Long-Term Outcomes of Zygomaticomaxillary Reconstruction With Autologous Bone Grafts Supported by Pedicled Buccal Fat Pad Flap.

PURPOSE: The purpose of this study was to investigate the effectiveness of the pedicle buccal fat pad flap combined with autogenous bone grafts to reconstruct zygomaticomaxillary defects after tumor resection. MATERIALS AND METHODS: A retrospective case series analysis of 11 patients that underwent zygomaticomaxillary reconstruction after tumor resection with autologous bone grafts supported by pedicle buccal fat pad flap as the lining of the maxillary sinus from January 2009 to December 2015 was performed. All the patients underwent computed tomography to measure the aesthetic appearance, bone graft formation, mucosa of the maxillary sinus, and their response to treatment, including complications. RESULTS: With a mean follow-up period of 4.7 years, all patients were pleased with the symmetrical contours of zygomaticomaxillary and symptom improvements of the maxillary sinus except for one patient who complained of transient infraorbital numbness. Recurrence, bone infection or necrosis, and other complications were not observed in the follow-up period. CONCLUSION: Pedicled buccal fat pad flap promotes wound healing and prevents the exposure of bone grafts to the maxillary sinus. This technique may be a promising treatment option when reconstructing complicated zygomaticomaxillary defects.

Growth pattern and physiological characteristics of the temporomandibular joint studied by histological analysis and static mechanical pressure loading testing.

OBJECTIVE: The aim of this study was to investigate the age-related changes in the articular disc, condyle, condylar fibrocartilage, and subchondral bone of the temporomandibular joint (TMJ) in rabbits. METHODS: Female New Zealand white rabbit aged 1, 4, 12, and 32 weeks were obtained. Each age group comprised 5 rabbits and was subjected to chondrocyte culture, histological assessment of the articular disc length, assessment of the anteroposterior diameter of the condyle, measurement of the fibrocartilage thickness, and assessment of the subchondral bone architecture. The production of Collagen, type II, alpha1 (COL2A1); SOX9; Collagen, type X, alpha1 (COL10A1); and Runt-related transcription factor 2 (Runx2) was detected via western blot. Six rabbits at the ages of 12 and 32 weeks were sacrificed for the mechanical pressure loading test (75 kPa, 3 days). Changes in the condyles after pressurization were observed via scanning electron microscopy and evaluated by micro-CT. RESULTS: Significant enlargement of the condyle occurred from 4 to 12 weeks of age (p = 0.003); however, the length of the articular disc increased significantly from 1 to 12 weeks of age (p < 0.005). A rapid decrease in the cartilage thickness but an increase in the subchondral bone density occurred from 1 to 4 weeks of age and from 4 to 32 weeks of age in rabbit, respectively (p < 0.05). The expressions of COL2A1 and SOX9 gradually decreased from 1 to 32 weeks of age. The protein expressions of COL10A1 and Runx2 were maintained at a high level at 4-12 weeks of age. After static mechanical pressure loading, the damage and reduction in the bone mineral density (BMD) in the12-week-old group was greater than those in the 32-week-old group. CONCLUSIONS: An inconsistency between the condyle and articular disc during growth and development may be a causal factor for temporomandibular disorders TMDs in adolescents. Our findings suggest that the response of the adult condyle to the mechanical pressure is significantly greater than that of the adolescent condyle; however, with regard to reconstruction, the situation is reversed, which may influence the pathological progress of TMDs.

Study on the effects of gradient mechanical pressures on the proliferation, apoptosis, chondrogenesis and hypertrophy of mandibular condylar chondrocytes in vitro.

OBJECTIVE: To investigate the effects of gradient mechanical pressure on chondrocyte proliferation, apoptosis, and the expression of markers of chondrogenesis and chondrocyte hypertrophy. METHODS: Mandibular condylar chondrocytes from 5 rabbits were cultured in vitro, and pressed with static pressures of 50kPa, 100kPa, 150kPa and 200kPa for 3h, respectively. The chondrocytes cultured without pressure (0kPa) were used as control. Cell proliferation, apoptosis, and the expression of aggrecan (AGG), collagen II (COL2), collagen X (COL10), alkaline phosphatase (ALP) were investigated. Ultrastructures of the pressurized chondrocytes under transmission electron microscopy (TEM) were observed. RESULTS: Chondrocyte proliferation increased at 100kPa and decreased at 200kPa. Chondrocyte apoptosis increased with peak pressure at 200kPa in a dose-dependent manner. Chondrocyte necrosis increased at 200kPa. The expression of AGG increased at 200kPa. The expression of COL2 decreased at 50kPa and increased at 150kPa. The expression of COL10 and ALP increased at 150kPa. Ultrastructure of the pressurized chondrocytes under TEM showed: at 100kPa, cells were enlarged with less cellular microvillus and a bigger nucleus; at 200kPa, cells shrank with the sign of apoptosis, and apoptosis cells were found. CONCLUSIONS: The mechanical loading of 150kPa is the moderate pressure for chondrocyte: cell proliferation and apoptosis is balanced, necrosis is reduced, and chondrogenesis and chondrocyte hypertrophy are promoted. When the pressure is lower, chondrogenesis and chondrocyte hypertrophy are inhibited. At 200kPa, degeneration of cartilage is implied.

Multi-Space Infections in the Head and Neck: Do Underlying Systemic Diseases Have a Predictive Role in Life-Threatening Complications?

