Marginal Fitness Research Articles

A Comparative Evaluation of Marginal and Internal Fitness of Zirconia Monolithic Crown Fabricated with Different CAD\CAM Systems: (In Vitro Study)

The precision of computer-aided design/computer-aided manufacturing (CAD/CAM) systems is reliant upon their technical attributes and reliability in producing the designated restorations. The evaluation of this precision is primarily conducted through the examination of the marginal and internal fitness of said restorations. Consequently, the objective of this research endeavor was to analyze and compare the marginal and internal fitness of zirconia crowns fabricated using various CAD/CAM systems. The samples were categorized into four groups, each consisting of 10 samples, based on the specific CAD/CAM equipment employed for crown fabrication as follows: Group I fabricated using Sirona CAD\CAM milling machine, Group II fabricated using Dentium CAD\CAM machine, Group III fabricated using XTCERA CAD\CAM machine and Group IV fabricated using IMES-ICORE CAD\CAM machine. Tooth preparation done following the guidelines recommended by KATANA TM Zirconia (Kurary Noritake Dental Inc., Japan). To ensure standardization, one CAD/CAM program designed parameters was selected to be used for all CAD/CAM machines. Cement thickness was directly measured using sectioning technique to assess the crown's internal and marginal fitness. After performing sectioning, measurements were conducted using a digital microscope with a magnification of 230x. Eleven predetermined measuring locations were selected for each sample, representing four distinct areas: two marginal points, two chamfer points, four axial points, and three occlusal points. Results showed that none of four CAD\CAM machines tested was able to accurately reproduce the designed cement space parameter except Group I (Sirona) showed the closest results. As a conclusion, no CAD\CAM system is 100% accurate however, crowns fabricated using Sirona CAD\CAM milling machine showed the closest recordings to selected parameters among other CAD\CAM milling machines tested.

Evaluation of the effects of an Iraqi phosphate bonded investment and two commercial types on the marginal fitness of porcelain- fused- to- metal copings .

The effect of different phosphate- bonded investments on the marginal fitnessof porcelain- fused—to-metal copings cast by one type of noble alloy and one type ofbase metal alloy was studied. Three types of phosphate—bonded investments (Castorit -Super C, Norvest, and Iraqivest) were used for investing the thirty copings of eachgroup. The marginal fitness of each coping was determined by measuring the verticalmarginal discrepancies between the gingival margin of the coping and the margin ofthe preparation at four reference points on the labial, mesial, palatal and distal aspectsof the die by the aid of light traveling microscope .The statistical analysis of the results showed that there were significantdifferences in marginal fitness among different investments for both Pd- Ag& Ni-Cralloys. The Castorit- Super C and Norvest investments produced comparable resultswith both alloys, while the Iraqivest appeared less compatible with Pd-Ag alloy thanthe other two investments and it had comparable compatibility to Norvest investmentwhen used with Ni- Cr alloy. The Ni- Cr alloy (Heraenium NA) copings revealedsignificantly greater marginal discrepancy than the Pd-Ag alloy (QD) eopingsspecially when using Castorit- Super C and Norvest investments .

Digital Evaluation of the Trueness and Fitting Accuracy of a Three-Unit Fixed Zirconium Bridge Fabricated from Different Types of Zirconia and Different Marginal Cement Space Thickness

