Incisors In Class Research Articles

Non-surgery Treatment with MEAW Technique in Skeletal Class III Malocclusion and Facial Asymmetry in Adults: A Case Report

Background Treating skeletal Class III malocclusions characterized by mandibular deviation, facial asymmetry, and other complex orthodontic issues is among the most demanding orthodontic procedures. Orthognathic surgery is not recommended to everyone due to the dangers involved. Hence, it is considered to be very difficult to correct face asymmetry with orthodontics alone, much less without surgery. Objective The goals of this case study were to decrease crowding in the upper teeth, manage the vertical dimension, and treat the patient's primary complaints of crossbite in the anterior teeth and facial asymmetry. Case Presentation A female patient, aged 21, came in with many concerns, including an incisor crossbite, facial asymmetry, and an insecurity that manifested only when she smiled. An adult patient with a mandibular deviation to the right and an incisor crossbite received orthodontic treatment for these issues. The patient had asymmetric molar extraction in both the lower and upper jaws to retract the lower incisors and correct the midline of the teeth using intermaxillary elastic. Fixed appliances were utilized in conjunction with overbearing lower anterior braces to manage the torque on the lower anterior teeth. As a result, she had a pleasant smile, a harmonious face, and stable dental and skeletal connections. The whole therapeutic period lasted 30 months. As a result, asymmetric molar extraction may be an acceptable option for retracting mandibular incisors in Class III malocclusion with facial asymmetry. Conclusion The most important step in treating the severe skeletal Class III malocclusion in this patient without surgery was to retract the lower arch. After using the MEAW approach, Class III elastics, posterior bite turbos, and orthopedic splint treatment, the patient reported a satisfactory achievement.

Changes in Soft Tissue Variable of Lips Following Retraction of Anterioir Teeth- A Cephalometric Study.

The purpose of this study was to assess the short-term perioral soft tissue variations of the lips before and after treatment cases in 15 patients with bi-maxillary protrusion using treated lateral cephalograms who had already achieved active growth. Fifteen pre-treatment and post-treatment lateral cephalometric radiographs of 18-25-year-old individuals with bimaxillary protrusion treated with all four 1st premolar extractions were accessed from the records. From the reference planes and landmarks, 13 horizontal, 10 vertical, and 2 angular measurements were noted. Statistical comparisons between pre-treatment and post-treatment measurements were measured by a paired t-test to assess the importance of the mean variations at the predetermined significance level. Pearson's correlation coefficient (R) was utilized to assess the strength and significance of the linear relationship between the mean differences for paired (dependent and independent) variables. Pearson's correlation exhibited a noteworthy positive association between the horizontal changes in upper lip position and the horizontal changes of the upper incisor tip point (H-tU1) (R = 0.748), the upper incisor cervical point (H-cU1) (R = 0.707), the lower incisor tip point (H-tL1) (R = 0.839), and the lower incisor cervical point (H-cL1) (R = 0.767). This indicated that upper lip changes are the aftermath of the retraction of the upper and lower incisors in class I bi-maxillary protrusion malocclusion. Thick upper lips showed more retraction of the upper lip in correlation with retraction of the incisors as compared with thin lips. The lower incisor cervical point displayed the strongest association with lower lip retraction.

Comparison of collum angle and labial crown-root angle of maxillary central incisor in Class I and Class II division 2 malocclusion

Introduction: Variation in tooth morphology widely influences the achievement of optimum esthetics and stable occlusal relationship. This study was conducted to compare the collum angle and labial crown root angles in class I, class II division 2 malocclusions, using cephalometric radiographs, and to find a correlation between these angles. Methods: This cross-sectional study was conducted from March 2018 to January 2021 among patients visiting the department of Orthodontics at Gandaki Medical College. A total of 62 lateral cephalograms were included and equally divided into 2 groups: Angle’s Class I and Class II division 2. Cephalometric tracing was done to measure the collum angle and labial crown root of maxillary central incisors. Pearson’s correlation test and independent t-test were used. Results: There was a weak positive correlation (r=+0.348) between the angles in Class I group, (p=0.27) and a moderate positive correlation (r=+0.547) between the angles in Class II division 2 group (p<0.001). The mean collum angle was found to be greater in class II division 2 (11.90±6.86) than in class I (4.51±4.13) which was statistically significant (p<0.001). The mean labial crown root angle was found to be greater in class II division 2 (39.65±8.57) than in class I (30.23±5.20) which was statistically significant (p<0.001). Conclusions: There was no statistically significant correlation between collum angle and labial crown-root angle in class I groups. The mean of collum angle and labial crown-root angle was found to be greater in class II division 2 which were statistically significant in both angles.

