Search Results (138)

Primary teeth play a crucial role in a child’s development, particularly in maintaining space for permanent teeth. The premature loss of a primary tooth can lead to orthodontic issues, making the use of space maintainers essential to ensure proper growth and development of permanent teeth. To preserve space, the fabrication of a space maintainer is necessary. Since conventional space maintainers do not restore masticatory function, this study presents an innovative solution for space preservation following the extraction of the first primary molar through the design of the functional space maintainer KOS&MET (Key Orthodontic System and Materials Enhanced Therapy). The space maintainer was designed using the 3Shape Dental Designer 2023 version software tool and manufactured via additive 3D printing, utilizing a metal alloy with high resistance to masticatory forces. The crown is supported by the primary canine, while an intraoral window is created to monitor the eruption of the successor tooth. This design does not interfere with occlusion and enables bilateral chewing. Masticatory performance was assessed using two-color chewing gum, and the results showed improvement after cementing the space maintainer. This innovative approach not only preserves space for permanent teeth but also enhances masticatory function, contributing to the proper growth and development of the jaws and teeth. Full article

Background: Prosthetic cementation using the biologically oriented preparation technique (BOPT) presents challenges in removing excess cement from the gingival sulcus, due to the absence of a finishing line and the impossibility of using absolute isolation with a rubber dam. This study aimed to evaluate the effectiveness of relative isolation using polytetrafluoroethylene (PTFE) tape in reducing cement retention during BOPT cementation. Methods: Fifteen 3D-printed resin models were created from an intraoral scan of a patient restored with BOPT in both upper central incisors. Each model included removable gingiva. Splinted polymethylmethacrylate (PMMA) provisional crowns were fabricated and cemented with temporary cement. One central incisor was isolated with PTFE (0.1 mm or 0.2 mm), while the contralateral tooth was left unisolated as a control. After debonding, digital scanning and volumetric analysis using root mean square (RMS) deviation were performed to quantify retained cement. Paired t-tests were applied to compare groups. Results: The mean RMS for the PTFE group was 0.1248 ± 0.0519 mm, compared to 0.1973 ± 0.0361 mm in the non-isolated group (p < 0.001). No significant difference was found between PTFE thicknesses of 0.1 mm and 0.2 mm (p = 0.388). Conclusions: PTFE tape is effective for relative isolation when rubber dam placement is not feasible in BOPT restorations. Further clinical studies are recommended to confirm these findings in vivo. Full article

Objective: This article presents a step-by-step digital technique for fabricating a 3D-printed surgical guide to assist in alveoloplasty for immediate denture placement. Methods: The workflow integrates intraoral scanning, virtual tooth extraction, digital soft tissue modeling, and additive manufacturing to produce a customized guide with an occlusal window and buccal slot, along with a verification stent. Results: This method ensures precise ridge recontouring and verification, enhancing surgical predictability and prosthetic fit. Conclusions: Unlike traditional surgical guides based on conventional casts or manual fabrication, this fully digital approach offers a practical and replicable protocol that bridges digital planning and clinical execution. By improving surgical precision, reducing operative time, and ensuring optimal denture fit, this technique represents a significant advancement in guided pre-prosthetic surgery. Full article

This study presents a methodology for developing and validating digital models of tooth-inlay systems, aiming to trace the complete workflow from clinical procedures to simulation by involving dental professionals—dentists for manual cavity preparation and dental technicians for restoration modelling—while integrating micro-computed tomography (micro-CT) imaging with finite element analysis (FEA). The proposed workflow includes (1) the acquisition of high-resolution 3D micro-CT scans of a non-restored tooth, (2) image segmentation and reconstruction to create anatomically accurate digital twins and mesh generation, (3) the selection of proper resin and the 3D printing of four typodonts, (4) the manual preparation of cavities on the typodonts, (5) the acquisition of high-resolution 3D micro-CT scans of the typodonts, (6) mesh generation, digital inlay and onlay modelling and material property assignment, and (7) nonlinear FEA simulations under representative masticatory loading. The approach enables the visualisation of stress and deformation patterns, with preliminary results indicating stress concentrations at the tooth-restoration interface integrating different cavity alternatives and restorations on the same tooth. Quantitative outputs include von Mises stress, strain energy density, and displacement distribution. This study demonstrates the feasibility of using image-based, tooth-specific digital twins for biomechanical modelling in dentistry. The developed framework lays the groundwork for future investigations into the optimisation of restoration design and material selection in clinical applications. Full article

