Buccolingual inclinations of posterior teeth in subjects with different facial patterns

Relationship of buccolingual inclination between the alveolar bone and first molar in different vertical facial types: A CBCT study

BACKGROUND

This study aimed to investigate the differences in the buccolingual inclination and transverse width of maxillary and mandibular first molars among different vertical facial types.

METHODS

In all, 78 samples were divided into three groups based on the GoGn-SN angle: the low-angle group (n = 26, mean age=24.21±5.11), average-angle group (n = 26, mean age=22.66±3.72), and high-angle group (n = 26, mean age=22.23±2.43). Cone beam computed tomography (CBCT) measurements were used to assess the buccolingual inclination of the axis of the maxillary and mandibular first molars, as well as the buccolingual inclination of the alveolar bone, the dental arch width, and the basal bone width. One-way ANOVA, the LSD test, and Pearson correlation analysis were performed.

RESULTS

The high-angle group showed significantly greater lingual inclination of the maxillary alveolar bone than the low-angle group and average-angle group (p < 0.001; p < 0.05). The difference in buccolingual inclination of the axis of the maxillary first molar and the alveolar bone was significantly greater in the high-angle group than in the low-angle group (p < 0.05). Both the maxillary and mandibular dental arch were significantly narrower in the high-angle group than in the other two groups. The mandibular basal bone was also significantly narrower in the high-angle group than in the low-angle group and average-angle group (p < 0.001; p < 0.01).

CONCLUSIONS

The alveolar bone of maxillary first molar in the high-angle group was more palatal inclined than that the low-angle group and the average-angle group, which suggests that orthodontists should pay more attention to the root-bone relationship in the high-angle group during expansion treatment to prevent bone fenestration and dehiscense.

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

BACKGROUND

 Understanding the attributes of vertical patterns is essential for delivering optimal orthodontic care. Cone-beam computed tomography (CBCT) represents a valuable resource for assessing the buccolingual inclination of the teeth. The present research delves into examining the buccolingual inclination of premolars in nongrowing individuals exhibiting diverse vertical facial patterns.

METHODS

CBCT scans of 66 adult patients (31 males and 35 females), mean age 31.6 years (SD = 6.4 years), exhibiting 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 the buccolingual inclination of the premolars among the three vertical patterns.

RESULTS

 Statistically significant differences between the three groups were observed in the buccolingual inclinations of both maxillary and mandibular first and second premolars (p < 0.05). The upper right first premolars exhibited a significantly increased buccal inclination in the normodivergent group compared to the hypodivergent group (p < 0.05). In contrast, the two groups had no notable differences in the inclination of the remaining premolars. The upper right and left first premolars exhibited a significantly increased buccal inclination in the hyperdivergent group compared to the hypodivergent group (p < 0.05). In contrast, there were no notable differences in the inclination of the remaining premolars between the two groups. The lower left first premolars exhibited a significantly increased lingual inclination in the hyperdivergent group compared to the normodivergent group (p < 0.05). In contrast, the two groups had no notable differences in the inclination of the remaining premolars. The upper right second premolars exhibited a significantly increased buccal inclination, and the lower left second premolars exhibited greater lingual inclination in the normodivergent group than in the hypodivergent group (p < 0.05). In contrast, there were no notable differences in the inclination of the remaining premolars between the two groups. The upper right and left second premolars exhibited a significantly increased buccal inclination, and the lower left second premolars exhibited greater lingual inclination in the hyperdivergent group than in the hypodivergent group (p < 0.05). In contrast, there were no notable differences in the inclination of the lower right second premolars between the two groups. There were no notable differences in the inclination of the second premolars between the hyperdivergent and normodivergent groups.

CONCLUSIONS

 In individuals presenting with class II relationships, the buccolingual inclinations of the first and second premolars exhibit similarities and variations across distinct facial patterns. As such, it is imperative for orthodontic practitioners to exercise meticulous consideration of these nuances throughout treatment.