Root resorption in Class II malocclusion treatment with and without maxillary premolar extractions

Class II malocclusion treatment efficiency with maxillary premolar extractions has been reported. However, no study evaluated the root resorption associated with this protocol. Therefore, this study aimed to compare the degree of root resorption of the maxillary incisors in Class II malocclusion treatment with and without maxillary premolar extractions. The sample consisted of 56 patients with complete Class II malocclusion, divided into 2 groups. Group 1 comprised 28 patients (10 female, 18 male) treated with maxillary first premolar extractions, and group 2 was composed of 28 patients (16 female, 12 male) treated without extractions. The groups were matched regarding initial age, treatment time, crowding, initial malocclusion severity, finishing quality, initial overjet, and overbite. Periapical radiographs of the maxillary incisors were used to assess the degree of root resorption using a scoring system. In addition, treatment changes involving maxillary incisors were evaluated in lateral headfilms. Intergroup comparisons were performed with t, Mann-Whitney U, and chi-square tests (P<0.05). Overjet, overbite, inclination, vertical positional changes, and vertical and horizontal apical displacements of maxillary incisors were similar between groups. There was no statistically significant difference between groups regarding root resorption of maxillary incisors. Root resorption degree ranged from mild to moderate in both groups. Treating complete Class II malocclusion with 2 maxillary premolar extractions resulted in a similar root resorption as treating without maxillary premolar extractions. An individualized evaluation of root resorption predisposing factors should be performed for each patient.

Comparison of alveolar bone width and sagittal tooth angulation of maxillary central incisors in Class I and Class III canine relationships: a retrospective study using CBCT

BackgroundCanine relationship is a key reference identifying anterior malocclusion and an important implication for evaluating preimplantation bone morphology at maxillary esthetic zone. This study aimed to compare the differences of maxillary central incisor-related measurements (alveolar bone thickness and tooth sagittal angulation) between Class I and Class III canine relationship and further explore the risk factors for immediate implant placement in the anterior maxilla based on cone beam computed tomography (CBCT) data.MethodsCBCT digital imaging and communications in medicine (DICOM) files of 107 patients (54 with Class I canine relationship and 53 with Class III canine relationship) were collected and the alveolar bone thickness at mid-root (mid-root buccal thickness/MBT; palatal/MPT), apical regions (apical buccal thickness/ABT; palatal/APT) and sagittal angulation (SA) of the maxillary central incisor at the examined side were measured on the mid-sagittal observation plane. Descriptive statistical analysis and frequency distributions of the measurements based on Class I or Class III canine relationship were established. Statistical analyses were performed using Fisher’s exact test, independent samples t test and Pearson correlation test with the significance level set at p < 0.05.ResultsThe frequency distributions of maxillary central incisors’ MPT, ABT, APT and SA showed significant differences between Class I and Class III canine relationships (p = 0.030, 0.024, 0.000 and 0.000, respectively). MPT (2.48 ± 0.88 mm vs. 3.01 ± 1.04 mm, p = 0.005), APT (6.79 ± 1.65 mm vs. 8.47 ± 1.93 mm, p = 0.000) and SA (12.23 ± 5.62° vs. 16.42 ± 4.49°, p = 0.000) were significantly smaller in patients with Class III canine relationship. Moreover, SA showed a strong positive correlation with APT (R = 0.723, p = 0.000) and a moderate negative correlation with ABT (R = − 0.554, p = 0.000).ConclusionsIn populations with Class III canine relationship, maxillary central incisors were significantly more labially inclined and have a thinner palatal bone plate at the apex compared with Class I relationship. Clinicians should avoid palatal perforation during immediate implantation at sites of originally protrusive maxillary incisors.

