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1 Serbian Dental J, 2008, UDC: ISSN COBISS. SR-ID Ispitivanje kruni nog mikropropuštanja kod intaktnih i karioznih zuba opturisanih metodom lateralne kompakcije gutaperke DOI: /SGS D Coronal microleakage in intact and carious teeth obturated using lateral compaction of gutta-percha eri A 1, Sukara S 2, Arbutina R 1, Trni Z 1, Gaji N 1 1 Klinika za Bolesti zuba, Stomatološki odsijek, Univerzitet u Banja Luci 2 Klinika za Preventivnu i dje iju stomatologiju, Stomatološki odsijek, Univerzitet u Banja Luci 1 School of medicine, Clinical for dentistry, University of Banja Luka 2 School of medicine, Clinical for pediatric dentistry, University of Banja Luka ORGINALNI RAD (OR) ORIGINAL ARTICLE KRATAK SADRŽAJ Uvod: Kruni no mikropropuštanje je jedan od najvažnijih faktora za uspjeh i trajnost endodontski lije enih zuba. Cilj: Cilj ovog rada je bio da se u in vitro uslovima ispita kvalitet kruni ne mikropropustljivosti kod karijeznih i intaktnih zuba opturisanih lateralnom kompakcijom gutaperke,primjenom metode bojenih rastvora. Materijal i metod: Korišteno je 40 ekstrahovanih humanih zuba podijeljenih u dvije grupe. Prvu grupu je inilo 20 intaktnih zuba (10 jednokorjenih,10 višekorjenih) a drugu grupu 20 karijesom zahva enih zuba (10 jednokorjenih,10 višekorjenih). Preparacija kanala je ura ena primjenom STEP-BACK tehnike uz obilnu irigaciju 2.5% rastvorom NaOCl. Svi kanali su opturisani metodom lateralne kompakcije primjenom paste AH PLUS u svakoj grupi. Kruni ni dio zuba je privremeno zatvaran samo CAVIT-om ili GJC i CAVITom u kombinaciji. Zubi su premazani sa 2 sloja laka i potapani u 50% rastvor AgNO 3, a potom, presijecani dijamantskim diskom u mezio-distalnom pravcu. Linearni prodor boje je provjeren stereolupom sa mikrometarskim razmjernikom i uve anjem 6 puta. Rezultati: Dobijeni rezultati su pokazali da je prodor boje uo en u 70% slu ajeva kod zuba privremeno zatvaranih samo CAVIT-om a u 10% slu ajeva kod zuba privremeno zatvaranih kombinacijom GJC i CAVIT-a.Razlika je bila statisti ki zna ajna(p<0.05) Zaklju ak: Na osnovu dobijenih rezultata može se zaklju iti da je najmanje kruni no mikropropuštanje uo eno kod intaktnih zuba koji su privremeno zatvarani kombinacijom GJC i CAVIT-a. Klju ne re i: kruni no mikropropuštanje lateralna kompakcija gutaperke, privremeno zatvaranje SUMMARY Introduction: Coronal microleakage is one of the most important factors for the success and longevity of endodontically treated teeth. Aim: The aim of this study was to evaluate in vitro the coronal microleakage in carious and intact teeth obturated with lateral compaction of gutta-percha using the dye penetration method. Materials and Methods: Forty extracted human teeth were allocated to two groups: Group I consisted of 20 intact teeth (10 single-rooted and 10 multi-rooted) and Group II comprised 20 carious teeth (10 single-rooted and 10 multi-rooted). Root canal preparation was performed using the Step-back technique and copious irrigation with 2.5% NaOCl. All root canals were obturated using lateral compaction and AH Plus endodontic sealer. The teeth were coronally filled with either CAVIT only or the combination of GIC and CAVIT, coated with 2 layers of nail varnish and immersed in 50% AgNO 3. Afterwards, the teeth were sectioned mesio-distally using a diamond disc and linear dye penetration was evaluated using a stereo loupe with a micrometer scale at x6 magnification. Results: The results showed dye penetration in 70% of teeth filled with CAVIT and in 10% of teeth filled with GIC+CAVIT. The difference was statistically significant (p<0.05). Conclusion: Based on the obtained results, it may be concluded that the least coronal microleakage was observed in intact teeth temporarily filled with the GIC+CAVIT combination. Key words: coronal microleakage lateral compaction Gutta-percha, caviti filled

