Herbst Appliance: How It Works, Effects and Timing

The Herbst appliance is the best-known fixed functional appliance for Class II malocclusion. It holds the mandible forward 24 hours a day, without relying on the patient to wear it, and corrects a large overjet in a matter of months. What it actually does to the mandible is a separate question, and the literature answers it with more nuance than the before-and-after photos suggest. This guide covers the mechanism, the main designs, indications and timing relative to growth, what meta-analyses report on skeletal and dental effects, the side effects to watch, and the questions patients ask most often.

What is a Herbst appliance?

A Herbst appliance is a bite-jumping device: on each side, a telescope (a tube and a plunger) connects the upper and lower arches and keeps the mandible advanced. The patient can open and close, because the plunger slides in the tube, but cannot close back into the Class II position.

The appliance is named after Herbst; its modern use goes back to Hans Pancherz. In his 1979 controlled study, ten growing boys with Class II division 1 malocclusion were treated for 6 months and compared with ten untreated boys: normal occlusal relationships were reached in all treated patients, SNA decreased slightly, SNB and mandibular length increased, and lower facial height increased while the mandibular plane angle stayed unchanged (Pancherz, 1979, Am J Orthod, PubMed).

In the D.U. courses behind GS Ortho, the Herbst belongs to the fixed mandibular advancers, also called non-compliance Class II correctors or "fixed activators", alongside spring devices such as the Forsus. In Lautrou’s classification of functional appliances, it is the typical "stop" device (a rigid connector). One course criterion applies to all of them before placement: when the patient postures the mandible forward, a good Class I occlusion must be obtained.

Herbst appliance designs

The telescopes stay the same; the anchorage changes.

A few points of comparison:

• In a retrospective study of 114 patients, complications did not differ significantly between a removable mandibular acrylic splint and a cantilever Herbst, nor between crowns and bands; one telescope system had more complications than another (Kanuru et al., 2017, J Contemp Dent Pract, PubMed). Different manufacturers’ telescopes are not interchangeable in terms of breakage.
• With the CBJ, Class II correction in 26 patients came from a 2.9 mm apical base change, 1.5 mm of distal movement of the upper molars and 1.1 mm of mesial movement of the lower molars; the vertical force of the telescopes could tip the lower molars mesially (Moro et al., 2009, Angle Orthod, PubMed).
• Adding miniscrews to an acrylic splint Herbst reduced lower incisor proclination by a mean of 5.49° in a meta-analysis of 4 studies, with a larger mandibular skeletal effect, but at a very low level of confidence (Al-Dboush et al., 2021, Orthod Craniofac Res, PubMed).

Indications and timing relative to growth

Who is the Herbst for?

The typical indication is a Class II division 1 with mandibular retrusion in a growing patient: increased overjet, Class II molars, and a mandible that is short or positioned backward. As with any functional appliance, the diagnosis comes first. Check where the discrepancy comes from with SNA, SNB and ANB, and read the vertical pattern with the mandibular plane angle. Our free cephalometric analysis tool calculates these angles from the landmarks you place.

The courses contraindicate activators in true hyperdivergence, but Boileau considers the Herbst "less contraindicated" in a hyperdivergent tendency, with caution if it is severe; in a hypodivergent patient with a deep curve of Spee, he recommends leveling before placement. The question remains open for moderately hyperdivergent patients. In a retrospective study of 42 patients treated with a cast splint fixed functional appliance, hypodivergent and hyperdivergent patients showed similar skeletal and dentoalveolar effects; lower incisor protrusion was more pronounced in the hypodivergent group (Hourfar et al., 2023, Clin Oral Investig, PubMed).

When to start

Our sources agree on orthopedics around the pubertal growth peak, not on the exact window:

• Pancherz (as taught in the D.U.): from 2 years before to 2 years after the peak.
• D.U. course: optimal conditions for Class II orthopedics from the peak to one year after it, the ascending phase of the peak giving the best skeletal response.
• Boileau: at the peak or within the year that follows, finishing the orthopedic phase when the permanent teeth are in place, with a minimal interval before full fixed appliances.
• Lyon school (EMC): an opinion favoring the mixed dentition, between 7 and 10 years, based on series without control groups.

The literature supports timing around the peak for functional appliances in general. In a systematic review of 22 controlled studies, the supplementary mandibular growth was significantly larger when functional treatment was performed at the pubertal peak (Cozza et al., 2006, Am J Orthod Dentofacial Orthop, PubMed). Skeletal age is a better guide than calendar age: our article on cervical vertebral maturation (in French) explains how to stage it.

