Search Results (211)

Objective: To evaluate the concordance of automated 3D superimposition methods applied to digital models, with a focus on methods that consider stable palatal regions as geometric reference landmarks versus those that do not. Design and setting: This was a prospective, cross-sectional study using digital model files of patients undergoing orthodontic treatment in a university clinical setting. Participants: Sixty-one patients were prospectively enrolled and divided into three groups based on the type of orthodontic treatment they received: (20) non-extractive orthodontic treatment without intermaxillary elastics, (21) intermaxillary elastics, and (20) control subjects with no orthodontic movement. The inclusion criteria included the availability of complete pre- and post-treatment digital casts and the absence of significant craniofacial anomalies. Methods: Three superimposition methods were tested: (1) superimposition according to palate and palatal ridges, (2) best-fit superimposition of arches in occlusion, and (3) best-fit superimposition of individual arches. Discrepancies were identified by comparing the spatial positions derived from each method. Within three spatial axes, deviations of ±0.5 mm and ±1.15° were not considered significant. Bland–Altman plots were used to quantify palatal rugae based and non-based spatial differences between methods. Differences in the superimposition results between the three patient groups were evaluated using ANOVA tests. Results: Differences in spatial position between the superimposition methods often exceeded the acceptable range. The results were compared between the three patient groups with a statistical significance of α = 0.05. In the present study, the high reliability of the superimposition method based on the palate and palatal ridges was observed. Conclusion: Superimposition methods based on the palate and palatal rugae provide superior accuracy in determining treatment-related changes in upper arch digital models. These findings illustrate the need for appropriate selection of superimposition techniques based on the study objective of using clinically relevant techniques. Full article

Laser powder bed fusion (LPBF) is an advanced additive manufacturing technology that is gaining increasing interest for biomedical implants because it can produce dense, patient-specific metallic components with controlled microstructures. This study investigated the LPBF fabrication of 316L stainless steel, which is widely used in orthopedic and dental implants, and examined the effects of laser power and scanning speed on the microstructure and mechanical properties relevant to biomedical applications. The study achieved 99.97% density and refined columnar and cellular austenitic grains, with optimized molten pool morphology. The optimal LPBF parameters, 190 W laser power and 700 mm/s, produced a tensile strength of 762.83 MPa and hardness of 253.07 HV_0.2, which exceeded the values of conventional cast 316L stainless steel. These results demonstrated the potential of optimized LPBF 316L stainless steel for functional biomedical applications that require high mechanical integrity and biocompatibility. Full article

Achieving accurate fit in implant-supported prostheses is critical for avoiding mechanical complications; however, the influence of digital manufacturing techniques and abutment designs on misfit and preload remains unclear. This study evaluated the impact of different manufacturing techniques (CAD-cast and 3D printing) and abutment connection types (engaging [E], non-engaging [NE]) on the misfit and preload of implant-supported cantilevered fixed dental prostheses (ICFDPs). Misfit was measured at six points using scanning electron microscopy, and preload was assessed via eight strain gauges placed buccally and lingually on four implants. Frameworks were torqued to 35 Ncm, retorqued after 10 min, and subjected to 200,000 cycles of loading. Mean preload values ranged from 173.4 ± 79.5 Ncm (PF) to 330 ± 253.2 Ncm (3DP). Preload trends varied depending on the abutment type and manufacturing technique, with the 3DP group showing higher preload in engaging (E) abutments, whereas the CAD-cast group showed the opposite pattern. Although preload values varied numerically, these differences were not statistically significant (p = 0.5). In terms of misfit, significant differences were observed between groups (p < 0.05), except between CAD-cast E (86.4 ± 17.8 μm) and 3DP E (84.1 ± 19.2 μm). Additionally, E and NE abutments showed significant differences in misfit within both CAD-cast and 3DP groups. Overall, 3DP frameworks showed superior fit over CAD-cast. These findings suggest that 3DP may offer improved clinical outcomes in terms of implant–abutment fit. Full article

