Molar Incisor Hypomineralisation—To Extract Or to Restore Beyond the Optimal Age?

children

Case Report Molar Incisor Hypomineralisation—To Extract or to Restore beyond the Optimal Age?

Mustafa Elhussein 1 and Hasan Jamal 2,*

1 Faculty of Dentistry, Ibn Sina University, Khartoum P.O.Box 10995, Sudan; [email protected] 2 Eastman Dental Institute, University College London, London WC1X 8LD, UK * Correspondence: [email protected]

Received: 23 July 2020; Accepted: 5 August 2020; Published: 6 August 2020

Abstract: The management of compromised first permanent molars (FPMs) in children presents a clinical challenge to the dental team. Hypomineralised FPMs in molar incisor hypomineralisation (MIH) conditions could undergo post-eruptive breakdown, making them susceptible to caries, leading to their subsequent loss. The planned extraction of compromised FPMs is a valid alternative to complex restorative treatment. However, establishing the presence or absence of third permanent molars, amongst other considerations, is crucial to reaching a successful outcome. Clinicians should understand the importance of an orthodontic examination around the age of 8 years old with regard to establishing a differential therapeutic decision about the ideal timing of MIH-affected FPMs’ extraction in children. The aim of this article is to highlight that, with an interdisciplinary approach, a good outcome can be achieved following the extraction of poorly prognosed FPMs. The most cost-effective way of addressing MIH-affected FPMs is extraction, followed by orthodontic space closure when indicated. This obviates the need for the repeated restorative replacement and saves perfectly healthy premolars from being extracted for space creation in orthodontic treatment in several clinical scenarios.

Keywords: paediatric dentistry; orthodontics; enamel defects; ﬁrst permanent molars (FPMs); molar incisor hypomineralisation (MIH); post-eruptive breakdown (PEB); temporary anchorage devices (TADs)

1. Introduction The term molar incisor hypomineralisation (MIH) was first introduced in 2001, and defined as ‘demarcated, qualitative developmental defects of systemic origin of the enamel of one or more first permanent molar (FPM) with or without the affection of incisors’ [1]. More recently, new patterns have been observed, such as the cusp tips of permanent canines and premolars. hypomineralised second primary molars (HSPMs), which can also affect the cusp tips of permanent canines and premolars [2–4]. It was also noted that, when there are HSPMs, there is a 50% chance that the FPMs may also be affected [5].

1.1. Aetiology Although the aetiology of MIH remain unclear, several causes have been hypothesised. They could be grouped into either maternal or neonatal. For the maternal causes, it could be a nutritional, infectious, haematological, metabolic or endocrinal disturbance. The neonatal causes could be related to premature birth, systemic upset, nephrotic or gastrointestinal disturbances. Recent studies have also shown a possible genetic link to MIH [6,7].

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1.2. Prevalence A recent systematic review reported that, globally, MIH aﬀects 878 million individuals, with an annual prevalence of 17 million [8]. Other regional studies have shown that MIH’s prevalence ranges from 2.4% to 40.2% in studies conducted among populations in Hong Kong, Denmark and Brazil [9–11]. The wide variations in regard to prevalence are thought to be due to a lack of uniformity in the use of classiﬁcation indexes, which were utilised inconsistently and with no standardisation.

1.3. Classification MIH lesions are characterised by being well-demarcated opacities. The colour, the extent of the lesion and the level of sensitivity differ depending on the severity of the condition. Numerous classification criteria were developed to classify MIH lesions. The European Academy of Paediatric dentistry first classified MIH in 2003. The key features for this classification are the demarcation of the opacity, enamel disintegration, atypical restorations, sensitivity, extracted and unerupted teeth [12]. A more basic classification has also been suggested for MIH, which could either be mild or severe [13]. In mild conditions, the demarcated opacities are not associated with a post-eruptive breakdown (PEB), with occasional sensitivity to external stimulus and with less aesthetic concerns. While in severe cases, the demarcated enamel is associated with PEB, spontaneous sensitivity and high aesthetic demands. Another classification was developed, which classified MIH into three categories, mild, moderate or severe [14]:

1. Mild MIH: The demarcated opacities located at non-stress bearing areas, no caries associated with the aﬀected enamel, no hypersensitivity and incisor involvement is usually mild if present; 2. Moderate MIH: The demarcated opacities present on molars and incisors, the post-eruptive enamel breakdown limited to one or two surfaces without cuspal involvement, atypical restorations can be needed and normal dental sensitivity; 3. Severe MIH: Post-eruptive enamel breakdown, crown destruction, caries associated with aﬀected enamel, a history of dental sensitivity and aesthetic concerns.

