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EFFECT OF RESIN INFILTRANT AND FLUORIDE VARNISH ON MICRO-HARDNESS OF DE-MINERALIZED ENAMEL SUBMITTED TO pH CHALLENGE

Reham M. Attia

ABSTRACT

The purpose of this study was to evaluate the micro-hardness of artificially induced de- mineralized enamel after application of resin infiltrant and fluoride varnish and after pH challenge.

Material and methods: In the current study; sound bovine incisors were used. A total of 40 sound enamel were then embedded in pre-cut metal cylinders. Two layers of acid-resistant nail varnish were applied to cover most of the enamel surfaces, leaving a window of 4×4 mm for demineralization. Each specimen was immersed in 32 ml of a de-mineralizing solution containing 50 mM acetate buffer solution and 1.28 mM Ca(NO3)2_4H2O, 0.74 mM (NaH2PO4)_2H2O, and 0.03 ppm F at pH 5.0,10 for 24 hours at 37˚C , then microhardness was recorded. The samples then were divided into two groups according to the material used to treat the de-mineralized enamel, each group consisted of 20 samples. Group 1: The samples of de-mineralized enamel were infiltrated with resin infiltration. Then the micro-hardness was recorded for all resin infiltrated samples before pH cycling challenge. The samples were then submitted to a pH cycling model at 37 C over 7 days. The pH cycling consisted of immersing the samples in 35.5 ml of de-mineralizing solution: (2.0 mmol/ L Ca, 2.0 mmol/ L P, 0.075 mol/ L acetate buffer, 2.22 mL/mm2  of enamel surface) for 6 hours, alternated with immersion in 17.75 mL of re-mineralizing solution: (1.5 mmol/ L Ca, 0.9 mmol/ L P, 0.15 mol/ L KCl, 0.02 mol/ L cacodylate buffer, pH 7.0, 0.25 mL/mm2) for 18 hours for 5 days. Then, specimens were kept for 2 more days in a fresh re-mineralizing solution, completing 7 days of treatment. The samples were washed in de-ionized water for 30 seconds among de-mineralizing and re-mineralizing cycles. Group 2: Fluoride varnish (Duraphat , Colgate- Palmolive ,NSW, Australia) was applied as a thin layer by a brush and totally dried, then  the micro-hardness was recorded. The samples were then subjected to a pH cycling as in group 1. Then after challenge the micro-hardness measurements were performed as formerly described.

Results: The difference was highly significant between resin infiltrant and fluoride varnish treated enamel. The comparison among micro-hardness values of initial, de-mineralized enamel, resin-infiltrated enamel and resin infiltrated after pH cycling showed that there was a significant difference. The difference between micro-hardness values was highly significant when comparison was accomplished between initial and de-mineralized enamel, initial and after pH cycling, de- mineralized enamel and resin infiltrated enamel, de-mineralized enamel and after pH cycling and finally between resin infiltrated enamel and after pH cycling. The difference between micro- hardness values was not significant regarding initial and resin infiltrated enamel.

Conclusion: Within the limitations of this study, it was concluded that the micro-hardness of resin infiltrated enamel was higher than that of de-mineralized enamel treated with fluoride varnish before and after pH cycling.

Vol. 64, 323:332, January, 2018 I.S.S.N  0070-9484

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Resin composite bond integrity with desensitized dentin

Asmaa A. Yassen – Mohamed F. Haridy – Mohamed A. Abdelaal

Objectives: To study the influence of using nano-hydroxyapatite or self-assembling peptides containing desensitizing agent on the dentin-resin composite microtensile bond strength and interfacial micromorphology.

Materials and methods: Standardized mid coronal flat dentin was obtained from a collected thirty molars. Exposed dentin surfaces were demineralized and randomly divided into three equal groups (10 each) according to the desensitizing agent used; without (control), nano-hydroxyapatite containing (Remin Pro, VOCO, Germany) or self-assembling peptide (CurodontTM Protect, Credentis, Switzerland). Desensitizing agents were uniformly distributed over the demineralized surfaces and left for 5 minutes/ once daily for 7 days. Specimens were stored in artificial saliva during the seven days. Resin composite (Aelite Aesthetic Enamel, Bisco, Inc, Schaumburg, USA) core was built over the demineralized substrate after being bonded with All-Bond Universal adhesive (Bisco, Inc, Schaumburg, USA). Slabs with a cross-sectional area of approximately 1mm2 were obtained from all bonded specimens and subjected to microtensile bond strength testing at a cross head speed of 1.0mm/min. Fractured specimens were examined under a digital microscope at 50x to examine the failure mode. Micromorphological analysis for the resin dentin interface and fractured specimens were done using SEM. Statistical analysis was done using One way-ANOVA followed by Tuckey’s post hoc test for comparison (P≤ 0.05).

