The short-term skeleto-dental effects of a new spring for the intrusion of maxillary posterior teeth in open bite patients

Abstract

BackgroundThe technology surrounding temporary skeletal anchorage devices has improved in leaps and bounds. However, no specific auxiliary exists for the intrusion of molars in conjunction with these devices and currently clinicians are forced to make do with available force delivery materials. A new intrusion auxiliary, the Sydney Intrusion Spring (SIS), was designed to facilitate intrusion without frequent need for reactivation or tissue irritation.MethodsThe subjects consisted of 16 adolescent patients (12 females and 4 males) with an average age of 13.1 years (range 12.2 to 14.3 years). All patients were in the permanent dentition with an anterior open bite of ≥2 mm. Four self-drilling miniscrews were placed into the posterior maxillary buccal alveolar bone. The intrusion appliance consisted of a bonded acrylic appliance and the SIS, activated to produce an initial intrusive force of 500 g. Cone beam computed tomograms were taken after miniscrew placement and at the end of active intrusion. Rendered lateral cephalograms were produced and measurements were taken and compared.ResultsAll study objectives were achieved in 4.91 months (range 2.5 to 7.75 months). The mean molar intrusion was 2.9 ± 0.8 mm (P < .001), resulting in over bite increase of 3.0 ± 1.5 mm (P < .001). The intrusion led to a 2.6° ± 1.3° (P < .001) clockwise occlusal plane rotation and a 1.2° ± 1.3° (P < .01) counter-clockwise rotation of the mandible. Dental measurements showed a significant uprighting and elongation of the incisors. There was no significant extrusion of the lower molars.ConclusionThe SIS is an effective appliance for the intrusion of maxillary posterior teeth, in conjunction with miniscrews.

Biochemical and Clinical Assessments of Segmental Maxillary Posterior Tooth Intrusion

“…For our treatment modalities for maxillary posterior tooth intrusion, the force magnitude (as low as 50 g per side) was lower than previously recommended (Table 1) [10–15]. …”

Force magnitude as a variable in maxillary buccal segment intrusion in adult patients with skeletal open bite:

“…A debate in the literature regarding the force magnitude required for effective skeletal anchoragesupported posterior segment intrusion has been reported. 17 Different authors used variable forces and reported different amounts of intrusion. The minimum intrusive force used was 50 g per side, 21 while the more commonly used forces ranged between 100 and 200 g. 13,14,22 On the other hand, Kato and Kato 23 suggested that a force of 100 g was insufficient for posterior segment intrusion and stated that increasing the force up to 300 g permitted progressive intrusion.…”

“…Later, a range of 200 to 400 g for segmental posterior intrusion was suggested. 24 Less commonly, heavier forces were used, ranging from 400 g 16 up to 500 g, [17][18][19] to achieve adequate amounts of intrusion. Since most of these studies used different methodologies, their results could not be compared directly.…”

“…10 The literature is replete with approaches that have been adopted to achieve maxillary buccal segment intrusion with a diversity of skeletal anchorage devices, force delivery systems, and force magnitudes. Despite being not clearly stated in some studies, 8,9,11,12 the reported force magnitudes for maxillary posterior segment intrusion ranged from 150 g [13][14][15] to 500 g. [16][17][18][19] Yet evidence is still lacking with regard to which force magnitude is best to provide the optimum outcomes. 17 The aim of the current study was to compare the effects of two different force magnitudes used for maxillary buccal segment intrusion in terms of the amount of posterior segment intrusion and anterior open bite closure as the primary outcomes.…”

Anterior Open Bite Treatment with Zygomatic Anchorage in Adult Patient: A case report

“…2 Miniscrews can also be used for anterior open bite treat ment. 14,15 Through the use of miniscrews for intrusion of the upper and lower posterior teeth, similar rates of mandibular autorotation can be achieved as miniplates. 16 However miniplates are more reliable compared to the miniscrews because of their distance from tooth roots.…”