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Information on the dimensional changes in maxillary and mandibular dentures made by using computer-aided design and computer-aided manufacturing (CAD-CAM) techniques under uniform testing conditions is lacking.The purpose of this in vitro study was to evaluate the dimensional changes and reproducibility of maxillary and mandibular dentures by using CAD-CAM-milled and 3D-printed techniques.Maxillary and mandibular edentulous models with wax occlusal rims were scanned, and dentures were designed by using a CAD software program and fabricated by using 2 techniques and materials: CAD-CAM-milled (CCM) and 3D-printed (3DP). The 3DP fabrications included 4 subgroups: dentures printed with a 90-degree build angle with UV light polymerization on the reference model (3DP 90M), dentures printed with a 90-degree build angle and light polymerization without the reference model (3DP 90), dentures printed with a 45-degree build angle with light polymerization on the reference model (3DP 45M), and dentures printed with a 45-degree build angle and light polymerization without the reference model (3DP 45). The preprocessing and postprocessing scan files of each denture produced by CCM and 3DP were superimposed by using a surface matching software program. Ten points each on maxillary and mandibular dentures were measured for deviations after processing. Additionally, for each denture, the widths were measured between the canines and molars, the anteroposterior plane from cusp tips between the canines and molars, and the vertical plane from the cusp tip of the canines to the marginal gingiva. They were then compared with those in the denture design CAD cast. The Kruskal-Wallis analysis of variance test was used for statistical analyses (α=.05).According to digital superimposition, CCM had the smallest values of deviation with no statistical difference (P.05), indicating more uniform results from measurement points in both maxillary and mandibular dentures, followed by 3DP 90M, 3DP 90, 3DP 45M, and 3DP 45. Regarding the width measurements, CCM had the smallest values of deviation (P.05). In 3DP, smaller deviation values were observed at the vertical plane from the tip of the canine to the marginal gingiva, and larger values were observed in the intermolar width (P.05).CCM exhibited smaller dimensional changes and better reproducibility among the tested techniques. In 3DP, the build angle and methods of light postprocessing influenced the dimensional stability. The 90-degree build angle with additional light polymerization on the cast improved the dimensional deviations.

Made available in DSpace on 2022-05-01T06:02:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Objectives: This study evaluated the effect of restoration occlusal design on the maximum fracture load and stress distribution of a feldspathic ceramic crown. Materials and Methods: Twenty dentin analogues were used to simulate a full-crown preparation. Next, 20 feldspathic crowns were milled according to the occlusal design parameter available in the CAD database (Young or Adult). The crowns were cemented with dual cure resin-cement and loaded until fracture at 1 mm/min crosshead speed. Data were analyzed by using one-way ANOVA and Tukey tests (p < 0.05). The same geometry and experimental setup was modeled and exported to the computer aided engineering software and tensile stress concentration was calculated using the finite element method with 300 N occlusal load simulation. Results: The occlusal anatomy significantly influenced the load-to-fracture (p < 0.05). Adult design showed higher mean values (1149 ± 201 N) than Young design (454 ± 77 N). The maximum principal stress criteria showed similar stress pattern for both designs, however, the highest stress concentration was calculated for Young design (91 MPa) in the occlusal surface. Conclusions: An anatomy design with reduced cusp angulation and less evident occlusal sulcus can reduce the stress concentration and increase the fracture load for feldspathic CAD/CAM posterior crowns. Department of Dental Materials and Prosthetics São Paulo State University (UNESP) Institute of Science and Technology Division of Dental Biomaterials Center for Dental and Oral Medicine Clinic for Reconstructive Dentistry University of Zurich Department of Dental Materials and Prosthetics São Paulo State University (UNESP) Institute of Science and Technology

The aortic valve is the functional unit of cusp and root. Various geometrical and functional analyses for the aortic valve unit have been executed to understand normal valve configuration and improve aortic valve repair. Different concepts and procedures have then been proposed for reparative approach, and aortic valve repair is still not standardized like mitral valve repair. It has become apparent, however, that interpretation of the geometry of the aortic cusp and root and its appropriate application to operative strategy lead to creating a functioning aortic valve. Herein, the aortic valve geometry and its clinical implications are reviewed to provide information for the selection of appropriate operative strategies.

Objectives To investigate the effects of long-term use of the lower lingual arch (LLA) on the sagittal and vertical positions of the permanent lower incisors and first molars. Materials and Methods The sample consisted of 98 patients who were treated with an LLA (LLA group) and 39 patients who were treated without an LLA (no-LLA group). The positional changes of the lower incisors and first molars were analyzed after performing mandibular structural superimpositions on lateral cephalometric radiographs taken before treatment (T1) and at the end of LLA therapy (T2). The mean ages at T1 and T2 were 8.5 years and 13.2 years, respectively. Study casts were analyzed to quantify arch dimensional changes. Results Mesial movement of the lower molar cusp was similar between the LLA and no-LLA groups, but the vertical position was slightly greater at T2 in the LLA group. In the LLA group, there was a molar tip-back effect, and the lower incisors were proclined 4.2° more than in the no-LLA group. Arch perimeter decreased 3.6 ± 2.6 mm without an LLA and 0.97 ± 3.7 mm with an LLA. Intercanine and intermolar widths both increased about 1 mm more with an LLA (P < .0001). Conclusions The LLA does not seem to restrict mesial movement and vertical eruption of the lower incisors and molars in the long term. The LLA effectively preserves the arch perimeter at the expense of a slight lower incisor proclination.

