The 10,000-year biocultural history of fallow deer and its implications for conservation policy.

Over the last 10,000 y, humans have manipulated fallow deer populations with varying outcomes. Persian fallow deer (Dama mesopotamica) are now endangered. European fallow deer (Dama dama) are globally widespread and are simultaneously considered wild, domestic, endangered, invasive and are even the national animal of Barbuda and Antigua. Despite their close association with people, there is no consensus regarding their natural ranges or the timing and circumstances of their human-mediated translocations and extirpations. Our mitochondrial analyses of modern and archaeological specimens revealed two distinct clades of European fallow deer present in Anatolia and the Balkans. Zooarchaeological evidence suggests these regions were their sole glacial refugia. By combining biomolecular analyses with archaeological and textual evidence, we chart the declining distribution of Persian fallow deer and demonstrate that humans repeatedly translocated European fallow deer, sourced from the most geographically distant populations. Deer taken to Neolithic Chios and Rhodes derived not from nearby Anatolia, but from the Balkans. Though fallow deer were translocated throughout the Mediterranean as part of their association with the Greco-Roman goddesses Artemis and Diana, deer taken to Roman Mallorca were not locally available Dama dama, but Dama mesopotamica. Romans also initially introduced fallow deer to Northern Europe but the species became extinct and was reintroduced in the medieval period, this time from Anatolia. European colonial powers then transported deer populations across the globe. The biocultural histories of fallow deer challenge preconceptions about the divisions between wild and domestic species and provide information that should underpin modern management strategies.

HNF4α isoforms regulate the circadian balance between carbohydrate and lipid metabolism in the liver.

Hepatocyte Nuclear Factor 4α (HNF4α), a master regulator of hepatocyte differentiation, is regulated by two promoters (P1 and P2) which drive the expression of different isoforms. P1-HNF4α is the major isoform in the adult liver while P2-HNF4α is thought to be expressed only in fetal liver and liver cancer. Here, we show that P2-HNF4α is indeed expressed in the normal adult liver at Zeitgeber time (ZT)9 and ZT21. Using exon swap mice that express only P2-HNF4α we show that this isoform orchestrates a distinct transcriptome and metabolome via unique chromatin and protein-protein interactions, including with different clock proteins at different times of the day leading to subtle differences in circadian gene regulation. Furthermore, deletion of the Clock gene alters the circadian oscillation of P2- (but not P1-)HNF4α RNA, revealing a complex feedback loop between the HNF4α isoforms and the hepatic clock. Finally, we demonstrate that while P1-HNF4α drives gluconeogenesis, P2-HNF4α drives ketogenesis and is required for elevated levels of ketone bodies in female mice. Taken together, we propose that the highly conserved two-promoter structure of the Hnf4a gene is an evolutionarily conserved mechanism to maintain the balance between gluconeogenesis and ketogenesis in the liver in a circadian fashion.

A conceptual framework to support hospitals to measure and realise financial benefits from process improvement programs: perspectives from Australia, USA and UK.

Objective The objective of this research is to appraise current practice in hospitals against the 'Framework to achieve value in healthcare' (the Framework) and to identify additional contributory factors that support or hinder its application. Methods A multi-site case study was undertaken with five hospitals in Australia, the USA and UK using purposeful sampling to identify hospitals to participate. Data collection took place between September and November 2022. The hospitals included in the study had Process Improvement (PI) programs of more than 5 years duration, with strong executive engagement and broad outcomes measurement, including financial benefits. All hospitals were acute public hospitals or private, not for profit. Results All hospitals indicated current practice according to Steps 1-5 for some part of their PI programs. All hospitals indicated that they were more likely to include financial benefits measurement for activities aimed specifically at improving cost rather than reducing non-value adding activities or improving the value of clinical care. Step 5 (reinvestment of cost savings) of the Framework is dependent on the accomplishment of Step 4 (measurement and realisation of financial benefits) and the contributory elements are important in supporting hospitals to utilise the Framework. Conclusions The 'Framework to achieve value in healthcare' provides a practical guide for hospitals to reduce non-value adding activities, improve the value of clinical care and reduce costs. Further research is indicated to establish its reliability in hospitals in other countries and hospitals that do not have an established PI program.

