Cellularised Biomaterials Used as Gingival Connective Tissue Substitutes In Vivo: Systematic Review.

Developing an in vitro model of gingival connective tissue, mimicking the original structure and composition of gingiva for clinical grafting is relevant for personalised treatment of missing gingiva. Using tissue engineering techniques allows to bypass limitations encountered with existing solutions to increase oral soft tissue volume. This review aims to systematically analyse the different currently existing cellularised materials and technologies used to engineer gingival substitutes for in vivo applications. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. An electronic search on PubMed, Scopus, Web of Science and Cochrane Library databases was conducted to identify suitable studies. In vivo studies about gingival substitute and graft containing oral cells compared with a control to investigate the graft remodelling were included. Risk of bias in the included studies was assessed using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) 10-item checklist. Out of 631 screened studies, 19 were included. Animal models were mostly rodents, and the most used implantation was subcutaneous. According to the SYRCLE tool, low-to-unclear risk of bias were prevalent. Studies checked vascularisation and extracellular remodelling up to 60 days after implantation of the cellularized biomaterial. Cells used were mostly fibroblasts and stem cells from oral origin. Grafts presenting vascularisation potential after implantation were produced by tissue engineering technologies including cell seeding or embedding for 14, cell sheets for 2, microsphere for 1 and extrusion 3D bioprinting for 2. Components used to build the scaffold containing the cells are all naturally derived and are mainly fibrin, gelatine, collagen, agarose, alginate, fibroin, guar gum, hyaluronic acid, and decellularised extracellular matrix. The most recurring crosslinking method was using chemicals. All studies except 1 reported vascularisation of the graft after implantation and some detailed extracellular matrix remodelling. Current solutions are not efficient enough. By assessing the relevant studies on the subject, this systematic review showed that a diversity of cellularised biomaterials substituting gingival connective tissue enable vascularisation and extracellular remodelling. Taking results of this review in count could help improving current bio-inks used in 3D bioprinting for in vivo applications compensating for gingival loss.

Concordance of judgement: A tool to foster the development of professionalism in dentistry.

INTRODUCTION: Developing professionalism notably involves learning how to make professional judgements in ambiguous situations. The Concordance of Judgement Test (CJT) is a learning tool that was proposed to develop professionalism competencies, but it was never performed in dentistry or used with a synchronous methodology. The present study evaluated the feasibility of the use of CJT in the context of dental education, to foster professionalism and stimulate reflexivity and discussion. MATERIALS AND METHODS: After different steps of optimization, a questionnaire presenting 12 vignettes was submitted to 33 Canadian students. Second, after an additional optimization, a questionnaire of 7 vignettes was submitted to 87 French students. An immediate educational feedback was proposed after each vignette to promote reflexivity and discussions during the experience. RESULTS: The overall experience of the students was reported as good, thanks to the feedback of real-life situations. This promoted reflexivity and stimulated discussion between students and educators regarding professionalism issues. The students considered CJT as a relevant and well-adapted tool, and reported positive feelings regarding the inter-university aspect of the activity. The mean score of the panel members was close to 80/100 and the mean score of the students was 5 to 10 points lower, which is in agreement with docimological performance. CONCLUSION: The results suggested that the use of CJT in a synchronous way was a feasible and relevant tool to motivate the students to improve their professionalism, and to stimulate their reflexivity and discussion. The students reported positive experience with CJT, and we believe that this tool can be integrated in the dental curriculum.

Implant Survival Rate in Mandible Reconstructed with Free Fibula Flaps After Oral Tumors: A Systematic Review and Meta-Analysis.

