Expression form of p53 and PCNA at the invasive front in oral squamous cell carcinoma: correlation with clinicopathological features and prognosis.

BACKGROUND: Abnormalities in cell-cycle-controlling genes are important in the malignant transformation and proliferation of tumors. Among these genes, the tumor suppressor gene p53 is the most notable, and its mutations provide an indicator of tumor progression and prognosis. Proliferating cell nuclear antigen (PCNA) is a highly conserved nuclear protein that is expressed during cell replication and DNA repair. This study examined the expression of p53 and PCNA at the invasive front of oral squamous cell carcinomas (OSCC) by immunohistochemical staining, and investigated the relationship of these proteins to clinicopathological findings and prognosis. METHODS: Fifty-nine biopsy cases of OSCC were examined by immunohistochemical staining. Clinicopathological data were gathered and patient survival was analyzed. RESULTS: The p53 labeling index (p53-LI) and PCNA labeling index (PCNA-LI) were examined at the invasive front of the tumors. A high p53-LI (p53+) was observed in 17 of the 59 cases (28.8%) and a high PCNA-LI (PCNA+) was observed in 28 of the 59 cases (47.5%). Among the modes of cancer invasion, many of the p53+/PCNA+ cases could be confirmed as highly invasive cancer (P < 0.05). In addition, the p53+/PCNA+ cases showed a high risk of tumor recurrence compared with the other expression forms, and patients with p53+/PCNA+ had a worse prognosis than those with the other expression forms. High labeling indices of p53 and PCNA are associated with poor prognosis in patients with OSCC. CONCLUSION: We suggest that it is important to investigate the expression of p53 and PCNA at the invasive front of OSCC.

Use of self-setting α-tricalcium phosphate for maxillary sinus augmentation in rabbit.

PURPOSE: The purpose of this study was to histologically and immuno-histochemically evaluate tissue changes in the maxillary sinus after bone screw implantation and maxillary sinus augmentation using self-setting α-tricalcium phosphate (α-TCP; BIOPEX(®)-R) in rabbit. STUDY DESIGN: Adult male Japanese white rabbits (n=15, 12-16 weeks, 2.5-3 kg) were used. The sinus lift was made from the nasal bone of a rabbit. Bone screws (Dual top auto-screw(®)) were implanted into the nasal bone, and after BIOPEX(®)-R was implanted into the left elevated space (operated side) an atelocollagen sponge (ACS: Teruplug(®)) was implanted into the right elevated space (control side). The rabbits were sacrificed at 4, 12 and 24 weeks postoperatively, and formalin-fixed specimens were embedded in acrylic resin. The specimens were stained with hematoxylin and eosin. For immune-histochemical analysis, the specimens were treated with bone morphogenetic protein-2 (BMP-2) antibodies. Finally, these were evaluated microscopically. RESULTS: Tight bonding without fibrous tissue continued between the bone screw and BIOPEX(®)-R, and the rigidity of the bone screw in the nasal bone was retained for 24 weeks in all cases. The area ofnew bone formation increased gradually on both sides; however, there was no significant difference between both sides at 4, 12 and 24 weeks. The number of BMP-2-stained cells on the experimental side was significantly larger than that on the control side after 4 weeks (P=0.0361). CONCLUSION: This study suggested the usefulness of self-setting α-TCP (BIOPEX(®)-R) to maintain the rigidity of implanted bone screws from an early period, and the result of BMP-2 expression suggested that BIOPEX(®)-R could have bone-conductive activity in the maxillary sinus augmentation.

Skeletal stability after mandibular setback surgery: comparisons among unsintered hydroxyapatite/poly-L-lactic acid plate, poly-L-lactic acid plate, and titanium plate.

PURPOSE: The purpose of this study is to compare the time-course changes in condylar long-axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with an unsintered hydroxyapatite (u-HA)/poly-L-lactic acid (PLLA) plate, PLLA plate, or titanium plate. PATIENTS AND METHODS: Of 60 Japanese patients diagnosed with mandibular prognathism, 20 underwent SSRO with a u-HA/PLLA plate system, 20 underwent SSRO with a PLLA plate system, and 20 underwent SSRO with a conventional titanium plate system. The time-course changes in condylar long-axis and skeletal stability were assessed by use of axial, frontal, and lateral cephalograms. RESULTS: Compared with the u-HA/PLLA group, the titanium group showed a significantly greater change in the right condyle angle between initially and 1 month (P = .0105) and intercondylar axes angle between 1 and 3 months (P = .0013). The PLLA group showed a significantly greater change than the titanium group (P = .0043) and u-HA/PLLA group (P = .0002) in terms of ramus inclination between 1 and 3 months; however, there were no significant differences among the 3 groups in the other measurements for each time interval. CONCLUSION: This study suggests that there are no significant differences in postoperative time-course changes among a u-HA/PLLA plate system, PLLA plate system, and conventional titanium plate system.

