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The Steiner Sinus Lift

Sinus lift surgery has proven to be a successful method of providing adequate bone for dental implants in the atrophic maxilla. The Steiner Sinus Lift procedure is a surgical technique that allows the sinus to be entered at its lowest point through a 3-4 mm osteotomy, significantly reducing surgical trauma.

The unique characteristics of Sinus Graft have enabled the development of new surgical procedures. In adults, the size of the maxillary sinus often needs to be reduced to permit tooth replacement with dental implants. However, the cost, morbidity, and surgical complexity associated with maxillary bone augmentation has limited the use of this procedure. The Steiner Sinus Lift addresses each of these issues with the intention of making maxillary bone augmentation in the floor of the sinus a simple, non-traumatic procedure within the skill level of all dental practitioners.

When the alveolar ridge that separates gingiva from the sinus is 2.5 mm in thickness or greater, this area of the maxilla will contain trabecular bone in the remaining alveolar ridge. The bone lining the sinus wall will contain an osteoid-like layer. The osteoid-like layer of bone is firm, but flexible and lucent (Figure 1). This layer appears to have minimal mineralization, which accounts for its flexible nature. Histologically, this layer of bone is indistinguishable from cortical bone. When preparing an osteotomy into the maxillary sinus form the lateral wall, hard bone is present until encountering what appears to be a soft tissue separation from this osteoid-like layer. Histology bears out this clinical finding (Figure 1).

The lift of the sinus membrane with hydraulic pressure while injecting the graft material helps to avoid membrane tears. Bonding of the graft material to the implant stabilizes the implant and facilitates successful implant integration.

Figure 1: Sinus Bone Anatomy
S: Sinus
O: Osteoid-like layer
A: Artifact
CT: Soft connective tissue
B: Mineralized bone
When the sinus membrane is removed, the osteoid like layer is encountered and a layer of soft connective tissue is found. Adjacent to the layer of soft connective tissue is hard mineralized bone. This structure may explain why sinus grafting is a very successful procedure. The sinus membrane is perfused with capillaries that penetrate the osteoid-like layer and anastomose with capillaries in the soft connective tissue layer immediately under the osteoid-like layer. The fragility of the osteoid-like layer and the presence of a large soft connective tissue layer immediately beneath the osteoid-like layer provides an excellent source of vascularity and cells of osteogenic potential surrounding the graft site when the remaining alveolar ridge is 2.5 mm in thickness or greater.

When there is greater than 2 mm of alveolar ridge remaining, trabecular bone with its accompanying regenerative cells is found without cortical bone lining the sinus or the alveolar crest. However, when there is less than 2mm of alveolar ridge remaining, trabecular bone is lost and only cortical bone remains. In these cases, the osteoid-like layer is present but it is not backed by a rich layer of soft connective tissue. This is a significant factor in tissue engineering. Cortical bone is over 90% mineralized tissue and contains no regenerative cells. Whereas trabecular bone is less than 50% mineralized tissue and contains regenerative bone precursor cells.

The presence or absence of regenerative cells in the local tissues dictates the tissue engineering principals that need to be considered in order to achieve clinical success. The surgical procedure outlined here is designed for those patients who have approximately 2.5 mm of alveolar ridge remaining or more.

Materials and Method

A series of 30 implants were placed in grafted sinuses via the Steiner Sinus Lift technique, using Sinus Graft as the graft material. The average age of the patient pool was 58 years. The age range of the patient pool was 44-92 years. There was no screening for various disease states or habits. A wide range of diseases were represented in the patient pool. A small percentage of the patients were smokers. No patients were excluded from the study for health reasons. At the end of the study, the average time since placement was 16 months with a time range of 6 to 33 months. The range of pregraft alveolar bone was between 2.5 and 8 mm with an average alveolar bone thickness of 4.6mm.

Sinus manipulation and grafting was performed using 6X magnification on surgical glasses with headlamp illumination (Designs for Vision Inc.) To perform the Steiner Sinus Lift, a crestal incision is made to accommodate implant placement and to expose the buccal alveolar ridge of the maxilla to the lowest point of the maxillary sinus. Periapical radiographs are used to approximate the floor of the sinus.

Figure 2: A #8 round bur is used to prepare the osteotomy

A #8 round bur is used to perforate the lateral wall of the maxillary sinus at the lowest point of the sinus. As the internal wall of the sinus is approached, the dark sinus is easily noted prior to perforating into the sinus. At this stage, switch to a #8 multifluted round bur. The multifluted round burr removes bone smoothly, thereby preventing damage to the sinus membrane. As discussed previously, a thin osteoid-like layer of bone separates mineralized bone from the sinus membrane. The osteoid-like layer of bone is not solidly fixed to the surrounding bone as there is a significant layer of soft connective tissue between the bone of the maxilla and the osteoid-like layer of bone supporting the sinus membrane. The osteoid-like layer does not have to be completely removed.
Figure 3:
O: Osteoid-like bone lining
M: Sinus membrane
B: Bone
The micropaddle is approximately 1mm in diameter
In Figure 3, the osteoid-like layer presents with cracks and a small area of exposed membrane. This osteoid-like layer is pliable and can be displaced with hand instruments. The osteotomy is commonly between three and four millimeters in diameter and two to three millimeters deep.

