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Article
The influence of recent adhesive onlay fabrication techniques on the fracture resistance of endodontically treated premolars (An in vitro study)

Authors: Zainab Shaker Al-Taii زينب شاكر الطائي --- Inas I. Al-Rawi ايناس الراوي
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 2 Pages: 12-17
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Endodontically treated teeth have low resistance to fracture against occlusal forces. The strengtheningeffect of bonded esthetic onlay restoration on weakened tooth has been reported. This study aimed to assess thefracture resistance of endodontically treated premolars restored with composite with and without cuspal coverageby using direct and indirect techniques. Indirect technique done by CAD/CAM system (computer aided design –computer aided manufacturer) and laboratory processing.Material and methods: Forty human extracted maxillary premolars of approximately comparable sizes were dividedinto four groups: Group (A): Ten endodontically treated teeth directly filled with Filtek Z250xt without cuspalcoverage. Group (B): Ten endodontically treated teeth prepared with onlay cavities and restored directly with FiltekZ250 XT. Group(C): Ten endodontically treated teeth prepared with onlay cavities and restored indirectly with FiltekZ250 XT. Group (D): Ten endodontically treated teeth prepared with onlay cavities and restored indirectly withParadigm MZ100 CAD/CAM blocks. Fracture strength of the samples was measured by using universal testingmachine (an axial compression test). Data were analyzed statistically by one way ANOVA test and least significantdifference test,Results showed that Group A has the lowest fracture resistance value than all experimental Groups and thedifference are highly significant. While Group B has a high significant fracture resistant value than the indirectlyrestored groups. Group C and Group D showed an approximate fracture resistant result (1.13KN and 1.07KNrespectively) and the difference is statistically not significant.Conclusion All CAD/CAM composite onlay, indirect Filtek z250 XT and direct cuspal coverage survived maximumbiting force for posterior single tooth, so these types of onlays provide good reinforcement in an extensive MODcavities in premolars The mode of fracture for Group D was 90% restorable which is higher than group C (80%)restorable and group B (30%) restorable type of fracture


Article
Fracture resistance of weakened premolars restored with sonically-activated composite, bulk-filled and incrementally-filled composites (A comparative in vitro study)

Authors: Fatima Fahad فاطمة فهد --- Manhal Abdul-Rahman Majeed منهل عبد الرحمن مجيد
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 4 Pages: 22-27
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: This study was conducted to assess the effect of sonic activation and bulk placement of resincomposite in comparison to horizontal incremental placement on the fracture resistance of weakened premolarteeth.Materials and method: Sixty sound human single-rooted maxillary premolars extracted for orthodontic purposes wereused in this study. Teeth were divided into six groups of ten teeth each: Group 1 (sound unprepared teeth as acontrol group), Group 2 (teeth prepared with MOD cavity and left unrestored), Group 3 (restored with SonicFill™composite), Group 4 (restored with Quixfil™ composite), Group 5 (restored with Tertic EvoCeram® Bulk Fill composite)and Group 6 (restored with Universal Tetric EvoCeram® composite using horizontal incremental layering technique).Standardized class II MOD cavity was prepared in all teeth except (group 1).After finishing the restorative procedureof each group according to the manufacturer's instructions, all teeth were stored in deionized distilled water in anincubator at 37°C for seven days.All specimens were subjected to compressive axial loading until fracturein auniversal testingmachine.Specimens were examined by a stereomicroscope at a magnification of (20X) to evaluatethe mode of fracture .Results: The results of this study revealed that the control group exhibited the highest fracture resistance compared toall prepared teeth groups (restored or unrestored) and the differences were statistically highly significant (P<0.01),except with group 3 (which was restored with SonicFill™ composite) where the difference was statistically significantonly (P < 0.05).Additionally the results of this study revealed that the prepared unrestored teeth (Group 2) exhibitedthe lowest fracture resistance compared to all restored groups and the differences were statistically highly significant(P<0.01). Meanwhile, among the restored teeth groups, teeth restored with SonicFill™ composite (group 3) exhibitedthe highest fracture resistance as compared with all other restored groups and the difference was statistically highlysignificant (P<0.01) .On the other hand, no statistically significant differences in fracture resistance were found amonggroups 4, 5 and 6, which were restored with Quixfil™ composite, Tetric EvoCeram® Bulk Fill composite and UniversalTetric EvoCeram® composite, respectively (P > 0.05). Group 3and Group 5 showed mostly mixed mode of failure,while Group 4 showed mostly adhesive mode of failure. On the other hand Group 6 teeth showed different modes offailure.Conclusions: SonicFill™ composite can be considered as a viable treatment modality for the restoration of weakenedmaxillary premolar teeth. On the other hand, the time-consuming incremental layering technique can be substitutedwith bulk filling, using bulk fill materials (Quixfil™ and Tetric EvoCeram® Bulk Fill) for reinforcement ofweakenedmaxillary premolars