Sinus of Valsalva aneurysms are abnormal bulges of the aortic root caused by a tissue deficiency resulting in an enlargement of the aortic root in the area between the aortic annulus and the sinotubular junction. Frequently, sinus of Valsalva aneurysms are asymptomatic. However, sinus of Valsalva aneurysms can also be potentially fatal due to their risk of rupture. We present a case of a 49-year old asymptomatic male patient with a rare image of a sinus of Valsalva aneurysm of the non-coronary cusp which was initially mistaken for a right ventricular thrombus. Surgical repair of the sinus of Valsalva aneurysm was eventually achieved by a valve sparing root replacement and the patient was discharged 7 days after surgery. This case report shows that sinus of Valsalva aneurysms are vulnerable to misdiagnosis when it is not initially suspected. Because of the potential fatality of this phenomenon we would like to underline the necessary vigilance in the diagnostic process, as sinus of Valsalva aneurysms can be missed when the physician is not aware of this potential rare diagnosis.

Introduction: After orthodontic treatment, some teeth undergo external root resorption due to different factors, such as the root shape, oral habits, biological and genetic factor, gender, and age. Furthermore, extraction cases, long treatment duration, and the amount of force applied during the treatment might be related to root resorption. Materials and Methods: Panoramic radiographs for 226 patients treated in the orthodontic department were screened. The lower first permanent molars, lower second premolars, and lower first premolars were measured in centimeters on a ruler using ImageJ System. Teeth were measured from the cusp tip to the cementoenamel junction (CEJ) and from the CEJ to the root apex, and then, the tooth was measured as a whole before and after the treatment. Results: Multiple analysis of variance showed that there were no interactions between the root lengths of all teeth tested and either gender, treatment type, or treatment duration (P > 0.05). Conclusion: Based on the results of this study, no statistically significance relationship between external apical root resorption and gender, type of treatment, and treatment duration was found.

Teeth act as tools for acquiring and processing food, thus holding a prominent role in vertebrate evolution. In mammals, dental-dietary adaptations rely on tooth complexity variations controlled by cusp number and pattern. Complexity increase through cusp addition has dominated the diversification of mammals. However, studies of Mammalia alone cannot reveal patterns of tooth complexity conserved throughout vertebrate evolution. Here, we use morphometric and phylogenetic comparative methods across fossil and extant squamates to show they also repeatedly evolved increasingly complex teeth, but with more flexibility than mammals. Since the Late Jurassic, multiple-cusped teeth evolved over 20 times independently from a single-cusped common ancestor. Squamates frequently lost cusps and evolved varied multiple-cusped morphologies at heterogeneous rates. Tooth complexity evolved in correlation with changes in plant consumption, resulting in several major increases in speciation. Complex teeth played a critical role in vertebrate evolution outside Mammalia, with squamates exemplifying a more labile system of dental-dietary evolution., Tooth morphology has provided many insights into the tempo and mode of dietary evolution in mammals. A study of fossil and extant squamates shows that this group also repeatedly evolved increasingly complex teeth with more flexibility than mammals, and that higher tooth complexity and herbivory likely led to higher speciation rates.

Background:The study of dental morphological characteristics is useful for providing information for phylogenic, anthropological, forensic and genetic studies and understanding variations within and among species.The aim of the study was to investigate, compare and document the distinctive cuspal outlines and groove patterns of permanent maxillary molars in a sample of Egyptian population, this was performed morphologically through study casts inspection, followed by statistical analysis of the collected data. Materials and Methods: 50 upper study casts models of patients aged above 21 years from the Orthodontic Department of Faculty of Dentistry at Ain Shams University with all maxillary molars teeth present were collected. Results: Regarding cusp number and groove pattern of maxillary molars, M1 showed prevalence of 4H groove pattern while 3 cusps and U groove pattern was the most common pattern for M2&M3.Regarding the frequency of molar tubercle (tubercle of carabelli), M1 showed prevalence of type I molar tubercle(depression), while the absence of the molar tubercle was the most common pattern for M2 &M3.Occlusal outline of M1 showed prevalence of the rhomboidal outline while M3 showed prevalence of triangle outline. Statistical results showed significant difference between the maxillary molars.Conclusions: The morphological characteristics of teeth in a sample of Egyptian population were consistent with those of other studies performed on different populations using similar methodology.

The aortic chordae tendineae strands are suggested to be embryonic remnants of the cusp formation process. We herein describe a 70-year-old male who was admitted to our hospital for shortness of breath and chest tightness. During echocardiographic examination, severe aortic regurgitation with a ruptured fibrous strand was detected. Moreover, another fibrous strand was found by three-dimensional transesophageal echocardiography (TEE). To our knowledge, this is the first literature review of aortic chordae tendineae strands, including diagnosis, management, and mechanisms of aortic regurgitation due to such informal strands.