Background: Inadequate presurgical planning is a key contributor to suboptimal outcomes in orthognathic surgery. This study aims to assess the accuracy of a digital surgical planning workflow conducted prior to any orthodontic intervention. Methods: Digital planning was performed for 26 patients before orthodontic treatment (T0) and compared to the actual preoperative planning (T1). Digitized plaster casts were merged with CBCT data and converted to orthodontic setups to create a 3D virtual head model. After voxel-based registration of T0 and T1, dental arches were virtually osteotomized and repositioned according to planned outcomes. These T0 segments were then aligned with T1 planning using bony landmarks of the maxilla. Anatomical landmarks were used to construct virtual triangles on maxillary and mandibular segments, enabling assessment of positional and orientational differences. Transformations between T0 and T1 were translated into clinically meaningful metrics. Results: Significant differences were found between T0 and T1 at the dental level. T1 exhibited a greater clockwise rotation of the dental maxilla (mean: 2.85°) and a leftward translation of the mandibular dental arch (mean: 1.19 mm). In SARME cases, the bony mandible showed larger anti-clockwise roll differences. Pitch variations were also more pronounced in maxillary extraction cases, with both the dental maxilla and bony mandible demonstrating increased clockwise rotations. Conclusions: The proposed orthognathic surgical planning workflow shows potential for simulating mandibular outcomes but lacks dental-level accuracy, especially in maxillary anterior torque. While mandibular bony outcome predictions align reasonably with pretreatment planning, notable discrepancies exceed clinically acceptable thresholds. Current accuracy limits routine use; further refinement and validation in larger, homogeneous patient groups are needed to enhance clinical reliability and applicability. Full article

This in vitro study aims to compare the trueness of digital impressions obtained using two intraoral scanners (IOS) and one photogrammetry device for full-arch implant-supported rehabilitations. According to the Caramês Classification I, three models were produced with Straumann implants arranged in different spatial distributions: Option A with six implants and Options B and C with four implants each. The three models were scanned using a 12-megapixel scanner to create digital master casts. For each reference model, 30 digital impressions were acquired: 10 with the 3Shape Trios 3 intraoral scanner, 10 with the Medit i500 intraoral scanner, and 10 with the PIC Dental photogrammetry device. Trueness was assessed through best-fit superimpositions between the digital master casts and the corresponding virtual models. The Shapiro–Wilk test was applied to assess the normality of the data distribution, and Levene’s test was used to evaluate the homogeneity of variances. The non-parametric Kruskal–Wallis test was employed to compare group differences, with post hoc adjustments made using the Bonferroni correction. A significance threshold of p = 0.05 was adopted for all statistical tests. Statistically significant differences were observed in the root mean square values among the three devices. The Medit i500 demonstrated the highest trueness, with a median (interquartile range) deviation of 24.45 (18.18) µm, whereas the PIC Dental exhibited the lowest trueness, with a median deviation of 49.45 (9.17) µm. Among the implant distribution, the Option C showed the best trueness, with a median deviation of 19.00 (27.83). Considering the results of this in vitro study, intraoral scanners demonstrated comparable trueness, whereas the photogrammetry-based system exhibited lower trueness values. Additionally, a smaller number of implants and reduced inter-implant distances were associated with improved trueness in digital impressions for full-arch implant rehabilitation. Full article

