---
title: "Facial Growth Modification Orthodontics UK"
url: https://virtualconsultant.online/guides/facial-growth-modification-orthodontics-uk
description: "Facial growth modification uses appliances like twin blocks in growing children to correct jaw discrepancies before they need surgery."
updated: 2026-08-27T00:00:00Z
publisher: Virtual Consultant Online
---

Growth Modification

Twin Block

Facemask

RME

Interceptive

# Facial Growth Modification in Orthodontics

Facial growth modification uses orthodontic appliances such as twin blocks, Herbst appliances, and reverse-pull facemasks in growing children to redirect, restrain, or stimulate jaw growth. Used at the right age, these appliances can significantly reduce the severity of jaw discrepancies and in many cases reduce or eliminate the need for corrective jaw surgery in adulthood. This guide explains how growth modification works, which appliances are used, and what parents and patients should realistically expect.

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## What is facial growth modification?

Facial growth modification is the use of orthodontic appliances to alter the size, position, or direction of growth of the jaws during the period of active facial development in childhood and adolescence. The principle is that growing bone — unlike mature adult bone — responds to prolonged mechanical force by remodelling at sutures, condyles, and periosteum. Appliances can therefore guide jaw growth in a desired direction if used during the relevant growth window. Growth modification is distinct from tooth movement: it targets the skeletal framework rather than the teeth themselves, though the two are often combined in a phased treatment plan.

## How do twin block and Herbst appliances treat Class II jaws?

Class II Division 1 malocclusion — where the lower jaw is underdeveloped or positioned too far back relative to the upper jaw — is the most common indication for mandibular advancement appliances. The twin block, developed by William Clark and widely used in UK practice, consists of upper and lower acrylic blocks that lock together when the patient bites, holding the lower jaw in a forward position during all jaw activity including eating and speaking. Worn full-time for 9 to 12 months, twin blocks stimulate adaptive remodelling at the mandibular condyle and glenoid fossa, physically lengthening and repositioning the lower jaw. The Herbst appliance is a fixed alternative that achieves the same mandibular repositioning without relying on patient compliance, as it is cemented in place. Both are most effective during the pubertal growth spurt.

## How does a reverse-pull facemask treat Class III jaws?

Where the problem is an underdeveloped upper jaw rather than an overgrown lower jaw — or a combination of both — a reverse-pull facemask (protraction facemask) applies forward traction to the upper jaw. The appliance consists of a forehead and chin rest connected by a central frame, with elastic hooks that attach to a palatal expander bonded to the upper teeth. Worn 12 to 14 hours daily, it pulls the upper jaw forward and downward, stimulating growth at the circummaxillary sutures. It is most effective between ages 8 and 10, before these sutures begin to ossify. Earlier treatment (age 6 to 7) is possible but anchorage in the mixed dentition can be challenging. After age 12, response to facemask therapy diminishes significantly.

## What does rapid maxillary expansion (RME) do?

Rapid maxillary expansion uses a fixed palatal expander to widen the upper jaw by separating the mid-palatal suture, which remains mobile until late adolescence (early to mid-20s in females, mid-20s or later in males). RME is used to correct posterior crossbite caused by a narrow upper arch, to create space for crowded teeth without extractions, and as a component of facemask therapy for Class III treatment. There is evidence that successful palatal expansion in children can improve nasal airway resistance, which may benefit mouth breathers. Expansion is typically rapid (one quarter-turn of the screw per day for two to four weeks) followed by a retention period of four to six months to allow bone to consolidate across the opened suture.

## What does headgear do for maxillary restraint?

Orthodontic headgear applies rearward (and sometimes downward) force to the upper jaw to restrain forward maxillary growth in Class II cases where the upper jaw is genuinely protrusive rather than the lower jaw being deficient. It attaches to upper molar bands and connects to a neck pad or head cap, applying force via elastic traction. Headgear has become less commonly prescribed in UK practice than previously, partly due to compliance challenges and partly because functional appliances address the more common scenario of mandibular deficiency rather than maxillary excess. Safety considerations — headgear should always incorporate a safety release mechanism — are important, and it should only be used under orthodontic supervision.

## When is the optimal timing for growth modification?

The pubertal growth spurt is the most important window for mandibular growth modification. Activating a twin block or Herbst appliance before or at the peak of the growth spurt produces significantly better skeletal outcomes than starting after peak growth has passed. Clinicians use several tools to identify growth status: hand-wrist radiographs (less used now due to radiation exposure), and cervical vertebral maturation (CVM) assessment using the lateral cephalometric radiograph already taken as part of orthodontic records. CVM identifies five stages of maturation based on the shape and concavity of the lower cervical vertebrae — stage 3 (CVM3) represents peak growth velocity and is the ideal time to begin mandibular advancement. CVM assessment is now standard practice in UK specialist orthodontics.

## What can growth modification realistically change, and what can't it change?

Growth modification can meaningfully change the jaw relationship in growing patients, reducing overjet, improving chin position, and reducing the skeletal discrepancy that would otherwise require surgery in adulthood. However, it cannot completely eliminate a genetic growth pattern — a patient genetically programmed to have a significant Class III skeletal pattern will continue to grow that way despite early treatment, though usually to a lesser degree. Growth modification does not change facial bones in adults, whose sutures are fused and whose condylar growth is complete. The improvements gained in childhood may partially relapse if adverse growth continues through adolescence, which is why comprehensive fixed braces are almost always needed after a phase of growth modification.

