Three dimensional laser scan assessment of the Oriental nose with a new classification of Oriental nasal types.

The Oriental nose, which has been broadly classified as mesorrhine, differs in anatomy and morphology from other racial groups. The objective of this study is to carry out anthropometric measurements in the nose region, in order to establish norms for the Oriental nose and also to identify the variations that might occur within this group. Knowledge of the unique shape, anatomy and dimensions of the Oriental nose would be very useful for surgeons undertaking repair and reconstruction of Oriental noses. Ninety, normal Oriental subjects were scanned using a laser surface scanner, and the assessments were then carried out on the laser scan images. The 3-D laser scan images permit adjustment and positioning to achieve the correct standard views for assessment. Subjective assessment of the nose shape, as well as linear and angular measurements were carried out. Depending on the fullness and roundness of the nasal tip and the prominence of the alar lobules on either side, the Oriental nasal base may take on varied shapes and accordingly, three distinct shapes have been identified. They have been classified into types A, B and C where type A has a very prominent alar lobule and a full and rounded nasal tip. In type B, the alar lobule was less prominent and the nasal tip was more defined while in type C the alar lobule was the least prominent resulting in the lateral walls forming a relatively straight slope from the tip to the alar base. The linear and angular measurements for Oriental noses were also obtained and compared to values for other racial groups. The proportion indices for the Oriental nose showed that it was broader in relation to the nose height, and had less tip protrusion in relation to both the height and width of the nose. The data collected from this study can be used as norms for Oriental cases and the simple classification of the nose shape will serve as a guide for quick reference, when planning aesthetic or reconstructive rhinoplasties for the Oriental patient.

The role of laser surface imaging in the evaluation of craniomaxillofacial disorders: the Singapore General Hospital experience.

The medical profession today, has the choice of many imaging techniques for documenting, investigating, assessing or planning treatment. Amongst them, the laser surface imaging system is emerging as a useful tool to capture and store digital data for reformatting into a three-dimensional computer model. The laser scanning system captures only the surface morphology of a subject, and is highly appropriate for the evaluation of surface morphological changes of craniofacial disorders. Although originally acquired for the study of facial anthropometry, many other clinical uses have been found for the scanner and this paper describes our experience with the laser scanner in our department. These include archival, preoperative assessments, projective linear and surface measurements, area measurements, comparative analysis, planning and prediction of surgical outcomes, and in the fabrication of physical models and external prostheses.

Selective laser sintering: application of a rapid prototyping method in craniomaxillofacial reconstructive surgery.

Advances in technology have benefited the medical world in many ways and a new generation of computed tomography (CT) scanners and three-dimensional (3-D) model making rapid prototyping systems (RPS) have taken craniofacial surgical planning and management to new heights. With the development of new rapid prototyping systems and the improvements in CT scan technology, such as the helical scanner, biomedical modelling has improved considerably and accurate 3-D models can now be fabricated to allow surgeons to visualise and physically handle a 3-D model on which simulation surgery can be performed. The principle behind this technology is to first acquire digital data (CT scan data) which is then imported to the RPS to fabricate fine layers or cuts of the model which are gradually built up to form the 3-D models. Either liquid resin or nylon powder or special paper may be used to make these models using the various RPS available today. Selective laser sintering (SLS), which employs a CO2 laser beam to solidify special nylon powder and build up the model in layers is described in this case report, where a 23-year old Chinese female with panfacial fracture and a skull defect benefited from SLS biomodelling in the preoperative workup.

Evaluation of the laser scanner as a surface measuring tool and its accuracy compared with direct facial anthropometric measurements.

The development of new laser scanning techniques enabling the capture of 3-D images which can be quantitatively assessed permits their use for surface measurements of the face. We used a laser optical surface scanner to study 30 subjects and took 83 facial anthropometric measurements, using 41 identifiable landmarks on the scanned image. These were compared to the standard anthropometric measurements using the same landmarks. Of these, 12 (14.0%) showed a mean difference less than 1.0 mm and were considered highly reliable measurements and 16 (19.0%) with less than 1.5 mm difference were considered reliable. The highly reliable measurements were mainly in the nasal and circumoral regions and the landmarks involved were mainly those in the mid-saggital plane. This indicates that the laser scanner can be a useful tool for rapid facial measurements in selected anatomical parts of the face. Accurate location of landmarks and operator skill are important factors to achieve reliable results.