Original article

Cranioskeletal displacements caused by rapid palatal expansion in the rhesus monkey

Untruths and distortion of scientific findings inhabit the medical and dental fields, not intentionally but often because of the lack of firm evidence. The aim in this paper is to visit a common orthodontic treatment modality, palatal expansion, and explore whether the accumulated biologic and mechanical findings are sufficient or misinterpreted for proper intervention. Specifically, questions are raised regarding the sutural response to maxillary widening in relation to the age-related changes in the morphology of the suture. The fractures occurring when expansion of a heavily interdigitated suture is performed and the healing that leads to its closure may impede the sutural pubertal growth spurt. Later widening of the arch width, even when surgically assisted, may lead to a bony relapse and severe bony dehiscence of the lateral teeth. Extensive research is needed to help generate appropriate guidelines for palatal expansion especially the age of the patient, timing and amount of expansion, duration of retention, and factors related to maintenance of the treatment results.

The objective of this study was to analyze the short-term and long-term effects of miniscrew-assisted rapid palatal expansion (MARPE) and conventional rapid palatal expansion (RPE) appliances on cranial and circummaxillary sutures as compared with a matched control group.

One hundred and eighty cone-beam computed tomography scans for 60 subjects were evaluated for the 3 groups: (1) MARPE (n = 20; aged 13.7 ± 1.74 years), (2) RPE (n = 21; age 13.9 ± 1.14 years), and (3) control (n = 19; age 13.3 ± 1.49 years) at pretreatment (T1), postexpansion (T2), and posttreatment (T3) (T1 to T3: MARPE, 2 years 8 months; RPE, 2 years 9 months; control, 2 years 7 months). Frontonasal suture, frontomaxillary suture, zygomaticomaxillary suture, zygomaticofrontal suture, intermaxillary suture, pterygomaxillary suture, nasomaxillary suture, and zygomaticotemporal suture were measured on the right and left sides for all 3 time labels. In addition, midpalatal suture was measured at the incisor, canine, and molar levels.

Within-group analysis showed that MARPE and RPE led to a significant increase in the widths of frontonasal, frontomaxillary, intermaxillary, nasomaxillary, and midpalatal suture at incisor, canine, and molar levels at T2 compared with T1. Between-group analysis showed that MARPE and RPE significantly increased the width of the intermaxillary and midpalatal suture at the incisor, canine, and molar compared with controls at T2. In the long term, between-group comparisons showed no significant difference among the 3 groups except that MARPE led to a significant increase in the width of midpalatal suture at incisor, canine, and molar levels compared with RPE and controls at T3.

MARPE led to a significant increase in the width of the midpalatal suture at incisor, canine, and molar levels compared with RPE and controls in the long term. There was no difference in the width of other cranial and circummaxillary sutures among the 3 groups in the long term.

The objective of this study was to analyse the displacement, strain, and stress distribution of various craniofacial structures after applying maxillary expansion with two different bone-borne Haas-inspired miniscrew-assisted maxillary expander (BB HIMAME) and bone-tooth-borne miniscrew-assisted rapid palatal expander (BTB MARPE) using three-dimensional finite element analysis (3D FEA).

two expanders including bone-anchored maxillary expander and bone tooth-borne were designed to simulate expansion in a 3D FEA. Expanders were activated transversely for 0.2 mm. The stress distribution and displacement of various craniofacial structures and anchor teeth were calculated.

The finding showed that the amount of stress in all sutures was greater in BB than BTB expander. The greatest stress was induced in the fronto-maxillary suture in the BB expander, which was 4.45 MPa. While it was 0.7 MPa in BTB. Anchor tooth showed tipping movement in BTB expander, although the crown and apex of the anchor tooth moved in the same direction with BB device.

It is recommended that the BB expander is used when bodily movement of anchor tooth is needed. BTB may serve as an effective modality for cases with low-quality bone conditions. BTB appliance creates some extent of tipping on anchor teeth.

Our objectives were to evaluate midfacial skeletal changes in the coronal plane and the implications of circummaxillary sutures and to localize the center of rotation for the zygomaticomaxillary complex after therapy with a bone-anchored maxillary expander, using high-resolution cone-beam computed tomography.

Fifteen subjects with a mean age of 17.2 ± 4.2 years were treated with a bone-anchored maxillary expander. Pretreatment and posttreatment cone-beam computed tomography images were superimposed and examined for comparison.

Upper interzygomatic distance increased by 0.5 mm, lower interzygomatic distance increased by 4.6 mm, frontozygomatic angles increased by 2.5° and 2.9° (right and left sides), maxillary inclinations increased by 2.0° and 2.5° (right and left sides), and intermolar distance increased by 8.3 mm (P <0.05). Changes in frontoethmoidal, zygomaticomaxillary, and molar basal bone angles were negligible (P >0.05).

A significant lateral displacement of the zygomaticomaxillary complex occurred in late adolescent patients treated with a bone-anchored maxillary expander. The zygomatic bone tended to rotate outward along with the maxilla with a common center of rotation located near the superior aspect of the frontozygomatic suture. Dental tipping of the molars was negligible during treatment.

This article describes the combined use of maxillary expansion and a protraction facemask in the correction of a skeletal Class III malocclusion after the patient's pubertal growth spurt. Treatment efficacy and the effects on facial and smile esthetics are presented. The nonextraction option with an arch-size increase and stability issues is discussed.

Surgically assisted rapid maxillary expansion (SARME) is an effective and stable method for treating severe maxillary transverse discrepancies in skeletally mature individuals, but it has potential complications. The authors report the case of a 34-year-old woman who developed carotid cavernous fistula after undergoing SARME with a bone anchored appliance and discuss the possible etiological basis of this condition.