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today EAO Paris Sep. 30 & Oct. 1, 2016

science & practice 25th EAO Annual Scientific Meeting 13 n Having discussed in yesterday’s article, all of the preprosthetic stages for the replacement of a lat- eral maxillary incisor and having explained the surgical procedures required to im- prove the final es- thetic outcome, in this second part, we discuss the prosthetic stages. Ob- servation of clinical cases over a pe- riod of almost 15 years has made it possible to assess, over the different steps in the prosthetic chain, the im- pact of particular choices of compo- nents or clinical procedures on the final esthetic outcome of the gingi- val setting and the ceramic crown. As a result, for each clinical step, there are recommendations to help optimize and complete the surgical outcome and to ensure a long-last- ing result. In the last section, the esthetic outcome will be considered in rela- tion to its medium- and long-term evolution, compared with the initial results. The effects of continuous tooth eruption and an analysis of different risk factors lead the au- thors to make clinical recommenda- tions to minimize any negative ef- fects. Provisional prosthesis A provisional prosthesis can be fabricated at different stages of treatment: when the implant is placed to provide an immediate tem- porary solution, when the implant is uncovered, or once the soft tissues have healed. A temporary abutment can be utilized, but this will involve greater manipulation of the subgin- gival components (Figs. 1a & b). One abutment, one time The concept of the single abut- ment being seated early and defini- tively during im- plant treatment in order to preserve the attachment of soft tissues around the abutment is based on a publication many years ago by Abrahamsson et al.1 For these authors, the multiple connec- tions and disconnections of healing screws resulted in apicalization of the periimplant bone. This study is now considered to be biased be- cause of the cleaning of healing screws with alcohol (which destroys the attached fibroblasts); neverthe- less, it provided the basis for the one-abutment–one-time concept (OAOT) put forward by Maurice and Henry Salama at conferences from 2007. At present, the medical litera- ture is generally in favor of this con- cept, even though research results are mixed: – In dogs, the results of Iglhaut et al.2 showed a highly negative out- come of connection and discon- nection at four and six weeks, while in Alves et al.3 five such ma- nipulations between 6 and 14 weeks had no negative conse- quences. – In humans, several recent studies have concluded that there is a ver- tical advantage of 0.5 mm,4 hori- zontal advantage of 0.3 mm,5 ver- tical advantage of 0.2 mm6 and nonsignificant7 result for the OAOT protocol in different clinical situations. In their 2014 review of the liter- ature on factors influencing apicali- zation of periimplant tissue, Iglhaut et al.8 documented interest in the concept of the single abutment and proposed recording the position of the implant at the time of place- ment. Thus, there is some evidence suggesting that it is desirable to limit the number of manipulations of the subgingival elements as much as possible, even though the literature is not unanimous in this regard. The OAOT technique has a drawback pointed out by Piñeyro and Tucker:9 however: the in- creased risk of cement overflow where the abutment–crown limit is deeply buried. Different clinical strategies make it possible to apply the OAOT concept: – The fabrication, using 3-D imag- ing, of a surgical guide and a ma- chined abutment prepared dur- ing the preoperative stage makes immediate placement possible, but it is also more risky, since any error in the guide or any lack of precision in the placement could make the prepared abutment un- usable. – The same technique, starting with an impression at time of implant placement, is less risky, since the position of the implant has al- ready been finalized. Since these two techniques involve the collaboration of the lab- oratory, a simplified protocol was used for the majority of the 120 NobelActive implants (Nobel Bio- care; 3 mm) placed over the past three years: – Preoperative cone beam computed tomography imaging is used to determine whether a straight abutment or a 15° angulated abut- ment is the best choice for the specific clinical case. – Radiographic monitoring makes it possible to check on the place- ment axis in the mesiodistal plane, and the use of a parallelism guide when the 2 mm drill is be- ing used provides a check on the buccal–palatal plane. Once the implant is in place, an angulated prosthetic abutment is seated to optimize the rotational position of the implant, which is done to avoid, as far as possible, any ad- justment to the abutment by grinding (Figs. 2a–c). In order to assist with intra- operative fitting, the surgical kits contain sterile angled abutments, the incisal edges of which are slightly curved, which presents the rotational alignment of the implant better than a straight cylindrical abutment does (Fig. 3). An adjust- ment of a few degrees and a check of the occlusion make it possible to position the vestibular gingival edge perfectly and, most often, to use the abutment without any al- teration, which substantially sim- plifies the rest of the prosthetic chain. Keep manipulations of the abutment to a minimum In order to respect the principle of OAOT during the fitting of the pro- visional crown, a provisional resin coping is prepared on a straight or angled abutment, depending on the clinical requirement, along with a resin veneer created from a pros- thetic tooth (Figs. 4a–c). The resin coping is bonded in the mouth to the veneer using a minimal quantity of resin in order to avoid direct pollu- tion of the soft tissues by the cyto- toxic resin monomer (Figs. 5a–e). The use of a standard abutment and a provisional coping makes the fab- rication of temporary crowns very quick and simple while also respect- ing the principle of OAOT. Emergence profile When putting the provisional tooth in place, it is preferable to give it an initial emergence profile that is concave in order to allow healing of the papilla with the maximum space available. A convex profile or an overcontour encourages apicali- zation of the gingival margin, which is generally deleterious buccally (Figs. 6a–c). After stabilizing the soft-tissue margin, small amounts of resin placed mesially and distally with a brush on the temporary tooth allow some pressure to be placed on the papilla according to the cervical con- touring concept of Bichacho and Landsberg10 and, in this way, to optimize the filling of any gaps and the emergence profile. Buccally, the gingival level or the crown zenith can be moved by modifying the tem- porary tooth (Figs. 6d & e). In order Lateral maxillary incisor implant: Key issues for esthetic success Part 2: Prosthetic stages and long-term issues. By Dr Philippe Russe and Prof. Patrice Margossian, France. 5 Figs. 1a & b: Provisional abutment after modified roll flap (a). Temporary crown in place at the end of the surgical reopening (b). 5 Figs. 2a–c: Intraoperative placement of a 15° angled abutment (a). Precise rotational adjust- ment of the implant (b). Check of rotational adjustment in the axial plane (c). 5 Fig. 3: Surgical kit with 3.0, NP and RP angled abutments (NobelActive system). Fig. 1a Fig. 1b Fig. 2a Fig. 2b Fig. 2c Fig. 3 5 Figs. 4a–c: Temporary coping created with a brush (UNIFAST III, GC) and a veneer (a). Initial clinical situation with a 15° angled abutment in place (b). Temporary coping in place (c). 5 Fig. 5a: Bonding of the coping and veneer. Palatal view showing the small quantity of resin used. 5 Figs. 5b–d: Bonded veneer, then relined and finished. 5 Fig. 5e: Provisional crown after cementing. Fig. 5a Fig. 5b–d Fig. 4a Fig. 4b Fig. 4c Fig. 5e 5 Figs. 6a–e: Buccal compression (a). Creation of a concave profile on the provisional crown (b). Provisional clinical outcome: The shape of the incisal edge also plays a role in the esthetic re- sult (c). Resin applied with a brush to distalize the zenith (UNIFAST III; d). Emergence profile optimized by the provisional crown (e). 5 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 impres- sion tray, Zhermack; c). 5 Fig. 8: Creation of cement retentions on a titanium abutment. Fig. 6a Fig. 6b Fig. 6c Fig. 6d Fig. 6e Figs. 7a & b Fig. 7c Fig. 8