Cephalometric assessment of the axial inclination of upper and lower incisors in relation to the third-order angle

A digitalized analysis of incisal changes among orthodontically treated patients: A retrospective comparative study

Background

To compare incisor angulation and/or position changes among orthodontically treated patients with metal brackets and clear aligners.

Methods

A total of sixty-two participants of both sexes, aged-16-40 years old, with CL I skeletal pattern and mild crowding following strict eligibility criteria were included. The patients were divided into two groups based on their treatment approach. Pre and post lateral cephalograms were collected from Riyadh Elm University (REU) and then digitally analyzed using WEBCEPH (Medical Image Analysis) software. Eight angular and two linear measurements were used for the assessment.

Results

The upper incisor angulation and position showed statistically significant differences when orthodontic clear aligners were used. In contrast, no significant difference was observed with the conventional orthodontic treatment. However, the upper incisal palatal root torque decreased after clear aligner therapy compared to conventional treatment. The inter-incisal angle demonstrated a significant increase with clear aligners compared to conventional treatment.

Conclusions

The current study revealed the importance of definitive guidelines upon and after treatment, in addition to determining incisor changes. Orthodontic clear aligners are distinct from conventional treatments in controlling the incisors' angulation and position. The expansion treatment modality precedes Interproximal reduction in increasing the arch perimeter.

XGBoost-aided prediction of lip prominence based on hard-tissue measurements and demographic characteristics in an Asian population

INTRODUCTION

Prediction of lip prominence based on hard-tissue measurements could be helpful in orthodontic treatment planning and has been challenging and formidable thus far.

METHODS

A machine learning-based cross-sectional study was conducted on 1549 patients. Hard-tissue measurements and demographic information were used as the input features. Seven popular machine learning algorithms were applied to the datasets to predict upper and lower lip prominence. The algorithm that performed the best was selected for the construction of the prediction model. Evaluation of feature importance was conducted using 3 classical methods.

RESULTS

Among the 7 algorithms, the XGBoost model performed the best in the prediction of the distances between labrale superius or labrale inferius to the esthetics plane (UL-EP and LL-EP distances), with root mean square error values of 1.25, 1.49 and r2 values of 0.755 and 0.683, respectively. Among the 14 input features, the L1-NB distance contributed the most to the prominences of the upper and lower lips. A lip prominence predictor was developed to facilitate clinical application by deploying the prediction model into a downloadable tool kit.

CONCLUSIONS

The XGBoost model performed well with high accuracy and practicability in predicting upper and lower lip prominence. The artificial intelligence-aided predictor could serve as a reference for orthodontic treatment planning.

Clinical implementation of axial angulation of incisors in the course of routine fixed appliance treatment - a retrospective cohort study

PURPOSE

To identify clinically relevant factors for changes in axial angulation of incisors during routine fixed appliance orthodontic treatment.

METHODS

A total of 106 patients (grades 1-2 of IOTN, 64 females, 42 males; mean age: 15.5 years) from a private practice and treated with metal or ceramic brackets were included in this retrospective cohort study. The axial angulation of the upper and lower incisors was measured on lateral cephalograms before insertion of the first rectangular 0.016 × 0.022-in NiTi archwire (T0) and at the end of treatment about 8 weeks after insertion of the working 0.019 × 0.025-in stainless steel archwire (T1). Treatment-related changes according to bracket type, initial situation, premolar extraction, angle class, and skeletal vertical configuration were analyzed.

RESULTS

Although statistically significant treatment-related changes were seen for both the upper incisors (+ 1.3°) and the lower incisors (- 5.2°), only in ten patients (9.4%) was the prescribed torque value of 17° for the upper incisors and in no patient for the lower incisors achieved. A negative association between the induced change of axial angulation of incisors and the initial values was detected for the upper incisors as well as for the lower incisors. A comparison of the angle classes revealed significant differences in incisor changes. At the end of therapy, only a slight change for the upper central incisors in patients in angle class I cases and a significantly greater change in patients with angle class II/2 was observed. Cases with premolar extraction ended with lower axial angulation of the incisor than cases without extraction. The individual analysis of possible influencing factors also revealed an association with the vertical skeletal configuration.

CONCLUSIONS

For the first time, the presented data show clinically relevant influencing factors for incisor axial angulation changes of the upper and lower incisors in relation to the torque value of the applied brackets in the course of routine clinical practice. For the orthodontist, it remains mandatory to decide whether a customized system must be individualized in order to achieve individual therapy goals.

Lower incisor position in different malocclusions and facial patterns

Introduction: The position of lower incisor has been of considerable concern when planning an orthodontic treatment, having been recognized as one of diagnostic keys, Very important in the development of malocclusion and facial pattern. Objectives: In this study we claim to determine the importance of the position and inclination of lower incisor in the different malocclusions and facial patterns, and to base which of the cephalometric measurement parameters are the mostreliable. Material and Methods: Ninety lateral radiographies were taken, and they were classified by skeletal malocclusion and facial pattern.These teleradiographies have been performed cephalometric analysis, which includelower incisor position belong the following analysis: Ricketts, Riolo, Tweed, McHorris, Jarabak-MSE and Holdaway. Study Design: Cross-sectional study where we perform statistical analysis Anova test, Pearson correlations and Bonferroni analysis. Results: The analyzed measurements present a statistically significant differentiation in lower incisor inclination respect to the anterior cranial base, McHorris angle, angulation of lower incisor respect to occlusal plane and mandibular plane. Conclusions: There are statistically significant differentiation in lower incisor position and inclination respect the malocclusion and individual facial pattern.

Key words:Lower incisor, cephalometric analysis, facial patterns, facial biotype, skeletal malocclusions.