Partial duplication of the jaw: case reports and review of relevant publications

Double mandible coronoid process: a very unusual feature

PURPOSE

The double coronoid process (DCP) is a very unusual feature in patient. The literature, which briefly describes just only one case. Being this a very unusual feature, the aim of the paper is to describe the finding, discuss the anatomic, radiological, and clinical characteristics of a DCP.

METHODS

A 61-year-old-woman with no significant medical history, extraoral and intraoral examination was unremarkable. Following panoramic radiography (PR) for assessment of periodontal support and pre-implant planning suspicious radiopaque area in the mandibular notch on the left side was observed. Cone-Beam Computed Tomography (CBCT) and Magnetic resonance imaging (MRI) were subsequently performed.

RESULTS

No signs and symptoms of syndromes or medical records with a relevant contribution to the DCP existence and the patient denied any type of facial trauma. CBCT image showed the structure found on the PR was indeed a DCP and it was not superimposed on the mandibular notch area, MRI was performed to investigate soft tissue components and temporomandibular joint (TMJ) or other alterations.

CONCLUSION

DPC is extremely rare with the only case reported in the literature within the same comparison parameters. In this case images revealed the muscles, articular surfaces and articular disc were well preserved, and no other alterations were found.

A Neural Crest-specific Overexpression Mouse Model Reveals the Transcriptional Regulatory Effects of Dlx2 During Maxillary Process Development

Craniofacial morphogenesis is a complex process that requires precise regulation of cell proliferation, migration, and differentiation. Perturbations of this process cause a series of craniofacial deformities. Dlx2 is a critical transcription factor that regulates the development of the first branchial arch. However, the transcriptional regulatory functions of Dlx2 during craniofacial development have been poorly understood due to the lack of animal models in which the Dlx2 level can be precisely modulated. In this study, we constructed a Rosa26 site-directed Dlx2 gene knock-in mouse model Rosa26 ^{CAG-LSL-Dlx2-3xFlag} for conditionally overexpressing Dlx2. By breeding with wnt1 ^cre mice, we obtained wnt1 ^cre ; Rosa26 ^Dlx2/- mice, in which Dlx2 is overexpressed in neural crest lineage at approximately three times the endogenous level. The wnt1 ^cre ; Rosa26 ^Dlx2/- mice exhibited consistent phenotypes that include cleft palate across generations and individual animals. Using this model, we demonstrated that Dlx2 caused cleft palate by affecting maxillary growth and uplift in the early-stage development of maxillary prominences. By performing bulk RNA-sequencing, we demonstrated that Dlx2 overexpression induced significant changes in many genes associated with critical developmental pathways. In summary, our novel mouse model provides a reliable and consistent system for investigating Dlx2 functions during development and for elucidating the gene regulatory networks underlying craniofacial development.