Cooperative epithelial phagocytosis enables error correction in the early embryo.

Errors in early embryogenesis are a cause of sporadic cell death and developmental failure1,2. Phagocytic activity has a central role in scavenging apoptotic cells in differentiated tissues3-6. However, how apoptotic cells are cleared in the blastula embryo in the absence of specialized immune cells remains unknown. Here we show that the surface epithelium of zebrafish and mouse embryos, which is the first tissue formed during vertebrate development, performs efficient phagocytic clearance of apoptotic cells through phosphatidylserine-mediated target recognition. Quantitative four-dimensional in vivo imaging analyses reveal a collective epithelial clearance mechanism that is based on mechanical cooperation by two types of Rac1-dependent basal epithelial protrusions. The first type of protrusion, phagocytic cups, mediates apoptotic target uptake. The second, a previously undescribed type of fast and extended actin-based protrusion that we call 'epithelial arms', promotes the rapid dispersal of apoptotic targets through Arp2/3-dependent mechanical pushing. On the basis of experimental data and modelling, we show that mechanical load-sharing enables the long-range cooperative uptake of apoptotic cells by multiple epithelial cells. This optimizes the efficiency of tissue clearance by extending the limited spatial exploration range and local uptake capacity of non-motile epithelial cells. Our findings show that epithelial tissue clearance facilitates error correction that is relevant to the developmental robustness and survival of the embryo, revealing the presence of an innate immune function in the earliest stages of embryonic development.

Tooth loss and dementia amongst older adults residing in long-term care facilities in Vancouver: A case-control study.

OBJECTIVE: The purpose of this case-control study was to determine the association between dementia and the number of missing teeth, functional occlusal units and denture use in older adults residing in Long-Term Care (LTC) facilities. BACKGROUND: Many studies have shown an association between dementia and tooth loss. However, few studies with a large sample size have been reported describing the relationship between dementia and the number of missing teeth, remaining teeth and functional occlusal units. METHODS: An oral health assessment database of 2160 older adults admitted to LTC facilities in Vancouver, Canada, between 2015-2019 was utilised. Participants with a diagnosis of dementia in their medical records (N = 1174) were compared to those without dementia (N = 986). Multiple logistic regression analysis was used to explore a potential association between the number of missing teeth, functional occlusal units and the use of dentures and dementia. RESULTS: The number of remaining teeth (OR = 1.0, 95% Confidence Interval = 1.0-1.0; P = .054) and number of functional occlusal units (OR = 1.0, 95% CI = 1.0-1.0; P = .059) were not associated with dementia after adjusting for age, sex, oral self-care and systemic conditions. Denture use (OR = 1.1, 95% CI = 0.5-2.4; P = .790) was not associated with dementia in edentulous patients. CONCLUSION: There was no association between dementia and the number of remaining teeth, functional occlusal units or wearing dentures.

Comparison of digital and conventional methods of fit evaluation of partial removable dental prosthesis frameworks fabricated by selective laser melting.

STATEMENT OF PROBLEM: Three-dimensional (3D) printing technology may improve the fit of partial removable dental prosthesis frameworks made by selective laser melting. Conventionally, the gaps between definitive casts and prostheses are evaluated by using clinical replicas, but digital evaluations may provide a better alternative. PURPOSE: The purpose of this in vitro study was to compare digital and conventional methods for evaluating the fit of partial removable dental prosthesis frameworks made by selective laser melting. MATERIAL AND METHODS: A printed resin definitive cast representing a Kennedy class II modification 2 design with 5 reference markers was made from a dentiform cast. Twelve cobalt-chromium partial removable dental prosthesis frameworks were fabricated by selective laser melting on this definitive cast with a digital design software program. The gaps between the frameworks and the cast were assessed by using the clinical replica method with a silicone impression material and measuring the thickness at each marker with calipers. Digital casts of each framework and the definitive cast were scanned and then registered with the CloudCompare software program to measure 3D gaps at the 5 reference markers and 3 occlusal rests. The results were analyzed individually for each technique by 1-way analysis of variance (ANOVA) with post hoc Bonferroni tests (α=.05). RESULTS: For clinical registration, the mean gap between the frameworks and definitive cast was 13.9 ±7.6 µm. For digital registration, the root mean square gap was 70.7 ±24.2 µm. Statistically significant differences among the gaps for different markers were found for both approaches (P<.05). There were no significant differences among the gaps between the different frameworks. In both situations, the gap measurements were below the 300-µm clinically acceptable standard. CONCLUSIONS: Both registration methods determined whether the fit of a framework fabricated by selective laser melting was within a clinically acceptable standard. The differences in the values produced most likely arose from the different registration methods.

