Carbamide Peroxide Research Articles

The Effect of Carbamide Peroxide Bleaching Gel Containing Remineralization Agents on the Bond Strength of Universal Adhesives to Enamel

The Effect of Carbamide Peroxide Bleaching Gel Containing Remineralization Agents on the Bond Strength of Universal Adhesives to Enamel

Different approaches for aesthetic management of molar-incisor hypo-mineralization: two case reports

Background: Molar-incisor hypo-mineralization (MIH) is a developmental enamel defect that affect one or more permanent first molars, with or without incisor teeth involvement. When incisors are affected, that might lead to aesthetic concerns and consequently, negative impact on the child's quality of life. Hence, this study presented and discussed the conservative treatment modalities for maxillary incisors with discolored enamel defects. Case Presentation: Two 12-year-old female patients was referred from pediatric clinics to treat anterior teeth discolorations after management of affected first molars. In the first case, the defect was more heterogenous with yellow-brownish discoloration. To remove yellow-brownish discoloration, in-office bleaching with 37% hydrogen peroxide was performed, followed by home bleaching with 10% carbamide peroxide for one week. Then, resin infiltration (RI) was performed to seal the porous enamel and to mask the white enamel defects. In the second case, the white opacities were more homogenous, therefore, only RI treatment was applied. Conclusion: Aesthetic management of MIH patients should follow more conservative approaches like dental bleach systems and resin infiltration.

An oxygen-coordinated cobalt single-atom electrocatalyst boosting urea and urea peroxide production

An oxygen-coordinated cobalt single-atom catalyst was successfully fabricated, exhibiting exceptional electrocatalytic activity toward urea and H2O2 production. Subsequently, the value-added urea peroxide was efficiently synthesized.

Assessment of surface roughness and compressive strength of resin-based composite using different types of bleaching protocols.

Background and objective: This study aimed to evaluate the effect of three types of bleaching protocols on the surface roughness and compressive strength of composite resin. Methods: Eighty composite resin samples were prepared using metal molds; forty samples (2 mm in height and 8 mm in diameter) for surface roughness evaluation and the other forty samples (6 mm in height and 4 mm in diameter) for compressive strength. Every forty samples were divided into four groups; Group 1 (n = 10) The samples were stored in deionized water at 37°C for two weeks as control, group 2 (n =10) The samples were subjected to bleaching with 22% Carbamide Peroxide (CP) Home bleaching, group 3 (n =10) The samples were subjected to bleaching with 14% Hydrogen Peroxide (HP) Home bleaching and group 4 (n =10) The samples were subjected to bleaching with 25% Hydrogen Peroxide (HP in-Office) in a dental clinic. After bleaching, groups 2, 3, and 4 were evaluated for surface roughness and compressive strength. Results: The enamel surface roughness of all specimens were increased after bleaching protocols to a very similar extent with no statistically significant difference between the means of enamel roughness of the control group and the other three groups and the highest value was recorded in the Carbamide Peroxide group (CP), while compressive strength of the composite was decreased after using bleaching protocols in all groups in comparison with the control group and the least compressive strength was recorded in (HP) group followed by (HP in-Office) group and (CP) group respectively. Conclusions: Within the limitation of this study, the following conclusions can be drawn: There was a decrease in surface roughness using different types of bleaching protocols (22% CP and 14% HP) at-Home bleaching technique and (25%) in-Office HP bleaching. Although there was no significant difference between them. The compressive strength of the composite resin was reduced after bleaching with no significant difference. Keywords: Bleaching protocol, Hydrogen peroxide, Carbamide peroxide

Effect of the Teeth Whitening Procedure on the Mineral Composition of Oral Fluid.