2 100 Stom Glas S, vol. 55, 2008 Uvod Endodontska terapija je komplikovana mikrohirurška intervencija koja zahtijeva izuzetno veliku preciznost odnosno znanje i tehniku terapeuta. (1) Uspjeh lije enja zavisi od mnogo faktora pri emu se moraju poštovati osnovni endodontski principi lije enja po ev od pravilne obrade pristupnog kaviteta, pravilnog izbora tehnike preparacije i opturacije, odnosno kvalitetne restauracije kruni nog dijela zuba. Brojni istraživa i smatraju da je neadekvatno apikalno zaptivanje materijala za opturaciju osnovni faktor neuspjeha endodontskog lije enja. (2,3) Me utim, aktuelna istraživanja potvr uju da je za uspjeh endodontske terapije vrlo važna trodimenzionalna hermeti ka opturacija kanalskog sistema zuba i dobro kruni no zaptivanje,odnosno pravovremeno konzervativno ili protetsko zbrinjavanje endodontski lije enog zuba. (4,5,6) Smatra se da lije eni zub, nakon endodontske terapije, treba restaurisati ili protetski zbrinuti u roku od 30 dana nakon definitivne opturacije, jer neadekvatan privremeni ispun može dovesti do prodora oralnih fluida i bakterija izme u zida kanala i paste za opturaciju i uzrokovati ošte enja periapeksnih tkiva. (7,8) Da bi se obezbijedilo dobro kruni no zatvaranje neophodno je prvo ostvariti hermeti no zaptivanje sredstvima za privremeno zatvaranje a potom i sredstvima za trajne ispune. Za provjeru kvaliteta kruni ne mikropropustljivosti korištene su brojne metode i tehnike,kao što su semikvantitativne metode linearnog prodora boje (4,8,9), radioizotopi (2), SEM analize (6), trodimenzionalna kompjuterska analiza (10) i druge. Cilj ovog rada je bio da se u in vitro uslovima ispita kvalitet kruni ne mikropropustljivosti, kod intaktnih i karioznih zuba opturisanih lateralnom kompakcijom gutaperke, primjenom metode bojenih rastvora. Materijal i metod U ispitivanju je korišten uzorak od 40 ekstrahovanih zuba humanog porijekla (karijesnih i intaktnih) ekstrahovanih iz ortodontskih i drugih razli itih razloga. Ekstrahovani zubi su o iš eni od mekih naslaga i kamenca te ostavljeni dvije sedmice u alkoholu. Tako pripremljeni zubi su obra ivani okruglim, obrnuto koni nim i fisurnim turbinskim svrdlima, veli ine 14 i 16, uz vodeno hla enje da bi se dobili pristupni okluzalni i oralni kaviteti. Ulazi u kanale korjenova su obra ivani rotiraju im mašinskim instrumentima Gates Glidden veli ine od 1 do 4. Introduction Endodontic therapy is a complicated microsurgical intervention which requires high precision, knowledge and skills of the operator. 1 Treatment success depends on many factors and basic endodontic principles must be adhered to, such as adequate cavity access preparation, instrumentation and obturation techniques and quality restoration of the coronal part of the tooth. Numerous researchers believe that inadequate apical seal of obturation materials remains the main factor leading to endodontic failure. 2,3 However, current studies have confirmed that hermetic three-dimensional root canal obturation and good coronal seal i.e. timely conservative or prosthodontic restoration of endodontically treated teeth are essential for the success of endodontic therapy. 4-6 It is accepted that an endodontically treated tooth should be coronally restored within 30 days of obturation because an inadequate temporary filling may lead to the penetration of oral fluids and bacteria between canal walls and the obturation paste resulting in periapical destruction. 7,8 In order to achieve good coronal seal, it is essential that both temporary and definitive fillings provide hermetical seal. Numerous methods and techniques, such as semi quantitative linear dye penetration 4,8,9, radioisotopes 2, SEM analysis 6 or 3D computer analysis 10 have been used to evaluate coronal microleakage. The aim of this study was to evaluate in vitro the coronal microleakage in carious and intact teeth obturated with lateral compaction of gutta-percha using the dye penetration method. Materials and Methods Forty human teeth (carious and intact) extracted for orthodontic and other reasons were used in the study. The teeth were cleaned from debris and calculus and kept in alcohol for two weeks. Afterwards, access occlusal and oral cavities were prepared using round, inverted cone and fissure burs #14 and #16 in a high-speed hand piece with water cooling. Root canal orifices were prepared using rotary Gates Glidden burs #1-4.

