Buccolingual Inclination Research Articles

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

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

Transverse dentoalveolar development in Chinese children and adolescents: A cross-sectional study using revised Andrews’ Element III analysis

This study investigated the prevalence of maxillary transverse deficiency (MTD) in Chinese children and adolescents using revised Andrews' Element III analysis and studied transverse developmental characteristics of the maxillomandibular complex. Plaster or digital casts of 794 participants aged 7-18 years were evaluated. MTD was diagnosed when the maxilla-mandible width difference, represented by the decompensated maxillary and mandibular first molars, exceeded 4 mm. The average prevalence of MTD among patients aged 7-18 years was 31.1%. Patients with MTD exhibited narrower maxillary and/or wider mandibular arches. Strikingly, 32.3% of participants with posterior crossbite because of local crowding or mandibular deviation were not diagnosed with MTD. Dental compensation, such as a greater buccolingual inclination of the first molars, was common in patients with MTD. Transverse growth of the maxillomandibular complex was completed by 17 years old, with the maxilla undergoing greater transverse growth than the mandible. The physiological buccolingual inclination of first molars was observed in patients without MTD. The 95% reference value of the palatal arch width was 31.9-42.3 mm. The prevalence of MTD is 31.1% among Chinese children and adolescents. However, it is often camouflaged by dental compensation and sagittal discrepancy. The etiology of MTD is uncoordinated width in the maxillomandibular complex, which is not solely attributed to a narrow maxilla but also to an excessively wide mandible. To enhance diagnostic accuracy, individualized measurements of the maxillomandibular complex and a revised dental decompensation formula, rather than posterior crossbite alone, are recommended for transverse diagnosis. A potential presence of MTD is indicated when the palatal arch width is<31.9 mm.

Comparison of dental movements in digital setups created by orthodontists and “3shape design service®” engineers: A cross-sectional study

The demand for faster and invisible orthodontic treatments has led to the increased use of clear aligners, facilitated by advancements in digital treatment planning. This study aims to evaluate the reliability of digital orthodontic setups performed by orthodontists compared to those by 3Shape Design Service®engineers. A monocentric, cross-sectional observational study was conducted at Bretonneau Hospital from October 2022 to May 2023. All patients meeting the inclusion criteria and willing to participate were included in the study. Intraoral scans were used to create treatment setups using the Ortho System® software, performed by both orthodontists and 3Shape® engineers. The primary objective was to compare the dental movements (rotation, intrusion, extrusion, buccolingual inclination, tipping, mesiodistal translation and buccolingual translation) between the two groups. Secondary objectives included the number of teeth displaced, aligners needed, interproximal enamel reduction and number of attachments placed. Nineteen patients with mild to moderate malocclusion were included. Statistically significant differences were found in tooth displacements between the two groups with engineers executing greater dental movements for derotation (4.9±2.6 vs. 3.7±2.3), tipping (0.79±0.69 vs. 0.26±0.44), bucco-lingual (0.40±0.26 vs. 0.08±0.11) and mesio-distal translations (0.31±0.20 vs. 0.20±0.17). Secondary measures showed no significant differences except for the number of teeth displaced (15.32±5.21 vs. 9.68±4.82), which was higher in the 3Shape group. While digital setups by engineers showed more significant tooth movements, the practical impact on mild malocclusion treatment was minimal. This study highlights the need for precise treatment objectives and consideration of overcorrection practices. For mild malocclusions, outsourcing setups to 3Shape engineers can be an alternative to in-office setups by orthodontists. However, further studies are needed to evaluate setup reliability for more complex malocclusions.

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

BackgroundTo 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 methodsPre-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.ResultsNo 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).ConclusionThe 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.

