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The activated face-bow: Simple, safe, extraoral traction
The activated face-bow: Simple, safe, extraoral traction Franc0 Magni, D.M.D., Ph.D., M.D., D. Orth., R.C.S.* Genoa, Italy
T
he activated face-bow is a simple mechanism that has been used since 1966 with satisfactory results. It is made of two parts: the face-bow and the unextensible neck strap or headgear (Fig 1). The face-bow consists of the inner bow wire (I .2.5 mm.) and the outer bow wire (I .50 mm.), specially shaped and soldered together. The neck strap or headgear is made of a simple plastic strap 25 mm. wide. At each extremity an aluminum half-ring is fixed. These two half-rings act as connections with the face-bow. To provide some elasticity to the outer bow at the joint level, a loop is shaped into it with a gentle curve. This solves the problem of breakages near the soldered joint. Rubber bands, coil springs, or other auxiliary elastic attachment used to connect face-bows to neck straps or headgear have become obsolete for US.‘-~ The activation of the face-bow’s central coil, which moves the arms of the outer bow outward, is enough to produce the same force delivered by the rubber bands. The amount of force can be tested by pushing the expanded outer arms against the patient’s cheeks in order to engage its hooks with the half-rings of the neck Stmp or headgear (Fig. 2). The amount of force delivered by the mechanism can be adjusted and measured with a Don&ix gauge or similar instrument. The coiled outer bow plus a nonextensible strap makes it impossible to withdraw the face-bow, even out of the molar tubes, without previous disengagement of the neck strap or headgear. If this is done, the face-bow becomes a passive tool with little power to cause injury. The arms of the outer bow, once engaged with the half-rings of the neck strap or headgear, should be as near the patient’s cheeks as possible. In this way accidental withdrawal is practically impossible (Fig. 2). Therefore, face-bow wearing becomes safe. Construction
procedure
Cut one piece of 1.5 mm. stainless steel hard wire, 33 cm. long. Mark the middle of it and bend at that level a symmetrical coil with a gentle curve (Fig. 3). Cut a piece 20 cm. long of 1.25 mm, stainless steel hard wire and mark the middle of it. Bend it in an ideal arch form with a molar stop and adapt to the patient’s plaster cast. Spot weld the two arches in the center and wrap 0.08 by 1.OO mm. stainless steel tape *Lecturer at the University of F’arma, Dental Institute, and at the School of Orthodontics, University of Cagliari.
152
OCQZ-Y416/79/020152+04$00.40/0
0
1979 The C. V. Mosby
Co.
Volume Number
15 2
Activated face-bow
153
Fig. 1. Activated face-bow with passive neck strap.
Fig. 2. The outer arm is pushed against the patient’s cheek to provide engagement of the half-ring of neck strap. For maximum safety, the outer bow should rest near the cheek.
Fig. 3. A gentle loop is shaped in the middle of the 1.5 mm. outer bow. The 1.25 mm. inner bow is shaped over the patients cast. The outer and inner bows are spot welded, with 0.08 by 1 .O mm. tape wrapped around them.
Fig. 4. One of the two aluminum half-rings has been already stapled to the neck strap
Fig. 5. Cervical strap pulled backward through unstapled aluminum half-ring until hooks approximate patient’s cheeks.
twice on each side of the joint. Spot weld around the tape. The tape should be covered with solder, while the wire should not be annealed during soldering (Fig. 3). Check for resiliency of outer and inner bow. Cut a piece of plastic neck strap 25 cm. long and fix one of the two aluminum half-rings on one side of it with a heavy stapling machine. Insert the strap into the other ring but do not staple yet (Fig. 4).
Volume75 Number
2
Activated face-bow
155
Fig. 6. Combined high-pull and cervical pull. The length of outer bow has been reduced for correct application of neck strap and headgear.
Insert the inner bow in the molar tubes. The anterior portion of the inner bow should be 2 mm. from the labial surface of the upper incisors. Push one flexible arm of the outer bow against the patient’s cheek and mark it with a pencil 15 mm. anterior to the earlobe. Shape a horizontal hook at that level. The same must be done on the other side. Now take the prepared neck strap and insert the fixed half-ring into the hooks of the outer bow and pull the strap until both activated outer bow hooks are 5 mm. from the cheeks (Fig. 5). Staple the other aluminum half-ring and check for safety by attempting to pull the face-bow out of the patient’s mouth. One should not be able to pull the inner bow out of the molar tubes. Some modifications are necessary to adjust the activated face-bow for high-pull and for horizontal or combined-pull extraoral traction (Fig. 6). To apply orthopedic forces, use a heavier outer bow, size 1.8 mm. or even 2.0 mm. The activation of the heavier wire should provide the necessary forces. Summary A simple and safe extraoral traction model is described. This consists of a face-bow with activated outer arms and a neck strap or headgear without any elastic force, such as rubber bands, elastic ribbons, coil springs, etc. The appliance cannot be withdrawn from the mouth by accident; therefore, the patient is protected from possible injuries. REFERENCES 1. Dougherty. H. L.: A biodifferential system of face-bow mechanics, AM. J. ORTHOD. 70: 505-516, 1976. 2. Kloehn S. J.: Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face, Angle Orthod. 17: 10-33, 1947. 3. Kloehn, S. J.: Orthodontics; evolution of cervical anchorage force in treatment, Angle Orthod. 31: 9 I- 104, 1961.
