Hyperdivergent Groups Research Articles

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.

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.

Comparative Study on the Impact of Vertical Growth on dental and Soft Tissue Profile

Aim: This study aimed to compare facial groups based on their vertical skeletal characteristics (hypodivergent, normodivergent, and hyperdivergent) and their associated soft tissue features, focusing on the lips and chin. Materials and Methods: A total of 103 lateral cephalometric x-rays were obtained from patients sought orthodontic treatment. The samples were categorized into hypodivergent (Md/Mx &lt;20°), normodivergent (Md/Mx between &gt;20° and 28°), and hyperdivergent (Md/Mx &gt;28°) facial types. Results: In Class I group, normodivergent facial type was the most prevalent (55.2%), while hyperdivergent pattern dominated in Class II (54.5%) and Class III (40%) groups. The hypodivergent group exhibited the highest mean thickness for upper and lower lips (8.95 mm and 9.35 mm, respectively). Hyperdivergent individuals had the greatest mean upper lip height (11.3 mm), whereas hypodivergent individuals had the highest mean lower lip height (25.32 mm). Procumbency of upper (PUL) and lower lips (PLL) was most prominent in the hypodivergent group (2.08 mm and 0.87 mm, respectively). Hyperdivergent individuals showed the maximum mean chin thickness (7.84 mm). Statistically significant differences were observed only between Hypo vs Normo-divergent groups in upper lip thickness (ULT), and in PUL and PLL between Hypo vs Normodivergent and Hypo vs Hyperdivergent groups. Conclusion: The study concluded that a correlation between the hard tissue (bones and teeth) and soft tissue (facial features) topography were found in Sudanese subjects. There was a significant correlation between the soft tissue variables including nasolabial angle, upper lip thickness, and length in the three different skeletal vertical dimensions, but this correlation was observed only in the lower jaw. Individuals with hypodivergent facial patterns tend to have greater thickness in the upper and lower lips, lower lip height, compared to normodivergent and hyperdivergent counterparts.

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.

Prevalence of Ectopic Canine in Different Sagittal and Vertical Skeletal Patterns.

The present investigation aims to find out the prevalence of ectopic canines among skeletal class I, II, and III malocclusions and to evaluate its variability among different genders and their growth patterns. The study sample included orthopantomograms (OPGs), lateral skull views, and study models of 999 patients collected from departmental archives. Among the selected samples, 258 were males and 738 were females. They were divided into skeletal class I, II, and III malocclusions sagittally and hypodivergent, normodivergent, and hyperdivergent groups according to their angle formed between point A-Nasion - point B (ANB) and angle formed between the Sella-Nasion (SN) plane and Gonion (Go) - Gnathion (Gn) plane (SnGoGn) values respectively. Of the 999 samples, 738 (73.9%) were female and 260 (25.8%) were male patients. When compared to men, females had a higher proportion of ectopic canines. An estimated 62.3% of skeletal class I, 29.1% of skeletal class II, and 8.6% of skeletal class III cases were found to have ectopic canines. An estimated 720 (72.1%) patients were found to have maxillary ectopic canines and out of the available sample, 474 patients have horizontal growth patterns, 335 have average growth patterns and 190 patients have vertical growth patterns. Labial impaction was the commonest (65.4%) followed by palatal (24.8%). Bilateral impaction was comparatively more (51.1%) than unilateral impaction (48.2%). Maxilla was more prevalent (72.1%) as compared to the mandible (16.3%) and for both the arches it was (11.6%). Ectopic canines were identified in a total of 62.3% of cases with skeletal class I, 29.1% of cases with skeletal class II, and 8.6% of cases with skeletal class III. The bilateral ectopic canine was mostly seen in skeletal class I and class III malocclusions, whereas, a unilateral presentation was mostly seen in skeletal class II malocclusions. Knowing the likelihood of a maxillary canine erupting ectopically will aid clinicians in starting with interceptive therapy since this condition necessitates complex orthodontic mechanics.

Comparative Evaluation of Cranial Base Length and Flexure on Facial Parameters in Hypodivergent, Normodivergent and Hyperdivergent Patients: A Retrospective Cephalometric Study.

