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Article
Assessment of shear bond strength of glass ionomer cement reinforced by different amounts of Hydroxyapatite

Author: Mohammed R. Hameed* BDS, MSc, PhD
Journal: Journal of the Faculty of Medicine مجلة كلية الطب ISSN: 00419419 Year: 2009 Volume: 51 Issue: 2 Pages: 151-154
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: This study was done to assist bond strength of glass ionomer cement reinforced by different amount of Hydroxyapatite Materials and methods: In this study a hydroxyapatite materials were added to glass ionomer cement at different ratios; 10%, 15%, 20%, 25% and 30% (by weight) and the bond strength was detected by construction a cylinders from these mixed materials, constructed on exposed dentine of human extracted premolar teeth and by Zwick’s universal testing machine the bond strength were detected for these mixed materials.Results: Results showed that the glass ionomer cement reinforced by hydroxyapatite has higher bond strength than conventional glass ionomer cement and the hydroyapatite powder to glass ionomer cement powder ratio by weight best to be 25%. Conclusion: The addition of hydroxyapatite to conventional glass ionomer cement increased its bond strength to dentine.


Article
Evaluation of marginal gap at the composite/enamel interface in Class II composite resin restoration by SEM after thermal and mechanical load cycling (An in vitro comparative study)

Authors: Mais Yaroub ميس يعرب --- Mohammed R. Hameed
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 4 Pages: 63-70
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: This study compared in vitro the marginal adaptation of three different, low shrink, direct posteriorcomposites Filtek™ P60 (packable composite), Filtek™ P90 (Silorane-based composite) and Sonic fill™ (nanohybridcomposite) at three different composite/enamel interface regions (occlusal, proximal and gingival regions) of astandardized Class II MO cavity after thermal changes and mechanical load cycling by scanning electronmicroscopy.Materials and methods:Thirty six sound human maxillary first premolars of approximately comparable sizes weredivided into three main groups of (12 teeth) in each according to the type of restorative material that was used:group (A) the teeth were restored with Filtek™ P60 and single bond™ Universal adhesive using horizontal incrementaltechnique, group (B)the teeth were restored with Filtek™ P90 and P90 system adhesive using horizontal incrementaltechnique and group (C) the teeth were restored with Sonic fill™ composite and single bond™ Universal adhesiveusing bulk technique.After specimens were stored in distilled water at 37°C for 7 days, all specimens were subjectedto thermocycling at (5° to 55 °C), then submitted to mechanical load cycling (intermittent axial force of 49N and atotal of 50.000 cycles). The specimens were observed under scanning electron microscope at (2000 X) to measuremarginal gap width (the distance between the dental wall and the restoration) at occlusal, proximal and gingivalregions in micrometer using Tescan software, version 3.5. Data were analyzed statistically by one way ANOVA testand least significant difference tests.Results:The results showed that the silorane-based posterior composite (Filtek™ P90) showed significantly the leastmarginal gap width at the occlusal, proximal and gingival regions after the application of thermal changes andmechanical load cycling in comparison to the two methacrylate-based posterior composite Filtek™ P60 (packable)and the Sonic fill™ (nano-hybrid). Sonic fill™ bulk fill composite that relied on the vibration concept to lower theviscosity of high filler loaded composite material showed significantly lesser marginal gaps width at occlusal, proximaland gingival composite/enamel interface regions in comparison with Filtek™ P60 (packable composite) usinghorizontal incremental technique. The silorane-based composite (Filtek™ P90) showed non-significant difference inmarginal gaps width at the three different regions. While, both methacrylate based Filtek™ P60 and Sonic fill™composite showed significantly lesser marginal gap width at the occlusal region in comparison with gingival regions.Conclusion: None of the low-shrinkage composite restorative materials tested in this study totally prevented microgapformation at composite/enamel interfaces of Class II MO cavity


Article
A study to compare the cleaning efficiency of different irrigation systems for macro debris removal in instrumented canals (An in vitro study)

