Fanibunda K, Matthews J N
Department of Oral and Maxillofacial Surgery, University of Newcastle upon Tyne, UK.
J Anat. 2000 Jan;196 ( Pt 1)(Pt 1):23-9. doi: 10.1046/j.1469-7580.2000.19610023.x.
The medial cortical surface of the mandible can be involved by tumour infiltration from the floor of the mouth. A detailed study of spread via accessory foramina through the edentulous alveolar crest has been previously undertaken, but no similar study has been carried out for the medial surface. In order to gain further appreciation of the mode of tumour spread, a study of the number and distribution of accessory foramina on the medial mandibular surface was performed on 89 mandibles. The number of foramina varied greatly from specimen to specimen. In the ascending ramus above the inferior dental foramen, 3 mandibles showed no foramina; the condylar section possessed the greatest proportion followed by the sigmoid and the coronoid. On the rest of the medial surface below the inferior dental foramen, all specimens showed at least 1 accessory foramen; the greatest concentration was in the middle third along the path of the inferior dental canal, followed by the upper third and the lower third section. Accessory foramina were repeatedly present at certain dedicated sites. The medial facing wall of the inferior dental foramen was found to be the commonest dedicated site (98.3%) followed by foramina on either side of the genial tubercles (71.9%), the digastric fossa (71.9%) and the median foramen above the genial tubercles (64%). The findings of this study are in keeping with the current observation that the lower border is least commonly involved in tumour spread. In view of the presence of accessory foramina along the inferior dental canal and especially on the medial facing wall of the inferior dental foramen, it is imperative to preclude tumour spread in this region prior to undertaking the conservative rim resection procedure. Medial to the symphysis the alveolar mucosa dips down almost to the level of the dedicated foramina in the vicinity of the genial tubercles. As a general rule the attached muscle forms a barrier to tumour spread except in the later stages, however, in irradiated mandibles resistance to spread has been previously reported to be diminished. Under these circumstances, it is possible that the numerous accessory foramina reported in this study could facilitate a direct pathway into the cancellous bone.
下颌骨的内侧皮质表面可能会受到来自口腔底部肿瘤浸润的影响。此前已对通过无牙牙槽嵴的副孔进行扩散的情况展开了详细研究，但尚未对内侧表面进行类似研究。为了进一步了解肿瘤的扩散方式，对89例下颌骨的下颌骨内侧表面副孔的数量和分布进行了研究。孔的数量在不同标本之间差异很大。在下颌孔上方的升支中，3例下颌骨未显示出孔；髁突部分的孔比例最大，其次是乙状切迹和冠突。在下颌孔下方的内侧表面其余部分，所有标本均至少有1个副孔；最集中的区域是沿下颌管走行的中三分之一，其次是上三分之一和下三分之一部分。副孔在某些特定部位反复出现。发现下颌孔的内侧壁是最常见的特定部位（98.3%），其次是颏结节两侧的孔（71.9%）、二腹肌窝（71.9%）和颏结节上方的正中孔（64%）。本研究结果与目前观察到的肿瘤扩散最少累及下缘的情况一致。鉴于下颌管沿线尤其是下颌孔内侧壁存在副孔，在进行保守性边缘切除手术之前，必须防止肿瘤在该区域扩散。在正中联合内侧，牙槽黏膜几乎向下延伸至颏结节附近特定孔的水平。一般来说，附着的肌肉除了在后期外会形成一道肿瘤扩散的屏障，然而，此前有报道称，接受过放疗的下颌骨对扩散的抵抗力会减弱。在这种情况下，本研究中报告的众多副孔可能会为进入松质骨提供一条直接途径。
