Thermal profiles of Cicindelidia haemorrhagica (Coleoptera: Cicindelidae) activity in hot springs in Yellowstone National Park.

The wetsalts tiger beetle, Cicindelidia haemorrhagica (LeConte) (Coleoptera: Cicindelidae), is found in several active thermal hot spring areas in Yellowstone National Park (YNP) where substrate surface temperatures can exceed 50 °C. However, relationships between surface temperatures and the time adults spend on them remain poorly understood. Therefore, we characterized thermal profiles of Dragon Spring and Rabbit Creek, 2 thermally active research sites containing C. haemorrhagica in YNP, to quantify the time adults spend at different surface temperatures. We took 58 thermal video recordings of adults over 6 total days of observation ranging from 10 to 15 min for each adult. Thermal video analysis results indicated a positive relationship between the total time adult beetles spent on surface temperatures from Dragon Spring and Rabbit Creek as temperatures increased from 20 °C. Once surface temperatures exceeded 40 °C, the total time spent at those surface temperatures declined. Adults were recorded on substrates exceeding 50 °C at one of the 2 research locations. Rabbit Creek had substantially more instances of adults present with surface temperatures exceeding 40 °C, including one individual on a surface temperature of 61.5 °C. There were 3 instances of beetles spending more than 4 min at a particular surface temperature, all within the preferred range of 30-40 °C. Our thermal profile results and previous behavioral observations suggest that adults may be resistant to the heat produced from the thermal waters that influence the substrate temperatures but may not be subject to high surface temperatures as previously reported.

Heavy metal movement through insect food chains in pristine thermal springs of Yellowstone National Park.

Yellowstone National Park thermal features regularly discharge various heavy metals and metalloids. These metals are taken up by microorganisms that often form mats in thermal springs. These microbial mats also serve as food sources for invertebrate assemblages. To examine how heavy metals move through insect food webs associated with hot springs, two sites were selected for this study. Dragon-Beowulf Hot Springs, acid-sulfate chloride springs, have a pH of 2.9, water temperatures above 70 °C, and populations of thermophilic bacterial, archaeal, and algal mats. Rabbit Creek Hot Springs, alkaline springs, have a pH of up to 9, some water temperatures in excess of 60 °C, and are populated with thermophilic and phototrophic bacterial mats. Mats in both hydrothermal systems form the trophic base and support active metal transfer to terrestrial food chains. In both types of springs, invertebrates bioaccumulated heavy metals including chromium, manganese, cobalt, nickel, copper, cadmium, mercury, tin and lead, and the metalloids arsenic, selenium, and antimony resulting from consuming the algal and bacterial mat biomass. At least two orders of magnitude increase in concentrations were observed in the ephydrid shore fly Paracoenia turbida, as compared to the mats for all metals except antimony, mercury, and lead. The highest bioaccumulation factor (BAF) of 729 was observed for chromium. At the other end of the food web, the invertebrate apex predator, Cicindelidia haemorrhagica, had at least a 10-fold BAF for all metals at some location-year combinations, except with antimony. Of other taxa, high BAFs were observed with zinc for Nebria sp. (2180) and for Salda littoralis (1080). This accumulation, occurring between primary producer and primary consumer trophic levels at both springs, is biomagnified through the trophic web. These observations suggest trace metals enter the geothermal food web through the microbial mat community and are then transferred through the food chain. Also, while bioaccumulation of arsenic is uncommon, we observed five instances of increases near or exceeding 10-fold: Odontomyia sp. larvae (13.6), P. turbida (34.8), C. haemorrhagica (9.7), Rhagovelia distincta (16.3), and Ambrysus mormon (42.8).

Posterior restoration rotational torque associated with cuspal incline angulation: A proof of concept.

