The Accuracy of Post and Core Fabricated with Digital Technology.

PURPOSE: To compare the accuracy of post and cores created with three different fabricating techniques: direct conventional, machine milling, and three-dimensional (3D) printing. MATERIALS AND METHODS: Thirteen extracted single root central incisors were selected. Root canal treatment and tooth preparation for crown were performed on all teeth. Post space preparation of 11 mm was created using prefabricated fiber post drill to standardize post space width and length. Root canal impressions were performed on all teeth using polyvinyl siloxane impression material. Each impression was then three dimensionally scanned using an extraoral lab scanner. The scanned impressions were used to design digital files of post and cores with 3Shape CAD software. The digitally designed post and cores were used to fabricate 3D printed and milled post and core resin patterns. The same teeth were used to fabricate post and core with conventional technique (direct duplication of root canal with resin pattern). All posts were then scanned before being invested and then cast using base metal educational alloy. The metal post and cores were tried in with sample teeth and manually adjusted until found to be clinically acceptable. The post and cores were scanned in different stages to perform digital volume measurement using Geomagic Control software to determine accuracy. Pairwise comparisons were accomplished using exact version of the sign test (α = 0.05). RESULTS: These three techniques of post and core fabrication showed different results in the various stages of fabrication. The accuracy of 3D printed resin pattern (26.89 ±11.09 mm3 ) was found to be inferior compare to milled resin pattern (28.20 ±11.41 mm3 , p = 0.0002). However, dimensional stability of the 3D printed resin pattern before and after casting (0.56 ±0.95 mm3 ) was found to be superior to milled resin pattern (0.79 ±0.89 mm3 ) and direct resin pattern (2.51 ±1.38 mm3 , p = 0.00002). All three techniques showed significant volume reduction after adjustment (p = 0.0002). In the final stage, the adjusted metal post and core fabricated with three different techniques showed no statistical different in accuracy (p = 0.15). CONCLUSION: Digitally fabricated post and cores have the same degree of accuracy as those fabricated using the gold standard direct conventional post and core technique.

Crystalline phase evolution and thermal behavior of zirconia-lanthanum aluminate ceramics produced by surface modification.

The purpose of the present work was to investigate the effect doping with lanthanum aluminate on the phase assemblage and thermal behavior of zirconia ceramics for biomedical applications. Four compositions were prepared by a surface modification route of either conventional tetragonal zirconia (3Y-TZP) or high translucency cubic-based zirconia (5Y-PSZ) to reach a nominal composition of either 0.5 wt. % (3Y-0.5LAO and 5Y-0.5LAO) or 5 wt. % of lanthanum monoaluminate (3Y-5LAO and 5Y-5LAO). Undoped powders were used as controls. DTA and XRD analyses revealed that lanthanum dizirconate crystallized in the 934°C-936°C range, while lanthanum aluminate crystallized in the 1,056°C-1,063°C range in both types of zirconias doped at the 5% level. No second phase was found in compositions doped at the 0.5% level. The a lattice parameter and the amount of the cubic phase increased in both 3Y-5LAO and 5Y-5LAO. The microstructure of the compositions doped with 5% LAO was characterized by well distributed LAO twinned crystals and sparse needle-shaped lanthanum hexaaluminate crystals. A bimodal grain size distribution was observed in 5Y-doped compositions. This was attributed to abnormal grain growth of the cubic phase, and in line with aluminum segregation at grain boundaries and the presence of second-phase LAO crystals.

Effect of crystalline phase assemblage on reliability of 3Y-TZP.