Abstract Objective The aim of this study was to measure the internal, marginal fitness, and trueness of a three-unit fixed zirconium bridge fabricated using two types of zirconia and different marginal cement space thicknesses. Methods and Materials Thirty-two aluminum master models, constructed by computer numerical control (CNC) milling machines using aluminum rod, representing two prepared aluminum abutments (the upper first premolar and the first molar) were chosen due to differences in shape and dimensions, which may affect adaptation. It may also be considered one of the most common cases in clinical practice and a missing second premolars were used to fabricate a three-unit fixed partial zirconium bridge. A master model was scanned with an intraoral scanner. Fixed dental prostheses (FDPs) were fabricated with two designs (single-layer high-translucent [HT] Katana and ultra-translucent multilayer (UTML] zirconia Katana) and two marginal cement space thicknesses (0 and 25μm for HT and ML). These specimens are divided according to marginal cement space and type of zirconia into four groups, each containing eight samples. Group A: 25-μm marginal cement space with single-layer HT zirconia. Group B: 25-μm marginal gap with UTML zirconia. Group C: 0 μm marginal gap single-layer HT zirconia. Group D: 0 μm marginal gap with UTML zirconia. Fitness and trueness of the fabricated three-unit FDPs were evaluated by scanning the silicone replica of the cement space and analyzing the thickness of the silicone replica in the three-dimensional inspection software (Geomagic Control X, Morrisville, North Carolina, USA). Results Highest mean value of internal gap was recorded at the molar abutment of group D (95.05, ± 3.42 μm), while the lowest was recorded at the premolar abutment of group A (57.12, ± 2.43μm). For marginal gap, the lowest marginal gap was also recorded at the premolar abutment of group A (36.14, ± 3.94μm), and the highest was at the molar abutment of group D (84.74, ± 2.98 μm).For trueness, group A showed the lowest root mean square (RMS) of mean with both abutments compared with group D, which recorded the highest RMS of mean for trueness. Conclusion The marginal cement space thickness affects the FPD internal, marginal fitness, and trueness; single-layer HT (Katana) zirconia shows better fitness and trueness than UTML (Katana).

Influence of stress-relieving heat treatments on the efficacy of Co-Cr-Mo-W alloy copings fabricated using selective laser melting.

Purpose This study aimed to evaluate the influence of stress-relieving heat treatments on the metal-ceramic bond strength and fitness accuracy of selective laser melting (SLM)-fabricated Co-Cr alloy copings.Methods SLM-manufactured Co-Cr samples were stress-relieved at 750 (Ht-750) and 1150 °C (Ht-1150). The microstructure, surface roughness, metal-ceramic bond strength, marginal and internal fit, Vickers hardness, and residual stress were then compared with those of the non-heat-treated group (As-built). The results were analyzed using one-way ANOVA and post-hoc tests (Tukey's or Student's t test) (P = 0.05).Results The microstructure of the Ht-1150 samples had a brittle oxide layer and lower surface roughness, resulting in significantly lower bond strength values than those of the other groups. The As-built group exhibited significantly lower marginal gap values than the Ht-750 and Ht-1150 groups. Therefore, the post-heat treatments degraded the marginal fitness. The surface residual stress in all sample groups were compressive because of the sandblasting effect. The compressive stresses were larger in Ht-1150 than in As-built and Ht-750 owing to their low hardness values.Conclusions Stress-relief annealing porcelain-fused-to-metal single crowns does not improve bond strength and degrades fitness accuracy because additional post-heat treatments induce thermal distortion. These findings are expected to facilitate the direct application of As-built SLM single crowns in dentistry to minimize post-manufacturing costs and time.

Marginal fit and retention force of zirconia resin-bonded fixed dental prostheses in the posterior region with different designs

Background/purposeRetainer debonding of resin-bonded fixed dental prostheses (RBFDPs) is one of the major reasons for their lower survival rates than fixed dental prostheses (FDPs) with full-coverage crowns. Recent advances in milling technology have enabled the fabrication of RBFDPs with complex retainers (D-shaped designs). This study aimed to assess the marginal fit and retention force of zirconia RBFDPs with inlay-, L-, and D-shaped designs to clarify their clinical applications. Materials and methodsThree abutment teeth models without maxillary second premolars were created using inlay-, L-, and D-shaped retainer designs. The zirconia RBFDPs were designed and fabricated according to the manufacturer’s instructions (n = 10). The marginal gap was measured using the silicone replica technique. Zirconia frameworks were bonded to the abutment teeth using resin cement. Tensile test was conducted after thermal cycling and dynamic loading tests. The loads during debonding or fracture were recorded. The failure pattern was analyzed by observing the fracture surface using a scanning electron microscope. ResultsD-shaped RBFDPs showed a significantly larger marginal gap than inlay- and L-shaped RBFDPs (P < 0.05). However, the mean marginal values were clinically acceptable (<120 μm). The D-shaped model exhibited the highest tensile strength in the tensile tests. The inlay-shaped and most of the D-shaped RBFDPs experienced debonding with cohesive failure, whereas the L-shaped RBFDPs showed fractures near the connector. ConclusionThe D-shaped retainer design was superior to the inlay- and L-shaped designs with respect to the inhibition of retainer debonding. However, the marginal fitness needs to be improved.

