Giovanni Cricchio

Sinus membrane elevation and simultaneous insertion of dental implants: a new surgical technique in maxillary sinus floor augmentation

Sinus membrane elevation and simultaneous insertion of dental implants : a new surgical technique in maxillary sinus floor augmentation.

Sinus bone formation and implant survival after sinus membrane elevation and implant placement: a 1- to 6-year follow-up study.

OBJECTIVES To investigate the long-term clinical and radiographic results of the maxillary sinus membrane elevation technique where implants were inserted in a void space created by the elevation of the sinus membrane without adding any graft material. MATERIALS AND METHODS A total of 84 patients were subjected to 96 membrane elevation procedures and simultaneous placement of 239 implants. Changes of intra-sinus and marginal bone height in relation to the implants were measured in intraoral radiographs taken at insertion, after 6 months of healing, after 6 months of loading and then annually. Computerized tomography was performed pre-surgically and 6 months post-surgically. Resonance Frequency Analyses measurements were performed at the time of implants placement, at abutment connection and after 6 months of loading. The implant follow-up period ranged from a minimum of one to a maximum of 6 years after implants loading. RESULTS All implants were stable after 6 months of healing. A total of three implants were lost during the follow-up period giving a survival rate of 98.7%. Radiography demonstrated on average 5.3±2.1 mm of intra-sinus new bone formation after 6 months of healing. RFA measurements showed adequate primary stability (implant stability quotient 67.4±6.1) and small changes over time. CONCLUSION Maxillary sinus membrane elevation and simultaneous placement of implants without the use of bone grafts or bone substitutes result in predictable bone formation with a high implant survival rate of 98.7% during a follow-up period of up to 6 years. The intra-sinus bone formation remained stable in the long-term follow-up. It is suggested that the secluded compartment allowed for bone formation according to the principle of guided tissue regeneration. The high implant survival rate of 98.7% indicated that the implants sufficiently supported the fixed bridges throughout the study period. This technique reduces the risks for morbidity related to harvesting of bone grafts and eliminates the costs of grafting materials.

Histological outcomes on the development of new space-making devices for maxillary sinus floor augmentation.

BACKGROUND Previous studies have pointed out that the mere elevation of the maxillary sinus membrane promotes bone formation without the use of augmentation materials. PURPOSE This experimental study aimed at evaluating if the two-stage procedure for sinus floor augmentation could benefit from the use of a space-making device in order to increase the bone volume to enable later implant installation with good primary stability. MATERIALS AND METHODS Six male tufted capuchin primates (Cebus apella) were subjected to extraction of the three premolars and the first molar on both sides of the maxilla to create an edentulous area. The sinuses were opened using the lateral bone-wall window technique, and the membrane was elevated. One resorbable space-making device was inserted in each maxillary sinus, and the bone window was returned in place. The animals were euthanatized after 6 months, and biopsy blocks containing the whole maxillary sinus and surrounding soft tissues were prepared for ground sections. RESULTS The histological examination of the specimens showed bone formation in contact with both the schneiderian membrane and the device in most cases even when the device was displaced. The process of bone formation indicates that this technique is potentially useful for two-stage sinus floor augmentation. The lack of stabilization of the device within the sinus demands further improvement of space-makers for predictable bone augmentation. CONCLUSIONS It is concluded that (1) the device used in this study did not trigger any important inflammatory reaction; (2) when the sinus membrane was elevated, bone formation was a constant finding; and (3) an ideal space-making device should be stable and elevate the membrane to ensure a maintained connection between the membrane and the secluded space.

Histological Findings Following the Use of a Space-Making Device for Bone Reformation and Implant Integration in the Maxillary Sinus of Primates

BACKGROUND Previous studies have shown that membrane elevation results in predictable bone formation in the maxillary sinus provided that implants can be placed as tent poles. In situations with an extremely thin residual crest which impairs implant placement, it is possible that a space-making device can be used under the sinus membrane to promote bone formation prior to placement of implants. PURPOSE The present study was conducted to test the hypothesis that the use of a space-making device for elevation of the sinus membrane will result in predictable bone formation at the maxillary sinus floor to allow placement of dental implants. MATERIALS AND METHODS Eight tufted capuchin primates underwent bilateral sinus membrane elevation surgery, and a bioresorbable space-making device, about 6 mm wide and 6 mm in height, was placed below the elevated membrane on the sinus floor. An oxidized implant (Nobel Biocare AB, Gothenburg, Sweden) was installed in the residual bone protruding into the created space at one side while the other side was left without an implant. Four animals were sacrificed after 6 months of healing. The remaining four animals received a second implant in the side with a space-making device only and followed for another 3 months before sacrifice. Implant stability was assessed through resonance frequency analysis (RFA) using the Osstell (Osstell AB, Gothenburg, Sweden) at installation, 6 months and 9 months after the first surgery. The bone-implant contact (BIC) and bone area inside the threads (BA) were histometrically evaluated in ground sections. RESULTS Histologically there were only minor or no signs of bone formation in the sites with a space-making device only. Sites with simultaneous implant placement showed bone formation along the implant surface. Sites with delayed implant placement showed minor or no bone formation and/or formation of a dense fibrous tissue along the apical part of the implant surface. In the latter group the apical part of the implant was not covered with the membrane but protruded into the sinus cavity. CONCLUSIONS The use of a space-making device, with the design used in the present study, does not result in bone formation at the sinus floor. However, membrane elevation and simultaneous placement of the device and an implant does result in bone formation at the implant surface while sites with implants placed 6 months after membrane elevation show only small amounts of bone formation. It is suggested that lack of stabilization of the device and/or a too extensive elevation of the membrane may explain the results.

