Huiming Wang

Influence of Orthotropy on Biomechanics of Peri-Implant Bone in Complete Mandible Model with Full Dentition

Objective. The study was to investigate the impact of orthotropic material on the biomechanics of dental implant, based on a detailed mandible with high geometric and mechanical similarity. Materials and Methods. Multiple data sources were used to elaborate detailed biological structures and implant CAD models. In addition, an extended orthotropic material assignment methodology based on harmonic fields was used to handle the alveolar ridge region to generate compatible orthotropic fields. The influence of orthotropic material was compared with the commonly used isotropic model and simplified orthotropic model. Results. The simulation results showed that the values of stress and strain on the implant-bone interface almost increased in the orthotropic model compared to the isotropic case, especially for the cancellous bone. However, the local stress concentration was more obvious in the isotropic case compared to that in orthotropic case. The simple orthotropic model revealed irregular stress and strain distribution, compared to the isotropic model and the real orthotropic model. The influence of orthotropy was little on the implant, periodontal ligament, tooth enamel, and dentin. Conclusion. The orthotropic material has significant effect on stress and strain of implant-bone interface in the mandible, compared with the isotropic simulation. Real orthotropic mechanical properties of mandible should be emphasized in biomechanical studies of dental implants.

Release Behavior and Biological Activity of Recombinant Human Bone Morphogenetic Protein-2 from Porous PLGA Scaffold

The feasibility of using the poly-(DL-lactic-co-glycolic acid) (PLGA) scaffold as a carrier for controlled recombinant human bone morphogenetic protein-2 (rhBMP-2) delivery was assessed. PLGA rhBMP-2-loaded scaffolds were fabricated by emulsion polymerization and freeze-dried; a porous morphology was observed by scanning electron microscopy. The in vitro release of rhBMP-2 from the polymer was assessed using high performance liquid chromatography. An initial burst release of the incorporated rhBMP-2 was observed over the first 24h followed by an 80.6% sustained release for one month. The rhBMP-2-loaded scaffolds were implanted bilaterally into rat ectopic muscle pouches. The rhBMP-2 implanted animals showed bone formation submuscle space and osteoblasts located in the new bone region while none was seen in the control groups.

Medial Sural Artery Perforator Flap Aided by Ultrasonic Perforator Localization for Reconstruction After Oral Carcinoma Resection

PURPOSEnTo evaluate the application of the medial sural artery perforator flap (MSAPF) aided by preoperative ultrasonic perforator localization for postsurgical reconstruction of oral carcinoma.nnnMATERIALS AND METHODSnFrom November 2013 to August 2014, 25 patients with oral carcinoma underwent postsurgical reconstruction after oral carcinoma resection using MSAPFs. To explore and locate the perforators, preoperative vascular ultrasound localization was used to find the MSAPs. The number and location of the perforators, length of the vascular pedicle, and thickness of the MSAPF were measured. Thirty-eight patients who underwent reconstruction with a radial forearm flap (RFF) and 21 patients who underwent reconstruction with an anterolateral thigh flap (ALTF) were selected for comparison.nnnRESULTSnThe number of MSAPs ranged from 1 to 4, and 52 perforators were found accurately using preoperative ultrasonic localization (92.86%). The distance from the perforator to the popliteal crease ranged from 6.2 to 17.1xa0cm (10.70 ± 2.31xa0cm); the distance from the perforator to the midline of the back of the calf ranged from 0.1 to 3.5xa0cm (1.83 ± 0.81xa0cm); and the pedicle length ranged from 6.8 to 12.5xa0cm (10.14 ± 1.51xa0cm). Compared with the RFF, and ALTF, the thickness, postoperative oral sensation, and function of the MSAPF were similar to those of the RFF but better than those of the ALTF. In appearance and function of the donor site, the MSAPF was similar to the ALTF, but better than the RFF.nnnCONCLUSIONnThe MSAPF is a good alternative for postsurgical reconstruction of oral carcinoma because of its anatomic structural stability, suitable thickness, minimal donor-site scar, and ideal functional recovery after surgery. Preoperative vascular ultrasonic localization is a feasible and advantageous method for preoperative mapping of the MSAP because of its high accuracy.

Pedicled partial thickness clavicular graft for oromandibular reconstruction.