Comparative evaluation of buccolingual inclination of molars in low-angle cases and high-angle cases using manual technique- A pilot study

The general feature of occlusal curvature, when viewed from the front, consists of a buccal inclination of the maxillary molars and a lingual inclination of the mandibular molars. The fourth key of Andrew’s six keys of occlusion is related to the curve of Wilson, describing the posterior inclination of the crowns of the lower posterior teeth as a concave curve, setting the molars with a lingual torque. Facial skeletal characteristics of subjects with a vertical growth pattern include increased total face height, especially the lower anterior face height, high mandibular plane angle, clockwise mandibular rotation, short mandibular ramus, and high gonial angle. Opposite aspects are present in subjects with a horizontal growth pattern. This study aimed to measure the buccolingual inclination of maxillary first molars in low-angle and high-angle cases using a manual technique. 20 subjects with permanent dentition were divided into 2 groups. Group I comprises 10 subjects with a low-angle case (proportionally short lower anterior facial height) and group II with a high-angle case (proportionally long lower anterior facial height). The buccolingual inclination of 1st molar was assessed on model casts.The maxillary posterior teeth of subjects with a vertical growth pattern (group II) had a significantly greater buccal inclination compared with those of subjects with a horizontal growth pattern (group I).

Enhanced pendulum appliance utilizing temporary anchorage device-based Nance arch and modified springs for optimized molar distalization control: a case report.

A 20-year-old female patient with severe maxillary crowding and skeletal Class III malocclusion was successfully treated using an enhanced pendulum appliance. Camouflage treatment was chosen because the patient refused surgical intervention. Detailed examination and analysis revealed that labial inclination of the maxillary anterior teeth could provide the alignment space necessary after tooth extraction in the maxillary arch but it would not be beneficial esthetically and would increase the moment perpendicular to the tooth long axis as well as increase the risk of bone dehiscence. Therefore, lingual inclination of the mandibular anterior teeth was performed. To create space for aligning the maxillary arch, an enhanced pendulum appliance was utilized, in addition to premolar extraction. The enhanced pendulum appliance had one mesial and one distal helix on each spring, exerting opposing forces in the buccolingual direction and reducing the buccolingual inclination of the molars. In addition, miniscrews were integrated into the Nance arch of the enhanced pendulum appliance to provide skeletal anchorage, minimizing the reciprocal movement of anchorage teeth. This modification not only enhanced control over tooth movement but also improved treatment efficiency. During the entire treatment duration of 17 months, substantial improvement in facial and occlusal aspects were noted. Additionally, the patient retained these positive changes until the subsequent 2-year follow-up period.

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.

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

BackgroundThis study aimed to investigate the differences in the buccolingual inclination and transverse width of maxillary and mandibular first molars among different vertical facial types. MethodsIn 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. ResultsThe 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). ConclusionsThe 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.

Clinical expression of programmed maxillary buccal expansion and buccolingual crown inclination with Invisalign EX30 and SmartTrack aligners and the effect of 1-week vs. 2-week aligner change regimes: A retrospective cohort study.

: This retrospective cohort study aimed to assess and compare the accuracy of 3 different Invisalign® treatment regimens in terms of variations of aligner change frequency and type of aligner material in achieving maxillary dental buccal expansion. : Altogether, 120 adult patients whose treatment involved maxillary dental expansion with Invisalign® were included. The patients were divided into 3 groups, with each group comprising 40 patients as follows: SmartTrack® 1-week changes (ST1), SmartTrack® 2-week changes (ST2), and EX30® 2-week changes (EX2). The groups were assessed by comparing actual changes achieved with those prescribed by ClinCheck®. The rates of clinically significant inaccuracies (CSI) observed for buccal expansion (≥ 0.5 mm) and buccolingual inclination (≥ 2°) during expansion were then determined. : In terms of expansion, the ST1 group demonstrated the highest CSI rate at all tooth levels, whereas the ST2 group had the lowest rate of CSI and the lowest mean inaccuracy for each tooth level. In terms of buccolingual inclination, the ST1 group had the highest CSI rate across all tooth levels, whereas the EX2 group had the lowest CSI rate at all tooth levels except for the canine level where the ST2 group had the lowest CSI rate. A tendency toward overexpression of buccal crown inclination, and underexpression of buccal expansion was observed at all tooth levels. : Two-week aligner change regimens offer improved accuracy compared with 1-week aligner changes. SmartTrack® 2-week changes were the most accurate for buccal expansion, whereas EX30® 2-week changes were the most accurate for buccolingual inclination.

