The cracked tooth conundrum: Terminology, classification, diagnosis, and management

ABSTRACT: Purpose: To provide an overview of the clinical features, diagnosis, classification and management of cracked teeth which may be a diagnostic challenge in clinical practice. Results: Cracks may initiate from coronal tooth structure or from within the root and affect healthy or root treated teeth. There are many terminologies and classifications in the literature for cracked teeth that can be as confusing as the array of clinical symptoms which are associated with this condition. The term "cracked tooth syndrome" is misleading as there are a range of symptoms that do not form a distinct and reliable pattern. Symptoms will vary with teeth that have healthy pulps, for teeth with inflamed or necrotic pulps, and for teeth that have been root treated. The American Association of Endodontists have classified five specific variations of cracked teeth; craze line, fractured cusp, cracked tooth, split tooth, and vertical root fracture. The importance of differentiating dentin, pulpal and periodontal pain for diagnosis and treatment for these specific entities will be elaborated. A decision flow chart indicating the treatment options available is presented. (Am J Dent 2008;21:275-282). CLINICAL SIGNIFICANCE: A cracked tooth should be considered in the diagnosis of teeth which are sensitive to bite and thermal change. The American Association of Endodontists classification of cracked teeth is useful, though non-vital and root filled cracked teeth and teeth with periapical pathosis should be also considered in forming a diagnosis

Depot repair capacity as a criterion for transportation mode selection in the retrograde movement of reparable assets

To support smaller reparable asset inventories, current Air Force logistics policies direct the “expedited evacuation of reparables ... to the source of repair.” Mode selection is based on the asset. Focusing on the asset is an efficient and effective method of getting assets to where they are needed in a timely manner in the forward portion of the supply pipeline. However, in the reverse portion of the pipeline, the demand for an asset may no longer be critical to how it is transported. The quantity of the asset at the depot may already exceed repair capacity. In this instance, rapid movement results in the asset being added to the backlog already awaiting repair, thus retrograde modal selection focus should shift to repair capacity. Since the depots face budget and manning constraints and do not operate on a continuous basis, their repair capacity is limited. With finite repair resources, the question of when an asset can be repaired should be involved in mode determination. A stock-point modeling approach was used, with depot production requirements as a surrogate for demand in calculating shipping priority. Using Warner Robins Air Logistics Center reparable asset production data, this article illustrates potential savings in transportation that are possible utilizing an alternative factor in modal choice decision for the retrograde or reverse portion of the pipeline

The influence of particle size and curing conditions on testing mineral trioxide aggregate cement

Objectives: To assess the effects on curing conditions (dry versus submerged curing) and particle size on the compressive strength (CS) and flexural strength (FS) of set MTA cement. Materials and methods: Two different Portland cements were created, P1 and P2, with P1 < P2 in particle size. These were then used to create two experimental MTA products, M1 and M2, with M1 < M2 in particle size. Particle size analysis was performed according to ISO 13320. The particle size at the 90th percentile (i.e. the larger particles) was P1: 15.2 μm, P2: 29.1 μm, M1: 16.5 μm, and M2: 37.1 μm. M2 was cured exposed to air, or submerged in fluids of pH 5.0, 7.2 (PBS), or 7.5 for 1 week. CS and FS of the set cement were determined using a modified ISO 9917-1 and ISO 4049 methods, respectively. P1, P2, M1 and M2 were cured in PBS at physiological pH (7.2) and likewise tested for CS and FS. Results: Curing under dry conditions gave a significantly lower CS than when cured in PBS. There was a trend for lower FS for dry versus wet curing. However, this did not reach statistical significance. Cements with smaller particle sizes showed greater CS and FS at 1 day than those with larger particle sizes. However, this advantage was lost over the following 1-3 weeks. Conclusions: Experiments that test the properties of MTA should cure the MTA under wet conditions and at physiological pH

Structure-Function Relationships of the Neisserial EptA Enzyme Responsible for Phosphoethanolamine Decoration of Lipid A: Rationale for Drug Targeting

Bacteria cause disease by two general mechanisms: the action of their toxins on host cells and induction of a pro-inflammatory response that can lead to a deleterious cytokine/chemokine response (e.g., the so-called cytokine storm) often seen in bacteremia/septicemia. These major mechanisms may overlap due to the action of surface structures that can have direct and indirect actions on phagocytic or non-phagocytic cells. In this respect, the lipid A (endotoxin) component of lipopolysaccharide (LPS) possessed by Gram-negative bacteria has been the subject of literally thousands of studies over the past century that clearly identified it as a key virulence factor in endotoxic shock. In addition to its capacity to modulate inflammatory responses, endotoxin can also modulate bacterial susceptibility to host antimicrobials, such as the host defense peptides termed cationic antimicrobial peptides. This review concentrates on the phosphoethanolamine (PEA) decoration of lipid A in the pathogenic species of the genus Neisseria [N. gonorrhoeae and N. meningitidis]. PEA decoration of lipid A is mediated by the enzyme EptA (formerly termed LptA) and promotes resistance to innate defense systems, induces the pro-inflammatory response and can influence the in vivo fitness of bacteria during infection. These important biological properties have driven efforts dealing with the biochemistry and structural biology of EptA that will facilitate the development of potential inhibitors that block PEA addition to lipid A

