Crassulacean acid metabolism (CAM) photosynthesis is a successful adaptation that has evolved often in angiosperms, gymnosperms, ferns and lycophytes. Present in ~5 % of vascular plants, the CAM ...diaspora includes all continents apart from Antarctica. Species with CAM inhabit most landscapes colonized by vascular plants, from the Arctic Circle to Tierra del Fuego, from below sea level to 4800 m a.s.l., from rainforests to deserts. They have colonized terrestrial, epiphytic, lithophytic, palustrine and aquatic systems, developing perennial, annual or geophyte strategies that can be structurally arborescent, shrub, forb, cladode, epiphyte, vine or leafless with photosynthetic roots. CAM can enhance survival by conserving water, trapping carbon, reducing carbon loss and/or via photoprotection.
This review assesses the phylogenetic diversity and historical biogeography of selected lineages with CAM, i.e. ferns, gymnosperms and eumagnoliids, Orchidaceae, Bromeliaceae, Crassulaceae, Euphorbiaceae, Aizoaceae, Portulacineae (Montiaceae, Basellaceae, Halophytaceae, Didiereaceae, Talinaceae, Portulacaceae, Anacampserotaceae and Cactaceae) and aquatics.
Most extant CAM lineages diversified after the Oligocene/Miocene, as the planet dried and CO2 concentrations dropped. Radiations exploited changing ecological landscapes, including Andean emergence, Panamanian Isthmus closure, Sundaland emergence and submergence, changing climates and desertification. Evidence remains sparse for or against theories that CAM biochemistry tends to evolve before pronounced changes in anatomy and that CAM tends to be a culminating xerophytic trait. In perennial taxa, any form of CAM can occur depending upon the lineage and the habitat, although facultative CAM appears uncommon in epiphytes. CAM annuals lack strong CAM. In CAM annuals, C3 + CAM predominates, and inducible or facultative CAM is common.
CAM evolved independently at least eight times in Dendrobium, and divergence of the CAM lineages on the Asian continent was earlier than divergence of those on the Australasian continent.
Abstract
...Members of the Orchidaceae, one of the largest families of flowering plants, evolved the crassulacean acid metabolism (CAM) photosynthesis strategy. It is thought that CAM triggers adaptive radiation into new niche spaces, yet very little is known about its origin and diversification on different continents. Here, we assess the prevalence of CAM in Dendrobium, which is one of the largest genera of flowering plants and found in a wide range of environments, from the high altitudes of the Himalayas to relatively arid habitats in Australia. Based on phylogenetic time trees, we estimated that CAM, as determined by δ 13C values less negative than –20.0‰, evolved independently at least eight times in Dendrobium. The oldest lineage appeared in the Asian clade during the middle Miocene, indicating the origin of CAM was associated with a pronounced climatic cooling that followed a period of aridity. Divergence of the four CAM lineages in the Asian clade appeared to be earlier than divergence of those in the Australasian clade. However, CAM species in the Asian clade are much less diverse (25.6%) than those in the Australasian clade (57.9%). These findings shed new light on CAM evolutionary history and the aridity levels of the paleoclimate on different continents.
Objectives
To present the results of guided bone regeneration (GBR) of atrophic edentulous ridges with customized CAD/CAM titanium meshes.
Material and methods
Forty‐one patients, presenting with 53 ...atrophic sites, were enrolled between 2018 and 2019. GBR was obtained with titanium meshes filled with autogenous bone chips and bovine bone mineral (BBM). After a mean of 7 months (range: 5–12 months), meshes were removed and 106 implants placed. After a mean of 3.5 months (range: 2–5 months), implants were uncovered and prosthetic restorations started. The outcomes were vertical and horizontal bone augmentation changes, biological complications and implant survival.
Results
Out of 53 sites, 11 underwent mesh exposure: eight of them were followed by uneventful integration of the graft, while three by partial bone loss. The mean vertical and horizontal bone gain after reconstruction was 4.78 ± 1.88 mm (range 1.00–8.90 mm) and 6.35 ± 2.10 mm (range 2.14–11.48 mm), respectively. At the time of implant placement, mean changes of initial bone gain were −0.39 ± 0.64 mm (range −3.1 to + 0.80 mm) and −0.49 ± 0.83 mm (range –3.7 to +0.4 mm), in the vertical and horizontal dimensions, respectively. Reduction of bone volume was significantly higher (p < .001 for both dimensions) in the exposed sites. The mean follow‐up of implants after loading was 10.6 ± 6.5 months (range: 2–26 months). The survival rate of implants was 100%.
Conclusion
Customized titanium meshes can represent a reliable tool for GBR of severely atrophic sites, with simplification of the surgical phases.
The accuracy of virtual interocclusal records has been evaluated, but clinical studies comparing the clinical output to the virtual design are lacking.
The purpose of this clinical study was to ...evaluate the agreement between the virtual occlusal scheme designed by a computer-aided design and computer-aided manufacturing (CAD-CAM) software program and the occlusal scheme obtained clinically on the definitive prosthesis assessed with articulating paper.
The virtual occlusal scheme design of 20 single monolithic crowns and their adjacent teeth were obtained using an intraoral scanning system (IOS) in 17 participants. These registrations were compared with conventional occlusal records obtained by applying articulating paper in 2 stages: first with 200-μm blue film and the second with 12-μm metallic red articulation tape. The analysis included both the quantity and the quality of the contacts of the conventional occlusal records referred to as the standard method. For accuracy analysis, virtual record sensitivity was calculated per crown as the percentage of true positive virtual contacts of the actual contacts identified by articulating paper. Specificity was also calculated as the percentage of true negative virtual contacts of the actual sites of clearance.
