Multiple Cervical Root Resorption Involving 22 Teeth: A Case with Potential Genetic Predisposition.

A rare case of extensive multiple idiopathic cervical root resorption with potential genetic predisposition was presented. A heathy 19-year-old Chinese male with no contributory medical or family/social history complained of pain during mastication that lasted for several months. Oral examination identified 7 missing teeth and external cervical root resorption involving 9 teeth. Comparison of orthopantomograms taken in May 2021 and February 2022 identified that cervical root resorption occurred in 22 teeth. Resorption commenced at the cementoenamel junction and progressed rapidly over the 9-month period. Laboratory test results were within normal limits. Trio-based whole-exome sequencing showed a missense mutation c.5630 C > T in the filamin A (FLNA) gene at chromosome X of the subject. This is suggestive of the possibility of sex-linked recessive inheritance. This is the first study to report FLNA mutation in human subjects with cervical root resorption involving multiple teeth.

Transcriptomic profiling of feline teeth highlights the role of matrix metalloproteinase 9 (MMP9) in tooth resorption.

Tooth resorption (TR) in domestic cats is a common and painful disease characterised by the loss of mineralised tissues from the tooth. Due to its progressive nature and unclear aetiology the only treatment currently available is to extract affected teeth. To gain insight into TR pathogenesis, we characterised the transcriptomic changes involved in feline TR by sequencing RNA extracted from 14 teeth (7 with and 7 without signs of resorption) collected from 11 cats. A paired comparison of teeth from the same cat with and without signs of resorption identified 1,732 differentially expressed genes, many of which were characteristic of osteoclast activity and differentiation, in particular matrix metalloproteinase 9 (MMP9). MMP9 expression was confirmed by qPCR and immunocytochemistry of odontoclasts located in TR lesions. A hydroxamate-based MMP9 inhibitor reduced both osteoclast formation and resorption activity while siRNA targeting MMP9 also inhibited osteoclast differentiation although had little effect on resorption activity. Overall, these results suggest that increased MMP9 expression is involved in the progress of TR pathogenesis and that MMP9 may be a potential therapeutic target in feline TR.

Polymorphisms of genes encoding P2X7R, IL-1B, OPG and RANK in orthodontic-induced apical root resorption.

OBJECTIVE: Orthodontic-induced external apical root resorption (EARR) is a complex phenotype determined by poorly defined mechanical and patient intrinsic factors. The aim of this work was to construct a multifactorial integrative model, including clinical and genetic susceptibility factors, to analyze the risk of developing this common orthodontic complication. MATERIALS AND METHODS: This retrospective study included 195 orthodontic patients. Using a multiple-linear regression model, where the dependent variable was the maximum% of root resorption (%EARRmax) for each patient, we assessed the contribution of nine clinical variables and four polymorphisms of genes involved in bone and tooth root remodeling (rs1718119 from P2RX7, rs1143634 from IL1B, rs3102735 from TNFRSF11B, encoding OPG, and rs1805034 from TNFRSF11A, encoding RANK). RESULTS: Clinical and genetic variables explained 30% of%EARRmax variability. The variables with the most significant unique contribution to the model were: gender (P < 0.05), treatment duration (P < 0.001), premolar extractions (P < 0.01), Hyrax appliance (P < 0.001) and GG genotype of rs1718119 from P2RX7 gene (P < 0.01). Age, overjet, tongue thrust, skeletal class II and the other polymorphisms made minor contributions. CONCLUSION: This study highlights the P2RX7 gene as a possible factor of susceptibility to EARR. A more extensive genetic profile may improve this model.

A novel mutation in the AMELX gene and multiple crown resorptions.

Amelogenesis imperfecta (AI) is a heterogeneous group of genetic disorders with regard to genetic aetiology and clinical phenotype and affects tooth enamel with no other non-oral syndromic conditions. X-linked AI is caused by mutations in the amelogenin (AMELX) gene, the only AI candidate gene located on the X chromosome. To date, 15 mutations in the AMELX gene have been found to cause AI. We identified a proband with generalized hypoplastic enamel and unusual multiple crown resorption in premolars and molars. Pedigree analysis suggested an X-linked hereditary pattern. We performed mutational analysis for the AMELX gene based on the candidate gene approach. Sequencing analysis revealed a novel mutation in exon 6 (g.4090delC, c.517delC, p.Pro173LeufsX16). This frameshift mutation produces a premature stop codon within exon 6 and is predicted to replace 33 amino acids at the C-terminus with 15 novel amino acids if the mutant mRNA escapes the nonsense-mediated decay system. Although crown resorptions occur frequently in patients with the hypoplastic type of A1, an association with the AMELX mutation has not been previously reported. We believe that these findings will broaden our understanding of the clinical phenotype and pathogenesis of X-linked AI.

Amelogenesis imperfecta due to a mutation of the enamelin gene: clinical case with genotype-phenotype correlations.

The major protein components of the enamel matrix include the most abundant amelogenin proteins as well as less plentiful proteins such as enamelin and ameloblastin. The enamel defect in amelogenesis imperfecta (Al) generally results in enamel that is too thin (hypoplastic) or too soft (hypocalcification or hypomaturation). Previous reports indicate that mutations in the human enamelin gene (ENAM) cause hypoplastic Al through autosomal-dominant inheritance patterns and patients may also exhibit an anterior open bite. Although crown resorption of unerupted teeth occurs more frequently in Al patients, this finding has not been previously associated with known ENAM mutations. The purpose of this article was to report the genotype-phenotype correlations for a 9-year, 11-month-old boy with a homozygous ENAM mutation (c.1258_1259insAG).