A detailed scoring system was then put forward, which quantiﬁes MIH’s severity according to the number of teeth aﬀected along with the type and extent of the defect [15]. More recently, a more subjective index was proposed, referred to as MIH treatment need index (MIH-TNI). This index was based on describing the population’s treatment needs, and it is based on two factors, hypersensitivity and PEB [16].

1.4. Clinical Considerations Current research demonstrated that children presenting with MIH (moderate to severe) usually require life-long, extensive and repeated restorative treatments that will eventually fail [17]. Studies have shown that children with MIH exhibited 11 times greater probability of having their teeth restored compared to unaffected children. It has been demonstrated that fissure sealants and fillings used in affected FPMs had over three times greater probability of requiring re-treatment compared to children with unaffected FPMs; this is also complicated with anxious children [18,19]. These failures are primarily related to the mechanical, structural and compositional defects of MIH-affected teeth. Under scanning electron microscopy (SEM), the enamel prisms were shown to have less dense and with less organised hydroxyapatite crystals [20,21]. Regarding composition, transmission electron microscopy (TEM) data have shown that MIH-affected teeth have reduced mineral density and with significantly high protein content [22], in comparison to sound enamel [23,24]. Concerning the mechanical properties, the main aspect of being assessed is the hardness and the modulus of elasticity. MIH-affected teeth were shown to have significantly reduced hardness and elasticity levels in comparison to sound enamel. Several clinical and laboratory studies compared Children 2020, 7, 91 3 of 11

MIH-affected molars and molars with sound enamel concerning dental composite bonding strength to enamel substrate. They have reported that the bond strength to MIH-affected enamel was significantly less in comparison to molars with sound enamel [25]. Regarding the cavity design, studies have shown that if the cavity designs were invasive (i.e., removal of all affected tooth structure), the success rate would be higher in comparison to non-invasive design [26]. Nonetheless, the compromise of sound enamel will result in further tooth weakening, and ultimately, this will compromise the longevity of composite fillings. As highlighted previously, MIH-affected teeth have increased protein content, which directly affects the bond strength. Thus, deproteinization was suggested as a method to enhance bond strength. Although some studies showed improvement in bond strength following deproteinization, there is weak evidence to prove this [27]. This, in return, will negatively affect the restoration-support by the tooth surface [21]. There is also emerging and growing evidence of the influence of MIH on children’s oral health-related quality of life in terms of aesthetic concerns related to the maxillary incisors [28–30].

1.5. Management Strategies: Cost Effectiveness and Long-Term Prognosis Management of moderate to severely affected FPMs can be summed up into three categories; direct restorations (e.g., composite); indirect restorations (e.g., gold-onlays); or extraction (aiming for spontaneous or orthodontic intervention to close the gap). However, due to the aforementioned compositional and structural defects of severely affected FPMs, the restorative option could be questionable and more expensive in most of the cases. A recent model-based analysis aimed to analyse the cost effectiveness of different treatment options for severely affected FPMs [31]. The treatment options included in the analysis were extraction (with or without orthodontic space closure), composite restorations or indirect restorations. Based on their findings, they concluded that the extraction of severely affected FPMs followed by orthodontic alignment was the most cost-effective option with a good long-term prognosis compared to the restorative option [31].

1.6. The Orthodontic Interface: Timely Versus Delayed Extractions It is crucial for general dental practitioners, paediatric dentists, and orthodontists to adopt appropriate clinical guidelines [32–35]. Guidelines on treatment planning FPMs’ extraction in children within the context of malocclusion have been produced. The Royal College guidelines is considered to be the most often cited aid decision-making tool in the UK [35]. However, even when these guidelines are adopted, the management of compromised FPMs yield significant amounts of confusion, which recent articles aimed to clarify [36,37]. The most cost-effective way of addressing the loss of FPMs is orthodontic space closure because it obviates the need for restorative-prosthetic replacement and saves dentally sound premolars from being extracted for space creation in orthodontic treatment. Therefore, a meticulous treatment planning process and an interdisciplinary approach, which depends upon excellent lines of communication between the general dental practitioner, or paediatric dentist, and orthodontist, are essential for achieving excellence in patient care [38]. The extraction of FPMs is considered to be technically more difficult; even a good result is in some way a compromise [39]. Many cases that would benefit from this approach because of the questionable long-term prognosis of these molars are treated with the extraction of perfectly sound premolars. Sandler et al. [39,40] highlighted several reasons for the avoidance of FPMs extraction cases:

