Molar incisor hypomineralization: a survey of members of the Australian and New Zealand Society of Paediatric Dentistry

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1 SCIENTIFIC ARTICLE Australian Dental Journal 2008; 53: doi: /j x Molar incisor hypomineralization: a survey of members of the Australian and New Zealand Society of Dentistry FA Crombie,* DJ Manton,* KL Weerheijm, NM Kilpatrickà *School of Dental Science, The University of Melbourne, Victoria. Dental Centre, Milletstraat Amsterdam, The Netherlands. àroyal ChildrenÕs Hospital and Oral Health Research Unit, Murdoch ChildrenÕs Research Institute, Melbourne, Victoria. ABSTRACT Background: Worldwide, molar incisor hypomineralization (MIH) affects a substantial number of children and impacts greatly on treatment need and dental anxiety, yet there is little information regarding its prevalence, aetiology, presentation and management. The aims of this survey were to assess awareness and perceptions of the Australian paediatric dental community concerning MIH, and to describe current treatment strategies. Methods: A questionnaire, based upon a previous European study, was sent to all Australian members of the Australian and New Zealand Society of Dentistry. The questionnaire sought information on clinical experience of MIH, knowledge of prevalence, aetiology and contemporary management strategies for MIH. Results: One hundred and thirty useable responses were received (58.8 per cent response rate) of which 36 were paediatric, 6 paediatric dentistry postgraduate students, 59 general, 14 dental therapists and 14 specialists in other fields. Most (98.5 per cent) respondents were familiar with MIH and encountered it in their practice. The majority (73.1 per cent) estimated that MIH occurred in between 5 to 25 per cent of their clinical practice and almost all (96.9 per cent) considered it to be a clinical problem. Only 16.9 per cent of respondents were aware of existing prevalence data and 96.9 per cent valued investigating the prevalence of MIH. No consensus existed regarding the aetiology of MIH or its restorative management. used preformed crowns significantly more than non-specialists, however glass ionomer cements were popular with all groups. Conclusions: MIH is a well recognized and widely encountered clinical condition. MIH presents several clinical problems and is worthy of further investigation. Currently, no consistent clinical management strategies are utilized. Key words: Hypomineralization, dental enamel, MIH, knowledge. Abbreviations and acronyms: ANZSPD = Australian and New Zealand Society of Dentistry; DDE = Developmental Defects of Enamel; GICs = glass ionomer cements; MIH = molar incisor hypomineralization; SSCs = stainless steel crowns. (Accepted for publication 1 November 2007.) INTRODUCTION The term molar incisor hypomineralization (MIH) has been defined recently to describe the phenomenon of demarcated, qualitative defects of enamel of systemic origin, affecting one or more permanent molars with or without involvement of the incisor teeth. 1 As such, it encompasses a wide range of conditions 2 with which the dental clinician is likely to be familiar, including: idiopathic enamel hypomineralization in the first permanent molars, hypomineralized first permanent molars, non-fluoride hypomineralization in permanent first molars, cheese molars, non-fluoride enamel opacities, idiopathic enamel opacities and opaque spots. Clinically, MIH may present as discrete, opaque lesions, ranging from white to yellow-brown, distinct from the more diffuse linear opacities usually associated with fluorosis, and may be associated with post-eruptive enamel loss making it potentially difficult to distinguish from enamel hypoplasia. The distribution of the condition is often asymmetric, commonly with marked variation in severity within an individual. 1,3 160 ª 2008 Australian Dental Association

2 Molar incisor hypomineralization Several challenges are presented by MIH to both the affected individual and treating clinician, with a significant increase in treatment need being reported for those with MIH. 4 8 These teeth are often sensitive, impacting on oral hygiene practices and vulnerable to caries so that intervention may be required soon after eruption. Increased treatment need is not only due to increased caries susceptibility but also ongoing deterioration in the affected teeth and marginal breakdown impacting on the durability of restorations. In some cases, extraction is the most viable long-term option which may have major orthodontic implications, as well as representing a significant and stressful procedure for a young patient. 8 When considered in conjunction with difficulties in oral access for the clinician, limited cooperation, difficulty in achieving adequate local analgesia and the need for multiple re-treatments, it is hardly surprising these patients also experience higher levels of dental anxiety and or phobia. 