Soft tissue morphology of the naso-maxillary complex following surgical correction of maxillary hypoplasia

Orthognathic surgery is undergone to improve facial and dental aesthetics and to improve function. Three dimensional (3D) soft tissue analysis based on stereophotogrammetry provides a realistic measurement of facial morphology. There is a need for objective assessment of surgery outcomes. The study aim was to evaluate the 3D naso-maxillary complex soft tissue morphology following Le Fort I maxillary advancement and compare the findings with a local reference group. 3D images of 112 volunteers were captured using stereophotogrammetry and viewed by 8 lay people; 40 images (16 males and 24 females) were chosen as the reference group to have harmonious facial appearance. The linear and angular measurements of this group were compared with 35 patients (19 female and 16 male) who had maxillary advancement in the post-surgical group. Facial morphology post-surgery was similar to the reference group, except the nasal base width which was wider by 2.3mm in males and 2.6mm in females. In the orthognathic group, the females had a smaller nasolabial angle by 9.7° than the reference group. In conclusion, 3D imaging is a sensitive tool for analysing facial appearance. Compared with a control group, statistical differences were identified in soft tissue morphology which should be considered in surgical planning and patient consent.     

Crystal structure of IgE bound to its B-cell receptor CD23 reveals a mechanism of reciprocal allosteric inhibition with high affinity receptor Fc{varepsilon}RI

The role of IgE in allergic disease mechanisms is performed principally through its interactions with two receptors, FcεRI on mast cells and basophils, and CD23 (FcεRII) on B cells. The former mediates allergic hypersensitivity, the latter regulates IgE levels, and both receptors, also expressed on antigen-presenting cells, contribute to allergen uptake and presentation to the immune system. We have solved the crystal structure of the soluble lectin-like "head" domain of CD23 (derCD23) bound to a subfragment of IgE-Fc consisting of the dimer of Cε3 and Cε4 domains (Fcε3-4). One CD23 head binds to each heavy chain at the interface between the two domains, explaining the known 2:1 stoichiometry and suggesting mechanisms for cross-linking membrane-bound trimeric CD23 by IgE, or membrane IgE by soluble trimeric forms of CD23, both of which may contribute to the regulation of IgE synthesis by B cells. The two symmetrically located binding sites are distant from the single FcεRI binding site, which lies at the opposite ends of the Cε3 domains. Structural comparisons with both free IgE-Fc and its FcεRI complex reveal not only that the conformational changes in IgE-Fc required for CD23 binding are incompatible with FcεRI binding, but also that the converse is true. The two binding sites are allosterically linked. We demonstrate experimentally the reciprocal inhibition of CD23 and FcεRI binding in solution and suggest that the mutual exclusion of receptor binding allows IgE to function independently through its two receptors.     

The definitions of three‐dimensional landmarks on the human face: an interdisciplinary view

The analysis of shape is a key part of anatomical research and in the large majority of cases landmarks provide a standard starting point. However, while the technology of image capture has developed rapidly and in particular three‐dimensional imaging is widely available, the definitions of anatomical landmarks remain rooted in their two‐dimensional origins. In the important case of the human face, standard definitions often require careful orientation of the subject. This paper considers the definitions of facial landmarks from an interdisciplinary perspective, including biological and clinical motivations, issues associated with imaging and subsequent analysis, and the mathematical definition of surface shape using differential geometry. This last perspective provides a route to definitions of landmarks based on surface curvature, often making use of ridge and valley curves, which is genuinely three‐dimensional and is independent of orientation. Specific definitions based on curvature are proposed. These are evaluated, along with traditional definitions, in a study that uses a hierarchical (random effects) model to estimate the error variation that is present at several different levels within the image capture process. The estimates of variation at these different levels are of interest in their own right but, in addition, evidence is provided that variation is reduced at the observer level when the new landmark definitions are used.     

