2-the timing of orthod tx

8/12/2019 2-The Timing of Orthod TX

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4 3 4 Dental Update November 2002

Abstract: The time at which orthodontic treatment should be started remains a

matter of conjecture. Anomalies of dental development and functional problems tend tobe addressed in the mixed dentition, while definitive treatment tends to be delayeduntil the late mixed dentition to maximize growth potential and patient compliance.However, some clinicians advocate starting treatment earlier in certain types of malocclusion. In this article, the current concepts of early treatment, both physiologicaland psychological, will be explored and the relevant indications and contraindicationsdiscussed.

Dent Update 2002; 29: 434441

Clinical Relevance: General dental practitioners need to have an understanding of the timing of orthodontic treatment in different types of malocclusion to maximize theeffectiveness of patient referrals.

T H E B E L L E M A U D S L E Y L E C T U R E 2 0 0 2

ithin the practice environment, dentists are the first to examine

and screen children for developingmalocclusions. They are often faced withthe dilemma of deciding at what age torefer for a further opinion and possiblytreatment. This of course depends on the

problem that has been diagnosed and thedental development of the child, but isthere an ideal time for orthodontictreatment, if the clinician wants tomaximize the benefits of growth and co-operation without subjecting every child to four or more years of treatment?

MANAGING THEDEVELOPING DENTITIONFrom the eruption of the first primarytooth until the development and eruption

of the wisdom teeth, the developingdentition should be monitored and interceptive treatment prescribed asnecessary. There is a difference, however,

between treatment decisions that arethrust upon us due to aberrations of dental development and types of malocclusion that we may choose to treatearly by use of appliance therapy or elective extraction of teeth. Table 1 liststhe problems that should be looked for atvarious stages of dental development.

It is obvious from these lists that themanagement of certain problems such asskeletal discrepancies or crowding can beundertaken at differing times during thedental development. When earlytreatment is contemplated, especially if itinvolves the use of active appliances, thefollowing questions should be asked: 1

l Will early treatment correct the problem or eliminate the need for comprehensive treatment at a later date?

l Will the final result of two-phasetreatment be better than that of asingle course of treatment at a later stage?

l Will early treatment reduce the risk of trauma to susceptible incisors?

l Will early treatment result in greater skeletal change than treatmentduring the growth spurt?

l Will early treatment reduce theseverity of the problem to make asecond phase of treatment easier and of a shorter duration?

l Will early treatment create problemsor reactions that are undesirable?

l Will early treatment have a beneficial psychological impact onthe patient?

The Timing of OrthodonticTreatment

A NDREW D IB IASE

Andrew DiBiase , BDS(Hons), MSc, FDS(Orth), MOrth RCS(Eng), Consultant Orthodontist, Kentand Canterbury Hospital, Canterbury.

WEarly mixed dentition:l Delayed eruption of permanent incisorsl Supplemental incisorsl Early loss of deciduous teethl Congenital absence of incisorsl One or more incisors in crossbitel Impaction of first permanent molarsl Severe crowdingl Severe skeletal discrepancyl Posterior crossbites

Late mixed dentition :l Severe skeletal problemsl Unfavourably positioned canines or

other teethl Congenitally absent permanent teethl Poor-quality first permanent molarsl Traumatic overbites

Early permanent dentition:l Severe skeletal problemsl Impacted teethl Crowdingl Hypodontia

Table 1. Problems to look for in the developing dentition in relation to timing of orthodontic treatment.


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B E L L E M A U D S L E Y L E C T U R E

Dental Update November 2002 4 3 5

It is also important to differentiate between interceptive and definitivetreatment: interceptive treatment isintervening in the developing dentitionto allow it to achieve the best occlusion

possible, or to make subsequenttreatment as simple and short as

possible. Therefore, although certain problems may be addressed earlier, thereis a difference between a 6-monthcourse of treatment in the mixed dentition followed by later treatment inthe early permanent dentition and adefinitive course of treatment thatcommences in the mixed dentition and extends over several years.

