Dental Tribune Asia Pacific Edition

Dental TribuneAsia Pacific Edition | 12/201514 TRENDS&APPLICATIONS Anterior crowns come in many differ- ent variations,from purely functional to highly aesthetic,depending on the requirements and means of the pa- tient,theskillofthedentaltechnician, availability of materials,and prepara- tion and cementation procedures used. Many anterior crowns consid- ered to be aesthetic in the past no longer meet the demands of today’s patients.The example detailed in this articleisacaseinpoint. When she presented to our prac- tice, the 20-year-old high school graduate wished to have the crowns on her two central incisors replaced (Fig. 1). At the age of 14, she had sus- tainedanteriortoothtraumathatap- parently damaged the mesio-incisal partoftheincisaledgesofbothteeth. Thedentistshehadconsultedatthat time restored her teeth with por- celain-fused-to-metal (PFM) crowns. Even though the extent of the trauma can no longer be assessed, today’s alternative—in light of the patient’s young age in particular— would most probably have been a directcompositerestoration. Figure 2 shows the two central in- cisors in detail from the labial aspect and Figure 3 shows an incisal view. Thecrownsdidnotexhibitanyfunc- tional defects. As a result, the main treatment aim was to improve the aesthetic appearance of the anterior teethasrequested.Subsequently,the patientwasinformedaboutthetreat- ment procedure, in particular about any possible additional preparation requiringtheremovaloftoothstruc- ture,aswellasthecostinvolved. The treatment was begun at a sep- arate appointment. The restorations were fabricated by the dental lab- oratory of Hildegard Hofmann (Mainz, Germany). Pressed all-ce- ramic IPS e.max lithium disilicate (Ivoclar Vivadent) crowns were se- lected for this case, since they are the firstchoiceforthistypeofindication. Thishasbeenconfirmedbynumerous clinicalstudies,includingtherecently publishedGermanS3ClinicalPractice Guidelineonceramicrestorations. The teeth were anaesthetised at the placement appointment. The crownswereremovedandthebond- ing surfaces were carefully cleaned with ultrasound and a fluoride-free cleaning paste. Since the new Vario- link Esthetic DC (Ivoclar Vivadent) had been chosen as the luting ma- terial, the crowns were tried in with the corresponding try-in pastes. An immediate match to the adjacent and the mandibular anterior teeth wasachievedwiththeNeutralshade. Noadjustmentswerenecessarywith regard to a lighter (Light) or darker (Warm) shade of the luting com- posite. We attributed this excellent match to the dental technician hav- ing selected the shade at the chair- side. The extra expense of this step far outweighs the inconvenience of having to make numerous adjust- ments or new restorations because ofashademismatch. Conditioning of the crown Saliva and residue of the try-in paste were removed (Ivoclean, Ivoclar Vivadent) from the crowns before they were conditioned. It is advisable to fabricate a “handle” to allow the inner crown surfaces to be conditionedwithouthavingtotouch the crown with the fingers. In this case, the crowns were attached to a brushholderwithalight-curingpro- visional composite. This handle also allowedthecrownstobeplacedwith ease during the luting procedure. As an alternative, an OptraStick (Ivoclar Vivadent) could have been used. Hy- drofluoricacidetchingofglass-based ceramics and subsequent silanisa- tionhasbeenanacceptedcondition- ing method for decades. The newest studies confirm its effectiveness. It even generates a strong bond on state-of-the-art ceramic materials suchashybridceramics.Anacidcon- centration of 5 % has been estab- lished,whichrepresentsareasonable compromise according to the latest research. The new Monobond Etch & Prime (Ivoclar Vivadent), which was intro- ducedatthe2015InternationalDental Show,isaconditioningmaterialbased on ammonium polyfluoride. The product is actively scrubbed on the bondingsurface(Fig.4)for20seconds, thereby removing any contamina- tion with saliva or silicone. After an- other 40 seconds (Fig. 5), the ammo- nium polyfluoride reacts with the ceramicsurfaceandproducesarough etching pattern. Even though this pattern is not as pronounced as that of conventional 20 seconds etching with 5 % hydrofluoric acid, the bond- ing results achieved in both cases are comparable. The enlarged surface created in this way helps to activate theceramicbondingsurface. The restoration is subsequently rinsed to remove the ammonium polyfluorideanditsreactionproducts. The reaction of the silane and the ac- tivated glass-ceramic then begins. A thin layer of chemically bonded silaneremainsontheceramicafterits distributionwithblownair.Thisprod- uct, therefore, combines the steps of hydrofluoric acid etching and silani- sation and it even appears to render cleaning with Ivoclean superfluous. The currently available in vitro data justifies using this new product with due care to replace the hydrofluoric acid etching and silanising method. Even though it has not been shown to improve the bonding values in re- lation to the established references, no negative effects on the adhesive bond have been found to date either. Moreover,sincetheadhesivebondto glass-ceramicsisconsideredtobethe most unproblematic interface in the bonding process of indirect restora- tions, no clinical irregularities are to beexpected. In the case presented, the crowns could even have been placed by con- ventionalorself-adhesivemeans.The loss of retention would have been as unlikelyastheoccurrenceofaceramic fracture due to inadequate adhesive support.Figure6showsoneofthetwo crownsafterMonobondEtch&Prime had been rinsed off and the surface driedwithblownair. Cementation of the crowns Variolink Esthetic DC was used for the adhesive cementation of the Aninnovativeadhesivelutingprotocol All-ceramic anterior crowns (IPS e.max Press lithium disilicate) placed with Monobond Etch & Prime By Prof.Claus-Peter Ernst, Germany 1 2 3 4 5 6 Fig.1: Unattractive,old porcelain-fused-to-metal restorations on teeth #11 and 21 in a 20-year-old patient.—Fig.2: Close-up photograph of the functionally intact anterior crowns showing unattractive PFM work due to the metal framework showing through.—Fig.3: Incisal view of the existing crowns.—Fig.4:The self-conditioning ceramic primerMonobondEtch&Primeisscrubbedinfor20seconds.—Fig.5:AdditionalreactiontimeofMonobondEtch&Primeof40seconds.—Fig.6:ApicalviewoftheIPSe.max PresslithiumdisilicatecrownafterMonobondEtch&Primehadbeenrinsedoff.—Fig.7:Conditioningofthepreparedteethfortheadhesivecementationoftherestorations under cotton roll isolation. Retraction cords were placed in the sulcus to prevent any contamination with sulcular ﬂuids.—Fig. 8: Incisal view of the prepared teeth.— Fig.9: Application of Adhese Universal adhesive with the pen applicator. 10 11 12 13 Fig. 10: Light polymerisation of the adhesive after careful distribution with blown air.—Fig. 11: The polymerised adhesive layer on teeth#11and21.—Fig.12:TheIPSe.maxPresslithiumdisilicatecrowns,cementedwithVariolinkEstheticDC,at thefollow-up examination after four weeks.—Fig.13: Incisal view of the crowns at the follow-up examination after four weeks. 987 123 456 1011 1213

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