency (PVI), the intra-oral ramus vertical lengthening osteotomy (IORVLO) can be proposed as it allows simultaneous correction of mandibular height and retrusion. This study assessed the 3D morpho-anatomical changes of the ramus-condyle unit and occlusal stability after IORVLO. This retrospective analysis compared immediate and 1-year post-operative 3D CBCT reconstructions. The analysis focused on the condylar height (primary endpoint) and on the changes in condylar (condylar diameter, condylar axis angle) and mandibular (ramus height, Frankfort-mandibular plane angle, gonion position, intergonial distance, angular remodeling) parameters. Additionally, this analysis investigated the maxillary markers and occlusal stability. On the 38 condyles studied in 21 included patients (mean age 23.7 ± 3.9years), a condylar height (CH) loss of 0.66mm (p < 0,03) was observed, with no correlation with the degree of ramus lengthening (mean 13.3 ± 0.76mm). Only one patient presented an occlusal relapse of Class II, but a 3.4mm (28%) condylar diameter loss and a 33% condylar volume reduction with loss of 1mm and 3.4mm in CH and condyle diameter, respectively. A mean 3.56mm (p < 0.001) decrease in ramus height was noted, mainly due to bone resorption in the mandibular angles. This study confirms the overall stability obtained with IORVLO for the correction of PVI. This study aims to precise indication of IORVLO, and to validate the clinical and anatomical stability of results.

Skeletal, Dental and Soft Tissue Effects of Twin Block Appliance in Different Facial Divergence Cases

IntroductionClass II malocclusions refer to a discrepancy in the sagittal plane associated with either backward or upward rotation of the jaw. A backwardly positioned mandible is usually managed using a Twin block appliance which contains a bite plane to direct the occlusal forces in a more favorable direction. Our aim was to evaluate skeletal, dental, and soft tissue changes using twin-block appliance therapy in different facial divergence patients. MethodsA cephalometric study was conducted among two groups with 15 patients in each group. Group 1 have a Frankfort Mandibular plane Angle (FMA) of 18-25 degree while Group 2 have an FMA of 28 to 33 degree with Class II Division I malocclusion. All of them were treated with twin block appliances with modifications done according to FMA. Cephalometric analysis was done using Dolphin software (Dolphin Imaging 11.95) to evaluate skeletal, dental, and soft tissue changes after twin block therapy. ResultsAnalysis of variance and paired t-test were used to evaluate pre and post-treatment changes in cephalograms. The position of the mandible, maxillomandibular relation, and mandibular length was changed by 3.99 degrees, 5.23 degrees, and 4.04mm respectively in horizontal growers, while by 2.9 degrees, 1.74 degrees, and 1.07mm respectively in vertical growers. An increment in FMA by 4.59 degrees in horizontal growers with good vertical control and a little increment in FMA by 1.07 degrees in vertical growers were seen. Conclusions The twin block appliance is effective in skeletal, dental, and soft tissue correction in patients with different facial divergences.

HYOID BONE POSITION AND PHARYNGEAL SPACE IN DIFFERENT VERTICAL JAW DYSPLASIAS

Background: The position of hyoid bone and pharyngeal space is affected by various factors. One of the factors is vertical malocclusion. This study aimed to evaluate the position of hyoid bone and pharyngeal space in different vertical jaw dysplasias. Methods: In total 102 lateral cephalograms of 70 females and 32 males in the age range of 15 to 25 years were selected from records of the patients who visited to the Department of Orthodontics and Dentofacial Orthopedics, UCMS College of Dental Surgery Bhairahawa, Nepal. For the vertical plane of the face, sample was divided into three groups based on Frankfort mandibular plane angle: Group 1 (n=34; normal growth pattern) group 2 (n=34; horizontal growth pattern) and group 3 (n =34; Vertical Growth Pattern). Results: The anteroposterior position of the hyoid bone was found significantly forward in horizontal grower compared with normal and vertical grower (p&lt;0.05). There was no statistically significant difference in vertical positioning of the hyoid bone among the patients with different growth patterns. There was no statistically significant difference in the axial orientation of the hyoid bone in patients with different growth patterns. Upper pharyngeal space was significantly different in different facial skeletal patterns (p=0.019) whereas, lower pharyngeal space had no significant association. Conclusions: The position of the hyoid bone in horizontal growth pattern group was more anterior than the vertical growth pattern group. The upper pharyngeal space was found narrower in vertical growth pattern than horizontal and normal growth patterns.

Association between the occurrence of buccally displaced canine and palatal and craniofacial morphology in adolescents.