STATEMENT OF PROBLEM: Strengthening mechanisms of zirconia ceramics stabilized with 3 mol% yttria (3Y-TZP) are complex and dictated by the crystalline phase assemblage. Although their clinical performance for dental restorations has been excellent, there is evidence that framework fractures do occur and have been underreported. Meanwhile, the relationship between phase assemblage and reliability of 3Y-TZP is not properly understood. PURPOSE: The purpose of this in vitro study was to elucidate the relationship between crystalline phase assemblage and the reliability of 3Y-TZP and to calculate the associated probabilities of survival. MATERIAL AND METHODS: Disks of 3Y-TZP were prepared from cylindrical blanks and randomly assigned to 12 experimental groups (n=20 per group). Different crystalline phase assemblages were produced by either varying the sintering temperature from 1350 °C to 1600 °C and/or treating the surface by airborne-particle abrasion with 50-mm alumina particles at a pressure of 0.2 MPa for 1 minute with or without subsequent heat treatment. Crystalline phases were analyzed by standard and grazing incidence X-ray diffraction (GIXRD). The relationship between phase assemblage and reliability was determined by measuring the biaxial flexural strength (BFS) according to ISO standard 6872 and by using Weibull statistics to calculate the Weibull modulus (m), probability of survival, and maximum allowable stresses. XRD results were analyzed by ANOVA to detect statistically significant differences between groups. Adjustment for all pairwise group comparisons was made using the Tukey method (α=.05). RESULTS: Standard incidence XRD confirmed the presence of a small amount of cubic phase after sintering at 1350 °C. A cubic-derived nontransformable tetragonal t'-phase was observed at sintering temperatures of 1450 °C and above, the amount of which increased linearly. GIXRD revealed that airborne-particle abraded groups sintered at 1350 °C and 1600 °C had the highest variability in monoclinic phase fraction as a function of depth. These groups were also associated with the lowest reliability. Groups as-sintered at 1350 °C and 1600 °C had the lowest modulus (m=8.1 [0.5] and 7.0 [0.8], respectively) and probability of survival (Ps) for a maximum allowable stress of 700 MPa, while treated groups sintered at 1450 °C and 1550 °C were associated with the highest modulus (from 15.0 [1.4] to 20.9 [1.4]) and Ps (≥0.9999). The lower strength and reliability of groups sintered at 1600 °C was consistent with the presence of a significant amount of nontransformable t'-phase. The pattern of BFS results indicated that ferro-elastic domain switching was a dominant strengthening mechanism in 3Y-TZP. CONCLUSIONS: The present study first reported on the detrimental effect of the cubic-derived nontransformable t'-phase on the mechanical properties of 3Y-TZP. It was demonstrated that phase assemblage determined reliability and was directly linked to the probability of survival.

Antimicrobial efficacy of platinum-doped silver nanoparticles.

Silver nanoparticles (AgNPs) have been proposed to combat oral infection due to their efficient ionic silver (Ag+ ) release. However, concentrations required for antimicrobial efficacy may not be therapeutically viable. In this work, platinum-doped silver nanoparticles (Pt-AgNPs) were explored to evaluate their potential for enhanced Ag+ release, which could lead to enhanced antimicrobial efficacy against S. aureus, P. aeruginosa, and E. coli. AgNPs doped with 0.5, 1, and 2 mol% platinum (Pt0.5 -AgNPs, Pt1 -AgNPs, and Pt2 -AgNPs) were synthesized by a chemical reduction method. Transmission electron microscopy revealed mixed morphologies of spherical, oval, and ribbon-like nanostructures. Surface-enhanced Raman scattering revealed that the surface of Pt-AgNPs was covered with up to 93% Pt. The amount of Ag+ released increased 16.3-fold for Pt2 -AgNPs, compared to AgNPs. The initial lag phase in bacterial growth curve was prolonged for Pt-AgNPs. This is consistent with a Ag+ release profile that exhibited an initial burst followed by sustained release. Doping AgNPs with platinum significantly increased the antimicrobial efficacy against all species. Pt2 -AgNPs exhibited the lowest minimum inhibitory concentrations, followed by Pt1 -AgNPs, Pt0.5 -AgNPs, and AgNPs, respectively. Doping AgNPs with a small amount of platinum promoted the release of Ag+ , based on the sacrificial anodic effect, and subsequently enhanced their antimicrobial efficacy.

Comparison of the Accuracy of Implant Position Using Surgical Guides Fabricated by Additive and Subtractive Techniques.

