Comparative Study on Color Stability of Denture Reline Polymers when Using Microwave and Chemical Disinfection

This study investigated the color stability of reline resin after two methods of disinfection i.e microwave disinfection and chemical disinfection. A stainless steel moldwith a breakaway compartment (10 mm in diameter by 0.7 mm thickness) was made to fabricate specimens of various resins. Each material was mixed according to manufacturer’s instructions and applied into the mold. Prior to color stability testing, specimenswere cleaned in distilled water for 20 minutes to kill any microorganisms that may had contaminated the discs during fabrication. And then specimens were immersed in Sodium Perborate Monohydrate 200 ml of solution for 15 days and microwaved for 15 days sothat it is comparable to chemical disinfection soaking. The color stability of each specimen was measured again using spectrophotometer and values were obtained. The data of ∆E, ∆L, ∆b, ∆a were analysed by 2 way repeated measures ANOVAs test. Significant statistic changes in color parameters ∆L, ∆a, ∆b of the reline resin DPI, Ufi Gel Hard And Kooliner were observed when dentures were disinfected by Sodium Perborate Monohydrate 2% solutions. The color stability of the reline resin was influenced by time, regardless of disinfection or non disinfection. This can be attributed to bleaching (whitening) effect of reline material. Discoloration Original Research Article of resin based materials may be caused by intrinsic or extrinsic factors. Intrinsic factors are related to internal alterations in material resulting from physicochemical reactions or residual monomer oxidation with time. Thus the initiator, quantity and type of monomer and the polymerisation efficiency can affect the color stability of resin based materials. The color stability deviation value ∆E significantly increased to maximum for chemical disinfectant, least for Control group and intermediate for microwaved group. Ufi Gel showed the highest deviation ∆E and Control Group showed the lowest deviation according to results

A survey among Palestinian dentists regarding preferences over vital and non-vital teeth bleaching: a cross-sectional study.

ABSTRACT Background: With bleaching treatments becoming very popular, assessment was conducted among Palestinian dentists to check their preferences. Objective: To evaluate the preferences of general dentists regarding vital and non-vital tooth bleaching therapies and to investigate whether the time of clinical practice influences these options. Material & methods: A cross-sectional study was conducted among 200 Palestinian dentists. Options regarding bleaching therapies including the first choice of material, technique and clinical practice for vital and non-vital tooth bleaching therapies were included in the 20 item questionnaire. Data were submitted to descriptive analysis and the associations were evaluated using chi-square test (p<0.05) Results: The response rate was 56.7%. In-office therapy (50.9%) was the preferred treatment of choice for the dentists, followed by a combination of in-office and at-home therapies (29.8%); At home therapies were the least preferred (19.3%). Hydrogen peroxide more than 22% was the preferred treatment of choice for vital bleaching therapy (57.9%), whereas the combination of sodium perborate with water or hydrogen peroxide (46.5%) was the preferred treatment of choice for non-vital bleaching. There was a significant association between the time since graduation and the preference for in-office bleaching (P=0.01) and no significant association between the time since graduation and the material used. Conclusion: In-office bleaching was preferred over at-home therapies; HP >22% and sodium perborate with water or HP were chosen as first treatment options to manage discolored vital and non-vital teeth, respectively. The time in clinical practice had an effect only on the choice of vital bleaching technique.

Evaluation of morphological and chemical alterations in enamel, dentin and cementum after internal bleachingtechnique using different bleaching agents / Avaliação das alterações químicas e morfológicas em esmalte, dentina e cemento após clareamento interno usando diferentes clareadores