4 If the anterior teeth are affected then there may be significant aesthetic issues and clinical challenges. Estimates of the prevalence of MIH vary widely in the literature, with data ranging from 3 to 50 per cent in general population studies This variation may reflect a prior lack of both a consistent classification index and a standardized methodology of assessment for MIH. 15 Since most studies assess developmental defects using the Developmental Defects of Enamel (DDE) Index, rather than MIH specifically, prevalence figures are generally based on data for demarcated opacities as this is the DDE category most representative of the lesions of MIH. There is a higher incidence of developmental defects (up to 81 per cent) in children with co-existing medical conditions, however the majority of studies do not distinguish between demarcated and diffuse lesions so it is unknown what percentage would be considered affected by MIH The aetiology of MIH is still unclear and whilst several factors (such as birth complications, medication, acute medical conditions or environmental contaminants) have been implicated, available evidence is equivocal A 2003 European survey of paediatric investigating the existence and prevalence of MIH in Europe reported that, although MIH was widespread, little prevalence data was available and that the majority of clinicians perceived MIH to be a clinical problem worthy of further investigation. 30 Similarly in Australia, there is a dearth of information regarding the prevalence and significance of MIH. The aims of this study were: (1) to ascertain the knowledge and opinions regarding MIH in a population of Australian dental care providers; and (2) to describe their clinical experience associated with MIH. MATERIALS AND METHODS A questionnaire was modelled (with approval) after that of Weerheijm and Mejare, 30 including the same clinical photographs (Fig 1) and five questions posed in 2003, with the addition of three supplementary clinical photographs and questions regarding clinical problems, aetiology and restorative care which were beyond the scope of the original questionnaire. The Human Research Ethics Committee of The University of Melbourne granted approval for the study (No ). Permission was granted by the Federal Committee of the Australian and New Zealand Society of Dentistry (ANZSPD) to access their mailing list. Participants were asked to supply basic demographic data which were de-identified upon receipt of the questionnaire. The remaining questions investigated the respondentsõ knowledge and opinions regarding MIH, including prevalence, incidence, clinical challenges, aetiology and restorative management. Questionnaires were distributed via mail and included postage-paid self-addressed envelopes for return. Fig 1. Examples of the images of MIH used in the present survey. These were the same images used by Dr K Weerheijm and Dr I Mejare in the 2003 European survey. ª 2008 Australian Dental Association 161

3 FA Crombie et al. One month after the initial mail-out a second identical reminder mail-out was sent to non-respondents. 31,32 Data were entered into an Excel spreadsheet (Microsoft Corp, Seattle, WA, USA) and analysed using SPSS Version 14.0 (SPSS Inc, Chicago, IL, USA). Categorical data were analysed using the Chi-square (v 2 ) test. The critical level for alpha was set at RESULTS Of the 239 questionnaires mailed, 148 responses were received; of these, 14 questionnaires were returned due to change of address and four replies were to the effect that the recipient was no longer involved in clinical practice. Therefore, from 221 remaining eligible recipients, 130 valid questionnaires remained, a response rate of 58.8 per cent. A variety of clinicians are represented in the sample: 36 paediatric, 6 paediatric dentistry postgraduate students, 59 general, 14 dental therapists, 13 orthodontists, 1 endodontist and 1 unknown. Several questionnaires were partially completed with many non-paediatric specialists leaving questions unanswered since these were not applicable to their field of practice. Responses were received from locations across Australia, with all states and territories except the Northern Territory represented. There were no statistically significant differences in the familiarity with, reported prevalence of, or increasing incidence of MIH between the different states and territories. Tables 1 and 2 summarize the knowledge and perceptions of MIH reported by the dental care providers. Almost all respondents (98.5 per cent) were familiar with MIH and encountered it in their practice (95.4 per cent). Most respondents estimated the prevalence in their practice to be between 5 and 25 per cent. and dental therapists reported a higher prevalence than general (v 2 = 29.41, df = 16, p = 0.021); just over half (53.1 per cent) reported that the incidence of MIH was increasing, 26.2 per cent were