Buccolingual inclination of posterior dentition in maxillary impacted canine patients using quadrant analysis - A cone-beam computed tomographic study

BACKGROUND

To examine the buccolingual inclination of maxillary posterior teeth, curve of Wilson, and transversal dimensions in palatally impacted maxillary canine patients, compared to controls by cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Pre-treatment images of 22 bilateral, 32 unilateral impacted maxillary canine patients and 30 controls were included. All patients had palatally impacted canines, with no posterior cross-bite. Data were reclassified in quadrants according to the presence of impaction, as the impaction quadrant (right and left quadrants of 22 bilateral impacted cases, and quadrants presenting impaction of 32 unilateral cases, n = 76), unaffected quadrant (quadrant without impaction in 32 unilateral cases, n = 32) and the control quadrant (right and left quadrants of 30 controls, n = 60) to evaluate the buccolingual inclination angle, transversal width, and arch perimeter. Additionally, comparisons were made regarding curve of Wilson and total arch perimeter among bilateral and unilateral impaction groups with the control group. Statistical analysis was performed by one-way ANOVA and Kruskal Wallis tests. Tukey or Dunn tests were used for comparisons between groups in pairs.

RESULTS

No significant difference was found for the buccolingual inclination of maxillary posterior teeth and curve of Wilson among groups. The buccolingual inclination of canines in the impaction quadrant was significantly lower than the other quadrants (p < 0.001). Basal bone width at the level of second premolars, and alveolar width at both premolars were significantly narrower in the impaction quadrant than in the unaffected quadrant (p < 0.05). Dental arch width at the level of first premolar was significantly decreased in the impaction quadrant compared to other quadrants (p < 0.05). Arch perimeter was significantly reduced in the impaction quadrant than in the unaffected quadrant (p < 0.05).

CONCLUSION

The presence of bilateral or unilateral palatally impacted maxillary canines did not effect the buccolingual inclination of posterior teeth, and curve of Wilson. Transverse discrepancy was evident in the impaction quadrant even in the absence of posterior cross-bite. Quadrant analysis was particularly useful in evaluating asymmetry for basal bone and alveolar bone widths in the premolar region in patients with unilateral palatally impacted maxillary canine patients.

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.

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

OBJECTIVE

This study sought to three-dimensionally (3D) evaluate the maxillomandibular basal bone and dentoalveolar widths using cone-beam computed tomography (CBCT) scans in adult Chinese populations with different vertical and sagittal facial skeletal patterns whilst no apparent posterior dental crossbite.

MATERIALS AND METHODS

The retrospective cross-sectional comparative study enrolled CBCT images of 259 adult patients (125 males and 134 females). The subjects were divided into the hyperdivergent(n = 82), hypodivergent(n = 88), and normodivergent(n = 89) groups based on the Jarabak ratio (S-GO/N-Me), which were further divided into three subgroups of skeletal Class I, II and III, based on both the ANB angle and AF-BF parameters. ANOVA was used to analyze the extracted data of the studied groups. The intra- and inter-observer reliability was analyzed using the intra-class correlation coefficient (ICC).

RESULTS

In all three vertical facial skeletal patterns, the skeletal Class II had significantly smaller mandibular basal bone width compared to skeletal Class I and Class III, both at the first molar and first premolar levels. The skeletal Class III seemed to have smaller maxillary basal bone width compared to skeletal Class I and Class II malocclusions; however, a significant difference was found only in the normodivergent pattern. As for the dentoalveolar compensation, it was most notable that in the hypodivergent growth pattern, the skeletal Class II had significantly smaller maxillary dentoalveolar width compared to the Class I and Class III groups, both at the first molar and first premolar levels.

CONCLUSIONS

Based on the sample in the present study, skeletal Class II has the narrowest mandibular basal bone regardless of the vertical facial skeletal pattern.

CLINICAL RELEVANCE

For Chinese adults with no apparent transverse discrepancy, the maxillomandibular basal bone and dentoalveolar widths are revealed in specific categories based on different vertical and sagittal facial skeletal patterns. In diagnosis and treatment planning, particular attention should be paid to skeletal Class II for possibly existing mandibular narrowing.

Three-dimensional analysis of posterior tooth inclinations in transverse and sagittal relationships: A cross-sectional study

OBJECTIVE

To compare tooth inclinations in different sagittal skeletal patterns and transverse maxillary relationships three-dimensionally.

METHODS

A cross-sectional study carried out with 132 three-dimensional digital models in the complete permanent dentition divided into six groups (n=22); three groups with maxillary atresia: G1- skeletal class I, G2- skeletal class II and G3-skeletal class III; three groups without maxillary atresia: G4- skeletal class I; G5- skeletal class II and G6- skeletal class III. The comparison between the skeletal pattern was performed by the non-parametric tests of Kruskal Wallis and Dunn and between the groups by the non-parametric test of Mann Whitney.