Collum angle of the anterior teeth: A systematic review and meta-analysis.

To assess and evaluate the collum angle (CA) of the anterior teeth of the permanent dentition. A search in seven databases for articles that had measured the CA in sagittal malocclusions was conducted until November 30, 2021. The risk of bias was assessed using the Modified Newcastle Ottawa scale. CA measurements using Cone Beam Computed Tomography or lateral cephalograms were included. The CA data were summarized by random-effects inverse generic meta-analyses. Qualitative analysis of the 17 selected articles revealed that four were rated as "very good," 12 as "good" and 1 as "satisfactory." CA was 4.7° (95% CI of 3.1 to 6.4) and 2.0° (95% CI of 0.1 to 3.9) greater in Class II division 2 and Class III malocclusions respectively, than in Class I malocclusion cases. Majority of the studies were rated as good or very good. Most studies evaluated the CA of the maxillary central incisors in Class II division 2 malocclusion. Studies assessing other maxillary anterior and mandibular anterior teeth are required. Practice of esthetic dentistry for teeth with increased CA is of clinical importance since the angle would determine the longevity and esthetic/cosmetic success of the rehabilitation. Placement of dental implants in areas of missing teeth with increased collum angle leads to excessive stress between the fixture and abutment leading to gingival recession. Thus, knowledge about the collum angle of anterior teeth and its variations in sagittal malocclusions would enable precise treatment planning in the field of esthetic dentistry.

Alveolar bone changes around upper incisors in Class I non extraction patient after orthodontic treatment using cone beam computed tomography

Introduction: The position and movement of incisors play important role in orthodontics. Efficient tooth movement and stable position cannot be ensured without adequate alveolar bone support. The bone loss estimated by traditional radiograph is always less than real bone loss so CBCT is currently best to evaluate bone changes. The purpose of this study was to use CBCT to evaluate and compare changes in alveolar bone thickness and Vertical alveolar bone height around maxillary anterior teeth of Class I malocclusion patient after orthodontic treatment. Materials and Method: Forty patients with Class I occlusion between ages of 12 to 18 years were selected. The cone beam computed tomography (CBCT) and lateral cephalograms were taken before treatment (T0) and after treatment (T1). The lateral cephalograms were used to assess the change in tooth inclination whereas CBCT was used to assess the alveolar bone change. All the data were statistically analyzed using paired sample t-test and independent sample test. Result: Significant changes in alveolar bone thickness and vertical bone height were found on the palatal surface of the anterior teeth compared to that of labial surface with significant change in tooth inclination. Conclusion: Based on the results, we can conclude that the palatal alveolar bone loss and vertical bone loss was greater than that of the labial alveolar bone.

Correlation between collum angle and lower lip position in different Class II malocclusions - A retrospective cephalometric study

ABSTRACT Purpose: Significance of analysing collum angle in class II malocclusions with respect to lip position may lend greater credibility to variable torque brackets (mainly in the anteriors) that are fast gaining traction. Determine the magnitude of collum angle of maxillary central incisors in Class II division 1, division 2 malocclusions and changes in measurement brought about by variations in lower lip position and incisal contact. Materials and methods: 154 lateral cephalograms were divided into three groups- 55(Angle’s class I), 52 (Angle’s class II division 1) and 47 (Angle’s class II division 2). The collum angle was measured along with lower lip line (in Class II division 2) and lower lip contact (in Class II division 1) malocclusions. Results: The mean collum angles were 2.12 ± 1.43°, −0.84 ± 0.87° and 4.67 ± 2.23° in Groups 1, 2, and 3, respectively. Mean collum angle is significantly increased when the lower lip was found to contact the middle-third of the central incisor(in Group 3)and significantly decreased when the anterior one-third of the lower lip was in contact with the incisal edge of the central incisor (in Group 2). ANOVA followed by Tukey HSD test was carried out to determine statistically significant differences (p < 0.05). Conclusion: Collum angle is significantly decreased in Class II division 1 malocclusions necessitating variable torque prescriptions and segmental mechanics of maxillary anteriors. Appropriate alveolar bone support must be assessed prior to en-masse retraction and intrusion respecting the cortical boundaries. KEY MESSAGES: Variable torque brackets are rapidly gaining credence for their ability to provide sufficient alveolar bone support in different clinical scenarios. In this study, we have emphasized upon utilizing similar mechanics to treat class II malocclusions by utilizing the lower lip position as a reference guide.