Evaluation of maxillary dimensional changes in the mixed dentition: clear aligners vs acrylic expanders.

To compare changes in upper arch dimension and molar inclination between Invisalign First (IF) and removable acrylic expander (RE) treatments during the mixed dentition period. Seventeen patients meeting inclusion criteria underwent IF treatment and were age matched with a group that received treatment with a removable acrylic expander (RE). Intercanine width (ICW), intermolar width, arch depth, buccolingual inclination of the first molars (MI), surface area (SA) and volume (VAP) of the anterior palate, and expansion were compared before and after treatment. The predictability of expansion was calculated for the IF group. Analysis of variance and Kruskal-Wallis tests were used to assess differences. The ICW increased significantly by 2.14 mm in the IF group and 3.49 mm in the RE group, with no significant intergroup difference. Both groups exhibited significant increases in intermolar width (P < .05), except for intermolar distopalatal width in the IF group (P = .246). Mesiobuccal rotation of the first molar was observed with IF treatment. Although SA and VAP increased in both groups, the changes were not significant for the IF group (P > .05). The RE group exhibited significantly higher increases (P < .05), with an SA increase of 34.32 mm2 and VAP increase of 119.15 mm3. MI changes were in the opposite directions. The prediction accuracy of expansion was 70.28% for canines and 34.12% for first molars. Both appliances effectively expanded the intercanine region in growing patients. Expansion predictability was lower in first molars than in canines for the IF group. Removable acrylic expanders could be a choice of preference for expansion targeted to the molar region.

A Hypothesis Testing of Archwire Rounding for the Efficacy of Torque Springs in Orthodontics: A Finite Element Study.

Achieving the proper buccolingual inclination of teeth is a cornerstone in orthodontic treatment, directly impacting the attainment of ideal occlusal relationships and long-term stability. A practical torque expression that moves the tooth in its proper position across all three planes is imperative to finish orthodontic cases optimally. The primary focus of this research is to investigate Burstone's hypothesis about Warren torque springs when applied to the rectangular wire. Additionally, it examines the hypothesis of rounding these wires in between the bracket wings of the target tooth to be moved. This study aims to determine whether the rounding of wires, in conjunction with the use of torque springs, influences orthodontic outcomes, addressing a notable gap in current literature and resolving controversies in orthodontic practice. A three-dimensional set of maxillary teeth was modeled. A 0.022" MiniSprint™ brackets and Stainless steel archwires of 0.019" × 0.025" and 0.017" × 0.025" (Forestadent, Pforzheim, Germany) were generated. Warren torque spring was modeled and used in the simulation on the upper right central incisor. Four case scenarios were simulated. In two scenarios, the archwires were untouched for both archwire sizes. In comparison, in the other two scenarios, each archwire size was rounded for the upper right maxillary incisor bracket area. Stresses in the Warren torque springs were calculated, the root tip displacement in the four scenarios was measured in millimeters, and both were analyzed. The root tip displacement was highly affected by rounding the archwire. The increase in root tip displacement was 1538% for the Warren torque spring on 0.019" × 0.025" and 783% for 0.017" × 0.025". The amount of root tip displacement was about 18.8 mm for 0.017" × 0.025" with rounding and 12.2 mm for 0.019" × 0.025". The concentration of the stresses in the Warren torque spring was in the neck of the spring next to the coils. Rounding the archwires while using the Warren torque spring on a rectangular archwire will increase the efficiency of the spring and, in turn, will exhibit more torque on the tooth. Smaller dimensions of rectangular archwires will give more torque in conjunction with Warren torque springs compared to larger sizes of archwires.

Correlation between Cleft Width and Adjacent Teeth Inclination in Patients with Unilateral Cleft Lip and Palate Using CBCT: A Retrospective Study.

