Cast Models Research Articles

The (T) thrombosis (I) in patients with (L) lower (L) limb (I) injuries (R) requiring (I) immobilisation (TILLIRI) Study

BackgroundPatients requiring lower limb immobilisation after injury have an increased venous thromboembolism (VTE) risk. The extent of this risk in published studies varies. The TRiP(cast) model quantifies VTE risk using clinical parameters. Delineating low from high-risk patients remains challenging. AimsDetermine the 90-day incidence of symptomatic VTE following temporary lower limb immobilisation after injury in an unselected cohort. Prospectively collect data on risk factors, including those incorporated in TRiP(cast) model, to calculate TRiP(cast) scores. MethodsTILLIRI is a multi-centre, pragmatic observational cohort study including 10 sites within the Irish Network for VTE Research. Patients≥18 years with an immobilised injured lower limb were included. Twenty-one clinical variables were collected at presentation. Thromboprophylaxis was prescribed according to clinical gestalt. Patients were followed up at 90-days to determine if VTE occurred. ResultsBetween November 2018 and February 2023, 1242 patients were recruited. Follow-up was complete for 1199 patients(96.5%).43 patients(3.5%) were lost to follow-up.44(3.6%) patients and 125(10%) patients were prescribed anticoagulation and aspirin respectively. 21 patients receiving regular anticoagulation removed from final analysis. VTE incidence at 90-day follow-up was 6/1179(0.51%; CI 0.1%-0.92%). TRiP(cast) scores were calculated for 1176/1221 patients. 846 patients(71.9%) had TRiP(cast) Score< 7, received no prophylaxis and had no VTE. ConclusionTILLIRI indicates a low VTE incidence in an unselected cohort following lower limb immobilization with low rates of prophylaxis use. The proportion of patients with low TRiP(cast) scores and no symptomatic VTE suggests that thromboprophylaxis may be avoided in patients with TRiP(cast)scores< 7, with a low 90-day VTE risk.

FABRICATION OF ALL PORCELAIN CANTILEVER BRIDGE RESTORATION IN CASES OF GINGIVA RECESSION USING ZIRCONIUM DIOXIDE MATERIAL WITH ADDITIONAL RETENSION

Background: Aesthetic and functional dental restoration is a hope for people who have lost teeth, especially in the anterior region. Missing tooth 13 with more than 2 mm gingival recession can be made into a cantilever bridge restoration with the addition of porcelain gingiva. Gingival recession is when the tooth root surface is exposed due to periodontal tissue loss. Zirconia is a dental restoration material often used because of its biocompatibility, strength, and aesthetics. Purpose: To determine the procedure for making all porcelain cantilever bridge restorations in cases of gingival recession using zirconia material. Case analysis: The dental laboratory received a dental cast model of a 39-year-old female patient missing tooth 13 and had gingival recession on tooth 14 of more than 2 mm. Order in the form of restoration of all porcelain cantilever bridges from zirconia. Result: The cantilever bridge coping was made from zirconium dioxide and then layered with feldspathic porcelain to achieve optimal strength and aesthetics. A rest is made on tooth 12 to provide additional retention. Conclusion: The procedure for making all porcelain cantilever bridge restorations includes making diagnostic wax-up, scanning, coping design, milling, sintering, fitting, sandblasting, layering, anatomy, and glazing. Things that must be considered are the design, thickness of the coping, and connectors to achieve a restoration that is strong, resistant to fracture, and has good aesthetics. Porcelain gingiva was added in the cervical area of tooth 14 restorations to cover the recession

Influence of implant depth and scanning rod length on accuracy of digital impression for mandibular posterior single-tooth implant restoration

To study the influence of implant depth and scanning rod lengths on the accuracy of digital impression for single-tooth implant restoration of the mandibular posterior teeth. Five standard dental cast models with missing right mandibular first molar (46) were prepared with the subgingival implant depths of 0, 1, 3, 5 and 7 mm. ITI RC and ITI RC H11 scanning rods were connected to the replacement body and placed into the seating tract for scanning. The reference data were obtained using a 3D dental scanner, and the experimental data were obtained by 10 scans of each model using a digitized intraoral scanner. Geomagic Wrap 2021 was used to analyze the model data to test the trueness and precision of the models. The trueness did not differ significantly among the groups (P > 0.05). The implant depth of 1 mm achieved the highest impression precision (66.81±2.45 μm), and the depth of 0 mm resulted in a significantly lower precision (95.60±3.04 μm) than the depth of 1 and 3 mm. Starting from the subgingival depth of 1 mm, the precision of the scan decreased progressively with the increase of the implant depth. At the subgingival implant depth of 5 or 7 mm, the use of an extended rod significantly improved the scan precision. For single-tooth implant restoration of the mandibular posterior teeth, the implant depth can substantially affect the accuracy of digital impression, which decreases as the implant depth increases. For a deep implant, the use of a longer scanning rod can improve the scanning accuracy.