The main objective of the present research study is to evaluate the association between the occurrence of buccally displaced canine (BDC) and the palatal as well as the craniofacial morphology in adolescents in accordance at the early permanent dentition. As the experimental group, 100 adolescents of Chinese ethnicity (mean age 13.05 years) with crowding and buccally displaced canine (BDC-c) were selected in comparison with the same number of candidates (mean age 12.59 years) without BDC and crowding as control group. Digital dental casts and cephalograms were collected for three dimensional (3D) and cephalometric measurements. An independent sample T-test was used to compare the cephalometric values between the two groups. Logistic regression as commonly statistical methods used in empirical study including categorical dependent variables was used to identify the joint effects of the dental variables' 3D measurements. When comparing the groups with above analysis, patients with BDC showed a statistically significant narrower and higher palatal vault. For the cephalometric variables, the anterior cranial base length, sagittal position of the maxilla (SNA), sagittal position of the mandible (SNB), and skeletal relationship between maxilla and mandible (ANB) appeared to be smaller, whilst palatal plane angle (SN-PP), Frankfort-mandibular plane angle (FMA), anterior facial height, and lower facial height were larger in BDC-c control group (p < 0.05). A smaller inter-first premolar width was significant in the prediction model (p = 0.002). This study highlights that BDC-c participants in early permanent dentition exhibited a narrower dental arch and higher palatal vault, of which a smaller inter-first premolar width would significantly increase the occurrence of BDC.

Facial Soft Tissue Characteristics Among Sagittal and Vertical Skeletal Patterns: A Cone-Beam Computed Tomography Study.

Background Facial esthetics depend on the skeletal and dental structures underlying variable facial soft tissue thickness. In this social context, determining the relationship between external soft tissue and underlying skeletal and dental hard tissue is essential for detailed orthodontic diagnosis and treatment planning. Objective This study aims to measure facial soft tissue thickness in different sagittal and vertical skeletal patterns. Methodology This is an observational study utilizing pre-existing cone-beam computed tomography (CBCT) images of 170 subjects (110 females and 60 males) with a mean age group of 37.45 ± 13.83 years. CBCT images were then classified sagittally based on the point A-Nasion-point B (ANB) angle from Steiner's analysis into skeletal Class I, Class II, and Class III. Furthermore, vertical patterns were grouped based on the Frankfort-mandibular plane angle (FMA) from Tweed's analysis into hyperdivergent, hypodivergent, and normodivergent facial types. One-way ANOVA was used to compare the means of facial soft tissue thickness between the skeletal groups, followed by Tukey's post-hoc test for individual comparison. Multinomial logistic regression analysis was used to test the association between gender, age, and skeletal groups. The significance level was 0.05. Results One-way ANOVA revealed statistically significant differences in both sagittal and vertical groups (p≤0.05).Tukey's post hoc analysis showed that the skeletal Class III group has increased soft tissue thickness in the subnasale, upper lip, and mention compared to Class I and Class II subjects. Moreover, the hypodivergent group demonstrated increased soft tissue thickness in gnathion and mentioned landmarks in relation to the other groups. Multinomial logistic regression analysis showed significant differences between groups according to both gender and sagittal skeleton patterns (p≤0.05), with males less likely to be in Class II. Conclusions Skeletal Class III and hypodivergent groups have thicker soft tissue in specific facial landmarks. Sexual dimorphism was marked in soft tissue measurements.

Association between the Temporomandibular Joint Morphology and Chewing Pattern.

This study aimed to investigate whether the morphology of the temporomandibular joint (TMJ) is associated with chewing patterns while considering skeletal morphology, sex, age, and symptoms of temporomandibular disorder (TMD). A cross-sectional observational study of 102 TMJs of 80 patients (age 16-40 years) was performed using pretreatment records of cone-beam computed tomography imaging of the TMJ, mandibular kinesiographic records of gum chewing, lateral and posteroanterior cephalometric radiographs, patient history, and pretreatment questionnaires. To select appropriate TMJ measurements, linear regression analyses were performed using TMJ measurements as dependent variables and chewing patterns as the independent variable with adjustment for other covariates, including Nasion-B plane (SNB) angle, Frankfort-mandibular plane angle (FMA), amount of lateral mandibular shift, sex, age, and symptoms of TMD. In multiple linear regression models adjusted for other covariates, the length of the horizontal short axis of the condyle and radius of the condyle at 135° from the medial pole were significantly (p < 0.05) associated with the chewing patterns in the frontal plane on the working side. "Non-bilateral grinding" displayed a more rounded shape of the mandibular condyle. Conversely, "bilateral grinding" exhibited a flatter shape in the anteroposterior aspect. These findings suggest that the mandibular condyle morphology might be related to skeletal and masticatory function, including chewing patterns.

