Name: Expansion Assessment Using Finite Element Analysis from Surgically Assisted Rapid Palatal Expansion (SARPE)
Uploaded: 2023-10-20T13:00:00
Description: Watch this Scientific Journal Video about Expansion Assessment Using Finite Element Analysis from Surgically Assisted Rapid Palatal Expansion SARPE at JoVE.com

expansion assessment using finite element analysis from surgically assisted rapid palatal expansion (sarpe)

有限要素モデルを用いたSARPEによる拡張パターンの解析

Surgically assisted rapid palatal expansion (SARPE) is a commonly used technique for transversely expanding the maxillary bony structure and the dental arch in skeletally mature patients1. The surgery involves a LeFort I osteotomy, a mid-palatal corticotomy, and, optionally, the release of the pterygoid-maxillary fissure2. However, undesired expansion patterns from SARPE, such as uneven expansion between left and right hemimaxillae3 and dentoalveolar process buccal tipping/rotation4, have been reported, which could lead to failure of SARPE, and sometimes, even requiring additional surgeries for correction5. Previous studies have indicated that the variation in circum-maxillary osteotomies may play a significant role in post-SARPE expansion pattern2,3, as the collisions between the bone blocks at the Le Fort I osteotomy sites can contribute to the uneven resisting force of lateral expansion of the hemimaxillae and to the rotation of the hemimaxillae with the alveolar edges below the cut moving inwards while the dentoalveolar process expands3,4. Therefore, there is a need to investigate the effects of different osteotomy directions, especially the buccal osteotomy, on post-SARPE expansion patterns.
Several finite element analysis (FEA) models have been set up to evaluate the force distribution during SARPE. However, the amount of expansion set in these models is limited to up to 1 mm, which is far below the required clinical amount6,7,8,9,10,11,12. Inadequate expansion in FEA models can lead to erroneous predictions of post-SARPE outcomes. More specifically, the collision between the bones at the osteotomy site, as reported by Chamberland and Proffit4, may not be demonstrated if the expander is not adequately turned, which may not reflect the true clinical reality. With the limited amount of expansion built in the previous models, the outcome evaluations of these models were focused on stress analysis. However, the stress analysis of FEA in dentistry is usually conducted under static loading with the mechanical properties of materials set as isotropic and linearly elastic, which further restricts the clinical relevance of the FEA studies13.
Furthermore, most of these studies did not consider the thickness of the surgical instrument at the osteotomy site6,7,8,10,11,12, often setting friction to zero at the cuts as part of the boundary conditions. However, this setting oversimplifies the contacts between the hard and soft tissues. It may significantly impact the distribution of force and the resulting expansion pattern of the hemimaxillae.
Nevertheless, no available literature has investigated the effect of osteotomy on post-SARPE asymmetry using finite element analysis (FEA) models. All the current studies employed models with symmetrical osteotomy patterns6,7,8,9,10,11,12,14, which do not reflect the reality of clinical practice where the osteotomies may differ on each side of the skull. The lack of literature examining the effect of asymmetrical osteotomies on post-SARPE asymmetry represents a significant knowledge gap that must be addressed.
Therefore, the goal of this study is to develop a novel FEA model of SARPE that can truly mimic the clinical conditions, including the expansion amount and osteotomy gap, and investigate the expansion patterns of the hemimaxillae in all three dimensions with various designs of the osteotomy. Such an approach would provide valuable insight into the mechanics underlying post-SARPE expansion patterns and serve as a useful tool for clinicians in the planning and execution of SARPE procedures.