Speech Outcomes in Children with Robin Sequence Treated with a Pre-Epiglottic Baton Plate

Objective To analyze speech outcomes and cleft shape changes in children diagnosed with Robin sequence (RS) treated with a customized pre-epiglottic baton plate (PEBP). Design Single-surgeon retrospective analysis. Setting Tertiary care institution. Patients and Participants Twenty-five patients with RS who were treated with PEBP and primary cleft palate repair between 2010 and 2019. Interventions Postnatal use of a PEBP. Main Outcome Measures Speech assessment at the age of 3.5 to 4.5 years documenting hypernasality, nasal emission, nasal turbulence, voice quality, and consonant production, and analysis of digitally scanned cast models before and after the use of PEBP to quantify changes in cleft shape and width. Results The study cohort ( N = 25) consisted of 19 patients with hard and soft cleft palates and 6 patients with soft cleft palate only and postnatal use of PEBP. The mean reduction in cleft width following PEBP treatment prior to cleft palate repair in 19 infants with hard and soft cleft palates was 41.30% (standard deviation, 13.25). Speech assessments were conducted at a mean age of 48.5 months in all 25 children treated with PEBP. Most children presented with absent or mild hypernasality (96%), a rate of 8% of nasal emission and 4% of nasal turbulence was found. The most frequent findings were articulation errors in 14 children (56%), of whom 2 presented with cleft-type characteristics. Conclusions Children with RS and cleft palate treated with PEBP demonstrated a narrowing of the cleft palate prior to a timely surgical repair, and favorable speech outcomes already at a young age during childhood.

PREPARATION TECHNIQUES: FROM SINGLE BONE FRAGMENTS TO MOUNTED SKELETONS—MODELS, HYBRID EPISTEMIC OBJECTS, AND THE QUESTION OF EVIDENCE IN THE CONTEXT OF 19TH-CENTURY MOA FINDS

ABSTRACT After the first Moa bones were found in New Zealand in 1839, a Moa ‘frenzy’ unfolded in London under Richard Owen’s dominant expertise. Further finds of Moa skeletons in New Zealand gave Julius Haast, the founder of the Canterbury Museum in Christchurch, New Zealand, the opportunity to sell or exchange the bones to other museums, making him an international expert, independent from London as one of the world’s scientific centres. By 1870, the museum had seven complete mounted skeletons on display. In 1860, Vienna joined New Zealand and London in having a unique Moa skeleton find. Ferdinand Hochstetter visited New Zealand in 1858–1859 as a member of the Austrian circumnavigation expedition of the Novara and travelled across the islands as a geologist with Julius Haast. Hochstetter placed great attention on obtaining these bones, and on his return to Vienna they were prepared and articulated by Gustav Jäger. As an early Darwinian scholar in Vienna, he described the procedure of bone preparation and articulation in great detail and developed a plaster cast model made from a complete skeleton of the Palapteryx ingens Owen, of which only rudiments had been known until 1858. This paper discusses the technique of mounting skeletons, working with plaster casts and their role in the making of science. How did the mounting of skeletons guide research and how did the relationship between authenticity and evidence work? The use and meaning of 3-D constructions as opposed to images are the focus of the article. Jäger’s casts from 1863 will serve to illustrate how a producer reflected the relationship between ‘Naturwahrheit’ and preparation, between an original skeleton and a replica. What is the significance of taxidermy and artificial reconstruction, especially as it mediated between research and the public? I argue in different directions: the moa skeletons were hybrid objects that captivated scientists and the general public alike. As models, they mediated between the founders and describers of the bones, the producers of the skeletons and the public. Not only did the skeletons raise unresolved palaeontological, anatomical, taxonomical and evolutionary questions, they also fascinated because of their monumentality and uniqueness. They broadened the public’s view of the general phenomenon of extinction in the animal world, they allowed Māori legends to be incorporated as information into natural history research, and they linked human history with natural history. They were also objects that publicly promoted the importance of palaeontological collections and palaeontology as a young science.

