Chuanchang Dai

Prolonging the duration of masseter muscle reduction by adjusting the masticatory movements after the treatment of masseter muscle hypertrophy with botulinum toxin type a injection.

BACKGROUND Botulinum toxin type A (BTX-A) is widely used for the clinical treatment of masseteric hypertrophy. Until now, few reports have discussed how to prolong the duration of its effectiveness. OBJECTIVE This study evaluated that purposely adjusting the masticatory movements is possible of postponing the masseter muscle rehypertrophy. METHODS Ninety-eight patients were randomly and equally divided into 2 groups, and 35 U BTX-A per side was injected into the masseters. The thickness and volume of the masticatory muscles were measured by ultrasound and computerized tomography, respectively. Patients in Group 1 were instructed to strengthen their masticatory effort during the denervated atrophic stage of the masseter (the interval was evaluated by real-time ultrasound monitoring), whereas patients in Group 2 were not given this instruction. When the masseter muscle began to recover, patients in both groups were instructed to reduce their chewing. RESULTS The duration of the masseter muscle rehypertrophy was significantly prolonged in Group 1 patients. The thickness and the volume of the other masticatory muscles were significantly increased in Group 1 but were either slightly decreased or insignificantly different in Group 2. CONCLUSION Purposely strengthening masticatory muscle movement during the denervated atrophic stage of the masseter can prolong the duration of masseter rehypertrophy.

Reconstruction of through-and-through facial defects with combined anterior tibial flap and dorsalis pedis flap.

Abstract Through-and-through facial defects can be the result of malignancy, malformations, or trauma and pose a challenge for reconstructive surgeons. An ideal reconstruction of such defects should restore both lining and external skin defects at the same time. In this report, we describe the use of combined anterior tibial flap and dorsalis pedis flap to reconstruct complex facial defects. Six patients who presented with through-and-through facial defects were included. The cause of defects were trauma, radiotherapy, or flap necrosis, and defect locations were the buccal (3 patients), oral region (2 patients), and frontal (1 patient). The outer defects were between 5 × 6 cm and 13 × 9 cm, whereas the inner defects were between 3 × 3 cm and 5 × 6 cm. The anterior tibial flaps that were used to cover the outer defects ranged from 5 × 8 cm to 10 × 15 cm, and the dorsalis pedis flaps that were used to reconstruct the lining ranged from 3 × 4 cm to 6 × 8 cm. Donor sites were covered with skin grafts. No flap failure was evident, and a good aesthetic outcome was obtained in all cases. In 1 patient, the skin graft on the dorsal pedis presented partial necrosis and ultimately healed by dressing change. Compared with other techniques, the combined anterior tibial flap and dorsalis pedis flap possesses the potential benefits of being thin and pliable and having reliable vascularity. It brings a new alternative method for complex facial defect reconstruction.

The Role of Cell Seeding, Bioscaffolds, and the In Vivo Microenvironment in the Guided Generation of Osteochondral Composite Tissue

Tissue engineering based on cell seeding, bioscaffolds, and growth factors has been widely applied for the reconstruction of tissue defects. Recent progress has fueled in vivo tissue engineering techniques in becoming hot topics in regenerative medicine and reconstructive surgery. To improve the efficacy of tissue engineering, we here investigated the roles of cell seeding, bioscaffolds, growth factors, and in vivo microenvironment (IM) in tissue regeneration. Bone marrow-derived stem cells, allogeneic demineralized bone matrix as bioscaffold, and growth factor bone morphogenetic protein 2/transforming growth factor, and the IM of rib periosteum and perichondrium were used in different combinations for the generation of osteochondral composite tissue. Self-regenerated neocomposite tissue based on the IM alone exhibited excellent anatomical configuration, vascularization, biomechanical stability, and function similar to native controls. Our findings indicate that the IM is a crucial factor in biofunctional tissue generation. Further refinement and development of this technique may enable transfer to clinical application with broad spectrum of application.

Bone morphogenetic protein receptor IB as a marker for enrichment of osteogenic precursor-like cells in human dermis

The scarcity of bone marrow mesenchymal stromal cells (BMSCs) prompts the search for alternative sources for cell-based bone defects repair. Human dermal fibroblasts (FBs) have been shown to have a high proliferative potential and the capacity to differentiate into an osteogenic phenotype. The easy and repeated harvest in large quantities makes this cell source a potential candidate for bone tissue engineering. The aim of our study was to compare directly the immune phenotype, proliferative capacity and osteogenic differentiation potential of FBs with that of “gold standard” BMSCs or adipose-derived mesenchymal stromal cells (ADSCs), another alternative osteoprogenitor cell source. Flow cytometry demonstrated that FBs, ADSCs and BMSCs shared common cell surface marker protein expression profiles when using a panel of surface antigens. FBs had the highest proliferative potential, but lowest osteogenic differentiation potential in vitro, compared with ADSCs or BMSCs. More importantly, BMPR-IB+-sorted FBs subpopulation had a higher osteogenic differentiation potential than BMPR-IB−-sorted FBs subpopulation. Our results indicated that the heterogeneous FBs were not an appropriate cell source for bone tissue engineering. Immunoselection by BMPR-IB can generate highly purified osteogenic precursor-like cells in the human dermis.

Double Composite Tissue Z-plasty Technique for Anatomical Restoration of Severe Nasal Deformity in Secondary Unilateral Cleft Lip.

