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ePaper created 2015-03-10, 11:16:47 | version 1.33.01
issue 1/2015 — 17Implant Dentistry Article Hard tissue augmentation Where a bone reconstruction is indicated, this should take into account one of the key factors for the overall cosmetic out- come: restoration of papillary support in ordertoavoidanyunsightlyblacktriangles between the lateral incisor and the adja- cent teeth or any concave area above the implant crown that would create an ugly shadow. The cortical graft, taken from the chin orthe external oblique, should be formed in such a wayas to provide support forthe gingival papillae (Fig. 11). Gaps under and around the graft should be filled with cor- ticalboneparticles,crushedfromthechin block or lateral mandibular area using a bone mill. The attachment must be reliable.This is doneusingtwo1.6mmdiameterosteosyn- thesis screws (Fig. 12). Autografts take about 5 months to heal. Ideally, the im- plant should be inserted between 4.5 and 5.5 months after the graft (Fig. 13). Fully reconstruct papillary support. Insertion of implant Choice of implant The mesio-distal dimension ofthe gap will determine the choice of the implant. When this is close to or less than the av- erage size of 6.5mm, the bone and papil- laryvolume around standard size implants will be limited. According to Hasan et al.10 and Bourauel et al.,11 the disadvantage of small diameterimplants isthattheytrans- mit higher stresses to the crestal bone thandostandardimplants.Whenreplacing a lateral maxillary incisor, it is possible to arrange both the anterior guidance and the diduction in such a way as to make them largely affect the natural teeth, in the absence of any significant malposi- tioning,andinthiswayreducethestresses applied to the implants. Under these con- ditions, small diameter implants have the advantage of increasing surrounding residualbonevolumeaswellasspaceavail- able for papillary healing. In a forthcoming study of 120 Nobel Active 3mm diameter implants, one of the conclusions confirmed the impor- tance of these small diameter implants as regards the additional height of the papillae, resulting in an improvement in the Fürhauser pink aesthetic score12 (Figs. 14, 15a and b). Favor small diameter implants. 3-D positioning As regards replacement of a lateral max- illary incisor, the tolerances for the loca- tion of the implant are very small because of the narrow width of the implant corri- dor.Tworecentmeta-analysis13, 14concern- ing the precision of surgical guides result- ingfrom3-Dimagery,evenifthesedonot apply specifically to the lateral incisor re- placement,hasfoundadeviationintheor- derofamillimetreatthepointtheimplant emergesand4to5degreesasregardsthe drilling axis. ForVan Assche et al.,14the av- erage imprecision at the apex of the im- plant is 1.24mm. Since these measurements are incom- patible with a 12 or 22 implant corridor, it is important to check the first drill hole(s) duringtheoperation,whetherthesurgery is guided or being carried out freehand. If the implant clinic does not have retroalveolar X-Ray equipment, portable generatorssuchastheAnyray2® (Vatech) are available on the market, which allow you to produce intraoperative images (Fig. 16). In this context the Precision Drill from the Nobel Biocare kits is particularlyhelp- ful. Its sharp point provides considerable Fig.12 Fig.15a Fig.15b Fig.16 Fig. 12 X-Ray result, compare with Fig. 6. Fig. 13 Clinical outcome 5 months after the graft. Compare with Fig. 11. Fig. 14 3mm diameter Nobel Active implant. Figs. 15a & b Papillary view (b) X-Ray view (a), 2 years after the insertion of the implant. Fig. 16 Mobile Anyray 2® (Vatech) X-Ray generator. Fig.14Fig.13