Nonextraction treatment of severe Class II, Division 2 malocclusions. Part 1

Torque recovery of the maxillary incisors with a modified double J retractor in a Class II division 2 case treated with clear aligners

A patient with a Class II division 2 malocclusion is presented, illustrating the application of a modified double J retractor (DJR) and palatal miniscrews along with clear aligners to correct the malocclusion and normalize the incisor torque. In terms of incisor torque recovery, a nonextraction approach might be a good choice if the Class II correction could be successfully achieved with total arch distalization. When maxillary molar distalization was limited by anatomical boundaries, the treatment plan was changed to bilateral maxillary first premolar extractions, which led to even more retroclination of the maxillary incisors after space closure. Anterior interdental miniscrews were used to intrude the maxillary incisors. A modified DJR and palatal miniscrews were used to regain torque and achieve palatal root movement of the maxillary incisors. The treatment effects and biomechanical designs were evaluated for torque recovery of the retroclined maxillary incisors.

Effect of proclination of the upper incisors on Point A in adult Class II division 2 individuals: A cephalometric study

Objectives:

The study aimed to identify and evaluate changes in the cephalometric position of Point A due to an incisal inclination change caused by orthodontic treatment in non-growing Class II division 2 patients.

Material and Methods:

A total of 24 pairs of consecutive pre-treatment and post-treatment lateral cephalograms were systematically collected from the departmental database and hand traced. The total change in the position of Point A was investigated by superimposing pre-treatment and post-treatment lateral cephalograms at a stable basicranial line. The treatment changes in maxillary incisor inclination, the sagittal position of Point A, SNA angle, movement of incisor root apex, and incisal edge were calculated.

Results:

The mean SNA angle was reduced significantly suggesting that the A point had moved backward solely due to orthodontic remodeling. Point A distance to true vertical was reduced significantly (mean 1.2 mm), suggesting that local remodeling has occurred due to orthodontic treatment. The incisal edge also moved forward significantly (mean 2.6 mm). The apex of the upper incisor moved significantly backward as a result of its counterclockwise rotation (mean 3.2 mm). The upper incisor to palatal plane values also showed a highly significant change in inclination of the upper incisors (mean 12.30).

Conclusion:

Counter-clockwise rotation of the upper incisor causing its root apex to move more palatally makes remodeling changes in Point A in the form of its retraction roughly by one-third the amount of the backward movement of the upper incisors’ root apex. Moreover, it can be inferred that the retraction of Point A in millimeters will roughly be equal to the reduction in SNA angle in degrees.

MKG Angle: A True Marker for Maxillomandibular Discrepancy

Aim: To evolve a new cephalometric estimation called the MKG angle using three skeletal landmarks—point key ridge (KR), point M, and point G to evaluate the sagittal relationship between the maxilla and mandible.

Materials and methods: A total of 60 pretreatment lateral cephalograms were selected and segregated into classes I, II, and III groups on the basis of ANB angle, Wits appraisal, and W angle. The MKG angle was constructed between the lines drawn from point M to point KR and point KR to point G. The MKG angle was measured to calculate the mean and the standard deviation.

Results: After using the one-way analysis of variance and the Newman–Keuls test and running ROC curves, the results showed that an MKG angle in the range 51º–59º can be considered to have a class I skeletal pattern. The MKG angle more than 59º indicates a class II skeletal pattern and less than 51º indicates class III skeletal pattern.

Conclusion: The MKG angle can be used as a dependable marker to assess sagittal jaw discrepancy.

Changes in lips, cheeks and tongue pressures after upper incisor protrusion in Class II division 2 malocclusion: a prospective study

Background

The etiology of Class II division 2 (CII/2) malocclusion focuses on heredity; however lip, cheek, and tongue pressures that are associated with the environmental effect are considered to have an effect. The aim of this study was to evaluate the relation between perioral pressures and the upper incisor inclination in CII/2 malocclusion.