Introduction: Successful root canal therapy relies on thorough cleaning and disinfection to eliminate microorganisms and residual pulp tissue. Advanced irrigation activation techniques, including Sonic, Ultrasonic, and Diode Laser activation, have improved cleaning efficacy, bacterial reduction, smear layer removal, and irrigant hydrodynamics. On the other hand, these irrigation activation techniques may lead to a temperature rise that may risk the surrounding periodontal tissue. Thus, this study aimed to investigate the temperature rise during different irrigation activation techniques at various time intervals and evaluate the efficacy of these techniques in removing biofilm-mimicking hydrogel BMH of a simulated root canal system in 3D-printed tooth models. Methods: Ten extracted human mandibular premolars, prepared to size 40/0.04 taper, and a hundred 3D-printed resin premolars with simulated main (0.25 mm) and lateral canals (0.15 mm at 3, 7, 11 mm from apex) were used; 50 of them were filled with biofilm-mimicking hydrogel (BMH). Five irrigation activation techniques were evaluated: Diode Laser, Ultrasonic, Sonic, XP-Finisher, and Control (n = 10). Temperature rises were measured on the extracted premolars after 30 and 60 s of activation using a thermographic camera in a controlled environment (23 ± 2 °C). Irrigant penetration, with and without BMH, was assessed in 3D-printed premolars using a 2.5% sodium hypochlorite-contrast medium mixture, visualized with a CMOS radiographic sensor. Penetration was scored (main canal: 3 points; lateral canals: 0–2 points) and analyzed with non-parametric tests. Results: Diode Laser activation technique resulted in the highest temperature rise on the external root surface, followed by the Ultrasonic, with no statistically significant difference observed among the remaining groups. In terms of efficacy, Ultrasonic and Sonic activation achieved significantly greater irrigant penetration in samples without BMH, and greater BMH removal in samples with BMH, compared to Diode Laser, XP-Finisher, and Control groups. Conclusions: In this in vitro study, Diode Laser caused the highest temperature rise, followed by Ultrasonic, with significant increases from 30 to 60 s. Temperature rise did not significantly affect penetration or BMH removal. Ultrasonic and Sonic irrigation techniques achieved the highest depth of penetration (without BMH) and biofilm-mimicking Hydrogel removal (with BMH) compared to Diode Laser, XP-Finisher, and Control. Full article

This in vitro study aims to investigate the fracture properties of 3D-printed resin provisional material designed with different connector dimensions for two-unit fixed dental prostheses (FDPs). The master model was digitally designed following Shillingburg’s all-ceramic restoration tooth preparation guidelines and milled from aluminum. Four two-unit FDPs with different connector dimensions were designed: 2 × 3 mm, 3 × 3 mm, 3 × 4 mm, and 4 × 4 mm (width × length) (Groups A, B, C, and D, respectively; n = 10 for each group). These specimens were printed using 3D-printed resin material (Detax FREEPRINT^® temp). Forty specimens were subjected to a three-point test using a universal testing machine until fracture. The failure mode was examined under a stereomicroscope. The Kruskal–Wallis test at α = 0.05 revealed non-significant differences in fracture resistance load but significantly different elastic modulus, yield strength, and compressive strength (p = 0.061, p < 0.001, p < 0.001, and p < 0.001, respectively) among the different groups. The 2 × 3 mm connectors had higher means of modulus, yield strength, and compressive strength compared to the other groups. The study found that the maximum load causing fractures in 3D-printed provisional material connectors was consistent, regardless of connector cross-section variations. The 2 × 3 mm group performed best, while the 4 × 4 mm group performed worst. Full article

Background: Autogenous tooth transplantation is a valuable option for dental rehabilitation, particularly in young patients. Template-guided approaches, using 3D-printed replicas of donor teeth, have recently emerged as a method to increase precision and reduce extraoral time—two critical factors in maintaining periodontal ligament (PDL) vitality, which is essential to improve long-term outcomes. Methods: This report presents the case of a 12-year-old patient who underwent autotransplantation of tooth 18 to the site of tooth 75, which exhibited ankylosis. Patients exhibiting unfavorable root anatomy and morphology, systemic conditions, or completed root development were not considered for this technique. A patient-specific donor tooth replica was digitally designed and 3D-printed via CAD/CAM manufacturing to preoperatively shape the recipient site. The transplanted tooth 18 was then inserted with an extraoral time of less than one minute and subsequently stabilized using a flexible titanium trauma splint (TTS). Results: Longitudinal clinical and radiographic follow-up over 12 months confirmed favorable healing without signs of complications. Conclusions: This case illustrates the practical advantages of a fully digital, template-guided workflow in managing anatomically complex cases. Full article

