M. de Koning

3D evaluation of the lingual fracture line after a bilateral sagittal split osteotomy of the mandible.

The purpose of this prospective observational study was to evaluate whether cone beam CT (CBCT) is a useful tool for analyzing the fracture line in a bilateral sagittal split osteotomy (BSSO). The patient group consisted of 40 consecutive patients (9 males and 31 females) with a mandibular hypoplasia who underwent a BSSO advancement (Hunsuck modification; n=80 splits) between September 2006 and July 2008. The mean age at the time of surgery was 34 years (range 17-61 years). A newly developed lingual split scale was used to categorize the path of the fracture line on the lingual side of the ramus based on one-day postoperative data sets reconstructed from CBCT data. Although all splits (n=80) were performed according to the standardized protocol, only 51% of the fracture lines run according to the Hunsucks description, whereas 33% ran through the mandibular canal and 16% split otherwise. The split pattern was influenced by the length of the medial osteotomy (p=0.01). In conclusion, 3D imaging is a useful tool for analyzing the surgical outcome of a BSSO and has the potential to provide substantial data on the position of the proximal segments as a result of the lingual fracture line.

The potential of the horizontal ramus of the mandible as a donor site for block and particular grafts in pre-implant surgery.

The results on 32 consecutive patients, who underwent bone grafting prior to implant surgery, are presented. The grafts were taken from the horizontal part of the mandible, including the full height of the buccal cortico-cancellous plate and were used to reconstruct alveolar defects or to augment sinus floors. 3-5 months postoperatively, 99 implants were inserted in 43 onlay grafts and in 17 sinus floor augmentations. The follow-up ranged from 2-6 years post implant insertion. Parameters examined included: healing of donor site and bone grafts, implant survival, peri-implant condition, donor site morbidity and patient satisfaction. This study indicates that with one full height ramus graft, alveolar defects comprising a bicuspid-molar area, can be augmented. The grafted volume is also sufficient to augment one sinus floor. The implant survival rate (99%) compares well with studies using iliac crest or skull bone. Postoperative complaints were minimal, resulting in extremely high patient satisfaction (97%).

One year postoperative hard and soft tissue volumetric changes after a BSSO mandibular advancement.

In this study, cone beam computed tomography (CBCT) and three dimensional (3D) stereophotogrammetry are used to compare the 3D skeletal and soft tissue changes caused by a bilateral sagittal split osteotomy (BSSO) 1 year after a mandibular advancement. Eighteen consecutive patients with a hypoplastic mandible were treated with a BSSO according to the Hunsuck modification. Preoperatively and 1 year postoperatively, a CBCT scan was acquired and a 3D photograph. The pre- and postoperative CBCT scans were matched using voxel based registration. After registration, the mandible could be segmented in the pre- and postoperative scans. The preoperative scan was subtracted from the postoperative scan, resulting in the hard tissue difference. To investigate the soft tissue changes, the pre- and postoperative 3D photographs were registered using surface based registration. After registration the preoperative surface could be subtracted from the postoperative surface, resulting in the overall volumetric difference. As expected, a correlation between mandibular advancent and volumetric changes of the hard tissues was found. The correlation between advancement and soft tissues was weak. The labial mental fold stretched after surgery. This study proved that using 3D imaging techniques it is possible to document volumetric surgical changes accurately and objectively.

Three-dimensional changes in nose and upper lip volume after orthognathic surgery

Orthognathic surgery aims to improve both the function and facial appearance of the patient. Translation of the maxillomandibular complex for correction of malocclusion is always followed by changes to the covering soft tissues, especially the nose and lips. The purpose of this study was to evaluate the changes in the nasal region and upper lip due to orthognathic surgery using combined cone beam computed tomography (CBCT) and three-dimensional (3D) stereophotogrammetry datasets. Patients who underwent a Le Fort I osteotomy, with or without a bilateral sagittal split osteotomy, were included in this study. Pre- and postoperative documentation consisted of 3D stereophotogrammetry and CBCT scans. 3D measurements were performed on the combined datasets and analyzed. Anterior translation and clockwise pitching of the maxilla led to a significant volume increase in the lip. Cranial translation of the maxilla led to an increase in the alar width. The combination of CBCT DICOM data and 3D stereophotogrammetry proved to be useful in the 3D analysis of the maxillary hard tissue changes, as well as changes in the soft tissues. Measurements could be acquired and compared to investigate the influence of maxillary movement on the soft tissues of the nose and the upper lip.

Stability, complications, implant survival, and patient satisfaction after Le Fort I osteotomy and interposed bone grafts: follow-up of 5-18 years

The results of a retrospective study on 24 patients who underwent a Le Fort I osteotomy to improve the condition for implant insertion are presented. They all had an edentulous maxilla, Cawood and Howell class VI. Bone grafts were taken from the anterior or posterior iliac crest and implants were placed between 3 and 6 months after the osteotomy. The follow-up period ranged from 5 to 18 years. Initial complications occurred in seven patients in whom small bony defects were present at the time of the implant insertion procedure. The position of the advanced and downward grafted maxilla remained stable over the years. A total of 135 implants were initially inserted, of which 34 failed over the years. Ten implants were inserted to compensate for lost ones, of which only one failed. The screw implants tended to do better than the cylindrical implants. Two patients lost all implants; they had undergone previous surgery affecting the sinus and were also heavy smokers. The remaining 22 patients were satisfied with their treatment as shown by visual analogue scale scores. The results presented are in keeping with those of other reports and underscore the viability of the procedure.

Three-dimensional evaluation of the alar cinch suture after Le Fort I osteotomy

Orthognathic surgery has an influence on the overlying soft tissues of the translated bony maxillomandibular complex. Improvements in both function and facial appearance are the goals of surgery. However, unwanted changes to the soft tissues, especially in the nose region, frequently occur. The most common secondary change in the nasolabial region is widening of the alar base. Various surgical techniques have been developed to minimize this effect. The purpose of this study was to evaluate the changes in the nasal region due to orthognathic surgery, especially the alar width and nasal volume, using combined cone beam computed tomography (CBCT) and three-dimensional (3D) stereophotogrammetry datasets. Twenty-six patients who underwent a Le Fort I advancement osteotomy between 2006 and 2013 were included. From 2006 to 2010, no alar base cinch sutures were performed. From 2010 onwards, alar base cinch sutures were used. Preoperative and postoperative documentation consisted of 3D stereophotogrammetry and CBCT scans. 3D measurements were performed on the combined datasets, and the alar base width and nose volume were analyzed. No difference in alar base width or nose volume was observed between patients who had undergone an alar cinch and those who had not. Postoperatively the nose widened and the volume increased in both groups.