Effect of Flat-Plane Splint Vertical Thickness on Disc Displacement Without Reduction: A Retrospective Matched-Cohort Study.
OBJECTIVE
The efficacy of occlusal splints for treating temporomandibular disorders (TMDs) remains controversial. This study aimed to evaluate and compare the effectiveness of flat-plane splints (FPSs) with a vertical thickness of 3 mm (VT3) and 5 mm (VT5) in treating disc displacement without reduction (DDWOR).


METHODS
This retrospective matched-cohort study selected the study participants from 400 TMD patients treated in the Department of Oral and Maxillofacial Surgery of Tainan Sin-Lau Hospital, Tainan, Taiwan, between August 2013 and July 2015. The thickness of occlusal splints was the predictor variable. The outcome variables included joint crepitus sound, deviation of the mandible during opening, TMD-associated headache, myofascial pain with referral, temporomandibular joint (TMJ) arthralgia, and maximum assisted opening. The case and control groups were matched 1:1 by propensity scoring to ensure that there were no statistical differences in the categorical variables and continuous variables. The analysis used χ2tests, t tests, and multiple regression analyses.


RESULTS
We allocated 162 patients into 2 groups, with 81 patients each: VT3 group and VT5 group. Both VT3 FPSs and VT5 FPSs effectively improved the DDWOR. At 12 months after treatment, the VT5 group showed remarkable improvement in joint crepitus sound and TMJ arthralgia compared with the VT3 group. No statistical differences in other TMJ-associated symptoms such as deviation of the mandible during opening, TMD-associated headache, and myofascial pain with referral were observed between the 2 groups.


CONCLUSIONS
Both VT3 and VT5 FPSs can effectively improve various clinical symptoms of DDWOR. We suggest that VT5 FPS treatment for at least 1 year is a suitable option for DDWOR patients with joint crepitus sound and TMJ arthralgia. For DDWOR patients without joint crepitus sound and TMJ arthralgia, there are no differences between the VT3 and VT5 FPSs.
Attending Physician, Department of Psychiatry, Kaohsiung Armed Forces General Hospital Pingtung Branch, Pingtung, Taiwan; and Graduate Student, Graduate Institute of Medical Science, College of Health Science, Chang Jung Christian University, Tainan, Taiwan.
Shang-Lun
SL
Lin
Associate Professor, School of Medicine, Griffith University, Gold Coast, Queensland, Australia.
Shang-Liang
SL
Wu
Associate Professor, Graduate Institute of Medical Science, College of Health Science, Chang Jung Christian University, Tainan, Taiwan.
Shun-Yao
SY
Ko
Associate Professor, School of Dentistry, Taipei Medical University, Taipei, Taiwan, and Director, Department of Oral and Maxillofacial Surgery, Chi-Mei Medical Center, Tainan, Taiwan.
Ching-Yu
CY
Yen
Director, Department of Oral and Maxillofacial Surgery, Tainan Sin-Lau Hospital (The Presbyterian Church in Taiwan), Tainan, Taiwan; Assistant Professor, Graduate Institute of Medical Science, College of Health Science, Chang Jung Christian University, Tainan, Taiwan; and Chief Executive Officer, Yuan Yuan Dental Federation, Tainan, Taiwan. Electronic address: jungwuyang1979@gmail.com.
Jung-Wu
JW
Yang
D000328:Adult; D015331:Cohort Studies; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D017090:Occlusal Splints; D057216:Propensity Score; D012189:Retrospective Studies; D013624:Taiwan; D013705:Temporomandibular Joint Disorders / Q000628:therapy*; D016896:Treatment Outcome