The article is devoted to considering church construction on the territory of Kostanay city, which broadly speaking includes building of churches, church government, and administrative organization. The investigations have led to a conclusion that the main factors contributing to soaring church construction in rapidly growing Kostanay city on the cusp of 19th and 20th centuries were active migration processes resulting in movement of significant number of orthodox people from European part of Russia, as well as development of missionary activities among native population. On the basis of photographic documents, the authors have characterized orthodox temple architecture, as well as subdivided churches according to institutional principle, composition and spatial dynamics, and style of space-planning decisions. It was found that a greater number of churches in Kostanay were the parish ones, prayer halls of temples had a single or five-domed top, the following architectural styles were distinguished in the temple construction: eclecticism, elements and techniques of provincial Baroque and classicism, national Russian style combined with the techniques of the brick style. Within church construction, the government was tasked with designing living environment in general, rather than religious buildings. The urban realm balanced all aspects of confessional life, included its physical, functional_ pragmatic, social, as well as emotional and artistic parameters. After Orthodox temples were built and given certain functions, there were changes in the social structure of the society, the parish was growing, the number of priests was increasing, which led to changes in the urban realm. The environment is connected with the main elements of the urban system, having stability and variability, respectively, which resulted in a set of individual and collective creative acts. The Russian Orthodox Church had a great influence on education and the moral state of urban dwellers. A network of parochial schools was formed at each church and each temple. Such schools pursued not only educational, but also missionary goals.

The North Indian states of Punjab and Haryana (P&H) are a part of the water-rich Indo-Gangetic river basin. Despite this abundance, both states are on the cusp of a severe water crisis due to groun...

Purpose Adaptive slicing is a key step in three-dimensional (3D) printing as it is closely related to the building time and the surface quality. This study aims to develop a novel adaptive slicing method based on ameliorative area ratio and accurate cusp height for 3D printing using stereolithography (STL) models. Design/methodology/approach The proposed method consists of two stages. In the first stage, the STL model is sliced with constant layer thickness, where an improved algorithm for generating active triangular patches, the list is developed to preprocess the model faster. In the second stage, the model is first divided into several blocks according to the number of contours, then an axis-aligned bounding box-based contour matching algorithm and a polygons intersection algorithm are given to compare the geometric information between several successive layers, which will determine whether these layers can be merged to one. Findings Several benchmarks are applied to verify this new method. Developed method has also been compared with the uniform slicing method and two existing adaptive slicing methods to demonstrate its effectiveness in slicing. Originality/value Compared with other methods, the method leads to fewer layers whilst keeping the geometric error within a given threshold. It demonstrates that the proposed slicing method can reach a trade-off between the building time and the surface quality.

(1) Background: to propose a new approach for crown veneers, with the use of an aesthetic porcelain coating, only in part of the zirconia infrastructure, and to analyze its biomechanical behavior to minimize chipping failures. (2) Methods: a maxillary molar was modeled using CAD software, preparing for traditional crowns and veneer crowns with various lengths. Five groups were formed: M—control group (monolithic crown of ultra-translucent zirconia), B—conventional (bilayer crown of ultra-translucent zirconia and ceramic covering), V—veneer (ultra-translucent zirconia crown with reduction only in the buccal and application of covering ceramics), V1—ultra-translucent zirconia crown with buccal reduction and 1 mm occlusal extension for covering ceramic application), V1.5—ultra-translucent zirconia crown with buccal reduction and 1.5 mm occlusal extension for application of covering ceramics. A load of 600 N was performed axially to a fossa bottom to simulate parafunction, and 300 N to the cusp tip to obtain the maximum principal stress results. (3) Results: group B showed a higher stress concentration in the occlusal region of the restorations, while the other groups absorbed the stress and dissipated it throughout the crown, presenting a higher stress concentration in the interface region with the tooth. (4) Conclusion: the highly translucent zirconia ceramic only associated with buccal covering ceramic could add aesthetic gain and rigidity to the system and could be a good option to restore maxillary molars in patients who do not have parafunction.

STATEMENT OF PROBLEM Whether additively produced zirconia could overcome problems with conventional computer-aided design and computer-aided manufacture (CAD-CAM) such as milling inaccuracies and provide accurate occlusal veneers is unclear. PURPOSE The purpose of this in vitro study was to compare the marginal and internal fit of 3D-printed zirconia occlusal veneers with CAD-CAM-fabricated zirconia or heat-pressed lithium disilicate ceramic (LS2) restorations on molars. MATERIAL AND METHODS The occlusal enamel in 60 extracted human molars was removed, with the preparation extending into dentin. Occlusal veneers at a thickness of 0.5 mm were designed and manufactured according to their group allocation: 3DP, 3D-printed zirconia; CAM, milled zirconia; and HPR, heat-pressed LS2. The prepared teeth and restorations were scanned and superimposed, and the marginal and internal adaptation were measured 2- and 3-dimensionally; the production accuracy (trueness) was also measured. The comparisons of the group medians were performed with nonparametric methods and a pairwise group comparison (α=.05). RESULTS Three-dimensionally printed zirconia revealed median outcomes of 95 μm (margin), 252 μm (cusp), 305 μm (fossa), and 184 μm (3D internal adaptation). CAM showed median values of 65 μm (margin), 128 μm (cusp), 203 μm (fossa), and 120 μm (3D internal adaptation). The respective values for the group HPR were 118 μm (margin), 251 μm (cusp), 409 μm (fossa), and 180 μm (3D internal adaptation). Significant differences (P

Previous research has shown that the course of income inequality of a US cohort in retirement depends on the inequality measure used. For example, the variance of logarithmic income, a bottom sensitive measure, displays a decidedly declining trend. This study examines the mechanisms that underlie these income inequality changes as a cohort enters their retirement years using longitudinal data over a 20-year period and a variety of methods. In particular, individual income trajectories and income instability just before and in retirement are investigated. The results show (i) the variance of logarithmic income falls as the cohort ages primarily due to a reduction in income instability; (ii) on average, the rich and poor get poorer as they age into retirement; and (iii) consistent with previous research, a person’s place in the retirement income distribution is largely determined before retirement.