Objectives: To introduce a novel method for apical lesion sampling using a protected paper point device and to evaluate its effectiveness and robustness during the sampling process in vitro. Methods: A prototype for apical sample collection was developed as an adaptation of the Micro-Apical Placement System—the device features a highly tapered screw head with a thin, hollow, stainless-steel tube and an internal wire piston. Standardized 5 mm paper points (ISO 10; PD Dental, Switzerland) served as carrier material. The prototype was tested using 30 × 3D-printed, single-rooted tooth models inoculated using two bacterial strains (Staphylococcus epidermidis and Escherichia coli) to simulate apical and intraradicular bacterial infections, respectively. The sampling process involved collecting and analyzing samples at specific timepoints, focusing on the presence or absence of E. coli contamination. Following sample collection, cultural detection of bacterial presence was performed by incubating the samples on agar plates to confirm the presence of E. coli. Samples were collected as follows: S0 (sterility control of the prototype), P0 (sterility control of the tooth model), P1 (apical sample collected with the CAPS (controlled apical sampling) device, and P2 (contamination control sample to check for the presence of E. coli inside the root canal). Results: Handling of the CAPS prototype was straightforward and reproducible. No loss of paper points or complications were observed during sample collection. All sterility samples (P0, S0) were negative for tested microorganisms, confirming the sterility of the setup. P2 samples confirmed the presence of E. coli in the root canal in all trials. The P1 samples were free from contamination in 86.67% of trials. Conclusions: The CAPS method for apical sampling demonstrated advances in the successful and precise sample collection of apically located S. epidermidis and will be a useful tool for endodontic microbiological analysis. Its user-friendly design and consistent performance highlight its potential for clinical application, contributing to more accurate microbial diagnostics and later patient-specific therapeutic approaches in endodontic treatments. Full article

Background: A 19-year-old female patient reported to the Department of Conservative Dentistry, Medical University of Gdańsk, with pain in the left lateral incisor. During the attempt to perform root canal treatment on tooth 22, we encountered difficulties in locating the canal opening, which resulted in treatment failure. Radiographic examinations revealed Pulp Canal Obliteration and a root fracture with a double fracture line, resulting in two root fragments. The prognosis for this tooth was poor, with extraction being the most likely outcome. Methods: To provide effective therapy, a 3D-printed endodontic guide was utilized, allowing for more precise localization of the canal in a tooth with a calcified root canal and complex fracture morphology. An intraoral scan and cone-beam computed tomography (CBCT) were performed, followed by the design of the guide. This facilitated accurate planning of the entry path for endodontic instruments, promoting minimally invasive treatment and reducing the loss of tooth structure. Results: Through navigated endodontics, the treatment became more predictable, and the risk of iatrogenic complications was minimized, significantly improving the prognosis of the therapy. Clinical and radiological examinations conducted after 12 months demonstrated successful treatment and preservation of the tooth in the oral cavity. Conclusions: The obtained results suggest that the use of guided endodontics can improve outcomes in cases with pulp canal obliteration and complex fractures, offering a minimally invasive and predictable approach. Full article

