Volumetric comparison of maxillofacial soft tissue morphology: computed tomography in the supine position versus three-dimensional optical scanning in the sitting position

Changes in three-dimensional nasal morphology according to the direction of maxillary movement during Le Fort I osteotomy

BACKGROUND

Le Fort I (LFI) osteotomy is commonly performed by orthognathic surgeons; however, postoperative changes in nasolabial morphology are of concern. Several factors influence such changes, but it is difficult to accurately predict the postoperative results. This study evaluated the three-dimensional (3D) morphological changes in the nasal region according to the different directions of maxillary movement during LFI osteotomy.

MATERIALS AND METHODS

Forty-one patients who underwent LFI osteotomies were included. All patients were divided into maxilla-up (Group U: 20 patients) and maxilla-forward (Group F: 21 patients) groups. Soft tissue morphologies were determined preoperatively and 3 or 6 months postoperatively using an optical 3D scanner. All datasets were evaluated in terms of volume changes in nine subregions and changes in linear measurements around the nasal area.

RESULTS

Both groups exhibited increased nasal volumes after surgery in the order of the three upper, three central, and three lower subregions. The change in volume of the central nasal region tended to be greater in Group U than that in Group F.

CONCLUSION

We evaluated 3D morphological changes in the nasal region according to the direction of maxillary movement during LFI osteotomy. Group U exhibited a large change in the volume of the central nasal region.

Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion

OBJECTIVES

This study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy.

MATERIALS AND METHODS

Patients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect.

RESULTS

A total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0-T1 (p = 0.02), T0-T2 (p = 0.03), and T0-T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group.

CONCLUSIONS

We found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback.

CLINICAL RELEVANCE

It is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Cone-Beam Computed Tomography for Objective Diagnosis of Age-Related Soft Tissue Changes in Lower Face and Neck

BACKGROUND

An objective assessment of the causes of age-related contour deformities of the soft tissues of the face and neck is very important in esthetic surgery, especially as minimally invasive techniques gain increasing popularity.

METHODS

To visualize the tissues that cause age-related soft tissue changes, we performed cone-beam computed tomography (CBCT) in 37 patients who underwent facial and neck rejuvenation procedures in 2021-2022.

RESULTS

Vertical CBCT enabled visualization of the causes and degree of tissue involvement in age-related changes in the lower third of the face and neck. CBCT showed the location and condition of the platysma (hypo- [ptosis], normo-, or hyper-tonus), position, thickness, and location (above and/or below the platysma) of fat tissue, presence of ptosis of the submandibular salivary glands, condition of the anterior bellies of the digastric muscles, and the degree of their participation in contours of the cervicomandibular angle, and location of the hyoid bone. Moreover, CBCT enabled demonstrating for the patient the facial and neck contour deformations and discussing the suggested corrective methods using a clear objective visual image.

CONCLUSIONS

CBCT in the upright position enables objective assessment of each soft tissue in the age-related deformity of the cervicofacial region and provides an opportunity to plan the appropriate impact on the particular anatomical structures during rejuvenation procedures and estimate their results. This is the only study to date to objectively and clearly visualize the entire topographic anatomy of the soft tissues of the face and neck vertically for plastic surgeons and patients.

LEVEL OF EVIDENCE IV

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Investigation of the usability of cone-beam computed tomography images using digital radiography equipment for boron neutron capture therapy treatment planning in the sitting position

In boron neutron capture therapy (BNCT), treatment planning images are acquired in the recumbent position. However, treatment is occasionally performed in the sitting position. For BNCT treatment planning, we investigated the usability of cone-beam computed tomography (CBCT) images using digital radiography equipment that allows imaging in the sitting position. The dose calculation results in both CBCT and fan beam CT were in good agreement. This method will eliminate the posture difference between planning and treatment.

A comparison of postoperative, three-dimensional soft tissue changes in patients with skeletal class III malocclusions treated via orthodontics-first and surgery-first approaches

The aim of this retrospective study was to compare three-dimensional (3D) soft tissue and hard tissue changes between orthodontics-first approach (OFA) and surgery-first approach (SFA) after mandibular setback surgery. All patients underwent bilateral sagittal split osteotomy, and were examined by lateral cephalograms and 3D optical scanner before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Three standard angles (FMA, U1 to FH, IMPA) were measured as hard tissue change and the 2 sets of 3D data were superimposed, and volumetric differences were calculated as soft tissue change. Statistical analyses were performed by using unpaired t-tests. Differences with P < 0.05 were considered significant. A total of 39 patients with mandibular prognathism were included in this study. The OFA group consisted of 24 patients and the SFA group of 15 patients. The SFA group exhibited more labial inclination from T1 to T2 (p = 0.008) and T2 to T3 (p = 0.003) than did the OFA group. There were no significant changes at maxilla and mandible at each term of T0, T1, T2 and T3 (p > 0.05), but compared to before surgery, mandibular volume in SFA group significant increased at 1year (p = 0.049) after surgery. We found that the soft tissue changes after the SFA differed significantly from those after the OFA; thus, soft tissue predictions require more care. An analysis of our data compared with OFA and SFA for the patient with mandibular prognathism confirm that the mandibular soft tissue changes by postoperative orthodontic treatment and occlusal relationship in SFA.

Anthropometric Changes in the Upper Lip Between the Standing Position in the Clinic and Supine Position on the Operative Table in Secondary Cleft Lip Nasal Deformities

BACKGROUND

We evaluated changes in lip height and length by position in cleft lip nasal deformity patients who underwent treatment with Millard technique.

METHODS

A retrospective review of the medical records and an anthropometric analysis of photographs were performed in 209 cases of cleft lip nasal deformity. In the photogrammetric analysis, the lip height and length were calculated with respect to the intercanthal width. To evaluate the change in the difference between the cleft- and noncleft-side measurements between the standing and supine positions, the difference between the cleft- and noncleft-side measurements (Δnc-c) was calculated. We identified which patients and surgical factors affected the difference between the cleft- and noncleft-side measurements between the standing and supine positions (Δst-sp).

RESULTS

From a total of 120 cases, cases with missing medical charts and clinical photographs were excluded, and 89 cases were included in this study. The discrepancy between the cleft-side lip height and noncleft-side lip height was significantly different between the standing and supine positions (P = 0.007). According to the univariate regression analysis, Δst-sp (sbal-cphi) had a significant positive correlation with body mass index (P = 0.044). In the final multiple linear regression analysis, body mass index had a significant positive correlation with Δst-sp (sbal-cphi, P = 0.044).

CONCLUSION

In our results, the difference in vertical lip height is easy to underestimate in the supine position during surgery. Therefore, surgeons should verify lip height with the patient in the sitting or standing position during the operation to avoid undercorrecting lips with short heights.