<p>U slučajevima neuspe&scaron;ne endodontske terapije, neophodno je ponovno lečenje kanala korena. Ortogradni endodontski retretman podrazumeva uklanjanje postojećeg materijala za punjenje iz kanala uz dodatno či&scaron;ćenje, dezinfekciju i ponovnu finalnu opturaciju kanala. Važan korak u toku retretmana je &scaron;to potpunije uklanjanje postojećeg kanalnog punjenja kako bi se pristupilo svim delovima kanalnog sistema. Cilj doktorske teze bio je da se ispita kvalitet čis&scaron;ćenja zidova kanala korena nakon endodontskog retretmana pomoću skening elektronske mikroskopije (SEM). Posmatran je uticaj vrste materijala za opturaciju, uticaj upotrebe rastvarača i uticaj ručnih i ma&scaron;inskih instrumenata na količinu zaostalog materijala na zidovima kanala. Takođe, ispitan je uticaj ovih faktora na apikalnu transportaciju materijala i na vreme potrebno za retretman, a utvrđena je i učestalost o&scaron;tećenja kori&scaron;ćenih instrumenata. Materijal i metode: Ukupan uzorak činilo je 125 ekstrahovanih, humanih jednokorenih zuba. Nakon preparacije kanala korena, 120 zuba je podeljeno u dve grupe i napunjeno pomoću dva različita materijala za opturaciju (gutaperkom i resilonom). U zavisnosti od tehnike uklanjanja ovih materijala, grupe su dalje podeljene u odnosu na kori&scaron;ćene instrumente (Hedstrom, ProTaper i Twisted File) i u odnosu na upotrebu rastvarača (sa i bez hloroforma). Preostalih 5 zuba, bez kanalnog punjenja, kori&scaron;ćeni su kao kontrolna grupa. Nakon zavr&scaron;enog retretmana, korenovi su uzdužnim cepanjem razdvojeni, a odabrane polovine posmatrane na SEM-u. Mikrofotografije svake trećine kanala načinjene su pri uveličanju od 500x. Količina preostalog materijala za punjenje ocenjivana je pomoću skale. Otvoreni dentinski kanalići prebrojavani su na mikrofotografijama načinjenim pri uveličanju od 1000x, u odnosu na uvek konstantnu povr&scaron;inu. Rezultati: Analiza rezultata ukazala je na postojanje statistički značajne razlike u kvalitetu či&scaron;ćenja zidova kanala u zavisnosti od uklanjanog materijala za opturaciju. Kvalitet či&scaron;ćenja zidova kanala bio je veći nakon uklanjanja gutaperke nego nakon uklanjanja resilona. Rotirajućim, ma&scaron;inskim instrumentima je efikasnije uklanjana gutaperka, a ručnim Hedstrom turpijama je bolje uklanjan resilon. Posmatrajući ceo uzorak, ProTaper instrumenti ostavljali su velike količine materijala na zidovima kanala nakon endodontskog retretmana. Međutim, uklanjanje materijala pomoću ovih instrumenata bilo je najbrže. Primena rastvarača značajno je doprinela bržem uklanjanju materijala, dok uticaj na kvalitet či&scaron;ćenja zidova kanala nije bio značajan. Posmatrajući kanal korena po trećinama, najveća količina materijala nalazila se u apikalnoj trećini, bez obzira na vrstu uklanjanog materijala i kori&scaron;ćenih instrumenata, i bez obzira na upotrebu rastvarača tokom retretmana. Učestalost o&scaron;tećenja instrumenata bila je značajno veća prilikom upotrebe Twisted File instrumenata. Apikalna transportacija materijala je bila veća tokom uklanjanja resilon materijala i kada su kori&scaron;ćene ručne Hedstrom turpije. Zaključak: Kvalitet či&scaron;ćenja zidova kanala nakon uklanjanja gutaperke je veći nego nakon uklanjanja resilona. Dizajn i vrsta instrumenata utiče na kvalitet či&scaron;ćenja zidova kanala korena. Upotreba rastvarača tokom retretmana ne utiče značajno na smanjenje količine materijala zaostalog na zidovima kanala. Ma&scaron;inski pokretani instrumenti i upotreba rastvarača značajno skraćuju vreme potrebno za endodontski retretman.