Combining isotope ratios for provenancing Viking Age iron artefacts in the British Isles: a pilot study.

Stable and radiogenic isotope analysis - particularly using lead isotope analysis (LIA) - has previously been shown to be a useful tool for the provenancing of ancient metal artefacts of silver and copper and its alloys, but less progress has been made in the provenancing of iron artefacts, despite their importance and frequency in the archaeological record. In this pilot study we investigate for the first time the possibilities of iron isotope analysis in combination with trace strontium isotope analysis and LIA for the provenancing of iron objects believed to be from the Viking Age in the British Isles. Previous studies have shown that analysis of each of these isotopes can contribute to provenancing iron artefacts, but they are not individually resolutory. In this proof-of-concept study, we examine the Fe, Sr and Pb isotopes of 7 artefacts believed to derive from the Viking Age: 3 from Meols - a former Viking seaport on Wirral and 4 samples from the probable location of the AD 1066 Battle of Fulford in North Yorkshire. We also examine an additional artefact of unknown antiquity from Bebington Heath - a possible location of the AD 937 Battle of Brunanburh. Although the pilot data set is too small to make definitive conclusions, it has paved the way for a fuller study involving 100 samples (including 30 from the former Viking camp of Torksey, Lincolnshire) funded by the NEIF fund of the UK National Environmental Research Council. The high range of 87Sr/86Sr values in the present data set of 8 is beyond what would be expected for bog iron (with a cut-off ∼ 0.709) and suggests that mined ore was being used, a preliminary conclusion supported by the narrow range of Fe isotope data.

Wet feet: developing sulfur isotope provenance methods to identify wetland inhabitants.

The stable isotopes of sulfur provide a distinctive signature for marine proximity and interaction. Exploring coastal proximity has been the principal application of sulfur isotopes in archaeology and palaeoecology, but this deals only with high (greater than 14‰) isotope values, meaning little interpretation has been gained from lower values. Progress has been hindered by issues with biosphere mapping. Air pollution can impact modern landscapes, significantly lowering sulfur isotope baselines, leading to the assumption that modern vegetation-based sulfur maps are not reliable. This research explores the potential of previously undiagnostic low, and often, negative sulfur isotope values for identifying wetland dwellers. Impervious clays that support wetlands are distinctive ecosystems and this study tests the hypothesis that they will produce low isotope values owing to both the underlying substrate and to redox conditions. Primary mapping of targeted areas using modern plants highlights zones with natural negative sulfur values and demonstrates that this constitutes a distinctive wetland signature. Analysis of modern and archaeological fauna demonstrates that these distinctive isotope compositions are transferred into the food chain. These findings propel the interpretative potential of sulfur isotopes forward and add to the growing knowledge to provide means for identifying archaeological humans and animals raised in wetlands.

Effect of build orientation on the trueness of occlusal splints fabricated by three-dimensional printing.

PURPOSE: Scientific evidence pertaining to the evaluation of trueness of occlusal splints fabricated using different three-dimensional (3D) printers and build orientations compared to subtractive technologies is lacking. METHODS: Overall, one hundred and ten occlusal splints were manufactured using two different 3D printers and a dental mill. Five groups of ten were fabricated using the 3D printers at different build orientations (0, 30, 45, 60, and 90 degrees). In addition, a comparison group of ten occlusal splints was subtractively manufactured using a five-axis dental mill. All occlusal splints were scanned and exported as a standard tessellation language file. Analysis was conducted with metrology software with root mean square estimate average positive deviation and average negative deviation used as the measured outcome. RESULTS: The 0 degree printing orientation was the most accurate for printer one with the root mean square value of 0.05 ± 0.01 mm, and 60 degree printing orientation was most accurate for printer two with the RMS value of 0.11 ± 0.01 mm. Subtractively manufactured occlusal splint had significantly higher trueness with the lowest RMS value of 0.03 ± 0.05 mm. CONCLUSION: Build orientations influence the trueness of additively manufactured occlusal splints while occlusal splints produced by subtractive manufacturing were statistically significantly more accurate.

