The Truitt III retainer was designed by Dr. John Wellington (Skip) Truitt in Gainesville, Texas. Dr. Truitt recognized the need for a long term night retainer for the prepubertal Class III patient. (See fig.#1)

Fig.#1

The basic concept for the treatment of a prepubertal Class III patient is to diagnose the child as early as possible and prevent the mandible from attaining its full skeletal Class III genetic potential. In the process the length of the maxilla and the position of the maxilla are overdeveloped as much as possible to compensate the skeletal Class III and in turn avoid the orthognathic surgery.

The problem with the skeletal Class III malocclusion is that it is genetic. Once the skeletal Class III is initially controlled the child continues in the pathologic growth pattern until completion of puberty.

Numerous studies have shown that the child experiences around 80% of their genetic growth while sleeping. The Truitt III retainer is worn at night following active Class III treatment to retard as much of the pathologic mandibular growth as possible. It is used in conjunction with intra oral and extra oral Class III elastics.(See fig.#2)

Truitt III Mixed Dentition Truitt III Permanent Dentition

Fig.#2

Early Diagnosis

The key to successfully treating the skeletal Class III patient is early diagnosis. Sometimes the diagnosis can be made in the primary dentition. Usually, the diagnosis is difficult to confirm until the early mixed dentition. The normal growth for a child this age is from a skeletal Class II into a skeletal Class I. If the child is observed growing from a skeletal Class I into a Skeletal Cass III the diagnosis is confirmed.

The Bimler cephalometric analysis is exceptionally accurate in making the skeletal Class III diagnosis on the younger patient. The Class III patient inherits both a long mandible and the forward position of the glenoid fossa. The position of the glenoid fossa is established early in the child’s maturation giving the clinician insight into the developing skeletal Class III.

Another valuable cephalometric diagnostic guide is Point-B should never approach Point-A. This relationship is measured in millimeters using the A-B overjet, and in degrees using the Factor #2. For these assessments to be accurate the clinician must check for modeling of the alveolar bone at Point-B, and for the relationship of Point-A to the anterior cranial base using Factor #1.

All of these diagnostic tools are explained in detail in the article entitled “The Bimler Cephalometric Analysis”. This article can be downloaded from the website at www.CFOO.com.

Class III Treatment

The maxillary appliance used for the initial correction of the skeletal Class III child in the primary or mixed dentition is either a 3D-Schwarz appliance or a 3-Screw Schwarz appliance. The appliance is modified with occlusal coverage of acrylic and with intra oral and extra oral Class III elastic hooks.

Many Class III patients have ideal or even sometimes overdeveloped lower arches. This is an indication the patient has low tongue posture. A tongue spinner is placed at the back of the upper appliance to assist the patient in leaning to elevate the tongue. In addition, the clinician should always check the lingual frenum for ankyloglossia and the need for laser surgery. (See fig.#3)

Fig.#3

The Class III maxillary Schwarz appliance is used with both intra and extra oral Class III elastics. It is important to note that the mandibular condyles must be properly related on the articular disks before Class III elastic force can be initiated. It is also critical to understand that once the articular disks mature from dense fibrous tissue into fibrocartilage the TMJs can no longer tolerate Class III elastics.

Reverse Pull Head Gear

The Maxillary Protraction Appliance is usually called a reverse pull head gear because its effect on the maxilla is the reverse of the classic Class II head gear. The RPHG rests on the mandible and is never used on a post pubertal patient. The RPHG is used I the skeletal Class III patient to retard the growth of the mandible and to advance the position of the maxilla.

The extra oral elastic force is initially 8 oz per side which allows the cranial sutures to begin responding to the force. After approximately four weeks the elastic force is increased to 16 oz which is the optimal orthopedic force.

The RPHG is manufactured in two sizes. Small for patients in the primary and mixed dentition and large for the patient in the permanent dentition. Each size has a daytime design that is out of the patient’s field of vision and a nighttime design that is comfortable for sleeping. The elastics in the nighttime version must be crossed to prevent the child from loosing the RPHG in their sleep. The extra oral elastics are attached to the front of the maxilla to prevent the maxilla from canting downward. This unwanted cant is known as the Kline effect and can damage the TMJs.(See fig.#4)

Fig.#4

Intreoral Class III Elastics

The intra oral Class III elastics cannot be used until the mandibular condyles are correctely positioned on the articular disks and the articular disks have not matured into fibrocartledge. The force of the intraloal Class III elastics are light, 4.5oz perside, due to the direction of force relative to the TMJs. They are worn durring the day only to allow the TMJs to decompress at night. (See fig.#5)

Fig.#5

The intraoral Class III elastics are attached to the posterior of the maxillary orthopedic appliance. They attach to the lower appliance at the cuspid area.

There are three basic options for the lower appliance in the Skeletal Class III teatment. If the lower arch is ideal the Class III fixed labial retainer is the best option. If the lower arch is underdeveloped the Class III fixed expander is the better option. If the lower arch is underdeveloped and has lower arch length loss the Class III Williams appliance is the appliance of choice. (See fig.#6)

Fig.#6

The lower appliance is banded on the deciduous second molars in the primary and the mixed dentition assuming the molars still have at least one half of their root structure remaining. The deciduous second molars should be acid etched prior to cementing the appliance to increase retention for the bands. The appliance is banded on the first permanent molars in the older patient.

Lingual rests are extended to either the first or second permanent molars. The rests are activated after the appliance has been cemented with the Distal Stop pliers. This prevents the Class III elastics from tipping the molars. (See fig.#7)

Fig.#7

Class III Retention

Once the active phase of treatment has been completed the skeletal Classs III patient must go into nighttime retention until all growth is complete. The Truitt III retainer is placed in conjunction with the night R.P.H.G. and intraoral Class III elastics.

The extraoral elastic force is reduces from the active 16 oz per side to 8 oz per side. The intra oral Class III elastic force remaines at 4.5oz per side. The labial bow is adjusted into contct with the lower incisors.

The clinician should monitor the patient every six months to evaluate the function of the TMJs. If the patient experiences any pressure in the TMJs the screws in the retainer are activated for additional maxillary development. The activation is once a week until the joints decompress. This adjustment may be required several times durring the retention plase of treatment. (See fig.8)

Fig.#8

It is extremely important that both the patient and the parrents fully understand the importance of of the nighttime retention phase of the treatment to avoid the need for orthognathic surgery. A special advised consent form is signed by the parent or gaurdian acknowledging they fully understand all of the ramifications of the skeletal Class III treatment. (See fig#9)

Fig.#9