Zu-Bing Li

Aetiology, pattern and treatment of mandibular condylar fractures in 549 patients: A 22-year retrospective study

PURPOSE The purpose of this study was to retrospectively investigate the aetiology, pattern, and treatment of mandibular condylar fractures in our department over the past 22 years. PATIENTS AND METHODS Data of patients who sustained mandibular condylar fractures from 1988 to 2009 were recorded, including fracture aetiology, pattern of condylar fracture, time, age, sex, associated injury, patient transferred by other clinics, lag time and treatment method. Data analysis included X(2) test, Fisher exact test, t-test, Ridit analysis and Logistic regression analysis. RESULTS The sample was composed of 549 patients (749 condylar fractures), 404 male and 145 female (male:female = 2.79:1), with a mean age of 30.12 ± 14.44 years. Road traffic accidents were the most common cause (248, 45.2%). Condylar head fractures were significantly related to a fall at ground level (p = .001). A fall from a height had a 3.19-fold risk of bilateral condylar fractures (odds ratio, 3.19; 95% confidence interval, 1.33 to 7.65; p = .010). A majority of the condylar fractures (693, 92.5%) were treated by a surgical procedure. Condylar head were mostly removed (95.0%, p < .001), condylar neck and condylar base fractures were most frequently treated by open reduction and internal fixation with miniplates (74.4%, p < .001). Most of the dislocated condylar fractures were treated by open surgery (96.5%, p = .026). CONCLUSIONS The anatomic position and uni/bilateral pattern of mandibular condylar fractures were positively related to situations when considerable force is involved. Open condylar surgery was based on the level of fracture and degree of displacement or dislocation.

Repair of mandible defect with tissue engineering bone in rabbits.

Background:  The aim of the present study was to investigate the effect of tissue engineering bone composed of bone marrow‐derived osteoblasts and demineralized bone in repairing mandible defect.

Effects of intermittent versus continuous parathyroid hormone administration on condylar chondrocyte proliferation and differentiation.

Endochondral ossification is a complex process involving chondrogenesis and osteogenesis regulated by many hormones and growth factors. Parathyroid hormone (PTH), one of the key hormones regulating bone metabolism, promotes osteoblast differentiation and osteogenesis by intermittent administration, whereas continuous PTH administration inhibits bone formation. However, the effects of PTH on chondrocyte proliferation and differentiation are still unclear. In this study, intermittent PTH administration presented enhanced effects on condylar chondrocyte differentiation and bone formation, as demonstrated by increased mineral nodule formation and alkaline phosphatase (ALP) activity, up-regulated runt-related transcription factor 2 (RUNX2), ALP, collagen type X (COL10a1), collagen type I (COL1a1), osteocalcin (OCN), bone sialoprotein (BSP), bone morphogenetic protein 2 (BMP2) and osterix (OSX) mRNA and/or protein expression. On the contrary, continuous PTH administration promoted condylar chondrocyte proliferation and suppressed its differentiation, as demonstrated by up-regulated collagen type II (COL2a1) mRNA expression, reduced mineral nodule formation and down-regulated expression of the mRNAs and/or proteins mentioned above. Our data suggest that PTH can regulate condylar chondrocyte proliferation and differentiation, depending on the type of PTH administration. These results provide new insight into the effects of PTH on condylar chondrocytes and new evidence for using local PTH administration to cure mandibular asymmetry.

Dental trauma in patients with maxillofacial fractures

PURPOSE The purpose of this study was to analyze and evaluate the correlation between dental injuries and the pattern of maxillofacial fractures. The correlation with age, gender, trauma mechanism and type of maxillofacial fracture was also investigated. MATERIALS AND METHODS From January 2000 to December 2009, 1131 patients with facial fractures were registered. Of these, 473 presented with associated dental trauma. The information and data collected and analyzed included: age, gender, mechanism of injury, type of facial fracture, type of dental injury, and the relationship between dental injury and facial fracture. RESULTS Dental injury was sustained by 473 patients (41.8%), with a total of 2215 injured teeth. Of the 2215 injured teeth, 1191 (53.8%) were in the maxilla and 1024 (46.2%) in the mandible. Fall from a height had the highest risk of dental injuries (OR = 4.145, P = 0.002). The central incisor was the most injured tooth for both the maxilla (388, 36.2%) and mandible (284, 27.7%). The most common type of dental injury was avulsion (1070, 47.4%). More anterior teeth in the maxilla were of crown fracture, avulsion, and intrusion than that in the mandible, whereas more anterior teeth in the mandible were of subluxation and concussion than that in the maxilla. Dental injuries were more prone to occur in patients who sustained only symphysis fractures (OR = 2.817, P < 0.001), only 0.236-fold risk in patients who sustained only mandible angle fracture (P < 0.001). CONCLUSIONS The occurrence of dental trauma is significantly related to the pattern and position of the maxillofacial fractures.

