Australian Dental Journal
The official journal of the Australian Dental Association
Australian Dental Journal 2017; 62:(1 Suppl): 11–19 doi: 10.1111/adj.12474
Timing orthodontic treatment: early or late? PS Fleming Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
ABSTRACT The timing of orthodontic interventions has been a contentious topic for many years with early treatment to address or indeed to prevent skeletal discrepancies in all three spatial planes and to alleviate crowding in common practice. In terms of effectiveness, however, broadly speaking early intervention has not been shown to be superior to later intervention. As such, in view of the additional burden and duration of early intervention, the weight of evidence points to reserving early treatment for localized problems and specific situations with definitive treatment typically initiated in the late mixed or early permanent dentition. Keywords: Crowding, Interceptive Orthodontic, Early treatment.
INTRODUCTION The appropriate timing of orthodontic intervention has sparked considerable debate with a body of specialist and non-specialist providers wedded to the routine provision of ‘early’ treatment.1 However, definitive orthodontic treatment is most commonly started in the late mixed or early permanent dentition. This phase typically coincides with a period of maximal growth, allowing efficient correction of growthrelated occlusal anomalies; may permit beneficial use of the leeway space; and offers the availability of permanent teeth for retention of appliances and definitive correction of a malocclusion. Interceptive orthodontics constitutes any measure performed to correct a developing malocclusion or to simplify later orthodontic care. It has been suggested that developing problems in the mixed dentition could be fully corrected with simple interceptive treatment in 15% and improved in 49% of cases.2 Therefore, targeted implementation of simple interceptive measures is important and cost-effective with the general practitioner perfectly placed to identify and occasionally correct developing occlusal problems in a timely manner. However, blanket prescription of early treatment either to prevent or treat a malocclusion at a young age does not appear to be indicated.3 The value of early intervention to intercept localised problems has variously been reviewed;4, 5 the present review will therefore focus on the relative merits of early treatment in the management of generalised malocclusion and growthrelated issues. © 2017 Australian Dental Association
Early Treatment: Theoretical Basis A range of potential indications for early orthodontic intervention commencing prior to the late mixed dentition phase have been proposed and include: A dental health benefit: Early intervention to address crowding may improve access for oral hygiene measures. While this may certainly be the case, there is no evidence that crowding in the mixed dentition is incompatible with periodontal health in the long-term.6 There is some evidence that early intervention to address increased overjet may translate into a reduced risk of incisor trauma; however (See Class II correction).7 Psychosocial considerations/benefit: There is a proven association between a range of dental anomalies including increased overjet and overbite, anterior spacing and open bites with teasing and bullying.8 Persistent teasing is known to affect self-perceptions and so a malocclusion may have a negative socio-psychological impact. Given that targeting arises on an individual and often unpredictable basis, early treatment to address occlusal issues in those affected rather than as a blanket measure has been recommended on the basis of high-quality prospective research.9 Growth response: The plasticity of the skeleton both in the short- and medium- term has been the subject of lengthy, often vociferous debate. Early research involving cephalometry alluded to the ‘immutability’ of the facial skeleton contrary to what had previously been propounded by orthodontic pioneers.10 Contemporary research, 11
PS Fleming most notably randomised studies carried out in the U.S. and the U.K. with prolonged follow-up periods of up to 10 years, have confirmed that overjet reduction, for example, during functional appliance therapy is attributable both to skeletal (30%) and dento-alveolar changes (70%) in the shortterm. However, in the longer term these skeletal changes appear to dissipate with little difference in mandibular length or position relative to untreated groups.11–13 Nevertheless, there remains a school of thought that more sustained intervention might translate into more meaningful levels of skeletal change. There is currently, no prospective evidence to support this theory and a growing acceptance that early intervention in Class II malocclusion cases is no more effective, but less efficient, than later treatment.14 Aetiology: Proponents of early intervention, particularly those advocating sustained growth modification, typically consider malocclusion to be essentially environmental in origin. For example, soft tissue behaviour and position, and aberrant habits have variously been linked to growthrelated disturbances.15 While the environmental aetiology of certain malocclusions is undeniable, with, for example digit sucking, known to induce localised malocclusions, most are a manifestations of genetic and environmental interactions. Moreover, craniofacial growth is governed by a complex interplay of signalling molecules, transcription factors and extra-cellular matrix proteins. It is known that transcription factors encoded by Dlx genes are instrumental in the morphogenesis of the maxilla and mandible within the first branchial arch. Perturbations of these events are known to induce dramatic skeletal facial changes.16
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Table 1. Timing of eruption Typical eruption date (Years)
Range (Years)
6 6 6 7 7 8 10 10 11 11
6–7 6–7 6–7 7–8 7–8 8–9 9–10 10–12 10–12 11–12
Maxillary
Mandibular First molar
First molar Central incisor Central incisor Lateral incisor Lateral incisor First premolar Second premolar Canine
Canine First premolar Second premolar
NORMAL OCCLUSAL DEVELOPMENT IN THE MIXED DENTITION The ability to recognise occlusal anomalies is predicated on an understanding of normal occlusal development in the mixed dentition.17 The mixed dentition spans the period from eruption of the first permanent tooth at 5-6 years to exfoliation of the last primary tooth at 12-13 years, with a variation of up to 18 months being common. Common eruption sequences and timing are provided in Table 1. Intra-arch features: Crowding of the incisors is typical in the mixed dentition as the combined width of the permanent incisors is 7mm and 5mm more than the primary incisors in the maxillary and mandibular arches, respectively18. A resolution or improvement often arises naturally due to widening of the inter-canine dimension, increased arch length due to proclination of the permanent incisors, and closure of primate spacing. Distal fanning of permanent maxillary incisors, known as the ‘ugly duckling’ or ‘Broadbent’ stage,
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Fig. 1 (a) Lip trap involving maxillary central incisors. (b) Lip trap leading to isolated proclination of UR1 and UL2 as the lip functions palatal to these teeth. The lower lip, however, is labial to UL1; this tooth is therefore not proclined. (c) Lip trap related to a skeletal II pattern with mandibular retrognathia 12
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Timing orthodontic treatment (a)
The eruption of the canines and premolars is expected between 9 and 13 years of age. In the presence of crowding, available space is used on a ‘first come, first served’ basis with impaction of the canines and second premolars therefore, common. Primary crowding may cause displacement, for example, of lateral incisors or the buccal impaction of maxillary canines, in particular. This may be compounded in the second premolar region by early loss of the second primary molars and subsequent mesial migration and rotation of the first permanent molar. Inter-arch features:
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Typically first permanent molars erupt into a one-half unit II molar relationship guided by the flush terminal plane between the second primary molars seen in 76% of individuals in the primary dentition19. A Class I molar relationship may develop naturally by “early” or “late mechanisms”. Early establishment of a Class I molar relationship arises due to mesial migration of the mandibular first molar in the open mixed dentition to close the primate spacing present distal to the lower primary canines. The later mechanism occurs in an unspaced dentition following loss of the second primary molars as the permanent dentition becomes established. This facilitates greater mesial migration of the lower first molar, as there is a greater discrepancy between the mesio-distal widths of the mandibular primary molars and the succeeding premolars than is the case in the maxilla. The emergence of the permanent incisors is normally accompanied by a transient anterior open bite prior to their complete eruption. Subsequent to incisor eruption, changes in the magnitude of an overjet are usually limited but may be influenced by the soft tissue environment. CLASS II CORRECTION
Fig. 2 Treatment was commenced in the mixed dentition to address a large overjet relatively early (2a) as there was a profound lip trap and associated teasing (See Figure 1a). The Class II relationships were addressed with a functional appliance over a 12 months (2b). Detailing of the occlusion was undertaken following eruption of the permanent dentition with treatment undertaken over a 5-year period.
