Non-compliant upper molar distalization, pros and cons of different mechanics using palatal mini-implants.

A treatment objective of upper molar distalisation may often be indicated for the correction of a dentoalveolar Class II malocclusion with an associated increased overjet and/or anterior crowding. Due to aesthetic concerns and the duration of treatment, molar distalisation using headgear is unacceptable for many patients. This has resulted in a preference for purely intraoral distalisation appliances which require minimal patient cooperation. Unfortunately, most conventional devices for non-compliance maxillary molar distalisation produce unwanted side effects, such as anchorage loss. If the anchorage unit includes teeth, mesial migration and/or protrusion of the anterior dentition need to be considered as major disadvantages. To minimise or eliminate anchorage loss related to the anterior teeth, skeletal anchorage has been integrated into distalisation appliances. The anterior palate has proved to be an ideal site for miniscrew placement for the distalisation of upper teeth. The good bone quality, the attached mucosa, and the minimal risk of injury to nearby teeth have been suggested as major advantages of miniscrew placement in this region. Furthermore, the mini-implants are unlikely to be in the path of tooth movement. Skeletal anchorage mechanics can be divided in direct and indirect appliances. If the maxillary molars are to be distalised, direct anchorage is advantageous, since a major disadvantage of devices employing indirect anchorage is the need for a two-phase clinical procedure: (a) distalisation of the molars, and (b) stabilisation of the molars while retraction of the anterior dental segment occurs. To benefit from the advantages of direct anchorage mechanics and use the anterior palate as the most suitable mini-implant insertion site, the Beneslider and the Pendulum B mechanics may be employed.