PURPOSE: To assess the incidence, risk factors, treatment, and outcomes of life-threatening complications of multi-space infections (LCMIs) in the head and neck. PATIENTS AND METHODS: This was a retrospective cohort study that enrolled a sample of patients with multi-space infections who were referred from February 2006 through July 2014. The patients were classified into LCMI and non-LCMI groups. The primary predictor in this study was underlying systemic disease. The primary outcome variable was LCMI. Univariate analyses were used for data statistics. RESULTS: A total of 549 patients were included, and an LCMI was found in 66 patients (12.20%). Descending mediastinitis was the most frequent LCMI (n = 37; 56.06%), followed by airway obstruction (n = 27; 40.91%), pneumonia (n = 12; 18.18%), pericarditis (n = 6; 9.09%), intraorbital infection (n = 2; 3.03%), multiple organ failure (n = 2; 3.03%), intracranial infection (n = 2; 3.03%), and sudden cardiac death (n = 1; 1.52%). Twelve patients with LCMI died during treatment. Elderly patients with an underlying systemic disease more commonly developed an LCMI. CONCLUSIONS: Multi-space infections in the head and neck can cause several life-threatening complications, and the morbidity of LCMI is considerable. Older age and underlying systemic disease can increase the risk of an LCMI.

The effects of static pressure on chondrogenic and osteogenic differentiation in condylar chondrocytes from temporomandibular joint.

OBJECTIVE: The goal of the study was to investigate the production of collagen, type II, alpha 1 (COL2A1), SOX9, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), Indian hedgehog (Ihh), and periarticular cell-derived parathyroid hormone-related protein (PTHrP) in mandibular condylar chondrocytes under static pressure stimuli. METHODS: Mandibular condylar chondrocytes separated from rabbit temporomandibular joint (TMJ) were treated with a static pressure of 100kPa for 0, 1, 2, 3, and 4h by an in-house-designed pressure chamber. A CCK-8 kit was used to analyze the cell viability. The production of COL2A1, SOX9, ALP, Runx2, Ihh, and PTHrP was detected by Western blot or real-time polymerase chain reaction (PCR). Changes in cell morphology were observed by scanning electron microscopy. RESULTS: Compared with the control group (0h), the cytoplasmic processes of treated chondrocytes obviously increased and elongated, and the cell viability of pressurized chondrocytes were 91.13% (1h), 103.41% (2h), 103.47% (3h), and 104.94% (4h), respectively. The exposure of condylar chondrocytes to a static pressure of 100kPa for 3-4h resulted in a significant increase in COL2A1, SOX9, ALP, and Runx2. After a static pressure loading of 100kPa, the activation of Ihh and PTHrP was also observed. CONCLUSIONS: Mandibular condylar chondrocytes adapt to alterations of the microenvironment. Ihh and PTHrP are sensitive to static pressure. Our findings suggest that static pressure accelerated the chondrogenic and osteogenic differentiation of condylar chondrocytes, which may influence the pathological progress of temporomandibular diseases.

Disc positions and condylar changes induced by different stretching forces in the model for anterior disc displacement of temporomandibular joint.

OBJECTIVE: The aim of this study was to compare the disc positions and condylar changes induced by different stretching forces in the modified animal model for anterior disc displacement (ADD) of the temporomandibular joint. METHODS: In the experimental group, 30 rabbits were equally divided into 3 subgroups and underwent surgical ADD via different stretching forces: group A with 0.5 N, group B with 1 N, and group C with 2 N. In the sham group, 6 rabbits underwent the same surgery without the disc being pulled anteriorly. The diagnosis of ADD was made when the anterior band of the disc was located anteriorly to the articular eminence. Histologic and radiographic changes of the condyles were observed under light microscopy and micro-computed tomography scanning 1 week after surgery. RESULTS: The success rates of ADD were both 100% in groups B and C and 70% in group A. The correlations between the stretching force and severity of ADD, the stretching force and severity of cartilage changes, and the severity of ADD and cartilage changes were statistically significant (P < 0.01). The most advanced ADD and severest condylar changes were induced in group C. Condylar remodeling and scleroses were found in micro-computed tomography scans. CONCLUSIONS: The rabbit model for ADD has been successfully established in this study, which is feasible and minimally invasive. The stretching force of at least 1 N could induce the disc displaced successfully. Larger stretching force would induce severer ADD and condylar degenerative changes.

Ruptured disc after arthroscopic repositioning in the temporomandibular joint: a retrospective magnetic resonance imaging study.

Our aim was to explore the incidence of rupture after arthroscopic repositioning of the disc of the temporomandibular joint (TMJ) by reviewing magnetic resonance images (MRI) of the TMJ taken before and after operation, and to investigate correlations retrospectively. We studied 247 patients with anterior disc displacement of the TMJ, and categorised them into 3 groups based on the postoperative MRI. The first group comprised those whose disc ruptured after repositioning, the second those who had a possible rupture of the disc after repositioning, and the third had no rupture of the disc after repositioning. Age, sex, duration of symptoms, maximum incisal mouth opening, whether the anterior disc displacement was unilateral or bilateral, and the Wilkes stage, were included in the analysis. The incidence of rupture (5/247) was 2%. Weak points at the intermediate zone of the disc were found in 4 of the 5 joints. The patients whose discs ruptured were significantly younger than the other 2 groups (p=0.001). There was no statistically significant difference in preoperative duration of symptoms and mouth opening among the groups. The proportions of unilateral and bilateral disc displacement (p=0.047) and Wilkes stage (p=0.027) differed among the 3 groups. The Wilkes stages was significantly more advanced in the ruptured group than in the other 2 groups (p=0.027) with 4/5 being bilateral. The weak point in the intermediate zone of the disc on MRI could be a sign of rupture. Teenagers and young adults with anterior disc displacement without reduction, particularly those in whom it is bilateral, are at a higher risk of a rupture after repositioning of the disc by arthroscopy.