Results: The mean bond strength values recorded in (MPa) were (38.0(6.7)) Remin Pro, (30.17(6.3)) Curodont and (30.65(6.4)) control with a statistical significant difference between them. Adhesive failure was prominent in Curodont, however, cohesive and mixed failures were common in the other two groups. Micromorphological analysis revealed crystal deposits along the hybrid layer and resin tags in Remin Pro group and defective hybridization with Curodont.

Conclusions: Dentin desensitization has not any adverse effect on the resin composite bond integrity. The use of Nano-hydroxyapatite containing agent plays a role in the reinforcement of hybrid layer.

KEYWORDS: Bond strength; Curodont; Desensitization; Nanohydroxyapatite; Protect; Remin Pro; Self assembling peptides;

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Surface Roughness of Monolithic Zirconia and Gold Alloy After Wear Simulation Against Human Enamel

Khaled Haggag – Muhammad Abbas – Zainab El Sharkawy

Purpose: To evaluate the effect of simulated wear against human enamel on the surface roughness of monolithic zirconia and gold alloy under different occlusal loads.

Materials and Methods: Forty rectangular plate specimens (6×6×2) mm, were prepared from monolithic zirconia (Bruxzir, n=20) and type IV gold (Begostar, n=20) forming two experimental groups. Forty premolar teeth freshly extracted for orthodontic purpose were sectioned mesio-distally and only the cusp tips of the buccal halves were used as antagonists in the wear simulation testing procedure. All of the specimens were mounted to chewing simulator with the cusp antagonists, half of them were subjected to (50000 chewing cycles under 50N load), the other half subjected to (50000 chewing cycles under 150N load) cyclic loading. Data were submitted to two-way ANOVA, and statistical significance was set at p < 0.05.

Results: With low load (50 N), it was found that gold alloy group recorded statistically significant higher roughness change mean value (0.00085±0.001 Ra) than Bruxzir group mean value (-0.00079±0.0023 Ra). The difference between groups was statistically significant as indicated by student t-test (t=2.08, p=0.0492 < 0.05). While, enamel cusp antagonist of gold alloy group recorded non-statistically significant higher roughness change mean value (0.01867±0.024 Ra) than enamel cusp antagonist of Bruxzir group mean value (0.016567±0.0013 Ra). The difference between groups was statistically non-significant as indicated by student t-test (t=1.7, p=0.1043> 0.05). With high load (150 N), it was found that gold alloy group recorded statistically non-significant higher roughness change mean value (0.00135±0.0017 Ra) than Bruxzir group mean value (-0.00052±0.003 Ra). The difference between groups was statistically non-significant as indicated by student t-test (t=1.648, p=0.1135 > 0.05). While, enamel cusp antagonist of gold alloy group recorded statistically non-significant higher roughness loss mean value (0.00219±0.005 Ra) than enamel cusp antagonist of Bruxzir group mean value (-0.00021±0.005 Ra). The difference between groups was statistically non-significant as indicated by student t-test (t=1.15, p=0.2615> 0.05).

Conclusions: 1. Monolithic zirconia do not become as rough as type IV gold when subjected to simulated mastication cycles at low (50 N) load, although they were not significantly different from each other at high (150 N) load. 2. Although being non-significant, there was a correlation between roughness change of both monolithic zirconia and gold substrates, and that of their enamel antagonists.

Volume 64, No 1, January 2018, Page 275-285

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Effect of simulating toot h brushing on surface change of different ceramic materials

Khaled Haggag – Muhammad Abbas – Hussein Ramadan – Mohamed Fawzy

Objectives: Purpose of the present study was to evaluate the surface roughness of current ceramics before and after tooth brushing abrasion, using simulated tooth brushing wear testing.