Comparing Marginal Fitness between Overdenture Copings Produced by Three Techniques

Comparing Marginal Fitness between Overdenture Copings Produced by Three Techniques

Comparative analysis of bonding strength between enamel and overlay of varying thicknesses following an aging test

AbstractBackground/purpose: Overlay restorations can be used clinically as a treatment option to preserve natural dentine. However, whether the residual enamel thickness and overlay thickness affect the adhesion between the restoration and tooth is still unknown. This study was to investigate effects of the overlay thickness and residual enamel thickness on bonding strength. Materials and methodsOverlays of different thicknesses were prepared with natural teeth which had 2, 4, and 6 mm of occlusal reduction (n = 10). Specimens were subjected to 10,000 cycles in water at 5–55 °C, and finally compressive strength tests were used to evaluate the bonding strength. ResultsAll groups showed good bond strength (P > 0.05). The overlay restorations of different thicknesses reduced the preparation amount by 30.3%–7.2% and significantly preserved more of the tooth structure (P < 0.005). Compared to the control group, the overlay restoration increased the marginal fitness by about 0.67–0.88 times. The thermal cycling indicated that the decrease in the maximum bearing stress was due to the aging of the ceramic itself. Therefore, the thickness of the overlay had a greater influence on the compressive strength than the bond strength. ConclusionBased on the above this study recommends an overlay thickness of at least 2 mm in clinical practice. The aging test confirmed that adhesion between the overlay and teeth was quite firm and stable. This shows that a stable adhesive effect of the overlay can be used as a treatment option for preserving a greater amount of a tooth's structure.

Pollen production per flower increases with floral display size across animal-pollinated flowering plants.

The number of open flowers on a plant (i.e., floral display size) can influence plant fitness by increasing pollinator attraction. However, diminishing marginal fitness returns with increasing floral display are expected as pollinators tend to visit more flowers per plant consecutively. An extended flower visitation sequence increases the fraction of ovules disabled by self-pollination (ovule discounting) and reduces the fraction of a plant's own pollen that is exported to sire seeds in other plants (pollen discounting). Hermaphroditic species with a genetic system that prevents self-fertilization (self-incompatibility) would avoid ovule discounting and its fitness cost, whereas species without such a genetically based barrier would not. Contrarily, pollen discounting would be an unavoidable consequence of a large floral display irrespective of selfing barriers. Nevertheless, the increasing fitness costs of ovule and pollen discounting could be offset by respectively increasing ovule and pollen production per flower. We compiled data on floral display size and pollen and ovule production per flower for 1241 animal-pollinated, hermaphroditic angiosperm species, including data on the compatibility system for 779 species. We used phylogenetic general linear mixed models to assess the relations of pollen and ovule production to floral display size. Our findings provide evidence of increasing pollen production, but not of ovule production, with increasing display size irrespective of compatibility system and even after accounting for potentially confounding effects like flower size and growth form. Our comparative study supports the pollen-discount expectation of an adaptive link between per-flower pollen production and floral display across animal-pollinated angiosperms.

Heterogeneous distribution of Cardinium in whitefly populations is associated with host nuclear genetic background.