The mechanical properties of 3D printed denture base resin incorporating essential oil microcapsules.

Purpose: The aim of this study was to investigate the mechanical properties of three-dimensional (3D) printed denture base resin incorporating microcapsules containing plant essential oils. Materials and Methods: Denture base specimens containing up to 3% w/v essential oil microcapsule powders (MCPs), i.e., eucalyptus, geranium, lavender, menthol, and tea tree, in two resins (Detax and NextDent 3D+) were 3D printed using two printers (Asiga and NextDent 5100). The dispersion and interaction of the MCPs in the resin were assessed by SEM while the mechanical properties of the incorporated denture base including flexural strength (MPa), flexural modulus (MPa), Vickers hardness (VHN), and surface roughness (Ra) were also subsequently evaluated. Statistical analysis of any differences in mean values was determined using a two-way ANOVA with Tukey's post hoc testing (α = .05). Results: The spherical shape of the MCPs was maintained during the mixing and polymerization/printing process. However, the Detax-Asiga group showed significant agglomeration of the MCPs even at the lowest MCP concentration levels (0.5% w/v). Overall, as the microcapsule concentration increased, the mean flexural strength decreased, though the menthol MCP groups remained compliant with the ISO standard. The flexural modulus and harness remained relatively unchanged, and the flexural modulus complied with the ISO standard regardless of the MCP concentration. Surface roughness increased with the addition of the MCPs but also remained below that required for clinical acceptance. Conclusion: Incorporation of microencapsulated plant essential oils into 3D printed denture base resin was successfully achieved. While incorporation negatively influenced flexural strength and surface roughness, little effect on flexural modulus and Vickers hardness was demonstrated.

A 3-year qualitative evaluation of interprofessional team-based clinical education at an Australian dental school.

PURPOSE/OBJECTIVES: This article describes a qualitative evaluation of interprofessional (IP) team-based treatment planning (TBTP) involving dentistry, oral health therapy, dental prosthetics, and dental technology students at the Griffith University School of Dentistry and Oral Health (DOH). Using the same data from a recently published article that looked solely at the quantitative evaluation of TBTP, this article focuses on the qualitative evaluation of TBTP. This evaluation explores the contextual meaning related to the previously published aspects of TBTP that contributed positively toward oral health students' IP clinical learning and identifies themes reflecting students' IP clinical experience. METHODS: Thematic analysis of transcripts from nine focus groups, comprised of 46 final year students and open-ended questions collected from 544 students through an online instrument from 2012 to 2014, explored the question: "What is the contribution of IP student team-based processes on students' perceptions of IP learning and practice at DOH?" RESULTS: Responses from online participants and student focus groups revealed three major themes: useful role learning, communication confidence, and pro-active collaborative teamwork. Throughout each of these themes, students stated they possessed a confidence in collaborating with other oral health students as exhibited through an understanding of profession-specific and IP roles, self-assurance in communicating, and teamwork skills. CONCLUSION: Aspects of TBTP that contributed positively toward students' IP clinical learning and practice were meaningfully identified.

A systematic review of the evidence of how hospitals capture financial benefits of process improvement and the impact on hospital financial performance.

BACKGROUND: Governments, funders and hospital managers around the world are looking for ways to address the continual growth in expenditure by reducing the level of waste in the healthcare delivery system and improving the value of care provided to patients. Process improvement methods are applied to increase high value care, reduce low value care and remove waste from care processes. The purpose of this study is to review the literature to identify the methods used by hospitals to measure and capture financial benefits from PI initiatives to identify best practice. The review also pursues the way hospitals collate these benefits at the enterprise level to achieve improved financial performance. METHODS: A systematic review was undertaken in line with the PRISMA process and employed qualitative research methods. Databases searched were Medline, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINHAL), Web of Science and SCOPUS. The initial search was conducted in in July 2021 with a follow up search conducted in February 2023 using the same search terms and databases to identify additional studies published in the intervening period. The search terms were identified through the PICO (Participants, Interventions, Comparisons and Outcomes) method. RESULTS: Seven papers were identified that reported reduction in care process waste or improvement of the value of care using an evidence-based PI approach and included financial benefits analysis. Positive financial impact was measured for the PI initiatives but none of the studies reported how these financial benefits were captured or applied at the enterprise level. Three of the studies suggested that sophisticated cost accounting systems were required to enable this. CONCLUSION: The study demonstrates the paucity of literature in the field of PI and financial benefits measurement in healthcare. Where financial benefits are documented, they vary in terms of cost inclusions and the 'level' at which the costs were measured. Further research on best practice financial measurement methods is needed to enable other hospitals to measure and capture financial benefits arising from their PI programs.

