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. To cite this article:
Cricchio G, Sennerby L, Lundgren S. Sinus bone formation and implant survival after sinus membrane elevation and implant placement: a 1‐ to 6‐year follow‐up study.
Clin. Oral Impl. Res. 22 , 2011; 1200–1212.
doi: 10.1111/j.1600‐0501.2010.02096.x     

Osteotome sinus floor elevation with concentrated growth factor and simultaneous implant placement with or without bone grafting: a retrospective study

The aim of this study was to compare the clinical effects of osteotome sinus floor elevation (OSFE) combined with concentrated growth factor (CGF) and simultaneous implant placement with or without bone grafting in the maxillary posterior region, where the residual bone height (RBH) was 4–6 mm. A total of 44 patients who underwent OSFE combined with CGF and the simultaneous placement of 60 implants (group A, 31 implants with bone grafting; group B, 29 implants without bone grafting) were included in this retrospective study. The clinical indicators of implants were observed for 24 months. Sinus floor lift height was 6.02 ± 0.99 mm in group A and 5.81 ± 0.72 mm in group B (P = 0.360) after surgery. There was no significant difference in the vertical bone resorption between the two groups at 24 months (P = 0.097). Postoperative pain at 14 days (visual analogue scale) was significantly greater in patients with bone grafting when compared to those without bone grafting (P < 0.001). There was no significant difference in marginal bone loss (MBL) between the two groups (P = 0.707 for MBL during the first 12 months, P = 0.922 for MBL during months 12–24). The implant success rate was 100% with or without bone grafting. The technique of OSFE with CGF, either with or without bone grafting, is safe and reliable in patients with RBH 4–6 mm.     

Instrument for extraction socket measurement in immediate implant installation

The aim of the present study was to create an instrument and a computer program for measurement of extraction sockets and for planning of the immediate replacement of teeth using screw-shaped dental implants. Ten titanium screw-shaped Osteofix Dental Implant System implants (Osteofix, Oulu, Finland) were immediately installed after extraction in nine patients, four women and five men (age 17-62 years). The measurements of fresh extraction sockets were taken at six points (mesio-buccal, buccal, disto-buccal, disto-lingual, lingual and mesio-lingual) using an instrument created by the author. The area of no contact between bone and dental implant was 11-40% (mean 31%, SD 9%), calculated by computer program. If less than 30% of the implant surface area would be in contact with the bone, immediate replacement was abandoned because sufficient primary stability could not be achieved. Guided bone regeneration was promoted by covering the implant and bone defect with deproteinized bovine bone mineral (Bio-Oss, Geistlich AG, Wolhusen, Switzerland) and bioresorbable collagen membrane (Bio-Gide, Geistlich AG), fixed in place with resorbable pins (Resor Pin, Geistlich AG). After 6 months a considerable, statistically significant (P < 0.05) defect reduction of 90% (SD 7%) was noted. It was concluded that an instrument and a computer program created for extraction socket measurement are useful in some borderline cases when there is lack of bone and the success of one-stage implantation is doubtful.     

Minimal invasiveness in the transcrestal elevation of the maxillary sinus floor: A systematic review

In the attempt to reduce the invasiveness of a transcrestal sinus floor elevation procedure, different aspects must be considered; that is, the minimization of intra‑ and postsurgery morbidity, the reduction of treatment time, and the simplification/elimination of the reconstructive technology. Within this context, a systematic literature search was performed for controlled clinical trials evaluating the impact of one or more of these aspects on transcrestal sinus floor elevation invasiveness. Nineteen articles (15 studies) were included. Overall, the results confirmed that transcrestal sinus floor elevation is a minimally invasive and effective option for bone augmentation in the edentulous, atrophic posterior maxilla. By using powered instruments rather than manual osteotomes and hand mallet, the invasiveness of transcrestal sinus floor elevation can be further reduced without affecting its clinical effectiveness. To impact effectively on morbidity, the key elements to consider when selecting instruments for transcrestal sinus floor elevation are (a) their availability as a standardized sequence, to be adapted on predetermined residual bone height, and (b) the possibility to control pressure (eg, with screwable osteotomes) and/or instrument excursion (eg, with stop devices) to fracture the maxillary sinus floor. Among powered instruments, a standardized sequence of drills incorporating a trephine drill seem to be particularly indicated, due to reduced chair time, high tolerability for the patient, and the possibility to isolate a bone core to implement histomorphometric outcomes. At molar extraction sites with an interradicular septum characterized by a height of at least 4 mm, immediate transcrestal sinus floor elevation and implant placement can be considered a valid option to shorten treatment time.     

