Inadvertent side effects of fixed lingual retainers : An in vitro study

PURPOSE

To better understand the side effects of fixed lingual retainers by means of an in vitro study in a two-tooth model determining the three-dimensional (3D) force-moment components acting at adjacent teeth combined with different composite-wire interfaces.

METHODS

Triple-stranded round retainer wires were embedded in cured disks of flowable composite. At one side the composite-wire interface was untreated and checked to be absolutely fix. At the other side the composite-wire interface was configured as either an isolated compound with (1) petroleum jelly coating, or an adhered compound with (2) no manipulation, (3) ethanol degreasing or (4) ethanol degreasing and rectangular bending of the wire ends. The 3D force-moment components were registered, while the intertooth distance was increased in steps of 0.01 mm leading to increasing tension of the wire. Measurements were repeated after artificially aging the specimens.

RESULTS

Retainer wire specimens with adhered compound (2, 3, 4) showed negative vestibulo-oral moments ranging maximally each between -0.3 and -0.9 Nmm in opposite direction to positive moments of 1.9 Nmm for specimens with isolated compound 1. Significant tipping moments occurred in the group with isolated compound at lower forces than in those groups with adhered compound. Similar effects were observed after artificial aging.

CONCLUSION

Side effects emerge under specific circumstances: an altered adhesive compound combined with the presence of oral forces. Compounds with lost adhesion at the composite-wire interface showed rotational moments in the direction of the wire windings even during low tensile forces similar to those that may occur in clinical settings. Opposite rotational moments leading to unwinding of the wire may occur in cases with adhered compounds at higher tensile forces. Utilization of round triple-stranded retainer wires without bent ends are of higher risk to induce inadvertent side effects.

Patient perceptions and attitudes regarding post-orthodontic treatment changes

OBJECTIVES

To determine patient perceptions and attitudes regarding posttreatment changes at least 2 years after completion of orthodontic treatment.

MATERIALS AND METHODS

A total of 125 patients (75 females, 50 males, aged 22.93 ± 2.98 years) were enrolled at least 2 years after debonding. Participants had either vacuum-formed retainers (VFRs) or bonded retainers (BRs). Posttreatment changes were evaluated digitally by comparing tooth positions at debonding and at least 2 years after debonding. A questionnaire was used to assess patient attitudes. Retainer usage, awareness of relapse, satisfaction with their current occlusion, and whether posttreatment changes were severe enough for them to consider retreatment were investigated.

RESULTS

All patients showed some posttreatment changes in irregularity. Only 74% of patients wearing VFRs and 47.1% of patients wearing BRs were aware of posttreatment changes. Patients were more likely to notice posttreatment changes if there was an increase in mandibular irregularity of 1-3 mm. Awareness of posttreatment changes in the upper arch was higher in both groups. The majority of participants were satisfied with the results even if they noticed some minor posttreatment changes (VFR, 69.4%; BR, 76.5%). Dissatisfaction with posttreatment changes did not necessarily mean that a patient wanted retreatment.

CONCLUSIONS

A total of 26% of patients wearing VFRs and 52.9% of patients wearing BRs were unaware of posttreatment changes. Approximately half of the patients who noticed posttreatment changes were still satisfied with the result 2 years after debonding. Even patients dissatisfied with the effect of posttreatment changes do not necessarily want retreatment.

T2 Fluid-Attenuated Inversion Recovery Imaging of Uveal Melanomas and Other Ocular Pathology

BACKGROUND/AIMS

This study describes patterns of intraocular lesions on T2 fluid-attenuated inversion recovery (FLAIR) imaging, exploring a prospective role of FLAIR imaging sequence in diagnosis and treatment.

METHODS

A retrospective study of orbital magnetic resonance imaging (MRI) studies from the years 2000 to 2015 was performed. MRI sequences included: pre-contrast T1-weighted, T2-weighted, T2 FLAIR, and postcontrast T1 and T2 imaging gadolinium, which were evaluated by a neuroradiologist. Two cases of melanoma were correlated to their pathology.

RESULTS

Twenty-four patients with intraocular pathology were evaluated. All lesions, regardless of pigmentation, revealed previously described melanotic patterns on T1- and T2-weighted images; 80% of 10 melanomas localized were hyperintense on T2 FLAIR, which better delineated lesion margins. All of the four inflammatory pathologies on T2 FLAIR were hyperintense, as were 80% of the amelanotic neoplasms. Pathology of two large uveal melanomas paralleled the findings seen on T2 FLAIR.

CONCLUSIONS

T2 FLAIR appears beneficial in the demarcation of pigmented ocular lesions and may aid in determining protein content or previous treatment. Data also promote previous assertions that blood flow impacts intensity of lesions on T2 FLAIR. Further research is warranted.