Position of mandibular canal and ramus morphology before and after sagittal split ramus osteotomy.

PURPOSE: The purpose of this study was to evaluate changes in the mandibular canal and ramus morphology before and after a sagittal split ramus osteotomy. PATIENTS AND METHODS: The subjects were 30 patients (60 sides) with mandibular prognathism who had undergone bilateral sagittal split ramus osteotomy setback surgery. The mandibular canal position and ramus morphology were measured at the 3 horizontal planes under the mandibular foramen level (level A), 1 cm lower than level A (level B), and 2 cm lower than level A (level C) preoperatively and 1 year postoperatively by computed tomography. RESULTS: Postoperative ramus width, lateral distance, lateral marrow distance, and canal length were significantly larger than the preoperative values at the foramen, 1 cm lower, and 2 cm lower. The mandibular canal completely contacted the lateral cortex without lateral bone marrow in 6 sides (10%) in levels A and B and 4 sides (6.7%) in level C preoperatively and 6 sides (10%) in level C postoperatively. CONCLUSION: This study suggested that postoperative mandibular canal position was located more posteriorly and the postoperative lateral bone marrow became thicker compared with the preoperative state.

Stress change on the temporomandibular joint in mandibular prognathism subjects with asymmetry after orthognathic surgery.

The purpose of this study was to evaluate changes in stress on the temporomandibular joint (TMJ) in 80 Japanese subjects (21 males and 59 females, mean age 23.7 years) with mandibular prognathism, with and without asymmetry after orthognathic surgery using the rigid bodies spring model (RBSM). The asymmetric group consisted of 40 subjects whose Mx-Md midline was more than 3 degrees. The remaining 40 subjects formed the symmetric group. The geometry of the stress analysis model was based on frontal cephalograms of the subjects. Menton (Me), the centre point of occlusal force on a line connecting the bilateral buccal cusps of the second molars, and the most lateral, superior, and medial points on the condyle were plotted on a computer display and stress on the condyle was calculated with the two-dimensional RBSM program, Fortran. The degree (force partition) of the resultant force, the direction (angulation), and the displacement (X, Y) of each condyle were calculated and the horizontal displacement (u), the vertical displacement (v), and rotation displacement (theta) of the mandibular body at Me were calculated pre- and post-operatively. The data was analysed using paired and unpaired t-tests. For the vertical (v) and rotational (theta) displacement, the post-operative value was smaller than the pre-operative value (v: P < 0.001, theta: P = 0.0063) in the asymmetric group. For angulation and the X-component, the post-operative value was smaller than that pre-operatively on the deviated (angulation: P = 0.0074, X-component: P = 0.0003) and non-deviated (angulation: P = 0.0024, X-component: P = 0.001) side in the asymmetric group. However, there was no significant difference between the pre- and post-operative value for any parameter in the symmetric group. These findings suggest that surgical correction of mandibular prognathism, with and without asymmetry, could induce an improvement in stress balance on the TMJ in the frontal aspect.

Loss of maspin is a negative prognostic factor for invasion and metastasis in oral squamous cell carcinoma.

OBJECTIVE: Maspin, a 42-kDa protein, belongs to the serpin family of protease inhibitors and is known to have tumor-suppressor function. In this study, we investigated the interrelationship between clinicopathologic findings and maspin expression in oral squamous cell carcinoma (OSCC). METHODS: Using immunohistochemical techniques to examine the expression levels of maspin in OSCC, maspin expression in OSCC was detected in 46 (64.8%) of 71 cases. We also compared the clonicopathologic features of OSCC cases with maspin expression levels. Moreover, we examined expression of maspin in eight cell lines derived from OSCC using reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. RESULTS: There was a significant correlation between decreased maspin expression and T-category (P < 0.01), lymph metastasis (P < 0.0001), and mode of invasion (P < 0.0001). Patients with positive maspin expression had a significantly better prognosis (P < 0.001). Lower expression of maspin was also seen in cell lines derived from grade 4D, which shows stronger invasive potential than other grades of OSCC. CONCLUSION: Maspin may be a useful marker to identify the potential for progression in OSCC.