Background: Aortic cusp extension is a technique for aortic valve (AV) repairs in pediatric patients. The choice of the material used in this procedure may influence the time before reoperation is required. We aimed to assess post-operative and long-term outcomes of patients receiving either pericardial or synthetic repairs. Methods: We conducted a single center, retrospective study of pediatric patients undergoing aortic cusp extension valvuloplasty (N=38) with either autologous pericardium (n=30) or CorMatrix (n=8) between April 2009 and July 2016. Short and long-term postoperative outcomes were compared between the two groups. Freedom from reoperation was compared using Kaplan Meier analysis. Degree of aortic stenosis (AS) and aortic regurgitation (AR) were recorded at baseline, post-operatively, and at outpatient follow-up. Results: At five years after repair, freedom from reoperation was significantly lower in the CorMatrix group (12.5%) compared to the pericardium group (62.5%) (P = 0.01). For the entire cohort, there was a statistically significant decrease in the peak trans-valvar gradient between pre- and post-operative assessments with no significant change at outpatient follow-up. In the pericardium group, 28 (93%) had moderate to severe AR at baseline which improved to 11 (37%) post-operatively and increased to 21 (70%) at time of follow-up. In the biomaterial group, 8 (100%) had moderate to severe AR which improved to 3 (38%) post-operatively and increased to 7 (88%) at time of follow-up. Conclusion: In terms of durability, the traditional autologous pericardium may outperform the new CorMatrix for AV repairs using the cusp extension method.

The results of 2.5D-simulation of the dynamics of particles of a high-current ion beam moving in a magnetic field of acute-angled geometry (cusp), compensated in charge and current by an electron beam injected along the radius onto the axis from the periphery, uniformly in azimuth, are presented. The influence of own space charge fields and polarization fields on the dynamics of ions is clarified. It is shown that at high densities of the electron and ion beams, the electron beam injected into the cusp together with the ion beam, moving along the magnetic field lines, drags the ion beam away from the axis to the periphery into the region of zero magnetic field. At the exit from the cusp, the electron beam injected along the radius onto the axis drifts along the axis in a uniform magnetic field, while the ion beam performs oscillatory motion by radius in the crossed the electric field of the electron beam space charge and the longitudinal magnetic field.

This report describes a case of talon cusp treated by an intentional partial pulpotomy, which made it possible to recontour the tooth crown into the desired shape. The patient was an 11-year-old boy with a large talon cusp on the lingual surface of the right maxillary lateral incisor. He was referred to our clinic for treatment of abnormality cusp because it was expected to impede orthodontic treatment. The talon cusp was amputated using an intentional partial pulpotomy. The procedure resulted in successful recontouring of the tooth crown into the desired morphology and the dental pulp exhibited a vital reaction at three years after the operation.

In this paper, a self-designed cusp external magnetic field (EMF) was employed to assist the two-electrode TIG (T-TIG), and its common conductive channel characteristics were aimed to optimize the energy distribution of T-TIG. The influences of the cusp EMF on arc morphology, arc plasma information, and arc pressure of T-TIG were respectively analyzed based on a high-speed camera, spectrograph, and pressure sensor. The results showed that the cusp EMF could compress T-TIG in the direction parallel to the array of two electrodes of T-TIG, and thus, a common conductive channel with stronger brightness and higher stiffness was obtained. Besides, by applied cusp EMF, the electron temperature and electron density of the common conductive channel of T-TIG were increased, and in the radial, the distributions of electron temperature and electron density of T-TIG were more concentrated. Under the condition of welding current of 40 A + 40 A, the electron density on the central axis of T-TIG could be increased by 16% by applied cusp EMF with a 30 A excitation current. In addition, the enhanced common conductive channel characteristics of T-TIG by the cusp EMF caused the arc pressure on the central axis of T-TIG to be increased by 14%, which was beneficial to improve the weld penetration.

During the 1970s, industrialized society seemed to be on the cusp of sweeping change, moving away from the Fordist ‘modern’ era and into an undefined ‘post-modern’ future. To contemporaries in Fran...

Objectives: Evaluating the fracture resistance and failure mode of human maxillary premolars restored with two ceramic onlay materials prepared with two preparation designs. Materials and methods: A total of 40 extracted, human maxillary premolars were selected and divided into two groups according to preparation design; Group A: MOD cavity with anatomical reduction of functional cusp and Group F: MOD cavity with flat reduction of the functional cusp. Each group was divided into two subgroups according to the material of construction; Subgroup S: restored using zirconia-reinforced glass-ceramic and Subgroup E: restored using hybrid ceramic. The finished onlay restorations were luted to prepared teeth using self-adhesive resin cement. Specimens were exposed to thermocycling for 5000 cycles. Fracture resistance was assessed using a Universal testing machine. Failure mode was evaluated using a stereomicroscope. Two-way ANOVA was used to assess the effect of different tested variables and their interaction. Intergroup comparison was done using one-way ANOVA followed by Tukey’s post hoc test. The significance level was set at p≤0.05 within all tests. Results: Two-Way ANOVA showed that ceramic material had no significant effect on the fracture resistance of restored teeth. While the preparation design had a statistically significant effect. The interactions between the independent variables, ceramic materials, and preparation designs had a significant effect on the fracture resistance of teeth. Conclusion: Both preparation designs and materials showed clinically acceptable fracture resistance of onlay restorations. All subgroups showed high fracture resistance and favorable failure modes except VITA SUPRINITY with anatomical reduction of the functional cusp.

