Three-dimensional technology for documentation and record keeping for patients with facial clefts

Polymers in 3D printing of external maxillofacial prostheses and in their retention systems

Maxillofacial defects, arising from trauma, oncological disease or congenital abnormalities, detrimentally affect daily life. Prosthetic repair offers the aesthetic and functional reconstruction with the help of materials mimicking natural tissues. 3D polymer printing enables the design of patient-specific prostheses with high structural complexity, as well as rapid and low-cost fabrication on-demand. However, 3D printing for prosthetics is still in the early stage of development and faces various challenges for widespread use. This is because the most suitable polymers for maxillofacial restoration are soft materials that do not have the required printability, mechanical strength of the printed parts, as well as functionality. This review focuses on the challenges and opportunities of 3D printing techniques for production of polymer maxillofacial prostheses using computer-aided design and modeling software. Review discusses the widely used polymers, as well as their blends and composites, which meet the most important assessment criteria, such as the physicochemical, biological, aesthetic properties and processability in 3D printing. In addition, strategies for improving the polymer properties, such as their printability, mechanical strength, and their ability to print multimaterial and architectural structures are highlighted. The current state of the prosthetic retention system is presented with a focus on actively used polymer adhesives and the recently implemented prosthesis-supporting osseointegrated implants, with an emphasis on their creation from 3D-printed polymers. The successful prosthetics is discussed in terms of the specificity of polymer materials at the restoration site. The approaches and technological prospects are also explored through the examples of the nasal, auricle and ocular prostheses, ranging from prototypes to end-use products.

Cloner 3D photogrammetric facial scanner: Assessment of accuracy in a controlled clinical study

OBJECTIVE

To evaluate the accuracy of facial measurements on three-dimensional images obtained using a new photogrammetric scanner.

MATERIAL AND METHODS

A total of 11 participants were included in the study. Nine customized adhesive labels were used to identify the facial landmarks: Trichion (Tri), Glabella (G), Right (Exr) and Left (Exl), Pronasal (Pn), Subnasal (Sn), Chelion right (Chr) and left (Chl) and Mentonian (Me). Two trained and calibrated examiners were responsible for performing seven linear measurements for each participant (Tri-G, Sn-Me, Exr-Exl, Chr-Chl, Exr-Chr, Exl-Chl, Pn-Sn) first with a digital caliper and later with a three-dimensional model obtained after digitalization with photogrammetric technology. The intraclass correlation coefficient (ICC), mean difference, SD, and Bland-Altman correlation were used to compare the measurements performed.

RESULTS

Intra and inter-examiner reliability were excellent (ICC >0.9). In general, the measurements presented a variation of a minor 2.0 mm. However, only three measures (Sn-Me, Exr-Exl, and Exr-Chr) were outside the clinical acceptability range.

CONCLUSIONS

The 3D Cloner scanner showed clinically acceptable accuracy comparable to the digital caliper with a variation of -0.8 ± 1.2 mm. Inter- and intra-examiner agreement on digital measurements was also observed.

CLINICAL SIGNIFICANCE

Scanners with accurate 3D model reproductions associated with reliable digital measurements provide a more precise diagnosis and better planning in orofacial treatment.

Accuracy and reliability of 2-dimensional photography versus 3-dimensional soft tissue imaging

Purpose

This study was conducted to objectively and subjectively compare the accuracy and reliability of 2-dimensional (2D) photography and 3-dimensional (3D) soft tissue imaging.

Materials and Methods

Facial images of 50 volunteers (25 males, 25 females) were captured with a Nikon D800 2D camera (Nikon Corporation, Tokyo, Japan), 3D stereophotogrammetry (SPG), and laser scanning (LS). All subjects were imaged in a relaxed, closed-mouth position with a normal smile. The 2D images were then exported to Mirror® Software (Canfield Scientific, Inc, NJ, USA) and the 3D images into Proplan CMF® software (version 2.1, Materialise HQ, Leuven, Belgium) for further evaluation. For an objective evaluation, 2 observers identified soft tissue landmarks and performed linear measurements on subjects' faces (direct measurements) and both linear and angular measurements on all images (indirect measurements). For a qualitative analysis, 10 dental observers and an expert in facial imaging (subjective gold standard) completed a questionnaire regarding facial characteristics. The reliability of the quantitative data was evaluated using intraclass correlation coefficients, whereas the Fleiss kappa was calculated for qualitative data.