Inherited bacterial symbionts are very common in arthropods, but infection frequency can vary widely among populations. Experiments and interpopulation comparisons suggest that host genetic background might be important in explaining this variation. Our extensive field investigation showed that the infection pattern of the facultative symbiont Cardinium was heterogeneous across geographical populations of the invasive whitefly Bemisia tabaci Mediterranean (MED) in China, with genetic nuclear differences evident in 2 of the populations: 1 with a low infection rate (SD line) and 1 with a high infection rate (HaN line). However, whether the heterogeneous frequency of Cardinium is associated with the host genetic background remains poorly understood. Here, we compared the fitness of the Cardinium-infected and uninfected sublines with similar nuclear genetic backgrounds from SD and HaN lines, respectively, and further determine whether host extranuclear or nuclear genotype influenced the Cardinium-host phenotype by performing 2 new introgression series of 6 generations between SD and HaN lines (i.e., Cardinium-infected females of SD were backcrossed with uninfected males of HaN, and vice versa). The results showed that Cardinium provides marginal fitness benefits in the SD line, whereas Cardinium provides strong fitness benefits in the HaN line. Further, both Cardinium and the Cardinium-host nuclear interaction influence the fecundity and pre-adult survival rate of B.tabaci, whereas the extranuclear genotype does not. In conclusion, our results provide evidence that Cardinium-mediated fitness effects were closely associated with the host genetic background, which provides a fundamental basis for understanding the mechanism underlying the heterogeneous distribution of Cardinium in B.tabaci MED populations across China.

Influence of Direct and Indirect Digital Data Capturing Techniques on Marginal Accuracy and Internal Fit of CAD/CAM Fabricated PEEK and Zirconia Crowns

Purpose: The aim of this study was to evaluate the marginal and internal fitness of PEEK and Zirconia crowns fabricated by three different impression techniques. Materials and methods: Thirty standardized acrylic die models were prepared. Dies were divided into two main groups (n= 15): Group 1: CAD/CAM fabricated zirconia crowns. Group 2: CAD/CAM fabricated PEEK crowns. Each group was subdivided into three subgroups (n= 5), according to the impression technique using for data acquisition: Sub-group (A): direct digital scans of the model used intraoral digital scanner. Sub-group (B): indirect digital scans of the silicon impressions using extraoral scanner. Sub-group (C): indirect digital scans of the stone casts obtained from silicon impressions using extraoral scanner. Crowns were then designed and fabricated. Marginal and internal gaps were measured using silicone replica technique and field digital microscope. Results: Independent t-test was used for comparison between groups. Comparisons between subgroups were performed by one-way analysis of variance (ANOVA) test, followed by Bonferroni’s post hoc test. In Zirconia group, the highest mean value was recorded in stone cast scan group, followed by intraoral scan, with the least value recorded in impression scan subgroup. In PEEK group, the highest mean value was recorded in stone cast group, followed by impression scan, with the least value recorded in intraoral scan subgroup. Conclusions: All tested crowns showed marginal gap distance values within the clinically acceptable levels. PEEK crowns had lower vertical marginal gap distance than zirconia crowns with different scanning techniques.

Influence of Direct and Indirect Digital Data Capturing Techniques on Marginal Accuracy and Internal Fit of CAD/CAM Fabricated PEEK and Zirconia Crowns

Purpose: The aim of this study was to evaluate the marginal and internal fitness of PEEK and Zirconia crowns fabricated by three different impression techniques. Materials and methods: Thirty standardized acrylic die models were prepared. Dies were divided into two main groups (n= 15): Group 1: CAD/CAM fabricated zirconia crowns. Group 2: CAD/CAM fabricated PEEK crowns. Each group was subdivided into three subgroups (n= 5), according to the impression technique using for data acquisition: Sub-group (A): direct digital scans of the model used intraoral digital scanner. Sub-group (B): indirect digital scans of the silicon impressions using extraoral scanner. Sub-group (C): indirect digital scans of the stone casts obtained from silicon impressions using extraoral scanner. Crowns were then designed and fabricated. Marginal and internal gaps were measured using silicone replica technique and field digital microscope. Results: Independent t-test was used for comparison between groups. Comparisons between subgroups were performed by one-way analysis of variance (ANOVA) test, followed by Bonferroni’s post hoc test. In Zirconia group, the highest mean value was recorded in stone cast scan group, followed by intraoral scan, with the least value recorded in impression scan subgroup. In PEEK group, the highest mean value was recorded in stone cast group, followed by impression scan, with the least value recorded in intraoral scan subgroup. Conclusions: All tested crowns showed marginal gap distance values within the clinically acceptable levels. PEEK crowns had lower vertical marginal gap distance than zirconia crowns with different scanning techniques.

