七條 なつ子

Background: Melanotic neuroectodermal tumor of infancy (MNTI) is a very rare tumor, and case reports of orthodontic treatment for patients with MNTI may be previously unreported. This article describes the orthodontic treatment for a 7-year-old girl with MNTI in the mandible. Case: Her chief complaint was anterior crossbite. Although she had an MNTI diagnosis at the age of 8 months, it remained subclinical. Therefore, she has been regularly followed-up by computed tomography (CT) and magnetic resonance (MR) imaging without aggressive treatment. We had worried about the stimulation of MNTI on the mandible by changing her occlusal position with orthodontic treatment. Therefore, we sufficiently explained to her and her family that orthodontic treatment was at risk for worsening MNTI. However, they desired treatment that consisted of maxillary protraction and slow expansion to correct anterior crossbite and encourage the permanent tooth eruption. After 19 months of active orthodontic treatment, the anterior crossbite was improved, and the eruption of permanent teeth made good progress. No evidence of progression and exacerbation of MNTI has been found by both CT and MR imaging. As the observation period is still short, we need a careful and long-term follow-up of her occlusion and MNTI. Furthermore, when we encounter rare cases without previous experience and reports, informed consent was of particular importance.

BACKGROUND: Open bite is considered one of the most complicated malocclusions in orthodontic treatment. In this study, the authors successfully treated total open bite involved in hypercementosis using orthodontic miniscrews. CASE DESCRIPTION: A woman aged 25 years 8 months had total open bite. Her occlusal contact at the maximum intercuspation was present at the right second molars. A panoramic radiograph showed diffuse hypercementosis. The titanium miniscrews were interradicullay implanted between the first and second molars, and intrusion force was applied for 14 months. After active treatment, the patient's maxillary first molars showed about 1.6-millimeters of intrusion, resulting in counterclockwise mandibular rotation. Her acceptable occlusion was maintained after 1.0-year retention. PRACTICAL IMPLICATIONS: Miniscrews might be useful tool to improve malocclusion involved in diffuse hypercementosis though they are considered to be difficult to move and brought on ankylosis.

Le Fort I型骨切り術(LI)単独と馬蹄形+LIを比較し、馬蹄形+LIによる上下顎移動術の有用性について検討した。当院で施行した上下顎移動術22症例のうち、馬蹄形+LI 4症例を対象とした。出血量については、馬蹄形+LIは約635mL、LIは約379mLとなり、馬蹄形+LIとLIの出血量には有意差が認められた。手術時間は馬蹄形+LIは約5時間24分、LIは約5時間2分であり、馬蹄形+LIとLIの手術時間には有意差は認められなかった。馬蹄形の予定上顎移動量と実際の上顎移動量の比較については、前方部の予定移動量は3.75mm、実際の上顎移動量は3.3mm、後方部の予定移動量は4.25mm、実際の上顎移動量は2.8mmとなった。後方部の実際の上顎移動量が予定の上顎移動量より少なくなった理由として、後方部は蝶形骨翼状突起をはじめ下行口蓋動脈周囲の骨の干渉が完全に取り除けていなかったことなどが考えられた。

骨格性下顎前突症は、その改善に上下顎移動術が適用される場合があり、とりわけ上下顎歯列弓幅径の著しい不調和が認められる症例では、上顎骨に対する分割骨切り術の併用が必要となる。今回、我々は上顎歯列弓の狭窄を伴う骨格性下顎前突症例に対し、二分割Le Fort I型骨切り術と下顎枝矢状分割術(SSRO)を併用した外科的矯正歯科治療を施行し、良好な結果を得たので報告する。初診時年齢42歳の女性で、受け口を主訴として来院した。現病歴としてシェーグレン症候群に起因する唾液分泌量低下を示した。口腔内所見としてoverjetは-3.5mm、overbiteは+4.3mmで、右側第一小臼歯から左側犬歯にかけて反対咬合が、両側第一大臼歯部には交叉咬合がそれぞれ認められた。正貌はオトガイの左方偏位と咬合平面の左上がりを呈し、側貌はstraight typeであった。側面頭部エックス線規格写真分析の結果、∠ANBは-0.3°と下顎骨の前方位を認め、FMAは37.6°とhigh mandibular plane angleであることから、本症例は上下顎歯列弓幅径の不調和と左上がりの咬合平面傾斜を伴う骨格性下顎前突症と診断された。17ヵ月の術前矯正治療後、二分割Le Fort I型骨切り術とSSROを併用した顎矯正手術を施行した。通法によりLe Fort I型骨切りを行い、正中にて上顎を分割し両骨片間を臼歯部で4.0mm開大させ、上顎正中を顔面正中に一致させ口蓋床にて固定した。下顎はSSROにて右側6.5mm、左側5.0mmの後方移動を行いチタンプレートにて固定した。顎間固定終了後、術後矯正治療により緊密な咬合が獲得されたため、保定へ移行した。上下顎歯列弓幅径の不調和は改善され、良好な咬合関係が確立された。以上より、上顎二分割Le Fort I型骨切り術を併用した上下顎同時移動術は上下顎歯列弓幅径の調和を図る際の歯の移動を最小限に抑え、正中二分割を行わない場合と比較して、治療期間を短縮する上でも有用であることが示唆された。(著者抄録)