RESULTS

Subjects with skeletal class II and maxillary atresia had a greater lingual inclination of the maxillary teeth than those with class I and III; Subjects with skeletal class II without atresia had a less lingual inclination of the mandibular molars than the other classes (p<0.05). The maxillary premolars showed no variation in dental inclination with atresia, independent of the skeletal class in G1, G2, and G3 (p>0.05). The mandibular premolars showed that the groups without atresia G4, G5, and G6 presented no significant difference (p>0.05). Lower premolars in skeletal class III malocclusion individuals with atresia had a more negative inclination than the others.

CONCLUSION

There is a difference in the inclination of posterior teeth between individuals with and without maxillary atresia and skeletal classes I, II, and III.

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

OBJECTIVES

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).

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

A Correlation Analysis between Arch Width and Molar Inclination Using Cone-Beam Computed Tomography Transverse Measurements: A Cross-Sectional Study

A new era in 3-dimensional analysis has begun with the use of cone-beam computed tomography (CBCT) in orthodontics, which promises to provide a more thorough understanding of the craniofacial skeletal architecture. This study aimed to investigate the correlation between the transverse basal arches discrepancy and dental compensation by utilizing CBCT width analysis. An observational study was conducted to retrospectively review 88 CBCT scans of patients presented to dental clinics from 2014 to 2020 obtained from the Planmeca Romexis x-ray system at three centers. Dental compensation data across normal and narrow maxillae were analyzed and a Pearson correlation was used to find the relationship between molar inclination and width difference. Significant maxillary molar compensation differences were observed between the normal maxilla and narrow maxilla group, where the amount of dental compensation (164.73 ± 10.15) was higher in the narrow maxilla group. A significant negative correlation (r = -0.37) was observed between width difference and maxillary molar inclination. Maxillary molars were tipped buccally to compensate for the reduced maxillary arch width. These findings are important to determine the amount of needed maxillary expansion taking into account the buccal inclination while treating cases.

Soft- and Hard-Tissue Thicknesses in Patients with Different Vertical Facial Patterns and the Transverse Deficiencies, An Integrated CBCT-3D Digital Model Analysis

Different vertical facial patterns may present different bone and gingival thicknesses at the molar level and can be influenced by the dental compensations that manifest in the presence of transverse bone discrepancies. A retrospective analysis was made of 120 patients divided into three groups according to their vertical facial patterns (mesofacial, dolichofacial or brachyfacial). Each group in turn was divided into two subgroups according to the presence or absence of transverse discrepancies assessed by cone-beam computed tomography (CBCT). The bone and gingival measurements were made integrating a CBCT-3D digital model of the patient dentition. In the brachyfacial patients, the distance from the palatine root to the cortical bone corresponding to the right upper first molar was significantly greater (1.27 mm) than in the dolichofacial (1.06 mm) and mesofacial (1.03 mm) (p < 0.05) patients. The brachyfacial and mesofacial patients with transverse discrepancies presented a greater distance from the mesiobuccal root of the left upper first molar and from the palatine root to the cortical bone, while in the dolichofacial individuals the distances were shorter (p < 0.05); The presence of transverse bone discrepancies in brachyfacial and mesofacial patients without posterior cross-bite implies a better dentoalveolar expansion prognosis than in dolichofacial individuals.

Buccolingual Inclination of Second Molars in Untreated Adolescents and Adults with Near Normal Occlusion: A CBCT Study

The mandibular second molars are lingually positioned relative to the alveolar ridge and have a limited amount of lingual alveolar bony support. As the maxillary second molars are articulated with the mandibular second molars, maintaining the normal buccolingual inclination of both maxillary and mandibular second molars would potentially help to not only optimize the masticatory function, but also avoid dehiscence and fenestration. The current study evaluated the buccolingual inclination of second molars in untreated adolescents and adults. One hundred and two Caucasian subjects with skeletal class I and minimum dental arch crowding/spacing were selected and divided into two groups: (1) adolescent group: age 12-18 years, N = 51 (21 females, 30 males); (2) adult group: age 19-65 years, N = 51 (40 females, 11 males). For each subject, the inclination for each second molar was measured as the angle between the long axis of each tooth and a vertical line on cone beam computed tomography images. The Mann-Whitney U test was used for intergroup comparisons. Maxillary second molars exhibited a buccal inclination of 15.30° in the adolescent group and 15.70° in the adult group. Mandibular second molars exhibited a lingual inclination of 17.05° in the adolescent group and 15.20° in the adult group. No statistically significant differences were detected between the age groups. In addition, a statistically significant difference was only found between genders in the adolescent group for the maxillary second molar inclination. In summary, maxillary second molars exhibited buccal inclination and mandibular second molars exhibited lingual inclination. The amount of buccolingual inclination of the second molars was similar in the adolescent and adult groups.

