Unified Denovo Multipurpose Analyzer

Abstract

Tooth movement is affected by various factors like magnitude, direction, and the duration of the forces applied; the direction of force plays the most pivotal part. Orthopedic appliances have long been used to apply extraoral traction forces to entirely limit or redirect the growth of the maxilla and mandible. Here, we present a very simple and efficient device. The multipurpose analyzer (MPA) is used to locate the center of resistance of maxilla and maxillary dentition, giving a more accurate direction of force vector in facemask and headgear cases. It is also used as chairside device clinically to measure facial heights, nasolabial angle, mentolabial angle, and mandibular plane (MP), as well as to measure cephalometrically MP, Frankfort horizontal (FH)–MP, palatal plane (PP)–MP, occlusal plane (OP), and MP during analysis.

Introduction

It is considered that the center of resistance serves as the primary point of reference for both skeletal bases and controlled tooth movement. To ensure effectiveness in clinical outcomes in orthodontics, appropriate control of the movement of various pressures applied to a tooth or skeletal foundation is required.^{1, 2}

It is relatively easy to locate the center of resistance for a tooth or group of teeth, but it is relatively difficult to locate the same in the skeletal base clinically. Even though there are various methods to locate, there are hardly any tools or devices to very accurately locate the same. Multipurpose analyzer (MPA) is designed as an innovative, simple, and efficient device. This can be used to locate the center of resistance of the maxilla, which aids in providing a more accurate direction of force vector for facemask and headgear cases. It can further be utilized for clinically measuring facial heights, nasolabial angle, mentolabial angle, mandibular plane (MP), etc., apart from cephalometric parameter measurement for analysis.

Technique for Fabrication

The ends of the straight-tip tweezers were made blunt, and an acrylic ball is placed at the tip of the intraoral arm (Figure 1).

Figure 1.

Acrylic Ball Placed at Intraoral Arm.

A modified metal protractor with a scale, along with tweezer, was assembled together using screws to form an analyzer (Figure 2).

Figure 2.

Metal Protractor with Scale and Stainless-Steel Straight Tip Tweezer All Assembled Together Using Screw.

A scale with a movable vertical component with wire is attached at the center of the plastic protractor using screw for the same (Figure 3).

Figure 3.

Movable Vertical Component with Wire is Attached to the Scale.

Methodology

Locating Center of Resistance

1. The patient, after being seated on the chair, was asked to look straight at the eye level having teeth in occlusion and soft tissues relaxed.

2. The intraoral arm with a plastic sleeve is placed at the center of resistance of maxilla, and the acrylic ball is palpated and marked extraorally; it will coincide with the intraoral center of resistance point.

3. The extraoral arm is adjusted according to the intraoral arm as superimposed, and the center of resistance is marked extraorally. The value is viewed extraorally on a metal protractor. Force vector can be adjusted for facemask (Figure 4) and headgear depending on control needed in the maxilla (Figures 5 and 6).

Figure 4.

Force Applied 30° Downward and Forward to Occlusal Plane.

Figure 5.

Force Should be Passed Along the Center of Resistance to Produce Translation.

Figure 6.

Force Passed Above the Center of Resistance to Produce Counter Clockwise Rotation and Below for Clockwise.

Cephalometric Application

1. A movable vertical metal component is attached to the scale.

2. The cephalometric tracing sheet is placed on the view box, and the vertical component with wire is made to coincide with the sella-nasion (SN) and Frankfort horizontal (FH) plane, and the center of the protractor is placed on the gonial point.

3. Angular measurements [FH–MP, palatal plane (PP)–MP, SN–MP, occlusal plane (OP), and MP] are calculated using a protractor (Figures 7–9).

Figure 7.

Frankfort Horizontal (FH)–Mandibular Plane (MP).

Figure 8.

Palatal Plane (PP)–Mandibular Plane (MP).

Figure 9.

Sella-Nasion (SN)–Mandibular Plane (MP).

Clinically Linear and Angular Measurement

1. The patient is made to sit in an upright position and is asked to look at distant object straight at eye level.

2. The vertical metal component is attached to the scale, and it is moved up and down to measure linear facial heights clinically (Figures 10 and 11).

3. By coinciding wire at the FH plane and by keeping the center of the protractor at gonial point clinically, mandibular, nasolabial, and mentolabial angles can be measured (Figures 12–14).

Figure 10.

Clinical Measurement of Upper Facial Height.

Figure 11.

Clinical Measurement of Mid Facial Height.

Figure 12.

Clinical Measurement of Mandibular Plane.

Figure 13.

Clinical Measurement of Nasolabial Angle.

Figure 14.

Clinical Measurement of Mentolabial Angle.

Advantages

1. Single device for accurately locating and coinciding with the intraoral and extraoral center of resistance. It helps with measuring angular and linear measurements; no need for additional tools while doing cephalometric analysis.

2. Easy to carry.

3. Fabricated easily in a dental lab.

Conclusion

This novel, simple, innovative device can extraorally determine precisely the direction of the force vector and center of resistance of the maxillary dentition and maxilla. It can be used as an aid for class II patients requiring headgear for skeletal/dental or combination of movements. For class III patients requiring protraction headgear, this device could be used as a chairside device with added benefits.

Author’s Contribution

The corresponding author confirms that the manuscript has been read and approved for submission by all the named authors.