</p> / <p>In cases when endodontic treatment fails, it is necessary to retreat the root canal. Orthograde endodontic retreatment requires the removal of the existing root filling material with additional cleaning, disinfection and refilling of the canal. An important step during retreatment is complete removal of existing filling materials, to regain access to all parts of the canal system. The aim of the doctoral thesis was to investigate the cleanliness of root canal walls after removal of two different obturation material. The retreatment efficacy was observed depending on the usage of solvent and different hand or rotary instruments. The amount of residual material on the canal walls was assessed using scanning electron microscopy (SEM). Also, apical transportation of the obturation material, working time and frequency of instrument damage during retreatment was recorded. Materials and Methods: The total sample consisted of 125 extracted, single-rooted human teeth. After root canal preparation, 120 teeth were divided in two groups and filled using two different obturation materials (gutta-percha and resilon). Depending on the technique of removing these materials, the groups were further divided, in relation to the used instruments (Hedstrom, ProTaper and Twisted File), as well as in relation to the use of solvent (with or without chloroform). The remaining 5 tooth without canal filling were used as a control group. After root canal desopturation, the longitudinaly splitted root halves were observed on SEM. Microphotography of each third were made at magnification of 500x. The amount of remaining filling material was evaluated by using a scale. Open dentinal tubules were counted on microphotographies made at a magnificiation of 1000x, on a surface that was always constant. Results: Analysis of the results indicated a significant difference in the cleanliness of the canal walls depending on the used obturation material. Cleanliness of the canal walls was higher after gutta-percha removal than after the removal of resilon.&nbsp; Rotary instruments were more effective in removing gutta-percha and Hedstrom hand files better removed resilon. ProTaper instruments left more residual material on canal walls, however endodontic retreatment with these instruments was the fastest. The application of solvent significantly contributed to faster material removal, while the impact on the increase of canal cleanliness was not significant. The largest amount of material remained in the apical third, regardless of the type of material removed and instruments used, and also regardless whether solvent was used for retreatment. The frequency of instrument deformation and fracture was significantly higher when Twisted File instruments were used. Apical transportation of material had a significantly higher occurrence during resilon removal and when manual Hedstrom files were used. Conclusion: Cleanliness of the canal walls was higher after the removal of gutta-percha than after the removal of resilon. The use of solvent is not significant on the increase of canal wall cleanliness, but significantly shortens the time needed for retreatment. There is a difference in the cleanliness of root canal walls depending on the used instruments. Engine-driven rotary instruments and the use of a solvent significantly shortens the time needed for endodontic retreatment.</p>

<p>Uvod: Sistem kanala korena je složena celina koja pored glavnog korenskog kanala sadrži brojne lateralne, sekundarne, akcesorne kanale, apikalne istmuse i delte, kao i razgranatu mrežu dentinskih tubula. Kako korensko kanalni sistem ne može biti u potpunosti oči&scaron;ćen i dezinfikovan postojećim tehnikama instrumentacije, irigacije i intrakanalne medikacije, uloga kanalnog punjenja se ogleda u postizanju trodimenzionalne opturacije kanalnog prostora, &rdquo;pečaćenju&rdquo; preostalih bakterija i onemogućavanju njihovog prodora u periradikularna tkiva. Ispitivanjem reolo&scaron;kih svojstava mogu se bliže odrediti karakteristike tečenja i viskoelastična svojstva endodontskih materijala. Definisanje i razumevanje reolo&scaron;kih svojstava endodontskih silera u različitim uslovima doprinosi pravilnom rukovanju materijalom shodno primenjenoj tehnici opturacije. Cilj istraživanja: ispitivanje viskoelastičnih svojstava tri različita endodontska silera, uključujući i tečenje / prodor silera u dentinske tubule u kombinaciji sa različitim tehnikama opturacije. Materijal i metode: Ukupan uzorak činilo je 132 meziobukalna i meziolingvalna kanala korena prvih donjih molara. Nakon preparacije kanala krunično-apeksnom tehnikom i ProTaper endodontskim instrumentima, uzorak je podeljen u tri grupe u zavisnosti od