Effect of sono-abrasion in the microleakage of a pit and fissure sealant

PURPOSE

To assess the microleakage of a pit and fissure sealant after preparing enamel with sono-abrasion, used alone or associated with acid etching. This technique was compared with classical enamel preparations i.e. acid etching and diamond bur associated with etching.

MATERIALS AND METHODS

Ninety 3rd molars were used. In the mesial halves, the fissures were prepared with sono-abrasion and acid etching for 15 seconds. Then, the samples were randomly assigned to three groups of 30. They were either treated with acid etching alone (group 1), widened mechanically with a bur and etched for 15 seconds (group 2) or prepared with sono-abrasion alone (group 3). Then, the resin-based sealant was applied according to the manufacturer's recommendations. The teeth were thermocycled and placed in a 1% solution of methylene blue. The teeth showing microleakage and the means of infiltration were assessed with an image analysis system.

RESULTS

The poorest results were obtained with sono-abrasion alone which showed a greater number of specimens with microleakage (73.3%) (p < 0.001). They also showed the highest mean of microleakage (0.85+/-0.79 mm vs 0.1+/-0.26 for acid; 0.35+/-0.85 for bur associated with etching p < 0.0001); and 0.19+/-0.45 for sono-abrasion associated with etching.

CONCLUSION

No significant difference was noted between the three types of enamel preparation using etching. Sono-abrasion can be used for preparing dental enamel prior to sealing the tooth but it does not eliminate the need for etching.

In vitro action of Bordeaux red wine on the microhardness of human dental enamel

Several studies have demonstrated that the regular and large consumption of wine is associated with increased risk of tooth erosion. Here, the effect of Bordeaux red wine on enamel was estimated by measuring changes in its Vickers microhardness. Thirty premolars were used; microhardness tests were performed on buccal areas before and after 10, 30, 90 and 120 s immersion in the wine (pH=3.9). Enamel surfaces were also observed by scanning electron microscopy. No statistically significant difference was found between the mean Vickers microhardness obtained at t=0 and 90 s, but slight signs of enamel demineralisation were observed with the scanning electron microscope. It appears that wine has no disastrous effect on the microhardness of dental enamel when the two are in contact for less than 90 s. When the exposure is for at least 120 s, it may become harmful, as the decrease in the microhardness of enamel was then significant (P<0.05).

[The French project ETOILE: review of clinical data for light ion hadrontherapy]

The Lawrence Berkeley Laboratory was the pioneer in light ions hadrontherapy with almost 2500 patients treated between 1957 and 1993 with Helium and Neon. The NIRS (National Institute For Radiological Science, Chiba, Japan) was the first dedicated medical centre for cancer with more than 1200 patients exclusively treated with carbon ion from 1994. A three-year 70 to 100% local control was reported for radio-resistant cancers, supporting the use of high LET particles. Hypo-fractionation was particularly explored for lung cancers and hepatocarcinoma (4 sessions only). Dose escalation studies demonstrated a tumour dose-effect and permitted to precise dose constraints for healthy tissues especially for the rectum. More than 140 patients were treated with carbon ion exclusively or associated with photons since 1997 in the GSI laboratory Gesellschaft Für Schwerionenforschung, Darmstadt, Germany). A very high local control was also obtained for radioresistant cancer of the base of the skull. Preliminary clinical data seem to confirm the expected therapeutic gain with light ions, due to their ballistic and radio-biological properties, and justify the European projects for the construction of dedicated medical facilities for cancers. The French "Etoile" project will be integrated in the European hadrontherapy network "Enlight", with the objectives to coordinate technologic, medical and economic features.

[Transmandibular buccopharyngectomy after radiotherapy for orpharyngeal cancer]

MATERIALS & METHODS

We present a retrospective study of 95 patients with recurrence of oropharyngeal carcinoma after exclusive radiotherapy. The treatment consisted in a salvage composite resection in all cases.

RESULTS & DISCUSSION

Since the use of muscular flaps, the post-operative complications have been relatively minimised but the carcinologic results were disappointing: only 20% of patients were alive free of disease at 5 years. The main prognostic factors for overall survival were the stage rT of the relapse, the histologic invasion of the nodes and the quality of the resection. The anatomic site of relapse did not influence the survival.

CONCLUSION

Our serie confirms the high frequency of second primary tumors in oropharyngeal cancers. Rigorous selection of patients for exclusive radiotherapy is mandatory to decrease the number of relapses and might avoid salvage surgery.

Periapical status, prevalence and quality of endodontic treatment in an adult French population

AIM

The aim of this study was to determine the periapical status and the quality of root-canal treatment amongst an adult population attending the dental school in Nice, France during 1998.