The basis of modern tooth whitening systems is the use of a whitening gel, which usually contains hydrogen peroxide or carbamide peroxide. The study included 81 patients aged 22 to 35 years with a tooth color A2 and a darker color on the Vita Classic scale. The purpose of our research was to identify a new approach to whitening teeth to improve safety and gentleness. To perform this, we assessed the effect of the tooth whitening procedure on the mineral composition of the oral fluid. A new approach to the teeth whitening procedure was to use a mouth retractor and a tool for aspirating the whitening gel, which we developed. Before the procedure, a protective film-forming aerosol, which included sodium ascorbate, was applied. After the tooth whitening procedure, the enamel was remineralized with a sealing liquid for 14 days. The concentrations of calcium and phosphorus in the oral fluid were determined using a spectrophotometer with a set of reagents (Human). The results obtained indicate that the new approach to the teeth whitening procedure contributed to less pronounced changes in the concentrations of calcium (+29.07, p < 0.001) and phosphorus (-14%, p < 0.001) in the oral fluid immediately after the procedure and in combination with the standard procedure for teeth whitening; immediately after this procedure, the calcium concentration increased by 74.4% (p < 0.001), and the phosphorus concentration decreased by 23.07% (p < 0.001). The use of remineralizing agents led to a faster recovery of the initial levels of calcium and phosphorus in the oral fluid.

Effect of incorporation of calcium polyphosphate sub-microparticles in low-concentration bleaching gels on physical properties of dental enamel.

To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs). A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE00, ΔWID) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE00, and ΔWID, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test. The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05). The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy.

Analysis of critical residues for peroxygenation and improved peroxygenase activity via in situ H2O2 generation in CYP105D18.

Limited numbers of CYPs have been reported to work naturally as peroxygenases. The peroxide shunt pathway can be efficiently used as an alternative for the NAD(P)H and reductase systems, particularly in high hydrogen peroxide (H2O2) resistance CYPs. We reported the structural and biochemical features of CYP105D18 peroxygenase for its high H2O2 tolerance capacity. Q348 was a crucial residue for the stability of CYP105D18 during the exposure to H2O2. In addition, the role of the hydrophilic amino acid T239 from the I helix for peroxygenation and regiospecificity toward testosterone was investigated. Interestingly, T239E differs in product formation from wild type, catalyzing testosterone to androstenedione in the presence of H2O2. The other variant, T239A, worked with the Pdx/Pdr system and was unable to catalyze testosterone conversion in the presence of H2O2, suggesting the transformation of peroxygenase into monooxygenase. CYP105D18 supported the alternative method of H2O2 used for the catalysis of testosterone. The use of the same concentration of urea hydrogen peroxide adducts in place of direct H2O2 was more efficient for 2β-hydroxytestosterone conversion. Furthermore, in situ H2O2 generation using GOx/glucose system enhanced the catalytic efficiency (kcat/Km) for wild type and F184A by 1.3- and 1.9-fold, respectively, compared to direct use of H2O2 The engineering of CYP105D18, its improved peroxygenase activity, and alteration in the product oxidation facilitate CYP105D18 as a potential candidate for biotechnological applications.

The Effect of Strawberries as a Natural Teeth Whitening Agent on Tooth Surface Roughness: In Vitro Study

Teeth whitening due to discoloration can be achieved by methods of bleaching. The material used in bleaching conventional methods can have effects on hard tooth tissue, such as increasing tooth surface roughness. Strawberries (Fragaria x ananassa) have long been known for being effective in whitening teeth. The aim of the research was to determine the effect of strawberries as a natural teeth whitening agent on tooth surface roughness in vitro. This research is an in vitro experiment. The samples were 24 first premolars of the upper jaw and lower jaw, which were divided into two groups. Group 1 (strawberry juice 100%) and group 2 (carbamide peroxide 10%). Testing tooth surface roughness using tools surface roughness tester, then the data was analyzed using statistical test paired t-test and Mann-Whitney. The results of the study showed that the mean and standard deviation of tooth surface roughness before and after application of strawberry fruit juice was 0.37 ± 0.156 and 0.22 ± 0.129, while the 10% carbamide peroxide group obtained the value of tooth surface roughness before and after application was 0.36 ± 0.118 and 0.37 ± 0.263.