EARLY MANAGEMENT OFTOOTH SIZE/ARCH SIZEDISCREPANCIESHistorically, the enforced early loss of deciduous teeth (usually due to caries)often necessitated a decision whether to

balance (to maintain the centre line) or compensate (to maintain the buccalrelationship) with further extractions,especially when crowding was present.The advances in restorative techniquesin paediatric dentistry and the moreuniversal availability of comprehensivetreatment with fixed appliances hasmeant these procedures tend to becarried out less and less. Conversely,current practice dictates that deciduous

canines are often extracted early in thehope of correcting the palataldisplacement of their permanentsuccessors. A more elective choice isthe early extraction of teeth for therelief of crowding. This can range fromthe removal of upper primary canines tocreate space for upper lateral incisorsand stop them erupting into crossbite,to serial extraction. The latter procedureis rarely undertaken in its entirety nowthat comprehensive appliances are morereadily available. Early extraction of

premolar units in the late mixed dentition

before eruption of the canines to allowalignment of the labial segments,

however, remains a common practice.The advantages of this are that it allowsfor spontaneous alignment of labiolingual displacement of the incisors(especially in the lower arch), if thecanines are mesially inclined. 2 In theupper arch there is little or nospontaneous alignment of the incisors,

but early loss of first premolars whenthe canines are unerupted, buccallydisplaced and short of space will allowfor eruption of these teeth into the lineof the arch. There is evidence that earlyextraction of first premolars, followed byactive appliance therapy, results in lesslower incisor irregularity than treatmentwith first premolar extractions and fixed appliances, once all the permanent teeth(except the second molars) haveerupted. 3

If non-extraction treatment is planned and begins before loss of the second deciduous molars, in the lower arch theleeway space can be used for relief of crowding, as shown in Figures 13. If alingual arch is placed during the mixed dentition only an arch length decreaseof 0.44 mm has been reported, leaving anaverage of 4.44 mm leeway space. 4 Thisallowed for the resolution of crowding in60% of 107 patients with an average of 4.85 mm crowding at the start of treatment. It must be remembered,

Figure 1. Class II division 2 malocclusion withcrowding: (a) right buccal view; (b) labial view;(c) left buccal view.

a b

c

Figure 2. Treatment for the dentition shown inFigure 1: commencement before loss of lower second deciduous molars: (a) right buccal view; (b) labial view; (c) left buccal view.

a b

c


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however, that in patients in the primarydentition there is often a straightterminal plane at the distal aspect of thesecond deciduous molars. If there is

spacing in the primary dentition as the permanent maxillary and mandibular first molars erupt, the space mesial tolower deciduous molars lets these teethmove forward, allowing the permanentmolars to erupt into a Class Irelationship. This is called an earlymesial shift (Figure 4). However, if thereis no spacing between the deciduousteeth (i.e. a closed primary dentition),there is no mesial movement of themandibular deciduous molars as the

permanent molars erupt, and they eruptinto a cusp-to-cusp relationship. Themandibular leeway space thereforeallows for mesial migration of the lower first molars into a Class I relationshipas the deciduous molars are shed. Thisis called a late mesial shift (Figure 5).Therefore, if lower arch length is

preserved to use the leeway space torelieve crowding, correction of themolar relationship will requiredistalization of the maxillary firstmolars, often using headgear.

Crowding is thought to be related tothe dimension of the dental arches inthat the greatest crowding exists in thenarrower arches. 5 This has led someclinicians to advocate active expansionof the arches in the mixed dentition inan attempt to create space toaccommodate the complete dentition.Unfortunately, it appears that lower arch width, particularly in the

intercanine region, typically decreasesafter treatment, regardless of whether a

case was expanded during treatment or not. This results in higher degrees of relapse in cases where there has beenenlargement of the mandibular arch. 6

EARLY MANAGEMENT OFPOSTERIOR CROSSBITESCrossbites with displacement aregenerally thought to be a functionalindication for early orthodontictreatment. The aim is to stop thecrossbite becoming established in the

permanent dentition, as crossbites withdisplacement are one of the fewocclusal traits that have a slightassociation with the development of temporomandibular joint dysfunctionlater in life. 7 There is evidence of asymmetric muscle activity and altered

bite force in children with a posterior crossbite with displacement. 8,9

Treatment in the primary or early mixed dentition by selective grinding and active expansion with a removable plateis thought to decrease the risk of thecrossbite being perpetuated to the

permanent denti tion. 10

Figure 3. Dentition shown in Figure 1 at end of active treatment: after 22 months: (a) rightbuccal view; (b) labial view; (c) left buccal view.

a b

c

Figure 4. Early mesial shift in spaced primary dentition.

Figure 5. Late mesial shift in closed primary dentition.



