**1. Introduction**

422 Contemporary Approach to Dental Caries

Yap, A. U., Khor, E., & Foo, S. H. (1999). Fluoride release and antibacterial properties of

305.

new-generation tooth-colored restoratives. *Operative Dentistry*, Vol. 24(5), pp. 297-

The prevalence of dental caries has been reduced over the years due to increased access of fluorides, such as fluoride tooth paste, to dental services and to oral health education on the great part of the population. However, a significant portion of the same population still remains undertreated and show dental cavities as after-effects of this oral disease. In spite of dental caries is strongly influenced by social, economic, cultural, religious and environmental factors, its severity may be increased by structural changes of enamel/dentin such those observed in cases of molar incisor hypomineralization (MIH). In a Brazilian survey, children with MIH showed higher caries experience in the permanent dentition than the general population of similar age. (da Costa-Silva et al., 2010) The MIH increases the dental caries risk as consequence of affected teeth because they are not only soft and porous enamel teeth but also very sensitive to stimuli making effective oral hygiene difficult. (Kilpatrick, 2009) Several aetiological factors are mentioned as the cause of MIH (Alaluusua, 2010, Lygidakis et al., 2010, Crombie et al., 2009, Brook, 2009) and they are frequently associated with childhood diseases or nutritional conditions during the first three years of life. (Fagrell et al., 2011)

Clinically, MIH can create serious drawbacks for the dentist as well as for the child affected. For dentists, the problems are related to unexpectedly rapid caries development in the erupting first permanent molar and unpredictable behaviour of apparently intact opacities. Moreover, these teeth are very sensitive and often require extensive treatment since rapid breakdown of tooth structure may occur, giving rise to acute symptoms and complicated treatments. Defected enamel teeth require complex treatment solutions and the different treatment options will depend on the extension of the defect, the degree of tooth eruption, the oral hygiene and diet habits of the patient. According to the severity of the case, the treatment ranges from topical fluoride varnish, to the use of adhesive materials for restorative procedures, or even the extraction of the teeth associated with orthodontic therapy. (Lygidakis et al., 2010, Lygidakis, 2010) The child, on the other hand, will experience pain and sensitivity, even when the enamel is intact, suffering from toothache during teeth brushing. Often, there is more difficulty to anaesthetize the MIH molars when treatment is indicated. Furthermore, children may also complain about the appearance and

Molar Incisor Hypomineralization:

carious lesion. (Kilpatrick, 2009)

Developmental defects of enamel

Clinical aspects

Clinical appearance

Characteristics Hypomineralised enamel or

tissue

in incisors

enamel opacities

Enamel defect Qualitative quantitative

yellow-brown coloration

Assymmetrical opacities

Normal thickness of the enamel Demarcated opacities of white to

Enamel is soft, porous and poorly delineated from normal tooth

Post eruptive breakdown in molars

Fig. 1. A – Assymmetrical opacities

Fig. 1. B – Assymmetrical opacities in upper first permanent molars

Commission on Oral Health, Research and Epidemiology (FDI, 1982)

Aetiological factorsRemains obscure Identifiable systemic or local insult

Table 1. Differences between two developmental defects of enamel according to FDI

Morphological, Aetiological, Epidemiological and Clinical Considerations 425

opacities (Figures 2A to 2F) to those covering much or the entire crown affecting cuspal areas and sparing the cervical areas. (Brook, 2009) CHAWLA ET AL. 2008 (Chawla et al., 2008) suggested that yellow–brown enamel defects are more severe than white–opaque ones it means that the stained degree of MIH enamel, may be used clinically to reflect the severity of the defect. (Farah et al., 2010a) In severe cases, the defective enamel is lost shortly after molar eruption, exposing underlying dentine favoring the tooth sensitivity and the dental

Enamel hypoplasia

White colored lesions

Symmetrical or isolated

grooves

lesions

incisors

upper incisor

primary teeth)

are smooth

Partial or total absence of enamel

Deep fissures, horizontal or vertical

Edges with adjacent normal enamel

Fig. 1. C – Symmetrical opacities in

Fig. 1. D – Isolated opacity in left

(trauma or local infection in

stainment of their affected incisor. (William et al., 2006a) In such circumstance, the esthetic complaint may also be considerable. Apart from the restorative difficulties faced by clinicians, children with MIH have dental fear and anxiety and these behaviour problems can be related to pain experienced by the patients during multiple treatment appointments, as many of them were either inadequately anesthetized or even had treatment without local analgesia (Jalevik & Klingberg, 2002). It has been shown that children with MIH receive much more dental treatment that unaffected children. (Jalevik & Klingberg, 2002, Kotsanos et al., 2005) Thus, treatment planning should also consider the long-term prognosis of teeth suffering from this condition.

Children during the period of eruption of their first permanent molars and/or incisors should be monitored very carefully in order to obtain an early diagnosis and immediate treatment for MIH. Considering all aspects mentioned above, MIH is one of the biggest challenges to great challenger of great clinical interest for dental practice because MIH has a great impact on the oral health as consequently, on the quality of life of children and adolescents. Thus, the objective of this chapter is to describe some epidemiological, morphological and treatment management considerations about MIH.