No abstract available

Background: The aortic valve neocuspidalization (AVNeo) is an innovative surgical technique aiming at the reconstruction of the aortic valve using autologous pericardium. One of the main criticisms to AVNeo is the longer duration of the aortic clamping time (ACT) as compared to standard aortic valve replacement due to the sizing of the valve neocusps. Methods: We retrospectively enrolled 30 consecutives patients underwent AVNeo. For each patient we developed a 3D aortic root model (ARM) based on CT-scan datasets. We retrospectively compared the leaflets measurements performed during surgery with those obtained on the corresponding ARMs. Results: In 100% of cases no difference between the in vitro and in vivo measurements exceeded the acceptable error limit of 2 ​mm. The correlation of each single in vitro versus in vivo measurements demonstrates a strong coincidence between the two different methods of sizing (r ​> ​0,9, p ​< ​.0001). By analyzing the data considering the annulus perimeter and not the single cusp size, the perfect coincidence was to be found in 89.9% with a slight acceptable discrepancy (2 ​mm on total) in the remaining 10.1%. Conclusions: 3D-ARMs, printed from CT-scan, represent a reproducible process to obtain overlapping cusp sizes compared to those measured in-vivo, possibly reducing the ACT.

OBJECTIVE Standard methods of evaluating tooth long axes are not comparable (digital dental models [DDMs], panoramic and cephalometric radiographs) or expose patients to more radiation (cone-beam computed tomography [CBCT]). This study aimed to compare angular changes in tooth long axes using DDMs vs using CBCTs. SETTINGS AND SAMPLE POPULATION Secondary data analysis of DDMs and CBCTs, taken before and after orthodontic treatment with piezocision of 24 patients. METHODS Angular changes in tooth long axes were evaluated using landmarks on first molars (centre of the occlusal surface and centre of the furcation), canines and incisors (cusp tip and centre of the root at the cementoenamel junction). Wilcoxon test, intraclass correlation coefficient (ICC) and Bland-Altman plots were used to test intra- and inter-rater agreement and compare DDM and CBCT measurements. RESULTS The mesiodistal angulation and buccolingual inclination DDM measurements were reproducible. Overall mean differences between DDM and CBCT measurements of mesiodistal angulation, 1.9°±1.5°, and buccolingual inclination, 2.2 ± 2.2°, were not significant for all teeth. ICC between DDM and CBCT measurements ranged from good (0.85 molars) to excellent (0.94 canines; 0.96 incisors). The percentages of measurements outside the range of ±5 were 17.4% for molars, 13.8% for canines and 4.5% for incisors. CONCLUSIONS DDM assessment of changes in tooth long axes has good reproducibility and yields comparable measurements to those obtained from CBCT within a 5° range. These findings lay the groundwork for machine learning approaches that synthesize crown and root canal information towards planning tooth movement without the need for ionizing radiation scans.

To analyze the stress distribution and subsequent fracture resistance of human maxillary premolars with mesial-occlusal-distal (MOD) defects restored with different minimally invasive restorations. Seventy non-carious human maxillary premolars were selected and divided into seven groups (n = 10). Ten teeth without further preparation served as control. The remaining teeth were endodontically treated and received three restorative patterns: inlays without cusp coverage (I), onlays with palatal coverage (O), overlays with both buccal and palatal coverage (Ov). Lithium disilicate glass ceramics (EM) and machinable composite resin (LU) were used for restoration. Specimens were tested under cycling loading with tongue direction of 45° for 1.2 × 106 cycles at a 50-N load and 2.0-Hz frequency. The survival time and two fracture mode classifications were assessed. Three-dimensional models of each group were designed. The magnitude and pattern of stresses were analyzed under the same condition of the in vitro test using finite element stress analysis. Although the overlay model pattern produced more favorable stress distribution, three restorative patterns restored with the same material had no difference in survival curves (P > 0.05). Only the survival curve of the EM-Ov group had no statistical difference with that of the control group (P > 0.05). EM groups presented mainly interface adhesive failure, while LU groups were mainly material cohesive failure. For the endodontically treated maxillary premolars with MOD defect, the lithium disilicate glass ceramic overlay pattern can reach the best restorative effect. Comparing with restorative pattern, restorative material had a greater influence on the minimally invasive restoration of posterior teeth.

Upon observation of the steep rise in Covid cases patients all over the world, it seems to be clear that along with conventional methods for prevention and cure of this unpredictable disease, something more requires employment. This paper proposes that the concept of ’Yamdanshtra’ (described in Sharangdhar Samhita)1/ ”Ritusandhi”(described in Charak Samhita)2 is a viable solution. A specific ’diet modification pattern’(Padanshik Tyag vidhi) is recommended for better immunity. Detailed graphical studies have been shown about rela- tionship of the number of cases of Covid and the periods of Yamdanshtra or Ritusandhi(cusp between two seasons) in Bharat and three more countries viz. USA,UK and Russia. It was concluded in the study that a positive relation between Covid cases and transition periods can be established. In countries other than Bharat, the rise in Covid cases was present but not significant. It is hypothesized that that may be because the seasons do not show much differ- ence in climatic conditions or in other parameters. For Bharat, the Padanshik Tyag3 method of diet modification during transition periods may work,while other countries may prefer taking a lighter diet during them.