3 Serbian Dental J, 2008, Zubi su podijeljeni u dvije eksperimentalne grupe. Prvu grupu inilo je 20 intaktnih zuba (10 jednokorjenih i 10 višekorjenih) a drugu grupu inilo je 20 karioznih zuba (10 jednokorjenih i 10 višekorjenih). Svi kanali korjenova su obra eni na isti na in STEP BACK tehnikom preparacije uz obilnu irugaciju 2.5% rastvorom NaOCl. Radna dužina je dobijena na taj na in što se proširiva br.15 uvodio u kanal dok se njegov vrh nije pojavio na vrhu korijena zuba. Zatim je proširiva vra an unazad za 1mm i ta dužina je registrovana kao radna dužina. Kanali su obra ivani ru nim instrumentima Flexicut. Svaki put kada se mijenjao kanalni instrument,kanal je obilno irigiran 2.5% rastvorom NaOCl pomo u igle br.27. Kona na irigacija je provedena sa 5ml 2.5% NaOCl. Svi kanali su prošireni do veli ine 40 a zatim osušeni papirnim poenima. Tako pripremljeni zubi su opturisani metodom lateralne kompakcije a kao siler je korištena pasta AH PLUS. U obje eksperimentalne grupe, po 10 zuba je nakon punjenja privremeno zatvarano CAVIT-om (ESPE GmbH, Seefeld, Germany) debljine 4mm. Kod drugih 10 zuba je, nakon punjenja, zagrijanim nabija em i okruglim svrdlom najprije uklonjeno 2-3 mm gutaperke iz kanala a potom postavljen GJC(FUJI IX) debljine 2 mm i krunica privremeno zatvorena CAVIT-om debljine 4mm. Zubi su uvani na temperaturi 37 o C u uslovima relativne vlažnosti(umotani u vlažnu vatu) tokom 7 dana. Zatim su svi zubi premazani sa dva sloja laka za nokte izuzev širine 1mm na spoju CAVIT-a i zida kaviteta. Ispitivanje kruni ne mikropropustljivosti obavljeno je metodom bojenih rastvora primjenom 50% rastvora AgNO 3. Zubi su držani u rastvoru srebro nitrata tokom 6 h, isprani pod mlazom teku e vode i potopljeni u 10% rastvor fotorazvija a tokom 2 h. Nakon toga su zubi dijamantskim diskom presijecani uzdužno i pažljivo odvajani. Prodor boje je provjeravan stereo lupom sa mikrometarskim razmjernikom i uve anjem 6 puta. Rezultati Dobijeni rezultati su prikazani na tabelama 1-4 i grafikonu 1. Kod svih ispitivanih zuba je uo en prodor boje. Analizom dobijenih rezultata prodor boje kod jednokorjenih zuba zahva enih karijesom uo en je u 40% uzoraka a kod jednokorjenih intaktnih zuba u 30% uzoraka. Na ena razlika nije bila statisti ki zna ajna. Kod višekorjenih zuba prodor boje je uo en u 50% uzoraka i u grupi sa karijesom i u grupi intaktnih zuba. (Tabela 1) The teeth were allocated to two experimental groups. Group I consisted of 20 intact teeth (10 singlerooted and 10 multi-rooted) and Group II comprised 20 carious teeth (10 single-rooted and 10 multi-rooted). All root canals were instrumented in the same manner, using the Step-back technique with copious irrigation with 2.5% NaOCl. The working length was determined by inserting a reamer #15 into the canal until its tip appeared at the root apex. The reamer was then retracted for 1 mm and that distance was considered to be the working length. Root canals were instrumented using hand instruments Flexicut. Between the two instruments, the canal was abundantly irrigated with 2.5% NaOCl and a #27 