Cyclophosphamide-induced temporomandibular synostosis

Area of Science:

• Developmental biology
• Teratology
• Orthodontics

Background:

• Understanding normal craniofacial development is crucial for orthodontists.
• Facial malformations provide insights into developmental processes.
• Temporomandibular joint (TMJ) synostosis has not been previously reported as a teratogen-induced abnormality.

Purpose of the Study:

• To investigate the potential of cyclophosphamide to induce temporomandibular joint (TMJ) synostosis.
• To characterize the craniofacial abnormalities resulting from TMJ synostosis in rabbit offspring.

Main Methods:

• Pregnant rabbits received daily injections of cyclophosphamide (50 mg) from days 11-14 of gestation.
• Control group received no treatment.
• Fetuses were delivered via cesarean section on day 28 and alizarin-stained for skeletal analysis.

Main Results:

• Six of ten cyclophosphamide-treated rabbits produced offspring with TMJ synostosis.
• Affected skulls exhibited retrognathic mandibles and altered mandibular angle trabeculae orientation.
• Head length was significantly reduced in treated groups, particularly in those with synostosis.

Conclusions:

• Cyclophosphamide can induce TMJ synostosis, a novel teratogenic effect.
• The malformation may result from impaired mesenchymal factors or mandibular musculature development.
• Findings align with theories linking immobilization and hypodevelopment in maxillofacial growth.