Impact of the COVID-19 pandemic on the University of British Columbia Geriatric Dentistry Program: Clinical education and service.

BACKGROUND AND OBJECTIVE: In Canada, the COVID-19 pandemic was associated with significant morbidity and mortality in older adults, particularly those in long-term care (LTC). Access to oral health services was limited during the pandemic due to public health restrictions. The aim of this paper was to describe the impact of the pandemic on the clinical education and service of the University of British Columbia (UBC) Geriatric Dentistry Program (GDP), which provides care to LTC residents. METHODS: Data were collected from UBC GDP AxiUm dental software records, including number of dental appointments in 2019 and 2020. Data on revenue in 2019 and 2020 based on clinical production were collected through financial summary reports. Data on the number of educational rotations were collected from summary reports from scheduling software. RESULTS: In 2020, significant reductions in clinical service, revenue, and productivity were observed in the UBC GDP relative to 2019. The number of GDP appointments for June-December 2020 was lower by 68%. The clinical productivity reduced by 67% for the same period. Expenses were slightly reduced. The overall number of LTC clinical rotations for students were only slightly lower for undergraduate students in 2020 than in 2019, and it increased for graduate students. CONCLUSION: The COVID-19 pandemic and associated public health restrictions had a negative impact on the clinical service and productivity of the UBC GDP in 2020 relative to 2019. However, clinical educational rotations to LTC were slightly increased in 2020 relative to 2019. Dental care for LTC residents can be provided if rigorous administrative controls, engineering controls and personal protective equipment are employed.

Clinical Oral Disorders in Adults Screening Protocol (CODA-SP) from the 2019 Vancouver IADR Consensus Symposium.

BACKGROUND: The Clinical Oral Disorder in Elders (CODE) index was proposed in 1999 to assess the oral health status and treatment needs of older people who typically were edentate or had few natural teeth. Since then, more people are retaining natural teeth into old age and have oral disorders similar to younger adults. In addition, there has been further guidance on screening for disease that includes changes to the clinical indicators of several oral disorders and greater sensitivity to people's concerns about their oral health and care needs. METHODS: Experts in dental geriatrics assembled at a satellite symposium of the International Association of Dental Research in June 2019 to revise the objectives and content of the CODE index. Before the symposium, 139 registrants were asked for comments on the CODE index, and 11 content experts summarised current evidence and assembled reference lists of relevant information on each indicator. The reference lists provided the base for a narrative review of relevant evidence supplemented by reference tracking and direct searches of selected literature for additional evidence. RESULTS: Analysis of the evidence by consensus of the experts produced the Clinical Oral Disorders in Adults Screening Protocol (CODA-SP). CONCLUSIONS: The CODA-SP encompasses multiple domains of physical and subjective indicators with weighted severity scores. Field tests are required now to validate its effectiveness and utility in oral healthcare services, outcomes and infrastructure.

The effect of overnight storage conditions on complete denture colonization by Candida albicans and dimensional stability: A systematic review.