STATEMENT OF PROBLEM: Off-axis, external forces with a moment arm on posterior restorations have not been investigated in experimental studies. PURPOSE: The purpose of this proof-of-concept study was to determine the interaction between occlusal force directed toward cuspal incline angulations with variations in base width and preparation vertical heights. Torque forces on a single crown restoration in simulated premolar and molar tooth forms were calculated for 3 different rotational axes. MATERIAL AND METHODS: Trigonometric calculations were made to determine the amount of torque generated in a simulated-crown restoration in premolar and molar tooth forms. Restorations with different cuspal incline angulations were loaded with an off-axis force of 200 N. This force was applied to 5 different cuspal incline angulations in both tooth forms at varying preparation heights. Right triangles were used to enable trigonometric computations of the resulting moment arms that accompanied the 3 rotational axes. RESULTS: The total torque values were calculated with a range from 7.5 to 372.8 Ncm. The highest levels of torque were generated in the 5-mm-high molar tooth form with a rotational axis located within the root form, perpendicular to the 45-degree cuspal incline. In general, large moment arms were generated with steep cuspal incline angulations and mid-root axis locations; the lowest torque values in all cuspal incline angulations were found in the rotational axis locations at the crown finish line. The torque values at the rotational axis finish line location were found to be greatest in the largest vertical tooth form height category (5 mm) in both tooth model sizes. CONCLUSIONS: The crown restoration cuspal incline angulations, vertical preparation heights, base widths, and rotational axis locations all played a role in the torque force levels generated, probably influencing restoration stability.

Habitat Characteristics, Distribution, and Abundance of Cicindelidia haemorrhagica (LeConte) (Coleoptera: Cicindelidae) in Yellowstone National Park.

We observed the tiger beetle species, Cicindelidia haemorrhagica (LeConte), foraging in and reproducing near the thermal pools of Yellowstone National Park (YNP). Although this species was recorded in YNP more than 130 years ago, its distribution, ecology, and association with thermal features are unknown. Therefore, we examined the distribution and habitat characteristics of C. haemorrhagica and evaluated methods for studying its abundance. Given the extreme environments in which these beetles live, typical methods to estimate abundance are challenging. We used a series of presence/absence studies and observations to assess distribution and recorded temperature and pH measurements to determine habitat characteristics. We also conducted visual counts, light trapping, and mark/recapture experiments to assess abundance. The inability to capture C. haemorrhagica with lights led to a phototaxis experiment, which showed minimal attraction to light. Cicindelidia haemorrhagica was found throughout YNP, but it was exclusively associated with thermal springs. The thermal springs ranged from pH 2.7 to 9.0 with temperatures from 29.1 to 75.0 °C and had varying metal concentrations in soil and water. However, all thermal springs with C. haemorrhagica had barren soil with a gradual slope toward the thermal water. Specifically, habitats were thermal pools with gradual margins (a less than five-degree slope) and thermal (i.e., heated) soils for larval burrows by thermal springs or pools. Population sizes of C. haemorrhagica ranged between 500 and 1500 individuals based on visual counts.

Rotational Restoration Resistance and Future Possibilities for Digital Impression Technology: Literature Review and Survey Data.

Digital impression procedures increasingly have been utilized to capture final impressions of fixed prosthodontic preparations in the natural tooth and single-implant restorations as well as for fixed partial dentures in both conditions. The literature related to restoration resistance to rotational displacement has been reviewed. Many digital camera systems have "open architecture" with the generation of generic standard tessellation language (STL) files. These STL files can be analyzed by software to determine preparation attribute-compliance with evidence-based standards. This literature review presents an overview of the knowledge base and survey data of US certified dental technicians (CDTs) and Canadian registered dental technicians (RDTs). The technician data reveal opinions about the level of clinician compliance with standards from the literature and possible future developments for additional applications of this emerging technology.

Axial wall angulation for rotational resistance in a theoretical-maxillary premolar model.

Objectives: The aim of this study was to determine the influence of short base lengths and supplemental grooves on surface area and rotational resistance in a simulated-maxillary premolar. Materials and Methods: Trigonometric calculations were done to determine the total surface area with and without supplemental grooves. Additional computations were done to determine the maximum wall angle needed to resist rotation displacement in a premolar-sized model. Wall heights of 3.0, 4.0, and 5.0 mm were used in the surface area and rotational axis computations. The rotational axis was located on the lingual restoration margin to produce a buccal-to-lingual rotational displacement. Results: Total surface area decreased with increasing four-wall taper levels from 2° to 18° and decreasing preparation heights from 5 to 3 mm. Significant surface area improvements were found with the supplemental use of mesial and distal axial grooves compared with the same condition without grooves in all taper levels and preparation height categories. Resistance to rotational displacement was determined to occur at only at very low levels of opposing wall taper angles. The use of supplemental grooves on mesial and distal axial walls significantly improved both total surface area and rotational resistance. Conclusions: The vertical wall taper angles, preparation heights, and supplemental grooves play a role in resistance form and restoration stability.

