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Force transmission characteristics of lingual orthodontic appliances
446 Reviews and abstructs
Force Transmission Lingual Orthodontic A. R. Brunette, and J. Matyas Orthodontic, Llentistr~
(From
S. J. Chaconas,
Res.
of
A. A. Caputo,
Posture and Intraoral Pressures Comparing Classes I, II, and Ill S. Y. Archer Universir)
and Biontaterials
J. Dent.
Characteristics Appliances
63: 257,
Sectiom.
UCLA
School
of
1984)
Until recently, lingual orthodontic appliances were considered to be impractical for a variety of reasons including difficulties with their design and construction. Improvements of lingual bracket design have led to the clinical utilization of this appliance. Several factors suggest that activation of lingual appliances are [sic] likely to produce force systems that differ from those produced by conventional fixed appliances. The purpose of this study was to visualize the results of forces applied on the lingual surfaces of teeth. Photoelastic models were constructed by embedding anatomic plastic teeth into a birefringent plastic. Malocclusions of the maxillary and mandibular arches were simulated that could be treated by either lingual or conventional fixed orthodontic appliances. The forces produced by both types of appliances were observed photoelastically. Forces applied by, leveling arch I+‘ires to the tooth posterior to the first premolars Mere similur in nature and intensi& ,for both linguul und conventional uppliunces. Also, similar stress patterns cc’ereobserved on the anterior and first premolar teeth for both arch w+res, but the intens&, was greater for the lingual appliance. Closing loop arch viaires produced more force on the incisor teeth by the lingual uppliunce than by the conventional appliance. The clinician must therejore be aware of the force d[fferences produced b> the lingual appliunce.
(From
and P. S. Vig
of Mat$and J. Dent.
Res.
und University,
63: 258,
of’Michigun
1984)
In a previous report comparing normal and Class II subjects, it was found that in both classes, posterior lingual forces varied with changes in head posture and were consistently higher than anterior lingual or labial forces. Anterior lingual forces decreased from head flexion to extension in both groups. The aim of this study was to establish if subjects with severe Class III skeletal relationships exhibited different patterns of pressure/head posture associations. Ten Class III subjects were compared with 10 Class I and I 1 Class II subjects using the pressure transducer technique previously described. Recordings were made in natural head position and at both -c_20” of extension and flexion during resting, swallowing, and speaking. Our results indicate: (I) Every subject shonaed pressure changes with changes in head position. (2) Statistical!\ signi3cunt differences within skeletal classes between transducer positions during ull tusks ic’cre found (a = .0.5). (3) Pressure duration during both speech and swallowing demonstrated the greatest dt#erence bctw.een skeletal classes. (4) When the factor of time was considered, Class I mean pressures were no longer the highest values. (5) Labiul recordings by Class 111subjects during rest in hemd extension were found to be significantly higher than Class I or Class II recordings. (6) More differences bcerefound when comparing the classes during function than during rest. (Supported by NIDR Grants DE05277 and DE0688 1. )
Force Transmission Lingual Orthodontic A. R. Brunette, and J. Matyas Orthodontic, Llentistr~
(From
S. J. Chaconas,
Res.
of
A. A. Caputo,
Posture and Intraoral Pressures Comparing Classes I, II, and Ill S. Y. Archer Universir)
and Biontaterials
J. Dent.
Characteristics Appliances
63: 257,
Sectiom.
UCLA
School
of
1984)
Until recently, lingual orthodontic appliances were considered to be impractical for a variety of reasons including difficulties with their design and construction. Improvements of lingual bracket design have led to the clinical utilization of this appliance. Several factors suggest that activation of lingual appliances are [sic] likely to produce force systems that differ from those produced by conventional fixed appliances. The purpose of this study was to visualize the results of forces applied on the lingual surfaces of teeth. Photoelastic models were constructed by embedding anatomic plastic teeth into a birefringent plastic. Malocclusions of the maxillary and mandibular arches were simulated that could be treated by either lingual or conventional fixed orthodontic appliances. The forces produced by both types of appliances were observed photoelastically. Forces applied by, leveling arch I+‘ires to the tooth posterior to the first premolars Mere similur in nature and intensi& ,for both linguul und conventional uppliunces. Also, similar stress patterns cc’ereobserved on the anterior and first premolar teeth for both arch w+res, but the intens&, was greater for the lingual appliance. Closing loop arch viaires produced more force on the incisor teeth by the lingual uppliunce than by the conventional appliance. The clinician must therejore be aware of the force d[fferences produced b> the lingual appliunce.
(From
and P. S. Vig
of Mat$and J. Dent.
Res.
und University,
63: 258,
of’Michigun
1984)
In a previous report comparing normal and Class II subjects, it was found that in both classes, posterior lingual forces varied with changes in head posture and were consistently higher than anterior lingual or labial forces. Anterior lingual forces decreased from head flexion to extension in both groups. The aim of this study was to establish if subjects with severe Class III skeletal relationships exhibited different patterns of pressure/head posture associations. Ten Class III subjects were compared with 10 Class I and I 1 Class II subjects using the pressure transducer technique previously described. Recordings were made in natural head position and at both -c_20” of extension and flexion during resting, swallowing, and speaking. Our results indicate: (I) Every subject shonaed pressure changes with changes in head position. (2) Statistical!\ signi3cunt differences within skeletal classes between transducer positions during ull tusks ic’cre found (a = .0.5). (3) Pressure duration during both speech and swallowing demonstrated the greatest dt#erence bctw.een skeletal classes. (4) When the factor of time was considered, Class I mean pressures were no longer the highest values. (5) Labiul recordings by Class 111subjects during rest in hemd extension were found to be significantly higher than Class I or Class II recordings. (6) More differences bcerefound when comparing the classes during function than during rest. (Supported by NIDR Grants DE05277 and DE0688 1. )