Effects of 35% Versus 10% Carbamide Peroxide At-Home Bleaching Agents with or without MI Paste Plus on Enamel Properties

This study compared the effects of 35% with 10% carbamide peroxide (CP) home used bleaching agents on enamel color change, microhardness, and surface changes in association with MI paste plus (CPP -ACPF). Forty buccal and lingual enamel samples from twenty human third molars were prepared and divided into four groups (n=10). The groups were bleached for two weeks according to different bleaching regimens as follow; G1 bleached with 10%CP, G2 bleached with 35%CP, G3 bleached with a mixture of 10%CP and MI paste plus, and G4 bleached with a mixture of 35%CP and MI paste plus. Color change was recorded with a colorimeter before and after bleaching and total color differences (ΔE*) was calculated. Vickers microhardness test was recorded for all the samples before and after treatment. One sample from each group was evaluated for surface changes by scan electron microscopy (SEM). The data were analyzed with repeated measure of variance and student's t-test at p&lt;0.05. No significant difference in ΔE* was recorded among the four groups (p&gt;0.05). Significant reduction in enamel microhardness was only recorded for G2 (p=0.003). SEM for G3 and G4 showed obvious mineral deposition. Similar teeth color whitening can be resulted after two weeks of bleaching with both 10%CP and 35%CP when used as recommended by the manufacturer with and without the addition of MI paste plus. Using 35%CP decreased enamel microhardness significantly, whereas MI paste plus when mixed with both bleaching agents could compensate for the microhardness reduction.

Linking Carbendazim Accumulation with Soil and Endophytic Microbial Community Diversities, Compositions, Functions, and Assemblies: Effects of Urea-hydrogen Peroxide and Nitrification Inhibitors.

Fungicide carbendazim accumulation in soils and plants is a wide concern. Nitrogen (N) is a substantial nutrient limiting crop growth and affecting soil microbial activity and the community in degrading fungicides. We investigated the effects of urea-hydrogen peroxide (UHP) and nitrification inhibitors Dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) on carbendazim accumulation and soil and endophytic microbial communities. The UHP application had negligible influences on soil and plant carbendazim accumulation, but the combined UHP and DCD decreased soil carbendazim accumulation by 5.31% and the combined UHP and DMPP decreased plant carbendazim accumulation by 44.36%. The combined UHP and nitrification inhibitor significantly decreased the ratios of soil Firmicutes and endophytic Ascomycota. Soil microbial community assembly was governed by the stochastic process, while the stochastic and deterministic processes governed the endophyte. Our findings could provide considerable methods to reduce fungicide accumulation in soil-plant systems with agricultural N management strategies.

Effect of Tooth Bleach on Dentin Fatigue Resistance in Situ.

Negative effects of bleaching on dentin have previously been reported in vitro. The purpose of this study was to determine the effect of carbamide peroxide bleaching on dentin fatigue resistance using a clinically relevant in situ model. Following research ethics board approval, 60 human teeth requiring extraction were collected. Sterilized human dentin specimens were cut (1.2×1.2×10 mm) and secured into customized bleaching trays to be used by study participants. Participants were randomly assigned to either bleach (10% carbamide peroxide, n=23) or control (gel without bleach, n=26) treatment groups. Treatment was applied to the bleaching trays and worn overnight by participants for 14 days. After treatment completion, dentin specimens were removed from the bleaching trays and subjected to fatigue testing (10 N, 3 mm/s, 2×105 cycles) while submerged in artificial saliva. Kaplan-Meier survival analysis was conducted to compare the number of cycles to failure during fatigue testing in both groups. A log rank test was run to determine if there were differences in the survival distribution between the two groups (α<0.05). The median number of cycles to failure was 352 ± 202 and 760 ± 644 for the bleach and control groups, respectively. The survival distributions for the two groups were significantly different (p=0.020). Dentin fatigue resistance was significantly lower in the bleach group compared to the control. Direct bleaching of human dentin using an at-home tray bleaching protocol in situ reduced dentin fatigue resistance. This has implications for tooth fracture risk and longevity.

