Registration of jaw centric relation with different deprogramming devices

BACKGROUND: There are several methods to register jaw centric relation for diagnosis and therapy of dysfunctional disorders of the temporomandibular joint. However, there is insufficient information in the literature regarding the choice of the optimal way to determine this indicator.

AIM: To compare different methods for recording jaw centric relation according to the data of the computed tomography of temporomandibular joint.

MATERIALS AND METHODS: The study includes participants with increased abrasion of hard tooth tissues and symptoms of musculoskeletal dysfunction of the temporomandibular joint. The main group (80 people) has been recorded jaw centric relation using deprogramming devices (Lucia jig — 1^st subgroup, Kois deprogrammer — 2^nd subgroup, sheet calibrator — 3^rd subgroup, deprogrammer in combination with M. Rocаbado kinesiotherapy elements — 4^th subgroup). The control group included 20 participants, who had not had deprogramming before registration of jaw centric relation. The results were monitored using computed tomography of temporomandibular joint and subsequent assessment of the sizes of the TMG articular gap in the coronary and sagittal sections at 3 stages of the study: diagnostic, after registration of jaws central relation and prosthetic treatment and 6 months after prosthetic rehabilitation. Since there were no more than 50 observations in each group, the Shapiro–Wilk W-test was used to verify compliance with the norm.

RESULTS: According to the data obtained, the parameters of the temporomandibular joint gap have changed in the main group of the 1^th subgroup, where indicators are approaching the physiological norm (98% of cases). In the 2^nd subgroup, 90% of the participants show a tendency to conform to the physiological norm. The exception is 10% of the participants with no tendency of improvement. The smaller part (75%) of the participants of the 3^rd subgroup observed compliance of the parameters of the articular gap with the criteria of the norm. The dimensions of the anterior part of the articular gap of the temporomandibular joint exceed the dimensions of the distal part, which indicates the anterior position of the temporomandibular joint. Some patients in this group (25%) showed no positive results of computed tomography measurements after jaws centric relation registration. In the 4^th subgroup, the patients returned to normal values (100% of the cases). The positive effect of prosthetic treatment and restoration of the position of the articular heads of the temporomandibular joint were obtained in 45 % of the participants in the control group. However, in 55% of the participants the location of the articular gap of the temporomandibular joint did not improve.

CONCLUSIONS: Lucia jig in combination with the M. Rokabado’s complex of cranial-postural kinesiotherapy is the most effective method to register jaw centric relation within this study. The remaining methods are also applied among prosthetic dentists and gnathologists. However, in each clinical situation, it is necessary to consider temporomandibular joint pathology indications, type and degree of severity as well as the technical and financial capacity of both doctor and patient.