This study measures the masking of ability of 800 mg of ibuprofen on common endodontic diagnostic tests (cold, palpation, percussion) and bite force. Preoperative administration of 800 mg of ibuprofen did not result in statistically significant different diagnostic testing results or mechanical pain thresholds over the placebo treatment group. Although the results from this present study are not statistically significant, these results can be clinically significant and have impact on diagnosis and resulting treatment in certain instances. In patients with SIRP/SAP, ibuprofen masked palpation values by 40% and percussion values by 25% with little change on mechanical pain thresholds. Therefore, the bite force transducer could have potential future use as a diagnostic aid. Competent clinicians should develop an accurate diagnosis after utilizing a variety of endodontic diagnostic tests using a system of checks and balances. If this information does not coincide, then patients are encouraged to return the dental office when their symptoms resume. Since results from common endodontic testing can be masked by a high, single dose of ibuprofen, patients should be advised not to take ibuprofen prior to their return dental visit to aid in the proper diagnosis.