An update of the aetiological factors involved in molar incisor hypomineralisation (MIH): a systematic review and meta-analysis

PURPOSE

To systematically review the aetiological factors associated with molar incisor hypomineralisation (MIH). To this day, the aetiology remains unknown. Determining risk factors would allow risk assessment and enhance early diagnosis of MIH in young patients. The aim was to assess, evaluate and summarise the relationship between MIH and reported aetiological hypotheses.

METHODS

Electronic database searches of MEDLINE, EMBASE, EBSCO, LILACS and Cochrane Library were conducted. Authors conformed to PRISMA guidelines. Studies were screened, data extracted, assessment of risk of bias and calibration was completed by two independent reviewers. Meta-analyses with heterogeneity calculations were performed.

RESULTS

Of the potential 8949 studies, 64 studies were included in the qualitative analysis whilst 45 were included in the quantitative analysis. Prenatal factors: results are inconclusive as only unspecified maternal illnesses appear to be linked to MIH. Perinatal factors: prematurity (OR 1.45; 95% CI 1.24-1.70; p = 0.0002) and caesarean delivery (OR 1.45; 95% CI 1.09, 1.93; p < 0.00001) are associated with an increased risk of developing MIH. Birth complications are also highlighted. These three factors can lead to hypoxia, and children with perinatal hypoxia are more likely to develop MIH (OR 2.76; 95% CI 2.09-3.64; p < 0.0001). Postnatal factors: measles, urinary tract infection, otitis media, gastric disorders, bronchitis, kidney diseases, pneumonia and asthma are associated with MIH. Fever and antibiotic use, which may be considered as consequences of childhood illnesses, are also associated with MIH. Genetic factors: an increasing number of studies highlight the genetic and epigenetic influences in the development of MIH.

CONCLUSION

Several systemic and genetic and/or epigenetic factors acting synergistically or additively are associated with MIH, revealing a multifactorial aetiology model. Peri- and postnatal aetiological factors are more likely to increase the odds of causing MIH than prenatal factors.

Best clinical practice guidance for clinicians dealing with children presenting with molar-incisor-hypomineralisation (MIH): an updated European Academy of Paediatric Dentistry policy document

AIM

To update the existing European Academy of Paediatric Dentistry (EAPD) 2010 policy document on the 'Best Clinical Practice guidance for clinicians dealing with children presenting with Molar-Incisor-Hypomineralisation (MIH).'

METHODS

Experts, assigned the EAPD, worked on two different topics: (A) Aetiological factors involved in MIH, and (B) Treatment options for the clinical management of MIH. The group prepared two detailed systematic reviews of the existing literature relevant to the topics and following a consensus process produced the updated EAPD policy document on the 'Best Clinical Practice guidance for clinicians dealing with children presenting with molar-incisor-hypomineralisation (MIH).' The GRADE system was used to assess the quality of evidence regarding aetiology and treatment which was judged as HIGH, MODERATE, LOW or VERY LOW, while the GRADE criteria were used to indicate the strength of recommendation regarding treatment options as STRONG or WEAK/CONDITIONAL.

RESULTS

(A) Regarding aetiology, it is confirmed that MIH has a multifactorial aetiology with the duration, strength and timing of occurrence of the aetiological factors being responsible for the variable clinical characteristics of the defect. Perinatal hypoxia, prematurity and other hypoxia related perinatal problems, including caesarean section, appear to increase the risk of having MIH, while certain infant and childhood illnesses are also linked with MIH. In addition, genetic predisposition and the role of epigenetic influences are becoming clearer following twin studies and genome and single-nucleotide polymorphisms analyses in patients and families. Missing genetic information might be the final key to truly understand MIH aetiology. (B) Regarding treatment options, composite restorations, preformed metal crowns and laboratory indirect restorations provide high success rates for the posterior teeth in appropriate cases, while scheduled extractions provide an established alternative option in severe cases. There is great need for further clinical and laboratory studies evaluating new materials and non-invasive/micro-invasive techniques for anterior teeth, especially when aesthetic and oral health related quality of life (OHRQoL) issues are concerned.

CONCLUSIONS

MIH has been studied more extensively in the last decade. Its aetiology follows the multifactorial model, involving systemic medical and genetic factors. Further focused laboratory research and prospective clinical studies are needed to elucidate any additional factors and refine the model. Successful preventive and treatment options have been studied and established. The appropriate choice depends on the severity of the defects and the age of the patient. EAPD encourages the use of all available treatment options, whilst in severe cases, scheduled extractions should be considered.

Peripartum events and molar-incisor hypomineralisation (MIH) amongst young patients in southwest France

AIM

This was to investigate the association of peripartum events with the occurrence of MIH.

