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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Protein Analysis of Sapienic Acid-Treated Porphyromonas gingivalis Suggests Differential Regulation of Multiple Metabolic Pathways.

UNLABELLED: Lipids endogenous to skin and mucosal surfaces exhibit potent antimicrobial activity against Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. Our previous work demonstrated the antimicrobial activity of the fatty acid sapienic acid (C(16:1Δ6)) against P. gingivalis and found that sapienic acid treatment alters both protein and lipid composition from those in controls. In this study, we further examined whole-cell protein differences between sapienic acid-treated bacteria and untreated controls, and we utilized open-source functional association and annotation programs to explore potential mechanisms for the antimicrobial activity of sapienic acid. Our analyses indicated that sapienic acid treatment induces a unique stress response in P. gingivalis resulting in differential expression of proteins involved in a variety of metabolic pathways. This network of differentially regulated proteins was enriched in protein-protein interactions (P = 2.98 × 10(-8)), including six KEGG pathways (P value ranges, 2.30 × 10(-5) to 0.05) and four Gene Ontology (GO) molecular functions (P value ranges, 0.02 to 0.04), with multiple suggestive enriched relationships in KEGG pathways and GO molecular functions. Upregulated metabolic pathways suggest increases in energy production, lipid metabolism, iron acquisition and processing, and respiration. Combined with a suggested preferential metabolism of serine, which is necessary for fatty acid biosynthesis, these data support our previous findings that the site of sapienic acid antimicrobial activity is likely at the bacterial membrane. IMPORTANCE: P. gingivalis is an important opportunistic pathogen implicated in periodontitis. Affecting nearly 50% of the population, periodontitis is treatable, but the resulting damage is irreversible and eventually progresses to tooth loss. There is a great need for natural products that can be used to treat and/or prevent the overgrowth of periodontal pathogens and increase oral health. Sapienic acid is endogenous to the oral cavity and is a potent antimicrobial agent, suggesting a potential therapeutic or prophylactic use for this fatty acid. This study examines the effects of sapienic acid treatment on P. gingivalis and highlights the membrane as the likely site of antimicrobial activity.

Factors Associated with Reevaluation of the Stepwise Excavation Procedure: An 8-Year Retrospective Study.

Although the stepwise excavation procedure (SWP) has been shown to be an effective caries treatment technique, studies reporting its application outside of controlled clinical trials are limited. We performed a retrospective study from patient record data to assess the proportion of patients who had an SWP reevaluated within 18 months at The University of Iowa College of Dentistry (UICOD) between 2004 and 2012, and evaluated the association between different variables and this outcome. A total of 1,985 SWPs were performed in 1,326 patients, with 518 patients having had reevaluation within 18 months. Bivariate analysis and logistic regression modeling revealed strong associations between explanatory variables such as provider type, tooth type, patient age, number of recalls and the calendar year in which the SWP was done and reevaluation status. There was also evidence of association with dental insurance status. Other characteristics such as gender, distance traveled to the UICOD, number of surfaces treated and tooth arch did not show any significant association. In general, patients were more likely to have reevaluation when seen by faculty members or residents, the procedure was performed in molars/pre-molars, they were older, they had more recalls and were seen earlier in the study period. These results suggest that decisions to use SWP should consider patient demographics and treatment characteristics such as provider level, tooth type, patient age and number of recalls. The impact of treatment year may reflect program heterogeneity or temporal changes in external societal factors.

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).

The roles of cutaneous lipids in host defense.

Lauric acid (C12:0) and sapienic acid (C16:1Δ6) derived from human sebaceous triglycerides are potent antimicrobials found at the human skin surface. Long-chain bases (sphingosine, dihydrosphingosine and 6-hydroxysphingosine) are also potent and broad-acting antimicrobials normally present at the skin surface. These antimicrobials are generated through the action of ceramidases on ceramides from the stratum corneum. These natural antimicrobials are thought to be part of the innate immune system of the skin. Exogenously providing these lipids to the skin may provide a new therapeutic option, or could potentially provide prophylaxis in people at risk of infection. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Comparison of pro-inflammatory cytokines and bone metabolism mediators around titanium and zirconia dental implant abutments following a minimum of 6 months of clinical function.

