Magister Scientiae Dentium - MSc(Dent) / Introduction: Micro-leakage and enamel demineralization is still a major challenge in dental practice. It can lead to formation of demineralization lesions around and beneath the adhesive–enamel interface (Mali et al., 2006). Enamel demineralization adjacent to orthodontic brackets is one of the risks associated with orthodontic treatment. The prevention of demineralization during orthodontic treatment is therefore essential for aesthetic reasons and to circumvent the onset of caries. Aim: To assess micro-leakage and enamel demineralization around orthodontic direct attachments (brackets) using three different orthodontic cements. Materials and methods: In this in-vitro study, intact (non carious) extracted human premolars were used to compare the micro-leakage and enamel demineralization of three different cements (Fuji Ortho LC, Rely X luting 2 and Transbond XT). The dye penetration technique was used to evaluate micro-leakage on extracted human premolars. Micro-hardness testing was performed on 21 teeth to determine enamel demineralization. Sixty teeth were randomly divided into 3 groups of twenty teeth each. Direct attachments were cemented on each tooth using 3 different cements; Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan), (group 1), Rely X luting 2 cement (3M ESPE dental product, USA), (group 2), Transbond XT Light Cure (3M Unitek, Monrovia, Calif), (group 3). After the orthodontic direct attachments were fitted, they were exposed to 500 thermo-cycles between 5°C and 55°C, with a dwell time of 15 seconds in a buffered (pH 7) 1% methylene blue dye solution (Grobler et al, 2007). The specimens were viewed under a stereomicroscope (Nikon, Japan) at magnification of 40 times. Photographs of each specimen were taken with a Leica camera (Leica DFC 290 micro-systems, Germany) fitted onto a stereomicroscope. The ACDsee photo editing programme was used to transfer the photographs to a computer to measure the dye penetration along the enamel–adhesive and adhesive–bracket interfaces, both on the gingival and occlusal edge at × 40 magnification. For the demineralization sample, 21 teeth were divided into 3 groups of seven teeth each, where direct attachments were cemented using each of the 3 cements, group 1, Fuji Ortho LC (GC Fuji II LC GC Corporation Tokyo, Japan); group 2, Rely X luting 2 cement (3M ESPE dental product, USA) and group 3, Transbond XT Light Cure (3M Unitek, Monrovia, Calif). A digital hardness tester with Vickers diamond indenter (Zwick RoellIndentec (ZHV; Indentec UK) was used to measure surface micro-hardness of enamel before and after attaching the brackets. Ten indentations were made on the enamel surface of each tooth before bonding the brackets with a 300g load applied for 15 seconds to establish the baseline hardness value. After de-bonding the brackets, the hardness was measured again in the same area as mentioned above to determine the degree of enamel demineralization (softening). Result: The result showed statistically significantly lower levels of micro-leakage for Transbond XT (P= <0.001). The amount of micro-leakage on the margins was significantly higher in the gingival portion (P <0.05) as compared with the occlusal margin. Enamel micro-hardness tests before bonding using the three different cements showed that the variances are not significantly different (Chi-squared = 3.051, df = 2, p-value = 0.218). However, the micro-hardness tests done after bonding and thermo-cycling was statistically significantly different (Chi-squared = 13.435, df = 2, p-value = 0.001). Clearly, the Transbond XT group had less hardness, implying greater demineralization than the Fuji Ortho LC and Rely X luting 2 groups. Two sample t-tests show that mean value for the Fuji Ortho and Rely X luting 2 were not significantly different from each other (t = -0.636, df = 12, p-value = 0.537). The mean value for Transbond XT differed significantly from both the other two means: Transbond XT vs Fuji Ortho LC (t = 3.249, df = 6.9, p-value = 0.014). Transbond XT vs Rely X luting 2 (t = 3.493, df = 6.8, p-value = 0.011). Conclusions: This study showed that Fuji Ortho LC and Rely X luting 2 show more micro-leakage than Transbond XT. However Transbond XT had significant lower micro-leakage, less hardness (greater demineralization) than the Fuji Ortho LC and Rely X luting 2. This may have been due to the fluoride release which significantly reduces demineralization. Therefore the Fuji Ortho LC and Rely X luting 2 may be recommended for prevention of demineralization during orthodontic treatment.

<p>Aim and Objectives: To assess the effect of bleaching on the marginal integrity of Class V composite resin restorations. To determine the effect of a 6% hydrogen peroxide over the counter and a 38% hydrogen peroxide in-office vital bleaching treatment products on the microleakage of Class V composite restorations.</p>

<p>Aim and Objectives: To assess the effect of bleaching on the marginal integrity of Class V composite resin restorations. To determine the effect of a 6% hydrogen peroxide over the counter and a 38% hydrogen peroxide in-office vital bleaching treatment products on the microleakage of Class V composite restorations.</p>

Magister Scientiae Dentium - MSc(Dent) / Aim and Objectives: To assess the effect of bleaching on the marginal integrity of Class V composite resin restorations. To determine the effect of a 6% hydrogen peroxide over the counter and a 38% hydrogen peroxide in-office vital bleaching treatment products on the microleakage of Class V composite restorations. / South Africa