Bone reformation and implant integration following maxillary sinus membrane elevation: an experimental study in primates

Background: Recent clinical studies have described maxillary sinus floor augmentation by simply elevating the maxillary sinus membrane without the use of adjunctive grafting materials. Purpose: This experimental study aimed at comparing the histologic outcomes of sinus membrane elevation and simultaneous placement of implants with and without adjunctive autogenous bone grafts. The purpose was also to investigate the role played by the implant surface in osseointegration under such circumstances. Materials and Methods: Four tufted capuchin primates had all upper premolars and the first molar extracted bilaterally. Four months later, the animals underwent maxillary sinus membrane elevation surgery using a replaceable bone window technique. The schneiderian membrane was kept elevated by insertion of two implants (turned and oxidized, Brånemark System®, Nobel Biocare AB, Göteborg, Sweden) in both sinuses. The right sinus was left with no additional treatment, whereas the left sinus was filled with autogenous bone graft. Implant stability was assessed through resonance frequency analysis (Osstell^TM, Integration Diagnostics AB, Göteborg, Sweden) at installation and at sacrifice. The pattern of bone formation in the experimental sites and related to the different implant surfaces was investigated using fluorochromes. The animals were sacrificed 6 months after the maxillary sinus floor augmentation procedure for histology and histomorphometry (bone‐implant contact, bone area in threads, and bone area in rectangle). Results: The results showed no differences between membrane‐elevated and grafted sites regarding implant stability, bone‐implant contacts, and bone area within and outside implant threads. The oxidized implants exhibited improved integration compared with turned ones as higher values of bone‐implant contact and bone area within threads were observed. Conclusions: The amount of augmented bone tissue in the maxillary sinus after sinus membrane elevation with or without adjunctive autogenous bone grafts does not differ after 6 months of healing. New bone is frequently deposited in contact with the schneiderian membrane in coagulum‐alone sites, indicating the osteoinductive potential of the membrane. Oxidized implants show a stronger bone tissue response than turned implants in sinus floor augmentation procedures.     

Bone reformation with sinus membrane elevation: a new surgical technique for maxillary sinus floor augmentation