STATEMENT OF PROBLEM: Overnight removal of complete dentures is recommended to reduce the incidence of denture stomatitis. The effect of overnight storage conditions is unclear. PURPOSE: The purpose of this systematic review was to assess the effect of overnight storage conditions on complete denture colonization by Candida albicans and to explore the effect of overnight storage conditions on the dimensional stability of complete dentures. MATERIAL AND METHODS: Two electronic databases were searched through to November 2018. The terms "denture*", "dental prosthes*", "acrylic resin*", "storage", "nighttime", "overnight", "wet", "dry", "water*", and "solution" were chosen. Articles meeting the inclusion criteria were selected. For both research questions, studies that did not store the dentures overnight or for a minimum of 8 hours were excluded. For the primary research question, studies that were not randomized controlled studies or comparative studies were excluded. RESULTS: The database search strategy resulted in a total of 159 potential studies. After screening titles and abstracts and applying the inclusion and exclusion criteria, 6 studies were retrieved for a full-text assessment. Hand searching was also performed. Four studies were included in the systematic review for the primary research question. Three studies were included for the secondary research question. A meta-analysis could not be performed because of variation in study design. CONCLUSIONS: Cleaning of dentures before overnight storage helps reduce C. albicans colonization. If the dentures are not cleaned, the use of an alkaline peroxide-based cleaning tablet should be considered. Alternately, overnight dry storage is an option for reducing C. albicans colonization, with clinically insignificant changes to the dimensions of the complete denture. Storing dentures in water alone may promote C. albicans colonization.

Clinical accuracy and reproducibility of virtual interocclusal records.

STATEMENT OF PROBLEM: Although in vitro studies have investigated the accuracy of virtual interocclusal records, clinical research on their ability to register virtual dental casts accurately is lacking. PURPOSE: The purpose of this clinical study was to evaluate the accuracy and reproducibility of the virtual interocclusal records of an intraoral scanning system compared with conventional polyvinyl siloxane (PVS) interocclusal records. MATERIAL AND METHODS: Three conventional interocclusal records followed by 3 virtual interocclusal records per side per participant were made in 10 participants. Three sites of close proximity (SCP) and 3 sites of clearance (SC) per side per participant were identified on the transilluminated conventional interocclusal PVS records for a total of 60 SCP and SC. The presence or absence of these sites on the virtual interocclusal records was analyzed by using an independent software program. RESULTS: The sensitivity for correct identification in the virtual interocclusal record was 87%, and its specificity was 95%. The positive predictive value was 95%, and the negative predictive value was 88%. For reproducibility, 74% of the SCP were detected consistently for all 3 repeated scans, and 92% of the SCs were identified accurately. CONCLUSIONS: The accuracy of virtual interocclusal records in identifying interocclusal contacts is clinically acceptable. However, the method tends to miss interocclusal contacts rather than introducing false ones and can result in perforations between the opposing virtual casts. Repeated buccal occlusal scans made of the same side showed fair reproducibility, and this aspect would benefit from further investigation.

Dimensional Changes of Yttria-stabilized Zirconia under Different Preparation Designs and Sintering Protocols.

PURPOSE: To evaluate the linear and volumetric dimensional changes that occur throughout the fabrication process of monolithic 4.5-6% yttria-stabilized zirconia copings under the influence of different preparation designs and two sintering protocols. MATERIALS AND METHODS: A titanium master die was fabricated using Atlantis core file implant-abutment. Six copings were designed virtually according to different finish line offsets and coping thicknesses, with four equidistant occlusal posts for linear measurements. Zirconia copings were milled using IPS e.max ZirCAD LT zirconia blanks. The experimental groups according to the coping designs were the following: G1: 0.5 mm finish line offset, 0.5 mm thickness; G2: 0.5 mm finish line offset, 1.0 mm thickness; G3: 0.5 mm finish line offset, 1.5 mm thickness; G4: 1.2 mm finish line offset, 0.5 mm thickness; G5: 1.2 mm finish line offset, 1.0 mm thickness; G6: 1.2 mm finish line offset, 1.5 mm thickness. Six samples per group were sintered by standard sintering (SS) and the other six by fast sintering (FS). Linear and volumetric measurements were taken at the three fabrication stages (virtual design, milling stage, and sintering) by using an intraoral scanner and imported as the .stl file to Meshmixer software for analysis. Statistical analysis was performed by a linear mixed effect model via statistical software R (R Core team, 2018). RESULTS: There was a significant interaction between the coping design group, stage of fabrication and sintering protocol on the linear (F = 4.451, p < 0.001) and volumetric (F = 2.716; p < 0.001) dimensional changes. Standard sintering G1 showed the smallest linear and dimensional changes among the groups compared to the reference design. Sintered copings had shrunk on average 1.32% within SS and 1.54% within FS linearly and 3.82% within SS and 3.90% within FS volumetrically compared to the initial design parameters. CONCLUSION: The linear and volumetric dimensional changes did not differ significantly between standard and fast sintering protocols, and the preparation designs had more influence on the dimensional changes compared to sintering protocols.