Objectives. The aim of this retrospective study was to determine the position of the impacted maxillary canine (IMC) and then to inspect the frequency, location, and extent of the consequent root resorption (RR) of the adjacent teeth by using CBCT. Materials and Methods. Forty-one patients aged 12-68 who have 56 IMC detected on CBCT images were retrospectively examined in 3D. The canine position was determined by assessing the side of impaction, buccopalatal location, the distance of the canine cusp tip to the midline and to the occlusal plane, and canine angulation to the midline. RR of adjacent teeth was analyzed by investigating the nearest location of ectopic canine to adjacent teeth in horizontal and vertical dimensions in addition to measuring the degree of RR. Results. Twenty-seven (48.2%) impacted canines were on the right side, and 29 (51.8%) were on the left. Most of these teeth 31 (55.4%) were located palatally, while buccal impaction was seen in only 13 (23.2%) canines and 12 (21.4%) were located centrally. The mean distance of the ectopic canine cusp tip to the occlusal plane was significantly higher in males (14.4 mm) than in females (10.7 mm). RR was seen in 9 central incisors (31.03%) and 21 lateral incisors (41.17%) as well as one case in the first and second premolar. This RR was slight for all the adjacent central incisors and premolars. Conclusions. IMC is more frequent in females, palatally and apically. When left untreated, it may cause RR of some of the adjacent teeth with various degrees, however, with no gender preference.

We are on the cusp of having medication that bestows the health benefits of exercise. Is it a good idea? Jo Marchant investigates

Objectives of this study was to evaluate odontometric linear measurements obtained from CBCT software including mesiodistal, tooth length dimensions and enamel thickness of the mandibular canine and mandibular first molar and arch measurements for sexual dimorphism in Egyptian population sample. Material and Methods: The study was carried out on 100 patients who visited the department of oral and maxillofacial radiology, Fayoum University for dental treatments. The study sample were grouped into two groups, group A (50 males) and group B (50 females) aged between 18-25 years old. The teeth which were selected for linear measurements using CBCT in the present study were 100 mandibular permanent canines (Lower 3) and 100 mandibular permanent 1st molar (Lower 6), for each group respectively. The linear measurements were taken on crown width and height, Enamel thickness, arch depth and width. Results: There was a highly significant difference between Male and Female for odontometric measurements of mandibular right and left canines and 1st molars including (CWL3, CLL3, CWL6 and CLL6) while enamel thickness measurements showed non-significant differences between males and females including (ETL3 at cusp tip, ETML6, ETDL6 and ETL6 at mesio-lingual cusp tip). Arch measurements including (ICW, IMW through fossa and IMW through contact) showed high significant differences between males and females. Conclusion: Odontometric parameters including mandibular canine, mandibular first molar crown width and length, inter-canine width and inter-molar width measurements based on CBCT imaging show highly significant gender difference. Thus, the parameters can be simple and reliable sexual dimorphism for medicolegal purpose.

Mice possess two types of teeth that differ in their cusp patterns; incisors have one cusp and molars have multiple cusps. The patterning of these two types of teeth relies on fine-tuning of the reciprocal molecular signaling between dental epithelial and mesenchymal tissues during embryonic development. The AP-2 transcription factors, particularly Tfap2a and Tfap2b, are essential components of such epithelial-mesenchymal signaling interactions that coordinate craniofacial development in mice and other vertebrates, but little is known about their roles in the regulation of tooth development and shape. Here we demonstrate that incisors and molars differ in their temporal and spatial expression of Tfap2a and Tfap2b. At the bud stage, Tfap2a is expressed in both the epithelium and mesenchyme of the incisors and molars, but Tfap2b expression is restricted to the molar mesenchyme, only later appearing in the incisor epithelium. Tissue-specific deletions show that loss of the epithelial domain of Tfap2a and Tfap2b affects the number and spatial arrangement of the incisors, notably resulting in duplicated lower incisors. In contrast, deletion of these two genes in the mesenchymal domain has little effect on tooth development. Collectively these results implicate epithelial expression of Tfap2a and Tfap2b in regulating the extent of the dental lamina associated with patterning the incisors and suggest that these genes contribute to morphological differences between anterior (incisor) and posterior (molar) teeth within the mammalian dentition.

We report a rare case of a 39-year-old male who presented with acute inferior wall myocardial infarction (IWMI). Coronary angiography revealed an anomalous single coronary artery arising from the right coronary cusp. Premature atherosclerotic coronary artery disease (CAD) with critical stenosis in the mid right coronary artery (RCA), proximal posterior left ventricular (PLV) artery, and distal left circumflex (LCX) artery was detected during angiography. The patient managed successfully by percutaneous coronary interventions (PCI) with drug-eluting stents (DESs) by radial approach.

The general solutions of the stress intensity factors (SIFs) for a cusp-type crack problem under remote uniform mechanical and thermal loads are presented in this work. According to the complex variable theory and the method of conformal mapping, a symmetric airfoil crack is mapped onto a unit circle, and both the temperature and stress potentials are used to solve the relevant boundary-value problems. By introducing the auxiliary function and applying the analytical continuation theorem, the SIFs at the cusp-type crack tip can be analytically determined. The obtained SIF results are dependent on the geometric configurations of the cusp-type crack components and the magnitudes of the mechanical and thermal loads. For some combinations of combined loads, the SIF is maximized, and the system has a high risk of damage.

