Gyd Clarence Tam, HBSC, DDS, AAACD, FIADFE

Porcelianinių laminačių (venyrų) naudojimas priekinių dantų formai, atspalviui ir vizualinei padėčiai pagerinti ir atkurti yra įprastas estetinės odontologijos metodas. Biomimetinis dantų restauravimo tikslas yra ne tik estetika, bet ir funkciniai aspektai. Labai svarbu pažymėti, kad būtent nepažeistas gomurinio ir lūpinio paviršių emalis priekiniuose dantyse užtikrina įgimtą lenkiamąjį stiprį. Jei danties struktūra buvo pažeista dėl endodontinės prieigos, ėduonies ir (arba) traumos, reikia dėti visas pastangas, kad būtų išsaugota likusi struktūra, ir stengtis atkurti arba viršyti pradinį sveiko danties funkcionalumo lygį.

ISTORIJA

55 metų ASA II pacientė atvyko į odontologijos kabinetą dėl dantų balinimo. Buvo numatyta, kad dantų balinimas neturės įtakos jau esamos 1.2 danties porcelianinės laminatės atspalviui. Šį dantį reikės iš naujo tvarkyti baigus procedūrą, ypač jei atspalvio vertės pokyčiai bus reikšmingi. Iš pradžių pacientės dantys buvo išbalinti iki pradinio atspalvio VITA* 1M1:2M1 50:50 santykiu viršutinėje priekinėje srityje ir 1M1 apatinėje priekinėje srityje. Įgyvendinus naktinio balinimo kapa protokolą naudojant 10 proc. karbamido peroksidą per naktį 3–4 savaites, pacientei pavyko pasiekti VITA* 0M3 atspalvį tiek viršutiniame, tiek apatiniame lanke. Dėl to atsirado reikšmingas verčių neatitikimas tarp 1.2 danties su laminate ir gretimų dantų, be to, pastebėtas kontralateralinio 2.2 danties spalvos intensyvumas dėl lūpinį paviršių apimančios III klasės kompozito restauracijos. Pastarasis dantis savo matmenimis taip pat neatitiko kontralateralinio danties, todėl buvo nuspręsta abu šoninius kandžius padengti surištomis ličio disilikato laminatėmis (venyrais). Šalia esančiame iltiniame dantyje (2.3) buvo lokalizuotas lengvas ar vidutinio sunkumo gumburo viršūnės dilimas, tačiau pacientė nenorėjo šio dilimo taisyti, kol nebuvo uždėtos aptariamos laminatės. Šio etapo planuojamos šypsenos tikslas – abiejų pusių harmonija, atsižvelgiant į tai, kad artimiausiu metu planuojama sukurti papildomą netiesioginę restauraciją, atkursiančią 2.3 danties lūpinio paviršiaus apimtį ir gumburio viršūnės trūkumą.

PROCEDŪRA

Pirminiam planui, t. y. atskiram šoninių kandžių tvarkymui, skaitmeninio šypsenos dizaino protokolo nereikėjo. Leidžiamas nedidelis šio tipo dantų pokytis, nes tai yra šypsenos ypatumo ir lyties žymuo. Prieš taikant anesteziją buvo parinktas tikslinis atspalvis analizuojant nuotraukas, padarytas naudojant retraktorių ir naudojant arba ne poliarizacinius filtrus. Nuotraukos buvo paruoštos skaitmeninio atspalvių kalibravimo tikslais darant atskaitos vaizdus su 18 proc. neutralia pilkai balta pusiausvyros kortele (1 pav.).

1 pav. Referencinė nuotrauka, padaryta naudojant 18 proc. neutralią pilką kortelę

Pagrindinis atspalvis buvo VITA* 0M2 su bloko atspalviu BL2. Pacientei buvo atlikta anestezija naudojant 1,5 karpulės 2 proc. lidokaino tirpalą su 1:100 000 epinefrinu, prieš tai uždėjus padalytą koferdamą. 1.2 danties laminatė buvo perpjauta ir pašalinta iš 1.2 danties, o 2.2 dantyje baigtas minimaliai invazinis laminatės paruošimas (2 pav.). Dalinis senos restauracijos iš kompozitinės dervos keitimas buvo baigtas 12 danties mezialiniame kandamojo krašto lūpiniame ir gomuriniame paviršiuose išlaikant nepažeistą segmentą. Adhezija su senu kompozitu buvo pasiekta naudojant mikrodalelių abraziją ir silanavimo medžiagą (CLEARFIL™ CERAMIC PRIMER PLUS). Kraštai buvo išlyginti, o retrakciniai siūlai įterpti suvilgius aliuminio chlorido tirpalu. Buvo užfiksuoti paruošto danties atspalviai. Galutiniai atspaudai buvo padaryti naudojant tiek skystos, tiek tirštos konsistencijos polivinilsiloksaną metaliniame šaukšte. Pacientei buvo sukurta laikina konstrukcija ir jai nurodyta, kad reikės patikrinti atspalvį laboratorijoje pirminio kepinimo stadijoje. Laboratorijoje parengti modeliai patvirtino minimaliai invazinį atvejo pobūdį.

2 pav. 1.2 ir 2.2 dantų laminačių paruošimas

Pradėjus dirbti pacientei taikytas skausmo malšinimas ir laikinosios medžiagos pašalintos. Apdorotini paviršiai buvo nuvalyti ir paruošti surišimo procedūrai nušlifavus paviršius 27 mikronų aliuminio oksido milteliais 30–40 psi slėgiu. Laminatės įvertintos naudojant skaidrią glicerino bandomąją pastą („PANAVIA™ V5 Try-in Paste Clear“, „Kuraray Noritake Dental Inc.“). Prieš aplikuojant silanizavimo medžiagą (CLEARFIL™ CERAMIC PRIMER PLUS (3 pav.), kurios sudėtyje yra 10-MDP, buvo įterpti retrakciniai siūlai, o restauracijų vidinis paviršius 20 sekundžių apdorotas 5 proc. vandenilio fluorido rūgštimi. Danties paviršius buvo 20 sekundžių ėsdinamas 33 proc. ortofosforo rūgštimi ir tada nuplautas. Ant danties užtepta praimerio, kurio sudėtyje yra 10-MDP („PANAVIA™ V5 Tooth Primer“ (4 pav.), ir išdžiovinta pagal gamintojo instrukcijas. Tuomet aplikuota laminačių cemento („PANAVIA™ Veneer LC Paste Clear“) (5 pav.) ir uždėta laminatė. Cemento perteklius buvo tirštas ir tinkamai išlaikė laminatę savo vietoje, kol buvo vykdomos visos kraštų tikrinimo procedūros ir prieš trumpą 1 sekundės pakietinimą (6 pav.).

3 pav. CLEARFIL™ CERAMIC PRIMER PLUS, aplikuojamas ant laminačių vidinių paviršių

4 pav. „PANAVIA™ V5 Tooth Primer“ aplikavimas ant ėsdintų danties paviršių

5 pav. „PANAVIA™ Veneer LC Paste Clear“ aplikuojama ant paruoštų vidinių laminačių paviršių

6 pav. „PANAVIA™ Veneer LC Paste“ iš karto uždėjus. Atkreipkite dėmesį į klampią, tirštą cemento konsistenciją, dėl kurios pastą lengva pašalinti tiek drėgnos, tiek gelio fazės.

Cementas perėjo į gelio fazę, o tai palengvino cemento pertekliaus pašalinimą ir valymo procedūra buvo minimali (7 pav.). Prieš galutinę kietinimo procedūrą, siekiant pašalinti deguonies inhibicinį sluoksnį, kraštai buvo padengti skaidriu glicerino geliu (8 pav.).

7 pav. Cemento pertekliaus šalinimas pakietinus 1 sekundę

8 pav. Galutinis laminačių gomurinio ir lūpinio paviršių kietinimas vienu metu

Kraštai buvo užbaigti ir nupoliruoti, kad kuo labiau blizgėtų, o restauracijų okliuzija patvirtinta kaip tinkama. Iš pooperacinių vaizdų matyti puiki estetinė kraštų integracija (9 pav.).

9 pav. Pooperacinė estetinė 1.2 ir 2.2 laminačių integracija

Atliekant pakartotinį vertinimą pagal naudojant poliarizacinius filtrus padarytą nuotrauką, nustatyta, kad restauracijos į naują šypseną integruotos estetiškai ir funkcionaliai (10 pav.). Dabar planuojama estetinė 2.3 danties augmentacija, kad dantis atitiktų kontralateralinį iltinį dantį.

