牙周变化可由牙髓病经过侧管而来,反之,牙周病之毒素产物经侧管进入牙髓能使牙髓组织发炎或坏死。不正常之牙髓组织可压迫毒素经过侧管导致牙周组织破坏,因此产生局部病变之有害循环。由牙髓散布至牙周组织之物质可能是细菌或组织崩解之毒 Periodontal changes can be caused by endodontic disease through the side tube, conversely, toxins from periodontal disease into the pulp through the lateral tube can make pulp tissue inflammation or necrosis. Abnormal pulp tissue can be oppressed toxins through the lateral tube caused by damage to periodontal tissue, resulting in a detrimental cycle of local lesions. The material that is spread to the periodontal tissue by the pulp may be the bacterial or tissue disintegrating poison