Tooth Contour Research Articles

Automatic 3D Teeth Reconstruction From Five Intra-Oral Photos Using Parametric Teeth Model.

Orthodontic treatment is a lengthy process that requires regular in-person dental monitoring, making remote dental monitoring a viable alternative when face-to-face consultation is not possible. In this study, we propose an improved 3D teeth reconstruction framework that automatically restores the shape, arrangement, and dental occlusion of upper and lower teeth from five intra-oral photographs to aid orthodontists in visualizing the condition of patients in virtual consultations. The framework comprises a parametric model that leverages statistical shape modeling to describe the shape and arrangement of teeth, a modified U-net that extracts teeth contours from intra-oral images, and an iterative process that alternates between finding point correspondences and optimizing a compound loss function to fit the parametric teeth model to predicted teeth contours. We perform a five-fold cross-validation on a dataset of 95 orthodontic cases and report an average Chamfer distance of 1.0121 mm2 and an average Dice similarity coefficient of 0.7672 on all the test samples in the cross-validation, demonstrating a significant improvement compared with the previous work. Our teeth reconstruction framework provides a feasible solution for visualizing 3D teeth models in remote orthodontic consultations.

DPML: Prior-guided multitask learning for dental object recognition on limited panoramic radiograph dataset

Addressing the growing need for advanced computer-aided diagnostic tools in dentistry, this study presents DPML (Dental Prior-guided Multitask Learning), a pioneering framework tailored for the analysis of dental panoramic radiographs in the face of data scarcity. DPML introduces a novel multitask learning strategy that effectively mitigates the limitations of sparse, well-annotated dental datasets. The methodology integrates four advanced techniques: targeted data augmentation for enhanced image diversity, segmentation structures for improved edge definition, polar-coordinate methods for precise tooth contour extraction, and a spatially informed classification strategy for accurate tooth type identification. Our comparative analysis demonstrates that DPML markedly surpasses traditional approaches in tooth segmentation, detection, and classification. Remarkably, it achieves a 95.06% mean Average Precision (mAP) and a 97.70% precision rate in dental object recognition tasks on a small-size dataset.

Lightweight design of steel sprocket for roller chain drive using explicit dynamic simulation

Roller chain drives are frequently applied in a variety of machinery for mechanical motion and power transmission. The roller engagement location on the sprocket tooth contour and the resulted contact behavior is governed by the wear of components and pretension of the chain. Therefore, the influence of extension of chain resulted from wear and pretension of chain on contact behavior was investigated numerically using explicit dynamics module of ABAQUS software. The contact angles evaluated from the numerical simulation were assessed relative to those obtained from the basic rigid body analytical formulation. The chain elongation of 3% increased the maximum contact force up to 52% during engagement with the driver sprocket. The contact force raised to 400% when the pretension in the chain drive was increased from 200 to 1000 N, leaving the force distribution pattern unaltered. The optimal design of a steel sprocket is realized through equivalent static finite element contact analysis of a sprocket engaged with 3% extended roller chain. The dynamic finite element analysis in conjunction with topology optimization reduced the weight of the sprocket by 24%.

Research on Dental Chairside Scanning and Diagnostic System Based on Artificial Intelligence and Deep Learning

Abstract The scanning technology and diagnosis and treatment system of dental chairs play a better auxiliary role in the level of oral diagnosis and treatment as well as the doctor’s therapeutic effect. In this paper, we design an oral chairside scanning and diagnosis and treatment system, which includes two modules for scanning, acquiring, and managing oral image information. Taking CBCT as the main technology, the steps of image reconstruction, generation, estimation of tooth main axis, and reconstruction of independent tooth contour are carried out sequentially to obtain the three-dimensional network model of teeth. Through the dental clinic information management system, the case base is effectively managed to enhance operational efficiency. The system presented in this paper is tested and applied to analyze its effects during usage. The results show that the maximum difference between the measurement of this system and the manual measurement is not more than 1mm. The mean values of the errors of the system designed in this paper in the angular error and apical error are 3.547±1.556mm and 1.154±0.265mm, respectively. The P-value is less than or equal to 0.05, which is significant, and the system performs very well in these two aspects.

