Dentistry and Medical Research

: 2020  |  Volume : 8  |  Issue : 1  |  Page : 4--9

Minimally Invasive Transalveolar Sinus Augmentation: An Answer to Sinus Conundrum

Jaibin George, Saumiya Gopal, Febel Huda, Niti Thomas 
 Cochin Implant Centre, Kalamassery, Ernakulam, Kerala, India

Correspondence Address:
Saumiya Gopal
JJ Dental Care, Near CUSAT Signal Junction, South Kalamasser, Ernakulam, Kerala


Dental implants have become the routine option for replacement of missing teeth, but it is challenging to place implants in the posterior maxilla due to inadequate bone dimensions and pneumatization of the maxillary sinus. Several techniques have been introduced over the years for sinus augmentation and bone grafting; both lateral and crestal approaches to sinus lift have been used with good results. In recent times, a minimally invasive technique has been used as a modification of crestal approach to sinus augmentation called minimally invasive technique sinus augmentation (MITSA). This method utilizes the calcium phosphosilicate putty for hydraulic sinus membrane elevation along with osseodensification drills. MITSA has simplified the sinus lift technique with predictable good results.

How to cite this article:
George J, Gopal S, Huda F, Thomas N. Minimally Invasive Transalveolar Sinus Augmentation: An Answer to Sinus Conundrum.Dent Med Res 2020;8:4-9

How to cite this URL:
George J, Gopal S, Huda F, Thomas N. Minimally Invasive Transalveolar Sinus Augmentation: An Answer to Sinus Conundrum. Dent Med Res [serial online] 2020 [cited 2021 Jan 23 ];8:4-9
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With the advancements in implant dentistry, the prosthetic treatment options have increased. However, due to reduced bone height, poor bone quality,[1],[2],[3],[4],[5] thinning or missing cortex,[6] and undercuts,[7] posterior regions in the maxillary arch remain a challenge to many. The anatomical structure that hinders in implant placement in the posterior maxillary region is the maxillary sinus, which exhibits an increased osteoclastic activity after tooth extraction, resulting in reduced bone height due to pneumatization of the maxillary sinus, which influences the length and location of implants.[8] Earlier many fixed restorations terminated at the second premolar region due to insufficient alveolar ridge height.[9] Other studies have also concluded that when shorter implants (<10 mm) are placed, they are less successful than longer implants.[4],[10],[11],[12],[13] Thus, techniques that elevate the sinus floor, which facilitate the placement of longer implants in the maxillary posterior region, have been popularized in recent years.

This literature review enumerates all the techniques used for sinus augmentation with emphasis on minimally invasive transalveolar sinus augmentation, which is an easy-to-perform technique, with greater advantage over previous methods.

Maxillary sinus floor elevation (SFE) was first described by Dr. Hilt Tatum at an Alabama implant conference in 1976.[5] This triggered a series of studies and trials to develop a procedure which is appropriate for implant placement. A literature review on this topic shows numerous techniques being tried, but before mastering the technique, the dentist should have a thorough knowledge of the anatomy, vascularity, and nerve supply of maxillary sinus, along with its variations.

 Classification for Treatment Approach

In 1987, Misch developed a classification for the treatment of edentulous posterior maxilla based on the amount of bone available below the antrum and the ridge width.[14]

SA1: It has an adequate vertical bone for implants, that is, 12 mm. No manipulation of sinus is requiredSA2: It has 0–2 mm less than the ideal height of bone and may require surgical correctionSA3: It has just 5–10 mm of bone below sinusSA4: It has <5 mm of bone below sinus. [Figure 1] illustrates the classification.[15]{Figure 1}

 Indications and Contraindications for Sinus Augmentation

The following are indications for sinus augmentation:[16]

No history of sinus pathosisInsufficient residual bone height (<10 mm of bone height)Severely atrophic maxillaPoor bone quality and quantity in the posterior maxilla.

Sinus augmentation is not indicated when the patient has history as follows:

Recent radiation therapy in maxillaUncontrolled systemic diseases such as diabetes mellitusAcute/chronic maxillary sinusitisHeavy smokerAlcohol abusePsychosisSevere allergic rhinitisTumor or large cyst in the maxillary sinusOroantral fistula.

