The orthodontic–paediatric interface. Part 2

Interceptive orthodontics

Class II

Class II relationships often present with increased overjets, lower lip traps and habits. Interception of habits has been described in Part 1 of this series.² In these cases, the use of a mouthguard should be emphasized to reduce the risk of dental trauma.

A Cochrane review in 2018 identified some benefit for interceptive early treatment of a Class II relationship, in terms of reducing the incidence of new incisal trauma.³ Additionally, early treatment is sometimes indicated if bullying is a particular concern. Seehra and colleagues have previously described how bullying was significantly associated with a Class II division 1 malocclusion and an increased overjet and overbite.⁴ Referral to orthodontics at the optimal time can enable functional appliance treatment to be commenced if indicated. Retention of a twin block appliance is often gained using Adam's cribs on the upper and lower first premolars and molars. For this reason, the eruption of these teeth is generally preferred before starting functional treatment. However, where indicated, modifications can be made, particularly in cases of hypodontia and traumatic loss of teeth (Figure 1). Despite the aforementioned indications, early treatment can be challenging in terms of both maintaining cooperation and retaining the sagittal correction achieved following functional appliance treatment until fixed appliances can be bonded. Early treatment of Class II malocclusions can be associated with increased overall treatment time and cost. It has also been associated with less optimal occlusal outcomes.⁵ Therefore, delaying the start of this treatment to coincide with the anticipated peak in the adolescent growth spurt is often preferred, allowing for a smooth transition between functional and fixed treatment (Figure 2).

Class III

Class III malocclusions can be challenging to manage orthodontically because of the influence of growth. Patients may present with features of a Class III malocclusion at an early stage, for example an anterior crossbite associated with a displacement. This could also result in hard and soft tissue damage, such as attrition and recession. Interceptive treatment for Class III cases is sometimes useful to reduce the need and complexity for later treatment, but also reduce the risk of further damage to the hard and soft tissues.

Identifying the aetiology is important in the management of these cases. These patients may be monitored until their growth potential has slowed sufficiently to determine whether the patient can be treated orthodontically or if this needs to be combined with orthognathic surgery to achieve an ideal outcome. Where interceptive management is indicated, the use of a sectional, 2x4 upper fixed appliance can be used to correct an anterior crossbite (Figure 3). Alternatively, an upper removable appliance with posterior bite planes and either an anterior spring or screw could be used, although treatment has been shown to be slower and more expensive with this method (Figure 4).^6,7 A sufficient overbite is important to aid in stability of the correction in these interceptive cases.

‘Growth modification’ treatments can also be used in this cohort of patients. In a multicentre randomized controlled trial (RCT), the use of protraction facemask treatment in patients aged 7–9 years old, was shown to reduce the later subjective need for orthognathic treatment compared to untreated controls.⁸ For patients of this cohort, with a skeletal class III pattern owing to maxillary hypoplasia, it is worth GDPs considering referral to a local specialist orthodontist.

Crossbites

Crossbites can present anteriorly and/or posteriorly, owing to a discrepancy of the antero-posterior or transverse dimensions, respectively. As discussed previously, crossbites can result in recession and tooth surface loss. The aetiology could result from a combination of skeletal, soft tissue and dental factors. Additionally, persistent habits, such as digit sucking, can result in the development of posterior crossbites.⁹ Early diagnosis and management can aid in preventing unintended consequences, which can persist into the full permanent dentition. Lombardo described the prevalence of posterior crossbites in children in Europe as approximately 4%.¹⁰

The interceptive management of anterior crossbites has been discussed previously in the management of Class III malocclusions. In terms of posterior crossbites, the factors that need to be considered when choosing between interventions include the extent of expansion required, the presence of sufficient teeth for appliance retention, the presence of a displacement, patient age, anticipated patient cooperation, oral hygiene and the likely stability of the correction.

In some cases, a crossbite can self-correct as the permanent teeth erupt.¹¹ If the aetiology of the crossbite involves a habit such as thumb sucking, early cessation of the habit is vital and will often result in some spontaneous correction. In 2021, a Cochrane review highlighted that, for patients treated in the early mixed dentition, both removable appliances and quad helixes are beneficial for correcting posterior crossbites, although treatment with quad helix has been shown to have shorter treatment times.⁹ Rapid maxillary expansion (RME) appliances may also occasionally be considered in the mixed dentition. Other methods, such as incorporation of expansion screws into a functional appliance, archwire expansion, cross-elastics, self-ligating brackets and expansion arches can be used to correct posterior crossbites in the permanent dentition.¹²

Unerupted central incisors

The developing dentition should be regularly monitored for correct sequence of eruption. Delayed eruption of a permanent maxillary incisor tooth should be considered when the contralateral tooth erupted over 6 months ago, the mandibular incisors erupted over 1 year ago, or there is a deviation from the normal sequence of eruption. The authors would recommend early referral to an orthodontist, or paediatric dentist in this situation.

