Tongue reduction in Beckwith-Wiedemann syndrome: outcome and treatment algorithm.

Beckwith-Wiedemann syndrome is a rare congenital overgrowth disorder with macroglossia being one of the cardinal symptoms. In pronounced cases, macroglossia can lead to airway obstruction, musculoskeletal alterations and functional deficits. Surgical tongue reduction is performed at varying ages and with different techniques. This study evaluated perioperative complications, as well as long-term aesthetic and functional outcomes, in a large cohort. A total of 68 patients, treated either surgically or conservatively, were included. Depending on the severity of macroglossia, patients were divided into three groups to determine the treatment algorithm. Complications after surgical tongue reduction were prolonged intubation and revision due to dehiscence or haematoma. In the long term, no patient suffered from impaired sense of taste or paresthesia, although the shape of the tongue was disproportional in 85%. With the present treatment algorithm, operative tongue reduction exerts a positive influence on skeletal, dentoalveolar and functional development with sufficient long-term outcome and high grade of satisfaction of the patients. Supportive therapy in an interdisciplinary centre is of fundamental importance for both surgical and conservative treatment.

Man as a living bioreactor: Long-term histological aspects of a mandibular replacement engineered in the patient's own body.

In 2016, we reported the world's first reconstruction of a mandibular discontinuity defect using a custom-made bone transplant that had been prefabricated in the gastrocolic omentum using tissue engineering strategies. However, the tissue of an engineered human neomandible has not been evaluated histologically until now. The current study assessed the long-term histological characteristics of biopsies of the neomandible 9months after transplantation. Histological analysis showed an increased amount of vital mineralized bone tissue after 10months, in comparison to biopsies obtained earlier. The engineered bone covered the surface of the bone substitute material but also grew out typical structures of cancellous bone tissue without a core of BioOss. The amount of induced bone tissue was 32% in the biopsy. In addition, the soft tissue showed an alignment of the connective tissue fibres parallel to the trabecular bone. Increasing time and mechanical forces at the mandible led to an increased amount of mineralized tissue and remodelling of the connective tissue fibres after transplantation. Further research should focus on developing advanced scaffold materials, as the outer titanium mesh cage leads to complications.

Computer-assisted orthognathic surgery: evaluation of mandible registration accuracy and report of the first clinical cases of navigated sagittal split ramus osteotomy.

Intraoperative navigation is a helpful tool in complex anatomical regions or procedures. The mobility of the mandible in relation to the skull base limits the use of navigation tools on the lower jaw if the reference device is installed on the forehead. A new workflow that allows navigation-assisted sagittal split osteotomy in orthognathic surgery using a separate non-invasive mandibular registration technique has been developed. An evaluation of accuracy in different anatomical regions and with different registration techniques was performed on skull models and skulls with movable mandibles. The mean inaccuracy was 1.51mm, with no significant difference between anatomical sites. Using a splint-based reference device allows the movable mandible to be registered independently from the midface. Registration using metal points in the splint provides higher accuracy than using interdental anatomical landmarks. The workflow could be transferred successfully to patient treatment. Navigation-assisted osteotomy by Obwegeser-Dal Pont technique was performed without any complication in six patients. The mean deviation from the planned osteotomy line was 1.52mm. The navigated sagittal split ramus osteotomy seems to be a suitable technique to increase patient safety.

Mechanical resistance of the periorbita and the orbital floor complex--are isolated orbital floor fractures only a soft tissue problem?

The primary aims of orbital floor reconstruction are to prevent enophthalmos and herniation of the orbital contents in order to achieve correct globe position. Theoretically, the mechanical load of the orbital floor is approximately 0.0005N/mm(2) (30g orbital content onto 600mm(2) of orbital floor area). Therefore, low mechanical stress from orbital floor reconstruction materials is expected. The periorbita and orbital floor complex (bony orbital floor with periorbita) of 12 human cadavers were investigated for their mechanical resistance to distortion and compared to different absorbable pliable reconstruction materials after modification with pores (Bio-Gide, Creos, and PDS). The human periorbita resistance (approximately 1.4N/mm(2)) was comparable to that of the absorbable membranes (Creos, Bio-Gide), and the resistance of PDS (approximately 2.3N/mm(2)) was comparable to that of the orbital floor complex. The periorbita has a higher stability than the bony orbital floor. Therefore, in isolated orbital floor fractures with a traumatized bony orbital floor and periorbita, reconstruction of the soft tissue as a periorbita equivalent with a resorbable membrane appears to be adequate to prevent enophthalmos and herniation of the orbital contents.

Detection of the genial spinal canal in atrophic mandibles with a CBCT: a cadaver study.

OBJECTIVES: The use of a single midline implant to retain a complete mandibular denture when more implants cannot be used is an incipient treatment modality. However, in the mandibular symphysis, the genial spinal canal (GSC) is an anatomical structure with neurovascular content that can be harmed during dental implant surgery. The purpose of the present study was to use CBCT of edentulous atrophic cadaver mandibles and evaluate how often the simulated placement of a single midline implant would contact the GSC if present. METHODS: CBCT scans of 47 edentulous cadaver mandibles were performed. A digital simulation of the placement of a single midline implant (3.8 × 11.0 mm) was performed, and the implant-GSC contact was evaluated. RESULTS: A GSC was detected in the CBCT scan of all atrophic mandibles. In 42 cases (89.4%), the single midline implant contacted the GSC. On average, the five cases without GSC contact had a higher alveolar ridge (4.1 mm) and a lower GSC (0.79 mm) than did the cases with GSC contact. CONCLUSIONS: CBCT scans can adequately detect the GSC during pre-surgical diagnostics. There is a high risk of implant-GSC contact during surgery of the anterior mandible. However, the clinical relevance of such a contact is not known yet, because none of the clinical studies evaluating a single midline implant has reported any implant-GSC contact-related complications.

Mechanical properties of collagen membranes modified with pores--are they still sufficient for orbital floor reconstruction?

Adequate mechanical strength is essential for materials used to reconstruct the orbital floor, and collagen membranes have recently been suggested for the repair of isolated fractures of the orbital floor. However, their mechanical properties after modification with pores for increased drainage of blood into the sinus have not been sufficiently investigated. We have tested the mechanical resistance of polydioxanone foils (PDS) to distortion and compared it with that of 3 resorbable collagen membranes (Smartbrane(®), Bio-Gide(®), and Creos(®)) in mint condition and when artificially aged (3 weeks, 6 weeks, and 8 weeks) after modification with pores (diameter 2mm) in a standard configuration (n=12 in each group). PDS and Creos(®) had comparable initial values for mechanical resistance of about 2.3N/mm(2), and Bio-Gide(®) and Smartbrane(®) had about 20% and 80% lower initial mechanical resistance, respectively. All materials tested had lower values after artificial ageing. After eight weeks of ageing, PDS lost about 99% of its initial mechanical resistance, Creos(®) about 66%, Bio-Gide(®) about 30%, and Smartbrane(®) about 95%. After 3 weeks the mechanical resistance in all groups was significantly less than the initial values (p=0.05), but there was no difference between samples aged artificially for 6 compared with 8 weeks. The mechanical resistance of the tested materials was not influenced by the presence of pores in a standard configuration and was in the appropriate range for moderate fractures of the orbital floor. We recommend further clinical investigations of collagen membranes modified with pores.