{"id":{"repo_id":"freiburg-diss","oai_identifier":"oai:freidok.uni-freiburg.de:1433"},"canonical_url":"https://search.dev.ndltd.org/etd/freiburg-diss/oai:freidok.uni-freiburg.de:1433","repository":{"repo_id":"freiburg-diss","name":"University of Freiburg","base_url":"https://freidok.uni-freiburg.de/oai/oai2.php"},"display":{"title":"The effect of two bleaching products on microhardness and surface texture of different dental aesthetic restorative materials","abstract":"In this study, the effect of two different bleaching agents on the microhardness and the surface texture of six different aesthetic restorative materials were evaluated.
Four different composite resins (a hybrid, a flow, a micro-hybrid and a nano-hybrid), an ormocer, and a ceramic, were used and two bleaching agents were tested: hydrogen peroxide 38% and carbamide peroxide 15%.
For the first part of the study, where the microhardness was evaluated, 28 samples were prepared from every material (14 polished and 14 unpolished), except the ceramic (only 14 polished samples). All samples categories were divided in groups, 7 samples each, for every bleaching agent. The bleaching procedure followed.
On the top-surface of every sample, 5 Knoop microhardness measurements were made on every tested time period. For hydrogen peroxide 38%, the tested time periods were: before bleaching, after 15, 30 and 45 min bleaching, 24 hours later and 1 month later. For carbamide peroxide 15% the tested time periods were: before bleaching, after 8 and 56 hours bleaching, 24 hours later and 1 month later. For the second part of the study, where the surface texture was tested, 3 samples of every category and for every time period described above, were prepared respectively.
The statistical analysis showed that the effect of bleaching on microhardness of composite resins and ceramic was not statistically significant (hybrid: p=0,8670>0,05, flow: p=0,9479>0,05, micro-hybrid: p=0,3542>0,05, nano-hybrid: p=0,7665>0,05, ceramic:0,8255>0,05). In contrast, the effect of bleaching on microhardness of ormocer was statistically significant (p=0,0435<0,05).
The SEM evaluations showed slight changes on the surface of the samples. The polished samples were more stable compared to the unpolished ones. The hydrogen peroxide 38% caused more surface changes compared to carbamide peroxide 15%.
In conclusion, bleaching seems to cause slight but not significant changes on the restorative materials. There is no reason to avoid bleaching when composite materials are present in the oral cavity.","abstract_html":"In this study, the effect of two different bleaching agents on the microhardness and the surface texture of six different aesthetic restorative materials were evaluated. <br>Four different composite resins (a hybrid, a flow, a micro-hybrid and a nano-hybrid), an ormocer, and a ceramic, were used and two bleaching agents were tested: hydrogen peroxide 38% and carbamide peroxide 15%. <br>For the first part of the study, where the microhardness was evaluated, 28 samples were prepared from every material (14 polished and 14 unpolished), except the ceramic (only 14 polished samples). All samples categories were divided in groups, 7 samples each, for every bleaching agent. The bleaching procedure followed. <br> On the top-surface of every sample, 5 Knoop microhardness measurements were made on every tested time period. For hydrogen peroxide 38%, the tested time periods were: before bleaching, after 15, 30 and 45 min bleaching, 24 hours later and 1 month later. For carbamide peroxide 15% the tested time periods were: before bleaching, after 8 and 56 hours bleaching, 24 hours later and 1 month later. For the second part of the study, where the surface texture was tested, 3 samples of every category and for every time period described above, were prepared respectively. <br>The statistical analysis showed that the effect of bleaching on microhardness of composite resins and ceramic was not statistically significant (hybrid: p=0,8670>0,05, flow: p=0,9479>0,05, micro-hybrid: p=0,3542>0,05, nano-hybrid: p=0,7665>0,05, ceramic:0,8255>0,05). In contrast, the effect of bleaching on microhardness of ormocer was statistically significant (p=0,0435<0,05). <br>The SEM evaluations showed slight changes on the surface of the samples. The polished samples were more stable compared to the unpolished ones. The hydrogen peroxide 38% caused more surface changes compared to carbamide peroxide 15%. <br>In conclusion, bleaching seems to cause slight but not significant changes on the restorative materials. There is no reason to avoid bleaching when composite materials are present in the oral cavity.","abstract_has_math":false,"creators":["Polydorou, Olga"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Hellwig, Elmar"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T02:22:16Z","subjects":["bleaching","composite","ormocer","microhardness","SEM"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://freidok.uni-freiburg.de/data/1433","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Hellwig, Elmar"]},{"key":"dc:creator","label":"Author","values":["Polydorou, Olga"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["DoctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["bleaching","composite","ormocer","microhardness","SEM"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In this study, the effect of two different bleaching agents on the microhardness and the surface texture of six different aesthetic restorative materials were evaluated.
Four different composite resins (a hybrid, a flow, a micro-hybrid and a nano-hybrid), an ormocer, and a ceramic, were used and two bleaching agents were tested: hydrogen peroxide 38% and carbamide peroxide 15%.