ispitivanog silera (AH Plus, Sealapex i EndoREZ) i dodatno u četiri podgrupe shodno primenjenoj tehnici opturacije (hladna lateralna kompakcija, monokona tehnika, opturacija sa čvrstim nosačem gutaperke i topla vertikalna kompakcija), &scaron;to je činilo ukupno 12 grupa po 11 kanala. Nakon opturacije, uzorci su poprečno presečeni na rastojanju 3, 5 i 8mm od anatomskog foramena, kako bi se dobili preseci koji odgovaraju apikalnoj, srednjoj i koronarnoj trećini kanala. Koronarne povr&scaron;ine preseka su analizirane skening elektronskim mikroskopom (SEM). Mesto najdubljeg tubularnog prodora silera je izmereno i izraženo u mikrometrima i procentualno u odnosu na ukupno rastojanje dentinski zid kanala - spolja&scaron;nja povr&scaron;ina korena. Viskoelastična svojstva endodontskih silera su ispitana na dinamičkom oscilatornom reometru, frequency sweep testom, na četiri različite temperature: 25&deg;C, 35&deg;C, 40&deg;C i 65&deg;C. Rezultati: Tehnike opturacije silerom AH Plus koje primenjuju toplotu i pritisak daju značajno vi&scaron;u dubinu prodora silera u dentinske tubule u odnosu na tehnike koje ne primenjuju. Primena toplote i pritiska tokom opturacije silerom Sealapex nema značajnu ulogu u dubini prodora silera u dentinske tubule. Tehnike opturacije silerom EndoREZ koje ne primenjuju toplotu i pritisak daju značajno vi&scaron;u dubinu prodora silera u dentinske tubule u odnosu na tehnike koje primenjuju. Dubina prodora sva tri ispitivana endodontska silera u dentinske tubule je najvi&scaron;a u koronarnoj trećini, zatim srednjoj i značajno je niža u apikalnoj trećini kanala korena. AH Plus, Sealapex i EndoREZ ispoljavaju viskoelastični karakter sa dominantnim vrednostima elastičnog modula u odnosu na vrednosti viskoznog modula, na svim zadatim temperaturama, u opsegu primenjenih frekvencija i napona smicanja. Kompleksni viskozitet svih ispitivanih silera opada sa porastom frekvencije, na svim zadatim temperaturama. Sa porastom temperature kompleksni viskozitet silera AH Plus opada, dok za silere Sealapex i EndoREZ raste. Korelacionom analizom ustanovljena je jaka negativna korelacija između kompleksnog viskoziteta ispitivanih silera i dubine prodora u dentinske tubule: opadanjem kompleksnog viskoziteta dubina prodora silera u dentinske tubule raste. Zaključak: Odabir endodontskog silera treba da je zasnovan na tehnici opturacije koja se primenjuje.</p> / <p>Introduction: The root canal system has a complex anatomy with main root canal and many lateral, secondary, accessory canals, apical isthmuses and deltas, as well as numerous branched dentinal tubules. Due to its complexity, the root canal system cannot be completely cleaned, shaped and disinfected using available techniques of instrumentation, irrigation and intracanal medication. The aim of root canal filling is to achieve a three-dimensional obturation of the root canal space, entomb residual bacteria and prevent their penetration into the periradicular tissue. Defining and understanding the rheological properties of endodontic sealers in different conditions contributes to the proper handling of the material according to the obturation technique applied. The aim: testing the viscoelastic properties of three different endodontic sealers, including the flow / sealer penetration into dentinal tubules in combination with different obturation techniques. Materials and Methods: The total sample consisted of 132 mesiobuccal and mesiolingual root canals of first mandibular molars. After root canal preparation using ProTaper endodontic instruments, in crown-down manner, the sample is divided into three groups depending on the tested sealers (AH Plus, Sealapex and EndoREZ) and additionally into four subgroups according to the obturation technique applied (cold lateral compaction, single-cone technique, carrier &ndash; based obturation and warm vertical compaction), making a total of 12 groups of 11 canals. After root canal obturation, the samples were sectioned horizontally at 3, 5 and 8mm from the anatomical foramen, in order to get the sections that correspond to the apical, middle and coronary third of the canal. The coronal