The aim of the study was to assess the influence of cranial base length (CBL) and Flexure on facial parameters in Hypodivergent, Normodivergent, and Hyperdivergent patients. Around 60 standardized cephalograms were divided into Hypodivergent, Normodivergent, and Hyperdivergent groups (20 each) based on the FMA angle. The CBL, cranial flexure (CF), and various facial parameters were measured for each case. The results were analyzed for the correlation between Cranial and facial parameters in each of the three study groups. Comparison and Pairwise Comparison of variables between study groups were done using ANOVA and Tukey's post hoc Test. Cranial base length, mandibular body length, LAFH, N-Me-Go angle (p-value <0.001), and Jarabak's ratio were found to be significantly different between the groups. Pearson's Correlation showed that most of the facial parameters had a significant correlation with CBL in Hypodivergent groups. The CBL is more closely related to facial parameters in vertical dysplasia individuals than CF. The CBL is positively correlated to facial variables, especially in Hypodivergent individuals. The N-Me-Go Angle introduced in the study was significantly different in all three vertical facial types studied; hence, it cannot be used as a valuable diagnostic tool. Changes in the length and flexure of the cranial base influence the anteroposterior position of jaw bases. The influence of the cranial base on the development of vertical dysplasias is not studied much, hence the present study aims at resolving this lacuna in literature.

Quantitative analysis of the morphology of the lips according to different anteroposterior and vertical skeletal patterns

Objectives: The aim of this study was to compare the differences in the morphology of the lips according to anteroposte-rior dentoskeletal patterns and facial divergence.Materials and Methods: The samples were composed of the frontal facial photographs of 117 adult patients who satisfied all the cephalometric measurements for six groups (Class I or II or III and normodivergent or hyperdivergent). The morphol-ogy of the lips was evaluated on the frontal facial photographs and the measurements were compared between the groups.Results: In the normodivergent groups, the height-to-width ratio of the lip vermilion was significantly greater in the Class II group than in the Class I group, and the labrale superius angle and upper lip convexity of the Class II group was smaller than that of the Class I group. In the hyperdivergent groups, the stomion inferius angle of the Class III group was smaller than that of the Class II group. Lower facial height and the interlabial gap in the hyperdivergent groups tended to be larger than those in the normodivergent groups. The height-to-width ratio of the lip vermilion and the commissure height were larger in the hyperdivergent groups than in the normodivergent groups. However, the upper lip height and philtrum height did not differ between the hyperdivergent and normodivergent groups.Conclusion: The morphological characteristics of the lip vermilions on the frontal view differed according to the sagittal dentoskeletal relationship and facial divergence.

Three-dimensional radiographic assessment of the mandibular retromolar donor site in different vertical facial growth types

PurposeTo assess volumetrically, the impact of vertical facial growth types (VGFT) on the retromolar area as a bone donor site Material and methods60 cone beam computed tomography (CBCT) scans of adult individuals were classified in three groups according to their SN-GoGn angle: hypodivergent group (hG) (33.33%), normodivergent group (NG) (30%) and hyperdivergent group (HG) (36.67%). Total harvestable bone volume and surface (TBV and TBS respectively), total cortical and cancellous bone volume (TCBV and TcBV respectively) and the percentage of cortical and cancellous bone volume (CBV and cBV respectively) were evaluated. ResultsThe whole sample showed a mean TBV of 1220.99±448.81mm³ and a mean TBS of 940.29±259.93mm². Statistically significant differences were found between the different outcome variables and the vertical growth patterns (p<0.001). TBS differs for the different vertical growth patterns with the highest mean of TBS observed in the hG group. TBV also significantly differs between the different vertical growth patterns (p<0.001) with the highest mean observed for the hG individuals. Significant differences in percentages of cBV and CBV were present between the hyper-divergent groups and the other groups (p<0.001) with the hyper-divergent group having the lowest percentage of CBV and the highest percentage of cBV. Conclusionhypodivergent individuals tend to have thicker bone blocks that can be used in onlay technique while thinner bone blocks harvested from hyperdivergent and normodivergent individuals can be used in three-dimensional grafting approach.

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.

