Mineralization Potential of Polarized Dental Enamel

Background: Management of human teeth has moved from a surgical to a more conservative approach of inhibiting or preventing lesion progression. Increasing enamel mineralization is crucial in this regard. A potential difficulty is the preferential mineralization of the outermost portion of the enamel that can prevent overall mineralization. We describe a strategy for increasing the mineralization potential of dental enamel. Methodology/Principal Findings: Extracted human premolar teeth enamel (n = 5) were exposed to a high concentration of hydrogen peroxide with an energizing source. Samples were stored in artificial saliva at 37uC for 1 wk. A desktop X-ray micro-CT system was used to evaluate the mineral density of samples. Mineral distribution was polarized between the lower and the higher mineralized portion of enamel by charged oxygen free radicals due to activation of permeated hydrogen peroxide. The kinetics of energy absorption in the deeper enamel region demonstrated improvement of preferential mineralization into the region without restricting overall mineralization of the enamel. Subsequent increasing mineralization, even in the dense mineralized outer portion of enamel, was also achieved. Conclusions/Significance: This increased mineralization may promote resistance to acidic deterioration of the structure. The present study is one of the primary steps towards the development of novel application in reparative and restorativ

The Most-cited Articles in Dentistry Up to 2017

Introduction: Citation analysis is a suitable way to help us to identify research trends within a specific topic. The purpose of this study was to identify the 100 most cited articles in the field of dentistry published over the past 67 years. Methods: A comprehensive list of the most cited articles in dentistry was compiled using ISI Web of Science. The characteristics including number of citations, authors and journals were analyzed. Results: The database resulted in 3,831 articles with 100 or more citations published between 1950 and 2017. Most of these articles had been published by the Journal of Clinical Periodontology, followed by the Journal of Periodontology, and Journal of Dental Research. Sokransky SS followed by Lindhe J, Nyman S, and Genco RJ had the most number of citations. Conclusion: The most cited articles in the field of dentistry allows for advances in this field and also provide useful information for direct future studies and patient care

In situ proliferation and differentiation of macrophages in dental pulp

The presence of macrophages in dental pulp is well known. However, whether these macrophages proliferate and differentiate in the dental pulp in situ, or whether they constantly migrate from the blood stream into the dental pulp remains unknown. We have examined and compared the development of dental pulp macrophages in an organ culture system with in vivo tooth organs to clarify the developmental mechanism of these macrophages. The first mandibular molar tooth organs from ICR mice aged between 16 days of gestation (E16) to 5 days postnatally were used for in vivo experiments. Those from E16 were cultured for up to 14 days with or without 10% fetal bovine serum. Dental pulp tissues were analyzed with immunohistochemistry to detect the macrophages and with reverse transcription and the polymerase chain reaction (RT-PCR) for the detection of factors related to macrophage development. The growth curves for the in vivo and in vitro cultured cells revealed similar numbers of F4/80-positive macrophages in the dental pulp. RT-PCR analysis indicated the constant expression of myeloid colony-stimulating factor (M-CSF) in both in-vivo- and in-vitro-cultured dental pulp tissues. Anti-M-CSF antibodies significantly inhibited the increase in the number of macrophages in the dental pulp. These results suggest that (1) most of the dental pulp macrophages proliferate and differentiate in the dental pulp without a supply of precursor cells from the blood stream, (2) M-CSF might be a candidate molecule for dental pulp macrophage development, and (3) serum factors might not directly affect the development of macrophages

Discoloration of Coating Resins Exposed to Staining Solution: The Influence of Different Surface Conditions

This study evaluates in vitro the effects of discoloration induced by coating resins under various polymerization conditions. Two coating resins (WTC and BTC) were used. Disk specimens (diameter: 15.0 mm;thickness: 0.7 mm) were used uncoated, coated with a polyethylene film, or coated with an application of TopCoat for WTC or GlossRefine for BTC. Five specimens were immersed for 72 h in a staining solution of either coffee or water. The CIELAB coordinates (L*, a*, b*) of each specimen were measured against a black background using a colorimeter (Shade Eye, NCC) and the color difference [ΔE] was estimated and analyzed by one-way ANOVA and Tukey comparison. The specimen surfaces were observed by FE-SEM. The results reveal that for both materials, the uncoated group had the highest ΔE values (p3.6). Coffee discolored the coating resins. Oxygen inhibition significantly affected the discoloration of the coating resins. We propose applying a coating agent for WTC and a glazing agent for BTC to suppress discoloration of coating resins

How reliable are failure site assessments after "macro" shear debonding of resin from tooth substrate?

Objective: To determine inter-examiner reliability and concordance of failure pattern assessments made by stereomicroscopy and SEM, respectively, after macro shear bond testing of bonded resin composite from human enamel and dentin.Method: Six investigators examined independently the failure pattern morphology of 184 debonded tooth side specimens using stereomicroscopy inspection at 20-fold magnification. The same specimens were investigated using SEM at 1000-fold magnification to determine the "true" failure site morphology. Failures were classified as 1=adhesive, 2=mixed (adhesive-cohesive), 3=cohesive in resin, 4=cohesive in tooth, 5=mixed cohesive (resin-tooth).Results: Spearman’s rho coefficients of correlation between the paired examiner score allocations differed between "strong disagreement" and "moderate agreement". Comparisons of each examiner's ratings with the SEM ratings revealed coefficients, describing these relationships as“disagreement"in the worst and“moderate agreement" in the best case.Conclusion: Inter-examiner reliability in fracture pattern characterization of tooth specimens is ambiguous and not concordant with fracture pattern morphology rating using SEM

Mineral volume versus BMD range as a function of time.

<p>Mineral distribution of BMD range 2500–3200 mg/cm³ of hydroxyapatite within the ROI of (a) control and (b) treated sample. Mean values (n = 5) of mineral volume (mm³ of hydroxyapatite) between the range 2500 mg/cm³ and 3200 mg/cm³ of hydroxyapatite (2500–3200 mg/cm³ then 2600–3200 mg/cm³ up to 3100–3200 mg/cm³) within the ROI are shown.</p

Mean BMD within the ROI.

<p>(a) Mean BMD (mg/cm³ of hydroxyapatite) within the ROI of control and (b) treated enamel. Results are mean±SD of each result (n = 5), and analyzed by analysis of variance (ANOVA) with a follow-up Tukey test.</p

Three-dimensional visualization of the ROI.

<p>(a) Color gradation due to the different BMD range 2500–3200 mg/cm³ of hydroxyapatite of the untreated sample. (b, c) BMD range 2500–2600 mg/cm³ mineral within the ROI of the sample and after exposure to hydrogen peroxide with an energizing source. (d, e) Preferential mineralization of the deeper region (BMD range 2500–2600 mg/cm³) of treated enamel was generated after exposure to artificial saliva for 1 d. (f) Enhanced mineralization was seen in the outer portion (BMD range 2900–3200 mg/cm³) of the treated sample submerged in artificial saliva for 1 wk; 255-colour gradation of different BMD was assigned according to intensity.</p