| Osteotome sinus floor elevation is performed by osteotome technique through which hydraulic pressure comes from bone graft materials mixed with blood elevates the sinus floor. Generally, the implanted bone graft material will form new bone tissues to bring a new sinus floor in about 6 months. This procedure was simple, less invasive and higher patient comfort. However, it was a higher sensitivity technique. For bone graft volume required in different membrane elevation height often depends on the experience of the surgeon and surgical techniques, the risk of surgery is often uncontrollable and the osteogenesis after healing period is in great uncertainty. With our limited acknowledge, no study has performed to explore the bone formation law of the bone graft space.CBCT provides a good three dimensional information.In the study, the three dimensional bone formation pattern in sinus floor after osteotome sinus floor elevation was elvaluated by using CBCT, aiming to guide the required bone graft volume. The prevalence of pathological abnormalities in maxillary sinus is very high with a highly variable individual difference in the performance of mucosal thickness and cysts. Untill now, no confirmation has been carried out for whether the mucosal thickening or cysts would affect the osteotome sinus floor elevation.The research was designed as a prospective clinical cohort study. We evaluated and analyzed the clinical outcome. 3D bone formation patterns in grafted area and the physiological changes of sinus mucosal after osteotome sinus floor elevation through clinical following up and CBCT images was measured. We hope the study can provide some useful insights for further clinical work.Part I: Clinical observation of Osteotome sinus floor elevation in conjunction with implant placementObjective: To evaluate clinical effect of Osteotome sinus floor elevation in combination with dental implant placement,including complications,success rate,implant survival rate,marginal bone loss and peri-implant soft tissue conditions of dental implants placed.Material and Methods: Samples were included in the patients who were planned for Osteotome sinus floor elevation owing to the reduced residual bone height of the posterior maxilla at the Department of Oral Implants, School of Stomatology at the Fourth Military Medical University between January 2012 and July 2015. All the surgery were performed by one surgeron. CBCT was performed prior to,immediately or one-day after surgery,before functional loading and following time. All CBCT scans were input a specific software to mearsure linear variables.Clinical examinations were screend at each recall appointment.Results: 103 cases were included in our study. 3 cases treated by the lateral window approach because sinus membrane perforation occurred during OSFE surgery were excluded. Perforation rate was 2.33%.Finally, 100 cases, 53 males and 47 females, aged 49.76±11.34 years, and treated with 126 implants placed in the maxilla were actually completed. One implant lost in healing-time,resulting in 99.2% early success rate.During one and two year follow-up time, all the implants were successfully in function, resulting the cumulative survival rate of implant 92.2%. The mean MBL was 0.37±0.84mm(-0.70~1.65)at 1-year follow-up, and 0.28±0.33mm(-0.32~0.84)at 2-year follow-up period. During the follow-up time,no peri-implant mucositis and peri-implantitis was found in peri-implant soft tissue.Conclusions: Osteotome technique was a predictable option in areas with a reduced bone height subjacent to the sinus Compared with dental implant under normal condition, its long-term survival rate is favorable(99.2% in 2 years). Following up examination indicated that the peri-soft and hard tissues around implants were stable.Part II: Bone formation pattern after osteotome sinus floor elevation:three demensional radiographically evaluation by using CBCTObjectives: To study the three dimensional bone formation pattern in sinus floor after osteotome sinus floor elevation and analyze the affection of different factors to new bone height and volume formation rate in bone grafted area and bone coverage rate around the protrusion part of implant.Materials and methods: Sample collection was the same as previously described. The CBCT images of patients pre- and after operation in addition with final restoration were collected. Mimics image analyzing software was used to analyze the 3D bone formation pattern in bone grafted area in maxillary sinus.Results: A total of 100 patients with 125 implants were analyzed. The average residual alveolar bone height before sinus floor elevation was 7.18±1.20 mm; and the average height of implants in the maxillary sinus was 2.89±0.91 mm. The average elevated height of sinus floor was 4.71±0.81mm; the average floor width of bone grafted area was 7.64±1.46mm; the average grafted bone volume was 42.52±13.79mm3. After healing procedure, the average new bone height was 3.23±0.81mm; the average floor width of newly formed bone was 6.98±1.39 mm and the average newly formed bone volume in maxillary sinus was 26.47±12.46mm3.;the new bone height formation rate was 69.44%±18.79% and the new bone volume formation rate was 61.14±19.45%. Factors such as gender, age, membrane status before the surgery had no significant statistical effect toward the new bone height and volume formation rate(P>0.05).The protrusion height of implant and implant tooth position showed significant effect to the new bone height and volume formation rate. The Logistic regression analysis indicated that only bone space ratio had effect toward the complete bone formation. The higher of the ratio, a higher possibility of complete bone formation was realized(P<0.05). When the space ratio was higher than 0.4,the complete bone formation rate was higher than 90%.No statistic differences were found in elevation height,bone graft volume,new bone height,new bone volume between different membrane scores(P>0.05).Conclusions:Imaging analysis confirmed the better effect was achieved in sinus floor elevation and bone formation after Osteotome sinus floor elevation and revealed the law of three dimensional space of bone graft. Thickened membranes and antral pseudocysts might not be contraindications to OSFE from the standpoint of the impact on the sinus floor elevation and new bone formation.Part Ⅲ: Physiological change of sinus membrane after osteotome technique in conjunction with implant placement:CBCT radiographically evaluation in 2-year follow-up.Objective: To evaluate membrane change in Osteotome sinus floor elevation in conjunction with dental implant placement.Material and Methods: The sample was same to the part I. 104 sinus of 100 patients were evaluated.CBCT was performed prior to, immediately and one-day after surgery,before functional loading and following time. All CBCT scans were input mimics software. The Schneiderian Membrane Thickness(MT) of the elevated region,ostium patency,and other clinical data was evaluated.Results: Based on pre-surgery CBCT scans,Normal membrane(≤ 2 mm)were found in 76 sinus(73.1%). Flat membrane thickening were found in 13 sinus(12.5%). Antral pseudocysts were found in 15 sinus(14.4%). The Schneiderian membrane in both Normal membrane and Flat membrane thickeing all exhibited significant swelling immediately after surgery(P < 0.05),The corresponding changes were also observed for ostium patency with a tendency of transient obstruction( 8.7%) after surgery. Significant difference was found compared to pre-surgery( P < 0.05).Transient membrane swelling disappeared after a mean healing period of 6.51 months.MT were stable in follow-up periods. Compared with pre-surgery CBCT scans,no difference were found in diameter of antral pseudocysts in different periods(P > 0.05).Conclusion: The results showed that OSFE has no significant influence on MT and ostium patency after an average six months healing period except for postoperative transient swelling and obstruction. Thickened membranes and antral pseudocysts might not be contraindications to OSFE from the standpoint of the surgical impact on the Schneiderian membrane. |
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