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BACKGROUND: Ameloblastin (AMBN) is a secreted matrix protein that is critical for the formation of dental enamel and is enamel-specific with respect to its essential functions. Biallelic AMBN defects cause non-syndromic autosomal recessive amelogenesis imperfecta. Homozygous Ambn mutant mice expressing an internally truncated AMBN protein deposit only a soft mineral crust on the surface of dentin. METHODS: We characterized a family with hypoplastic amelogenesis imperfecta caused by AMBN compound heterozygous mutations (c.1061T>C; p.Leu354Pro/ c.1340C>T; p.Pro447Leu). We generated and characterized Ambn knockout/NLS-lacZ (AmbnlacZ/lacZ ) knockin mice. RESULTS: No AMBN protein was detected using immunohistochemistry in null mice. ß-galactosidase activity was specific for ameloblasts in incisors and molars, and islands of cells along developing molar roots. AmbnlacZ/lacZ 7-week incisors and unerupted (D14) first molars showed extreme enamel surface roughness. No abnormalities were observed in dentin mineralization or in nondental tissues. Ameloblasts in the AmbnlacZ/lacZ mice were unable to initiate appositional growth and started to degenerate and deposit ectopic mineral. No layer of initial enamel ribbons formed in the AmbnlacZ/lacZ mice, but pockets of amelogenin accumulated on the dentin surface along the ameloblast distal membrane and within the enamel organ epithelia (EOE). NLS-lacZ signal was positive in the epididymis and nasal epithelium, but negative in ovary, oviduct, uterus, prostate, seminal vesicles, testis, submandibular salivary gland, kidney, liver, bladder, and bone, even after 15 hr of incubation with X-gal. CONCLUSIONS: Ameloblastin is critical for the initiation of enamel ribbon formation, and its absence results in pathological mineralization within the enamel organ epithelia.

Operationalizing faculty contributions in ways that align with organizational mission can be difficult, particularly when monetizing effort. Conventional compensation methods may result in faculty effort going undefined, resulting in more subjectivity in recognition and compensation. Inequities lead to faculty marginalization, fragmentation, decreased motivation, and attrition. Dental faculty retirements are expected to increase, as 81% of men and 19% of women faculty aged 60 years and older in 2015-2016. We present opposing perspectives on the use of educational value units (EVUs) in academic dentistry. The first viewpoint articulates that such models improve recruitment and retention by objectifying (a) faculty performance measurement, (b) academic productivity improvements, and (c) compensation determination. The counterpoint suggests EVUs are deterrents to faculty retention due to challenges with objectively quantifying performance measures, a potential inherent bias linked to gender, and the undervaluing of teaching quality or collaborative practices. [ABSTRACT FROM AUTHOR]

Research education and training in Translational Science develops and sustains a workforce to efficiently advance studies designed to improve human health. We evaluated the effectiveness of a Translational Science Training (TST) TL1 Program. Participants had significantly better publications/year, citations/year, h-index , and m-quotient than nonparticipants. Female and male participants, and participants from underrepresented and well-represented backgrounds, performed similarly on all bibliometric assessments. Finally, TST/TL1 Program participants outperformed students from other PhD programs at our institution. This analysis suggests that the TST/TL1 Program has been effective for participants, including those who are female and from underrepresented backgrounds. [ABSTRACT FROM AUTHOR]

Abstract Background The purpose of this study was to test the null hypothesis that there is no difference between the effect of (1) a 5000 ppm fluoride toothpaste, and (2) a 250 ppm fluoride mouth rinse on demineralized human dentin surfaces, against the alternative hypothesis of a difference. Findings Dentin specimens were obtained from the cervical regions of 45 extracted human third molars. Half the surface of each specimen was sealed with a self-etching adhesive system and served as the reference surface. The dentin specimens were randomly assigned to one of the three groups, 5000 ppm fluoride toothpaste (Duraphat), 250 ppm fluoride mouth rinse (Meridol) and distilled water (negative control). An intraoral appliance was made for one volunteer. In each test cycle, 15 specimens were inserted in the appliance and worn for 24 hours a day, over a period of three weeks. Once daily, the appliance was immersed in the agent being tested; either toothpaste slurry, mouth rinse or distilled water for 60 seconds. Demineralization was assessed in terms of lesion depth (μm) and mineral loss (vol. % × μm) by transversal microradiography. Data analysis was accomplished using Kolmogorov-Smirnov test and ANOVA (SPSS 12.0). Statistically significant differences for mineral loss and lesion depth were found between the toothpaste and the mouth rinse as well as between the toothpaste and the control group, but not between the mouth rinse and the control group. Conclusion Within the limitations of this study, the results suggest that treatment of demineralised dentin with a toothpaste containing 5000 ppm fluoride may considerably reduce mineral loss and lesion depth on exposed dentin.

Purpose: The aim was to determine the in vitro fracture resistance of incisors restored with veneers and full ceramic crowns compared to unrestored teeth. Materials and Methods: Seventy intact, extracted human maxillary central incisors were randomized and assigned to 7 groups (n = 10). The teeth in group 1 remained intact (control). The teeth in groups 2 to 6 were prepared and IPS Empress restorations were conditioned and bonded using an adhesive luting cement, Variolink II/Syntac (group 2: labial veneer with incisal overlap, group 3: ¾ veneer with margin in enamel, group 4: ¾ veneer with margin in dentin, group 5: crown with margin in enamel, group 6: crown with margin in dentin group 7: veneer on worn tooth. After finishing and polishing, specimens were stored in water and thermocycled for 2000 cycles between 5°C and 55°C. The maximal fracture load of the specimens (40-degree inclination) was determined using the universal testing machine (Zwick) at a constant crosshead speed (0.5 mm/min). The statistical analysis was performed using the Kruskal-Wallis test with Bonferroni correction (p < 0.05). Fracture surfaces were qualitatively analyzed by SEM. Results: All restored teeth with cervical preparation margins in enamel showed a fracture load not significantly different from the intact teeth (control). Restored teeth with cervical preparation margins in dentin showed a significantly lower fracture load. All restorations showed a fracture load far above 400 N, serving as functional reference for anterior teeth. The failures were predominantly cohesive. Conclusion: For the restoration of tooth strength, defining the finishing lines of veneers and crowns in enamel is recommended. Restorations with finishing lines in dentin resulted in significant loss of strength. Three-quarter veneers with finishing lines in enamel are functionally equal to crowns with the advantage of conserving tooth structure. [ABSTRACT FROM AUTHOR]