Objetivo: O objetivo deste estudo foi avaliar as alterações químicas e morfológicas em esmalte, dentina e cemento após clareamento interno utilizando microscopia eletrônica de varredura e espectrometria de energia dispersiva. Materiais e Métodos: Setenta e dois incisivos bovinos foram preparados, cortados e clareados por 7 dias com os seguintes agentes clareadores: PH: gel de peróxido de hidrogênio 35%; PH + PS: gel de peróxido de hidrogênio 35% + perborato de sódio; PC: gel de peróxido de carbamida 37%; PC + PS: gel de peróxido de carbamida 37% + perborato de sódio; PS: perborato de sódio + água; e Controle: água deionizada. Os espécimes foram seccionados e preparados para análise em microscopia eletrônica de varredura e análise dos níveis de cálcio, fósforo, oxigênio e carbono usando espectrometria de energia dispersiva. Resultados: Foi observada uma redução significante nos níveis de cálcio em esmalte após clareamento com PC + PS e PC (p < 0,05). Os níveis de carbono (parte orgânica) foram alterados em esmalte. Uma redução significante nos níveis de cálcio foi encontrada na dentina nos grupos PH + PS, PC e PC + PS. Os níveis de fósforo aumentaram após o uso de PS (p < 0,05) e PC (p < 0,05). Níveis de carbono mostraram pequena variação e a maior quantidade foi encontrada nos grupos PC e PC + PS (p < 0,05), nos outros grupos não houve alteração. Uma redução significante nos níveis de cálcio foram encontradas no cemento no grupo PC + PS (p < 0,05). Conclusão: Alterações em esmalte, dentina e cemento ocorreram após o clareamento e essas alterações foram menos significantes quando utilizado perborato de sódio e água

Objective: The aim of this study was to evaluate the morphological and chemical alterations in enamel, dentin and cementum after internal bleaching using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Material and Methods: Seventy-two bovine incisor teeth were prepared, cut and bleached for 7 days as follows: HP: 35% hydrogen peroxide gel; HP+SP: 35% hydrogen peroxide gel + sodium perborate; CP: 37% carbamide peroxide gel; CP+SP: 37% carbamide peroxide gel + sodium perborate; SP: sodium perborate + water; and control: deionized water. The specimens were sectioned and prepared for morphological analysis under SEM and analysis of calcium, phosphorus, oxygen and carbon levels using EDS. Results: A significant reduction was found in the calcium levels in enamel after treatment with CP + SP and CP (p < 0.05). Carbon (organic part) was hardly altered in enamel. A significant reduction in the calcium levels was found in dentin in Groups HP+SP, CP and CP+SP. Phosphorus levels increased after SP+H20 (p < 0.05) and CP (p < 0.05). Carbon levels showed little variation and the largest amount was found in Groups CP and CP+SP (p < 0.05); in the other groups there was no alteration. A significant reduction in the calcium levels was found in the cementum in Group CP+SP (p < 0.05). Conclusion: Alterations in the enamel, dentin and cementum compositions occurred after bleaching and these alterations showed to be less significant with sodium perborate and water.

Effect of different denture cleansers on surface roughness and microhardness of artificial denture teeth

PURPOSE: The aim of this study was to compare the effects of different denture cleansers on the surface roughness and microhardness of various types of posterior denture teeth. MATERIALS AND METHODS: 168 artificial tooth specimens were divided into the following four subgroups (n=42): SR Orthotyp PE (polymethylmethacrylate); SR Orthosit PE (Isosit); SR Postaris DCL (double cross-linked); and SR Phonares II (nanohybrid composite). The specimens were further divided according to the type of the denture cleanser (Corega Tabs (sodium perborate), sodium hypochlorite (NaOCl), and distilled water (control) (n=14)) and immersed in the cleanser to simulate a 180-day immersion period, after which the surface roughness and microhardness were tested. The data were analyzed using the Kruskal–Wallis test, Conover's nonparametric multiple comparison test, and Spearman's rank correlation analysis (P<.05). RESULTS: A comparison among the denture cleanser groups showed that NaOCl caused significantly higher roughness values on SR Orthotyp PE specimens when compared with the other artificial teeth (P<.001). Furthermore, Corega Tabs resulted in higher microhardness values in SR Orthotyp PE specimens than distilled water and NaOCl (P<.005). The microhardness values decreased significantly from distilled water, NaOCl, to Corega Tabs for SR Orthosit PE specimens (P<.001). SR Postaris DLC specimens showed increased microhardness when immersed in distilled water or NaOCl when compared with immersion in Corega Tabs (P<.003). No correlation was found between surface roughness and microhardness (r=0.104, P=.178). CONCLUSION: NaOCl and Corega Tabs affected the surface roughness and microhardness of all artificial denture teeth except for the new generation nanohybrid composite teeth.

