Three-dimensional retrospective comparison of disc repositioning, condylar remodelling, and mandibular symmetry following traditional versus digital articulation techniques in patients with temporomandibular disorders

Abstract

Background: With advancements in computer technology, digital mandibular repositioning techniques are increasingly utilised in the management of temporomandibular disorders (TMDs). This study aimed to compare the differences in joint structure restoration between traditional and digital articulation techniques.

Methods: Two groups of patients with TMD (40 in each group) received traditional or digital articulation. An occlusal splint was fabricated and administered to each patient. Imaging data were collected prior to the articulation process and after the patients wore the splint for six months. Morphological and positional changes in the articular disc were analysed; condylar displacement and mandibular asymmetry were measured, and the osseous condition of the condyle was compared using three-dimensional reconstructed models.

Results: The digital articulation technique performed better than the traditional approach in improving articular disc morphology (p = 0.036) and recapturing displaced discs (p = 0.032). In contrast to the traditional method [-0.1138 mm (95% CI: -0.2338, 0.0062)], digital technology notably facilitated condylar bone regeneration [0.0552 mm (95% CI: -0.0540, 0.1644)] (p = 0.040). Although no differences were observed in condylar displacement, an improvement in mandibular asymmetry was noted. A significant association was identified between articular disc repositioning and condylar bone alterations, with considerably greater bone growth noted in cases where successful articular disc repositioning was achieved [0.1072 mm (95% CI: 0.0286, 0.1858)] than in those where it was not [-0.2332 mm (95% CI: -0.4193, -0.0471)].

Conclusions: Restoring the optimal disc-condyle relationship is associated with condylar bone regeneration. The digital articulating technique offers precise control over the mandibular position and joint configuration, demonstrating satisfactory performance in improving the articular disc condition and reversing condylar bone destruction. Furthermore, it is user-friendly and highly efficient. The results suggest that the digital articulation technique may be a promising method for repositioning the articular disc and restoring condylar bone integrity.

Keywords: Articulating; Mandibular condyle; Occlusal splints; Temporomandibular disorder; Temporomandibular joint disc; Three-dimensional.

Fig. 1

Workflows of the two articulating techniques. a In the traditional group, the maxillomandibular-occlusal relationship was transferred to the articulator using plaster dental casts and an anatomical facebow. b Jaw position was manually adjusted by moving the condyle ball. c The therapeutic jaw position (TP) was evaluated through bite registration. d In the digital group, imaging data were aligned with digital dental models to create a three-dimensional (3D) stomatognathic model. e Jaw position was adjusted using the software. f 3D printed guides were produced to assess the TP. g Occlusal splints were manufactured based on the TP

Fig. 2

Measurement of the disc and condyle displacement. a The angle α, formed by the line perpendicular to the Frankfurt plane and the line connecting the condylar centre to the midpoint of the disc’s posterior margin, was denoted as α₁ before treatment. b The angle was denoted as α₂ after treatment. The disc repositioning angle (Δα) was calculated as α₁ - α₂. c Establishment of the coordinate system based on maxillary marks. d Sagittal plane projections: the blue outline represented the pre-treatment condyle, the yellow outline represented the post-treatment condyles, and the stars indicated the condylar centroids. Condyle displacement in the z direction was calculated as ΔZ = z₂ – z₁. e Horizontal plane projections: using the right condyle as an example, ΔX = x₂ – x₁, ΔY = y₂ – y₁

Fig. 3

Measurement of the condylar osseous condition. a Condyle reconstruction and segmentation: Points A and B marked the posterior border of the mandibular ramus, whereas point C represented the lowest point of the sigmoid notch. b Registration of pre-and post-treatment condyles. c Three-dimensional deviation analysis of the condylar surface after treatment, showing red and blue for bone growth and resorption, respectively, with quantitative analysis of nine specific landmarks. AL anterior-lateral, AC anterior-central, AM anterior-medial, ML middle-lateral, MC middle-central, MM middle-medial, PL posterior-lateral, PC posterior central, PM posterior medial

Fig. 4

Comparison of the articular disc repositioning conditions. The angle of disc repositioning (Δα) was significantly greater in the digital group than in the traditional group (p = 0.032). ^*p < 0.05

Fig. 5

Comparison of the condylar osseous conditions. a–c The digital group exhibited significantly increased deviation at AC, AM, and MC sites. d The average deviation was significantly greater in the digital group than in the traditional group (p = 0.040). AC anterior-central, AM anterior-medial, MC middle-central. ^*p < 0.05

Fig. 6

Comparison of the condyle positional changes. a No significant differences were observed in condylar displacement along the x, y, and z axes. b No significant difference existed in the RMS error. c–d The mean ΔX and RMS error in the digitally treated group with the disc repositioned was smaller than that in the traditional group. e ΔX showed a strong correlation with RMS error, whereas a moderate correlation existed between ΔZ and RMS error and between ΔX and ΔZ RMS root mean square

Fig. 7

Comparison of the condylar surface deviation. a Joints with morphologically improved discs exhibited significantly increased deviation compared to the deteriorated group. b Joints with positional improved discs showed greater deviation values than the other two groups. c Repositioning of the displaced discs was associated with higher condylar bone deviations. ^*p < 0.05, ^**p < 0.01