## 2 Materials and Methods
### Outcome Measures  
Psychophysical pain processing features were evaluated as primary outcome measures. Widespread mechanical hyperalgesia was calculated by adding up the mean of three Pain Pressure Thresholds (PPTs) (with 30 s rest between them) [11], assessed with a handheld pressure algometer (FPX Model, Wagner Instruments, Greenwich, CT, USA) at distant areas spread throughout the body: the right upper trapezius, the right epicondyle and the left anterior tibialis muscle. The PPT was applied with the algometer perpendicular to the skin, increasing at a rate of 1 kg/s [12] until the first sensation of pain. The reliability of algometry to assess PPTs has been shown to be good to excellent, with an intraclass correlation coefficient of 0.84-0.96 [13]. Temporal Summation (TS) was elicited through the application of 10 pulses of the handheld algometer with the intensity of the PPT,previously calculated following the protocol above, over the middle of the distal phalanx of the left thumb [14]. In each pulse, pressure intensity increased at a rate of 2 kg/s over the previously determined PPT intensity, leaving an interstimulus interval of one second, according to the optimal method reported for inducing TS with pressure pain [15]. The patient was taught to rate the pain intensity of the 1 st and 10 th pressure pulses through the VNPRS, and the recorded punctuation was the result of subtracting the VNPRS score at the 10 th pulse minus the VNPRS score at the 1 st pulse. Finally, Conditioned Pain Modulation was evaluated after 5 min of finishing the TS task to prevent contamination. One PPT was assessed with algometry in the middle of the distal phalanx of the right thumb, corresponding to the first test stimulus. Afterwards, the immersion of the contrary hand up to the wrist into stirred ice-cold water (0-4 \({}^{\circ}\)C) for 3 min or until the pain was unbearable was used as the conditioning stimulus [16]. A second PPT was measured immediately after removing the hand from the cold water, corresponding to the second test stimulus. A third PPT was calculated 1 min later to assess the CPM residual functioning. The combination of PPT induced ba y handheld pressure algometer as a test stimulus and cold water as a conditioning stimulus is considered to be the most reliable method to assess CPM [17].  
The secondary outcome measures included were clinical pain and craniofacial disability, assessed by the VNPRS, Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) Pain Scale [18], by the Brief Pain Inventory (BPI) [19], and by the Crani Pain and Disability Inventory (CF-PDI) [20]; quality of sleeping was evaluated by the Pittsburgh Sleep Quality Index (PSQI) [21]; and oral health was measured by the General Oral Health Assessment Index (GOHAI) [22] and by the Oral Health Impact Profile (OHIP-14) [23].  
Secondarily, other psychological and cognitive variables were measured through the following tests: Trail Making Test (TMT) [24], Stroop [25], Montreal Cognitive Assessment (MoCA) [26], Digits-Symbols of the Wechsler Intelligence Scale III [27], State-Trait Anxiety Inventory (STAI) [28], Beck Depression Inventory II (BDI-2) [29], and Pain Catastrophizing Scale (PCS) [30].