The Williams appliance was designed by Dr. Jeff Williams who was cross trained as both a pediatric dentist and as an orthodontist. (See fig#1)

 

Jeff I.Williams D.D.S.,M.S.

jiwms3@gmail.com

Fig.#1

The Williams appliance is basically a fixed expander for the lower arch that incorporates a .014 thermal Niti lingual arch wire to the lower incisors. The appliance is used to develop the lower arch and to recover lost lower arch length. (See fig.#2)

Fig. #2

The Williams appliance is primarily used in the mixed dentition but can be modified for the permanent dentition. The first step in the design of the appliance is to make the decision as to placing the bands on the deciduous second molars or on the permanent first molars.

In the early mixed dentition, the blank bands are usually placed on the deciduous second molars. In the late mixed dentition, the bands with buccal tubes are placed on the permanent first molars. The band should always be placed symmetrically. A good rule to follow is the deciduous second molars should have at least 50% of their roots remaining to support the appliance. (See fig.#3)

Fig. #3

The first permanent molars should be banded.

The lingual arch wire in the appliance is .014 thermal Niti. The arch wire is in a .032 steel tube. The steel tube is sealed at its distal end to prevent the wire from escaping when it is loaded behind the lower incisors.

Steel buttons are bonded to the lingual of the most in standing lower incisors to stabilize the arch wire. If the most in standing lower incisor is a central incisor, one button will stabilize the arch wire. If the most in standing lower incisor is a lateral incisor a second button is required on the contralateral side to fully stabilize the arch wire. The buttons are bonded as gingival as possible.(See fig#4)

Fig. #4

Placing the Williams appliance

The technique employed for the fabrication of the Williams appliance is called indirect banding. The clinician makes either a scan or an impression of the lower arch. They then place separating elastics mesial and distal to the molars to be banded creating the necessary band spacing. (See fig#5) The laboratory technician cuts the band spacing on the model and fits the appropriate size band.

Fig. Fig. #5

The steps for placing the Williams appliance are as follows:

1. Remove the separating elastics.
2. Remove the lingual arch wire from the appliance.
3. Trial fit the appliance. Each appliance will have a “path of insertion” that needs to be determined prior to attempting to cement the appliance.
4. Remove the appliance and acid etch the in standing lower incisor or incisors.
5. Bond the steel buttons to the incisors using any flowable composite. Most clinicians use the same bonding material they use for bonding brackets.
6. Replace the lingual arch wire into the framework of the appliance.
7. If the Williams appliance is banded on the deciduous second molars the molars must be acid etched prior to cementing the bands.
8. Cement the appliance with any light cured band cement. Caution. Before curing the cement be sure the mesial of the bands are not over seated. You must be able to access and change the lingual arch wire without removing the appliance!
9. Use the ice ligature director to place the .014 thermal Niti arch wire under the buttons. The arch wire has been pre-loaded by the laboratory during fabrication of the appliance. (See fig.#5)

The lower Williams appliance is almost always used in conjunction with an orthopedic appliance developing the maxilla. The four most common maxillary appliances are a transverse Schwarz, a 3-D Schwarz, a 3-Screw Schwarz, and a maxillary version of the Williams appliance. (See fig.#6)

Transverse Schwarz 3-D Schwarz

3-Screw Schwarz Upper Wiliams

Fig. #6

Sequence of developing arches

It is extremely important to understand the correct sequence of developing the upper and lower arches with any appliance system. It is also important to understand the rational that creates this sequence. The most pathologic clinical condition a clinician can encounter is treating a patient with a transversely narrow maxilla, a short maxilla, a retrognathic maxilla, an asymmetric premaxilla causing an upper skeletal midline shift, and a dental alveolar base Division Two. The correct sequence is as follows:

1. Treat the asymmetrical premaxilla which corrects the upper skeletal midline shift as well as the asymmetrical dental Division Two. This step requires maximum anchorage within the maxilla which is easy to attain if this correction is addressed first.
2. Correct the now symmetrical dental Division Two until a sagittal over jet starts to develop. This prevents any loss of anchorage within the appliance which could distalize the maxillary buccal segments and starts to decompress the TMJs.
3. Continue the symmetrical sagittal correction and start the transverse maxillary development. This begins to eliminate the transverse entrapment on the mandible and decompresses the TMJs.
4. When a transverse overjet of the maxilla to the mandible occurs the TMJs have decompressed. The Reverse Pull Head Gear can now be added to the upper orthopedic appliance if required.
5. It is at this point the transverse development of the lower arch also begins.

Applying this concept to the lower Williams appliance, the appliance is placed at the same appointment as the maxillary arch development appliance. The lingual arch wire is loaded behind the lower incisors to take advantage of the additional anchorage created by the maxillary entrapment on the lower inter canine area. This allows the appliance to immediately begin to recover the lost lower arch length. The maxillary arch is developed in the previously established sequence. The screw in the lower Williams appliance is not activated until step #5 in the sequence of developing arches.

