56-month clinical performance of Class I and II resin composite restorations

Objective: This study evaluated the 56-month clinical performance of Class I and II resin composite restorations. Filtek P60 was compared with Filtek Z250, which are both indicated for posterior restorations but differ in terms of handling characteristics. The null hypothesis tested was that there is no difference in the clinical performance of the two resin composites in posterior teeth. Material and Methods: Thirty-three patients were treated by the same operator, who prepared 48 Class I and 42 Class II cavities, which were restored with Single Bond/Filtek Z250 or Single Bond/Filtek P60 restorative systems. Restorations were evaluated by two independent examiners at baseline and after 56 months, using the modified USPHS criteria. Data were analyzed statistically using Chi-square and Fisher's Exact tests (alpha=0.05). Results: After 56 months, 25 patients (31 Class I and 36 Class II) were analyzed. A 3% failure rate occurred due to secondary caries and excessive loss of anatomic form for P60. For both restorative systems, there were no significant differences in secondary caries and postoperative sensitivity. However, significant changes were observed with respect to anatomic form, marginal discoloration, and marginal adaptation. Significant decreases in surface texture were observed exclusively for the Z250 restorations. Conclusions: Both restorative systems can be used for posterior restorations and can be expected to perform well in the oral environment.

Effects of chemical composition on the corrosion of dental alloys

The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.

The 3rd Schizophrenia International Research Society Conference, 14-18 April 2012, Florence, Italy: Summaries of oral sessions

The 3rd Schizophrenia International Research Society Conference was held in Florence, Italy, April 14-18, 2012 and this year had as its emphasis, "The Globalization of Research". Student travel awardees served as rapporteurs for each oral session and focused their summaries on the most significant findings that emerged and the discussions that followed. The following report is a composite of these summaries. We hope that it will provide an overview for those who were present, but could not participate in all sessions, and those who did not have the opportunity to attend, but who would be interested in an update on current investigations ongoing in the field of schizophrenia research. (C) 2012 Elsevier B.V. All rights reserved.

Is missing maxillary lateral incisor in complete cleft lip and palate a product of genetics or local environment?

Objective: To test the null hypothesis: Subjects with isolated complete unilateral cleft lip and palate (UCLP) show no differences in overall frequency of tooth agenesis (hypodontia), comparing a subsample with cleft-side maxillary lateral incisor (MxI2) agenesis to a subsample without cleftside MxI2 agenesis. Findings could clarify the origins of cleft-side MxI2 agenesis. Materials and Methods: Tooth agenesis was identified from dental radiographs of 141 subjects with UCLP. The UCLP cohort was segregated into four categories according to the status and location of MxI2 in the region of the unilateral cleft: group M: subjects with one tooth, located on the mesial side of the alveolar cleft; group D: subjects with one tooth, located on the distal side of the alveolar cleft; group MD: subjects with two teeth present, one mesial and one distal to the cleft; and group ABS: subjects with lateral incisor absent (agenesis) in the cleft area. Results: The null hypothesis was rejected. Among UCLP subjects, there was a twofold increase (P < .0008) in overall frequency of tooth agenesis outside the cleft region in a subsample with cleftside MxI2 agenesis (ABS), compared to a subsample presenting with no agenesis of the cleft-side MxI2 (M+D+MD). Conclusions: Cleft-side MxI2 agenesis in CLP subjects appears to be largely a genetically controlled anomaly associated with cleft development, rather than a collateral environmental consequence of the adjacent cleft defect, since increased hypodontia involving multiple missing teeth observed remote from a cleft clearly has a significant genetic basis. (Angle Orthod. 2012;82:959-963.)

Increase in gastric pH reduces hypotensive effect of oral sodium nitrite in rats

The new pathway nitrate-nitrite-nitric oxide (NO) has emerged as a physiological alternative to the classical enzymatic pathway for NO formation from L-arginine. Nitrate is converted to nitrite by commensal bacteria in the oral cavity and the nitrite formed is then swallowed and reduced to NO under the acidic conditions of the stomach. In this study, we tested the hypothesis that increases in gastric pH caused by omeprazole could decrease the hypotensive effect of oral sodium nitrite. We assessed the effects of omeprazole treatment on the acute hypotensive effects produced by sodium nitrite in normotensive and L-NAME-hypertensive free-moving rats. In addition, we assessed the changes in gastric pH and plasma levels of nitrite, NOx (nitrate+ nitrite), and S-nitrosothiols caused by treatments. We found that the increases in gastric pH induced by omeprazole significantly reduced the hypotensive effects of sodium nitrite in both normotensive and L-NAME-hypertensive rats. This effect of omeprazole was associated with no significant differences in plasma nitrite, NOx, or S-nitrosothiol levels. Our results suggest that part of the hypotensive effects of oral sodium nitrite may be due to its conversion to NO in the acidified environment of the stomach. The increase in gastric pH induced by treatment with omeprazole blunts part of the beneficial cardiovascular effects of dietary nitrate and nitrite. (c) 2012 Elsevier Inc. All rights reserved.