Authors: Hussein A. Hussein --- Mohammed R. Hameed محمد رشيد حميد
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 2 Pages: 11-16
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Irrigation of the canal system permits removal of residual tissue in the canal anatomy that cannot bereached by instrumentation of the main canals so the aim of this study was to compare and evaluate the efficiencyof conventional irrigation system, endoactivator sonic irrigation system,P5 Newtron Satelec passive ultrasonicirrigation and Endovac irrigation system in removing of dentin debris at three levels of root canals and to comparethe percentage of dentin debris among the three levels for each irrigation system.Materials and methods: Forty extracted premolars with approximately straight single root canals were randomlydistributed into 4 tested groups of 10 teeth each. All canals were prepared with Protaper Universal hand files to size#F4, and irrigated with 2.5% NaOCI 1 ml between files and 5ml for 60 seconds as a final irrigant by different irrigationdevices; group one, by using conventional system; group two, by using Endoactivator sonic irrigation system, groupthree, by using Satelec Passive Ultrasonic irrigation and group four by using the Endovac system. After the finalirrigation, the roots were split longitudinally and photographed with a digital microscope. The roots were magnifiedto 100X; a percentage of debris was calculated for the apical 0-3, middle 3-6 and coronal 6-9 mm. The debris scorewas calculated as a percentage of the total area of the canal that contained debris as determined by pixels inAdobe PhotoshopCS5. Data were analyzed statistically by ANOVA and LSD at 5% significant level.Results: when comparing the debris remaining, the Endovac, Endoactivator and Satelec groups showed significantlyless debris than the conventional group at all three levels (p < 0.01). The Endovac group showed significantly lessdebris than the Endoactivator group at middle and coronal levels while no significant difference found between theEndovac system and Endoactivator system at apical level. The apical 0-3 mm showed significantly more debris thanboth the middle and coronal level for all groups.Conclusion: The EndoVac system showed a higher cleaning capacity of the canal at all levels, followed by theprotocols that used Endoactivator sonic irrigation system. The conventional irrigation system with maxi-i-probeneedles showed inferior results. The apical three millimeters showed a greater amount of debris than the 3-9millimetres from the working length, regardless of the irrigation device used


Article
Comparative Study of The Amount of Apically Extrusion Of Debris During Root Canal Preparation Using Wave One™, Trushape 3D™, Hyflex™ CM and One Shape™ Instrumentation Systems (An In Vitro Study)

Authors: Ali W. Hadi --- Mohammed R. Hameed محمد رشيد حميد
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2017 Volume: 29 Issue: 1 Pages: 1-8
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Many types of instruments and techniques are used in the instrumentation of the root canal system. These instruments and techniques may extrude debris beyond the apical foramen and may cause post-instrumentation complications. The aim of this study was to evaluate the amount of apically extruded debris resulted by using 4 types of nickel-titanium instruments (WaveOne, TRUShape 3D conforming files, Hyflex CM, and One Shape files) during endodontic instrumentation.Materials and methods: Forty freshly extracted human mandibular second premolar with straight canals and a single apex were collected for this study. All teeth were cut to similar lengths. Pre-weighted glass vials were used as collecting containers. Samples were randomly divided into four groups with 10 samples in each group: Group A instrumentation by WaveOne reciprocating file, Group B instrumentation by TRUShape 3D rotating files, Group C instrumentation by Hyflex CM rotating files and Group D instrumentation by One Shape rotating file. A total volume of 7 ml of sodium hypochlorite was used for irrigation in each sample. Apical patency confirmed and maintained by a size #15 K-File. All canals were instrumented up to a size #25. After completion of endodontic instrumentation, vials were then stored in an incubator for 5 days at 68o C for dryness. Then vials are weighted again, and the pre-weight subtracted from the post-weight, the weight difference resembled the amount of apically extruded debris from the apical foramen during root canal instrumentation. Data obtained were statistically analysed by using ANOVA and LSD tests.Results: The results showed that the Hyflex CM Group (C) has statistical significant lowest apically extruded debris as compared to other groups of this study (P ≤0.05), while the TRUShape Group (B) has statistical significant lowest apically extruded debris as compared to One Shape Group (D) and WaveOne Group (A), while the WaveOne Group (A) showed the highest value of apically extruded debris (p ≤0.01). The result showed that all groups resulted in apical extrusion of debris.Significance: Although all systems caused apical extrusion of debris and irrigant, continuous rotary instrumentation was associated with less extrusion as compared with the use of reciprocating file system

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