Tooth eruption is a process in which the crown moves toward the occlusal surface, involving the interaction of multiple factors (dental follicle, osteoclast and related signals, etc.), and the abnormality of one factor may cause the abnormal eruption of teeth In clinical practice, PFE is defined as partial tooth eruption disorder. There are no clear local or systemic factors in clinical practice, but the abnormal mechanism of tooth eruption is called primary tooth eruption disorder
PFE is a rare disease, which is caused by the abnormal eruption mechanism of teeth. The clinical examination of
has no definite etiology, often involves one or several quadrants, and the orthodontic traction effect is poor. As the etiology of this disease is unknown, the clinical diagnosis is more difficult, especially with mechanical failure of teeth
MFE is caused by adjacent teeth or supernumerary teeth, alveolar bone adhesion, hyperplasia tissue and other mechanical reasons. Most of them are single tooth involved. The orthodontic traction effect is good. This paper reports a case of PFE treated in our hospital, and reviews the literature
1. Case report
A 10-year-old boy presented with eruption of lower anterior teeth and failed to replace the primary teeth one year ago. After extraction of retained deciduous teeth in the local hospital, the remaining teeth did not sprout and affected food intake.
had no other abnormal physical development.
past history: full-term, spontaneous labor, denied the history of systemic and systemic diseases
family history: parents, younger sister, no obvious abnormality in the replacement of primary and permanent teeth, no abnormality in physical development, the elder uncle had tooth eruption disorder, the specific situation is unknown.
denies the history of systemic and genetic diseases
Special examination found 51, 52, 53, 54, 55, 61, 62, 63, 64, 31, 72, 73, 74, 75, 41, 82, 83, 84 normal; 65, 85, 16, 26, 36, 46 did not erupt (Fig. 1).
showed 65, 85, 16, 26, 36, 46 impacted teeth; 11,12,13,14,15,17,21,22,23,24,25,27,32,33,34,35,37,42,43,44,45,47 teeth germ, 85,45 overlapping images (Fig. 2).
clinical diagnosis: primary tooth eruption disorder (PFE).
Fig. 1 oral radiography at initial diagnosis
Fig. 2 surface fault slice
1) tooth eruption mechanism
The process of tooth eruption needs the precise coordination of dental follicle, tooth germ cells, osteoclasts, osteoblasts and a series of related molecular signals. If a certain factor fails, the process of tooth eruption may be abnormal Tooth eruption channel is mainly formed by the formation and development of tooth germ to promote alveolar bone resorption. Influenced by various cytokines synthesized and secreted by macrophages, osteoclasts play a role in promoting physiological absorption of deciduous teeth roots, thus causing the eruption of inherited permanent teeth Some scholars have found that macrophages can secrete parathyroid hormone related protein (PTHrP), activate the corresponding receptors to promote bone resorption and tooth eruption in mice; however, knockout of PTHrP gene in mice will cause tooth eruption disorder, indicating that PTHrP can regulate tooth eruption
Some scholars have found that cytokines can also affect tooth eruption. Cytokines can make osteoclast volume larger. When osteoclast volume increases, bone absorption function is enhanced. After administration of mouse osteoclast inhibitor, tooth eruption is delayed In terms of tooth eruption dynamics, it has been confirmed that periodontal fiber remodeling and periodontal membrane hemodynamics provide the impetus for tooth eruption. The mature remodeling of periodontal ligament fiber leads to tooth eruption after gingival rupture.
many unexplained tooth eruption disorders are mostly related to periodontal ligament abnormalities
2) clinical manifestations of PFE
In 1981, profit believed that this unexplained tooth eruption disorder should be the mechanism of tooth eruption itself, which is different from the previous theory of root and alveolar bone adhesion, and named this disease “primary failure of erution (PFE)”; The clinical manifestations can be summarized as follows: 1) posterior teeth often involve permanent teeth, the first permanent molar is the most common, which can be manifested as severe posterior teeth opening and closing, permanent premolars and permanent canines can also be involved, and permanent incisors are rarely involved, occasionally in deciduous dentition, and the eruption degree is irregular.
② the affected teeth may not erupt completely or partially ③ (4) can occur simultaneously on one side or both sides, but it is usually asymmetric. Most of the cases are unilateral without obvious systemic diseases.
(5) PFE has family aggregation, and the proportion of cases with family history is 26% – 45% Through the pedigree analysis of PFE families, it was found that PFE was autosomal dominant inheritance, with complete penetrance rate, but different expression degrees. For sporadic cases, the incomplete collection of family history and gene mutation can be used to explain
According to the onset time of PFE, PFE can be divided into 2 types: according to the time of eruption, PFE can be divided into type 2. Type
type 1: at a certain time point, the eruption of the affected teeth stops at the same time, and the opening and closing situation becomes more and more serious; Type 2: the time of eruption and opening and closing of different teeth may be different
3) pathogenesis of PFE
The research on the mechanism of tooth eruption has never stopped, and there are many theories. So far, no conclusion has been reached, and the pathogenesis of PFE has not been fully understood. Early studies such as
have found that PFE may be related to the abnormal blood supply of periodontal ligament In recent years, it has been found that the pathogenic gene of PFE may be PTH1R, which is associated with parathyroid hormone related protein (PTHrP or PTHLH) and parathyroid hormone (PTHLH) If PTH1R gene mutation occurs, it may break the balance between osteogenesis and osteoclast and cause PFE
The study of Frazier Bowers and others found that all patients with PFE carried the mutated PTH1R gene, which further confirmed the relationship between PFE and PTH1R gene At the same time, we also found that patients with PTH1R gene mutation not only suffered from PFE, but also had osteoarthritis, which suggested that there was a certain relationship between PFE and osteoarthritis. Up to now, the relationship between PFE and PTH1R gene and its mechanism still need to be explored
Diagnosis and differential diagnosis of PFE
The diagnostic criteria defined by
stellzig eisenhauer et al. Were as follows: (1) no eruption during normal eruption, partial or complete eruption of single or multiple teeth, and no sign of attachment or other eruption disorders; ② The results showed that there was an eruption path formed by normal bone resorption in the crown of the affected teeth; 3) all the teeth in the distal part of the affected teeth were involved; 4) the posterior teeth were occluded; ⑤ It is easy to confuse MFE with
and PFE. MFE only affects a single tooth, and there is no normal bone absorption channel in the crown. The orthodontic traction effect is better because of the mechanical reasons such as adjacent teeth or supernumerary teeth, alveolar bone adhesion, hyperplasia tissue and other mechanical reasons
The discovery of PTH1R gene of
PFE provides a new idea for the differential diagnosis of PFE. However, there is still a lack of a gold standard for the diagnosis of PFE, which needs to be further explored
5) therapeutic principle and prognosis of PFE
For the patients with a 603 2.2 crowns, which can not be restored by pfa2.2 crowns, it can be used to repair the teeth which are difficult to be restored If the implant conditions are not satisfied, only removable partial denture can be considered.
has reported the use of distraction osteogenesis in the treatment of patients with posterior teeth, which can also provide a new treatment idea for PFE patients
Objective: To investigate the clinical effect of primary tooth eruption disorder (PDD) on primary tooth eruption [J]. Journal of Modern Stomatology, 2019 (02): 123-125