Chamber Floor Research Articles

A case of infected root canal treatment of a mandibular first molar with a perforated floor of the pulp chamber, and a middle mesial canal

A case of infected root canal treatment of a mandibular first molar with a perforated floor of the pulp chamber, and a middle mesial canal

Management of Bilateral Maxillary Second Molars with Extra Palatal Root: A Case Report

A crucial understanding of teeth’ internal and external anatomy is critical for the successful outcome of endodontic therapy. The presence of two palatal roots in maxillary molars, particularly in the second molar is rare. The present case report addresses this anatomical variation in an 18-year-old female patient with a chief complaint of severe pain in the upper left back teeth region since one week. Preoperative radiographic evaluation of maxillary second molar did not reveal the aberrant anatomy due to its location and impaction of maxillary third molar onto the roots of the second molar. After access opening, inspection of the pulp chamber floor revealed a slightly deviated location of the palatal canal and a bleeding point mesial to the palatal canal. Intensive exploration for determining any additional canals was done using David Green (DG) 16 endodontic explorer under 3X magnification using dental loupes. A narrow field of view Cone Beam Computed Tomography (CBCT) was obtained to evaluate the unusual root canal morphology. Following a thorough analysis of CBCT, root canal treatment was performed employing a standard protocol. This case report highlights the successful diagnosis and management of the bilateral maxillary second molar with two separate palatal roots. With CBCT and magnification, determining the root morphology and canal configuration will be more accurate, further improving the quality of root canal treatment.

Topography of Primary Molar Pulp Chamber Floor: A Scanning Electron Microscopy and Micro-Computed Tomography Analysis

Objective: To determine in vitro the frequency, shape, type, diameter, and patency of accessory canals in the primary molars pulp chamber floor . Material and Methods: Sixteen healthy primary molars were evaluated by micro-computed tomography and scanning electron microscopy. Descriptive analyses of the frequency, shape (round, oval, or irregular), type (blind, true, or hidden), patency and diameter of the accessory canals were performed. Results: Half of the teeth presented accessory canals, 62.5% of which were located in the upper molars and 37.5% in the lower molars. The most frequent shape was irregular. In three-dimensional analysis, blind accessory canals (12.5%) and with patency (18.7%) of the teeth were observed. The average accessory canal diameter was 51.97 µm (± 26.03 µm) . Conclusion: Upper molars showed a higher frequency of accessory canals with larger diameters. The irregular shape was the most frequent. 18.7% of accessory channels showed patency.

Significance of the Coronal Pulp Chamber Floor Anatomy in the Human Dentition: A Narrative Review

In root canal treatment, the foundation on which all surgical procedures are performed is a thorough knowledge of the anatomy of the pulp chamber and the root canal system. The endodontic triad comprises biomechanical preparation, microbial control and complete obturation of the root canal space. Knowledge of the pulp chamber floor anatomy is important in locating the numbers and orifices of root canals present within the tooth being root canal treated. This is particularly important while treating teeth that are heavily restored, mal-positioned, or calcified. The current review attempts to explain the complex anatomy of the pulp chamber floor and its significance in root canal treatment.CPD/Clinical Relevance: To allow the location of all root canal orifices in the pulp chamber and to perform successful root canal treatment, knowledge of pulp chamber floor anatomy is essential. The clinician should consider that, as the external morphology of the tooth varies in individuals, so does the internal morphology.

Dentin Thickness of Pulp Chamber Floor in Primary Molars: Evaluation by Cone-Beam Computed Tomography

Objective: Use cone-beam computed tomography (CBCT) images to evaluate the dentin thickness of the pulp chamber floor in primary molars . Material and Methods: Cross-sectional study, conducted with CBCT images of teeth of children. Primary molars with preserved pulp chamber floor were included. The dentin thickness of the pulp chamber floor in the primary molars was measured linearly in CBCT cross-sections. Data were descriptively analyzed and the Mann-Whitney test was applied (p<0.05). Results: 27 CBCT exams and 123 primary molars of children aged 4 to 13 years were analyzed; the majority was female (52.0%). In maxillary molars, the median dentin thickness was 1.50 (0.6–2.2) mm in the first and 1.65 (0.6–2.3) mm in the second (p=0.049) molars. In mandibular molars, the median was 1.20 (0.3–1.7) mm in the first and 1.60 (1.0–2.2) mm in the second (p<0.001) molars. Children aged 4 to 8 years showed less dentin thickness (p<0.001) . Conclusion: The median dentin thickness of the pulp chamber floor in primary molars was 1.50 mm, ranging from 0.3 to 2.3 mm. Less dentin thickness was associated with younger children, teeth in the mandibular arch, and first molars.

