Statement of the problem: Vertical bone height reduction after extraction in the posterior maxilla complicates the treatment plan. Lateral sinus elevation, crestal sinus elevation, using short implants and different grafting procedures are some of the proposed treatment protocols, however, there is still a gap of knowledge in high quality evidence for the most effective approach. Purpose : The aim of the study is to evaluate clinical long term implant stability and radiographic vertical bone height gain after implant placement in posterior maxilla using crestal sinus approach in comparison to lateral sinus elevation technique. Materials and Methods: Thirty patients have single maxillary posterior tooth in atrophic maxilla will be enrolled. Patients will be allocated randomly into two groups; group 1 (test group) will receive implants using crestal sinus approach and group 2 (control group) will be assigned to the lateral sinus elevation technique, no bone grafts will be placed in both groups. Resonance frequency analysis will be employed to measure implant stability with a dedicated device (Osstell). For each implant, implant stability quotient ISQ values will be measured from the four sites.The mean of all measurements will be rounded to a whole number and regarded as the final ISQ of the implant. ISQ values will be obtained after implant insertion, at 3 months after delivery of the final restoration, at 6 and 12 months post-surgical. CBCT will be taken at 3 &12 months follow up periods, to assess the amount of bone height gained around the dental implants in both groups.

1. Clinical examination and preoperative evaluation using CBCT:

   1. Evaluation of the patient's general condition of the oral cavity, to make sure it complies with the criteria required to be enrolled in the study in terms of oral hygiene, pathological conditions, occlusion and inter-arch space.
   2. A preoperative CBCT will be performed for each patient prior to the surgery. Evaluation of available bone height and bucco-palatal bone width. Suitable implant length and diameter will be determined as well.

2. Random allocation: The patients will be divided into two groups with random allocation. Allocation ratio is 1:1. Randomization list will be provided using computerized excel sheet and will be concealed to the principle investigator till the time of the surgery, and will be kept with a contributor (Ingy Kastour) a clinician in IDCE who is not involved in the trial procedures. A phone call will be done after administration of anesthesia to reveal the randomization sequence for each case.

3. Blinding: The outcome assessors will be blinded, the outcome assessor (CoI-II) for the implant stability and the outcome assessor (CoI-V) for the vertical bone height difference obtained from blinded CBCTs, outcome assessor (CoI-III) of the other variables will be also blinded. Blinding of the principle investigator and participants cannot be achieved due to different surgical procedures

4. Surgical procedure:

   After administration of local anesthesia, the allocation will be revealed, for the test group, a Full thickness flap will be elevated at the edentulous site with two vertical releasing incision and then the preparation of osteotomy will be prepared following standard implant system protocol preparation of the osteotomy. Drilling will be done gently till reaching 0-1mm from the sinus floor, then implant placement will take place and the implant itself will be used to gently elevate the sinus up to 3-5mm. For the control group, a full-thickness flap will be elevated at the edentulous site with two vertical releasing incisions extending to the vestibule for better reflection and exposure to the lateral wall of the sinus. The lateral antrostomy will be prepared in the lateral sinus wall using rotary bur no. 8 to provide adequate access to remove the thin to thick cortical bone and to expose the thin sinus membrane. The membrane will be elevated across the sinus floor and up the medial wall and this elevation must extend anteriorly-posteriorly to provide the exposed sinus floor. Drilling will be done gently till reaching 0-1mm from the sinus floor, then implant placement will take place. Primary stability of the implant will be measured by rotational insertion torque value, to be ≥30Ncm(25). A resorbable collagen membrane will be placed over the window preparation in the lateral approach to prevent the flap tissue in cooperating inside the antrostomy and the osseointegration process. Primary closure of the flap will be achieved.

5. Postoperative Care:

   1. Antibiotics (Amoxicillin 1g orally- twice daily for 5 days).

   2. Anti-inflammatory drugs (NSAIDS; Ibuprofen 600mg three times daily for 5 days).

   3. Antiseptic mouth rinse (0.12% Chlorhexidine oral rinse) will be prescribed starting from the second day for 60 seconds, 15 ml each time, two times a day for 14 days.

   4. Patient self-care instructions:

      • Application of an ice bag to the treated area for the first 24 hours will be instructed.
      • The patients will be instructed to gently brush the operated area after two weeks with a soft brush.
      • In case of emergency; severe pain and bleeding, the patient will call the co-investigator and will be presented to the clinic.
      • Patients will be recalled after two weeks for suture removal and every month for supportive periodontal therapy and recording of outcome variables at three, six and twelve months.

After 3 months of the implant placement, stage II will be performed, 2 weeks later, impressions will be taken as regular for the prosthetic crowns fabrication. All crowns will be temporary cemented to allow an easy access to the implant platform for the follow-up RFA measurements.

Inclusion Criteria:

1 Patients who have at least one missing posterior maxillary tooth. 2. Adults above the age of 18. 3. Bone height from 4mm to 6mm under the maxillary sinus assessed in CBCT. 4. Good oral hygiene. 5. Patient accepts to sign an informed consent.

Exclusion Criteria:

1. Smokers.
2. Pregnant and lactating females
3. Medically compromised patients. as Uncontrolled diabetic patients, patients taking bisphosphonates injection for treatment of osteoporosis, patients with active cardiac diseases, patients undergoing radiotherapy or chemotherapy, or any other medical and general contraindications for the surgical procedure (i.e. ASA score ≥III)
4. Patients with active infection related at the site of implant/bone graft placement.
5. Patients with untreated active periodontal diseases.
6. Patients with parafunctional habits.
7. Acute or chronic sinusitis.

All data can be shared

One year

Principal investigator