Results

Linear and angular measurements carried out on 2D and 3D images showed excellent inter-observer and intra-observer reliability. The 2D photographs displayed the highest combined total error for linear measurements. SPG performed better than LS, with borderline significance (P=0.052). The qualitative assessment showed no significant differences among the 2D and 3D imaging modalities.

Conclusion

SPG was found to a reliable and accurate tool for the morphological evaluation of soft tissue in comparison to 2D imaging and laser scanning.

Measuring progressive soft tissue change with nasoalveolar molding using a three-dimensional system

BACKGROUND

For craniofacial orthodontics and surgery to progress, accurate temporal evaluation of soft tissue and skeletal change with treatment is necessary. Evolution in three-dimensional imaging eliminates certain inherent challenges in making such measurements in infants with facial clefts.

OBJECTIVE

The aim of this pilot study was to measure progressive three-dimensional changes in nasal form in a series of infants with facial clefts during the course of presurgical nasoalveolar molding.

MATERIALS AND METHODS

In 5 infants with unrepaired cleft lip and palate, three-dimensional photographs were obtained using the 3dMD system (3dMD, Inc, Atlanta, GA) at 2-week intervals during nasoalveolar molding treatment. Using the 3dMD Vultus software, temporal soft tissue changes were evaluated quantitatively based on three-dimensional linear measurements of 3 landmarks in the nasal area and qualitative changes in the surface shell.

RESULTS

Increase in columellar length on the cleft side and decrease of the nostril floor on the noncleft side were observed in all subjects. Progressive changes were observed most significantly in week 4 (T3) into treatment.

CONCLUSIONS

This pilot study describes an approach using the 3dMD photo system with Vultus software for measuring the progressive change in the nasal soft tissues. The 3dMD system was believed to be valuable for facial analysis in this setting.

Comparison of facial soft tissue measurements on three-dimensional images and models obtained with different methods

AIM

The aim of this study was to compare the clinical facial soft tissue measurements with the measurements of facial plaster cast, three-dimensional scanned facial plaster cast, 3-dimensional digital photogrammetrical images, and three-dimensional laser scanner images.

MATERIALS AND METHODS

Three-dimensional facial images of 15 adults were obtained with stereophotogrammetry and a three-dimensional laser scanner. Facial models of subjects were obtained using silicone impression and were scanned. Landmarks were marked on the subjects and plaster casts, digitized on three-dimensional models, and measured in Mimics 12.0 software (Materialise's Interactive Medical Image Control System, Leuven, Belgium).

RESULTS

No statistically significant differences were found between all three-dimensional measurement methods in mouth width, philtrum median height, and nasal width. Comparison of clinical measurements with facial plaster cast measurements revealed that philtral width, nasal tip protrusion, and right lip and nostril heights were wider and longer in clinical measurements than in facial plaster cast measurements. Comparison of clinical measurements to the laser scanned and stereophotogrammetric model measurements revealed that philtrum lateral and lip heights and philtral width were significantly different between methods. When laser scanned and stereophotogrammetric measurements were compared, significant differences were observed in lip and nostril heights.

CONCLUSIONS

Facial impression may be problematic owing to the depression caused by the impression material especially on the tip of the nose. Laser scanning is not sensitive enough to visualize the deeper indentations such as nostrils. Stereophotogrammetry is promising for three-dimensional facial measurements and even will be better when color identification between mucocutaneous junctions of the lip region is achieved.

3D digital stereophotogrammetry: a practical guide to facial image acquisition

The use of 3D surface imaging technology is becoming increasingly common in craniofacial clinics and research centers. Due to fast capture speeds and ease of use, 3D digital stereophotogrammetry is quickly becoming the preferred facial surface imaging modality. These systems can serve as an unparalleled tool for craniofacial surgeons, proving an objective digital archive of the patient's face without exposure to radiation. Acquiring consistent high-quality 3D facial captures requires planning and knowledge of the limitations of these devices. Currently, there are few resources available to help new users of this technology with the challenges they will inevitably confront. To address this deficit, this report will highlight a number of common issues that can interfere with the 3D capture process and offer practical solutions to optimize image quality.