The mandibular condyle is a critical growth center in craniofacial bone development, especially during postnatal stages. Postnatal condyle osteogenesis requires precise spatiotemporal coordination of growth factor signaling cascades and hierarchical gene regulatory networks. Plagl1, which encodes a zinc finger transcription factor, is a paternally expressed gene. We demonstrate that PLAGL1 is highly expressed in cranial neural crest cell (CNCC)-derived lineage cells in mouse condyles. Using the CNCC-derived lineage-specific Plagl1 knockout mouse model, we evaluate the function of PLAGL1 during postnatal mouse condyle development. Our findings show that PLAGL1 contributes significantly to osteoblast differentiation, and its deficiency impairs osteogenic lineage differentiation, which consequently disrupts mandibular condyle development. Mechanistically, insulin-like growth factor 2 (IGF2) in complex with IGF-binding proteins (IGFBPs) has been identified as the principal PLAGL1 effector responsible for osteogenic regulation during postnatal condyle morphogenesis. Plagl1 deficiency significantly downregulates the IGF2/IGFBP pathway, leading to disordered glucose metabolism, defective extracellular matrix organization, and impaired ossification. Exogenous IGF2 treatment rescues impaired osteoblast differentiation caused by Plagl1 deficiency. In conclusion, the PLAGL1-IGF2 axis is a critical regulator of osteogenesis during mandibular condyle development.
Animals ; Osteogenesis/genetics* ; Insulin-Like Growth Factor II/metabolism* ; Mice ; Transcription Factors/metabolism* ; Mice, Knockout ; Cell Differentiation ; DNA-Binding Proteins/genetics* ; Mandibular Condyle/growth & development* ; Osteoblasts/cytology* ; Signal Transduction ; Neural Crest/cytology*

Anterior disc displacement is a common subtype seen in temporomandibular disorders (TMD) patients. It may cause mandibular movement disorders, such as clicking of joint, intermittent closed lock, limitation of mouth opening, etc. These disorders may affect the life qualities of patients. Anterior disc displacement may also cause mandibular malformations, especially among adolescents, which may affect the growth of condyle, therefore may have a correlation with mandibular retrusion or mandibular deviation when grown up. This paper going to review the influences of anterior disc displacement on oral mandibular function and morphology and their biological mechanisms.
Adolescent ; Humans ; Mandible ; abnormalities ; pathology ; Mandibular Condyle ; growth & development ; Mandibular Diseases ; etiology ; Movement ; Retrognathia ; etiology ; Temporomandibular Joint Disorders ; etiology ; physiopathology

OBJECTIVETo observe the changes of bone histomorphometry parameters in condyle of rabbits during mandibular forward positioning.

METHODSForty rabbits with eight weeks of age were simple randomly divided into the experimental group (n = 24) and control group (n = 16).Mandibles of rabbits in the experimental groups were induced to forward position by a functional appliance.The experimental group and control group were sacrificed after 2 and 4, 8, 12 weeks.The specimens from right tempromandibular joints were processed for undemineralised sections.These sections were used for fluorescent microscopy observation and the measurement of bone histomorphometry.

RESULTSAt 8 week bone-volume fraction [(75.83 ± 1.10)%], trabecular thickness [(103.28 ± 2.89) µm], trabecular number [(2.86 ± 0.06) mm(-1)], mineral apposition rate [(2.32 ± 0.02) µm/d] and index of osteoblast [(30.20 ± 0.47) N/mm(2)] in subchondral region of the cartilage in the experimental group were significantly increased compared with the age-matched controls [respectively (64.00 ± 1.54)%, (87.00 ± 1.13) µm, (1.84 ± 0.08) mm(-1), (1.69 ± 0.02) µm/d and (21.07 ± 0.59) N/mm(2)] (P < 0.05). However, trabecular separation [(170.00 ± 2.25) µm] was lower than those in the controls [(241.50 ± 1.57) µm] with significant difference(P < 0.05). There was no significant difference in the bone histomorphometry parameters of the central region between the experimental group and the age-matched control group (P > 0.05).

CONCLUSIONSThe pattern of bone histomorphometry parameters expression in subchondral region has a high correlation with the adaptive remodeling of the condyle after functional appliance.

Animals ; Cartilage ; anatomy & histology ; growth & development ; Female ; Male ; Mandibular Advancement ; Mandibular Condyle ; anatomy & histology ; growth & development ; Orthodontic Appliances, Functional ; Rabbits ; Random Allocation