Profile changes after class II treatment with twin force appliance in patients with different facial patterns

ABSTRACT Objective This study aimed to compare the soft tissue profile changes after treatment with the Twin Force Bite Corrector (TFBC) appliance in patients with different facial patterns. Material and Methods The sample consisted of 42 patients with Class II malocclusion treated orthodontically without extractions and the TFBC. Six patients with balanced facial patterns were excluded from the sample. The sample was then divided into 2 groups: Group 1 (hypodivergent pattern) consisted of 18 patients with a mean initial age of 17.91 years (SD = 7.13), mean final age of 20.45 years (SD = 7.18), and mean treatment time of 2.53 years (SD = 0.93). Group 2 (hyperdivergent pattern) consisted of 18 patients with a mean initial age of 15.87 years (SD = 5.64), mean final age of 18.63 years (SD = 5.79), and mean treatment time of 2.75 years (SD = 0.60).The initial and final lateral cephalograms of each patient were used to measure the soft tissue profile variables. Intergroup comparison was performed by independent t-tests Results There was no statistically significant difference between the soft tissue profile changes with treatment with the TFBC between the hypodivergent and hyperdivergent groups. Conclusion The treatment of the Class II malocclusion with the Twin Force appliance in patients with hypodivergent and hyperdivergent patterns promoted similar changes in the soft tissue profile.

Volumetric Analysis of the Jaws in Skeletal Class I and III Patients with Different Facial Divergence Using CBCT Imaging.

Aim The main objective was to evaluate any possible maxillary or mandibular volumetric difference between hyperdivergent skeletal Class III (CIII), normodivergent skeletal CIII, hypodivergent skeletal CIII, and normodivergent skeletal Class I (CI) patients using cone-beam computed tomography (CBCT) images. Also, the secondary objective was to investigate any possible correlation between CBCT-derived lateral cephalometric variables and the mandibular and maxillary volumes (MdV and MxV, respectively). Materials and Methods 80 CBCT images of patients between 18 and 32 years of age were taken with one CBCT imaging device (Scanora 3D®, Soredex, Tuusula, Finland). The sample consisted of four groups: 20 hypodivergent skeletal CIII (11 males and 9 females), 20 normodivergent skeletal CIII (7 males and 13 females), 20 hyperdivergent skeletal CIII (8 males and 12 females), and 20 normodivergent skeletal CI (5 males and 15 females). The volumes of both jaws and the ratio of MxV/MdV were obtained using Mimics™ 19 software (Materialise, NV, Belgium), and 2D variables were obtained from CBCT-derived lateral cephalogram using AudaxCeph™ software (Orthodontic software suite, Ljubljana, Slovenia). One-way ANOVA test and Kruskal–Wallis analysis were employed to detect any possible significant difference between the volumetric variables, whereas Pearson's and Spearman's correlation coefficients were calculated to detect any possible relationship between the 2D variables and the volumetric measurements. Results There were no statistically significant differences in the maxillary volume or maxillary/mandibular ratio between the four groups (p=0.081 and 0.432, respectively). There was a significant difference in MdV between CIII hypodivergent (higher mean) and CIII hyperdivergent (p=0.039). There were some correlations between the MdV and 2D variables in the four studied groups especially in the posterior facial height (S-Go) and the facial depth (N-Go). There were some weaker correlations between the MxV and some 2D variables in the CIII hypodivergent and hyperdivergent groups. Conclusions The mandibular volume of the Class III hypodivergent patient was significantly greater than that of the Class III hyperdivergent patients. Correlations between the maxillary or mandibular volumes were found with some of the 2D variables. The volume of both jaws increased when the maxillofacial complex moved toward a horizontal growth pattern.

Anatomical limitations and factors influencing molar distalization.