Changes in Oral Health and Treatment Needs for Elderly Residents of Long-Term Care Facilities Over 10 Years.

PURPOSE: This study aimed to examine the oral health status of seniors residing in Providence Health Care (PHC) long-term care facilities in 2002 and 2012. METHODS: Staff dentists with the University of British Columbia Geriatric Dentistry Program made a complete oral health assessment of 799 elderly residents of 7 long-term care PHC facilities in 2002 and 381 residents in the 5 remaining PHC facilities in 2012. The 2012 data were divided into those for 275 residents who had received treatment in previous years and 106 new residents. All consenting residents were examined by dentists using the clinical oral disorder in elders (CODE) index detailing their medical and oral health status and medications. On completion of the oral health assessment, the dentist documented the need for specific dental treatment and reassessment. RESULTS: Comparing the cohorts from 2002 and 2012, the mean age of the residents who had CODE assessments increased from 85 years to 86 years, the proportion of men increased from 31% to 35%, the mean number of medical conditions per resident remained unchanged (2.6 to 2.5), but the mean number of prescribed medications has increased from 4.0 to 4.6. The percentage of residents with natural teeth increased from 56% to 76%. The proportion of edentulous residents recommended for denture-related treatment decreased from 21% to 10%. The 106 new residents in 2012 had higher treatment needs than the 275 original residents, but fewer required extractions than in 2002. Although the mean number of teeth per resident examined increased from 14.6 to 17.4 over the study period, the need for restorations remained at 20%, and the need for extraction of teeth decreased from 22% to 6%. The proportion of residents with healthy periodontium increased from 14% to 21%, but the need for dental hygiene services increased from 43% to 80%. CONCLUSIONS: The profile of long-term care residents who consented to an oral health assessment changed over the first decade of the new millennium, with an increase in mean age and number of prescribed medications, number of retained natural teeth and the need for dental hygiene services, but a decrease in the need for extractions.

The influence of altering sintering protocols on the optical and mechanical properties of zirconia: A review.

OBJECTIVE: As a result of advancements in chairside technology and speed sintering techniques and increased esthetic demands of patients, efforts have been made to produce monolithic zirconia restorations that are highly translucent, strong, and dense. While methods for processing zirconia are well known, there is a tendency to modify the process parameters with the aim of decreasing the overall processing time and, in particular, the sintering time. This review provides clinicians with scientific evidence of the effects of altering sintering parameters used for dental zirconia on its microstructure, phase transformation, and mechanical and optical properties. MATERIALS AND METHODS: A systematic search of Embase and Medline using Boolean operators was performed to locate relevant articles. RESULTS: Eleven articles were selected for this review. The following characteristics of monolithic zirconia have been confirmed to be affected by alterations in sintering: the microstructure, mechanical properties, optical properties, wear behavior, and low thermal degradation. CONCLUSIONS: The alteration of sintering parameters has been found to alter the grain size, wear behavior, and translucency of zirconia. There is a lack of clinical studies that investigate the influence of altering sintering parameters or methods on the clinical performance of monolithic zirconia restorations. CLINICAL SIGNIFICANCE: Alteration of sintering parameters alters the microstructural, mechanical, and optical properties of zirconia. This will consequently impact the clinical performance of zirconia prostheses. Future clinical investigations are encouraged to support these in vitro findings.

Marginal Discrepancies of Monolithic Zirconia Crowns: The Influence of Preparation Designs and Sintering Techniques.