Background: Digital dental photography is increasingly essential for documentation and smile design. This study aimed to compare the linear measurement accuracy of various smartphones and a Digital Single-Lens Reflex (DSLR) camera against digital models obtained by intraoral and desktop scanners. Methods: Tooth height and width from six different casts were measured and compared using images acquired with a Canon EOS 250D DSLR, six smartphone models (iPhone 13, iPhone 15, Samsung Galaxy S22 Ultra, Samsung Galaxy S23 Ultra, Samsung Galaxy S24, and Vivo T2), and digital scans obtained from the Helios 500 intraoral scanner and the Ceramill Map 600 desktop scanner. All image measurements were performed using ImageJ software (National Institutes of Health, Bethesda, MD, USA), and statistical analysis was conducted using one-way analysis of variance (ANOVA) with Tukey’s post hoc test (α = 0.05). Results: The results showed no significant differences in measurements across most imaging methods (p > 0.05), except for the Vivo T2, which showed a significant deviation (p < 0.05). The other smartphones produced measurements comparable to those of the DSLR, even at distances as close as 16 cm. Conclusions: These findings preliminary support the clinical use of smartphones for accurate dental documentation and two-dimensional smile design, including the posterior areas, and challenge the previously recommended 24 cm minimum distance for mobile dental photography (MDP). This provides clinicians with a simplified and accessible alternative for high-accuracy dental imaging, advancing the everyday use of MDP in clinical practice. Full article

Printed cast models are becoming increasingly important in prosthodontics. The aim of this in vitro study was to evaluate the influence of print orientation and external shell thickness on the accuracy of stereolithography (SLA) master casts for fixed dental prostheses. Seventy-two maxillary hollow master casts were fabricated from a standard tessellation language (STL 0) reference file containing dental preparations. The casts were divided into six groups (n = 12 per group) according to internal shell thickness (2 mm and 4 mm) and print orientation (0°, 10°, and 20°). Discrepancies between STL 0 and the STL files of the printed casts were measured using the root mean square (RMS) error. Data were statistically analyzed using a one-way Kruskal–Wallis test to assess trueness, and precision was evaluated with the Levene test (α = 0.05). No statistically significant differences were found in any of the tested conditions. Print orientation and cast thickness did not influence the overall accuracy of SLA master casts for fixed dental prostheses. Full article

Objective: To evaluate mandibular kinematics in an orthodontic population using the Modjaw^® optical jaw tracking system. Materials and methods: A total of 154 orthodontic patients underwent mandibular kinematic analysis using the Modjaw^® system. ANB values determined skeletal classification, while dental classification was assessed on digital casts. The Modjaw^® records were taken as instructed by the manufacturer, and data collected from the readings included the discrepancy between centric occlusion and maximum intercuspation, maximum opening, Bennett angles, and sagittal condylar guidance. The presence or absence of temporomandibular disorders was determined by the DC-TMD questionnaires. Non-parametric tests and Spearman correlations were applied for the statistical analysis. Results: Significant differences in mandibular kinematics were observed between skeletal classes, particularly in CO-MI discrepancies, Bennett angles, and maximum opening (p < 0.05). TMD symptoms were associated with higher absolute CO-MI discrepancies but did not significantly alter other kinematic parameters. Weak correlations were found between sagittal condylar guidance and anterior guidance variables. Conclusions: Mandibular kinematics differ by skeletal classification, with Class III patients demonstrating distinct patterns. While TMD symptoms impact CO-MI discrepancies, overall mandibular dynamics remain consistent. Full article

Background/Objectives: Among the complications of endodontic treatment, root fractures are the most severe and may require tooth extraction. The objective of this study was to develop virtual models of mandibular molars with different endodontic restorations to assess the stress distribution in tooth structures based on the type of corono-radicular restoration, compared with the model of an intact molar. Methods: Four virtual models of a mandibular molar were created: (1) an intact molar with preserved enamel, dentin, dental pulp and cementum; (2) an endodontically treated molar restored with a composite filling; (3) a molar restored with a fiberglass post and monolithic zirconia crown; (4) a molar restored with a metal cast post and monolithic zirconia crown. External force loads from 0 to 800 N were simulated using Finite Element Method (FEM). Results: The highest displacement, strain and stress values were observed in the molar restored with a composite filling, whereas the lowest values were recorded in the molar restored with a fiberglass post and zirconia crown. Critical stresses were primarily concentrated on the pulp chamber floor. Conclusions: The pulp chamber floor was identified as the most vulnerable area for fracture. This underscores the importance of preserving tooth structure to enhance the strength and durability of molars throughout and beyond endodontic treatment. 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