GALUTINĖ SITUACIJA

10 pav. Galutinis rezultatas naudojant poliarizacinius filtrus pakartotiniam įvertinimui atlikti

Dentist:

CLARENCE TAM

References

1. Magne P, Douglas WH. Rationalization of esthetic restorative dentistry based on biomimetics. J Esthet Dent. 1999;11(1):5-15. doi: 10.1111/j.1708-8240.1999.tb00371.x. PMID: 10337285.
2. Magne P, Douglas WH. Porcelain veneers: dentin bonding optimization and biomimetic recovery of the crown. Int J Prosthodont. 1999 Mar-Apr;12(2):111-21. PMID: 10371912.
3. Pongprueksa P, Kuphasuk W, Senawongse P. The elastic moduli across various types of resin/dentin interfaces. Dent Mater. 2008 Aug;24(8):1102-6. doi: 10.1016/j.dental.2007.12.008. Epub 2008 Mar 4. PMID: 18304626.
4. Source: Kuraray Noritake Dental Inc. Samples (beam shape; 25 x 2 x 2 mm): The solvents of each material were removed by blowing mild air prior to the test.

Kokybiško protezavimo svarba

Kokybiškas gydymas yra bene svarbiausias elementas siekiant patenkinti pacientų lūkesčius. Per kiekvieną vizitą pacientas nori jausti, kad juo tinkamai rūpinasi kvalifikuotas specialistas, o kėdėje praleidžiamas laikas ir vizitų skaičius turėtų būti kiek įmanoma mažesnis. Tai reiškia, kad protezuojant restauracija turi iš karto puikiai priglusti ir laikui bėgant išlikti stabili, kad nereikėtų nieko perdaryti ir skirti papildomų vizitų.

Tačiau kaip kiekvieną kartą užtikrinti, kad restauracija būtų puikios kokybės ir puikiai priglustų? Su netiesioginių restauracijų kokybe susijusios problemos gali būti tokios: odontologijos kabinete ar laboratorijoje daromos klaidos, komunikacijos problemos ir (dažnai nepastebima priežastis) žemos kokybės odontologinio cirkonio oksido naudojimas.

Cirkonio oksido restauracijos – šiuolaikiškas ir estetiškas odontologinis sprendimas

Daugiau nei prieš 20 metų cirkonio oksidas pateko į odontologijos rinką kaip metalo, naudojamo vainikėlių ir tiltų gamyboje, pakaitalas. Abi medžiagos – cirkonio oksidas ir metalas – dažniausiai buvo derinamos su porceliano sluoksniu, formuojant su metalu sulydyto porceliano arba su cirkonio oksidu sulydyto porceliano restauracijas. Vėliau keli pirmaujantys odontologinio cirkonio oksido gamintojai (pvz., „Kuraray Noritake Dental Inc.“) sutelkė dėmesį į medžiagų tobulinimą. Dėl patobulinimų originali baltos spalvos matinė pagrindo medžiaga pamažu pavirto į dantį optiškai panašia keramine medžiaga, pasižyminčia puikiomis mechaninėmis savybėmis. Naujausius skirtingų skaidrumo ir stiprumo lygių cirkonio oksido variantus daugelis odontologijos specialistų visame pasaulyje laiko geriausiu galimu restauravimo būdu įvairiems pacientams, esant įvairioms indikacijoms. Viena iš priežasčių – jiems reikia tik plono porceliano sluoksnio arba šis sluoksnis apskritai nereikalingas. Kitas dalykas yra tai, kad esant mažam minimaliam sienelės storiui cirkonio oksidas leidžia konservatyviai preparuoti dantis, bet taip pat pasižymi palankiomis ilgalaikėmis savybėmis, žinoma, jei naudojama aukštos kokybės medžiaga.

Odontologinio cirkonio oksido kokybės skirtumai

Cirkonio oksido produktų kokybė gali skirtis priklausomai nuo įvairių veiksnių, pavyzdžiui, žaliavų grynumo (sudėtyje gali būti ne tik cirkonio oksido, bet ir aliuminio oksido bei itrio oksido, taip pat dažiklių ir kt.), tikslios cheminės sudėties, grūdelių dydžio ir dalelių pasiskirstymo. Kiekvienas ruošinio gamybos proceso etapas – nuo miltelių surinkimo iki ruošinio presavimo ir pirminio deginimo – turi įtakos galutinei cirkonio oksido kokybei, t. y., mechaninėms ir optinėms savybėms.

Dėl žemos kokybės cirkonio oksido kylančios problemos

Kai yra koks nors trūkumas, susijęs su restauracijos optinėmis savybėmis – jos skaidrumu, bendra spalva ar perėjimu nuo vieno sluoksnio prie kito daugiasluoksnės spalvos struktūros ruošiniuose, problema išryškėja baigus galutinę deginimo procedūrą laboratorijoje. Gali tekti perdaryti ir galiausiai primatuojant gali pasitaikyti dėmių, taigi pacientas vargu ar bus patenkintas. Tas pats pasakytina ir apie atvejus, kai restauracija netinkamai priglunda, pavyzdžiui, dėl nehomogeniškos medžiagos struktūros. Dar blogiau yra prastas biologinis suderinamumas, paviršiaus kokybė, krašto stabilumas, lenkiamasis stipris arba atsparumas lūžiams. Šias problemas galima nustatyti tik naudojant bandymo įrangą, kuri yra labai brangi, o dažniausiai odontologijos laboratorijose jos net ir nėra. Tai reiškia, kad tokio pobūdžio trūkumai dažniausiai lieka nepastebėti tol, kol neatsiranda tikrų klinikinių problemų – pavyzdžiui, dantenų recesija, padidėjęs apnašų kaupimasis, didesnis dilimas arba anksti išryškėjantys trūkumai, galintys sukelti skausmą ir diskomfortą.

Galimų problemų ir klinikinių pasekmių pacientams apžvalga

Dantų cirkonio oksido sertifikavimas ir standartizavimas

Dėl aprašytų priežasčių specialistai sukūrė ISO standartą (ISO 6872:2015). Jame aprašomi in vitro bandymai, kuriuos turi atlikti kiekvienas Europoje ar JAV naudojamo odontologinio cirkonio oksido gamintojas, kad gautų JAV maisto ir vaistų administracijos (angl. FDA) patvirtinimą ir jo produktui būtų suteiktas CE ženklas. Šie bandymai naudojami matuojant lenkiamąjį stiprį ir atsparumą lūžiams – dvi bene svarbiausias savybes, lemiančias ilgalaikį restauracijų, pagamintų iš šios medžiagos, funkcionalumą. Kiekvienos šių Europoje ar Jungtinėse Amerikos Valstijose naudojamų medžiagų bandymų rezultatai turi būti teigiami.

Kaip įsitikinti, kad į paciento burną dedamos odontologinio cirkonio oksido restauracijos nėra padirbtos ar žemos kokybės

Visi, naudojantys šį sertifikuotą cirkonio oksidą, turėtų būti saugūs, o su medžiaga susijusi rizika turėtų būti minimali. Visgi didėjantis odontologinio cirkonio dioksido populiarumas patraukė įmonių, bandančių tiesiog gauti pelno, dėmesį. Tokios įmonės nededa reikiamų pastangų, kad užtikrintų aukštą gaminio kokybę ir gautų sertifikatą. CE ženklu nepaženklinti ir nesertifikuoti produktai turi vieną bendrą bruožą: jie neabejotinai kelia pavojų jūsų veiklai ir pacientui.

Taigi, kaip užtikrinti cirkonio oksido produkto kokybę odontologijos kabinete? Džiugi žinia – ta, kad yra kelios paprastos taisyklės. Laikydamiesi jų, įsitikinsite, kad į savo pacientų burną nededate padirbtų ar žemos kokybės odontologinio cirkonio oksido restauracijų.

Įsitikinkite, kad į paciento burną nededate padirbtų ar žemos kokybės odontologinio cirkonio oksido restauracijų.

Trys auksinės taisyklės, kad savo pacientams siūlytumėte tik aukštos kokybės cirkonio oksido restauracijas:

• Užsakykite tik tas restauracijas, kurios gaminamos jūsų šalyje arba regione, kuriame taikomi tokie patys standartai kaip ir jūsų šalyje: pavyzdžiui, Kinijos odontologijos laboratorijose gaminamoms restauracijoms taikomi žemesni standartai (taigi nėra CE ženklo) ir jos gali nepateisinti jūsų lūkesčių;
• Pasikalbėkite su savo (savo šalies) laboratorijos partneriu apie jo cirkonio oksido šaltinį: įsitikinkite, kad jis perka cirkonio oksidą iš pirmaujančių gamintojų (pvz., „Kuraray Noritake Dental Inc.“) per įgaliotuosius platintojus arba pardavėjus, kuriuos iš tiesų pažįsta;
• Venkite sandorių, kurie yra įtartinai geri: galbūt vilioja maža produkto kaina, tačiau galutinė gydymo kaina gali būti net didesnė už įprastą, jei atsiras komplikacijų.