SUMMARY Objectives: To analyze the effect of the porosity caused by incremental and bulk resin composite filling techniques using low- and high-viscosity composite resins on the biomechanical performance of root-treated molars. Methods: Forty intact molars received standardized mesio-occlusal-distal (MOD) cavity preparation, were root treated, and randomly divided into four groups with different filling techniques (n=10). The first involved two incremental filling techniques using VIT/Z350XT, a nanofilled composite resin (Filtek Z350XT, 3M ESPE) associated with a resin-modified glass ionomer cement, and resin-modified glass ionomer cement (RMGIC; Vitremer, 3M ESPE) for filling the pulp chamber. The second involved TPH/VIT, a microhybrid composite resin TPH3 Spectrum associated with Vitremer. The third and fourth involved two bulk-fill composite resins: SDR/TPH, a low-viscosity resin composite (Surefill SDR flow, Dentsply) associated with TPH3 Spectrum, and POST, a high-viscosity bulk-fill resin composite (Filtek Bulk Fill Posterior, 3M ESPE). The volume of the porosity inside the restoration was calculated by micro-CT. The cusp deformation caused by polymerization shrinkage was calculated using the strain-gauge and micro-CT methods. The cusp deformation was also calculated during 100 N occlusal loading and loading to fracture. The fracture resistance and fracture mode were recorded. Data were analyzed by one-way analysis of variance and Tukey test. The fracture mode was analyzed by the χ2 test. The volume of the porosity was correlated with the cusp deformation, fracture resistance, and fracture mode (a=0.05). Results: Incremental filling techniques associated with RMGIC resulted in a significantly higher porosity than that of both bulk-fill techniques. However, no significant difference was found among the groups for the fracture resistance, fracture mode, and cusp deformation, regardless of the measurement time and method used. No correlation was observed between the volume of the porosity and all tested parameters. Conclusions: The porosity of the restorations had no influence on the cuspal deformation, fracture resistance, or fracture mode. The use of the RMGIC for filling the pulp chamber associated with incremental composite resins resulted in similar biomechanical performance to that of the flowable or regular paste bulk-fill composite resin restorations of root-treated molars.

Gemination is a morphologic anomaly of the tooth characterized by the formation of a macrodont. Bilateral presentation is rarely reported in permanent canines. Talon's cusp is an accessory cusp projecting lingually from the cingulum to the incisal edge and may be seen facially sometimes. Simultaneous occurrence of facial and lingual talons on the same tooth is rare. Concurrent occurrence of all the three entities has not been reported. These anomalies can cause unpleasant esthetic appearance due to irregular morphology. The presence of deep grooves on these teeth increases the susceptible to caries and periodontal disease requiring an endodontic intervention. Proper clinical and radiographic examination provides an accurate diagnosis and helps the clinician in the proper treatment planning and avoiding further complications. This article presents a unique case of simultaneous occurrence of bilateral gemination in the permanent maxillary canines with labial and palatal talon's cusps, which has not been reported in the literature till date.

Background A major goal of evolutionary developmental biology is to discover general models and mechanisms that create the phenotypes of organisms. However, universal models of such fundamental growth and form are rare, presumably due to the limited number of physical laws and biological processes that influence growth. One such model is the logarithmic spiral, which has been purported to explain the growth of biological structures such as teeth, claws, horns, and beaks. However, the logarithmic spiral only describes the path of the structure through space, and cannot generate these shapes. Results Here we show a new universal model based on a power law between the radius of the structure and its length, which generates a shape called a ‘power cone’. We describe the underlying ‘power cascade’ model that explains the extreme diversity of tooth shapes in vertebrates, including humans, mammoths, sabre-toothed cats, tyrannosaurs and giant megalodon sharks. This model can be used to predict the age of mammals with ever-growing teeth, including elephants and rodents. We view this as the third general model of tooth development, along with the patterning cascade model for cusp number and spacing, and the inhibitory cascade model that predicts relative tooth size. Beyond the dentition, this new model also describes the growth of claws, horns, antlers and beaks of vertebrates, as well as the fangs and shells of invertebrates, and thorns and prickles of plants. Conclusions The power cone is generated when the radial power growth rate is unequal to the length power growth rate. The power cascade model operates independently of the logarithmic spiral and is present throughout diverse biological systems. The power cascade provides a mechanistic basis for the generation of these pointed structures across the tree of life.

BioTechniques’ Senior Editor, Abigail Sawyer, explores current research on the human gut–brain axis and whether scientists are on the cusp of a breakthrough treatment for depression.

For decades, technology advocates have claimed that we are on the cusp of a complete transformation in education. But, as Justin Reich explains, such transformations have not yet come to pass. Even during the COVID-19 pandemic, teachers did not use technology to significantly alter their teaching. Instead, technology enabled them to maintain many of their classroom routines (using learning management systems or video conferencing) or supplement their usual instruction (using gamified apps). Teachers did, however, tinker with their methods throughout the pandemic, gradually improving over time. Reich suggests that this tinkering framework is a more realistic way to think about ed tech’s potential to support teaching and learning.