Methods

Twenty patients (8 females, 12 males; mean age 10.29 ± 0.90 years) with CII/2 malocclusion were included in the study group, and 15 patients (5 females, 10 males; mean age 10.56 ± 1.06 years) with Class I malocclusion were included. The upper incisors were protruded with a utility arch (0.016 × 0.022 in. blue elgiloy wire). Perioral pressure assessment was made with the Iowa Oral Pressure Instrument. Upper lip pressure, lower lip pressure, vertical lip pressure, left-right buccal pressures, swallowing, and maximum tongue pressures were measured. Repeated measure ANOVA was used to test the intragroup differences. Intergroup comparisons were made using two-way repeated measure ANOVA with Bonferroni correction. Relationships between the variables were analyzed using rank correlation (Spearman’s rho). The significance for all statistical tests was predetermined at p < 0.05.

Results

A significant change occurred in the upper lip pressure, lower lip pressure, and vertical lip pressure; however, significant difference was not found between the groups. Upper lip pressure increased significantly in both groups. In the CII/2 group, lower lip pressure increased after protrusion and decreased after retention, while vertical lip pressure decreased and then increased significantly. Left buccal pressure changes between the groups were not parallel. Right buccal pressure, swallowing, and maximum tongue pressure changes were not statistically significant. Statistically significant correlation was found between U1-NA (mm) and vertical lip pressure (r −0.467).

Conclusions

In the CII/2 group, upper lip pressure increased only in retention. Lower lip pressure increased and vertical lip pressure decreased after protrusion. Nevertheless, these changes did not remain stable after the retention period. The difference between groups was not statistically significant at the end of retention.

Association of dentoskeletal morphology with incisor inclination in angle class II patients: a retrospective cephalometric study

Introduction

The purpose of this study was to identify possible dentoskeletal parameters associated with variation of anterior tooth inclination in Angle Class II subdivisions.

Methods

Pre-treatment lateral radiographs of 144 Class II patients (68 males, 76 females) aged 9 to 17 years were classified for upper incisor inclination into three groups (proclined, normally inclined, retroclined) homogeneous for gender and skeletal jaw relationship. The effect of age on the 22 cephalometric variables was controlled by covariance analysis.

Results

Multivariate analysis of the cephalometric parameters indicated significant inter-group differences. Systematic associations with incisor inclination were revealed using rank correlation: Lower incisor proclination, Wits appraisal and gonial angle significantly decreased (0.04 ≥ p ≥ 0.002), while intercisal angle, mandibular total and corpus length and nasolabial angle increased (0.04 ≥ p ≥ 0.001) with decreasing incisor proclination.

Conclusions

Clear-cut classification criteria and control of confounding effects may clarify conflicting previous findings on dentoskeletal differences between Class II subdivisions in the mixed dentition. Only minor dentoskeletal differences appear to be associated with incisor inclination. The increased interincisal and nasolabial angle in Class II division 2 subjects are due to reclination of both upper and lower incisors. Jaw positions and chin prominence are not significantly different between the subdivisions. However, Wits appraisal is decreased in Class II division 2. The increased mandibular length observed in Class II division 2 requires further scrutinization.

A new approach of assessing sagittal dysplasia: the W angle

In orthodontic diagnosis and treatment planning, an accurate antero-posterior measurement of jaw relationships is critically important. Previously described angular and linear measurements can be inaccurate because of their dependency on various factors. The purpose of this study was to introduce a new cephalometric measurement, named the W angle, to assess the sagittal relationship between maxilla and mandible with accuracy and reproducibility. This angle uses three skeletal landmarks--point S, point M, and point G--to measure an angle that indicates the severity and the type of skeletal dysplasia in the sagittal dimension. One hundred and forty-two pre-treatment cephalometric radiographs of patients between the age of 15 and 25 years were selected. They were again subdivided into Classes I, II, and III groups on the basis of Beta angle, Wits appraisal, and ANB angle. The W angle was measured between the perpendicular from point M on S-G line and the M-G line. The mean and the standard deviation for the W angle were calculated. After using the one-way analysis of variance and the Newman-Keuls test, receiver operating characteristics curves were obtained. Results showed that a patient with a W angle between 51 and 56 degrees can be considered to have a Class I skeletal pattern. With an angle less than 51 degrees, patients are considered to have a skeletal Class II relationship and with an angle greater than 56 degrees, patients have a skeletal Class III relationship.

