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Volume 2 | Issue 1/2016 41 Journal of Oral Science & Rehabilitation Tra n s c res ta l s in us f lo o r e le vati o n wi th a so ni c i nstru me nt Introduction After tooth extraction, shrinkage of the alveolar process is expected that may reach 50% of the original horizontal width.1 In the posterior max- illa, the resorption of the radicular portion of the sockets that may protrude into the sinus could yield a further bone volume reduction due to sinus pneumatization. In the molar area, the re- sorptionisgreaterthaninthepremolararea,ow- ingtothelargervolumeoftheextractionsockets that requires more time to be filled by newly formed bone, thus allowing the time for sinus pneumatization.2 In periodontally compromised patients, a large sinus pneumatization, together with the concomitant alveolar crestal resorption, mayre- sult in an inadequate bone height, which may hinder the primary stability of implants in the edentulousposteriormaxilla.3–5 The maxillarysinus floorelevationtechnique with a lateral approach has been well described in literature.6 This surgical approach was based on a previously unpublished technique pre- sented by Tatum at the Alabama Birmingham meeting in 1976. The safety and reliability of the technique have received large consensus by cli- niciansandresearchers.Severalmodificationsof the sinus floor elevation technique have been subsequently proposed for the surgical proce- dures and grafting materials used. Many of the sinus floor elevation techniques include the use of grafting materials to fill the subantral space, aimingtomaintainthevolumecreated. However,clinicalstudiesonsinusflooreleva- tion performed concomitantly with implant placementhaveshownthattheestablishmentof an isolated space betweenthe bonewallsurface and the sinus mucosa, resulted in spontaneous formation of new bone, even without the use of grafting materials.4–7 Moreover, the integrity of the sinus membrane is known to be a prerequi- site for success of the technique because it pre- vents the shift of the grafted material inside the sinus cavity; shifting of the material may favor acute or chronic infective complications and possibly compromise bone regeneration.8 An- other technique frequently adopted for sinus floor elevation requires a crestal access,9 first carriedoutwiththeuseofosteotomesandautol- ogous bone as filler material.10 The crestal ap- proach may reduce the perforation of the sinus membrane (4.7%)11 compared with the lateral approach(44%).12 Several modifications of the crestal approach havebeensubsequentlyproposed,aimingtoele- vate the sinus floor while maintaining the in- tegrity of the Schneiderian membrane. For this purpose, a variety of osteotomes, used with or without bone fillers,13, 14 or drills designed to avoidmembraneperforation,15 ortheuseofspe- cific devices16, 17 or ultrasonic instruments18, 19 have been proposed. With the use of os- teotomes,anelevationofthesinusmembraneof up to 10 mm in total may be obtained without causing tearing.20 Another modification of the transcrestal approach was proposed21–23 based on the principle of the edentulous ridge expan- sion technique.24 This approach includes the use of a blade to perform the osteotomies and, sub- sequently,theuseofbluntosteotomes. The preservation of sinus walls appears to have an important role in bone formation in the sinus floor elevation procedure. In fact, in an ex- periment in monkeys onthe earlyhealing at ele- vated floor sinuses,25, 26 it was shown that new bone only originated from the bone walls and septa of the sinus. In that study, no evidence of bone formation was observed from the sinus mucosa, even though other studies have demonstratedthatthe Schneiderian membrane has the potential to produce bone.27–30 A mini- mum height of 4–6 mm of the sinus floor has been suggested to guarantee the stabilityofthe implant and, consequently, the success of the crestal access for sinus elevation.10, 31–35 When the primary stability of an implant cannot be guaranteed, a two-stage approach may be fol- lowed and implant placement would have to be postponedforseveralmonths,dependingonthe quality of the filler material used.31–35 A two- stage procedure has also been described for sinusfloorelevationthroughacrestalaccessus- ing blades, osteotomes and a mallet.21 The aim ofthepresentstudyistodescribeaminimallyin- vasive two-stage technique for sinus floor ele- vation through a crestal access, using in both stages a trapdoor prepared with the Sono- surgerysystem. Materials&methods The case of a patient who required oral rehabili- tationbymeansofimplantsintheposteriormax- illary area and presented with a widely pneuma- tized sinus was chosen to present the step-by- step procedure of the technique. The height of Volume 2 | Issue 1/201641