Correction: Effects of collagen matrix and bioreactor cultivation on cartilage regeneration of a full-thickness critical-size knee joint cartilage defects with subchondral bone damage in a rabbit model.

[This corrects the article DOI: 10.1371/journal.pone.0196779.].

Effects of collagen matrix and bioreactor cultivation on cartilage regeneration of a full-thickness critical-size knee joint cartilage defects with subchondral bone damage in a rabbit model.

Cartilage has limited self-repair ability. The purpose of this study was to investigate the effects of different species of collagen-engineered neocartilage for the treatment of critical-size defects in the articular joint in a rabbit model. Type II and I collagen obtained from rabbits and rats was mixed to form a scaffold. The type II/I collagen scaffold was then mixed with rabbit chondrocytes to biofabricate neocartilage constructs using a rotating cell culture system [three-dimensional (3D)-bioreactor]. The rabbit chondrocytes were mixed with rabbit collagen scaffold and rat collagen scaffold to form neoRBT (neo-rabbit cartilage) and neoRAT (neo-rat cartilage) constructs, respectively. The neocartilage matrix constructs were implanted into surgically created defects in rabbit knee chondyles, and histological examinations were performed after 2 and 3 months. Cartilage-like lacunae formation surrounding the chondrocytes was noted in the cell cultures. After 3 months, both the neoRBT and neoRAT groups showed cartilage-like repair tissue covering the 5-mm circular, 4-mm-deep defects that were created in the rabbit condyle and filled with neocartilage plugs. Reparative chondrocytes were aligned as apparent clusters in both the neoRAT and neoRBT groups. Both neoRBT and neoRAT cartilage repair demonstrated integration with healthy adjacent tissue; however, more integration was obtained using the neoRAT cartilage. Our data indicate that different species of type II/I collagen matrix and 3D bioreactor cultivation can facilitate cartilage engineering in vitro for the repair of critical-size defect.

Theoretical axial wall angulation for rotational resistance form in an experimental-fixed partial denture.

PURPOSE: The aim of this study was to determine the influence of long base lengths of a fixed partial denture (FPD) to rotational resistance with variation of vertical wall angulation. MATERIALS AND METHODS: Trigonometric calculations were done to determine the maximum wall angle needed to resist rotational displacement of an experimental-FPD model in 2-dimensional plane. The maximum wall angle calculation determines the greatest taper that resists rotation. Two different axes of rotation were used to test this model with five vertical abutment heights of 3-, 3.5-, 4-, 4.5-, and 5-mm. The two rotational axes were located on the mesial-side of the anterior abutment and the distal-side of the posterior abutment. Rotation of the FPD around the anterior axis was counter-clockwise, Posterior-Anterior (P-A) and clockwise, Anterior-Posterior (A-P) around the distal axis in the sagittal plane. RESULTS: Low levels of vertical wall taper, ≤ 10-degrees, were needed to resist rotational displacement in all wall height categories; 2-to-6-degrees is generally considered ideal, with 7-to-10-degrees as favorable to the long axis of the abutment. Rotation around both axes demonstrated that two axial walls of the FPD resisted rotational displacement in each direction. In addition, uneven abutment height combinations required the lowest wall angulations to achieve resistance in this study. CONCLUSION: The vertical height and angulation of FPD abutments, two rotational axes, and the long base lengths all play a role in FPD resistance form.

FEA evaluation of the resistance form of a premolar crown.

PURPOSE: The purpose of this study was to evaluate the influence of buccal and lingual wall convergence angles on the ability of the preparation to resist rotational displacement. MATERIALS AND METHODS: An intact premolar digitized by micro-CT yielded a 3D reproduction of a human tooth. Simulated crown preparations with known buccolingual axial wall convergence angles (4°, 8°, 12°, 16°, 20°, 24°, 28° 32°), sloped-shoulder marginal area, and occlusal reduction were created and restored with a ceramic crown. The tooth restoration was loaded with a 200 N force at 45° to the incline of the buccal cusp. The responses of the restored tooth with luting agents were analyzed using the 3D finite element method. RESULTS: This study demonstrated that a convergence angle of the preparation above 12° produced a decrease of the resistance of the crown to rotational effects. The study also showed that the use of luting agents that provide bonding between the restoration and dentine improved the rotational resistance of the crown on preparations with large convergence angles. CONCLUSIONS: Use of buccolingual convergence angles greater than 12° reduced the resistance form of the preparation. Luting agents capable of delivering strong bonding between the crown and the preparation improved the resistance in highly tapered preparations.