Fiery rituals among the Alanian population of the Saltov culture of the Seversky Donets Basin (based on materials from catacomb cemeteries)

One of the typical features of the funeral rite of the Alanian population of the Saltov culture is the sprinkling of the burial chamber floor with a layer of charcoal. Paired (male + female) burials on coal bedding S. A. Pletneva considered as burials of couples in which coal was a symbol of “posthumous marriage”. The presence of coal bedding in solitary burials in the catacombs Nos. 6, 9, 11, 13, 17 of Rubizhan and the catacombs Nos. 1, 10 of the Staro-Saltov burial grounds allows us to offer a different interpretation of this feature of the Alanian funeral rite. At these cemeteries, the dominant type of burial structure was the catacombs with a longitudinal chamber in relation to the dromos, which were used by the Sarmatian-Alans often for one-time rather than family burials. Thus, taking into account ethnographic materials on Ossetians, it can be suggested that the initial sprinkling of charcoal on the floor of the burial chamber was associated with the rite of endowing the dead person with a “part of the family fire”, which was to ensure the unity of the dead people with their living relatives. In this context, the sprinkling of charcoal from the family hearth on the floor of the burial chamber should be considered as a desire to provide the deceased with the necessary heat and light, and thus turn the grave into a full-fledged otherworldly home, which, if necessary, could accept new deceased relatives. This assumption is confirmed by paired and collective burials at the Upper-Saltov burial ground, in which coal bedding was made only under one of the people buried in the chamber. At the same time, bodies of people were laid on the coal bedding, regardless of their gender (male, female) and age (children, adults). The use of charcoal to dry the chamber floor in adverse weather conditions before placing the bodies of a deceased person cannot be excluded.

External apical root resorption after molar space closure with miniscrew as anchorage: a tomographic evaluation

Objective: The purpose of this retrospective study was to evaluate and quantify external apical root resorption (EARR) in molars after masialization into atrophic alveolar ridge area. Materials and Methods: The sample consisted of 11 patients, five women and six men, and a total of 16 molars, both superior and inferior (seven in the maxilla and nine in the mandible). The age range was 19 to 55 years at the beginning of treatment (initial mean age of 36 years and 5 months), with an average treatment time of 23 months. Tooth movement was performed with mini-implant anchorage using NiTi springs, using a mean force of 300 grams. The sample was evaluated using cone-beam CT scans (CBCT) in two periods, at the beginning of the treatment (T1) and after 4 mm of movement (T2). Root resorption was measured by the difference in root lengths (T2-T1). Using the distance from the floor of the pulp chamber to the root apex as a reference. Root length was measured using specific software (OnDemand3Ddental) and was analyzed using the paired t-test, adopting a significance level of 5%. Results: There was statistically significant resorption only in the mesial and distal roots, with a mean reduction of 0.69 mm in the mesial root (-6.2%) and 0.83 mm in the distal root (-7.4%). Conclusion: Space closure after dental movement in an atrophic alveolar ridge was identified as a risk factor for ARR. However, the amount of ARR could be considered clinically irrelevant.

Maxillary lateral incisor with four root canals: A rare case report

The objective of the present study is to present a case report of endodontic treatment of a maxillary lateral incisor with 1 root and 4 root canals. The success of endodontic treatment requires knowledge of dental anatomy and its variations. The maxillary lateral incisor usually presents with one root canal system within one root. The incidence of 4 root canals in this tooth is rare. However, it must be taken into consideration, the clinical and radiographic evaluations during the endodontic treatment in order to enhance the diagnostic. The detection of all canals was achieved by examination of the pulp chamber floor with the help of the dental loupes as well as careful examination of intraoral radiographs.

Influence of access cavity design on fracture strength of endodontically treated lower molars.

To assess whether access cavity design influences the fracture strength of endodontically treated and restored molars. Fifty human lower molars with standard crown dimensions were selected and assigned to the following groups: S - positive control (healthy tooth), ET - negative control (conventional endodontic access (CEA) and no restoration), NI - negative control (minimally invasive endodontic access (MEA) and no restoration), ETR (CEA+restoration with Bulkfill flow) and NIR (MEA+restoration with Bulkfill flow). The specimens were subjected to a compression test. The teeth were inspected for the site of fracture: either pulp floor or cusp. ANOVA, followed by Tukey's multiple comparison test (α=5%), was used for statistical analysis. The type of access cavity preparation did not increase the fracture strength of endodontically treated teeth. Even with the restoration, all teeth with endodontic access performed had a higher incidence of fractures at the pulp chamber floor level.