Transverse Analysis of Maxilla and Mandible in Adults with Normal Occlusion: A Cone Beam Computed Tomography Study

Objectives: To study the transverse widths of maxilla and mandible and their relationship with the inclination of first molars. Materials and Methods: Fifty-six untreated adults (12 males, 44 females) with normal occlusion were included. On each Cone Beam Computed Tomography (CBCT) image of the subject, inter-buccal and inter-lingual bone widths were measured at the levels of hard palate, alveolar crest and furcation of the first molars, and maxillomandibular width differentials were calculated. In addition, the buccolingual inclination of each first molar was measured and its correlation with the maxillomandibular width differential was tested. Results: At the furcation level of the first molar, the maxillary inter-buccal bone width was more than the mandibular inter-buccal bone width by 1.1 ± 4.5 mm for males and 1.6 ± 2.9 mm for females; the mandibular inter-lingual bone width was more than the maxillary inter-lingual bone width by 1.3 ± 3.6 mm for males and 0.3 ± 3.2 mm for females. For females, there was a negative correlation between the maxillomandibular inter-lingual bone differential and maxillary first molar buccal inclination (p < 0.05), and a positive correlation between the maxillomandibular inter-lingual bone differential and mandibular first molar lingual inclination (p < 0.05). Conclusions: This is a randomized clinical study on transverse analysis of maxilla and mandible in adults with normal occlusion using CBCTs. On average: (1) At the furcation level of the first molars, the maxillary inter-buccal bone width was slightly wider than mandibular inter-buccal bone width; whereas the mandibular inter-lingual bone width was slightly wider than maxillary inter-lingual bone width; (2) A statistically significant correlation existed between the maxillomandibular transverse skeletal differentials and molar inclinations.

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

OBJECTIVE

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.

MATERIALS AND METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Can palatal depth influence the buccolingual inclination of molars? A cone beam computed tomography-based retrospective evaluation

Objective:

To interpret a correlation between buccolingual inclination of molars and palatal depth in hyperdivergent patients and to identify importance of determining inclination of molars in assessing transverse discrepancies (as skeletal or dental)

Design:

This was a retrospective cone beam computed tomography (CBCT) study.

Setting:

The study was conducted in the Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India.

Methods:

This was a retrospective CBCT study of 79 patients who underwent diagnostic CBCT for treatment purposes. The CBCT scans were evaluated systematically and the required parameters were accessed with suitable reference planes. Student’s t-test (95% confidence interval) was performed to determine buccolingual inclination of first molars between the right and left sides. Only patients with a vertical growth pattern and skeletal class I relation were included and they were classified into three groups based on their palate depth.

Results:

In patients with palatal depth > 22 mm, the mean inclination of molars was 7.4°; with palatal depth in the range of 19–22 mm, the mean inclination of molars was 5.23°; and with palatal depth < 19 mm, the mean inclination of molars was 2.9°. Results showed that there was a significant correlation between the buccolingual inclination of molars and the palate depth in vertical growers ( P < 0.05).

Conclusion:

The buccolingual inclination of first molars is increased in patients with greater palatal depth. This parameter is helpful in classifying crossbites as skeletal or dental. The amount of compensation required to correct the cross bite can be adjusted using Korkhaus Index.

Buccolingual Inclination of Canine and First and Second Molar Teeth and the Curve of Wilson in Different Sagittal Skeletal Patterns of Adults Using Cone-Beam Computed Tomography

Objectives

This study aimed to assess the buccolingual inclination of canine and first and second molar teeth and the curve of Wilson in different sagittal skeletal patterns in untreated adults using cone-beam computed tomography (CBCT).

Materials and Methods

Sixty-six CBCT scans of adults (mean age: 28.74 ± 5.25 years) were evaluated in this cross-sectional study. The images were standardized using the Frankfurt horizontal plane and the interorbital line. The sagittal skeletal pattern was determined using the ANB angle and Wits appraisal. Inclination angles were measured by NNT Viewer and Mimics software. The curve of Wilson was measured by connecting the tips of mesiobuccal and mesiolingual cusps of maxillary first and second molars along the buccal groove and measuring the formed angle. Data were analyzed using ANOVA.

