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Purpose: The purposes of this study were to examine the occurrence of different types of mandibular lateral translation (DYMLT) using condylography and magnetic resonance imaging (MRI), to investigate the relationship between DYMLT and the disunion pattern in intracapsular derangement patients with DYMLT, and to consider the three-dimensional therapeutic position of the condyle in the mandibular fossa.Material and methods: Sixty-two patients with DYMLT, or side shift, during symmetrical mandibular movements were analyzed with computerized condylography and MRI to determine the occurrence of different types of MLT and the relationship between the DYMLT and the intracapsular derangement pattern.Results: Of a total of 62 subjects, we classified 43 (69.4%), 12 (9.4%), and 7 (11.2%) of them as DYMLT type, closed lock type, and excessive condylar rotation type, respectively. There was a high prevalence of DYMLT for subjects who had one side antero-medial (including medial sideway) and the other side antero-lateral disk displacement. The directions of DYMLT and disk displacement coincided in 95.3% of cases; this means recapturing of the displaced disk by the condyle in lower joint translation.Conclusion: Results indicate that mandibular lateral displacement causes the condyle to be displaced in the same direction, and the disk displacement to the opposite side; hence it creates DYMLT in the disk displacement direction. On the basis of these findings, it is concluded that the DYMLT is a useful indicator for early detection of intracapsular derangement and that the DYMLT allows estimation of the therapeutic condylar position.

Purpose: The purposes of this research were to investigate the mandibular lateral translation (DYMLT) during asymmetric mandibular movement and to clarify the relationship between the occurrence of DYMLT and temporomandibular joint (TMJ) status.Materials and methods: Lateral deviation of the condyle during the mandibular functional movement of 1658 orthodontic patients was screened using computerized condylography. Maximum lateral deviation during opening/closing, mastication, and grinding movements were calculated.Results: Occurrence of DYMLT in orthodontic patients was 26% and consisted of three types: DYMLT, over rotation MLT, and closed lock MLT. Occurring point of DYMLT in the condylar movement was in between 1 and 3.5 mm from reference position (RP). Maximum DYMLT tends to increase with age and DYMLT started at an early stage of growth and development. Subjects in the DYMLT group showed significantly more lateral deviation during mastication and bruxism than those in the non-DYMLT control group.Conclusion: It is suggested that the DYMLT of the condyle occurs in the lower joint after disk displacement, and that the analysis of condylar tracking can be useful for early detection of dysfunction.

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