Author: Â Dr MJ Rowland-Warmann
Student ID BP0150715
Note: This is an academic resource for dentists and orthodontists written by Dr Rowland-Warmann for her Orthodontics Masters at BPP.  If you’re a patient and want to know more about braces and orthodontics at Smileworks and how we can help you or your child with their teeth-straightening then see our main Smileworks braces and orthodontics page here:  Braces Liverpool.
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Introduction
Interceptive orthodontics (IO) is performed to eliminate or reduce the severity of a developing malocclusion with early treatment in order to negate, reduce or simplify later treatment (Ackerman & Proffit, 1980; Chung & Kerr, 1987). IO is performed in the mixed dentition and is associated with full correction in 15% and improvement in 49% of treated cases (Ackerman & Proffit, 1980), although it often forms the basis of a more comprehensive treatment plan (BOS-Publication, 2010).
The mixed dentition phase starts at 5-6 years and ends with the exfoliation of the last primary tooth (Fleming, Johal, & DiBiase, 2008a). Therefore, screening at age 8-10 years should focus on recognising unusual dental development but also whether the identified anomaly even needs intervention (Scott & Atack, 2015). The decision whether to treat depends on child cooperation and behaviour, their family support, social interaction, cost and commitment (Proffit, Fields, & Sarver, 2013) and it is important to distinguish cases that can be treated in-practice from those requiring specialist referral (BOS-Publication, 2010).
The overriding aims of IO are the maintenance of the midline, the prevention of class II molars, reduction of crowding, reduction of incidence of trauma and psychosocial factors associated with malocclusion (Atack, Nattrass, Sandy, Thomas, & Turner, 2015). However, it is important to assess the intended benefits of improvement in aesthetics, attitudes to dental health and psychological wellbeing (Brook & Shaw, 1989) before embarking on potentially lengthy treatment which itself involves risks to the patient and their dentition and may leave them feeling burnt-out before definitive orthodontic treatment can even begin  (Proffit et al., 2013).
When to start IO
It is very rare that the deciduous dentition requires treatment (BOS-Publication, 2010) but it is nevertheless important to monitor eruption sequence and presence of teeth.  IO is, by virtue of its intended effects, started early. Screening at age 9 and 11 has been suggested by Al Nimri & Richardson (Al Nimri & Richardson, 2000). The various features of discrepant dental development will need assessment at different times depending on the occurrence of the problem in the developmental sequence. As a rule, intervention should be considered as soon as the problem becomes evident to reduce the severity of any developing malocclusion.
What requires treatment
In order to commence IO, it is important to distinguish between facial development, dental development and aberrant development attributable to syndromes. Children suffering from syndromes such as cleft lip and palate, Teacher Collins, hemifacial macrosomia or Couzon’s syndrome display complex issues and will require growth modification, surgery and medical treatment at a specialist centre (Proffit et al., 2013).
Discrepancies in facial development
Early treatment of Class II division 1 malocclusion results in a small but favourable skeletal change but results show that there is only minimal benefit to functional appliances in the mixed dentition. Reduction of more complex treatment in around 15% of cases is seen but the final occlusal result compared to adolescent treatment is not significantly improved, meaning treatment can be deferred until near-adolescence. A disadvantage in terms of attendance, cost and length of treatment is seen, which links back to the potential for patient burn-out before definitive treatment can be commenced (O’Brien et al., 2009; Scott & Atack, 2015). The correction of Class III discrepancies has definitive advantages and should be explored early. In a study by Mandall et al, 70% of treated individuals achieved positive overjet, which was the indicator of success. This is best achieved with protraction headgear in under 10s to achieve maximum benefit. Surprisingly, there appeared to be no psychosocial benefit to successful Class III treatment (Mandall et al., 2010; Scott & Atack, 2015).
Any transverse discrepancy in development should be assessed when this becomes apparent, although treatment may come later. Asymmetries can be very challenging and often require specialist treatment (Scott & Atack, 2015).
