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16 — issue 2016 Advanced Implant Esthetics Article depth of the abutment–crown joint and the amount of excess cement on the sur- face of the abutment. This is an argument in favor of the use of NobelProcera indi- vidualabutments.However,theseindivid- ualized abutments often have significant undercut areas, which are recognized risk factors for the retention of intrasulcular cement.30 On small-diameter implants, the reduced dimensions ofthe abutments diminish the friction surface of the im- plant-supported crown and the creation of two small mechanical retentions in the incisal zone of the abutment reduces any loosening (Fig. 8). Maximize retention of small-diameter abutments. — Crown Where edentulous gaps were narrow, 3 mm Nobel Active implants were placed and only titanium abutments, standard or NobelProcera, were used. Two types of crownarepossible:metal–ceramiccrowns or all-ceramic crowns. — IPS e.max (Ivoclar Vivadent) If the abutment is titanium, using an all- ceramic system can present restrictions related to the bucco-palatal thickness of thelateralincisor.Whenthetoothisthick, this prosthetic solution makes it possible to achieve an acceptable esthetic out- come (Figs. 9a–d). Conversely, when the thickness is less, this type of all-ceramic crown can sometimes result in more dis- advantages than advantages from an es- thetic perspective. In such a case, for the coping in lithium disilicate, one has to use high-opacity ceramic of significant thick- ness in order to hide the titanium abut- ment as much as possible. This has the ef- fect of reducing the thickness of the cosmetic ceramic and thus reduces its ability to mimic the appearance of adja- cent teeth (Figs. 10a–d). — Metal–ceramic crowns Conversely, using metal-fused-to-porce- lain crowns on narrow and small teeth makes it possible to reduce the thickness of the copings made from precious alloys or palladium (to 0.3 mm or 0.4 mm) and in this way to increase stratification (Figs. 11a–c & Figs. 12a–d). However, the transgingival area remains the weak point inthistypeofrestorationwithariskofthe greycolorofthetitaniumabutmentshow- ingthrough whenthe periimplant mucosa is thin (see Fig. 33 in Russe & Limbour).31 Do not hesitate to use metal– ceramic crowns for small lateral incisors. — Monoblock screwed zirconia crown The use of hexagonal implants measuring 3.3 mm externallyorwith an internal con- nection measuring 3.5 mm makes it pos- sible to use zirconia abutments. In these circumstances, two options are possible, depending on the emergence position of the abutment screw: either a two-stage solutionofazirconiaabutmentsupporting a cemented ceramic crown (Figs. 13a–d) oramonoblockcrownscreweddirectlyon to the implant (Figs. 14a & b). In these sit- uations, the semitranslucent character of the material makes it possible to ensure optical continuityin boththe coronal sec- tion and the gingival section, resulting in better esthetic integration. — Cement Inordertoreducethevisibilityoftitanium showing through when a glass-ceramic crown is used, an opaque white cement should be employed accordingto Dede et al.18 This involves a polycarboxylate ce- ment (Poly-F, DENTSPLY DeTrey), se- lected initially for its theoretical ability to potentially allow detachment of the crown.Recentstudieshavedemonstrated that polycarboxylate has greater tensile strength than does zinc oxyphosphate or glassionomer.32 Atthetimeofcementing, the cement-coated crown is placed on a replica abutment; any excess is removed before placing the crown in the mouth.33 This clinical technique has been proven beneficialforbothitsqualitiesofretention and reducing excess cement.34 If standard abutments are used, then the crown limit can be considerably sub- gingival and it is then vital to use a mini- mum amount of cement and to remove any excess immediately.The washable na- ture of polycarboxylate cement immedi- atelyafterplacementcanbeanadvantage for its removal. — Esthetic outcome When the esthetic outcome is evaluated according to the criteria specified by Fürhauser et al.35 and when particular at- tention is paidtothe scoreforthe papillae and the gingival level, use of small-diam- eter implants to replace lateral maxillary Figs. 7a–c Resin transfer coping on a standard abutment (a). Transfer coping on an abutment that has never been removed (b). Transfer and analog repositioned in a polyether impression (Impregum, 3M ESPE; Rim-Lock dental impression tray, Zhermack; c). Fig. 8 Creation of cement retentions on a titanium abutment. Figs.7a & b Fig.7c Fig.8 Article_Russe_00-00.qxp_Layout 1 02.03.16 20:52 Seite 5 Article_Russe_00-00.qxp_Layout 102.03.1620:52 Seite 5