Reproducibility of 6- and 4-category faces pain scale to the assessment of temporomandibular joint pain and muscle in school-age children.

Objective: The aim of this study was to compare the levels of reproducibility between two Faces Pain Scales (FPS) of 6 and 4 categories to the assessment of pain intensity on children with and without Temporomandibular joint and muscle pain.
Material and Methods: A total of 29 children were recruited: 13 symptomatic (9.79 ± 1.36 years old) and 16 asymptomatic (8.69 ± 0.87 years old). One previously-trained examiner applied manual palpation to evaluate orofacial structures, and FPS to assess pain intensity. All children were initial evaluated using 6-category FPS and after 3 days using 4-category FPS. The children were assessed after a seven day time interval from initial and second sessions. Weighted Kappa coefficient was used to verify reproducibility levels.
Results: Similar levels of reproducibility (moderate and fair kappa values) have been verified with the application of the 6-category FPS on symptomatic and asymptomatic children. Similar results were verified using 4-category FPS on symptomatic and asymptomatic children (poor and fair kappa values).
Conclusion: Higher levels of reproducibility were verified with the application of the 6-category FPS in both groups and considering symptomatic and asymptomatic as single group. In this way, the 6-category FPS should be preferred over the 4-category FPS to assess pain intensity on children's orofacial structures.