unsure and 20.0 per cent did not think there was any increase. However, less than one-fifth (16.9 per cent) of respondents were aware of any prevalence data for Australia. In contrast, the vast majority (96.9 per cent) felt the prevalence of MIH in Australia was worth investigating. A variety of views were expressed regarding the aetiology of MIH with many respondents indicating uncertainty in this area by the use of question marks or comments at the side of the question (Table 1). The overwhelming majority implicated medical conditions, approximately one-half believed there is a genetic component or that medications are involved, and less than one-third considered environmental contaminants or fluoride relevant factors. Clinical challenges posed by MIH were reported by 96.9 per cent of clinicians with the most common problems reported as aesthetic issues, establishing the margins of sound tooth during cavity preparation and the long-term success of restorations (Table 2). Some issues presented a challenge for all clinicians, particularly aesthetics and determining the margins of the MIH lesions. Others were more common, in particular clinician groups with non-paediatric reporting difficulties providing adequate restorations (v 2 = 11.30, df = 4, p = 0.023) and achieving long-term success of Table 1. Clinician awareness, knowledge and perceptions of MIH Question postgraduates General Dental therapists All Yes N (%) Are you familiar with these types of teeth? 36 (100) 6 (100) 58 (98.3) 14 (100) 128 (98.5) Do you encounter these teeth in your practice? 36 (100) 5 (100)* 56 (94.9) 14 (100) 124 (95.4) Approximately what percentage of patients do you observe these teeth in? <10% 14 (38.9) 4 (66.7) 47 (79.7) 8 (57.1) 85 (67.4) 10 25% 15 (41.7) 2 (33.3) 10 (16.9) 6 (42.9) 35 (27.8) >25% 5 (13.9) 0 (0.0) 1 (1.7) 0 (0.0) 6 (4.8) In your practice do you feel the incidence has 24 (66.7) 2 (33.3) 26 (44.1) 11 (78.6) 69 (53.1) increased in the last 10 years or less? Are you aware of prevalence data for your country? 11 (30.6) 2 (33.3) 6 (10.2) 1 (7.1) 22 (16.9) Do you think it would be worthwhile 35 (97.2) 6 (100) 58 (98.3) 14 (100) 126 (96.9) investigating the prevalence? Which factors do you think are involved in the aetiology of MIH?* Genetic 18 (50.0) 4 (66.7) 31 (52.5) 7 (50.0) 68 (52.7) Antibiotics medications 15 (41.7) 5 (83.3) 33 (55.9) 5 (35.7) 66 (51.2) Chronic medical conditions 34 (94.4) 6 (100) 43 (72.9) 11 (78.6) 106 (82.2) Acute medical conditions 36 (100) 6 (100) 59 (90.8) 14 (100) 122 (94.6) Fluoride 9 (25.0) 1 (16.7) 19 (32.2) 3 (21.4) 40 (31.0) Environmental contaminants 16 (44.4) 6 (100) 15 (25.4) 4 (28.6) 42 (32.6) *One respondent did not complete this question. 162 ª 2008 Australian Dental Association

4 Table 2. Clinical problems encountered with MIH and reasons for material choice Molar incisor hypomineralization postgraduates General Dental therapists All Do you think MIH is a clinical problem? If yes; 35 (97.2) 6 (100%) 58 (98.3) 14 (100) 126 (96.9) do you experience problems with: Diagnosis 9 (25.0) 1 (16.7) 22 (37.3) 4 (28.6) 38 (29.2) Aesthetics 35 (97.2) 6 (100) 49 (83.1) 13 (92.9) 116 (89.2) Achieving adequate LA 25 (69.4) 5 (83.3) 34 (57.6) 8 (57.1) 77 (59.2) Determining the margins of affected tooth 31 (86.1) 6 (100) 50 (84.7) 12 (85.7) 103 (79.2) Providing adequate restorations 25 (69.4) 6 (100) 50 (84.7) 13 (92.9) 98 (75.4) Long-term success of restorations 24 (66.7) 6 (100) 50 (84.7) 14 (100) 101 (77.7) Achieving patient comfort (for function, OH) 23 (63.9) 6 (100) 34 (57.6) 8 (57.1) 78 (60.0) Which factors influence your choice of restorative material?* Adhesion 31 (86.1) 5 (83.3) 51 (86.4) 13 (92.9) 102 (87.9) Aesthetics 21 (58.3) 6 (100) 23 (39.0) 6 (42.9) 58 (50.0) Patient parent preference 12 (33.3) 2 (33.3) 14 (23.7) 3 (21.4) 31 (26.7) Durability 34 (94.4) 6 (100) 42 (71.2) 8 (57.1) 91 (78.4) Remineralization potential 10 (27.8) 4 (66.7) 37 (62.7) 12 (85.7) 77 (66.4) Sensitivity 27 (75.0) 4 (66.7) 35 (59.3) 10 (71.4) 77 (66.4) Personal experience 26 (72.2) 2 (33.3) 37 (62.7) 14 (100) 80 (69.0) Research findings 18 (50.0) 6 (100) 13 (22.0) 3 (21.4) 41 (35.3) *Percentages exclude those who left this question unanswered marked N A, in All column. restorations (v 2 = 11.17, df = 4, p = 0.025) significantly more than paediatric specialists (Table 2). Reasons given for choosing materials are shown in Table 2. Adhesion was a decisive factor for most clinicians regardless of their practice type, however there was considerable variation between practitioner groups for other influences. Nonetheless, durability, sensitivity and personal experience were cited by more than half of respondents in each of the clinical groups except paediatric postgraduates for the latter. Table 3 summarizes which materials the practitioners report using to manage these teeth (collapsed data). Glass ionomer cements (GICs) were used widely and composite resin was also