The use of urea hydrogen peroxide as an alternative N-fertilizer to reduce accumulation of arsenic in rice grains

A greenhouse experiment was conducted to examine the effects of urea hydrogen peroxide (UHP) on reducing the accumulation of As in rice grains. The results show that UHP effectively triggered Fenton-like reaction by reacting with Fe2+ in the paddy soils. This significantly inhibited the activities of As(V)-reducing microbes, causing impediment of As(V)–As(III) conversion following inundation of dryland crop soils for paddy rice cultivation. As-methylating microbes were also inhibited, adversely affecting As methylation in the soils. These processes led to the reduction in phyto-availability of As in the soil solutions for uptake by rice plant roots, and consequently reduced the accumulation of As in the rice grains. In this study, an UHP application rate of 0.0625% on three occasions (tillering, heading and filling) during the rice growth period was sufficient to lower the rice grain-borne As concentration to below 0.2 mg/kg, meeting the quality standard set by the Chinese government. No additive effect on reducing grain-borne As was observed for the joint application of UHP and biochar or biochar composite. The use of UHP for soil fertilization had no adverse impact on rice yield in comparison with the application of urea at an equal amount of nitrogen.

Effect of Bleaching on the Microhardness and Modulus of Elasticity of ACTIVA BioACTIVE – RESTORATIVE: An In Vitro Study

Aim: Bleaching is reported to have a deleterious effect on the physical properties of composite material. There is a lack of studies evaluating the effect of bleaching on ACTIVA BioACTIVE – RESTORATIVE. The aim of this study was to evaluate the effects of bleaching on the microhardness and modulus of elasticity of ACTIVA BioACTIVE – RESTORATIVE. Materials and methods: In this in vitro study, the effect of bleaching on two restorative materials was tested. The two restorative materials ACTIVA BioACTIVE – RESTORATIVE and 3M Filtek Z350 Xt were subjected to bleaching with two concentrations of carbamide peroxide (15% and 35%). Measurements of Microhardness and Modulus of elasticity were recorded before and after the bleaching procedure. Data were checked for normality using the Shapiro–Wilk test. Unpaired t test was applied to compare mean of different variables across groups ( p &lt; .0001). Results: The microhardness and modulus of elasticity was higher among the 3M Filtek Z350 Xt group when compared to ACTIVA BioACTIVE – RESTORATIVE. Approximately 35% carbamide peroxide showed the least values when compared to 15% carbamide peroxide. Conclusion: Within the limitation of this study it can be concluded that 15% and 35% carbamide peroxide significantly decreased the Microhardness and Modulus of Elasticity of ACTIVA BioACTIVE – RESTORATIVE and 3M Filtek Z350 Xt. The deleterious effect was concentration dependent as more effect was noted with 35% Carbamide Peroxide. Therefore, patients have to be advised that the existing composite restoration might become softer after bleaching.

Iron-loaded bentonite coupled with urea peroxide to control the escape of trichloroethylene, a representative odorous substance in the restoration site

To effectively control the escape of odorous chemicals like trichloroethylene (TCE) in soil remediation sites, a novel technology for iron-loaded bentonite activated urea peroxide (FBT/UHP) was developed in this study. This was significantly higher than the 51.40% removal in the untreated bentonite and UHP (BT/UHP) system. The stability test revealed that FBT remained stable after five uses. The hydroxyl radical was primarily responsible for the degradation process, accounting for almost 82.74% of total TCE removal. Intermediate identification and theoretical calculations further analyzed the possible degradation pathways of TCE. Intermediate identification combined with theoretical calculation further analyzed the potential degradation pathways of TCE. According to experimental results, the FBT/UHP system decreased the TCE cumulative relative escape rate by almost 91.90%. In summary, the FBT/UHP system shows promising potential for controlling TCE and other odour leakages during soil remediation at pesticide sites.

An In Vitro Study regarding the Wear of Composite Materials Following the Use of Dental Bleaching Protocols.

