Three dimensional assessment of segmented Le Fort I osteotomy planning and follow-up: A validation study

Virtual surgical analysis: long-term cone beam computed tomography stability assessment of segmental bimaxillary surgery

“…Semi-automated approaches using VBR have previously been proposed for the assessment of the postoperative outcome and follow-up of orthognathic surgery. 20,21 Shaheen et al 20 proposed a semi-automated approach using VBR with excellent repeatability for the evaluation of the surgical outcome and short-term follow-up (6 months) exclusively for one-piece Le Fort I osteotomy. Their protocol requires the identification of three landmarks for the maxillary segment to allow the calculation of translational and rotational movements.…”

“…Their protocol requires the identification of three landmarks for the maxillary segment to allow the calculation of translational and rotational movements. 20 Recently, the protocol was expanded by da Costa Senior et al 21 to include assessment of the segmented Le Fort I osteotomy, and the repeatability remained high. The reliability results of the VSA proposed in the present study are similar or better than the findings in these related studies, 20,21 where exclusively maxillary osteotomies were assessed and validated on CBCT scans obtained at the 6-month follow-up, where skeletal remodelling has only initiated.…”

“…20 Recently, the protocol was expanded by da Costa Senior et al 21 to include assessment of the segmented Le Fort I osteotomy, and the repeatability remained high. The reliability results of the VSA proposed in the present study are similar or better than the findings in these related studies, 20,21 where exclusively maxillary osteotomies were assessed and validated on CBCT scans obtained at the 6-month follow-up, where skeletal remodelling has only initiated. 32 Remodelling is present at osteotomy sites, and in the case of mandibular ramus osteotomy, is also due to mechanical stresses and changed muscular activity following orthognathic surgery.…”

“…32,33 Hence, the validity of these short-term stability assessment protocols may be limited. 20,21 The bone remodelling processes and the continuous post-surgical orthodontic treatment influences the mutual image information of longterm postoperative CBCT scans used for registration of the individual bone segments, and thus affects the performance of the VSA. Hence, long-term Table 2.…”

“…[9][10][11][12] The error may exceed the clinically relevant 0.5 mm margin, 13,14 and even the clinically acceptable surgical accuracy and stability of 2 mm. 4,8 Consequently, image registration techniques have been introduced for the superimposition of two consecutive uni-or multimodal scans based on a reference structure using mutual image information, [13][14][15][16][17][18][19][20][21] i.e. voxel-based registration (VBR), [22][23][24] hence making the re-identification of landmarks superfluous.…”