Ilgalaikis poveikis pacientams naudojant sertifikuotą cirkonio oksido restauraciją

Jei visuomet įsitikinsite, kad jūsų odontologijos kabinete įdedama cirkonio oksido restauracija atitinka aukščiausius įmanomus kokybės standartus, ilgalaikis pacientų pasitenkinimas bus garantuotas. Nors pradinė aukštos kokybės cirkonio oksido restauracijos kaina yra šiek tiek didesnė nei prastesnės kokybės dirbinių, bendros investicijos gali būti mažesnės, nes restauracijos išsilaiko ilgiau ir jų nereikia perdaryti. Patenkinti pacientai, ko gero, labiau įsitrauks į procesą, laikysis burnos higienos ir išliks lojalūs, o tai turės teigiamos įtakos jūsų reputacijai ir pacientų bazei.

Sužinokite apie įvairius cirkonio oksido variantus ir rinkitės sertifikuotų gamintojų produktus

Jei norite pasigilinti labiau, galite palyginti kelių gamintojų sertifikuotus cirkonio oksido variantus ir sužinoti skirtumus. Pavyzdžiui, „Kuraray Noritake Dental Inc.“ yra viena iš nedaugelio odontologinio cirkonio oksidų gamintojų, kuri vykdo visą gamybos procesą, nuo pat žaliavų gamybos. Dėl šios priežasties įmonė gali kontroliuoti kiekvieną procedūros etapą ir užtikrinti išskirtinę gaminio kokybę – nesvarbu, koks medžiagos variantas pasirenkamas. Įmonės siūlomas asortimentas, kurį sudaro „KATANA™ Zirconia UTML“ (itin skaidrus daugiasluoksnis), „KATANA™ Zirconia STML“ (labai skaidrus daugiasluoksnis) ir didelio skaidrumo daugiasluoksniai HTML PLUS ir YML (didesnio stiprumo ir su skaidrumo gradacija), leidžia aprėpti beveik visas indikacijas.

Prof.  Lorenzo Breschi straipsnis

Mažiau buteliukų, daugiau pasirinkimo galimybių – tai turbūt trumpiausias būdas apibūdinti universalių dervinių cementų kategoriją. Kadangi šie dvigubo kietėjimo derviniai cementai yra savaiminės adhezijos, daugelyje klinikinių atvejų galima taikyti tik vieno komponento darbo procedūrą ir nereikia atskirų dantų ar restauracijų praimerių. Taip pasiekiamas danties ir restauracijos surišimas paprastai yra pakankamai stiprus ir stabilus esant įvairioms indikacijoms. Vis dėlto šis surišimas yra šiek tiek silpnesnis nei surišimas gaunamas naudojant įprastas kelių komponentų dervinio cemento sistemas (paprastai dantų praimerio, dervinio cemento ir restauracijų praimerio).

Be savaiminės adhezijos aplikavimo procedūros, universalūs derviniai cementai gali būti derinami su papildomais sistemos komponentais, siekiant padidinti surišimo su danties struktūra arba restauracine medžiaga stiprumą. Tai atveria naujas produkto panaudojimo galimybes: priklausomai nuo reikalingų ar pageidaujamų surišimo savybių, universalus dervinis cementas gali būti naudojamas vienas arba kartu su dantų praimeriu, restauracijų praimeriu arba abiem komponentais. Be to, tampa įmanomos hibridinės koncepcijos, pavyzdžiui, kaip aprašyta šiame straipsnyje, kuriame pagrindinis dėmesys skiriamas „PANAVIA™ SA Cement Universal“ („Kuraray Noritake Dental Inc.“).

Cementavimas savaiminės adhezijos būdu. Tinka daugeliui indikacijų

„PANAVIA™ SA Cement Universal“ yra dvigubai kietėjantis universalus dervinis cementas, kuris, kai taikoma savaiminės adhezijos procedūra, gali būti naudojamas įvairiais būdais. Surišimas su restauracinėmis medžiagomis (įskaitant silikatinę keramiką) yra stiprus net nenaudojant atskiro praimerio arba silano1-4. Taip yra dėl dviejų skirtingų adhezijos monomerų: originalaus MDP monomero ir LCSi monomero (ilgos anglies grandinės silanizavimo medžiaga, užtikrinanti stiprų cheminį ryšį su silikatine keramika). Vadinasi, dervinį cementą galima naudoti neaplikuojant ant restauracijos jokių papildomų komponentų – net ir tais atvejais, kai nepakanka retencijos ir dėl to reikia itin stipraus surišimo.

Stiprus surišimas su emaliu ir dentinu taip pat gaunamas taikant savaiminės adhezijos procedūrą. Visgi tam tikrose situacijose gali būti naudinga dar labiau padidinti surišimo su danties struktūra stiprumą naudojant dantų praimerį.

Adhezinis cementavimas. Sudėtingiems atvejams

Naudojant „PANAVIA™ SA Cement Universal“ rekomenduojamas dantų praimeris yra „CLEARFIL™ Universal Bond Quick“ („Kuraray Noritake Dental Inc.“). Jį rekomenduojama naudoti kiekvieną kartą, kai naudotojas mano, kad restauruojant reikėtų ypač stiprios ir patvarios cheminės jungties, t. y. itin sudėtingais atvejais, kai nepakanka mechaninės retencijos. Šios priemonės veiksmingumas buvo patvirtintas Japonijoje atliktame in vitro tyrime, kuriame 24 valandų mikrotempimo jungties su dentinu stiprumas buvo reikšmingai padidintas aplikavus universalaus adhezyvo5. Visgi kai naudojamas atskiras adhezyvas, itin svarbu užtikrinti visišką darbo lauko sausumą. Taip yra dėl to, kad dervinio cemento atsparumas drėgmei paprastai būna didesnis nei adhezyvų. Taigi labai rekomenduojama naudoti koferdamą.

Selektyvus adhezinis cementavimas. Žemoms atramoms ir subgingivaliniams kraštams

Tais atvejais, kai sunku tinkamai izoliuoti darbo lauką koferdamu, galima taikyti Italijos mokslininkų grupės pasiūlytą trečią aplikavimo variantą – selektyvų adhezinį cementavimą. Šiuo atveju „CLEARFIL™ Universal Bond Quick“ aplikuojamas tik tose preparuoto danties dalyse, kuriose galima tinkamai kontroliuoti drėgmę, taip pat pasikliaujant „PANAVIA™ SA Cement Universal“ savaiminės adhezijos savybėmis tose srityse, kuriose sunku užtikrinti darbo lauko sausumą. Šis metodas skirtas atvejams, kai atraminiai dantys yra su subgingivaliniu preparavimo kraštu ir (arba) atraminiai dantys itin žemi (todėl sunku uždėti koferdamą).

Selektyvaus adhezinio cementavimo metodo veiksmingumas buvo patikrintas in vitro tyrime. Jame buvo lyginamos trys adhezijos strategijos: cementavimas savaiminės adhezijos būdu, visiškas adhezinis cementavimas ir selektyvus adhezinis cementavimas, naudojant surišimo šlyties stiprio bandymą6. Bandymų rezultatai rodo, kad naudotojai gali padidinti „PANAVIA™ SA Cement Universal“ surišimo su dentinu ir emaliu stiprumą adhezyvą aplikuodami tik ant dalies danties paviršiaus. Panašūs kaip cementavimo sistemos, kurią sudaro „PANAVIA™ SA Cement Universal“ ir „CLEARFIL™ Universal Bond Quick“, rezultatai buvo gauti taikant visiško adhezinio cementavimo ir selektyvaus adhezinio cementavimo metodus.

Tais atvejais, kai sunku tinkamai izoliuoti darbo lauką koferdamu, galima taikyti Italijos mokslininkų grupės pasiūlytą trečią aplikavimo variantą – selektyvų adhezinį cementavimą.