Clinician comfort with orthodontics cases involving the planned extraction of premolars for space creation; Lack of experience in handling FPM extraction cases; Presence of an inter-dependence for patients between dental specialists in some ﬁnancially driven healthcare systems. Children 2020, 7, 91 4 of 11

Nevertheless, the planned extraction of FPMs, is dependent on certain circumstances, including, but not limited to [39]:

Level of oral hygiene; • Patient and parent motivation to orthodontic treatment; • Amount and site of crowding; • Presence or absence of other permanent teeth, particularly the third molars. • Children 2020, 7, x FOR PEER REVIEW 4 of 11 It is of paramount importance therefore to consider these circumstances to ensure a patient’s  suitability forPatient such invariablyand parent motivation lengthy courseto orthodontic of fixed treatment; appliance therapy. Depending on the patient’s  Amount and site of crowding; age, the decision Presence to extract or absence FPMs of other would permanent ideally teeth, be made particularly by an the interdisciplinary third molars. team, which includes the clinician who is involved in patient’s dental care, and the orthodontist who will ultimately be It is of paramount importance therefore to consider these circumstances to ensure a patient’s providingsuitability the fixed for appliance such invariably therapy. lengthy course of fixed appliance therapy. Depending on the patient’s age, the decision to extract FPMs would ideally be made by an interdisciplinary team, which includes 2. Cases Presentationthe clinician who is involved in patient’s dental care, and the orthodontist who will ultimately be providing the fixed appliance therapy. 2.1. Case 1—Delayed Extraction of FPMs 2. Cases Presentation A 15-year-old male, presented with a Class I incisor relationship on a mild Class II skeletal base with2.1. increased Case 1—Delayed vertical Extraction proportions of FPMs (Figure1). This was complicated by heavily restored upper first permanentA 15 molars,-year-old restoredmale, presented lower with first a Class permanent I incisor relationship molars, reduced on a mild overbite,Class II skeletal moderate base upper arch and severewith increased lower vertical arch crowding, proportions and(Figure a lower 1). This centreline was complicated discrepancy by heavily to restored the right upper side first (Figure 1). The maxillarypermanent central molars, incisors restored showed lower whitefirst permanent opacities. molars, His dentalreduced history overbite, revealed moderate repeated upper arch and major and severe lower arch crowding, and a lower centreline discrepancy to the right side (Figure 1). The restorative work associated with his MIH-affected FPMs. The patient also presented with signs and maxillary central incisors showed white opacities. His dental history revealed repeated and major symptomsrestorative associated work with associated the heavily with his restored MIH-affected upper FPMs. FPMs. The patient His Orthopantomograph also presented with signs (OPT) and showed signs of molarsymptoms stacking associated of the with upper the heavily right restored and left upper second FPMs. molars, His Orthopantomograph and distally tipped (OPT) lowershowed right and left secondsigns molars of molar (Figure stacking1). of Histhe upper paediatric right and dentist left second referred molars, him and distally to explore tipped the lower potential right and for fixed applianceleft therapy second molars and, if (Figure indicated, 1). His whether paediatric ordentist not extractionsreferred him to of explore FPMs the will potential be planned for fixed as part of appliance therapy and, if indicated, whether or not extractions of FPMs will be planned as part of orthodonticorthodontic treatment. treatment.

Figure 1. Pre-treatment intraoral photographs and radiographs. Figure 1. Pre-treatment intraoral photographs and radiographs.

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With a With view a view to help to help the the patient patient avoid avoid a course a course of root of canal root treatment canal to treatment his upper FPMs, to his treatment upper FPMs, treatmentinvolved involved the extractionthe extraction of the upperof the and upper lower and ﬁrst lower permanent first molars, permanent together molars, with upper together and lower with upper and lowerﬁxed fixed appliances appliances (Figure (Figure2). 2).