occurs prior to the eruption of maxillary lateral incisors and canines due to the proximity of the erupting teeth to the distal root surfaces of the more mesial adjacent teeth. An associated maxillary midline diastema prior to eruption of the maxillary canines is also regarded as physiological. Intervention to address this spacing prior to the eruption of the maxillary canines is therefore not warranted. © 2017 Australian Dental Association
Early intervention to address an excessive overjet has proven no more effective than postponing treatment until adolescence. The primary indication for early intervention in Class II malocclusions remains psychosocial problems and teasing.20 However, a recent Cochrane review has suggested that early reduction of an overjet does have a protective effect in relation to dental trauma.7 Incompetent lips, a markedly increased overjet and increased incisal exposure at rest predispose, in particular, to dental trauma and may derive some benefit from early intervention (Figure 1).21 The decision to address increased overjet ‘early’ is undertaken on an individual basis, with the weight of evidence suggesting that early intervention does not result in enhanced mandibular growth. The arbitrary 13
PS Fleming use of chronological age, typically 10 to 13 years in females and 11 to 14 years in males, continues to be an acceptable yardstick for the timing of most efficient and effective growth modification in Class II subjects. Little difference in the skeletal effects associated with functional appliances at the age of 10 years relative to a group treated just after the onset of puberty (mean age 12.9 years) has been shown.22 Moreover, demonstrable, albeit limited skeletal changes with the Herbst appliance have been reported based on magnetic resonance imaging of the temporo-mandibular joints.23 There is, however, clearly an increase in treatment duration with early treatment. This relates to the reduced rate of mandibular growth observed in pre-adolescents and to the requirement for dental eruption to permit complete and optimal occlusal inter-digitation. A period of intermittent appliance wear may be required following an early full-time functional phase to limit relapse of the initial Class II correction (Figure 2). In contrast, when Class II correction is undertaken in the late mixed or early permanent dentition, the fixed phase can either be undertaken concurrent with Class II correction or may follow the initial phase in a relatively seamless manner (Figure 3).
CLASS III MALOCCLUSION Anterior crossbites are a common finding in the mixed dentition with maxillary lateral or central incisors displaced in lingual occlusion. Localised crossbites of dental origin can be easily corrected with either removable or fixed appliances. Indications for correction include: aesthetics, as anterior crossbites predispose to a Class III profile; incisal wear, associated with occlusal displacement; and periodontal attachment loss labial to the lower incisors related to continued forward mandibular displacement (Figure 4). The correction of an anterior crossbite may be achieved by an upper removable appliance incorporating posterior capping to disengage the occlusion and ‘T-’ or ‘Z-’springs made from 0.5mm stainless steel wire to procline the involved maxillary incisor. This provides a simple means of correction, but, a complete or partial fixed appliance (2 X 4 appliance) can be used to achieve more controlled tooth movement. This may be appropriate if more than one incisor is in crossbite or if dental rotations require correction. Both treatment approaches have been shown to be effective and stable, although the use of fixed appliances may provide a more predictable outcome.24, 25
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Fig. 3 (a-d). Seamless progress to fixed appliances following an initial functional phase facilitating efficient Class II correction in the early permanent dentition. 14
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Timing orthodontic treatment (a)
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Fig. 4 An untreated Class III malocclusion with anterior displacement from RCP (a) to centric occlusion (b) with associated incisal wear (a-c). This was subsequently treated with fixed appliances to camouflage the mild underlying skeletal III discrepancy (d, e). Earlier interception may have prevented the occurrence of the incisal wear.