PURPOSE: To evaluate the accuracy of implant position using surgical guides fabricated by additive and subtractive techniques. MATERIALS AND METHODS: A partially edentulous standardized mandibular implant model with different bone densities and soft tissue was duplicated and a diagnostic wax-up was performed for the #30 area. A reference radiographic guide was fabricated and cone beam computed tomography (CBCT) was made with the reference radiographic guide in place. A surgical guide was designed using BlueSky Plan 4 software and a reference implant was placed in the #30 region. The STL file of the surgical guide was exported and specimens (n = 15) were fabricated by two different techniques: additive (3D printing) and subtractive (milling). The standardized mandibular model was surface-scanned and duplicated with printed dental model resin (n = 30). Each surgical guide was used to place an implant in thirty duplicate printed models. Differences in implant position as compared to the reference were measured from digital scans with scan bodies in place. The angular deviations, differences in depth, coronal and apical deviations were measured using GeoMagic Control X software. Results were analyzed by Wilcoxon-Mann-Whitney test and PERMANOVA (Permutational Multivariate Analysis of Variance). Intraclass correlation was used to assess measurement reproducibility with Bonferroni adjustment for multiple testing as needed (α = 0.05). RESULTS: There were no significant differences in accuracy of implant placement using guides fabricated using additive vs subtractive techniques. The mean angular deviations between the reference and actual position of implant in mesio-distal cross-section were 0.780 ± 0.80° for printed group and 0.77 ± 0.72° for the milled group. The differences in bucco-lingual cross-section were 1.60 ± 1.22° in in printed group and 1.77 ± 0.76° in the milled group. The differences in depth (mm) were measured at the top of the scan body at four locations: mesial, distal, buccal and lingual. The mean differences in depth for the group that used printed surgical guides were (mesial) 0.37 ± 0.29 mm, (distal) 0.32 ± 0.23 mm, (buccal) 0.24 ± 0.23 mm, and (lingual) 0.25 ± 0.17 mm. The mean differences in depth for the group that used milled surgical guides were (mesial) 0.51 ± 0.33 mm, (distal) 0.40 ± 0.32 mm, (buccal) 0.22 ± 0.23 mm, and (lingual) 0.23 ± 0.12 mm in those four aspects, respectively. The mean coronal deviation showed 0.32 mm in the printed group and 0.27 mm in the milled group. For the apical deviation, the results of this study showed mean apical deviation 0.84 mm in the printed group and 0.80 mm in the milled group. CONCLUSIONS: Results indicate that 3D-printed surgical guides are statistically as accurate as milled guides for guided-implant surgery with the benefits of high accuracy, ease of fabrication, less waste compared to subtractive techniques, and reduction of laboratory time thereby increasing cost-effectiveness.

A novel sample design for determining color compatibility between layered resin composite and vita shade guides.

OBJECTIVE: To compare the color of double-layered (DL) resin-composite (RC) samples with variant enamel-thicknesses (ET) to their corresponding shade-tabs from VITA classical (VC) and 3D-Master (V3DM). METHODS: A2-DL samples (N = 30) fabricated using three pairs of custom-made molds with an ET of 0.5, 0.7, and 1.0 mm. Shades were selected according to the manufacturer's instructions of two RC brands: Clearfil-Majesty (CM), and Vita-l-essence (VL). A spectrophotometer measured CIE L*a*b* color parameters. We used ΔE 00 to calculate color differences among DL samples, VC, and V3DM shade-tabs. The data were analyzed using Spearman correlation coefficient, one-way ANOVA, and Tukey test (∝=0.05). RESULTS: ΔE 00 between DL samples A2 and 2M2 shade tabs were all greater than the predetermined 50:50% acceptability threshold (ΔE 00 = 6.6-10.4). Depending on the shade tabs compared, the ΔE 00 among CM and VL ET subgroups were statistically different (P < .001). ET and L* were negatively correlated for CM and VL. For CM, ΔE 00 and L* correlated on the A2 shade tab, whereas for VL, ΔE 00 , and ET correlated on the 2M2 shade tab (P < .05). CONCLUSIONS: The DL samples produced unacceptable color matches to their corresponding shade. An enamel layer thickness of 0.7 mm corresponded to the lowest ΔE 00 . The use of V3DM for RC shade selection should be investigated. CLINICAL SIGNIFICANCE: Understanding color interaction between RC layers is important to achieve consistent results in esthetic clinical procedures. The thickness of the enamel layer can critically alter the overall shade for a given RC shade and brand. This variation is difficult for the clinician to predict and negatively impacts patient satisfaction, increasing overall procedure costs, and decreasing efficiency. This color interaction study aims to facilitate consistency in shade reproduction.

Enhancing Student Learning in Removable Partial Denture Design by Using Virtual Three-Dimensional Models Versus Traditional Two-Dimensional Drawings: A Comparative Study.