Phenotypic changes in proliferation, differentiation, and migration of chondrocytes: 3D in vitro models for joint wound healing.

We aim to establish a 3D model of cartilage wound healing, and explore the involvement of chondrocytes in its repair. To characterize chondrocyte involvement in wound healing, an in vitro 3D model composed of chondrocyte mixing with either type II/I collagen or type I collagen matrix was established. The "defects" measuring 5 mm in diameter were made on each collagen matrix-chondrocyte construct to mimic in vivo cartilage defects. The effects of basic fibroblast growth factor (bFGF) on chondrocytes migration and differentiation were studied. The migration and Glucosaminoglycan (GAG) synthesis of chondrocytes in the defect areas were observed by microscopy after Alcian-blue staining. In the presence of bFGF, GAG expression increased significantly when chondrocytes were cultured in type II/I collagen matrix compared to type I collagen matrix. However, mild GAG accumulation was also found when cells were cultured in either type I or type II/I collagens without bFGF. In a 3D model of cartilage wound healing, bFGF promote chondrocyte proliferation, migration and differentiation in the presence of type II/I collagen matrix, and showed potential to regulate wound healing. These wound healing models may provide feasible methods to explore various drugs prior to human trials.

Effects of the nanostructure and nanoporosity on bioactive nanohydroxyapatite/reconstituted collagen by electrodeposition.

Hydroxyapatite (HA)/collagen composites were reported to induce bony growth. Various methods for preparing HA-based composites have been investigated as potential biomaterials for bone substitutes. However, no method can generate a thick nanoporous HA. A novel bone regenerative nanocomposite consisting of nano-hydroxyapatite (HA), nano-amorphous calcium phosphate (ACP) and reconstituted collagen by electrodeposition was designed in this research. Specimens with and without nanoporosity were evaluated using electrochemical measurements, material analyses, and cell-material interactions. The results showed that reconstituted collagen/nano-(HA and ACP) illustrated a multinanoporous structure and enhanced biocompatibility. Nanocomposite was comprised to nano-(HA and ACP) and reconstituted collagen. The core cell structure was formed during electrodeposition. Nanoporosity and nanostructure were observed as formation of nanocomposite. The nano-(HA and ACP) phases were essentially composed of a nanoporous and nanostructural biocomposite. Reconstituted collagen incorporation with the nanoporous and nanostructural biocomposite significantly facilitated the osteogenic differentiation of mesenchymal stem cells. Reconstituted collagen was covered with nano-(HA and ACP), profoundly impacting the enhancement of biocompatibility on application of implant and tissue engineering. The bioactive nano-HA/reconstituted collagen-induced osteogenic differentiation of mesenchymal stem cells enables to enhance bone growth/repair and osseointegration.

Surface area improvement with grooves and boxes in mandibular molar crown preparations.

STATEMENT OF PROBLEM: Axial-wall inclination has been shown to affect the stability of a cemented restoration in function, resulting in early restoration failure. PURPOSE: The purpose of this study was to evaluate surface area improvement with the use of supplemental grooves in tooth preparations for complete crowns. MATERIAL AND METHODS: The surface area preparation improvement in combinations of unfavorable/marginal height and axial-wall inclinations was quantified. A right regular pyramid was used to simulate a single mandibular molar tooth preparation with known axial-wall inclinations and vertical heights. Various combinations of these 2 variables allowed the calculation of surface areas with a formula for the area of a pyramid, cones, and right triangles through geometric/trigonometric manipulations. The pyramidal model system had a 9-mm square base with marginal and unfavorable vertical heights, 3 or 4 mm, and axial-wall inclination angles from 2 to 25 degrees. Conical-shaped grooves of varying lengths and widths, depending on height and axial-wall inclinations, were introduced with a tapered fissure bur. The percentage of surface area gained or lost through the supplementation with tapered grooves and boxes served as the dependent variables, alpha-factors (1) through (5). RESULTS: Significant area gains were demonstrated in all alpha-level comparisons. The greatest change was found in the 4-mm height grouping, as a positive 35.2% gain in the 25-degree level with 4 grooves. CONCLUSIONS: Axial-wall groove and box supplementation were shown to improve the surface areas of simulated mandibular molar preparations with unfavorable axial-wall inclination and vertical height levels.