The objective of this study was to measure and compare the mechanical properties of conventional and three additively manufactured soft tissue silicone materials, while evaluating the precision of additively manufactured (AMed) materials through different printing angles. Three additively manufactured soft tissue silicone materials were used, in addition to one conventional self-curing injectable silicone material as a control. AMed materials were divided into three groups with three build angles. Mechanical testing was conducted for tensile and compressive strength by a universal testing machine and Shore A hardness by a durometer. Accuracy analysis of additively manufactured materials (n = 20/group) was performed following superimposition and root mean square (RMS) calculation. Statistical differences between the groups were assessed with a one-way analysis of variance (ANOVA) and Tukey’s post hoc test at a significance level of p < 0.05. Scanning Electron Microscopy (SEM) analysis was performed for fracture surface analyses. The tensile strength of all additively manufactured silicone soft tissue materials was significantly lower (p < 0.0001) than that of the control material. All additively manufactured soft tissue material groups had significantly higher compressive strengths (p < 0.0001) and Shore A hardness values. Accuracy analysis showed no significant difference between the groups when compared at the same printing angle (0°, 45°, and 90°); however, within each material group, printing at 45° had higher RMS values than specimens printed at an angle of 0° and 90°. The conventional soft tissue material (control) had a significantly higher tensile strength than all the AMed soft tissue materials, whereas the opposite trend was found for flexural strength and shore hardness. When selecting an AMed material for soft tissue casts used during implant restoration fabrication, it is recommended to print the soft tissues at either 0° or 90°. Full article

Precision in diagnosis is essential for achieving optimal outcomes in prosthodontics, orthodontics, and orthognathic treatments. Virtual articulators provide a sophisticated digital alternative to conventional methods, integrating intraoral scans, facial scans, and cone beam computed tomography (CBCT) to enhance treatment predictability. This review examines advancements in virtual articulator technology, including digital workflows, virtual facebow transfer, and occlusal analysis, with a focus on Artificial Intelligence (AI)-driven methodologies such as machine learning and artificial neural networks. The clinical implications, particularly in condylar guidance and sagittal condylar inclination, are investigated. By streamlining the acquisition and articulation of digital dental models, virtual articulators minimize material handling errors and optimize workflow efficiency. Advanced imaging techniques enable precise alignment of digital maxillary models within computer-aided design and computer-aided manufacturing systems (CAD/CAM), facilitating accurate occlusal simulations. However, challenges include potential distortions during digital file integration and the necessity for robust algorithms to enhance data superimposition accuracy. The adoption of virtual articulators represents a transformative advancement in digital dentistry, with promising implications for diagnostic precision and treatment outcomes. Nevertheless, further clinical validation is essential to ensure the reliable transfer of maxillary casts and refine digital algorithms. Future developments should prioritize the integration of AI to enhance predictive modeling, positioning virtual articulators as a standard tool in routine dental practice, thereby revolutionizing treatment planning and interdisciplinary collaboration. This review explores advancements in virtual articulators, focusing on their role in enhancing diagnostic precision, occlusal analysis, and treatment predictability. It examines digital workflows, AI-driven methodologies, and clinical applications while addressing challenges in data integration and algorithm optimization. Full article