For the first part of the study, where the microhardness was evaluated, 28 samples were prepared from every material (14 polished and 14 unpolished), except the ceramic (only 14 polished samples). All samples categories were divided in groups, 7 samples each, for every bleaching agent. The bleaching procedure followed.
On the top-surface of every sample, 5 Knoop microhardness measurements were made on every tested time period. For hydrogen peroxide 38%, the tested time periods were: before bleaching, after 15, 30 and 45 min bleaching, 24 hours later and 1 month later. For carbamide peroxide 15% the tested time periods were: before bleaching, after 8 and 56 hours bleaching, 24 hours later and 1 month later. For the second part of the study, where the surface texture was tested, 3 samples of every category and for every time period described above, were prepared respectively.
The statistical analysis showed that the effect of bleaching on microhardness of composite resins and ceramic was not statistically significant (hybrid: p=0,8670>0,05, flow: p=0,9479>0,05, micro-hybrid: p=0,3542>0,05, nano-hybrid: p=0,7665>0,05, ceramic:0,8255>0,05). In contrast, the effect of bleaching on microhardness of ormocer was statistically significant (p=0,0435<0,05).
The SEM evaluations showed slight changes on the surface of the samples. The polished samples were more stable compared to the unpolished ones. The hydrogen peroxide 38% caused more surface changes compared to carbamide peroxide 15%.
In conclusion, bleaching seems to cause slight but not significant changes on the restorative materials. There is no reason to avoid bleaching when composite materials are present in the oral cavity.","Ziel der vorliegenden Studie war es, die Wirkung von zwei unterschiedlichen Bleichmitteln auf die Mikrohärte und die Oberflächenstruktur sechs verschiedener Restaurationsmaterialien zu bestimmen.
In dieser Studie wurden vier Komposite (ein Hybrid-, ein Flow-, ein Microhybrid- und ein Nanohybridkomposit) ein Ormocer und eine Keramik in Verbindung zweier Bleichmittel (Opalescence Xtra Boost und Opalescence PF 15%) untersucht.
Für die Untersuchung der Mikrohärte wurden 28 Proben aus jedem Restaurationsmaterial hergestellt (14 poliert und 14 unpoliert). Aus Keramik wurden nur 14 polierte Proben hergestellt. Die Proben jeder Material wurden in zwei Gruppen (eine pro Bleichmittel) eingeteilt. Daraufhin erfolgte die Bleichbehandlung.
Bei jeder Probe wurden fünf Mikrohärte-Messungen zu jedem Prüfungszeitpunkt durchgeführt. Die Prüfungszeitpunkte für Opalescence Xtra Boost waren: vor dem Bleichen, nach 15, 30 und 45 min. Bleichen, sowie 24 Std. und 1 Monat nach dem Bleichen. Die Prüfungszeitpunkte für Opalescence PF 15% waren: vor dem Bleichen, nach 8 und 56 Std. Bleichen, sowie 24 Std. und 1 Monat nach dem Bleichen.
Für die Untersuchung der Oberflächenstruktur wurden drei Proben von jeder Kategorie sowie für jeden Prüfungszeitpunkt (wie oben beschreiben) hergestellt.
Die statistische Analyse zeigte, dass der Einfluss von Bleichmitteln auf die Mikrohärte von Kompositen und Ceramic statistisch nicht signifikant war (Hybrid: p=0,8670>0,05, Flow: p=0,9479>0,05, Microhybrid: p=0,3542>0,05, Nanohybrid: p=0,7665>0,05, KeramiK: p=0,8255>0,05). Der Einfluss des Bleichvorgang auf die Mikrohärte von Ormocer war statistisch signifikant (p=0,0435<0,05).
SEM Beobachtungen zeigten kleine Veränderungen der Oberfläche der Proben. Die polierten Proben waren „stabiler“ als die Unpolierten. Opalescence Xtra Boost hat einen stärkeren Einfluss als Opalescence PF 15% auf die Restaurationsmaterialien.
Schlussfolgernd kann man sagen, dass das Bleichen einen leichten, aber nicht signifikanten Einfluss auf die Restaurationsmaterialien ausübt. Bei vorhandenen Komposit- und Keramik-Restaurationen kann eine Bleichbehandlung durchgeführt werden."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The effect of two bleaching products on microhardness and surface texture of different dental aesthetic restorative materials","Die Wirkung von zwei unterschiedlichen Bleichmitteln auf die Mikrohärte und die Oberflächenstruktur verschiedener Restaurationsmaterialien"]}]}],"canonical_facts":{"dc:contributor":["Hellwig, Elmar"],"dc:creator":["Polydorou, Olga"],"dc:description.abstract":["In this study, the effect of two different bleaching agents on the microhardness and the surface texture of six different aesthetic restorative materials were evaluated.