Characteristics of Plane Gate Vibration and Holding Force in Closing Process by Experiments

A 1:25 scale physical model test was employed to study the plane gate vibration and holding force under the conditions of the fixed gate opening and closing process, respectively. We paid more attention to the characteristics of the gate vibration, holding force and the failure of gate-closing in closing process. The correlation between gate vibration and holding force was further examined. The results show that vertical vibration is weaker than the lateral and horizontal vibrations in fixed gate opening and is stronger than the lateral and vertical vibrations in closing process. Gate vertical vibration is self-excited vibration with a frequency of 7–14 Hz. Besides, crawl vibration in closing process is related to the upstream water depth. The higher the water level is, the earlier the crawl vibration appears. After the crawl stage, plane gate stops motion at a certain distance from the chamber floor and then the failure of gate-closing happens. Finally, gate vibration in three directions is significantly correlated with the holding force. In closing process, holding force has positive correlation with the vertical vibration and has negative correlation with the lateral and horizontal vibrations. In the crawl stage, the average of correlation coefficient in lateral, vertical and horizontal direction is −0.723, 0.733 and −0.664, respectively. Thus, the influence of gate vibration on holding force should be taken into consideration in determining the hoists capacity.

Insights Into Magma Chamber Processes From the Relationship Between Fabric and Grain Shape in Troctolitic Cumulates

The strength of foliations defined by shape preferred orientation of plagioclase in troctolitic cumulates from the Layered Series of the Skaergaard intrusion, and the Rum Eastern Layered Intrusion, increases as the grains become more tabular, due either to the greater propensity of highly non-equant grains to be re-arranged by magmatic currents or tectonic disruption of poorly consolidated mush, or by the effects of a pre-existing shape preferred orientation on final grain shape in fully solidified rocks. The stratigraphic evolution of grain shape, microstructures and fabrics in the lowest 320 m of the Skaergaard Layered Series records the progressive inflation of the chamber to its final size. During the earliest stages of solidification, the extent of in situ nucleation and growth on the chamber floor decreased upward through the stratigraphy, due to the development of a thermally insulating blanket of mush on the floor. An upward increase in foliation strength as the chamber inflated to its final size was a result of the increasing strength of convection of the bulk magma and an increasing contribution to the floor mush of crystals derived from the walls of the enlarging magma chamber. Plagioclase in the troctolites in the open-system magma chamber of the Rum Eastern Layered Intrusion is generally more equant than that in the Skaergaard intrusion, perhaps related to the slower crystal growth on the margins of the continuously replenished Rum chamber. Significant sub-solidus modification of original igneous microstructures is observed in Rum troctolites from parts of the stratigraphy recording frequent replenishment events.

Endodontic Management of Permanent Mandibular First Premolar with Type V Canal Configuration: Case Report

Effective endodontic treatment relies on a strong understanding of root canal anatomy, specific evaluation of the pulp chamber floor, critical interpretation of radiograph, and chemo-mechanical planning accompanied by three-dimensional obturation of root canal system. The risk of extra root /canal should be considered even in teeth with a small incidence of irregular root canal morphology. Mandibular premolars have acquired the distinction for having aberrant anatomy. This article reports and discusses the successful endodontic management of mandibular first premolar with one canal bifurcating into two canals.

Fossilized solidification fronts in the Bushveld Complex argue for liquid-dominated magmatic systems

Chemical differentiation of magma on Earth occurs through physical separation of liquids and crystals. The mechanisms of this separation still remain elusive due to the lack of information on solidification fronts in plutonic magmatic systems. Here, we present records of fossilized solidification fronts from massive magnetitites of the Bushveld Complex in South Africa, obtained by two-dimensional geochemical mapping on field outcrops. The chemical zoning patterns of solidification fronts indicate that nucleation and crystallization occur directly at the chamber floor and result in near-perfect fractionation due to convective removal of a compositional boundary layer from in situ growing crystals. Our data precludes the existence of thick crystal mushes during the formation of massive magnetitites, thus providing no support for the recent paradigm that envisages only crystal-rich and liquid-poor mushy reservoirs in the Earth’s crust.

