Bilateral Calcifying Odontogenic Cyst: A Rare Entity

The calcifying odontogenic cyst (COC) accounts for 1 % of jaw cysts, found most commonly as central lesion. The COC usually manifests itself as a painless, slow growing swelling, anterior to the first molar region. Radiographically it appears as a well-defined, unilocular radiolucency, and may have a radiopaque mass in its center. Majority of the cases appear before the fourth decade of life. The COC is found rarely in patients in the first decade of life. Histopathological features include a cystic lining demonstrating characteristic "Ghost" epithelial cells with a propensity to calcify. Here we report the unusual occurrence of a case of 8 year child diagnosed with bilateral COC on right and left side of mandible.

Mandibular reconstruction using AO/ASIF stainless steel reconstruction plate: a retrospective study of 36 cases

AIM

The study was aimed at esthetic and functional results as well as patient tolerance after reconstruction with reconstruction plate. The follow-up ranged from 1 to 4 years.

MATERIALS AND METHODS

A retrospective study of 36 patients who had mandibular reconstruction with AO/ASIF stainless steel reconstruction plates after oncologic resection was evaluated. The indications and postoperative outcomes were studied.

RESULTS

At the end of study, 24 of 36 patients (67%) still had the plate in place. Around three (8%) plates were fractured. Nine (25%) plates got exposed leading to surgical intervention. Surgical results were satisfying, particularly when looking at delayed healing or long-term tolerance. Esthetic (79% rated results as good or acceptable) and functional results of this reconstruction were satisfying.

CONCLUSION

We conclude by saying that reconstruction plate provides a solution for safe and rapid mandibular reconstruction for patients with poor prognosis or poor condition. This method also preserves the possibility of secondary reconstruction.

CLINICAL SIGNIFICANCE

The reconstruction plate may be a good clinical choice for safe and rapid mandibular reconstruction.

Multiple Pathology in a Single Lesion: AOT Associated with Dentigerous Cyst

Odontogenic cysts and tumors are quite common occurrences in jaw bones, although both of them occurring together are rare. The epithelial lining of odontogenic cyst has a potential to transform into neoplastic conditions like squamous cell carcinoma and mucoepidermoid carcinoma, and odontogenic tumors like ameloblastoma and adenomatoid odontogenic tumor. However, the frequency of such cases being encountered is very less. Here, we report a case of adenomatoid odontogenic tumor (AOT) associated with a dentigerous cyst around the crown of an unerupted lateral incisor (follicular variant), in a 14-year-old boy. We also attempt to unravel its mechanism of cytodifferentiation and tumor progression. The origin and nature of such kind of lesions (i.e., independent development of multiple pathologies as a single lesion in a single location, single pathology giving rise to another pathology or a distinct entity/new variant) cannot be explained with certainty at this point of time. The molecular mechanism of tumor development needs to be further elucidated in order to conclude that a different entity called 'hybrid' AOT exists.

Traumatic herniation of buccal fat pad in 1 year old child: case report and review of literature

Traumatic herniation of buccal fat pad (BFP) is very rare, usually seen in infants and young children ranging from 5 months to 12 years of age. Etiology will be blunt injury to buccal mucosa from foreign objects or trauma due to teeth and fall. The suckling activity in infants may also encourage the herniation following trauma. A minor injury or perforation to the buccal mucosa can cause herniation of BFP. The size of herniated mass is very large when compared to the size of the perforation. The history of trauma, absence of prolapse before the injury, its occurrence in infants and young children, specific anatomic sites and location of perforation in mucosa, histopathological appearance of adipose tissue are the characteristic features important for diagnosing the condition. The treatment options for the herniated BFP are usually excision. Alternative to excision is repositioning of the herniated fat in its anatomical location if noticed early.

Dengue risk zone mapping of Thiruvananthapuram district, India: a comparison of the AHP and F-AHP methods

Dengue fever, which is spread by Aedes mosquitoes, has claimed many lives in Kerala, with the Thiruvananthapuram district bearing the brunt of the toll. This study aims to demarcate the dengue risk zones in Thiruvananthapuram district using the analytical hierarchy process (AHP) and the fuzzy-AHP (F-AHP) methods. For the risk modelling, geo-environmental factors (normalized difference vegetation index, land surface temperature, topographic wetness index, land use/land cover types, elevation, normalized difference built-up index) and demographic factors (household density, population density) have been utilized. The ArcGIS 10.8 and ERDAS Imagine 8.4 software tools have been used to derive the risk zone maps. The area of the risk maps is classified into five zones. The dengue risk zone maps were validated using dengue case data collected from the Integrated Disease Surveillance Programme portal. From the receiver operating characteristic (ROC) curve analysis and the area under the ROC curve (AUC) values, it is proved that the F-AHP method (AUC value of 0.971) has comparatively more prediction capability than the AHP method (AUC value of 0.954) in demarcating the dengue risk zones. Also, based on the comparison of the risk zone map with actual case data, it was confirmed that around 82.87% of the dengue cases occurred in the very high and high-risk zones, thus proving the efficacy of the model. According to the dengue risk map prepared using the F-AHP model, 9.09% of the area of Thiruvananthapuram district is categorized as very high risk. The prepared dengue risk maps will be helpful for decision-makers, staff with the health, and disaster management departments in adopting effective measures to prevent the risks of dengue spread and thereby minimize loss of life.