Results

The intraobserver agreement was 0.969. The mean inclination of maxillary first and second molars in class I and III patients was significantly higher than that in class II patients (P < 0.05). The mean inclination of mandibular first and second molars in class II patients was significantly higher than that in class I and III patients (P < 0.05). The difference in inclination of maxillary and mandibular canine teeth was not significant (P > 0.05). The mean curve of Wilson in second molars of class II patients was significantly higher than that in class I patients (P < 0.05).

Conclusion

In different sagittal skeletal patterns, a compensatory relationship exists between the opposing teeth, which, along with the standards of crowns, can be used to determine the appropriate position of teeth in dental arch.

Assessment of buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth in patients with severe skeletal Class III malocclusion with mandibular asymmetry

INTRODUCTION

The purpose of this study was to evaluate the buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth in patients with severe skeletal Class III malocclusion with and without mandibular asymmetry and compare with those in patients with skeletal Class I malocclusion.

METHODS

Cone-beam computed tomography images of 69 patients with severe skeletal Class III malocclusion and 30 patients with skeletal Class I malocclusion were collected and reconstructed with Dolphin 3D software. Based on the distance from menton to the sagittal plane (d), the patients with skeletal Class III malocclusion were divided into a symmetry group (d ≤ 2 mm) and an asymmetry group (d ≥ 4 mm). Buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth were measured and compared. Correlations among dental measurements, severity of sagittal discrepancy, and mandibular deviation were analyzed.

RESULTS

Maxillary posterior teeth on the deviated side in Class III asymmetry group and symmetry group were buccally inclined compared with the Class I group (P < 0.001). A significant negative correlation was noted between buccolingual inclination of maxillary posterior teeth and ANB value with Spearman correlation coefficient of maxillary first molar, second premolar, and first premolar of -0.687, -0.485 and -0.506, respectively (P < 0.001). Maxillary first molar showed thinner buccal alveolar bone on deviated side in asymmetry group and symmetry group of Class III, compared with the Class I group, with average values of 1.21 mm, 1.19 mm, and 1.83 mm, respectively (P < 0.05). The maxillary first premolar also showed thinner buccal alveolar bone on deviated side in Class III asymmetry group compared with the Class I group, with average values of 0.87 mm and 1.28 mm, respectively (P < 0.05).

CONCLUSIONS

Decompensation of buccally inclined posterior teeth in patients with skeletal Class III malocclusion should be more cautious owing to thinner buccal alveolar bone to avoid a high risk of fenestration and dehiscence.

Mesiodistal angulation of posterior teeth in orthodontic patients with different facial growth patterns

Background. Mesiodistal and buccolingual angulations of teeth are variable in different malocclusion classes. This study aimed to assess the mesiodistal angulation of posterior teeth in orthodontic patients with vertical, normal, and horizontal facial growth patterns. Methods. This descriptive, cross-sectional study evaluated 150 lateral cephalograms of orthodontic patients. According to cephalometric analysis, facial growth patterns were divided into three groups of normal, horizontal, and vertical (n=50). The angulation of maxillary and mandibular posterior teeth was then measured. Data were analyzed using SPSS 22. Results. The results showed an increase in the mean angle of maxillary and mandibular posterior teeth relative to palatal and mandibular planes in patients with a vertical facial growth pattern. Conversely, their angulation decreased relative to the bisected occlusal plane (BOP). The angulation of posterior teeth decreased relative to palatal and mandibular planes and increased relative to the occlusal plane with an increase in overbite. The mean angle of all maxillary teeth relative to the palatal plane was significantly greater in open bite patients compared to normal and deep bite patients. This value in patients with normal bite was significantly greater than that in deep bite patients (P<0.05). Conclusion. The current results revealed that in patients with a vertical growth pattern, all the posterior teeth had a forward inclination. Conversely, in patients with a horizontal growth pattern, the teeth had a backward inclination.

Evaluation of buccolingual molar inclinations among different vertical facial types

Objective

The aim of this study was to compare the buccolingual inclination of maxillary and mandibular molars in adults with different vertical facial types.

Methods

Cone-beam computed tomography images of 135 adult patients (age, 20–45 years) with skeletal Class I maxillomandibular relationships were assigned to normodivergent (n = 46), hypodivergent (n = 49), and hyperdivergent groups (n = 40) according to linear and angular sella-nasion/gonion-menton measurements. The normodivergent group consisted of 24 females and 22 males, hypodivergent group of 26 females and 23 males, and hyperdivergent group of 24 females and 16 males. Buccolingual inclination of the maxillary and mandibular first and second molars was measured relative to the occlusal plane. One-way analysis of variance was used for intergroup comparison. Gender differences were evaluated using independent t-tests.