surfaces of the sections were analyzed using scanning electron microscopy (SEM). The maximum depth of sealer penetration was measured and expressed in micrometers and as a percent of the total distance: canal dentinal wall - the outer surface of the root. The viscoelastic properties of endodontic sealers were measured using frequency sweep test on dynamic oscillatory rheometer, at four different temperatures: 25&deg;C, 35&deg;C, 40&deg;C and 65&deg;C. Results: Obturation techniques with AH Plus that applied heat and pressure produced a significantly higher depth of sealer penetration into dentinal tubules as compared to techniques that did not apply. The application of heat and pressure during obturation with Sealapex had no a significant role in the depth of sealer penetration into dentinal tubules. Obturation techniques with EndoREZ that did not apply heat and pressure produced a significantly higher depth of sealer penetration into dentinal tubules as compared to techniques that applied. The depth of penetration of all three endodontic sealers into dentinal tubules was the highest in the coronary third, followed by the second and was significantly lower in the apical third of the root canal. AH Plus, Sealapex and EndoREZ exhibited viscoelastic character with dominant values of elastic over viscous modulus, at all specified temperatures, in the range of applied frequencies and shear stresses. Complex viscosity of all sealers decreased as the frequency increased at all temperatures. AH Plus showed decreased viscosity as the temperature increased, while Sealapex and EndoREZ demonstrated opposite behavior. Correlation analysis has established a strong negative correlation between the complex viscosity of the tested sealers and the depth of penetration into dentinal tubules: the decrease of complex viscosity increase the depth of sealer penetration into dentinal tubules. Conclusion: The choice of endodontic sealer should be based on the obturation technique applied.</p>

Indiana University-Purdue University Indianapolis (IUPUI) / This in-vitro, prospective, randomized study microscopically compared the debridement efficacy of passive ultrasonic irrigation (PUI) using the Ultrasonic Bypass System and different irrigating protocols. Eighty extracted maxillary anterior teeth were randomly assigned to four groups. Teeth were instrumented using EndoSequence rotary instrument system and treated with passive ultrasonic irrigation with different irrigating regimens for one minute. Group one (control) was treated with hand/rotary instrumentation. Group two was treated with hand/rotary instrumentation followed by a one-minute PUI using the Ultrasonic Bypass System with 6.0-percent NaOCl. Group three was treated with hand/rotary instrumentation followed by a one-minute PUI using the Ultrasonic Bypass System with 17-percent EDTA. Group four was treated with hand/rotary instrumentation followed by a one-minute PUI using the Ultrasonic Bypass System with 30 seconds of 6.0-percent NaOCl and 30 seconds of 17-percent EDTA. Teeth were sectioned longitudinally and each half was divided into three equal parts from the anatomic apex. The half with the most visible part of the apex was used for SEM evaluation. A scoring system for debris and smear layer removal was used. Statistical analysis was performed using a Kruskal-Wallis test, which determines if there are any differences among the four groups. Following this test, a Wilcoxon Rank Sum test was used to compare each pair of groups. The addition of a one-minute PUI with the Ultrasonic Bypass System significantly enhanced the removal of smear layer when compared with the hand/rotary instrumentation with conventional irrigating solutions. The Ultrasonic Bypass System when used with the combination of 6.0-percent NaOCl and 17-percent EDTA after hand/rotary instrumentation significantly removed smear layer at the coronal, middle, and apical areas of a tooth when compared with all other groups. A one-minute PUI with the Ultrasonic Bypass System combined with NaOCl and EDTA is significantly better in smear removal and ultimately will result cleaner canal wall.