To evaluate buccolingual and mesiodistal inclination of cleft-adjacent maxillary permanent central incisors (U1) and canines (U3) in patients with unilateral cleft lip and palate (UCLP) in the late mixed dentition and to investigate the correlation between the alveolar cleft width and cleft-adjacent teeth inclination using cone beam computed tomography (CBCT). Observational cross-sectional retrospective study. Department of Orthodontics, Hama University Dental School. 32 patients with UCLP (22 boys, 10 girls; mean age = 10.53 ± 1.51 years). Buccolingual and mesiodistal inclination of maxillary central incisors and canines were measured on both sides. Then, the cleft and non-cleft sides were compared using the Wilcoxon signed-rank test. Pearson's correlation was used to explore the association between the alveolar cleft width and cleft-adjacent U1 and U3 buccolingual and mesiodistal inclination. The cleft-adjacent central incisors were significantly inclined lingually and distally compared with their non-cleft antimeres (P = .003, P < .001, respectively). The cleft-adjacent canines were significantly inclined buccally and mesially compared with their non-cleft antimeres (P < .001, for both). A positive correlation was found between the buccolingual inclination of cleft-adjacent U1 and the alveolar cleft width (r = 0.49, P = .004). Patients with UCLP demonstrated a significant lingual and distal inclination of cleft-adjacent U1 and a significant buccal and mesial inclination of cleft-adjacent U3. The buccolingual inclination of cleft-adjacent U1 tends to increase with increasing the alveolar cleft width; however, the correlation was weak.

Evaluation of digital and manual orthodontic diagnostic setups in non-extraction cases using ABO model grading system: an in-vitro study

BackgroundTo evaluate the outcome quality of manual and digital orthodontic diagnostic setups in non-extraction cases according to the American Board of Orthodontics model grading system and to calculate the laboratory time needed for orthodontic diagnostic setup construction.MethodsThe sample consisted of 60 pretreatment models of non-extraction orthodontic cases with age ranges of 18–30. The study models were duplicated and scanned with 3Shape R-750 scanner. Digital and manual diagnostic setups were constructed according to their respective treatment plans. Digital diagnostic setups were 3D printed and then both manual and digital setups were assessed using the modified American Board of Orthodontics Cast Radiograph evaluation score (ABO CRE), which includes alignment, marginal ridge, buccolingual inclination, occlusal contacts, occlusal relationships, interproximal contacts, and overjet. The laboratory time needed for orthodontic setups was measured in minutes.ResultsThe total ABO CRE score of the digital diagnostic setup group (5.93 ± 2.74) was significantly lower than that of the manual diagnostic setup group (13.08 ± 3.25). The manual diagnostic setup had significantly larger scores in marginal ridge, overjet, overbite, buccolingual inclination, occlusal relationship, and total scores (P < 0.01). However, the digital diagnostic setup had a statistically larger occlusal contacts score than the manual diagnostic setup (P < 0.01). There was no significant difference between the alignment and the interproximal contacts scores in either group. The manual diagnostic setup needed significantly longer laboratory time (187.8 ± 14.22) than the digital setup (93.08 ± 12.65) (P < 0.01). Comparison between broken teeth was performed by using the chi-square test which found no significant difference between different tooth types.ConclusionsDigital diagnostic setup is a reliable tool for orthodontic diagnostic setup construction providing excellent quality setup models. Manual diagnostic setup is time consuming with a technique-sensitive laboratory procedure.

Orthodontic finishing errors detected in board-approved cases: common types and prediction.

To report and rank orthodontic finishing errors recorded in the clinical phase of the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO) examination and correlate pretreatment case complexity with orthodontic treatment outcomes. This single-center cross-sectional survey collected retrospective data from the clinical phase of BBO examinations between 2016 and 2023. The quality of orthodontic clinical outcomes of each case was assessed by means of the Cast-Radiograph Evaluation (CRE), while case complexity was evaluated using the Discrepancy Index (DI), both tools provided by the American Board of Orthodontics. Survey items were analyzed using descriptive statistics, and a correlation analysis between total CRE and DI scores (p<0.05) was also performed. A total of 447 orthodontic records was included. Orthodontic finishing errors were often observed, and no case was completely perfect. In the total CRE score, an average of 15 points was discounted for each case. Most frequently found issues involved problems with alignment, buccolingual inclination, marginal ridge, and occlusal relationship. The median DI score for initial case complexity was 22.0 (range 10.0 - 67.0). There was no significant correlation between the DI and CRE scores (p=0.106). Orthodontic finishing errors are inevitable, even in well-finished board-approved cases. Rotation, excessive buccolingual inclination, and discrepancies in marginal ridges are the most frequently observed areas of concern, in that order. Moreover, while case complexity, determined by DI, can impact orthodontic planning and pose challenges for clinicians, the study did not consider it a determining factor in predicting treatment outcomes.

