Two different designs of mini-screw assisted maxillary expanders, using FEM to analyse stress distribution in craniofacial structures and anchor teeth.

OBJECTIVE: 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). MATERIAL AND METHODS: 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 0.2mm. The stress distribution and displacement of various craniofacial structures and anchor teeth were calculated. RESULTS: 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 4.45MPa. While it was 0.7MPa 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. CONCLUSIONS: 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.

A New Proposal: a Digital Flow for the Construction of a Haas-Inspired Rapid Maxillary Expander (HIRME).

Maxillary expansion is a common orthodontic treatment used for the correction of posterior crossbite resulting from reduced maxillary width. Transverse maxillomandibular discrepancies are a major cause of several malocclusions and may be corrected in different manners; in particular, the rapid maxillary expansion (RME) performed in the early mixed dentition has now become a routine procedure in orthodontic practice. The aim of this study is to propose a procedure that reduces the patient cooperation as well as the lab work required in preparing a customized Haas-inspired rapid maxillary expander (HIRME) that can be anchored to deciduous teeth and can be utilized in mixed dentition with tubes on the molars and hooks and brackets on the canines. This article thus presents an expander that is completely digitally developed, from the first moment of taking the impression with an optical scanner to the final solidification phase by the use of a 3D printer. This digital flow takes place in a CAD environment and it starts with the creation of the appliance on the optical impression; this design is then exported as an stl extension and is sent to the print service to obtain a solid model of the device through a laser sintering process. This "rough" device goes through a post-processing procedure; finally, a commercial expansion screw is laser-welded. This expander has all the advantages of a cast-metal Haas-type RME that rests on deciduous teeth; moreover, it has the characteristic of being developed with a completely digitized and individualized process, for the mouth of the young patient, as well as being made completely of cobalt-chrome, thus ensuring greater adaptability and stability in the patient's mouth.

The ideal insertion angle after immediate loading in Jeil, Storm, and Thunder miniscrews: A 3D-FEM study.

OBJECTIVE: The miniscrew is effectively used to provide additional anchorage for orthodontic purposes. The aim of this study was to identify an optimal insertion angle for Jeil, Storm, and Thunder miniscrews on stress distribution at the bone miniscrew interface. MATERIALS AND METHODS: To perform 3-dimensional finite element model analysis, a 3-dimensional model with a bone block was constructed with type D2 of bone quality, and with miniscrews of Storm, Thunder, Jeil, with the diameter of 2, 1.5. 1.6mm and length 15.9, 12.4, 14.4mm respectively. The miniscrews were inserted at 15° 30°, 45°, 60°, 75° and 90° to the bone surface. A simulated horizontal orthodontic force of 200 gram was applied to the centre of the miniscrews head in all models, and stress distribution and its magnitude were evaluated with a 3-dimensional finite element analysis program. RESULTS: In the cancellous bone, minimum stress was found at placement angles of 90° for Jeil and Storm, which was 0.37 and 0.39MPa respectively, and 15° for Thunder, which was 0.85MPa. The maximum von Mises stresses in the cancellous bone for Jeil was at 60°, which was 0.92MPa, and for Thunder at 90°, which was 1.3MPa. CONCLUSION: Each miniscrew has an ideal insertion angle, optimal insertion positions were found within 90° for Jeil and for Storm but 15° for Thunder. Clinical significance 3-dimensional finite element analysis confirmed that each miniscrew has an ideal insertion angle according to its characteristics.

Four TADs supported Herbst mechanics: A case report.

The Herbst appliance (HA) is considered an efficient method to treat class II malocclusion characterized by mandibular retrusion. Nevertheless, HA is although hampered by side effects reducing its therapeutic potentialities. The association between HA and TADs in the lower arch has proved to be very effective in controlling lower incisor flaring. This case report shows that the insertion of TADs in both arches offers a satisfactory control of the vertical dimension, by avoiding a maxillary clockwise inclination.

Bone-anchored intermaxillary elastics in an asymmetric Class II malocclusion: A case report.

PURPOSE: A 13-year-old male patient, presenting a Class II, division 1 malocclusion and crowding was treated by an innovative technique. METHODS: After rapid palatal expansion by a Hyrax appliance, the teeth were bonded with straightwire brackets. Two miniscrews were inserted, one per side, in the mandibular buccal bone between the roots of the mandibular first molar and the second premolar. On the right side, the miniscrew implant was connected to the hook clamped on a 0.021×0.028″ SS wire with a twisted SS ligature in order to maintain the inclination of the frontal incisors during the Class II mechanics. On the left side, where the Class II relationship was more marked, intermaxillary elastics were applied from the upper left hook clamped on the archwire to the lower first molar and a power chain (100g) was stretched from the lower left hook to the miniscrew implant. Class II correction was accomplished using sequential Class II elastics of progressive strength coupled with rectangular stainless steel wires. RESULTS: After 22 months of active treatment, the results were balanced facial esthetics and a good occlusion. CONCLUSIONS: This dual anchorage set-up of Class II elastics reinforced with TADs produced protrusive action on the mandible with minimal side effects and with no significant change in the vertical dimension during the sagittal correction of the Class II malocclusion.

Light-force technique for the early treatment of an ectopic tooth.

Free crown tipping can be useful when teeth do not erupt in their physiologic sequence and a real intraosseous migration and eruption of a single tooth into a distant ectopic position can be observed. This article presents a case of an ectopic mandibular lateral incisor treated early, with the light-force technique and uncontrolled forces, and finished with the bidimensional edgewise appliance. A Caucasian female patient, 10 years 10 months of age, had a mandibular left lateral incisor displacement, with the lateral incisor crown positioned mesial to left second primary molar. An early treatment was planned to correct the mandibular left lateral incisor displacement and to allow proper eruption of the mandibular left canine and first premolar. A second phase of treatment, in permanent dentition, was planned for the dental Class II subdivision on the right and deep bite correction. Phase 1 treatment was completed after 10 months; phase 2 treatment was initiated in the permanent dentition and lasted 18 months. Treatment achieved the following outcomes: (1) mandibular lateral incisor in corrected position; (2) full canine and molar Class I relationship; (3) overjet and overbite within the normal limits; (4) symmetric arches; and (5) a balanced profile. The radiograph evaluation revealed good root parallelism and mandibular left lateral incisor light root resorption. The light-force technique is not only a possible alternative but the ideal appliance for treatment in the mixed dentition, when the permanent teeth should be controlled.