PURPOSE: To compare the use of virtual 3D casts as an alternative to paper-based exercises in preclinical removable partial denture (RPD) design in terms of student outcomes (as evidenced by exercise evaluation scores), as well as student attitudes related to the 2 formats. The first hypothesis of this study is that virtual 3D digital models in the exercise will result in better student outcomes as evidenced by the final exercise score compared to the 2D drawings. The second hypothesis is that virtual 3D digital models in the exercise will result in greater student acceptance compared to the 2D drawings. MATERIALS AND METHODS: Students were divided into 2 equal, randomly assigned groups Both groups were made to solve 2 exercises: a class II exercise and a class IV exercise. Group 1 received the first exercise (exercise #1) as a Kennedy class IV design exercise in virtual 3D and the second exercise (exercise #2) as a Kennedy class II design exercise in traditional format. Group 2 would receive the opposite exercise #1 as a Kennedy class IV in traditional format and exercise #2 as a Kennedy class II in virtual 3D format. Virtual 3D casts were made to be identical to the traditional exercises. Students were then asked to complete a short survey to assess their preferences. The Wilcoxon Rank Sum test was used to compare the distribution of scores of exercises using the virtual 3D format with the scores when students used the traditional 2D format. Preference comparisons for the 2 formats were accomplished using exact binomial tests. RESULTS: There was no difference in learning outcomes based on the distribution of student scores for either exercise independent of presentation format (p > 0.52). There was also no difference in individual student score between 2 identical exercises, independent of whether the exercise was using 3D virtual models or 2D drawings. A greater proportion of students agreed with the statements that favored the use of the virtual 3D models than disagreed with respect to all 7 questions asked, based upon the sign test (comparing agreement vs. disagreement with the statement, p < 0.0003 in all instances). CONCLUSION: Despite there being no difference in learning outcomes (final scores), the students showed an overwhelming preference in having the virtual 3D casts part as part of the curriculum.

Masking and Penetration Ability of Various Sealants and ICON in Artificial Initial Caries Lesions In Vitro.

PURPOSE: The purpose of the present in vitro study and survey was to compare the masking ability and the penetration capacity of three resin composite sealers as well as a resin infiltrant in shallow artificial caries lesions. MATERIALS AND METHODS: Panels of artificial initial caries lesion with an average depth of 200 µm were created on buccal and lingual surfaces of 75 extracted human molars. Specimens were randomly assigned to 5 groups: ICON (DMG America), Biscover LV (Bisco), Optiguard (Kerr Hawe), Permaseal (Ultradent), and control (no treatment). Teeth were hemi-sectioned yielding two halves, each with a panel of artificial caries lesion. Lesions on one hemi-section were used to assess the esthetic improvement following caries lesion penetration with the 4 resins based on photographs evaluated using a 100-mm visual analogue scale (VAS) by 17 raters. Lesions on opposite hemi-sections were used to measure the resin penetration area percentage (PA%) and the resin penetration depth percentage (PD%) visualized using a confocal laser scanning microscope (CLSM, Leica). RESULTS: ICON, Optiguard, and Permaseal yielded significantly greater average VAS scores compared to Biscover. The mean PA% and PD% were significantly higher for ICON, intermediate for Optibond and Permaseal, and significantly lower for Biscover. A moderately large positive correlation was noticed between the average VAS scores and the penetration measures. CONCLUSION: All the resin sealers (Biscover, Optiguard, and Permaseal) penetrated the artificial initial caries lesions. However, ICON resulted in the deepest penetration and the largest penetration area percentages. The masking ability of Optiguard and Permaseal of the artificial caries lesions was similar to ICON.

A High-Throughput Assay for Congenital and Age-Related Eye Diseases in Zebrafish.

Debilitating visual impairment caused by cataracts or microphthalmia is estimated to affect roughly 20 million people in the United States alone. According to the National Eye Institute, by 2050 that number is expected to more than double to roughly 50 million. The identification of candidate disease-causing alleles for cataracts and microphthalmia has been accelerated with advanced sequencing technologies creating a need for verification of the pathophysiology of these genes. Zebrafish pose many advantages as a high-throughput model for human eye disease. By 5 days post-fertilization, zebrafish have quantifiable behavioral responses to visual stimuli. Their small size, many progeny, and external fertilization allows for rapid screening for vision defects. We have adapted the OptoMotor Response to assay visual impairment in zebrafish models of cataracts and microphthalmia. This research demonstrates an inexpensive, high-throughput method for analyzing candidate genes involved in visual impairment.

Effect of Surface Modification on In-Depth Transformations and Flexural Strength of Zirconia Ceramics.