REKOMENDUOJAMI SELEKTYVAUS ADHEZINIO CEMENTAVIMO ETAPAI

1 pav. Dantų preparavimas

2 pav. Selektyvus emalio ėsdinimas fosforo rūgšties ėsdikliu

3 pav. Universalaus adhezyvo aplikavimas ir džiovinimas ore

4 pav. Vainikėlio uždėjimas į jį aplikavus dervinio cemento

5 pav. Itin trumpas kietinimas

6 pav. Pertekliaus nuvalymas ir galutinis kietinimas šviesa

7 pav. Rezultatas pakvietus į vizitą po vienų metų

Selektyvaus adhezinio cementavimo privalumai

Be norimo (ilgalaikio) surišimo stiprumo padidėjimo, pasiekiamo aplikuojant atskirą adhezyvą ant preparuotų dantų paviršiaus ar jo dalies, šis metodas suteikia papildomų privalumų. Palyginti su daugiaetapėmis cementavimo sistemomis, šis protokolas yra paprastesnis, nes nereikia atskiro restauracijų praimerio. Jeigu naudotojas naudoja rekomenduojamą sistemą, adhezyvo nereikia kietinti šviesa. Ir, priešingai nei naudojant visiško adhezinio cementavimo metodą, pagal kurį būtina uždėti koferdamo, selektyvaus adhezinio cementavimo metodui šio etapo nereikia. Taigi pacientui tenka trumpiau sėdėti odontologinėje kėdėje ir dėl to padidėja komfortas.

Išvada

Priklausomai nuo indikacijų, klinikinių kintamųjų ir individualių pageidavimų, universalių dervinių cementų, tokių kaip „PANAVIA™ SA Cement Universal“, naudotojai gali pasirinkti metodą, kuris greičiausiai suteikia geriausią klinikinį rezultatą. Būtent šis lankstumas ir apskritai platus aplikavimo galimybių spektras paverčia šią naujoviškų produktų kategoriją iš tiesų universalia. Kadangi reikia naudoti mažiau komponentų, universalios medžiagos leidžia supaprastinti ir standartizuoti klinikines procedūras, o kadangi reikia naudoti mažiau buteliukų, jos taip pat padeda darbuotojams palaikyti tvarką ir geriau valdyti atsargas.

Dentist:

LORENZO BRESCHI

Prof. Lorenzo Breschi yra Bolonijos universiteto restauracinės odontologijos ir odontologijos medžiagų srities profesorius. Jis aktyviai dalyvauja emalio ir dentino ultrastruktūrinių aspektų tyrimuose.

L. Breschi – buvęs Odontologijos medžiagų akademijos (ADM) prezidentas, išrinktasis Europos konservatyviosios odontologijos federacijos (EFCD) prezidentas, išrinktasis Odontologijos medžiagų grupės IADR prezidentas, išrinktasis Italijos konservatyviosios odontologijos akademijos prezidentas (AIC) ir išrinktasis Tarptautinės adhezinės odontologijos akademijos (IAAD) prezidentas.

Literatūra

1. Cowen M, Cunha S, Powers JM. Novel Cement Bond Strength to Multiple Substrates DENTAL ADVISOR Biomaterials Research Center, Biomaterials Research Report, Number 132 - June 16, 2020. 2. Patel N, Anadioti E, Conejo J, Ozer F, Mante F, Blatz M. Bond Strength of Different Self-Adhesive Resin Cements to Zirconia“ (2021). Dental Theses. 62. https://repository.upenn.edu/dental_theses/62 3. Yoshihara K, Nagaoka N, Maruo Y, Nishigawa G, Yoshida Y, Van Meerbeek B. Silane-coupling effect of a silane-containing self-adhesive composite cement. Dent Mater. 2020 Jul;36(7):914-926. 4. Irie M, Tokunaga E, Maruo Y, Nishigawa G, Yoshihara K, Nagaoka N, Minagi S, Matsumoto T Shear bond strength of a resin cement to CAD/CAM Blocks for molars. P-2, 37th Annual Meeting of the Japanese Society of Adhesive Dentistry 2018. 5. Ohara N. Bonding strength of resin cement containing silane coupling agent to dentin or core resin. Results presented at the 150th meeting of the Japanese Society of Conservative Dentistry 6. Breschi L, Josic U, Maravic T, et al. Selective adhesive luting: A novel technique for improving adhesion achieved by universal resin cements. J Esthet Restor Dent 2023;1-9. doi:10.1111/jerd.13037

Case by Martin Laurik, MDT

There are so many different restorative materials out there and so many design and finishing concepts available that it often seems difficult to select the best option for a specific case. Using an allrounder like KATANA™ Zirconia YML can facilitate decision making: It is a great choice for single- to multi-unit restorations, works on teeth and implants alike, and can be adapted to individual needs by selecting a suitable design concept and adequate finishing technique. In this way, it is even possible to solve aesthetically challenging cases as the one illustrated below.

Initial situation and temporization

This patient was in need for treatment after the loss of her maxillary right central incisor and the placement of an implant in this region. As a replacement of the restorations on the other three maxillary incisors was necessary as well, it was decided to produce four crowns made of the same material – KATANA™ Zirconia YML. For aesthetic evaluation of the restorations’ length, angulations and shape in the mouth and a functional test drive, the crowns were digitally designed in full contour and milled from PMMA in the determined tooth shade A2 (Fig. 1).

Fig. 1. Full-contour PMMA crowns on the master cast.

Design, milling and effect dyeing of the zirconia crowns

Once the appearance and functional aspects of the temporary restorations were approved by the patient and the restorative team, the definitive crowns were produced. Their design was based on the full-contour design of the temporaries; however, a facial reduction of 0.6 mm was carried out by the software to create space for individualization with a small layer of veneering porcelain. The crowns were then milled from a KATANA™ Zirconia YML disc in the shade A1 – approximately one shade lighter than the determined tooth shade. To mask the uneven colour from the tooth stumps and the implant abutment, the intaglio of the crowns was treated with Esthetic Colorant in the shade Opaque. Some individual and intensified colour effects on the vestibular surface were also created with Esthetic Colorant.

Internal staining and porcelain layering

To slightly adjust the chroma and lightness, a first layer of CERABIEN™ ZR Internal Stains was added, followed by a wash bake. After the application of a first layer of CERABIEN™ ZR porcelains (Body, Enamel and Translucent) and baking (Fig. 2) – the central incisors received a layer of A1B, the lateral incisors a mixture of A1B and A2B (slightly darker to provide for a better match with the canines) with LT1, LT Natural completing the picture – additional internal staining was carried out (Fig. 3). The final layer of CERABIEN™ ZR luster porcelains (LT1, ELT2 used on the convex line angles to achieve an external reflection) was added and fixed in a fourth bake (Fig. 4).

After adjustments and very rough polishing, a self-glaze firing programme was selected (firing temperature 915 °C, holding time 5 seconds). On the highly polished incisal and palatal parts of the crowns and for contact point adjustment, CERABIEN™ ZR FC Paste Stain Glaze was applied and fixed with the same bake. The finished crowns on the model are shown in Figure 5, while Figure 6 displays the final treatment outcome.

Fig. 2. Crowns milled from KATANA™ Zirconia YML with a facial cutback of 0.6 mm after individualization with Esthetic Colorant, sintering, internal staining and the application of a first layer of porcelain.

Fig. 3. This picture shows the subtle internal stain adjustment to the ceramic mostly on the incisal part.

Fig. 4. Crowns prior to final shape adjustments and polishing.

Fig. 5. Finished crowns on the model.

FINAL SITUATION

Fig. 6. Treatment outcome.

Easy approach to beautiful restorations

The presented approach is a relatively easy way of producing highly aesthetic anterior restorations. Using an allrounder zirconia combined with a few selected effect liquids, internal stains and luster porcelains, it is possible to achieve a great optical integration even in a situation where teeth and implants need to be restored. The natural shape and surface texture of the restorations plays an important role in this context, as does the base material – a naturally shaded, highly translucent zirconia.

Dentist:

MARTIN LAURIK, MDT

Martin started working as a dental technician in 2014. In the time since, he never stopped training and learning from renowned colleagues. Continuing education courses focused on dental ceramics and occlusion in the functional concept of Slavicek. Fascinated by the beauty of natural teeth, developing an understanding of their complexity and learning how to mimic nature’s design as closely as possible has always been his primary goal, while he is well aware that there is still a lot to be learned and explored on the road to excellence.

Unlock the power of zirconia: perfect for adhesive cementation, the ideal material for a wide range of indications, and essential in minimal invasive dentistry. Time to trust zirconia bonding!

