ALF Appliance

The Advanced Light wire Functional appliance (ALF) was developed by Dr. Darick Nordstrom. (See fig.#1)

Darick Nordstrom B.S., D.D.S.

d@nordstromdds.org

The ALF appliance took advantage of the advancement in wire technology that created a form of nickel titanium that could be soldered. This in turn allowed for the various designs of the appliance.

It should be noted that there are clinicians that strictly adhere to the ALF treatment philosophy which disregards the use of other appliances or treatment concepts. This article is intended to demonstrate how to practically incorporate the ALF appliance and treatment concepts into a multi disciplined orthopedic & orthodontic practice.

The appliance is typically anchored on the permanent first molars with either cribs or on bands. Most clinicians use bands to anchor the appliance as this eliminates compliance problems and the fact that the appliance can be distorted when removed and replaced by the patient. The patient is cautioned not to eat anything sticky as this can distort the appliance. (See fig.#2)

Bands Cribs

Fig. #2

The connecting wire molar to molar is known as the body wire. The body wire always has an omega loop mesial to the first molars. Crescent wires can be soldered to the body wire to stabilize the appliance and to function as anchorage within the appliance. Additional omega loops are placed within the body to generate a light force when activated. (See fig. #3)

Fig.#3

Indirect Banding

The technique employed for the fabrication of the ALF appliance is called indirect banding. The clinician makes either a scan or an impression of the arch. They then place separating elastics mesial and distal to the first molars creating the necessary band spacing. The laboratory technician cuts the band spacing on the model and fits the appropriate size band.

Placing The ALF Appliance

The first step in placing the ALF appliance is to check the length of the crescent wires. The clinician needs to check the length of the crescent wires and adjust them for retention.

Once the crescent wires are properly adjusted composite ledges are placed on the teeth with the crescents wires to stabilize the appliance. A special ALF instrument is used to place the composite ledges. The opposite end of the instrument is used to place and remove the ALF appliance. (See fig.#5)

Fig.#5

The ALF appliance can be used in either the lower or upper arch. The primary use for the appliance is to develop the transverse width of the arches. An additional effect of the appliance is to recover lost arch length. This action is especially important in the lower arch where active mesial drift frequently causes mandibular arch length loss.

The upper ALF appliance can be modified with two additional sagittal omega loops to place a sagittal force within the maxilla. (See fig. #6)

Fig.#6

Another modification of the upper ALF appliance is the addition of a trans palatal arch (TPA). The TPA is placed in the upper ALF appliance when the posterior segment of the maxilla is more severely underdeveloped . (See fig. #7

)

Fig.#7

The ALF appliance is frequently used in conjunction with fixed orthodontic appliances, typically the Delta Force, to level, align, and torque the teeth during the arch development. This technique significantly reduces the treatment time and increases stability as it parallels the roots of the teeth early in the treatment.(See fig.#8)

 

Fig.#8

Activation Of The ALF Appliance

The optimal load for all light wire appliances, including the ALF appliance, is 3mm. The ALF appliance has both midline and sagittal omega loops. The midline omega loops are activated by expanding the base of the omega loop by approximately 1.5mm using a flat on flat pliers. This is followed by holding the throats of the omega loop with the round beak of the Jaraback pliers and returning the body to the Roman arch bilaterally using the fingers. (See fig.#9)

Fig.#9

The sagittal omega loops are activated by expanding the base of the omega with a flat on flat pliers. Only one of the two throats are adjusted with the Jaraback pliers and fingers to return symmetry to the body wire. (See fig.#10)

Fig.#10

The sequence of arch development is as follows:

1. The asymmetrical Division Two is corrected first activating only one of the sagittal omega loops in the upper Sagittal appliance.
2. Once the asymmetrical Division Two has been corrected, which also corrects the deviation of the upper skeletal midline, both sagittal omega loops are activated to begin the correction of the symmetrical Division Two.
3. When a sagittal over jet appears the transverse omega loop is activated. When a transverse overjet is created by developing the maxilla the midline omega loop in the lower ALF is activated to begin the lower transverse arch development.

Monthly Appoints

Most patients are seen once a month for evaluation and appliance adjustment. It is important that the clinician monitors the omega loops relative to the soft tissue. If an omega loop comes into active contact with the soft tissue, it will incorporate into the soft tissue. The patient is usually totally unaware this has occurred. (See fig. #11)

Fig.#11

If this does occur the appliance needs to be surgically removed from the soft tissue. A soft tissue laser is the best option for removing the appliance. (See fig.#12)

Fig.#12

Two things can cause an omega loop to come into active contact with the soft tissue. One cause is over expanding an omega loop. The omega loop can be unloaded using a large occulist pliers to reduce the circumference of the loop. (See fig.#13)

Fig.#13

A second cause is torquing the omega loop during the adjustment, or the patient accidentally torquing the omega loop by eating something sticky. The torque in the omega loop can be changed by holding the two throats with a flat on flat pliers and pushing the loop away from the soft tissue. (See fig.#14)

Fig.#14

Combination Appliance Therapy

A common combination of light wire appliance therapy is the use of an upper RN-Sagittal appliance with the lower ALF appliance. This combination of appliances allows the doctor to control the vertical dimension, develop the arches, and distract the mandible in the skeletal Class II patient. (See fig.#15)

Fig#15

Critical Anchorage & the ALF Appliance

Critical anchorage in a light wire appliance means that there is something in the occlusion that creates an anchor unit that causes the appliance to produce asymmetrical movement. The critical anchorage must be eliminated first before the light wire appliance can be used. The three most common critical anchorage situations are posterior dental cross-bites, the posterior skeletal cross -bite, and an internally rotated maxilla.

The posterior dental cross-bites are corrected with 3/16” 4.5oz cross-bite elastics. Separating elastics are used to open the contacts of the tooth or teeth actually in the cross-bite. This allows them to move back into the arch. (See fig.#16)

Fig. #16

The posterior skeletal cross-bite is corrected with a rigid appliance such as a Schwarz or a fixed expander. (See fig.#17)

Fig. #17

The internally rotated maxilla is corrected with a modified Schwarz appliance that engages cross arch anchorage and unilaterally develops the maxilla. (See fig.#18)

Fig.#18