PURPOSE: The marginal fit is an essential component for the clinical success of prosthodontic restorations. The aim of this study was to investigate the influence of different abutment finish line widths and crown thicknesses on the marginal fit of zirconia crowns fabricated using either standard or fast sintering protocols. MATERIALS AND METHODS: Six titanium abutments were fabricated for receiving zirconia molar crowns. Crowns were designed virtually and milled from partially sintered zirconia blanks and divided into 12 groups (n = 10/group). Crowns in groups 1 to 6 were sintered by standard sintering, while those in groups 7 to 12 were sintered by fast sintering. Groups were further categorized according to abutment finish line and crown thickness: G1/G7 (0.5 mm chamfer, 0.8 mm thick); G2/G8 (0.5 mm chamfer, 1.5 mm thick); G3/G9 (1.0 mm chamfer, 0.8 mm thick); G4/10 (1.0 mm chamfer, 1.5 mm thick); G5/G11 (1.2 mm chamfer, 0.8 mm thick); G6/G12 (1.2 mm chamfer, 1.5 mm thick). The marginal gaps were assessed at 8 locations using digital microscopy. The linear mixed effect model analysis was performed at a significance level of 0.05. RESULTS: All vertical marginal gaps were within the clinically acceptable range (∼11-52 µm). G8 (FS, 0.5 mm chamfer, 1.5 mm thick) demonstrated the largest gaps (47.95 µm, 95% CI: 44.57-51.23), whereas G3 (SS, 1.0 mm chamfer, 0.8 thick) had the smallest marginal gap (14.43 µm, 95% CI: 11.15-17.71). A linear mixed effect models showed significant differences for the interaction between finish line × crown thickness × sintering (F = 18.96, p < 0.001). The lingual surfaces showed the largest gaps in both sintering protocols, while the mesial and mesiobuccal surfaces demonstrated the smallest gaps. CONCLUSIONS: There was a significant interaction between finish line widths, crown thickness, and sintering protocol on the marginal gaps in both sintering protocols; 1.0 mm finish line preparations with either 0.8 mm or 1.5 mm occlusal reduction had better marginal fit in both sintering protocols compared to 0.5 mm or 1.2 mm finish lines. Smaller marginal discrepancies were observed for standard sintering crowns with a 0.5 mm finish line and 1.5 mm occlusal reduction. Conservative occlusal reduction should be accompanied with a 1.2 mm finish line to obtain better marginal fit for full-contoured zirconia crowns.

Molecular signatures of plastic phenotypes in two eusocial insect species with simple societies.

Phenotypic plasticity is important in adaptation and shapes the evolution of organisms. However, we understand little about what aspects of the genome are important in facilitating plasticity. Eusocial insect societies produce plastic phenotypes from the same genome, as reproductives (queens) and nonreproductives (workers). The greatest plasticity is found in the simple eusocial insect societies in which individuals retain the ability to switch between reproductive and nonreproductive phenotypes as adults. We lack comprehensive data on the molecular basis of plastic phenotypes. Here, we sequenced genomes, microRNAs (miRNAs), and multiple transcriptomes and methylomes from individual brains in a wasp (Polistes canadensis) and an ant (Dinoponera quadriceps) that live in simple eusocial societies. In both species, we found few differences between phenotypes at the transcriptional level, with little functional specialization, and no evidence that phenotype-specific gene expression is driven by DNA methylation or miRNAs. Instead, phenotypic differentiation was defined more subtly by nonrandom transcriptional network organization, with roles in these networks for both conserved and taxon-restricted genes. The general lack of highly methylated regions or methylome patterning in both species may be an important mechanism for achieving plasticity among phenotypes during adulthood. These findings define previously unidentified hypotheses on the genomic processes that facilitate plasticity and suggest that the molecular hallmarks of social behavior are likely to differ with the level of social complexity.

The accuracy of virtual interocclusal registration during intraoral scanning.