PURPOSE: To assess the implant survival rate in mandibles reconstructed with free fibula flap after oral tumor resection after 1 year of prosthetic loading. A secondary objective was to compare immediate or delayed implant placement protocols in this population. MATERIALS AND METHODS: Electronic and manual searches were performed on different databases for controlled and prospective trials that indicated implant survival rate. This systematic review followed PRISMA guidelines. Risk of bias was evaluated using Cochrane Collaboration tools. Meta-analyses heterogeneity source assessment and GRADE evaluation were performed among studies with identical follow-ups. RESULTS: Among 305 primarily selected articles, 109 were eligible after reading the title and abstract, and 8 were included after full-text reading: 2 randomized controlled trials and 6 prospective studies comprising 140 patients and 507 implants. Meta-analyses estimated an overall survival rate of 97% (95% CI: 94% to 99%) after 1 year of prosthetic loading. The survival rate was 98% (95% CI: 94% to 100%) with immediate implantation and 97% (95% CI: 90% to 99%) with delayed implantation. Only 3 studies reported radiotherapy treatment, with no real impact on implant survival rate. Overall, 69% of tumors were benign. CONCLUSIONS: Implant placement in vascularized fibula flaps in the mandible is recommended for patients undergoing segmental mandibular reconstruction after tumor resection. Within the limitations of this study, no significant difference in survival rates was found between immediate and delayed implant placement.

Development of craniometry-based predictive model to determine occlusal vertical dimension by using the eye-ear distance in a French population.

STATEMENT OF PROBLEM: Techniques for determining occlusal vertical dimension (OVD) have limitations, including the lack of reproducibility or invasiveness. Recently, a craniometry-based predictive model comparing OVD with eye-ear distance (EED) was developed in Chile. However, this study included a specific population and excluded patients with a history of orthodontics. For verification, studies on other populations are required. PURPOSE: The purpose of this clinical study was to follow the previously described protocol to obtain an equation for determining OVD in a French cohort (mostly White with an orthodontic history). MATERIAL AND METHODS: Dentate adults with a stable occlusion and no known maxillofacial, otolaryngeal, or temporomandibular problems were included in this study. Demographic information, including participant age, sex, and history of orthodontic treatment, was collected. Facial height and width were measured with digital calipers, and the left EED and OVD were recorded with a craniometer. The facial index was calculated to classify participants into euryprosopic, mesoprosopic, or leptoprosopic types. RESULTS: Of the 300 included participants (28 ±11 years), 60% were women, and 67% reported a history of orthodontic treatment. Euryprosopic represented 17% of participants, mesoprosopic 48%, and leptoposopic 35%. A positive correlation was found between the left EED and OVD in all facial types, but it was more important in women. The following equation was obtained: OVD=44.58+(0.45×left EED)+sex (women=-4.57; men=0)+facial type (leptoprosopic=0; mesoprosopic=-3.35; euryprosopic=-7.27). CONCLUSIONS: The occlusal vertical dimension is correlated with sex, left EED, and facial type. This straightforward method can be applied in conjunction with other techniques to determine the OVD in the French population.

Effect of triangular mesh resolution on the geometrical trueness of segmented CBCT maxillofacial data into STL format.

OBJECTIVES: To determine the optimal level of mesh reduction that would maintain acceptable levels of geometrical trueness while also minimizing the impact on other parameters such as file size and processing time. METHODS: Intraoral and extraoral maxillofacial defects were created on 8 cadaver heads and scanned by using a CBCT scanner (NewTom 3D Imaging, Verona). DICOM data were segmented to produce head (n=8) and skull models (n=8) saved as standard tessellation language (STL) files. A further processing of head models was preformed to produce face (n=8) and ear models (n=8). A mesh reduction process was performed for each STL model (reference, R0) by generating 50% (R1), 75% (R2), and 90% (R3) reductions. The 3 datasets were compared to the R0 file using 3D evaluation software (GOM Inspect) using a global best-fit algorithm, to calculate the root mean square (RMS) deviations. Statistical analyses were performed at a level of significance of α=0.05. RESULTS: There was no 3D deviation after the 50% triangular mesh reduction in the 4 datasets. Minor 3D deviations were observed after 75% reduction, in all groups. After 90% reduction, higher 3D deviations were observed, and especially in head and skull. Statistically significant increase in 3D deviations was observed with higher degrees of mesh reduction (p < 0.001). CONCLUSION: The resolution of CBCT-based maxillofacial defect models can be reduced up to 50%, with neglectable concern to inaccuracy. CLINICAL SIGNIFICANCE: Accurate maxillofacial models can be obtained from CBCT DICOM files after segmentation and export as STL files, even when the mesh resolution is reduced up to 50%. This information can be valuable for practitioners and researchers working with 3D models of maxillofacial defects.