Provenancing antiquarian museum collections using multi-isotope analysis.

Many of the most significant archaeological sites in Europe were excavated by antiquarians over one hundred years ago. Modern museum collections therefore frequently contain human remains that were recovered during the nineteenth and early twentieth centuries. Here we apply multi-isotope analysis (87Sr/86Sr, δ 18O, δ 13C, δ 15N) and 14C dating to evaluate the provenance of human remains within a collection that is thought to have been recovered from one of the most important archaeological sites in Britain. Excavated in 1910, the site of Coldrum in Kent is a megalithic burial monument that may be one of the earliest sites associated with the transition to farming in Britain. The interpretation of this site is therefore key to understanding how agriculture began. Using isotope analysis we show that although the human skeletal collections attributed to Coldrum do contain some of the earliest dated Neolithic human remains in Britain, they also contain the remains of individuals of fifth to seventh centuries AD date. We evaluate subsistence and mobility patterns of early Neolithic populations and provide new information about the origins of those individuals in the collection that date to the fifth to seventh centuries AD. We demonstrate the utility of employing isotope analysis to provide direct and independent information about the provenance of human remains in museum collections.

Exploring digital technologies used in the design and manufacture of craniofacial implant surgical guides: A scoping review.

STATEMENT OF PROBLEM: Unlike intraoral implants, digitally planned surgical templates used for guiding the ideal position of the craniofacial implants are not well established, and clear methods and guidelines for their design and construction are lacking. PURPOSE: The purpose of this scoping review was to identify the publications that used a full or partial computer-aided design and computer-aided manufacture (CAD-CAM) protocol to create a surgical guide that achieves the correct positioning of craniofacial implants to retain a silicone facial prosthesis. MATERIAL AND METHODS: A systematic search was conducted in MEDLINE/PubMed, Web of Science, Embase, and Scopus for articles published before November 2021 in the English language. Articles needed to satisfy the eligibility criterion of in vivo articles that created a surgical guide with digital technology for inserting titanium craniofacial implants to hold a silicone facial prosthesis. Articles that inserted implants in the oral cavity or upper alveolus only and articles that did not describe the structure and retention of the surgical guide were excluded. RESULTS: Ten articles were included in the review; all were clinical reports. Two of the articles used a CAD-only approach alongside a conventionally constructed surgical guide. Eight articles described applying a complete CAD-CAM protocol for the implant guides. The digital workflow varied considerably depending on the software program, design, and retention of guides. Only 1 report described a follow-up scanning protocol to verify the accuracy of the final implant positions compared with the planned positions. CONCLUSIONS: Digitally designed surgical guides can be an excellent adjunct to accurately place titanium implants in the craniofacial skeleton for support of silicone prostheses. A sound protocol for the design and retention of the surgical guides will enhance the use and accuracy of craniofacial implants in prosthetic facial rehabilitation.

Mobility and kinship in the world's first village societies.