STATEMENT OF PROBLEM: Evidence on the accuracy and reproducibility of the virtual interocclusal registration procedure and recommendations as to how to make a virtual interocclusal record are lacking. PURPOSE: The purpose of this in vitro study was to assess whether virtual interocclusal registration records made at different locations around the arch affect the alignment of virtual casts, and to assess whether quadrant and complete arch scans have different effects on cast alignment when they are articulated with virtual interocclusal records. MATERIAL AND METHODS: Three sites of close proximity (SCPs) and 3 sites of clearance (SCs) were identified in each sextant of mounted zirconia master models. The SCPs and SCs were confirmed by using shimstock foil and the transillumination of an interocclusal impression. Complete-arch and quadrant scans of the master models were made with an intraoral scanner and registered with different virtual interocclusal registration records. The SCPs and SCs indicated by the scanner's software and by independent software were compared according to the sensitivity, specificity, and predictive values of each method. RESULTS: Changed locations of SCPs were found depending on the location of the virtual interocclusal registration record. The intraoral scanner's software contacts had a higher sensitivity of 92.86% and a negative predictive value of 84.21% than the contacts revealed by the independent software that exhibited a sensitivity of 69.05% and a negative predictive value of 70.45%. However, the intraoral scanner software had a lower specificity of 41.03% and a positive predictive value of 62.90% compared with the independent software, which exhibited a specificity of 79.49% and a positive predictive value of 78.38%. The quadrant scans had a higher sensitivity than did the complete-arch scans. CONCLUSIONS: Different occlusal contacts are obtained from interocclusal registration scans in different segments of the dental arch. The difference is more obvious in complete-arch scans, where a tilting effect toward the site of the interocclusal registration scan was observed. Occlusal contacts obtained from interocclusal registration scans for quadrant scans had a higher sensitivity than did those for complete-arch scans.

Marginal Fit of Lithium Disilicate Crowns Fabricated Using Conventional and Digital Methodology: A Three-Dimensional Analysis.

PURPOSE: To compare the marginal fit of lithium disilicate (LD) crowns fabricated with digital impression and manufacturing (DD), digital impression and traditional pressed manufacturing (DP), and traditional impression and manufacturing (TP). MATERIALS AND METHODS: Tooth #15 was prepared for all-ceramic crowns on an ivorine typodont. There were 45 LD crowns fabricated using three techniques: DD, DP, and TP. Microcomputed tomography (micro-CT) was used to assess the 2D and 3D marginal fit of crowns in all three groups. The 2D vertical marginal gap (MG) measurements were done at 20 systematically selected points/crown, while the 3D measurements represented the 3D volume of the gap measured circumferentially at the crown margin. Frequencies of different marginal discrepancies were also recorded, including overextension (OE), underextension (UE), and marginal chipping. Crowns with vertical MG > 120 µm at more than five points were considered unacceptable and were rejected. The results were analyzed by one-way ANOVA with Scheffe post hoc test (α = 0.05). RESULTS: DD crowns demonstrated significantly smaller mean vertical MG (33.3 ± 19.99 µm) compared to DP (54.08 ± 32.34 µm) and TP (51.88 ± 35.34 µm) crowns. Similarly, MG volume was significantly lower in the DD group (3.32 ± 0.58 mm3 ) compared to TP group (4.16 ± 0.59 mm3 ). The mean MG volume for the DP group (3.55 ± 0.78 mm3 ) was not significantly different from the other groups. The occurrence of underextension error was higher in DP (6.25%) and TP (5.4%) than in DD (0.33%) group, while overextension was more frequent in DD (37.67%) than in TP (28.85%) and DP (18.75%) groups. Overall, 4 out of 45 crowns fabricated were deemed unacceptable based on the vertical MG measurements (three in TP group and one in DP group; all crowns in DD group were deemed acceptable). CONCLUSION: The results suggested that digital impression and CAD/CAM technology is a suitable, better alternative to traditional impression and manufacturing.

How do we enhance undergraduate healthcare education in dementia? A review of the role of innovative approaches and development of the Time for Dementia Programme.

