Crossbow Versus Forsus Springs in Mild to Moderate Class II Malocclusion Cases

Summary

Class II malocclusion (mismatch between the upper and lower jaw in which the lower jaw appears to be smaller from a profile point of view) are common in the general population. Around 1/3 of the population have some degree of this skeletal/dental problem and it is one frequent reason why patients decide to undergo orthodontic treatment. Treatment alternatives will basically depend on the facial skeletal development of the patient and also on the magnitude of the skeletal/dental discrepancy.

For patients that are not yet fully skeletal mature, the treatment of mild to moderate Class II malocclusion involves a combination of a small skeletal growth modification effect and more significant dental movements. For skeletal mature individuals with a severe mismatch, the treatment usually involves jaw surgery to fully correct the malocclusion. For less severe cases orthodontic camouflage exclusively done by orthodontic movements is an option.

If the case is not severe enough to warrant a surgical approach there are several treatment alternatives. One of the most commonly used options is the use of orthodontic loaded springs that apply forces through brackets and arch wires bonded into the teeth so that the teeth will interrelate better.

A different alternative was proposed some years ago. The Xbow (spelled Crossbow) appliance differs from the above-proposed option in that no brackets are bonded or arch wires used. The orthodontic springs are applied to a metal framework cemented on some upper and lower teeth. Once the skeletal/dental problem is believed to have been significantly improved, fine tuning of the remaining dental problems is managed with brackets and arch wires. The theoretical advantage of such a design is that adverse effects, such as root resorption and decalcification from the long-term use of brackets and arch wires, are theoretically minimized as the brackets and arch wires have to be used for a shorter period of time.

Although there are some retrospective reports about the skeletal and dental effects of the Xbow appliance and only one prospective trial comparing the skeletal and dental changes to a non-treated growing sample; no randomized clinical trial has yet evaluated the changes compared to a current standard of care alternative which is the simultaneous use of loaded springs concurrent with brackets and arch wires.

Conditions

• Malocclusion, Angle Class II

Interventions

DEVICE

Brackets plus Forsus springs

Full brackets and after completion of level and alignment insertion of Class II correctors (Forsus spring devices).

DEVICE

Xbow plus full brackets

Xbow appliance to be inserted first. After anteroposterior changes have been completed full brackets will be bonded and occlusion fine tuned

Sponsors & Collaborators

• University of Alberta

  lead OTHER

Principal Investigators

• Carlos Flores Mir, DDS, FRCD(O) · University of Alberta

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

11 Years

Max Age

15 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2012-10-01

Primary Completion

2018-07-31

Completion

2020-07-31

Countries

• Canada

Study Locations