Tooth Motion Monitoring in Orthodontic Treatment by Mobile Device-based Multi-view Stereo.

Nowadays, orthodontics has become an important part of modern personal life to assist one in improving mastication and raising self-esteem. However, the quality of orthodontic treatment still heavily relies on the empirical evaluation of experienced doctors, which lacks quantitative assessment and requires patients to visit clinics frequently for in-person examination. To resolve the aforementioned problem, we propose a novel and practical mobile device-based framework for precisely measuring tooth movement in treatment, so as to simplify and strengthen the traditional tooth monitoring process. To this end, we formulate the tooth movement monitoring task as a multi-view multi-object pose estimation problem via different views that capture multiple texture-less and severely occluded objects (i.e. teeth). Specifically, we exploit a pre-scanned 3D tooth model and a sparse set of multi-view tooth images as inputs for our proposed tooth monitoring framework. After extracting tooth contours and localizing the initial camera pose of each view from the initial configuration, we propose a joint pose estimation scheme to precisely estimate the 3D pose of each individual tooth, so as to infer their relative offsets during treatment. Furthermore, we introduce the metric of Relative Pose Bias to evaluate the individual tooth pose accuracy in a small scale. We demonstrate that our approach is capable of reaching high accuracy and efficiency as practical orthodontic treatment monitoring requires.

The effect of individual drilling sleeves on the precision of coronectomy tooth sections. An in vitro 3D-printed jaw model experiment

ObjectivesThe aim of this in vitro study was to evaluate the effect of a 3D-printed drill sleeve (DS) on the precision and duration of coronectomy sections.Materials and methodsThirty-six trainees and oral surgeons performed 72 coronectomy cuts in a 3D-printed, entirely symmetric mandible model. Coronectomy was performed freehand (FH) on one side and with a DS on the other side. The occurrence of “too superficial” (≥ 4 mm unprepared lingual tooth tissue) and “too deep” (drilling ≥ 1 mm deeper as tooth contour) cuts and sectioning times were registered.ResultsIn 7 cases, the sections were “too deep” with FH, while none with DS (OR: 18.56; 95%CI: 1.02–338.5; p = 0.048). The deviation between virtually planned and real cut depths was significantly greater in the FH group (1.91 ± 1.62 mm) than in DS group (1.21 ± 0.72 mm) (p < 0.001). A total of 18 “too superficial” buccolingual sections occurred with FH, while 8 cases with DS (OR: 3.50; 95%CI: 1.26–9.72; p = 0.016). Suboptimal sections did not correlate with experience (p = 0.983; p = 0.697). Shortest, suboptimal drillings were most frequently seen distolingually (OR: 6.76; 95% CI: 1.57–29.07; p = 0.01). In the inexperienced group, sectioning time was significantly longer with FH (158.95 ± 125.61 s vs. 106.92 ± 100.79 s; p = 0.038).ConclusionsThe DS effectively reduced tooth sectioning times by less experienced colleagues. Independently from the level of experience, the use of DS obviated the need for any preparation outside the lingual tooth contour and significantly decreased the occurrence of “too superficial” cuts, leaving thinner unprepared residual tooth tissue lingually.Clinical relevanceCoronectomy sections may result in lingual hard and soft tissue injury with the possibility of damaging the lingual nerve. The precision of the buccolingual depth-control can be improved, while surgical time can be reduced when applying a drilling sleeve.

A technique to convert a 3D printed cast used in the fabrication of an interim implant-supported crown into a definitive cast capturing the acquired emergence profile.

An esthetic peri-implant soft tissue contour is a critical element of the success of implant restorations in the esthetic zone. Once the optimal transmucosal soft tissue profile is formed, it needs to be accurately replicated on the master cast. This clinical technique involves the utilization of a silicone putty positioning index placed in the patient's mouth to accurately duplicate the external contour of teeth and soft tissue. By combining this positioning index with the implant-supported interim crown, the 3D-printed initial cast, which was used to fabricate the interim crown, can be conveniently and efficiently transformed into a definitive master cast.