An anterior crossbite affecting two or more teeth or presenting with a reverse overjet in the absence of a functional displacement, may signify an underlying skeletal discrepancy. Skeletal problems of this nature might well indicate specialist referral for assessment and possible growth modification with maxillary protraction devices (Figure 5). Early referral may be advised as maxillary protraction, using face-mask © 2017 Australian Dental Association
therapy, is thought to be most successful when performed in the early mixed dentition.26 Patients treated in the late mixed dentition may still derive benefit, but to a lesser extent. The overall skeletal effect, of early maxillary protraction is unlikely to exceed 3mm of change, although in selected cases, this may be sufficient to obviate the need for orthognathic surgery at skeletal maturity.27 15
PS Fleming (a)
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Fig. 5 A Class III malocclusion on a significant skeletal III pattern with the maxillary incisors in crossbite in the mixed dentition. The mandibular incisors were retroclined indicating an antero-posterior compensation for the underlying skeletal discrepancy. There was also significant maxillary arch crowding (a-c). Protraction headgear was used in conjunction with a fixed appliance in the maxillary arch to effect Class III correction and relief of maxillary arch crowding, respectively (d, e). A second phase of fixed appliance treatment was undertaken 3 years following initial treatment to detail the final occlusion and consolidate Class III correction (f, g). 16
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Timing orthodontic treatment VERTICAL ISSUES Early correction of an anterior open bite may be attempted by a range of fixed or removable appliances. In common with much early treatment, the prognosis depends on the aetiology with open bites related to aberrant habits, such as digit sucking, responding well. Growth-related, skeletal open bites require more complex intervention and, depending on later growth, may be more amenable to definitive correction in the permanent dentition. Persistent digit sucking is found in up to 12% of 9year olds and 2% of 12-year olds.28 The impact of digit sucking hinges on the frequency, intensity and duration of the habit with 6 hours daily regarded as a threshold level above which significant effects are expected. With the exception of a narrowing of the palatal vault, the effects of digit sucking are confined to the dento-alveolar complex and typically include an increased overjet, asymmetric anterior open bite and a unilateral posterior crossbite. Conservative methods including education, dissuasion and use of barriers, such as plasters, varnishes or gloves, are considered the first line of treatment. If the use of
reminders is unsuccessful, simple fixed orthodontic appliances including palatal arches with one of a variety of projections including inverted goalposts, beads or cribs may be used as a deterrent for 6 to 12 months. The use of removable orthodontic appliances may also be effective in these cases but their effects may be negated by poor compliance. Anterior open bites have also been attributed to soft tissue behaviour and pattern. The use of fixed adjuncts such as tongue spurs to alter tongue posture has been advocated with some retrospective evidence supporting their effectiveness. The early use of myofunctional treatment in an effort to alleviate aberrant neuromuscular behaviour has received some attention, particularly in Europe. Treatment is based on the premise that a malocclusion is related to muscular behaviour and oral function, although further research is needed to confirm its utility. Van Dyck et al.29 in a pilot study comprised of 22 children aged between 7 and 11 years, reported a marginal improvement in tongue elevation and posture with an associated increase in the prevalence of a complete overbite. No improvement in speech or transverse changes was noted.
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Fig. 6 A significant anterior open bite (9mm) in the permanent dentition (a, b). Temporary anchorage devices were used to facilitate both Class II correction, with distal movement of the maxillary molars, in conjunction with posterior intrusion to effect closure of the anterior bite. © 2017 Australian Dental Association
17