Changes in the duration of the chewing cycle in patients with skeletal class III with and without asymmetry before and after orthognathic surgery.

PURPOSE: The purpose of this study was to examine the changes in the chewing rhythm before and after mandibular ramus osteotomy in patients with prognathism with and without asymmetry. PATIENTS AND METHODS: We divided 12 men and 22 women with mandibular prognathism into groups on the basis of symmetry and osteotomy procedure. The duration of the chewing cycle was recorded preoperatively and postoperatively. The duration of the chewing cycle and coefficient of variation were compared between groups, and the differences were analyzed statistically. RESULTS: No significant differences in each of 3 phases of the chewing cycle and total duration were found between groups on the basis of symmetry or osteotomy procedure. However, there were significant differences between the preoperative and postoperative coefficients of variation for the undeviated side in the asymmetry group (P = .0037) and in the group undergoing sagittal split ramus osteotomy (P = .0166). CONCLUSION: This study suggests that surgical orthodontic treatment does not significantly change the duration of the chewing cycle.

Assessment of pterygomaxillary separation in Le Fort I Osteotomy in class III patients.

PURPOSE: To examine the separation of the pterygomaxillary region at the posterior nasal spine level after Le Fort I osteotomy in Class III patients. PATIENTS AND METHODS: The study group consisted of 37 Japanese patients with mandibular prognathism and asymmetry, with maxillary retrognathism or asymmetry. A total of 74 sides were examined. Le Fort I osteotomy was performed without a pterygoid osteotome, with an ultrasonic curette used to remove interference at the pterygomaxillary region. Postoperative computed tomography (CT) was analyzed for all patients. The separation of the pterygomaxillary region and the location of the descending palatine artery were assessed. RESULTS: Although acceptable separation between the maxilla and pterygoid plates was achieved in all patients, an exact separation of the pterygomaxillary junction at the posterior nasal spine level was found in only 18 of 74 sides (24%). In 29 of 74 sides (39.2%), the separation occurred anterior to the descending palatine artery. In 29 of 74 sides (39.2%), complete separation between the maxilla and lateral and/or medial pterygoid plate was not achieved, but lower level separation of the maxilla and pterygoid plate was always complete. The maxillary segments could be moved to the postoperative ideal position in all cases. CONCLUSION: Le Fort I osteotomy without an osteotome does not always induce an exact separation at the pterygomaxillary junction at the posterior nasal spine level, but the ultrasonic bone curette can remove the interference between maxillary segment and pterygoid plates more safely.

Evaluation of bone formation after sagittal split ramus osteotomy with bent plate fixation using computed tomography.

PURPOSE: To evaluate bone formation between the proximal and distal segments after a sagittal split ramus osteotomy (SSRO) with bent plate fixation. PATIENTS AND METHODS: The subjects were 23 patients (46 sides) who underwent bilateral SSRO setback surgery. They were divided into titanium and absorbable plate groups. A 3 to 7-mm gap was made between the proximal and distal segments and a bent plate was fixed with 4 screws in each side of the mandible. The square of ramus (RmS), the anteroposterior length (RmA-RmP), and the mediolateral width (RmM-RmL) of the ramus at the horizontal plane under the mandibular foramen were assessed preoperatively, immediately after surgery, and 1 year postoperatively by computed tomography (CT). RESULTS: There were no significant differences between the titanium and absorbable plate groups over time. RmS after 1 year was larger than preoperatively in both groups (P < .0001). RmA-RmP significantly increased immediately after surgery and significantly decreased after 1 year in both groups (P < .0001). RmA-RmP after 1 year was significantly larger than the preoperative value in both groups (P < .0001). RmM-RmL showed a similar tendency to the anteroposterior length, but was not significant. CONCLUSIONS: The gap between the proximal and distal segments can fill with new bone after SSRO with both titanium and absorbable plates, even with few bony contacts between segments.

Apoptosis-associated markers and clinical outcome in human oral squamous cell carcinomas.