Materials and Methods: 40 ceramic samples (Zirconia ceramics, Vita Enamic, Lava Ultimate, & E-max ceramics) were cut from corresponding 4 types of ceramic blocks using microtome, then 40 samples were divided into 4 groups (n=10). Each sample has a fixed dimension about 10 x 10 x 2mm (thickness). The 3-body simulated tooth brushing wear testing was performed using a programmable logic controlled equipment; ROBOTA chewing simulator* integrated with thermo-cyclic protocol, then Surface roughness of each material (Ra) was measured with USB digital surface profile gauge.

Results: Total effect of material; regardless to toothbrush wear simulation cycles, totally there was no-significant (p=0.1379 > 0.05) difference between all materials where (Zr ≥ e.max ≥V enamic ≥ L ultimate) with their mean values respectively after 24 months (Zr; 0.25898 ±0.0035, e.max; 0.25428 ±0.0029, V enamic; 0.25413 ±0.0049, L ultimate; 0.25403 ±0.0028). Total effect of toothbrush wear simulation cycles; irrespective of material, totally toothbrush wear simulation cycles did not affect roughness significantly (p=0.8281 > 0.05) difference between all materials where (18 m ≥ baseline ≥ 6 m ≥24 m ≥ 12 m).

Conclusions: Brushing of ceramic materials with conventional dentifrices non-significantly increased surface roughness, where results of surface roughness present within the clinically acceptable range, not insult the patient intraorally

Volume 64, No 1, January 2018, Page 265-274

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Effect of different types of water on cusp deflection of teeth restored with composite

Hossam Mohamed Mossa

Objective: It is in vitro study to evaluate the influence of various mouth washes on cusp deflection of premolar teeth restored with different types of composite.

Methods: A total of 45 human premolars were used in this study. The teeth were randomly divided into three equal groups according to the type of resin composite (Silorane, Bulk fill and FiltekTM Z250). Each group were immersed for three months in three different solutions (alcoholcontaining mouth rinse, alcohol-free mouth rinse, and artificial Saliva). The cuspal deflection was measured after curing of the composite resin and after immersion in the solution using digital caliper.

Results: All the composite resin specimens show cusp deflection. The lowest value of cusp deflection was recorded for the Silorane specimen in comparison to other types of composites. The specimens who immersed in alcohol containing mouth wash recorded the highest values.

Conclusion: Alcohol-free mouth rinse may prefer to alcohol containing mouth rinse in patients with extensive restorations

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The Effects of Tricalcium Phosphate and Novamin Remineralizing Agents on Microhardness of Bleached Enamel with 35% Hydrogen Peroxide-An In vitro Study

Sahar Abd El Halim

Objectives: The aim of the present study was to evaluated the effects of remineralizing agents (Tricalcium phosphate and Novamin) on microhardness of bleached enamel surface with 35%hydrogen peroxide (in office).

Materials and Methods: Forty human permanent maxillary premolars free from caries or enamel malformation were used. The teeth were sectioned transversally across the cemento-enamel junction, and specimens were embedded in self-cure acrylic. The labial enamel surface faced upward and then they were ground flat and polished with silicon carbide abrasive papers. A total specimen were prepared and kept in deionized water. Then the specimens were drying subjecting them for baseline microhardness testing (control). The dental bleaching treatment was performed just on the labial enamel surface of the specimens using a commercial 35% hydrogen peroxide Whitness HP bleaching gel (in-office ).It was used according to the manufacture instruction. Microhardness was tested for all specimens after bleaching. Specimens were divided into two groups according to remineralizing agent n=20, Group I: Treated by NUPRO Sensodyne with NovaMin, Group II: Treated by Clinpro™ White Varnish Tri-Calcium Phosphate. The remineralizing agent was applied for three minutes per day. Two remineralizing agents were applied for fourteen consecutive days. After each application procedure, the specimens were washed with deionized water and then kept in artificial saliva. At the end of the fourteen days the remineralized specimens were subjected to microhardness testing and values were recorded. All the data were analyzed by ANOVA and Tukey’s post hoc test.