Mandibular symphysis morphology and lower incisor angulation in different anteroposterior jaw relationships and skeletal growth patterns - a cephalometric study.

ObjectiveThe purpose of the present study was to assess the symphyseal morphology and lower incisor angulation in different anteroposterior relationship and in different growth patterns and to investigate whether the symphyseal morphology had any correlation with dentofacial parameters.MethodRandom Sampling method and lateral cephalograms of 90 subjects, age group 16–30 years, were divided into 30 in each group, i.e. Class I, Class II & Class III after calculating the following parameters (ANB angle, wits appraisal). After that, groups were again divided into 10 in each subgroup i.e. Average, Horizontal and Vertical growers.ResultsResults showed the increase in actual symphysis width, inclination of the alveolar part, total height of symphysis and reduction in overall width along with retroclination of lower incisors in class III subjects as compared to class I and class II. Similarly actual and overall width of the symphysis were decreased and inclination of the alveolar part, symphyseal height and symphyseal ratio were increased in vertical growers.ConclusionThe dimensions and configuration of Mandibular Symphysis in class III was found to be different than those in Class I and Class II relationships; the alveolar part of Mandibular Symphyseal compensated for the skeletal relationship in the Class III pattern. Mandibualr Symphysis dimensions were strongly correlated to anterior facial dimensions. Similarly the dimensions and configuration of Mandibular Symphysis was also different in vertical growers as compared to horizontal and average growers, moreover symphyseal morphology and lower incisor angulation had a correlation with dentofacial parameters.

Canine substitution of congenitally missing maxillary lateral incisors in Class I and Class III malocclusions by using skeletal anchorage

This prospective cohort study aimed to evaluate canine substitution supported by skeletal anchorage as a viable treatment protocol for patients with maxillary lateral incisor agenesis (MLIA) and skeletal Class I or Class III. Patients (n=30) who met the following criteria were recruited: (1) bilateral MLIA or unilateral MLIA with a riziform contralateral incisor with a planned extraction; (2) skeletal Class I or Class III; and (3) dentoalveolar discrepancy in the mandible<5mm. The archwire sequence routine was administered, combined with a rapid palatal expander, temporary intraoral skeletal anchorage device, and intermaxillary traction with Class III elastics. The results of the cephalometric analyses, peer assessment rating indexes, and the patient's smile self-evaluation using the visual analog scale were compared between initial and final treatments. This study indicated that closing the space in patients with Class I or Class III malocclusion by using temporary intraoral skeletal anchorage devices in the mandible, along with Class III elastics, yielded satisfactory outcomes. Proper occlusion was established by mesialization of the maxillary teeth and correction of the intermaxillary discrepancy, thereby yielding beneficial and significant cephalometric changes after the treatment. The soft tissue profile was maintained when it was harmonious before the treatment and improved posttreatment in patients in whom the profile was initially inharmonious. All occlusions improved, as evidenced by the peer assessment rating index. Smile esthetics were also enhanced after orthodontic treatment for all patients. Canine substitution may be safely offered to patients with Class I and Class III skeletal pattern and MLIA.

