A new guide to mandibular resection for oral squamous cell carcinoma based on the Cawood and Howell classification of the mandible

A new guide for mandibular resection in the management of oral squamous cell carcinoma based on the Cawood and Howell classification of the jaws is suggested. This was a retrospective review of case records and pre-operative orthopantomograms (OPG), bone scintigraphy and magnetic resonance imaging (MRI). The classification of the mandible was based on the residual bone height as measured in the molar region of the OPG to be equivalent to the Cawood and Howell classification of the mandible (Class I-II dentate or immediate post-extraction), Class III-IV >20 mm well-rounded or knife-edge ridge, and Class V-VI <20 mm (flat or depressed ridge form). Of the 77 patients, 58% (22/38) of Class I-II, 43% (9/23) of Class III-IV and 6% (1/16) of Class V-VI were treated with a marginal (rim) resection of the mandible. The predictability of the pre-operative investigations was more accurate in the edentulous mandible (Class III-VI). A simple guide is suggested for mandibular resection taking into account the pre-operative investigations, the estimation of invasion clinically, and the Cawood and Howell classification of ridge resorption.Cawood and Howell classificationOPG−, MRI−, BS−, no invasion/periosteal invasionOPG−, MRI+ or BS+, early invasion (<5 mm)OPG+, MRI+, BS+, late invasion (>5 mm)I-II (dentate or immediately post-extraction)RimRimRim/segmentIII-IV (round or knife-edge ridge)RimRim/segmentSegmentV-VI (flat or depressed ridge)Rim/segmentSegmentSegment