Effect of different concentrations of fluoride in dentifrices on dentin erosion subjected or not to abrasion in situ/ex vivo

This in situ/ex vivo study assessed the effect of different concentrations of fluoride in dentifrices on dentin subjected to erosion or to erosion plus abrasion. Ten volunteers took part in this crossover and double-blind study performed in 3 phases (7 days). They wore acrylic palatal appliances containing 4 bovine dentin blocks divided in two rows: erosion and erosion plus abrasion. The blocks were subjected to erosion by immersion ex vivo in a cola drink (60 s, pH 2.6) 4 times daily. During this step, the volunteers brushed their teeth with one of three dentifrices D (5,000 ppm F, NaF, silica); C (1,100 ppm F, NaF, silica) and placebo (22 ppm F, silica). Then, the respective dentifrice slurry (1: 3) was dripped on dentin surfaces. While no further treatment was performed in one row, the other row was brushed using an electric toothbrush for 30 s ex vivo. The appliances were replaced in the mouth and the volunteers rinsed with water. Dentin loss was determined by profilometry and analyzed by 2-way ANOVA/Bonferroni test (alpha = 0.05). Dentin loss after erosive-abrasive wear was significantly greater than after erosion alone. Wear was significantly higher for the placebo than for the D and C dentifrices, which were not significantly different from each other. It can be concluded that the presence of fluoride concentrations around 1,100 ppm in dentifrices is important to reduce dentin wear by erosion and erosion + abrasion, but the protective effect does not increase with fluoride concentration. Copyright (C) 2008 S. Karger AG, Basel.

Effects of Erosive, Cariogenic or Combined Erosive/Cariogenic Challenges on Human Enamel An in situ/ex vivo Study

Individuals with cariogenic diet can also consume erosive beverages. Thus, it seems necessary to investigate a possible caries/erosion interaction. To test in situ/ex vivo a combination of these challenges, 11 subjects wore intraoral appliances containing four enamel blocks randomly assigned. In the first 2-week phase, the appliances were immersed in a cola drink 3 times/day. Two blocks were free of plaque (erosion only: EO) and two blocks were covered with plaque (erosion + plaque: EP). In the second 2-week phase, four new blocks were all covered with plaque and subjected to a sucrose solution 8 times/day. Among the four new blocks, two were also subjected to the cola drink 3 times/day (erosion + caries: EC) while the other two were not (caries only: CO). Thus, in EO, the specimens were fixed at the intraoral appliance level. In EP, EC and CO they were fixed 1.0 mm under the appliance level and covered with plastic meshes for dental plaque accumulation. Changes in wear and hardness were measured. Data were tested using ANOVA and Tukey`s test (p < 0.05). Mean values of wear (mu m) and change in hardness (kp/mm(2)) were: EO 4.82/310; EP 0.14/48; EC 0.34/245; CO 0.42/309. With respect to surface softening, EP and EC differed significantly from each other and from EO and CO, which did not differ significantly. EO presented significantly higher wear than the other groups. The data suggest that the presence of dental plaque can decrease the acid attack of an erosive drink and the association of erosive and cariogenic challenges showed less enamel alterations when compared to erosive or cariogenic challenges only. Copyright (C) 2008 S. Karger AG, Basel

Tooth abnormalities and soft tissue alterations in patients with G/BBB syndrome

OBJECTIVE: The G/BBB syndrome is an X-linked recessive disorder characterized by eye anomalies, laryngotracheoesophageal cleft, congenital heart disease, genitourinary anomalies and gastrointestinal disorders. Patients may also present cleft lip and palate, high-arched palate and thin upper lip. This study aimed to investigate the occurrence of tooth abnormalities and soft tissue changes in patients with G/BBB syndrome. DESIGN: Cross-sectional. SUBJECTS AND METHODS: Twenty-one patients with G/BBB syndrome were analyzed as to the presence of tooth abnormalities and soft tissue alterations. MAIN OUTCOME MEASURES: The prevalence of tooth agenesis and supernumerary teeth was compared to patients without morphofunctional alterations, matched for gender and age. RESULTS: All patients had complete cleft lip and palate; 95.23% of patients presented tooth abnormalities, mainly hypoplastic alterations, with predominance of alterations of number, followed by alterations of structure, shape and position. The frequency of tooth agenesis and supernumerary teeth was significantly higher compared with the control group; 11 patients presented incisiform supernumerary teeth in the mandibular anterior region. Ankyloglossia was observed in 11 of 21 patients. CONCLUSION: The presence of mandibular anterior supernumerary teeth and ankyloglossia should be investigated in the clinical evaluation of patients with suspected diagnosis of the G/BBB syndrome. Oral Diseases (2008) 14, 747-753

Tooth abnormalities and soft tissue changes in patients with velocardiofacial syndrome

Objective. The objective of this study was to investigate the prevalence of tooth abnormalities and soft tissue changes in patients with velocardiofacial syndrome. Study design. Twenty-six patients with velocardiofacial syndrome were examined to investigate the presence of tooth abnormalities and soft tissue alterations. The occurrence of tooth agenesis and supernumerary teeth was compared to patients without morphofunctional alterations, matched for gender and age. Results. Of all patients, 76.92% exhibited at least one tooth abnormality, with predominance of hypoplastic alterations, especially represented by hypodevelopment of the lingual cusp of mandibular first premolars and enamel opacities. The occurrence of tooth agenesis and supernumerary teeth was similar in both study and control groups. Conclusion. the present results suggest an association between hypodevelopment of the lingual cusp of mandibular first premolars and enamel opacities, yet these findings still require corroboration. Future studies should further investigate these aspects in larger samples compared to control groups, as well as employing molecular genetics techniques.