Methodologies for measuring the setting times of mineral trioxide aggregate and Portland cement products used in dentistry

The current standard used to measure setting time for Mineral Trioxide Aggregate (MTA) involves indentation testing with arbitrary weights. This study compared indentation testing against rheological measurements and assessed the influences of particle size and the inclusion of bismuth oxide on the setting time of experimental MTA and Portland cement (PC). Two PCs (P1 and P2) of different particle sizes were produced using the same clinker. From these two PCs, two experimental MTAs (M1 and M2) were created with the addition of bismuth oxide. Particle size distributions were assessed using laser diffraction analysis. Indentation setting time tests were performed in accordance to the Gillmore needle test. Elastic modulus was assessed using a strain-controlled rheometer at 1 rad s and an applied strain of 0.01%. P1, P2, M1 and M2 cements had median particle sizes of 6.1, 12.5, 6.5 and 13.0 μm, respectively. Using indentation testing, final setting times were ranked P1 < M1 < P2 < M2. The ranking of the final setting time corresponded with the rheological assessment of time required to reach 95% of the elastic modulus plateau. The time to reach 95% elastic modulus plateau of 9.3 min corresponds to a time close to the point where the material can be overlaid with another restorative material to give a final restoration. The 95% plateau value for elastic modulus may be a more useful parameter for determining how the setting reaction of PC and MTA cements progress over time

Deconvolution of the particle size distribution of ProRoot MTA and MTA Angelus

Mineral trioxide aggregate (MTA) cements contain two types of particles, namely Portland cement (PC) (nominally 80% w/w) and bismuth oxide (BO) (20%). This study aims to determine the particle size distribution (PSD) of PC and BO found in MTA. The PSDs of ProRoot MTA (MTA-P) and MTA Angelus (MTA-A) powder were determined using laser diffraction, and compared to samples of PC (at three different particle sizes) and BO. The non-linear least squares method was used to deconvolute the PSDs into the constituents. MTA-P and MTA-A powders were also assessed with scanning electron microscopy. BO showed a near Gaussian distribution for particle size, with a mode distribution peak at 10.48 μm. PC samples milled to differing degrees of fineness had mode distribution peaks from 19.31 down to 4.88 μm. MTA-P had a complex PSD composed of both fine and large PC particles, with BO at an intermediate size, whereas MTA-A had only small BO particles and large PC particles. The PSD of MTA cement products is bimodal or more complex, which has implications for understanding how particle size influences the overall properties of the material. Smaller particles may be reactive PC or unreactive radiopaque agent. Manufacturers should disclose particle size information for PC and radiopaque agents to prevent simplistic conclusions being drawn from statements of average particle size for MTA materials

A Method for Setting Northern Bobwhite Population and Habitat Objectives for Large Landscape Partnerships

Population and habitat objectives are the foundation for many conservation actions. Often objectives set at one scale are difficult to translate to larger or smaller scales. Three bird habitat Joint Ventures, Gulf Coast, Oaks & Prairies, and Rio Grande, working cooperatively with the Gulf Coast Prairie Landscape Conservation Cooperative, have a common objective to stabilize northern bobwhite (Colinus virginianus) populations in four Bird Conservation Regions. We cooperatively developed a method using the North American Breeding Bird Survey trend for several scenarios with different time horizons (10-, 20-, 30-year, or longer), the spring home range size, and the per acre cost of habitat management actions, to set spring population and habitat objectives and projected costs. The spring population objectives can easily be converted to fall population objectives using the percent summer gain. We provide an example of how three Joint Ventures could use this methodology to set bobwhite objectives within their geographies and then scale those objectives up to the next larger geography, a Landscape Conservation Cooperative geography. This methodology can be used by other multi-state partnerships (e.g., Joint Ventures and Landscape Conservation Cooperatives) across the bobwhite range to provide the bobwhite conservation community meaningful objectives at regional and national scales

The Critical Juncture Concept’s Evolving Capacity to Explain Policy Change

This article examines the evolution of our understanding of the critical junctures concept. The concept finds its origins in historical intuitionalism, being employed in the context of path dependence to account for sudden and jarring institutional or policy changes. We argue that the concept and the literature surrounding it—now incorporating ideas, discourse, and agency—have gradually become more comprehensive and nuanced as historical institutionalism was followed by ideational historical institutionalism and constructivist and discursive institutionalism. The prime position of contingency has been supplanted by the role of ideas and agency in explaining critical junctures and other instances of less than transformative change. Consequently, the concept is now capable of providing more comprehensive explanations for policy change