Reversing the effects of 2% Lidocaine: A randomized controlled clinical trial.

OBJECTIVES: Prolonged soft tissue anesthesia following a dental appointment is a complaint that is frequently reported by patients. Soft tissue anesthesia generally exceeds the duration of pulpal anesthesia by a few hours. This can lead to difficulties with smiling, drinking, speaking and lip/cheek biting following dental appointments. Phentolamine Mesylate (PM) is a pharmacological agent capable of reducing the duration of soft tissue anesthesia following dental treatments. Many clinical trials supporting its efficacy have used sham injections compared to injections with PM. The present study aims to evaluate the effect of PM on the duration of soft tissue anesthesia compared to a control injection of saline water. METHODS: This randomized controlled trial recruited 40 participants above 18 years of age. Following an inferior alveolar nerve block using 1.8 ml of Lidocaine 2%, 1:100 000 epinephrine, participants were randomized into one of 2 groups. The test group received an injection of 0.4 mg PM (OraVerse). Participants in the control group received an injection of sterile saline water. Participants were trained in self-assessing their anesthesia, which they did until return to normal sensation. RESULTS: Thirty-six participants completed the study. PM significantly reduced the duration of soft tissue anesthesia in the lower lip (104 vs 170 min, p = .001), and tongue (83 vs 134 min, p = .004) compared to the control injection. No serious adverse events were encountered. The only adverse events observed were post-operative pain and discomfort. CONCLUSIONS: Phentolamine Mesylate hastens the return to normal soft tissue sensation and function by approximately one hour compared to a control injection of water. CLINICAL SIGNIFICANCE: Phentolamine Mesylate can be considered a safe and effective way of reducing the duration of soft tissue anesthesia following a dental appointment. This controlled clinical trial is registered at the National Institutes of Health (ClinicalTrials.gov) #NCT02861378.

Induction and processing of complex DNA damage in human breast cancer cells MCF-7 and nonmalignant MCF-10A cells.

Oxidatively induced stress and DNA damage have been associated with various human pathophysiological conditions, including cancer and aging. Complex DNA damage such as double-strand breaks (DSBs) and non-DSB bistranded oxidatively induced clustered DNA lesions (OCDL) (two or more DNA lesions within a short DNA fragment of 1-10 bp on opposing DNA strands) are hypothesized to be repair-resistant lesions challenging the repair mechanisms of the cell. To evaluate the induction and processing of complex DNA damage in breast cancer cells exposed to radiotherapy-relevant gamma-ray doses, we measured single-strand breaks (SSBs), DSBs, and OCDL in MCF-7 and HCC1937 malignant cells as well as MCF-10A nonmalignant human breast cells. For the detection and measurement of SSBs, DSBs, and OCDL, we used the alkaline single-cell gel electrophoresis, gamma-H2AX assay, and an adaptation of pulsed-field gel electrophoresis with E. coli repair enzymes as DNA damage probes. Increased levels for most types of DNA damage were detected in MCF-7 cells while the processing of DSBs and OCDL was deficient in these cells compared to MCF-10A cells. Furthermore, the total antioxidant capacity of MCF-7 cells was lower compared to their nonmalignant counterparts. These findings point to the important role of complex DNA damage in breast cancer and its potential association with breast cancer development especially in the case of deficient BRCA1 expression.