Discrepancies in Dental development
Anterior crossbites
The occlusion of lower anterior teeth labially to upper anterior teeth can cause attrition, gingival recession or fracture of the upper incisors. There has also been a weak association with the development of temporomandibular joint dysfunction. Treatment options include fixed or removable appliances, with the evidence favouring ‘2×4’ fixed appliance therapy (F. Borrie & Bearn, 2013; Fleming et al., 2008a). General dental practitioners likely favour removable appliances due to their ease of use, and research by Wiedel suggests that there is no difference in outcome between fixed and removable appliance therapy for the correction of crossbites. Although removable appliances are associated with higher cost and longer duration of treatment (Wiedel, 2015).
Posterior crossbites
Posterior crossbites are found in around 7.5 to 22% in deciduous and mixed dentitions (Petren, Bjerklin, & Bondemark, 2011). Unilateral crossbites with displacement can lead to temporomandibular dysfunction (TMD), and early treatment has been advocated (F. Borrie & Bearn, 2011). Treatment of posterior crossbites can be achieved initially by grinding the primary dentition, and further to this by appliance treatment with a fixed quadhelix or expansion plate in the early mixed dentition. Petren et al found that the stability of the outcome for both appliances was similar (Petren et al., 2011).
Impacted upper central incisors
Any delays in the eruption of, or abnormality in eruption sequence, should be investigated. Impaction of permanent incisors, the prevalence of which Is around 3%, can be caused by supernumeraries blocking eruption path, previous trauma to deciduous teeth, and occasionally crowding (F. Borrie & Bearn, 2011; Johnsen, 1977). In the case of supernumerary teeth, 90% are found in the anterior maxilla, and if located in the path of eruption, can cause dilacerations of the permanent successors (Proffit et al., 2013).
In children under ten, treatment should focus on removing the obstruction, maintaining the space for the unerupted tooth and waiting for it to descend before intervening with bracket therapy. In children over 10 intervention by bonding a bracket to move the tooth should be completed (F. Borrie & Bearn, 2013).
Ectopic maxillary permanent canines
Of multifactorial aetiology, the incidence of impacted maxillary canines is around 2%, with over 60% palatally placed (Stivaros & Mandall, 2000). Naturally, space is an issue if the canine is displaced. The creation of space will increase the chance of eruption. Extraction of the deciduous canine has been shown to be effective in around 79% cases. Extraction of the deciduous canine plus headgear or rapid maxillary expansion followed by trans-palatal arch placement also have increased favourable outcomes (F. Borrie & Bearn, 2013; Sigler, Baccetti, & McNamara, 2011). Canines should be palpable in the labial sulcus at age 10 and should be investigated if not present or if the deciduous canine is showing no sign of mobility if the contralateral deciduous canine has already exfoliated (BOS-Publication, 2010; Fleming, Johal, & DiBiase, 2008b).
Poor quality first permanent molars (FPM)
FPM are susceptible to caries in childhood and as such may be of limited long term prognosis. Timing of the lower FPM extraction is crucial, and should be completed when there is radiographic evidence of the calcification of the bifurcation of the second permanent molar in order to achieve mesial migration of this tooth and subsequent acceptable occlusion. The recommendation is that upper FPM should be removed if lower FPM are to be extracted. In Class II cases the second molars should erupt before extraction of the FPM, and in Class III cases extraction of FPM should be avoided where possible (F. Borrie & Bearn, 2013; Cobourne, Williams, & Harrison, 2014).
Infra-occlusion of primary molars
Infraoccluded primary molars, occurring at a rate of 8 to 14%, often become ankylosed, resulting in impaction or deflection of permanent teeth. There is a genetic element to their occurrence. If the underlying premolar is present, the infraoccluded primary molar may serve as a space preserver and should be monitored, removing it only if space loss is in issue. The presence of a permanent successor usually results in natural exfoliation, which may require assistance if there has been significant difference to the time of exfoliation of the contralateral tooth (F. Borrie & Bearn, 2013).
