Asociación Mexicana de Ortopedia Maxilar A.C.

CEFALOMETRIA


Dr. Prof. Sabine Ruf
Ex. Prof. der Kieferothopädische Abteilung der Universität Gissen, Deutschland Director Prof. Dr..H.Panchez
Director:
Kieferorthopädische Abtailung der Universität Bern, Der Zwise. Klinik für Kieferorthopadie
Berna Zuisa
AMOM


Encuentro Internacional de Ortopedia Dentofacial Amom 2002 México-Alemania, Pto. Vallarta 27 Nov.- 1 Dic
7 Reunión Anual de Ortopedia Maxilar.

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The Herps Appliance in Modern Orthodontics

Introduction, clinical procedues, complications
Based on the "bite jumping" idea introduced by Kingsley in 1877, Emil Herbst developed his appliance in the early 1900s and presented it for the first time at the International Dental Congress in Berlin in 1909.
Twenty-five years later, in 1934, Herbst wrote about his experiences with the appliance in 3 articles.
After that time, very little was published about the subject until Pancherz reintroduced the
treatment method in 1979.

Initially, Pancherz used the Herbst bite jumping mechanism as a scientific tool in clinical-experimental orthodontic-orthopedic research. Through the years, however, it became obvious that the appliance is most useful in the therapy of severe Class II malocclusions. In comparison to conventional functional appliances (eg. activator, bionator, Fränkel), the Herbst appliance has several clinical advantages:
The appliances is fixed to the teeth, works continuously 24 hours a day, does not interfere with speech, and requires no patient compliance to attain the desired treatment effects.

Different clinical designs have been used since 1979 (simple banded anchorage system,
extended banded achorage system, casted maximum anchorage system). The clinical procedures required for Herbst appliance treatment will be explained step by step for every appointment. In comparison to the banded Herbst appliance, the cast splint appliance has many advantages: It has a precise fit on the teeth,
is strong and hygienic, and saves chair time because it is easy to insert and causes few clinical problems (no broken bands). Due to the higher laboratory costs of the cobaltchromium splints, acrylic splints have been advocated by some clinicians. However, acrylic splints break more easily and are less hygienic.

Complications during Herbst treatment are seldom, generally minor and easy to control.
All complications encountered during the last decades
as well as the way to manage them will be presented.

Treatment effects and possibilities Part I

In current dentofacial orthopedics, Herbst appliance therapy, followed by a conventional multibracket appliance treatment phase, is a most efficient 2-step approach in the management of severe Class II malocclusions. In the first step, Class II correction is accomplished with the Herbst appliance
(6 to 8 months of treatment).

When the appliance is placed at the start of Herbst treatment, the mandible is usually advanced to an incisal edge-to-edge position and the condyles are positioned on the top of the articular eminence. During the course of therapy, however, the condyles return to their original fossa position.

This is accomplished by adaptive dental and skeletal changes: posterior movement of the maxillary dentition and anterior movement of the mandibular dentition, stimulation of sagittal condylar growth in a more
favorable direction, and remodeling of the glenoid fossa.
The Herbst/multibracket appliance approach makes it possible to treat severe Class II malocclusions, which otherwise would have been very difficult, if not impossible, to handle without extraction or orthognathic surgery. Our clinical-experimental research throughout the years has shown that the Herbst appliance is most useful in the Class II subjects and situations described below.

Class II, Division 1 malocclusions
This malocclusion is the main indication for Herbst therapy. In cases with a narrow maxilla, it is advantageo us to combine the maxillary splint with a rapid maxillary expander or a quad-helix.
In most Class II, Division 1 cases, an undesirable side effect of the Herbst appliance is the proclination of the mandibular incisors. This effect is the result of anchorage loss, due to the forces exerted by the telescope mechanism on the anterior teeth. The incisor proclination is difficult to control independently of the anchorage system used. However, no increased incidence of mandibular anterior crowding could be found several years posttreatment despite a spontaneous uprighting of the teeth after Herbst therapy.

Class II, Division 2 malocclusions
The Herbst appliance is also very effective in Class II, Division 2 cases. In this type of malocclusion, the mandibular incisors (as well as the maxillary incisors) have a retroclined position. Therefore, the mandibular anchorage loss (proclination of the mandibular anterior teeth) during Herbst
treatment can be used advantageously to reduce the interincisal angle and to create a stable anterior

occlusion. This would be a prerequisite for the prevention of a deep bite relapse.
Class II malocclusions with a hyperdivergent jaw base relationship are generally considered to have an unfavorable growth pattern, making their treatment difficult. As the Herbst appliance has been shown to increase condylar growth in the therapeutically desired sagittal direction without resulting in a posterior (backward) rotation of the mandible, high-angle Class II subjects are good candidates
for successful Herbst therapy.

Retrognathic facial profile
The excessive facial profile convexity characteristic of Class II malocclusions is generally reduced by Herbst therapy. This effect is obvious both in subjects treated during growth and those treated at the end of
growth. The most favorable soft tissue profile changes are seen in Class II Malocclusions with a retrognathic chin, retruded lower lip, and protruded upper lip.

Maxillary anterior crowding
Besides the orthopedic effect on the mandible, the Herbst appliance has a pronounced high-pull headgear effect on the maxillary molars. During therapy, the molars are distalized and significantly intruded.
The headgear effect is most useful in gaining anterior space and relieving crowding in the maxillary
canine and incisor areas.

Treatment effects and possibilities Part II

Early vs. Late treatment For an efficient Class II correction removable funct
ional appliances depend upon simultaneous guidance of the vertical dentoalveolar development and are thus only indicated in the mixed dentition.
The ideal treatment period for the Herbst appliance in terms of efficiency, stability and minimal retention time is in the permanent dentition after the pubertal peak of growth.

Class II adults treated with either the Herbst appliance or with mandibular sagittal split osteotomy.

Comparable changes in sagittal maxillary/mandibular jaw base relationship and skeletal profile convexity were seen in the 2 groups at the end of treatment (after final tooth alignment with multibracket appliances. Furthermore, in comparison to surgery, Herbst treatment implies lower costs and lower risks for the patient without increasing total treatment time. Thus, with respect to age and growth
development, the following modified new concept for Class II therapy is proposed:

Growth adaptation in children, adolescents, postadolescents, and young adults Camouflage orthodontics in older adults
Surgical correction in older adults

TMJ patients
Our short- and long-term TMJ research using tomography and MRI has shown no adverse effects of H Uerbst treatment on the different hard and soft tissue joint structures. However, many cases have demonstrated that Herbst therapy results in a retrusion of the articular disc. This effect can be used in the therapy of Class II malocclusions with milder forms of anterior disc displacement to attain a
reduction of the disc malposition.





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