Limits...
Asymmetric Outer Bow Length and Cervical Headgear Force System: 3D Analysis Using Finite Element Method.

Geramy A, Hassanpour M, Emadian Razavi ES - J Dent (Tehran) (2015)

Bottom Line: A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer.The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm).A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use.

View Article: PubMed Central - PubMed

Affiliation: Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran ; Professor, Department of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran.

ABSTRACT

Objectives: This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths.

Materials and methods: Four 3D finite element method (FEM) models of a cervical headgear attached to the maxillary first molars were designed in SolidWorks 2010 software and transferred to ANSYS Workbench ver. 11 software. Models contained the first molars, their periodontal ligament (PDL), cancellous and cortical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with differences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer.

Results: The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm).

Conclusion: As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment.

Clinical relevance: A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use.

No MeSH data available.


Related in: MedlinePlus

The force system of a cervical headgear with unequal outer bow lengths (the distances were measured in a volunteer using a caliper in the clinic)
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4663312&req=5

Figure 2: The force system of a cervical headgear with unequal outer bow lengths (the distances were measured in a volunteer using a caliper in the clinic)

Mentions: The models were designed in SolidWorks 2010 (SolidWorks Corp., MA, USA) and were then transferred to ANSYS Workbench ver. 11 (ANSYS, PA, USA) for the solving process. To find the angles formed between the outer bow and its tangent to the neck, accurate trigonometric calculations were made using SolidWorks. Distances needed to draw Figure 2 were derived from a volunteer dental student by a clinical vernier caliper. In this way, the exact force components in the anteroposterior and mediolateral directions were found.


Asymmetric Outer Bow Length and Cervical Headgear Force System: 3D Analysis Using Finite Element Method.

Geramy A, Hassanpour M, Emadian Razavi ES - J Dent (Tehran) (2015)

The force system of a cervical headgear with unequal outer bow lengths (the distances were measured in a volunteer using a caliper in the clinic)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4663312&req=5

Figure 2: The force system of a cervical headgear with unequal outer bow lengths (the distances were measured in a volunteer using a caliper in the clinic)
Mentions: The models were designed in SolidWorks 2010 (SolidWorks Corp., MA, USA) and were then transferred to ANSYS Workbench ver. 11 (ANSYS, PA, USA) for the solving process. To find the angles formed between the outer bow and its tangent to the neck, accurate trigonometric calculations were made using SolidWorks. Distances needed to draw Figure 2 were derived from a volunteer dental student by a clinical vernier caliper. In this way, the exact force components in the anteroposterior and mediolateral directions were found.

Bottom Line: A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer.The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm).A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use.

View Article: PubMed Central - PubMed

Affiliation: Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran ; Professor, Department of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran.

ABSTRACT

Objectives: This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths.

Materials and methods: Four 3D finite element method (FEM) models of a cervical headgear attached to the maxillary first molars were designed in SolidWorks 2010 software and transferred to ANSYS Workbench ver. 11 software. Models contained the first molars, their periodontal ligament (PDL), cancellous and cortical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with differences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was calculated trigonometrically using data from a volunteer.

Results: The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm).

Conclusion: As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment.

Clinical relevance: A difference range of 1mm to 15 mm of length in cervical headgear can be considered as a safe length of outer bow shortening in clinical use.

No MeSH data available.


Related in: MedlinePlus