The aetiology of such cases can often be associated with dental factors. For example, supernumeraries in the premaxillary region have been found in 2.6% of a referred UK population, which subsequently were found to be associated with the failed eruption of 42% of maxillary central incisors.¹³ Tuberculate and odontome types of supernumerary teeth are the most likely to prevent incisor eruption.^13,14

Furthermore, trauma to the deciduous incisors may result in dilaceration of the crown or root of the permanent central incisors and subsequently affect the eruption of these teeth.

Additionally, early loss of primary teeth, prolonged retention of primary teeth and crowding in the upper anterior segment may all prevent eruption of the incisor. Gingival fibromatosis, scar tissue or pathology, such as cysts, tumours or infection, can result in a physical obstruction to eruption of central incisors and should also be considered where no other obvious cause can be identified.

A multidisciplinary approach to these cases is imperative (Figure 5). Recently updated guidance by the Royal College of Surgeons of England highlights the need to consider several factors, including the space requirement to address the underlying malocclusion, patient age, medical history and likely compliance levels, as well as the eruptive potential of the impacted incisor.¹⁴

When alignment of the incisor is favourable, removal of any obstructions, such as supernumeraries and retained deciduous teeth, in patients younger than 9 years of age, may allow for the spontaneous eruption of the unerupted tooth, providing there is sufficient space for the tooth. However, consideration should be always given to the method of removal of any obstruction(s), as combining the procedure with an exposure may be necessary to limit the number of general anaesthetic (GA) episodes.

In older children (i.e. over 9 years of age), the eruptive potential of the impacted incisor may be reduced and therefore gold chain placement may be indicated to enable orthodontic alignment of the tooth.

Dilacerated teeth need to be carefully assessed, in some cases using cone beam computed tomography (CBCT), to reduce the risk of alignment resulting in fenestration through the cortical plate and subsequent devitalization.

As well as removing any obstructions, it is important to create sufficient space for the impacted incisor.¹⁵ Fixed appliances are most commonly used for this purpose, and can also be used for subsequent alignment of the exposed central incisor. One potential limitation of using a fixed appliance in the mixed dentition is that large unsupported sections of archwires can pose risks if they are fractured. Alternative approaches, including the use of upper removable appliances and magnets have been described by Parker and colleagues; however, it is often more pragmatic to incorporate any firm primary teeth into the fixed appliance.¹⁶ In some cases, alignment of the unerupted central incisor is unfavourable. In this situation, surgical removal of the impacted incisor may be necessary, and both short-term and long-term replacement options need to be carefully considered at the outset. If the optimal plan is determined to be long-term replacement of the incisor, then maintaining space for this tooth in the short term, for example by use of a removable appliance with a prosthetic tooth and stainless-steel stops (in case of fracture), should also be considered to prevent further space loss and an upper dental centreline shift.

In situations where alignment is deemed to be unfavourable, or when incisors fail to erupt with orthodontic traction (potentially due to ankylosis), considerations for the long-term replacement of the incisor need to be taken. Orthodontically, this may require treatment to optimize the space available for a prosthetic replacement. Occasionally, it may be more appropriate to work towards camouflaging the adjacent lateral incisor as a central incisor, dependant on the rest of the malocclusion. Involvement of the restorative team at the outset is also of great importance in cases where the incisor must be removed to ensure optimal long-term outcomes.

Palatally displaced canines (PDCs)

As with unerupted central incisors, a patient's dental development should be closely monitored for eruption of the permanent canines. Maxillary permanent canine teeth are the most likely to become impacted (after third permanent molars).¹⁷ Canines that are palatally displaced and fail to erupt into the mouth, are found in 1–3% of the population.^18,19 There are two main theories with regards to the aetiology of this: the genetic theory, described by Peck; and the guidance theory, described by Becker.^20,21

As permanent canines develop, they move from a palatal position to a more buccal one, ordinarily being palpable from approximately the age of 10 years old in the buccal sulcus. This is often accompanied by progressive mobility of the deciduous canines. If these signs are not detected, further investigation into the position of the canines should be considered. Failure to diagnose displaced canines early could result in significant resorption of adjacent teeth or may complicate future orthodontic treatment.