BACKGROUND: Apoptosis is a genetically regulated cell death involved in the deletion of cells in normal or malignant tissues. Proteins of the Bcl-2 family play a key role in the control of apoptosis and carry out both pro-apoptotic and anti-apoptotic functions. The present study evaluated the prognostic value of Bcl-2 and Bax expression at the invasive front of oral squamous cell carcinoma (OSCC), taking clinicopathological findings into account. METHODS: Fifty-six specimens of OSCC were randomly selected, and Bcl-2 and Bax expression was evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded pre-treated specimens at the invasive front of OSCC. Clinicopathological data were gathered and patient survival was analysed. RESULTS: No significant relationship was found between Bcl-2 or Bax expression and clinical variables. Patients with Bcl-2 expression had a worse prognosis than those without Bcl-2 expression, but the difference did not reach statistical significance. Patients with Bax expression had a significantly better prognosis than those without Bax expression (P < 0.05). In univariate analyses, T category, mode of cancer invasion and Bax expression showed significant correlations. Multivariate analysis revealed that the mode of cancer invasion and Bax expression were significant and independent variables. Bax expression was found to be the strongest independent prognostic parameter. Patients with negative Bcl-2 expression and positive Bax expression had a significantly better prognosis (P < 0.005). CONCLUSION: We suggest that Bax expression at the invasive front of OSCC is a significant predictor of prognosis and that it is therefore important to investigate the expression of Bcl-2 and Bax in this disease.

Predictive value of measuring p53 labeling index at the invasive front of oral squamous cell carcinomas.

Many studies have revealed the frequency of p53 abnormalities in oral cancer. However, it reports only on the relation between clinicopathological findings and p53 expression, and there is no study to examine the relation to the p53 labeling index (p53-LI). The purposes of this study were to examine the correlation between p53 labeling index (p53-LI) at the invasive front of oral squamous cell carcinomas (OSCC) and clinicopathological findings by immunohistochemical staining, and to evaluate clinical significance of measuring p53-LI at the invasive front of OSCC. Sixty-six biopsy specimens of OSCC were randomly selected. Patient age, gender, primary sites, T category, N category, degree of differentiation and mode of cancer invasion were analyzed. p53 expression did not correlate significantly with the clinical findings. However, significant differences were found between p53-LI and the degree of cell differentiation (p < 0.05). The p53-LI of high-grade invasive tumors was significantly larger than that of low-grade invasive tumors (p < 0.05). The overall survival rate (OS) among low-scoring p53-LI cases was 75.5% whereas that for high-scoring p53-LI cases was 40.6%. The disease-free survival rate (DFS) among low-scoring p53-LI cases was 39.5% whereas that for high-scoring p53-LI cases was 76.1%. Patients with low-scoring p53-LI had a significantly worse prognosis than those with among high-scoring p53-LI (p < 0.05). Consequently, the measurement of p53-LI at the invasive front of OSCC is significant as one of the indicators of prognosis.

The evaluation of surgical factors related to recovery period of upper lip hypoaesthesia after Le Fort I osteotomy.

PURPOSE: It is unclear whether surgical factors can affect the upper lip sensitivity. The aim of this study was to assess the factors that can affect the recovery period of hypoaesthesia of the upper lip after Le Fort I osteotomy, using trigeminal somatosensory evoked potential (TSEP) objectively. PATIENTS AND METHODS: Twenty-nine patients with mandibular prognathism underwent Le Fort I osteotomy with and without artificial pterygoid plate fracture. Trigeminal nerve hypoaesthesia at the region of the upper lip was assessed bilaterally by the TSEP method. The distance between the infraorbital foramen and the osteotomy line (IO) or the nearest plate/screw position (IP) was measured on three-dimensional computed tomography (CT). The relationship between the recovery period in upper lip hypoaesthesia and surgical factors (these distances, movement amount, pterygoid plate fracture) were analysed statistically. RESULTS: The recovery period in upper lip hypoaesthesia did not significantly correlate with IO, IP and movement amount. There was no significant difference between pterygoid plate fracture group and non-fracture group. CONCLUSION: Temporary hypoaesthesia of upper lip after Le Fort I osteotomy could not be avoided, however, osteotomy line, plate/screw position and pterygoid plate fracture in Le Fort I osteotomy did not affect the recovery period of upper lip hypoaesthesia with TSEP.

Assessment of the relationship between the recovery of maximum mandibular opening and the maxillomandibular fixation period after orthognathic surgery.