Preliminary impression for maxillary defect: A two-step technique.

Preliminary impressions must record the periphery and height of maxillary defects to allow for an eventual extension of the master impression tray. These impressions are usually made with irreversible hydrocolloid. Carrying the impression material into the defect can be complex, especially in the case of a limited oral opening. Moreover, the patient can be harmed during the removal procedure, and material may be stuck in anatomical structures. The technique presented in this article avoids these issues in any maxillary defect with a two-step preliminary impression. An elastomeric material ball is first placed in the defect until full setting. Then, this "obturator bulb" is removed and eventually relined until it is retentive. Retentions are designed on the oral side of the bulb and the bulb is placed back into the defect. Finally, an alginate over-impression of the maxillary is made. The alginate is removed after full setting, and the obturator can be reassembled on the maxillary impression to provide a full recording of the maxillary. This protocol can safely be used for defects of any size, despite eventual limitations in oral opening.

Digital optimization of teeth setup in an edentulous patient with partial glossectomy: A case report.

The purpose of this clinical report was to describe the use of a piezographic impression associated with computer-aided design and computer-aided manufacturing (CAD-CAM) for teeth setup and of digital tools for neuro-musculo-kinetic analyses. An edentulous patient with hemiglossectomy and heavily resorbed mandible consulted for complete denture rehabilitation to improve their masticatory function and speech. Master casts, wax rims, and piezographic impression were scanned for digital prosthetic work. Two digital try-ins were performed to respect the neutral zone: try-in 1 with posterior crossbite and try-in 2 without crossbite. Muscle activity and mandibular kinetics were performed for each try-in following the MAC2 protocol (six criteria): muscular tone, contraction synchrony, contraction efficiency, interocclusal rest distance, amplitude of mandibular movement, and velocity. Try-in 2 showed better data than try-in 1 in all criteria: muscle tone (respectively 71% vs. 59%), contraction synchrony (79% vs. 75%), contraction efficiency (85% vs. 77%), an increase in range of motion of 3.3 mm, and a better velocity (0.35 ± 0.12 s vs. 0.57 ± 0.14 s, p = 0.008). The piezographic impression, in combination with CAD-CAM, allowed the comparison of two prosthetic designs and the selection of the try-in with the best neuro-musculo-kinetic results.

In Vivo Application of Silica-Derived Inks for Bone Tissue Engineering: A 10-Year Systematic Review.

As the need for efficient, sustainable, customizable, handy and affordable substitute materials for bone repair is critical, this systematic review aimed to assess the use and outcomes of silica-derived inks to promote in vivo bone regeneration. An algorithmic selection of articles was performed following the PRISMA guidelines and PICO method. After the initial selection, 51 articles were included. Silicon in ink formulations was mostly found to be in either the native material, but associated with a secondary role, or to be a crucial additive element used to dope an existing material. The inks and materials presented here were essentially extrusion-based 3D-printed (80%), and, overall, the most investigated animal model was the rabbit (65%) with a femoral defect (51%). Quality (ARRIVE 2.0) and risk of bias (SYRCLE) assessments outlined that although a large majority of ARRIVE items were "reported", most risks of bias were left "unclear" due to a lack of precise information. Almost all studies, despite a broad range of strategies and formulations, reported their silica-derived material to improve bone regeneration. The rising number of publications over the past few years highlights Si as a leverage element for bone tissue engineering to closely consider in the future.

CAD-CAM resin-ceramic material wear: A systematic review.