GAN-based metal artifacts region inpainting in brain MRI imaging with reflective registration.

Metallic magnetic resonance imaging (MRI) implants can introduce magnetic field distortions, resulting in image distortion, such as bulk shifts and signal-loss artifacts. Metal Artifacts Region Inpainting Network (MARINet), using the symmetry of brain MRI images, has been developed to generate normal MRI images in the image domain and improve image quality. T1-weighted MRI images containing or located near the teeth of 100 patients were collected. A total of 9000 slices were obtained after data augmentation. Then, MARINet based on U-Net with a dual-path encoder was employed to inpaint the artifacts in MRI images. The input of MARINet contains the original image and the flipped registered image, with partial convolution used concurrently. Subsequently, we compared PConv with partial convolution, and GConv with gated convolution, SDEdit using a diffusion model for inpainting the artifact region of MRI images. The mean absolute error (MAE) and peak signal-to-noise ratio (PSNR) for the mask were used to compare the results of these methods. In addition, the artifact masks of clinical MRI images were inpainted by physicians. MARINet could directly and effectively inpaint the incomplete MRI images generated by masks in the image domain. For the test results of PConv, GConv, SDEdit, and MARINet, the masked MAEs were 0.1938, 0.1904, 0.1876, and 0.1834, respectively, and the masked PSNRs were 17.39, 17.40, 17.49, and 17.60dB, respectively. The visualization results also suggest that the network can recover the tissue texture, alveolar shape, and tooth contour. Additionally, for clinical artifact MRI images, MARINet completed the artifact region inpainting task more effectively when compared with other models. By leveraging the quasi-symmetry of brain MRI images, MARINet can directly and effectively inpaint the metal artifacts in MRI images in the image domain, restoring the tooth contour and detail, thereby enhancing the image quality.

ЭКСПЕРИМЕНТАЛЬНО-МАТЕМАТИЧЕСКОЕ ОПРЕДЕЛЕНИЕ ДЕФОРМАЦИОННЫХ РИСКОВ СТОМАТОЛОГИЧЕСКИХ МАТРИЦ ПРИ АНАТОМИЧЕСКОЙ АДАПТАЦИИ К ПРОКСИМАЛЬНОЙ ПОВЕРХНОСТИ ЗУБА

Introduction. Creating high-quality interdental contacts is the most important and difficult step in the treatment of proximal caries. In modern dentistry, most methods for restoring the proximal wall of teeth involve the use of dental matrices. The choice of matrix and the peculiarities of working with it are the determining factor in the formation of the proximal contour of the tooth and often causes difficulties, especially for young specialists.&#x0D; The aim of the study is to conduct an experimental-mathematical determination of the tensile strength of dental matrices to elastic deformation based on the curvature of the proximal surface of the chewing teeth.&#x0D; Materials and methods. The work consisted of 2 stages. Initially, a test bench was developed to assess the deformation capabilities of dental matrices, consisting of a strain gauge and a model of the proximal tooth wall with the possibility of fixing the matrix and imitating pushing. The model was created in SolidWorks software and 3D printed from light-cured polyamide. At the second stage, computer models of teeth and matrices were created, as well as an analysis of data from x-rays and other sources.&#x0D; Results. In the course of the work, the strength characteristics of dental matrices were obtained, the limits of their deformation capabilities were determined depending on the thickness of the material and the area of impact on it. Titanium matrices have the best strength characteristics, withstanding a force of 70 N, with an impact area of 2.25 mm2. An analysis of the curvature of the proximal surfaces of the chewing teeth revealed the best match between the matrix contour and the tooth contour on the medial surface of the first molars of the upper and lower jaws.&#x0D; Conclusions. To achieve high results in the restoration of the proximal walls of the teeth, in most cases it is recommended to press the matrix with an instrument with a working area of at least 2 mm2.

