finite element analysis model: osteotomy design to detect palatal expansion

Analisi dei modelli di espansione da SARPE utilizzando modelli agli elementi finiti

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.

Autore in primo piano: Sviluppo di un nuovo modello di analisi agli elementi finiti per il miglioramento delle tecniche chirurgiche ortognatiche 

Modello di analisi agli elementi finiti per la valutazione dei modelli di espansione da espansione palatale rapida assistita chirurgicamente

Watch this Scientific Journal Video about Finite Element Analysis Model: Osteotomy Design to Detect Palatal Expansion at JoVE.com

Finite Element Analysis Model: Osteotomy Design to Detect Palatal Expansion  

Modello di analisi agli elementi finiti: progettazione dell'osteotomia per rilevare l'espansione palatale

Per iniziare, avviare il software SolidWorks per creare un piano di un millimetro di spessore dall'apertura piriforme verso la cresta infrazigomatica. Ora apri il menu Inserisci, quindi fai clic sulle opzioni Geometria di riferimento e Piano. Dal piano dell'osteotomia, selezionare tre punti funzione e fare clic su OK per creare il piano O1.Passare nuovamente al piano facendo clic su Inserisci e Geometria di riferimento. Questa volta, scegli il piano dell'osteotomia e imposta una distanza di offset di un millimetro. Fate clic su OK per creare un piano di taglio inferiore contrassegnato con O2. Ora naviga per dividere selezionando Inserisci, seguito da Funzioni, e scegli i piani O1 e O2 in Strumenti di rifilatura.Selezionare i corpi di destinazione e premere Taglia corpi per creare un'anteprima di taglio. Quindi, selezionare le caselle di controllo nella sezione Corpi risultanti e premere OK per separare il complesso mascellare. Quindi fare clic sul corpo tra i piani O1 e O2, fare clic con il pulsante destro del mouse e premere Canc nella sezione Corpo.Per esportare i modelli con diversi angoli di osteotomia buccale, fare clic su File, quindi su Salva con nome e scegliere x_t Parasolid dall'elenco dei tipi di file. Infine, fare clic su Salva per esportare i modelli per il software di analisi agli elementi finiti. L'analisi dimostrata ha utilizzato l'immagine della tomografia computerizzata a fascio conico di una donna di 47 anni con deficit mascellare per generare un modello.Per un'accurata simulazione chirurgica, sono stati separati il setto nasale, le pareti laterali della cavità nasale e la fessura pterigomascellare.

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Finite Element Analysis Model: Osteotomy Design to Detect Palatal Expansion

95 Views. Per iniziare, avviare il software SolidWorks per creare un piano di un millimetro di spessore dall'apertura piriforme verso la cresta infrazigomatica. Ora apri il menu Inserisci, quindi fai clic sulle opzioni Geometria di riferimento e Piano. Dal piano dell'osteotomia, selezionare tre punti funzione e fare clic su OK per creare il piano O1.Passare nuovamente al piano facendo clic su Inserisci e Geometria di riferimento. Questa volta, scegli il piano dell'osteotomia e imposta una distan...

Video: Finite Element Analysis Model: Osteotomy Design to Detect Palatal Expansion  

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 patients. However, asymmetric expansion between the left and right sides has been reported in 7.52% of all SARPE patients, of which 12.90% had to undergo a second surgery for correction. The etiologies leading to asymmetric expansion remain unclear. Finite element analysis has been used to evaluate the stress associated with SARPE in the maxillofacial structures. However, as a collision of the bone at the LeFort I osteotomy sites occurs only after a certain amount of expansion, most of the existing models do not truly represent the force distribution, given that the expansion amount of these existing models rarely exceeds 1 mm. Therefore, there is a need to create a novel finite element model of SARPE that could perform a clinically required amount of expander activation for further analysis of the expansion patterns of the hemimaxillae in all three dimensions. A three-dimensional (3D) skull model from cone beam computed tomography (CBCT) was imported into Mimics and converted into mathematical entities to segment the maxillary complex, maxillary first premolars, and maxillary first molars. These structures were transferred into Geomagic for surface smoothing and cancellous bone and periodontal ligament creation. The right half of the maxillary complex was then retained and mirrored to create a perfectly symmetrical model in SolidWorks. A Haas expander was constructed and banded to the maxillary first premolars and first molars. Finite element analysis of various combinations of buccal osteotomies at different angles with 1 mm clearance was performed in Ansys. A convergence test was conducted until the desired amount of expansion on both sides (at least 6 mm in total) was achieved. This study lays the foundation for evaluating how buccal osteotomy angulation influences the expansion patterns of SARPE.

A set of novel finite element models of surgically assisted rapid palatal expansion (SARPE) that could perform a clinically required amount of expander activation with various angles of buccal osteotomy was created for further analysis of the expansion patterns of the hemimaxillae in all three dimensions.

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