Objectives: To examine the effects of surface treatments on the color stability, surface roughness, surface gloss, and wettability of monolithic polychromatic material jetting (MJT) 3D-printed denture material. Material and Methods: Twenty-one color variants of the same denture material (TrueDent; Stratasys, Eden, MN, USA) underwent two surface treatments (polishing only or polishing and glazing), creating 42 study groups with a total of 420 samples (n = 10 per group). The samples were manufactured using a PolyJet 3D printer (J5 DentaJet; Stratasys, Eden, MN, USA), a type of MJT 3D printer. Color measurements were taken with a digital spectrophotometer before and after the surface treatments, and quantitative color differences (ΔE₀₀ and ΔC*) were calculated using the CIE2000 system. Comparisons of ΔE₀₀ were made against the 50%:50% acceptability threshold (AT) of 1.8 and the 50%:50% perceptibility threshold (PT) of 0.8 for tooth shade, as well as the 50%:50% PT of 1.72 and the 50%:50% AT of 4.08 for gingival (pink) shade. After surface treatment, the gloss was measured using a glossmeter, surface roughness was measured with optical profilometry, and wettability was measured by contact angle measurements using an optical tensiometer. The significance of surface treatment on color changes for each color variant was evaluated using one-sided, one-sample t-tests against the AT and PT. The effects of surface treatment on surface gloss, surface roughness, contact angle, and ΔC* were analyzed using t-tests for each color variant. Pairwise comparisons between groups were made using Fisher’s Protected Least Significant Differences (α = 0.05). Results: In most cases, glazing caused the color change (ΔE₀₀) to exceed the AT and PT, with a few exceptions. Most materials exhibited a more vibrant (more saturated) appearance and statistically higher chroma, with glazed surface treatments compared to polished ones, though there were some exceptions. For all materials, the glazed samples had significantly higher gloss units than the polished ones (p < 0.0001). Additionally, all materials showed significantly higher surface roughness in glazed samples compared to polished ones (p < 0.0001 for most). The polished samples had significantly higher contact angles (p < 0.0001 for most). Conclusions: Surface treatments significantly influenced the color, surface gloss, surface roughness, and wettability of MJT 3D-printed denture materials. Glazing led to increased chroma and gloss and produced more hydrophilic surfaces, although it also increased surface roughness. These results highlight the importance of surface treatment selection in optimizing the clinical performance of MJT-fabricated dentures. Full article

This study evaluates the optical properties and mechanical durability of adhesive restorations fabricated using different techniques for the treatment of single-tooth loss in the posterior region after an aging process. Sixty extracted human teeth (thirty molars and thirty premolars) were restored using three different fabrication methods: 3D-printed resin restorations, fiber mesh-reinforced direct composite restorations, and indirect composite restorations. Color stability was assessed using a spectrophotometer, and fracture resistance was measured using a universal testing machine. Finite element stress analysis (FEA) was conducted to validate mechanical test results under simulated intraoral conditions. The fiber-reinforced composite group exhibited the highest fracture resistance (1057.91 MPa), while 3D-printed restorations showed the lowest (p < 0.05). Regarding color stability, the fiber-reinforced group demonstrated the highest ΔE⁰⁰ values (ΔE⁰⁰ = 1.71), differing significantly from the other groups, while the 3D-printed and indirect composite restorations showed no significant difference. Mechanical test results were consistent with FEA findings. These results indicate that fiber reinforcement enhances mechanical durability in high-load-bearing areas, while 3D-printed restorations may not yet be suitable for posterior regions. However, their potential use in anterior restorations, where occlusal forces are lower, warrants further investigation to improve material properties. Full article

Recently, with policies aimed at strengthening domestic manufacturing and technological innovation, the robotics industry has been growing rapidly, and its applications are expanding across various industrial fields. Accordingly, the importance of high-performance speed reducers with flexibility and precision is gradually increasing. The tooth profiles used in conventional harmonic reducers have structural limitations, such as meshing discontinuity, restrictions on the radius of curvature of the tooth base, and distortion of the contact trajectory, especially when the number of teeth is small. These problems limit the design freedom of the reducer and make it difficult to secure contact stability and durability under precision driving conditions. To solve these problems, this paper proposes a new tooth profile design equation, the IH (Involute Harmonic) tooth profiles and the HTPs (Hybrid Tooth Profiles), using the cycloid curve to overcome the structural limitations of the conventional harmonic tooth profile, which is difficult to design under small-tooth-number conditions, and to enable tooth design without restrictions on the number of teeth. HTP tooth profile is a new gear tooth profile design method that utilizes IH tooth profile and cycloid curve to optimize the meshing characteristics of gears. A tooth profile design tool based on the HTP equation was developed using Python 3.13.3. The tool’s effectiveness was validated through simulations assessing tooth meshing and interference. Using the tool, an R21_z3 reducer with a single-stage high reduction ratio was designed to evaluate practical applicability. A prototype was fabricated using 3D printing with PLA material, and experimental testing confirmed the absence of meshing or interference issues, consistent with simulation results. Through this study, we verified the usefulness of the HTP tooth profile design formula and design tool using the IH tooth profile and cycloid curve, and it is expected that the proposed HTP tooth profile can be utilized as a tooth profile applicable to various reducer designs. Full article

