Hans Pancherz

The mechanism of Class II correction in Herbst appliance treatment: A cephalometric investigation

Sagittal skeletal and dental changes contributing to Class II correction in Herbst appliance treatment were evaluated quantitatively on lateral roentgenograms. The material consisted of forty-two Class II. Division 1 malocclusion cases. Twenty-two of these were treated with the Herbst appliance for 6 months. The other twenty cases served as a control group. The results of the investigation revealed the following: (1) Bite jumping with the Herbst appliance resulted in Class 1 occlusal relationships in all treated cases. (2) The improvement in occlusal relationships was about equally a result of skeletal and dental changes. (3) Class II molar correction averaging 6.7 mm. was mainly a result of a 2.2 mm. increase in mandibular length, a 2.8 mm. distal movement of the maxillary molars, and a 1.0 mm. mesial movement of the mandibular molars. (4) Overjet correction averaging 5.2 mm. was mainly a result of a 2.2 mm. increase in mandibular length and a 1.8 mm. mesial movement of the mandibular incisors. (5) Anterior condylar displacement (0.3 mm.), redirection of maxillary growth (0.4 mm.), and distal movement of the maxillary incisors (0.5 mm.) were of minor importance in the improvement in molar and incisor relationships seen. (6) A direct relationship existed between the amount of bite jumping at the start of treatment and the treatment effects on the occlusion and on mandibular growth. For a maximal treatment response, it is suggested that the Herbst appliance be constructed with the mandible jumped anteriorly as much as possible, namely, to an incisal edge-to-edge position. The clinician should be aware of the dental changes occurring during Herbst appliance treatment and make sure that these changes are not incongruous with his over-all treatment goal.

Treatment of class II malocclusions by jumping the bite with the Herbst appliance. A cephalometric investigation.

The purpose of this study was to investigate the effect of continuous bite jumping with the Herbst appliance on the occlusion and craniofacial growth. The material consisted of twenty growing boys with Class II, Division 1 malocclusion. Ten of the boys were treated with the Herbst appliance for 6 months. The other ten boys served as a control group. Dental casts, profile roentgenograms, and TMJ radiographs were analyzed before and after 6 months of examination. The following treatment results were found: 1. Normal occlusal conditions occurred in all patients. 2. Maxillary growth may have been inhibited or redirected. The SNA angle was reduced slightly. 3. Mandibular growth was greater than average. The SNB angle increased. 4. Mandibular length increased, probably because of condylar growth stimulation. 5. Lower facial height increased. The mandibular plane angle, however, remained unchanged. 6. The convexity of the soft- and hard-tissue profile was somewhat reduced.

The Herbst appliance—Its biologic effects and clinical use

The purpose of this article is to survey the Herbst bite-jumping method. An outline of appliance design and appliance construction is given. The effects of the treatment method on the dentofacial complex and on the masticatory system have been analyzed with the aid of dental casts, cephalometric roentgenograms, and electromyographic registrations from the masticatory muscles. The use and effectiveness of the Herbst appliance in the treatment of Class II malocclusions are exemplified by clinical cases, some of which were followed for 5 years after treatment. The Herbst appliance is most effective in the treatment of Class II malocclusions, provided it is used as indicated. Thus, the appliance must be limited to growing persons only. The treatment method should not be looked upon as a last resort to be used only when other treatment approaches have failed. Treatment prognosis is best in subjects with a brachyfacial growth pattern. Unfavorable growth, unstable occlusal conditions, and persisting oral habits after treatment are potential risk factors for occlusal relapses. As treatment with the Herbst appliance is performed during a relatively short period, the hard and soft tissues (teeth, bone, and musculature) would need some time for adaptation to the new mandibular position after the appliance is removed. Posttreatment retention as a routine with a removable functional appliance is therefore recommended.

Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: A prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation

The aim of this prospective study was to analyze and compare the temporomandibular joint adaptive mechanisms in 25 adolescent and 14 young adult Class II malocclusions treated with the Herbst appliance. Temporomandibular joint remodeling was analyzed by magnetic resonance imaging. In each subject, 4 magnetic resonance images of both temporomandibular joints were available: before treatment, at the start of treatment (when the Herbst appliance was placed), during treatment (6 to 12 weeks after appliance placement), and after treatment (when the appliance was removed). Furthermore, effective temporomandibular joint changes (the sum of condylar remodeling, fossa remodeling, and condyle-fossa relationship changes) were analyzed with the aid of lateral cephalometric radiographs from before and after treatment. All subjects were treated to Class I or overcorrected Class I dental arch relationships, and their mandibles became significantly (P <.001) more prognathic. After 6 to 12 weeks of Herbst treatment, signs of condylar remodeling were seen at the posterosuperior border in 48 of the 50 adolescent condyles and in 26 of the 28 young adult condyles. Bilateral remodeling of the mandibular ramus could be detected in 1 adolescent and 2 young adult patients. Signs of glenoid fossa remodeling at the anterior surface of the postglenoid spine were noted in 36 adolescent and 22 young adult temporomandibular joints. Effective temporomandibular joint changes during treatment were more horizontally directed and larger in both adolescents and young adult patients treated with the Herbst appliance than in an untreated group of subjects with ideal occlusion (Bolton standards). The increase in mandibular prognathism accomplished by Herbst therapy in both adolescents and young adults seems, in particular, to be a result of condylar and glenoid fossa remodeling. Because the Herbst appliance is most successful in Class II patients also at the end of the growth period, the treatment method could be an alternative to orthognathic surgery in borderline skeletal Class II cases. Magnetic resonance imaging renders an excellent opportunity to visualize the temporomandibular joint remodeling growth processes.

A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment

The purpose of this investigation was to evaluate cephalometrically the mechanism of anteroposterior occlusal changes in activator treatment. The analysis used made it possible to relate alterations in the occlusion to sagittal skeletal and dental changes in the maxilla and mandible. The sample consisted of thirty Class II, Division 1 malocclusion cases treated successfully with activators during an average time period of 32 months. Before- and after-treatment head films in centric occlusion were analyzed. The occlusal line (OL) and occlusal line perpendicular (OLp) through sella were used for reference. Linear measurements were performed parallel to OL. The following results were found: (1) The improvement in occlusal relationships in the molar and incisor segments was about equally a result of skeletal and dental changes. (2) Overjet correction averaging 5.0 mm was a result of 2.4 mm more mandibular growth than maxillary growth, a 2.5 mm distal movement of the maxillary incisors, and a 0.1 mm mesial movement of the mandibular incisors. (3) Class II molar correction averaging 5.1 mm was a result of 2.4 mm more mandibular growth than maxillary growth, a 0.4 mm distal movement of the maxillary molars, and a 2.3 mm mesial movement of the mandibular molars. (4) When the findings were compared with longitudinal records of persons with normal occlusion (Bolton standards), activator treatment seemed to inhibit maxillary growth, move the maxillary incisors and molars distally, and move the mandibular incisors and molars mesially. Mandibular growth appeared not to be affected by activator treatment.

The headgear effect of the herbst appliance: A cephalometric long-term study

The short- and long-term effects of the Herbst appliance on the maxillary complex were evaluated in 45 patients who had Class II malocclusions. The patients were followed for 6.4 years (5 to 10 years) after treatment. Lateral cephalograms from before and after 7 months of treatment, 6 months, and 6.4 years after treatment were analyzed. During Herbst treatment the upper molars were distalized in 96% of the subjects (maximum 4.5 mm), and the upper molars were intruded in 69% of the subjects (maximum 3.5 mm). The maxillary occlusal plane was opened in 82% of the subjects (maximum 7.5 degrees). Sagittal maxillary jaw base position seemed unaffected by therapy. A downward tipping of the palatal plane was noted in 47% of the subjects (maximum 2 degrees). During the first 6 months after therapy most of the treatment changes reverted. During the following 5.9 years after treatment, normal growth developmental changes prevailed: the upper molars moved mesially, and the teeth extruded, the occlusal plane closed, the maxilla grew anteriorly, and the palatal plane tipped downward. In conclusion the Herbst appliance exhibited a pronounced high-pull headgear effect on the maxillary complex. Without proper retention, however, the effect seemed to be of a temporary nature.