STATEMENT OF PROBLEM: The increasing use of computer-aided design and computer-aided manufacturing (CAD-CAM) systems has led to the development of resin-ceramic materials that meet the requirements of minimally invasive dentistry, including the resin nanoceramic (RNC) and polymer-infiltrated ceramic network (PICN). The wear characteristics of these materials are unclear. PURPOSE: The purpose of this systematic review was to compare the wear resistance of resin-ceramic materials when compared with one another or with lithium disilicate glass-ceramics. MATERIAL AND METHODS: The PubMed, Scopus, and DOSS search engines were used to identify articles published between 2013 and 2021. Two independent researchers conducted the systematic review by following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines and by following a combination of keywords. RESULTS: Of a total of 310 articles, 26 were selected, including only 1 clinical study. Among these, 15 compared resin-ceramic materials with each other, while 11 compared resin-ceramic materials with lithium disilicate ceramics. Two types of wear were used to compare the materials: attrition and abrasion. The most commonly studied materials were 2 RNCs (Lava Ultimate and Cerasmart), 1 PICN (Vita Enamic), and 1 ceramic (IPS e.max CAD). Among the resin-ceramic materials, the PICN (Vita Enamic) showed less wear than the RNCs. Of the RNCs, Cerasmart had less attrition wear and less wear of the opposing teeth. CONCLUSIONS: Lithium disilicate glass-ceramics have a higher wear resistance than resin-ceramic materials, but they cause more wear of the opposing teeth.

Efficacy of a new membrane obturator prosthesis in terms of speech, swallowing, and the quality of life of patients with acquired soft palate defects: study protocol of the VELOMEMBRANE randomized crossover trial.

BACKGROUND: Soft palate defects created during oral cancer surgery may prevent complete palatal closure and trigger palatopharyngeal insufficiency. One current treatment employs a rigid obturator prosthesis; an extension of acrylic resin at the level of the hard palate ensures surface contact with the remaining musculature. Unfortunately, airflow escape often causes hypernasality, compromises speech intelligibility, and creates swallowing problems (including leakage of food and fluid into the nasal airway). We plan to test a new removable denture featuring a thick dental dam that serves as a membrane obturator. The principal objective of the clinical trial is a comparison of speech handicap levels after 1 month in patients with acquired velar insufficiencies who wear either the new device or a conventional, rigid obturator. The secondary objectives are between-device comparisons of the swallowing handicaps and the health-related qualities of life. METHODS: The VELOMEMBRANE trial is a superiority, open-labeled, two-way, random crossover clinical trial. Adult patients exhibiting velar or palatovelar substance loss after tumor excision and who are indicated for rigid obturator-mediated prosthetic rehabilitation will be recruited in two teaching hospitals in France. Fourteen participants will be randomly allocated to wear both prostheses for 1-month periods in either order. The new membrane obturator is a removable resin prosthesis incorporating a rigid extension that holds a dental dam to restore the soft palate. The primary outcome will be the extent of phonation-related disability (the overall score on the Voice Handicap Index [VHI]). The secondary outcomes will be the Deglutition Handicap Index and health-related quality of life scores of the European Organization for Research and Treatment of Cancer (EORTC). DISCUSSION: High-quality evidence will be provided to document the utility of a new medical device that may greatly improve the management and quality of life of patients with acquired velar insufficiency. TRIAL REGISTRATION: ClinicalTrials.gov NCT04009811 . Registered on 4 July 2019.

Use of Human Gingival Fibroblasts for Pre-Vascularization Strategies in Oral Tissue Engineering.

BACKGROUND: Cocultures of human gingival fibrobasts (hGF) and endothelial cells could enhance regeneration and repair models as well as improve vascularization limitations in tissue engineering. The aim of this study was to assess if hGF could support formation of stable vessel-like networks. METHODS: Explant primary hGF were isolated from gum surgical wastes collected from healthy patients with no history of periodontitis. Human umbilical vein endothelial cells (HUVEC) were two-dimensional (2D) and three-dimensional (3D) cocultured in vitro with hGF at a cell ratio of 1:1 and medium of 1:1 of their respective media during at least 31 days. Vessel quantification of HUVEC networks was performed. In order to investigate the pericyte-like properties of hGF, the expression of perivascular markers α-SMA, NG2, CD146 and PDGFR-ß was studied using immunocytochemistry and flow cytometry on 2D cultures. RESULTS: hGF were able to support a long-lasting HUVEC network at least 31 days, even in the absence of a bioreactor with flow. As observed, HUVEC started to communicate with each other from day 7, constructing a network. Their interconnection increased significantly between day 2 and day 21 and lasted beyond the 31 days of observation. Moreover, we tried to explain the stability of the networks obtained and showed that a small population of hGF in close vicinity of HUVEC networks expressed perivascular markers. CONCLUSION: These findings highlight a new interesting property concerning hGF, accentuating their relevance in tissue engineering and periodontal regeneration. These promising results need to be confirmed using more 3D applications and in vivo testing.