PURPOSE: The purpose of this study was to evaluate the differences in the recovery of maximum mandibular opening (MMO), and the relationship between MMO and the maxillomandibular fixation (MMF) period after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), with and without Le Fort I osteotomy. PATIENTS AND METHODS: Sixty-eight patients with diagnosed mandibular prognathism with or without asymmetry were divided into 4 groups (SSRO, IVRO, SSRO with Le Fort I osteotomy, and IVRO with Le Fort I osteotomy). MMO and the MMF period were measured preoperatively and at 1, 3, 6, 12, and 18 months after surgery. The differences among surgical procedures and the relationship between MMO and the MMF period were examined statistically. RESULTS: In relation to time-dependent changes in MMO, there were no significant differences among the groups. There were significant positive correlations between MMO and the MMF period from 1 month to 6 months after surgery. However, there were no significant correlations at 12 and 18 months after surgery. CONCLUSION: This study suggests that there were no significant differences between single-jaw surgery and double-jaw surgery in terms of postoperative time-dependent changes in the recovery of MMO. However, the MMF period was associated with the recovery of MMO.

Skeletal stability after mandibular setback surgery: bicortical fixation using a 2.0-mm locking plate system versus monocortical fixation using a nonlocking plate system.

PURPOSE: This study was conducted to compare the time-course changes in condylar long-axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with bicortical plate fixation versus monocortical plate fixation. PATIENTS AND METHODS: Of a group of 40 Japanese patients diagnosed with mandibular prognathism, 20 underwent SSRO with bicortical plate fixation using a locking plate system and the other 20 underwent SSRO with monocortical plate fixation using a conventional plate system. The time-course changes in condylar long-axis and skeletal stability were assessed through axial, frontal, and lateral cephalograms. RESULTS: Significant differences were found between the 2 groups in changes of the left condylar angle between the initial and 1-month measurements (P = .0454) and in ANB between the 1- and 3-month measurements (P = .0206); however, no significant differences were found between the 2 groups in the other measurements in each time interval. CONCLUSIONS: Our findings suggest no significant differences in postoperative time-course changes between bicortical plate fixation using a locking plate system and monocortical plate fixation using a conventional plate system.

Copper efflux transporter (ATP7B) contributes to the acquisition of cisplatin-resistance in human oral squamous cell lines.

Acquired resistance to cisplatin (CDDP) is an issue in cancer chemotherapy. This resistance has been reported to be correlated with the expression of the Cu influx copper transporter 1 (CTR1) and two copper efflux transporters (ATP7A, ATP7B). We investigated the correlation between the expression of these transporters and the sensitivity to CDDP using three pairs of parent cell lines and resistant cell lines derived from various types of invasive oral squamous cell carcinoma (OSCC). Using multiple steps, each of the CDDP-resistant cell lines, HSC-4-R, OSC-19-R, HOC313-R, was selected from HSC-4 cells derived from a cancer with medium invasiveness, OSC-19 cells derived from a cancer with high invasiveness and HOC313 cells derived from a cancer with the highest invasiveness. Resistant cell lines had a stronger expression of ATP7B in conjunction with the acquisition of CDDP-resistance than parent cell lines. Furthermore, OSC-19-R cells transfected with the ATP7B siRNA had a 10.6-fold higher sensitivity to CDDP compared to OSC-19-R cells transfected with a nonsense siRNA. These results suggest that each of the resistant cell lines had acquired resistance to CDDP due to the overexpression of ATP7B. On the other hand, the expression of CTR1 was the same between sensitive cell lines and resistant cell lines and ATP7A mRNA expression was barely noted. We conclude that ATP7B is correlated with the acquisition of CDDP resistance more closely than either CTR1 or ATP7A. ATP7B may be a key determinant in the acquired resistance to CDDP in OSCC.

Speech evaluation and dental arch shape following pushback palatoplasty in cleft palate patients: Supraperiosteal flap technique versus mucoperiosteal flap technique.