This article demystifies zirconia bonding, providing clear, practical steps to ensure long-term functionality and patient satisfaction, all based on scientific research. Master the three adhesion pillars: mechanical retention, chemical activation, and wetting capacity. Discover how to successfully prepare zirconia surfaces, avoid pitfalls like misapplying silica coating and silane, and choose proven bonding systems for optimal results. Optimise retention even with minimal tooth preparation and achieve reliable zirconia restorations. Say goodbye to doubts and hello to successful zirconia bonding!

Factors influencing retention

Loss of retention due to de-cementation or debonding is a common cause of dental prostheses' failure.  First, let’s have a look at how to cope with the three main factors significantly influencing retention: tooth preparation, restoration pre-treatment, and cement type/bonding.

Tooth preparation

The abutment tooth's height, angle, and surface texture must be considered to achieve sufficient retention and resistance from the preparation. The retention form counteracts tensile stresses, whereas the resistance counteracts shear stresses ⁴. With the proper preparation, a restoration resists dislodgement and subsequent loss.

Full coverage restorations

To achieve sufficient retention and resistance for full-coverage crowns, the tooth abutment should be at least 4 mm high, and the convergence angle should range from 6 to 12 degrees with a maximum of 15 degrees ^{1, 5-8}.

Source; Conventional cementation or adhesive luting - A guideline, Dr. A. Elsayed, Prof. Dr Florian Beuer 

Adhering to the tooth preparation guidelines is crucial for full-coverage restorations (e.g., crowns, and FDPs). These practical guidelines are designed to achieve the required retention and resistance to make conventional luting possible. However, optimal retention and resistance are, in reality, hard to achieve. An unwanted amount of sound tooth substance often should be removed to achieve a highly retentive preparation. Moreover, several studies^2,3 show that, in daily practice, the preparation angle often exceeds 15 degrees.

Minimal-invasive restorations

Minimal-invasive restorations, such as single retainer FDPs, veneers, table-tops and inlay-retained FDPs, are based on a non- or low-retentive preparation form. In this case, retention shifts from (macro-)mechanical to micro-mechanical and chemical, necessitating the use of adhesive techniques ^9-11. Even though the preparations for minimal-invasive restorations largely lack mechanical retention, the long-term success of these types of restorations is well-documented when using a suitable resin cement (e.g. PANAVIA™, Kuraray Noritake Dental, Japan), including a proper pre-treatment and bonding procedure ^{10, 11}.

In high-retentive situations, conventional luting is acceptable for full-coverage restorations*. In all other cases, choosing a resin cement is a better solution. With proper tooth preparation (e.g., shaping, (self-)etching, abrasion) and the right adhesive resin cement system, a non-retentive preparation form provides a reliable basis using mainly chemical retention and micro-mechanical retention instead of macro-mechanical retention.

*Please review the articles available regarding the debate over whether to use a conventional cementation procedure, adhesive cementing, or selective adhesive luting

Restoration pre-treatment

Zirconia is densely sintered and does not contain a glass phase. Therefore, it cannot be etched with hydrofluoric acid to create a micro-retentive etching pattern. In addition, silanes cannot effectively promote zirconia bonding. Several studies have shown that air abrasion with 50-µm alumina at a reduced pressure of 0.5 bar (0.05 MPa; 7 psi) will create a sufficient micro-retentive pattern¹² and greatly enhances the wetting capacity.

In addition to air abrasion, chemical coupling agents such as bifunctional phosphate resin monomers are used on air-abraded zirconia. Bonding with phosphate monomer-containing adhesive resin systems gives very reliable results^27,28. The use of phosphate monomer-based resin cement systems (e.g., Panavia [Kuraray Noritake Dental, Tokyo, Japan]) and/or phosphate monomer primers, such as CLEARFIL CERAMIC Primer Plus (Kuraray Noritake Dental, Tokyo, Japan)  on freshly air-abraded zirconia, offer the most reliable bonding methods today ^13,27,28. We therefor consider MDP-based composite resin cements the material choice for our bonding procedure. However, it must be stressed that contamination of the air-abraded zirconia with saliva, phosphoric acid or other contaminants will limit the formation of chemical bonds and, therefore, must be avoided.

Avoiding contamination

For optimal moisture control, absolute isolation of the working field is crucial. Minimising  the risk of contamination, avoiding exposure to oral fluids. Before restoration placement, a thorough cleaning of the abutment tooth is essential. Following trial placement, a meticulous recleaning step is recommended to remove any potential introduced contamination. KATANA Cleaner (Kuraray Noritake Dental, Tokyo, Japan) is an ideal choice due to its unique properties. Its slightly acidic pH of 4.5 allows for effective cleaning intraoral and extraoral adhesion surfaces. Additionally, the incorporation of MDP monomer technology makes it highly efficient. The MDP salt in this product effectively bonds with contaminants, breaks them down and results in easy removal by water rinsing.

Cement type/bonding

After pre-treatment of surfaces to optimise the , it is important to understand that the properties of highly translucent zirconia differ highly from those of earlier generation zirconia. Early-generation zirconium oxides, including 3 mol% yttrium oxide (3Y-TZP), are high in strength and low in translucency. With the increase in yttria, creating 4-5 mol% yttria, or higher, zirconium oxides, the number of cubic crystals increases, resulting in higher translucency but leading to a reduction in strength. Therefore, attention must be paid to zirconia type, material thickness, restoration type, and application area. These factors may influence the choice of cement based on the adhesive properties demanded for lasting restorations and high aesthetic outcomes.

PANAVIA™ V5

For a resin cement system to deliver a strong bond, it is not always enough to have it contain an appropriate adhesive monomer. It is necessary for that adhesive monomer to be polymerised effectively under different circumstances. The PANAVIA™ V5 system contains an innovative “ternary catalytic system” consisting of a highly stable peroxide, a non-amine reducing agent* and a highly active polymerisation accelerator. Since this catalytic system is amine-free, the hardened cement has unsurpassed colour stability. In addition, the highly active polymerisation accelerator, one of the components in PANAVIA™ V5 Tooth Primer, is not only an excellent reducer that promotes polymerisation effectively, but it is also capable of coexisting with the (in this product) acidic MDP. This makes it possible to create a single-bottle self-etching primer. This accelerator is also responsible for the so-called touch-cure reaction when it comes into contact with the paste. Resulting in the sealing of the dentin interface and, at the same time, allowing the paste to set even in situations where light curing is limited.

*PANAVIA™ V5 Tooth Primer applied and left for 20 seconds, followed by air drying.

The second primer in the PANAVIA V5 system is CLEARFIL™ CERAMIC PRIMER PLUS, which incorporates Kuraray Noritake Dental’s original MDP and a silane. This product is used to prime zirconia but is also an excellent choice for priming silica-based ceramics, composites, and metals.

CLEARFIL™ CERAMIC PRIMER PLUS, which contains the original MDP, applied and dried.

The PANAVIA™ V5 full adhesive resin cement system consists of all three above-mentioned components, always used in the same way, independent of the material, for a straightforward procedure to ensure reliable bonding. The PANAVIA^TM V5 systems offer try-in pastes to visualise the final results before final cementing and confirm the appropriate shade of the resin cement to be used.

PANAVIA™ VENEER LC

Offering a flexible workflow and high bondability of thin, translucent restorations like veneers but also inlays and onlays, PANAVIA™ Veneer LC was designed. It is a light-curing resin cement system allowing a long working time of 200 seconds under ambient light*. This allows multiple veneers to be placed simultaneously without racing against the setting. The final light-curing can be started anytime after positioning the provisions. The PANAVIA™ Veneer LC cementing system includes PANAVIA™ Tooth Primer and CLEARFIL CERAMIC PRIMER Plus as primers to chemically interact with the adhesive surfaces.

PANAVIA™ Veneer LC Paste applied and the laminate veneer seated. In this case six veneers were simultaneously placed during one session.

Unpolymerized excess paste removed with a brush. PANAVIA™ Veneer LC Paste is a light-cured type rein cement, designed to provide sufficient working time.

This photo shows the results after the final light curing. Since the excess cement was easily removed, there were almost no cement residues.

PANAVIA™ SA CEMENT Universal

Still, clinicians seek efficiency and effectiveness in everyday practice by using a straightforward but durable resin cement solution. PANAVIA™ SA Cement Universal is developed to offer this ease-of-use property without losing focus on bonding properties.  PANAVIA™ SA Cement Universal is developed with the original MDP monomer in the hydrophilic paste compartment, allowing for chemical reactiveness with zirconia and tooth structure. The other compartment contains the hydrophobic paste, to which a unique silane coupling agent, LCSi monomer, is added, which allows the cement to deliver a strong and durable chemical bond to silica-based materials like porcelain, lithium disilicate and composite resin*. Furthermore, PANAVIA™ SA Cement Universal is less moisture sensitive than full adhesive resin cement systems. This also makes it the ideal cement in situations where rubberdam isolation is difficult.