OBJECTIVEnTo report our experience on pedicled partial-thickness clavicular graft (PPCG) for oromandibular reconstruction.nnnSTUDY DESIGNnPPCG was used for oromandibular reconstruction after tumor resection in 23 patients with early-stage gingival carcinoma but were eager for postoperative dental implant therapy for restoration of good occlusal function. PPCG was harvested during neck dissection. The sternocleidomastoid (SCM) myocutaneous flap was also harvested in 18 cases. Dental implants were placed in the clavicular graft of 19 cases, and the other 4 declined because of financial concerns. Postoperative viability of the flaps and the dental implants were assessed.nnnRESULTSnAll the clavicular grafts survived without necrosis and implant-supported dentures of 19 patients provided satisfactory occlusion and masticatory function. Complications, although low in occurrence, included partial skin pedicle loss, nonunion between the clavicular graft and the remaining inferior border of the mandible, and clavicular bone fracture.nnnCONCLUSIONSnPPCG is a simple but reliable procedure for reconstruction of severe alveolar defects. Correct preoperative evaluation and precise surgical technique contribute to higher success rates and lower complication rates. It is a viable reconstructive option for early-stage gingival carcinoma requiring neck dissection without postoperative radiation therapy.

Chronological changes in the microstructure of bone during peri-implant healing: a microcomputed tomographic evaluation

Our objectives were to examine the titanium-bone interfaces chronologically and to clarify the process of osseointegration using microcomputed tomography (microCT). The mandibular premolars of 3 dogs were extracted and 12 weeks later 2 Straumann dental implants were installed in each quadrant. The microstructural changes at the bone-implant interface at the first, fourth, and eighth weeks after installation were evaluated by microCT and a 3-dimensional image was constructed. The microstructural measurements at the bone-implant interface, including the trabecular number (Tb.N), bone volume fraction (BV/TV), structure model index (SMI), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp) and connectivity density (Conn.D), were measured. Experimental outcomes were analysed for correlations between time and microstructural variables of trabecular bone. Tb.N increased significantly during the eighth week compared with that during the first and fourth week (p=0.001, 0.002). BV/TV increased generally with time and there were significant differences (p=0.003) between each time group. While Tb.Sp decreased with time and changed significantly during the eighth week compared with that during the first week (p=0.021), differences in SMI, Tb.Th and Conn.D did not differ significantly according to time of implant. The significant increase in the Tb.N and BV/TV during the eighth week after insertion of implants indicates that the formation of new bone before the eighth week is the key to osseointegration.

Use of the versatile sternocleidomastoid flap in oral and maxillofacial surgery: our experience.

Our aim was to evaluate the reliability of sternocleidomastoid (SCM) flaps in the reconstruction of defects after oral and maxillofacial resections, and summarise the ways in which morbidity can be reduced. We retrospectively enrolled 65 patients who had malignant tumours resected, and assessed the postoperative viability of the SCM flap. All complications were recorded during a follow up period of 1-64 months. We also investigated the relation between recurrence in regional lymph nodes and their preoperative histological state. The conventional SCM flap, the split SCM flap with only the sternal head, and the SCM flap with a half-thickness clavicular graft, were used to repair different defects. No flaps necrosed completely, and in only 5 cases was there partial loss of the skin paddle. The skin paddle avulsed in 2 cases 2 patients developed wound infections. Only 9 patients developed complications (14%, 9/65). Use of the split SCM flap overcomes the problem of bulk. The combination of the SCM flap and clavicular bone enables early dental implantation. The SCM flap is convenient, reliable, and technically easy for the reconstruction of intraoral or mandibular tissue loss. Preservation of the branch of the superior thyroid artery and precise surgical technique contribute to a higher success rate.

Utilization of a pre-bent plate-positioning surgical guide system in precise mandibular reconstruction with a free fibula flap

OBJECTIVESnWe evaluated the effects of three-dimensional virtual planning and the use of a plate-embedded surgical guide in mandibular reconstruction with microvascular fibula flaps.nnnMATERIALS AND METHODSnWe retrospectively reviewed 35 patients who underwent primary mandibular reconstruction with a free fibula flap. They were divided into three groups according to the therapy they received. In group A, 12 patients underwent reconstruction using the modified surgical guide system, including virtual surgeries, pre-bent titanium plates, screw-predesignated cutting guides for mandibular and fibular osteotomies, and plate-embedded shaping guides. In group B, 14 patients underwent reconstruction using the common surgical guide system, including virtual surgeries, cutting guides and pre-bent plates. In group C, 9 patients underwent reconstruction based on the surgeons experience. All cases were reviewed for the total operative time, ischemia time of the fibula flaps, accuracy of surgery, and postoperative complications.nnnRESULTSnAll of the fibula flaps survived. In group A, the ischemia time was shorter than that of groups B and C (Pu202f<u202f.05). The average gonion and condyle shift was lower in group A than in groups B and C (Pu202f<u202f.01).nnnCONCLUSIONSnApplication of the screw-predesignated and plate-embedded surgical guide system can reduce the ischemia time and operation time in mandibular reconstruction with a fibula flap, and can increase reconstruction accuracy. This method is a precise and highly reliable technique for improving the clinical outcome of mandibular reconstruction.

