STUDY DESIGN/ SAMPLE
This retrospective study was conducted in Affiliated Hospital of Stomatology, Nanjing Medical University, China. This study complies the Declaration of Helsinki and the Good Clinical Practice guidelines, and was approved by Medical Ethics Committee, School of Stomatology, Nanjing Medical University, China (Approval number: PJ2020-141-001). Informed consent for data evaluation and publishing has been obtained from all included subjects. Patients following our inclusion criteria during March 2021 until January 2022 underwent OSFE with simultaneously implantation, detailed medical record was established for each patient which included medical and dental history, oral examination, surgical records, details of bone grafts materials, and the use of prosthetic reconstruction using single-implant, single crown restorations. Inclusion criteria for enrollment in this study were as follows: Patient underwent OSFE with simultaneously implanting; at least 18 years of age; good general health; adequate oral hygiene, which is bleeding index less of than 30% and plaque score of less than 20%; all subjects have been extracted 1 or 2 maxillary molars or pre-molars because of failure of endodontic treatment, root fracture, or after severe caries for more than 3 months; Residual Bone Height (RBH) of the alveolar bone crest measured on CBCT at each implant site is 2-5mm; an adequate residual alveolar ridge width for implant placement 6 mm or more; absence of any radiographic signs of maxillary sinus pathology; the length of the inserted implants ranged from 8-10mm, 4.1/4.8 mm in diameter (Dentium implant/ ICX implant/ MIS).
Using the R program (R Foundation for Statistical Computing) [29]. The minimum required number of subjects is 107 to evaluate the association between the primary outcome and three categorial variables, assuming a medium effect size is 0.3 measured by Cohen’s, a P-value of 0.05 and a power of 80%. Considering the dropout rate of 20%, a total of 134 subjects are needed. Patient data was excluded for: postoperative CBCT imaging contained not enough clarity or unclear anatomic references; failure to follow the patient to the end of the determined follow up time.
Surgical Procedure
Patients were treated according to the designed treatment plan. Patients were given randomized numbers and assigned into three different groups according those numbers by doctor B.M. The surgery consisted of simultaneous implant placement with sinus augmentation via Osteotome technique (OSFE) by surgeon B.SH. All patients underwent a systemic oral examination and received a CBCT scan before surgery. Pre-operative CBCT image was used to evaluate RBH and crestal bone width, Patients who met our inclusion criteria were selected. For all subjects, local anesthesia was performed, a mid-crestal incision was performed and the flap then raised, with a pilot drill, the implant site was generated using a pilot drill, keeping a distance of 1 mm from the sinus floor. Then with vigilant light tap with a mallet, the bone of the sinus floor was fractured into the sinus cavity, which elevated the Schneiderian membrane, the initial sinus elevation was carried out with osteotomies gradually until the final depth was accomplished. In the first group (Group A), the implant was placed without any grafting material. In Group B, the elevated sinus was filled with (0.25 g) Bio-Oss® Bone Graft, the implant was then inserted immediately. In Group C, the elevated sinus was filled with (100 mg) Bio-Oss Collagen mixed with CGF, the implant was then inserted immediately. All implants were placed in sites with a more palatal position, using a submerged technique and using a two-stage procedure. Immediate postoperative CBCT was taken for all patients.
Postsurgical care following OSFE with simultaneously implants placement was according to the standard Postsurgical treatment after implanting. Rinsing of the mouth with a 0.12% solution of chlorhexidine for 60 seconds, five times a day, for 14 days was prescribed. Anti-inflammatory drugs and the antibiotics, prescribed following surgery.
Grafting Materials
Geistlich Bio-Oss ® small granules (0.25 – 1 mm), (Geistlich Pharma AG, Wolhusen, Switzerland). Geistlich Bio-Oss ® Collagen is comprised of 90% Geistlich Bio-Oss ® granules and 10% of porcine collagen. (Geistlich Pharma AG, Wolhusen, Switzerland). CGF was prepared in the hospital directly before surgery using a previously described method [30], the extracted CGF layer then separated and divided into small fragments, using sterile scissors, and mixed with 100 mg Geistlich Bio-Oss ® Collagen (Figure 1).
Prosthetic Rehabilitation
CBCT was taken for each patient after a healing period of six months, then the second stage surgery was undertaken. Following two weeks second healing period, dental impressions were made. At this point implants survival rate was evaluated. Two weeks later, the final restorations were performed after the insertion of the prosthetic abutments. Each implant was used to hold a single crown.
VARIABLES
The primary predictor variables were three groups according to the application of bone graft: Group A (control group): OSFE with simultaneously implant placement without the application of any bone graft. Group B: (OSFE) with simultaneously implant placement with Bone Graft application (OSFE with Bone Graft). Group C: (OSFE) with simultaneously implant placement with the application of Collagen mixed with CGF as grafting materials. (OSFE with Bone Collagen & CGF). The primary outcome variable was: Implant survival rate. The secondary outcome variables were the change in the endo sinus bone again at different time points which was measured by Height of the apical bone (H, mm), Sinus Lift (SL, mm), Vertical Bone Resorption (VBR, mm), Grafting size (D, mm), Total Bone Resorption (TBR, mm). Implant Stability Quotient (ISQ, between 0 and 100) and Bone density (B, HU). In addition to patients’ pain post-surgery (Yes, No) and patients’ willing to do this procedure again (Yes, No). Covariates included the age by years, sex (male, female), smoking (smoker, non-smoker), Residual Bone Height (RBH, mm), Alveolar Bone Width (ABW, mm), Implant protrusion length (IPL)
DATA COLLECTION
Implant Survival Rate
Implants success was evaluated at two time points. Six months after implant placement, and one year after functional loading of the upper prosthesis. The survival rate was recorded using the following success criteria: at clinical examination no implant mobility; no pain or any unusual complaint from the patient; no peri-implant radiolucency, infection, or neuropathies; fully functional suited prosthetic constructions with no positional change; no any occlusal malfunctions.
