Comparative Analysis of Additive Manufacturing Methods to fabricate Auricular Prostheses

In the current literature to the topic only little was published on the geometrical accuracy and resemblance of AM-produced prostheses replicas. Therefore the main objective of the present study was to identify the superior AM method from FDM, SLS and SL in terms of dimensional accuracy, skin details reproduction and efficiency to produce APRs using thereby the rapid prototyping approach. Twenty three subjects underwent a clinical study procedure encompassing ear anthropometry, followed by structured light scanning of patients’ left auricles. The auricular area including the pinna was scanned with a portable surface scanner (Artec 3D Spider, Artec Group, Luxembourg, Luxembourg), utilizing the structured light scanning method. The distances of the anthropometrical landmarks were measured within the Software (ARTEC Studio, version 9), three times blinded with the “digital lineal”. After the gathered data was post-processed and converted into OBJ format, it has been transferred to AM machines to produce 57 APRs by means of FDM (n=23), SLS (n=23) and SL (n=11) methods. The manufactured APRs were measured blinded three times each distance between the landmarks with the digital calipers. Measurements gathered from APRs have been compared to the In-vivo and CAD data groups. Results have been statistically evaluated. Additionally, the surface analysis of APRs utilizing stereomicroscopy and profilometry was conducted to ascertain what level of skin details reproduction is achievable. Production costs and time were calculated. The analysis of dimensional accuracy revealed difference up to 0.56 mm. This was found clinically acceptable, as not exceeding the threshold of 2 mm (see on page 20), which was set as a threshold ( However, the comparison of relative mean differences disclosed the bias of up to 1.85 % between the in vivo data group and AM-produced APRs, which was higher than 1.5 %, as assumed in the present study. The comparison of relative mean differences between CAD data group and APRs did not reveal any discrepancies that may be clinically recognizable. As far as pure accuracy of AM methods is concerned, the FDM showed the best result. The reproduction of skin surface structure was only feasible where the skin details exceed 192 µm of depth. The reference wrinkles “Lobula basis” and “Lobula corpus” were visible on each APR. However, the wrinkle “Helix” was not reproducible by any of the employed AM methods. The FDM showed the most detailed reproduction of the tissue portion captured by means of structured light scanning. The staircase effect remains the main limiting factor of this AM method. The disclosed differences were found to be clinically acceptable, although in 5 of 42 comparisons the mean relative differences between in vivo and APRs exceeded slightly the threshold of clinical relevance set in the present study. The step of digital data acquisition was obviously more responsible for the revealed dimensional errors than the AM methods themselves. The method of FDM showed the best trade-off between dimensional accuracy, level of texture details and pricing. Thus FDM can be recommended for rapid and efficient manufacturing of prostheses replicas

High-level laser therapy versus scalpel surgery in the treatment of oral lichen planus: a randomized control trial

Objective: To compare the clinical effectiveness of various types of high-level laser therapy (HLLT) toward scalpel excision for the surgical treatment of erosive oral lichen planus (OLP). Materials and methods: The total number of 128 individuals were enrolled in the study. The 35 did not meet the inclusion criteria due to malignancy signs and presence of diabetes mellitus. In total, 8 were lost to follow-up, and 10 were excluded from the analysis, due to analgesics intake. This way 75 patients with the erosive form of OLP were analyzed in three intervention groups (Er:YAG, n = 19; Nd:YAG, n = 15; Er:YAG + Nd:YAG combination, n = 20) and one control group with scalpel excision (n = 21). The therapy effectiveness has been assessed based on the comparison of salivary interleukin (IL)-1 beta, IL-6 and interferon (IFN)-gamma preoperative levels to 14, 30 days, and 2 years postoperation, as well as pain level and time of epithelization. Results: All HLLT groups demonstrated a significantly (p > 0.05) higher IL-1 beta, IL-6, IFN gamma and pain level reduction and quicker epithelization toward the control group on the 30th day, except Nd:YAG in case of IFN gamma level. The highest IL-1 beta, IFN gamma and pain level reduction and quicker epithelization on the 30th day was observed in Er:YAG group, followed by Er:YAG + Nd:YAG combination, Nd:YAG respectively. However no significant difference was observed between the HLLT groups with regard to IL-6 level reduction. After a 2-year follow-up, no significant difference was observed between all study groups with regard to all variables. Conclusion: HLLT yields a superior clinical outcome compared to the scalpel excision for the surgical treatment of oral lichen planus, whereby the Er:YAG has been proposed as the most effective laser type at the end of the first postoperative month. Clinical relevance: For the surgical treatment of erosive OLP the Er:YAG laser may be a preferable treatment option compared to Nd:YAG and scalpel surgery. Trial registration: The present trial was registered retrospectively in the German Clinical Trials Register, as a member of WHO international clinical trials registry platform, on the 18.03.2020 with the following number: DRKS00020986

