The needle teeth of piglets are often cut shortly after birth to prevent damage to littermates and the sow's udder. This practise is, however, contested because the pain it inflicts to piglets may counterbalance its benefits. The purpose of this experiment was to assess the consequences of tooth resection over the subsequent days and weeks by histological examination. Two techniques were compared: tooth clipping with clippers, and tooth grinding with a rotating grindstone. Twenty piglets received each of three treatments (one treatment per half-jaw): clipping, grinding, and control (teeth left intact). Four piglets were slaughtered at each of the following stages: 3, 6, 13, 27 and 48 days after tooth resection. Their teeth were then collected and prepared for histological examination. The analysis revealed that both clipping and grinding induce lesions such as pulp cavity opening, fracture, haemorrhage, infiltration or abscess, and osteodentine formation. Wost of these effects appeared sooner and were of greater magnitude after clipping than after grinding. Because most of the observed histological alterations are known to cause severe pain in humans, it is likely that tooth resection — even when achieved through grinding — induces severe pain in piglets. Thus, the rationale of this practice should be re-evaluated.