Primary Failure of Eruption (PFE) - a Case Report With Differential Diagnostic Aspects

Introduction: Tooth eruption disorders are due to both local and systemic factors. Complex diseases such as Apert syndrome, Down's syndrome, cleidocranial dysostosis, ectodermal dysplasia, or Gardner's syndrome can all be affected by numerous teeth. Patients with local eruption disorders usually have their third mandibular molars and maxillary canines affected. Very rare eruption disorders occur in the first and second molars. In a third variant, non-syndromal primary breakthrough disorder ["Primary Failure of eruption" (PFE)], a primarily non-ankylosed tooth does not break through or breaks through only partially. For the normal population, the prevalence of this abnormality was reported at 0.06% with a gender distribution of 1: 2.25 (male / female). Case Report: A 19-year-old female patient was suspected of having a genetic dental breach after many years of orthodontic treatment had failed. At the age of four, she was diagnosed with hearing loss in terms of central hearing impairment, growth retardation, and hypogonadotropic hypogonadism. Brain MRI, chromosomal analysis, and SHOX deletion analysis revealed no abnormal findings. As part of human genetic counseling, the patient wanted to find out whether her symptoms could be attributed to a superordinate syndromal disease and what diagnostic possibilities exist in suspected cases of PFE that affect molars 17, 27, and 47. A chromosome examination that had already been performed revealed an inconspicuous set of female chromosomes (46, XX). At the patient's request, an array analysis was performed to examine the entire genome for small deletions and duplications that are not visible in normal chromosome analysis. There was no disease-causing deletion or duplication. However, this finding does not exclude the presence of a syndromal disease. The patient was informed that a genetic non-syndrome-related tooth eruption disorder had been reported in some patients / families. Heterozygous mutations in the PTHR1 gene on chromosome 3, which contains the information for the paratreceptor, were identified as the cause of this. At the request of the patient, an examination of this gene was carried out. The mutation c.436C> T, p.Arg146 * in the PTHR1 gene could be detected in a heterozygous state, and the diagnosis of a primary failure of eruption could thus be confirmed. Discussion: The mutation c.436C> T, p.Arg146 * in the heterozygous PTHR1 gene leads to the termination of protein synthesis and has already been described in the literature as a disease-causing factor. Early, genetically-confirmed diagnosis of non-syndromal PFE saves patients, orthodontists, and oral / maxillofacial surgeons from having to undergo frustrating therapy for years. On the part of the practitioner, knowledge of the genetic aetiology of PFE is indispensable for the differential diagnosis of breakthrough disorders. Those affected should be offered a human genetic examination. In severe cases, oral surgical options for extraction or surgical removal with subsequent implant-based rehabilitation or the occlusion adjustment of PFE-affected teeth using segment osteotomy are early decisions. This requires the affected teeth to be surgically available. Keywords: PFE, PTHR-1, tooth eruption disorder