Indiana University School of Dentistry located on the campus of Indiana University-Purdue University Indianapolis (IUPUI) / This in-vitro, prospective, randomized study microscopically compared the debridement efficacy of negative pressure irrigation with the EndoVac (Discus Dental, Culver City, CA) versus the Canal CleanMax (Maximum Dental, Inc., Secaucus, NJ). Sixty extracted human canines were instrumented using a combination of hand-instrumentation with Lexicon K-type files and rotary instrumentation with ProTaper files. All canals were irrigated with 6.0-percent sodium hypochlorite and 17- percent ethylenediaminetetraacetic acid (EDTA). However, the irrigation/aspiration techniques differed among three groups of 20 randomly selected teeth. Group one (control) was irrigated with only a 12-ml Monoject syringe via 30-gauge side-vented, closed-end needle. Group two was irrigated with the EndoVac system. Group three was irrigated similar to group one, but with the adjunct of the Canal CleanMax system. All teeth were sectioned longitudinally, and the more intact sections were divided into coronal, middle, and apical thirds. Each portion of the canal was photographed with a scanning electron microscope (SEM). The photographs were scored by two independent examiners according to relative amount of debris and/or smear layer present, as well as relative number of patent dentinal tubules. These scores were statistically analyzed using a Krustal-Wallis test and Wilcoxon Rank Sum tests to determine differences between groups. The coronal aspect of root canal walls irrigated with the EndoVac system exhibited significantly less debris and/or smear layer present when compared to the coronal aspect of root canals irrigated with only a standard 12-ml Monoject syringe equipped with 30-gauge ProRinse side-vented, closed-end needle (control). There were no other significant differences in scores between any groups at any location. For all locations combined, the EndoVac system produced significantly cleaner root canal walls as compared to the control. No significant differences were seen between the Canal CleanMax and Control or Canal CleanMax and EndoVac. This study suggested negative pressure irrigation delivery with the EndoVac system during and after hand-rotary instrumentation is more effective in removal of debris and smear layer from the coronal third and combined thirds of root canal walls compared to irrigation with a standard 12-ml Monoject syringe equipped with 30-gauge ProRinse side-vented, closed-end needle.

Indiana University-Purdue University Indianapolis (IUPUI) / Introduction: Elimination of bacteria and active infection within an infected root canal system is one of the primary objectives of nonsurgical root canal treatment. One of the measures of successful root canal treatment is subsequent bone healing of periapical lesions caused by previous infection. A previous study by Yumoto et al. showed that electromagnetic wave stimulation can increase proliferation of osteoblastic cells with no cytotoxicity, and it can also up-regulate growth factors such as vascular endothelial growth factor and platelet-derived growth factor.18 They also showed increased proliferation of an immortalized osteoblastic MC3T3-E1 cell line 3 days following electromagnetic stimulation (EMS).18 Previously, Pauly et al. found increased alkaline phosphatase (ALP) activity with 10 mA EMS application to primary murine calvaria-derived osteoblastic cells with 5 pulses at 1 second per pulse, but no significant differences were found for MTS proliferation nor mineral deposition compared to a negative control group.82 Optimization of the different variables including post-treatment incubation time, current delivery, and number of pulses per treatment may be necessary to improve osteogenic activity. The use of mesenchymal stem cells from murine bone marrow may also offer a physiologically relevant model for osteoblastic regeneration of periapical lesions. Objectives: The goal of this study was to investigate and optimize the effects of electromagnetic wave stimulation (EMS) on murine bone marrow mesenchymal stem cells (MSCs) by evaluating the proliferation and differentiation of the cells after exposure to different EMS treatment regimens. Materials and Methods: 5 x104 stromal osteoblasts (SOBs) were cultured in 24-well plates in α-MEM containing 10% fetal bovine serum. Cells were then subjected to pulsed EMS treatments of 1 mA, 10 mA, and 50 mA. EMS was generated using an electromagnetic apical treatment (EMAT) device created by J. Morita MFG Corp. Proliferation was assessed via MTS assay 1 days after treatment. For osteogenic differentiation, ascorbic acid and β-glycerol phosphate were added to the culture media, and SOBs were cultured for 14 days. Afterwards, alkaline phosphatase (ALP) activity and Alizarin-red S mineral deposition were quantified as measures of osteoblast activity. Cells grown in osteogenic media without EMS treatment served as the negative control. Results: Although MSC proliferation was unaffected by different EMS treatment regimens, 50 mA EMS resulted in a decrease in ALP activity and mineral deposition by osteoblasts. Conclusions: Our findings suggest bone healing by EMS may involve a different cellular mechanism, that is not reproduced in vitro in our studies. Utilizing different amperage and EMS regimens may improve osteogenic differentiation.