OBJECTIVES: Traditional healthcare education, delivered through a series of time-limited clinical placements, often fails to deliver an understanding of the experiences of those with long-term conditions, a growing issue for healthcare systems. Responses include longitudinal integrated clerkships and senior mentor programmes allowing students' longer placements, continuity of contact and opportunities to learn about chronic illness and patient experience. We review their development and delivery in dementia and present the Time for Dementia (TFD) Programme, a novel 2-year interdisciplinary educational programme. DESIGN: The study design involves a scoping review of enhanced placements in dementia for healthcare professionals in training including longitudinal integrated clerkships and senior mentor programmes and a case study of the development of TFD and its evaluation. RESULTS: Eight enhanced programmes in dementia were identified and seven in the USA. None were compulsory and all lasted 12 months. All reported positive impact from case study designs but data quality was weak. Building on these, TFD was developed in partnership between the Alzheimer's Society, universities and NHS and made a core part of the curriculum for medical, nursing and paramedic students. Students visit a person with dementia and their family in pairs for 2 h every 3 months for 2 years. They follow a semi-structured interaction guide focusing on experiences of illness and services and complete reflective appraisals. CONCLUSIONS: We need interprofessional undergraduate healthcare education that enables future healthcare professionals to be able to understand and manage the people with the long-term conditions who current systems often fail. TFD is designed to help address this need. © 2016 The Authors. International Journal of Geriatric Psychiatry Published by John Wiley & Sons Ltd.

Evolutionary origin and functional divergence of totipotent cell homeobox genes in eutherian mammals.

BACKGROUND: A central goal of evolutionary biology is to link genomic change to phenotypic evolution. The origin of new transcription factors is a special case of genomic evolution since it brings opportunities for novel regulatory interactions and potentially the emergence of new biological properties. RESULTS: We demonstrate that a group of four homeobox gene families (Argfx, Leutx, Dprx, Tprx), plus a gene newly described here (Pargfx), arose by tandem gene duplication from the retinal-expressed Crx gene, followed by asymmetric sequence evolution. We show these genes arose as part of repeated gene gain and loss events on a dynamic chromosomal region in the stem lineage of placental mammals, on the forerunner of human chromosome 19. The human orthologues of these genes are expressed specifically in early embryo totipotent cells, peaking from 8-cell to morula, prior to cell fate restrictions; cow orthologues have similar expression. To examine biological roles, we used ectopic gene expression in cultured human cells followed by high-throughput RNA-seq and uncovered extensive transcriptional remodelling driven by three of the genes. Comparison to transcriptional profiles of early human embryos suggest roles in activating and repressing a set of developmentally-important genes that spike at 8-cell to morula, rather than a general role in genome activation. CONCLUSIONS: We conclude that a dynamic chromosome region spawned a set of evolutionarily new homeobox genes, the ETCHbox genes, specifically in eutherian mammals. After these genes diverged from the parental Crx gene, we argue they were recruited for roles in the preimplantation embryo including activation of genes at the 8-cell stage and repression after morula. We propose these new homeobox gene roles permitted fine-tuning of cell fate decisions necessary for specification and function of embryonic and extra-embryonic tissues utilised in mammalian development and pregnancy.

Case for implant platform unswitching.

Platform switching was introduced to reduce marginal bone loss and therefore maintain the gingival architecture, leading to a more favorable esthetic result. In the patient presented, recession had resulted in the exposure of the implant neck and threads; this was managed with a custom-made additional prosthetic component. The result, although not ideal esthetically, provided an implant abutment interface that was easier for the patient to clean.

Assessment of the Internal Fit of Lithium Disilicate Crowns Using Micro-CT.

PURPOSE: The aim of this study was to compare the internal fit of lithium disilicate crowns fabricated using digital technology with those fabricated by conventional means. MATERIALS AND METHODS: Forty-five lithium disilicate crowns were fabricated: 15 using digital impression and computer-aided design/computer-aided machining technique (group 1), 15 from the same digital impressions, but using a conventional die and laboratory fabrication process (group 2), and 15 using a conventional poly (vinyl siloxane) (PVS) impression and laboratory fabrication process (group 3). Tooth #15 was prepared for all-ceramic restoration on an ivorine typodont, which was digitized and a replica milled in zirconia to serve as master model. The master zirconia model was used for the impression procedures. Duplicate dies of the master zirconia die were made in polyurethane, enabling the internal fit of each crown to be evaluated using X-ray microcomputed tomography. The total volume of the internal space between the crown and die, the mean and maximum thickness of this space, and the percentage of the space that was at or below 120 µm thickness was calculated for each group and statistically tested for significant difference using one-way ANOVA, with post hoc Scheffé analysis. RESULTS: Group 1 crowns resulted in a smaller volume of internal space (12.49 ± 1.50 mm(3)) compared to group 2 (15.40 ± 2.59 mm(3) ) and to those of group 3 (18.01 ± 2.44 mm(3)). The mean thickness of the internal space for group 1 (0.16 ± 0.01 mm) and for group 2 (0.17 ± 0.03 mm) was significantly lower than that of group 3 (0.21 ± 0.03 mm). The average percentage of the internal space of a thickness of 120 µm and below was different between the three groups: 46.73 ± 5.66% for group 1, 37.08 ± 17.69% for group 2, and 22.89 ± 9.72% for group 3. Three-dimensional renderings of the internal space were also created. CONCLUSIONS: The results of this study suggested that pressed and milled IPS e. max crowns from LAVA COS digital impressions had a better internal fit to the prepared tooth than pressed IPS e.max crowns from PVS impressions in terms of total volume of internal space, average thickness of internal space, and percentage of internal space at or below 120 µm.

