1. To record any discrepancies between occlusal relationship at patient’s initial point of contact and at habitual occlusion
2. To record the path of lateral excursive movements of mandible
3. Possibly visualize the orientation of occlusal plane to face
The first reason to mount casts on articulator seems valid. Lateral and anterior shifts are not normal, and an articulator can certainly help recording that but it is not the only way to do so. In majority of cases, as seen in my preclinical ortho seminars, the shift is not big enough to warrant mounting and seldom seem to be affecting the treatment decision. However, for large shifts, mounting casts on articulator can be beneficial- I haven’t witnessed any such cases yet.
The second reason-to record the lateral excursion- seems unreasonable to me. Because teeth position and inclinations; and jaw positions will anyways change during the orthodontic treatment. If multiple restorations are planned at the end of orthodontic treatment, then the use of articulator can be justified towards the end of the treatment. In addition, in the pre-adolescent and adolescent orthodontic patients, which actually is the majority of orthodontic patient population, the contours of the temporo-mandibular joint are still developing. So, it doesn’t make ant sense mounting those cases on articulators because the relationship between teeth and TMJ will change based on the skeletal growth.
On the other hand, it will be beneficial to mount casts of adult patients with existing TMD. Anecdotally, even in the orthodontic preclinical seminars at UBC, I have never seen any instructor requesting mounted casts except for occasional surgical set ups. For some difficult cases, we have done “diagnostic set-up” in which we simulate the final position of the teeth and see if the upper and lower teeth fit together in MIP with good overjet and overbite. Even those diagnostic set casts are not mounted but just handheld.
May be UBC, is a “Articulator-free” orthodontic program and it seems to be working well so far. My hands-on clinical knowledge with the use of articulators in orthodontics is limited or zero so I did some lit search to see what the existing evidence is. I couldn’t find any systematic reviews on the merits of using articulator. Majority of published data is either case reports or expert opinion which falls at the bottom of hierarchy of evidence.
There is one study by Klar et al, which
Having said that, I don’t want to completely rule out the possible use of articulators in orthodontics. As several studies I came across have pointed out the cases which benefitted from the proper diagnosis with the help of mounted casts, there could be some crossbite, functional shift cases and cases with existing TMD where I may consider using articulators but without conclusive scientific evidence, it’s benefits will still be questionable in my head. There is a particular group of orthodontists called “gnathologists” who have been very strong proponents of using articulators in orthodontics.