Novel finite element-based plate design for bridging mandibular defects: Reducing mechanical failure

INTRODUCTION

When the application of a free vascularised flap is not possible, a segmental mandibular defect is often reconstructed using a conventional reconstruction plate. Mechanical failure of such reconstructions is mostly caused by plate fracture and screw pull-out. This study aims to develop a reliable, mechanically superior, yet slender patient-specific reconstruction plate that reduces failure due to these causes.

PATIENTS AND METHODS

Eight patients were included in the study. Indications were as follows: fractured reconstruction plate (2), loosened screws (1) and primary reconstruction of a mandibular continuity defect (5). Failed conventional reconstructions were studied using finite element analysis (FEA). A 3D virtual surgical plan (3D-VSP) with a novel patient-specific (PS) titanium plate was developed for each patient. Postoperative CBCT scanning was performed to validate reconstruction accuracy.

RESULTS

All PS plates were placed accurately according to the 3D-VSP. Mean 3D screw entry point deviation was 1.54 mm (SD: 0.85, R: 0.10-3.19), and mean screw angular deviation was 5.76° (SD: 3.27, R: 1.26-16.62). FEA indicated decreased stress and screw pull-out inducing forces. No mechanical failures appeared (mean follow-up: 16 months, R: 7-29).

CONCLUSION

Reconstructing mandibular continuity defects with bookshelf-reconstruction plates with FEA underpinning the design seems to reduce the risk of screw pull-out and plate fractures.

Concomitant leukoplakia in patients with oral squamous cell carcinoma

OBJECTIVE

There is an ongoing debate on the prevalence of premalignant lesions, in particular leukoplakia, at the time of diagnosis of an oral squamous cell carcinoma (OSCC). The aim of the present study was to determine the presence of concomitant leukoplakia in 100 patients with OSCC, and to evaluate possible differences in clinical and histopathological parameters of the OSCC between those with or without concomitant leukoplakia.

PATIENTS AND METHODS

One hundred consecutive patients, 61 men and 39 women, with a histologically proven OSCC were screened on the presence of leukoplakia. Four groups were distinguished: (I) leukoplakia adjacent to the OSCC, (II) combination of leukoplakia adjacent to the OSCC, and leukoplakia at another oral site, (III) leukoplakia present at another oral site, but not adjacent to the OSCC, and (IV) no leukoplakia present.

RESULTS

In 47 (47%) patients with OSCC the presence of concomitant leukoplakia was observed. Thirty-six (36%) patients had a leukoplakia adjacent to the OSCC (groups I and II), of which eight (8%) patients (group II) also had a leukoplakia present at another oral site. Eleven (11%) patients (group III) had no leukoplakia adjacent to the OSCC, but a leukoplakia present at another oral site. Fifty-three (53%) patients (group IV) with OSCC had no concomitant leukoplakia present. No differences were noted between men and women, nor was there any preference for an oral subsite with regard to the carcinoma. There were no statistically significant differences in clinical and histopathological presentation of OSCC's between those with or without concomitant leukoplakia.

CONCLUSION

Almost 50% of oral squamous cell carcinomas are presumably associated with or preceded by leukoplakia. Early detection and active management of patients with oral leukoplakia may prevent the true development of a number of oral squamous cell carcinomas.