Thickness of softened human enamel removed by toothbrush abrasion: an in vitro study

The aim of the study was to assess the thickness of softened enamel removed by toothbrushing. Human enamel specimens were indented with a Knoop diamond. Softening was performed with citric acid or orange juice. The specimens were brushed in a brushing machine with a manual soft toothbrush in toothpaste slurry or in artificial saliva. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% confidence interval) were recorded in treatment groups (in nanometers): (1) citric acid, abrasion with slurry = 339 (280-398); (2) citric acid, abrasion with artificial saliva = 16 (5-27); (3) orange juice, abrasion with slurry = 268 (233-303); (4) orange juice, abrasion with artificial saliva = 14 (5-23); (5) no softening, abrasion with slurry = 28 (10-46). The calculated thickness of the softened enamel varied between 254 and 323 nm, depending on the acid used.

Factors predicting prognosis and recurrence in patients with esophago-gastric adenocarcinoma and histopathological response with less than 10 % residual tumor

PURPOSE: Neoadjuvant treatment is an accepted standard approach for treating locally advanced esophago-gastric adenocarcinomas. Despite a response of the primary tumor, a significant percentage dies from tumor recurrence. The aim of this retrospective exploratory study from two academic centers was to identify predictors of survival and recurrence in histopathologically responding patients. METHODS: Two hundred thirty one patients with adenocarcinomas (esophagus: n = 185, stomach: n = 46, cT3/4, cN0/+, cM0) treated with preoperative chemotherapy (n = 212) or chemoradiotherapy (n = 19) followed by resection achieved a histopathological response (regression 1a: no residual tumor (n = 58), and regression 1b < 10 % residual tumor (n = 173)). RESULTS: The estimated median overall survival was 92.4 months (5-year survival, 56.6 %) for all patients. For patients with regression 1a, median survival is not reached (5-year survival, 71.6 %) compared to patients with regression 1b with 75.3 months median (5-year survival, 52.2 %) (p = 0.031). Patients with a regression 1a had lymph node metastases in 19.0 versus 33.7 % in regression 1b. The ypT-category (p < 0.001), the M-category (p = 0.005), and the type of treatment (p = 0.04) were found to be independent prognostic factors in R0-resected patients. The recurrence rate was 31.7 % (n = 66) (local, 39.4 %; peritoneal carcinomatosis, 25.7 %; distant metastases, 50 %). Recurrence was predicted by female gender (p = 0.013), ypT-category (p = 0.007), and M-category (p = 0.003) in multivariate analysis. CONCLUSION: Response of the primary tumor does not guarantee recurrence-free long-term survival, but histopathological complete responders have better prognosis compared to partial responders. Established prognostic factors strongly influence the outcome, which could, in the future, be used for stratification of adjuvant treatment approaches. Increasing the rate of histopathological complete responders is a valid endpoint for future clinical trials investigating new drugs.

Cyclooxygenase-2 inhibition selectively attenuates bone morphogenetic protein-6 synthesis and bone formation during guided tissue regeneration in a rat model

OBJECTIVES: Bone formation during guided tissue regeneration is a tightly regulated process involving cells, extracellular matrix and growth factors. The aims of this study were (i) to examine the expression of cyclooxygenase-2 (COX-2) during bone regeneration and (ii) the effects of selective COX-2 inhibition on osseous regeneration and growth factor expression in the rodent femur model. MATERIAL AND METHODS: A standardized transcortical defect of 5 x 1.5 mm was prepared in the femur of 12 male rats and a closed half-cylindrical titanium chamber was placed over the defect. The expression of COX-2 and of platelet-derived growth factor-B (PDGF-B), bone morphogenetic protein-6 (BMP-6) and insulin-like growth factor-I/II (IGF-I/II) was analyzed at Days 3, 7, 21 and 28 semiquantitatively by reverse transcriptase-polymerase chain reaction and immunohistochemistry. The effects of COX-2 inhibition by intraperitoneal injection of NS-398 (3 mg/kg/day) were analyzed in five additional animals sacrificed at Day 14. RESULTS: Histomorphometry revealed that new bone formation occurred in the cortical defect area as well as in the supracortical region, i.e. region within the chamber by Day 7 and increased through Day 28. Immunohistochemical evidence of COX-2 and PDGF-B levels were observed early (i.e. Day 3) and decreased rapidly by Day 7. BMP-6 expression was maximal at Day 3 and slowly declined by Day 28. In contrast, IGF-I/II expression gradually increased during the 28-day period. Systemic administration NS-398 caused a statistically significant reduction (P<0.05) in new bone formation (25-30%) and was associated with a statistically significant reduction in BMP-6 protein and mRNA expression (50% and 65% at P<0.05 and P<0.01, respectively). PDGF-B mRNA or protein expression was not affected by NS-398 treatment. CONCLUSION: COX-2 inhibition resulted in reduced BMP-6 expression and impaired osseous regeneration suggesting an important role for COX-2-induced signaling in BMP synthesis and new bone formation.