Adjusting the screw

Intraoral screws are fabricated to open anterior to posterior. This allows a new keyhole to appear for the next adjustment. All intra oral screws are adjusted with a special intra oral key that is designed with a bayonet bend that prevent the key from penetrating the soft tissue. The key has a handle that prevents the patient from swallowing or aspirating the key should the parent accidentally drop it in the patient’s mouth. (See fig. #7)

Intra oral Key

Fig #7

The screw in the lower Williams is turned at the same rate as the transverse screw in the maxillary appliance. The rate is twice a week in the mixed dentition unless the child has an anterior open bite and an anterior tongue thrust. In this situation the adjustments are made once a week to control the vertical dimension.

The lingual arch wire

The gauge of the lingua arch wire is .014 and is thermal nickel titanium. The wire is preloaded by 2mm per side when the appliance is fabricated. It is engaged under the lingual buttons with an ice ligature director after the appliance has been cemented. It is important that the arch wire is in the martensitic state when loaded beneath the buttons with the ice ligature director. This allows the appliance to immediately start to regain the lost lower arch length.

When the arch wire is no longer asymmetrical around the buttons it has become passive. (See fig#8)

Ice ligature director Passive lingual arch wire

Fig. #8

If the clinician still needs the appliance to continue to recover the lost lower arch length it must be replaced with a slightly longer arch wire. The passive arch wire is removed and used as a guide to establish the length of the new active arch wire. The new arch wire is 2mm longer per side. The new wire is placed into the lingual tubes of the appliance, chilled with the ice ligature director, and engaged under the buttons on the incisors. The pliers of choice to place and remove the lingual arch wire is the Wiengard pliers. (See fig.#9)

Weingard pliers

Fig. #9

A very important concept in using the Williams appliance is to understand the anchorage within the appliance. The clinician must constantly monitor the inclination of the lower incisors with the lingual buttons. If the incisors move into excess proclination the force in the lingual arch wire must be reduced. This is accomplished by removing the lingual arch wire and reducing its length by 1mm per side. The basic rule is you load the .014 thermal Niti lingual arch wire by 2mm per side, and you unload the arch wire by 1mm per side. Should the child miss a monthly appointment and the lower incisor proclination becomes excessive, simply remove the lingual arch wire. Allow the incisor to function for four weeks which will correct the excessive proclination. Reduce the length of the lingual arch wire and replace it into the appliance.

In extremely severe cases one of the lower incisors can be totally blocked out of the arch. The procedure in this situation is to proceed with the treatment as normal and allow the block out incisor to erupt lingual to the arch wire. Once the lower arch is fully developed and the lost arch is length recovered, bond a button to the fourth incisor. Engage the lingual arch wire beneath the button and move the incisor into the arch.

At some point in the treatment sequence the Williams appliance is usually replaced with a lingual arch to hold the lower Space of Nance as the child matures into the permanent dentition. In some patients the Williams appliance can be used as a lingual arch. In this situation the .014 thermal Niti lingual arch wire is replaced with a .016 standard austenitic Niti arch wire.

Impacting Second molars

The Williams appliance is a very efficient tool to develop the lower arch and to recover symmetrical lower arch length loss in the mixed dentition. When the child is in the late mixed dentition, has well developing third molars, and has severe lower arch length loss it is possible to impact the lower second molars by distal driving. (See fig.#10 ) In this situation it is usually best to extract the second molars and use the standard Williams appliance treatment. The third molars will replace the second molars creating a normal occlusion. This is actually the concept behind terminal arch extraction therapy for treating patients with severe arch length loss or macrodontia.

Fig. #10

Class III Williams Appliance

The Williams appliance can be modified with buccal arms to support intra oral Class III elastics. (See fig.# 11)

Fig. #11

This allows the clinician to develop the lower arch and at the same time employ intra oral Class III mechanics. Lingual rests are placed on the bands to prevent the Class III elastics from tipping the molars. The rest are activated with the distal stop pliers after the molar bands have been cemented.(See fig.#12) This modification can be applied in either the mixed dentition or the permanent dentition.

Distal Stop Pliers

FIG. #12

Pre Treatment Situations

There are two situations where the clinician must pretreat the lower arch with a Schwarz appliance prior to using the Williams appliance. Some children have an extremely constricted lower inter canine area to the point there is insufficient room for the for the screw, buttons, and lingual arch wire. There are also situations where the buccal segments are in lingual version and there is no path of insertion for the Williams appliance. (See fig.#13)

Fig. #13

Hygiene

It is very important the patient maintains proper hygiene while wearing the Williams. The patient should use an irrigation system containing a plaque control agent following breakfast and prior to retiring in the evening.

For additional information on the various orthopedic appliances visit www.cfoo.com. If you have questions regarding the Williams appliance contact Dr. Skip Truitt at skip@cfoo.com.