Use the next wider Densah® Bur (3.0) and advance it into the previously created osteotomy with modulating pressure and a pumping motion. When feeling the haptic feedback of the bur reaching the dense sinus floor, modulate pressure with a pumping motion to advance past the sinus floor in 1 mm increments, up to 3 mm. Maximum bur advancement past the sinus floor, at any stage, must not exceed 3 mm. Bone will be pushed toward the apical end and will begin to gently lift the membrane and autograft compacted bone up to 3 mm. Confirm the bur vertical position with a radiograph.
Densah Bur (4.0), (5.0) OD mode up to 3 mm past the sinus floor. Use the sequential wider Densah® Burs in Densifying Mode (Counterclockwise drill speed 800-1500 rpm) with copious irrigation with pumping motion to achieve additional width with maximum membrane lift of 3 mm (in 1 mm increments) to reach final desired width for implant placement. Densah® Burs must not advance more than 3 mm past the sinus floor at all times regardless of the Densah® Bur diameter.
After achieving the final planned osteotomy diameter, fill the osteotomy with a well hydrated, mainly cancellous, allograft. Use the last Densah® Bur used in step 4 in Densifying Mode (Counterclockwise) with low speed 150-200 rpm with no irrigation to propel the allograft into the sinus. The Densah® Bur must only facilitate the allograft material compaction to further lift the sinus membrane, and not to advance beyond the sinus floor more than 2-3 mm. Repeat the graft propelling step to facilitate additional membrane lift as needed according to implant length.
The anterior maxillary wall is slightly more concave. The pathway is totally intra-maxillary with an intra/extra-sinus approach. A tunnel osteotomy is created through the alveolar crest, into the sinus internal lateral wall, to slightly come out through that lateral wall and then re-enter again as a second tunnel osteotomy into the sinus to come out through the body of the zygoma.
The objective of this observational cohort study was, therefore, to evaluate longitudinal changes in bone height, apical bone gain, and marginal bone loss around implants placed combined with graft-free ISFE by evaluation of radiographs. Predictive factors for apical bone gain and marginal bone loss were also determined. Based on preliminary research [14,15,16] it was hypothesized that bone gain at the apical aspects of implants can be expected after internal sinus-floor elevation without graft after the healing period as well as in the long-term.
Of 225 tissue-level implants initially placed in combination with simultaneous internal sinus-floor elevation without graft, 217 implants were considered for the radiographic analysis. The eight excluded implants could not be considered for statistical analyses (no series measurement of radiographic changes in bone height possible) due to early failures (incidence of failure, absence of bony healing: 3.6%).
As far as the authors are aware, this study delivers the first evaluation of apical bone gain and marginal bone loss of implants placed in combination with transcrestal / internal sinus-floor elevation without graft in the long-term. However, it should be kept in mind that planning of implant surgery and evaluation of bone heights were based on two-dimensional radiographs. A 3D evaluation (e.g. cone-beam computer tomography, CBCT) would have been yielded advanced information on the surgical sites including bone characteristics and volumetric measurements. Nonetheless, three things regarding this issue should be considered: first, in clinical routine a CBCT is not done in each patient case, second, CBCT comes along with a substantially higher exposure dose which is hard to justify to the patients on a regular basis, especially in a long-term study. Last, the radiographs in this study were taken in parallel technique based on a reference (metal pins in the surgical splint) was performed in the radiograph viewing software which offered length correction. To this end, high inter-rater reliability of linear measurements was confirmed by repeated measurements of 40 radiographs by two independent investigators.
Three different methods for indirect sinus lifting, bone added osteotome sinus floor elevation (BAOSFE), sinus floor elevation with an inflatable balloon, and crestal approach system (CAS kit) from OSSTEM, were assessed for their ability to lift the sinus without causing laceration of the Schneiderian membrane. The study was performed on 18 freshly slaughtered sheep heads (36 sinus lifts were done, 12 for each method). CBCT images of the heads were taken to assess the best location for the sinus lift. Then, the heads were bisected and the membrane was exposed from the medial aspect. After that, each method was performed. The intended elevation height was 7 mm. If the 7 mm were not reached, the maximum height of elevation was measured.
This approach starts like BAOSFE. The osteotomy is enlarged to 5.0 mm before the balloon (Zimmer Sinus Lift Balloon, Zimmer Dental Inc., California, USA) is inserted (Fig. 3). The sinus floor was broken with the 5 mm osteotome after the addition of bone. The sleeve of the balloon was inserted 1 mm beyond the sinus floor. The saline was injected slowly from the syringe into the balloon, so the balloon would inflate progressively (Fig. 4). The balloon was deflated, and the desired elevation was checked if the elevation was not reached. The balloon was inserted again, and the process is repeated until the desired 7 mm are reached. One cubic centimeter of saline is expected to lift the membrane for 6 mm .