Three-dimensional evaluation of labial alveolar bone overlying the maxillary and mandibular incisors in different skeletal classifications of malocclusion

The purpose of this study was to investigate differences in the thickness of the labial bone overlying the maxillary and mandibular incisors in class I, II, and III skeletal classifications using three-dimensional cone-beam computed tomographs (CBCT) technology. Pretreatment CBCTs of 54 Caucasian subjects (44 males, 10 females) were collected from the archives of a graduate orthodontic clinic. The subjects were divided into three groups based on their skeletal classification. CBCT scans were oriented to the long axis of each maxillary and mandibular incisor from the root apex to incisal tip and the axial inclination of each incisor was measured and recorded. Labial bone thickness was measured at the apex (A) and at the midpoint (MP) on each maxillary and mandibular incisor. A linear measurement, perpendicular to the long axis, was recorded from the labial bone surface to the most anterior root surface at two points. The effects of skeletal classification, jaw, incisor position, and side on A, MP, and Inclination were evaluated using mixed-model ANOVA. A 5% significance level was used for all tests. Significantly greater bone thickness at the apex and midpoint was reported in class III individuals than class I or II. Central incisors had significantly greater bone thickness at both the root apex and midpoint. Significantly greater bone thickness was noted in the mandible at the level of the apex. At the level of the midpoint, significantly greater thickness was reported in the maxilla. There was a positive correlation between thickness and angle within each jaw-incisor combination for class I patients and for central incisors in class III patients. The thickness of labial alveolar bone over the incisors varies based on the underlying skeletal discrepancy in each patient. Skeletal discrepancy influences the inclination of the maxillary and mandibular incisors.

Analysis of the discrepancy of crown-root morphology of central incisors among different skeletal malocclusion using cone-beam CT

Objective: To investigate the discrepancy of crown-root morphology of upper and lower central incisors in adult patients with different skeletal malocclusions using cone-beam CT (CBCT). Methods: Patients visiting the Department of Orthodontics, College of Stomatology, Xi'an Jiaotong University from January 2015 to December 2017 were selected, including 108 cases (52 males, 56 females, aged from 18 to 30 years, mean age 25.8 years). According to CBCT data and cephalometric analysis, 66 patients with average angle were selected as the sagittal skeletal group, including 24 Class Ⅰ patients, 20 Class Ⅱ and 22 Class Ⅲ patients. In the other selected 66 skeletal Class Ⅰ patients including 21 low angle patients, 24 average angle patients (from the sagittal skeletal Class Ⅰ subgroup) and 21 high angle patients. Invivo 5 software was used to locate the CBCT image three dimensionally and then obtain the middle labio-lingual section of right central incisor. Auto CAD 2007 software was applied to measure the angle formed by the long axis of root and the extension line of the long axis of crown (Collum angle), and the angle between the long axis of crown and the lip tangent line passing through the center of the labial surface of crown (labial surface angle). One-way ANOVA and Scheff were used to analyze the discrepancies among classifications and Pearson correlation analysis was used to determine the correlation between the Collum angles and labial surface angles. Results: Significant differences were found in Collum angles and labial surface angles among different sagittal skeletal patterns (P<0.05). The Collum angle of maxillary central incisors in Class Ⅱ patients was 5.18°±4.97° and the average labial surface angle was 17.78°±3.74°, which were both significantly higher than that of maxillary central incisors in Class Ⅰ and Ⅲ subgroups (P<0.05). Similarly, the above two angles of mandibular central incisors in Class Ⅲ were 5.59°±5.64° and 15.32°±3.05°, which were significantly higher than that of mandibular central incisors in Class Ⅰ and Ⅱ subgroups (P<0.05). There was no significant difference among different vertical skeletal patterns (P>0.05). Notably, the Collum angles of maxillary or mandibular central incisors presented significantly positive correlation with labial surface angles (maxillary: r=0.723, P<0.001; mandibular: r=0.752, P<0.001). Conclusions: The long axis of the crown of the maxillary central incisor in skeletal Class Ⅱ patients and the mandibular central incisor in skeletal Class Ⅲ patients are obviously deviated toward the lingual side relative to the long axis of the root, and correspondingly there is a greater labial surface angle of the crown, which indicates that equivalent positioning deviation during bracket bonding can cause greater torque expression error.

