This study investigates the impact of printing layer orientation on the mechanical properties of 3D-printed temporary prosthetic materials. Traditionally, temporary prostheses are fabricated using acrylic resin (polymethyl methacrylate), but advancements have introduced bis-acrylic resins, CAD/CAM-based acrylic resin (milled), and 3D printing technologies. In 3D printing, material is manufactured in overlapping layers, which can be oriented in different directions, directly affecting the material’s resistance. Specimens were designed as bars (2 mm × 2 mm × 25 mm) and grouped according to their printing orientation: BP0 (0 degrees), BP45 (45 degrees), and BP90 (90 degrees). The models were created using Fusion 360 software (version 2.0.12600) and printed on a 3D DLP printer with DLP Slicer software (Chitu DLP Slicer, CBD Tech, version v1.9.0). The bars were then subjected to 3-point bending tests using an Instron Universal Testing Machine to measure Flexural Strength (FS) and Flexural Modulus (FM). Results demonstrated that the BP90 group exhibited the highest Flexural Strength (114.71 ± 7.61 MPa), followed by BP45 (90.10 ± 8.45 MPa) and BP0 (80.90 ± 4.01 MPa). Flexural Modulus was also highest in the BP90 group (3.74 ± 3.64 GPa), followed by BP45 (2.85 ± 2.70 GPa) and BP0 (2.52 ± 2.44 GPa). Significant statistical differences (p < 0.05) were observed, indicating changes in the mechanical properties of the 3D-printed material. The study concludes that printing orientation significantly influences the mechanical properties of temporary prosthetic materials, making the selection of an optimal orientation essential to enhance material performance for its intended application.

Background: Marginal adaptation is one of biggest challenges in restorative dentistry, mainly in restoration of composite resin. Even with development of lower shrinkage materials, like those which use the polymer silorane, it is necessary a faithful clinical protocol in order to obtain better results and more clinical durability of restorative procedure. The purpose of this study was investigated if different polymers can influence on marginal adaptation of different composite resin restorations. Material and methods: Twenty class V cavities were confectioned in twenty human molars in a standardized way. Ten dentists received one tooth each and a questionnaire to describe their own clinical protocol. The other 10 teeth were restored by one researcher as control group. The cavities received the adhesive system than increments of composite resin, and so the restorations were finished with finishing bur (KG Sorensen, São Paulo, SP, Brazil) to remove the excess, followed by sof-lex discs (3M ESPE). After this stage, all of specimens were embedded in 1% Methylene blue (Prolabo, Paris, France) during 48 h. The evaluation of pigment penetration into the interfaces was performed after specimens were washed in distilled water and longitudinally sectioned with steel Diamond disc in low velocity. Results: There was significant statistical difference between the different techniques using compose resin. Conclusions: it was possible conclude that the clinical protocol to perform dental restoration interfere dramatically in the final results of restorative procedure.

O crescente uso de implantes dentários tem impulsionado a demanda por soluções protéticas inovadoras. Essas novas formas e abordagens visam aprimorar tanto o manuseio clínico quanto a qualidade do tratamento, oferecendo melhores resultados e maior eficiência no atendimento ao paciente. Entre os desenvolvimentos recentes, a conexão Morse grande se tornou popular, mas não há estudos científicos que tenham comparado seu desempenho mecânico com o dos implantes de hexágono externo ou cone Morse. O objetivo deste estudo foi avaliar comparativamente as características mecânicas de dois tipos de conexões protéticas (hexágono externo e grand Morse) na reabilitação da maxila posterior, empregando o método de elementos finitos: hexágono externo e Morse grande (4,0 mm x 8,0 mm - Hélix Neodent), ambos com coroas retidas por parafuso. Modelos virtuais foram gerados com o software CAD Rhinoceros 7® com base na forma óssea de um segmento da maxila posterior do protocolo BioCAD. Uma malha tetraédrica 3D de ordem primária foi criada para a análise, simulando cargas de 100N a um ângulo de 30º em relação ao eixo do implante. Os resultados mostraram um deslocamento maior no modelo de hexágono externo (0,1399 mm) em comparação ao modelo Morse grande (0,0208 mm). A análise de estresse revelou padrões semelhantes próximos à plataforma do implante, mas o modelo de hexágono externo exibiu maior estresse von Mises (148,4 MPa) em comparação ao modelo Morse grande (99,03 MPa), que apresentou uma melhor dispersão de estresse. O Estresse Principal Máximo foi mais elevado no modelo Morse grande. Assim, o design da conexão da plataforma do implante afeta a distribuição e a intensidade do estresse.