<p>Već izvesno vreme u stručnoj literaturi vodi se rasprava o biokompatibilnosti materijala koji se koriste u periapikalnoj hirurgiji. Pored biokompatibilnosti, od materijala za retrogradnu opturaciju kanala korena zuba se očekuje da spreči prodor bakterija iz kanalnog sistema u okolna tkiva. Kvalitetno rubno zaptivanje, odnosno adekvatna marginalna adaptacija su među najznačajnijim faktorima za dugoročan uspeh tretmana. Cilj ovog istraživanja je bio ispitati biokompatibilnost i utvrditi da li postoji razlika u biokompatibilnosti između mineral-trioksid agregata, trikalcijum-silikatnog cementa i amalgama na osnovu tri standadna testa citotoksičnosti, kao i utvrditi marginalnu adaptaciju ispitivanih materijala za retrogradno zatvaranje kanala korena zuba. Materijali i metode: Eksperimentalni deo istraživanja je podeljen na dva dela. U prvom delu istraživanja je vr&scaron;eno ispitivanje biokompatibilnosti materijala, dok je u drugom delu vr&scaron;eno ispitivanje marginalne adaptacije na osnovu mikrofotografija dobijenih skening elektronskim mikroskopom. Ispitivanje biokompatibilnosti je izvr&scaron;eno na dve ćelijske linije, liniji mi&scaron;jih fibroblasta (L929) i liniji humanih fibroblasta (MRC-5). U eksperimentima su kori&scaron;ćene samo žive (vijabilne) ćelije. Broj ćelija i njihova vijabilnost je određena testom odbacivanja boje sa 0,1% tripan plavim. Vijabilnost ćelija kori&scaron;ćenih u eksperimentu je bila veća od 90%. Biokompatibilnost sve tri vrste materijala je ispitana na osnovu standardnih testova biokompatibilnosti: DET test, MTT test, Agar difuzioni test. Ispitivanje marginalne adaptacije je sprovedeno na 90 ekstrahovanih jednokorenih zuba interkaninog sektora gornje vilice sa intaktnom pulpom, zavr&scaron;enim rastom korena, bez frakture i resorpcije korena zuba. Izvr&scaron;ena je endodontska obrada svih zuba i nakon toga su zubi ostavljeni u vlažnoj sredini na 48h, da bi se sprečile frakture prilikom sečenja. Nakon mehaničko medikamentozne obrade i opturacije kanala korena zuba je vr&scaron;ena resekcija vrha korena zuba 3mm, a nakon toga su svi zubi preparisani do dubine od 3 mm unutar kanala, ultrazvučnim nastavcima (EMS, miniMaster Piezon scaler). Zubi su naizmenično podeljeni u 3 grupe (30 zuba po grupi). Prvu grupu čine zubi kojima je apikalni kavitet biti ispunjen amalgamom, u drugoj grupi, apikalni kavitet je ispunjen MTA, a u trećoj trikalcijum-silikatnim cementom. Nakon retrogradne opturacije, zubi su ostavljeni u vlažnoj sredini 48h, do potpunog vezivanja ispitivanih materijala. Nakon vezivanja ispitivanih materijala, zubi su sečeni longitudinalno, finom dijamantskom &scaron;ajbnom. Marginalna adaptacija ispitivanih materijala je procenjena skening elektronskim mikroskopom (SEM). Pripremljeni uzorci su posmatrani pod uvećanjima 30x, 40x, 80x i 100x. Uvećanje 30x je rađeno radi prikaza celokoupnog retrogradnog punjenja na jednom snimku, tj. spoja materijal-zub. Nakon toga je napravljeno vi&scaron;e uzastopnih snimaka sauvećanjem 80x do pune dužine materijala. Na taj način je utvrđeno postojanje i izvr&scaron;eno merenje marginalne pukotine u mikrometrima. Merenja ukupne dužine marginalne pukotine u mikrometrima u 5 tačaka sa obe strane preparata su vr&scaron;ena u softverskoj aplikaciji Image J software (National Institutes of Health, Bethesda, USA). Tačke su izabrane tako da tačka 1a i tačka 5a predstavljaju gornju i donju ivicu preparata. Tačka 3a predstavlja sredinu rastojanja između tačke 1a i tačke 5a. Tačka 2a i tačka 4a predstavljaju sredinu razmaka između tačke 1a i 3a, odnosno 3a i a5. Tačke 1b-5b su naspramne tačke. Rezultati biokompatibilnosti ukazuju na visok stepen ćelijske kompatibilnosti svih ispitivanih materijala. Međutim, DET testomnije utvrđena statistički značajna razlika u citotoksičnosti između istovetnih ispitivanih materijala u obe ćelijske linije, niti između sva tri ispitivana materijala u obe ćelijske kulture.Poređenjem rezultata MTT testa nakon 24h i 48h, kao i nakon 48h i 72h uočava se da su dobijene srednje vrednosti indeksa citotoksičnosti kod sva tri ispitivana materijala i na obe ćelijske linije manje nakon 48h, odnosno nakon 72h, &scaron;to ukazuje na oporavak ćelijskog metabolizma. Poređenjem rezultata nakon 24h i nakon 72h, uočava se znatno veći pad vrednosti indeksa citotoksičnosti nakon 72h kod sva tri ispitivana materijala i na obe ćelijske linije. U kulturi ćelija MRC5, kod sva tri ispitivana materijala postoji statistički značajna razlika između indeksa