Figure 2. Six months following the extraction of all first permanent molars (FPMs). Note the favorable Figure 2. Six months following the extraction of all first permanent molars (FPMs). Note the favorable spontaneous eruption of the second permanent molars. The placement of full fixed appliances was spontaneouspostponed eruption until completeof the second eruption permanent of the second molars. permanent The molars. placement of full fixed appliances was postponed until complete eruption of the second permanent molars. Discussion Discussion Although the timing of FPMs’ extraction is most favourable around a chronological age of 8–10 years old, this older case illustrates the advantages of FPMs’ extraction at a later stage. The extraction Althoughpattern inthe this timing case was of dictatedFPMs’ primarilyextraction because is most of the favourable pain, large restorationsaround a chronological and the questionable age of 8–10 years old,long-term this older prognosis case illustrates of the upper the FPMs, advantages and because of FPMs of the large’ extraction occlusal at restorations a later stage. on the The lower extraction pattern inFPMs. this Furthermore,case was dictated extraction primarily in the lower because arch was of indicated, the pain, because large ofrestorations the severity ofand the the crowding questionable long-termand prognosis space requirements. of the upper FPMs, and because of the large occlusal restorations on the lower In this case, the extraction of FPMs increased the prognosis of the remaining dentition and relieved FPMs. Furthermore,the signs and symptoms extraction associated in the with lower upper arch FPMs. was If the indicated, FPMs had because not been of of poor the prognosis, severity of the crowdingthe and extraction space patternrequirements. might have been the extraction of the first premolars. Although the response of In thisthe second case, permanentthe extraction molars ofis variable FPMs following increased extraction the prognosis of FPMs and of acceptable the remaining positions dentition would and relieved alsothe besigns achieved and irrespectivesymptoms of theassociated timing of with extraction upper [40], FPMs. a favourable If the mesial FPMs eruptive had not position been of of poor prognosis,second the extraction permanent molars pattern was might predictable, have tobeen some the extent, extraction in this case of duethe tofirst a number premolars. of reasons: Although the response of theThe second upper second permanent permanent molars molars is were variable still within following bone at theextraction time of extraction; of FPMs and acceptable positions wouldThe OPTalso revealedbe achieved signsof irrespective molar stacking of ofthe upper timing right of and extraction left second [4 permanent0], a favourable molars, mesial eruptive positionand distally of second tipped lowerpermanent right and molars left second was permanent predictable, molars reflectingto some posterior extent, molar in this crowding; case due to a The distinct vertical growth pattern and presence of a steep mandibular plane, which encouraged number of reasons: molar mesial movement. . The upperMoreover, second the permanent OPT showed molars favourable were positioningstill within of bone third at molars the time following of extraction; space closure . The(Figure OPT revealed3) Perhaps, signs in this of case, molar if elective stacking extraction of upper of FPMs right was prescribedand left second around thepermanent optimum time,molars, and distallyprovided tipped the third lower molars right were radiographicallyand left second detectable, permanent the repeated molars restorative reflecting work might posterior have molar crowding;been avoided. On the other hand, this approach could still be deemed cost effective, as it obviated the . Theneed distinct for further vertical dental growthtreatment i.e.,pattern root canal and treatment presence (Figure of 4). a steep mandibular plane, which encouraged molar mesial movement. Moreover, the OPT showed favourable positioning of third molars following space closure (Figure 3) Perhaps, in this case, if elective extraction of FPMs was prescribed around the optimum time, provided the third molars were radiographically detectable, the repeated restorative work might have been avoided. On the other hand, this approach could still be deemed cost effective, as it obviated the need for further dental treatment i.e., root canal treatment (Figure 4).

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FigureFigureFigure 3. Near 3.3. Near-end-of-treatmentNear-end-end-of--treatmentof-treatment stage stagestage following followingfollowing spacespace closure.closure.closure. Near-end-of-treatmentNear Near-end-end-of--oftreatment-treatment radiographsradiographs radiographs revealedrevealedrevealed favourable favourable favourable third third third molar molar positioning. positioning. positioning. Intermaxillary Intermaxillary Intermaxillary elastics elastics elastics with a with vertical with a verticala vector vertical were vector vector utilised were were utilisedtoutilised actively to actively to enhanceactively enhance enhance interdigitation. interdigitation. interdigitation.