Non-nutritive sucking habits (NNSH)
NNSH can lead to malocclusions which, if left until late in the child’s development, may become complex issues for treatment. Around 73% of children up to age five display NNSH, reducing to around 2% in 12-year olds. If persistent, NNSH can lead to anterior open bite, posterior cross bites and increased overjets, which may require orthognathic surgery to correct at a later stage (F. Borrie & Bearn, 2015)
IO for NNSH focuses on cessation of the habit, and includes psychological treatment, making the object of habit less appealing (such as application of ill-tasting varnish to the thumb) and habit-breaking appliances. Habit-breaking appliances are effective if behaviour management has not borne fruit (F. Borrie & Bearn, 2013).
Unilateral loss of primary teeth
A shift of 2mm or more is considered unaesthetic, and can cause occlusal issues due to incorrect intercuspation of buccal segments (Johnston, Burden, & Stevenson, 1999). In cases where one deciduous canine is lost, it may be necessary to balance the loss with the extraction of the contralateral canine in order to preserve the midline (Mitchell, 2013). Loss of the deciduous canine can result in significant crowding in the permanent dentition (F. Borrie & Bearn, 2013).
Increased overjet and trauma risk
Overjet increase of over 3.5mm or more is associated with a more than twofold risk of upper incisor trauma (Artun, Behbehani, Al-Jame, & Kerosuo, 2005). A study by Koroluk failed to find improvement in the outcome for incisors as a result of IO. This study suggested that in order to be effective, IO would need to be commenced as soon as the incisors erupt in order to have a beneficial impact (Koroluk, Tulloch, & Phillips, 2003). This is not considered to be a favourable cost-benefit ratio (Chen, McGorray, Dolce, & Wheeler, 2011). This treatment should only be considered if the increased overjet has a negative psychological on the child (F. Borrie & Bearn, 2013)
Space loss
Leeway space is the difference in mesio-distal widths between primary canine and molars compared to permanent canine and premolars. In the mandible this is 2-2.5mm, whereas in the maxilla it is around 1-1.5mm (Fleming et al., 2008b). If the second deciduous molar is compromised, it is advisable to retain this tooth for as long as possible to maintain space and prevent mesial migration of the first permanent molars (BOS-Publication, 2010). Maintenance of space can also be performed with removable appliances using lingual or palatal arches, which has been shown to have a positive effect in 60% of patients (Fleming et al., 2008b). In the case of severe lack of space of 10mm or more, serial extractions have been advocated, although this is now seldom performed. In cases where there is lack of space for emerging canines, first premolars may be extracted (Ackerman & Proffit, 1980; BOS-Publication, 2010). Addressing space loss in the lower arch with expansion is unstable and should not be performed (DiBiase, 2002).
ConclusionÂ
IO can significantly reduce the severity of a developing malocclusion but it must be remembered that it is unlikely to produce finished results (Jolley et al., 2010).  Often, IO can be undertaken by the general dental practitioner, meaning that it can significantly improve outcome for patients especially where access to specialist orthodontic services is limited (Al Nimri & Richardson, 2000; F. Borrie & Bearn, 2013). However, compliance with treatment can be disappointing in younger age groups (Al Nimri & Richardson, 2000).
Avoidance of fixed appliances and use of simple appliance for IO can reduce the risk of damage to the teeth and root resorption (F. Borrie & Bearn, 2011), especially considering that fixed appliance treatment can result in white spot lesions in between 15 to 85% of patients (F. Borrie & Bearn, 2013). It is important to consider which treatment is appropriate for the age of the child in order to improve compliance.
On the whole, treatment of the deciduous dentition is considered inappropriate. Treatment for delayed incisor eruption, early loss of deciduous teeth, crossbites, NNSH and severe crowding can be instigated in the early mixed dentition. In the late mixed dentition, discrepancies such as ectopic canines and poor quality FPM can be considered. It is, however, important to remember that treatment should be planned as soon as the discrepancy becomes evident in order to have ample opportunity to resolve it, even if resolution is more appropriate at a later stage (F. Borrie & Bearn, 2013; DiBiase, 2002).  In each case, it is vital to consider the evidence base in order to achieve the best long term outcome for the child.
References
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