INTRODUCTION: Condylar fractures are common in the maxillofacial region, comprising 29-40 percent of all mandibular fractures, accounting for about 20-62 percent). Previous studies reported that pediatric condylar fractures can cause disorders in facial growth and function, and the treatment methods have been controversial. Recently, conservative treatment has shown good results in skeletal growth and functional recovery but the conservative treatment of pediatric condylar fractures has shown unpredictable and undesirable results in some cases, such as facial asymmetry and temporomandibular joint disorder. This study examined the specific age groups and specific mandibular condylar fracture type in growing children treated conservatively in the past. MATERIALS AND METHODS: Eighteen patients (10 men and 8 women) who received conservative treatment for unilateral condylar fractures in Dankook University Dental Hospital between 2000 to 2007 were followed up for a mean period of 7.2 years. RESULTS: In the survey of 18 pediatric patients who received conservative treatment for condylar fractures, the incidence of temporomandibular dysfunction and growth disturbance was 45% and 35%, respectively. CONCLUSION: In all complications, the symptoms observed most frequently was mouth opening displacement of the mandible exceeding 2 mm. The other complications of functional and growth disturbance included facial asymmetry concentrated along specific condylar types. Complications including facial asymmetry and functional and growth disturbances showed an increasing tendency according to the specific fracture types. Functional and growth disturbances in the undisplaced condylar fracture type showed a lower incidence(P<0.05). Functional and growth disturbances differed according to the fracture type, which has poor relationship with articular fossa and condyle(P<0.05). Functional and growth disturbance in the cases of the high-level condylar fracture type showed a higher incidence(P<0.05). The functional and growth disturbances of the fracture types were similar in the fragment-contact and non-contact groups(P>0.05).
Accounting ; Child ; Displacement (Psychology) ; Facial Asymmetry ; Growth Disorders ; Humans ; Incidence ; Male ; Mandible ; Mandibular Condyle ; Mandibular Fractures ; Mouth ; Temporomandibular Joint Disorders

AIMTo determine cephalometrically the mechanism of the treatment effects of non-extraction and multiloop edgewise archwire (MEAW) technique on postpeak Class II Division 1 patients.

METHODOLOGYIn this retrospective study, 16 postpeak Class II Division 1 patients successfully corrected using a non-extraction and MEAW technique were cephalometrically evaluated and compared with 16 matched control subjects treated using an extraction technique. Using CorelDRAW software, standardized digital cephalograms pre- and post-active treatments were traced and a reference grid was set up. The superimpositions were based on the cranial base, the mandibular and the maxilla regions,and skeletal and dental changes were measured. Changes following treatment were evaluated using the paired-sample t-test. Student's t-test for unpaired samples was used to assess the differences in changes between the MEAW and the extraction control groups.

RESULTSThe correction of the molar relationships comprised 54% skeletal change (mainly the advancement of the mandible) and 46% dental change. Correction of the anterior teeth relationships comprised 30% skeletal change and 70% dental change.

CONCLUSIONThe MEAW technique can produce the desired vertical and sagittal movement of the tooth segment and then effectively stimulate mandibular advancement by utilizing the residual growth potential of the condyle.

Adolescent ; Case-Control Studies ; Cephalometry ; Female ; Follow-Up Studies ; Humans ; Image Processing, Computer-Assisted ; Incisor ; pathology ; Male ; Malocclusion, Angle Class II ; pathology ; therapy ; Mandible ; growth & development ; pathology ; Mandibular Condyle ; growth & development ; pathology ; Maxilla ; pathology ; Molar ; pathology ; Orthodontic Appliance Design ; Orthodontic Retainers ; Orthodontic Wires ; Retrognathia ; pathology ; therapy ; Retrospective Studies ; Serial Extraction ; Skull Base ; pathology ; Software ; Tooth Movement Techniques ; instrumentation ; methods ; Treatment Outcome ; Young Adult

OBJECTIVETo study the effect of gradually induced occlusal disorders on the expression of basic fibroblast growth factor (bFGF) of condylar cartilage in rat.

METHODSThe model of gradually induced occlusal disorders was established in rat. The expression of bFGF was examined by SABC technique of immunohistochemistry. The expression of bFGF was analyzed by amount of positive cells.

RESULTSbFGF was expressed positively in the proliferative cell layer, maturative layer and hypertrophical cell layer in the rat mandibular condyle cartilage. In control group, expression of bFGF increased from 2-week-old to 6-week-old, then it had a decrease during experiment. Compared with the control group, bFGF of experiment group was increasing at 2 week, 6 week and 8 week during experiment. But there was decreaseing at 4 week. There was no difference between young experiment group and the adult experiment group.

CONCLUSIONThe gradually induced occlusal disorders may lead to significant increase of expressiong of bFGF in condyle cartilage, which suggests that the bFGF may be involve in the procedure of repairing process of articular cartilage.

Animals ; Cartilage ; Cartilage, Articular ; Fibroblast Growth Factor 2 ; Mandibular Condyle ; Rats

OBJECTIVETo identify the relationship between the expression of BMP/Smads in condylar cartilage and condylar growth modifications in rabbits during mandibular forward positioning.

METHODSSixty male rabbits with 8 weeks of age were randomly divided into the experimental group (n=36) and control group (n=24). The mandibles of rabbits in the experimental groups were induced to forward position by a functional appliance. The rabbits in the experimental group and control group were sacrificed after 3 days and 1, 2, 4, 8, 12 weeks, respectively. The expression of BMP-2, Smad1/5, 4 and 6 in condylar cartilage was examined by immunohistochemical staining.