Tratamento ortodôntico de um paciente com necessidades especiais: um relato de caso

ABSTRACT This report presents the case of an adult patient with mental and intellectual limitations, whose main complaint was dental aesthetics. Dental treatment was performed at the Piracicaba Dental School and approved by the Ethics Committee (CAAE: 65752322.2.0000.5418). Clinically, the patient had inadequacies in the dental arrangement, with periodontal involvement that put the dental elements at risk. In intraoral clinical aspects, the deficiency was identified as maxillary atresia. The buccolingual inclination of the mandibular anterior teeth highlighted the severe crowding and anterior crossing of these teeth. Dental treatment was carried out aiming at the remission of periodontal and orthodontic problems in an integrated manner and with approaches that allowed greater interaction, participation, and patient compliance during treatment. Supra and subgingival scrapings and extraction of the upper left lateral incisor were performed. After three months of periodontal treatment, orthodontic treatment was started with fixed orthodontic appliances. The main objective was to level and align the teeth in both arches to achieve better aesthetic and functional conditions. Due to the COVID-19 pandemic, treatment has been discontinued. This resulted in the regression of the results obtained, including regarding self-care. People with disabilities require dental care with specific strategies for their needs, which must be carried out by a multidisciplinary team. Despite the access limitation imposed by the pandemic, the patient reestablished his motivation to restart treatment, which was facilitated by the bond of trust established between him and the team.

Prevalence and extent of Alveolar dehiscence and fenestration in Class I hyperdivergent subjects with different buccolingual inclinations of maxillary molar teeth

Buccolingual position of teeth could affect the prevalence of alveolar bone defects. Presence of alveolar defects may have a deleterious effect on orthodontic treatment. The aim was to assess the prevalence and extent of dehiscence and fenestration in Class I hyperdivergent subjects and correlate it with buccolingual inclinations(BL) of maxillary first molar teeth. Methods: This retrospective study involved 80 CBCTs of class I hyperdivergent subjects divided into two groups - group A (n=33) buccolingual inclination &gt;9º and group B (n=47) buccolingual inclination &lt;9º. Prevalence and extent of alveolar bone dehiscence and fenestrations were measured in CBCTs using OSIRIX Lite software. Descriptive statistics, Mann Whitney U test and Spearman correlation were done for evaluating intergroup differences and correlation with Buccolingual inclination. Results: Overall prevalence of dehiscence and fenestration in maxillary first molars was 60.95% and 5% respectively. In the buccal alveolar bone, prevalence of dehiscence was highest in group A (84.6%) for 16 and in the lingual alveolar bone prevalence of dehiscence was highest in group B (71.4%) for 26 . On intergroup comparison, the extent of lingual alveolar bone dehiscence (26) in group B was significantly higher (p value &lt;0.05) than in group A. No significant correlation between the extent of dehiscence and fenestration with buccolingual inclination of molar teeth was noted. Conclusion: Molar teeth with BL inclinations of more than 9º had higher prevalence of dehiscence on the buccal side and molar teeth with BL inclinations less than 9 degrees had more dehiscence on the lingual side. But no significant correlation of BL inclination with prevalence and extent of dehiscence and fenestration was noted.

Buccolingual Inclinations of First Molars among Untreated Individuals with Different Facial Pattern: A CBCT Study.

Buccolingual Inclinations of First Molars among Untreated Individuals with Different Facial Pattern: A CBCT Study.

Evaluation of First Molar Buccolingual Angulations and Dental Arch Parameters in Adolescents with Bilateral Posterior Crossbite.