Multiscale Analysis of Surface Topography for Engineering Applications in the Casting Industry.

This paper presents the results of studies aimed at assessing the impact of the molding process on the variability of surface irregularities of casting models. This research was conducted using a selected multiscale method, i.e., wavelet transformation, in both discrete and continuous perspective. The test samples were made both based on traditional methods of manufacturing casting models, i.e., machining of aluminum and wood, as well as using three additive technologies. The impact of the forming process on the variability of the topography of the produced models was evaluated. This research comprehensively relates to the assessment of the applicability of additive technologies, which are increasingly used in various industrial areas, as well as the impact of the process on surface topography in relation to scale. The statistical assessment based on the ANOVA analysis demonstrated that it is possible to distinguish between the surfaces before and after a specific number of forming cycles. Studies have shown that the impact of the forming process is relatively small, mainly affecting the long-term irregularity components, and there are no functional dependencies in terms of the impact of the forming process on the variation in surface topography in relation to the manufacturing method or its parameters.

Improved stomatognathic model for highly realistic finite element analysis of temporomandibular joint biomechanics

BackgroundMechanical response analysis of the temporomandibular joint (TMJ) is crucial for understanding the occurrence and development of diseases. However, the realistic modeling of the TMJ remains challenging because of its complex composition and multivariate associations. ObjectiveThis study aims to develop a highly realistic stomatognathic model that accurately represents the geometric accuracy, structural integrity, and material properties. And further optimizes the interference and establishes the application range of the simplifications and the assumptions. MethodsGeometric reconstruction of the bone was based on high-resolution image data, with the accuracy of the occlusal surface ensured by plaster cast model registration. Soft tissues such as cartilage, the disc, the periodontal ligament (PDL), and disc attachments often need to be approximated or assumed. Therefore, the finite element methods (FEM) was used to optimize these assumptions, including 1) the biomechanical effects of the thickness and modulus of the PDL, 2) the approximation of the geometry and material behavior of the disc, and 3) the simplification of the loading and boundary conditions. Results1) The deformation of the PDL causes tooth movement, which spreads to the distal condyle and further effects the TMJ load situation, 2) Disc reconstructed by MRI and hyperelastic material behavior are necessary for accurate TMJ loading analyses, 3) The loss of relative sliding movement between teeth interferes with realistic TMJ loading. ConclusionThe improved stomatognathic model delivers highly realistic and validated simulation, offering theoretical guidance for virtual treatments and TMJ multivariate overload studies.

Overwrapping Bivalved Casts: Does the Material Matter?

Circumferential integrity of bivalved casts (cut twice longitudinally) can be restored by overwrapping with different materials. This study compared the mechanical properties of solid casts and bivalved casts overwrapped with semirigid fiberglass (SF), elastic bandages (EB), and rigid fiberglass (RF) using an overwrapped-bivalved cast-bone fracture (OBCBF) model. This study used an MTS Bionix Servohydraulic system to test properties of OBCBF models in 4 conditions: intact Control made of RF (not bivalved or overwrapped), a Rigid overwrapped model made of a Control bivalved and overwrapped with RF, a Semirigid overwrapped model made of a Control bivalved and overwrapped with SF, and an Elastic model made of a Control bivalved and overwrapped with EB. Constructs were tested in 4-point bending. Force-displacement curves (FDC) were generated to calculate load-at-critical-failure (LCF, angulation > 10 degrees = 6.6mm vertical deformation) and stiffness. Five controls and 30 OBCBF models with 3 overwrapped cast types were tested, with each overwrapped cast type tested with 2 orientations of the initial cast bivalve axis, yielding 7 conditions (Control, Rigid 0 degrees, Rigid 90 degrees, Semirigid 0 degrees, Semirigid 90 degrees, Elastic 0 degrees, Elastic 90 degrees). Mean LCF was: Rigid 90 degrees > Rigid 0 degrees > Control > Semirigid 0 degrees > Semirigid 90 degrees > Elastic 90 degrees > Elastic 0 degrees ( P <0.0001). Mean stiffness was: Rigid 0 degrees > Rigid 90 degrees > Control > Semirigid 90 degrees > Semirigid 0 degrees > Elastic 0 degrees > Elastic 90 degrees ( P <0.0001). Multiple comparisons indicated no significant difference between LCF and stiffness for Semirigid 0 degrees/90 degrees casts compared with Controls. Mechanical properties of overwrapped bivalved casts change depending on the materials used to overwrap, with higher LCF and stiffness when overwrapping with RF > SF > EB; however, mean comparisons indicate that rigid bivalved casts overwrapped with SF did not have significantly different mean stiffness and LCF from controls and other cast models. This study compares the bending properties of a bivalved cast-construct overwrapped with different materials, providing basic science evidence for orthopaedic surgeons who have several choices of materials to overwrap bivalved casts.