Indications, design considerations, and clinical outcomes of implant-supported fixed prostheses

Implant-supported fixed prostheses are a highly successful treatment option for replacing missing teeth, offering improved esthetics, function, and patient satisfaction. Design considerations play a crucial role in achieving optimal outcomes. Implant distribution and angulation should be carefully planned to ensure balanced load distribution and biomechanical stability. Occlusal considerations are vital to minimize mechanical complications and implant overloading, with proper adjustments and occlusal schemes implemented. The emergence profile should replicate natural tooth contours for esthetic integration and ease of oral hygiene maintenance. Material selection is essential, considering factors such as occlusal loading, esthetic requirements, and patient-specific considerations. Biomechanical analysis helps identify stress distribution patterns and optimize prosthesis design for long-term success. Patient satisfaction is high, with improved chewing ability, speech, and overall quality of life reported. Long-term success rates exceed 90%, influenced by implant survival, peri-implant health, maintenance of prosthesis integrity, and patient satisfaction. Thorough patient assessment, treatment planning, precise surgical and prosthetic execution, and comprehensive follow-up care are crucial for favorable outcomes. Implant-supported fixed prostheses provide functional and esthetic restorations, enhancing oral health and overall well-being.

Modified bracket holder with magnifying lens: A precise bracket positioner

Awell finished orthodontic case is a result of precise bracket positioning during initial bonding. Orthodontists strive for accurate positioning of brackets so that we can avoid / minimize finishing arch wire bends. During the Bonding procedure, placing the bracket on tooth surface and then adjusting it to ideal position is time-consuming, also bracket displacement will reduce the bond strength. Therefore, to avoid these drawbacks this modified bracket holder with magnifying lens gives magnified image of tooth surface with precise visibility, so that bracket placement can be accurate according to the tooth contour with respect to mesio –distal and vertical position of tooth.

Endodontic Periodontal Lesion Due to Inadequate Endodontic Treatment: an Alert for Dental Practitioners: A Case Report

The complex intercommunication between the pulpal and periodontal tissues may result in the formation of endodontic periodontal lesions. The relationship between the pulpoperiapical and periodontal microflora explains the possibility of infection spreading between the root canal and the periodontal pocket. The associated tooth has periodontal involvement in the form of either pocket, clinical attachment loss, furcation loss, or other infrabony defects and also pulpoperiapical disease. The diagnosis of endodontic periodontal diseases can sometimes be challenging to make an accurate diagnosis. We report a case of a 34 years old female patient with an endo-perio lesion in the right lower second molar # 47 which was previously treated with endodontic therapy followed by prosthetic rehabilitation. We highlight the need for adequate endodontic management and the importance of maintaining proper prosthetic contour for the prevention of endodontic periodontal lesions. In our case, the endodontic periodontal was the result of inadequate endodontic treatment by the dental clinician. Hence with this case, we reiterate the importance of adequate and complete endodontic treatment and also the need to follow the tooth contours during prosthetic rehabilitation as a preventive protocol for endodontic periodontal lesions.

Comparative evaluation of the fracture resistance of reattched fragments using three different retentive methods: An in vitro study

: Traumatic injuries to the anterior teeth are one of the most difficult and perplexing problems faced in the paediatric dentistry. Coronal fracture of the anterior teeth is a common form of dental trauma that mainly affects the maxillary and mandibular incisors. Fragment reattachment has been the preffered technique among clinicians because it has several advantages over the composite restorations such as it is a conservative procedure, maintains original tooth contours, translucence and incisal edge wears at similar rate to adjacent teeth.: To compare and evaluate the fracture resistance of reattached fragments using three different methods.Forty sound permanent mandibular central and lateral incisor were selected and mounted in self-cure acrylic resin. The teeth were sectioned with a diamond disc 3mm short of the incisal edge and they were randomly divided into four groups (n=10). Group I – simple reattachment, group II- internal dentinal groove, group III – vertical groove with fiber reinforced post placement, group IV – overcontouring done before the reattachment procedure. The force required to fracture the specimen were recorded using an onscreen calibration tool of the universal testing machine. The results were statistically analyzed.: The results showed that group I, group II and group IV required lesser force to fracture when compared with group III.: The group restored with fiber reinforced post showed the highest value of fracture strength while the simple reattachment had the lowest value.