METHODOLOGY

Patients who attended the dental school for the first time during 1998 were included. Panoramic radiographs, taken by a trained radiology assistant, were used in this study. The periapical areas of all teeth with the exception of third molars, were examined and the technical quality of root fillings were evaluated for both apical extension and density. Statistical analyses were conducted using anova, Chi-square, Fisher's PLSD and Cohen's Kappa tests.

RESULTS

The survey involved 344 patients: 180 females and 164 males. Males had significantly fewer natural remaining teeth than females (P<0.03). Similarly, the average number of root-filled teeth was lower for males (P<0.01). Nonroot-filled teeth (n=6126) had significantly fewer signs of periapical pathology than root-filled teeth (n=1429) (1.7% vs. 31.5%, P<0.0001). The majority of root fillings were poorly executed. There was a significant correlation between the presence of periapical pathology and inadequate root-canal fillings (P<0.001).

CONCLUSIONS

The results of the present study indicate that many root-canal treatments were technically unsatisfactory in terms of quality and treatment outcome. There is a need for endodontic retreatment in the population examined.

Acute toxicity of conventional radiation therapy for high-risk prostate cancer in EORTC trial 22863

OBJECTIVES

We analysed the acute toxicity observed in the European Organisation for Research and Treatment of Cancer (EORTC) randomised trial 22863 comparing conventional external irradiation with or without an agonist analogue of gonadotropin-releasing hormone in high-risk prostate cancer patients.

METHODS

Four hundred five patients that received a dose of at least 30 Gy were considered evaluable for acute toxicity assessment. Toxicity was grouped in a few categories: general, genito-urinary, and lower gastro-intestinal. Univariate and multivariate analyses were performed using the World Health Organisation (WHO) toxicity score and grouping together toxicity scores in different bimodal and trimodal groups.

RESULTS

Overall, our data show that age, previous surgery and irradiation dose are important predictive factors for acute toxicity, but not the use of combined hormone therapy. Fifteen percent of patients suffered of moderate to severe acute toxicity (WHO G3-G4). Life threatening toxicity was observed in six cases (1.5%).

CONCLUSIONS

The assessment of toxicity combining in different groups the original five scores scale produced conflicting results similar to those commonly reported in literature. Interpretation of the role of pre-treatment factors with uneven distribution in the study requires careful evaluation. These data obtained with conventional curative irradiation of high-risk prostate cancer patients are proposed for comparison with results achieved using modern state-of-the-art irradiation techniques.

Estimating survival gain for economic evaluations with survival time as principal endpoint: a cost-effectiveness analysis of adding early hormonal therapy to radiotherapy in patients with locally advanced prostate cancer

The problem of estimating expected outcomes for the economic evaluation of treatments for which the outcome of principal interest is (quality adjusted) survival time has so far not received sufficient attention in the literature. The best estimate of expected survival is mean survival time, but with censored survival data, the true survival time for all the subjects is not known, so the mean is not defined.A possible solution to this estimation problem is illustrated by a retrospective cost-effectiveness analysis of the addition of hormonal therapy to standard radiotherapy for patients with locally advanced prostate cancer. A recently proposed method is used to approach the problem caused by censored cost data, and the impact of uncertainty is assessed by bootstrap resampling techniques. Mean survival time is estimated by a restricted means analysis with the time point of restriction determined by statistical criteria. When average total costs and mean survival time is evaluated at this time point of restriction, the result is that the combined therapy (radiotherapy plus hormonal therapy) increases mean survival time by about 1 year, while reducing the costs per patient for the French health insurance system by 12 700 FF. The time point of restriction may also be determined by other criteria and mean survival time may be estimated by extrapolating the survival curves by means of various parametric survival distributions. We show that the exact results of the economic evaluation are decisively determined by the restriction time point chosen and the approach taken to estimate mean survival time.

