Computer Guided Low Window Sinus Lift Technique

Study Overview
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Brief Summary
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The study group included 12 patients that were treated using the low window lateral sinus lift technique with simultaneous implant placement. This was facilitated using a CAD-CAM generated surgical guide. Subjective assessment on postoperative pain and swelling as well as objective assessment of implant stability, vertical bone height gained and complications such as Schneiderian membrane perforation rates and bleeding.

Detailed Description
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Presurgical assessment of each patient was performed. Preoperative impressions were taken and study models were mounted. Orthopantogram (OPG) and cone beam computer tomography (CBCT) of the targeted areas were also done in order to evaluate residual bone height between the alveolar bone crest and the sinus floor, residual ridge width, bone quality and planning the number, size and position the implants. Designing the surgical guide was performed using In2Guide™ system powered by OnDemand3D™. The low window design was also planned where the lower osteotomy line will be flushed with the floor of the sinus, the upper line is 6mm of height from the lower line, the mesial line is flushed with the anterior wall and the distal line will correspond to the position of the most distal implant. The final product was fabricated using OnDemand3D™ which was then transferred to the 3d printer machine. Patients were instructed to rinse with 0.125% chlorhexidine antiseptic mouth-wash for 2 minutes prior to surgery. The surgical area was anesthetized with local anesthesia. Infraorbital and greater palatine nerve blocks and local infiltration were given in order to properly anesthetize the area. A crestal incision was made in the posterior edentulous area followed by a vertical incision made at 45 degrees distal to the most anterior tooth. A full thickness mucoperiosteal flap was elevated at the surgical site enabling the apical osteotomy line to be drawn at a distance of 6mm above the residual bone height from the ridge. The customized surgical guide was secured in its proper position. After drilling, the anchor pin was placed in the prepared place. Using the standardized piezoelectric tip (SL1) with sterile saline irrigation, the outline of the window in the lateral maxillary sinus wall was formed. The bone window was thinned down using the specialized DASK drill #4 and #5 from the DASK Kit until the grey shadow of the sinus membrane becomes visible. The sinus membrane at the circumference of the bony window was detached using the dome-shaped Sinus Membrane Elevator (XSE1L). Sinus membrane elevators (XSE2L), (XSE3L) and (XSE4L) were used to carefully lift the sinus membrane from the floor and anterior wall of the sinus to create adequate space for graft material (Figure 2-b). The membrane was further elevated to the medial wall in order to provide additional blood supply from that bone. The implants were drilled in the positions indicated by the surgical guide. Half the amount of the xenograft was introduced into the cavity followed by insertion of the dental implants. The dental implants were placed at torque 30 45N‧cm. Stability of the implants was measured using an implant stability meter. Filling the cavity with the rest of the xenograft was completed after implant placement(s). The size of the collagen membrane was adjusted to match the size of the lateral bone window and then placed and stabilized by the cover screw. The flap was released by short horizontal cuts in the inner surface of the mucosa to provide a tension free flap. This was followed by closure of the flap with water tight sutures (horizontal mattress with a single interrupted it's centre) using 3/0 silk suture material. After 6 months from the operation, a small incision was made directly over the implant and the cover screw was removed. Implant stability was measured again using the Osstell device. The abutment was placed at torque 25 30 N.cm. An impression was taken and sent to the lab for fixed prosthetics construction. The fixed prosthesis was cemented using glass ionomer cement.

Official Title
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Evaluation of Computer-guided Low Window Sinus Lift Technique (A Clinical Trial)

Conditions
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Sinus Perforation

Intervention / Treatment
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* Procedure: Low Window Sinus Lift technique


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients requiring implant placement in the posterior maxilla (Kennedy Classification: Class 1 and Class 2). Age between 20-60 years irrespective of the gender. Tooth extractions at the implant sites were performed at least 4 months before surgery. Residual bone height between the alveolar bone crest and the sinus floor ranges from 4 to 6 mm. Patients who are willing and fully capable to comply with the study protocol. Exclusion Criteria: Maxillary sinus pathologies (sinusitis, long standing nasal obstruction). Any disease contraindicating surgery (e.g. uncontrolled diabetes). Heavy smokers. Acute oral infections. Untreated periodontal disease. Poor oral hygiene. A history of radiotherapy or chemotherapy of the head and neck region. Pregnancy.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sinus elevation using Low Window Sinus Lift technique<br> | Procedure: Low Window Sinus Lift technique<br>* Preoperative CBCT of surgical site and Fabrication CAD/CAM surgical stent, Sinus elevation using Low Window Sinus Lift technique, Implant, bone graft and membrane placement<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Presence or absence of intra or postoperative complications | Schneiderian membrane perforation occurrence is noted intraoperatively Intra/post operative bleeding, postoperative sinusitis, periimplantitis | 6 months | 
| Postoperative pain | This was assessed using a 10-point Visual Analogue Scale (VAS) in the 1st week postoperatively. (0-1=None, 2-4=Mild-Moderate, 8-10= Severe) | 1 week | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Implant stability | Implant stability is measured using the Osstell device immediately following implant placement and 6 months postoperatively (prior to abutment loading). | 6 months | 
| Postoperative edema | This was assessed in the 1st week postoperatively and measured as follows: None (no inflammation) Mild (intraoral swelling confined to the surgical field) Moderate (extraoral swelling in the surgical zone) Severe (extraoral swelling spreading beyond the surgical zone)+ | 1 week | 
| Bone Density | Radiographic evaluation of bone density around each implant was done using OnDemand3D™ program. Measurements were taken as follows: From the tool bar, the bone density around the implant was selected from task section. The required area was selected and bone density was chosen. Mean, standard deviation, minimum and maximum readings were automatically displayed by the system. | 6 months | 
| Vertical bone height gained | 4 reference points are selected on the CBCT. A vertical line immediately adjacent to the implant threads perpendicular to the horizontal line is drawn to a point on the bony floor of the maxillary sinus. From the cross-sectional view of 6 months postoperative, the distance from the crestal bone at the implant platform and the bone apical to the implant apex. The measurements are then subtracted from the preoperative bone height to obtain the amount of vertical bone height gained. | 6 months | 
| Marginal bone loss | Marginal bone loss (MBL) were measured at the buccal and palatal aspects of each implant using the implant/abutment junction as a reference point to the most coronal bone-implant junction. Measurements were performed on the CBCT immediately after surgery (baseline) and 6 months postoperatively. A decrease in this vertical distance between the reference point and the most coronal bone-implant contact on consecutive radiographs indicated a marginal bone loss (MBL). | 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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sinus augmentation