To analyze the anatomical limitations and characteristics of maxillary and mandibular retromolar regions affecting molar distalization using cone-beam computed tomography (CBCT). A total of 120 qualifying patients were classified into equal groups of skeletal Class II and Class III and stratified by vertical growth pattern, age, sex, and third molar presence. The available distance along the axis of distalization and cortical bone thickness (CBT) were measured in the maxillary and mandibular retromolar regions of Class II and Class III patients, respectively. One-way analysis of variance was used to examine the effects of the factors on the measured data. The minimum available distance of the Class II maxilla was observed at a level 3 mm from the cementoenamel junction (CEJ), while that of the Class III mandible was at a level 9 mm from the CEJ. The average available distance at the limit level was 4.06 ± 1.93 mm in the Class II maxilla, and the average corresponding CBT was 1.00 mm. The average available distance at the limit level in the Class III mandible was 2.80 ± 1.96 mm, and the corresponding CBT was 2.24 mm. In both skeletal Class II and Class III patients, hyperdivergent groups had the least available distance for molar distalization. The limit for available distance in the Class II maxilla is closer to the coronal level, while that of the Class III mandible is closer to the apical level. A hyperdivergent growth pattern in a patient is indicative of less potential for molar distalization. Axial slices of CBCT images provide valuable evaluation for molar distalization regarding limit levels.

Comprehensive three-dimensional positional and morphological assessment of the temporomandibular joint in skeletal Class II patients with mandibular retrognathism in different vertical skeletal patterns

BackgroundOnly a few studies have used 3D cone-beam computed tomography (CBCT) analysis to evaluate the positional and morphological characteristics of the temporomandibular joint (TMJ) in adults with skeletal Class II. No studies have focused on the case of skeletal Class II with mandibular retrognathism in different vertical skeletal patterns. As a result, this study aimed to evaluate and compare the position and morphology of TMJ in adults with skeletal Class II with mandibular retrognathism in different vertical skeletal patterns to the position and morphology of TMJ in the normal Chinese adult population in three dimensions.MethodsThis retrospective study analyzed CBCT images of 80 adult patients. Subjects with skeletal Class II with a normal sagittal position of the maxilla and mandibular retrognathism were classified according to the mandibular angle and facial height ratio into three groups of 20 subjects each: hypodivergent, normodivergent, and hyperdivergent groups, as well as a control group of 20 subjects. The following 3D measurements of TMJ were evaluated: (1) position, parameters, and inclination of the mandibular fossa; (2) position, parameters, and inclination of the mandibular condyle; (3) condyle centralization in their respective mandibular fossae; (4) anterior, posterior, superior, and medial joint spaces; and (5) 3D volumetric measurements of the TMJ spaces. Measurements were statistically analyzed by one-way ANOVA test, followed by Tukey’s post hoc test.ResultsSignificant differences were found in the hyperdivergent and hypodivergent groups compared with the normal group in the vertical and anteroposterior mandibular fossa position, vertical condylar inclination, and condylar width and length. The hyperdivergent group showed the significantly highest condylar inclination with the midsagittal plane; anterior and superior positioning of the condyle; smallest anterior, superior, and medial joint spaces; and largest volumetric total joint space relative to the two other groups.ConclusionsThe 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 TMD diagnosis and orthodontic treatment.

Evaluation of Facial Soft-Tissue Morphology among Different Vertical Skeletal Profile

The objective of this study was to compare facial groups classified according to their vertical skeletal characteristics (hypodivergent, normodivergent, and hyperdivergent) and to their respective soft tissue morphological features, particularly those relating to the lips and chin. 90 Lateral cephalometric x-rays were collected from the Orthodontic clinic at the Faculty of Dentistry, Beirut Arab University and divided into 3 equal groups based on mandibular plane angle, hypodivergent facial type (SN/MP &lt;27°), normodivergent facial type (SN/MP between 27° and 37°), hyperdivergent facial type (SN/MP &gt;37°). The mean upper and lower lips thickness was maximum among hypodivergent group (8.95 mm and 9.35 mm, respectively). The mean upper lip height was maximum among hyperdivergent group (11.3 mm), while lower lip height was maximum among hypodivergent group (25.32 mm). The mean procumbency of upper (PUL) and lower lips (PLL) was maximum among hypodivergent (2.08 mm and 0.87 mm, respectively). However, the mean chin thickness was maximum among hyperdivergent group (7.84 mm). Statistically significant difference among the three groups were observed only in Hypo vs Normo-divergent groups in ULT. Concerning PUL and PLL, there was a statistically significant differences between the different groups in Hypo vs Normodivergent and Hypo vs Hyperdivergent groups. It was concluded that the thickness of upper and lower lip, height of lower lip, and procumbency of both lips showed to be greater in hypodivergent facial patterns.

