Primary failure of eruption and other eruption disorders—Considerations for management by the orthodontist and oral surgeon

Primary failure of tooth eruption: Etiology and management

Primary failure of eruption (PFE) is a rare disorder defined as incomplete tooth eruption despite the presence of a clear eruption pathway. PFE is known to be caused by rare variants in the parathyroid hormone 1 receptor gene (PTH1R). Although several PTH1R variants have been reported, the etiology of PFE remains unclear. However, important studies that help elucidate the pathology of PFE have recently been published. The purpose of this review is to summarize current treatment options, clinical symptoms or phenotypes for diagnosis, genetic information including solid evidence in mouse disease models and disease-specific induced pluripotent stem cells, thus approaching the etiology of PFE from the perspective of the latest research.

Review and case report of the treatment in a young girl with primary failure of eruption

Any localized non‐eruption of teeth can be attributed to myriad of factors. A failure of a permanent tooth to erupt or cessation of initial eruption with no obvious local/systemic causative factor is said to be primary failure of eruption (PFE). The etio‐pathogenesis of PFE is due to the mutation of PTH1R gene. Clinical features such as infra‐occluded teeth, posterior open bite, lack of any cause or habit are usually attributed to diagnosing the condition, and a confirmatory diagnosis is done by the gene analysis of PTH1R gene. Treatment of such a condition is tricky as any application of orthodontic traction to teeth affected by PFE will not be successful and may cause ankylosis. This correspondence reviews and demonstrates the treatment of a case of PFE to restore function and esthetics to the best possible outcome.

Challenges, standards and prospects in the therapy of orthodontic traction of impacted maxillary canine: A surgical phase

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Validating clinical characteristic of primary failure of eruption (PFE) associated with PTH1R variants

BACKGROUND

Primary failure of eruption (PFE) is a hereditary condition, and linkage with variants in the PTH1R gene has been demonstrated in many cases. The clinical severity and expression of PFE is variable, and the genotype-phenotype correlation remains elusive. Further, the similarity between some eruption disorders that are not associated with PTH1R alterations is striking. To better understand the genotype-phenotype correlation, we examined the relationship between the eruption phenotype and PTH1R genotype in 44 patients with suspected PFE and 27 unaffected relatives. Sanger sequencing was employed to analyze carefully selected PFE patients. Potential pathogenicity of variants was evaluated against multiple genetic databases for function prediction and frequency information.

RESULTS

Mutational analysis of the PTH1R coding sequence revealed 14 different variants in 38 individuals (30 patients and 8 first-degree relatives), 9 exonic and 5 intronic. Their pathogenicity has been reported and compared with the number and severity of clinical signs. In 72.7% of patients with pathogenic variants, five clinical and radiographic criteria have been found: involvement of posterior teeth, involvement of the distal teeth to the most mesial affected, supracrestal presentation, altered vertical growth of the alveolar process and posterior open-bite. In cases with mixed dentition (3), the deciduous molars of the affected quadrant were infraoccluded.

DISCUSSION

The probability of an affected patient having a PTH1R variant is greater when five specific clinical characteristics are present. The likelihood of an eruption defect in the absence of specific clinical characteristics is rarely associated with a PTH1R mutation.

CONCLUSIONS

We report here that systematic clinical and radiographic observation using a diagnostic rubric is highly valuable in confirming PFE and offers a reliable alternative for accurate diagnosis.

[Primary failure of eruption: a French prospective survey among the orthodontists from the Grand Est and Bourgogne-Franche-Comté regions]

INTRODUCTION

 Primary failure of eruption (PFE) can be defined as the partial or complete failure of eruption of at least one posterior tooth, without any mechanical obstacle; isolated and syndromic forms exist. PFE results from an abnormal dental eruption process that can affect temporary teeth and / or permanent teeth. Molars are the main affected teeth, inducing posterior infraclusions. Orthodontists are the specialists most often concerned by this rare pathology. Unsuccessful orthodontic-surgical traction therapies are commonly reported.

MATERIALS AND METHODS

 The aim of our study using a prospective survey was to evaluate the level of knowledge reported by the orthodontists and the therapeutic difficulties they reported. An anonymous questionnaire was submitted to practitioners practicing in north-eastern France (Grand Est and Bourgogne-Franche-Comté regions).

RESULTS

 The participation rate was 33.5%. In France, until 2015, specialization in orthodontics was obtained thanks to a local qualification, the Certificat d'Etudes Cliniques Spéciales - Mention Orthodontie (CECSMO), which has now been replaced by specialization following a national ranking competition. Most respondents obtained their qualification between 1980 and 2009 (80%), via the CECSMO (87%). Eighty-six per cent were aware of PFE but only 20% of them knew that PTHR1 (Parathyroid Hormone Receptor 1) gene could be involved in this pathology. The wide range of proposed therapies and the variable satisfaction rates highlight the difficulties encountered by practitioners.

DISCUSSION

 Phenotypic variability complicates the diagnosis and makes any therapeutic systematization uncertain.

CONCLUSION

 New clinical research projects, particularly in the field of molecular diagnosis, may improve understanding of genotype-phenotype correlations, and may potentially pilot therapeutic management.

Heredity, Genetics and Orthodontics - How Much Has This Research Really Helped?

Uncovering the genetic factors that correlate with a clinical deviation of previously unknown etiology helps to diminish the unknown variation influencing the phenotype. Clinical studies, particularly those that consider the effects of an appliance or treatment regimen on growth, need to be a part of these types of genetic investigations in the future. While the day-to-day utilization of "testing" for genetic factors is not ready for practice yet, genetic testing for monogenic traits such as Primary Failure of Eruption (PFE) and Class III malocclusion is showing more promise as knowledge and technology advances. Although the heterogeneous complexity of such things as facial and dental development, the physiology of tooth movement, and the occurrence of External Apical Root Resorption (EARR) make their precise prediction untenable, investigations into the genetic factors that influence different phenotypes, and how these factors may relate to or impact environmental factors (including orthodontic treatment) are becoming better understood. The most important "genetic test" the practitioner can do today is to gather the patient's individual and family history. This would greatly benefit the patient, and augment the usefulness of these families in future clinical research in which clinical findings, environmental, and genetic factors can be studied.