Results

Buccolingual molar inclinations did not differ significantly between females and males (p > 0.05). There were no statistically significant differences among the buccolingual inclinations of the first and second maxillary and mandibular molars of the groups (p > 0.05).

Conclusions

Buccolingual inclinations of maxillary and mandibular molars are similar in normodivergent, hyperdivergent, and hypodivergent adults with Class I sagittal relationships.

Buccolingual inclination of molars in untreated children and adults: A cone beam computed tomography study

OBJECTIVES

To evaluate and compare the buccolingual inclinations of maxillary and mandibular first molars in untreated children and adults.

MATERIALS AND METHODS

One hundred and thirty-eight subjects were selected and divided into three groups, as follows: (1) age 6-9 years, N = 46; (2) age 10-19 years, N = 56; and (3) age 25-35 years, N = 36. For each subject, existing cone beam computed tomography images were used, and the long axis for each maxillary and mandibular first molar was determined. The converge angles formed by the long axis of left and right maxillary first molars and by the long axis of left and right mandibular first molars were measured.

RESULTS

The maxillary molars exhibited buccal inclination, with the converge angle of 21.1° ± 9.5° in group 1, 17.3° ± 8.6° in group 2, and 9.3° ± 7.3° in group 3. Statistically significant differences were found between groups 1 and 3 and groups 2 and 3, but not between groups 1 and 2. The mandibular molars exhibited lingual inclination, with the converge angle of 34.9° ± 11° for group 1, 26.6° ± 9.2° for group 2, and 26.1° ± 7.7° for group 3. Statistically significant differences were found between groups 1 and 2 and groups 1 and 3, but not between groups 2 and 3.

CONCLUSIONS

Maxillary first molars exhibited buccal inclination. Adults displayed less inclination than did children. Mandibular first molars exhibited lingual inclination. Adults displayed less inclination than did children. Some degree of curve of Wilson should be maintained at the end of orthodontic treatment to fulfill physiologic needs and stability.

The physiological linkage between molar inclination and dental macrowear pattern

OBJECTIVES

Exact symmetry and perfect balance between opposite jaw halves, as well as between antagonistic teeth, is not frequently observed in natural masticatory systems. Research results show that asymmetry in our body, skull, and jaws is often related to genetic, epigenetic, environmental and individual ontogenetic factors. Our study aims to provide evidence for a significant link between masticatory asymmetry and occlusal contact between antagonist teeth by testing the hypothesis that tooth inclination is one of the mechanisms driving distribution of wear in masticatory phases in addition to dietary and cultural habits.

MATERIALS AND METHODS

The present work investigates the relationship between dental macrowear patterns and tooth inclinations on a sample of complete maxillary and mandibular 3D models of dental arches from 19 young and adult Yuendumu Aboriginal individuals. The analysis was carried out on first molars (M1) from all quadrants. Occlusal Fingerprint Analysis was used for the quantification of macrowear patterns, and 2D cross-sectional geometric analysis was carried out to investigate asymmetry in dental arches.

RESULTS

The asymmetry is highly variable on both arches, and it is associated with differences in the inclination of upper M1 crowns. Each molar has variable inclination (buccal/lingual) which influence tooth to tooth contact, producing greater or lesser variation in wear pattern. Interindividual variability of morphological variation of the occlusal relationship has to be considered in macrowear analysis.

DISCUSSION

Our results suggest that overall asymmetry in the masticatory apparatus in modern humans affects occlusal contact areas between antagonist teeth influencing macrowear and chewing efficiency during ontogeny.

Changes in the buccolingual inclination of first molars with growth in untreated subjects: A longitudinal study

OBJECTIVES

To assess longitudinal changes in the buccolingual inclination of the maxillary and mandibular first molars in untreated male and female subjects.

MATERIALS AND METHODS

Forty-seven male and 48 female subjects whose longitudinal dental casts were available at ages 6-16 years, with normal maxillary and mandibular arch forms were included. The original casts at ages 6, 7, 8, 9, 10, 12, 14, and 16 years were digitized and standardized. Measurements were recorded as the differences in cusp heights in the vertical dimension for the mandibular and maxillary first molars using OrthoInsight software.

RESULTS

On average, for boys from age 6 to 16 years, both maxillary and mandibular first molars uprighted with age. Maxillary molars uprighted 0.403 mm on the left and 0.418 mm on the right; mandibular molars uprighted 0.441 mm on the left and 0.589 mm on the right. Similarly, for girls from age 6 to 16, both maxillary and mandibular molars uprighted with age. Maxillary molars uprighted 0.67 mm on the left and 0.574 mm on the right; mandibular molars uprighted 0.358 mm on the left and 0.329 mm on the right.