Development of the masticatory system is influenced by functional needs. Furthermore, masticatory exercise can improve masticatory function. The aim of this study was to evaluate the potential effect of the gum chewing exercise on the maximum bite force (MBF) in adult subjects with different facial morphologies. MBF was measured by a portable occlusal force gauge and lateral cephalogram was used for evaluation of craniofacial morphology in 19 individuals (7 males and 12 females) with a mean age of 25.4 years (SD ± 4.3). The volunteers underwent gum chewing exercise for 5 min twice a day for 4 weeks. MBF was measured before (T1) and after the 4-week exercise (T2). The facial morphology of the subjects was classified into the brachy (n = 7), mesio (n = 7), and dolicho (n = 5) facial types. In all three groups, exercise was associated with a significant increase in MBF, though the percent increase was highest in the dolicho facial type. We conclude that gum chewing exercise can improve masticatory performance, especially in individuals with dolicho facial morphology.

We successfully treated a Class II Division 2 patient with maxillary group distalization using interradicular miniscrews. A woman, aged 28 years 11 months, had a convex profile and an excessive overjet caused by a skeletal Class II jaw-base relationship. After leveling and alignment, titanium miniscrews were obliquely implanted between the maxillary second premolar and first molar. To distalize the maxillary dentition, nickel-titanium closing coil springs with a 2-N load were placed between the screws and the hooks on the archwire. After 28 months of active orthodontic treatment, a proper facial profile and an acceptable occlusion were achieved with a 4-mm distalization of the maxillary dentition. The resultant occlusion was stable throughout a 5-year retention period. Interradicular miniscrews were useful to distalize the maxillary dentition for correcting a Class II malocclusion. This new strategy, group distalization with miniscrews, can make the treatment simpler with greater predictability.

This article demonstrated the usefulness of a non-contact 3-dimensional (3D) morphometric apparatus in orthodontic diagnosis and treatment evaluation. A female patient, 23 years 6 months of age, had a Class III malocclusion with mandibular deviation. The 3D images taken by a 3D morphometric apparatus figured out her protrusive chin of 6 mm on the deviation side compared to the non-deviation side, and showed a possibility of orthognathic surgery. Before starting of orthodontic treatment, a diagnostic splint was used for 2 months to determine her proper mandibular position. The 3D images retaken for quantitative evaluation showed decrease of the mandibular protrusion by approximately 3 mm, and improvement of facial asymmetry. Then, we decided to treat the patient without orthognathic surgery. After 18 months of active orthodontic treatment with miniscrew anchorage, the mandibular deviation was improved and an acceptable occlusion was achieved. The 3D images at posttreatment demonstrated significant decrease of chin protrusion on the deviation side, and improvement of facial asymmetry. In conclusion, a 3D morphometric apparatus could provide quantitative data of facial asymmetry and chin protrusion and contributed decision making process of treatment planning in a patient with facial asymmetry.

今回、我々は抜歯を伴う矯正歯科治療の後戻り症例に対して、歯科矯正用アンカースクリューを固定源に再治療を行い、良好な結果を得たので報告する。患者は29歳9ヵ月の女性で、前歯で物が噛みにくいことを主訴に来院した。13歳から18歳までマルチブラケット装置による矯正歯科治療の既往があり、上顎左側側切歯と上顎右側および下顎両側第一小臼歯が抜歯されていた。下顎骨の後方回転による重篤なskeletal Class IIを呈し、臼歯関係はAngle Class Iであるが、オーバージェットが7mm、オーバーバイトが0mmの水平的な前歯部開咬であった。さらに下顎前歯部に著しい叢生を認めた。埋伏した上下顎第三大臼歯を抜歯し、クワドヘリックス、マルチブラケット装置と歯科矯正用アンカースクリューを用いて、上顎臼歯の圧下と下顎歯列のアップライトを行った。18ヵ月の動的治療の結果、下顎骨の反時計方向の回転により、適正な前歯部被蓋関係と機能的なI級の咬合関係が確立された。これらのことから、歯科矯正用アンカースクリューは、抜歯を伴う矯正歯科治療の後戻りに対する再治療に有効であることが示唆された。(著者抄録)

