The aim of this study is to evaluate validity and reliability of a novel digital pain measure tool, the Faces Thermometer Scale (FTS). Pain is commonly reported by children and adolescents undergoing dental treatment. Pain is also a strongly contributing factor in the development of Dental Fear and Anxiety (DFA). Professionals often underestimate the pain perceived by their patients. Self-report tools are seldom used to measure pain in a clinical setting, denying child patients the possibility to communicate their pain experiences.

The aim of this study is to evaluate validity and reliability of a digital self-report pain measure tool, the Faces Thermometer Scale (FTS). Children and adolescents (N=150) aged 8 to 17 years visiting a dental clinic will be asked to score their pain using three different self-report pain tools; FTS, Faces Pain Scale-Revised (FPS-R) and Color Analog Scale (CAS). The validity and reliability of FPS-R and CAS is long established and will therefore be used to evaluate the psychometric properties of FTS.

BACKGROUND Pain is a personal experience influenced by biological, psychological, and social factors. Pain is more than the sum of activity in sensory neurons and therefore different from nociception (Raja et al., 2020). Pain due to dental treatments and procedures is commonly reported by children and adolescents (Ghanei et al., 2018). Dental treatments giving rise to pain is considered a strongly contributing factor in the development of Dental Fear and Anxiety (DFA) and Dental Behavioral Management Problems (DBMP) in children (Klingberg et al., 1994; Radaal et al., 2002). Several studies have pointed to professionals underestimating pain compared to the perceived pain as reported by children themselves (Beyer et al., 1990; Versloot et al., 2004). Self-report tools are seldom used to measure pain in the clinical setting, denying child patients the possibility to communicate their pain experiences. One study showed that validated pain measure tools were used in only 19 % of cases in post-anesthesia care (Hetland Smeland et al., 2018). These findings point to the importance of letting children report their own pain experiences using validated tools easily accessible and which also children are willing to use.

As every-day life becomes progressively more digital through the use of internet and mobile devices the need for a valid and reliable digital self-report pain measure has become apparent. The use of a digital tool would also provide possibilities for real-time pain measure and empower children and adolescents in making their pain heard and understood facilitating pain-management in the inpatient care as well as outside the clinical setting. Analog scales and tools previously used for measuring pain are not directly transferable to a digital format. Digital tools are also preferred by children themselves over paper versions of the same scale. (Wood et al., 2011) The Faces Thermometer Scale (FTS) is a newly devised digital self-report tool to assess the intensity of children's and adolescents' pain. The FTS uses a 0 to 10 metric, 0 representing no pain and 10 indicating much pain. Each individual metric on the numeric scale is associated with a face and a color. FTS is part of and available through the mobile application Pictorial Support in Person-Centred Care for Children (PicPecc), which can be downloaded from App Store or Google Play.

Faces Pain Scale-Revised (FPS-R) (Hicks et al., 2001) and Color Analog Scale (CAS) (McGrath et al., 1996) are two frequently used and established analog self-report tools used in different settings to measure pain in children and adolescents. FPS-R and CAS have previously demonstrated convergent and discriminative validity, except for children under 7 years of age (Tsze et al., 2013). The same study showed good responsivity and reliability for both tools. FPS-R and CAS will be used to evaluate the psychometric properties of FTS.

The aim of this study is to evaluate the validity and reliability of the newly developed digital FTS tool for measuring children's pain. The hypotheses for this study are:

The FTS demonstrate an acceptable convergent validity in measuring pain in children aged 8-17, in relation to FPS-R and CAS.

The FTS shows acceptable constructive validity in measuring pain in children aged 8-17 in relation to FPS-R and CAS.

The FTS is reliable to use for pain measurement in children aged 8-17.

METHOD A consecutive sample of children and adolescents between the ages of 8 and 17 and meet the overall inclusion criteria are invited to participate in the study. The sample is drawn from patients visiting the pediatric general dental practice at the Faculty of Odontology at Malmö University. After inclusion, participants (N=150) are divided into four groups (no pain, acute pain, procedural pain, or postoperative pain/pain after surgery) depending on the presence of pain at inclusion and what type of procedure participants are scheduled for. Depending on these factors participants are asked about pain experience at between two to six times during the visit, using all three scales each time in a randomized order. Before first-time use, participants are introduced to each of the tools and familiarized on the use of each scale. FPS-R and CAS measurements are manually registered while pain measures on FTS are digitally recorded and stored.

We will determine the psychometric properties of FTS by analyzing convergent and construct validity/responsivity in relation to FPS-R and CAS. Comparative statistics will be employed but the exact statistical method to be used will be determined at a later stage and in cooperation with a statistician. Reliability will also be determined, even if not a measure of validity but a condition for a tool to be valid.

KNOWLEDGE GAINS The need for an easily available and valid mean for children to give voice to their pain experiences has become apparent. Evaluating the psychometric properties of the Faces Thermometer Scale (FTS) and thus validating a novel digital scale for measuring pain in children and adolescents will provide dental practitioners and researchers with such a tool.

Inclusion Criteria:

• 8 to 17 years of age, undergoing dental procedures and/or examinations

Exclusion Criteria:

• cannot understand Swedish nor instructions on how to use the pain measure tools

Children and adolescents, 8 to 17 years of age, undergoing dental procedures and/or examinations