 Different Techniques for Maxillary Sinus Augmentation

The two main techniques of SFE for dental implant placement are as follows: a two-stage technique with a lateral window approach, followed by implant placement after a healing period; and a one-stage technique using either a lateral or a transalveolar approach. The decision to use one- or two-stage techniques is based on the amount of residual bone available and the possibility of achieving primary stability for the inserted implants.

 Lateral Approach With Grafting Materials

Tatum[5] and Boyne and James[4] were the first authors to publish studies on elevation of the maxillary sinus floor in patients with large, pneumatized sinus cavities [Figure 2].[17] They described a two-stage procedure, where the maxillary sinus was grafted using autogenous particulate iliac bone in the first stage of surgery. After approximately 3 months, a second-stage surgery was performed in which blade implants were placed. Since then, numerous articles have been published regarding different grafting materials and modifications of this technique.{Figure 2}

The advantage of a single-stage procedure is decreased healing time due to one less surgery. However, the main disadvantage with the one-stage procedure is the possibility of being unable to stabilize implants in minimal bone heights, with the additional risk of implants falling inside the sinus. Therefore, if an implant is unstable or it is suspected that it would be difficult to stabilize, it is better to wait for graft healing for 6–9 months and going for a two-stage procedure for implant placement; this choice is left to the operator (and the patient).

Felice et al. conducted a multicenter trial with the aim to understand which procedure, one- or two-stage technique lateral window technique, could be preferable when augmenting sinuses with residual bone heights of 1–3 mm.[18] They evaluated the outcome of implants up to 1-year postloading follow-up. Both techniques were able to achieve the planned goals, and no statistically significant differences were observed. In addition, complications were similarly distributed between groups. In this study, only one implant did not obtain sufficient stability at placement.

 Indirect Sinus Lift

A crestal approach for SFE with subsequent placement of implants was first suggested by Tatum in 1986.[5] Utilizing this crestal approach, a “socket former” for the selected implant size was used to prepare the implant site. A “green-stick fracture” of the sinus floor was accomplished by hand tapping the “socket former” in a vertical direction. After preparation of the implant site, a root-formed implant was placed and allowed to heal in a submerged way.

Summers (1994) later described another crestal approach, using tapered osteotomes with increasing diameters.[19] Bone was conserved by this osteotome technique because drilling was not performed. Adjacent bone was compressed by pushing and tapping as the sinus membrane was elevated. Then, autogenous, allogenic, or xenogenic bone grafts were added to increase the volume below the elevated sinus membrane [Figure 3].{Figure 3}

Indirect osteotome maxillary SFE is generally employed when the residual bone height is equal to or >6 mm;[19] in cases with higher resorption, the direct sinus elevation technique is used.[20] The indirect osteotome technique offers a number of advantages: the surgery is more conservative, sinus augmentation is localized, there is a low rate of postoperative morbidity, a shorter time to implant loading is possible than with the direct technique, and high survival rates of around 90% are obtained.

 Direct Versus Indirect Sinus Lift Procedure

Pal et al. compared the two different ways of SFE: (a) lateral antrostomy as a one or two step procedure as direct method and (b) osteotome technique with a crestal approach as indirect method.[21] They found that the gain in bone height was significantly greater in direct procedure through lateral antrostomy (mean 8.5 mm) than in indirect method through crestal approach by osteotome technique (mean 4.4 mm). They concluded that osteotome technique can be recommended when more than 6 mm of residual bone height is present and an increase of 3–4 mm is expected. In case of more advanced resorption, direct method through lateral antrostomy has to be performed. Both sinus elevation techniques did not seem to affect the implant success rate.

Esposito et al. found in a review that if residual alveolar bone height is 3–6 mm, a crestal approach to lift the sinus lining and place 8-mm implants may lead to fewer complications than a lateral window approach to place implants at least 10 mm long.[22]

 Minimally Invasive Surgery

A minimally invasive surgical procedure has been defined in general surgery as a procedure that is carried out with the least damage possible to the patient. The procedure is called “minimally invasive” when there is minimal damage to biological tissues at the point of entrance of the instrument.[23]

