Enhanced Delivery of F-, Ca2+, K+, and Na+ Ions into Enamel by Electrokinetic Flows.

As the outermost layer of the tooth crown, dental enamel is the most mineralized tissue in mammals, consisting of hydroxyapatite crystallites separated by long and narrow nanochannels. A major challenge in dentistry is how various molecules can be infiltrated into these nanopores in an efficient and controlled way. Here we show a robust method to transport various ions of interest, such as fluoride (F-), potassium (K+), calcium (Ca++), and sodium (Na+), into these nanopores by electrokinetic flows. It is verified by fluorescence microscopy, laser-scanning confocal microscopy, mass spectrometry, and ion selective electrode technique. Different ions are demonstrated to infiltrate through the entire depth of the enamel layer (~1 mm), which is significantly enhanced penetration compared with diffusion-based infiltration. Meanwhile, transport depth and speed can be controlled by infiltration time and applied voltage. This is the first demonstration of reliably delivering both anions and cations into the enamel nanopores. This technique opens opportunities in caries prevention, remineralization, tooth whitening, and nanomedicine delivery in clinical dentistry, as well as other delivery challenges into various biomaterials such as bones.

Orofacial antinociceptive activity of (S)-(-)-perillyl alcohol in mice: a randomized, controlled and triple-blind study.

This study investigated the antinociceptive effects of (S)-(-)-perillyl alcohol (PA) on orofacial nociception in Swiss male mice using formalin-, capsaicin-, and glutamate-induced pain tests. For each test, eight animals per group were pre-treated intraperitoneally by a blinded investigator with PA (50 or 75mg/kg), morphine, or vehicle (saline+0.2% Tween 80). The treatment was performed before the induction of orofacial nociception by injecting formalin, capsaicin, or glutamate solution into the right area of the upper lip. The orofacial nociceptive behaviour was timed in all tests by an investigator who was blinded to the treatments. The statistical analysis was performed using confidence intervals (CI), the effect size, and power. PA blocked the orofacial nociceptive behaviour at both doses tested (P<0.05) similarly to morphine (P>0.05), in all tests. The effect size was high in the phase 1 formalin test for 50mg/kg PA (95% CI 0.48-2.31, power 84.6%) and 75mg/kg PA (95% CI 0.82-2.76, power 96.2%), in phase 2 for 75mg/kg PA (95% CI 0.44-2.26, power 82.3%), and in the glutamate test for 75mg/kg PA (95% CI 1.11-3.16, power 99.2%). These findings show strong evidence for the antinociceptive properties of PA in the orofacial region.

Osteonecrosis of the jaw induced by receptor activator of nuclear factor-kappa B ligand (Denosumab) - Review.

BACKGROUND: Denosumab, an anti-resorptive agent, IgG2 monoclonal antibody for human Receptor activator of nuclear factor-kappa B ligand (RANKL), has been related to the occurrence of osteonecrosis of the jaws. Thus, the aim of this study was to review the literature from clinical case reports, regarding the type of patient and the therapeutic approach used for osteonecrosis of the jaws induced by chronic use of Denosumab. MATERIAL AND METHODS: For this, a literature review was performed on PubMed, Medline and Cochrane databases, using the keywords "Denosumab" "anti-RANK ligand" and "Osteonecrosis of jaw". To be included, articles should be a report or a serie of clinical cases, describing patients aged 18 years or over who used denosumab therapy and have received any therapy for ONJ. RESULTS: Thirteen complete articles were selected for this review, totaling 17 clinical cases. The majority of ONJ cases, patients receiving Denosumab as treatment for osteoporosis and prostate cancer therapy. In most cases, patients affected by ONJ were women aged 60 or over and posterior mandible area was the main site of involvement. Diabetes pre-treatment with bisphosphonates and exodontia were the most often risk factors related to the occurrence of this condition. Systemic and local antibiotic therapy with or without surgical debridement was the most used treatment for ONJ resolution. CONCLUSIONS: It is concluded that the highest number of ONJ cases caused by the use of anti-RANKL agents occurred in female patients, aged 60 years or older, under treatment for osteoporosis and cancer metastasis, and the most affected region was the mandible posterior.

Water loss at normal enamel histological points during air drying at room temperature.

This in vitro study aimed to quantify water loss at histological points in ground sections of normal enamel during air drying at room temperature (25°C) and relative humidity of 50%. From each of 10 ground sections of erupted permanent human normal enamel, three histological points (n = 30) located at 100, 300 and 500 µm from enamel surface and along a transversal following prisms paths were characterized regarding the mineral, organic and water volumes. Water loss during air drying was from 0 to 48 h. Drying occurred with both falling and constant-drying rates, and drying stabilization times (Teq ) ranged from 0.5 to 11 h with a mean 0.26 (±0.12)% weight loss. In some samples (n = 5; 15 points), Teq increased as a function of the distance from the enamel surface, and drying occurred at an apparent diffusion rate of 3.47 × 10⁻8 cm² s⁻¹. Our data provide evidence of air drying resulting in air replacing enamel's loosely bound water in prisms sheaths following a unidirectional water diffusion rate of 3.47 × 10⁻8 cm² s⁻¹ (from the original enamel surface inward), not necessarily resulting in water evaporating directly into air, with important implications for transport processes and optical and mechanical properties.

Natural enamel caries in polarized light microscopy: differences in histopathological features derived from a qualitative versus a quantitative approach to interpret enamel birefringence.

Lesion area measurement of enamel caries using polarized light microscopy (PLM) is currently performed in a large number of studies, but measurements are based mainly on a mislead qualitative interpretation of enamel birefringence in a single immersion medium. Here, five natural enamel caries lesions are analysed by microradiography and in PLM, and the differences in their histopathological features derived from a qualitative versus a quantitative interpretation of enamel birefringence are described. Enamel birefringence in different immersion media (air, water and quinoline) is interpreted by both qualitative and quantitative approaches, the former leading to an underestimation of the depth of enamel caries mainly when the criterion of validating sound enamel as a negatively birefringent area in immersion in water is used (a current common practice in dental research). Procedures to avoid the shortcomings of a qualitative interpretation of enamel birefringence are presented and discussed.