Composite resection of oral cancer with
en bloc resection of a segment or hemi mandible with neck node dissection was the main stay of treatment for oral squamous cell carcinoma [
15]. This had been advocated to allow complete extirpation of tumour which was thought to invade mandible though periosteal lymphatics [
16,
17]. With increasing understanding of disease spread and biological behaviour of oral cancer it is now clear that majority of the spread to mandible occurs by direct infiltration of the tumour through alveolar ridge or lingual cortical plate [
10,
18]. It has also been noted that tumours enter at the point of abutment which in both edentulous and dentulous mandible is the junction of reflected and attached mucosa. It has always been believed that mandible could be preserved if there is normal tissue intervening between tumour and the bone. However, in our study we have found a high incidence of spread (20%) through the canal of the inferior alveolar nerve, which often exclude the preservation of mandible. In these cases it is often very difficult to assess the involvement of mandible preoperatively, and subsequent conservation of mandible can lead to positive resection margins if the canal has not been excised. It has also been shown that invasive pattern of disease is evident at shallower depths, [
18] however; no such association could be identified in the present study. Dubner and Heller (1993) reported a significantly higher local recurrence rates following marginal resection of mandible which was independent of size of the primary and involvement of the nodes [
19]. They further noticed that neither mandibular invasion by tumour nor addition of radiotherapy affected recurrence rates. Similar results have been seen in study of Ord
et al, [
12]. This study being a short outcome study aimed at identifying the invasion pattern follow-up information was not available at the time of reporting however, we are making an effort to collect this information and hope to correlate the mandibular bone involvement, route and type of spread with patterns of failure in future. The present study contains the cases with previous radiotherapy and recurrence and hence the power of the study is weak.