needle. The final irrigation was done with 5 ml of 2.5 % NaOCl. All canals were prepared to a #40 instrument and then dried using paper points. The teeth were then obturated using lateral compaction and AH Plus was used as the sealer. In both experimental groups, 10 teeth were temporarily sealed with 4 mm thick layer of Cavit (ESPE GmbH, Seefeld, Germany). In the other 10 teeth, 2-3 mm of gutta-percha was removed from the root canal using warm pluggers and round burs. Afterwards, the deep portions were filled with GIC (Fuji IX) in a 2 mm thick layer and coronal cavities with Cavit in a 4 mm thick layer. The teeth were kept at 37 C in relative humidity (wrapped in wet cotton wool) for 7 days. Afterwards, they were coated with two layers of nail varnish except for 1 mm at the Cavit-tooth junction. Coronal microleakage was evaluated using the dye penetration method with 50% AgNO 3. The teeth were kept in the AgNO 3 solution for 6 h, then rinsed under tap water and immersed in 10% photo developer solution for 2 h. The teeth were then cut longitudinally using a diamond disc and carefully separated. Dye penetration was assessed using a stereo loupe with a micrometer scale at x6 magnification. Results The results are presented in Tables 1-4 and Graph 1. Dye penetration was observed in all experimental groups. Data analysis revealed that dye penetration occurred in 40% of single-rooted carious teeth and 30% of single-rooted intact teeth. The difference was not statistically significant. In multi-rooted teeth, dye penetration was observed in 50% of specimens in both carious and intact teeth. (Table 1)

4 102 Stom Glas S, vol. 55, 2008 KARIJESOM ZAHVA ENI PRODOR BOJE INTAKTNI PRODOR BOJE DA NE DA NE N % N % N % N % JEDNOKORJENI 4 40, , , ,00 VIŠEKORJENI 5 50, , , , , , , ,00 Tabela 1. Linearni prodor boje u zavisnosti od morfološke grupe zuba. Table 1. Linear dye penetration with regard to morphological groups of teeth. Prosje an prodor boje kod intaktnih jednokorjenih zuba bio je manji (11.00 μm) nego kod višekorjenih zuba iste grupe (28.00 μm). Ova razlika je bila statisti ki zna ajna (p<0.05). (Tabela 2) The mean value of dye penetration in single-rooted intact teeth (11.00 μm) was lower than in multi-rooted teeth from the same group (28.00 μm). This difference was statistically significant (p<0.05). (Table 2) Broj prose an prodor SD SE Med Min Maks jednokorjeni višekorjeni Tabela 2. Prosje an prodor boje kod intaktnih zuba u zavisnosti od morfološke grupe. Table 2. Mean dye penetration in intact teeth with regard to morphological groups of teeth. Prosje an prodor boje kod karijesom zahva enih zuba bio je isti bilo da su jednokorjeni ili višekorjeni i iznosio je 26μm. (Tabela 3) The mean values of dye penetration in both single-rooted and multi-rooted carious teeth were the same, 26 μm. (Table 3) jednokorjeni Višekorjeni Broj prose an prodor SD SE Med Min Maks Tabela 3. Prosje an prodor boje kod zuba zahva enih karijesom u zavisnosti od morfološke grupe. Table 3. Mean dye penetration in carious teeth with regard to morphological groups of teeth.