popular. Resin modified GICs, compomer, flowable composite, amalgam and cast restorations were not used by the majority of clinicians. Preformed crowns were used significantly more by paediatric and paediatric dentistry postgraduate students than nonpaediatric (v 2 = 92.84, df = 20, p < 0.001). DISCUSSION This is the first published study to address the knowledge, clinical experience and perceptions of MIH in the Australian dental community. While this survey does replicate some research undertaken in Europe into clinician knowledge of MIH, previously reported clinical issues appear to have been only anecdotal and information on how these teeth are being restoratively managed has not been sought. The study population were members of the ANZSPD who have a particular interest in childrenõs dentistry. Consequently, they may see a larger proportion of children in their practice and be more aware of issues relating to paediatric dentistry so care must be taken in extrapolating the results to the general dental community. The small number of dental therapists may not be a representative sample. Table 3. Materials used in MIH affected teeth* postgraduates General Dental therapists All Yes N (%) High fluoride glass ionomer cement 28 (80.0) 5 (83.3) 47 (79.7) 14 (100) 95 (82.6) Glass ionomer cement 26 (74.3) 4 (66.7) 49 (83.1) 13 (92.9) 94 (81.7) Resin modified glass ionomer cement 14 (40.0) 5 (83.3) 27 (47.8) 4 (28.6) 51 (44.3) Compomer 8 (22.9) 5 (83.3) 15 (25.4) 0 (0.0) 28 (24.3) Flowable composite resin 16 (45.7) 4 (66.7) 24 (40.7) 2 (14.3) 46 (40.0) Composite resin 28 (80.0) 6 (100) 44 (74.6) 4 (28.6) 84 (73.0) Amalgam 6 (17.1) 3 (50.0) 21 (35.6) 4 (28.6) 36 (31.3) Preformed crowns 34 (97.1) 6 (100) 34 (57.6) 1 (7.1) 77 (67.0) Cast restorations 9 (25.7) 5 (83.3) 21 (35.6) 0 (0.0) 36 (31.3) *Excludes where entire question was blank or marked N A. All includes all respondent classifications. ª 2008 Australian Dental Association 163

5 FA Crombie et al. The vast majority of clinicians were familiar with teeth typical of MIH which was consistent with the results of the European survey. 30 The low awareness of prevalence data also mirrored the findings of the European study where only 23 per cent reported that prevalence data were available. It is important to note that the European survey was of paediatric only, the clinician group which, in this study, reported the highest level of awareness. MIH would appear to be an issue of interest for the dental community since the overwhelming majority of respondents, both in the present and European study, felt that investigating the prevalence would be worthwhile. and dental therapists deal exclusively with children, therefore it is not surprising these groups express differences in experience, particularly an increased prevalence in their practice, compared to general whose adult patients, either through loss or restoration of the affected teeth, may no longer exhibit signs of MIH (Table 1). Just over half of the clinicians believed that the incidence of MIH was increasing, however little support exists in the literature. The perceived increasing burden of care associated with this dental disorder emphasizes the need for a comprehensive study of the prevalence of MIH. To do this, a standardized assessment tool must be developed to allow valid comparisons in the future. The development of an appropriate index for MIH has been discussed by an eminent panel, and while no consensus was achieved, it was agreed that any index ought to: record the size as well as position and characteristics of the lesions; be easy to understand and to become proficient in the use of; and be simple and practical to utilize in the field. 33 The aetiology of MIH is poorly understood, and is likely to be multifactorial, with susceptibility varying between individuals despite being exposed to the same intrinsic or extrinsic challenges. This has been reported for the other major hypomineralized condition of enamel, dental fluorosis, 34,35 and animal models also indicate a genetic risk component for non-fluorotic hypomineralized enamel. 36,37 The exact aetiological mechanism(s) of enamel hypomineralization and why there is markedly asymmetric presentation in individuals remain unknown. While most respondents believed medical conditions to be involved in the aetiology, which is supported by several studies reporting a higher incidence of developmental enamel defects in medically compromised populations, just over half in the present study thought there was a genetic component. A number of respondents also implicated fluoride, which may indicate there is still confusion in the dental community regarding differentiation of fluorosis and other developmental enamel defects. It is important to establish and disseminate aetiological information so that clinicians are able to accurately assess risk and institute appropriate reviews and or intervention. The present study confirms that the significant clinical difficulties reported previously in the literature associated with these teeth are also experienced by Australian clinicians. 