Maxillary incisor proclination effect on the position of point A in Class II division 2 malocclusion

OBJECTIVE

To test the hypothesis that the magnitude of alteration in the position of point A is not associated with proclination of the upper incisors in Class II division 2 malocclusion.

MATERIALS AND METHODS

Cephalometric films were taken for 30 Class II division 2 patients (8 males and 22 females; average age, 18.3 years) before and after upper incisor proclination. The total change in the position of point A was measured by superimposing the pretreatment and postproclination lateral cephalograms on the sella-nasion line at the sella. To determine the local effect of alveolar bone remodeling associated with upper incisor proclination on the position of point A, postproclination tracing of the maxilla was superimposed on the pretreatment tracing according to the Bolton template of maxillary superimposition.

RESULTS

The total vertical displacement in Point A position was downward by 0.84 mm (P = .002), and the total horizontal displacement was forward by 0.45 mm (P = .054). Assessment of local changes in point A revealed that the position of point A had moved backward by 0.60 mm (P = .001). No significant change was observed in the value of the sella-nasion-point A angle (SNA).

CONCLUSION

The hypothesis is rejected. The position of point A is affected by local bone remodeling associated with proclination of the upper incisor in Class II division 2 malocclusion, but this minor change does not significantly affect the SNA angle.

Anteroposterior and Vertical Components of Class II division 1 and division 2 Malocclusion

Objective: To describe and analyze the skeletal and dental characteristics associated with Class II division 1 (Class II/1) and Class II division 2 (Class II/2) malocclusions in the anteroposterior and vertical dimensions.

Materials and Methods: A total of 551 lateral cephalograms were used; 293 films of Class II/1 and 258 films of Class II/2 malocclusions. Lateral cephalographs were traced and analyzed. Parameters for both malocclusions were compared with each other and with the norms calculated for the Jordanian population in another study.

Results: The maxilla was prognathic in both malocclusions. The mandible was retrognathic in Class II/1 and orthognathic in Class II/2. Vertically, LAFH was significantly reduced in patients with Class II/2 compared with subjects with Class II/1 who exhibited a significantly increased LAFH. In Class II/1, the lower incisors were proclined and the interincisal angle was reduced, while in Class II/2 the lower incisors were at a normal inclination and the interincisal angle was significantly increased.

Conclusions: Class II/2 may be considered as a separate entity which differs in almost all skeletal and dental features from Class I and Class II/1. A Class II skeletal pattern and reduced interincisal angle were common features of Class II/1 malocclusion, while a Class II skeletal pattern, increased interincisal angle, and skeletal deep bite were common features of Class II/2 malocclusion.

Dentoskeletal morphology in children with Deckbiss

A comparison of dentoskeletal morphology in 176 Deckbiss malocclusions with Class I molar relationship (Class I/2) and 156 Deckbiss malocclusions with Class II molar relationship (Class II/2) was performed using lateral cephalometric radiographs. Children at the ages of 8 to 10 years and 11 to 13 years were evaluated. The results of the study revealed broad variations in the variables analysed. A relatively short lower face and an obtuse interincisal angle were the only consistent features of the Deckbiss (Class I/2 and Class II/2). Otherwise the dentoskeletal morphology of the Deckbiss was untypical. When comparing the Class I/2 and Class II/2 samples the following morphological traits were more pronounced and/or more frequent in the Class II/2 sample: 1. mandibular retrusion, 2. skeletal Class II jaw base relationship, 3. mandibular plane angle reduction, 4. jaw base hypodivergency, and 5. upper incisor retroclination. Lower incisor retroclination, on the other hand, was more pronounced and more frequent in the Class I/2 sample. Age affected exclusively the Class I/2 sample: maxillary and mandibular retrusion were seen more frequently in the younger than in the older subjects.