Background Patients with secondary unilateral cleft lip are regularly affected by serious nasal deformities especially of the alar and nasal floor. A large number of techniques for correction have been published, but symmetrical restoration of severe nasal deformation is difficult to achieve. We propose an innovative approach for anatomical restoration for this entity of nasal deformities to achieve long-term symmetrical appearance and muscular function. Methods A total of 68 patients with severe nasal deformity due to secondary unilateral cleft lip underwent reconstructive surgery using a double composite tissue Z-plasty technique for anatomical restoration of cartilage, muscle, and soft tissue layers. Patient pictures were taken preoperatively and postoperatively to evaluate appearance and incisional wound healing. The surgical outcome was assessed based on a postoperative patient satisfaction survey. All occurring adverse effects were recorded. Results All patients were followed up for at least 7 months up to 8 years; mean follow-up period was 14.6 months. Patients were highly satisfied with the aesthetic result and improved facial profile (97.1%) and healing of the incision site (94.1%). There were 4 cases of implant deviation and 2 cases of impaired ventilation due to hypertrophic scarring of the upper lip (2 patients) and relatively decreased nostril size after augmentation rhinoplasty (1 patient), respectively, requiring surgical revision 1 year postoperatively. No other complications such as bleeding, infection, flap necrosis, and sensory dysfunction were recorded. Conclusions The double composite tissue Z-plasty technique allows for thorough anatomical restoration of cartilage, muscle, and skin layers in unilateral cleft lip nasal deformities. This single-step approach is a safe and technically easy therapeutic option that is associated with high patient satisfaction and acceptance.

Autologous temporomandibular joint reconstruction independent of exogenous additives: a proof-of-concept study for guided self-generation

Joint defects are complex and difficult to reconstruct. By exploiting the body’s own regenerative capacity, we aimed to individually generate anatomically precise neo-tissue constructs for autologous joint reconstruction without using any exogenous additives. In a goat model, CT scans of the mandibular condyle including articular surface and a large portion of the ascending ramus were processed using computer-aided design and manufacturing. A corresponding hydroxylapatite negative mold was printed in 3D and temporarily embedded into the transition zone of costal periosteum and perichondrium. A demineralized bone matrix scaffold implanted on the contralateral side served as control. Neo-tissue constructs obtained by guided self-generation exhibited accurate configuration, robust vascularization, biomechanical stability, and function. After autologous replacement surgery, the constructs showed stable results with similar anatomical, histological, and functional findings compared to native controls. Further studies are required to assess long-term outcome and possible extensions to other further applications. The absence of exogenous cells, growth factors, and scaffolds may facilitate clinical translation of this approach.

Guided Self-Generation of Vascularized Neo-Bone for Autologous Reconstruction of Large Mandibular Defects.

AbstractReconstruction of large mandibular defects is complex and challenging. The authors aimed to individually self-generate a large vascularized bone construct for autologous transplantation without the use of exogenous additives based on the concept of guided self-generation. Using computer-aided design and manufacturing a large size goat mandibular bone was reconstructed in 3 dimensions. Its negative mold printed from hydroxylapatite was temporarily embedded into the costal periosteum along with a contralateral demineralized bone matrix scaffold as control. After 3 months, a mandibular bone construct was obtained and used for autologous transplantation. Osteogenesis and angiogenesis were assessed by real-time imaging, histology, and biomechanical tests during neo-bone formation and up to 6 months after transplantation surgery. A total of 20 animals received implantation of a mandibular bone negative mold along with a contralateral demineralized bone matrix scaffold. Resulting negative mold mandibular bone constructs showed anatomically, histologically, and functionally similar characteristics compared with native controls. Only 1 goat presented partial fibrosis during construct generation with subsequent absorbtion after reconstruction. The absence of exogenous cells, growth factors, and scaffolds facilitated direct translation of this novel concept into clinical application. Further studies are needed to determine functional long-term outcomes and possible extensions to other tissues and organs.

Correction of Midface Depression Using an Inverted m-shaped Expanded Polytetrafluoroethylene Implant Improves Gingival Exposure.

BackgroundCurrent approaches for the treatment of gingival exposure are often time- and cost-consuming and/or rather invasive. We previously observed a strong correlation between the presence of gingival excess and midfacial depression and here propose an easy 1-step correction technique as a new strategy to improve gingival exposure. MethodFrom February 2004 to December 2012, 42 patients with gingival exposure associated with different degrees of midfacial depression, defined by Frankfort horizontal plane-labrale superius-subspinale angle and sella-nasion-A point angle, were treated by implantation of an inverted m-shaped expanded polytetrafluoroethylene at the base of the piriform aperture in a subperiosteal location. Patient pictures were taken preoperatively and postoperatively to assess gingival exposure at rest and fullest smile, as well as measurements of upper lip length, nasolabial angle, and facial convexity angle. A postoperative patient satisfaction survey was performed. ResultsThe average maximum gingival exposure was 5.52 ± 1.64 mm preoperatively and significantly decreased to 1.79 ± 0.67 mm at 6 months after surgery (P < 0.05) along with a significantly improved nasolabial angle from initially 85.3° ± 6.21° to 95.2° ± 7.1° (P < 0.05). The majority of patients (90.5%) rated their postoperative outcome as highly improved and improved. Temporary discomfort involving upper lip numbness, foreign body sensation, and stiff smiling expression was complained at 1 month postoperatively and gradually returned to normal after 3 months. No late recurrence or other complications were seen in any of the patients. ConclusionsFor cases involving midface depression, the present technique provides an effective and permanent treatment strategy to improve excessive gingival exposure. This single-step approach is a safe and technically easy therapeutic option which is associated with high patient acceptance.