Figure 4

A 1mm micropaddle (SteinerBio) is pressed onto the osteoid-like layer or the sinus membrane and slipped between the membrane and bone (Figure 4). The micropaddle is held in contact with bone as the membrane is released a few millimeters around the circumference of the osteotomy.

Figure 5

When the initial dissection of the membrane around the circumference of the osteotomy is complete, the sinus is entered with a microball (Figure 5). Contact is maintained with bone as the membrane is dissected off the floor of the sinus until the medial wall of the sinus is reached. The membrane is dissected mesial and distal to the osteotomy as needed.

Figure 6

Sinus Graft is loaded into a monoject syringe for delivery into the maxillary sinus. The physical and osteogenic properties of Sinus Graft™ make this surgical modality possible. As the graft material is injected, the sinus membrane rises under hydraulic pressure (Figure 6). The tip of the syringe is cut to develop a diameter that seals the osteotomy orifice. The syringe tip is manipulated to limit the amount of graft material that leaks between the maxilla and syringe tip as it is injected. The amount of sinus lift is determined by the amount of graft material injected.

The graft material will first fill the void created by the mechanical dissection of the sinus membrane from the bone. As this void is filled with graft material, pressure develops between bone and the membrane. In this manner, the lift of the membrane can be directed.
Figure 7:
The graft material fills the posterior portion of the graft site on the left but the sinus membrane remains attached in the mesial portion of the sinus to the right.
The graft material will flow freely until the void is filled where the membrane was mechanically detached from bone is filled. When this void is filled, an increase in resistance is felt as the membrane detaches as it rises. Experience will guide the proper amount of Sinus Graft to inject. If the sinus floor is smooth with no apparent septa or adjacent roots, a two gram packet can be injected. However, if adjacent roots or changes in the sinus floor are nearby, injecting approximately one gram and then radiographically assessing the lift of the membrane is advised. In Figure 7, a gram of Sinus Graft was injected and the radiographic evaluation shows that the membrane remains attached in the mesial portion of the sinus lift area. The sinus is reentered with a small ball instrument and the sinus is mechanically detached from this area before completing the lift procedure.

When placing one or two implants and only grafting a portion of the sinus, a single osteotomy is adequate. However, when the complete floor of the sinus is grafted and three or more implants are placed, two osteotomies are often required.

Figure 8:

A low sinus in the molar region. The posterior maxilla commonly presents with poor bone density and a low maxillary sinus (Figure 8).

Figure 9:
The sinus has been grafted and pilot holes are started.

After grafting with Sinus Graft, the implant osteotomies are initiated (Figure 9). During this part of the procedure, Sinus Graft is beginning to set. Subsequent drills to the final implant depth should be used so as to remove the graft material in the area to be occupied by the implants. If the graft material is not removed, the graft material can be displaced en masse when inserting the implants. Internal irrigation cannot be used, as it would dilute the graft material.

Figure 10:
Three months after sinus lift and implant placement.

Sinus Graft will be completely replaced with bone over the next two months. Commonly, the trabecular bone of the alveolus increases in thickness as bone growth occurs from the wall of the sinus. However, bone growth occurs throughout the grafted sinus as nutrient canals spread and cells migrate into the graft matrix. Bone that forms through surface growth from the wall of the sinus appears radiographically as trabecular bone. Bone that forms in the graft material after perfusion of nutrient canals has the radiographic appearance of cortical bone. Three months after grafting and implant placement, the original alveolus has increased in thickness and the sinus is filled with dense bone as the sinus is experiencing growth of both trabecular bone from the wall and cortical bone in the grafted sinus (Figure 10).

Figure 11:
Four months post grafting and implant placement with the implants restored.

With this technique, implants are placed at the time of sinus grafting. In this case, the implants were restored and loaded 3 months after implant placement and grafting with Sinus Graft (Figure 11).

Figure 12:

The regeneration of bone and the placement of hygienic implants and crowns rival the esthetics and function of a natural dentition. For financial reasons, the patient in this series chose to have only one molar replaced. Widening the distance between implants permitted a complete occlusion for the mandible and excellent esthetics. In addition, a significant cost savings was provided for the patient (Figure 12).

Restorative dentistry courtesy of Dr. Ron Ask, Jackson, CA.
Figure 13:
Twenty months after grafting and implant placement.
At 20 months post op, the bone levels and the density of the bone regenerated in the maxillary sinus remain unchanged from the three month post operative radiograph (Figure 13).