Figure 4. End-of-treatment intraoral photographs. Space closure was fully achieved and orthodontic treatment was completed in 16 months. FigureFigure 4. End 4. End-of-treatment-of-treatment intraoral intraoral photographs. photographs. Space Space closureclosure was was fully fully achieved achieved and and orthodontic orthodontic treatmenttreatment was was completed completed in in16 16 months. months. 2.2. Case 2—Timely Extraction of FPMs

2.2. Case 2A— 16Timely-year- oldExtraction male, presented of FPMs with a Class II division 2 incisor relationship on a mild Class II skeletal base with average vertical proportions. This was complicated by a moderately crowded Aupper 16-year arch,-old buccally male, impacted presented UR3, with and a increased Class II divisionoverbite, 2which incisor was relationship complete to softon atissue mild with Class II skeletal base with average vertical proportions. This was complicated by a moderately crowded upper arch, buccally impacted UR3, and increased overbite, which was complete to soft tissue with

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2.2. Case 2—Timely Extraction of FPMs A 16-year-old male, presented with a Class II division 2 incisor relationship on a mild Class II skeletal base with average vertical proportions. This was complicated by a moderately crowded Children 2020, 7, x FOR PEER REVIEW 7 of 11 upper arch, buccally impacted UR3, and increased overbite, which was complete to soft tissue with no evidence of trauma (Figure5). The maxillary central incisors showed white and cream opacities. no evidence of trauma (Figure 5). The maxillary central incisors showed white and cream opacities. His dental history revealed delayed dental development, and also reported that his-MIH-aﬀected His dental history revealed delayed dental development, and also reported that his-MIH-affected FPMs were extracted at the age of 9. No orthodontic consultation had been sought at the time. His OPT FPMs were extracted at the age of 9. No orthodontic consultation had been sought at the time. His moreover conﬁrmed the presence of all third molars, apart from the lower right third molar. The upper OPT moreover confirmed the presence of all third molars, apart from the lower right third molar. The standard occlusal radiograph showed no evidence of pathology associated with the upper right lateral upper standard occlusal radiograph showed no evidence of pathology associated with the upper incisor and upper right canine. right lateral incisor and upper right canine.

FigureFigure 5. 5.Pre-treatment Pre-treatment intraoral intraoral photographs photographs and and radiographs. radiographs.The The extraction extraction of of all all molar molar incisor incisor hypomineralisationhypomineralisation (MIH)-a(MIH)-affectedﬀected FPMs was was carried carried out out at atthe the age age of 9. of Note 9. Note the congenitally the congenitally absent absentLR8. LR8.

DiscussionDiscussion TheThe FPMs FPMs in this this case case report report were were extracted extracted around around the therecommended recommended optimal optimal age (8 age–11), (8–11), which whichled to led successful to successful spontaneous spontaneous eruption eruption of of the the second second permanent permanent molars molars (Figure (Figure 5 5).). The The space space requirementsrequirements in in the the upper upper arch, arch, however, however, were were deemed deemed to to be be signiﬁcant significant in in this this case; case; perhaps perhaps the the temporizationtemporization or or restoration restoration of of the the upper upper FPMs FPMs might might have have been been a a valid valid treatment treatment alternative alternative at at the the time.time. Additionally, Additionally, the the early early extraction extraction of of the the FPMs FPMs led led to to compromising compromising the the molar molar dentition dentition in in this this case,case, due due to to the the congenital congenital absence absence of of the the lower lower right right third third molar molar (Figure (Figure5). 5). It It is is important important to to take take intointo consideration consideration the the thirdthird molar’smolar’s presence when treatment treatment planning planning for for the the extraction extraction of of FPMs, FPMs, to toensure ensure the the remaining remaining molars molars erupt erupt in in a aposition position that that maintains maintains good good functional functional occlusion. occlusion. In contrast to Class I cases, the extraction of FPMs in growing Class II cases is more critical to plan, particularly with regard to the timing of upper FPMs extraction. This is due to the space requirements often needed in the upper arch for the correction of the incisor relationship and increased overjet. Whilst a favourable mesial eruptive position of second permanent molars was achieved in this case, the timely extraction predisposed the patient to a number of malocclusion features, including (Figure 5): . Round tipping of upper and lower second permanent molars;