Does orthodontic proclination of lower incisors in children and adolescents cause gingival recession

In this investigation we sought to assess the effect of orthodontic proclination of lower incisors in children and adolescents with respect to the possible development of gingival recession. Ninety-eight children with a mean +/- SD start-of-treatment age of 12.8 +/- 1.4 years, treated with the Herbst appliance, were surveyed, for a total of 392 lower incisors. Lateral head films, dental casts and intraoral photographs were analyzed with respect to the degree of orthodontic proclination, crown height, and gingival recession. In all subjects, Herbst treatment resulted in varying degrees of lower-incisor proclination (mean = 8.9 degrees, range = 0.5 degrees to 19.5 degrees). In 380 of the surveyed teeth (97%), either no recession developed or preexisting recession remained unchanged during Herbst therapy. In only 12 teeth (3%) did recession develop or preexisting recession deteriorate during treatment. No interrelation was found between the amount of incisor proclination and the development of gingival recession. In conclusion, orthodontic proclination of lower incisors in children and adolescents seems not to result in gingival recession.

The nature of class II relapse after herbst appliance treatment: A cephalometric long-term investigation

The purpose of this investigation was to assess the number of, and the interrelation between, skeletal and dental components that contribute to Class II relapse after Herbst treatment. A comparison was made between 15 relapse and 14 stable cases at least 5 years after treatment. Lateral cephalograms taken before and immediately after Herbst treatment, as well as 6 months and 5 to 10 years after treatment, were analyzed. The results revealed that relapse in the overjet and sagittal molar relationship resulted mainly from posttreatment maxillary and mandibular dental changes. In particular, the maxillary incisors and molars moved significantly (p less than 0.05) to a more anterior position in the relapse group than in the stable group. The interrelation between maxillary and mandibular posttreatment growth was favorable and did not contribute to the occlusal relapse. It is hypothesized that the main causes of the Class II relapse in patients treated with the Herbst appliance were a persisting lip-tongue dysfunction habit and an unstable cuspal interdigitation after treatment.

Dentoskeletal effects and facial profile changes in young adults treated with the Herbst appliance

This prospective Herbst study analyzed the sagittal dental and skeletal changes contributing to Class II correction in young adults. Additionally, the alteration in skeletal and soft tissue convexity occurring during treatment was assessed. Early adolescent subjects in the permanent dentition who had been treated with the Herbst appliance were used for comparison. Lateral headfilms from before and after an average treatment period of 8.5 months for the young adults and 7.1 months for the adolescents were evaluated. All adult and adolescent subjects were treated to either Class I or overcorrected Class I occlusal relationships. In both groups the improvement in sagittal incisor and molar relationships was achieved more by dental changes than by skeletal ones. The amount of skeletal change contributing to overjet and molar correction was smaller in the young adult group (22% and 25%, respectively) than in the early adolescent group (39% and 41%, respectively). Skeletal and soft tissue facial profile convexity was reduced in adults and adolescents. Facial profile improvement did not differ between the two groups. The results of this study revealed that the Herbst appliance is most effective in the treatment of Class II malocclusion in young adults. It is suggested that this treatment method could be an alternative to orthognathic surgery in borderline Class II cases.

The effects, limitations, and long-termdentofacial adaptations to treatment with the herbst appliance

The purpose of this article is to summarize the existing scientific data with respect to the short- and long-term effects of the Herbst appliance on the occlusion and on the maxillo/mandibular complex. The article also discusses the treatment indications and possible treatment limitations. The Herbst method is most effective in the treatment of Class II malocclusions. Long-term stability seems to be dependent on a stable cuspal interdigitation. Marked mandibular morphological changes occur during therapy and sagittal condylar growth is increased. Posttreatment, most of the mandibular morphological changes revert and no long-term influence of Herbst treatment on mandibular growth can be verified. The appliance effect on the maxillary complex can be compared with that of a high-pull headgear. Without proper retention, however, this effect is of a temporary nature. Herbst treatment is especially indicated in the permanent dentition at or just after the pubertal peak of growth. Mixed dentition treatment is not recommended, as a stable cuspal interdigitation after therapy is difficult to achieve and relapses are prone to occur. In the nongrowing patient, the appliance should be used with great caution.