CONCLUSIONS

Maxillary molars erupted with buccal crown inclination at age 6 in both boys and girls and uprighted lingually with growth. At age 16, maxillary molars were not completely upright but rather maintained some buccal crown inclination. Mandibular molars erupted with lingual crown inclination at age 6 and uprighted buccally with age. At age 16, mandibular molars were not completely upright but rather maintained some lingual inclination.

Buccolingual angulation and intermolar width changes in the maxillary first molars of untreated growing children

INTRODUCTION

Buccolingual inclinations of the maxillary permanent molars and intermolar widths increase with growth for Class I subjects. Changes for untreated Class II subjects have not yet been assessed. The aim of this study was to test the hypothesis that changes in palatal inclination of the maxillary molars and intermolar width throughout growth vary between Class I and Class II molar occlusions.

METHODS

Patients were selected from the Forsyth/Moorrees Twin Study. Dental models taken for 6 consecutive years of 55 untreated subjects (28 with Angle Class I and 27 with Angle Class II occlusion) were scanned. The images were superimposed on the palatal rugae, and the angle between a reference plane and the buccolingual inclination plane was used to calculate the buccolingual molar inclination at each time point. The distance between lingual groove points was used to calculate the intermolar width.

RESULTS

All molars showed increasing palatal inclinations over the 6 years. The change for each time interval was statistically significant. Class I subjects demonstrated significantly greater palatal inclination at each time point. The molar inclination changed by means of 4.99° for Class I subjects and 6.25° for Class II subjects. Intermolar width increased continuously (P <0.001) and was significantly greater (P <0.05) for Class I patients.

CONCLUSIONS

These results suggest that palatal inclination of the maxillary permanent first molars occurs continuously between ages 9 and 14 years, with Class II subjects showing greater changes. The intermolar width increases steadily during this time, with Class II subjects having a narrower intermolar width and less change over time.

Buccolingual inclination of first molars in untreated adults: A CBCT study

OBJECTIVE

To evaluate the buccolingual inclinations of maxillary and mandibular first molars in untreated adults.

MATERIALS AND METHODS

Fifty-nine subjects (14 males and 45 females; mean age, 41.2 years) with no missing teeth, no crossbite, and minimal crowding were included. For each subject, a CBCT was taken. The long axis of each first molar was determined, and the inclination of each molar was measured using the long axis and the floor.

RESULTS

One hundred seventeen out of 118 mandibular first molars measured had a lingual inclination, with a mean of 12.59° ± 5.47°. For the maxillary first molars, 107 out of 118 had a buccal inclination, with a mean of 4.85° ± 4.22°.

CONCLUSIONS

There is a curvature to the inclinations of first molars in untreated adults, where the maxillary molars have a slight buccal inclination and mandibular molars have a slight lingual inclination.

Transverse dental compensation in relation to sagittal and transverse skeletal discrepancies in skeletal Class III patients

INTRODUCTION

The purposes of this study were to compare the buccolingual inclinations of the posterior teeth in skeletal Class III patients with and without facial asymmetry with those of skeletal Class I patients and to investigate their relationships with sagittal and transverse skeletal discrepancies.

METHODS

Sixty-three skeletal Class III adult patients were divided into 2 groups according to the degree of menton deviation: a symmetry group with deviation less than 2 mm (n = 30), and an asymmetry group with deviation greater than 4 mm (n = 33). The control group comprised 25 skeletal Class I patients. The buccolingual inclinations of the posterior teeth measured on cone-beam computed tomography images were compared among the 3 groups, and regression analysis was performed to investigate the relationships between the inclinations and the sagittal and transverse skeletal discrepancies.

RESULTS

The symmetry group showed greater buccal inclinations of the maxillary posterior teeth and lingual inclinations of the mandibular second molars than did the control, and this was correlated with the ANB angles. The deviated sides in the asymmetry group showed the greatest transverse dental compensation, which was correlated with menton deviation, whereas the nondeviated sides showed no significant transverse dental compensation.

CONCLUSIONS

Transverse dental compensation is closely related to sagittal and transverse skeletal discrepancy in skeletal Class III patients.

