Abstract
The sinus infiltration technique for sinus floor elevation and simultaneous implant placement has been used successfully when a reduced vertical height is available in the posterior maxilla. However, the effect of the quantity of graft material and the volume of the solution used on the volume of new bone formed has not been fully investigated. The aim of this study was to evaluate, both quantitatively and qualitatively, the new bone formation after sinus augmentation using either the lateral sinus lift or sinus infiltration technique and to determine any correlation with the volume of bone grafting material used. Further, the volume of solution used in the sinus infiltration technique was also assessed. Twenty healthy adults (13 women, seven men) were randomized to two groups, each undergoing one of the two techniques. Quantitative aspects and the space lifted in the sinus floor were analyzed using Simplant Pro Crystal software. No correlation was found between the volume of bone created in the sinus floor and the volume of bone grafting material used for the sinus infiltration technique or the lateral sinus lift. A strong correlation was found between the volume of liquid used in the sinus infiltration technique and the new volume created in the sinus floor.
Implant anchorage in the edentulous maxilla is often challenging due to insufficient bone volume following crestal bone resorption. In the past, clinicians developed surgical augmentation techniques that used the existing space in the maxillary sinus to restore bone height and subsequently create an adequate implant bed. Several modifications to the originally described sinus augmentation procedure have been made; however, the basic principle of increasing maxillary bone height by placing graft material in the maxillary sinus after detaching the Schneiderian membrane remains the same.
After sinus augmentation, the blood supply to the graft and cells originating from the bony walls allow the formation of new bone. The volume of augmented graft is usually proportional to the size of the sinus. The time required for graft resorption and replacement by new bone is longer in a larger sinus. Therefore, many studies have reported that the high osteogenic potential of autogenous bone is essential when sinus floor augmentation is performed in a large sinus.
The use of the sinus infiltration technique for sinus floor elevation and simultaneous implant placement is an emerging technique that results in fewer complications compared with the conventional lateral sinus floor elevation. However, radiological aspects of the newly formed bone with the sinus infiltration technique have not been studied before. The objective of this study was to evaluate, in a prospective manner, the volume and density of the new bone formed in the maxillary sinus following the sinus infiltration technique and lateral sinus lift and to determine any correlation with the volume of bone substitute used. Further, the volume of the solution used in the sinus infiltration technique was also measured.
Materials and methods
Study design
This was a prospective, randomized study, using radiological measures to assess the volume and density of the new bone formed in the maxillary sinus following the sinus infiltration technique and lateral sinus lift and any correlation with the volume of bone substitute used. The volume of the solution used for infiltrating the maxilla sinus was also measured. Approval for the study was obtained from the Ethics Committee of the Union of Tangiers Dental Surgeons. All study participants gave informed consent prior to taking part in this study.
Patient selection
Twenty-six patients were eligible to participate in the study. They required rehabilitation of their dentition in the posterior maxilla with implant placement and sinus floor elevation and were referred to the Tangiers Implant Centre. However, only 20 healthy adult patients in need of sinus floor elevation and implant placement and who fulfilled the eligibility criteria were finally randomized into the two groups of 10 each for the study ( Fig. 1 ). Thirteen were women and seven were men, and they ranged in age from 35 to 58 years.
All patients underwent a clinical and occlusal examination, including panoramic radiography and computed tomography (CT) scan, to allow the planning of implant placement. Simultaneous implant placement was performed with both the sinus infiltration technique and lateral sinus lift.
Subjects were excluded if they had a residual sinus floor >5 mm in height, a maxillary sinus pathology, systemic diseases or conditions that would contraindicate dental surgery (e.g., uncontrolled hypertension, or a history of head and neck radiation), moderate to severe chronic periodontitis in the remaining teeth (i.e., suppuration, bleeding on probing in >30% of the sub-gingival sites, or any site with a probing depth >5 mm), or had undergone recent extractions (less than 1 year previously) in the area involved.
Patients who met the necessary criteria and agreed to participate in the study were required to read, understand, and sign an informed consent form. Eligible patients were assigned randomly to the two groups by opening a sealed envelope. Patients were treated with In-Kone TEKKA implants. These are medical grade titanium alloy implants with an etched and sandblasted surface. Different diameters (3.5, 4, and 4.5 mm) and lengths (10, 11.5, and 13 mm) were used in this study.
Surgical procedure
Sinus infiltration procedure
The procedure was performed using a hydraulic sinus lift instrument, consisting of an intraosseous small titanium screw for bone anchorage to the sinus bone and a hermetic connector that serves to inject the fluid through the intraosseous element. Access was by flapless surgery with the punch technique, or with a horizontal crestal incision, slightly towards the palatal aspect, through the entire length of the edentulous segment and supplemented by buccal releasing incisions extending beyond the mucogingival junction mesially and distally, with full-thickness flap elevation to expose the alveolar crest.
An ultrasonic piezoelectric device (Surgysonic II; Esacrom S.r.l, Bologna, Italy) with a trephine tip was used to prepare the bed for the hydraulic instrument, and a round tip was used to break the sinus floor with minimal contact with the sinus membrane. Once access to the sinus cavity was gained, the membrane was examined for perforation using the Valsalva manoeuvre, and the instrument for the sinus elevation was positioned. The sinus membrane was displaced by the slow injection of a metronidazole infusion (equivalent to only 1/20 of a common 200 mg oral tablet). The volume of fluid injected through the maxilla was measured for all cases and depended on the residual bone height (2–4.5 ml). Membrane integrity was checked by asking the patient to re-perform the Valsalva manoeuvre gently. A large perforation represented an absolute contraindication to continuation of the surgery. Additional autologous platelet-rich fibrin (PRF) matrix was used to reinforce the membrane surface prior to particulate bone grafting (MBCP; Biomatlante Inc., Vigneux de Bretagne, France) in all patients. The access for implant placement was enlarged to 0.5–1.5 mm less than the anticipated implant diameter, depending on local bone height and density, to increase implant stability. Implants were then placed in the socket formed ( Fig. 2 ).