Comparison and Evaluation of Alveolar Bone Around Lower Central Incisors in Class III and Class I Patients

Objectives: The aim was to compare the alveolar bone support of mandibular central incisors in subjects with Class III and Class I skeletal patterns using cone-beam computed tomography (CBCT). Materials and Methods: Group 1 included 20 patients (mean age=19.78±2.80) with Class III malocclusion (mean ANB°=-2.77±3.69), mesofacial growth pattern (FMA°=27.03 ±5.11) and lingual-inclined mandibular incisors (IMPA°&amp;lt;85). Group 2 included 20 patients (mean age=20.85±3.97) with Class I malocclusion (mean ANB°=2.94 ±1.46), mesofacial growth pattern (FMA°=25.67±6.83) and normal inclined mandibular incisors (85&amp;lt;IMPA°&amp;lt;95). Vertical alveolar bone level and alveolar bone thickness (ABT) of total 80 mandibular central incisors (40 from each group) were evaluated. Buccal, lingual and total ABT were measured at the crestal, midroot, and apical levels. Buccal (BACH) and lingual (LACH) alveolar crestal heights were also evaluated. Mann-Whitney U, independent samples-t-tests, and Spearman’s rank correlation analysis were applied for statistical analysis. Results: The lingual ABT at the crestal and midroot level, buccal ABT at the apical level, and total ABT at all levels were significantly lower in Group 1 than Group 2 (p&amp;lt;0.05). There was a negative correlation between the buccal (r=-0.324; p=0.042) ABT at the apical level and mandibular plane angle. The change in mandibular incisor inclination was positively correlated with buccal ABT at the apical level (r=0.463; p=0.003) and lingual ABT at the crestal level (r=0.550;p&amp;lt;0.001). BACH was significantly higher in Group 1 (2.21±1.48 mm) compared to Group 2 (1.42±0.17 mm) (p &amp;lt; 0.05). Conclusions: In subjects with Class III deformities, mandibular central incisors have less bone support especially at the buccal side of the alveolar bone at the apical level and lingual side of the alveolar bone at the crestal and midroot levels. Rate of change in mandibular incisor inclination and mandibular plane angle can be thought as significant factors that may influence alveolar bone thickness.

Comparative tomographic study of the maxillary central incisor collum angle between Class I, Class II, division 1 and 2 patients.

INTRODUCTION:It has been reported that Class II, division 2 maxillary central incisors frequently demonstrate increased collum angles, which indicates an excessive palatal “bend” of the crown. However, evidence supporting such observation is mostly derived from radiographic studies.OBJECTIVE:The objective of this study was to evaluate and compare the collum angle of maxillary central incisors in Class I, Class II, division 1, and Class II, division 2 cases using cone-beam computed tomography.MATERIALS AND METHODS:Forty-eight consecutive orthodontic cases (16 Class I, 16 Class II, division 1, and 16 Class II, division 2 malocclusion) with cone-beam computed tomography as part of their initial diagnostic records were evaluated. Cross-sections including maxillary right and left central incisors were used to calculate the angulation between the crown and root long axes (collum angle). Comparisons between groups were performed using analysis of variance for multiple and post-hoc Tukey for paired analyses.RESULTS:Mean collum angle observed in Class II, division 2 cases was significantly larger (5.2 ± 1.3°) than the ones obtained for Class I (1.1 ± 4.2°) (P = 0.034) or Class II, division 1 cases (0.1 ± 0.7°) (P = 0.014).CONCLUSIONS:Our findings suggest that Class II, division 2 individuals demonstrate accentuated lingual inclination of the maxillary central incisor crown compared to the other types of malocclusion studied here. Such morphological feature indicates the need for better tooth movement planning, especially in regard to root palatal torqueing of the maxillary central incisors.

