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ePaper created 2016-09-20, 16:58:27 | version 1.38.0
Journal of Oral Science & Rehabilitation 58 Volume 2 | Issue 3/2016 I m m e d i a t e l o a d i n g u s i n g g u i d e d s u r g e r y Twelvepatientswith68implantsshowedaslight amount ofplaque aroundthe implant–abutment interface; thus, the overall plaque score was 36.0% and 44.4% at implant and patient level, respectively. The gingival index was reported as 90.5% normal gingiva, 7.9% with mild inflam- mation and 1.6% with moderate inflammation. Discussion This studyretrospectivelyevaluatedthe success andsurvivalratesofvariable-threadtapered-body implants placed into post-extraction or healed sitesinthemaxillausingcomputer-assistedtem- plate-guided surgery in combination with a spe- cially designed two-piece radiographic stent.21 The main limitations of this study are its retrospective nature,which mayhave limitedthe data collection, and the analysis of possible variables (soft-tissue thickness, time of place- ment or loading) that may have influenced the bone resorption.Anotherlimitation isthe limited numberofparticipants. However,this investiga- tion maybe considered as a pilot studyforfuture multicenter randomized controlled trials with samplesizecalculationandmultivariateanalysis. Implants placed into post-extraction sockets showed lower marginal bone remodeling than implants placed into healed sites did; thus, the null hypothesis that there is no difference bet- ween the two protocols in terms of hard-tissue response has to be rejected. In the present study, one out of 160 implants failed over a period of five years, accounting for an overall implant CSR of 99.4%. The major clinical conclusion of this retrospective study is that immediate post-extraction placement of implants and immediate provisionalization may be considered an effective and reliabletreatment option for patients who would prefer to have a shortened overall treatment time and to be re- habilitatedimmediatelywiththeaidofcomputer- assisted template-guided surgery. Proper patient selection and well-trained operators are necessary to minimize the risk of implant failure. Immediate implant placement and provisionalization in both post-extraction sockets and healed sites are technically deman- ding procedures, and the surgical and prosthetic skills required are superiortothose necessaryfor conventional implant treatment. To the best of our knowledge at the time of writingthisarticle,therewerenootherpublished studiesthatevaluatedtheuseofavariable-thread tapered-body implant with internal conical connection, in-built platform shifting and a mod- erately rough oxidized surface in combination with computer-assisted template-guided sur- gery to treat failing dentition in the maxilla. For this reason, it is difficult to evaluate how the presentresultsfitwithothercomparablestudies. However, there is a randomized controlled trial that investigated the same implant design that may provide some comparable data.25 The marginal bone remodeling reported in thepresentstudy,measuredfromimplantplace- ment until the last follow-up examination, was -0.58±0.98mm.Thisvalueisslightlylowerthan the data reported in the literature for two-piece implants, for which after the initial bone loss during the first year post-placement, about 0.1–0.2 mm ofcrestalbone losswasfound atthe annualfollow-up.26,27 Pozzietal.recentlypublish- ed three-year results of a randomized controlled trial, reporting a marginal bone remodeling of 0.83 ± 0.27 mm around NobelActive implants placed into healed sites in the posterior man- dible.25 One reason for these differences may be that surgeons operating freehand tend to ele- vate wider flaps to better visualize the area in which the implants are to be placed. With dedi- catedtemplate-guidedimplantplacement,wider flaps were in many cases considered unneces- sary, since the surgeons were able to rely on the surgicaltemplate.11 Anotherexplanationthatmay account for the differences in the observed MBL changes is that, in some of the aforementioned studies, all of the implants were placed into healed sites.11, 25 In the present study, statistical analysis showed a statistically significant differ- ence (P = 0.026) in mean marginal bone remo- deling at the last follow-up between im- plants placed into healed sites (-0.67 ± 0.97 mm) and those placed into post-extraction sites (0.42 ± 0.99 mm). These findings are in accor- dance with a recent systematic review and me- ta-analysis onthe alterations ofthe bone dimen- sion after immediate implant placement into extraction sockets.28 In the present study, the diagnostic protocol included the calibration procedure of the digital workflow for each patient, according to the manufacturer’s instructions. Scanning physical objects like the radiographic guide requires an optimized workflow, because the data are con- verted into 3-D models, which are used not only fordiagnostic purposes but alsoforphysicalpro-