Immediate Loading of Implants Placed Simultaneously with Sinus Membrane Elevation in the Posterior Atrophic Maxilla: A Two-Year Follow-Up Study on 10 Patients

BACKGROUND Clinical studies on immediate loading of implants in the posterior atrophic maxilla are rare. PURPOSE The study aims to evaluate immediate loading of implants placed with sinus membrane elevation without additional grafting material for bone augmentation of the maxillary sinus floor. MATERIALS AND METHODS The study group comprised of 10 patients in whom a total of 10 maxillary sinus floor augmentations were performed. A total of 21 dental implants (1 to 4) were inserted through the residual bone to protrude into the maxillary sinus under the elevated sinus membrane. The implant site was underprepared to improve primary stability. All the implants were inserted with a torque insertion no less than 20 Ncm. Implants were loaded immediately after surgery with a screw-retained temporary acrylic restoration. Intraoral X-rays were taken at implant insertion, after 6 months loading, and after 1st and 2nd year of loading. Resonance frequency analysis (RFA) was performed at the time of initial placement and after 6 months of functional loading. RESULTS RFA after implant insertion gave an implant stability quotient (ISQ) level with a range from 62 to 72. All implants remained clinically stable during the follow-up period of 2 years. Radiography demonstrated on average 5.7 ± 3.4 mm of intrasinus new bone formation after 6 months of implant loading. RFA measurements showed ISQ mean values of 67 (range: 62-72) and 68 (range: 62-71) at placement and after 6 months of loading, respectively. CONCLUSION Within the limits of this case series report, it is concluded that maxillary sinus membrane elevation with simultaneous placement and immediate loading of implants without the use of any additional grafting material shows predictable results after 2 years of functional loading. Moreover, evidence of intrasinus bone formation around the implants was found in all patients. Further studies are needed to study the influence of immediate loading on the mineralization of bone forming at dental implant sites.

On the Early Mechanisms of Bone Formation after Maxillary Sinus Membrane Elevation: An Experimental Histological and Immunohistochemical Study

BACKGROUND Previous studies have shown predictable bone formation in the maxillary sinus after membrane elevation. However, how and where the bone is formed is not well understood. PURPOSE The aim of the study was to histologically and immunohistochemically study the early bone formation events in primates after membrane elevation in the maxillary sinus. MATERIALS AND METHODS Nine adult male tufted capuchin primates (Cebus apella) were included in the study. Eight animals were subjected to bilateral maxillary sinus membrane elevation using a lateral replaceable bone window technique. One oxidized dental implant was placed into the maxillary sinus cavity on both sides. In four animals, one sinus was left without any additional treatment, whereas the contralateral sinus was filled with autologous bone grafts from the tibia. In two animals, the implants were inserted under the elevated sinus membrane on both sides. In two animals, the sinus membrane was totally removed. The animals were euthanized after 10 or 45 days. One nonoperated animal representing pristine tissue conditions served as control. The maxillary sinuses with implants were retrieved and further processed for light microscopic ground sections or decalcified sections for immune-histochemical analyses. RESULTS Bone formation started from the bottom of the sinus floor, sprouting into the granulation tissue along the implant surface under the elevated membrane irrespective of time and surgical technique. Bone formation was not seen in direct conjunction with the sinus membrane. A distinct expression of osteopontin was observed in the serous glands of the lamina propria close to the implant within all groups. CONCLUSION Bone formation after sinus membrane elevation with or without additional bone grafts starts at the sinus floor and sprouts into the elevated space along the implant surface. The sinus membrane does not seem to present osteoinductive potential in sinus membrane elevation procedures in this study.

Tomographic, Histological, and Immunohistochemical Evidences on the Use of N-Butyl-2-Cyanoacrilate for Onlay Graft Fixation in Rabbits

BACKGROUND The bone tissue responses to Cyanoacrylate have been described in the literature, but none used N-butyl-2-cyanoacrilate (NB-Cn) for bone graft fixation. PURPOSE The aims of the study were: (a) to analyze the bone grafts volume maintenance fixed either with NB-Cn or titanium screw; (b) to assess the incorporation of onlay grafts on perforated recipient bed; and (c) the differences of expression level of tartrate-resistant acid phosphatase (TRAP) protein involved in bone resorption. MATERIALS AND METHODS Eighteen New Zealand White rabbits were submitted to calvaria onlay grafting on both sides of the mandible. On one side, the graft was fixed with NB-Cn, while on the other hand the bone graft was secured with an osteosynthesis screw. The computed tomography (CT) was performed just after surgery and at animals sacrifice, after 1 (n = 9) and 6 weeks (n = 9), in order to estimate the bone grafts volume along the experiments. Histological sections of the grafted areas were prepared to evaluate the healing of bone grafts and to assess the expression of TRAP protein. RESULTS The CT scan showed better volume maintenance of bone grafts fixed with NB-Cn (p ≤ 0.05) compared with those fixed with screws, in both experimental times (analysis of variance). The immunohistochemical evaluation showed that the TRAP expression in a 6-week period was significantly higher compared with the 1-week period, without showing significant difference between the groups (Wilcoxon and Mann-Whitney). Histological analysis revealed that the NB-Cn caused periosteum damage, but provided bone graft stabilization and incorporation similar to the control group. CONCLUSION The perforation provided by screw insertion into the graft during fixation may have triggered early revascularization and remodeling to render increased volume loss compared with the experimental group. These results indicate that the NB-Cn possesses equivalent properties to titanium screw to be used as bone fixation material in osteosynthesis.