Modulation of COX-2 expression by statins in human aortic smooth muscle cells. Involvement of geranylgeranylated proteins

Cyclooxygenase (COX)-2 and COX-1 play an important role in prostacyclin production in vessels and participate in maintaining vascular homeostasis. Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, which is crucial in cholesterol biosynthesis. Recently, cholesterol-independent effects of statins have been described. In this study, we evaluated the effect of two inhibitors of HMG CoA reductase, mevastatin and lovastatin, on the production of prostacyclin and the expression of COX in human aortic smooth muscle cells. Treatment of cells with 25 microm mevastatin or lovastatin resulted in the induction of COX-2 and increase in prostacyclin production. Mevalonate, the direct metabolite of HMG CoA reductase, and geranylgeranyl-pyrophosphate reversed this effect. GGTI-286, a selective inhibitor of geranylgeranyltransferases, increased COX-2 expression and prostacyclin formation, thus indicating the involvement of geranylgeranylated proteins in the down-regulation of COX-2. Furthermore, Clostridium difficile toxin B, an inhibitor of the Rho GTP-binding protein family, the Rho selective inhibitor C3 transferase, and Y-27632, a selective inhibitor of the Rho-associated kinases, targets of Rho A, increased COX-2 expression whereas the activator of the Rho GTPase, the cytotoxic necrotizing factor 1, blocked interlukin-1alpha-dependent COX-2 induction. These results demonstrate that statins up-regulate COX-2 expression and subsequent prostacyclin formation in human aortic smooth muscle cells in part through inhibition of Rho.

Curved molar root canal preparations using Hero 642 rotary nickel-titanium instruments

AIM

The Bramante method was used to study how the natural curvature of root canals was modified when using the Hero 642 nickel-titanium rotary system.

METHODOLOGY

Twenty-four canals were selected in freshly extracted human mandibular molars. Every root canal had an angle of curvature greater than 20 degrees. Roots were embedded in clear casting resin using a plaster mould. Cross-sectional cuts were made in the apical, middle and coronal thirds of each root. A first group (control) of 12 curved root canals was prepared using stainless steel hand instruments and the step-back technique. A second group of 12 curved root canals was instrumented using the Hero sequence according to the manufacturer's instructions. For each sectioning level, the amount of dentine removed, the change of shape factor and the canal centre displacement were calculated with the aid of a digital image analysis system. The results were subjected to the Mann-Whitney U-test.

RESULTS

No significant difference occurred in the amount of dentine removed, change of shape factor or canal centre displacement in the coronal and middle thirds of the curved canals. In the apical third, transportation was significantly higher (P=0.0171) with stainless steel hand instruments than with the Hero system.

CONCLUSIONS

The original canal shape was maintained better in the apical third of curved canals when using the Hero system in a crown-down technique when compared to a hand preparation technique with stainless steel instruments.

Odontometrical method useful in determining gender and dental alignment

Rao et al.'s method of sex determination, which considers the mandibular canine index (MCI) is one giving satisfactory results. However, they did not take occlusion into consideration. The aim of this study, therefore, was to evaluate the effectiveness of this method with respect to tooth alignment. The study population involved the students enrolled in the University of Nice-Sophia Antipolis. Two hundred and ten girls and 214 boys were randomly sampled (1/20). Both tooth sizes and dental arches were measured using a vernier calliper to calculate MCI for both sexes. The results were compared to standard MCI, taking into account tooth alignment.Rao et al.'s method can only be used in the case of correct lower-anterior dental alignment and by using the standard MCI of the local population.

Cost-effectiveness of the addition of early hormonal therapy in locally advanced prostate cancer: results decisively determined by the cut-off time-point chosen for the analysis

We present a retrospective cost-effectiveness analysis using data from a randomised controlled trial (EORTC 22863) of the addition of early hormonal therapy with a luteinising hormone-releasing hormone (LHRH) analogue to radiotherapy in the treatment of patients with locally advanced prostate cancer. Data on the use of medical resources were extracted from the hospital charts of 90 patients recruited into the trial by one French hospital. Costs are assessed from the viewpoint of the French healthcare financing system and adjusted for censoring. Expected costs per patient of each treatment is related to the expected outcome, mean survival time, estimated by a restricted means analysis. The time point of restriction is determined by statistical criteria. In the base case analysis with a cut-off time point at 8.58 years, the combined therapy group (COMB) had a gain in mean survival time of 1.06 years (7.05 versus 5.99 years) and a reduction of average total costs of 12700 French francs (FF) (58300 FF versus 71000 FF). The analysis of uncertainty uses bootstrap techniques with 5000 replicates to examine the joint distribution of cost and survival outcomes. In 76% of the cases, COMB results in longer mean survival time and lower costs than the radiotherapy group (RT). In cases where COMB therapy raises costs (13% of the cases), it is rarely by more than 20000 FF per patient, no matter the size of the associated survival gain. It is thus highly likely that COMB should be considered a cost-effective option compared with RT for these patients. The exact result of the economic evaluation is decisively determined by the restriction time point selected for the determination of mean survival time, partly also because the average total costs of the two treatments develop entirely differently as a function of the survival time.

