Three-dimensional facial morphometry in patients rehabilitated with implant-supported prostheses

The aim of the present study was to assess a low-cost, non-invasive facial morphometric digitizer to assist the practitioner in three-dimensional soft-tissue changes before and after oral rehabilitation. The method should provide quantitative data to support an objective assessment of the facial esthetic outcome [1]. Twenty-two patients aged 45-82 years, all with edentulous maxilla and mandible, were assessed both before and after receiving their definitive complete implant-supported prostheses (each received 4-11 implants in each dental arch; full-arch fixed prostheses were made). The three-dimensional coordinates of 50 soft-tissue facial landmarks were collected with a non-invasive digitizer; labial and facial areas, volumes, angles and distances were compared without/ with the prostheses [2]. Dental prostheses induced significant reductions in the nasolabial, mentolabial and interlabial angles, with increased labial prominence (p<0.05, Wilcoxon test). Lip vermilion area and volume significantly increased; significant increments were found in the vertical and anteroposterior labial dimensions. The presence of the dental prostheses significantly (p<0.001) modified the three-dimensional positions of several soft-tissue facial landmarks. The current approach enabled quantitative evaluation of the final soft-tissue results of oral rehabilitation with implant-supported prostheses, without submitting the patients to invasive procedures. The method could assess the three-dimensional appearance of the facial soft tissues of the patient while planning the provisional prosthetic restoration, providing quantitative information to prepare the best definitive prosthesis. Dote ricerca: FSE, Regione Lombardi

A 3D non invasive assessment of the position of the occlusal plane

Introduction. The occlusal plane has a key-role in various dental and medical fields. Several methods have analyzed and measured the relative positions of the occlusal and facial planes; most of these investigations used 2D radiographic exams. Currently, 3D assessments may be performed overlapping CT reconstructions and digitized dental casts, but the method requires ionizing radiations, and it is not applicable in reference studies performed with healthy subjects. The efficacy of these measurements could be improved by a 3D, non invasive approach to the problem. Methods. 20 healthy subjects were selected to have their maxillary dental casts digitized by laser scanning, and their 3D facial soft tissue stereophotogrammetry acquisition merged in a single file. The digital 3D coordinates of three facial (right and left Tragus, Subnasale) and three dental landmarks (inter-incisor, tips of the mesio-vestibular cuspids of right and left first permanent molars), were obtained and exported in a 3D CAD (computed aided design) software for a geometrical analysis. The 3D orientation of the planes, referred to a Cartesian orthogonal reference system, was estimated calculating angular values between the sagittal midlines of the two planes. To evaluate the repeatability of the measurements the protocol was performed independently by two different operators. In total 120 measurements were obtained; descriptive statistics were calculated for each variable. To evaluate the method repeatability mean absolute difference between repeated measurements (MAD), technical error of measurement (REM) and Paired Student’s T tests (P<0.05) were computed. Results. In the frontal and horizontal projections, the occlusal plane resulted nearly parallel to Camper’s plane, with average inclinations of 1.5 (frontal) and 1.9 (horizontal) degrees. In the sagittal projection, the two planes had an average angle of 4.9 degrees, with the occlusal plane more anteriorly inclined than Camper’s plane. For all three projections, a fair inter-operator repeatability was found, with all MADs and TEMs slightly lower than 2 degrees. No systematic errors between repeated measurements were found (T test > 0.05). Conclusions. The current non-invasive method resulted appropriate to the aims. Camper’s and occlusal planes resulted almost parallel in the frontal and horizontal projections, while in the sagittal projection the occlusal plane was 5 degrees more anteriorly inclined than Camper’s plane