Radiographic evaluation of a bone substitute material in alveolar ridge preservation for maxillary removable immediate dentures: A randomized controlled trial.

STATEMENT OF PROBLEM: Maxillary bone resorption after multiple extractions can jeopardize the success of an immediate denture, but whether bone volume preservation techniques are effective is unclear. PURPOSE: The purpose of this randomized controlled trial was to evaluate the efficacy of socket grafting with a xenogenic bone substitute in participants receiving maxillary immediate removable complete dentures in terms of bone volume preservation (height and width of the bone ridge). MATERIAL AND METHODS: The study was a single-blinded, randomized controlled clinical trial with 2 balanced parallel arms. Thirty-six participants who had Kennedy Class I edentulous posterior areas bilaterally for at least 3 months and required maxillary immediate removable complete dentures were enrolled. Duplicates of the removable complete denture were made and converted into radiographic and surgical guides. Participants allocated to the test group received deproteinized bovine bone mineral blended with 10% porcine collagen (DBBM-C) in the extraction sockets, and participants in the control group received no grafting material. With a radiographic guide in place, cone beam computed tomography scans were made 10 days after tooth extraction, when the immediate removable complete denture was delivered (D10, baseline), after 3 months (D90), and after 1 year (D365). The scans were superimposed, and measurements were made on the cross-sectional plane of each extraction site. The influence of various prognosis factors associated with bone volume preservation, including the location of tooth extraction, smoking habits, periodontal disease, and operator team, were analyzed. RESULTS: Of 36 participants, 3 were lost to follow-up. The mean ±standard deviation loss of height of the buccal crest was 1.2 ±1.8 mm in the control group and 0.3 ±1.2 mm in the test group after 3 months of healing (P<.001) and 2.1 ±2.0 mm in the control group and 0.7 ±1.4 mm in the test group after 1 year of follow-up (P<.001). Mean ±standard deviation horizontal ridge width change was 1.3 ±1.4 mm in the control group and 0.5 ±0.8 mm in the test group after 3 months (P<.001) and 2.2 ±1.4 mm in the control group and 0.9 ±1.1 mm in the test group after 1 year of follow-up (P<.001). None of the other prognostic factors had a significant effect at either time period. CONCLUSIONS: Grafting DBBM-C into the extraction socket after removing anterior teeth for immediate removable denture therapy resulted in significantly less vertical buccal crest and horizontal ridge resorption as compared with spontaneous socket healing after 1 year of follow-up. This procedure may be useful for preserving bone, especially when a fixed implant-supported prosthesis is planned.

Accuracy of commercial 3D printers for the fabrication of surgical guides in dental implantology.

OBJECTIVES: To evaluate the accuracy of two different surgical guides (small extent = single implant and large extent = full arch) fabricated by five additive manufacturing technologies (SLA=Stereolithography, DLP= Digital Light Processing, FDM=Fused Deposition Modeling, SLS=Selective Laser Sintering, Inkjet). METHODS: Overall, 72 guides (6 per type) were obtained with the different machines (SLA=Form2; DLP=Rapid Shape D40 and Cara Print 4.0; FDM=Raise 3D Pro2; SLS=Prodways P1000; Polyjet®=Stratasys J750). The guides were surface-scanned with an optical dental scanner, and the resulting files were compared with the initial design files using a surface matching software. Root Mean Square (RMS) and standard deviation were calculated, representing respectively trueness and precision. Kruskall-Wallis non-parametric test was used to compare trueness and precision between small-extent and large-extent guides and 3D printer by pairs. The threshold for significance was α=0.05, except for the comparison of printers by pairs where a Bonferroni-corrected level of 0.0033 was used. RESULTS: Significant differences were observed for trueness and precision between small-extent and large-extent guides, regardless the printer except for DLP (trueness and precision) and SLS (precision). SLA, DLP and Polyjet® technologies showed similar results in terms of trueness and precision for both small-extend and large-extend guides (P>0.05). CONCLUSIONS: The size affected the accuracy of CAD-CAM surgical guides. The different additive manufacturing technologies had a limited impact on the accuracy. CLINICAL SIGNIFICANCE: This study is of clinical interest as it shows that the 3D printing technology (SLA/DLP) has a limited impact on 3D printed surgical guides accuracy. However, the size of the guide can have a significant impact, as small-extent guides were more accurate than large-extent guides.