PURPOSE: Chairside surface adjustments of zirconia dental restorations enhance the toughening stress-induced tetragonal-to-monoclinic phase transformation and domain reorientation by ferro-elastic domain switching (FDS), but also trigger subsurface damage, which could compromise long-term clinical performance. The purpose of this study was to assess the depth of phase transformation, associated FDS, and flexural strength of dental zirconia (BruxZir HT 2.0), after chairside surface treatments. MATERIALS AND METHODS: Square specimens were sectioned from CAD/CAM blocks and sintered according to manufacturer's recommendations (n = 30). They were left as-sintered (AS; control), air abraded with fine (AAF) or coarse (AAC) alumina particles, ground (G) or ground and polished (GP). Roughness was measured by profilometry. Crystalline phases were investigated by grazing incidence X-ray diffraction (GIXRD) (n = 3). GIXRD data were fit using semi-log regression protocols to assess transformation depth and extent of FDS. The mean biaxial flexural strength was measured according to ISO 6872. Subsurface damage was assessed from SEM images using a bonded polished interface configuration. Flaw distribution was assessed by Weibull analysis. Results were analyzed by Kruskal-Wallis with Tukey's adjustment for multiple comparisons (p < 0.05). RESULTS: Air-abraded and ground groups exhibited higher mean surface roughness than control. AAF group exhibited the highest flexural strength (1662.6 ± 202.6 MPa) with flaw size (5.9 ± 1.8 µm) smaller than transformation (14.5 ± 1.2 µm) or FDS depth (19.3 ± 1.1 µm), followed by GP group (1567.2 ± 209.7 MPa) with smallest FDS depth (9.3 ± 2.0 µm) and flaw size (2.6 ± 1.8 µm), but without m-phase. AAC group (1371.4 ± 147.6 MPa) had the largest flaw size (40.3 ± 20.3 µm), transformation depth (47.2 ± 3.0 µm) and FDS depth (41.2 ± 2.2 µm). G group (1357.0 ± 196.7 MPa) had the smallest transformation depth (8.6 ± 1.5 µm), and mean FDS depth (19.8 ± 3.7 µm) and flaw size (18.6 ± 3.1 µm). AAC and AAF exhibited the highest Weibull modulus (11.2 ± 0.4 and 9.8 ± 0.3 µm, respectively). CONCLUSIONS: Variations in mean biaxial flexural strength were explained by the balance between the depth of toughening mechanisms (phase transformation and FDS) and subsurface damage. AAF and GP groups were the most efficient surface adjustments in promoting the highest mean biaxial flexural strength.

Patient Expectation and Satisfaction with Different Prosthetic Treatment Modalities.

PURPOSE: To investigate the relationships between gender, age, patients' perceptions about the dentists' conduct, number of adjustments, treatment type, and expectation prior to prosthetic treatment and patient satisfaction with their treatments. MATERIALS AND METHODS: Data were integrated from four studies that measured patient expectations before treatment and satisfaction after treatment using a visual analog scale (VAS) from 0 to 10. These scores were given for each of four aspects of the therapeutic outcomes: chewing, esthetics, phonetics, and comfort. Patients' perceptions about the dentists' conduct was also assessed using a Likert-scale questionnaire. The total sample size, after combining the data from all four studies, was 223 subjects. Bivariate and multivariable analyses were performed. The covariates entertained were gender, age, treatment type, patients' perceptions about the dentists' conduct, number of adjustments, and expectation prior to denture fabrication. RESULTS: In the entire sample, 115 (51.57%) patients were females and 108 (48.43%) were males. They ranged in age from 28 to 81 years old; the mean age was 53.2 years (SD = 11.5). Combining four treatments together, there was no significant difference between patients' expectation and satisfaction scores for all four items. There were no significant differences between expectation and satisfaction for different genders. Multivariable analysis showed that patient expectation, satisfaction and the difference (satisfaction score-expectation score) scores for all four aspects were associated with treatment type (implant treatments were favored), and expectation prior to prosthetic treatment (the higher the expectation, the higher the satisfaction) was associated with satisfaction and difference scores. Satisfaction and difference scores for chewing were associated with number of adjustments and satisfaction, and satisfaction and difference scores for phonetics and comfort were associated with how well the dentist explained the intended treatment before performing it. CONCLUSIONS: Patient satisfaction was associated with treatment type (implant treatments were favored), expectations prior to prosthetic treatment (the higher the expectation, the higher the satisfaction), and how well the dentist explained the intended treatment before performing it.