Apolipoprotein E4 and coronary heart disease in middle-aged men who smoke: a prospective study

BACKGROUND

The common isoforms of apolipoprotein E (apoE), E2, E3, and E4, are important determinants of plasma lipid concentrations, and the epsilon4 allele is associated with raised risk of coronary heart disease. We investigated whether the effect of smoking on coronary heart disease risk is affected by APOE genotype.

METHODS

We enrolled 3052 middle-aged men who were free of coronary heart disease for prospective cardiovascular surveillance in the second Northwick Park Heart Study (NPHSII). Smoking habit was ascertained at baseline and yearly by questionnaire. APOE genotype was identified by PCR and restriction enzyme digestion. Endpoints were fatal coronary heart disease, non-fatal myocardial infarction, and coronary artery surgery and silent myocardial infarction at follow-up.

FINDINGS

During 18836 person years of surveillance, 96 men had an acute myocardial infarction, 26 needed coronary artery surgery, and 14 had silent myocardial infarctions. Compared with never-smokers, risk of coronary heart disease in ex-smokers was 1.34 (95% CI 0.86-2.08) and in smokers it was 1.94 (1.25-3.01). This risk was independent of other classic risk factors. In never-smokers, risk was closely similar in men with different genotypes. Risk in men homozygous for the epsilon3 allele was 1.74 (1.10-2.77) in ex-smokers and 1.68 (1.01-2.83) in smokers, whereas in men carrying the epsilon4 allele risk was 0.84 (0.40-1.75) and 3.17 (1.82-5.50), respectively, with no significant differences in risk in the epsilon2 carriers. For the epsilon3 group, the genotype effect on risk was no longer significant after adjustment for classic risk factors (including plasma lipids). However, even after adjustment, smokers who were carriers of the epsilon4 allele, showed significantly raised risk of coronary heart disease compared with the non-smoking group (2.79, 1.59-4.91, epsilon4-smoking interaction p=0.007).

INTERPRETATION

Smoking increases the risk of coronary heart disease in men of all genotypes but particularly in men carrying the epsilon4 allele.

S-phase fraction and DNA ploidy in 633 T1T2 breast cancers: a standardized flow cytometric study

The lack of a standardized methodology for quantifying DNA ploidy and S-phase fraction (SPF) by flow cytometry is hindering routine use of these markers in breast cancer management. In a retrospective clinical multicenter study, we validated a standardized flow cytometry protocol. We tested 633 frozen T(1)T(2), N(0)N(1), M(0) breast tumors obtained in four institutions. Cell preparation was standardized, and precise rules for data interpretation were followed. Three SPF classes were defined on the basis of tertiles after adjustment for ploidy. DNA aneuploidy was observed in 61.0% of cases. No significant difference was observed among centers. Aneuploidy and high SPF were associated with large tumor size, node involvement, high histological grade, and hormone receptor negativity. In the overall population (median follow-up, 69 months), patients with medium and high SPF values had shorter disease-free survival (DFS) than those with low SPF values (P < 0.0001). Ploidy had no significant influence. By Cox analysis, SPF, pN, and estrogen receptor status were independent predictors of DFS (P = 0.0002, P = 0.001, and P = 0.05). In node-negative patients, SPF was the only predictor of DFS (P = 0.01), whereas in node-positive patients, the risk of relapse increased with both high SPF (P = 0.003) and estrogen receptor negativity (P = 0.004). Low SPF values distinguished grade II tumors with a particularly good outcome. Our results strongly support the use of SPF in multicenter studies and clinical trials and suggest that node-negative patients with slowly proliferating tumors do not require systemic adjuvant therapy.

The role of apolipoprotein E in cognitive decline after cardiac operation

BACKGROUND

Recently, Tardiff and colleagues have suggested that the presence of the apolipoprotein E, epsilon4 allele was associated with increased likelihood of cognitive decline after coronary artery bypass grafting. The objective of the current study was to replicate this earlier work using an increased sample size. The increased sample also enabled an analysis by individual genotype in cognitive decline after coronary artery bypass grafting.

METHODS

Apolipoprotein E genotyping was performed on 111 individuals undergoing coronary artery bypass grafting. Each participant underwent a battery of nine neuropsychological tests before operation and 4 to 7 weeks after operation.

RESULTS

Cognitive decline, assessed by both continuous Z change scores and two categoric measures of cognitive deficit, was not significantly associated with either individual apolipoprotein E genotypes or categorization by the presence or absence of the epsilon4 allele. The examination of potential moderating factors did not alter this finding.

CONCLUSIONS

This study suggests that the epsilon4 allele is not associated with cognitive decline in the weeks after coronary artery bypass grafting.