Fabrication of a 3D Printer Filamnet Extruder

3D printing, an additive manufacturing process, transforms digital designs into physical objects by layering material. This mechanization adds consecutive layers to build up the complete entity, resulting in a 3D object. It develops objects progressively to formulate the preferred look. Filaments are the main component in a die cast model (FDM) 3D printer, these are thermoplastic substances that are injected through a hot die to form the object. These filaments are available in different types such as PLA, ABS, PETG, HDPE each of which has specific characteristics that offer different applications and material options in 3D printing. This paper depicts about fabricating and developing a design of a 3D filament extruder that can produce 1.75 mm diameter filaments from recycled HDPE material. The extruder consists of a motor, a speed controller, a cylinder, a hopper, band heaters, a thermocouple, a temperature controller, a fan, a nozzle and a winder. This system works in the correct temperature range of 350-370 degrees Celsius for melting thermoplastic materials (recycled HDPE). Extruder function is to feed the material from the nozzle into the hot cylinder. A motor screw pushes the metal into the nozzle, where it becomes the filament. This filament is then injected onto a substrate for later use in 3D printing. The temperature is determined using thermocouples and a temperature controller, which ensures optimal extraction conditions. A fan is designed to quickly cool the removed filament. The objective of this research is to create an economical as well as efficient filament to produce high quality filaments. Extruder performance is evaluated based on filament diameter consistency, material penetration and energy efficiency.

Three-Dimensional Evaluation of Treatment Effects and Post-Treatment Stability of Maxillary Molar Intrusion Using Temporary Anchorage Devices in Open Bite Malocclusion.

Background: We investigated treatment outcomes and post-treatment stability in 10 patients with an anterior open bite and nonsurgical orthodontics. Methods: The patients underwent maxillary molar intrusion using temporary anchorage devices (TADs) to deepen the overbite due to mandibular autorotation. Lateral cephalograms and dental cast models were obtained before treatment (T0), immediately after it (T1), and >1 year after it (T2). Skeletal and dental cephalometric changes and three-dimensional movements of the maxillary dentitions were evaluated. Results: At T0, cephalometric analysis indicated that patients had skeletal class I with tendencies for a class II jaw relationship and a skeletal open bite. During active treatment (T0 to T1), the maxillary first molar intruded by 1.6 mm, the mandibular first molar extruded by 0.3 mm, the Frankfort-mandibular plane angle decreased by 1.1°, and the overbite increased by 4.1 mm. Statistically significant changes were observed in the amount of vertical movement of the maxillary first molar, Frankfort-mandibular plane angle, and overbite. Three-dimensional (3D) dental cast analysis revealed that the maxillary first and second molars intruded, whereas the anterior teeth extruded, with the second premolar as an infection point. In addition, the maxillary molar was tipped distally by 2.9° and rotated distally by 0.91°. Statistically significant changes were observed in the amount of vertical movement of the central incisor, lateral incisor, canine and first molar, and molar angulation. From T1 to T2, no significant changes in cephalometric measurements or the 3D position of the maxillary dentition were observed. The maxillary and mandibular dentitions did not significantly change during post-treatment follow-up. Conclusions: Maxillary molar intrusion using mini-screws is an effective treatment for open bite correction, with the achieved occlusion demonstrating 3D stability at least 1 year after treatment.