PS Fleming Skeletal open bites present a more significant challenge. Similar to the management of sagittal skeletal discrepancies, the ability to alter vertical facial growth appears to be limited and may require sustained intervention, which correspondingly taxes patient compliance and risks adverse effects. Many treatment methods have been advocated including high-pull orthopaedic headgear directed through the centre of the resistance of the maxilla, vertical-pull chincup and high-angle functional appliance variants, with limited evidence of skeletal effectiveness.30 The advent of temporary anchorage devices has also raised the possibility of posterior intrusion of the dentition to induce open bite closure (Figure 6). The latter, however, more correctly represents a compensation for vertical skeletal excess and while the net effect may well be a decrease in the vertical dimension, the effect is produced through dental intrusion. TRANSVERSE CORRECTION Posterior crossbite correction can be undertaken with fixed or removable appliances, including auxiliaries such as rapid palatal expanders or quadhelix appliances. Early crossbite correction may be undertaken, in particular, if there is an associated occlusal displacement as this may predispose to occlusal wear, periodontal problems and facial asymmetry, if left untreated. There is, however, no comparative evidence concerning the effectiveness or stability of crossbite correction in different age groups. While retrospective research has indicated that early crossbite correction is effective in the primary dentition, later correction is the more accepted approach.31 Similarly, in a randomised trial, a fixed appliance (quadhelix) and a removable appliance were successful in addressing a posterior crossbite, although the removable appliance was slightly less effective. Both of these approaches are known to produce dental rather than skeletal change.32 ALLEVIATION OF CROWDING The relief of crowding is normally performed in the late mixed or permanent dentition. In the permanent dentition space may be generated either by a decrease in the amount of tooth structure (extractions or interproximal reduction) or by increasing the arch length either by transverse expansion, advancement of the incisors or distal movement of the molars. In the late mixed dentition, however, the leeway or ‘E’ space may also be utilised. This represents the difference in width of the primary canine and molars compared with the permanent canines and premolars. In the mandibular arch this space amounts to 2-2.5mm per quadrant during the transition to the permanent 18
dentition with slightly less space available in the maxillary arch, although inter-individual variation does exist. Fixed appliances such as palatal and lingual arches may be useful in leeway space preservation leading to the resolution of crowding in 60% of patients while perfect space preservation would have eliminated crowding in 68% in one study.33 In view of the availability of teeth, in the absence of other features of malocclusion, the optimal timing for correction of dental crowding would appear to be in the late mixed or early permanent dentition. CONCLUSIONS The philosophical debate concerning the merits of early orthodontic treatment has been characterised by dogmatic opinion with a dearth of robust or indeed prospective evidence. Direct comparison of the merits of early or later commencement is complicated by inevitable differences relating to discrepancies in dental, skeletal and overall maturation and development inherent in differing age groups. However, at present, there is little evidence to suggest that initiating treatment prior to the age of 10 years is of greater benefit than later treatment other than to intercept localised malocclusions in a targeted manner. CONFLICT OF INTEREST The author declares no conflict of interest. REFERENCES 1. Wahl N. Orthodontics in 3 millennia. Chapter 12: Two controversies: early treatment and occlusion. Am J Orthod Dentofacial Orthop 2006;130:799–804. 2. Ackerman JL, Proffit WR. Preventive and interceptive orthodontics: a strong theory proves weak in practice. Angle Orthod 1980;50:75–87. 3. Sunnak R, Johal A, Fleming PS. Is orthodontics prior to 11 years of age evidence-based? A systematic review and meta-analysis. J Dent 2015;43:477–86. 4. Kirschen R. Orthodontic clinical screening in under a minute. Br Dent J 1998;185:224–6. 5. Richardson A. Interceptive orthodontics. British Dental Association; 1999. 6. Bollen AM, Cunha-Cruz J, Bakko DW, Huang GJ, Hujoel PP. The effects of orthodontic therapy on periodontal health: a systematic review of controlled evidence. J Am Dent Assoc 2008;139:413–22. 7. Thiruvenkatachari B, Harrison JE, Worthington HV, O’Brien KD. Orthodontic treatment for prominent upper front teeth in children. Cochrane Database Syst Rev 2013;11:CD003452. 8. Seehra J, Fleming PS, Newton T, DiBiase AT. Bullying in orthodontic patients and its relationship to malocclusion, selfesteem and oral health-related quality of life. J Orthod 2011;38:247–56. 9. O’ Brien K, Wright J, Conboy F et al. Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 2: Psychosocial effects. Am J Orthod Dentofacial Orthop 2003;124:488–94. © 2017 Australian Dental Association
Timing orthodontic treatment 10. Brodie AG, Downs WB, Goldstein A, Myer E. Cephalometric Appraisal of Orthodontic Results. Angle Orthod 1938;8: 261–5. 11. O’Brien K, Wright J, orthodontic treatment ticenter, randomized, skeletal effects. Am J 234–43.