Background Bone mass and mineralization are largely influenced by loading. The purpose of this study was to evaluate the reaction of the entire mandibular bone in response to decreased load during growth. It is hypothesized that decreased muscular loading will lead to bone changes as seen during disuse, i.e. loss of bone mass. Methods and Findings Ten 21-day-old Wistar strain male rats were divided into two groups (each n=5) and fed on either a hard-or soft-diet for 11 weeks. Micro-computed tomography was used for the investigation of bone mineralization, bone volume, bone volume fraction (BV/TV) and morphological analysis. Mandibular mineralization patterns were very consistent, showing a lower degree of mineralization in the ramus than in the corpus. In the soft-diet group, mineralization below the molars was significantly increased (p<0.05) compared to the hard diet group. Also, bone volume and BV/TV of the condyle and the masseter attachment were decreased in the soft-diet group (p<0.05). Morphological analysis showed inhibited growth of the ramus in the soft-diet group (p<0.05). Conclusion Decreased loading by a soft diet causes significant changes in the mandible. However, these changes are very region-specific, probably depending on the alterations in the local loading regime. The results suggest that muscle activity during growth is very important for bone quality and morphology.

The influence of masticatory loading stimulus on mandibular development is not fully clear. In this paper, experimental alterations in the daily muscle use, caused by a changed diet consistency, were continuously monitored, while adaptations in bone and cartilage were examined. It is hypothesised that decreased muscular loading will result in a decrease in the growth factor expression and mandible growth. Fourteen 21-day-old Wistar strain male rats were randomly divided into two groups and fed on either a hard or soft diet for 14 weeks. An implanted radiotelemetric device recorded continuously muscle activity of the superficial masseter muscle. Chondroblast proliferation in the condylar cartilage was identified by insulin-like growth factor-1 receptor (IGF-1r) immunostaining. Furthermore, an X-ray was taken for cephalometric analysis. In the soft-diet group, the duty time of the superficial masseter muscle at higher activity levels was significantly lower than that in the hard-diet group. This decrease in muscular loading of the jaw system was accompanied by: a significant reduction in (i) articular cartilage thickness, (ii) expression of IGF-1r immunopositive cells and (iii) mandible ramus height. In conclusion, a decrease in masticatory demand during the growth period leads to insufficient mandibular development.

Introduction: In this study, we examined the impacts of age, sex, root length, bone levels, and bone quality on orthodontic tooth movement. Methods: Clear aligners were programmed to move 1 central incisor 1mmover the course of 8 weeks. Thirty subjects, ages 19 to 64, were enrolled, and measurements were made on digital models (percentage of tooth movement goal achieved). Morphometric features and bone quality were assessed with cone-beam computed tomography. Data from this study were combined with data from 2 similar studies to increase the power for some analyses. Results: The mean percentage of tooth movement goal achieved was 57% overall. Linear regression modeling indicated a cubic relationship between age and tooth movement, with a decreasing rate of movement from ages 18 to 35 years, a slightly increasing rate from ages 35 to 50, and a decreasing rate from ages 50 to 70. The final decreasing trend was not apparent for women. As would be expected, the correlation was significant between the percentage of the goal achieved and the cone-beam computed tomography superimposed linear measures of tooth movement. A significant negative correlation was found between tooth movement and the measurement apex to the center of rotation, but bone quality, as measured by fractal dimension, was not correlated with movement. Conclusions: The relationship between age and tooth movement is complex and might differ for male and female patients. Limited correlations with cone-beam computed tomography morphology and rate of tooth movement were detected.

We successfully treated a nonsyndromic oligodontia patient with implant-anchored orthodontics and prosthetic restorations. A woman, age 18 years 11 months, had a straight profile and a skeletal Class I jaw-base relationship but had spaced arches because of 7 congenitally missing teeth. After leveling and alignment of the dentition, a titanium miniscrew was temporarily placed at the distal alveolus of the mandibular right first premolar, and the posterior teeth were mesialized to reduce the restorative spaces. After determination of the incisor positions, 3 dental implants were respectively inserted at the sites of the maxillary canines and the mandibular left lateral incisor with guided bone regeneration procedures. Then, screw-retained temporary prostheses were delivered after subepithelial connective tissue grafting and used for molar mesialization as absolute anchorage. After 36 months of active orthodontic treatment, an acceptable occlusion was achieved, both functionally and esthetically, with the 3 dental implants. The maxillary and mandibular molars were mesialized, but the changes of incisor position were minimal. As a result, a proper facial profile was maintained, and an attractive smile was achieved. The resultant occlusion was stable throughout a 3-year retention period. In conclusion, interdisciplinary treatment combined with orthodontics, implant surgery, and prosthodontics was useful for a nonsyndromic oligodontia patient. Especially, the new strategy-implant-anchored orthodontics-can facilitate the treatment more simply with greater predictability.