Inflammatory cytokines and the nuclear vitamin D receptor are implicated in the pathophysiology of dental resorptive lesions in cats.

Dental resorptive lesions (RL) are a common oral disease in cats (Felis catus) associated with pain and tooth destruction. The aetiology of RL in cats is unknown, but inflammation is often seen in conjunction with RL. Vitamin D involvement has been suggested because 1,25-dihydroxyvitamin D (1,25(OH)(2)D) stimulates osteoclastogenesis, through up-regulation of the nuclear vitamin D receptor (nVDR). The aim of this study is to determine the involvement of inflammatory cytokines and the possible role of vitamin D in the pathophysiology of RL using quantitative PCR. We measured the mRNA expression of cytokines with stimulatory (IL-1beta, IL-6, and TNF-alpha) and inhibitory effects (IL-10 and IFN-gamma) on osteoclastogenesis, and the mRNA expression of the receptor activator of nuclear factor-kappaB ligand (RANKL), osteoprotegerin (OPG), and nVDR in RL samples. We found increased expression of mRNA levels for inflammatory cytokines and nVDR, but not for RANKL and OPG, in tissue from RL-affected cats compared with tissue from radiological confirmed healthy controls. The mRNA levels of nVDR were positively correlated with mRNA levels of pro-inflammatory (IL-1beta, IL-6, TNF-alpha, and IFN-gamma), anti-inflammatory (IL-10), pro-resorptive (IL-1beta, IL-6, and TNF-alpha), and anti-resorptive (IFN-gamma and IL-10) cytokines in the course of resorptive lesions. These data are consistent with our view that both inflammation and an overexpression of the nVDR are likely to be involved in RL in cats.

Expression of MT1-MMP during deciduous tooth resorption in odontoclasts.

Membrane type 1-matrix metalloproteinase (MT1-MMP) is a membrane-bound matrix metalloproteinase capable of mediating pericellular proteolysis of extracellular matrix components. In osteoclasts, the localization of MT1-MMP has been reported at the tips of specialized membrane protrusions (podosomes and lamellipodia) so that osteoclasts might use MT1-MMP to perform focal proteolysis and move through the extracellular matrix to the bone surface. The objectives of this study were to investigate an association of MT1-MMP in physiological root resorption of the deciduous tooth by reverse transcriptase-polymerase chain reaction (RT-PCR) and Northern blot analysis, and to identify MT1-MMP-producing cell during deciduous tooth resorption by in situ hybridization and immunohistochemistry. RT-PCR and Northern blot analysis revealed the exclusively high expression of MT1-MMP mRNA in bovine root-resorbing tissue, which lies between the root of the deciduous tooth and its permanent successor. Expression of MT1-MMP mRNA was seen in odontoclasts aligning in the surface layer of the root-resorbing tissue at sites of root resorption. Furthermore, immmunohistochemistry also confirmed the localization of MT1-MMP protein to the odontoclasts. The present identification of MT1-MMP in odontoclasts during deciduous tooth resorption might be relevant to the migration activity that these cells have to gain access to the root surface.

Hyper-IgE syndrome with recurrent infections--an autosomal dominant multisystem disorder.

BACKGROUND: The hyper-IgE syndrome with recurrent infections is a rare immunodeficiency characterized by recurrent skin and pulmonary abscesses and extremely elevated levels of IgE in serum. Associated facial and skeletal features have been recognized, but their frequency is unknown, and the genetic basis of the hyper-IgE syndrome is poorly understood. METHODS: We studied 30 patients with the hyper-IgE syndrome and 70 of their relatives. We took histories, reviewed records, performed physical and dental examinations, took anthropometric measurements, and conducted laboratory studies. RESULTS: Nonimmunologic features of the hyper-IgE syndrome were present in all patients older than eight years. Seventy-two percent had the previously unrecognized feature of failure or delay of shedding of the primary teeth owing to lack of root resorption. Common findings among patients were recurrent fractures (in 57 percent of patients), hyperextensible joints (in 68 percent), and scoliosis (in 76 percent of patients 16 years of age or older). The classic triad of abscesses, pneumonia, and an elevated IgE level was identified in 77 percent of all patients and in 85 percent of those older than eight. In 6 of 23 adults (26 percent), IgE levels declined over time and came closer to or fell within the normal range. Autosomal dominant transmission of the hyper-IgE syndrome was found, but with variable expressivity. Of the 27 relatives at risk for inheriting the hyper-IgE syndrome, 10 were fully affected, 11 were unaffected, and 6 had combinations of mild immunologic, dental, and skeletal features of the hyper-IgE syndrome. CONCLUSIONS: The hyper-IgE syndrome is a multisystem disorder that affects the dentition, the skeleton, connective tissue, and the immune system. It is inherited as a single-locus autosomal dominant trait with variable expressivity.

Familial expansile osteolysis.

Familial expansile osteolysis (FEO) is a unique bone dysplasia, which has, over five generations, affected 42 members of a Northern Ireland family. The disease follows a classic autosomal dominant pattern of inheritance. The condition is distinct enough in its clinical features and natural history to be recognized as a new and unique disease. There are both general and focal skeletal changes, the latter having a predominantly peripheral distribution and an onset from the second decade. Progressive osteoclastic resorption accompanied by medullary expansion leads to severe and painful disabling deformities with a tendency to pathologic fracture. Most affected members of the family have an associated early-onset deafness and loss of dentition as a result of unique middle ear and dental abnormalities. The serum alkaline phosphatase and urinary hydroxyproline are elevated to a variable degree, whereas other biochemical indices are normal. The response of the disease to a therapeutic trial using parenteral dichloro-methylene-diphosphonate (dichloro-MDP) produced an initial rapid biochemical response, which was not sustained.