Evaluation of the Accuracy of Measurements Made at Probable Implant Site Using Cone-Beam Computed Tomography

Introduction: Computed Tomography (CT) was the most used 3D radiographic diagnostic technique for years, but cone-beam computed tomography (CBCT) was created to reduce radiation exposure, costs, and accessibility issues . Aim: To evaluate the accuracy of CBCT measurements made at probable implant sites. Materials and Methodology: This was a retrospective study that compared panoramic reconstructed CBCT with RVG measurements at 77 probable implant sites, especially mandibular posterior tooth-bounded edentulous areas. Measurements made were the mesiodistal width of the edentulous area at the crest and at the highest point of the adjacent tooth's contour and the length of the natural teeth in the mandibular first molar region from the highest cusp to the apex next to the edentulous area. Statistical analysis was done with the Statistical Package for the Social Sciences (SPSS) and the independent t-test. Results: The mean difference between CBCT and radiovisiography (RVG) readings for mesiodistal width at the crest and highest contour of the edentulous bounded two neighboring teeth was −0.21039 and 0.02961, respectively, which was not statistically significant. The mean difference between CBCT and RVG readings along the tooth was 0.80481, which was statistically significant (P = 0.018). RVG outperformed CBCT (SD = 1.7) in estimating tooth length. Conclusion: Conventional RVG radiographic measurements were similar to real tooth length, whereas CBCT panoramic reconstructions underestimated the lengths by 15% but were clinically acceptable. Clinical CBCT application requires operator abilities and knowledge with software. It is critical to pay close attention to the calibration of data obtained from clinical examination and CBCT.

ESTIMATION OF CIRCULAR SAW TOOTH MICROGEOMETRY

This study solves the problem of estimating the microgeometry of a circular saw tooth. For research, a circular saw with one false tooth, equipped with a VK6M hard alloy plate, was used as a cutting tool. The purpose of this study is to attempt to estimate the real wear curve of a wood-cutting tool edge. The cutting was performed on an experimental installation, which is a drive shaft with a saw attached to it, with the possibility of adjusting the cutting and feeding speeds. The tooth tip was photographed after some wear in a plane perpendicular to the short blade edge with 30-50x magnification. The tooth contour was measured using a large BMI-2 toolmaker microscope. As a result of the study, a method for estimating the sharpness of the tool edge using tangent and subsequent calculations has been developed, which allows figuring out both the local curvature and the average curvature of the entire form of tooth. This method allows finding the sections of the form of tooth with minimal and maximum curvature, as well as figuring out the curvature of a particular section of the form of tooth and the area (wear) of this section. The proposed solution allows transitioning from qualitative features of wear to accurate quantitative estimates, expressed either in units of area or units of mass, which allows comparing the tool materials from which teeth are made in cases where microgeometry is approximately the same, while wear is different. The practical significance of this study lies in the possibility of estimating the state of the parameters of the cutting unit and allows predicting its changes during operation (the degree of wear, the frequency of re-sharpening, finding the ultimate tool service life)

A fine-grained network for human identification using panoramic dental images

SummaryWhen accidents occur, panoramic dental images play a significant role in identifying unknown bodies. In recent years, deep neural networks have been applied to address this task. However, while tooth contours are significant in classical methods, few studies using deep learning methods devise an architecture specifically to introduce tooth contours into their models. Since fine-grained image identification aims to distinguish subordinate categories by specific parts, we devise a fine-grained human identification model that leverages the distribution of tooth masks to distinguish different individuals with local and subtle differences in their teeth. First, a bilateral branched architecture is designed, of which one branch was designed as the image feature extractor, while the other was the mask feature extractor. In this step, the mask feature interacts with the extracted image feature to perform elementwise reweighting. Additionally, an improved attention mechanism was used to make our model concentrate more on informative positions. Furthermore, we improved the ArcFace loss by adding a learnable parameter to increase the loss of those hard samples, thereby exploiting the potential of our loss function. Our model was tested on a large dataset consisting of 23,715 panoramic X-ray dental images with tooth masks from 10,113 patients, achieving an average rank-1 accuracy of 88.62% and rank-10 accuracy of 96.16%.