Iowa nursing facility oral hygiene (INFOH) intervention: A clinical and microbiological pilot randomized trial.

PURPOSE/AIM: The aim of this pilot study was to evaluate feasibility and gather initial data for a definitive study to test the clinical and microbiological effectiveness of a nursing facility (NF) customized oral hygiene protocol, intended to be delivered by dental hygienists and NF personnel. MATERIALS AND METHODS: A convenience sample of 8 Eastern Iowa NFs was recruited, and each NF was assigned to one of three intervention groups: (1) control (current oral hygiene practice), (2) educational program only, and (3) educational program plus 1% chlorhexidine varnish monthly application. Demographic information, systemic health data, patient centered data, oral health data, and microbiology samples were collected at baseline and after 6 months. RESULTS: Recruitment response rates were 21% for NFs and 23% for residents. A total of 81 residents were examined at baseline and of those, 49 were examined at 6 months (39.5% attrition). There were no statistically or clinically significant differences among the intervention groups at 6 months for any of the recorded clinical or microbiological outcomes. CONCLUSIONS: Recruitment and retention posed a significant challenge to this trial, even with a relatively short observation period. Results from this pilot study did not encourage further investigation of this customized oral hygiene protocol.

High-throughput behavioral assay to investigate seizure sensitivity in zebrafish implicates ZFHX3 in epilepsy.

Epilepsy, which affects ∼1% of the population, is caused by abnormal synchronous neural activity in the central nervous system (CNS). While there is a significant genetic contribution to epilepsy, the underlying causes for the majority of genetic cases remain unknown. The NIH Undiagnosed Diseases Project (UDP) utilized exome sequencing to identify genetic variants in patients affected by various conditions with undefined etiology, including epilepsy. Confirming the functional relevance of the candidate genes identified by exome sequencing in a timely manner is crucial to translating exome data into clinically useful information. To this end, we developed a high throughput version of a seizure-sensitivity assay in zebrafish (Danio rerio) to rapidly evaluate candidate genes found by exome sequencing. We developed open access software, Studying Epilepsy In Zebrafish using R (SEIZR), to efficiently analyze the data. SEIZR was validated by disrupting function of a known epilepsy gene, prickle 1. Next, using SEIZR, we analyzed a candidate gene from the UDP screen (Zinc Finger Homeobox 3, ZFHX3), and showed that reduced ZFHX3 function in zebrafish results in a significant hyperactive response to the convulsant drug pentylenetetrazol (PTZ). We find that ZFHX3 shows strong expression in the CNS during neurogenesis including in the pallium, thalamus, tegmentum, reticular formation, and medulla oblongata - all regions which have roles in motor control and coordination. Our findings in the zebrafish confirm human ZFHX3 is a strong candidate for further neurological studies. We offer SEIZR to other researchers as a tool to rapidly and efficiently analyze large behavioral data sets.

The Nkd EF-hand domain modulates divergent wnt signaling outputs in zebrafish.

Wnt proteins regulate diverse biological responses by initiating two general outcomes: ß-catenin-dependent transcription and ß-catenin-independent activation of signaling cascades, the latter including modulation of calcium and regulation of cytoskeletal dynamics (Planar Cell Polarity, PCP). It has been difficult to elucidate the mechanisms by which Wnt signals are directed to effect one or the other outcome due to shared signaling proteins between the ß-catenin-dependent and -independent pathways, such as the Dishevelled binding protein Naked. While all Naked paralogs contain a putative calcium-binding domain, the EF-Hand, Drosophila Naked does not bind calcium. Here we find a lineage-specific evolutionary change within the Drosophila Naked EF-hand that is not shared with other insects or vertebrates. We demonstrate the necessary role of the EF-hand for Nkd localization changes in calcium fluxing cells and using in vivo assays, we identify a role for the zebrafish Naked EF-hand in PCP but not in ß-catenin antagonism. In contrast, Drosophila-like Nkd does not function in PCP, but is a robust antagonist of Wnt/ß-catenin signaling. This work reveals that the zebrafish Nkd1 EF-hand is essential to balance Wnt signaling inputs and modulate the appropriate outputs, while the Drosophila-like EF-Hand primarily functions in ß-catenin signaling.

A Teaching Tool for Establishing Risk of Oral Health Deterioration in Elderly Patients: Development, Implementation, and Evaluation at a U.S. Dental School.

