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Article
Estimation of the Bennett mandibular immediate side shift in Iraqi full mouth rehabilitation patients

Author: Ma'an Rasheed Zakaria معن رشيد زكريا
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 4 Pages: 54-62
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Controversy exists concerning the presence and amount of the Bennett mandibular immediate sideshift among patients and whether it is necessary to accommodate for it in adjustable articulators. The aim of thisstudy was to register and calculate the amount of any immediate side shift (ISS) present in patients requiring fullmouth rehabilitation.Materials and methods: 3- dimensional condylar movements of 50 Iraqi TMD-free patients were recorded using astereographic fully adjustable articulator system during protrusion, left and right eccentric mandibular movements.Protrusive angles of each patient were verified to figure out the suitable fossa analog for each case. The thickness ofeach right and left premade fossa analog selected was measured with a vernier caliper and was tightly secured inthe articulator fossa compartment. Functionally-generated path recordings were performed using custom-madeintraoral clutches. Bennett ISSs, verified by the stereographic system in the molded fossae, were measured using thevernier caliper. The final right and left ISSs were estimated by subtracting the thickness of the blank fossa analog fromthat of the molded one. The final ISSs were recorded and statistically compared.Results: Stereographic recordings of eccentric mandibular movements revealed ISSs within all patients involved in thisstudy. The ISSs varied among the patients and bilaterally within them. Their average values ranged between 0.80 mmfor females and 1.68 mm for males, showing significant statistical differences between them but with no relevancy toage advancement. Mean values of ISSs of males' and females' mandibular left joints were more than those recordedby their right joints.Conclusion: Verifying the mandibular ISS in the molded fossae is an essential step to efficiently rehabilitate full mouthcases; thus it would be helpful to use a fully adjustable articulator system to restore complicated cases since veryminor intraoral occlusal adjustments might be required for the finished restorations prior to the final cementation


Article
A Comparison between the Horizontal Condylar and Bennett Angles of Iraqi Full Mouth Rehabilitation Patients by Using Two Different Articulator Systems (An In-Vivo Study)

Author: Ma'an Rasheed Zakaria معن رشيد زكريا
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2016 Volume: 28 Issue: 1 Pages: 26-35
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Errors of horizontal condylar inclinations and Bennett angles had largely affected the articulation ofteeth and the pathways of cusps. The aim of this study was to estimate and compare between the horizontalcondylar (protrusive) angles and Bennett angles of full mouth rehabilitation patients using two different articulatorsystems.Materials and Methods: Protrusive angles and Bennett angles of 50 adult males and females Iraqi TMD-free full mouthrehabilitation patients were estimated by using two different articulator systems. Arbitrary hinge axis location followedby protrusive angles and Bennett angles, estimation was done by a semiadjustable articulator system. A fullyadjustable articulator system was utilized to locate the terminal hinge axis using a kinematic face bow followed byprotrusive angles location by the aid of two square shaped transparent hard plastic protractors attached close tothe condylar stylus of the articulator followed by Bennett angles calculation according to the Hanau formula. Allresults were subjected to statistical analyses.Results: The two articulator systems scored protrusive angles for male patients greater than female patients whichwere non-significant for the fully adjustable articulator but they were significant for the semiadjustable articulator.Non-significance existed between females of the fully adjustable articulator and males of the semiadjustablearticulator while high significance was located between males of the fully adjustable articulator and females of thesemiadjustable articulator. Concerning Bennett angles, the highest mean value belonged to the male group of thefully adjustable articulator, while the lowest scored by the female group of the semiadjustable articulator. Highlysignificant differences were located between the Bennett angle mean values of the groups.Conclusion: Using both articulators, the total mean values of the males were greater than the females regardingboth horizontal condylar angles and Bennett angles with the total means scored by the fully adjustable articulatorbeing larger than those of the semi-adjustable type. Using both articulators, the males' right and left condylesexhibited greater Bennett angles than their female equivalents. The precision estimation of the horizontal condylarangles and Bennett angles provided by the condylar axis protractors of the fully adjustable articulator render suchtype of articulators most suitable for treating full mouth rehabilitation cases


Article
An evaluation of an Iraqi phosphate-bonded investment and a commercial type on the marginal fit of ceramometalcopings using three different investing and burnout techniques