Identifying cortical plate inclination as a parameter to re-assess transverse discrepancies in untreated adults with different vertical facial heights-A retrospective CBCT study.

To determine the inclination angles of buccal, palatal cortical plates and assess its harmony with existing molar buccolingual inclination in adults with different vertical facial heights. The aim of this study was to identify the role of cortical plate inclination as a diagnostic tool for determining alveolar support in adults with transverse discrepancies. One-hundred and fifty seven CBCTs (50-Hypo-divergent, 51-Normo-divergent and 56-Hyper-divergent growth patterns) of untreated adults were utilized. Cross-sectional slices with respect to the maxillary first molar were taken as orientation landmarks in defined reference planes. Inclination angles for the first molar, buccal and palatal cortical plate were determined with respect to the palatal plane. ANOVA and Post Hoc Tukey's HSD test were carried out to determine significant differences between groups. Molar inclination was significantly greater in hyper-divergent groups compared to normo-divergent and hypo-divergent groups (P<.05). Greater variation between molar inclination and cortical plate inclination (buccal and palatal) was seen in hyper-divergent groups (P<.05). Hypo-divergent and normo-divergent groups showed almost similar molar and cortical plate inclinations; however, there was a significant difference between the buccal and palatal cortical plates (P<.05). Cortical plate inclination is in agreement with molar inclination in hypo- and normo-divergent groups when compared to hyper-divergent groups. In adults with decreased/normal facial heights, greater balance and harmony is observed between the dental and alveolar substructures in the posterior region. In adults with increased facial heights, a greater amount of dentoalveolar compensation is seen with respect to the molar and its surrounding bone support.

Mandibular skeletal posterior anatomic limit for molar distalization in patients with Class III malocclusion with different vertical facial patterns.

ObjectiveThe aim of this study was to compare the differences in mandibular posterior anatomic limit (MPAL) distances stratified by vertical patterns in patients with skeletal Class III malocclusion by using cone-beam computed tomography (CBCT).MethodsCBCT images of 48 patients with skeletal Class III malocclusion (mean age, 22.8 ± 3.1 years) categorized according to the vertical patterns (hypodivergent, normodivergent, and hyperdivergent; n = 16 per group) were analyzed. While parallel to the posterior occlusal line, the shortest linear distances from the distal root of the mandibular second molar to the inner cortex of the mandibular body were measured at depths of 4, 6, and 8 mm from the cementoenamel junction. MPAL distances were compared between the three groups, and their correlations were analyzed.ResultsThe mean ages, sex distribution, asymmetry, and crowding in the three groups showed no significant differences. MPAL distance was significantly longer in male (3.8 ± 2.6 mm) than in female (1.8 ± 1.2 mm) at the 8-mm root level. At all root levels, MPAL distances were significantly different in the hypodivergent and hyperdivergent groups (p < 0.001) and between the normodivergent and hyperdivergent groups (p < 0.01). MPAL distances were the shortest in the hyperdivergent group. The mandibular plane angle highly correlated with MPAL distances at all root levels (p < 0.01).ConclusionsMPAL distances were the shortest in patients with hyperdivergent patterns and showed a decreasing tendency as the mandibular plane angle increased. MPAL distances were significantly shorter (~3.16 mm) at the 8-mm root level.

Computed tomography assessment of maxillary bone density for orthodontic mini-implant placement with respect to vertical growth patterns.