Mechanism in favorable prognosis of pediatric condylar fractures managed by closed procedures: an experimental study in growing rats

The purpose of this study was to investigate the underlying mechanism in favorable prognosis following pediatric condylar fractures managed by closed procedures. Seventy-five 1-month-old male Wistar rats were used in this experiment. Unilateral medially rotated condyle fracture in growing rats was adopted as the condyle fracture model to investigate the mechanism in favorable healing of pediatric condylar fractures. The entire fracture healing process was investigated. The rotated subcondylar fractures in young rats healed by means of callus formation, with simultaneous and prompt repositioning of the condyle. The positive outcome in these condyle fractures was also associated with active cell proliferation potential in the condyle, as well as the condyles remodeling capability. The growth potential and remodeling capability of the condyle during the growing period might be the intrinsic factor for favorable healing following pediatric condylar fractures managed by closed procedures.

Incidence and pattern of maxillofacial fractures in children and adolescents: A 10 years retrospective cohort study

OBJECTIVE The purpose of this study was to evaluate and compare the demographic characteristics of maxillofacial fractures between children and adolescents. METHODS The sample was composed of all children (less than 12 years) and adolescents (between 13 and 18 years old) who presented with maxillofacial fractures during a 10-year period (2000-2009). The age, gender, time of injury, mechanism of trauma, location and pattern of fracture, associated injuries, and treatment methods were recorded and analyzed. Data analysis included Chi-Square test, Fisher exact test. p less than 0.05 was considered significant. RESULTS Seventy-nine children (male-to-female ratio, 1.63:1) and 113 adolescents (male-to-female ratio, 3.52:1) sustained 389 maxillofacial fractures. Children were more involved in falls compared to adolescents (44.3% versus 23.9%, p=0.003), while adolescents sustained more assault-related injuries (13.3% versus 2.5%, p=0.010) and motorcycle accidents (22.1% versus 8.9%, p=0.015) compared to children. Children suffered mandibular fractures proportionally higher than adolescents (93.1% versus 64.5%, p<0.001). Adolescents sustained mid-facial fractures more frequently than children (35.5% versus 6.9%, p<0.001). Severe facial fractures occurred more in adolescents compared to children (35.4% versus 14.1%, p=0.001). Open reduction was done more in adolescents than in children (92.3% versus 74.6%, p<0.001). CONCLUSIONS The incidence and pattern of maxillofacial fractures in children were remarkably different from that in adolescents. Preventive measures and treatment plan should be designed with differences between the two groups in mind.

Changing pattern in the characteristics of maxillofacial fractures.

PurposeThis study was designed to assess the changes in the etiology, incidence, and pattern of maxillofacial fractures during 2 different study periods in our department. Patients and MethodsIn this retrospective study, patients treated for maxillofacial fractures at our department from January 2000 to December 2009 were included. Data regarding patient’s age, sex, etiology of fracture, time of injury, site of fracture, and pattern of fracture were collected and grouped chronologically into two 5-year periods: 2000 to 2004 (period 1) and 2005 to 2009 (period 2); the results of the study during these periods were analyzed and compared. ResultsA total of 1131 patients sustained maxillofacial fractures: 422 in the first period and 709 in the second period. During the second period, the male–female ratio increased from 3.35:1 to 3.63:1. Road traffic accidents remained the major etiologic factor, which increased remarkably from 49.3% to 54.6% (P = 0.085), whereas assault-related injuries decreased significantly from 16.8% to 12.4% (P = 0.039). The proportion of patients with mandibular fractures decreased from 59.6% to 55.3% (P = 0.037), whereas the proportion of patients with midfacial fractures increased from 40.4% to 44.7% (P = 0.037). ConclusionsThe changing pattern of maxillofacial fractures in our center is correlated to the socioeconomic status, population mobility, and etiologic factors. Strict enforcement of traffic laws and regulations is still a focal factor in attaining appreciable reduction in maxillofacial fractures associated with road traffic accidents.