EFFECTS OF THREE-DIMENSIONAL-PRINTED ZIRCONIA ALL-CERAMIC CROWNS ON PERIODONTAL HEALTH AND AESTHETICS OF PATIENTS RECEIVING ANTERIOR TOOTH AESTHETIC RESTORATION

The aim of this study was to evaluate the effects of three-dimensional (3D)-printed zirconia all-ceramic crowns on the periodontal tissues and aesthetics of patients receiving anterior tooth aesthetic restoration. A total of 85 patients with anterior tooth defects treated from January 2018 to October 2019 were selected. We studied zirconia all-ceramic crowns made by computer-aided design and computer-aided manufacturing (CAD/CAM) (control group) and 3D printing (observation group). The short-term restoration effects, periodontal health indices, functional recovery, long-term clinical efficacy and aesthetic effects were compared. The gingival marginal fitness of the observation group was better than that of the control group, but the control group had better tooth color matching (P &lt; 0.05). One year after the restoration, the bleeding index, probing depth, attachment loss, gingival index and plaque index all declined in the two groups, particularly in the observation group. Both the masticatory and language functions were improved in the two groups, especially in the observation group (P &lt; 0.05). Both 3D-printed and CAD/CAM zirconia all-ceramic crowns have better cosmetic restoration effects on the anterior teeth. However, 3D-printed zirconia all-ceramic crowns have better gingival marginal fitness, which can benefit the periodontal tissue recovery, relieve gingival inflammation, and improve masticatory and language functions.

Technical comment on "sex ratios when helpers stay at the nest".

I contributed a paper to volume 60 of the journal. The paper reported on my study of sex-ratio evolution when one sex (females) is helpful but the other sex (males) suffers less from kin competition. I had based my study on a kin-selection model, and so I was dismayed to discover an error in the relatedness calculations therein. Specifically, relatedness coefficients that should have been calculated using a sampling-without-replacement scheme were instead calculated using sampling with replacement. Here, I correct my error and show how it impacts my original findings. I argue that my main conclusions are unchanged. Furthermore, only two new findings contrast with those I presented earlier. First, changing those model details unrelated to the marginal fitness benefits of help does not, in turn, impact substantially the conflict that occurs between mates over the brood sex ratio (I had previously reported some noteworthy impact was possible). Second, help can reduce sex-ratio conflict between mates more effectively when breeders occur in smaller groups (previously, I had said this occurred in larger groups).

Evaluation of Fitness and Accuracy of Milled and Three-Dimensionally Printed Inlays.

This article compares and evaluates the marginal and internal fitness and three-dimensional (3D) accuracy of class II inlays fabricated using Tescera (TS) resin, milling of hybrid and zirconia blocks, and 3D printing with NextDent C&B. Fifty-two mesio-occlusal inlays were fabricated using conventional method with TS, milling of Lava Ultimate (LU), milling of Zolid Fx multilayer (ZR), and 3D printing (n = 13 each). The marginal and internal fitness were evaluated at six points in the mesio-distal section of a replica under a digital microscope (160× magnification), and the accuracy was evaluated using 3D software. Analyses were conducted using t-test, one-way analysis of variance (ANOVA) and two-way ANOVA, while Duncan's multiple range test was used for post hoc analyses (α = 0.05). The marginal and internal fitness of the 3D and ZR were significantly superior to that of the TS and LU. For LU, ZR, and 3D, a significant discrepancy between the marginal gap and internal gap was observed (p < 0.05). On evaluating accuracy, trueness was significantly higher in ZR than in TS and LU; precision was significantly higher in 3D and ZR than in TS and LU (p < 0.05). The marginal and internal fitness and the accuracy of TS, ZR, and 3D were within the clinically acceptable range. The marginal and internal fitness and accuracy of 3D were better than those of TS and LU, which are commonly used in dentistry. There is immense potential for using 3D-printed inlays in routine clinical practice.