citotoksičnosti izmerenog nakon 24h i nakon 72h, kao i u kulturi ćelija L929. Agar difuzionim testom nije uočena dekolorizacija, niti liza ćelija ispod ispitivanih materijala. Ćelijski odgovor je 0/0 &scaron;to ukazuje da ovim testom nije utvrđeno postojanje citotoksičnog efekta ispitivanih materijala na ćelijske linije L929 i MRC-5. Ispitivanje marginalne adaptacije materijala je vr&scaron;eno na osnovu mikrofotografija dobijenih skening elektronskim mikroskopom.. Najpre su testirane razlike na prvoj tački merenja. Rezultati ovog testa pokazuju da postoje značajne razlike između materijala i da amalgam ima značajno vi&scaron;e vrednosti izmerenih pukotina u odnosu na preostala dva materijala, dok se vrednosti za MTA i biodentin međusobno značajno ne razlikuju. Kao jo&scaron; jedna referentna tačka uzeta je tačka merenja 5. I u odnosu na vrednosti u ovoj tački merenja zabeležene su značajne razlike između materijala. Post hoc Mann-Whitney test pokazuje da se amalgam značajno razlikuje od preostala dva materijala, dok nema značajnih razlika između MTA i biodentina. Na osnovu medijane može se videti da amalgam ima niže vrednosi u ovoj tački merenja u odnosu na preostala dva materijala. U tačkama 2-4, kao i u tačkama 1-5 (ukupno), ne postoji statistički značajna razlika u marginalnoj adaptaciji ispitivanih materijala. Rezultati biokompatibilnosti ukazuju na visok stepen ćelijske kompatibilnosti svih ispitivanih materijala. Rezultati sva tri testa pokazuju da ne postoji statistički značajna razlika u citotoksičnosti između ispitivanih materijala. MTT test pokazuje da u obe ćelijske kulture, kod istovetnih ispitivanih materijala postoji statistički značajna razlika između indeksa citotoksičnosti izmerenog nakon 24h i nakon 72h. Rezultati ispitivanja marginalne adaptacije pokazuju da u tački 1 najgore zaptiva amalgam, dok izmedju MTA i biodentina nema razlike. U tački 5 najbolje zaptiva amalgam.</p> / <p>Biocompatibility of materials, deployed in periapical surgery, has been a subject of debate in referential literature for some time now. Apart from biocompabillity, root end filling materials are expected to prevent bacteria from entering the surrounding tissue from canal system. The most important factors for successful long term treatment include marginal seal, i.e. adequate marginal adaptation. The aim of this research was to examine biocompatibility and establish the potential difference in biocompatibility between mineral trioxide aggregate, tricalcium silicate cement and dental amalgam according to three cytotoxicity tests, but also to corroborate marginal adaptation of the materials in question for retrograde seal of a root canal. Materials and methods: The experimental part of the research is divided in two parts. In the first part of the research biocompatibility of the materials was examined, while the examination of the marginal adaptation based on the micro images from scanning electron microscope was conducted in the second part. The examination of biocompatibility was executed on two cell lines, mouse fibroblast cell line (L929) and human cell line (MRC-5).Biocompatibility of all three types of material was examined based on three standard biocompatibility tests: DET test, MTT test, Agar diffusion test.The examination of marginal adaptation was carried out on 90 single-rooted tooth extractied human teeth of the intercanine sector of maxilla with intact pulp, mature apices, without root fractures or resorption. All teeth were endodontically treated. After the extirpation, irrigation and opturation, the resection of 3mm of root apex and retrograde preparation with ultrasonic instruments up to 3 mm depth inside the canal was done. Teeth were divided in three groups alternately. The First group include teeth which apical cavitation was filled with amalgam, in the Second group apical cavitation was filled with MTA, and in the Third group with tricalcium silicate cement. After the complete setting of the materials, teeth were cut in longitudinal manner, with fine, diamond tool. Marginal adaptation of the materials was assessed through scanning electron microscope (SEM). Software application Image J software was deployed to measure the total length of marginal fissure in micrometers in 5 pointson both sides of the preparation . The results of biocompatibility indicate high degree of cell compatibility of all tested materials. DET test did not assert any statistically significant difference in cytotoxicity between the same