Figure 14:

This surgical technique calls for implant placement at the time of sinus grafting, however the following is an example of a case where implants could not be placed at the time of sinus grafting due to extensive bone loss around a fractured bicuspid (Figure 14).

Figure 15:

The bridge was sectioned from tooth #2, and after the removal of tooth #4, a significant alveolar defect remained. As a result of the root fracture complete loss of the buccal alveolar bone and partial loss of the lingual alveolar bone occurred leaving only a shell of bone separating the lesion from the maxillary sinus. The osteotomy for the completed sinus lift is filled with Sinus Graft, which is white in color and located to the left of the extraction site (Figure 15). The sinus was lifted with Sinus Graft and the ridge was augmented with Ridge Graft followed by primary flap closure. No membranes were used.

Figure 16:
NB: New Bone
OB: Old Bone
Three months after the Steiner Sinus Lift with Sinus Graft and ridge augmentation with Ridge Graft™, the site is ready for implant placement. New bone (NB) in the area of the defect created by the fractured root is hardly distinguishable from the old bone (OB) (Figure 16).
Figure 17:
Seven months after grafting. Three months after restoration.
The success of any regenerative procedure requires consideration of the patient’s regenerative potential and the lesion being treated. Maxillary sinus regeneration is very predictable. However, ridge augmentation is significantly more difficult. In this case, Sinus Graft and Ridge Graft were the only materials used to regenerate the sinus and the ridge. No membranes or granular graft materials were utilized.

This particular case was determined to have high regenerative potential due to the following factors: The patient was a healthy middle aged woman with no negative lifestyle habits; the patient presented with good alveolar structure in her maxilla and mandible, indicating a positive bone balance; the extraction site was filled with granulation tissue and when the granulation tissue was removed, the surface bone actively bled. After removal of granulation tissue, the porosity of the surface of the bone and the presence of blood vessels provided an efficient path for the migration of regenerative cells from the surrounding bone. The same lesion in another patient might require a different surgical methodology.

The implants were restored with hygienic abutments and crowns (Figure 17).
Figure 18:
Seven months after grafting. Three months after restoration.
The health of the tissue around the implants is excellent, with esthetics of the implant restorations superior to the surrounding dentition (Figure 18).

Restorative dentistry courtesy of Dr. Ron Burrell, Santa Rosa, CA.
Figure 19:
Bone core sample 15 weeks after sinus lift with Sinus Graft.
A core sample taken from a sinus 15 weeks after grafting with Sinus Graft, wetted with pharmaceutical grade purified water shows complete resorption of the graft material and significant bone growth (Figure 19).

Results

There were no post operative bleeding complications, no sinus membrane tears occurred, and no post operative sinus infections related to the sinus lift surgery. In one patient as a result of an undiagnosed endodontic lesion on a canine that drained into the maxillary sinus, a portion of the sinus graft material was lost. An apicoectomy was performed on the canine in combination with sinus debridement and re-grafting, which resolved the infection. All 30 implants integrated, but one implant failed at 21 months. The failure was in a bruxism patient who wore a mandibular night guard. Over the time period of the study, the success rate was 97%.

The Steiner Sinus Lift requires between 30 minutes to an hour to perform and patients often report no pain or sensation in the grafted sinus.

Discussion

Sinus lift surgery has proven to be a successful method of providing adequate bone for dental implants in the atrophic maxilla. The characteristics of the graft material presented in this paper has permitted the development of the Steiner Sinus Lift procedure. This surgical technique, which allows the sinus to be entered at its lowest point through a 3-4 mm osteotomy, significantly reduces surgical trauma. The lift of the sinus membrane with hydraulic pressure while injecting the graft material, helps to avoid membrane tears. Bonding of the graft material to the implant stabilizes the implant and facilitates successful implant integration.

The advantages of the Steiner Sinus Lift include:

  • Procedure is minimally invasive
  • The osteotomy is minimal being 1-3 mm deep and 3 to 4mm wide
  • The dark sinus can be easily visualized prior to reaching the membrane
  • The membrane is easily visualized assuring detachment without damage
  • Directed hydraulic pressure lifts the membrane in the desired direction
  • The amount of lift is determined by the volume of graft injected
  • Lifting the membrane with hydraulic pressure prevents membrane damage
  • The graft material sets hard and supports implants placed in minimal bone
  • The graft material bonds to the implant and sinus bone facilitating integration
  • The graft material is osteogenic and quickly resorbed
  • Minimal instrumentation with closed graft permits a sterile technique
  • Implants are placed at the time of sinus grafting
  • Implant are restored 3 months after grafting
  • Simplicity of the procedure requires less time and expertise

Clinicians interested in the Steiner Sinus Lift are encouraged to contact us at contactus@steinerbio.com. You can also email a periapical radiograph of the surgical site to us for a presurgical consultation prior to performing this surgery.

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