1. TEMPOROMANDIBULAR JOINT INTERPOSAL MATERIAL STUDY –
TEMPOJIMS PHASE 1 – PILOT KINEMATIC OUTCOMES
Ângelo DF (1,6), Monje F (2), González R (2), Mónico L (3), Sanz D (3), Morouço P (4), Alves N (4), Salvado F (1)
Faculty of Medicine, Lisbon, Portugal; (2) Infanta Cristina Hospital, Faculty of Medicina, University of Extremadura, Badajoz, Spain; (3) Coimbra University, Coimbra Portugal; (4) Instituto Politécnico de Leiria, Centre for Rapid and Sustainable Product Development (CDRSP), Leiria, Portugal
Introduction Despite the large number of discectomy procedures performed annually, we are not aware of any high-quality randomized, controlled trial that have investigated in human or animal the jaw movement implication of bilateral discectomy and bilateral discopexy using a sham surgery control group. Most of the previous studies have focused in the histologic an imaging changes, but would that be enough? With this paper the authors will report for the first time a high-quality preclinical study, evaluating the impact of bilateral discectomy and bilateral discopexy in mastication and rumination of Black Merino Sheep.
Methods Temporomandibular Joint Interposal Material Study (TEMPOJIMS) is a is a two-phase exploratory randomized preclinical trial with 18 animals. This report is aimed to understand the role of TMJ bilateral discectomy versus TMJ bilateral discopexy versus sham surgery control group in Black Merino sheep masticatory time and ruminant kinematics. The evaluation of the kinematics movement of the sheep jaw was based in the normal processes used by ruminants to breakdown of particulate dry matter: (1) initial chewing during eating, and (2) further chewing during rumination. The authors discriminate the two processes and analyzed them separately. To analyze the initial chewing we proposed to analyze the time spent to eat a dose of 150 grams of dry pellets (Rico Gado A3).
These dry pellets were introduced in the feeder and 09:00 am and the time was chronometered until they eat all the pellets. We called this outcome absolute masticatory time. With this outcome we expected to determine if TMJ surgical interventions proposed could change the initial chewing time. To analyze the ruminant chewing phase we constructed a special box and recorded with a video camera 15 ruminant chewing. With special software we analyzed this ruminant movements in a frontal position proposing the following pilot outcomes: (1) ruminant time per cycle, (2) ruminant kinetics and (3) ruminant area. We compared this outcomes in the three groups 19, 20 and 21 days after the surgery T1), and each month in the same days during five months (T2 to T6).
Figure 1. Complete ruminant cycle.
Results ABSOLUTE MASTICATORY TIME - An one-way Analysis of Variance (ANOVA) was performed, showing significant differences between the three groups only in T1, F(2, 6) = 8.37, p = .018, η2p = .736, (1 – β) = Throughout the remaining follow-up period (T2-T6) no statistically differences were found between discectomy, discopexy, and sham surgery conditions (p > .20).
RUMINANT TIME PER CYCLE - Ruminant time per cycle rate didn´t vary across groups both in the pre-test (T0) and ruminant time per cycle rate didn´t vary across groups both in the pre-test (T0) and in all times for the post-test (p > .20). For T1 and T2, due to the Levene's test of equality of error variances showed that the error variance of the dependent variables were different across groups, the non-parametric Kruskal-Wallis test was performed. Ruminant time per cycle rate in the baseline and from T1 to T6. As can be seen, the main differences are in T1 and T2 for discectomy in comparison with discopexy, and sham surgery. The masticatory time/masticatory cycle rate was lower in the discectomy condition, despite the non-parametric test power, probably due to its low lower, didn’t identify this difference as statistically significant.
RUMINANT KINETICS AND AREA - Masticatory area didn´t vary across groups in the pre-test (T0) and in all times for the post-test. Masticatory area didn´t vary across groups in T0 and in all times for the post-test (p > .10). For T3 the Fisher LSD post-hoc identified a significant superiority in the Discopexy area in comparison with the Discectomy area, p = For T4 the same post-hoc test identify a significant superiority in the sham surgery area in comparison with the Discectomy area, p = .016.
Conclusions The authors agree that the rigorous study design and the animal model were the high values of this research. The limitations were the small sample size. The first month after intervention (T1) seems to be the critical period regarding kinetic changes. TMJ discopexy don’t seem to have an important impact concerning kinetic changes in Black Merino Sheep. TMJ bilateral discectomy seems to have an important impact in the first 2 months after surgery but in T3 and T4 a normalization of the results were observed. The only outcome that discectomy group was not able to recover was the ruminant area. The introduction of kinematics evaluation introduce a new challenge for future TMJ studies.
Sheep code
Sham surgery
Sham surgery
Sham surgery
B.discectomy
B.discopexy
References (1) Eriksson L., Westesson P-L. Discectomy as an effective treatment for painful temporomandibular joint internal derangement: A 5-year clinical and radiographic follow-up. J Oral Maxillofac Surg 2001;59(7):(2).Mazzonetto R., Spagnoli DB. Long-term evaluation of arthroscopic discectomy of the temporomandibular joint using the Holmium YAG laser. J Oral Maxillofac Surg 2001;59(9):1018–23; (3).Trumpy IG., Lyberg T. Surgical treatment of internal derangement of the temporomandibular joint: long-term evaluation of three techniques. J Oral Maxillofac Surg 1995;53(7): (4) Bjørnland T., Larheim TA. Discectomy of the temporomandibular joint: 3-year follow-up as a predictor of the 10-year outcome. J Oral Maxillofac Surg 2003;61(1):55–60. (5)Nyberg J., Adell R., Svensson B. Temporomandibular joint discectomy for treatment of unilateral internal derangements—a 5 year follow-up evaluation. Int J Oral Maxillofac Surg 2004;33(1):8–12. (6) Sato S., Goto S., Koeda S., Motegi K. Changes of the elastic fibre network of the rabbit temporomandibular joint following discectomy. J Oral Rehabil 2002;29(9):847–52. (7) Bjørnland T., Haanaes HR. Discectomy of the temporomandibular joint: an experimental study in monkeys. J Craniomaxillofac Surg 1999;27(2):113–6. (8) Dimitroulis G., Slavin J. The effects of unilateral discectomy and condylectomy on the contralateral intact rabbit craniomandibular joint. J Oral Maxillofac Surg 2006;64(8):1261–6.
B.discopexy
B.discopexy
B.discectomy
B.discectomy
Figure 2. Geometry and area of ruminant pattern of Black Merino sheep in TEMPOJIMS phase 1.