Distance-dependent accuracy in Le Fort I maxillary repositioning procedures.

It has been hypothesised that, in maxillary repositioning procedures, longer distances correlate with less accurate transfers and particularly the repositioning forces of facial skin and muscles that increase exponentially. However, this has not to our knowledge been confirmed. The purpose of this study was to search for differences in the accuracy of transfer from maxillary repositioning procedures parallel to the three orthogonal planes and with respect to three different anatomical landmarks of the first molar left and right (M1L and M1R) and the first incisor (I). Cone-beam computed tomography (CT) datasets taken before and after operation for 92 patients who had Le Fort I maxillary repositioning procedures were aligned to measure the changes in the maxillary position in the axial, sagittal, and transverse directions. Differences between planned distances and those achieved were calculated and analysed with Pearsons correlation coefficient. The strongest significant correlations between the extent of planned repositioning distances and achieved differences (error) were detected in the sagittal plane for the anatomical landmarks of the right (M1R) and left first molar (M1L). Correlations became weaker if a limited planned distance ranging from 0-4mm was compared with a complete observed range that reached up to 12mm. Our results show for the first time to our knowledge that the accuracy of transfer of wafer-based maxillary positioning procedures depends on the distance being moved. Longer distances correlate with less accuracy, particularly in the sagittal plane and in the first molar region.

Three-dimensional fracture pattern analysis of the Obwegeser and Dal Pont bilateral sagittal split osteotomy.

The Obwegeser and Dal Pont modification of the bilateral sagittal split osteotomy (BSSO) is a well-established procedure in orthognathic surgery. The purpose of this retrospective study was to analyze the actual fracture patterns achieved with BSSO by Obwegeser and Dal Pont modification using postoperative cone beam computed tomography (CBCT) datasets from 100 patients. A total of 200 split osteotomies were assessed, which could be categorized into nine different split patterns. Only one of the observed split fractures (0.5%) followed exactly the fracture line described by Obwegeser and Dal Pont, whereas 40% followed the fracture line according to the Hunsuck and Epker modification and 13.5% were seen as unfavourable splits mainly running over the buccal plate. A significant correlation was found between unfavourable buccal splits and both horizontal osteotomies reaching the buccal surface at the dorsal ramus (P=0.001) and a vertical caudal bone cut end at the corpus with a buccal position (P<0.001). These results show that a complete antero-posterior horizontal osteotomy at the mandibular ramus does not lead to the intended fracture pattern, which rebuts the argument of a greater amount of bony overlap using the Obwegeser and Dal Pont modification.

Assessment of iron stores in old people.

Iron deficiency is the commonest cause of anaemia in the old. Anaemia is a useful indicator of morbidity, occurring much more frequently in individuals referred to hospital. Isolated serum iron estimations are often misleading. A study of 34 cases in whom serum iron, iron-binding capacity and bone marrow were examined showed that the percentage saturation of the binding capacity remains a good method of assessing iron stores.