A Comparative Study of Two Smartphone Applications and a Traditional Orthodontic Model Analysis Method

Introduction An orthodontic study used to determine whether teeth are positioned appropriately and whether there is an opportunity for orthodontic therapy or tooth extractions by model analysis. While certain manual model studies can be laborious and time-consuming, there are smartphone applications that can simplify the mathematical calculations necessary for orthodontic cast model analysis.  Objective The purpose of this research is to compare the outcomes and processing times of model analysis utilizing two smartphone apps, such as Model Analysis App and iModel Analysis, and the traditional technique.  Materials And Methods This is a comparative analytic study. The samples are made up of thirty dental casts that underwent several model studies, including as the Boltons, Ashley-Howe, Carey’s and Arch Perimeter assessments. A comparison in results and time was carried out for these model analyses using three methods - conventional method, iModel Analysis App and Model Analysis App.  Results The conventional technique gave results for a Bolton's overall ratio analysis of 3.3967±3.44579, iModel Analysis produced results of 3.4333±3.77709, while the Model Analysis app produced results of 4.6200±6.83744. The conventional technique yielded results for Bolton's anterior ratio analysis of 4.9133±5.81969; iModel Analysis produced results of 4.7700±5.57743; and the Model Analysis app produced results of 4.7500±5.59068. The results of arch perimeter discrepancy analysis for conventional method were 4.0000±3.15135, those for iModel Analysis was 4.0000±3.15135, and for Model Analysis app it was 4.0000±3.15135. The results of Carey’s discrepancy analysis for conventional method were 3.8667±2.59620, those for iModel Analysis was 3.8667±2.59620, and for Model Analysis app it was 3.8667±2.59620. The results of Ashley - Howe PMBAW% analysis for conventional method were 44.0200±3.71255, those for iModelAnalysis was 42.1367±5.74531, and for Model Analysis app it was 43.8133±3.71787. The results of Pont’s expansion analysis for conventional method, iModel Analysis and for Model Analysis app showed p value 0.114 (not significant = p&gt;0.05). The results of period required for the analysis by conventional method were 903.3000±30.19951, while those for iModelAnalysis was 399.2000±42.94375, and for Model Analysis app it was 392.0333±35.58233.  Conclusion There was no critical distinction within the results of the examinations done by the different methods. However, there was a noteworthy contrast within the time duration required to carry out the examination by conventional methods and that of iModelAnalysis and Model Analysis App.

Srovnání změn v dolním zubním oblouku u pacientů léčených konvenčními zámky a samoligujícími zámky

Aim: The aim was to assess the changes in the mandible in patients treated with conventional brackets compared to those treated with self-ligating brackets. In particular, we focused on the degree of transversal changes and the length of therapy. Material and method: The sample included 43 patients; 11 men and 32 women. The mean age was 22.2 years. The patients had complete permanent dentition, were treated without extractions, molars in Angle Class I. The subjects were divided into two groups – conventional brackets, self-ligating brackets. Measurements were performed in scans of cast models made prior to therapy (T1), after removal of fixed appliance (T2), the length of treatment was given in months. The changes in intercanine and intermolar distance were compared in teeth and in relevant points on WALA ridge of the mandible. ORTODONCIE | ročník 33 | č. 2/2024 ODBORNÉ PRÁCE / ORGINAL ARTICLES 29 www.ortodonciejournal.cz | e-mail: redakce@ortodonciejournal.cz, office@ortodonciejournal.cz Results: In lower first molars the change in intermolar width was significant in both groups both at T1 and T2. The change was significantly bigger in the group with self-ligating brackets. The change in intercanine width between T2 and T1 was statistically significant only in the group with self-ligating brackets when measured on canine tips. Measurements at FA points (the most prominent point in the middle of longitudinal axis of the clinical crown) did not prove significant change. At WALA the change between T2 and T1 was significant only in the group with self-ligating brackets and only in first lower molars (clinically the change was small). The change in the distance WALA-FA in first lower molars on the left and on the right between T2 and T1 was statistically significant in both groups, however, it was significantly bigger in the group with self-ligating brackets. The difference in the length of therapy was not statistically significant. Conclusion: In patients with self-ligating brackets there is a greater expansion in first molars and canines. We can also observe more prominent vestibular inclination of canines and first molars. In patien

Comparative study of nasal cavity drug delivery efficiency with different nozzles in a 3D printed model.