5 Serbian Dental J, 2008, Statisti kom analizom prodora boje u grupi intaktnih zuba je utvr eno da postoji statisti ki zna ajna razlika izme u zuba ije su krunice privremeno zatvarane samo Cavit-om (prodor boje u 70% zuba) i zuba ije su krunice privremeno zatvarane kombinacijom GJC i Cavit-a. (p<0.05) (Tabela 4, grafikon 1) Statistical analysis revealed a significant difference between intact teeth filled with Cavit only (dye penetration in 70% of specimens) and those filled with GIC+Cavit (dye penetration in 10% of specimens) (p<0.05). (Table 4, graph 1) % Cavit GJC+Cavit Prodor boje da ne Grafikon 1. Linearni prodor boje u zavisnosti od materijala za privremeno zatvaranje. Graph 1. Linear dye penetration with regard to temporary filling material. U grupi karijesom zahva enih zuba na ena je statisti ki zna ajna razlika u prodoru boje izme u zuba ije su krunice privremeno zatvarane Cavit-om (60% uzoraka) i zuba ije su krunice privremeno zatvarane kombinacijom GJC i Cavit-a (30% uzoraka). (Tabela 4) In the group of carious teeth, there was a significant difference in dye penetration between teeth filled with Cavit (60% of specimens) and those filled with GIC+Cavit (30% of specimens). (Table 4) KARIJESOM ZAHVA ENI INTAKTNI PRODOR BOJE PRODOR BOJE DA NE DA NE N % N % N % N % CAVIT 6 60, , , ,00 GJC+CAVIT 3 30, , , , , , , ,00

6 104 Stom Glas S, vol. 55, 2008 Diskusija Hermeti no zatvaranje kanalnog sistema korijena endodontski lije enog zuba,odnosno kvalitetna trodimenzionalna opturacija je jedan od izuzetno važnih faktora uspjeha endodontske terapije. U ovoj studiji je analizirana kruni na mikropropustljivost kod endodontski lije enih zuba ije su krunice privremeno zatvarane Cavit-om ili kombinacijom glass ionomer cementa (GJC) i Cavit-a. U literaturi se mogu na i brojne studije koje ukazuju na zna ajan uticaj silera i tehnike opturacije na mikropropuštanje. U svojim istraživanjima Saleh i sar. (11) su provjeravali efekat silera AH Plus, Apexit-a i Real Seal na stepen mikropropuštanja i zaklju ili da je AH Plus pokazao najmanje mikropropuštanje u odsustvu razmaznog sloja. U ovoj studiji su svi zubi opturisani tehnikom lateralne kondenzacije. Prema dobijenim rezultatima nema statisti ki zna ajne razlike u prodoru boje izme u uzoraka koji su opturisani pastom AH Plus i onih koji su opturisani Apexitom što je u saglasnosti sa rezultatima Shafera i Olthoffa (12) kao i Campsa i Pashley-a (13). Shafer i Olthoff (12) ispituju i kruni no propuštanje kod AH Plus, AH 26 i RSA Roeko Seal zaklju uju da nema signifikantne razlike u prodoru boje kada se kao tehnika opturacije koristi lateralna kompakcija gutaperke. Camps i Pashley (13) su ispitivali apikalnu propustljivost AH Plus, Pulp Canal Sealer, Sealapex i Ketac Endo nakon opturacije metodom lateralne kompakcije. Pokazalo se da nije bilo statisti ki zna ajne razlike izme u silera. Razli iti rezultati mogu biti posljedica odsustva ili prisustva razmaznog sloja, neadekvatne opturacije, nedovoljne debljine privremenog ispuna ili neadekvatno postavljenog privremenog ispuna. Da bi se obezbijedilo dobro kruni no zatvaranje, neophodno je prvo ostvariti hermeti ko zaptivanje sredstvima za privremeno zatvaranje a potom i sredstvima za trajne ispune. Rezultati ovog istraživanja su pokazali da korišteni materijali za privremeno zatvaranje kaviteta nisu obezbijedili kompletno kruni no zaptivanje. Prodor boje je registrovan kod svih uzoraka. Najmanji prodor boje je uo en kod intaktnih zuba kod kojih je gutaperka uklonjena 2-3 mm iz kanala korijena i potom aplikovan glass ionomer cement (2-3 mm) a zatim je krunica privremeno zatvorena Cavit-om debljine 4 