Less invasive management of deep neck infection and descending necrotizing mediastinitis: A single-center retrospective study

Abstract By a 7-year retrospective review, we reported our experience in management of descending necrotizing mediastinitis (DNM) and deep neck infection (DNI). A retrospective design was used to reveal the clinical characteristics of DNI and DNM. The clinical outcome was analyzed to validate less invasive management. We reviewed 82 patients between 2009 and 2016, 12 of which were diagnosed as DNM by clinical and computed tomography findings. A total of 35 patients had relevant systemic conditions, mainly diabetes mellitus (19 patients). Most cases were secondary to oropharyngeal or dental infections. All patients underwent transcervical drainage, and 10 DNM patients were treated with additional closed thoracic drainage simultaneously. Twenty patients accepted more than 1 operation. Seven patients died as a result of sepsis and/or multiple organ failure. The mortality rate in our study was similar to that in other studies. In our opinion, less invasive therapies are useful to most patients. Transcervical drainage alone is optimal management for all DNI cases and some DNM cases. Additional closed thoracic drainage is enough for type I and IIA DNM with pleural effusion or empyema.

Duplicated posterior belly of digastric muscle and absence of omohyoid muscle: a case report and review of literature

PurposeWe report a unique case of duplicated posterior belly of digastric muscle and absence of omohyoid muscle, review literatures and discuss its clinical importance.Materials and methodsAn abnormal strip of muscle was found during the routine functional neck dissection in a 58-year-old man, who suffered from moderately differentiated squamous cell carcinoma of right tongue. We check the anatomical features and search for similar variations in the past literatures.ResultsThe abnormal strip of muscle was attached to mastoid process, passed anteroinferiorly into the infrahyoid muscles. The muscle was as long as, but narrower than the posterior belly of the digastric muscle. So far, only one case of this anomaly was reported. Meanwhile, the omohyoid muscle was confirmed to be absent in the right neck of this patient.ConclusionsTo our knowledge, report of variations of both digastric muscle and omohyoid muscle, this variation mostly derives from abnormal development of the mesenchyme in the branchial arches. Attention should be paid to such variations, which might influence surgical procedures.

Clinical observation of single-tooth implant in the deficient anterior maxilla with intraoral bone grafts of thin periodontal biotype patients.

To the Editor: Implant rehabilitation in the esthetic zone of the anterior maxilla remains a challenge to clinicians due to high patient expectations for esthetics. A sufficient quantity and quality of bone is vital for esthetic success of implant restorations in the anterior maxillae. However, insufficient bone volume of the alveolar ridge, due to atrophy, trauma, and periodontal and endodontic diseases, is often present. To optimize esthetic implant placement into deficient ridges, additional bony augmentation procedures are required. Autogenous bone grafts are considered ‘‘the gold standard’’ due to their compatibility and osteogenic potentials to form new bone via osteogenesis, osteoinduction, and osteoconduction. Autogenous bone can be harvested from various sites that include iliac crest, calvarium, tibia, fibula, scapula, ribs, and oral cavity. Local bone defects requiring small grafts will most often receive grafts harvested from intraoral sites including the implant site, external oblique ridge, mandibular ramus, mental region, maxillary tuberosity, or the anterior nasal spine region. Autogenous block grafting from intraoral sources is a predicable technique for successful reconstruction of ridge defects. The main sources for this type of grafting are the mandibular symphysis/parasymphysis and ramus, which primarily provide a cortical graft and are characterized by a shorter healing period, maintenance of osseous density, rare complications, and no cutaneous scar. In addition, intramembranous bone from the mandibular symphysis and ramus undergoes less resorption than endochondral bone: these procedures can be accomplished on an outpatient basis under regional anesthesia. The term ‘‘periodontal biotype’’ was introduced by Seibert and Lindhe to describe the thickness of the gingiva in the buccolingual dimension as being either thick or thin. The periodontal biotype of teeth may have an effect on the esthetic features of the grafted site. A number of studies have suggested that teeth with a thin biotype are at higher risk for tissue recession. A thin biotype could be especially prone to substantial ridge volume loss, resulting in a challenge for the placement of implants and esthetic outcomes. The purpose of this retrospective study was to evaluate the success and esthetic outcomes of dental implants placed into the anterior region after intraoral block grafts in patients with a thin periodontal biotype. PATIENTS AND METHODS Patients