Lateral sinus lift
Full-thickness flaps were elevated to expose the alveolar crest and the lateral wall of the maxillary sinus. The antrostomy in the lateral wall of the maxillary sinus was created using the ultrasound cutting bone, and the lateral window was created. The sinus membrane was elevated with curettes of different shapes until it became completely detached from the lateral and inferior walls of the sinus. PRF was used to seal any small perforation, and depending on the volume of the maxillary sinus bone, graft material (MBCP) was placed inside the sinus of the control group. The access for implant placement was enlarged to 0.5–1.5 mm less than the anticipated implant diameter, depending on the local bone density, in order to increase implant stability. Implants were then placed in the socket formed. Simultaneous implant placement was conducted in all cases.
Preoperative and postoperative care
Before surgery, each patient rinsed their mouth with chlorhexidine digluconate 0.12% and cetylpyridinium chloride 0.05% solution for 2 min. Antibiotic prophylaxis was used in all cases (amoxicillin, or amoxicillin and clavulanic acid), starting approximately 1 h before surgery.
Nutritional supplements (vitamin C, vitamin D3, and calcium) were given for 20 days post surgery, and antibiotics (1 g three times a day amoxicillin, or amoxicillin and clavulanic acid) were continued for 6 days after surgery.
In the case of a patient with a denture, this was not worn before the healing process was complete. In those with natural teeth, a removable bridge could be applied temporarily in order to protect the area. Implants were loaded at 6 months postoperative.
Implant stability
Implant stability was evaluated through the resistance and seating torque of the implant during insertion (>15 N/cm 2 ). Implant stability was evaluated at loading with a Periotest instrument (Medizintechnik Gulden, Modautal, Germany).
X-ray bone volume analysis
A conventional CT scan was obtained at 1 year after surgery. Three-dimensional (3D) images were analyzed using 3D image analysis software (Simplant Pro Crystal; Materialise, Leuven, Belgium) to assess the volume of the new space created by the implant placement and new bone formed in the sinus. The volume was expressed in millilitres ( Fig. 3 ). The density of the graft fraction occupied by the bone substitute and new bone formation were determined with the digitized image system, by analysis of the follow-up CT scan. The density expressed by each type of structure and the total density were determined from these images.
Statistical analysis
Data were analyzed using SPSS v. 10.0 for Windows (SPSS Inc., Chicago, IL, USA). Results are presented as the mean ± standard deviation (SD) values. Pearson’s rank correlation was applied to test the relationships between the volume of the new bone formed and the volume of bone graft material used, and the volume of the new bone formed and the volume of liquid infusion used in the sinus infiltration technique.
Results
Twenty healthy adult patients fulfilled the eligibility criteria (13 women, seven men, ranging in age from 35 to 58 years). These patients required rehabilitation of their dentition in the posterior maxilla and were randomized to two groups of 10 each for the study. Demographic and clinical data for the two study groups are presented in Table 1 .
| Sinus infiltration technique | Lateral sinus lift | P -value | |
|---|---|---|---|
| Age, years, mean ± SD | 43.3 ± 6.2 | 45.5 ± 7.3 | 0.41 |
| Gender, n | 0.63 | ||
| Male | 3 | 4 | |
| Female | 7 | 6 | |
| Tobacco smokers, n (%) | 6 (60%) | 7 (70%) | 0.63 |
Simultaneous implant placement was performed with the sinus infiltration technique or lateral sinus lift. No membrane perforation or intraoperative complication was recorded ( Table 2 ). Postoperative follow-up showed no signs of infection or postoperative swelling in the surgical area in any of the patients. Nevertheless, some patients in both groups presented moderate oedema that disappeared completely a few days later, with no suppuration.
| Sinus infiltration technique | Lateral sinus lift | |
|---|---|---|
| Number of implants | 13 | 15 |
| Implant penetration, mm, mean | 7.5 | 8.9 |
| Implant length, mm, mean ± SD | 11.05 ± 1.01 | 11.5 ± 0.71 |
| Membrane perforation, n (%) | 0 | 0 |
| Height of the membrane elevation, mm, mean | 15.8 | 13.5 |
| Residual bone height, mm, mean ± SD | 2.91 ± 0.82 | 2.7 ± 0.76 |
Radiographic evidence of new bone formation in the elevated sinus area was seen in all patients, in both groups, on CT scan investigations done 12 months after surgery. All sides of the implants were covered with new bone, independent of the group evaluated. The volume of the new space created was 2.94 ± 0.70 ml in the lateral sinus lift group and 3.40 ± 1.30 ml in the sinus infiltration technique group ( Fig. 3 ).
In the lateral sinus lift group, the volume of bone graft material used and the volume of new bone formed were not strongly correlated ( Table 3 ). In the same way, no correlation was found between the volume of the new space formed with the sinus infiltration technique and the volume of bone substitute used. Furthermore, the volume of new bone created with both techniques exceeded the volume of the bone graft used ( Table 3 ), and with the sinus infiltration technique, the new volume formed appeared to depend on the volume of the liquid used in the infiltration procedure rather than on the volume of the bone substitute ( Table 4 ).