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In contrast to Class I cases, the extraction of FPMs in growing Class II cases is more critical to plan, particularly with regard to the timing of upper FPMs extraction. This is due to the space requirements often needed in the upper arch for the correction of the incisor relationship and increased overjet. Whilst a favourable mesial eruptive position of second permanent molars was achieved in this case, the timely extraction predisposed the patient to a number of malocclusion features, including Children 2020, 7, x FOR PEER REVIEW 8 of 11 (Figure5): . Distal tipping of lower second premolars; Round tipping of upper and lower second permanent molars; . Spacing in the lower arch; Distal tipping of lower second premolars; . Excessive retroclination of the lower labial segment that worsened an inherent deepbite. Spacing in the lower arch; TheExcessive aforementioned retroclination features of the are lower a relatively labial segment common that sequelae worsened of the an inherentearly extraction deepbite. of FPMs in some Class II malocclusions, particularly the division 2 type, and they often present with a varying degreeThe of aforementioned severity. features are a relatively common sequelae of the early extraction of FPMs in some Class II malocclusions, particularly the division 2 type, and they often present with a varying degree3. Conclusions of severity.

3. ConclusionsTreatment planning for the extraction of FPMs can present a challenge, particularly in the presence of an underlying malocclusion. The available evidence for managing and prescribing FPMs Treatment planning for the extraction of FPMs can present a challenge, particularly in the presence extraction is considered weak, merely reflecting clinical opinion [35,37]. Up until today, there are no of an underlying malocclusion. The available evidence for managing and prescribing FPMs extraction randomised prospective controlled trials reporting on the outcome of different interventions, hence is considered weak, merely reflecting clinical opinion [35,37]. Up until today, there are no randomised yielding high-quality evidence. prospective controlled trials reporting on the outcome of different interventions, hence yielding With the presence of an orthodontist’s support, the extraction of FPMs should be encouraged. high-quality evidence. This valid treatment approach is not only cost effective, but it limits the repeated restorative events a With the presence of an orthodontist’s support, the extraction of FPMs should be encouraged. child is normally subjected to, thus leading to increased anxiety in these children. It is worth This valid treatment approach is not only cost effective, but it limits the repeated restorative events a mentioning that, orthodontic cases involving the extraction of FPMs has shown a 90% success rate of child is normally subjected to, thus leading to increased anxiety in these children. It is worth mentioning third molars’ eruption, compared to approximately a 55% chance with cases involving premolar that, orthodontic cases involving the extraction of FPMs has shown a 90% success rate of third molars’ extractions, therefore reducing future common complications associated with unerupted and eruption, compared to approximately a 55% chance with cases involving premolar extractions, therefore impacted third molars [41,42]. reducing future common complications associated with unerupted and impacted third molars [41,42]. An orthodontic examination around the age of 8 years old thus makes sense with regard to An orthodontic examination around the age of 8 years old thus makes sense with regard to establishing a differential therapeutic decision, with regard to, the ideal timing of MIH-affected molar establishing a differential therapeutic decision, with regard to, the ideal timing of MIH-affected molar extraction. As described and illustrated in this paper, contemporary fixed appliances (Figures 6 and extraction. As described and illustrated in this paper, contemporary fixed appliances (Figures6 and7) 7) can achieve good and predictable treatment outcomes following the planned extraction of FPMs can achieve good and predictable treatment outcomes following the planned extraction of FPMs irrespective of the chronological ages, particularly with the advent of temporary anchorage devices, irrespective of the chronological ages, particularly with the advent of temporary anchorage devices, which are deemed versatile, thus facilitating space closure in challenging orthodontic cases (Figure which are deemed versatile, thus facilitating space closure in challenging orthodontic cases (Figure8) [43,44]. 8) [43,44].

Figure 6. Fixed appliances and headgear were used to create sufficient suﬃcient space in the upper arch and align the teeth.

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FigureFigureFigure 7. 7. End End-of-treatmentEnd-of-of-treatment-treatment intraoral intraoralintraoral photographs. photographs.photographs. Alignment, Alignment, overbite, overbite, and and overjet overjetoverjet correction correctioncorrection was waswas achievedachievedachieved with withwith fixed ﬁxedfixed appliances appliancesappliances in inin 18 1818 months. months.months.