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One factor that encourages earlytreatment is the fact that correction canoften be achieved very simply withremovable appliances and minimal

patient compliance within a reasonablysmall time period. As such it is a

procedure that can often be carr ied outin general practice. Although fixed expansion devices such as thequadhelix may result in orthopaedic aswell as orthodontic expansion, 11 thereis evidence that removable appliancesand quadhelices produce similar amounts of dental and skeletalexpansion and have similar relapserates, 12 but tha t the use of removableappliances with midline expansionscrews may result in less buccal tippingof the posterior teeth. 13 Rapid maxillaryexpansion has been found to producemore bodily movement of teeth. 12

EARLY MANAGEMENT OFCLASS III MALOCCLUSIONSThe correction of anterior crossbites inthe mixed dentition may prevent loss of

periodontal attachment of the lower incisors. If only one or two incisors arein crossbite and there is adequatespace available, a removable appliancecan often be used 14 (Figure 6): if spaceneeds to created and more bodilymovement of teeth is required, better results may be achieved with simplefixed appliances 15 (Figure 7). Thesuccess of either depends on creating a

positive overbite at the end of treatment.

Both the above scenarios primarilyrelate to skeletal I or mild skeletal IIIrelationships. Other methods of earlycorrection of severe skeletal

relationships have been described,including the use of functionalappliances 16,17 (Figures 810),

protraction headgear, 18,19 chin caps 20and headgear to the lower arch. 21 All of these treatment modalities surprisinglyseem to have similar clinical effects:

proclination of the upper incisors,retroclination of the lower incisors and rotation of the mandible downwardsand backwards. There also appears to

be a slight anterior movement of themaxilla when protraction headgear isused, especially when accompanied by

palatal expansion. 18 The skeletal effectsof protraction headgear also appear to

be greater in pre-adolescent patients . 19

Early treatment of Class IIImalocclusions is generally notsuccessful in cases with increased lower face height and minimaloverbites. The overriding factor in

whether treatment is successful is theunderlying growth pattern, which tends

to re-impose itself following treatment,especially mandibular prognathism.

EARLY MANAGEMENT OFCLASS II MALOCCLUSIONSThere is currently a resurgence ininterest in the concept of two-phasetreatment: early use of functionalappliances in the mixed dentition,followed by a period of retention and then a second phase of treatment,usually involving the use of fixed appliances. The advocates of earlytreatment feel that starting early willmaximize the chances of growthmodification (especially in female

patients who tend to reach their skeletal maturity earlier), allow for twochances to correct the malocclusionand avoid problems of complianceoften encountered in adolescents. 22

It has been shown, however, that theskeletal contribution to correction of Class II division 1 malocclusionstreated with twin blocks is greater if treatment is carried out during or slightly after the onset of the pubertal

peak in growth velocity. 23 Similar findings have been reported for theBass appliance, 24 the Herbst appliance 25

and the FR-2 appliance. 26 Further research has also shown that the early

a b

Figure 6. Correction of anterior crossbite with removable appliance.

Figure 7. Correction of anterior crossbite withfixed appliance.

a b

c


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use of functional appliances has littleor no long-term benefit in terms of enhanced growth or better outcomeover later one-stage treatment. 27,28

So, if there are no advantages in earlytreatment physiologically, are there any

psychological advantages? There issubstantial evidence that the dentalappearance has an effect on social

perceptions and interaction, 29 and can be a target of teasing. 30 The negativeimpact of malocclusion on self-

perception appears to increase withage. 31 Despite this, early treatment for Class II malocclusion has been reported to have no effect on self-concept, 32

although within this study the childrenlooked at did not present for treatmentwith low selfconcept in the first place.This is supported by other work whichfound that pre-adolescent childrenawaiting orthodontic treatment generallyhave higher than average self-concept. 33

More recent work, however, may showthat early treatment increases self-esteem (K. OBrien, personal

communication). Figures 1113 show thecase of a patient in the mixed dentitionwho requested treatment as a result of concerns about teasing at school.