Stereolithography vs. Direct Light Processing for Rapid Manufacturing of Complete Denture Bases: An In Vitro Accuracy Analysis

The topical literature lacks any comparison between stereolithography (SLA) and direct light processing (DLP) printing methods with regard to the accuracy of complete denture base fabrication, thereby utilizing materials certified for this purpose. In order to investigate this aspect, 15 denture bases were printed with SLA and DLP methods using three build angles: 0°, 45° and 90°. The dentures were digitalized using a laboratory scanner (D2000, 3Shape) and analyzed in analyzing software (Geomagic Control X, 3D systems). Differences between 3D datasets were measured using the root mean square (RMS) value for trueness and precision and mean and maximum deviations were obtained for each denture base. The data were statistically analyzed using two-way ANOVA and Tukey's multiple comparison test. A heat map was generated to display the locations of the deviations within the intaglio surface. The overall tendency indicated that SLA denture bases had significantly higher trueness for most build angles compared to DLP (p < 0.001). The 90° build angle may provide the best trueness for both SLA and DLP. With regard to precision, statistically significant differences were found in the build angles only. Higher precision was revealed in the DLP angle of 0° in comparison to the 45° and 90° angles

Longitudinal Three-Dimensional Stereophotogrammetric Growth Analysis in Infants with Unilateral Cleft Lip and Palate from 3 to 12 Months of Age.

This longitudinal study aimed to evaluate facial growth and soft tissue changes in infants with complete unilateral cleft lip, alveolus, and palate (CUCLAP) at ages 3, 9, and 12 months. Using 3D images of 22 CUCLAP infants, average faces and distance maps for the entire face and specific regions were created. Color-coded maps highlighted more significant soft tissue changes from 3 to 9 months than from 9 to 12 months. The first interval showed substantial growth in the entire face, particularly in the forehead, eyes, lower lip, chin, and cheeks (p < 0.001), while the second interval exhibited no significant growth. This study provides insights into facial soft tissue growth in CUCLAP infants during critical developmental stages, emphasizing substantial improvements between 3 and 9 months, mainly in the chin, lower lip, and forehead. However, uneven growth occurred in the upper lip, philtrum, and nostrils throughout both intervals, with an overall decline in growth from 9 to 12 months. These findings underscore the dynamic nature of soft tissue growth in CUCLAP patients, highlighting the need to consider these patterns in treatment planning. Future research should explore the underlying factors and develop customized treatment interventions for enhanced facial aesthetics and function in this population

Digitaler Workflow in der Gesichtsprothetik

The current thesis touches upon the digital workflow and implementation of CAD/CAM for manufacturing of facial prostheses. It investigates the three inherent steps of a digital workflow: digitization, prothesis design and prothesis materialization. For a successful DW, an extraoral structured light scanner remains the state-of-the-art digitizer, as it allows for the most universal data capture, including morphology of the defect, contralateral side and the whole face. Currently, the DW in maxillofacial prosthetics lacks a plug-and-play solution, calling for special software development with a more extensive database of facial parts, retention elements and skin details. The evolution of prosthesis delivery in digital workflow seems to follow two parallel avenues: indirect mold making approach and rapid manufacturing. Both technical options are viable, however they stil show a need for improvements. Indirect mold making calls for a new wax printing method with skin-like wax and decreased costs. Rapid manufacturing calls for a new silicone multimaterial and multi-color printing hardware at an affordable price

Multi-Material 3D Printing of a Customized Sports Mouth Guard: Proof-of-Concept Clinical Case

A multilayer mouth guard is known to have the best protective performance. However, its manufacturing in a digital workflow may be challenging with regards to virtual design and materialization. The present case demonstrates a pathway to fabricate a multilayer individualized mouth guard in a fully digital workflow, which starts with intraoral scanning. A free-form CAD software was used for the virtual design. Two various CAM techniques were used, including Polyjet 3D printing of rubber-like soft material and silicone printing using Drop-on-Demand technique. For both methods the outer layer was manufactured from more rigid materials to facilitate its protective function; the inner layer was printed from a softer material to aid a better adaptation to mucosa and teeth. Both 3D printed multilayer mouth guards showed a clinically acceptable fit and were met with patient appraisal. Their protective capacities must be evaluated in further clinical studies