Article
Marginal Discrepancy and Fracture Resistance of CAD/CAM Ceramill Sintron Metal Copings with Different Porcelain Materials

Authors: Ammar A. Al-Sa'ady --- Mustafa N. Abdulghani --- Eanas I. Jellil
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2017 Volume: 29 Issue: 2 Pages: 7-12
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: This study was performed to compare the marginal fit changes and facture resistance of metal ceramiccrowns constructed from Ceramill Sintron metal coping veneered with three different porcelain veneering materials(Vita Master Koromikos VMK, Willi Geller Creation CC and GC initial MC), also to evaluate the influence ofthermocycling on load at fracture.Materials and Methods: Master brass die was scanned ,then metal coping was designed and milled from CeramillSintron blank to get 60 metal copings, then divided randomly into three groups(20 sample), then veneered withporcelain: VITA, Creation or GC. The marginal gaps were measured before and after porcelain veneering thenmarginal fit changes was calculated. Fracture resistance test was done by Instron®, the master die was duplicatedto sixty analogs then each analog was fixed into acrylic base. After that each crown was cemented onto thecorresponding die analog. Ten samples of each group were subjected to compressive loading to fracture and otherten subjected to thermocycling followed by compressive loading to fracture.Result and Conclusion: The result of marginal fit changes showed that GC group had the lowest marginal gap followby VITA and Creation. While VITA group showed the highest fracture resistance follows by GC then Creation.Thermocycling process did not significantly reduce the load at fracture for all groups


Article
The influence of cavity design for cusp coverage on fracture strength of weakened maxillary first premolars using two esthetic restorative systems (CAD/CAM hybrid ceramic and nanohybrid composite) (An in vitro study)

Authors: Zainab Salman Jawad زينب سلمان جواد --- Abdul Karim J. Al-Azzawi عبد الكريم جاسم العزاوي
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 1 Pages: 1-10
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Maxillary first premolar with wide MOD cavity more susceptible to fracture. The aim of this study was toassess the influence of cavity design for cusp coverage on the fracture resistance of weakened maxillary firstpremolar restored with CAD/CAM hybrid ceramic versus nanohybide composite.Materials and Methods: Fifty six intact maxillary first premolars of approximately comparable sizes were divided intoseven groups eight for each: Group A: Intact teeth (control group); Group B: teeth prepared for MOD inlay; Group C:teeth prepared for MOD onlay covering the lingual cusp; Group D: teeth prepared for MOD covering buccal andlingual cusps ,the previous three groups indirectly restored with nanohybrid composite (3M ESPE Z 250 XT); GroupE,F,G prepared with the same design as group B, C, D respectively and restored with CAD/CAM hybrid ceramic(VITA ENAMIC).Results: An axial compression test was used to measure the fracture strength of experimented teeth. The readingswere analyzed statistically by t-test, one way ANOVA and LSD, then the mode of fracture had been examined. Theresults showed that sound teeth in group (A) had more fracture resistance values than all experimental groups andthe difference were highly significant with group (B, E, F, G).When the influence of cavity design tested amongcomposite groups it showed highly significant difference between group (B) and (C)and the highest fractureresistance value was for group(C), whereas the influence of cavity design among Enamic groups showed highlysignificant difference between group (E) and (G) the highest fracture resistance value was for group(E).T-testbetween similar designs showed non-significant difference between MOD groups and highly difference betweenother groups.Conclusions: Cusp coverage increased the fracture resistance of composite groups but result in non-restorablefracture, while Enamic total onlay presented promising fracture resistance with favorable mode of fracture