Conboy F, et al. Effectiveness of early with the Twin-block appliance: a mulcontrolled trial. Part 1: dental and Orthod Dentofacial Orthop 2003;124:
12. Tulloch JC, Phillips C, Koch G, Proffit WR. The effect of early intervention on skeletal pattern in Class II malocclusion: a randomized clinical trial. Am J Orthod Dentofacial Orthop 1997;111:391–400. 13. O’Brien K, Wright J, Conboy F, et al. Early treatment for Class II Division 1 malocclusion with the Twin-block appliance: a multi-center, randomized, controlled trial. Am J Orthod Dentofacial Orthop 2009;135:573–9. 14. Proffit WR. The timing of early treatment: an overview. Am J Orthod Dentofacial Orthop 2006;129:S47–9. 15. Mew JR. The postural basis of malocclusion: a philosophical overview. Am J Orthod Dentofacial Orthop 2004;126: 729–38.
23. Ruf S, Pancherz H. Herbst/multibracket appliance treatment of Class II division 1 malocclusions in early and late adulthood. a prospective cephalometric study of consecutively treated subjects. Eur J Orthod 2006;28:352–60. 24. Wiedel AP, Bondemark L. Fixed versus removable orthodontic appliances to correct anterior crossbite in the mixed dentition–a randomized controlled trial. Eur J Orthod 2015;37:123–7. 25. Wiedel AP, Bondemark L. Stability of anterior crossbite correction: a randomized controlled trial with a 2-year follow-up. Angle Orthod 2015;85:189–95. 26. Franchi L, Baccetti T, McNamara JA. Postpubertal assessment of treatment timing for maxillary expansion and protraction therapy followed by fixed appliances. Am J Orthod Dentofacial Orthop 2004;126:555–68. 27. Mandall N, DiBiase A, Littlewood S, et al. Is early Class III protraction facemask treatment effective? A multicentre, randomized, controlled trial: 15-month follow-up. J Orthod 2010;37:149–61. 28. Brenchley ML. Is digit sucking of significance? Br Dent J 1991;171:357–62.
16. Depew MJ, Lufkin T, Rubenstein JL. Specification of jaw subdivisions by Dlx genes. Science 2002;298:381–5.
29. Van Dyck C, Dekeyser A, Vantricht E, Manders E, Goeleven A et al. The effect of orofacial myofunctional treatment in children with anterior open bite and tongue dysfunction: a pilot study. Eur J Orthod 2015;July 1 (epub).
17. Fleming PS, Johal A, DiBiase AT. Managing malocclusion in the mixed dentition: six keys to success. Part 1. Dental update 2008;35:607–10.
30. Cozza P, Mucedero M, Baccetti T, Franchi L. Early orthodontic treatment of skeletal open-bite malocclusion: a systematic review. Angle Orthod 2005;75:707–13.
18. Moorees CF, Chadma JM. Available space for the incisors during dental development: A growth study based on physiological age. Angle Orthod 1965;35:12–22.
31. Mutinelli S, Cozzani M, Manfredi M, Bee M, Siciliani G. Dental arch changes following rapid maxillary expansion. Eur J Orthod 2008;30:469–76.
19. Friel S. The development of ideal occlusion of the gum pads and teeth. Am J Orthod 1954;40:196–227.
32. Petren S, Bondemark L. Correction of unilateral posterior crossbite in the mixed dentition: a randomized controlled trial. Am J Orthod Dentofacial Orthop 2008;133:790.e7–13.
20. O’Brien K, Wright J, Conboy F, et al. Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 2: psychosocial effects. Am J Orthod Dentofacial Orthop 2003;124:488–94. 21. Nguyen QV, Bezemer PD, Habets LL, Prahl-Andersen B. A systematic review of the relationship between overjet size and traumatic dental injuries. Eur J Orthod 1999;21:503–15. 22. Baccetti T, Franchi L, Toth LR, McNamara JA Jr. Treatment timing for Twin-block therapy. Am J Orthod Dentofacial Orthop 2000;118:159–70.
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33. Brennan MM, Gianelly AA. The use of the lingual arch in the mixed dentition to resolve incisor crowding. Am J Orthod Dentofacial Orthop 2000;117:81–5.
Address for correspondence: Barts and The London School of Medicine and Dentistry Queen Mary University of London London E1 2AD Email:
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