Results: Results revealed that a statistically significant decrease on mean microhardness values after enamel bleaching compared to control, followed by a significant increase on mean microhardness after the application of the both remineralizing agents. One way-ANOVA showed a statistically insignificant difference between NUPRO Sensodyne with NovaMin and Clinpro™ White Varnish at p≥0.05.

Conclusions: Based on the results of this in vitro study both Tricalcium phosphate and Novamin are effective in remineralization of bleached enamel surface and no significant difference was detected in their efficacy

Volume 64, No 1, January 2018, Page 251-258

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Effect of One Year Brushing with Nano-Hydroxyapatite Modified Toothpaste on Surface Roughness and Micro- Shear Bond Strength of Enamel to Resin Composite Restoration Using Two Adhesive Systems: In vitro study

Dalia M Abdel-Hamid – Norhan A El-Dokky – Sherif B El-Tawil

This study aimed at evaluating in vitro the effect of one year brushing with 10 wt. % nanohydroxyapatite (n-HAp) modified toothpaste on surface roughness and micro-shear bond strength(μ-SBS) of enamel to resin composite restoration (Filtek Z350 XT Universal Restorative) using total-etch (TE), Adper Single Bond Plus Adhesive and self-etch (SE), Single Bond Universal Adhesive systems. Thirty human enamel/dentin slabs were prepared and divided according to the toothpaste into: control group (Signal Kids toothpaste) and test group (10 wt. % n-HAp ~20 nm modified Signal Kids toothpaste). Brushing was performed for one hour/day for 24 days. Roughness (Ra) was measured by the AFM for 10 brushed slabs. For μ-SBS evaluation, 20 brushed slabs were randomly subdivided into 2 subgroups/ group according to the adhesive system (control/TE, control/SE, test/TE and test/SE). Micro-cylinders of nano-filled resin composite were prepared. The μ-SBS test was performed by a universal testing machine. The mode of failure was evaluated by digital microscope and the morphological changes of the de-bonded surfaces were examined by the SE microscope. The data were statistically analyzed. The mean Ra (nm) values of the enamel brushed with unmodified toothpaste were not significantly different than those brushed with n-HAp modified toothpaste. Whereas, the mean μ-SBS (MPa) of the control (brushed with unmodified toothpaste) subgroups with either TE or SE were significantly lower than those of the test (brushed with n-HAp modified toothpaste) subgroups. Subgroups with SE adhesives exhibited predominantly adhesive failure mode, while predominance of mixed failures were detected for subgroups with TE adhesives. In conclusion, one year simulated brushing with 10 wt. % n-Hap modified toothpaste did not affect enamel roughness while it improved the bond strength to resin composite regardless of the adhesive system. However, the adhesive system type has an influential effect on the failure mode.

Keywords: Brushing, Roughness, Nano-hydroxyapatites, Toothpaste, μ-shear bond strength, Adhesives, Enamel

Volume 64, No 1, January 2018, Page 237-250

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Mineral Trioxide Aggregate VS Calcium Enriched Mixture molar pulpotomy: A systematic review and meta-analysis

Marwa El-Sayed Sharaan – Mohamed Ibrahim Rabie

Objectives: The aim of the current systematic review /meta-analysis was to perform a comparison of the outcomes of Calcium Enriched Mixture (CEM) and Mineral Trioxide Aggregate (MTA) as agents for pulpotomy in primary and permanent molars.The proposed PICO question was “Whenever there is vital pulp exposure in primary and permanent molars, what are the treatment outcomes of CEM compared to MTA pulpotomy regarding clinical and radiographic success?

Methods: We looked for published randomized clinical trials (RCTs) of the at least 12-month period; the search covered papers published up to July 2017 in PubMed (Medline) and Springer- Link databases. Meta-analysis was performed using R program 3.3.3 with specialized meta-analysis packages, namely rmeta, metaphor, and RGtk2. Data was reformulated dichotomously (success or other [healing, failure, or missing]) for the selected studies. The fixed effect model was tested, OR (Odds ratio), RR (Risk ratio), and 95% CI (Confidence interval) were calculated using the formulated raw dichotomous data of the selected studies. The heterogeneity among studies was assessed using standard chi- square test and Woolf’s test. Mantel-Haenszel fixed-effect method was used to compute OR for the fixed model. The level of significance was at 0.05.