To quantitatively measure and report bone density of maxilla in the interradicular (alveolar and basal bone) and infrazygomatic crest (IZC) region in various growth patterns among Dravidian individuals. This was a retrospective spiral computed tomography (CT) study. The study was conducted at the Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India. Sixty CT scans (24 men, 36 women; mean age = 25.3 years and 23.8 years, respectively) divided equally into three groups based on vertical facial proportions were included. Bone density measurements in Hounsfield units (HU) were performed using Philips and RadiAnt DICOM viewers. Buccal cortical, palatal cortical and cancellous bone regions were analysed in a Philips DICOM viewer and IZC region was analysed in a RadiAnt DICOM viewer. Statistical analysis with one-way ANOVA and post-hoc Tukey HSD test was done. The hypodivergent group had a significantly higher bone density at the buccal cortex in posterior region (P < 0.05) when compared to the normodivergent and hyperdivergent groups. Buccal basal bone was denser than buccal alveolar bone (P < 0.05) in all three groups. In the IZC region, hypodivergent groups had significantly higher density values when compared to the normodivergent and hyperdivergent groups (P < 0.05). The present study concluded that cancellous bone density in the interradicular regions was greatest in the anterior sites and was not influenced by growth pattern. Hypodivergent groups tend to have higher density in the posterior regions (buccal and palatal cortical bone) and at the IZC region compared to normodivergent and hyperdivergent groups.

Comparison of mandibular cross-sectional morphology between Class I and Class II subjects with different vertical patterns: based on CBCT images and statistical shape analysis

BackgroundThis study is aimed to (1) investigate the influence of sagittal and vertical patterns on mandibular cross-sectional morphology and to (2) provide visualized mandibular cross-sectional morphology in different groups with General Procrustes Analysis (GPA), canonical variance analysis (CVA) and discriminant function analysis (DFA).Methods324 cone-beam computed tomography (CBCT) images were collected to analyze mandibular cross-sectional morphology and were categorized into 12 groups according to sagittal and vertical pattern and gender. One-way analysis of variance (ANOVA) was used to compare the difference among the groups. Thirty equidistant points were marked along the contour of mandibular cross-section and GPA, CVA and DFA were applied.Results(1) Mandibular height in hyperdivergent groups was significantly higher than that in normodivergent and hypodivergent groups (P < 0.05). (2) Hypodivergent groups showed significantly wider upper third of mandibular width from symphysis to molar region than that in hyperdivergent group (P < 0.05), except for the premolar and molar regions in male groups (P > 0.05). (3) Class II hyperdivergent group showed narrowest lower third width in the molar region, with the mean value of 12.03 mm in females and 11.98 mm in males. (4) For males and females, the ratio between height and lower third width at symphysis was significantly higher in Class II hyperdivergent group than that in Class I hyperdivergent group (P < 0.05).Conclusions(1) The influence of vertical facial patterns on mandibular cross-sectional morphology is more obvious than that of sagittal skeletal pattern. (2) Subjects with increased vertical dimension presented with a remarkable “slimer” mandibular cross-sectional morphology at symphysis. (3) A deeper curve along the anterior contour of symphysis in Class II hyperdivergent group was noted with GPA.

Morphometric analysis of palatal rugae in different malocclusions

Studies of the association between palatal rugae (PR) and malocclusion are scarce. While unstable following treatment such as rapid maxillary expansion, we hypothesized that PR differ among malocclusions because of genetic determination but also different environmental conditions during development. Our goal was to assess the possible association between PR morphometric measurements and both sagittal and vertical characteristics of malocclusion. Maxillary pretreatment dental casts of 243 nongrowing individuals (115 males, 128 females, age 25.5 ± 7.5years) were laser scanned (Perceptron ScanWorks® V5, Hallam VIC, Australia); angular and linear measurements of the first three PR were recorded in transverse and anteroposterior directions. Cephalometric measurements were obtained from corresponding digitized lateral cephalograms. Statistics included analyses of variance to compare PR measurements among sagittal (classI, classII divisions1 and 2, classIII) and vertical (hypodivergent, normodivergent, hyperdivergent) malocclusion groups and the Pearson correlations among PR dimensions and cephalometric measurements. PR measurements were statistically different between malocclusions, especially with respect to vertical patterns. Amajority of transverse and anteroposterior rugae measurements were greatest in classII division2 subjects. PR were more anteriorly directed in hypodivergent than hyperdivergent groups; the transverse separation between opposing rugae points was smaller. Correlations were generally low. The findings suggest the possibility for PR to adapt to environmental effects in developing malocclusions, mostly in the classII division2 phenotype. This premise reinforces the need to explore in longitudinal studies the long-term environmental influences on rugae superimposed on their genetically determined morphological pattern.

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.