Four different composite resins (a hybrid, a flow, a micro-hybrid and a nano-hybrid), an ormocer, and a ceramic, were used and two bleaching agents were tested: hydrogen peroxide 38% and carbamide peroxide 15%.
For the first part of the study, where the microhardness was evaluated, 28 samples were prepared from every material (14 polished and 14 unpolished), except the ceramic (only 14 polished samples). All samples categories were divided in groups, 7 samples each, for every bleaching agent. The bleaching procedure followed.
On the top-surface of every sample, 5 Knoop microhardness measurements were made on every tested time period. For hydrogen peroxide 38%, the tested time periods were: before bleaching, after 15, 30 and 45 min bleaching, 24 hours later and 1 month later. For carbamide peroxide 15% the tested time periods were: before bleaching, after 8 and 56 hours bleaching, 24 hours later and 1 month later. For the second part of the study, where the surface texture was tested, 3 samples of every category and for every time period described above, were prepared respectively.
The statistical analysis showed that the effect of bleaching on microhardness of composite resins and ceramic was not statistically significant (hybrid: p=0,8670>0,05, flow: p=0,9479>0,05, micro-hybrid: p=0,3542>0,05, nano-hybrid: p=0,7665>0,05, ceramic:0,8255>0,05). In contrast, the effect of bleaching on microhardness of ormocer was statistically significant (p=0,0435<0,05).
The SEM evaluations showed slight changes on the surface of the samples. The polished samples were more stable compared to the unpolished ones. The hydrogen peroxide 38% caused more surface changes compared to carbamide peroxide 15%.
In conclusion, bleaching seems to cause slight but not significant changes on the restorative materials. There is no reason to avoid bleaching when composite materials are present in the oral cavity.","Ziel der vorliegenden Studie war es, die Wirkung von zwei unterschiedlichen Bleichmitteln auf die Mikrohärte und die Oberflächenstruktur sechs verschiedener Restaurationsmaterialien zu bestimmen.
In dieser Studie wurden vier Komposite (ein Hybrid-, ein Flow-, ein Microhybrid- und ein Nanohybridkomposit) ein Ormocer und eine Keramik in Verbindung zweier Bleichmittel (Opalescence Xtra Boost und Opalescence PF 15%) untersucht.
Für die Untersuchung der Mikrohärte wurden 28 Proben aus jedem Restaurationsmaterial hergestellt (14 poliert und 14 unpoliert). Aus Keramik wurden nur 14 polierte Proben hergestellt. Die Proben jeder Material wurden in zwei Gruppen (eine pro Bleichmittel) eingeteilt. Daraufhin erfolgte die Bleichbehandlung.
Bei jeder Probe wurden fünf Mikrohärte-Messungen zu jedem Prüfungszeitpunkt durchgeführt. Die Prüfungszeitpunkte für Opalescence Xtra Boost waren: vor dem Bleichen, nach 15, 30 und 45 min. Bleichen, sowie 24 Std. und 1 Monat nach dem Bleichen. Die Prüfungszeitpunkte für Opalescence PF 15% waren: vor dem Bleichen, nach 8 und 56 Std. Bleichen, sowie 24 Std. und 1 Monat nach dem Bleichen.
Für die Untersuchung der Oberflächenstruktur wurden drei Proben von jeder Kategorie sowie für jeden Prüfungszeitpunkt (wie oben beschreiben) hergestellt.
Die statistische Analyse zeigte, dass der Einfluss von Bleichmitteln auf die Mikrohärte von Kompositen und Ceramic statistisch nicht signifikant war (Hybrid: p=0,8670>0,05, Flow: p=0,9479>0,05, Microhybrid: p=0,3542>0,05, Nanohybrid: p=0,7665>0,05, KeramiK: p=0,8255>0,05). Der Einfluss des Bleichvorgang auf die Mikrohärte von Ormocer war statistisch signifikant (p=0,0435<0,05).
SEM Beobachtungen zeigten kleine Veränderungen der Oberfläche der Proben. Die polierten Proben waren „stabiler“ als die Unpolierten. Opalescence Xtra Boost hat einen stärkeren Einfluss als Opalescence PF 15% auf die Restaurationsmaterialien.
Schlussfolgernd kann man sagen, dass das Bleichen einen leichten, aber nicht signifikanten Einfluss auf die Restaurationsmaterialien ausübt. Bei vorhandenen Komposit- und Keramik-Restaurationen kann eine Bleichbehandlung durchgeführt werden."],"dc:format.medium":["application/pdf"],"dc:subject":["bleaching","composite","ormocer","microhardness","SEM"],"dc:title":["The effect of two bleaching products on microhardness and surface texture of different dental aesthetic restorative materials","Die Wirkung von zwei unterschiedlichen Bleichmitteln auf die Mikrohärte und die Oberflächenstruktur verschiedener Restaurationsmaterialien"],"dc:type":["DoctoralThesis"]},"updated_at":"2026-07-24T02:22:16Z"}