*The product is available in both auto mix and hand mix options.

*Old PFM bridge (shown here) removed, and existing preparations modified to accommodate a 3-unit KATANA™ Zirconia bridge. The upper right canine was prepared to receive a single-unit KATANA™ crown.

Before

After. Seating & Final Smile. PANAVIA™ SA Cement Universal and CLEARFIL™ Universal Bond Quick were used for cementation and bonding. “I love the ease of use and clean-up with PANAVIA™ SA Cement Universal, and its MDP monomer creates a strong chemical bond to the tooth structure and zirconia. CLEARFIL™ Universal Bond Quick has a quick technique without reducing bond strengths, releases fluoride and has a low film thickness. I simply rub CLEARFIL™ Universal Bond Quick into the tooth for a few seconds and air dry. There is no need to light-cure, since it cures very well with PANAVIA™ SA Cement Universal. The patient was very happy with the results. She loved that she no longer saw metal margins, and her smile was much more uniform and lifelike.” Dr. Kristine Aadland

*Images are a part of a case by Dr. Kristine Aadland; 3-Unit anterior maxillary

Bonding to zirconia in three steps

Over the last century, the popularity of highly translucent zirconia has skyrocketed due to its excellent properties and wide range of anterior and posterior clinical applications. Because zirconium oxide prostheses are, if processed correctly, antagonist-friendly and easy (and relatively inexpensive) to fabricate, the material keeps gaining popularity in dentistry.

Several steps need to be taken into account for reliable and durable bonding. Years of research on achieving high and long-term bond strength to zirconia have concluded into three practical steps, summarised as the APC concept¹³ as a reliable procedure guideline.

APC-Step A

Zirconia should be air-particle abraded (APC-Step A) with alumina or silica-coated alumina particles; the sandblasting or micro-etching procedure. Air abrasion with a chairside micro-etcher using aluminium oxide particles (size: up to 50 μm) at a low pressure of 0,5 bar (0.05 – 0.25 MPa) is sufficient.^14,18,25-27

APC-Step P

The subsequent step includes applying a special ceramic primer (APC-Step P), which typically contains specially designed adhesive phosphate monomers, onto the zirconia adhesive surfaces.^29,30 The MDP monomer has been shown to be particularly effective at bonding to metal oxides like zirconium oxide.

APC-Step C

Dual- or self-cure resin cement systems should be used to reach an adequate C=C conversion rate underneath the zirconia restoration since the lack of translucency in zirconia reduces light transmission.¹³ However, in cases where high-translucent zirconia (HTZr0₂) is used, the zirconia transmits light so that the shade of composite or resin cement might influence the final appearance of such restorations. It is, thereforebased on the individual situation and shade of the abutment tooth.

The APC zirconia-bonding concept is not limited to intra-oral situations and can also be applied in the laboratory for implant reconstructions that include cemented zirconia components.

Conclusion

Rapid developments in high-quality translucent zirconia have made the utility and reliability of adhesive cementing systems even more crucial. This applies to fully opaque restorations but also minimally invasive and ultra-translucent restorations of low thickness. In all cases, the longevity of the bonding and, thus, the provision directly affects patient  satisfaction. By taking into account the three primary parameters we have discussed in this article and following the predictable APC protocol, you will successfully realise durable bonded zirconia restorations from now on.

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24. Blatz M.B., Chiche G., Holst S., Sadan A. Influence of surface treatment and simulated aging on bond strength of luting agents to zirconia. Quintessence Int. 2007;38 (9):745-753

25. Quaas A.C., Yang B., Kern M., Panavia F 2.0 bonding to contaminated zirconia ceramic after different cleaning procedures. Dent Mater. 2007;23(4):506-512

26. Song J.Y., Park S.w., Lee K., et al. Fracture strength and microstructire of Y-TZP zirconia after different surface treatments. J Prosthet Dent. 2013;110(4):274-280

27. Koizumi H., Nakayama D., Komine F., et al. Bonding of resin-based luting cements to zirconia with and without the use of ceramic priming agent. J adhes Dent. 2012;14(4):385-392

28. Nakayama D., Koizumi H., Komine F., et al. Adhesive bonding of zirconia with single -liquid acidic primers and a tri-n0butylborane initiated acrylic resin. J Adhes Dent. 2010;12(4):305-310

29. Alnassar T., Ozer F., Chiche G., Blatz M.B. Effect of different ceramic primers on shear bond strength of resin-modified glass ionomer cement to zirconia. J Adhes Sci Technol. 2016;DOI:10.1080/01694243.1184404

30. Blatz M.B. Long-term clinical success of all-ceramic posterior restorations. Quintessence Int. 2002;33(6):415-426

31. Mante F.K., Ozer F., Walter R., et al. The current state of adhesive dentistry: a guide for clinical practice. Compend Contin Educ Dent. 2013;34:Spec 9:2-8

32. Ozcan M., Bernasconi M. Adhesion to zirconia used for dental restorations: a systematic review and meta-analysis. J Adhes Dent. 2015;17(1):7-26

33. Inokoshi M., De Munck J., Minakuchi S., Van Meerbeek B. Meta-analysis of bonding effectivenss to zirconia ceramics. J Dent Res. 2014;93(4):329-334

Abrasion and shape correction was also the major reason for this 58-year-old female patient to ask for cosmetic dental treatment. She was unhappy with the appearance of the anterior teeth in the maxilla, which showed signs of tooth wear and discolouration. The selected treatment approach was composite veneering with CLEARFIL MAJESTY™ ES-2 Universal in the shade UD. The shade was selected based on the indication and the somewhat darker shade of the patient’s natural teeth.

Fig. 1. Initial clinical situation.

Fig. 2. Treatment outcome.

Reasons for selecting universal dark:

- For older patients (tooth shades A3 and darker)

- Situations in which light easily passes through the composite (e.g., Class III, Class IV)

Universal dark properties:

- High light scattering effect

- Well-balanced translucency

Dentist:

JUSUF LUKARCANIN

Dr. Jusuf Lukarcanin is a Certified Dental Technician (DCT) and a Doctor of Dental Science (DDS). He studied dentistry at the Ege University Dental Faculty in Izmir, Turkey, where he obtained a Master‘s degree in 2011. In 2017, he received a Ph.D. degree from the Department of Restorative Dentistry of the same university. Between 2012 and 2019, Dr. Lukarcanin was the head doctor and general manager at a private clinic in Izmir.

Between 2019 and 2020, he worked at Tinaztepe GALEN Hospital as a Restorative Dentistry specialist, between 2020-2022 he worked at MEDICANA International Hospital Izmir as a Restorative Dentistry specialist. Currently he is an owner of a private clinic for aesthetics and cosmetics in Izmir.

Presented by Kuraray Noritake Dental Inc.

Highly translucent multi-layered zirconia developed by a proprietary material and manufacturing method from Japan

CURRENT STATUS AND FUTURE PROSPECTS OF ZIRCONIA RESTORATIONS

In this issue, we asked Markus B. Blatz, Professor at the University of Pennsylvania, USA, Aki Yoshida (Gnathos Dental Studio) and Naoki Hayashi (Ultimate Styles Dental Laboratory), both dental technicians active in the USA and international instructors for Kuraray Noritake Dental Inc., to give their views on zirconia restorations and their outlook for the future.

WITH THE INTRODUCTION OF ZIRCONIA, THE MAINSTREAM OF PROSTHETIC TREATMENT HAS SHIFTED FROM METAL CERAMICS¹ TO ZIRCONIA CERAMICS². WHAT CHANGES HAVE OCCURRED WITH THE INTRODUCTION OF ZIRCONIA?

Blatz: My mentor for my first Ph.D. in dental materials was in the group that developed lithium disilicate and glass-infiltrated alumina. Therefore, I have seen the evolution of dental ceramic materials, including zirconia, which is the subject of this presentation, up close and personal.

Early zirconia was white, opaque, and not as esthetic as today. However, there is no doubt that zirconia ceramics were much more esthetic than metal ceramics. At the same time, however, we often heard the opinion that bilayer zirconia ceramic restorations were problematic, and this provoked much discussion. We conducted a large study in collaboration with a Boston laboratory to compare more than 1,000 posterior porcelain-fused-to-metal crowns and 1,100 posterior porcelain-fused-to-zirconia crowns and found no difference in chipping or fracture rates after about seven years. This proves that bilayer zirconia ceramics are safe when used with the proper veneering materials and the proper sintering and cooling protocols. The fact that zirconia became established as it is today is a major change for dentistry in general.