Around 10,000 y ago in southwest Asia, the cessation of a mobile lifestyle and the emergence of the first village communities during the Neolithic marked a fundamental change in human history. The first communities were small (tens to hundreds of individuals) but remained semisedentary. So-called megasites appeared soon after, occupied by thousands of more sedentary inhabitants. Accompanying this shift, the material culture and ancient ecological data indicate profound changes in economic and social behavior. A shift from residential to logistical mobility and increasing population size are clear and can be explained by either changes in fertility and/or aggregation of local groups. However, as sedentism increased, small early communities likely risked inbreeding without maintaining or establishing exogamous relationships typical of hunter-gatherers. Megasites, where large populations would have made endogamy sustainable, could have avoided this risk. To examine the role of kinship practices in the rise of megasites, we measured strontium and oxygen isotopes in tooth enamel from 99 individuals buried at Pinarbasi, Boncuklu, and Çatalhöyük (Turkey) over 7,000 y. These sites are geographically proximate and, critically, span both early sedentary behaviors (Pinarbasi and Boncuklu) and the rise of a local megasite (Çatalhöyük). Our data are consistent with the presence of only local individuals at Pinarbasi and Boncuklu, whereas at Çatalhöyük, several nonlocals are present. The Çatalhöyük data stand in contrast to other megasites where bioarchaeological evidence has pointed to strict endogamy. These different kinship behaviors suggest that megasites may have arisen by employing unique, community-specific kinship practices.

Overview of incorporation of inorganic antimicrobial materials in denture base resin: A scoping review.

STATEMENT OF PROBLEM: Dental hygiene for institutionalized patients and recurring Candida-associated denture stomatitis remain problematic because of a patient's limited dexterity or inability to eliminate Candida from denture surfaces. Although there has been extensive research into antimicrobial modification of denture base resins with inorganic materials, scoping reviews of the literature to identify knowledge gaps or efficacy of inorganic antimicrobial materials in denture base resins are lacking. PURPOSE: The purpose of this scoping review was to provide a synopsis of the efficacy of the major classes of inorganic antimicrobial materials currently incorporated into denture base resins. MATERIAL AND METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews was applied. Four electronic databases, including Embase, PubMed, Web of Science, and Google Scholar, were accessed for articles in the English language, up to February 2019, without restrictions on the date of publication. RESULTS: From the 53 articles selected, 25 distinguishable inorganic materials were found and divided into 3 subgroups. Forty-three articles evaluated nanomaterials, where mostly silver ion nanoparticles and/or titanium dioxide nanoparticles were incorporated into denture base resins. Fourteen articles examined antimicrobial drugs and medications, including azole group medications, amphotericin-B, Bactekiller, chlorhexidine, Novaron, and Zeomic. Two articles classified as others explored hydroxyapatite- and fiber-incorporated denture base resins. CONCLUSIONS: Although nanotechnology and antimicrobial medications or drugs have been successfully used to reduce Candida-associated denture stomatitis, long-term solutions are still lacking, and their disadvantages continue to outweigh their advantages.

Sources of occupational stress amongst dentistry academics.

BACKGROUND: Dentistry professionals may experience significantly higher occupational stress than other health professionals and dentistry academics may have specific work content and context sources of stress. AIMS: The aim of this study is to identify common sources of occupational stress, and how these are associated with wellbeing, in dentistry academics. MATERIALS & METHODS: A cross-sectional online survey with staff in Dentistry departments in Australia and New Zealand. Assessment included 23 items from five general domains of occupational stress from the NIOSH-Generic Job Stress Questionnaire, a 23-item list of sources of stress and the 22-item Psychological General Well-Being Index. Analyses used descriptive statistics and multiple linear regression. RESULTS: A total of 107 respondents (average age 50 ± 11.7 years, 56.8% men) completed the survey. Leading sources of occupational stress were job future, time pressure at work, work overload, and administration demands. A multiple linear regression model significantly predicted wellbeing, F(8,77) = 13.141, p = .000, adj.R2  = .53, but there were no significant associations for any of the specific sources of stress. CONCLUSION: The combination of time pressure, workload and responsibility, job dissatisfaction, low social support, and uncertain job future was inversely associated with wellbeing amongst these dentistry academics. Future studies should consider the development and evaluation of interventions to address these concerns.

Applying lead (Pb) isotopes to explore mobility in humans and animals.

