Soft Splints are(n’t) bad?!
Biting into the controversy
“Soft Splints” are Bad?
The belief that soft/flex nightguards are harmful or ineffective for splint therapy originates from a 1987 article by Jeffrey P. Okeson which found that 70% of “soft” splint users experienced a 25% or greater increase in nocturnal muscle activity. From the surface of this claim, it seems evident that soft splints cause an increase in nocturnal bruxism, however, my immediate question as a lab owner and technician was, what materials were used to fabricate the “soft splint” and how would the properties of that material affect the results?
The “Soft Splint” Material
In Okeson’s study, the “soft splint” was fabricated from 4mm thick soft vinyl sheets - a material that is intended for sports guard fabrication and commonly worn by contact sport athletes. The splint in Okeson’s study was made by adapting a sports mouthguard to the antagonist jaw which resulted in a significant increase in nocturnal muscle activity. Sports Mouthguards should not be used in splint therapy according to Gray and Davies in their 2001 article, this style of splint is to be used as an emergency appliance only. Nonetheless, The findings from Okeson’s study continues to lead researchers and practitioners in a misleading path as the study is still frequently cited in modern literature and has been cited 334 times as of June 2023 according to the National Institute of Health.
4mm thick Vinyl Sheet (Used in Okeson’s study as a “Soft Splint”)
https://dental.keystoneindustries.com/product/pro-form-mouthguard-dual-color-laminates-2/
Modern Soft splints
It is quintessential that all of the authors that referenced Okeson’s study understand the fundamental difference between the materials used in Okeson’s study and modern flexible splint materials such as 3D printable splint materials (KeySplint Soft) as they have drastically different functional properties. As of June 2023, I have found no articles that test the nocturnal muscle activity of modern soft/flex materials, however, there was a study done by Hajimahmoudi and Atri regarding the effects of splint therapy on TMJ symptoms, they found there was no significant difference between hard and modern soft splints on improving TMJ symptoms.
Conclusion
In fairness to Dr. Okeson and his 1987 study, material sciences have evolved significantly over the past 36 years and a vast selection of 3D Printed, milled, and analog thermal flexing splints have made their way into the market that would have been a far more suitable option for splint therapy/treatment. More studies will be required using modern soft splint materials to determine nocturnal muscle activity when wearing a modern soft splint.
Works Cited
Gray, R. J., and S. J. Davies. Occlusal Splints and temporomandibular disorders: why, when, how? Dent Update, 2001.
Okeson, Jeffrey P. “The effects of hard and soft occlusal splints on nocturnal bruxism.” JADA, 1987, https://pubmed.ncbi.nlm.nih.gov/3475357/.
Atri, Hajimahmoudi, Sahebi. “Comparative evaluation of soft and hard splints in treatment of clenching
disorder.” J Craniomax Res 2020; 7(3) : 145-151