Quantitative cone-beam computed tomography evaluation of premaxilla and symphysis in Class I and Class III malocclusions

AIMS

In order to compare the premaxilla and symphysis in Class I and Class III individuals, we measured the following parameters on CBCT scans: incisor inclination, symphyseal morphology, upper alveolar process morphology, symphyseal and maxillary leeway space, as well as anterior and posterior maxillary and mandibular bone thickness at various points below the cementoenamel junction.

MATERIALS AND METHODS

CBCT scans were taken of 62 individuals (41 females and 21 males) of ages ranging between 11 and 53years (mean 23.26). The dentoskeletal relationship and alveolar process morphology (thickness) were evaluated on axial slices of the upper and lower jaws, and Student's parametric t-test for paired data was used to compare Class I and Class III values within different facial types.

RESULTS

Many significant differences in measurements between the two facial types were noted in terms of tooth inclination, alveolar thickness, and leeway space.

CONCLUSIONS

Our findings confirm that Class III patients have little periodontal support at the upper and lower incisors, irrespective of the amount of symphyseal leeway space available, and any tooth movement must therefore be carefully planned and monitored.

Association between mandibular posterior alveolar morphology and growth pattern in a Chinese population with normal occlusion

OBJECTIVE

To investigate the relationship between growth patterns and mandibular posterior tooth-alveolar bone complex morphology in a Chinese population with normal occlusion.

METHODS

Forty-five patients with normal occlusion (23 males, 22 females) were included in this study. Among these patients, 20 displayed the vertical growth pattern, and 20 had the horizontal growth pattern, while the remaining patients displayed the average growth pattern. All of the patients underwent dental cone beam computed tomography (CBCT), which included the region of the mandibular posterior teeth and the alveolar. A linear regression analysis and a correlation analysis between the facial height index (FHI) and the alveolar bone morphology were performed.

RESULTS

The inclination of the molars, the thickness of the cortical bone, and the height of the mandibular bone differed significantly between patients with the horizontal growth pattern and those with the vertical growth pattern (P<0.05). Significant positive correlations were found between: the FHI and the inclination of the molars; the FHI and the thickness of the cortical bone; and the FHI and the height of the mandibular bone.

CONCLUSIONS

The mandibular posterior tooth-alveolar bone complex morphology may be affected by growth patterns.

Comparison of arch width, alveolar width and buccolingual inclination of teeth between Class II division 1 malocclusion and Class I occlusion

Objective:

To compare the arch width, alveolar width, and buccolingual inclination of maxillary and mandibular posterior teeth between Class II division 1 malocclusion and Class I occlusion.

Materials and Methods:

Forty-five subjects with Class I occlusion and 45 subjects with Class II division 1 malocclusion were selected to measure the maxillary and mandibular arch width and alveolar width of premolars and first molars with digital caliper. Buccolingual inclination of maxillary and mandibular premolars and first molars were measured with a modified universal bevel protractor.

Results:

All of the posterior teeth in both groups were lingually tilted. The maxillary premolars and first molars were significantly more lingually tilted (P &lt; .05) in Class II division 1 malocclusion than in Class I occlusion. Mandibular first premolars were significantly less lingually tilted in Class II division 1 malocclusion than in Class I occlusion. No significant difference of buccolingual inclination was found in mandibular second premolars and first molars between the two groups. No significant difference in maxillary and mandibular arch width and alveolar width was found between the two groups.

Conclusions:

Buccolingual inclination rather than arch width and alveolar width plays an important role in transverse discrepancy of Class II division 1 malocclusion.

Upper Incisor Position and Bony Support in Untreated Patients as Seen on CBCT

Objective: To test the null hypothesis that there are no correlations between the morphology of the upper jaw, the position of the upper incisors, and facial type.

Materials and Methods: From a sample of 191 patients, the FMA angle was used to select 20 short face type, 20 norm face type, and 20 long face type patients, aged 12 to 40 years. Using cone-beam computed tomography (CBCT), tomography was carried out on sagittal sections corresponding to the four upper incisors. Some parameters defining the dentoskeletal relationships, the alveolar thickness, the alveolar height, and the dental movement were measured. The measurements were processed using analysis of variance and Tukey's test.

Results: At the upper central incisors, short face type patients presented a greater alveolar bone thickness than long face type patients. In short face type and norm face type subjects the root apex of the upper incisors was farther away from the lingual cortex than in the long face type patients. At the central incisors the alveolar thickness was greater and the lingual cortex was higher with respect to the lateral incisors in all three facial types.

Conclusion: At the upper incisors, facial type is statistically significantly correlated with both alveolar bone thickness and distance between the root apex and lingual cortex.