Investigations into the use of an ultrasonic chisel to cut bone. Part 1: Forces applied by clinicians

OBJECTIVES: To measure in vitro the direction and force of applied loads applied by clinicians when using both a conventional slow surgical handpiece (CH) and an ultrasonic chisel (USC) for cutting bone. STUDY DESIGN: Five clinicians were asked to cut bovine bone using either an USC or a CH. The bone was placed on a force measurement system that could measure both longitudinal and downward loads. The rate of cut was calculated over a fixed time-period and the depth of cut measured using a penetratometer. RESULTS: The magnitude of the longitudinal forces generated varied between 1.48 and 3.22 N (USC) and 0.04 and 4.56 N (CH). The CH had a pulling force directed towards the operator. Both instruments produced a similar range of downward forces although there was intra- and inter-operator variability. The rate of cut varied in a similar manner, however, the CH produced a significantly greater depth of cut (p < 0.05). CONCLUSIONS: The force measurement system demonstrated differences in the way clinicians used the USC and CH instruments to cut bone. Of the two cutting methods investigated, the rotary bur is more efficient than the ultrasonic chisel. An ultrasonic chisel does cut bone in a different manner from a conventional bur and clinicians may require training before using it clinically.     

An in-vitro study to assess the feasibility,validity and precision of capturing oncology facial defects with multimodal image fusion

Aim

Assess the feasibility, validity and precision of multimodal image fusion to capture oncology facial defects based on plaster casts.

The validity of a computer-assisted simulation system for orthognathic surgery (CASSOS) for planning the surgical correction of class III skeletal deformities: single-jaw versus bimaxillary surgery

The aim of this study was to assess the accuracy of the two-dimensional profile prediction produced by the computer-assisted simulation system for orthognathic surgery (CASSOS), for the correction of class III facial deformities. Correction was by maxillary advancement (n=17) or bimaxillary surgery (n=16). The mean age was 24 years (range 18-42). The surgical and dental movements obtained from the postoperative cephalogram were used to produce a CASSOS profile prediction, which was compared with the soft-tissue profile. The prediction was superimposed onto the postoperative radiograph, and a coordinate system was used to measure linear differences. For the maxillary advancement group there were statistical differences for three horizontal landmarks: superior labial sulcus (p=0.017), labrale superious (p=0.038) and labiomental fold (p=0.014). In the bimaxillary group only the landmark vertical labrale superious (p=0.002) showed a statistical difference. Generally, CASSOS produced useful profile predictions for maxillary advancement surgery or bimaxillary surgery for Class III patients, although there was considerable individual variation. The main areas of inaccuracy were the lips. The major difference between the two types of surgery was that most of the errors in the maxillary surgery group were in the horizontal direction, whilst for the bimaxillary surgery the errors were mainly in the vertical direction.     

Comprehensive analysis of soft tissue changes in response to orthognathic surgery: mandibular versus bimaxillary advancement

This study was performed to compare soft tissue changes in response to mandibular and bimaxillary advancement osteotomy. Preoperative and postoperative cone beam computed tomography scans of 24 cases were analysed: 12 underwent bimaxillary advancement and 12 underwent mandibular advancement. The skeletal surgical movements were measured and soft tissue changes were displayed on a three-dimensional colour map. The intensity and shade of the colour indicated the magnitude and direction of the changes. In the bimaxillary advancement group, maxillary advancement was 5.5 ± 2.7 mm with anterior vertical impaction of 2.7 ± 2.5 mm; mandibular advancement was 4.6 ± 3.2 mm. Most of the mediolateral soft tissue changes were limited to the anatomical boundaries of the paranasal region – the columella together with the alar bases of the nose; these showed clear forward movement, which extended to involve most of the cheeks. In the mandibular surgery group, the mean advancement was 3.5 ± 2.6 mm. The chin region, lower lip, and inferior parts of the cheek showed forward shift with minimal changes at the vermilion border, which was only displaced in an upward direction. In conclusion, dense anatomical correspondence is a clinically meaningful method of producing a visual comprehensive analysis of the changes in response to orthognathic surgery.     

Amino acid ester prodrugs of the antiviral agent 2-bromo-5,6-dichloro-1-(beta-D-ribofuranosyl)benzimidazole as potential substrates of hPEPT1 transporter

Amino acid ester prodrugs of 2-bromo-5,6-dichloro-1-(beta-d-ribofuranosyl)benzimidazole (BDCRB) were synthesized and evaluated for their affinity for hPEPT1, an intestinal oligopeptide transporter. Assays of competitive inhibition of [(3)H]glycylsarcosine (Gly-Sar) uptake in HeLa/hPEPT1 cells by the amino acid ester prodrugs of BDCRB suggested their 2- to 4-fold higher affinity for hPEPT1 compared to BDCRB. Further, promoieties with hydrophobic side chains and l-configuration were preferred by the hPEPT1 transporter.