Reconstruction of facial morphology from laser scanned data. Part I: reliability of the technique.

OBJECTIVES: The aim of this study was to evaluate the effects of scanning parameters on the precision of the data acquired using a facial laser scanner and to assess the reliability of automatic model recording in humans. METHODS: Data were acquired using a laser scanner (Cyberware 3030RGB); analysis and measurements were performed with Rapid Form 2004 software. A mannequin and six volunteers were scanned to investigate the effects of environmental conditions, positioning, head orientation, and software procedures. Precision and accuracy of the data were evaluated comparing six linear measures calculated on scanned data with those obtained directly. Two sessions with different head inclination were performed. The reliability of repeated scans was also assessed measuring the distance between the surfaces reconstructed from two separate scans of the same subject, at 12 anatomical points, in 5 subjects, during two sessions using a different head inclination. Differences were analysed using paired t-tests or analysis of variance (ANOVA). RESULTS: The accuracy of scanning was +/-0.65 mm. The development of a specific protocol resulted in a mean scanning error of 1-1.2 mm and a recording error of 0.3-0.4 mm on repeated scans of human subjects. CONCLUSIONS: This study indicates that scanning of the human face may be hampered by errors and artefacts, mainly due to movements. While the effect of trembling and involuntary movements during the exam may be minimized using faster scanning devices, comparative observation over time may be affected by unreal differences due to the uncertainty of facial expression. The overall error is, however, in the range useful for most clinical studies.

Transverse maxillary distraction with a bone-anchored appliance: dento-periodontal effects and clinical and radiological results.

In 29 adult patients presenting with maxillary deficiency, a bone-anchored palatal distractor (Surgi-Tec NV, Brugge, Belgium) was applied after osteotomy of the anterolateral walls of the maxillary sinuses, midpalatal suture, and, eventually, separation of the pterygomaxillary sutures. Expansion proceeded at a rate of 0.33-0.66 mm per day and the device was retained for 4-6 months for consolidation. Active orthodontic therapy was started after 8-10 weeks. The increment of arch width and the perimeter were evaluated using dental casts. Tooth thermal sensitivity and the periodontal side effects of treatment were monitored clinically after distraction, at device removal, and after 1 year. Bone healing was also investigated during the procedure using conventional radiological techniques. This experience confirms that transverse maxillary distraction is an effective technique in adult patients, leading to the formation of new bone. There were no noticeable intraoperative complications, but postsurgical periodontal side effects were documented. The procedure offers advantages over traditional teeth-borne appliances in terms of rapidity of treatment and the absence of mechanical forces acting on the teeth. Further evaluation is required to assess the long-term stability and periodontal consequences of this technique.

[Facial anthropometry and aesthetic perception in young italian subjects: their use for orthognatic surgery]. / Antropometria e percezione estetica del volto in un campione di popolazione italiana. Considerazioni ai fini della chirurgia ortognatica.

BACKGROUND: Aesthetic requests of patients undergoing orthognatic surgery have increased over time and represent nowadays the leading subjective motivation for the patient and a major aim of the treatment for the surgeon. In this regard, anthropometric evaluation has considerably improved the diagnostic capacity of the orthodontist and of the surgeon. Aim of the study is to provide the orthognatic surgeon with anthropometric normal values based on a sample of aesthetically pleasant Italian subjects and to discuss the use of a simplified aesthetical analysis in the set-up of the surgical plan and in the evaluation of treatment outcome. METHODS: The present study analyses 94 Italian subjects, by means of anthropometric measurements on photographic images, considering 28 facial proportions and 33 angular values. These figures were compared with the aesthetic judgement provided by 3 common observers and 3 orthodontists. The aesthetic score was attributed on a subjective discrete scale (common observer: above average/average/below average; orthodontist: eumorphic/ dismorphic). Data were also compared with similar evaluations on North-American and African subjects reported in the international literature. RESULTS: This study confirms the sexual dismorphism and the ethnic variability already reported by other Authors and documents specific morphological characters in the Italian population. CONCLUSIONS: The described method appears acceptably simple and consistent for clinical application. Its use in orthognatic surgery may provide objective and reproducible data for evaluating the aesthetic outcome of treatment.

Dimensions and volumes of the orbit and orbital fat in posttraumatic enophthalmos.

OBJECTIVES: To estimate from 2D and 3D-CT the anatomical defects that are most likely to be responsible for posttraumatic enophthalmos. MATERIALS AND METHODS: The morphology and dimensions of the orbit and of fat content were investigated in 25 patients 6-12 months after treatment for complex orbital fractures by image analysis and volumetric estimation from 2D and 3D-CT. RESULTS: The shape of orbit was very often changed from conical to more rounded due to enlargement of the posterior segment. The retrobulbar fat appeared fragmented and dislocated posteriorly. No changes were observed in the structural appearance or radiodensity of either the orbital fat or muscles. There was reduced sagittal eye projection, increased width of the orbital rim, downward dislocation of the posteromedial orbital floor, and increased volume in the posttraumatic orbits which was significantly different (P < 0.05). Enophthalmos was correlated with orbital volume and height of the retrobulbar portion of the orbit. The volume of fat did not correlate with enophthalmos. CONCLUSIONS: Posttraumatic enophthalmos appears to be more commonly related to failure in correcting the orbital volume and in reducing the outward dislocation of the posterior orbital floor and not to changes in the fat content.