The aim of this study was to develop and evaluate a learning strategy using critical thinking to teach dental students how to assess the risk of rapid oral health deterioration (ROHD) among elderly patients. A learning guide was developed using risk factors identified in the literature and the steps that expert faculty members apply in their clinical decision making, summarized in a set of ten steps. A new system of labeling risk was developed for the elderly population, which correlates the level of risk with the amount of disease. Participants in the study were all 91 fourth-year dental students in two subsequent classes who took part in a five-week Geriatrics and Special Needs Clinic rotation in the spring of 2015 and 2016. The students were introduced to the ROHD concept and asked to use the guide in a presentation during their rotation. The students were graded on an A, G, or M scale (Applied concept, Grasped and applied concept, or Missed application of concept). Students were also asked to assess their learning experience, and their answers were thematically grouped and analyzed. For eight of the ten steps, at least 93% of the students were graded A or G. The exceptions were the steps about developing a communications plan, which was missed by 23.1%, and self-assessment, which was missed by 30.8%. Interexaminer agreement on students' applying (A + G grades) versus missing the step was moderate or high on six of ten items. Nearly all the students (98.7%) considered assessing the risk of ROHD an important or very important skill. In this study, a learning strategy to teach dental students how to assess the risk of ROHD among elderly patients was developed and successfully implemented.

Descriptive Epidemiology of Orofacial Clefts in Ethiopia.

BACKGROUND: The prevalence of birth defects including orofacial clefts (OFC) in Ethiopia is not known and there is no established birth defects registration system. OBJECTIVES: To investigate the prevalence and incidence of OFC in Ethiopia. DESIGN: Retrospective hospital-based descriptive study. METHODS: The authors obtained data from the Smile Train database on Ethiopian patients with OFC who underwent surgical treatment from June 2007 to December 2013 at 31 hospitals distributed throughout the country. Data related to live births in Ethiopia during the mentioned period were obtained from the Federal Ministry of Health database for estimates of the incidence and prevalence rates. RESULTS: The total number of life births during the study period was 18,811,316. During this same period, 18,073 cleft patients approximately ranging from 1 to 75 years old were examined and treated at the hospitals mentioned earlier. The incidence rate estimated from the total number of affected children during the study period (N = 8232) is 0.44/1000 live births. The prevalence rate is 0.20/1000 and this was estimated using the number of total population in 2013 (N = 88,703,914). There is a significant difference in frequency between bilateral clefts of the lip and/or palate (CLP) (26.9%) versus unilateral CLP (73.1%) (P < 0.0001). There is also a significant difference in frequency between bilateral cleft lips only (15.4%) versus unilateral cleft lip only (84.6%), P < 0001. CONCLUSION: It is obvious that the findings in this study cannot be representative of the true picture but provides a previously unavailable national estimate of incidence and prevalence of OFC in Ethiopia. It can also be used as comparison for future community-based studies.

Genotypic characterization and comparison of Streptococcus mutans in American Indian and Southeast Iowa children.

Early childhood caries is a complex health care issue that has a multifactorial etiology. One aspect of this etiology is the colonization and propagation of acidogenic bacteria at an early age. There have been several bacterial species associated with caries but 1 common species is Streptococcus mutans. Here, we describe genotypic diversity and commonality of Streptococcus mutans recovered from children representing 2 groups with similar socioeconomic demographics: a Northern Plains American Indian Tribe and a Southeast Iowa population. Forty 36-month-old American Indian children were selected from a cohort of 239 mothers and children, and forty 2- to 5-year-old children from Southeast Iowa were selected to compare the genotypic profiles of Streptococcus mutans recovered from each child's plaque. S. mutans isolates were selected from whole mouth plaque samples; DNA was extracted and amplified via AP-PCR to show specific genotype patterns. These patterns were compared with GelComparIIv6.5 gel analysis software. We found 18 distinct genotypes from 524 isolates; 13 of which were common between the 2 communities. Five genotypes were unique to only the American Indian children while the Southeast Iowa children harbored no unique genotypes. Although the American Indian children had some genotypes that were not present in the Southeast Iowa children, these were not widely distributed among the community. Furthermore, the levels of genotypic diversity and commonality were similar between the 2 populations. This study sets the groundwork for a comprehensive comparison of genotypes and caries among larger subsections of both populations.

PCR-Based Identification of Oral Streptococcal Species.