Artificial Intelligence (AI) is rapidly transforming orthodontic care by providing personalized treatment plans that enhance precision and efficiency. This narrative review explores the current applications of AI in orthodontics, particularly its role in predicting tooth movement, fabricating custom aligners, optimizing treatment times, and offering real-time patient monitoring. AI’s ability to analyze large datasets of dental records, X-rays, and 3D scans allows for highly individualized treatment plans, improving both clinical outcomes and patient satisfaction. AI-driven aligners and braces are designed to apply optimal forces to teeth, reducing treatment time and discomfort. Additionally, AI-powered remote monitoring tools enable patients to check their progress from home, decreasing the need for in-person visits and making orthodontic care more accessible. The review also highlights future prospects, such as the integration of AI with robotics for performing orthodontic procedures, predictive orthodontics for early intervention, and the use of 3D printing technologies to fabricate orthodontic devices in real-time. While AI offers tremendous potential, challenges remain in areas such as data privacy, algorithmic bias, and the cost of adopting AI technologies. However, as AI continues to evolve, its capacity to revolutionize orthodontic care will likely lead to more streamlined, patient-centered, and effective treatments. This review underscores the transformative role of AI in modern orthodontics and its promising future in advancing dental care. Full article

Background: Mucostatic impressions have been always indicated in thin, sharp, or flabby ridges, and have been addressed for their beneficial effect on long-term residual ridge stability. Nonetheless, a purely mucostatic impression was not possible until intraoral scans became available. This provides an option for digital removable denture which is biologically sensible but might reduce retention in comparison with a mucocompressive impression with border molding. On the other hand, pressure applied to the mucosa may have harmful effects on the long-term residual ridge stability, causing higher resorption and ultimately reduced denture retention. Hence, the possibility to merge mucostatics and mucocompressive philosophies would be a clinically and biologically sensible option for oral rehabilitation in aging populations where patients will potentially wear dentures for longer periods. This possibility is demonstrated in this technical report with a cast-free digital workflow. Technique: Baseplates for occlusion rims, closely adapted to the mucosa, were designed on intraoral scans of edentulous arches and, once 3D-printed, used to register maxillomandibular relations and information for tooth arrangement, as well as to perform border molding. Occlusion rims were then scanned and, within the 3Shape Dental System 2024 software program, the intaglio surfaces of their baseplates were segmented and inverted to obtain the digital master casts which incorporated the precise reproduction of the molded borders. Then, denture design was performed and manufactured; no limitations regarding manufacturing options are applicable to the presented technique. Conclusions: The potential benefits (i.e., improved retention in the initial period after denture delivery and the preservation of tissues) of the presented digital cast-free workflow, based on merging mucostatic and mucocompressive philosophies to obtain dentures with a mucostatic intaglio surface and functional borders, are sensible clinical outcomes which recommend the clinical application of the technique, although further validation, especially in the long term, is required. Full article

This study evaluates the biomechanical efficacy of clear aligners in closing anterior maxillary diastemas using enhanced force systems. While clear aligners offer esthetic and functional benefits, their predictability in controlling bodily movement and torque remains limited. This research investigates the effects of structural modifications, such as the addition of flowable resin to interdental embrasures and intrusive force application, on the force and moment characteristics during mesial bodily movement of maxillary central incisors. Experiments were conducted using 3D-printed maxillary models with a 6-axis force/torque sensor under controlled conditions. Four experimental groups were tested: Group 1 (0.3 mm mesial bodily shift), Group 2 (0.3 mm mesial shift + 0.1 mm intrusion), Group 3 (0.3 mm mesial shift with resin reinforcement), and Group 4 (0.3 mm mesial shift + 0.1 mm intrusion with resin reinforcement). The results showed that Groups 1 and 3 exhibited extrusive forces, while Groups 2 and 4 exhibited intrusive movement with minimized extrusion. Resin reinforcement significantly increased mesiodistal force application and reduced unwanted tipping and rotational moments, improving bodily movement efficiency. The addition of intrusive movement minimized extrusive forces but introduced a minor lingual inclination. The combination of both modifications provided the most controlled and efficient tooth movement. These results suggest that modifying clear aligners with localized structural enhancements can improve treatment predictability and efficiency. Clinically, the application of flowable resin enhancements offers a simple and effective approach to optimizing clear aligner therapy. Full article