Die adhäsive Befestigung von keramischen Inlays erfordert viele mühsa-me und zeitintensive Arbeitsschritte. Zudem werden die Dentin-Bonding-Materialien nicht nach den Herstellerangaben verarbeitet, was unter Um-ständen einen negativen Einfluss auf die Randqualität von keramischen Inlays deren Ränder sich im Dentin befinden können, haben kann. Ziel der Untersuchung: In dieser Studie wurde der Einfluss einer verein-fachten Applikationstechnik auf die Randqualität keramischer Inlays un-tersucht. Material und Methode: MOD-Inlaykavitäten mit Präparationsgrenze im Dentin wurden in 32 humane kariesfreie Prämolaren präpariert. Die Prä-molaren wurden zufällig in vier Gruppen geteilt (n=8). In dem Ver-suchsaufbau war ein Untersuchungsparameter das Inlaymaterial (Empress/Cerec) und der andere die Polymerisation des Dentin-Bonding-Materials vor Insertion des Inlays (P+) und nach Insertion des Inlays (P). Alle Inlays wurden mit einem Dualzement (Variolink II) in Kombination mit einem schmelz- und dentinkonditionierenden Universal-Bonding-Material (Etch & Prime 3.0) eingegliedert. Drei Parameter wurden verwandt, um die Qualität der Versorgung zu bestimmen: 1. Die Passung, gemessen durch die Differenz der Einsenktiefe in die Kavität zwischen der Anprobe und nach dem Zementieren, 2. die Randqualität, die mittels quantitativer Randanalyse im SEM bei einer 200fachen Vergrößerung vor und nach Temperaturlastwechsel (2000 mal zwischen 5° und 55° C) durch Replikas aus Epoxydharz bestimmt wurde und 3. die Randdichtheit, überprüft mit einem Farbstoffpenetrationstest (0,5% wässrige Lösung von basischem Fuchsin). Ergebnisse: Die statistische Analyse (ANOVA) ergab: In allen vier Gruppen waren die Inlays nach der Eingliederung > 5µm tiefer in der Kavität, als bei der Anprobe. Das Ergebnis war für die Gruppe Cerec-Inlays bei denen das Dentin-Bonding vor dem Eingliedern nicht polymerisiert wurde signifikant größer. Die statistische Auswertung der Randanalyse nach dem Friedman und Wilcoxon Test ergab für die zervikalen Bereiche für beide getesteten Kriterien keine statistisch signifikanten Unterschiede (p< 0,01). Die Median-werte für alle Gruppen zeigten 100 Prozent klinisch akzeptable Ränder und keine Randspalten. Der Farbstoffpenetrationstest ergab 71 Prozent dichte Ränder im Schmelz und 38 Prozent dichte Ränder im Dentin. Schlussfolgerung: Bei der Verwendung des universal Bonding-Materials ist es möglich, hohe Randqualitäten mit keramischen Inlays im Schmelz und Dentin selbst mit einer vereinfachten Applikationstechnik, zu erzielen. / The adhesive luting technique for ceramic inlays requires a sequence of multiple steps that are cumbersome and time consuming. Furthermore, modifications of dentin bonding procedures may negatively influence the margin quality of ce-ramic inlays with cervical dentin finishing lines. Purpose: The objective of this study was to test the effect of a new, sim-plified procedure for dentin bonding on the margin quality of ceramic inlays. Materials and Methods: Thirty-two MOD inlay cavities with cervical finish-ing lines in dentin were prepared into premolars. They were randomly di-vided into four groups (n = 8): In the balanced design, one parameter was the inlay material (Empress/Cerec) and the other the polymerization of the dentin bonding agent, before insertion of the inlay (P+) and after in-sertion of the inlay (P-). All inlays were inserted with dual cured cement (Variolink II) in combination with an enamel and dentin conditioning uni-versal bonding agent (Etch & Prime 3.0). Three parameters were used to determine the inlay margin quality: (1) the fit, measured by the difference of the insertion depth into the cavity between try-in and cementation, (2) a quantitative margin analysis in the SEM at a magnification of 200xs, be-fore and after thermocycling (2000 times between 5 and 55 degrees cen-tigrade), using epoxy replicas and (3) dye penetration. Results: Statistical analysis using the ANOVA test showed in all four groups the inlays were >5 µm deeper in the cavities than at the try-in ses-sion. This is explained by the substance loss from the etching. The measured difference for Cerec inlays inserted in cavities, where the bond-ing agent was not polymerized prior to insertion, was significantly larger. Statistical interpretation of the margin analysis of the cervical segment using the Friedman and Wilcoxon Test revealed no statistical differences (p< 0.01) for both criteria tested. The median values for all groups were 100% for clinical acceptable margin and 0% for marginal opening. The dye penetration test resulted in 71% of the enamel margins and 38% of the dentin margins. Conclusion: By using the universal bonding agent, high margin qualities on dentin and enamel are obtained with ceramic inlays even with the sim-plified approach.