Results: Four hundred forty-nine articles were gathered. Two reviewers screened the articles, and three RCTs were included in the study. After the assessment, three RCTs were suitable for meta- analysis tested by Mantel Haenszel method. Statistically, the insignificant difference was found between the success rate of CEM compared to MTA, with OR=0.92(95% CI, 0.57-1.49). RR= 0.94 (95% CI, 0.66-1.35). Test for heterogeneity showed p-values (0.4241, 0.4455)

Conclusions: Systematic review /meta-analysis of the chosen RCTs showed that CEM pulpotomy in human teeth presented insignificant but superior clinical and radiographic success compared to those treated with MTA. Good quality and homogeneity of the included RCTs were yielded.

Key Words: Calcium Enriched Mixture, Meta-Analysis, Mineral Trioxide Aggregate, Molar pulpotomy, Systematic review.

Volume 64, No 1, January 2018, Page 227-235

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Bone height changes around hybrid implants in three implant retained mandibular Overdentures

Eatemad R. Taha – Azza F. Metwally

Objective: The purpose of this RCL was to evaluate bone height changes around hybrid implants in three implant- retained mandibular overdenture with locator attachment.

Materials & Methods: Ten completely edentulous male patients were enrolled in this study. Preoperative Cone beam computed tomography (CBCT) had been made to evaluate bone height & density in areas for implant installation. Patients had received three hybrid implants installed in midline & mandibular canine areas following flapless technique. Implants were early loaded; two weeks after implant installation. Overdentures were functionally fitted onto the locator attachment of the hybrid implants by direct pick-up technique.

Evaluation: Bone height changes were evaluated with the aid of CBCT at the time of implants’ loading, six months and twelve months later. Mesial & distal crestal bone heights were calculated from reconstructed corrected sagittal views.

Results: The results had revealed that there was no significant difference in peri-implant bone level throughout the follow-up periods on comparing the three implant sites. However, there was slightly higher bone resorption around the distal implants than the midline ones.

Conclusions Three implant retained overdentures with locator attachments may preserve periimplant bone in the anterior mandibular area. Midline implant in three implant overdentures may not be subjected to more stresses than the two distal implants

Volume 64, No 1, January 2018, Page 219-226

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Effect of carbamide peroxide bleaching with and without topical desensitizing gels on enamel roughness, microhardness, and bond strength to orthodontic brackets

Abeer A.M.M Elhatery – Mohammed M. Ellaithy

Objective: The objective of this study was to evaluate, in vitro, the influence of two concentrations of carbamide peroxide bleaching agents with and without topical desensitizing gels on enamel microhardness, roughness, and shear bond strength to orthodontic metal brackets.

Methods: One hundred and sixty-eight (168) human extracted premolars for orthodontic purpose were obtained and randomly divided into seven groups (n =24): Group 1, control group (Neither bleaching nor desensitizing); Group 2, bleached with 22% carbamide peroxide; Group 3, bleached with 22% carbamide peroxide followed by Minerals desensitizing gel; Group 4, bleached with 22% carbamide peroxide followed by ‘’D.M. Sense’’ desensitizing gel; Group 5, bleached with 35% carbamide peroxide; Group 6, bleached with 35% carbamide peroxide followed by Minerals desensitizing gel; Group 7, bleached with 35% carbamide peroxide followed by ‘’D.M. Sense’’ desensitizing gel. Microhardness test and roughness measurements were carried on specimens immediately after finishing of treatment, using Vickers Diamond Microhardness Tester and Roughness Analyzer respectively. Only specimens for brackets shear bond strength (SBS) were stored for 7 days in distilled water after treatments and before testing. Shear bond strength were tested using Instron Universal Testing Machine

Results: Statistical significant differences were found between groups. Groups that received bleaching treatments only, showed greater deterioration in all tested properties than, groups received desensitizing treatments after bleaching treatment.

Conclusion: Application of desensitizing agent after in-home bleaching is highly recommended to minimize deleterious effects of bleaching agents.

Keywords: Bleaching, Carbamide Peroxides, Enamel Roughness, Microhardness, Brackets shear bond strength.

Volume 64, No 1, January 2018, Page 207-218

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