Niigata Dent. J. 35（2）：1 − 7,

185

2005

− ORIGINAL ARTICLE −Anchorage effect of palatal osseointegated implant on teeth
with simulated bone loss: A finite element study
Fengshan Chen1），Kazuto Terada2），Yassin Hemoudi1），
Fumi Takemura1），Kooji Hanada3），Isao Saito1）
1)

Division of Orthodontics, Graduate School of Medical and Dental Sciences, Niigata University (Chief : Prof. Isao Saito)
2)

Polyclinic Intensive Oral Care Unit, Niigata University Medical and Dental Hospital (Chief: Prof.Tadashi Noda)
3)

Meirin College for Dental TechnologyReceived 10. 21. 2005 ／ Accepted 11. 30. 2005

骨吸収を想定した歯における矯正用パラタルインプラントの固定効果に関する有限要素法を用いた研究
陳竹鳳村山 1），寺 田 員 人 2），Yassin Hemoudi1），史 1），花 田 晃 治 3），齋 藤功 1）

1）

新潟大学大学院医歯学総合研究科歯科矯正学分野（主任 : 齋藤2）

新潟大学医歯学総合病院特殊歯科総合治療部（部長 : 野田功）忠）

3）

明倫短期大学

Key words：implant, anchorage, finite element analysis
Abstract：The purpose of this study was to compare the anchorage effect of the osseointegrated implantconnected on the second premolar with different alveolar bone loss using the finite element analysis. Four modelswith the implant and four models without the implant were constructed. Four levels of alveolar bone loss (0, 2,4 and 6 mm) were studied. The model with the implant was consisted of two maxillary second premolars, theirassociated periodontal ligament and alveolar bones, palatal bone, palatal implant and transpalatal arch. The model
without the implant was used to compare with the model with the implant. The horizontal force (mesial 5N,palatal 1N) was loaded at the buccal bracket of each second premolar. The stress in the periodontal ligament,
implant and surrounding bone were calculated. The results showed that the palatal implant could significantly
reduce von Mises stress (maximum von Mises stress was reduced from 29.63% to 44.30% with the alveolar boneloss from zero mm to six mm) and make stress even distribution in the periodontal ligament. The stress in
the implant and surrounding bone was very low. These results suggested that palatal implant is a good tool toenhance the anchorage of teeth with alveolar bone loss.
抄録：本研究の目的は，第二小臼歯部の歯槽骨の吸収程度とこれに連結したインプラントによる加強固定の効果について，有限要素法を用いて検討することとした。歯槽骨の吸収の程度を４段階（０，２，４，６mm）設定し，それぞれインプラント有りと無しのモデルについて調べた。インプラントのあるモデルは，左右側の上顎第二小臼歯，歯根膜，歯槽骨，口蓋骨，パラタルインプラント，インプラントと小臼歯とを連結するパラタルバーで構成した。インプラントのないモデルは，上述のモデルにおいてインプラントを除外し , 他は同じとした。水平力として，近心方向に5N と口蓋方向に 1N を両側の上顎第二小臼歯の頬側ブラケットに負荷した。この荷重を負荷した時，歯根膜，インプラントとその周囲の骨に現れる応力を算出した。その結果，インプラントを用いることで，設定した０〜６mm 歯槽骨の吸収したモデルにおいて，von Mises stress が歯根膜部で 29.63 〜 44.30% の減少した。インプラントとその周囲の骨に現れる応力は , きわめて小さかった。このことより，歯槽骨の吸収を起こしている歯に対して，加強固定の−1−186

Niigata Dent. J. 35（2）：2005

ためにパラタルインプラントが有効であることが示唆された。

1. Introduction
The percentage of adult patients who seek
orthodontic treatment has increased significantly
in recent decades 1）. These patients often havebone loss in posterior teeth, which is often used asanchorage teeth. Excessive orthodontic force withadvanced periodontal bone loss may traumatize theperiodontium, and increased apical pressure because
reduced bony support may contribute to apical root
resorption2）. Additional anchorage aid is often required
for the posterior teeth with alveolar bone loss (ABL).
Routinely, headgears, transpalatal arches (TPAs)
and Nance appliances are used to enhance anchorage
during clinic treatment. However, many patients

Fig. 1. Palatal implant used as an orthodontic anchorage
in the clinic. The second maxillary premolars wereanchored by the implant through the transpalatalarch.

rejected headgear wear because of social and esthetic
concerns and the success of this treatment depends

Finite element analysis (FEA) has been increasingly

entirely on patient cooperation3）. In most studies onused for the prediction of the eﬀects of stress on theTPAs4） and Nance appliance5, 6）, anchorage loss wastissues in orthodontics. FEA is a mathematical methodunavoidable.

in which the shape of complex geometric objects andImplants, as a means of enhancing orthodontic

their physical properties are computer constructed.

anchorage, are gaining increased importance inPhysical interactions of various component of theorthodontic treatment because of the limitations andmodel are then calculated in terms of stress andacceptance problems of conventional intraoral orstrain.

7, 8）. The median − sagittal

The purpose of this study was to analyze

region of the hard palate9, 10） was described as a suitable

the anchorage effect of the palatal implant by

location for implant placement because orthodontic

investigating periodontal stresses when the second

patients generally have a complete dentition. This

premolar at diﬀerent levels of alvelor bones loss.

extraoral anchorage aids

region is surgically very well accessible and offers
excellent peri − implant conditions due to the attached

2. Material and method

mucosa. Palatal implant is often used to connect
with the second premolar by a transpalatal arch to

2.1 Model

increase anchorage as shown in Fig. 1. There are

2.1.1 Models with the implant: Model 1-49, 10）

some clinical studies

showed that a palatal implant

Model 1(Fig. 2A) was composed of two maxillary

could offer enough anchorage effect. However, thepremolars, PDL, alveolar bone, palatal implant, palatalalveolar condition of anchorage teeth was not wellbone, bracket, band, and TPA. The maxillary second

documented. The implant anchorage eﬀect on the teeth

premolar was created by manually designing the toothwith ABL has not been sufficiently explored. Henceaccording to dimension and morphology found in athere is a necessity to explore what occurred when thestandard dental anatomy textbook12）. The outmost

implant was used as an anchorage on the teeth withboundary of the tooth was ﬁrst deﬁned and sectioning

different ABL. As we know, an anchorage is related

the tooth into cross-sections created the thirdto periodontal stress11）; the anchorage eﬀect of palataldimension. The tooth was reconstructed by inputting

implant can be explained by the redistribution of thethree-dimensional coordinates, defining the shape of

periodontal ligament (PDL) stress of the natural teeth

the tooth into the Unigraphics NX 1.0 (Unigraphic

connected with the palatal implant.

solutions Inc.2002 California). Next the PDL, alveolar−2−