An in situ/ex vivo comparison of the ability of regular and light colas to induce enamel wear when erosion is combined with abrasion

Objective: To evaluate whether the type of cola drink (regular or diet) could influence the wear of enamel subjected to erosion followed by brushing abrasion, Method and !Materials: Ten volunteers wore intraoral devices that each had eight bovine enamel blocks divided into four groups; ER, erosion with regular cola; EAR, erosion with regular cola plus abrasion; EL, erosion with light cola; and EAL, erosion with light cola plus abrasion, Each day for 1 week, half of each device was immersed in regular cola for 5 minutes, Then, two blocks were brushed using a fluoridated toothpaste and electric toothbrush for 30 seconds four times daily, Immediately after, the other half of the device was subjected to the same procedure using a light cola, The pH, calcium, phosphorus, and fluoride concentrations of the colas were analyzed using standard procedures, Enamel alterations were measured by profilometry. Data were tested using two-way ANOVA and Bonferroni test (P < .05), Results: Regarding chemical characteristics, light cola presented pH 3.0, 13.7 mg Ca/L, 15.5 mg P/L, and 0.31 mg F/L, while regular cola had pH 2.6, 32.1 mg Ca/L, 1:8.1 mg P/L, and 0.26 mg F/L, The light cola promoted less enamel loss (EL, 0.36 pm; EAL, 0.39 pm) than its regular counterpart (ER, 0.72 pm; EAR, 0.95 pm) for both conditions, There was not a significant difference (P > .05) between erosion and erosion plus abrasion for light cola, However, for regular cola, erosion plus abrasion resulted in higher enamel loss than erosion alone,.nclusion: The data suggest that light cola promoted less enamel wear even when erosion was followed by brushing abrasion, (Quintessence Int 2011;42:xxx-xx)()

Integrating the tourism industry: problems and strategies

This paper addresses two interrelated issues in tourism development: horizontal integration within tourism's component sectors and attempts at vertical integration between them. The paper employs a conceptual framework adapted from regulation theory, to assess the dynamics of these processes, particularly in relation to airlines and hotels. Through examining some of the most important examples of both horizontal and vertical integration, it indicates how these have influenced contemporary strategies in the component sectors. The paper goes on to illustrate how trends towards Fordist organization within airlines have conflicted with post-Fordist trends in hotel operations, to undermine attempts at vertical integration across the tourism industry. (C) 2000 Elsevier Science Ltd. All rights reserved.

Least-Cost Planning and electricity industry reform in Australia

Least-Cost Planning played a key role in the development of the energy efficiency and renewable energy industries in the USA, It has not been widely used elsewhere, largely due to differences in other nations' regulatory environments and the emergence of competitive markets as the dominant paradigm for electricity planning, Least-Cost Planning, however may over valuable insights for creating regulatory framework for competitive electricity markers. This paper examines some lessons which may be extracted from an analysis of the Least-Cost Planning experience in the USA and suggests how these lessons might prove beneficial in guiding Australia's electricity industry reform, This analysis demonstrates how market-based reforms may be flawed if they ignore the history of previous reform processes.

The effect of incentive reforms upon productivity: Evidence from the Vietnamese rice industry

In this study we use region-level panel data on rice production in Vietnam to investigate total factor productivity (TFP) growth in the period since reunification in 1975. Two significant reforms were introduced during this period, one in 1981 allowing farmers to keep part of their produce, and another in 1987 providing improved land tenure. We measure TFP growth using two modified forms of the standard Malmquist data envelopment analysis (DEA) method, which we have named the Three-year-window (TYW) and the Full Cumulative (FC) methods. We have developed these methods to deal with degrees of freedom limitations. Our empirical results indicate strong average TFP growth of between 3.3 and 3.5 per cent per annum, with the fastest growth observed in the period following the first reform. Our results support the assertion that incentive related issues have played a large role in the decline and subsequent resurgence of Vietnamese agriculture.

The effect of soft tissue deloading tape on thoracic spine pressure pain thresholds in asymptomatic subjects

The application of tape to deload soft tissue is used in the management of thoracic spine pain. A reported clinical feature of this treatment is reduced tenderness of the spine during postero-anterior mobilizations. A randomized, single blind, placebo controlled, repeated measures design study was employed to investigate the effects of deloading tape on pressure pain threshold measurements at the level of the T7 spinous process in an asymptomatic group of 24 subjects. Pressure pain thresholds were assessed prior to and following the application of deloading tape, placebo sham tape and no-tape control conditions. All subjects received all three conditions in a randomized order on three separate days. Differences between the pre- and post-measurements were used as indicators of change in a subject's pressure pain threshold. No significant change in pressure pain threshold measurements was found between conditions. In summary, this study demonstrated that deloading tape applied to the level of the T7 spinous process did not significantly change pressure pain threshold measurements in asymptomatic subjects, raising the possibility that any pain relieving effect may well be conditional upon pain being present. (C) 2002 Elsevier Science Ltd. All rights reserved.