T
he activated face-bow is a simple mechanism that has been used since 1966 with satisfactory results. It is made of two parts: the face-bow and the unextensible neck strap or headgear (Fig 1). The face-bow consists of the inner bow wire (I .2.5 mm.) and the outer bow wire (I .50 mm.), specially shaped and soldered together. The neck strap or headgear is made of a simple plastic strap 25 mm. wide. At each extremity an aluminum half-ring is fixed. These two half-rings act as connections with the face-bow. To provide some elasticity to the outer bow at the joint level, a loop is shaped into it with a gentle curve. This solves the problem of breakages near the soldered joint. Rubber bands, coil springs, or other auxiliary elastic attachment used to connect face-bows to neck straps or headgear have become obsolete for US.‘-~ The activation of the face-bow’s central coil, which moves the arms of the outer bow outward, is enough to produce the same force delivered by the rubber bands. The amount of force can be tested by pushing the expanded outer arms against the patient’s cheeks in order to engage its hooks with the half-rings of the neck Stmp or headgear (Fig. 2). The amount of force delivered by the mechanism can be adjusted and measured with a Don&ix gauge or similar instrument. The coiled outer bow plus a nonextensible strap makes it impossible to withdraw the face-bow, even out of the molar tubes, without previous disengagement of the neck strap or headgear. If this is done, the face-bow becomes a passive tool with little power to cause injury. The arms of the outer bow, once engaged with the half-rings of the neck strap or headgear, should be as near the patient’s cheeks as possible. In this way accidental withdrawal is practically impossible (Fig. 2). Therefore, face-bow wearing becomes safe. Construction
procedure
Cut one piece of 1.5 mm. stainless steel hard wire, 33 cm. long. Mark the middle of it and bend at that level a symmetrical coil with a gentle curve (Fig. 3). Cut a piece 20 cm. long of 1.25 mm, stainless steel hard wire and mark the middle of it. Bend it in an ideal arch form with a molar stop and adapt to the patient’s plaster cast. Spot weld the two arches in the center and wrap 0.08 by 1.OO mm. stainless steel tape *Lecturer at the University of F’arma, Dental Institute, and at the School of Orthodontics, University of Cagliari.
152
OCQZ-Y416/79/020152+04$00.40/0
0
1979 The C. V. Mosby
Co.
Volume Number
15 2
Activated face-bow
153
Fig. 1. Activated face-bow with passive neck strap.
Fig. 2. The outer arm is pushed against the patient’s cheek to provide engagement of the half-ring of neck strap. For maximum safety, the outer bow should rest near the cheek.
Fig. 3. A gentle loop is shaped in the middle of the 1.5 mm. outer bow. The 1.25 mm. inner bow is shaped over the patients cast. The outer and inner bows are spot welded, with 0.08 by 1 .O mm. tape wrapped around them.
Fig. 4. One of the two aluminum half-rings has been already stapled to the neck strap
Fig. 5. Cervical strap pulled backward through unstapled aluminum half-ring until hooks approximate patient’s cheeks.
twice on each side of the joint. Spot weld around the tape. The tape should be covered with solder, while the wire should not be annealed during soldering (Fig. 3). Check for resiliency of outer and inner bow. Cut a piece of plastic neck strap 25 cm. long and fix one of the two aluminum half-rings on one side of it with a heavy stapling machine. Insert the strap into the other ring but do not staple yet (Fig. 4).
Volume75 Number
2
Activated face-bow
155
Fig. 6. Combined high-pull and cervical pull. The length of outer bow has been reduced for correct application of neck strap and headgear.
Insert the inner bow in the molar tubes. The anterior portion of the inner bow should be 2 mm. from the labial surface of the upper incisors. Push one flexible arm of the outer bow against the patient’s cheek and mark it with a pencil 15 mm. anterior to the earlobe. Shape a horizontal hook at that level. The same must be done on the other side. Now take the prepared neck strap and insert the fixed half-ring into the hooks of the outer bow and pull the strap until both activated outer bow hooks are 5 mm. from the cheeks (Fig. 5). Staple the other aluminum half-ring and check for safety by attempting to pull the face-bow out of the patient’s mouth. One should not be able to pull the inner bow out of the molar tubes. Some modifications are necessary to adjust the activated face-bow for high-pull and for horizontal or combined-pull extraoral traction (Fig. 6). To apply orthopedic forces, use a heavier outer bow, size 1.8 mm. or even 2.0 mm. The activation of the heavier wire should provide the necessary forces. Summary A simple and safe extraoral traction model is described. This consists of a face-bow with activated outer arms and a neck strap or headgear without any elastic force, such as rubber bands, elastic ribbons, coil springs, etc. The appliance cannot be withdrawn from the mouth by accident; therefore, the patient is protected from possible injuries. REFERENCES 1. Dougherty. H. L.: A biodifferential system of face-bow mechanics, AM. J. ORTHOD. 70: 505-516, 1976. 2. Kloehn S. J.: Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face, Angle Orthod. 17: 10-33, 1947. 3. Kloehn, S. J.: Orthodontics; evolution of cervical anchorage force in treatment, Angle Orthod. 31: 9 I- 104, 1961.