Effect of denture cleansers on surface hardness of resilient denture liners at various time intervals- an in vitro study

PURPOSE: This study was aimed to determine the effect of two chemically distinct denture cleansers and water on the surface hardness of acrylic and silicone based soft denture liners at various time intervals. MATERIALS AND METHODS: Two commonly used commercial resilient liner material were selected based on their chemical composition (silicone- and acrylic-based soft liners) for this investigation. 120 cylindrical specimens were made of 15 mm x 10 mm dimensions (according to ASTM: D-2240-64T) in a custom made metal mold. All specimens were stored in artificial saliva throughout the study. Forty specimens were cleansed daily in 0.5% sodium hypochlorite solution; forty were cleansed in sodium perborate and remaining forty specimens were daily rinsed in water. Testing was done at 1 week, 1 month, 3 months and 6 months for surface hardness using a Shore A Durometer. A mean of 3 reading for each sample was subjected to one-way ANOVA, Post Hoc test and pair-t test for statistical analysis. P values of less than 0.05 were taken as statistically significant. RESULTS: Surface hardness of all the samples was significantly higher after a period of 6 months irrespective of the cleansing treatment. Minor changes were observed between control, sodium hypochlorite and sodium perborate groups with time. Greater change was observed in surface hardness of acrylic-based soft denture liners as compared to silicone-based soft liners for all groups, as time progressed. CONCLUSION: Silicone-based soft denture liners performed significantly better in all cleansing treatments than acrylic-based soft denture liners.

Deslocamento axial de fluido em capilar de vidro, após a reação intracoronária de diversos agentes clareadores / Axial displacement of fluid in glass capillary after intracoronary reaction of several bleaching agents

Introdução e objetivo: Buscou-se quantificar, indiretamente, a liberaçãode oxigênio após a reação química intracoronária, por deslocamentoaxial de fluido em capilares de vidro, adaptados em coroas dentárias.Material e métodos: Coroas bovinas foram acessadas, e foi executadoo tampão cervical e posicionado um capilar de vidro na face externavestibular, contendo um veículo oleoso. Na sequência, foram preparadasquatro associações de clareadores e colocadas em seu interior: G1? perborato de sódio e peróxido de hidrogênio a 3%; G2 ? perborato de sódio e água; G3 ? associação de percarbonato de sódio e peróxidode hidrogênio a 3%; G4 ? associação de percarbonato de sódio eágua destilada. Após serem mantidas por 24 horas, quantificou-se odeslocamento axial do fluido, interpretado como liberação de oxigêniopela reação química. Resultados: Os resultados mostraram umatendência das associações com o peróxido de hidrogênio em promovermaior liberação de oxigênio. Entretanto não houve diferença entre operborato de sódio e o percarbonato de sódio (p > 0,05). Conclusão:Os grupos experimentais não demonstraram diferenças entre si duranteas 24 horas de reação química.

Objective: To indirectly quantify the release of oxygen after intracoronarychemical reaction, by axial displacement of fluid in glass capillariesarranged in dental crowns. Material and methods: Bovine crownswere accessed, the cervical plug was executed and a glass capillarywas placed in the vestibular external face, containing an oily vehicle.Following that, four associations of bleaching were prepared and placedin its interior: G1 ? sodium perborate and hydrogen peroxide 3%; G2? sodium perborate and water, G3 ? sodium percarbonate and hydrogenperoxide 3%; G4 ? sodium percarbonate and distilled water. After beingkept for 24 hours, the axial displacement of the fluid was quantifiedand interpreted as the release of oxygen by the chemical reaction.Results: The results showed a trend of the associations with hydrogenperoxide to promote the release of more oxygen. However, there wasno difference between sodium perborate and sodium percarbonate(p > 0.05). Conclusion: The experimental groups showed no differencesbetween them during the 24 hours of chemical reaction.