Corrective orthodontic treatment of high Frankfort mandibular plane angle with maxillary expansion and four premolar extractions with presence of external apical root resorption during treatment

This case report describes the orthodontic treatment performed on a 10-year-old female patient in mixed dentition stage who presented with maxillary constriction that was associated with Angle Class III malocclusion, severe crowding, and high mandibular plane angle. She had the main complaint of an unaesthetic smile. The rapid maxillary expansion approach was chosen, followed by four first premolars extraction with fixed appliance. Two mandibular miniscrews were used for anchorage control and 0.018 × 0.025-in beta titanium advance archwire were used to increase labial tipping of the maxillary incisors. After 3 years, favorable results were achieved for the occlusion, dental aesthetics, and facial profile. External apical root resorption was noted in the maxillary incisors. The patient's self-esteem improved. Treatment results were stable after 1-year follow-up.

Three-dimensional evaluation of the pharyngeal airway space in patients with anterior open bite.

: This study aimed to three-dimensionally evaluate the pharyngeal airway space (PAS) of patients with anterior open bite (AOB) by using cone-beam computed tomography (CBCT) and compare the findings with those obtained in individuals with normal occlusion. : The open bite group (OBG, n = 25) consisted of patients with an anterior overbite of -3 mm or less, while the control group (n = 25) consisted of age- and sex-matched individuals with an anterior overbite of 1-3 mm, Angle Class I malocclusion (1° ≤ point A-nasion-point B angle ≤ 4°), and a normodivergent profile (22° ≤ Frankfort mandibular plane angle ≤ 28°). After the CBCT data were reconstructed into a three-dimensional image, the PAS was segmented into four parts, and the volume of each part was measured. Pharyngeal airway length (PAL) and the area and transverse width of the part showing minimal constriction were also measured. Pearson's correlation analysis was used to evaluate the correlation between changes in the PAS and the amount of anterior overbite. : The OBG showed a significantly narrower airway space in the nasopharyngeal, hypopharyngeal, and total airway volumes. The OBG also showed a significantly smaller area and transverse width of the part with minimal constriction. The OBG showed a significantly longer PAL, but there was no correlation between the amount of anterior overbite and the changes in PAS. : The PAS was associated with AOB. Patients with AOB had a narrower PAS and a smaller part showing minimal constriction.

Orthodontic Treatment Does Not Affect Frontal Sinus Development in Female Adults: A Clinical Study.

Frontal sinus growth is gradual and lasts until post-puberty. However, the influence of biomechanical stimuli, such as orthodontic treatment, on frontal sinus development after the growth period has ended remains unclear. This study was designed to elucidate the impact of orthodontic treatment on the frontal sinus morphology of adult females. Sixty women were included and divided into three groups, based on the Frankfort mandibular plane angle. All participants underwent computed tomography and lateral cephalometry before and after treatment. Although two participants exhibited frontal sinus agenesis, most exhibited a bilaterally symmetric frontal sinus without fusion. The frontal sinus width and height were almost similar, irrespective of the vertical skeletal pattern, where the frontal sinus depth was significantly larger in the average mandibular plane angle group than in the low- and high-angle groups. Furthermore, the sinus volume in the low-angle group was likely smaller than that in the average and high-angle groups. On comparing pre-treatment and post-treatment measurements, minimal or no changes to the frontal sinus dimension were detected after treatment. In conclusion, orthodontic treatment did not affect frontal sinus development after the end of growth.

Investigation of the change in the degree of Frankfort mandibular plane angle after levelling the curve of spee in different malocclusion groups.

The curve of Spee is a naturally occurring phenomenon in the human dentition. Leveling the curve of Spee can affect the Frankfort-mandibular plane (FMP) Angle and thus the lower anterior facial height. This study examined the degree of change in FMP angle after leveling the curve of Spee in different malocclusion groups. In this study, 75 patients who were aged >14 years and had undergone fixed appliance therapy using a 0.022-slot MBT bracket system were included. The pre- and post-treatment casts and lateral cephalograms of the patients were divided into three groups, namely Class I, II, and III malocclusions, with 25 patients in each group. The curve of Spee and FMP angle were measured before and after orthodontic treatment, and their correlation was evaluated. After leveling the curve of Spee, the FMP angle decreased in Class I and II groups and increased in Class III group. These results were statistically significant except in Class I malocclusion group. A mild positive correlation was observed between the curve of Spee and FMP angle in Class I and III malocclusion groups and a negative correlation in Class II malocclusion group. The change in FMP angle, following the leveling of the curve of Spee, in Class II and III malocclusion group, is attributed to alterations in lower anterior facial height. The study observed a mild positive correlation between the curve of Spee and FMP angle in Class I and III malocclusion groups and a negative correlation in Class II malocclusion group.