RESULTThe expression of BMP-2, Smad1/5, 4 and 6 was mainly found in the chondrocytes from the transitional zone and hypertrophic zone, and was also found in the chondrocytes and osteoblasts of the mineralized zone. Compared with those of the age-matched controls, the positive signals for BMP-2, Smad1/5, 4 and 6 in the experimental animals were stronger at early stage (P<0.05), coinciding with the remodeling in condylar cartilage after functional appliance.

CONCLUSIONThe expression of BMP-2, Smad1/5, 4 and 6 is associated with the adaptive remodeling of the condylar cartilage after functional appliance.

Animals ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; biosynthesis ; genetics ; Cartilage ; metabolism ; Chondrocytes ; metabolism ; Male ; Mandibular Advancement ; methods ; Mandibular Condyle ; metabolism ; Orthodontic Appliances, Functional ; Rabbits ; Random Allocation ; Signal Transduction ; Smad Proteins ; biosynthesis ; genetics ; Stress, Mechanical ; Transforming Growth Factor beta ; biosynthesis ; genetics

OBJECTIVETo study the influences on mandibular development after removing the outer cortex of mandibular body in childhood minitype pig.

METHODSSix childhood minitype pigs were selected as the experimental animals. The outer cortex of mandibular body measured as 3.0 cm x 1.5 cm was removed in one side, and the other side remained intact as the control. The changes of mandibular modality and occlusion relationship as well as the histological and biomechanical changes were studied 24 weeks after operation.

RESULTSThere was no obvious difference compared with the control side in the height of the mandibular ramus and the length of the mandibular body, However, lateral deviation occlusion was found in some animals. The body thickness was thinner than that of the control side, there were no obvious biomechanical and histological differences between the two sides.

CONCLUSIONSThere was less influence on the growth of mandibular bone after removing one side of the outer cortex of the mandibular body in childhood minitype pig. But further study should be done for the cause of the lateral deviation of the mandible in part of the animals.

Animals ; Female ; Male ; Mandible ; growth & development ; surgery ; Mandibular Condyle ; surgery ; Osteotomy ; adverse effects ; Swine ; Swine, Miniature

This study aimed to investigate the effects of indomethacin on distribution and expression of COX-2 and IGF-I in the mandibular condyle of growing dogs and to examine the number of chondroclasts around the mineralization zone. Indomethacin inhibits prostaglandin E2 production in the tissue by inhibiting synthesis of cyclooxygenase 2. Prostaglandin E2 stimulates insulin-like growth factor synthesis. Insulin-like growth factor stimulates growth of mandibular condylar cartilage. Eight mongrel dogs, aged 13 - 14 weeks, were divided into 4 groups. Group 1 and group 2 were administered indomethacin 2 mg/Kg/day orally two times a day for 7 days and 14 days respectively. Group 3 were administered indomethacin 8 mg/Kg/day orally 2 times a day for 14 days, and the control group were administered a placebo. The mandibular condyle heads were sectioned in 5 micrometer thickness. The specimens were stained with H-E staining, COX-2 immunohistochemical staining and IGF-I immunohistochemical staining and examined under light microscope. After TRAP staining, the number of chondroclasts were calculated. The observed results were as follows: Indomethacin inhibited expression and distribution of COX-2 and IGF-I on the proliferative zone of condylar cartilage. Indomethacin decreased the number of chondroclastes on the mineralization zone by a time-dependent manner (p < 0.05). Indomethacin inhibited expression and distribution of IGF-I by a dose- and time-dependent manner. These results show that indomethacin inhibited expression and distribution of COX-2 and IGF-I on the proliferative zone of condylar cartilage and decreased the number of chondroclasts and suggests that when indomethacin is administered for a long time, condyle growth could be delayed.
Animals ; Cartilage ; Cyclooxygenase 2 ; Dinoprostone ; Dogs* ; Head ; Indomethacin* ; Insulin-Like Growth Factor I* ; Mandibular Condyle*

OBJECTIVETo study the effect of growth hormone (GH) on the proliferation and type II collagen secretion of chondrocytes of mandibular condyle in rabbit in vitro.

METHODSFlow cytometry (FCM) and immunohistochemical technique were employed to observe the possible changes.

RESULTS(1) The exogenic GH can enhance the proliferation and synthesis of DNA of the chondrocytes of mandibular condyle in rabbit in vitro. The suitable concentration of GH is 10 microg/ml. The synthesis of DNA reaches the highest level after 12 hours, while the proliferation index (PI) hits the highest after 24 hours. (2) GH (10 microg/ml) can stimulate the secretion of type II collagen of the chondrocytes.

CONCLUSIONThe exogenic GH can enhance the proliferation, the synthesis of DNA and the secretion of type II collagen of the chondrocytes of mandibular condyle in rabbit in vitro.

Animals ; Cartilage, Articular ; cytology ; Cell Proliferation ; drug effects ; Cells, Cultured ; Chondrocytes ; drug effects ; secretion ; Collagen Type II ; drug effects ; Growth Hormone ; pharmacology ; Mandibular Condyle ; cytology ; Rabbits