Soft-tissue changes after maxillomandibular advancement surgery assessed with cone-beam computed tomography

The evaluation of the nasal morphologic changes after bimaxillary surgery in skeletal class III maloccusion by using the superimposition of cone-beam computed tomography (CBCT) volumes

“…In the present study, there was an increase to the alar base width (average: 2.45 AE 1.52 mm), which result is consistent with previous studies' reports of nasal base increases with forward maxilla movement (Rosen, 1988;Kang et al, 2000;Rychman et al, 2010). Rosen (1988) suggested the following reasons for enlargement of the nasal base: superior and anterior changes in skeletal bone, which incur swelling and nasal cavity floor; the relaxation of the muscle around the nose and of the periosteum attachment; the contraction of the muscle when separated from the origin or the insertion areas; shortened muscle length after reattachment.…”

“…However, this approach has a drawback, in that with lateral cephalometric radiographs, there is no midsagittal reference plane, and so measurement errors can occur due to overlapping of bilateral structures (Rychman et al, 2010). With CBCT, contrastingly, images can be reconstructed according to the reference planes, and measurement points such as Orbitale and Gonion, which are considered to be difficult to measure in lateral cephalometric radiographs, can be accurately defined (Ludlow et al, 2009).…”

“…Additionally, this method also incurred many errors originating from patients' head orientations (Park et al, 2006). On the other hand, CBCT has advantages in that it can measure changes with high reproducibility on the same reference planes, through superimposition based on stable structures such as the skull base; also, both soft and hard tissues can be evaluated with high resolution (Rychman et al, 2010). Superimposition of CBCT data can be accomplished in one of the two ways: rigid registration or non-rigid registration.…”

“…Cevidanes et al (2010) introduced a new method by which the skull base can be used as a stable reference structure for image superimposition. Rychman et al (2010) reported soft-tissue changes from movement of hard tissue after advancement surgery on the maxilla and mandible, as evaluated using overlapped pre-and post-orthognathic-surgery CBCT images.…”

3D Assessment of Orthognathic Surgical Outcomes

“…The ideal positioning of the jaws through orthognathic surgery does not always result in an ideal soft tissue appearance because the patient's facial soft tissue does not respond to movement of the underlying skeletal tissues in a 1 : 1 ratio (Lim et al, 2010;Ryckman et al, 2010). Therefore, surgical treatment objectives must focus on the desired soft tissue outcome (Sarver, 1998), rather than on the correction of skeletal discrepancies only.…”