Forces that fracture teeth during extraction with mandibular premolar and maxillary incisor forceps.

Our aim was to measure the forces that fracture teeth during extraction based on the effectiveness of the extraction forceps, and to compare them with data collected about forces applied to extracted teeth that did not fracture. We studied 208 patients whose teeth fractured during both the standard and our new method of extraction: maxillary incisors (n=79) extracted with forceps 1 (maxillary incisor forceps), and both maxillary (n=95) and mandibular incisors (n=34) extracted with forceps 13 (mandibular premolar forceps). Forces needed to fracture were assessed with a specially-designed instrument for measuring pressure and rotation. Mean (SD) pressure at the fracture site was significantly higher in maxillary incisors extracted with forceps 1 (1.26 (0.26) bar) then in both maxillary and mandibular incisors extracted with forceps 13 (0.96 (0.19) and 0.98 (0.16), p<0.001). Pressure at dislocation and both left and right rotation showed similar patterns. Pressure correlated to root surfaces of teeth ranging from r=0.35-0.54 but the correlation coefficients did not differ significantly between the teeth-forceps groups. Pressure was higher in fractured than in extracted teeth, and this varied from 3%-48%. In conclusion, forces that break teeth during extractions are sometimes only slightly higher than the extraction forces, so caution is needed during extraction.