One consistent finding is theincreased incidence of trauma to theupper labial segment in pre-adolescentchildren with increased overjets. 34,35

Increased overjet appears to be a greater contributor to traumatic injury in girlsthan boys, even though traumatic injuryfrequency is greater in boys. 35,36 A high

percentage of these injuries occur before the age of 10 years, especially in boys 34 (probably due to the rougher nature of boys activities and their moreactive participation in sports). 35

An advantage of starting functionalappliance therapy in the late mixed or

permanent dentition is that thefunctional phase of treatment can befollowed almost immediately by the fixed appliances, which can incorporatemechanics designed to stabilize thenewly established occlusion. By startingtreatment in the mixed dentition, therewill inevitably be a period when theclinician is awaiting further dentaldevelopment before further treatmentdecisions can be made. This will meaneither that treatment will have to bediscontinued during this period or thatsome form of retention regime will haveto be implemented. This may consist of wearing the appliances just at night, theuse of headgear or the use of simpleremovable retainers. If the last policy is

pursued, incorporation of an inclined anterior bite plane on an upper

removable appliance will help tomaintain the sagittal correction and

allow the lateral open bites to improveas the dentition develops. 37

EARLY TREATMENT ANDCOMPLIANCEAnother factor that has been used tofavour early treatment is the greater compliance obtained from pre-adolescent patients. This has certainly

been reported for adherence toinstructions given for removableappliances 38 and for headgear wear, 39

although some studies have found nocorrelation between patients age and level of co-operation. 40,41 Younger children are usually influenced by their

parents and other adults butadolescents are more susceptible to

peer pressure, especial ly in terms of self-image. Of course this can act ineither direction when trying toencourage compliance to orthodontictreatment: if an adolescent hassignificant concerns about theappearance of his or her teeth and has

a b

Figure 8. Class III malocclusion with anterior displacement on closing.

Figure 9. Class III Twin Block appliance used totreat the malocclusion shown in Figure 8.

a

b

Figure 10. Patient shown in Figure 8 at end of active treatment, after 6 months.



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a b

Figure 13. Patient shown in Figure 11: end of active treatment (after 14 months).

friends who are undergoingorthodontics, the treatment will have

peer acceptance and compliance may be forthcoming; however, if no peersare undergoing treatment, orthodontictreatment may not be accepted.

Pre-adolescent children seem lessconcerned about peer approval and the

here and now. 33 This age group isgenerally aware of the reason for referral for orthodontic treatment, and understands the perceived benefits of treatment. 33 There is therefore noindication that pre-adolescent childrenare not psychologically ready for treatment. One of the disadvantages of

early treatment, however, is often therequirement for a second phase of

treatment in the early permanentdentition. Whether the complianceduring this second stage of treatment isaffected by starting treatment in themixed dentition is unknown.

CONCLUSIONSl Expansion of the lower arch in mixed

dentition to address crowding isinherently unstable.

l When correctly planned, earlyextraction of teeth for the relief of crowding may result in increased long-term stability particularly inthe lower labial segment and simplify appliance mechanics duringactive treatment.

l Treatment in the mixed dentition isindicated for anterior and posterior crossbites with displacements ondental health grounds.

l If protraction headgear is planned for treatment of Class IIImalocclusions, treatment should commence in the mixed dentition for maximum benefit.

l Early treatment with functionalappliances for Class II division 1malocclusions does not appear toresult in greater skeletal changethan later treatment, and does notappear to offer any psychological

benefits in the ave rage child.l Risk of trauma to the upper labial

segment may justify early treatmentof Class II division 1 malocclusions,especially in girls.

l Most orthodontic treatment can bestarted in the late mixed dentition

just before loss of the primarymandibular second molar. This willmaximize growth potential and compliance, allow for utilization of the leeway space and keep overallactive treatment time as short as

poss ible .

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2. Stephens CD. The use of natural spontaneous

a b

Figure 11. Class II division 1 malocclusionwith lip incompetence and increased incisor show at rest.

a b

Figure 12. Patient shown in Figure 11 during treatment with high pull headgear and Bassfunctional appliance.



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39. Cureton SL, Regennitter FJ, Yancey JM. Clinicalversus quantitative assessment of headgearcompliance. Am J Orthod Dentofacial Orthop 1993;104: 277284.

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of dentist-evaluated compliance in orthodontics.Eur J Orthod 1992; 14: 463468.

THE BELLE MAUDSLEY 2002PRESENTATION

Professor C.D.Stephens OBE, Dental UpdateAdvisory Board member and President of theBritish Orthodontic Society, congratulatingAndrew DiBiase on the award of the 2002 BelleMaudsley Prize following his delivery of the 2002Belle Maudsley Lecture. The Societys annualconference was this year held at the ScottishExhibition and Conference Centre and wasattended by 1400 delegates including 40 fromoverseas.

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Send your transparencies to:The Executive Editor, Dental Update ,

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2-the timing of orthod tx

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