Radiographic Evaluation
For each patient, CBCT imaging was performed at each stage as shown in the study flowchart (Figure 2), because of its superior spatial resolution, including preoperative, immediately after first stage surgery T0, 3 months after first stage surgery T1, before Second stage surgery T2, and one year after loading with final restorations T3, using a CBCT machine using GiANO (NewTom, Imola, Italy) with NewTom NNT analysis software. All the linear variables were measured on the coronal cross-sections parallel to the longitudinal direction of the implant, using the measuring tool of NewTom NNT analysis software, the precision of the measuring system is 0.01 mm, measurements were assessed by a single operator three times and the average was calculated. The following are definitions of this study linear variables:
RBH: the vertical distance between the alveolar crest and the floor of the maxillary sinus in the maxilla axis was used to measure RBH before surgery.
ABW: the horizontal width of the alveolar bone was measured at 3 mm below the alveolar bone crest. RBH and ABW were only assessed before surgery using preoperative CBCT. IPL was calculated as the implant length IL minus RBH (IPL=IL-RBH).
On postoperative CBCT taken for each implant at four time points, four planes have been indicated orthogonal to the long axis of inserted implant using the previous software, as shown in (Figure 3). Plane ‘A’ was established passing through highest point of the elevated sinus floor after OSFE, plane ‘B’ was established passing through the vertex of the implant, plane ‘Cp’ was established passing through the bottom level of the maxillary sinus from the palatal side, and plane ‘Cb’ was established passing through the bottom level of the maxillary sinus from the buccal side. H was measured as the vertical distance between plane ‘A’ and ‘B’ at four time points. Immediately after surgery, the maxillary sinus floor plane ‘A’ was above the implant apex of all implants and H0 was greater than 0. At follow-up, when the maxillary sinus floor was on contact with the implant apex, plane ‘A’ and plane ‘B’ became identical and H was considered to be 0. H express the height of the augmented sinus floor and H ≥ 0. SL was calculated as H+IPL at four time points. VBR represented the difference in SL between the different follow-up time points. calculated twice, once as the difference between SL0 and SL2 (VBR1), and once as the difference between SL0 and SL3 (VBR2). D measured the mean of vertical distance between the initial sinus floor and the elevated sinus floor assessed at buccal and palatal sides; calculated as the average of buccal D (the vertical distance between plane ‘A’ and plane ‘Cb’), and palatal D (the vertical distance between plane ‘A’ and plane ‘Cp’). TBR represented the difference in D between the different follow-up time points, calculated twice, once as the difference between D0 and D2 (TBR1), and once as the difference between D0 and D3 (TBR2). H, buccal D, palatal D, D, and SL were measured and calculated four each implant at four time points postoperatively, immediately after first stage surgery T0, 3 months after first stage surgery T1, 6 months after first stage surgery and before second stage surgery T2, and one year after functional loading T3.
Implant Stability Quotient
Implant Stability was measured using The Osstell resonance frequency analyzer (Osstell, Göteborg, Sweden) for each specimen two weeks following the second stage surgery and before dental impression was made. The resonance frequency measurement as an indicator for mechanical implant stability was assigned a value between 0 and 100. ISQ was measured 3 times for each specimen, and the median was calculated.
Bone Density
The volume of bone tissue density was analyzed using NewTom NNT software in a spot diameter of 1 mm at three regions around the center of the measured implant protrusion buccally and lingually. The mean value of the three measurements of the average bone volume then was calculated and expressed in Hounsfield units (HU). B was measured and calculated four each implant at three time points T1, T2, and T3.
Patient’s Satisfaction
Patient’s satisfaction was evaluated by a simple questionnaire 3 days after the first stage surgery, to enquire about pain and discomfort feeling after the surgery, in addition to the patient’s willing to do similar kind of procedures in the future.
DATA Analysis
Statistical analysis of data was performed using IBM SPSS Statistics for Windows, Version 23.0 (IBM Corporation, Armonk, New York). The Shapiro–Wilk test was implemented to assess whether the data followed a normal distribution. ANOVA test followed by Tukey’s post hoc test was applied to analyze differences in RBH, ABW, IPL, SL, D, B, VBR, TBR and ISQ Measurements between three groups (A, B and C) and to look at how each group changed over time. The x2 test was used to compare ISR, sex, smoking and Patient’s satisfaction post-surgery between the three groups. Fisher’s exact test and independent t-test were used to conduct bivariate analyses of the covariates versus ISR. The Pearson’s correlation coefficient was calculated between primary outcome ISR and variables (RBH, B1and B2). Three multiple logistic regressions were implemented to examine the relationship between radiographic measurements (H, D and SL) and ISR at three time points T0, T1 and T2. P < 0.05 was considered to indicate a statistically significant difference.