Inhibition of Catechol-O-methyltransferase Does Not Alter Effort-Related Choice Behavior in a Fixed Ratio/Concurrent Chow Task in Male Mice.

Effort-related choice (ERC) tasks allow animals to choose between high-value reinforcers that require high effort to obtain and low-value/low-effort reinforcers. Dopaminergic neuromodulation regulates ERC behavior. The enzyme catechol-O-methyltransferase (COMT) metabolizes synaptically-released dopamine. COMT is the predominant regulator of dopamine turnover in regions of the brain with low levels of dopamine transporters (DATs), including the prefrontal cortex (PFC). Here, we evaluated the effects of the COMT inhibitor tolcapone on ERC performance in a touchscreen-based fixed-ratio/concurrent chow task in male mice. In this task, mice were given the choice between engaging in a fixed number of instrumental responses to acquire a strawberry milk reward and consuming standard lab chow concurrently available on the chamber floor. We found no significant effects of tolcapone treatment on either strawberry milk earned or chow consumed compared to vehicle treatment. In contrast, we found that haloperidol decreased instrumental responding for strawberry milk and increased chow consumption as seen in previously published studies. These data suggest that COMT inhibition does not significantly affect effort-related decision making in a fixed-ratio/concurrent chow task in male mice.

The MB3 canal in maxillary molars: a micro-CT study.

To assess the internal and external morphologies of the mesiobuccal (MB) root of maxillary molars presenting a third root canal (MB3), using micro-computed tomography (micro-CT). Two-hundred and sixty-five extracted maxillary first and second molars with different root configurations were imaged in a micro-CT scanner at 19.6-μm pixel size. Sixteen teeth presenting MB3 canal were selected and evaluated regarding root configuration, minimal dentine thickness 2mm under the furcation area, canal configuration of the MB root, MB3 canal morphology (location, independent or confluent orifice, and anatomy types), and the apical anatomy (aspect ratio, number of accessory canals and foramina, presence of isthmus, and independent MB3 foramen). Overall, a high variability in canal configuration was detected in the MB root. MB3 canal was observed in 10 maxillary first molars and 6 maxillary second molars (n = 16). Minimal dentine thickness related to the MB3 canal at the coronal third was smaller than that of the MB1 canal. A complex internal anatomy comprising 13 different root canal configurations was observed. A high number of independent MB3 orifices at the pulp chamber floor was observed in the first molars (7 out of 10 teeth), while most of the specimens (n = 14) showed a confluent anatomy of the MB3 canal. A varied number of accessory canals and foramina were observed. At the apical third, isthmus could be observed in 6 specimens, while an independent MB3 foramen was present in 37.5% of the MB roots. MB3 canal is a rare anatomical variation present in maxillary first and second molars. Its presence can be associated to a complex internal anatomy of the MB root which includes the presence of isthmuses and multiple accessory canals and foramina at the apical third, but also a thin dentine thickness at the coronal third and a confluent anatomy of the MB3 with the other main canals.

Three-dimensional thermal calculations of the radiation chamber of a cylindrical heating tube furnace

The paper briefly describes the method of thermal calculations of radiation chambers of tube furnaces on the basis of modelling interconnected processes taking place in the furnace by three-dimensional differential energy equations, the transfer of momentum components, mass concentrations of methane and air, continuity, a two-parameter model of turbulence and the equation of energy transfer by radiation. A software package using this method is applied to carry out numerical analysis of the spatial temperature distribution, the averaged values of velocities of the combustion products turbulent flow in the combustion chamber of a cylindrical heating tube furnace of the oil-processing industry. A furnace diagram with diffusion burners on the radiation chamber floor and differential equations describing physical processes taking place in the furnace are given. Methods for solution of the initial equations are described. The obtained distributions of the surface densities of heat fluxes to the coils along the chamber perimeter at different heights of the furnace are demonstrated. Graphs of the temperature change of the combustion products and the tubular reactor walls for different values of the angular coordinate are given.

The functional nasal anatomy of the pike, Esox lucius L.