Rate of intrusion of maxillary incisors in Class II Div 1 malocclusion using skeletal anchorage device and Connecticut intrusion arch

BackgroundNonsurgical correction of deep bite involves either extrusion of posterior teeth, intrusion of incisors, or combination of both. The introduction of skeletal anchorage device with microimplant provides near absolute anchorage without producing any untoward effects on anchor unit. Connecticut Intrusion Arch (CIA) provided an efficient system of intruding anterior segment without producing much adverse affects on anchor teeth. MethodsThe study comprised of 30 patients of Class II Div 1 malocclusion with overbite of >6mm and required therapeutic extractions of all first premolars, randomly distributed into two groups. Group 1 was treated using orthodontic microimplants, while Group 2 treated with CIA. Lateral cephalograms were taken pre-intrusion (T1) and post-intrusion at the end of six months (T2). ResultsThe rate of intrusion was 0.51 and 0.34mm/month for Group 1 and Group 2 respectively. The average amount of change in centroid point to PP distance and U1-SN angle was significantly higher in Group 1 compared to Group 2 (P<0.001). The average amount of change in U6 to PP distance did not differ significantly between two study groups (P>0.05). ConclusionThe amount of intrusion is significantly higher in SAD group. Although vertical molar positional change was higher in CIA group than the SAD group, it was not changed significantly in both treatment modalities. SAD group overall had better results and was easier in handling during intrusion.

Augmented Corticotomy-Assisted Surgical Orthodontics Decompensates Lower Incisors in Class III Malocclusion Patients

To quantitatively evaluate lower incisor decompensation and the surrounding periodontal region after augmented corticotomy-assisted surgical orthodontics in patients with Class III malocclusion. This prospective study enrolled patients with severe Class III malocclusion who underwent augmented corticotomy in the lower anterior region before orthodontic surgery. Cone-beam computed tomograms and lateral cephalograms were obtained before treatment (T0), after presurgical orthodontic treatment (T1), and at removal of the orthodontic surgical appliances (T2). Repeated measures analysis of variance was used to compare variables at each time point: root length (RL), anterior vertical alveolar bone level at the labial side (AVBL), posterior vertical alveolar bone level at the lingual side (PVBL), labial alveolar bone thickness at the apex (LA), lingual alveolar bone thickness at the apex (LP), and angle of the incisor to the mandibular plane (L1-MP). In the 8 subjects studied, RL was maintained from T0 to T2 (P > .05), whereas AVBL and PVBL increased from T0 to T1 (P < .05) and then decreased from T1 to T2 (P < .05). LA and L1-MP increased from T0 to T1 (P < .001) but remained steady from T1 to T2 (P > .05). LP decreased from T0 to T1 (P < .05) but increased from T1 to T2 (P < .05) with no further change. Augmented corticotomy-assisted surgical orthodontics can achieve adequate tooth decompensation with minimal periodontal side-effects in the lower anterior region in patients with Class III malocclusion.

Combined use of miniscrews and continuous arch for intrusive root movement of incisors in Class II division 2 with gummy smile

Adequate intrusion and torque control of the retroclined maxillary incisors are critical for the treatment of Class II division 2 (div2) malocclusion. In addition, anterior retraction via lingual root movement can be challenging. This case report demonstrates a combined use of miniscrews and continuous arch with additional torque for intrusion, retraction, and torque control of maxillary incisors in the Class II div2 with gummy smile. A 20-year-old woman presented with multiple issues, including impacted canine, lip protrusion, prolonged retained mandibular primary molar, and two missing maxillary premolars. In order to improve her facial profile and eliminate the need for prosthetic work, the mandibular primary molar and contralateral premolar were extracted. Two miniscrews were placed at the maxillary buccal alveolar bone to apply the posterosuperior force for retraction of anterior teeth, with additional labial crown torque on the arch wire. The results were the intrusion (4 mm) and lingual root movement (17°) of the maxillary incisors without anchorage loss of maxillary molars, flattening of the Curve of Spee, and Class I molar relation that were maintained after 50 months of retention period. The combined use of miniscrews and continuous arch could be a reliable and effective treatment modality for torque control and intrusion of retroclined maxillary incisors in the Class II div2 patient.

How much incisor decompensation is achieved prior to orthognathic surgery?