Nasal sprays are widely used in treating nasal and sinus diseases; however, there are very few studies on the drug delivery efficiency of nasal sprays. In this study, the drug delivery efficiency of three different nasal spray devices was evaluated in vitro using a 3D printed cast model of nasal cavity. Three nasal spray devices with different nozzles and angles of administration were used in the 3D model of the nasal cavity and paranasal sinuses. The spraying area (SA), maximal spraying distance (MSD), and spraying distribution scores on the nasal septum and lateral nasal wall were recorded. Different nasal spray devices have their own characteristics, including volume of each spray, SA, and plume angle. The SA of the three nozzles on the nasal septum increased with an increasing angle of administration. When the angle of administration was 50°, each nozzle reached the maximal SA. There was no statistically significant difference in MSD among the three nozzles at the three angles. The total scores for each nozzle using the three different spraying angles were as follows: nozzle A, 40°>30°>50°; nozzle B, 30°>40°>50°; and nozzle C, 30°>40°>50°. The total scores for different nozzles using the same angle were statistically significantly different and the scores for nozzle C were the highest. Nozzle C had the minimum plume angle. None of the three nozzles could effectively delivered drugs into the middle meatus at any angle in this model. The design of the nozzle affects drug delivery efficiency of nasal spray devices. The ideal angle of administration is 50°. The nozzle with smaller plume angle has higher drug delivery efficiency. Current nasal spray devices can easily deliver drugs to most areas of the nasal cavity, such as the turbinate, nasal septum, olfactory fissure, and nasopharynx, but not the middle meatus. These findings are meaningful for nozzle selection and device improvements.

Studying the Depth of Carbonifying Castings Obtained by the Lost Foam Casting Method with a Complex Polystyrene Composition

At present, lost foam casting method is an updated, long-term and the most economically feasible method in the foundry industry. Despite the fact that the casting technique is relatively simple, high demands are placed on the model materials. Carburization of the surfaces of steel castings obtained by the lost foam casting method is one of the main and the most significant problems in the use of this casting method. One solution is to use a complex composition of the material: a combination of cast and construction polystyrene. It was determined that the complex composition of the cast and construction polystyrene model in the ratio of 60 to 40% helps to reduce the depth of carburization and the percentage of internal defects. In addition, the cost of 1 kg of the complex composition models is 25% lower than the cost of 1 kg of models made of cast polystyrene.

Effects of occlusal wear on 16-year progression of non-carious cervical lesions-Results of the study of health in Pomerania (SHIP-START).

It is still discussed whether occlusal wear (OW) affects the formation of non-carious cervical lesions (NCCLs). To estimate effects of OW on the presence and development of NCCLs, using 16-year follow-up data from a cohort study. Occlusal and cervical defects were measured in 728 cast models (one from the upper jaw and one from the lower jaw) of 364 participants. Adjusted mixed-effects ordinal logistic models analysing estimated cross-sectional (N = 1308 teeth/291 subjects) and longitudinal (N = 718 teeth/226 subjects) associations of OW with NCCLs using tooth level data. OW size was cross-sectionally (OR = 1.74; 95% CI: 1.27-2.38 for OW size; OR = 0.97; 95% CI: 0.94-0.99 for squared OW size), but not longitudinally (OR = 1.14; 95% CI: 0.99-1.30) associated with odds of higher NCCL sizes. For cross-sectional analyses, predicted probabilities of an NCCL size of 0 decreased from about 0.996 to 0.010 for OW sizes of 0 to 25. Results suggest an association between OW and NCCL size. However, as longitudinal results were non-significant, while consistent in direction, large-scaled cohort studies are demanded to more precisely estimate effect strength.