(a(a) ) (b(b) )

FigureFigureFigure 8. 8.8. ( a(a) )Temporary Temporary anchorage anchorageanchorage devices devicesdevices were werewere used usedused to toto facilitate facilitatefacilitate the thethe space spacespace closure closureclosure of ofof 12 1212 mm mmmm of ofof space spacespace resultingresultingresulting from fromfrom the the planned planned extraction extraction of of of the the the lower lower lower FPMs; FPMs; FPMs; ( b( (b)b )S) Spaces Spacespaces were were were closed closed closed after after after a a period aperiod period of of of9 9 months.9months. months.

TheTheThe unfolding unfoldingunfolding COVID COVID-19COVID-19-19 pandemic pandemicpandemic rendered renderedrendered practice practicepractice guidelines guidelinesguidelines being beingbeing focused focusedfocused around aroundaround limiting limitinglimiting AerosolAerosolAerosol Generating GeneratingGenerating Procedures ProceduresProcedures (AGPs). (AGPs). This ThisThis influences inﬂuencesinfluences the thethe provision provisionprovision of ofof dental dentaldental services servicesservices of ofof paediatric paediatricpaediatric patientspatientspatients [4 [[44555].].]. F ForForor the the current current predicament, predicament, and andand in in the the post post-pandemicpost-pandemic-pandemic era, era, the the aerosols aerosols generated generatedgenerated from fromfrom thethethe repeated repeatedrepeated restorative restorativerestorative work workwork on onon such suchsuch teeth teeth,teeth, ,i.e. i.e.,i.e., ,MIH MIH-aMIH-affected-affectedﬀected FPMs, FPMs,FPMs, might mightmight not notnot be bebe in inin the thethe best bestbest interest interestinterest ofofof patients patientspatients and andand dental dentaldental team teamteam alike. alike.alike. As AsAs highlighted highlightedhighlighted above, above,above, a aa ho holisticholisticlistic management managementmanagement strategy strategystrategy should shouldshould be bebe utilisedutilisedutilised to toto avoid avoidavoid AGPs. AGPs.AGPs.

AuthorAuthorAuthor Contributions: Contributions:Contributions: Writing Writing—originalWriting——originaloriginal draft draftdraft preparation, preparation,preparation, H.J. H.J. and andand M.E.; M.E.;M.E.; writing writing—reviewwriting——reviewreview and and editing, editing, H.J. H.J. andandand M.E.; M.E.; orthodontic orthodontic orthodontic treatments, treatments,treatments, M.E. M.E. M.E. All Allauthors All authors authors have have read have and read read agreed and and agreed to agreed the published to to the the published published version of version theversion manuscript. of of the the manuscript.manuscript. Funding: This research received no external funding. Funding:Acknowledgments:Funding: This This researc researcThehh received received cases describedno no external external in funding. thefunding. article were treated by Mustafa Elhussein at the Chesterfield Royal Hospital, and the Charles Clifford Dental Hospital, under the supervision of Jonathan Sandler and Nicola Acknowledgments:Acknowledgments: The The cases cases described described in in the the article article were were treated treated by by Dr Dr Mustafa Mustafa Elhussein Elhussein at at the the Chesterfield Chesterfield Parkin. We would like to thank Jonathan Sandler, Paul Ashley, and Susan Parekh for their invaluable insights and RoyalcorrectionsRoyal Hospital, Hospital, on this and and work. the the Charles Charles Clifford Clifford Dental Dental Hospital, Hospital, under under the the supervision supervision of of Prof Prof Jonathan Jonathan Sandler Sandler and and DrDr Nicola Nicola Parkin. Parkin. We We would would like like to to thank thank Prof Prof Jonathan Jonathan Sandler, Sandler, Prof Prof Paul Paul Ashley Ashley, ,and and Dr Dr Susan Susan Parekh Parekh for for Conflicts of Interest: The authors declare no conflict of interest. thetheirir invaluable invaluable insights insights and and corrections corrections on on this this work. work.

ConflictsReferencesConflicts of of Interest: Interest: The The authors authors declare declare no no conflict conflict of of interest interest. .

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