Characteristics of dental composites and dentin restoratives relevant for optical properties of the final restoration

Abstract

High esthetic requirements present a challenge in restorative dentistry due to the complex structure of dental tissues, micromorphology and composition of dentin and enamel. Dental composite material is characterized by its excellent esthetic properties despite significant structural differences from the dental tissues. Nevertheless, optimum esthetic results are not easy to achieve and require balancing several clinical factors. The aim of this dissertation was to evaluate the effect of dentin restoratives with different optical properties than composite materials on the optical characteristics of the final restorations. This doctoral thesis investigates the optical characteristics (color and translucency) of such combined "sandwich" restorations related to their type, shade and thickness of the final composite layer. Fluorescence properties of materials, initial color and color stability and marginal integrity of combined restorations in prepared cavities in extracted teeth are also investigated in relation to the type of dentin restorative and final 'enamel' layer. Materials and Methods: The following materials were used as dentin restoratives: tricalcium-silicate cements (Biodentine, Septodont), experimental hydroxyapatite inserts (HAP), fiber-reinforced composite (EverX Posterior, GC). Filtek Z250 (micro-hybrid with Bis-GMA, 3M ESPE), Filtek Z550 (nano-hybrid, 3M ESPE), Gradia Direct (micro-hybrid without Bis-GMA, GC), of A1 or A3 shade, were used as control groups. For bulk-fill restorations nano-hybrid bulk-fill composite materials were used: Filtek Bulk Fill Posterior (3M ESPE) and Tetric EvoCeram Bulk Fill (Ivoclar Vivadent). Adhesives: Single Bond Universal (3M ESPE), Adhese Universal (Ivoclar Vivadent), GC G-aenial Bond (GC) were used with the respective composites. In the first part of the study, optical parameters of all materials, prepared in different layer thickness and shades were measured. Samples were made in standardized cylindrical plastic molds. Color (ΔE) and translucency (TP) were measured using a spectrophotometer VITA Easyshade® Advance 4.0 (VITA Zahnfabrik). The color, expressed as the deviation from ‘ideal white’, and translucency were determined according tothe CIEL*a*b* color system...

Estetski zahtevi predstavljaju izazov u restaurativnoj stomatologiji, pre svega zbog kompleksne strukture dentalnog tkiva, mikromorfologije i sastava dentina i gleđi. Dentalni kompozitni materijali odlikuju se izvanrednim estetskim svojstvima, iako se strukturalno znatno razlikuju od zubnih tkiva. Međutim, postizanje optimalnih estetskih rezultata nije uvek jednostavno i zahteva balans više kliničkih faktora. Predmet ove doktorske disertacije je ispitivanje uticaja dentinskih zamenika, bitno različitih estetskih svojstava od kompozitnih materijala, na optičke karakteristike finalne restauracije. Ispitivani su optički parametri (boja i translucencija) takvih "sendvič" restauracija, uzimajući u obzir vrstu dentinskih zamenika, vrstu, nijansu i debljinu završnog kompozitnog sloja, fluorescencija materijala, zatim inicijalna boja, stabilnost boje i marginalna mikropropustljivost ispuna u preparisanim kavitetima zuba u zavisnosti od materijala za nadoknadu dentina i završni gleđni sloj. Materijali i metode: Materijali koji su korišćeni kao dentinski zamenici su: trikacijum-silikatni cement (Biodentin, Septodont), inserti eksperimentalnog sintetičkog hidroksiapatita (HAP), kompozitni materijal ojačan staklenim vlaknima (everXPosterior, GC). Kontrolnu grupu su predstavljali univerzalni kompozitni materijali: Filtek Z250 (mikro-hibrid sa Bis-GMA-om, 3M ESPE), Filtek Z550 (nano-hibrid, 3M ESPE), Gradia Direct Posterior (mikro-hibrid bez Bis-GMA-e, GC) u dve različite nijanse A1 i A3. Kod restauracije "bulk-fill" tehnikom korišćeni su nano-hibridni bulk fill kompozitni materijali: Filtek Bulk Fill Posterior (3M ESPE) i TetricEvoCeram Bulk Fill (IvoclarVivadent). U ovom istraživanju korišćeni su adhezivi: Single Bond Universal (3M ESPE), Adhese Universal (Ivoclar Vivadent), GC G-aenial Bond (GC). U prvom delu istraživanja izmereni su optički parametri svih materijala, različitih debljina i nijansi. Uzorci su pravljeni u standardizovanim plastičnim kalupima cilindričnog oblika. Merenje je vršeno spektrofotometrom VITA Easyshade Advance 4.0 (VITA Zahnfabrik). Boja (ΔE, odstupanje od idealno bele) i translucencija (TP) su izračunate prema CIEL*a*b* sistemu...