Fully digital occlusion planning in orthognathic surgery – A crossover study

Orthognathic surgery enables patients with severe jaw malocclusions to normalise their chewing function and, as such, to improve their quality of life. Over the last few years, digitalisation has been set in motion by intraoral scanners and the improvement of planning software in the field of oral and maxillofacial surgery. Previous studies based on plaster cast models showed that the virtual occlusion based on digitally scanned models can be comparable to conventional methods. This retrospective crossover study aimed to prove that the virtual occlusion finding with the IPS CaseDesigner® (version 2.3.5.2, KLS Martin, Tuttlingen, Germany) is accurate enough to use intraoral scans exclusively. Materials and methodsA total of 23 orthognathic surgery patients receiving an intraoral scan for their treatment were included in this study. Two experienced maxillofacial surgeons haptically performed the occlusion finding on three-dimensional (3D) stereolithographic models using the fully digital pathway. One surgeon repeated the procedure a second time to evaluate intra-observer variability. The study aimed to show the difference between these two planning methods by upholding the surgical accuracy of less than 2 mm in translation and 2° in rotation. The conventional haptic occlusion was set as a reference throughout the whole study. The data were tested with a one-sample Wilcoxon test for the fit into the surgical accuracy. ResultsThe difference between the virtual and conventional groups was significantly smaller than the surgical accuracy (all p < 0.001). Both translational movements (anterior/posterior (median 0.51 mm [0.28, 0.88]), left/right (median 0.46 mm [0.20, 0.87]), cranial/caudal (median 0.37 mm [0.11, 0.69])) and rotations (Roll (median 0.71° [0.29, 1.35]), Pitch (median 0.72° [0.29, 1.44]), Yaw (median 1.09° [0.33, 1.60])) were in the range of surgical accuracy (2 mm/2°). The most significant differences were found in the anterior/posterior translation (median 0.51 mm [0.28, 0.88]) and the Yaw rotation (median 1.09° [0.33, 1.60]). ConclusionThese results demonstrate that the entirely virtual workflow in orthognathic surgery, including intraoral scanning and the virtual semi-automatic occlusion finding, represents a reliable and state-of-the-art alternative to the conventional haptic method.

Treatment Efficiency of Maxillary and Mandibular Orovestibular Tooth Expansion and Compression Movements with the Invisalign® System in Adolescents and Adults.

Aligners are an effective and esthetic orthodontic treatment option for permanent and mixed dentition. There are only a few studies dealing with the effectiveness of orovestibular tooth movement using aligners and applying adequate examination methods. In the present retrospective study, the aligner efficiency of orovestibular movements for the entire dentition was systematically evaluated using 3D superimposition, taking into account the influence of jaw, tooth type and Invisalign® system. Group 1 (n = 18 adults, Invisalign®) and Group 2 (n = 17 adolescents, Invisalign® Teen) were treated with Invisalign® Ex30 aligner material and Invisalign® specific auxiliary means. In this non-interventional retrospective study, pre- and post-treatment maxillary and mandibular plaster cast models were scanned and superimposed with ClinChecks® via Surface-Surface Matching Algorithm on unmoved teeth providing stable references. Effectivity of planned versus clinically realized movements was evaluated for each tooth. Statistics were performed with a t-test and Bonferroni-Holm correction (α = 0.05). Orovestibular movement efficiency was excellent without statistical significance regarding jaw, tooth type or Invisalign® system. Mandibular translational tooth movements were highly effective, and outstanding for premolars (91-98%). Maxillary translational tooth movements were successful for incisors and premolars, but less effective for canines and molars. Almost all teeth were moderately or very effectively corrected by crown tipping, performing better for mandibular (70-92%) than maxillary (22-31%) canines as much as for adolescent upper front teeth (81-85%) and lower canines (92%). Aligners are able to effectively implement translational orovestibular movements, supported by tilting the crowns for even more efficient implementation of the movements. This phenomenon was observed in our studies for all teeth in both jaws, regardless of the Invisalign® system used. Treatment planning should nevertheless take into account the individual patient parameters with regard to the movements to be performed in order to make the aligner therapy as successful as possible in terms of realizing the desired therapeutic goal.

A hybrid approach towards evaluation of average heat transfer coefficient in twin-roll strip casting mold

Continuous casting stands out as one of the most efficient and productive methods for producing billets, slabs, or thin sheets while conserving energy. Understanding the solidification dynamics and achieving defect-free sheets in continuous casting necessitates the accurate prediction of heat transfer coefficient (HTC) at the mold metal interface. Accurate prediction of HTC helps in selecting process parameters such as superheat temperature and casting velocity, which directly affect the production rate and quality of the cast component. Determining the HTC is a complex process, as it is influenced by various process parameters such as casting size, casting speed, superheat temperature, surface roughness, type of water used as a coolant, nozzle design and wettability. Therefore, the present study proposed a hybrid approach for finding HTC in a twin roll strip casting mold through a solidified shell shape, which is influenced by the factors affecting the heat transfer at the mold-metal interface. This approach integrates the experimental and simulation investigations. The numerical investigation used a three-dimensional coupled fluid flow and heat transfer equations with an assumed range of HTC (100–2000 W/(m2K)). The solidified shell shape for different HTCs was compared with the experimental solidified shape form at the outer wall of the mold using the solidification criteria. Results indicate that the initial HTC range of 100–1000 W/(m2K) does not lead to blockage of the graphite mold outlet. However, as HTC values approach 1000 W/(m2K) to 1400 W/(m2K), the melt obstructs the mold exit based on solidification criteria. The HTC values (1350 ± 150 W/(m2K)) obtained from the proposed methodology for mold, align well with the HTC values (1183 ± 593 W/(m2K)) calculated using lamellar spacing of the Al-Mg2Si composite microstructure. This hybrid approach presents a novel and straightforward method for determining HTC, offering accurate predictions that can enhance the precision of continuous casting models and provide a more nuanced understanding of solidification behavior.