The role of the disc in the healing of displaced subcondylar fracture in the growing period: an experimental study in rats

The purpose of this study was to evaluate the role of the disc in the healing of condylar fractures in the growing period. 40 growing and adult male Wistar rats were randomized into 4 equal groups: growing rats suffering condylar fracture with disc damage; growing rats suffering condylar fracture without disc damage; adult rats suffering condylar fracture with disc damage; adult rats suffering condylar fracture without disc damage. 3 months after the operation all animals were killed and the outcomes were compared using mandible deviation measure, body weight evaluation and histological observation. In growing rats, when the disc was undamaged maintaining its relation to the condyle head, even though the condylar fractured fragment was displaced, the condyle healed and recovered almost to normality in 3 months. In the same condyle fracture form, once the disc was damaged and lost the normal relation with the condyle head, the outcome was unfavourable. The occurrence of damage to the disc and its attachment to the condyle head are important factors in the healing of condyle fractures in the growing period.

Autophagy Prior to Chondrocyte Cell Death During the Degeneration of Meckel's Cartilage

The central portion of Meckels cartilage degenerates almost immediately after birth. Whether autophagy is involved in this process remains unclear. Thus, to explore the role of autophagy during this process, we have detected the expression of autophagy and apoptosis‐related markers in embryonic mice. In E15, Beclin1 and LC3 expressions were weak and negative in Meckels cartilage, respectively. In E16, chondrocytes of the central portion became hypertrophic. Moderate immunoreactivities of Beclin1 and LC3 were observed in prehypertrophic and hypertrophic chondrocytes of the central portion. In E17, the degradation occurred in the central portion and expanded anteriorly and posteriorly. Beclin1 expression was observed in Meckels cartilage with an increase in the hypertrophic chondrocytes of the central portion. The expression of LC3 was detected specifically in terminally differentiated hypertrophic chondrocytes. The mRNA expressions of LC3 and Beclin1 from E15 to E17 significantly increased. This result is in accord with the histologic findings. Terminal deoxynucleotidyltransferase‐mediated dUTP‐biotin nick‐end labeling assay and Caspase 3 expression demonstrated that apoptosis was detected in the lateral part of terminal hypertrophic chondrocytes along the degeneration area of Meckels cartilage. In addition, Bcl2 expression increased significantly from E15 to E17. These results indicate that autophagy is involved in hypertrophic chondrocytes during the degradation of Meckels cartilage and occurs prior to chondrocyte cell death during this process. Anat Rec, 2012.

Induction of traumatic temporomandibular joint ankylosis in growing rats: a preliminary experimental study.

There are many reports on the management of pediatric temporomandibular joint (TMJ) ankylosis. However, few authors have investigated the etiology of this disease in children. The purpose of this study was to determine the role of damage to both the condylar cartilage and disk in the induction of traumatic TMJ ankylosis during the growth period. The study was performed in growing rats by a common condyle fracture model. Intentional damage was performed to both the disk and condylar cartilage in the experimental group (n = 12), while the disk and condylar cartilage in the control group was left untouched (n = 12). Sham-operated growing rats were deemed the blank group (n = 10). Two rats from the experimental group and two from the control group were killed 24 h after the operation, and the result following surgical intervention was observed. Each rats body weight in the three groups was monitored and recorded at 1, 2, 4, 6, 8, 10, and 12 weeks after surgery. Twelve weeks after the operation, all animals were killed. The prognosis was compared by mandible deviation measure, body weight evaluation, and histological observation. Animals from the experimental group presented a slow body weight increase and obvious mandible deviation while all involved TMJs showed fibrous ankylosis in various degrees. The damage to both the condylar cartilage and disk in the condylar fracture might play a vital role in traumatic TMJ ankylosis development during the growth period. The results of this study suggest that more attention should be paid to condylar fractures in children that are accompanied with severe cartilage and disk damage, which is a matter of significance for pediatric TMJ ankylosis prevention.