Unbreakable?-Fracture of patient-specific implants after alloplastic mandibular reconstruction

Patient-specific implants (PSIs) are becoming increasingly common for mandibular reconstruction after continuity resection of the jaw. These implants can be used for purely alloplastic as well as complex microvascular bony reconstructions. In this regard, PSIs offer many advantages over hand-bent standard reconstruction plate systems, particularly in terms of reconstruction accuracy and the significantly increased stability shown in several in vivo studies. An in vitro study using a chewing simulator could also show that PSI plate systems seem to be non-fracturable. This paper presents two clinical cases in which a spontaneous fracture of the PSI occurred following purely alloplasticmandibular reconstruction, 40 and 42 months after primary reconstruction. When removing the fractured PSIs, no indications for plate fragments loosening on the mandibular bone were observed. It was thus assumed that mechanical stress on the plates, caused by the physiological masticatory forces, led to the fractures. Until now, no fractures of PSI systems have been detected at the authors' clinic when the PSI was combined with an autologous bone graft. Therefore, in the long-term in vivo, plate fractures of PSI systems should be still expected, particularly with purely alloplastic reconstructions. The combination of PSI and autologous (microvascular) bone graft should continue to be the treatment of choice in primary treatment planning. Purely alloplastic reconstruction may only be used in exceptional cases under strict indications.