Abstract
Purpose: This in vitro investigation was performed to assess microleakage and cusp fracture resistance of maxillary premolars specimens involving composite resin direct restorations and ceramic inlay restorations. Material and methods: Specimens were tested after artificial aging provoked by thermal and occlusal load cycling. For that purpose, 66 extracted maxillary premolars were used with six premolars in each study group. Standardized MOD cavities were prepared and classified into two main groups according to gingivalmargins location either 1mm above (A1) or 1 mm below (A2) the CEJ. Specimens were subdivided into two subgroups: Z250 composite resin direct restorations and IPS Empress glass ceramic restorations cemented with Variolink II resin-cement. Group of intact teeth specimens and two groups of A1 and A2 type prepared but not restored teeth served as control groups. Restored teeth were mounted in acrylic-resin blocks before loading and thermocycling. Microleakage was assessed by examining dye penetration scores under Zeissstereomicroscope. Cusp fracture resistance was performed using vertical static loading until failure. The fracture-load test mean values and microleakage results were statistically analyzed. Results: Investigated restorations showed insignificant difference in adaptation at enamel margins. Ceramic restorations showed better sealability and tooth structure reinforcing effects than composite restorations, especially at nonenamel margins. Conclusions: Cavity preparation produced significant weakening effect. Restorations just partly compensated weakening effect of cavity preparation. Upgrading the performance of adhesive restorations in terms of adaptation and tooth structure reinforcement poses a continuing challenge to restorative dentistry. Key words Bicuspid; Dental Bonding; Dental Cavity Preparation; Composite Resins; Metal Ceramic Alloys; Tooth Fractures; Dental Leakage Svrha: Ovo in vitro istrazivanje provedeno je na maksilarnim pretkutnjacima kako bi se procijenili mikropropusnost i otpornost kvrzica na frakturu. Materijal i metode: Uzorci su se sastojali od adhezivno vezanih direktnih ispuna i keramickih inlaya (ranije pripremljenih umetaka), a ispitani su nakon umjetno simuliranog starenja s pomocu termickog i okluzalnog ciklickog opterecenja. Za to je uporabljeno 66 tek izvadenih maksilarnih pretkutnjaka, a bilo ih je po sest u svakoj skupini. Zatim su izradeni standardizirani MOD-kaviteti i podijeljeni u dvije glavne skupine, ovisno o smjestaju gingivne stijenke i to jedan milimetar iznad (A1) ili jedan milimetar (A2) ispod cementno-caklinskog spoja (CCS-a). Nakon toga uzorci su podijeljeni u dvije podskupine: Z 250 kompozit za direktno postavljanje i IPS Empress--staklokeramicki ispun zatvoren kompozitnim cementom Variolink II. Skupina intaktnih zuba te dvije skupine s prepariranim kavitetima A1 i A2 sluzile su kao kontrola. Restaurirani zubi ulozeni su zatim u blokove od akrilatne smole i stavljeni u stroj za ciklicko-termicko i mehanicko opterecenje. Mikropropusnost je procijenjena metodom ocjenjivanja prodora boje pod Zeissovim stereomikroskopom. Rezultati: Otpornost kvrzica na frakturu ispitana je vertikalnim opterecenjem do pucanja. Srednje vrijednosti testa frakturnog opterecenja i mikropropusnosti analizirane su statisticki. Proucavani ispuni nisu pokazali vecu razliku u adaptaciji ispuna na caklinskim rubovima. Keramicki ispuni bolje su brtvili te snaznije ojacali strukturu zuba nego kompozitni, posebice na necaklinskim rubovima. Priprema kaviteta dosta je oslabila strukturu. Zakljucak: Ispuni su samo djelomice nadoknadili ucinak slabljenja zbog njegove pre-paracije. Poboljsanje adhezivnih ispuna, tj. adaptacija i pojacanje strukture zuba, stalan su izazov u restaurativnoj dentalnoj medicini. Kljucne rijeci pretkutnjak; svezivanje, dentalno; preparacija kaviteta; kompozitne smole; metalkeramicke legure; lomovi zuba; dentalno propustanje