Asymmetric nasomaxillary expansion induced by tooth‐bone‐borne expander producing differential craniofacial changes

Abstract

Objectives To evaluate three‐dimensional (3D) craniofacial changes induced by a non‐surgical tooth‐bone‐borne rapid palatal expander (TBB‐RPE) according to the symmetrical pattern of expansion, to investigate the 3D changes between the sides in patients with asymmetric expansion, and to identify the related factors of asymmetric expansion. Setting and sample population Sixty‐six patients (mean age: 19.3 ± 5.7 years) treated with TBB‐RPE were divided into a symmetric expansion group (Group S, n = 46) or asymmetric expansion group (Group A, n = 20). Group S was subdivided into Group Ss (n = 27), with bilateral frontomaxillary suture (FMS) split, and Group Sn (n = 19), with no FMS split. Materials and methods Pre‐ and post‐expansion cone‐beam computed tomography images were superimposed, and the common coordinated system was set. All landmarks were designated as coordinate pairs, and treatment changes were automatically calculated. Analysis of variance was conducted for intergroup comparison of craniofacial changes, and logistic regression analysis was performed to identify the related factors of asymmetric expansion. Results The frequency of asymmetric expansion was 30.3%. Group A with unilateral FMS split showed less craniofacial changes than Group Ss and more changes than Group Sn. Group A exhibited different nasomaxillary displacement between the two halves, showing greater changes in the FMS‐split side. Among the tested six variables (age, gender, Angle's classification, unilateral crossbite, maxillary cant and chin deviation), chin deviation was uniquely associated with asymmetric expansion. Conclusions Tooth‐bone‐borne rapid palatal expander had a risk of asymmetric expansion, especially in facial asymmetric patients with chin deviation, producing different craniofacial changes from symmetric expansion.

Rapid Palatal Expansion Should Not Be Trivialized: Two Case Reports of Unexpected Complications

“…39,40 Nevertheless, the risk of asymmetric expansion is still present, and in a study published by Kim et al, it was found to be 30.3%, without predictive factors, even if it was more frequent in patients with chin deviation. 41 It follows that, regardless of the subject's chronological age, RME is a therapy in which the distraction of the mid-palatal suture is dependent on the patient's skeletal maturity and sutural density, therefore potentially presenting significant undesirable effects if not strictly monitored: RME appliances should always be applied only after a correct diagnosis and a strict follow-up protocol during active expansion should be scheduled. 42…”

Palatal temporary skeletal anchorage devices (TSADs): What to know and how to do?

“…In some cases, asymmetric expansion with unilateral frontomaxillary suture split was reported. 71 In addition to transverse expansion, displacements of nasomaxillary complex (NMC) were accompanied by sagittal and vertical direction. Especially in skeletal Class III with midface deficiency, forward and downward displacement of NMC concurrently with maxillary expansion can be expected after MARPE, which is favourable for the improvement of facial profile and occlusal relationship.…”

“…Especially in skeletal Class III with midface deficiency, forward and downward displacement of NMC concurrently with maxillary expansion can be expected after MARPE, which is favourable for the improvement of facial profile and occlusal relationship. 71 In functional aspect, MARPE can increase nasal airway volume which would be a good treatment modality for OSA patients with nasomaxillary constriction. 72 Besides MARPE, reports on the transverse control of the maxillary dentition with the use of palatal TSADs are scarce.…”

“…The expansion pattern is almost parallel anteroposteriorly, and pyramidal in frontal section. In some cases, asymmetric expansion with unilateral frontomaxillary suture split was reported 71 . In addition to transverse expansion, displacements of nasomaxillary complex (NMC) were accompanied by sagittal and vertical direction.…”

“…In addition to transverse expansion, displacements of nasomaxillary complex (NMC) were accompanied by sagittal and vertical direction. Especially in skeletal Class III with midface deficiency, forward and downward displacement of NMC concurrently with maxillary expansion can be expected after MARPE, which is favourable for the improvement of facial profile and occlusal relationship 71 . In functional aspect, MARPE can increase nasal airway volume which would be a good treatment modality for OSA patients with nasomaxillary constriction 72 …”