@article{oai:niigata-u.repo.nii.ac.jp:00002973,
 author = {高木, 純一郎 and 佐野, 富子 and 田口, 洋 and 三富, 智恵},
 issue = {3},
 journal = {小児歯科学雑誌, 小児歯科学雑誌},
 month = {Jun},
 note = {下顎第二小臼歯は様々な局所的要因により萌出が障害されるが，本研究では特発的な歯胚の方向異常により下顎第二小臼歯の萌出が障害された症例について検討を行い，臨床的対応法についてフローチャートを考案した。調査対象は1979年から2008年までに新潟大学医歯学総合病院小児歯科診療室で処置した，歯胚の方向異常に起因する下顎第二小臼歯萌出障害の11症例15歯で，診断時年齢は8歳Oか月～13歳11か月，片側性7例，両側性4例であった。15歯中14歯が遠心に傾斜しており，歯胚形成度が低いものほど遠心傾斜度が大きい傾向にあった(R>0.70)。また，片側怪と両側怪の2群に分けて傾斜度を比較すると，遠心傾斜度は片側性で有意に大きい値を示した(P<0.01)。診断後に全症例で先行乳歯を抜去していたが，傾斜度の大きい場合には，その後歯胚形成がすすんでも傾斜度はわずかに改善するのみで，初期歯根形成期から歯根長1/4形成期頃にかけて骨開窓や牽引，誘導等の複雑な対応を必要とする場合が多かった。したがって，形成遅延が顕著に認められる場合には，早期に先行乳歯を抜去すると保隙期間が長くなるため，下顎第二小臼歯の歯根形成開始を待って対応した方が良いと考えられた。, The aims of this retrospective study were to examine the eruption disturbances of the mandibular second premolar caused by abnormal inclination of the tooth germs and to discuss and demonstrate the recommended treatment for these cases. The subjects comprised of 11 patients (eight girls and three boys) in whom the eruption of 15 mandibular second premolars was disturbed by aberrant direction of the tooth germs. The patients were treated at the Pediatric Dental Clinic of Niigata University Medical and Dental Hospital during 28 years from September 1979 to January 2008. The ages of the patients at the time of diagnosis ranged from 8 years exactly to 13 years and 11 months. The eruption disturbance occurred unilaterally in seven cases (five on the right side and two on the left) and bilaterally in four cases. In 14 of 15 affected premolars, the tooth germs exhibited distal inclinations. A strong correlation between the degree of distal inclination and the delay in formation of the tooth germ was observed (correlation coefficient: R>0.70); the more significant the delay in formation of the tooth germ, the higher the degree of distal inclination. In unilateral cases, the tilting degree was very high, and the formation of the tooth germ was significantly delayed. In bilateral cases, however, both the tilting degree and delay in formation were not severe, and were almost the same on both sides. A comparison between the unilateral group and the bilateral one revealed that the degree of distal inclination was considerably higher in the unilateral group (P<0.01). In the cases of 14 teeth among 10 patients (all but one unilateral case, in which血e patient was very young), the primary second molars were removed soon after diagnosis. The cases that had serious tilting, however, showed only slight improvement of the aberrant tilting even after their predecessors were extracted early, and additional complex treatments such as bone fenestration or traction of the affected tooth were required at the developing stage of initiation or one-fourth of the tooth root formation. If a predecessor is extracted at an early stage of tooth germ formation, long-term space maintenance is required. It was concluded that in cases with a markedly severe distal inclination, eruption disturbance of the mandibular second premolar should be treated after the root formation of its tooth germ is initiated.},
 pages = {433--441},
 title = {歯胚の方向異常による下顎第二小臼歯萌出障害の臨床的検討},
 volume = {47},
 year = {2009}
}