著者スポットライト:顎矯正手術技術の改善のための新しい有限要素解析モデルの開発 

外科的支援による急速口蓋拡大からの膨張パターンを評価するための有限要素解析モデル

SARPE is commonly used for maxillary expansion in skeletal immature patients. However, asymmetric expansion has been reported with unknown etiologies. This study aims to develop a novel FEA model of SARPE that can truly mimic the clinical conditions, and to investigate the expansion patterns of the hemi-maxilla in all three dimensions.Finite element analysis has been used in the dental and bioengineering field to allow in vitro simulation of surgeries, such as SARPE. In this study, four software were utilized to set up the FEA model and to predict expansion pattern. The most challenging part, which most previous studies link, is to simulate forces at the wound healing site across osteotomy surface.To achieve this, springs were set in our pilot study and is considered a novel design for SARPE FEA. This unified element model focused on its patient patterns, making it more realistic SARPE simulation through osteotomy gap creation and experience inclusion. It presents significant potential as the clinical tool for branding and its guiding SARPE procedures.Our interdisciplinary group will work diligently to develop cutting-edge 3D models that can provide valuable insights into personalized treatment strategies to analyze and improve orthognatic surgical technique by utilizing an engineering-assisted approach and to improve communication and collaboration between orthodontists and oral maxillofacial surgeons through engineering-assisted 3D imaging system.

Watch this Scientific Journal Video about Expansion Assessment Using Finite Element Analysis from Surgically Assisted Rapid Palatal Expansion SARPE at JoVE.com

Expansion Assessment Using Finite Element Analysis from Surgically Assisted Rapid Palatal Expansion (SARPE)  

Surgically Assisted Rapid Palatal Expansion (SARPE) の有限要素解析を用いた拡大評価

まず、Ansysソフトウェアを起動して、上顎複合体のモデルの材料パラメータをソフトウェアにインポートします。次に、ツールボックス内の静的構造をクリックしてドラッグし、解析ワークスペースを作成します。エンジニアリングデータをダブルクリックし、ツールボックスの下の線形弾性をダブルクリックし、プロパティ内のすべての材料のヤング率とポアソン比を設定します。次に、形状をダブルクリックし、次にfileをダブルクリックし、import external geometry fileを選択し、generateをクリックして上顎複合体をインポートします。次に、createをクリックし、続いてBooleanをクリックし、海綿骨と歯を持つ皮質靭帯と歯根膜Booleanを生成します。有限要素解析モデルを設定するには、モデルをダブルクリックし、ジオメトリを選択して各パーツの材料特性を決定します。次に、meshを右クリックし、generate meshを押してモデル要素を構築します。次に、結合をクリックし、接触ボディにソフト部品またはスモール部品を割り当て、ターゲットボディにスティッフ部品またはラージ部品を割り当ててから、定義で接触タイプと摩擦係数を割り当てます。次に、接続を右クリックして挿入を選択し、スプリングを押して骨切り面の上部と下部を接続します。ばねの長さを 1 ミリメートルに設定し、ばね定数 K を 60 ニュートン/ミリメートルに設定します。各節点に1つのばねを配置します。X軸に沿って臨床的に許容される力を設定した後、静的構造オプションを右クリックします。挿入を押してから固定サポートを押して、口蓋平面上の構造を不動としてレンダリングします。アクリル板に正中線から離れた方向に力を加えるには、static structuralをクリックし、力を挿入して150ニュートンに設定します。次に、解析を右クリックし、挿入、変形、合計の順にクリックして、展開変形を監視します。最後に、収束テストを実行するには、ツールバーのsolveを選択し、力の収束レベルが力の基準に達するまで待ちます。次に、解析情報をクリックし、続いて全変形をクリックして展開結果を表示します。実証されたモデルは、上顎欠損症の47歳女性のコーンビームコンピュータ断層撮影画像を使用してモデルを作成しました。正確な手術シミュレーションのために、海軍中隔、外側鼻腔壁、および翼状上顎裂を分離しました。モデルの左右両面で対称的なゼロ度の切断で予備試験を行ったところ、150ニュートンの力が8ミリメートル以上の膨張を引き起こしたことが示されました。さらに、さまざまな臨床状態を模倣するために、さまざまな角度が構築されました。左右の拡張は、上顎モデルの前後のカラーマップとして見えました。

Research

JoVE Journal

Bioengineering

Expansion Assessment Using Finite Element Analysis from Surgically Assisted Rapid Palatal Expansion (SARPE)

Finite Element Analysis Model for Assessing Expansion Patterns from Surgically Assisted Rapid Palatal Expansion

Surgically assisted rapid palatal expansion (SARPE) was introduced to release bony resistance to facilitate skeletal expansion in skeletally mature ...