Yoshida: I also switched from metal ceramics to zirconia ceramics, and now I don't use metal anymore. It used to take a lot of time and effort to invest and cast metal, observe it with a microscope, and fit it. Considering the recent rise in metal prices, it has also become more cost-effective. In addition, I am allergic to metal and have a skin rash every time I have a prosthetic processed, so the shift to zirconia ceramics as the mainstream prosthetic is a welcome change. Of course, the use of zirconia has also improved esthetics. The translucency of zirconia is the greatest advantage that metal does not have.

Hayashi: Yes, that's right. The big advantage of zirconia is that if the abutment is not strongly discolored, it no longer needs to be treated with an opaquer. It was not easy to control the reflection of light from the operative tooth when fabricating metal ceramics. In addition to the esthetic advantage, the prosthetic space can be thinner than that of metal ceramics.

1. Metal ceramics: Prosthetic made of metal frame with porcelain.
2. Zirconia ceramics: Prosthetic made of zirconia frame with porcelain.

THE YEAR 2023 MARKED THE 10^TH ANNIVERSARY OF THE FIRST MULTI-LAYERED ZIRCONIA – KATANA™ ZIRCONIA ML. SINCE THEN, HOW DO YOU THINK HIGHLY TRANSLUCENT MULTI-LAYERED ZIRCONIA HAS REVOLUTIONIZED PROSTHETIC DEVICE MANUFACTURING?

Yoshida: I feel the ability to extend the zirconia frame to the occlusal surface and the incisal edge is the greatest advantage of using highly translucent multilayered zirconia. This allows us to provide crowns of both esthetics and strength, even for patients with para function. I have also made a zirconia Maryland bridge using highly translucent multi-layered zirconia, and it is doing very well. There are some cases where it is not possible to use zirconia, but still, it is wonderful to have a wider range of options.

Blatz: Many people still have the impression that zirconia cannot be bonded to tooth structure, but resin cement can be used to bond zirconia to tooth structure after proper pretreatment. Clinical studies of resin-bonded zirconia bridges have shown very high success after 10 or 15 years. Currently, resin bonding is recommended for very thin, highly translucent zirconia, rather than cementation. However, it should be added that this requires the dentist and technician to understand the proper bonding technique for zirconia.

In addition, Kuraray Noritake Dental's multi-layered zirconia has revolutionized monolithic zirconia without the need for veneering porcelain. However, this has also resulted in the need for dental technicians to shift to a different approach: instead of building up the restoration as with veneering ceramics, esthetic features are created on the outer surface in each case.

Maxillary 6 anterior monolithic crowns (Markus B. Blatz)

Fig. 1a and b: Initial examination.

Fig. 1c: Simulation of final prosthetic restoration.

Fig. 1d: Completed prosthetic on model (monolithic crown using KATANA™ Zirconia STML).

Fig. 1e and f: Final restoration (Dr. Julian Conejo and Sean Han, CDT).

Two cases of Maryland bridge and laminate veneers and a mandibular canine single crown implant superstructure (Aki Yoshida)

Fig. 2a and b: Case 1: A case of a congenital defect of a lateral incisor was restored with a Maryland bridge. Since the proximal and distal width of the defect was greater than the central incisor, a non-prep veneer was fabricated on the central incisor to balance the proportions. KATANA™ Zirconia STML was used for the Maryland bridge. Note the harmony between the zirconia frame extended to the incisal edge and the transparency of the laminate veneers made of Super Porcelain EX-3™ on the central incisors. This case demonstrates the characteristics of zirconia, which combines strength and esthetics.

Fig. 3a to c: Case 2: A case of a screw-retained crown restoration of an implant placed in a mandibular canine tooth. Extension of the zirconia frame from the entire lingual side to the incisal margin prevents fracture of the porcelain by the screw access hole edges and canine guides. KATANA™ Zirconia STML provides natural transparency even when zirconia is exposed at the incisal edge.

Maxillary 4 Anterior teeth implant bridge (Naoki Hayashi)

Fig. 4a to f: Implant bridge of maxillary four anterior teeth using implants placed in the maxillary bilaterallateral incisors as abutments and maxillary bilateral central incisorsaspontics. The lingual side is fully backed with zirconia and the labial side is minimally layered with CERABIEN™ ZR.

Hayashi: Indeed, the highly translucent multilayered zirconia has expanded the possibilities of monolithic crowns. For patients with high occlusal forces, monolithic crowns are suitable in terms of strength, and with the use of highly translucent multilayered zirconia, it is possible to achieve a certain level of esthetics with monolithic crowns. In fact, some patients are happy with it. However, at least in the current situation, we believe that if patients and dentists want high-end esthetics, then porcelain buildup is necessary, and monolithic crowns are only an option.

Blatz: The variety of options available is the advantage of zirconia. The dentist and the technician can work together to provide the best possible outcome for the patient.

Yoshida: In terms of options, Kuraray Noritake Dental's zirconia can be sintered in a short time (approximately 90 minutes) in addition to the normal sintering time (7 hours) using a zirconia raw material and manufacturing method developed by Kuraray Noritake Dental, which is an advantage in that it can be used for immediate restorations, remanufacturing and other unexpected situations.

FINALLY, DO YOU HAVE A MESSAGE FOR THE NEW GENERATION OF DENTISTS AND DENTAL TECHNICIANS?

Blatz: I encourage my students and colleagues to always do their best. This leads to good results, makes you happy, and makes you feel satisfied with your life. Some people only try to get rich, but just accumulating wealth is never happiness. The second is to keep an open mind. Nowadays, we are inundated with information through social media.

Some of it is very stimulating and wonderful, but there is also a lot of it that is wrong. On the other hand, there are those who believe that everything one leader says must be done. I would like to tell them, "Make sure you get your information from reliable sources, and then choose reliable information for yourself. Dentistry is changing, so let's keep an open mind. The most important thing is that the patient is ultimately satisfied with the results.

Hayashi: I would like the future generation to learn more about tooth morphology, occlusion, and fit. Color is the essence of the quality of the final prosthetic device, but we need to learn tooth morphology, occlusion, and fit before we learn color. We are all about creating a prosthetic device that will function in the patient's mouth for the long term, and that is our goal. There will be new technologies and materials in the future, but their essence will never change. I hope that you will always remember what is important in your clinical practice. This is why basic knowledge of anatomy and function is necessary.

Yoshida: New technologies and materials will continue to emerge. But human teeth will not change. The most important thing is to provide the best possible care to the patient. I hope that you will accumulate such experiences, and that when you reach the end of your life, you will be able to say that you are glad you chose this profession.

Thank you very much for the meaningful discussion today.

Source: QDT Vol.49/2024 April
The magazine may not be printed from the web and may not be forwarded
No reproduction or reprinting allowed

Dentists:

KATANA™ Zirconia YML offers an unmatched blend of aesthetics and mechanical properties, but also provides for cost and time efficiencies.

Recognised for its strength and density at point of manufacture, the material delivers incredible hardness in its green state. This offers the fully validated opportunity to make adjustments in morphology directly after milling.

These qualities, along with its strength and translucency once sintered, deliver the possibility to produce a wide range of high aesthetic indications. KATANA™ Zirconia YML has set a new benchmark in prosthetic dentistry.

It provides dental technicians with a material that is truly universal with no compromises required.

KATANA Zirconia YML in a Nutshell

KATANA Zirconia YML represents a pinnacle of zirconia technology. With its multi-layered structure, it offers a seamless gradation of colour, strength and translucency that mimics natural teeth, making it an ideal choice for the entire indication spectrum.

The material's unique composition allows for high-speed sintering (up to 3-unit bridges), which significantly reduces production time without sacrificing optical or mechanical properties.

Colour Gradation and Physical Properties

The colour gradation of KATANA Zirconia YML is designed to replicate the natural colour transition of human teeth, from the dentin core to the translucent enamel surface.

This combined with the material's impressive flexural strength of up to 1,100 MPa and translucency of up to 49%, enables the production of restorations that are virtually indistinguishable from natural dentition.

Applications and Advantages of KATANA Zirconia YML

KATANA™ Zirconia YML's versatility extends to a wide range of indications, including crowns, veneers, inlays, onlays, and bridges of all sizes. With its strong body and highly translucent enamel layer, it offers exactly the properties required for an unlimited indication range.