Objective The aim of this article was to evaluate the influence of mesial root canal preparation of mandibular molars with the reciprocal systems (RCP) and self-adjusting file (SAF) in the incidence of voids spaces in endodontic obturation performed by modified continuous wave compaction (MCWC) technique, through images obtained in micro-computed tomography (micro-CT). Materials and Methods Mesial roots of 15 mandibular molars, with two independent root canals, were divided into three groups (n = 5/roots), according to the endodontic instrumentation strategy (RCP, SAF, and twisted file [TWF]). After the root canals (n = 10, for each instrumentation system) were filled with MCWC, images of each specimen were obtained by micro-CT followed by three-dimensional reconstruction. The percentage of voids was obtained (in mm³) in relation of the total volume, cervical–middle, and apical thirds. Statistical Analysis The data obtained were submitted to statistical analysis by Kruskal–Wallis and Dunn tests (p < 0.05). Results With respect to the total volume of root canal, TWF demonstrated a lower percentage in comparison to SAF (p < 0.05). No significant difference was obtained between TWF and RCP or RCP and SAF (p > 0.05). In the apical third, RCP showed a smaller percentage of voids when compared with SAF (p < 0.05); however, TWF demonstrated similarity with RCP and SAF (p > 0.05). The middle–cervical third exhibited no statistically difference between TWF and RCP or RCP and SAF (p > 0.05), whereas TWF was lower than SAF (p < 0.05). Conclusion Root canal preparation of mesial root of mandibular molars with TWF provides a lower incidence of voids in the endodontic filling performed by MCWC. Article published online: 30 January 2024 © 2024. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/) Thieme Medical and Scientific Publishers Pvt. Ltd. A-12, 2nd Floor, Sector 2, Noida-201301 UP, India

The aim of this study was to evaluate the effects of mechanized final irrigation protocols (XPE, XP-Endo Finisher; XPC, XP-Clean; and ECL, Easy Clean) compared to PUI (passive ultrasonic irrigation) on the debris incidence and open dentinal tubules, and their effects on the adhesion interface after 48 h and 6 months. One hundred twenty maxillary central incisors were submitted to chemical–mechanical preparation using a rotary instrument and 2.5% sodium hypochlorite. Specimens were distributed in 4 groups (n = 30) in accordance with the mechanized final irrigation protocol: XPE, XPC, ECL, or PUI. Forty specimens (n = 10/group) were submitted to SEM analysis to evaluate the residue incidence and dentin open tubules. The other specimens were obturated using Bio-C Sealer and submitted to push-out bond strength and adhesive failure mode evaluations in the cervical, middle, and apical thirds after 48 h or 6 months (n = 10/group). Only in the apical third, ECL presented the highest residue incidence and fewer open dentinal tubules when compared to the XPE, XPC, and PUI groups (p < 0.05). In the cervical and middle root thirds, no significant differences were observed regardless of the group evaluated (p > 0.05). After 48 h, ECL resulted in the lowest bond strength only in the apical third (p < 0.05), while the XPE, XPC, and PUI groups remained similar in the cervical and middle thirds (p > 0.05). At 6 months, all groups showed lower bond strength values regardless of the root third evaluated, but ECL showed the lowest bond strength in the apical and middle root thirds when compared to the other groups (p < 0.05). The ECL protocol did not provide adequate residue removal on the apical radicular third and negatively affected the longevity of endodontic obturation using a calcium silicate-based sealer.