The CAS kit consists of a set of safe end drills, metal stoppers, a depth gauge, a hydraulic lifter, bone graft carrier, condenser, and a bone spreader (Fig. 5). The procedure started with a 2-mm twist drill. The drills were used to enlarge the osteotomy and are stopped 1 mm short of the sinus floor. The sinus floor was broken with the 3.6 mm bur without going through the floor; a depth gauge was used to check the membrane integrity and to slightly lift the membrane. Then, the hydraulic lifter was inserted and stabilized (Fig. 6) and the saline solution is injected. 0.30 mL can elevate the membrane up to 3 mm . The saline is drown out then injected again until the desired elevation is reached.
The osteotome technique originally described by Tatum 1994 has been shown microscopically to elevate the sinus floor for 5 mm without causing perforations . Thus, this technique should not be used when the intended elevation height is more than 5 mm . Therefore, a need for transalveolar approach that can elevate the membrane safely and for elevation heights greater than 5 mm has risen, Tatum described a modified approach to his osteotome technique in which bone particles are pushed in the sinus. The addition of bone will prevent direct contact between the instruments and the membrane . Recently, many methods for SFE have been described as an alternative for the osteotome technique. Most of this techniques fall under two categories: using an inflatable device such as a balloon or using hydraulic pressure, both of which have been shown to reduce the rate of membrane perforation [6, 7, 13, 21, 22]. Soltan and Smiler described the use of the balloon and concluded that it is a highly successful and easy to perform procedure . Recently, many systems have been developed which rely on hydraulic pressure to lift the sinus mucosa including the Jeder-System (Jeder GmbH, Vienna, Austria) which consists of a drill with a chamber which is filled with saline solution. After the initial drilling is done, the drill is connected to a pump that produces high hydraulic pressure; the pressure is used to break the sinus floor and to lift the membrane . Also, OSSTEM implants introduced the CAS kit as a method for preparing the osteotomy and elevating the membrane through hydraulic pressure.
Our study compared between three techniques for SFE for elevation heights of 7 mm. The 7 mm elevation height was chosen as a previous study by Stelzle et al. 2011 showed that BAOSFE caused perforations in the mucosa in all samples for perforation heights of 10 mm . Therefore, we tried to set a threshold that might be achieved with internal sinus lifting techniques and be feasible in clinical practice. Perforations were checked using the three different methods: the mesial window, using a depth gauge, and the injection of saline solution through the osteotomy, which allowed for accurate recording of perforations.
Direct sinus lift with simultaneous implant placement with use of autogenous bone graft (a) In-fracturing and lifting of lateral window of right maxillary sinus, (b) Autogenous bone harvested from donor site being placed in newly created space, (c) Bone packed in the window, (d) Sinus floor augmented and implant placed
Line diagrams illustrating direct sinus lift with simultaneous implant placement, (a) Atrophic posterior maxilla with residual bone height between sinus floor and alveolar crest inadequate for placement of dental implant, (b) Lateral wall of sinus in-fractured and membrane is elevated, (c) Grafted bone is densely packed in space created after lifting the membrane, (d) Augmented maxillary sinus with implant placed
Pre- and postoperative orthopantomograph (OPG) in a case treated with indirect sinus lift and bone graft for implant placement, (a) Insufficient residual bone, (b) After prosthetic rehabilitation following indirect sinus lift, bone grafting, and implant placement
On comparing ISAT (n = 108) and DSAT (n = 89), the gender and age distribution in study population was not significant. The placement of graft was significant between ISAT and DSAT [Table 2]. On comparing the mean age between ISAT and DSAT, difference was not statistically significant (P = 0.271). The mean period of edentulous also did not appear to influence (P = 0.87). The difference in alveolar width was significant between ISAT and DSAT cases (P = 0.01). The mean length and diameter of implant used was also statistically significant (P = 0.000 and 0.007, respectively). The gain in bone height expressed as percentage of original RAB height at end of 1 year for ISAT was 99.52% while for DSAT it was 177.22%. This difference was statistically significant. [Table 3]. In the indirect sinus lift (ISL) method, when graft was used, the mean gain percentage was 115.52 ± 6.04%; while when no grafts were used, the gain in height was 95.2 ± 11.36%. 2b1af7f3a8