Effect of maxillary molar distalization on mandibular condylar pathways

Abstract

Introduction:The objectives of this study were to determine whether maxillary molar distalization with a Pendulum appliance affects mandibular condylar pathways and whether quantitative axiographic measurements and tracings can measure these changes.Methods: Twenty Dental Class II subjects, aged 11.5-15.5, were selected for maxillary molar distalization with a pendulum appliance. Before treatment open-close, protrusion-retrusion, and left and right mediotrusion movements were recorded for each subject. Axiography was repeated after molar correction to Class I and appliance removal. The differences between pre-treatment and post-treatment data were determined and analysed with paired t-tests.Results: The open-close curve coefficient increased 0.03 for left excursion (p < 0.033), 0.03 for left incursion (p < 0.008) and 0.04 for right incursion (p < 0.001). The protrusion-retrusion left reproducibility index was reduced 0.29 mm 2 /mm (p < 0.001) and the right reproducibility index of 0.65 mm 2 / mm (p < 0.001). The left mediotrusion movement left quantity was reduced 1.49 mm (p < 0.001). The right mediotrusion movement right quantity was reduced 1.07 mm (p < 0.001).Conclusion: Following Pendulum appliance treatment, for the open-close movement, the increases in the Kobs curve coefficient are indicative of a more physiologic condylar tracing. For the protrusion-retrusion and left and right mediotrusion movements the changes in both quantitative axiographic values and curvature deviation are indicative of a less physiologic condylar tracing as defined by Kobs.

The effect of maxillary molar distalization on cervical posture

“…In an associated study, significant change was found in the condylar pathways following molar distalization with a Pendulum appliance [11]. However, no significant change was recorded in this study for various measurements of cervical posture.…”

“…Changes secondary to upper molar distalization with a Pendulum appliance have been reported, these include a cephalometric analysis of the head [4], a cast and cephalometric analysis [16], a cast and cephalometric analysis of unilateral distalization [33] and an axiographic analysis of condylar movement [11]. It has not been reported whether cervical posture is altered as a consequence of maxillary molar distalization with a Pendulum appliance.…”

Impact of molar teeth distalization by clear aligners on temporomandibular joint: a three-dimensional study

“…Looking at the results of this study, the upper molars distalization technique performed with clear aligners seems to overcome various side effects related to this orthodontic procedure typically observed with other appliances [ 11 , 49 ] and seems to allow a predictable distal body movement of upper molars with control of the TMJ parameters. This could be related to the aligner design, which enables the control of 3D movements by holding teeth on all the surfaces (occlusal, vestibular, and palatal/lingual) and applying proper forces thanks to properly digitally planned attachments.…”

“…The thickness of aligners and the impact of the biting block of aligner material may explain the nonexistence of a significant vertical dimension increase [ 53 ]. The insignificance of our finding could be interpreted as molar distalization by clear aligners associated with the absence of molar extrusion and clockwise rotation of the occlusal plane in contrast with conventional appliances [ 11 ]. This would lead to premature contact and sudden alteration of temporomandibular components’ relation.…”

“…As this appliance is fixed in place, patient compliance becomes less of an issue, and forces are constantly applied. It accompanies different condylar pathway alterations documented as a consequence of upper molar distalization [ 10 , 11 ].…”