Background/Objectives: The development of dental arches is a complex adaptive system with interactions between genetic and environmental factors. At different developmental stages, the relative contribution of these factors varies. The aims of this project were to identify the longitudinal changes of dental arches in the primary, mixed and permanent dentition stages, using curve fitting methods on serial dental casts, and to investigate the contribution of the genotype to dental arch development. Methods: Longitudinal dental records from 125 monozygotic same-sex twin pairs, 89 dizygotic same-sex twin pairs, and 49 opposite-sex dizygotic twin pairs were used. Standardized model photographs were collected, and key landmarks were digitized. Fourth-order orthogonal polynomials were applied to the Cartesian data. Descriptive statistics were calculated, and structural equation models were developed to analyze the individual polynomial coefficients. The final models employed a genetic simplex framework, enabling the evaluation of how genetic and environmental influences changed over time. These changes were examined both quantitatively (e.g., variations in heritability) and qualitatively (e.g., the influence of different genes at various stages). Results: In the primary dentition, arches were typically parabolic, while in the permanent dentition, they tended to be more square-shaped. Asymmetry made a minor contribution to variation across all stages of development. Genetic analysis revealed that a core group of genes influenced arch shape over time, though their impact varied. Additionally, some genes were specific to certain developmental stages, with their relative contributions differing significantly. Notably, there was evidence of sexual heterogeneity in arch shape, particularly in the permanent dentition. Heritability was consistently high, both at individual developmental stages and throughout the overall developmental process. Conclusions: The degree of genetic influence at each developmental stage was substantial but it fluctuated between the primary, mixed, and permanent dentition stages. Full article

This study aimed to investigate the release of metallic ions from cobalt–chromium (Co-Cr) alloys fabricated by additive manufacturing (AM) for comparison with dental casting. Co-Cr alloys were fabricated via AM using selective laser melting (SLM) and electron beam melting (EBM) in powder-bed fusion. Polished and mechanically ground specimens were prepared. Each specimen was analyzed using an electron probe microanalyzer (EPMA). Each specimen was immersed in an acidic saline solution for 7 days in accordance with ISO 10271: 2020. The EPMA indicated the segregation of some elements in the as-prepared SLM and EBM specimens, whereas the polished and ground specimens exhibited a homogenous elemental distribution. The total amount of ion release from the SLM and EBM specimens was confirmed to be less than 7 μg/cm², which was less than 42 μg/cm² for the cast specimen. The polished and ground specimens exhibited an even lower ion release than the as-prepared specimens. The amount of ions released from the Co-Cr alloy was less than the 200 μg/cm² requirement of ISO 22674: 2022. Co-Cr alloys fabricated by SLM and EBM could provide superior corrosion resistance to cast specimens. AM could be a valuable method for fabricating appliances and denture frameworks in dentistry. Full article

Background/objectives: This retrospective longitudinal outcome study comparing orthodontic extraction modalities, including extraction of maxillary first or second molars, aimed to compare the three-dimensional tooth movement of maxillary canines (C), premolars (P1, P2), and molars (M1, M2) in Class II division 1 malocclusion treatment with fixed appliances. Methods: A sample of 98 patients (mean age 13.20 ± 1.46 years) was selected for the M1 group, and 64 patients (mean age 13.20 ± 1.36 years) were chosen for the M2 group. Tooth movement was analyzed three-dimensionally on pre-treatment (T0) and post-treatment (T1) digital dental casts. Regression analyses compared the tooth movements (in mm) between the M1 and M2 groups. Results: The mean treatment duration for the M1 group was 2.51 ± 0.55 year, while, for the M2 group, it was 1.53 ± 0.37 year. The data showed limited distal movements of the C, P1, and P2 of approximately 2 mm in the M1 group and 1 mm in the M2 group during orthodontic treatment, but the M1 group exhibited significantly more distal movements than the M2 group (mean difference 1.11 to 1.24 mm). Vertical movements of the C, P1, and P2 in both groups were also minor (0.16 to 1.26 mm). The differences between groups did not exceed 0.2 mm and were not significant. Both treatment modalities resulted in a significant degree of anchorage loss with a distinct mesialization (8.40 ± 1.66 mm) of M2 in the M1 group and limited distalization (0.83 ± 0.98 mm) of M1 in the M2 group. Conclusions: The findings highlight the importance of thorough case evaluation when choosing between extraction modalities in Class II treatment. If a large distal movement of canines and premolars is required, additional anchorage mechanics should be considered. Full article