Immersive 3D Educational Contents: A Technical Note for Dental Educators.

Three-dimensional files featuring patients' geometry can be obtained through common tools in dental practice, such as an intraoral scanner (IOS) or Cone Beam Computed Tomography (CBCT). The use of 3D files in medical education is promoted, but only few methodologies were reported due to the lack of ease to use and accessible protocols for educators. The aim of this work was to present innovative and accessible methodologies to create 3D files in dental education. The first step requires the definition of the educational outcomes and the situations of interest. The second step relies on the use of IOS and CBCT to digitize the content. The last "post-treatment" steps involve free software for analysis of quality, re-meshing and simplifying the file in accordance with the desired educational activity. Several examples of educational activities using 3D files are illustrated in dental education and discussed. Three-dimensional files open up many accessible applications for a dental educator, but further investigations are required to develop collaborative tools and prevent educational inequalities between establishments.

Augmented Reality for Interactive Visualization of 3D Maxillofacial Prosthetic Data.

PURPOSE: To introduce an augmented reality (AR) application for students, patients, and practitioners to use to visualize a maxillectomy defect, the associated obturator prosthesis, and the eventual effects on the patient's facial appearance. MATERIALS AND METHODS: Various 3D virtual models related to maxillectomy defects and their prosthetic rehabilitations were used to illustrate the handheld AR application. The AR "scene" was created using Vuforia and Unity3D software. Within this scene, 3D virtual models were linked to the target image by detecting a symbol track marker. The final file was saved as an installable application and exported for Android smart devices. RESULTS: The target image containing the maxillectomy defect and the prosthetic rehabilitation were successfully visualized interactively in 3D mode using the handheld AR maxillofacial prosthetic application. CONCLUSION: An AR application for visualizing maxillofacial prosthetic data could interestingly be developed as a pedagogic tool to explain prosthetic treatments.

Correction to: 3D printed bone models in oral and craniomaxillofacial surgery: a systematic review.

An amendment to this paper has been published and can be accessed via the original article.

3D printed bone models in oral and cranio-maxillofacial surgery: a systematic review.

AIM: This systematic review aimed to evaluate the use of three-dimensional (3D) printed bone models for training, simulating and/or planning interventions in oral and cranio-maxillofacial surgery. MATERIALS AND METHODS: A systematic search was conducted using PubMed® and SCOPUS® databases, up to March 10, 2019, by following the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) protocol. Study selection, quality assessment (modified Critical Appraisal Skills Program tool) and data extraction were performed by two independent reviewers. All original full papers written in English/French/Italian and dealing with the fabrication of 3D printed models of head bone structures, designed from 3D radiological data were included. Multiple parameters and data were investigated, such as author's purpose, data acquisition systems, printing technologies and materials, accuracy, haptic feedback, variations in treatment time, differences in clinical outcomes, costs, production time and cost-effectiveness. RESULTS: Among the 1157 retrieved abstracts, only 69 met the inclusion criteria. 3D printed bone models were mainly used as training or simulation models for tumor removal, or bone reconstruction. Material jetting printers showed best performance but the highest cost. Stereolithographic, laser sintering and binder jetting printers allowed to create accurate models with adequate haptic feedback. The cheap fused deposition modeling printers exhibited satisfactory results for creating training models. CONCLUSION: Patient-specific 3D printed models are known to be useful surgical and educational tools. Faced with the large diversity of software, printing technologies and materials, the clinical team should invest in a 3D printer specifically adapted to the final application.

Technical Protocol for Presenting Maxillofacial Prosthetics Concepts to Dental Students using Interactive 3D Virtual Models within a Portable Document Format.