Axial-wall inclination angle and vertical height interactions in molar full crown preparations.

OBJECTIVE: This study has been designed to evaluate the interaction of axial wall heights with inclination angles in full crown tooth preparations. The interaction of these parameters was related to the resulting preparation surface area. MATERIALS AND METHODS: A right regular pyramid was used to simulate a single mandibular molar preparation with known convergence angles and vertical heights. Various combinations of these two variables allowed the calculation of surface areas with a formula for the area of a pyramid and right triangles through trigonometric manipulations. The pyramidal model system had a 9-mm square base with vertical heights from 3- to 5-mm and single-side inclination angles from 2 to 25 degrees. The occlusal surface was a flat, square or rectangular surface and was included in the total area. RESULTS: A percentage of surface area lost or gained served as the dependent variables. The significance levels were set at 10.0% or greater magnitude of loss/gain in a surface area compared to the ideal 2 degree-level. Significant area loss was demonstrated in all alpha-level comparisons. The largest change was found in the 5-mm height grouping compared to the 3-mm height grouping, -36.6% difference between groups at the 2 degree-level. CONCLUSIONS: Axial single-side inclination angles greater than 10 degrees in 3- and 4-mm height-molars are detrimental to maximum surface area in full crown restorations. The 5-mm axial wall height with < or = 10 degree single wall has been shown to maximize the luting agent surface area between restoration and tooth structure.

Effect of margin location on crown preparation resistance form.

STATEMENT OF THE PROBLEM: The location of preparation margins may compromise the fixed prosthodontic restoration's resistance form. Purpose This study evaluated changes of opposite wall margin position on rotational resistance form compared to the equal-height margin configuration. MATERIAL AND METHODS: The trigonometric computation of the minimal resistance form preparation taper, alpha1 , was determined using a previously described formula. The alpha1-values for different tooth sizes with variation of base widths (range 4 to 10 mm) and vertical wall heights (range 4 to 9 mm) were calculated. The alpha1-values represent resistance form with both opposing wall margins at the same vertical height position. The alpha2-values were calculated with additional formulas to address uneven margin heights. Calculated alpha2-values of 10 degrees or less were considered clinically significant due to the known level of difficulty for the clinician. RESULTS: As a general trend, the alpha2-values were reduced compared to the alpha1-values with shortening opposing vertical wall heights in all tooth-size categories. Clinically significant changes in the resistance form taper were shown in all tooth size categories except the smallest 4-mm tooth base size. CONCLUSION: Fixed prosthodontic restoration resistance form is negatively affected by uneven vertical margin placement. This phenomenon reduces the resistance form of the restoration compared to equal-height margin placement.

Maximizing mandibular prosthesis stability utilizing linear occlusion, occlusal plane selection, and centric recording.

The stability of mandibular complete dentures may be improved by reducing the transverse forces on the denture base through linear (noninterceptive) occlusion, selecting an occlusal plane that reduces horizontal vectors of force at occlusal contact, and utilizing a central bearing intraoral gothic arch tracing to record jaw relations. This article is intended to acquaint the reader with one technique for providing stable complete denture prostheses using the aforementioned materials, devices, and procedures.

Minimal intervention prosthodontics: current knowledge and societal implications.

Minimal intervention prosthodontics can be considered a treatment option for a country's overall dental health care plan. Prosthodontics can cover a range of increasingly aggressive treatment interventions depending on the severity and progression of the disease. The 'shortened dental arch' concept is a minimal treatment intervention approach that has been advocated for a wide range of partially edentulous patients. This concept favors limited prosthodontic intervention to achieve patient-perceived acceptable function levels in the presence of multiple missing teeth. The implementation of minimal interventions should be balanced by considering risk-to-benefit ratios, as well as the consequences of nonintervention of low-level prosthodontic interventions. The 'nonintervention' approach and low-level prosthodontic interventions have inherent consequences and well-documented risks; professional ethics dictate that a practitioner present these risks as well as the known benefits of all treatment options. Developing countries are under significant pressure to effectively utilize limited resources, increase skilled human resources, provide advanced levels of care to very large numbers of patients and plan for the future dental health care of their society. Many developing countries are prime candidates for inadvertent abuse and misappropriation of prosthodontic materials, treatment modalities and human resources in trying to provide cost-effective prosthodontic care. A developing country can learn from the mistakes that developed countries have made in the past and use the evidence from these experiences to plan for a better future state of dental health for their society.