Objectives: To quantify incisor decompensation in preparation for orthognathic surgery. Study design: Pre-treatment and pre-surgery lateral cephalograms for 86 patients who had combined orthodontic and orthognathic treatment were digitised using OPAL 2.1 [http://www.opalimage.co.uk]. To assess intra-observer reproducibility, 25 images were re-digitised one month later. Random and systematic error were assessed using the Dahlberg formula and a two-sample t-test, respectively. Differences in the proportions of cases where the maxillary (1100 +/- 60) or mandibular (900 +/- 60) incisors were fully decomensated were assessed using a Chi-square test (p<0.05). Mann-Whitney U tests were used to identify if there were any differences in the amount of net decompensation for maxillary and mandibular incisors between the Class II combined and Class III groups (p<0.05). Results: Random and systematic error were less than 0.5 degrees and p<0.05, respectively. A greater proportion of cases had decompensated mandibular incisors (80%) than maxillary incisors (62%) and this difference was statistically significant (p=0.029). The amount of maxillary incisor decompensation in the Class II and Class III groups did not statistically differ (p=0.45) whereas the mandibular incisors in the Class III group underwent statistically significantly greater decompensation (p=0.02). Conclusions: Mandibular incisors were decompensated for a greater proportion of cases than maxillary incisors in preparation for orthognathic surgery. There was no difference in the amount of maxillary incisor decompensation between Class II and Class III cases. There was a greater net decompensation for mandibular incisors in Class III cases when compared to Class II cases. Key words:Decompensation, orthognathic, pre-surgical orthodontics, surgical-orthodontic.

Effects of crown-root angle on stress distribution in the maxillary central incisors’ PDL during application of intrusive and retraction forces: a three-dimensional finite element analysis

BackgroundDifferent crown-root angulations of maxillary central incisors can be assumed as a potential reason for many underscored outcomes of orthodontic treatments. The aim of this study was to determine the effects of the different crown-root angles on stress distributions in the maxillary central incisor’s periodontal ligament (PDL) during application of intrusive and retraction forces using a 3D finite element method.MethodsTwo models of a maxillary central incisor were constructed using ANSYS software: the first one with an angle of 166.7° (as a sample of the maxillary central incisor in a class II, division 2 patient) and the other one with an angle of 173.4° (normal angulation). Each of the samples was loaded twice by an intrusive force (0.25 N) and a retraction force (0.5 N) through the ideal position of brackets.ResultsFEM results showed little difference between stress distributions in the two models during intrusion (ten thousandth) compared to retraction (thousandth). In the application of retraction force, the stress concentration on the curved tooth was less than the other.ConclusionTo produce similar patterns of stress in the PDL, orthodontists can apply 1.18 times heavier retraction forces on the maxillary central incisors in class II, division 2 patients compared to class I patients.

Relationship between crown-root angulation (collum angle) of maxillary central incisors in Class II, division 2 malocclusion and lower lip line

The present study aimed to measure the magnitude of the collum angle (crown-root angulation) of maxillary central incisors present in Class II, division 2 malocclusion and to relate the changes in its magnitude with variations in the lower lip line. A set of 120 conventional lateral cephalograms were selected and divided into three groups of 40 each based on the type of malocclusion presented: Class II, division 2 (group 1); Class II, division 1 (group 2); and Class I (group 3). The collum angle of the maxillary central incisor was measured, and the lower lip line was recorded. Analysis of variance (ANOVA) revealed that the mean collum angle was statistically significantly different in the three groups. The mean collum angle was greatest in Class II, division 2 malocclusion (group 1). The mean collum angles were 3.24 ± 4.69 degrees, 0.95 ± 1.06 degrees, and 1.05 ± 1.50 degrees in groups 1, 2, and 3 respectively. In χ ² test comparison of the location of the lower lip line (incisal, middle, or apical third of the central incisor) among the three groups, the lower lip line was found to contact the middle third of the central incisor most frequently in Class II, division 2 malocclusion. ANOVA followed by Tukey honestly significant difference (HSD) test showed that the mean collum angle is significantly increased when the lower lip is in the middle third (P < .05) of the central incisor. Variations in magnitude of the collum angle with the change in the lower lip line suggest a probable etiologic role of the lower lip line in the development of the collum angle.