This study aimed to compare the maxillary and mandibular transverse dental arch widths and buccolingual inclinations of the molar teeth in patients with and without bilateral posterior crossbite (BPC) divided into different age groups. The study included dental models from 120 patients (age: 12-18 years), including 60 with BPC (32 boys and 28 girls) and 60 without BPC (controls; 30 boys and 30 girls), who were divided into three age groups (12-14, 14-16, and 16-18 years). The centroid and lingual transverse arch widths, dental arch perimeters, dental arch depths, and buccolingual angulation of the molar teeth in the maxillary and mandibular regions were evaluated using scanned three-dimensional dental models. Dental arch parameters and buccolingual molar angulation did not significantly differ between the different age groups in either the patients with BPC or the controls (p>0.05). However, several dental arch width parameters differed significantly between sexes in both groups, with higher values in boys than in girls (p<0.05). The difference in the upper and lower molar buccolingual angulation between patients with BPC and controls was greater at the age of 16-18 years than the age of 12-14 years (p<0.05). Patients with BPC have smaller maxillary dental arch widths and larger mandibular intermolar widths than those without BPC. The difference in the molar buccolingual angulation between them increases with advancing age.

COMPARING ARCH WIDTH, ALVEOLAR WIDTH ANDBUCCOLINGUAL INCLINATION OF POSTERIOR TEETH IN SUBJECTS WITH CLASS IANDCLASS II MALOCCLUSION

Aim: The aim of this study was to compare the arch width, alveolar width and buccolingual inclination of posterior teeth between Class I and Class II Div 1 malocclusion subjects. Materials and method: A sample of120 subjects (60 males and 60 females) in the age group of 16-19 years with Class I and Class II Div 1 malocclusion were chosen and arch width, alveolar width and buccolingual inclination of posterior teeth were measured and compared between the groups. Result: The maxillary posterior teeth showed more palatal inclination in Class II Div 1 malocclusion when compared with Class I group. Conclusion:Transverse discrepancy in Class II Div 1 might be due to more palatal inclination of maxillary posterior teeth rather than arch width and alveolar width. Hence slow maxillary expansion should be preferred for correcting the palatal inclination rather than rapid palatal expansion.

3D occlusal changes of upper first molars after rapid maxillary expansion on permanent versus deciduous teeth: a retrospective multicenter CBCT study

BackgroundThe purpose of this study was to compare the three-dimensional dental changes for the maxillary first molars and the overall skeletal effects achieved after expansion between the rapid maxillary expansion (RME) appliance attached to two different anchor units, the maxillary deciduous molars and the maxillary permanent first molars.MethodsPatients were retrospectively selected according to the anchorage unit used for RME: deciduous upper second molars (RME-E group; 10 M, 10 F; mean age 8.4 ± 1.1 years) and first upper permanent molars (RME-6 group; 10 M, 10 F; mean age 12.6 ± 1.8 years). CBCT scans were obtained before treatment start (T1) and after retention and removal of the expander (T2). Images were analyzed using a new three-dimensional intra-hemi-maxillary reference system. 3D landmarks were marked to calculate all changes on maxillary first permanent molars; mesio-distal and buccal-lingual inclination and rotation, as well as intermolar and interforaminal distances were calculated. The Wilcoxon test was used to compare within-group changes, whereas the Mann–Whitney test was used to compare between-group differences, with the significance level set at 0.05.ResultsIn the RME-E group, significant distorotation and lingual inclination of the first permanent molars at T2 were observed (p < 0.01); in the RME-6 group, only the buccolingual inclination of the crossbite side after RME was resulted statistically significant (p < 0.01). In both groups, intermolar and interforaminal values increased significantly (p < 0.01). Intergroup analysis showed a significantly higher distorotation and reduced buccal inclination of maxillary first permanent molars in the RME-E group after RME (p < 0.01).ConclusionsRME is effective in treating maxillary transverse hypoplasia; RME anchored too deciduous teeth spontaneously reduces buccal inclination and increases distorotation of maxillary first permanent molars, whereas anchorage to permanent molars is associated with increased buccal inclination, albeit with little clinical significance.