Influence of different modeling strategies for the periodontal ligament on finite element simulation results.

Introduction: The finite element method is a promising tool to investigate the material properties and the structural response of the periodontal ligament (PDL). To obtain realistic and reproducible results during finite element simulations of the PDL, suitable bio-fidelic finite element meshes of the geometry are essential.

Methods: In this study, 4 independent coworkers generated altogether 17 volume meshes (3-dimensional) based on the same high-resolution computed-tomography image data set of a tooth obtained in vivo to compare the influence of the different model generation techniques on the predicted response to loading for low orthodontic forces.

Stress distribution and displacement analysis during an intermaxillary disjunction--a three-dimensional FEM study of a human skull.

The goal of this study was to contribute to an understanding of how much expansion force is needed during a maxillary expansion (ME) and where bony reaction takes place. A finite element (FE) model of a dry human male skull was generated from CT scans. The FE model, which consists of cortical and cancellous bone and teeth, was loaded with the same force magnitudes, directions and working points as in rapid maxillary expansion (RME).

Dental care during orthodontic treatment with electric toothbrushes.

Objective: In an in-vitro experimental set-up, we tested the efficacy of different electric toothbrushes in cleaning teeth with a multibracket appliance.

Material And Methods: The efficacy of three sonic and four rotating toothbrushes were compared; the brushes removed artificial plaque from plastic teeth. The amount of removed plaque substitute was determined via a comparative photo-analysis with one picture of the teeth before and one picture after the brushing cycle.

Alignment of displaced or impacted teeth with the traction chain.

To align those teeth in the dental arch that cannot erupt or are displaced, they must be surgically exposed. After the traction device is attached, the tooth is again covered with the mucoperiosteal flap to protect the tissues involved. For this reason, the loss of this traction device must be absolutely avoided in order to prevent another surgical intervention.

Leveling of the second molar with a superelastic spring.

Background: Second permanent molars often erupt during fixed appliance treatment. When they are to be incorporated into the fixed appliance, it is often not possible to bond the buccal tube in the correct position.

Material And Methods: We describe herein a method for aligning second permanent molars by means of a superelastic segmental archwire.

The derotation of premolars and canines with NiTi elements.

Background: Canines or premolars must often be derotated during fixed appliance therapy. If such derotation is carried out on the continuous archwire during the leveling phase, it may lead to unwanted side effects on the neighboring teeth.

Material And Methods: At the University of Ulm a .

Initial results regarding force exertion during rapid maxillary expansion in children.

Aim And Method: We developed a method to measure the forces occurring during rapid maxillary expansion and carried out the University of Ulm rapid maxillary expansion method, similar to that of Chatellier and Chateau, in ten patients.

Results: The forces occurring on the maxilla increased up to 120 N. There was considerable variation in force level from patient to patient.

Dental care with manual toothbrushes during fixed orthodontic treatment--a new testing procedure.

Aim: The aim of this investigation was to employ a new in-vitro testing system for manual toothbrushes in order to distinguish the more effective from those less so for dental care during fixed appliance treatment.

Materials And Methods: The testing apparatus consisted of a sliding carriage able to execute a horizontal brushing movement, and a row of artificial teeth upon which the various toothbrushes were manipulated. The artificial row of teeth was fixed on a sensor that recorded in all three dimensions the forces and moments caused by the toothbrushes on the toothbrush field.