Adults

In non-growing patients, a meta-analysis of 11 non-randomized studies found that mandibular propulsion appliances normalized the Class II mainly through dentoalveolar changes (labial movement of the lower incisors, some lingual inclination of the upper incisors), with small mandibular changes, the largest being with the Herbst (González Espinosa et al., 2020, Eur J Orthod, PubMed). In an adult, a Herbst is a dental camouflage tool more than an orthopedic one, and the alternative of orthognathic surgery (in French) belongs in the discussion.

Activation protocol and treatment duration

Boileau’s protocol, as recorded in our knowledge base:

1. Decompensate the occlusion first (incisor inclination, arch form), so that the mandible can actually be advanced into Class I.
2. Initial advancement of 3 to 4 mm at most.
3. Reactivation by 2 to 3 mm shims (tubes) added on the plunger every 6 weeks, until overcorrection or an incisal edge-to-edge relationship.
4. Active treatment of about 6 to 8 months, followed by fixed appliances to finish the occlusion.

The literature reports similar durations: a mean of 8.0 months of Herbst treatment in one consecutive series (VanLaecken et al., 2006, Am J Orthod Dentofacial Orthop, PubMed), and 4 to 12 months across the fixed Class II correctors included in a systematic review (Phuong et al., 2019, Eur J Orthod, PubMed).

Stepwise or single-step? Stepwise advancement gave slightly more ANB reduction and slightly less lower incisor proclination than maximal bite jumping in a meta-analysis of randomized trials, with weak evidence and small differences (Knösel et al., 2020, J Orofac Orthop, PubMed).

Skeletal vs dentoalveolar effects

The Herbst corrects Class II reliably; the debate is about how much of the correction is skeletal.

What Pancherz described

The knowledge base summarizes Pancherz’s findings (Boileau; EMC): during wear, mandibular lengthening of about three times that of untreated controls, restraint of maxillary growth, intrusion and distal movement of the upper molars, proclination of the lower incisors that is difficult to control, and a clockwise tilt of the occlusal plane. The EMC gives about 2 mm of maxillary dentoalveolar retraction without incisor tipping, and about 2 mm of mesial movement of the mandibular dentition with roughly 6° of lower incisor proclination, 75% of which relapses within 12 months of removal. Boileau adds that the overcorrected Class I relapses until the occlusion settles, and that at about 7 years of follow-up a large part of the mandibular gain is temporary.

What meta-analyses report

• Fixed functional appliances versus untreated controls: in 9 prospective studies (244 treated patients), SNA decreased slightly (−0.83°/year), SNB increased slightly (+0.87°/year) and ANB decreased moderately (−1.74°/year); the authors concluded that the effects "seem to be mainly dentoalveolar rather than skeletal" (Zymperdikas et al., 2015, Eur J Orthod, PubMed).
• Herbst specifically: in 12 controlled trials, the Herbst was effective during active treatment, with clear dental changes and a skeletal change in mandibular length (Co-Gn); long-term evidence was insufficient (Yang et al., 2015, Eur J Orthod, PubMed).
• Herbst versus Twin Block: in 12 studies (574 patients), the Herbst produced a greater increase in mandibular body length and more lower incisor change, while SNA, SNB, ANB, overjet and overbite changes were similar (Xu et al., 2024, BMC Oral Health, PubMed).
• Rate of mandibular growth: the Herbst had the highest coefficient of efficiency (0.28 mm per month) in a 2006 review (Cozza et al., 2006), but not in a 2025 review of 90 studies (Venkatesan et al., 2025, J Orofac Orthop, PubMed).

Some cohorts report a large skeletal share: 16 months after removal in 32 patients, skeletal change made up 85% of the net overjet correction, but the net gains were only 2.7 mm of overjet and 1.0 mm of mandibular advancement, the molars having relapsed from an overcorrected Class III to Class I (VanLaecken et al., 2006). The honest summary is that the Herbst produces a real but modest skeletal effect, on top of a substantial dentoalveolar one.

Stability

The Herbst is the only fixed functional appliance with enough long-term data for a meta-analysis. Mean post-treatment relapse was 0.2° for ANB (12.4% of the treatment change), 1.8 mm for overjet (26.2%) and 1.4 mm for overbite in Class II division 1 (44.7%), with good overall stability despite a low evidence level (Bock et al., 2015, Eur J Orthod, PubMed). Relapse could not be predicted for an individual patient in an earlier review (Bondemark et al., 2007, Angle Orthod, PubMed). Boileau ties long-term stability to a well-interdigitated final occlusion and to the correction of lip and tongue dysfunctions.

