Tactile sensitivity of vital and endodontically treated teeth

Endodontically treated teeth (ETT) used as abutments for removable partial dental prostheses (RPDPs) have an increased fracture risk as compared to vital abutments. One suggested explanation is that ETT exhibit a lower threshold level for tactile sensitivity than vital teeth. Therefore, this study compared the threshold for tactile sensitivity of vital teeth and ETT in the same individuals.

Forty participants with double crown-retained RPDPs fixed to vital teeth and ETT were included in the study. Each subject had at least one vital and one corresponding contralateral endodontically treated abutment tooth in the same jaw. After removal of the RPDP, an increasing centric force (0cN to max. 2000cN) was separately applied axially to both free-standing abutment teeth using a force gauge while the patient was asked to give three acoustic signals: (1) when noticing the first contact, (2) when noticing pressure and (3) when the pressure became displeasing. Afterwards, the same trial was performed with an eccentric force applied parallel to the tooth axis.

Statistical analysis revealed no significant differences in the threshold of tactile sensitivity of vital teeth and ETT to either centric or eccentric loading (p>0.05). Eccentric loading showed lower mean threshold values compared to centric loading. A large variability of tactile sensitivity between individuals was noted. However, there were no gender-related significant differences in tactile sensitivity (p>0.05).

The tactile sensitivity of vital and non-vital teeth seems comparable.

The assumption that a lower threshold level for tactile sensitivity in ETT than in vital teeth is responsible for their increased fracture risk could not be confirmed. Therefore, other reasons, e.g. loss of hard tissue due to root canal treatment, have to be considered responsible for the increased fracture risk of ETT.