A Cell-Based Nasal Model for Screening the Deposition, Biocompatibility, and Transport of Aerosolized PLGA Nanoparticles.

The olfactory region of the nasal cavity directly links the brain to the external environment, presenting a potential direct route to the central nervous system (CNS). However, targeting drugs to the olfactory region is challenging and relies on a combination of drug formulation, delivery device, and administration technique to navigate human nasal anatomy. In addition, in vitro and in vivo models utilized to evaluate the performance of nasal formulations do not accurately reflect deposition and uptake in the human nasal cavity. The current study describes the development of a respirable poly(lactic-co-glycolic acid) nanoparticle (PLGA NP) formulation, delivered via a pressurized metered dose inhaler (pMDI), and a cell-containing three-dimensional (3D) human nasal cast model for deposition assessment of nasal formulations in the olfactory region. Fluorescent PLGA NPs (193 ± 3 nm by dynamic light scattering) were successfully formulated in an HFA134a-based pMDI and were collected intact following aerosolization. RPMI 2650 cells, widely employed as a nasal epithelial model, were grown at the air-liquid interface (ALI) for 14 days to develop a suitable barrier function prior to exposure to the aerosolized PLGA NPs in a glass deposition apparatus. Direct aerosol exposure was shown to have little effect on cell viability. Compared to an aqueous NP suspension, the transport rate of the aerosolized NPs across the RPMI 2650 barrier was higher at all time points indicating the potential advantages of delivery via aerosolization and the importance of employing ALI cellular models for testing respirable formulations. The PLGA NPs were then aerosolized into a 3D-printed human nasal cavity model with an insert of ALI RPMI 2650 cells positioned in the olfactory region. Cells remained highly viable, and there was significant deposition of the fluorescent NPs on the ALI cultures. This study is a proof of concept that pMDI delivery of NPs is a viable means of targeting the olfactory region for nose-to-brain drug delivery (NTBDD). The cell-based model allows not only maintenance under ALI culture conditions but also sampling from the basal chamber compartment; hence, this model could be adapted to assess drug deposition, uptake, and transport kinetics in parallel under real-life settings.

Comparative Accuracy of Intraoral and Extraoral Digital Workflows for Short Span Implant Supported Fixed Partial Denture Fabrication: An In Vitro Study.

BACKGROUND The advent of digital impressions using computer-aided design and manufacturing technology (CAD/CAM) has simplified and improved the fabrication of implant prostheses in dentistry. The conventional impression has several drawbacks, including tray selection, material type, impression technique, impression disinfection, and cast model storage. The inaccuracies caused by distortion and contraction of impression material can be minimized with digital impressions. This study aimed to compare digital dental impressions of 10 working casts made using the Pindex laser removable die system to fabricate parallel drill channels vs 10 working casts made using the Di-Lok plastic tray removable die system. MATERIAL AND METHODS An implant master die with 2 dental implant analogs was fabricated. Ten working casts using the Pindex laser removable die system with parallel drill channels and 10 working casts using the Di-Lok plastic tray removable die system were fabricated. The working casts were scanned using an extra-oral laboratory scanner and the implant master model was scanned with an intra-oral scanner. RESULTS The properties of the casts made using the 2 systems were evaluated and analyzed with ANOVA and post hoc Tukey test. The mean horizontal linear distances between A1B1 (P<0.021), A2B2 (P<0.018), C1D1 (P<0.026), C2D2 (P<0.03), B1C1 (P<0.01), and mean vertical distances between B1A2 (P<0.015), C1D2 (P<0.001), B1B2 (P<0.028), and C1C2 (P<0.001) were significantly different between the Pindex system and Di-Lok tray system as compared to intra-oral scans. CONCLUSIONS Complete digital workflow with intra-oral scans were more than the partial digital workflow with extra-oral scans for the Pindex system and Di-Lok tray systems.