1 The wide variety of materials reportedly used in the management of MIH affected teeth possibly reflects the lack of any evidence-based guidelines; published recommendations currently available are mostly review articles offering general but not scientifically backed advice. This is supported by the high number of practitioners citing personal experience, but not research findings, as an influence on material choice. The most commonly used materials were GICs (including high fluoride release varieties), composite resin and preformed crowns (also known as stainless steel crowns or SSCs). There were differences between operator groups with dental therapists particularly relying on GICs. Their choice of material was influenced by adhesion, remineralization potential and personal experience. However, there is no evidence currently available regarding the bonding or remineralization capacity of GIC to teeth with developmentally defective enamel, therefore it is not surprising that the majority of therapists reported difficulties providing adequate and long lasting restorations. were most concerned by durability and utilized SSCs significantly more than other groups, however it must be remembered that they are likely to be managing the more severe cases. This is consistent with other research (relating to caries) which has found SSCs are offered more commonly by paediatric and their use is rare amongst general and in the public sector. 38,39 were most likely to take research findings into consideration. There is some support for the use of SSCs, with no significant difference in longevity reported over a 2-year period between cast restorations and SSCs. 40 The latter having the advantages of being relatively inexpensive and a single visit procedure which is critical for treatment under general anaesthetic. The viability of SSCs as a long-term restorative solution is questionable and, in reality, is deferring the more clinically demanding and costly cast restorations rather than eliminating the need for them. Adhesion was the most commonly reported influence on material choice by general ; however, it was an important factor for all groups. While little is known about the adhesion of GIC to these teeth, there has been some investigation into composite resin. It was found that the bond strength is lower to this hypomineralized enamel but it was also reported that the predominant failure was cohesive (within enamel) not adhesive. 41 Determining margins was an issue for the majority of responders and an important one in light of the inherent weakness of the enamel and likelihood of this contributing to restorative failures. No clinical technique to 164 ª 2008 Australian Dental Association

6 Molar incisor hypomineralization determine where sound enamel begins has been outlined in the literature. Authors have recommended that margins be placed in apparently sound enamel without specifying how this is achieved. 1,6,7 Furthermore, one study reported that even the visually normal enamel in these teeth was 5 per cent less mineralized than truly unaffected enamel. 42 This 5 per cent deficit has been reported in association with a dramatic reduction in the mechanical properties of hypomineralized teeth. 43 Pretreatment with bleach (5% sodium hypochlorite) has been suggested, putatively to improve bond strength by removing enamel proteins and to improve the appearance of discoloured lesions prior to sealing restoration. 44 Currently, the evidence for this approach is based mostly on case reports. 45 Basic research is required into the aetiology, structure and clinical characteristics of MIH teeth to determine whether current caries-model management strategies are appropriate for MIH. The authors suggest that further investigation into the interactions, physical properties and clinical performance of restorative materials when placed in MIH affected teeth is undertaken so that evidence-based treatment guidelines can be developed. CONCLUSIONS Molar incisor hypomineralization is a condition widely recognized by members of the ANZSPD and poses significant clinical problems for the majority, especially difficulties in providing high quality restorative care. There is considerable variation in knowledge and opinions regarding the prevalence, aetiology and the clinical management of MIH. The majority of respondents in the present study know little of, but support further investigation into, the prevalence of MIH. ACKNOWLEDGEMENTS The authors acknowledge the support of the Murdoch ChildrenÕs Research Institute and the Cooperative Research Centre for Oral Health Science, The University of Melbourne. REFERENCES 1. Weerheijm KL. Molar incisor hypomineralisation (MIH). 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