IM0210

were lost (23/1163; 2.0%), fourteen (60.1%) before loadingandnine(39.1%)afterloading.Onlyoneau- thor (Pi-Urgell et al.)2 presented the fracture of one of the zygomatic implants, which is probably a rare complication.Farzardetal.26 observedthatthemar- ginalbonelossinthezygomaticimplantswouldrep- resent a decrease in the stability of the implant over time,withprogressivelylowerImplantStabilityQuo- cient (ISQ) values (<50). This confirms that the main anchorage site of the zygomatic implants is the zy- gomatic bone, especially in the long term, since and theresorptionoftheresidualcrestalbonecanoccur. This unfavourable biomechanical situation could eventuallyleadtoanincreaseintheincidenceofim- plant fractures in future studies with long follow- ups. Although some authors comment on the level of satisfaction or quality of life in their reports6, 19, 28 , only Al-Nawas et al.24 introduce success criteria in theirresults.Theseauthorsanalysedtheperiimplant soft tissue’s health (gingival bleeding index, probing depth, microbiological testing, etc.) concluding that only eleven of the 20 zygomatic implants (55%) would be considered successful, while the survival rate was 95%. A precise surgical evaluation of the patient is mandatory in this complex technique, since serious complications might occur, especially due to the length of the implant and to the presence of impor- tant anatomical structures (orbit, infratemporal fossa, etc) in the zygomatic anchorage area. More- over,ourliteraturereviewshowedalowrateofcom- plications (9.5%), all being minor problems. Sinus pathology seems to be the most frequent complica- tion, although other conditions have been reported. According to Maló et al.14 the sinus pathology is re- latedtopreviousepisodesofsinusitisortotheintra- operative perforation of the Schneiderian mem- brane.Onthecontrary,otherauthorslikeBrånemark et al.1 mention in their article that no special effort was made to keep the sinus membrane intact. As a matter of fact, Peñarrocha et al.12 , perforated all the sinus membranes in their study with 40 zygomatic implants and reported only two cases of sinusitis. This is an interesting aspect to discuss in future re- search,sincetheavailabledataisclearlyinsufficient. When sinus pathology is diagnosed long after im- plantplacement,itisdifficulttoidentifythecauseof the sinusitis. In fact, only one of the papers men- tionedtheremovalofthreeimplantsbecausethepa- tients had frequent episodes of sinus infections. On the other hand, all the other authors decided to maintain the implants and the sinus pathologies were favourably managed with antibiotics or with antibioticsincombinationwithantrostomysurgery. Themaxillarysinuscouldalsobeaffectedifthereisa substantial marginal bone loss, as described by Al- Nawas et al.24 In these cases, the infection will reach themaxillarysinusthroughtheperiimplantpockets. Thelackofstability,aestheticsand/orfunctionof theprosthesisandthedeficienthygieneoftheabut- ment areas are also important complications. Prob- ably,theseareoftenrelatedtothepalatalemergence ofthezygomaticimplants.Nowadays,thislimitation has been solved with the extramaxillary implants procedure.14,21 Nevertheless,thelong-termexposure ofthetitaniumthreadstothecheek’ssofttissuehas to be evaluated carefully. _Conclusions Basedonthecurrentliteraturereview,zygomatic implantsshowexcellentsurvivalrates(>90%)anda low incidence of complications, so this should be considered a valid and safe treatment option when dealing with patients with advanced maxillary atro- phy. Nevertheless, the authors would like to express their concern with the scarce amount of published studies (most of them of retrospective nature), with thelowlevelofscientificevidenceavailable,andwith the lack of studies with long follow-up periods. The introduction of success criteria also based on peri- odontal parameters should be considered in future research._ Editorial note: A complete list of references is avail- ablefromthepublisher. implants2_2010 Dr Rui Figueiredo DDS Associate professor of the Oral Surgery and Im- plantology Department,Barcelona Institut de Recerca Biomèdica de Bellvitge (IDIBELL) Facultat d’Odontologia Universitat de Barcelona Campus de Bellvitge Pavelló de Govern 2a planta,Despatx 2.9 08907 – L’Hospitalet de Llobregat,Spain Phone:+34 93 402 42 74 E-mail:ruipfigueiredo@hotmail.com 1 MD,DDS.,Professor of the Master degree pro- gram of Oral Surgery and Implantology,Barcelona 2 DDS.Fellow,Master degree program of Oral Sur- gery and Implantology,Barcelona 3 MD,DDS,PhD.Chairman,Oral Surgery and Im- plantology Department,and Director,Master de- gree Program of Oral Surgery and Implantology, Barcelona. _contact implants