Article
In Vitro Comparative Assessment of Facture Resistance of Roots Restored With Everstick Fiber Reinforced Composite Post

Authors: Makdad Chakmakchi --- Raghad Rasheed --- Rajaa Suliman
Journal: Journal of Oral and Dental Research مجلة طب الفم والاسنان ISSN: 23106417 Year: 2015 Volume: 2 Issue: 1 Pages: 43-50
Publisher: Iraqi Association for Oral Research الجمعية العراقية لبحوث طب الفم

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Abstract

Aims: To evaluate and compare the fracture resistance of maxillary central incisors received EverStick adaptableglass fiber reinforced composite posts and prefabricated glass fiber Luxa post and to determine the mode of failure.Materials and Methods: Thirty extracted human permanent maxillary central incisor were decoronated, instrumented,and obturated. Post space was prepared in each root, randomly divided into 3 groups (n=10). Group (A): Control group;the roots remained without post space preparation. Group (B): The roots prepared to receive prefabricated translucentglass fiber posts (Luxa post). Group (C): The roots prepared to receive adaptable EverStick fiber reinforced compositepost. After core built up, the specimens were thermocycled, mounted in a customized metal ring and fracture resistancewas tested in a Universal Testing Machine. Data collected were analyzed statistically and the mode of failures wasanalyzed under stereomicroscope. Results: Statistical analysis revealed highly significant difference at p≤ 0.001. Group(C) showed the highest mean of fracture resistance followed by Group (B). While Group (A) the control group showthe lowest mean of fracture resistance. Fracture pattern indicated that specimens in Group: C represent 100 % favorablefailure, followed by group: B which represent 80 % favorable failure, while the control group showed 80 % unfavorablefailure. Conclusions: EverStick adaptable glass fiber reinforced composite post showed significantly more predictablefracture resistance than prefabricated glass fiber Luxa post.


Article
Fracture Resistance of Roots After Canal Preparation by Two Methods and Obturated by Different Techniques ISSN

Author: Wiaam M.O. AL-Ashou
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2014 Volume: 14 Issue: 2 Pages: 212-219
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: The purposes of this in vitro study are to investigate the effect of instrumentation types ( hand and rotary instrumentations) and obturation techniques (Cold lateral, and Thermafil) on vertical root fracture. Materials and Methods: The crown of the 100 single rooted teeth were removed leaving 12mm of the roots length, then the root randomly divided into four groups. Control –ve Group(n=10), Hand Group(n=30), ProTaper Group(n=30) and Helix Group(n=30) according to the type of the instrument used to prepared the root canals. After that, the last three groups subdivided into subgroups according to the obturation technique either by using Cold Lateral condensation technique or Thermafil obturation technique. After the sealer set, the roots were embedded in acrylic moulds and subjected to compressive loading, the load at which the fracture occurred was recorded and statically analysis. Results: the fracture resistance of the root prepared by Helix and ProTaper files were significantly greater than that obtained for the root canals prepared with hand K-files. The results of this study also demonstrated that when root canals obturated with Thermafil the roots resist the fracture load greater than that of the canals obturated with Cold Lateral condensation obturation but the difference is not statistically significant between them. Conclusions: the use of rotary nickel titanium files in endodontic treatment provides higher fracture resistance for the roots, and the use of the Cold Lateral condensation obturation technique may weaken the roots, so that the roots become more susceptible to the vertical root fracture.

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