Original Research

Year : 2025 | Volume : 16 | Issue : 4 | Page : 91-101

Prediction Of Torque Expression Of Upper Central Incisor Using Different Auxiliaries In Clear Aligners - A FEM Study

Shifo Savio1, Srirengalakshmi Muthuswamy Pandian2, Muskan Chanduka1, Aravind Kumar Subramanian3,

Nikhillesh Vaiid4

1Post Graduate Resident, 2Associate Professor, 3Professor, 4Adjunct Professor, Department of Orthodontics, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai-77, India

Address for Correspondence:

Dr. Srirengalakshmi Muthuswamy Pandian

Associate Professor, Department of Orthodontics and Dentofacial Orthopaedics

Saveetha Dental College and Hospitals

SIMATS University

Email: rengalakshmi1910@gmail.com

ABSTRACT

BACKGROUND: Torque control of maxillary incisors remains a biomechanical limitation of clear aligner therapy. Auxiliaries such as attachments and power ridges have been proposed to enhance torque expression; however, quantitative evidence comparing their isolated biomechanical effects is limited. This finite element method (FEM) study aimed to predict and compare torque expression of the maxillary central incisor using clear aligners without auxiliaries, with vertical rectangular attachments, and with power ridges.

MATERIALS AND METHODOLOGY: A three-dimensional FEM model was constructed from CBCT and intraoral scan data of a patient with normal occlusion. Three models were analyzed: Group I (aligner without attachment), Group II (aligner with vertical rectangular attachment), and Group III (aligner with power ridge). A palatal force of 1.89 N was applied to simulate incisor torque. Displacement patterns along x, y, and z axes and stress distribution within the periodontal ligament (PDL) and alveolar bone were evaluated.

RESULTS: Vertical displacement was minimal and clinically insignificant in all groups. Labio-lingual displacement differed markedly: Group III demonstrated the greatest palatal crown and root displacement, indicating superior torque expression, followed by Group II, while Group I showed inadequate root control. Peak PDL stress was highest in the power ridge model (19.62 MPa), moderate with rectangular attachments (14.67 MPa), and lowest without attachments (13.48 MPa).

CONCLUSION: Power ridges significantly enhance torque expression of maxillary central incisors and have significant biomechanical advantage and force transmission compared with rectangular attachments or no attachment designs. Vertical rectangular attachments offer limited torque improvement, whereas aligners without auxiliaries are biomechanically insufficient for effective torque control.

KEYWORDS: Clear aligners; Torque expression; Power ridge; Auxillaries; Finite element analysis.

CONFLICT OF INTEREST AND FUNDING

Nil
How to cite this article: Shifo Savio, Srirengalakshmi Muthuswamy Pandian, Muskan Chanduka, Aravind Kumar Subramanian, Nikhillesh Vaiid. Prediction Of Torque Expression Of Upper Central Incisor Using Different Auxiliaries In Clear Aligners - A FEM Study. Int J Orthod Rehabil 2025;16 (4): 91-99.

Original Research

Year : 2023 | Volume : 14 | Issue : 2 | Page : 54-64

Evaluation Of Sphenoid Sinus Volume And Cranial Base Length In Subjects With Different Sagittal Skeletal Malocclusions

Arshya Kumar1, Srirengalakshmi Muthuswamy Pandian2

1Postgraduate Student, 2Associate Professor, Department of Orthodontics and Dentofacial Orthopedics, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences, Chennai 600077.

Address for Correspondence

Dr. Srirengalakshmi Muthuswamy Pandian,

Associate Professor, Department of Orthodontics and Dentofacial Orthopedics, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences, Chennai 600077 Email: srirengalakshmi.sdc@saveetha.com

Contact number: +91 8867783552.

Abstract

Introduction: 

The most hidden and inaccessible of all the paranasal air sinuses is the sphenoid sinus, a cavity with an irregular shape that is situated in the middle of the cranial base. Since the anterior cranial base shows little growth after the age of 7, it is regarded as a stable reference for cephalometric analysis.
Objective: The aim of this study was to predict skeletal malocclusion by correlating the length of the cranial base and the volume of the sphenoid sinus in different sagittal skeletal patterns.
Materials and methodology:

In this study, a total of 30 cone beam computed tomography (CBCT) scans of patients, aged between 18 and 35 years who underwent orthodontic and orthognathic treatment were evaluated. DICOM files from the CBCT scans were imported and viewed using Dolphin imaging software. Skeletal malocclusion was evaluated using a lateral cephalogram obtained from the CBCT. Volumetric analysis of the sphenoid sinus and length of the cranial base was evaluated with the help of the Dolphin imaging software. A normality test was done to decide the statistical method for data analysis. A one-way ANOVA with Tukey’s post hoc test was done to compare the three groups.
Results:

There was a correlation noted between the volume of the sphenoid sinus in skeletal class II malocclusion but no correlation was noted in the length of the cranial base. The mean value of the volume of the sphenoid sinus in subjects with class II skeletal malocclusion was 12613.50± 2023.409 which was greater compared to the other skeletal malocclusions.
Conclusion:

Sphenoid sinus volume was reported to be increased in subjects with skeletal class II malocclusion but there was no correlation between the cranial base length and sphenoid sinus volume in any group.

CONFLICT OF INTEREST

No conflicts of interest

FUNDING

No funding from the public, private sector or institutional organizations.

How to Cite this Article: Kumar, A., & Pandian, S. M. (2023). Evaluation Of Sphenoid Sinus Volume And Cranial Base Length In Subjects With Different Sagittal Skeletal Malocclusions: Original Research. International Journal of Orthodontic Rehabilitation, 14(2), 54–64. https://doi.org/10.56501/intjorthodrehabil.v14i2.870