Posterior Mandibular Displacement. A Systematic Review Based on Animal Studies

Treating extreme mandibular growth is challenging. The mandible is pushed backwards to address itsprotrusion. Nevertheless, conclusions after such displacement in animals have been contradictory. The aim of the present review is to present measurable alterations of the mandible and the condyle following retractionin healthy rats or rabbits. PubMed, Scopus and Web of Science were accessed for relevant studies up to October 2020. Eligibility was determined by the PICOS process, while the risk of bias was estimated with SYRCLE’s risk of bias tool. Retraction resulted in a more distal molar occlusion and the condyle rested more posteriorly. Mandibular anteroposterior bilateral growth restriction was achieved, the condylar process measured smaller and its angulation increased. The condylar neck thickened, its posterior surface flattened, the coronoid process was measured longer, and enlarged retromolar density was registered. Differences in the ramus height and the intercondylar distance were insignificant. Changes persisted for the period of study and subsequently the mandible resumed its inherited growth pattern. The timing of mandibular shaping and TMJ outcomes might depend on the properties of the applied force. Stability is of concern and well-structured, long-term studies are expected to resolve the issue and further clarify the results of posterior mandibular displacement.

TMJ Replacement Following Pseudoarthrosis of Condylar Neck Fracture With Dislocation of the Condylar Neck Within the Infra-Temporal Fossa

Study Design: Case Report Objective: To present a patient with long-standing TMJ dislocation and pseudoarthrosis in the temporal bone treated with orthognathic surgery and unilateral joint replacement. Method: The patient, a 52-year-old female, came to our department to treat facial asymmetry and oral rehabilitation. The patient reported early facial trauma at 7 years old showing partial edentoulism, dental occlusion class III and a 19 mm mandibular midline deviation. Cone beam computed tomography showed the left TMJ in long-standing dislocation into the fossa temporalis, creating a new articular fossa in the temporal bone and adaptation of the hard and soft tissue. Results: Orthognathic surgery and TMJ replacement using a patient-specific implant and dental rehabilitation were planned; surgery was performed with no complications, and the 1-year follow-up showed that this treatment was a good option for long-standing TMJ dislocation. Conclusion: The long-term TMJ dislocation can be successfully treated by TMJ replacement using a patient-specific implant to obtain facial balance and oral function and avoid relapse.

Condylar Neck and Sub-Condylar Fractures: Surgical Consideration and Evolution of the Technique with Short Follow-Up on Five Cases

Condylar neck and sub-condylar fractures of the mandible are a frequent occurrence in maxillofacial surgery. The indication for surgical treatment of these fractures has changed over time, and several techniques have been developed with different results in the attempt to avoid the most worrisome adverse event, i.e., facial nerve injury. In this study, we present a new technique that combines an intraoral and a cutaneous pre-auricular access, which allows for easy and safe access to the surgical site, preventing facial nerve injury and avoiding surgical scars in high-impact aesthetic areas of the neck. Five consecutive patients affected by condylar neck or sub-condylar fractures were treated at a single institution using a combined intraoral and pre-auricular access. Results were evaluated after three months from surgery in terms of mandibular mobility, occurrence of complications, and patient’s satisfaction. All five patients had good outcome, with complete healing of the fracture and no occurrence of complications, including no facial nerve palsy. A key point of the technique is the safe reduction of the two mandibular fragments realized by a combined intraoral and a cutaneous pre-auricular surgical access. The periosteal plan of the ramus can be widely and safely elevated with the intraoral approach and connected to the condylar bone plane by the pre-auricular cutaneous approach without any need for soft tissue dissection at the fracture rim, thereby avoiding facial nerve injuries. Wide ramus periosteum elevation creates an “optical space”, allowing fragment reduction and fixation under direct oblique view without any endoscopic need. Our results strongly suggest that with our technique it is possible to treat sub-condylar and condylar neck fractures safely, avoiding facial nerve injury, which is an unacceptable complication due to its heavy impact on a patient’s life.