Composite materials used in dental restorations are considered resistant, long-lasting and aesthetic. As the wear of restorations is an important element in long-term use, the aim of this study was to evaluate the surface condition of nanohybrid and microfilled composite resins, after being subjected to the erosive action of dental bleaching protocols. This paper reflects a comparative study between one nanofilled composite and three microfilled composites used in restorations. For each composite, three sets of samples (under the form of composite discs) were created: a control group, an "office bleach" group with discs bleached with 40% hydrogen peroxide gel, and a "home bleach" group with discs bleached with 16% carbamide peroxide gel. Wear was numerically determined as the trace and the coefficients of friction obtained using a tribometer, the ball-on-disk test method, and two balls: alumina and sapphire. For all composite groups, there were statistically significant differences between the wear corresponding to the control and bleaching groups, for both testing balls. Regarding the composite type, the largest traces were recorded for GC Gradia direct anterior, for all groups, using the alumina ball. In contrast, for the sapphire ball, 3M ESPE Filtek Z550 was characterized by the largest traces. With respect to the friction coefficients, the "office bleach" group recorded the largest values, no matter the composite or the ball type used. The 3M ESPE Valux Plus composite recorded the largest friction coefficients for the alumina ball, and 3M ESPE Filtek Z550 for the sapphire ball. Overall, the "office bleach" group was characterized by higher composite wear, compared to the "home bleach" protocol or control group. Nanofilled composite resins showed superior wear resistance to microfilled resins after undergoing a bleaching protocol.

Dental aesthetic perception of patients submitted to activated charcoal-based bleaching agents: A randomized clinical trial

ObjectiveTo evaluate the effects of activated charcoal-based products used in two presentation forms (powder or toothpaste), compared to 10 % carbamide peroxide and conventional toothpaste on aesthetic perception and psychosocial impact before and after treatment. MethodsFifty-six participants were divided into 4 experimental groups (n = 14). Activated charcoal-based powder (PW); Activated charcoal-based dentifrice (AC); Conventional fluoride toothpaste (CD) and 10 % carbamide peroxide (CP). All products were used for 14 days. Psychosocial impact on dental esthetics (PIDAQ), oral health impact profile (OHIP- Esthetics) and orofacial esthetics scale (OES) questionnaires were applied before and after treatment. Descriptive and exploratory data analyses were performed and analyzed using linear mixed models for repeated measures over time considering significance level of α = 0.05. ResultsFor PIDAQ, the CP group showed significant decrease in psychological impact, aesthetic perception domains and overall score, while in the PW group, there was only a significant decrease in the psychological impact domain. Decrease in OHIP was observed for the functional limitation domain scores for treatments with CP and PW, in the psychological discomfort domain, decrease was observed for all groups, while for the OES questionnaire, significant increase in the color domain was observed for the CP group. ConclusionActivated charcoal-based products showed lower scores in all questionnaires when compared with carbamide peroxide; thus, charcoal-based products promoted lower impact on quality of life and aesthetic perception. Clinical relevanceIn this randomized clinical trial, charcoal-based OTC products had inferior quality of life and aesthetic perception results compared to conventional carbamide peroxide bleaching.

Development of an Efficient On-Tissue Epoxidation Reaction Mediated by Urea Hydrogen Peroxide for MALDI MS/MS Imaging of Lipid C═C Location Isomers.

Unsaturated lipids containing different numbers and locations of C═C bonds are significantly associated with a variety of cellular and metabolic functions. Although matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) has been used to visualize the spatial distribution patterns of various lipids in biological tissues, in situ identification, discrimination, and visualization of lipid C═C location isomers remain challenging. Herein, an efficient and fast on-tissue chemical derivatization (OTCD) approach was developed to pinpoint the locations of C═C bonds in complex lipids in situ via methyltrioxorhenium (MTO)-catalyzed epoxidation of C═C with a urea hydrogen peroxide (UHP)/hexafluoroisopropanol (HFIP) system. The efficiency of OTCD could reach 100% via one-step spray deposition of the solution mixture of MTO/UHP/HFIP at room temperature. The developed OTCD method provided rich structural information on lipid C═C location isomers, and their accurate spatial distribution patterns were resolved in mouse brain tissues. Tissue-specific distributions and changes of lipid C═C location isomers in the liver sections of obese ob/ob and diabetic db/db mice were further investigated, and their correlation in two animal models was revealed. The simplicity and high efficiency of the OTCD method developed for MALDI tandem MSI of lipid C═C location isomers possess great potential for functional spatial lipidomics.

