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Orthodontic tooth movement is achieved by (re)modeling processes of the alveolar bone, which are triggered by changes in the stress/strain distribution in the periodontium. In the past, the finite element (FE) method has been used to describe the stressed situation within the periodontal ligament (PDL) and surrounding alveolar bone. The present study sought to determine the impact of the modeling process on the outcome from FE analyses and to relate these findings to the current theories on orthodontic tooth movement. In a series of FE analyses simulating teeth subjected to orthodontic loading, the influence of geometry/morphology, material properties, and boundary conditions was evaluated. The accurate description of alveolar bone morphology and the assignment of non-linear mechanical properties for the PDF elements demonstrate that loading of the periodontium cannot be explained in simple terms of compression and tension along the loading direction. Tension in the alveolar bone was far more predominant than compression.

Upper airway cannot be accurately expressed by single linear measurements as performed on cephalograms. The TV alone does not depict the morphology of the airway. A CBCT-based 3D analysis gives a better picture of the anatomical characteristics of the upper airways and therefore can lead to an improvement of the diagnosis.

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The healing around an immediately loaded screw was described and related to the bone type, manner of loading and observation time. In four adult macaca fasicularis monkeys, 16 titanium vanadium screws were inserted into the infrazygomatic crest and two in the symphysis region. Immediately after insertion, screws were loaded with 25‐ and 50‐g Sentalloy springs extending to the canines. Following an observation period of 1, 2, 4 and 6 months, the screws and the surrounding bone were removed. Undecalcified serial sections perpendicular to the long axis were made and the degree of osseointegration studied. Two of the screws were lost immediately after insertion. Of the remaining screws, osseointegration was present around all, but two. The integration was independent of bone type, trabecular or cortical, but increased with time. Based on the results of this study, the use of screws described in the report can be recommended as anchorage units in cases where conventional anchorage is not possible.