METHODS

This study, carried out between 2010 and 2011, was based on objective information noted in child health booklets on putative risk factors for MIH during the Peripartum period, aged between 6 to 28 years. The target population consisted of patients with MIH and a control group. Among the 849 patients examined by two calibrated paediatric dentists, 75 patients with MIH were recorded. These patients attended for consultation either at the teaching dental hospital of Bordeaux (France) or at a private dental practice (Bordeaux, France). Pearson's Chi-squared test was used and Odds ratios (OR) with 95 % test-based confidence intervals (CI) were calculated.

RESULTS

Correlations were observed between hypoxia during delivery and occurrence of MIH (OR = 6.1; CI = 1.7-21.85), and also between birth by caesarean section and MIH (OR = 2.9; CI = 1.2-6.9). There was no association between prematurity and MIH.

CONCLUSIONS

Peripartum events such as hypoxia during birth or delivery by caesarean section are suggested to be risk factors for the occurrence of MIH in this population.

Identification of double mandibular canals: literature review and three case reports with CT scans and cone beam CT

OBJECTIVES

The aim of this study is to describe three rare cases of double mandibular canals identified using three-dimensional imaging techniques and to discuss how frequently this variation occurs.

METHODS

A review of the current literature is presented and the study methods are discussed. Three hitherto unpublished cases of double mandibular canals are presented and described, two of them observed by CT scans and the third by cone beam CT (CBCT). They were identified from a pool of more than 6000 mandibular CT scans and CBCT images. These examinations were carried out in the context of pre-implant analyses in the mandible area.

RESULTS

Mandibular canals can be detected on panoramic radiographs. However, as confusion is possible when using two-dimensional images, it is only with tomographic imaging that some of these distinctive features can be identified. The case revealed by CBCT is the only one reported in the literature to date using this means of identification.

CONCLUSIONS

The presence of bifid mandibular canals is very rare, yet it is important to recognize this anatomical variation in any surgical procedures involving the lower jaw and its presence can only be confirmed by volumetric imaging.

La tomographie volumétrique numérisée par le système NewTom : intérêt de ce nouvel examen d'imagerie médicale chez l'enfant

In some cases, after preliminary clinical examination, medical imaging can provide indispensable complementary information for the care of young patients. Volume imaging using two- and three-dimensional reconstructions provides the most complete information possible. Problems involving the superposition of anatomical structures, which can occur with conventional X-rays, are a thing of the past, and this technique represents the future in this field. In high-density tissue such as bone or teeth, tomodensitometry is the preferred examination as it can give a three-dimensional approach to the study. However, because of the high radiation dose required, scanner is still a second intention examination. Development of digital volume tomography using NewTom system, designed for maxillofacial exploration, produces the same type of image for a very much reduced X-ray dose, and at low cost. Although the use of this new examining technique is developing rapidly in Europe and throughout the world since its recent introduction, France is lagging behind as to date there are only seven machines in the entire country. The main uses in children, illustrated by original clinical cases, relate to preoperative surgery planning, post-trauma diagnostic workups, orthodontic checkups, postoperative follow-up and TMJ examinations. The purpose of this article is to inform dental surgeons, paediatricians and doctors about this new medical imaging examination, which will most definitely have a place in the battery of diagnostic tools available to us. After weighing the advantages/risks involved, it should be possible to reduce the number of tomodensitometry exams in favour of this new examination technique in children according to the clinical examination data and diagnostic information required.

Hypsodontia in Castor canadensis: an anatomical and histological study

OBJECTIVES

The aim of this original study is to describe the dental morphology and anatomy of Castor canadensis and to compare results with existing data in the literature relating to this mammal. This will give us a better knowledge of its very distinctive dental system, representative of rodent typology.

MATERIAL AND METHODS

The authors used an osteological sample that is rarely found in Europe. A series of horizontal histological sections of the labial and jugal dental organs were prepared at different coronal and radicular levels for study under the optic microscope. Coloration was applied for tissue differentiation.

RESULTS

Observation of the histological sections reveals an enlargement of the space reserved for the pulp tissue which increases from the crown towards the widely open apex of the incisors. These characteristics are not found in the jugal teeth which, although they also have an open apex, present a different configuration.

CONCLUSION

The dental organs of Rodents in general and Castorides in particular are subject to a constant eruptive force throughout their lifetime. This permanent dental growth occurs as the dental system undergoes intense abrasion, especially the incisors.

[Carabelli's tubercule in the Wolof ethnic group (Senegal)]

The authors study the Carabelli's trait in a Wolof population (Senegal). This morphologiest alteration is mainly present on the first permanent maxillary molar.

MATERIAL AND METHODS

195 left and right first molars of 102 individuals with one equal sex distribution were used. The morphological examination of 194 second maxillary molars (left and right) completed the study.

RESULTS

They show a frequency of 11.8% traits, either individualized (6.7%), either hypertrophic (5.1%), with a predominance of attenuated (37.4%) or absent formations (50.8%), as well as a sexual dimorphism (19% of individualized or hypertrophic traits in the female population, versus 4.2% in the male). The presence of an attenuated trait (grooves and pits) on the second molars follows also a repartition in favor of the female population (24% versus 4.2%).