OBJECTIVES: Dental implant abutments are fundamental prosthetic components within dentistry that require optimal biocompatibility. The primary aim of this cross-sectional study was to preliminarily assess differences in the pro-inflammatory cytokine and bone metabolism mediator protein expression in the peri-implant crevicular fluid (PICF) adjacent to transmucosal abutments. MATERIAL AND METHODS: Abutments were fabricated from either titanium or zirconia in patients previously receiving single-tooth implant therapy. All subjects sampled in this study had an identical implant system and implant-abutment connection. Participants (n = 46) had an average time of clinical function for 22 months (6.2-72.8 months, ±SD 17 months) and received a clinical and radiographic examination of the implant site at the time of PICF sampling using a paper strip-based sampling technique. Cytokine, chemokine, and bone metabolism mediator quantities (picograms/30 s) were determined using a commercial 22-multiplexed fluorescent bead-based immunoassay instrument. A total of 19 pro-inflammatory cytokines and seven bone metabolism mediators were evaluated. RESULTS: Multivariable analyses provided no evidence of a group (titanium or zirconia), gender, or age effect with regard to the expression of pro-inflammatory mediators evaluated. Significant (P = 0.022) differences were observed for the bone mediator leptin, with titanium abutments demonstrating significantly elevated levels in comparison with zirconia. Osteopontin demonstrated a significant (P = 0.0044) correlation with age of the subjects. CONCLUSIONS: No significant differences in pro-inflammatory cytokine or bone metabolism mediator profiles were observed biochemically, with the exception of leptin, for the abutment biomaterials of titanium or zirconia The molecular PICF findings support the observed clinical biocompatibility of both titanium and zirconia abutments.

Phenotypic diversity in white adults with moderate to severe Class II malocclusion.

INTRODUCTION: Class II malocclusion affects about 15% of the population in the United States and is characterized by a convex profile and occlusal disharmonies. The specific etiologic mechanisms resulting in the range of Class II dentoskeletal combinations observed are not yet understood. Most studies describing Class II phenotypic diversity have used moderate sample sizes or focused on younger patients who later in life might outgrow their Class II discrepancies; such a focus might also preclude the visualization of adult Class II features. The majority have used simple correlation methods resulting in phenotypes that might not be generalizable to different samples and thus might not be suitable for studies of malocclusion etiology. The purpose of this study was to address these knowledge gaps by capturing the maximum phenotypic variations in a large sample of white Class II subjects selected with strict eligibility criteria and rigorously standardized multivariate reduction analyses. METHODS: Sixty-three lateral cephalometric variables were measured from the pretreatment records of 309 white Class II adults (82 male, 227 female; ages, 16-60 years). Principal component analysis and cluster analysis were used to generate comprehensive phenotypes to identify the most homogeneous groups of subjects, reducing heterogeneity and improving the power of future malocclusion etiology studies. RESULTS: Principal component analysis resulted in 7 principal components that accounted for 81% of the variation. The first 3 components represented variation on mandibular rotation, maxillary incisor angulation, and mandibular length. The cluster analysis identified 5 distinct Class II phenotypes. CONCLUSIONS: A comprehensive spectrum of Class II phenotypic definitions was obtained that can be generalized to other samples to advance our efforts for identifying the etiologic factors underlying Class II malocclusion.

Phenotypic diversity in white adults with moderate to severe Class III malocclusion.