Positioning of restorations in KATANA™ Zirconia YML discs is extraordinarily easy. The reason is that the gap between the lowest flexural strength found in the enamel area and the highest flexural strength found in the lowest body layer is comparatively small. Moreover, the Body Layer 1 that is found adjacent to the enamel layer already offers a flexural strength that is higher than the 800 MPa requested for bridges with four or more units. Consequently, the material is classified as a Class 5 zirconia and users are on the safe side whenever they place their long-span restorations in the middle of the blank.

Positioning of long-span restorations in the middle of the disc.

Revolutionizing Sintering with High-Speed Capabilities

One of the groundbreaking aspects of KATANA Zirconia YML is its compatibility with high-speed sintering protocols. This capability allows dental laboratories to expedite the production process, delivering high-quality restorations in a fraction of the time traditionally required. Sintered during normal working hours at daytime, small restorations can be finished within hours, while the sintering load at night is reduced automatically. Great option not only for rush cases!

The high-speed sintering process does not compromise the material's optical or mechanical properties, maintaining its aesthetics and strength.

Recommended Finishing Techniques for Optimal Results

KATANA Zirconia YML is a beautiful and aesthetic material in its own. Therefore, when it comes to finishing, CERABIEN™ ZR FC Paste Stain is a great option.

KATANA Zirconia YML: A Testament to Innovation in Dental Materials

KATANA Zirconia YML stands at the forefront of dental material technology, offering outstanding aesthetics, strength, and efficiency. Its introduction has marked a significant advancement in the capabilities of dental technicians, allowing for the creation of restorations that truly mimic the beauty of natural teeth in a fraction of time.

As the dental industry continues to evolve, KATANA Zirconia YML remains a testament to the relentless pursuit of excellence in restorative dentistry.

For more detailed information on KATANA Zirconia YML, including technical guide, FAQs and Clinical cases, visit Kuraray Noritake Dental's YML dedicated page.

Interested in articles, user experience or clinical cases using KATANA Zirconia YML? Check the blog section of our website! 

Mathias Fernandez Y Lombardi

EU Scientific Manager
Dental Ceramics & CAD/CAM Materials
Kuraray Europe GmbH

With PANAVIA™ SA Cement Universal and KATANA™ Zirconia

By using PANAVIA™ SA Cement Universal and its proprietary dual-monomer technology, you can now simplify the bonding of restoration to implant abutments without the use of separate primers or silane. Independent research has confirmed this new dual-monomer technology does not sacrifice adhesion or durability on glass-based ceramics or zirconia. The technique, in this case study, is for custom fabricated abutment & KATANA™ Zirconia YML crown, however, the basic technique on the treatment of the abutment and restoration may be used with any implant restoration combination as long as the proper surface treatments for type of material is followed.

INITIAL FIT OF ABUTMENT & RESTORATION

Basic technique on the treatment of the abutment and restoration.

Fig. 1. Check Initial Fit of Abutment & Restoration: abutment & crown margins should be checked to ensure proper fit.

Fig. 2. Protect base of implant with putty or light-cure block-out resin. The base of the implant should be covered so that it is not air abraded accidentally.

Fig. 3. Abrade titanium abutment with 50 μm alumina oxide powder.

Fig. 4. Clean abutment with KATANA™ Cleaner: Apply KATANA™ Cleaner by rubbing each area for 10 seconds.

KATANA™ Cleaner is a universal cleaner that is indicated to clean metal, zirconia & glass-based restorations. It is also an intra oral cleaner that may be used on dentin and enamel.

TREATMENT OF KATANA™ Zirconia RESTORATION WORKFLOW

Bonding to zirconia has been proven to be durable in research going back to the 1990’s with the original MDP adhesive monomer in the PANAVIA™ resin cements. The three requirements to bonding zirconia are:

1. Air abrade zirconia with 50 μm alumina oxide powder.
2. Clean zirconia
3. Apply an MDP-Based Primer or resin cement. PANAVIA™ SA Cement Universal contains the original MDP that was developed & patented in 1981 by Kuraray Dental.

Fig. 1. Air abrade KATANA™ Zirconia at 14-58 psi.

Fig. 2. Dispense & mix PANAVIA™ SA Cement Universal (it is available in automix or handmix formulations).

Fig. 3. Apply PANAVIA™ SA Cement Universal to the abutment or inside the crown.

Fig. 4. Seat restoration on abutment.

Fig. 5. Remove excess resin with a dry micro-applicator or brush.

Fig. 6. You may light-cure the margins after cleaning up all excess resin. If you fully cure excess resin, It can be difficult to remove. If difficult to remove, change curing time or distance with your light.

Fig. 7. Leave restoration on abutment to self-cure fully for approximately 10 minutes at room temperature.

Fig. 8. Final check of custom abutment KATANA™ Zirconia YML crown on model.

Dentist:

JEAN CHIHA

Technician Jean Chiha CDT, Santa Ana, CA USA

Mr. Chiha is the owner of North Star Dental Laboratory and Milling Center, Santa Ana, CA, and has served as President of the Dental Lab Owners Association of California since 2013. He is a 1985 graduate of Institut Dento Technic, a private dental technology school in France. Mr. Chiha lectures internationally on dental communication and case planning. Jean lectures around the world on a variety of topics and has carved out a niche with his extensive knowledge of zirconia. Affectionately referred to as “Mr. Katana” due to his involvement in the creation of the material.

With PANAVIA™ SA Cement Universal

By using PANAVIA™ SA Cement Universal and its proprietary dual-monomer technology, you can now simplify the bonding of any restoration to implant abutments without the use of separate primers or silane. Independent research has confirmed this new dual-monomer technology does not sacrifice adhesion or durability on glass-based ceramics or zirconia. The technique, in this case study, is for Ti-Base Implants, however, the basic technique on the treatment of the abutment and restoration may be used with any implant restoration combination.

TREATMENT OF TITANIUM ABUTMENT

Fig. 1. After attaching the abutment to the implant analog.

Fig. 2. Protect the base of the abutment with block out resin & light-cure.

Fig. 3. Air abrade the Titanium Abutment with 30-50 μm Alumina Powder @ 32 PSI.

Fig. 4. Clean abutment with KATANA™ Cleaner (10’s Rubbing, Rinse & Dry).

KATANA™ Cleaner is a universal cleaner that is indicated to clean metal, zirconia & glass-based restorations. It is also an intra oral cleaner that may be used on dentin and enamel.

REFERENCE INDEX POINTS TO ENSURE ACCURATE SEATING

Fig. 1. Mark Index position on implant analog.

Fig. 2. Mark index position (notch) on crown.

TREATMENT OF RESTORATION & BONDING TO THE ABUTMENT

Fig. 1. If Lithium Disilicate, HF acid etch Internal Surfaces, with 5% HF etch for 20’seconds then rinse & dry. If Zirconia, air abrade, at 14-58 PSI.

Fig. 2. Inject PANAVIA™ SA Cement Universal (White Shade) onto treated & cleaned abutment.

Fig. 3. Align index points & seat crown onto abutment.

Fig. 4. Place crown & implant into clamps & lightly tighten.

Fig. 5. Tack-Cure Clean-Up: Light-Cure excess cement for 2-5 seconds (time depends on light output & distance held).

Fig. 6. Remove excess cement & block-out resin with an explorer. PANAVIA™ SA Cement Universal has extremely easy clean-up.

Fig. 7. Wipe off remaining resin with gauze.

Fig. 8. Remove index mark with alcohol & gauze.

Fig. 9. Clean & polish restoration prior to seating. Surfaces coming in contact with soft-tissue should be polished.

Dentist:

GREG CAMPBELL

Dentist Greg Campbell DDS, Long Beach, CA USA

Greg Campbell, DDS is recognized internationally as an expert on integrating CAD/CAM dentistry into offices and is frequently sought out by industry leaders to lecture about Digital Dentistry. Dr. Campbell has a great understanding of Digital Technology and trains other dentists how to use this technology and is a certified Advanced CEREC Trainer. He is a former Beta tester for Sirona Dental and has authored two books on CAD/CAM dentistry. Dr. Campbell has created multiple polishing kits used for ceramics and has been trained on advanced adhesion materials, research & techniques and utilizing them clinically for over 8 years. Dr Campbell was an Alpha and Beta Tester for KATANA™ STML.

Dr. Campbell graduated from the University of Southern California School of Dentistry and completed advanced training in Cosmetic Dentistry at UCLA and maintains a private practice in Long Beach California.