Total Orthodontics – what are fixed functional appliances?

total orthodontics

In this month’s Total Orthodontics, Zaid Esmail discusses the benefits of using fixed functional appliances when treating skeletal discrepancies compared to a Twin Block appliance.

My first article for Total Orthodontics will discuss fixed functional appliances and an alternative approach to treating skeletal discrepancies. My co-writers and I, Dr Tom Witcher and Dr Richard Jones, work at Total Orthodontics, part of Bupa Dental Care.

Functional appliances are used as a form of growth modification to address skeletal discrepancies in growing patients.

Pressures created by the stretch of the muscles and soft tissues are transmitted to the dental and skeletal structures. As a result, this moves teeth and modifies growth.

In addition, they are predominantly used to treat skeletal class II cases in growing patients.

The most common functional appliance used in the UK is the Clarke Twin Block. Removable functional appliances must be worn on a full-time basis and are heavily reliant on patient compliance.

Recent studies have shown that most of the overjet correction results from dentoalveolar changes and skeletal growth only amounted to 1-2mm.

As well as this, the discontinuation rate for removable functional appliances has been reported as low as 17% and as high as 42%.

Functional appliances are usually worn for between nine and 12 months. Usually, this is then followed by a course of fixed appliance treatment ranging from 12 to 24 months depending on the complexity.

This article will focus on an alternative approach to treating mild to moderate skeletal class II cases in growing patients using a fixed functional appliance. Primarily, this will address the Forsus Class II corrector.

The advantages of the Forsus Class II corrector

  1. Single visit placement with no lab work required
  2. Fixed in situ – not reliant on compliance
  3. Class II correction can be carried out with concurrent mechanics
  4. Well-tolerated.

We will discuss a case in which a Forsus Class II corrector was utilised to treat a 13-year-old female.

The patient had a class II division two case on a mild skeletal class II, complicated by an increased overbite, mild crowding and missing lower right second premolar.

In addition, the molar relationship was a full unit class II on the right and half a unit class II on the left (Figure 1).

Figure 1: Pre-treatment photographs

The treatment plan

The plan for the treatment was to treat on a non-extraction basis and to correct the class II division two malocclusion using Forsus Class II corrector.

The treatment aimed to level and align the arches, torque the upper incisors and finish to a class I molar relationship bilaterally and maintain the lower right deciduous second molar.

The consensus for treating class II division two cases is to convert them into a class II division one, and then treat accordingly.

The patient was bonded up with 3M Gemini brackets (MBT prescription). In addition, 014” Nitinol wires were fully ligated.

Subsequent arch wires were then placed until we were ready to put 19×25” stainless steel wires.

At this appointment, the Forsus springs were also fitted (Figure 2).

Figure 2: Forsus fit appointment

At six weekly intervals, we reactivated the Forsus springs.

Further compression was placed on the spring at each appointment (Figure 3 and 4).

Once we achieved a class I incisor relationship, the Forsus springs were left passive for six weeks before removal.

Figure 3
Figure 4

We then removed the Forsus springs and took the case to its conclusion.

Figure 5 shows the completed case.

Figure 5

Total treatment time was just under 20 months.

Part of the delay in this case was waiting for the lower left second premolar to erupt.

In my experience, the average treatment time for a fixed functional case using Forsus springs is between 15-18 months.

In summary, Forsus springs are a good alternative to treating mild to moderate skeletal class II cases in growing patients. This is compared to the traditional Clarke Twin block functional appliance.

Contact [email protected] for references.

Read previous Total Orthodontics column

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