Incidence of dental caries among susceptible community-dwelling older adults using fluoride toothpaste: 2-year follow-up study.

OBJECTIVES: To explore reasons for the underuse of dental services covered by a government-funded program in Alberta. METHODS: In 2011, a survey questionnaire was sent to 4000 randomly selected clients of the Alberta Child Health Benefit and the Alberta Adult Health Benefit programs. Only respondents with children were included in the analysis. Reasons were explored among those who indicated that their children did not receive any dental services in the year before the survey. Difficulties faced by those who reported receiving at least 1 dental service were also noted. RESULTS: Among 795 respondents, 597 had at least 1 child. A total of 1303 children aged 1-19 years (mean age 11.79 years, standard deviation 4.2) were included in the analysis. Of these children, 443 (34.0%) had not received any covered dental services; the most common reason (50.7%) was no perceived need (interpreted from the replies "my child was too young" or "had no dental problems") followed by perceived insufficient coverage (38.6%). The most common challenge reported by dental care users was also insufficient coverage (44.9%). About 57% of parents were aware that annual fluoride application was covered by the program; however, only 34.3% of their children received fluoride and 14.2% had sealants. CONCLUSIONS: Low-income families underuse available dental benefits for children. Perceived need seems to be the primary determinant of use. Parental awareness about the coverage does not seem to promote the use of preventive measures for young children.

A comparison of the marginal fit of crowns fabricated with digital and conventional methods.

STATEMENT OF PROBLEM: Little evidence is available with regard to the marginal fit of crowns fabricated with digital impressions and computer-aided design/computer-aided manufacturing technology in comparison with crowns fabricated from conventional techniques. PURPOSE: The purpose of this study was to determine and compare the marginal fit of crowns fabricated with digital and conventional methods. MATERIAL AND METHODS: The maxillary right second premolar was prepared for a ceramic crown in a typodont. The typodont was then digitized with a laboratory scanner, and the digital file was used to mill a replica of the maxillary arch from a monolithic block of yttria-stabilized zirconia to serve as the master model. Digital impressions of the prepared maxillary right second premolar were recorded with a scanning unit. Scan files were exported as .STL files and sent by e-mail to a dental laboratory. The files were input into a digital design workflow for digital articulation, digital waxing, and design of the definitive crown. Fifteen crowns were produced by milling computer-aided designed lithium disilicate glass ceramic blocks with a 5-axis milling. Fifteen lithium disilicate glass ceramic crowns were produced with a conventional impression and a laboratory fabrication method. The original zirconia die was removed from the zirconia master model to evaluate the crown margins. Circumferential marginal gap measurements were made at 8 measurement locations: mescal, distal, buccal, palatal and associated line angles (mesiobuccal, mesiolingual, distobuccal, and distolingual). Measurements were made to determine the vertical component of the marginal gap according to the definition of marginal fit. RESULTS: A total of 240 images (2 groups, 15 crowns per group, 8 sites per crown) were recorded and measured. The overall mean ±SD vertical gap measurement for the digitally made crowns was 48 ±25 µm, which was significantly smaller than that for the conventionally made crowns (74 ±47 µm). CONCLUSION: The fully digital fabrication method provided better margin fit than the conventional method.