The findings of a recent RCT suggest that interceptive extraction of a deciduous canine can aid spontaneous eruption of the permanent canine in situations where the tooth has mild-to-moderate displacement and there is minimal maxillary arch crowding.²² However, a recent Cochrane review stated that the evidence base is ‘uncertain’ in this area.²³ The present authors would like to emphasize the importance of early referral of these patients to an orthodontist because careful assessment of the severity of displacement is required before committing to extraction of the primary canine.²³ Consideration for interceptive extraction of the deciduous canine should only be taken if the patient is 10–13 years old, with less than 2-mm crowding in the maxillary arch, and the canine is in a favourable position (i.e. in sector 2–3 with an alpha angle less than 21°).^24,25 It would also be imperative to discuss the potential need for exposure and alignment if the interceptive treatment was unsuccessful with the patient and their parent(s). Double extraction, where the deciduous maxillary canine and deciduous maxillary first molars has also been suggested in the literature, although the aforementioned Cochrane systematic review found no evidence that this increases the likelihood that palatally displaced canines will erupt at 18 months, compared to a single extraction of the deciduous maxillary canine.²³

Another method discussed in the literature includes the creation of space to improve the eruption of the canine (Figure 6).²⁶ Various methods of space creation have been investigated for this purpose, including the use of headgear, RME, quad helices and upper fixed appliances.^27–31

For more severely displaced canines, which are unfavourable for alignment, consideration should be given to incorporating removal of the displaced permanent canine into the overall extraction pattern for the patient's malocclusion. This may involve the camouflage of the first premolar as the canine tooth. If the permanent canine requires exposure (open or closed), consideration needs to be given to patient cooperation, motivation, age, severity of displacement and the existing malocclusion.

Enamel and dentine disorders

Disorders and abnormalities of dentine and enamel have been linked to a diverse range of interactive influences, from genetic factors (inherited as mutations in genes themselves, or as a feature of a familial condition), to environmental changes and systemic insults during enamel formation such as infections, radiation and metabolic conditions.³²

With increasing numbers of patients now receiving orthodontic treatment, the number of those being treated with atypical tooth surfaces is also likely to increase. This includes enamel conditions such as amelogenesis imperfecta (AI), molar–incisor hypomineralization (MIH) and fluorosis, as well as dentine conditions such as dentinogenesis imperfecta (DI) and dentine dysplasia (DD).³³ It is important that all members of the dental team have working knowledge of, and are able to distinguish between, the various types of enamel and dentine disorders, because this will affect the management options proposed. Localized and chronological enamel defects may be present on teeth due to a variety of factors: trauma or localized infection related to the primary predecessor, severe or chronic childhood conditions such as vitamin D deficiency, coeliac disease, liver and kidney diseases. These typically present as either hypoplastic or hypomineralized defects.³⁴

As opposed to molar–incisor hypomineralization (MIH), described in Part 1 of this series,² dental fluorosis can cause generalized hypomineralization of the enamel that results in subsequent brown discolouration and post-eruptive breakdown, both anteriorly and posteriorly (Figure 7). Teeth affected by dental fluorosis may display a spectrum of discolouration from opaque whiteness to pitted surfaces that are stained yellow–dark brown. A detailed fluoride history and family history is important to distinguish between dental fluorosis and other enamel defects, such as AI.

AI is a genetically inherited enamel defect, that is quite rare, affecting between 1 in 700 and 1 in 14,000 people and can presented as an isolated genetic defect or as part of a syndrome.³⁴ Hypomineralized AI is subdivided into hypocalcified (typically with a distinct dark yellow colour), and hypomature (typically with white diffuse opacities and mottling). Hypomature AI may present similarly to fluorosis or even MIH on occasion, hence a good family and medical history is crucial in determining a definitive diagnosis.³⁴ Hypoplastic AI tends to present as teeth with thin or absent enamel, alongside visible pits and grooves. Affected teeth display normal enamel colour to a more yellow/brown colour. Affected teeth pose issues with aesthetics, bonding, sensitivity and can have a severe impact on a patient's quality of life – management options are complex and often require specialist input and care.

Children with developmental dentine defects will usually present once the primary teeth begin to erupt and early referral to specialist paediatric dental services is advised. They are less common than developmental defects of enamel; however, clinical implications, especially in the primary dentition, tend to be more severe.³⁴ Dentine defects are grouped into those that affect dentine tissues only and those that show bone involvement alongside the dentine defect: osteogenesis imperfecta-related DI, isolated DI (mild, moderate, severe) and radicular dentine dysplasia.³⁵ Teeth may appear translucent, while some display shades of blue-grey or opalescent brown, and the crown tends to be more bulbous in form. Radiographically, they have a distinct small pulp chamber and small, narrow roots, with some showing complete obliteration of the pulp complex/root canal or even appear to be floating ‘rootless’ teeth – this can pose an issue owing to the potential adverse effects of orthodontic forces on short or malformed roots.³⁵

Conclusions

This article further demonstrates the importance of fostering a strong partnership between primary and secondary care clinicians in the management of common orthodontic–paediatric problems. The clinical cases presented across this two-part series serve as a guide in the early recognition of developing malocclusions and their optimal management across a diverse range of presenting issues. Timely referral from GDPs, alongside collaborative working between orthodontists and paediatric dentists, facilitates the best chance to produce ideal clinical outcomes.