Side effects and complications

Lower incisor proclination

The lower dentition anchors the forward pull on the mandible, so the lower incisors procline. Periodontal findings:

• In 98 children with a mean proclination of 8.9° (range 0.5° to 19.5°), recession developed or worsened on 3% of lower incisors, with no relation to the amount of proclination (Ruf et al., 1998, Am J Orthod Dentofacial Orthop, PubMed).
• In 259 Herbst-multibracket patients, the mean increase in labial recession was 0.1 mm, again without association with incisor position changes; the authors note that individual predisposition or excessive changes may still lead to recession (Südwasser et al., 2021, J Orofac Orthop, PubMed).
• A meta-analysis of 5 non-randomized studies found negligible changes in buccal cortical thickness, vertical alveolar bone height and recession, but recommended periodic periodontal assessment given the patients’ young age (Kumar et al., 2024, Int J Clin Pediatr Dent, PubMed).
• In 14 patients followed for 32 years, proclined lower incisors generally rebounded; minor recessions appeared in a few patients, mostly on bodily displaced or crowded teeth (Pancherz and Bjerklin, 2014, Am J Orthod Dentofacial Orthop, PubMed).

Reassuring on average, but not a reason to ignore the lower incisor: check the periodontium and symphysis first, and watch the IMPA.

Other effects

• Breakages and emergency visits: according to a systematic review, most Herbst patients, whatever the design, will have fractures or loosening that require extra appointments (low-level evidence) (Phuong et al., 2019).
• Temporomandibular joint: a meta-analysis of 4 studies found no increase in temporomandibular disorders after Herbst treatment (odds ratio 0.74, 95% CI 0.33-1.68) (Minervini et al., 2024, BMC Oral Health, PubMed).
• Root resorption: clinically minor shortening of posterior roots in 20 cast splint Herbst patients (Çoban et al., 2021, J Orofac Orthop, PubMed).
• Vertical: the clockwise tilt of the occlusal plane described by Pancherz; in hyperdivergent patients, Boileau recommends short Class II elastics in retention after the Herbst.

In practice

1. Confirm a Class II with a mandibular component: ANB, SNA, SNB and the profile, not the molar relationship alone.
2. Stage skeletal maturity and aim for the peak or the year after it; in an adult, discuss camouflage and surgery openly.
3. Read the vertical pattern; be cautious in severe hyperdivergence and level a deep curve of Spee first in hypodivergent patients.
4. Assess the lower incisors and periodontium (inclination, gingival biotype, symphysis) before choosing the anchorage.
5. Decompensate the arches so that the forward posture gives a Class I.
6. Advance by 3 to 4 mm at first, then by 2 to 3 mm every 6 weeks to overcorrection, over about 6 to 8 months.
7. Plan the finishing phase and retention, and explain to the family that part of the correction is dental and part relapses.

Frequently asked questions

Does the Herbst appliance hurt?

Published data on discomfort are limited. A systematic review of fixed Class II correctors found low-level evidence and too much heterogeneity for pooled figures; with Herbst appliances, the most consistent finding was frequent breakage or loosening requiring extra visits (Phuong et al., 2019). For a personal case, ask the treating orthodontist what to expect.

Can you eat and talk normally with a Herbst?

The appliance is fixed and worn day and night, but the telescopes slide, so the mouth can open and close; the device does not block jaw movements (Minervini et al., 2024). The studies we read give no reliable figures on eating or speech adaptation. Patients should ask their orthodontist which foods to avoid to limit breakage.

How long do you wear a Herbst appliance?

Typically about 6 to 8 months of active treatment in the protocols we cite, with a range of 4 to 12 months for fixed Class II correctors in the literature. It is usually followed by braces to finish the occlusion, and by retention.

Does the Herbst make the lower jaw grow?

It increases mandibular length during treatment compared with untreated controls, but meta-analyses describe the overall correction as mainly dentoalveolar, and part of the mandibular gain is temporary. The skeletal effect is larger around the pubertal growth peak and small in adults.

Herbst or removable functional appliance?

The Herbst does not depend on cooperation, its main advantage. Skeletal effects were broadly similar to the Twin Block in a 2024 meta-analysis, with more lower incisor change with the Herbst. Cooperation, the vertical pattern and the lower incisors guide the choice.

With GS Ortho

In GS Ortho, AI places 29 landmarks on the lateral cephalogram for you to check and correct before you validate the Steiner and Tweed analyses, so ANB, SNB, FMA and IMPA are available before a Herbst is discussed. The diagnostic studio guides the case through 12 panels, from the clinical examination and photos to the treatment plan of the same patient. When a case sits between orthopedics, camouflage and surgery, "Request an opinion" sends the question, with the panel attached, to a colleague or supervisor you choose; the answer stays in the record. Patient data are hosted at your practice. The GS Ortho interface is currently available in French.

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