Background and aims Complications of bicuspid aortic valve commonly include aortic stenosis, aortic regurgitation, and ascending aortic dilation. The progression of these lesions is not well described. Materials and methods We reviewed 249 bicuspid aortic valve patients with at least two echocardiograms from 2006 to 2016. Valve morphology (right-left or right-noncoronary cusp fusion) was confirmed by visual inspection, and aortic stenosis and regurgitation were quantified according to current guidelines; the ascending aorta was measured at end-systole 2-3 cm above the sinotubular junction. Annualized progression of stenosis, regurgitation, and aortic dilation from first to most recent echocardiogram were compared between right-left and right-nonfused valves using multivariable logistic regression to adjust for baseline differences in groups. Results Among 249 bicuspid aortic valve patients (mean age 47.6 ± 13.5 years, 66.3% male), 75.9% had right-left cusp fusion. At baseline, aortic stenosis was absent or mild in 80.3%; aortic regurgitation was absent or mild in 80.7%; and aortic diameters were 35.0 ± 5.7 mm (sinuses of Valsalva) and 37.4 ± 6.2 mm (ascending). Mean annualized decrease in aortic valve area was 0.07 cm2 /year, with 30% of bicuspid aortic valve patients progressing ≥0.1 cm2 /year. Aortic regurgitation progressed ≥1 grade in 37 patients. Mean annualized increase in ascending aorta diameter was 0.36 mm/year in right-left and 0.65 mm/year in right-nonbicuspid valves. Conclusions In this serial echocardiographic study of bicuspid aortic valve patients, cusp orientation was not associated with progression of valve dysfunction. Right-noncoronary cusp fusion was associated with ascending aortic diameter progression.

Valve-sparing root replacement using reimplantation techniques is increasingly applied to bicuspid aortopathy. Long-term durability of cusp repair is unclear. We analyze midterm results using a conservative approach to cusp repair.From 2006 to 2018, 327 patients underwent valve-sparing reimplantation, 66 with bicuspid valves. Leaflets were analyzed after reimplantation. A majority (51/66) required no cusp repair. Fifteen patients had cusp repair limited to closure of unfused raphe or central plication. Patients were followed by echocardiography.Mean age of patients was 44.7 ± 12.3 years. The cusp repair group had a higher incidence of preoperative moderate (10% vs 40%) or severe (4% vs 33.3%) aortic insufficiency (P .001). There was no operative mortality or major complication. Mean follow-up was 51.6 ± 40.8 months. On postoperative echocardiography, incidence of none, trace, or mild aortic insufficiency was 41.3% (19/46), 43.5% (20/46), and 15.2% (7/46) in the no cusp repair group and 40% (6/15), 40% (6/15), and 20% (3/15) in the cusp repair group, respectively (P = .907). Few patients progressed in degree of aortic insufficiency. No patients required reoperation. At 5 years, freedom from any aortic insufficiency was 46.9% versus 15.8% (P = .013), and freedom from greater than trace aortic insufficiency was 59.1% versus 36.9% (P = .002) due to the higher rate of postoperative trace and mild aortic insufficiency with cusp repair. There was no difference in freedom from greater than mild aortic insufficiency (92.1% vs 100%; P = .33).Valve-sparing root replacement is reliably performed with bicuspid aortic valves whether or not cusp reconstruction is necessary. Few patients progress to greater than mild aortic insufficiency. Need for reoperation is rare in midterm follow-up.

Ghost cell odontogenic carcinoma (GCOC) is a rare malignant neoplasm characterized by the presence of ghostcells. It is considered to originate from either a calcifying odontogenic cyst (COC) or a dentinogenic ghost cell tumor(DGCT). Its clinical and radiographic characteristics are non-specific, including slow growth, locally aggressivebehavior, and eventual metastasis. This case report describes a 43-year-old Thai man with plain radiographs and cone-beam computed tomographic images revealing a unilocular radiolucency with non-corticated borders surrounding an impacted left canine associated with radiopaque foci around the cusp tip. Based on the microscopic findings, the lesion was diagnosed as GCOC. Partial maxillectomy of the right maxilla was performed, and radiotherapy was administered. An obturator was made to support masticatory functions Three years later, the lesion showed complete boneremodeling and no signs of recurrence, and long-term follow-up was done regularly.

This study investigates enamel growth of a modern-day human upper first incisor (S197) possessing an accessory cusp. Growth rates collected from the accessory enamel are compared to data collected from the primary cusp and healthy incisors from the same population. Upper first incisors (n=12) and S197 were analysed using histological methods. Daily secretion rates (DSRs) were calculated for inner, mid, and outer regions of cuspal and lateral sites. Additional DSRs were calculated for equivalent regions of S197’s accessory cusp. S197’s primary cusp DSRs were significantly faster than the accessory cusp for all lateral regions, but significantly slower in the inner and mid cuspal regions. S197’s primary cusp DSRs were also significantly faster than the healthy incisor sample for all lateral regions, but significantly slower in the inner and mid cuspal regions. The DSRs of the healthy sample were significantly faster than those of S197’s accessory cusp for all lateral regions, but significantly slower in the inner cuspal region. This case study displays that human teeth possessing accessory cusps can present varying DSRs to healthy teeth of the same population, and that accessory enamel growth may not follow the same pattern of increasing DSRs along the length of enamel prisms.

At the end of 2013, China introduced what it calls the ‘One Belt, One Road Initiative’ (BRI) (yidaiyiluchangyi 一带一路战倡议). From a Chinese perspective, this initiative is nothing less than a strategy ...