An appropriate presentation of maxillofacial defects and their prosthetic rehabilitation concepts using traditional two-dimensional educational materials is challenging for dental students and prosthodontics residents. This technique article introduces a simple approach to visualize and communicate three-dimensional (3D) virtual models embedded into a portable document format (PDF) file for presenting maxillofacial prosthetics concepts and enhancing students' spatial ability when learning maxillofacial prosthetics. MeVisLab software was used to combine various maxillofacial models and save them as a single 3D model. Adobe Acrobat Pro DC software was used to import the 3D model and create interactive visualization PDF documents. Adobe reader software was then used to visualize the content of the PDF documents. This approach allows educators to develop PDF files with multiple 3D models for teaching maxillofacial prosthetics concepts and communicate them with their students. Students can simply open the PDF file, activate the 3D mode, and interactively manipulate the 3D models to enhance their spatial ability for learning maxillofacial prosthetics.

Engineered Prevascularization for Oral Tissue Grafting: A Systematic Review.

Extensive dental and periodontal defects are frequent and with a limited regenerative potential. Tissue engineering could be a promising tool to obtain personalized oral grafts. However, current research shows a lack of in vitro engineered oral tissues. This is explained by the difficulty to engineer blood vessel systems, impairing the connection to the host tissue and the graft success. Various strategies were used to engineer vascularized tissues and reported successful results, thus needing a clear analysis of the current state of art in oral tissue engineering. This systematic review aimed at studying the critical factors and techniques used to engineer a prevascularized oral tissue graft. PubMed, Cochrane Library, and SCOPUS databases were searched over the last 5 years following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Out of 638 screened studies, 24 were included in the systematic review according to strict inclusion and exclusion criteria and focusing on higher connection to the host vasculature. Animal models were all rodents, and subcutaneous implantation was the most used intervention. Studies presented low-to-unclear risk of bias according to the Systematic Review Center for Laboratory Animal Experimentation tool. Endothelial cells were mainly human umbilical vein endothelial cells, while stromal cells were most of the time oral or mesenchymal stem cells. Coculture of both types of cells at a 1:1 ratio was the most common technique used to obtain vascular networks, and some studies precultured grafts up to 3 weeks to enable network formation before implantation. Prevascularized grafts were produced by various tissue engineering technologies, including cell seeding and/or embedding, cell sheets, and spheroids. All studies reported a statistically significant faster and higher connection to host of prevascularized constructs compared to controls. Vessel networks were indeed denser, with a higher portion of lumen containing erythrocytes and blood flow increased. By assessing the relevant studies on the subject, this systematic review showed that engineered prevascularization proved to be an interesting approach to improve graft connection to the host vasculature and respective specific cell and scaffold criteria. Further studies on enhanced scaffolds and larger animals seem necessary to confirm these promising results with more voluminous grafts and get closer to native human tissues and applications. Impact statement Autologous oral grafts display limitations in terms of revascularization and morbidity of donor sites, despite being the gold standard. This systematic review aimed at clarifying existing data regarding techniques to engineer prevascularized oral grafts. Tissue engineering techniques, using cocultures of endothelial and oral stromal cells, proved to be an efficient way to enhance and accelerate the connection of the graft to the host vasculature. Engineered prevascularization appears to be a promising way to improve the connection to the host and the vascularization of grafts, especially when voluminous. Large animal and human studies are necessary to allow clinical translation.

Nucleotide lipid-based hydrogel as a new biomaterial ink for biofabrication.

One of the greatest challenges in the field of biofabrication remains the discovery of suitable bioinks that satisfy physicochemical and biological requirements. Despite recent advances in tissue engineering and biofabrication, progress has been limited to the development of technologies using polymer-based materials. Here, we show that a nucleotide lipid-based hydrogel resulting from the self-assembly of nucleotide lipids can be used as a bioink for soft tissue reconstruction using injection or extrusion-based systems. To the best of our knowledge, the use of a low molecular weight hydrogel as an alternative to polymeric bioinks is a novel concept in biofabrication and 3D bioprinting. Rheological studies revealed that nucleotide lipid-based hydrogels exhibit suitable mechanical properties for biofabrication and 3D bioprinting, including i) fast gelation kinetics in a cell culture medium and ii) shear moduli and thixotropy compatible with extruded oral cell survival (human gingival fibroblasts and stem cells from the apical papilla). This polymer-free soft material is a promising candidate for a new bioink design.