BACKGROUND: The aim of this study was to evaluate and compare the maxillary dental arch shape and speech of cleft palate patients following pushback palatoplasty using either the supraperiosteal flap technique or the mucoperiosteal flap technique. PATIENTS: Sixty-two patients (29, cleft palate only; 33, unilateral cleft lip, alveolus and palate) operated on by the supraperiosteal technique and 47 patients (23, cleft palate only; 24 unilateral cleft lip, alveolus and palate) by the mucoperiosteal technique were reviewed in this study. STUDY DESIGN: Dental arch shape and speech proficiency at preschool and school age were evaluated in all patients. RESULTS: Dental arch shapes were classified as U type (good dental arch shape) and V type (narrow dental arch shape). In cleft palate only patients, U type was observed in 90% of the supraperiosteal group and 83% of the mucoperiosteal group. In unilateral cleft lip, alveolus and palate patients, U type was observed in 85% of the supraperiosteal group, while only in 33% of the mucoperiosteal group. In cleft palate only patients, normal speech at school age was observed 100% of the supraperiosteal group and 83% of the mucoperiosteal group. In unilateral cleft lip, alveolus and palate patients, normal speech at school age was observed in 97% of the supraperiosteal group and 75% of the mucoperiosteal group. Misarticulation was frequently found in patients with the V type of dental arch shape. CONCLUSION: It is suggested that pushback palatoplasty using the supraperiosteal technique is more advantageous for speech development compared with the mucoperiosteal technique.

S100A4 regulates E-cadherin expression in oral squamous cell carcinoma.

S100A4 has multiple functions in cell cycle progression and cell motility, and has been implicated in cancer invasion. In this study, we examined the expression of S100A4, E-cadherin and its related proteins in oral squamous cell carcinoma (SCC) cell lines with different invasive phenotypes, grade 4C and 4D. Furthermore, grade 4C OSC-19 cells expressing E-cadherin were transfected with S100A4-expression vector and the expression of E-cadherin-related proteins in the stable clone was examined to elucidate the relationship between S100A4 and E-cadherin. Constitutive over-expression of S100A4 in stable transformant of OSC-19 (OSC-19/S100A4) cells led to down-regulation of E-cadherin and beta-catenin. Furthermore, grade 4D invasive cell lines (HOC313 and TSU) expressing S100A4 mRNA did not express E-cadherin, P-cadherin, and beta-catenin, while gamma-catenin protein was only weakly expressed. Thus, the mRNA expression of E-cadherin was reversely correlated with S100A4 expression in oral SCCs. Interestingly, vascular endothelial growth factor-C was up-regulated in OSC-19/S100A4 cells. In summary, S100A4-mediated regulation of E-cadherin expression may play an important mechanism in invasion and metastasis of oral SCC.

Inhibition of invasion and metastasis in oral cancer by targeting urokinase-type plasminogen activator receptor.

There have been reports of strong correlations between poor prognosis in various cancers and concomitant expression of urokinase-type plasminogen activator (uPA) and its surface receptor (uPAR). We and others have previously shown that the uPA system plays a significant role in a subset of head and neck squamous cell carcinoma. In the present study, we found that uPAR is required for invasion and metastasis of highly malignant oral cancer cells (OSC-19). Treating OSC-19 cells with antisense oligonucleotides (AS) targeting uPAR resulted in a dramatic decrease of uPAR mRNA expression. Furthermore, pretreatment with AS or siRNA targeting uPAR inhibited progression of OSC-19 cells in experimental models. These results suggest that overexpression of uPAR increases the invasiveness and metastasis of OSC-19 cells, and that uPAR is a promising therapeutic target for regulation of progression of oral cancer.

A comparative study of unilateral dislocated mandibular condyle fractures in the rabbit.

PURPOSE: The purpose of this study was to clarify the influence of patients age and the degree of dislocation on the healing of mandibular condyle fractures. MATERIAL AND METHODS: Sixty-two Japanese white rabbits (30 adolescent and 30 adult ones) were used. They underwent unilateral condylar neck osteotomy. The proximal fragments were positioned differently. In group I animals, the fragments were reduced into the original position, in group II animals the small fragment was dislocated 55-90 degrees to the ramus. In group III animals the proximal fragment was dislocated 135 degrees to the ramus. Gross and microscopic assessment was performed 4, 6, 8, 12 and 24 weeks postoperatively. RESULTS: In adolescent animals, complete healing of the fracture was observed, irrespective of the degree of dislocation. In the adult animals, there was complete healing of the fractures in groups I and II. In group III animals, there was a decrease of ramus height accompanied by some fibro-cartilaginous changes. CONCLUSION: Even in rabbits condylar deformation has been found following heavily dislocated artificial condylar fractures in adult animals. This result will help to decide for or against surgical treatment of condylar fractures in humans.