INTRODUCTION: Class III malocclusion is characterized by a composite of dentoskeletal patterns that lead to the forward positioning of the mandibular teeth in relation to the maxillary teeth and a concave profile. Environmental and genetic factors are associated with this condition, which affects 1% of the population in the United States and imposes significant esthetic and functional burdens on affected persons. The purpose of this study was to capture the phenotypic variation in a large sample of white adults with Class III malocclusion using multivariate reduction methods. METHODS: Sixty-three lateral cephalometric variables were measured from the pretreatment records of 292 white subjects with Class II malocclusion (126 male, 166 female; ages, 16-57 years). Principal component analysis and cluster analysis were used to capture the phenotypic variation and identify the most homogeneous groups of subjects to reduce genetic heterogeneity. RESULTS: Principal component analysis resulted in 6 principal components that accounted for 81.2% of the variation. The first 3 components represented variation in mandibular horizontal and vertical positions, maxillary horizontal position, and mandibular incisor angulation. The cluster model identified 5 distinct subphenotypes of Class III malocclusion. CONCLUSIONS: A spectrum of phenotypic definitions was obtained replicating results of previous studies and supporting the validity of these phenotypic measures in future research of the genetic and environmental etiologies of Class III malocclusion.

Antibacterial activity of sphingoid bases and fatty acids against Gram-positive and Gram-negative bacteria.

There is growing evidence that the role of lipids in innate immunity is more important than previously realized. How lipids interact with bacteria to achieve a level of protection, however, is still poorly understood. To begin to address the mechanisms of antibacterial activity, we determined MICs and minimum bactericidal concentrations (MBCs) of lipids common to the skin and oral cavity--the sphingoid bases D-sphingosine, phytosphingosine, and dihydrosphingosine and the fatty acids sapienic acid and lauric acid--against four Gram-negative bacteria and seven Gram-positive bacteria. Exact Kruskal-Wallis tests of these values showed differences among lipid treatments (P < 0.0001) for each bacterial species except Serratia marcescens and Pseudomonas aeruginosa. D-sphingosine (MBC range, 0.3 to 19.6 µg/ml), dihydrosphingosine (MBC range, 0.6 to 39.1 µg/ml), and phytosphingosine (MBC range, 3.3 to 62.5 µg/ml) were active against all bacteria except S. marcescens and P. aeruginosa (MBC > 500 µg/ml). Sapienic acid (MBC range, 31.3 to 375.0 µg/ml) was active against Streptococcus sanguinis, Streptococcus mitis, and Fusobacterium nucleatum but not active against Escherichia coli, Staphylococcus aureus, S. marcescens, P. aeruginosa, Corynebacterium bovis, Corynebacterium striatum, and Corynebacterium jeikeium (MBC > 500 µg/ml). Lauric acid (MBC range, 6.8 to 375.0 µg/ml) was active against all bacteria except E. coli, S. marcescens, and P. aeruginosa (MBC > 500 µg/ml). Complete killing was achieved as early as 0.5 h for some lipids but took as long as 24 h for others. Hence, sphingoid bases and fatty acids have different antibacterial activities and may have potential for prophylactic or therapeutic intervention in infection.

The use of a respiratory rate biofeedback device to reduce dental anxiety: an exploratory investigation.

Anxiety experienced by individuals visiting the dental office to receive treatment is common. Evidence has shown biofeedback to be a useful modality of treatment for numerous maladies associated with anxiety. The purpose of the current pilot study was to investigate the use of a novel biofeedback device (RESPeRATE™) to reduce patients' pre-operative general anxiety levels and consequently reduce the pain associated with dental injections. Eighty-one subjects participated in this study, forty in the experimental group and forty-one in the control group. Subjects in the experimental group used the biofeedback technique, while those in the control group were not exposed to any biofeedback. All subjects filled out a pre-injection anxiety survey, then received an inferior alveolar injection of local anesthetic. Post-injection, both groups were given an anxiety survey and asked to respond to four questions regarding the injection experience using a Visual Analog Scale (VAS). With the use of the respiratory rate biofeedback device, there was a significant reduction of negative feelings regarding the overall injection experience, as measured by a VAS. Our findings demonstrate that this novel biofeedback technique may be helpful in the amelioration of dental anxiety, and may help produce a more pleasant overall experience for the patient.

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.