Comparative evaluation of the marginal fitness of vonlay nanoceramic hybrid restorations using different computer-aided imaging techniques

Purpose The purpose of this in-vitro study was to evaluate the marginal fitness of vonlay nanoceramic hybrid restorations using different computer-aided imaging technique (an in-vitro study). Materials and methods Thirty 3D printed models of prepared premolar (no. 14) for vonlay restoration were fabricated using epoxy resin material and used for fabrication of thirty nanohybrid ceramic vonlays (Grandio Disc, VOCO). three groups (n = 10) of vonlays were fabricated using three different imaging technique: group 1: imaging of conventional impression of master die, group 2: imaging of stone master die and group 3: imaging of master die using chairside TRIOS Intraoral Scanners (3Shape). Vonlays were designed by using a CAD design software program (Exocad Dental CAD, Exocad. The vonlays were cemented over their corresponding dies with an automix dual cure adhesive cement system (Duo-Link universal resin cement, Bisco Inc.) under a static load by using custom made seating device. Digital microscope was used to measure the vertical marginal gap for each where a total of 120 measurements for the three groups (12 sites per vonlay and 10 vonlays per group) were evaluated. One-way analysis of variance test was used to analyze the results, Student sample t test was used to examine the marginal gap differences of each group and in the same group. Results A significant difference (P &lt; 0.001) was found between the marginal gap values of the vonlay restoration fabricated by using different imaging technique. The smallest marginal gaps were obtained with vonlay fabricated using chairside intraoral scanners as compared with imaging of master die impression and stone master die. But there was no significant difference between the marginal gap measurements of different sides in the same group. Conclusion The smallest marginal gaps were obtained with vonlay fabricated using chairside intraoral scanners.

A Sled Dog Model for Positive Health Effects of Weight Management and Exercise

Obesity is a significant risk factor for metabolic syndrome and type II diabetes. Physical activity and/or dietary modification can reduce the incidence of obesity. Marginal fitness levels limit the efficacy of exercise training, and most humans choose from a wide range of dietary strategies to lose weight. Despite these limitations, exercise in the absence of weight loss may offer protective benefits against the development of metabolic syndrome and type II diabetes. To examine the benefits of exercise training with and without weight loss, we measured changes in metabolic indices in conjunction with moderate body weight gain, exercise training with no intended change in body weight, and exercise training with bodyweight reduction in a healthy canine model. We measured glucose transporter type 4 on peripheral blood mononuclear cells, plasma glucose, hemoglobin A1c, tumor necrosis factor-alpha, interleukin 6, and insulin levels before, during, and after weight gain, exercise, and weight loss. Weight gain increased plasma glucose, while exercise increased glucose transporter by 4% in peripheral blood mononuclear cells. We also observed changes to plasma glucose, glucose transporter 4, and tumor necrosis factor-α which may be indicative of reduced insulin sensitivity with exercise and weight loss, potentially due to the high energy demand coupled with low caloric availability.

Comparison the marginal and internal fitness of veneered and anatomical zirconia crowns milled by two different CAD/CAM systems (An in Vitro Study)

Background: Accuracy of fit is considered a very important factor in a crown fabricating procedure. Zirconium oxide ceramic is gaining popularity because of its remarkable mechanical capabilities and the potential aesthetic results obtained by using its recommended veneering porcelain, this study aimed to determine the effect of porcelain veneering on the marginal and internal fitness of zirconium-oxide crowns milled with two different CAD/CAM systems ( Wet and dry milling).&#x0D; Materials and methods: An ideal prepared tooth #16 to receive an all-ceramic crown restoration with 0.8mm chamfer finishing line was used as a master die. It duplicated and poured to get thirty-two stone working dies. The stone dies divided into two major groups according to the CAD/CAM systems being used, then each group subdivided into two subgroups (n=8) either zirconia crowns milled to full contour or traditional veneered zirconia crowns. Each crown then cemented to it stone die and sectioned longitudinally into four pieces. Stereomicroscope with aid of (image J) was used to examine the sample at a magnification of (140X). Four points of measurement were selected at each of the four-sectioned parts.&#x0D; Results: The final internal gap value of each sample was the arithmetical mean of the selected points of the four-sectioned pieces The data was evaluated statistically, using One-way ANOVA and LSD tests which revealed highly significant differences (p&lt;0.001) among groups.&#x0D; Conclusion: Full-contoured zirconia crowns have better marginal and internal fit than the traditionally veneered crown, (CEREC AC, Sirona) system showed the best internal fitness. The mean gap of all groups was within the clinically acceptance.