There are several minimally invasive sinus lift devices available in the market, namely Hatch Reamer, Sinu-Lift System, Sinus Master, Sinus Crestal Approach (SCA) kit, Dentium Advanced Sinus Kit, sinus lateral approach kit, Dr. Cosci Drill, and Sinus Lift Drill. Cho et al.[24] and Kang and Lee[25] reported that sinus membrane elevation using the Hatch Reamer showed a very high success rate with rapid sinus membrane elevation. Lee and Kim reported that quick and safe sinus membrane elevation was possible even at the septum area using the SCA kit, which was a high-speed drill with a special blade, reducing the risk of sinus membrane perforation. Zhou et al. also evaluated the effectiveness of sinus lift using SCA kit and found that it effectively lifts the sinus floor and reduce the incidence of postoperative complications.[26]

The antral membrane balloon elevation technique is another minimally invasive technique to elevate the sinus membrane. An inflatable balloon is used to elevate the sinus membrane. The piezoelectric minimally invasive system involves the use of piezoelectric tips to elevate the sinus membrane, thereby completely eliminating chances of sinus perforation. This technique has been proposed for lateral osteotomies.

 Minimally Invasive Transcrestal Minimally Invasive Technique Sinus Augmentation Approach Using Calcium Phosphosilicate Putty to Elevate the Sinus Membrane

Another novel technique by Kher et al. (2014) evaluated a simplified minimally invasive transalveolar sinus elevation technique utilizing calcium phosphosilicate (CPS) putty for hydraulic sinus membrane elevation.[27] In this technique, transcrestal SFEs are performed using a modification of Summers' technique. Full-thickness mucoperiosteal flaps are elevated to gain access to the alveolar crest. An osteotomy is initiated at the ridge crest using a 2.0 mm pilot drill. The drill is stopped 1 mm short of the estimated height of the sinus floor, following which a periapical X-ray is obtained to verify the exact position of the drill in proximity to the sinus floor. The osteotomy is then further widened using the drilling sequence recommended by the implant manufacturer. A small quantity of approximately 0.2 cm of CPS putty is delivered in the osteotomy via a narrow tipped cartridge delivery system to act as a cushion before tapping the sinus floor, and a 3-mm concave osteotome with depth markings and a mallet are used to carefully fracture the floor of the sinus. Care is taken not to push the osteotome into the sinus cavity to avoid inadvertent perforation of the sinus lining.

Following the green-stick fracture of the floor of the sinus, the bone substitute is directly injected into the prepared sinus cavity via the cartridge delivery system. Once the cartridge tip fits tightly in the osteotomy, allowing the insertion pressure to be delivered directly to the fractured inferior border of the sinus floor, 0.5 cm of CPS putty is carefully injected into the osteotomy. The hydrostatic pressure exerted by the putty results in an atraumatic elevation of the sinus floor. CPS putty can be added in increments until adequate elevation of the Schneiderian membrane is seen on intraoperative radiographs. An appropriately sized implant is subsequently placed at the level of the osseous crest using a manual torque wrench for enhanced tactile sensation. The implants are initially engaged into the remaining native bone at the crest of the ridge and then slowly twisted in to engage in the viscous CPS putty at the apical aspect of the osteotomy. Cover screws are later placed and flap closure achieved [Figure 4].{Figure 4}

The authors claim that the most significant benefit from the use of this technique is that it can achieve a gain in bone height comparable with that achieved with the use of the lateral window approach, while maintaining the advantage of the less invasive transalveolar approach. It also overcomes the need to purchase the specialized equipment required to apply hydraulic pressure for the elevation of the Schneiderian membrane, while simultaneously placing an adequate volume of the graft material in the site to allow for placement of the implants. Its atraumatic nature, reduced chairside times, reduced overall treatment duration, improved patient comfort, and minimal graft wastage are additionally beneficial. The limitations of the technique proposed are the operator skill and experience necessary for success, and the minimum 3 mm of available bone height needed for achieving primary stability for the implant.