## Is growth modification available on the NHS or privately?

NHS orthodontic treatment is available for children under 18 meeting IOTN eligibility thresholds. Functional appliances, facemasks, and palatal expanders are all available through NHS specialist orthodontic services. However, NHS waiting lists can mean that referral at the optimal growth window is delayed; parents should ask their child's GDP to refer as early as age 8 to 9 if a jaw discrepancy is present, rather than waiting until the permanent dentition is fully erupted. Private orthodontic practices can typically offer faster assessment and treatment start, with no waiting list constraint, which can be critical when timing is important. The cost of functional appliance therapy typically ranges from £1,500 to £3,000 privately, depending on complexity.

## Useful related pages

[Functional Appliances UK](https://virtualconsultant.online/guides/functional-appliances-uk)

[Class III Correction in Children UK](https://virtualconsultant.online/guides/class-iii-correction-children-uk)

[Twin Block Appliance UK](https://virtualconsultant.online/guides/twin-block-appliance-uk)

[Palatal Expander UK](https://virtualconsultant.online/guides/palatal-expander-uk)

[Jaw Surgery and Orthodontics UK](https://virtualconsultant.online/guides/jaw-surgery-orthodontics-uk)

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.

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### Frequently Asked Questions

What age is best to start growth modification treatment?

It depends on the type of jaw problem. For Class II mandibular deficiency, the ideal time is around the pubertal growth spurt — typically age 10 to 12 for girls and 11 to 13 for boys, timed using cervical vertebral maturation assessment rather than chronological age alone. For Class III maxillary deficiency with a facemask, earlier is better: age 8 to 10 is the optimal window before the circummaxillary sutures begin to fuse. For palatal expansion, treatment is possible from the mixed dentition through to the late teens, but becomes progressively more difficult and less effective as skeletal maturation advances.

Will a twin block stop my child needing jaw surgery?

In many cases, yes — or it will at least reduce the severity of any jaw discrepancy significantly, making surgery less likely or simpler if it is still needed. Research consistently shows that twin block and Herbst treatment produce genuine skeletal changes in growing patients, not just dental movement. However, genetics plays a significant role, and children with a strong skeletal Class II pattern may still benefit from jaw surgery assessment in adulthood if residual discrepancy remains after growth. The aim of early treatment is to maximise growth potential, not to guarantee surgery avoidance.

Is the twin block appliance painful?

The twin block is not painful but causes considerable initial discomfort and adaptation difficulty in the first one to two weeks. Speech is significantly affected initially, eating requires practice, and the jaw feels strained from being held in an unfamiliar forward position. Most children adapt fully within two to three weeks. Thereafter the appliance should not cause pain, though some soreness after adjustments to the acrylic biting surfaces is normal. Persistent pain should be reported to the orthodontist.

How does cervical vertebral maturation work?

Cervical vertebral maturation (CVM) is a method of estimating skeletal growth stage using the lateral cephalometric X-ray taken during orthodontic assessment. The shape and concavity of the lower cervical vertebrae — specifically C2, C3, and C4 — change predictably as skeletal maturation progresses. A patient at CVM stage 3 is at or near peak growth velocity, which is the ideal time for mandibular advancement therapy. The method was developed to provide a radiation-free alternative to hand-wrist radiographs and is now routinely used by specialist orthodontists in the UK.

Can adults have growth modification treatment?

No. Growth modification appliances work by influencing bone remodelling at sutures and condyles during active growth. Once growth is complete — typically around age 16 to 18 for females and 18 to 21 for males, though there is significant individual variation — these sites are no longer responsive to functional appliance forces. In adults, skeletal jaw discrepancies can only be corrected through orthognathic surgery. Some tooth movement camouflage is possible in adults without surgery, but it masks rather than corrects the underlying skeletal problem.

What is the difference between a facemask and a twin block?

These appliances address different jaw problems. A twin block advances the lower jaw to correct Class II malocclusion where the lower jaw is underdeveloped or positioned too far back. A reverse-pull facemask pulls the upper jaw forward to correct Class III malocclusion where the upper jaw is underdeveloped or positioned too far back. They work on opposite jaws and use different mechanisms. Occasionally, some Class III patients may benefit from both — a palatal expander to widen the upper arch and facilitate facemask therapy, used alongside functional appliances.

Does rapid maxillary expansion help with breathing?

There is reasonable evidence that successful RME in children can reduce nasal airway resistance and improve nasal breathing by increasing the internal nasal cavity width. This can be beneficial for children who predominantly breathe through their mouth due to a narrow nasal airway associated with a narrow palate. However, RME is not a treatment for all causes of mouth breathing — adenoid hypertrophy, allergic rhinitis, and other ENT conditions require their own management. If mouth breathing is present alongside a narrow palate, discussing with both the orthodontist and the child's GP or ENT specialist is advisable.

How long does growth modification treatment take?

Most growth modification appliances such as twin blocks or facemasks are worn for 9 to 14 months to achieve the desired skeletal change. This is typically followed by a phase of comprehensive fixed braces to align the teeth once the jaw relationship has improved, adding a further 18 to 24 months. In total, a two-phase treatment plan spanning growth modification and later fixed braces commonly takes three to four years from start to finish, though the child is not in active appliance wear for the entire period.

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Citation details

Title Facial Growth Modification Orthodontics UK

Publisher Virtual Consultant Online

Published 2024-06-01

Updated 2026-08-27

URL [https://staging.virtualconsultant.online/guides/facial-growth-modification-orthodontics-uk](https://staging.virtualconsultant.online/guides/facial-growth-modification-orthodontics-uk)