永久歯の先天欠如例における下顎骨骨塩量と骨年齢に関する研究

Using photodensitometry for 47 patients who had congenitally missing permanent teeth, excluding for third molars, bone mineral content (BMC), determined via dental radiographs, was compared with a control group of 43 patients who have all their teeth. In addition, bone age was determined by hand-wrist radiographs using the TW 2 method, and the differences of skeletal maturation between both groups were evaluated. The results are as follows : 1. The average BMC was significantly lower in the group missing teeth than in the control group both for young males (aged 7-15 years old) and young females (aged 6-15 years old). 2. The BMC in the group of people missing more than three teeth was significantly lower than those in the groups of people missing one or two teeth. 3. Regarding the average BMC by the location of missing teeth : The maxillo-mandibular group had the lowest BMC, followed by the second lowest mandible group and finally the maxillary group. By type of missing teeth : The molar, which contained at least one molar and anterior-premolar teeth group, had the lowest BMC. Second lowest was the group missing premolar followed by the group missing anterior. 4. In the groups with missing teeth, bone age was lower by 0.97 years in young males compared to 1.18 years in young females. These results show delayed skeletal maturation. In conclusion, this study clearly indicates that compared to the control group BMC is lower, and skeletal maturity has a tendency to be delayed in children with missing teeth. These results can assist planning of orthodontic treatment to patients with congenitally missing teeth

Characterization of PAX9 variant P20L identified in a Japanese family with tooth agenesis.

Transcription factors PAX9 and MSX1 play crucial roles in the development of permanent teeth at the bud stage, and their loss-of-function variants have been associated with congenital tooth agenesis. We sequenced the coding regions of the PAX9 and MSX1 genes from nine patients with non-syndromic tooth agenesis, and identified a missense mutation, P20L, of PAX9 in a single familial case involving three patients in two generations. Identical mutation was previously reported by other authors, but has not been characterized in detail. The mutation was located in a highly conserved N-terminal subdomain of the paired domain and co-segregated as a heterozygote with tooth agenesis. The patients showed defects primarily in the first and second molars, which is typical for cases attributable to PAX9 mutation. Luciferase reporter assay using the 2.3-kb promoter region of BMP4 and electrophoretic mobility shift assay using the CD19-2(A-ins) sequence revealed that P20L substitution eliminated most of the transactivation activity and specific DNA binding activity of PAX9 under the experimental conditions we employed, while some residual activity of the mutant was evident in the former assay. The hypomorphic nature of the variant may explain the relatively mild phenotype in this case, as compared with other PAX9 pathogenic variants such as R26W

Luciferase reporter assay using the <i>BMP4</i> promoter region as a cis element.

<p>Activity of firefly luciferase expressed from the reporter vector was normalized with <i>Renilla</i> luciferase, and shown as arbitrary units (mean ± SEM). Experiments were repeated three times with independent transfections, and for each experiment luciferase activity was measured in triplicate. Protein samples were prepared from aliquots of transfected cells, and ectopic PAX9 expression was verified by immunoblotting. An alleviating effect of P20L on transactivation was supported statistically, while that of A240P was not, as shown above the graph.</p

Pedigree with tooth genesis involving three patients.

<p>(A) Proband (patient ID 9 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186260#pone.0186260.t001" target="_blank">Table 1</a>), her father (ID 7) and brother (ID 10) are affected (indicated with filled symbols), while her mother is unaffected (indicated with an open symbol). The inheritance pattern is consistent with autosomal dominance. The three affected members invariably show C/T heterozygosity at the second position of the Pro²⁰ codon, while the unaffected member shows C/C homozygosity. (B) Radiogram of the proband (patient ID 9 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186260#pone.0186260.t001" target="_blank">Table 1</a>). Missing teeth other than 3rd molars are indicated with asterisks.</p

Electrophoretic mobility shift assay of PAX9^WT and PAX9^P20L.

<p>Nuclear extract was prepared at 48 h after transfection with PAX9-Myc-expressing (WT or P20L) or 1st ATG-deleted plasmids (Null), and analyzed using the CD19-2(A-ins) probe. Ectopic expression of PAX9-Myc and integrity of nuclear extract were confirmed with immunoblotting (bottom). Excessive amount of the non-biotinylated DNA eliminated the mobility shift signals in PAX9^WT, whereas addition of anti-Myc antibody resulted in a super-shift, confirming the specificity of the bipartite interaction. No detectable degree of signal shift was observed in PAX9^P20L. No NE, no nuclear extract added; L probe, biotin-labelled probe; NL probe, non-labelled probe.</p

Position of the identified PAX9 mutation.

<p>(A) Locations of P20L and previously reported missense variants are shown with arrows above and below the PAX9 diagram, respectively [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186260#pone.0186260.ref012" target="_blank">12</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186260#pone.0186260.ref025" target="_blank">25</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186260#pone.0186260.ref031" target="_blank">31</a>]. Reported pathogenic variants with nonsense mutations or frameshifts are omitted. NSD, N-terminal subdomain of the paired domain; CSD, C-terminal subdomain of the paired domain. (B) Modeled pair-domain structure of the wild-type (blue and red with green backbone) and P20L (yellow) PAX9. P20L mutation results in Van del Waals clashes with the carbonyl oxygen of Leu²¹ (red disc) and the side chain of Pro⁶⁸ (brown disc). This results in a slight displacement of Pro⁶⁸. DNA is shown in pink with a gray surface.</p

歯胚位置異常の上顎犬歯を移転排列した骨格性反対咬合症例

初診時年齢9歳0か月の女児で,埋伏した上顎右側中切歯と位置異常の犬歯を伴った骨格性III級の一症例を報告する.埋伏した中切歯は逆生で歯根が屈曲していた.中切歯を抜去後,犬歯は抜去した中切歯の位置に自然に移動したが萌出は認められなかったため,上顎歯列にNanceのホールディングアーチを装着し犬歯の牽引を開始した.上顎犬歯はマルチブラケット装置を使用して十分なスペースを獲得した後,中切歯の位置に排列した.骨格性III級に対しては,上顎前方牽引装置を適用し顎間関係の改善を行った.マルチブラケットによる治療期間は,犬歯のスペース獲得のために11か月,牽引のために1年4か月,下顎を含めた全顎的な歯の排列のために2年11か月を要した.中切歯部に排列された犬歯は機能的にも問題はなく,形態修正を施すことにより審美的回復を得ることができた.This case report describes the orthodontic treatment of a 9-year-old girl with skeletal Cl III malocclusion, an impacted maxillary right central incisor, and ipsilaterally displaced canine. The impacted maxillary central incisor was inverted and the root was crooked. After the maxillary right central incisor was extracted, the ipsilateral canine spontaneously moved toward the extracted incisor position. However, eruption did not occur, so we began the traction of the maxillary right canine after setting Nance\u27s holding arch appliance for reinforced anchorage. The maxillary right canine was aligned the position of a central incisor after creating sufficient space using a multibracket appliance. For the skeletal problems, a maxillary protractive appliance was applied to improve the intermaxillary relationship. The treatment period employing the multibracket appliance was: 11 months for acquiring the canine space, one year and four months for traction of the canine, and two years and 11 months for full alignment of the maxillary and mandibular teeth, with a total of 5 years and 2 months. As a result, satisfactory dental aesthetics were achieved by adjusting the shape of the crown of the canine as well as realizing stable occlusion with a sufficient function