mm. Mnoge studije su potvrdile da je minimalna debljina privremenog ispuna koja može da obezbijedi korektno kruni no zaptivanje mm. To podrazumijeva preparaciju pristupnog kaviteta ali i uvanje debljine i visine zida, za željenu debljinu privremenog ispuna i dobru retenciju koja bi sprije ila pomjeranje privremenog ispuna izme u posjeta. Kod intaktnih zuba je to mogu e ostvariti jer nema gubitka zubne supstance kao kod karijesom zahva enih zuba. U klini kim uslovima to, esto,nije mogu e kada je izgubljeno puno zubnog tkiva. (14) Discussion Hermetic seal of the root canal system in endodontically treated teeth i.e. quality threedimensional obturation is one of exceedingly important factors for the success of endodontic therapy. In the present study, coronal microleakage in endodontically treated teeth temporarily filled with either Cavit or GIC+Cavit, was assessed. There are numerous literature data confirming the importance of sealers and obturation techniques on microleakage. Saleh et al. 11 studied the effect of AH Plus, Apexit and Real Seal on microleakage and concluded that AH Plus showed least microleakage in the absence of the smear layer. In the present study, all teeth were obturated using lateral compaction. The obtained results suggested there was no significant difference in dye penetration between samples obturated with AH Plus and Apexit, which is in accordance with the results of Shafer and Olthoff 12 and Camps and Pashley. 13 Shafer and Olthoff 12 evaluated coronal microleakage in AH Plus, AH 26 and RSA Roeko Seal and concluded there was no significant difference in dye penetration when lateral compaction was used as the obturation technique. Camps and Pashley 13 evaluated apical microleakage in AH Plus, Pulp Canal Sealer, Sealapex and Ketac Endo after lateral compaction. There was no statistically significant difference between various sealers. Different results may be due to the presence or absence of the smear layer, inadequate obturation, inadequate thickness or placement of the temporary filling. In order to achieve good coronal seal, it is essential that both temporary and definitive fillings provide hermetical seal. The present results showed that temporary filling materials used in the study failed to provide complete coronal seal. Dye penetration was observed in all specimens. The least dye penetration was seen in intact teeth where gutta-percha was removed from the root canal in the coronal 2-3 mm segment followed by the application of GIC (2-3 mm) and Cavit (4 mm thickness). Many studies have confirmed that the minimal thickness of a temporary filling must be mm in order to achieve adequate coronal seal. In other words, access cavity preparation should maintain the thickness and height of the cavity walls, so that temporary fillings have adequate thickness and good retention which will prevent their dislocation between two visits. In intact teeth, this is easily done as there is no tooth tissue loss which occurs in carious teeth. In clinical conditions, this is often not achievable when too much tissue is lost. 14

7 Serbian Dental J, 2008, Tetis i sar. (15) su u svojim istraživanjima uklanjali gutaperku iz kanala i krunicu zatvarali sa tri materijala (Cavit, modifikovani GJC, Kompozit) i pokazali da Cavit obezbje uje znatno bolje zaptivanje u odnosu na GJ i kompozit kada se koristi na mjestu uklonjene gutaperke u kanalu. Sli ne rezultate dobili su Imura i sar. (16) koji su, ispituju i kruni nu mikropropustljivost kavitete zatvarali Cavit-om, IRM-om i gutaperkom i zaklju ili da je Cavit superiorniji u odnosu na dva navedena materijala odnosno da obezbje uje bolje