The role of non-contact digitizer in geometrical evaluation of mandibular prostheses effect on facial asymmetry of mandibulectomy patients.

PURPOSE: This study sought to geometrically evaluate the effect of a mandibular prosthesis on facial asymmetry in patients with one of two different types of mandibulectomy defect. METHODS: Facial data from 20 participants (9 men and 11 women; mean age 68 years) with either a reconstructed segmental defect (segmental group,n = 10) or a marginal mandibulectomy defect (marginal group, n =10) were acquired with a non-contact three-dimensional (3D) digitizer. Facial asymmetry was evaluated by superimposing a facial scan onto its mirror scan using 3D evaluation software. Facial scans with and without the mandibular prosthesis in place were also superimposed to evaluate the effect of the mandibular prosthesis. RESULTS: Facial asymmetry differed significantly between subjects with and without the prosthesis in the segmental group (P = 0.005) but not in the marginal group (P = 0.16). There was no significant difference in the effect of the prosthesis on facial appearance between the two groups (P = 0.052). The ratio of 3D deviation of facial asymmetry without the prosthesis and in the mirror scan with the prosthesis differed significantly between the two groups (P = 0.01). CONCLUSIONS: Placement of a mandibular prosthesis has a notable effect on facial asymmetry in patients with segmental mandibulectomy defects.

Morphological comparison of artificial teeth position utilising denture space in glossectomy patients.

OBJECTIVE: This study aimed to compare the denture space of edentulous glossectomy patients with that of a control group from the perspective of artificial teeth positioning by using three-dimensional techniques. BACKGROUND: It is known that the shape of the denture space may be affected by tongue resection or reconstruction. However, the details of artificial teeth positioning in these patients remain unclear. MATERIALS AND METHODS: Six edentulous glossectomy patients aged 73-83 years and six normal participants aged 74-85 years participated in the study. Piezography was used to elucidate the characteristics of the denture space. For visualisation, piezographic records were scanned using cone beam computed tomography and the data were converted into stereolithographic format. Three-dimensional images of piezographic records were then constructed. Bucco-lingual widths of the mandibular occlusal surface were reproduced, and the camber line of the occlusal surface was set so as to simulate the position of the artificial teeth. The maximum chord of the occlusal surface on the left and right sides was recorded and measured. The discrepancy and ratio of the larger chord to the smaller chord between the right and left sides was calculated and subjected to statistical analyses using the Mann-Whitney U test. RESULTS: There were significant differences in discrepancy and ratio between the left and right in the control group and the glossectomy patients (P Ë‚ .01). The glossectomy patients showed a greater discrepancy and ratio than the control group. CONCLUSIONS: The simulated artificial teeth positions on the occlusal surface between the right and left side were asymmetric in glossectomy patients.

Color change of airborne particle-abraded acrylic resin surfaces: A palatography method.

STATEMENT OF PROBLEM: A palatogram aids prosthodontists and speech pathologists in evaluating the precise prosthetic treatment needed and the effectiveness of such treatment to improve speech intelligibility. Powder is commonly used to visualize tongue-palate contact, where wetted areas of powder in the oral cavity reveal such contact during palatography. However, discomfort and the risk of aspiration are among the shortcomings of this method, and an improved method is needed. PURPOSE: The purpose of this in vitro study was to examine the feasibility of a new method of palatography that uses airborne-particle-abraded acrylic resin so that wet areas can be easily distinguished from dry areas. MATERIAL AND METHODS: Seventy-two specimens of heat-polymerized acrylic resin were prepared in 6 different resin colors. After the specimens had been airborne-particle abraded, CIELab color values for each specimen were measured using a colorimeter under dry and wet conditions and recorded. Color difference (ΔE) was then computed, and a paired Student t test, 1-way analysis of variance, and multiple comparison using the Tukey post hoc analysis were applied (α=.05). RESULTS: A significant color difference was found between the 2 conditions in all acrylic resin specimens examined. Mean ΔE ranged from 5.58 to 6.76. CONCLUSIONS: The results indicated that an airborne-particle-abraded acrylic resin surface can show color differences made by wetting on palatograms.

Application of Digital Technologies in Maxillofacial Prosthetics Literature: A 10-Year Observation of Five Selected Prosthodontics Journals.

PURPOSE: To identify trends in the application of various types of digital technologies in maxillofacial prosthetics by identifying these digital technologies and their characteristics and reviewing the prevalence of applied digital technologies and their recent trends in the maxillofacial prosthetics literature. MATERIALS AND METHODS: Five leading peer-reviewed prosthodontics journals were manually searched for maxillofacial prosthetics articles on the use of digital technologies published from January 2008 to December 2017. Descriptive statistics were used to analyze data collected on productivity, type of digital technology used, type of article, type of defect, number of authors, and geographic distribution. RESULTS: Of the 336 maxillofacial prosthetics articles screened, 87 (26%) were selected for analysis. A remarkable increase was found in article productivity in the last 5 years (63%) compared to the first 5 years (37%). There was also a notable increase over the last 10 years in all digital technologies used except for evaluation technologies, which remained almost constant. Case reports most frequently mentioned use of digitization technologies (61%), design technologies (66%), and rapid prototyping technologies (66%). Original research articles most frequently mentioned use of evaluation technologies (89%); 39% of these technologies were used for intraoral defects and 27% for extraoral defects. Most often, articles had four to five authors (54%). Most published articles were from the Asia-Pacific region (44%), followed by North America (22%) and Europe (20%). CONCLUSION: Although the application of digital technologies reported in the maxillofacial prosthetics literature has increased notably in leading prosthodontics journals over the last 10 years, total article productivity has remained relatively small.