Effectiveness of carbamide peroxide and sodium perborate in non-vital discolored teeth

Objective: To evaluate the efficacy of 16% carbamide peroxide gel (CP16%), tetrahydrate sodium perborate (SP) and mixture (CP16% + SP), in walking bleaching of non-vital discolored teeth. Materials and methods: Sixty single-rooted human premolars with intact crowns were used and initial color was assessed using Vita shade guide and standardized photos. The teeth were stained using rabbit fresh blood for 18 days and photos of discolored teeth and color evaluation were performed. The teeth were divided into 4 groups (n= 15), according to bleaching agent used: G1) CP16% gel; G2) CP16% gel + SP; G3) SP + distilled water; G4: control.The bleaching agents were replaced twice at 7-day intervals for 21 days. All teeth were evaluated by two endodontists at days 0, 7, 14 and 21 and the color changes were assessed using Vita shade guide and standardized photos. The results were analyzed byKruskal-Wallis and Dunn’s tests (p=0.05). Results: The experimental groups presented statistically similar bleaching results (p>0.05) at the end of 7, 14 and 21 days. These groups presented significantly higher bleaching efficacy than control group (G4) (p<0.05). The mixture CP16% + SP promoted return of original color in 100% of teeth at the end of 21 days. Conclusion: It was concluded that three bleaching agents were effective in bleaching of stained teeth with blood products, especially at the end of 21 days.

Bleaching effect of carbamide peroxide gel on discolored nonvital teeth / 대한치과보존학회지

The bleaching of discolored nonvital teeth is conservative treatment that satisfy the cosmetic desire. The most common method for this treatment, walking bleaching, is using 30% hydrogen peroxide and sodium perborate. Many alternatives are suggested for preventing the external cervical root resorption that is the common complication of the nonvital teeth bleaching with 30% hydrogen peroxide. The same extent of oxidation reactions as that resulted by the bleaching with the application of 30% hydrogen peroxide and sodium perborate can also be acquired more safely by materials that contain 10% carbamide peroxide, used primarily for the bleaching of vital teeth. Therefore, this study was performed to evaluate the efficacy of 10% and 15% carbamide peroxide bleaching gel in nonvatal teeth bleaching. The internal bleaching of intentionally discolored teeth was performed in vitro with 10% carbamide peroxide (Group 1), 15% carbamide peroxide (Group 2), mixture of distilled water and sodium perborate (Group 3), and mixture of 30% hydrogen peroxide and sodium perborate (Group 4). The bleaching materials were refreshed following 3, 6, 9 and 12 days. To evaluate the bleaching effect, the color change of the crowns was measured at 1, 2, 3, 4, 7 and 15 days of bleaching using the colorimeter. The results were as follows : 1. L* and DeltaE* values were increased with time in all bleaching agents(p<0.01). 2. There was no significant difference in L* and DeltaE* value among bleaching agents. 3. DeltaE* value higher than 3 was shown after 3 days of bleaching with 10% carbamide peroxide gel, 1 day with 15% carbamide peroxide gel, 4 days with mixture sodium perborate and distilled water and 4 days with mixture sodium perborate and 30% hydrogen peroxide, respectively. These results revealed that the use of 10% and 15% carbamide peroxide bleaching gel in non-vital teeth bleaching is as effective as mixture of distilled water and sodium perborate and mixture of 30% hydrogen peroxide and sodium perborate. Accordingly, carbamide peroxide could be used clinically to bleach discolored non-vital teeth.