Single- or multiple-session viscosupplementation protocols for temporomandibular joint degenerative disorders: a randomized clinical trial.

The aim of the study was to compare the effectiveness of two single-session protocols, either adopting high- (protocol A) or medium-molecular weight hyaluronic acid (protocol B), with the reference five-session protocol of temporomandibular joint (TMJ) lavage plus viscosupplementation (protocol C) in the management of chronic TMJ degenerative disorders. A randomized clinical trial (RCT) with ten participants per treatment group was designed, with multiple observation points, ending at 6 months after treatment. Pain levels on a 10-point VAS scale were selected as the primary outcome variable to rate treatment effectiveness, along with a number of secondary outcome parameters. Findings showed that Group C patients had the highest decrease in pain levels. Nonparametric permutation analyses revealed that the global effect of treatment was significantly different between the three protocols (P = 0.024). Pairwise comparisons showed that the differences of treatment effect between the two single-session interventions were negligible (global P-value = 0.93). On the contrary, the five-session protocol was significantly superior to both single-session protocols (global P-values ranging from 0.003 to 0.012). In conclusion, in a population of age-, sex-, and psychosocial aspects-matched study groups, the standard of reference five-session protocol proved to be superior at 6 months as far as the decrease in pain levels was concerned, whilst there were no differences between the two single-session interventions. The absence of differences in treatment effect as for some other secondary clinical outcome variables may suggest that there is further space for future investigations attempting to reduce the number of multiple interventions for TMJ viscosupplementation.