PubMed · 6950080
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S Järvinen, P Väätäjä. 1981. Congenitally missing first permanent molars.. https://pubmed.ncbi.nlm.nih.gov/6950080/
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Absence of the maxillary lateral incisor creates an aesthetic problem which can be managed in various ways. The condition requires careful treatment planning and a consideration of the options and outcomes following either space closure or prosthetic replacement. Recent developments in restorative dentistry have warranted a re-evaluation of the approach to this clinical situation. Factors relating both to the patient and to the teeth, including the presenting malocclusion and the effect on the occlusion, are considered. This review considers the possible options: no treatment; orthodontic space closure with canine modification; space maintenance and replacement of the missing tooth with denture, bridge (adhesive and conventional), or implant.
Recently, sonography of the fetal face has gained increasing importance in prenatal diagnosis. It is not yet clear whether sonographic depiction of fetal tooth germs would have an influence on the prenatal diagnosis of ectodermal dysplasia syndromes. During routine malformation screening, horizontal sections of fetal jaws were visualized and examined for tooth germs in 124 pregnant women following sonographic 'facing'. Histological jaw sections of fetuses that had died in utero at various gestational ages were produced in order to examine the degree of correspondence between the sonographic and histological findings. At least four tooth germs were found in the jaws of all fetuses between 19 and 34 gestational weeks (n = 104). Although jaw visualization was possible between 14 and 18 gestational weeks (n = 20), the exact number and location of the tooth germs could not be determined. Assessment of tooth germs may become increasingly important, as aplasia of the tooth germs is one of the principal signs of various hereditary ectodermal diseases.
Hypodontia, congenital lack of one or a few teeth, is an autosomally inherited dominant trait. Homeobox genes MSX1 and MSX2 are expressed in presumptive dental tissues at the stage of initiation of tooth development. Recently, tooth development was shown to be inhibited in transgenic mice lacking a functional Msx1 gene. Here, we studied the relationship of the MSX1 and MSX2 genes to familial hypodontia in five Finnish families with a total of 20 affected individuals, by linkage analysis. The pairwise lod-scores regarding the intragenic microsatellites in the MSX1 and MSX2 genes at a recombination fraction of 0.0 were -3.1 and -3.0, respectively, thus excluding these genes as causative loci for hypodontia in these families.