AIM: To assess whether persistent idiopathic dentoalveolar pain (PIDAP), a diagnosis of exclusion, exhibits common features that can facilitate its diagnosis. PIDAP is defined by the International Classification of Orofacial Pain (ICOP 6.3.) as 'Persistent unilateral intraoral dentoalveolar pain, rarely occurring in multiple sites, with variable features but recurring daily for more than 2 h per day for more than 3 months, in the absence of any preceding causative event'. METHODOLOGY: In this observational study, participants fulfilling the new ICOP diagnostic criteria of PIDAP were included, covering 16 years of consecutive data. A systematic, retrospective assessment of patients utilizing the new PIDAP criteria on complaints of chronic tooth pain in a referral-based endodontic practice was undertaken. Non-idiopathic cases were excluded on the basis of clinical and radiologic findings. A modified neuropathic pain questionnaire was used to describe the painful sensations. Furthermore, allodynia in the periodontal space and sensory changes in the oral mucosa were assessed using a periodontal probe. RESULTS: Amongst the 160 patients assessed, 78 (63 women) fulfilled the strict PIDAP criteria. Pain history of PIDAP included no nocturnal awakening (85%) and a 'pulling/dragging' pain quality (59%). In 69% of the patients with PIDAP, pain was associated with a root filled tooth at the same site. In 14% of the cases, no endodontic treatment was performed in the affected quadrant. Mechanical allodynia in the gingival sulcus was observed in 91% of patients with painful teeth or implants. CONCLUSIONS: In this observational study, PIDAP mainly affected females and was associated with undisturbed sleep and periodontal allodynia.