Influence of mandibular incisor agenesis and growth pattern on symphysis characteristics: A retrospective cephalometric study.

This study was performed to investigate the effects of mandibular incisor (MnI) agenesis and divergent malocclusion type on mandibular symphysis inclination and morphology. A total of 162 selected patients were divided into two groups: one group consisted of patients with one or two congenitally missing MnIs, and another group comprised patients without tooth agenesis. Patients in each group were categorized into three divergent malocclusion groups (hypodivergent, normodivergent and hyperdivergent) according to the Frankfort mandibular plane angle, with 27 patients per group. Lateral cephalograms were used to evaluate mandibular symphysis inclination and morphology. Two-way analysis of variance, simple main effect analysis and Tukey's test were used for statistical comparisons. The agenesis group demonstrated a significantly greater retroclination of the mandibular symphysis than the non-agenesis group in the normodivergent group. In the hypodivergent and normodivergent groups, the agenesis group showed a significantly smaller area of the alveolar bone with thinner width and shorter height than the non-agenesis group. For the Japanese orthodontic patients, MnI agenesis caused a significantly great retroclination of the mandibular symphysis in patients with normodivergent malocclusion and significantly small area of the alveolar bone with thin width and short height in patients with hypo- and normodivergent malocclusions.

Occlusal Plane Changes after Maxillary Molar Distalization Using Temporary Skeletal Anchorages Devices: A Narrative Review and Preliminary Study

Background: We conducted a narrative review of studies analyzing the occlusal and mandibular plane angles after maxillary molar distalization using temporary skeletal anchorage devices (TADs). An original preliminary investigation was conducted on the occlusal and mandibular plane angle changes according to the design of TAD-supported distalization. Methods: We included 51 participants stratified into three groups (buccal TAD, lingual arch TAD, and pendulum TAD) who underwent lateral cephalography before and after treatment. The paired t-test and ANOVA were used to analyze the significant differences among the groups. Results: The pterygoid vertical to maxillary second molar (p &lt; 0.01) significantly differed before and after treatment within each group (group 1, 1.29 ± 1.73 mm; group 2, 2.01 ± 1.46 mm; group 3, 1.12 ± 1.43 mm). The angle between the Frankfort horizontal and anatomical occlusal plane increased by 1.96 ± 2.88° (p &lt; 0.05) and 2.51 ± 2.57° (p &lt; 0.01) in groups 2 and 3, respectively. Conclusions: The measured variables did not significantly differ among the three groups. The Frankfort-mandibular plane angle and functional occlusal plane did not change after maxillary molar distalization. The anatomical occlusal plane is influenced by the anterior teeth and may be unrelated to maxillary molar distalization. Further studies are required to verify the exact relationship between maxillary molar distalization and occlusal plane angle.

Vertical Skeletal Changes after Extraction and Nonextraction Orthodontic Treatment.

Due to the constant battle regarding the controversial topic of orthodontic extraction, this study aims to assess the changes in vertical dimensions of patients treated with premolar extractions compared with nonextraction orthodontic patients. A sample of 60 borderline patients were recruited and divided into extraction and nonextraction groups. Eleven pretreatment cephalometric measurements were recorded using WebCeph and patients were followed-up until the completion of treatment. Intragroup and intergroup comparisons were made using paired t-test and two-sample independent t-test, respectively. The joint significance of differences was measured using F-tests. The intragroup comparison revealed that in the extraction group, the vertical dimension was significantly increased posttreatment for four cephalometric measurements, that is, mandibular plane angle (p < 0.05), palatal plane angle (p < 0.05), Frankfort mandibular plane angle (p < 0.05), and y-axis (p < 0.05). In the comparison of the posttreatment values of both groups, the mean differences of the posttreatment values for sella nasion (SN)-gonion (Go)-gnathion (Gn) angle (p = 0.008), the total anterior (p = 0.050), and lower anterior facial heights (AFH; p = 0.011) were significantly higher. At the same time, the Jarabak ratio was significantly (p = 0.006) lower in the extraction group than in the nonextraction group. The increase in vertical dimension is significantly higher in the extraction group than in the nonextraction group which indicates a significant impact of orthodontic extraction on the vertical dimensions.