Urea Hydrogen Peroxide and Ethyl Lactate, an Eco-Friendly Combo System in the Direct C(sp2)-H Bond Selenylation of Imidazo[2,1-b]thiazole and Related Structures.

Herein, we describe a urea hydrogen peroxide-mediated sustainable protocol for the synthesis of selenylated imidazo[2,1-b]thiazole by using half molar equivalent diorganyl diselenides in ethyl lactate as a greener solvent. The reaction features high yields, easy performance on gram scale, metal-free conditions, as well as applicability to imidazopyridine and imidazopyrimidine.

Advantages and disadvantages of dental whitening between 35% hydrogen peroxide for office use and 10% carbamide peroxide for home use. Literature Review

Advantages and disadvantages of dental whitening between 35% hydrogen peroxide for office use and 10% carbamide peroxide for home use. Literature Review

Investigation of Hydrogen Peroxide for 45MV 5-Aminolevulinic Acid-Mediated Radiodynamic Therapy

Cytotoxicity caused by the reactive oxygen species (ROS), such as singlet oxygen species (1O2), superoxide radical (O2-), and hydroxyl radical (HO), is a mechanism for treating cancer cells in radiation therapy. 5-aminolevulinic acid (5-ALA)-mediated radiodynamic therapy (RDT) is more effective in killing tumor cells than conventional radiation therapy. ROS is produced not only by ionizing radiation but also by Cherenkov light-activated protoporphyrin IX (PpIX), which is metabolized endogenously from 5-ALA. Moreover, PpIX also catalyzes hydrogen peroxide to generate 1O2, and an enhanced catalytic yield of 1O2 was observed in X-ray irradiation in vitro. Therefore, using an in-vivo mouse model, this study aimed to investigate the effect of hydrogen peroxide as a coenzyme catalyst on a novel 45MV 5-ALA-mediated RDT. A subcutaneous C57BL/6 mouse model of KP1 cell line was used. The tumors (n = 240) were randomized into six groups, consisting of untreated, conventional radiation treatment (RT), and RDT with or without hydrogen peroxide: 1. control (untreated), 2. hydrogen peroxide, 3. 45MV RT, 4. 45MV RT + hydrogen peroxide, 5. 45MV RDT, 6. 45MV RDT + hydrogen peroxide. For 45MV photon irradiation, a single fraction of 4 Gy was delivered to the tumors. 5-ALA was systemically injected at 100 mg/kg by tail-vein 4 hours before the treatment for endogenous PpIX accumulation in the tumor. Carbamide peroxide was used to deliver hydrogen peroxide to tissue and was administered at 60 mg/kg intratumorally into tumors ∼3-5 min before the treatment. The treatment effect of a single fraction of treatment was measured by calculating tumor growth, measured using a 1.5 T MR scanner on the day of treatment (prior to the treatment), 3 and 7 days post-treatment. Two-way repeated ANOVA with Bonferroni correction was used to compare each treatment group to determine the statistically significant difference in tumor growth. A total of 45MV RDT with hydrogen peroxide was shown to significantly delay the tumor growth for the mouse model and cell line investigated in this work. 45MV RDT with hydrogen peroxide group resulted in a decrease in tumor growth by 51.3 ± 4.1 % and 56.1 ± 5.1 % compared to the control group on 3 and 7 days post-treatment, respectively (P<0.001), and 43.4 ± 0.8 % and 50.9 ± 0.8 % compared to 45MV RT alone on 3 and 7 days post-treatment, respectively. Moreover, the enhancement effect of hydrogen peroxide on 45MV RDT was 2.2-4.7 times greater on 45MV RT alone (P<0.05). Hydrogen peroxide did not contribute to tumor growth when administered alone. A total of 45MV 5-ALA-mediated RDT with hydrogen peroxide resulted in the most significant tumor growth delay compared to the other groups. The catalytic effect of PpIX and hydrogen peroxide was observed in-vivo. These preliminary results demonstrate an effective cancer treatment modality.