kruni no zaptivanje. Cavit je po sastavu kalcijum-sulfat-polivinil hlorid acetat. To je mekan privremeni materijal koji prilikom postavljanja apsorbuje vodu i daje posljedi nu linearnu ekspanziju 18%. (17) Postoji nekoliko razloga za postavljanje glass ionomer cementa preko gutaperke kod endodontski tretiranih zuba. Najvažniji je prevencija mikropropuštanja ili minimalno mikropropuštanje. Ukoliko je neophodno ponovno endodontsko lije enje kanala glass ionomer cement se mnogo jednostavnije uklanja nego kompozit. Osim toga glass ionomer ima bakteriostatski efekat i ostvaruje hemijsku vezu s dentinom. (18) Gemalmaz i sar. (19) nalaze da konvencionalni GJ u dodiru s vlagom gubi mehani ku snagu a površina izložena vlagi brzo postaje porozna zbog ega ima ve i stepen mikropropuštanja u odnosu na modifikovani GJC. Dobro kruni no zaptivanje neophodno je ostvariti ne samo kod materijala za privremeno zatvaranje nego i kod materijala za trajne ispune. Novija istraživanja pokazuju da nema idealnog trajnog ispuna. Prema rezultatima Brage i sar. (20) mikropropuštanje kod kompozitnih materijala je više izraženo kod kaviteta koji imaju ve i pre nik i dubinu. Ovo, naravno,potvr uje nalaze brojnih istraživa a da je za kruni no mikropropuštanje najefikasnije kada se ulaz u kanal ispuni glass ionomer cementima, kao i ve i dio krunice (umjesto dentina), a da se kompletna restauracija uradi kompozitnim materijalima. Trenutno je aktuelan kompozitni adhezivni sistem CoroSeal koji je proizveden isklju ivo za upotrebu u endodonciji. CoroSeal se postavlja preko ulaza u opturisani kanal kao barijera prodoru te nosti iz usne duplje i mikroorganizama. Tetis et al. 15 removed gutta-percha from the root canal and filled the coronal part with three materials (Cavit, modified GIC and composite) and reported that Cavit provided significantly better seal than GIC and composite when used instead of the removed gutta-percha. Similar results were reported by Imura et al. 16 who studied coronal microleakage and applied Cavit, IRM and gutta-percha. These authors concluded that Cavit was superior to the other two materials. By composition, Cavit is calcium-sulphatepolyvinyl chloride acetate. This is a soft temporary material which absorbs water and shows high linear expansion of 18%. 17 There are several reasons for the application GIC over gutta-percha in endodontically treated teeth. The most important one is the prevention of or minimal microleakage. If a retreatment is indicated, GIC is much more easily removed than composite. Besides, GIC a bacteriostatic effect and mechanicalchemical bond with dentine. 18 Gemalmaz et al. 19 have found that conventional GIC loses its mechanical power in contact with humidity and the exposed surface soon becomes porous which leads to greater microleakage compared to modified GIC. Good coronal seal must be achieved not only with temporary but also with definitive fillings. Recent studies have shown that there is no ideal material for definitive restoration. According to Braga et al. 20, microleakage around composite fillings is more evident in larger and deeper cavities. This confirms other results that, for coronal microleakage, it is most often suggested to fill the canal orifice and the larger coronal portion (instead of dentine) with GIC and to restore the rest of the cavity with composite materials. CoroSeal, a contemporary composite adhesive system for the sole use in endodontics, has been recommended for this purpose. It is applied over the obturated canal orifices as a barrier to prevent the leakage of oral fluids and microorganisms.

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