Olfactory flow in fishes is a little-explored area of fundamental and applied importance. We investigated olfactory flow in the pike, Esox lucius, because it has an apparently simple and rigid nasal region. We characterised olfactory flow by dye visualisation and computational fluid dynamics, using models derived from X-ray micro-computed tomography scans of two preserved specimens. An external current induced a flow of water through the nasal chamber at physiologically relevant Reynolds numbers (200−300). We attribute this externally-induced flow to: the location of the incurrent nostril in a region of high static pressure; the nasal bridge deflecting external flow into the nasal chamber; an excurrent nostril normal to external flow; and viscous entrainment. A vortex in the incurrent nostril may be instrumental in viscous entrainment. Flow was dispersed over the olfactory sensory surface when it impacted on the floor of the nasal chamber. Dispersal may be assisted by: the radial array of nasal folds; a complementary interaction between a posterior nasal fold and the ventral surface of the nasal bridge; and the incurrent vortex. The boundary layer could delay considerably (up to ~ 3 s) odorant transport from the external environment to the nasal region. The drag incurred by olfactory flow was almost the same as the drag incurred by models in which the nasal region had been replaced by a smooth surface. The boundary layer does not detach from the nasal region. We conclude that the nasal bridge and the incurrent vortex are pivotal to olfaction in the pike.

Observation of the Pulp Chamber of Maxillary First Premolars: A Micro-computed Tomographic Study.

There are a few studies about the evaluation of maxillary first premolars internal structure with micro-computed tomography (micro-CT). The aim of this study was to assess morphological features of the pulp chamber in maxillary first premolar teeth using micro- CT. Extracted 15 maxillary first premolar teeth were selected from the patients who were in different age groups. The distance between the pulp orifices, the diameter of the pulp and the width of the pulp chamber floor were measured on the micro-CT images with the slice thickness of 13.6 µm. The number of root canal orifices and the presence of isthmus were evaluated. The mean diameter of orifices was 0.73 mm on the buccal side while it was 0.61 mm on palatinal side. The mean distance between pulp orifices was 2.84 mm. The mean angle between pulp orifices was -21.53°. The mean height of pulp orifices on the buccal side was 4.32 mm while the mean height of pulp orifices on the palatinal side was 3.56 mm. The most observed shape of root canal orifices was flattened ribbon. No isthmus was found in specimens. Minor anatomical structures can be evaluated in more detail with micro-CT. The observation of the pulp cavity was analyzed using micro-CT.

Monomineralic anorthosites in layered intrusions are indicators of the magma chamber replenishment by plagioclase-only-saturated melts

The formation of some Earth’s monomineralic igneous rocks appears to be prohibited by constraints imposed by liquidus phase-equilibria on evolution of mantle-derived magmas. Yet, these rocks exist as stratiform layers in many mafic-ultramafic intrusions. One conspicuous example is monomineralic anorthosites in the Bushveld Complex that occur as stratiform layers up to hundreds of kilometres in length. Such monomineralic anorthosites appear to require parental melts saturated in plagioclase only but where and how to produce these melts remains a contentious issue. Here we argue that they are likely sourced from deep-seated magma reservoirs. In response to pressure reduction, these ascending melts become first superheated and then saturated in plagioclase after stalling and cooling in shallow-level chambers. Adcumulus growth of plagioclase from such melts at the chamber floor results in the formation of monomineralic anorthosites. We propose that stratiform layers of monomineralic anorthosites in layered intrusions are products of the chamber replenishment by melts whose saturation in plagioclase as a single liquidus phase is triggered by their transcrustal ascent towards the Earth’s surface.

Controlling the Spatiotemporal Transport of Particles in Fluid-Filled Microchambers.

The development of microscale devices that autonomously perform multistep processes is vital to advancing the use of microfluidics in industrial applications. Such advances can potentially be achieved through the use of "chemical pumps" that transduce the energy from inherent catalytic reactions into fluid flow within microchambers, without the need for extraneous external equipment. Using computational modeling, we focus on arrangements of multiple chemical pumps that are formed by anchoring patches of different enzymes onto the floor of a fluid-filled chamber. With the addition of the appropriate reactants, only one of the enzymatic patches is activated and thereby generates fluid flow centered about that patch. These flows drive the self-assembly of microparticles in the solution and localize the particles onto the activated patches. By varying the spatial arrangement of the enzymatic patches, and the sequence in which the appropriate reactants are added to the solution, we realize spatiotemporal control over the fluid flow and the sequential transport of microparticles from one patch to another. The order in which the particles visit the different patches can be altered by varying the sequence in which the reactants are added to the solution. By harnessing catalytic cascade reactions, where the product of one reaction is the reactant for the next, we achieve directed transport between the patches with the addition of just one reactant, which initiates the catalytic cascade. Through these studies, we show how the trajectory of the particles' motion among different "stations" can be readily regulated through intrinsic catalytic reactions and thus, provide guidelines for creating fluidic devices that perform multistep reactions in an autonomous, self-sustained manner.