Authors: Ma'an Rasheed Zakaria معن رشيد زكريا --- Dhifaf Mohammad Al-Obaidi ضفاف محمد العبيدي
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 3 Pages: 18-26
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The accuracy of fitness of any dental casting is imperative for the success of any prosthodontictreatment. From the time that dental casting was first introduced, efforts have been made to produce moreaccurate and better fitted castings with minimal marginal discrepancy. The aim of this in vitro study was to evaluatethe effects of three different investing and burnout techniques on the vertical marginal discrepanciesofceramometalcopings invested with two types of phosphate- bonded investments.Materials and methods: Sixty wax patterns were fabricated on a standardized prepared brass die representing anupper central incisor by the aid of a custom-made split mold. Three different investing and burnout techniques wereapplied for an Iraqi investment and a commercial type; Group I:Ring investing with conventional burnout technique(RC);Group II: Ringless investing with conventional burnout technique (RLC);Group III: Ring investing with acceleratedburnout technique (RA).Twenty wax patterns of each group were divided into two subgroups according to the typeof investment material used (10 for each subgroup) represented as (B) for the BellaStar XL and (W) for the WYMvestinvestments. Complete castings were finished and seated on the metal die. The accuracy of fit of each coping wasdetermined by measuring the vertical marginal discrepancies between the finish line on the metal die and themargins of each coping at four specific reference points on the labial, mesial, palatal, and distal aspects of the dieby the aid of a light microscope supplied with a digital camera.The arithmetic mean of each three records wascomputed and regarded as the amount of the marginal discrepancy of each coping and was used as a unit for thestatistical analysisResults: Mean marginal accuracy for W(RLC)was found to be the least (13.839+4.5724 um) while the highest meanvalue related to B(RLC) (29.033+2.102 um). In general, ANOVA test showed significant results among the mean valuesof the Binvestment subgroups while LSD test showed non-significance between the (RA) and both the (RC) and (RLC)subgroups. On the other hand, significance was present between the (RLC) and (RA)of the Winvestment subgroupswhile non-significance was located between the (RC) and both the (RLC) and (RA) subgroups. Comparing similarsubgroups of the two tested investments, the Student's t-test showed non-significance between the (RC) subgroupswhile high significance was located between the (RLC) and (RA) subgroups respectively.Concerning the verticalmarginal discrepancy of the copings, applying the (RC) technique for both investments caused non-statisticalsignificance between the labial, mesial, palatal, and distal aspects.The (RLC) technique caused high significancebetween the four aspects, while the (RA) technique caused non-significance between the labial aspect only andthe others.Conclusion: The Iraqi investment generally produced less vertical marginal discrepancies (using the three differentinvesting and burn-out techniques) than the commercial investment.In order to achieve a better marginal fit, itseems that ceramometalcopings invested with the commercial investment tested are better be cast using theconventional ring investing and burnout technique


Article
An evaluation of the influence of different finishing lines on the fracture strength of full contour zirconia CAD/CAM and heat press all-ceramic crowns

Authors: Ahmed Ibrahim Khalaf Al-Joboury احمد ابراهيم خلف --- Ma’an Rasheed Zakaria معن رشيد زكريا
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 1 Pages: 54-62
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: One of the major problems of all ceramic restorations is their probable fracture against the occlusalforces. The objective of this in vitro study was to evaluate the effect of two gingival finishing lines (90°shoulder anddeep chamfer) on the fracture resistance of full contour CAD/CAM and heat press all-ceramic crowns.Materials and Methods: Thirty two maxillary first premolars were prepared to receive full contour CAD/CAM (zolid)and heat press (Cergo Kiss) ceramic crowns using a special paralleling device (Parallel-A-Prep). The teeth weredivided into four groups according to the type of finishing line prepared. Each crown was cemented to itscorresponding tooth using self-etch, self-adhesive dual cure resin cement. Following storage for 1 week in distilledwater at room temperature, teeth were subjected to thermal cycling. Fracture resistance was determined using auniversal testing machine, and the samples were investigated microscopically from the point of view of the origin ofthe failure. Statistical analysis was carried out using the one-way ANOVA and Student’s t-tests.Results: The mean values of fracture resistance for CAD/CAM group showed 1367.250+178.967 N for 90°shouldermargins and 1109.250+252.455 N for the deep chamfer margins. ANOVA test results revealed high significancebetween and within the groups. The mean values of fracture resistance for heat press group were 548.562+272.471 Nfor 90°shoulder margins and 247.912+96.995 N for the deep chamfer margins expressing statistical significance.Conclusions: The results of this study pointed to a relationship between the design of the cervical finishing line andthe fracture strength of the full CAD/CAM crowns and the full heat press ceramic crowns. Both 90° shoulder anddeep chamfer finishing lines are suitable for zolid crowns while the 90° shoulder is more suitable for the Cergo Kisscrowns than the deep chamfer preparation

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