Minimally invasive technique sinus augmentation (MITSA) has been used along with osseodensification (OD), which is a novel, biomechanical, nonexcavation osteotomy preparation technique developed by Huwais in 2013.[28] OD technique generates a layer of condensed autograft surrounding the implant along the surface of the osteotomy making it valuable in clinical settings where there is an anatomic paucity of bone. The logic behind OD concept is that compacted, autologous bone immediately in contact with an endosteal device will not only have higher degrees of primary stability due to physical interlocking between the bone and the device, but also facilitate osseointegration due to osteoblasts nucleating on instrumented bone in close proximity to the implant.[29]

Ossedensification is done using specially designed burs (Densah™ burs) that help densify bone [Figure 5] as they prepare an osteotomy.[30] When the specialized drill is used at high speed in an anticlockwise direction with steady external irrigation (Densifying Mode) [Figure 6], the dense compact bone tissue is created along the osteotomy walls.[31] The pumping motion (in and out movement) creates a rate-dependent stress to produce a rate-dependent strain and allows saline solution pumping to gently pressurize the bone walls. This combination facilitates an increased bone plasticity and bone expansion.{Figure 5}{Figure 6}

The efficacy of this new surgical technique to enhance bone density, ridge width, and implant secondary stability was evaluated by Trisi et al. in a recent study.[32] The researchers inserted 20 implants in the iliac crest of two sheep. On the left sides, they used the conventional drilling protocol (control group), while on the right sides, they inserted the implants using the OD method (test group). Biomechanical and histological analyses were performed after 2 months. The authors report a significant increase of the ridge width and bone volume percentage of approximately 30% in the test group compared to the control group. In addition, better removal torque values and micromotion under lateral forces were recorded for the test group. The increase of bone density in the test group was particularly evident in the most coronal implant region where bone trabeculae were thickened because of incorporation of autogenous bone fragments during the healing process. It was concluded that the OD procedure is able to increase the bone volume around implants inserted in low-density bone which may lead to enhanced implant stability.

Lahen et al. in their study examined the effect of OD on the primary stability and early osseointegration of implants. Their results showed that the OD drilling technique significantly enhanced insertion torque values which are considered in this study as a method to gauge device primary stability. After 6 weeks in vivo, histometric results suggest that the experimental group drill design positively influenced osseointegration when utilized in both clockwise or counterclockwise (OD) directions. Thus, they concluded that regardless of the design of implant, the OD drilling technique enhanced the primary stability and bone to implant contact. They also concluded it as a result of densification of autologous bone debris at the bone walls.[29]

The computer-aided design/computer-aided manufacturing (CAD/CAM) approach has also been used for sinus elevation. Pozzi and Moy described a new procedure for sinus elevation using computer-guided planning and a guided surgical approach through the use of CAD/CAM-generated surgical template in combination with expander-condensing osteotomes, thus ensuring a minimally invasive surgical technique.[33]

 Complications in Sinus Lift Surgery

The various intraoperative, early postoperative, and late postoperative complications of maxillary sinus augmentation with identification of their possible cause(s) are as follows:[16]

1. Intraoperative

BleedingBuccal flap tearInfraorbital nerve injuryMembrane perforation.

2. Early postoperative

Incision line openingBleedingBarrier membrane exposureInfraorbital nerve paresthesia.

3. Late postoperative

Graft loss/failureImplant failureOroantral fistulaImplant migrationInadequate graft fill.

The sinus membrane rupture and other intraoperative and postoperative complications of surgery can decrease the predictability of the procedure and affect the success rate of the implants. The most common complication involving sinus elevation is membrane perforation. The incidence of this occurrence has been reported to range 10%–56%. Various techniques proposed to manage these perforations include suturing, the use of collagen membrane, fibrin sealants, and freeze-dried human lamellar bone sheets.[34],[35],[36],[37] The “Loma Linda pouch” technique involves the use of a slow-resorbing collagen membrane with external tack fixation, which results in complete coverage of all the internal bony walls.[38]

The complications can be largely reduced when the technique is performed with great care and all the necessary preoperative and postoperative protocols are followed. A considerable amount of bone formation takes place around the apical region of the implant, which predicts the long-term stability of the implant. Thus, we can conclude that, being aware of the complications associated with the implant treatment of posterior maxilla, the indirect or internal sinus lift can be considered as a promising method to restore the same.


As maxillary posterior region poses a challenge in implant placement, lot of research has been focused in developing a predictable technique for sinus augmentation and MITSA is currently providing dentists with good sinus lift and immediate implant placement. The major part of success with implant placement in this region lies in treatment planning. It is of utmost importance that the preoperative evaluations are done perfectly and the most suitable technique is decided accordingly for that particular situation, to improve the prognosis of that treatment. As with everything else, this procedure must also have a learning curve, which every budding implantologist will have to go through, but once those initial difficulties and glitches are resolved, this is certainly a great method for placing implants in the posterior maxilla.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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