Enamel Hypomineralization Viewed From the Pattern of Progressive Mineralization of Human and Monkey Developing Enamel

Abstract

Microradiograms and their computer-aided image analysis of ground sections of the developing enamel of human permanent third molars and monkey permanent teeth (Macaca fuscata) indicate that the mode of progressive mineralization of enamel is completely different between the matrix formation and maturation stages. During the former stage, the enamel matrix is slightly mineralized. During the latter stage, which takes a much longer period than the previous stage, the increase in the secondary mineralization takes place first slightly, from the surface toward the inner layer, and then heavily, from the inner layer toward the surface. The narrow outer layer mineralizes very slowly during the middle and late stages of maturation, but finally achieves the highest mineralization of the entire enamel layer. The very narrow innermost layer mineralizes slowly without expanding its width. The former three processes seem to be under the direct control of the ameloblasts. Hypoplastic areas which appear during the matrix formation stages are not necessarily accompanied by hypomineralization. Dysfunction of the cells immediately after the completion of matrix formation appears to cause hypomineralization throughout the entire width of matrix except for the innermost layer. Disorders of the cells occurring during the middle and/or the late stage of maturation--due to chronic metabolic disturbances, such as fluorosis--induced hypomineralization localized mainly at the outer layer. The hypomineralized enamel is not necessarily accompanied by hypoplasia. The process of enamel mineralization is not necessarily fully synchronized with that of tooth eruption. Therefore, the narrow outer layer, especially in the fissure and cervical regions, is sometimes hypomineralized even after the teeth have erupted normally.

Molar Incisor Hypomineralization: Morphological, Aetiological, Epidemiological and Clinical Considerations

“…On the other hand, disturbances during the transitional and/or maturation stage of amelogenesis result in pathologically soft (hypomaturated, hypomineralised) enamel of normal thicknesses. (Suga, 1989) According to REID AND DEAN, 2006 (Reid & Dean, 2006), enamel formation as a whole takes approximately one thousand days. Two thirds of this time is devoted to the maturation stage of amelogenesis.…”

Passports from the past: Investigating human dispersals using strontium isotope analysis of tooth enamel

“…trajectory as matrix deposition, on one front only, or at a regular pace (Boyde 1989, Suga 1982, Suga 1989.…”

Molar-incisor hypomineralization: Therapeutic challenge to paediatric dentistry practice

“…Zvaničnih podataka o rasprostranjenosti MIH za našu zemlju nema, mada se procenjuje da iznosi oko 19,5% 7,8 . Osnovni patogenetski mehanizam MIH je poremećaj resorptivnog potencijala ameloblasta i inhibicija proteolitičkih enzima usled čega dolazi do zadržavanja gleđnih proteina, ometanja rasta kristala i maturacije gleđi [9][10][11][12][13][14] . Rezultat toga je promena u mineralnom sastavu gleđi, povećanje poroznosti, smanjenje tvrdoće i modula elastičnosti hipomineralizovane gleđi u odnosu na gleđ koja nije zahvaćena promenama, što se klinički manifestuje promenama u boji gleđi, koje variraju od beličastih do promena braon prebojenosti [15][16][17] .…”

“…There are no official data on the prevalence of MIH for our country, but it is estimated to be approximately 19.5% 7,8 . The main pathogenic mechanism of MIH is the disorder of adsorbent potential of ameloblasts and inhibition of proteolytic enzymes, causing retention of enamel proteins, interfering with crystal growth and maturation of enamel [9][10][11][12][13][14] . This results in the transformation of mineral composition of the enamel, increase in porosity, decrease in hardness and elasticity module of hypomineralized enamel compared to the nonaffected enamel, which is clinically manifested by changes in enamel colour that varies from whitish to changes of brown discoloration [15][16][17] .…”