The virtual record sensitivity was 98.5 (95% confidence interval 96 to 100) for the crowns and 95 (95% confidence interval 85 to 100) for the adjacent teeth. The virtual record specificity was 88.6 (95% confidence interval 82.4 to 94.8) for the crowns and 82.6 (95% confidence interval 77.5 to 87.6) for the adjacent teeth. The agreement between the clinical and virtual contact intensities on the crowns was 83 (95% confidence interval 73 to 93) and 67.3 (95% confidence interval 56 to 78.7) for the adjacent teeth. The positive predictive value was 72.83 (95% confidence interval 60 to 86). The negative predictive value was 100% (95% confidence interval 100 to 100).
The intraoral scanning system provided clinically sufficient sensitivity and specificity for identifying the occlusal surface contacts of monolithic crowns. A slight decrease was detected in the system’s sensitivity and specificity in identifying contacts on adjacent teeth and a larger decrease identifying the intensity of these contacts.
The Dentsply Sirona CAD-CAM system intraoral scanner, design software program, and milling unit provide sufficient accuracy in designing and manufacturing single monolithic crowns in terms of the designed static occlusal scheme.
Self-adhesive resin cements (SARCs) are used because of their mechanical properties, ease of cementation protocols, and lack of requirements for acid conditioning or adhesive systems. SARCs are ...generally dual-cured, photoactivated, and self-cured, with a slight increase in acidic pH, allowing self-adhesiveness and increasing resistance to hydrolysis. This systematic review assessed the adhesive strength of SARC systems luted to different substrates and computer-aided design and manufacturing (CAD/CAM) ceramic blocks. The PubMed/MedLine and Science Direct databases were searched using the Boolean formula ((dental or tooth) AND (self-adhesive) AND (luting or cement) AND CAD-CAM) NOT (endodontics or implants). Of the 199 articles obtained, 31 were selected for the quality assessment. Lava Ultimate (resin matrix filled with nanoceramic) and Vita Enamic (polymer-infiltrated ceramic) blocks were the most tested. Rely X Unicem 2 was the most tested resin cement, followed by Rely X Unicem > Ultimate > U200, and μTBS was the test most used. The meta-analysis confirmed the substrate-dependent adhesive strength of SARCs, with significant differences between them and between SARCs and conventional resin-based adhesive cement (α < 0.05). SARCs are promising. However, one must be aware of the differences in the adhesive strengths. An appropriate combination of materials must be considered to improve the durability and stability of restorations.
The aim of this study was to evaluate and compare the fracture resistance of temporary restorations made of polymethylmethacrylate (PMMA), graphene-modified PMMA (GRA), acetal resin (AR) and ...polysulfone (PS) obtained by a subtractive technique (milling) using a computer-aided design and manufacturing (CAD/CAM) system of a three-unit fixed dental prosthesis (FDP).
Four groups of ten samples were fabricated for each material. Each specimen was characterized by a compression test on a universal testing machine, all specimens were loaded to fracture and the value in Newtons (N) was recorded by software connected to the testing machine. The fracture mode was evaluated on all samples using a stereomicroscope.
There were statistically significant differences (
value < 0.005) between PMMA and the other three materials (PMMA: 1302.71 N; GRA: 1990.02 N; RA: 1796.20 N; PS: 2234.97). PMMA presented a significantly lower value than the other materials, and PS showed the highest value. GRA and RA presented a similar range of values but they were still higher than those of PMMA.
GRA, RA and PS are presented as valid options within the range of interim milled restorative materials and as alternatives to PMMA.
This review compared Computer-aided designand Computer-aided manufactured (CAD-CAM) and conventionally constructed removable complete dentures (CDs).
Seventy-three studies reporting on CAD-CAM ...(milled/3D-printed) CDs were included in this review. The most recent literature search was performed on 15/03/2021.
Two investigators searched electronic databases PubMed (MEDLINE), Embase, CENTRAL, online search engines (Google) and research portals. Hand searches were performed to identify literature not available online.
Studies on CAD-CAM CDs were included if they reported on trueness of fit, biocompatibility, mechanical, surface, chemical, color , microbiological properties, time-cost analysis, and clinical outcomes. Inter-investigator reliability was assessed using kappa scores. Meta-analyses were performed on the extracted data .
The kappa score ranged between 0.897–1.000. Meta-analyses revealed that 3D-printed CDs were more true than conventional CDs (p = 0.039). Milled CDs had a higher flexural-strength than conventional and 3D-printed CDs (p < 0.0001). Milled CDs had a higher flexural-modulus than 3D-printed CDs (p < 0.0001). Milled CDs had a higher yield-strength than injection-molded (p = 0.004), and 3D-printed CDs (p = 0.001). Milled CDs had superior toughness (p < 0.0001) and surface roughness characteristics (p < 0.0001) than other CDs . Rapidly-prototyped CDs displayed poor color-stability compared to other CDs (p = 0.029). CAD-CAM CDs d displayed better retention than conventional CDs (p = 0.015). Conventional CDs had a higher strain at yield point than milled CDs (p < 0.0001), and had superior esthetics than 3D-printed (p < 0.0001). Fabrication of CAD-CAM CDs required less chairside time (p = 0.037) and lower overall costs (p < 0.0001) than conventional CDs.
This systematic review concludes that CAD-CAM CDs offer a number of improved mechanical/surface properties and are not inferior when compared to conventional CDs.
CAD-CAM CDs should be considered for completely edentulous patients whenever possible, since this technique offers numerous advantages including better retention, mechanical and surface properties but most importantly preserves a digital record. This can be a great advantage for older adults with limited access to dental care.
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