Features of the synthesis of transmissions with parallel axes for machining equipment

A mathematical model of the synthesis of the initial contour of the teeth of gears according to the criterion of the reduced curvature of the working surfaces is presented. The geometric parameters of the initial contours of the gear teeth with high values of the performance criteria for machining equipment are determined. Keywords: initial contour, gear transmission, criterion, strength, analysis. mukhovatiy@mail.ru

Clear aligner therepy – A review

Aesthetics is a major factor in Orthodontic treatment and it is a primary concern among patients seeking orthodontic treatment. To meet the growing aesthetic desire for an alternative to traditional braces, researchers have created a variety of alternatives, including ceramic or composite braces, lingual orthodontics, and transparent aligners. Clear aligner therapy is a treatment that consists of a set of clear dental appliances that are custom-made to fit the contour of a patient's teeth. Clear Aligners are an alternative to traditional braces that are used to guide teeth into appropriate alignment. Clear aligners, like braces, utilise a progressive force to regulate tooth movement, but without the need of metal wires or brackets.

Comparative Evaluation of Marginal Fit of Three Provisional Restorative Materials in Different Mediums: An In-Vitro Study

Temporaries are used as placeholders before the permanent crowns are installed. If the temporary crown is not fitted properly the tooth can be subject to increased decay and gums can become inflamed causing gingivitis which leads to other more serious problems. A provisional fixed restoration will provide a template for defining tooth contour, esthetics, proximal contacts, ridge contacts and occlusion. Margins made by the indirect technique are considered to be more accurate than those made by the direct technique. The purpose of this in vitro study was to compare the marginal accuracy of provisional crowns made from three different biomaterials using the established indirect method in different environments and to evaluate the effect of water absorption on polymerization shrinkage and the effect of polymerization shrinkage occurring in dry storage for a week. Method:Variables used in this study are: a) Revotek LC-light cured composite b) Protemp II c) poly methyl methacrylate. An aluminium master die was machined with dimensions: 5mm length, 10mm gingival diameter, 5 degree taper, and 1mm shoulder then dental stone die was prepared by making an impression of this experimental model using a poly vinyl siloxane material. Both group A and group B consisted of seven specimens each of DPI, ProtempII, Revotek LC. The specimens were evaluated using measuring microscope (Biolux), which had an eyepiece graticule of 1/10th of an mm. The seven specimens in group A (DPI, ProtempII, Revotek LC) were kept in air at room temperature for one week on the dental stone cast and the readings were tabulated and the mean values were obtained. The seven specimens in group B (DPI, ProtempII, and Revotek LC) were kept in water at room temperature for one week and the readings were tabulated in the same manner and the mean values were obtained. Results: Comparative statistics of the mean values of the specimens kept in air at room temperature showed that DPI had the least marginal discrepancies followed by ProtempII, Revotek LC. The values were highly significant (.002) Comparative statistics of the mean values of the specimens kept in water at room temperature showed that DPI had the least marginal discrepancies followed by Revotek LC, ProtempII. The values were highly significant (.009). Conclusion: After one week in air at room temperature and after one week in water at room temperature DPI recorded the minimal marginal discrepancy. When stored in air at room temperature, DPI had the best marginal adaptation. All of the materials showed evidence of continued polymerization shrinkage after storage in air for a week. Water absorption compensated for polymerization shrinkage in DPI and ProtempII whereas Revotek LC was an exception. Keywords: light cured composite, Protemp II-Bis –acryl composite, poly methyl methacrylate, marginal adaptation, provisional restoration.

Усовершенствование оборудования механической обработки за счет синтеза исходных контуров внеполюсных зубчатых передач

The synthesis of the initial contours of the teeth of out-of-pole gears on parallel axes according to the criterion of the contact strength of the working surfaces is presented, the geometric parameters of the original contours of the gear teeth with high contact strength of the working surfaces are determined. An assessment was carried out according to the following performance criteria: power loss in the engagement, the thickness of the oil layer, the specific work of friction forces, galling. transmission.