Lead (Pb) isotopes provide a complementary method to other provenance tools for tracking the origin and movement of humans and animals. The method is founded in the geographic distribution of Pb isotope ratios. However, unlike the Sr isotope method that is closely linked to the lithology of underlying rocks, Pb more closely reflects the tectonic regimes. This makes it particularly pertinent to use in Britain as there is major tectonic boundary (the Iapetus Suture) that runs between Berwick-upon-Tweed and the Solway Firth providing a compositional boundary in Pb isotope domains that approximates to the geographic areas of Scotland versus England and Wales. Modern pollution makes it difficult to use modern floral or faunal samples to characterize biosphere variation, and so we use geological datasets to define isoscape variation and present the first Pb isotope map of Britain. We have validated the use of these data form biosphere studies using well provenanced samples. Reference fields of diagnostic compositions, are created in µ-T space and these have been used in a test case to assess the geographic origins of Neolithic animals in Great Britain.

Use of strontium isotope ratios in geolocation of Guatemalan population: Potential role in identification of remains.

Within post-conflict communities, attempts to identify and repatriate unidentified and missing individuals poses a difficult task. As current forensic strategies commonly lack the capacity to provide region of origin assessments, forensic anthropologists/investigators are often unable to identify sources of DNA for kinship analysis. Using Thermal Ionization Mass Spectrometry (TIMS), hair samples from 10 volunteers were used to assess the variation in strontium isotope ratios (87 Sr/86 Sr) between extant people in Guatemala City and Coban; with a leach (external) and digest (dietary) signal analyzed for each sample. A two-way anova demonstrated that the difference between 87 Sr/86 Sr of Guatemala City and Coban was statistically significant (F [1, 16] = 259.839, p < 0.05), with no statistically significant differences observed between leach and digest 87 Sr/86 Sr (F [1,16] = 4.319, p = 0.054). Overall, individuals from Coban demonstrate 87 Sr/86 Sr comparable to previously recorded baseline values, demonstrating a minimal change in diet which is reflected in associated surveys. Volunteers from Guatemala City, however, show a marked shift in 87 Sr/86 Sr away from predicted values highlighting the potential influence of imported goods. The results here highlight the applicability of 87 Sr/86 Sr in hair to serve as a potential tool to support the identification of unknown individuals in Guatemala in a forensic context.

A technical and clinical digital approach to the altered cast technique with an intraoral scanner and polyvinyl siloxane impression material.

This technique digitalizes the clinical and laboratory steps of fabricating removable partial dentures (RPDs) with the altered cast technique. An intraoral scanner was used to capture the mandibular Kennedy class II partially edentulous arch. An RPD framework was fabricated digitally and then combined with a custom tray with a wax occlusal rim. A conventional polyvinyl siloxane altered cast impression was made and then digitalized both intraorally and extraorally, followed by a digital interocclusal record. The resulting scan was modified to produce an additively manufactured cast. The teeth and gingival components were then designed and fabricated with a combination of additive and subtractive manufacturing, followed by the conventional acrylic resin pour technique. The definitive prosthesis was completed with minimal conventional techniques and without the use of gypsum, prefabricated teeth, or a physical articulator. The technique reduces the number of appointments and achieves the functional extension of the prosthesis through border molding, which is not possible with intraoral scanning.

Changes in Spina Bifida Lesion Level after Folic Acid Fortification in the US.

OBJECTIVE: To assess whether the severity of cases of spina bifida changed after the institution of mandatory folic acid fortification in the US. STUDY DESIGN: Six active population-based birth defects programs provided data on cases of spina bifida for 1992-1996 (prefortification period) and 1999-2016 (postfortification period). The programs contributed varying years of data. Case information included both a medical record verbatim text description of the spina bifida diagnosis and spina bifida codes (International Classification of Diseases, Clinical Modification, or a modified birth defects surveillance coding system). Comparing the prefortification and postfortification periods, aORs for case severity (upper-level lesions [cervical, thoracic] vs lower-level lesions [lumbar, sacral]) and prevalence ratios (PRs) were estimated. RESULTS: A total of 2593 cases of spina bifida (out of 7 816 062 live births) met the inclusion criteria, including 573 cases from the prefortification period and 2020 cases from the postfortification period. Case severity decreased by 70% (aOR, 0.30; 95% CI, 0.26-0.35) between the fortification periods. The decrease was most pronounced for non-Hispanic White mothers. Overall spina bifida prevalence declined by 23% (PR, 0.77; 95% CI, 0.71-0.85), with similar reductions seen across the early, mid, and recent postfortification periods. A statistically significant decrease in upper-level lesions occurred in the postfortification period compared with the prefortification period (PR, 0.28; 95% CI, 0.22-0.34), whereas the prevalence of lower-level lesions remained relatively similar (PR, 0.94; 95% CI, 0.84-1.05). CONCLUSIONS: The severity of spina bifida cases decreased after mandatory folic acid fortification in the US. Further examination is warranted to better understand the potential effect of folic acid on spina bifida severity.