On the sign of the average effect of an allele

The concept of the average effect of an allele pervades much of evolutionary population genetics. In this context the average effect of an allele is often considered as the main component of the “fitness” of that allele. It is widely believed that, if this fitness component for an allele is positive, then the frequency of this allele will increase, at least for one generation in discrete-time models. In this note we show that this is not necessarily the case since the average effect of an allele on fitness may be different from its marginal additive fitness even in a one-locus setting in non-random-mating populations.

Comparative Ecophysiology of Hybrid Wood Fern Species

Premise of research. Polyploidy and hybridization are prevalent and widespread phenomena in plants. The genetic consequences of genome duplication are numerous, but we understand very little about the comparative ecology of polyploids. In particular, the ways in which hybrid and polyploid offspring differ in ecology relative to their parents and relatives are poorly known. Among angiosperms, the triploid bridge is hypothesized to accrue some marginal fitness benefit to parent species from mostly sterile hybrid offspring. Because of the complexities of the fern life cycle, involving two free-living life stages, the ability to backcross via a triploid bridge should be more limited. If the triploid sporophyte offspring provide no fitness benefit to parents via subsequent generations, this raises the question about whether triploids further compete with parents by occupying similar ecological niches. We investigated comparative ecophysiology across light and wetness gradients of five members of the hybrid wood fern complex, Dryopteris. Methodology. We selected two related triads. Each triad consisted of a triploid and its diploid and tetraploid progenitor species: the D. × triploidea (3n) triad, with the parents D. carthusiana (4n) and D. intermedia (2n), and the D. × bootii (3n) triad, with the parents D. cristata (4n) and D. intermedia (2n). We sampled the temperature and relative humidity, population abundance and relative frequency, photosynthetic parameters, and hydraulic conductivity of populations to examine the extent of shared ecological niche space. Pivotal results. We found that triploids varied in habitat space relative to their parents. In the case of the triploid D. × bootii, this taxon occupied habitats similar to those of its parents at similar abundances and frequencies. In the case of D. × triploidea, the hybrid occurred across a more diverse range of habitats, which was more similar to its diploid parent. In both triads, the triploid’s photosynthetic rate was intermediate between those of its parents, and the majority of the photosynthetic parameters were similar to those of the parents. There were some differences in hydraulic conductivity: xylem-specific hydraulic conductivity of the triploid D. × bootii was significantly higher than that of its diploid parent. Conclusions. Our results show that related triploids, diploids, and tetraploids substantially overlap in morphological and physiological niche space. The high relative frequency of triploids in habitats and the lack of clear niche partitioning within triads suggest that in addition to not contributing to parental reproductive fitness, the triploids could also negatively impact their progenitors by potentially competing for space and light resources in similar ways.

Fitness of self-glazed zirconia onlays using conventional and digital impressions

ABSTRACT The fitness of self-glazed zirconia (SGZ) onlays fabricated with computer-aided design/computer-aided manufacturing was analysed, and conventional impressions (CIs) were compared with intraoral digital impressions (DIs). Onlay preparation was applied on a typodont left mandibular first molar to create 22 copy dies, which were divided into DI and CI groups. The marginal gap of DI-fabricated onlays was smaller than that of CI-fabricated onlays (p < 0.05). In both groups, the marginal gap was larger in the distal gingival than in other regions (p < 0.05), and a trend of decreasing marginal accuracy after thermal cycling was observed. SGZ onlays performed well for internal fitness; the overall internal gaps were 72.05 ± 8.16 and 100.96 ± 22.53 μm in Groups DI and CI, respectively. SGZ onlays exhibited clinically acceptable marginal and internal fitness values. The marginal adaptation of DI-fabricated onlays was better than that of CI-fabricated onlays.