tested materials in both cell lines, nor between all three tested materials in both cell cultures. Comparing the results of MTT test after 24h and 48h, and 48h and 72h, it is noted that middle value of cytotoxicity index with all three tested materials and on both cell lines is lower after 48h, and after 72h, indicating the recovery of cell metabolism. In both cell cultures, with all three tested materials there is statistically significant difference between measured cytotoxicity indices after 24h and after 72h. Agar diffusion test did not show decolorization, nor cell lysis underneath the tested materials, which means that cytotoxic effect was not asserted on cell lines L929 i MRC-5. The examination of marginal adaptation was conducted according to micro images gained by scanning electron microscope. The results in the measure point 1 indicate there are significant differences between materials, and amalgam has significantly higher values of the measured fissures in relation to remaining two materials, whereas values for MTA and biodentine do not differ significantly. In measure point 5 significant differences were noted. Post hoc Mann-Whitney test shows that amalgam has lower values of the tested fissures in this measure point in relation to two other materials, while there were no significant differences between MTA i biodentine. In points 2-4, as well as points 1-5 (in total), there were no statistically significant differences in marginal adaptation of the examined materials. The results of all three tests show that there is no statistically significant difference in cytotoxicity between examined materials. MTT test shows that there is, in both cell cultures, with the same examined materials , statistically significant difference between cytotoxicity indices measured after 24h and after 72h. The results of the examination of marginal adaptation show that in point 1 amalgam has the worst seal, whereas between MTA and biodentine there is no difference. In point 5 amalgam has the best seal.</p>

Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this study was to evaluate the fracture resistance of three post and core systems in endodontically treated teeth by loading to failure, and to measure marginal gaps before and after cyclic loading. Sixty extracted canines were assigned to three groups. The groups tested were: 1) Single cast post and core (Group CP). 2) Prefabricated metal post and composite resin core (Group MR). 3) Glass fiber post and composite resin core (Group FR). All teeth were obturated and prepared to receive a post and core with a coping. Thirty teeth (10 from each group) were loaded to failure, and the other 30 teeth were fatigue-loaded. The marginal gaps on the facial and lingual surface of the fatigue-loaded group were measured before and after cyclic loading. There were two hypotheses for this study. The first was that the FR group would have less marginal gap opening on the lingual surface than the other groups. The second was that the CP group would have a higher load at failure than the other groups. Group CP was found to have a significantly smaller pre-loading marginal gap than group FR (p = 0.0265) and group MR (p = 0.0273), while groups FR and MR did not have a significantly different pre-loading marginal gaps (p = 0.86). Group FR had significantly less change in marginal gap than group MR (p = 0.0013). Groups CP and MR did not have significantly different changes in marginal gap (p = 0.09). Groups CP and FR did not have significantly different changes in marginal gap (p = 0.11). The three post types did not have significantly different maximum loads to failure (p= 0.49), moments of inertia at cervical area (p = 0.75), or moments of inertia at fracture site (p=0.12). There was no significant difference between groups CP, FR, and MR in the load-to-failure test. Group CP demonstrated the highest load-to-failure values; however, the highest load-to-failure mean was for group MR. All fractures observed in this study were catastrophic. Group FR demonstrated better stress distribution and caused no early fractures in the fatigue-loading group. All groups demonstrated significant marginal gap changes on the lingual surface after fatigue loading; however, group FR demonstrated <45 μm marginal gap opening. In group FR, the reduced marginal gap opening was attributed to the use of Panavia 21 with the proper surface treatments to bond to the tooth structure, the resin composite, and the metal coping.