The microbial etiology of dental caries is still debated. Among the hypothesized contributors are the "low pH streptococci," a designation given to unusually acid proficient strains among the primary plaque colonizers S. oralis, S. mitis, S. gordonii, and S. anginosus. However, accurate assignment of species is difficult among the oral streptococci. Our objective was to develop a streamlined method for identifying strains of S. oralis and S. mitis from plaque samples so that they could be analyzed in a separate study devoted to low pH streptococci and caries. Two independent PCR amplifications of a locus highly conserved among streptococci were used for presumptive species identification. Multilocus sequence analysis (MLSA) was used to measure accuracy. Sensitivity was 100% for selecting S. oralis and S. mitis among the clones sampled. Specificity was good except for the most closely related species that could not be reliably distinguished even by MLSA. The results with S. oralis and S. mitis were used to identify new primer sets that expanded the utility of the approach to other oral streptococcal species. These novel primer sets offer a convenient means of presumptive identification that will have utility in many studies where large scale, in-depth genomic analyses are not practical.

Acidogenicity and acid tolerance of Streptococcus oralis and Streptococcus mitis isolated from plaque of healthy and incipient caries teeth.

BACKGROUND: Non-mutans low pH oral streptococci are postulated to contribute to caries etiology. OBJECTIVE: This study was undertaken to investigate whether the acidogenicity and acid tolerance of clinical strains of Streptococcus oralis and Streptococcus mitis correlate with health or early-stage enamel caries. DESIGN: S. oralis and S. mitis were isolated from plaque samples taken from the occlusal surfaces of second molars sampled at two different visits 4 years apart. All sites were sound at Visit 1; subjects were segregated into one of three groups based on the status of the site at Visit 2 and caries elsewhere in the dentition. Strains of S. oralis and S. mitis were evaluated for acidogenicity and acid tolerance, and the results correlated with the clinical status of the sites from which they were isolated. Mutans streptococci (MS) isolated from the plaque samples were also quantified, and the presence or absence of growth on pH 5.5 media or on media selective for bifidobacteria was recorded. RESULTS: No significant positive correlations were found between the acidogenicity properties of the S. oralis and S. mitis clones and caries at either visit. Similar results were obtained for acid tolerance of S. oralis clones but were inconclusive for S. mitis clones. A statistically significant positive correlation between MS levels and caries (or future caries) was evident at both visits, but there were no statistical correlations with the growth on pH 5.5 media or media selective for bifidobacteria. CONCLUSIONS: The low pH potential likely varies considerably among oral streptococcal species and is least likely to be found among strains of S. mitis. Accordingly, the concept and constitution of 'low pH streptococci' may need to be re-evaluated.

Time Course of Potassium Nitrate Penetration into the Pulp Cavity and the Effect of Penetration Levels on Tooth Whitening Efficacy.

OBJECTIVES: To establish time-course of potassium nitrate (PN) penetration into the pulp cavity, and determine whether PN pretreatment would affect whitening efficacy. MATERIALS AND METHODS: Extracted teeth (n = 100) were randomized into five groups of 20 specimens each. Relief ACP (Philips Oral Healthcare, Los Angeles, CA, USA) was applied for 0, 5, 15, 30, and 60 minutes for groups 15, respectively. A nitrate/nitrite assay kit was used for colorimetric detection of nitrate. Whitening was performed using a Zoom White Speed system (Philips Oral Healthcare) for 60 minutes. Tooth color was measured with a spectrophotometer at baseline (T0 ), 1-day post PN application (T1 ), 1-day post-whitening (T2 ), and 1-month post-whitening (T3 ). Kruskal-Wallis test was used to assess group differences in PN penetration and tooth color change. RESULTS: PN penetration differed among all groups except 2 and 3. There were no differences among groups for any baseline color parameters (p > 0.30). At T2 there was no change relative to baseline for individual components L*, a*, and b*. At T3 and T4 there was significant change relative to baseline for ΔL*, Δb*, and ΔE*, for all groups. CONCLUSIONS: PN penetration is time dependent and pretreatment with PN does not affect whitening efficacy. CLINICAL SIGNIFICANCE: Postassium nitrate penetration into the pulp cavity occurred as early as 5 minutes after application, and pretreatment with potassium nitrate containing desensitizers did not adversely affect tooth whitening efficacy. (J Esthet Restor Dent 28:S14-S22, 2016).