The forest effect: Biosphere 87Sr/86Sr shifts due to changing land use and the implications for migration studies.

This study documents a transect of 87Sr/86Sr values from a variety of plant, soil and rock samples across the ancient woodland of the Sherwood Forest National Nature Reserve (SFNNR) and into adjoining farmland in Britain. All samples were collected from the Triassic Sherwood Sandstone Group. A shift of +0.0037 in 87Sr/86Sr values is observed between the average plant from the biosphere of the ancient forest and that of the farmland. This shift is caused by the leaf litter accumulation in the forest, through time, leading to soil acidity that leaches out the carbonate component of the soil. This results in the forest floor soil reflecting only the silicate minerals from the original Sandstone rock formation. We have named this process "the forest effect". Rock samples from boreholes of the Sherwood Sandstone Group, as well as water samples from aquifers and mineral waters from previous studies, further indicate that the change in biosphere 87Sr/86Sr is a result of the wooded environment rather than the anthropological addition of lime to farmland. The extent of the forest effect will vary with differing lithologies with the most susceptible terrains being those with mixed carbonate-silicate composition, and it may be sufficient to impact the interpretation of animal and human 87Sr/86Sr in studies of mobility and migration. The model provides an opportunity to understand and assess food procurement strategies and animal management practices in the past, as well as the interaction of humans with their natural environment.

Trueness assessment of additively manufactured maxillary complete denture bases produced at different orientations.

STATEMENT OF PROBLEM: The trueness of the intaglio surface of an additively manufactured maxillary denture base may be influenced by the build orientation and the inclusion of support struts. PURPOSE: The purpose of this in vitro study was to compare the trueness of a photopolymer additively manufactured maxillary complete denture base created at different orientations with different support strut designs. Optimizing the build is critical for adopting best practice when fabricating maxillary complete dentures through additive manufacturing techniques. MATERIAL AND METHODS: Denture bases (N=70) were additively manufactured at 5 different build orientations (0-, 15-, 45-, 60-, and 90-degrees) with 10 specimens per orientation. Another 2 groups of 10 were manufactured by using the optimal printing orientation with and without support struts. The denture bases were scanned after storage in artificial saliva at 37 °C, and the scan data were analyzed with a 3D metrology software program. Statistical differences were determined with 1-way analysis of variance (ANOVA) and the Kruskal-Wallis test (α=.05). Color deviation heat maps were used to determine areas of clinically significant dimensional errors. RESULTS: Significant differences were found among groups for positive mean deviation (F=44.09, P<.001), negative mean deviation (F=11.69, P<.001), and root mean square deviation (F=17.11, P<.001) for the different orientations. One-way ANOVA revealed significant differences with the use of support struts in relation to negative mean deviation (F=3.857, P<.001) and RMSE (F=11.215, P<.001) and positive mean deviation (Kruskal-Wallis H=0.070, P=.007). The color deviation maps showed that a 45- to 90-degree print orientation was truest overall and that the addition of support struts to the cameo and intaglio surfaces improved the trueness of the maxillary denture bases. CONCLUSIONS: The build orientation and inclusion of support struts influenced the accuracy of the intaglio surface of additively manufactured maxillary denture bases. A 45- to 90-degree build orientation with support struts on the cameo and intaglio surfaces resulted in the truest denture base.