Challenges with relativistic GW calculations in solids and molecules

For molecules and solids containing heavy elements, accurate electronic-structure calculations require accounting not only for electronic correlations but also for relativistic effects. In molecules, relativity can lead to severe changes in the ground-state description. In solids, the interplay between both correlation and relativity can change the stability of phases or it can lead to an emergence of completely new phases. Traditionally, the simplest illustration of relativistic effects can be done either by including pseudopotentials in non-relativistic calculations or alternatively by employing large all-electron basis sets in relativistic methods. By analyzing different electronic properties (band structure, equilibrium lattice constant and bulk modulus) in semiconductors and insulators, we show that capturing the interplay of relativity and electron correlation can be rather challenging in Green's function methods. For molecular problems with heavy elements, we also observe that similar problems persist. We trace these challenges to three major problems: deficiencies in pseudopotential treatment as applied to Green's function methods, the scarcity of accurate and compact all-electron basis sets that can be converged with respect to the basis-set size, and linear dependencies arising in all-electron basis sets, particularly when employing Gaussian orbitals. Our analysis provides detailed insight into these problems and opens a discussion about potential approaches to mitigate them.

Relativistic Fully Self-Consistent GW for Molecules: Total Energies and Ionization Potentials

The fully self-consistent GW (scGW) method with an iterative solution of the Dyson equation provides a consistent approach for describing the ground and excited states without any dependence on the mean-field reference. In this work, we present a relativistic version of scGW for molecules containing heavy elements using the exact two-component (X2C) Coulomb approximation. We benchmark SOC-81 data set containing closed shell heavy elements for the first ionization potential using the fully self-consistent GW as well as one-shot GW. The self-consistent GW provides superior results compared to G0W0 with PBE reference and comparable results to G0W0 with PBE0 while also removing the starting point dependence. The photoelectron spectra obtained at the X2C level demonstrate very good agreement with the experimental spectra. We also observe that scGW provides very good estimation of ionization potential for the inner d-shell orbitals. Additionally, using the well-conserved total energy, we investigate the equilibrium bond length and harmonic frequencies of a few halogen dimers using scGW. Overall, our findings demonstrate the applicability of the fully self-consistent GW method for accurate ionization potential, photoelectron spectra, and total energies in finite systems with heavy elements with a reasonable computational scaling.

Thermofield Theory for Finite-Temperature Electronic Structure

Wave function methods have offered a robust, systematically improvable means to study ground-state properties in quantum many-body systems. Theories like coupled cluster and their derivatives provide highly accurate approximations to the energy landscape at a reasonable computational cost. Analogues of such methods to study thermal properties, though highly desirable, have been lacking because evaluating thermal properties involve a trace over the entire Hilbert space, which is a formidable task. Besides, excited-state theories are generally not as well studied as ground-state ones. In this mini-review, we present an overview of a finite-temperature wave function formalism based on thermofield dynamics to overcome these difficulties. Thermofield dynamics allows us to map the equilibrium thermal density matrix to a pure state, i.e., a single wave function, albeit in an expanded Hilbert space. Ensemble averages become expectation values over this so-called thermal state. Around this thermal state, we have developed a procedure to generalize ground-state wave function theories to finite temperatures. As explicit examples, we highlight formulations of mean-field, configuration interaction, and coupled cluster theories for thermal properties of Fermions in the grand-canonical ensemble. To assess the quality of these approximations, we also show benchmark studies for the one-dimensional Hubbard model, while comparing against exact results. We will see that the thermal methods perform similarly to their ground-state counterparts, while merely adding a prefactor to the asymptotic computational cost. They also inherit all the properties, good or bad, from the ground-state methods, signifying the robustness of our formalism and the scope for future development.

Comparing Self-Consistent GW and Vertex-Corrected G0W0 (G0W0Γ) Accuracy for Molecular Ionization Potentials

We test the performance of self-consistent GW and several representative implementations of vertex-corrected G0W0 (G0W0Γ). These approaches are tested on benchmark data sets covering full valence spectra (first ionization potentials and some inner valence shell excitations). For small molecules, when comparing against state-of-the-art wave function techniques, our results show that full self-consistency in the GW scheme either systematically outperforms vertex-corrected G0W0 or gives results of at least comparative quality. Moreover, G0W0Γ results in additional computational cost when compared to G0W0 or self-consistent GW. The dependency of G0W0Γ on the starting mean-field solution is frequently more dominant than the magnitude of the vertex correction itself. Consequently, for molecular systems, self-consistent GW performed on the imaginary axis (and then followed by modern analytical continuation techniques) offers a more reliable approach to make predictions of ionization potentials.