Dr. Kidder expressed several concerns about our study, and we appreciate his comments and the opportunity to further clarify the study design and results.
Dr. Kidder states that the study was designed with "prejudice toward the behavioral sciences (and against splints)." His assumption is incorrect. As stated in the article, the original hypothesis of the study was that subjects assigned to a protocol that included a splint and a usual care protocol with a self-care component would demonstrate a statistically better post-treatment outcome on self-reported pain and clinical measures than subjects randomized to the same usual care protocol alone.
Dr. Kidder commented that we did not include subjects who had been successfully treated with splints. We are confused as to why he raised that concern, since a patient successfully treated by any method would be ineligible for enrollment as they would not meet study criteria, and to withdraw a successful treatment would raise ethical concerns.
Dr. Kidder also commented that the hard splint group was assigned patients with higher baseline symptoms. That is not correct, as shown in Tables 2, 3 and 4 and Figure 4, in which the only significant difference at baseline was for tinnitus, found to be greater in the soft splint group. Further, all subjects were randomly assigned to the treatment groups without regard to their symptom level.
Dr. Kidder correctly states that a larger number of subjects in the nonsplint group failed to complete follow-up, causing potential bias in outcome. We were aware of that potential, and under the heading "Assessment of bias due to study dropouts" on page 1105, we explained our use of carry-forward analysis, thus minimizing drop-out bias.
Dr. Kidder further commented that "the hard splint group did better ... in almost all follow-up assessments—especially in arthralgia, which was conveniently downplayed." While the raw numbers suggested that there were some differences in outcomes, analysis failed to demonstrate any statistically significant differences. The hard splint and soft splint groups did show a greater reduction in arthralgia at 12-month follow-up compared with the nonsplint group, but the difference did not reach statistical significance.
Contrary to his opinion, we reported all relevant findings as shown in the published tables. Page limitations and the lack of statistically significant differences restricted comment about trends in findings that may deserve exploration through additional research.
Dr. Kidder also raised concerns about the design of the hard splint used in the study. He is incorrect in stating that the hard splints were not adjusted. They were adjusted as needed to centric occlusion per the study design. He also felt that both upper and lower splints should have been utilized, but such a study design employing different types of hard splints would have required a dramatically larger sample size that was beyond the scope of our National Institute of Dental and Craniofacial Research funding. Further, unless patients are randomized to an upper or lower splint, the risk of selection bias would be significant.
Dr. Kidder stated that hard splints have value in treating periodontal patients, preventing tooth damage, minimizing tooth movement and preventing tooth wear. Our study was not designed to investigate those uses, and focused specifically on the treatment of painful TMD. The study found equivalent overall improvement with all three types of treatments, and no added benefit when splints were added to a usual care protocol that contained elements of self-care. It is possible that a subgroup of patients with TMD might benefit from splint therapy, but that was not the design of our study.