Background: Various maxillary sinus floor augmentation techniques using bone grafts and bone substitutes are frequently used to enable placement of dental implants in the posterior maxilla. A previous case report demonstrated the possibility of promoting bone formation in the sinus by lifting the membrane without using a grafting material. However, the predictability of the technique is not known. Purpose: The aim of this study was to investigate whether sinus membrane elevation and the simultaneous insertion of titanium implants without additional grafting material constitute a valid technique for bone augmentation of the maxillary sinus floor. Materials and Methods: The study group comprised 10 patients in whom a total of 12 maxillary sinus floor augmentations were performed. A replaceable bone window was prepared in the lateral sinus wall with a reciprocating saw. The sinus membrane was dissected, elevated superiorly, and sutured to the sinus wall to create and maintain a compartment for blood clot formation. One to three dental implants were inserted through the residual bone and protruded at least 5 mm into the maxillary sinus. The bone window was replaced and secured with the overlying mucosa. Bone height was measured directly at each implant site at the time of insertion. Resonance frequency analysis (RFA) was performed on each implant at the time of initial placement, at abutment surgery, and after 12 months of functional loading. Computed tomography (CT) was performed in the immediate postoperative period and 6 months later, prior to exposure of the implants. Results: A total of 19 implants (Brånemark System®, TiUnite?, Nobel Biocare AB, Gothenburg, Sweden) in lengths of 10 to 15 mm were placed, with an average residual bone height of 7 mm (range, 4–10 mm). All implants remained clinically stable during the study period. Comparisons of pre‐ and postoperative CT radiography clearly demonstrated new bone formation within the compartment created by the sinus membrane elevation procedure. RFA measurements showed mean implant stability quotient values of 65, 66, and 64 at placement, at abutment connection, and after 12 months of loading, respectively. Conclusions: The study showed that there is great potential for healing and bone formation in the maxillary sinus without the use of additional bone grafts or bone substitutes. The secluded compartment created by the elevated sinus membrane, implants, and replaceable bone window allowed bone formation according to the principle of guided tissue regeneration. The precise mechanisms are not known, and further histologic studies are needed. Sinus membrane elevation without the use of additional graft material was found to be a predictable technique for bone augmentation of the maxillary sinus floor.     

上颌窦提升术同期或延期牙种植的早期临床评价

目的对上颌窦提升术同期或延期牙种植进行早期临床评价。方法37例患者38侧上颌窦进行上颌窦提升同期或延期牙种植,种植体上部结构修复完成后6～36个月定期复查。结果观察期内同期牙种植27侧上颌窦共59颗种植体,松动、脱落1颗,成功率为98.3%。延期牙种植上颌窦11侧共23颗种植体,全部成功。除1颗失败种植体外,其余同期或延期植入的种植体均无松动或脱落,经X线片检查显示植入骨材料改建良好,种植体周围未见明显骨吸收阴影。结论上颌窦提升术同期或延期牙种植的早期临床效果无明显差异。     

Ridge alterations following immediate implant placement and the treatment of bone defects with Bio-Oss in an animal model

Background: Conflicting data exist on the outcome of placing Bio‐Oss® (Geitslich Pharm AG, Wolhausen, Switzerland) into extraction sockets. It is therefore relevant to study whether the incorporation of Bio‐Oss into extraction sockets would influence bone healing outcome at the extraction sites. Purpose: The aim of this study was to assess peri‐implant bone changes when implants were placed in fresh extraction sockets and the remaining defects were filled with Bio‐Oss particles in a canine mandible model. Materials and Methods: Six mongrel dogs were used in the study. In one jaw quadrant of each animal, the fourth mandibular premolars were extracted with an elevation of the mucoperiosteal flap; implants were then placed in the fresh extraction sockets and the remaining defects were filled with Bio‐Oss particles. After 4 months of healing, micro‐computed tomography at the implant sites was performed. Osseointegration was calculated as the percent of implant surface in contact with bone. Additionally, bone height was measured in the peri‐implant bone. Results: Average osseointegration was 28.5% (ranged between 14.8 and 34.2%). The mean crestal bone loss was 4.7 ± 2.1 mm on the buccal aspect, 0.4 ± 0.5 mm on the mesial aspect, 0.4 ± 0.3 mm on the distal aspect, and 0.3 ± 0.4 mm on the lingual aspect. Conclusion: The findings from this study demonstrated that the placement of implants and Bio‐Oss® particles into fresh extraction sockets resulted in significant buccal bone loss with low osseointegration.     

Ridge alterations following immediate implant placement in the dog: flap versus flapless surgery

Objective: To assess the healing process after flap or flapless surgery in immediate implant placement.
Material and Methods: This study was carried out on five Beagle dogs. Four implants were placed in the lower jaw in each dog immediately after tooth extraction. Flap surgery was performed before the extraction on one side (control), and flapless on the contrary (test). After 3 months of healing, the dogs were sacrificed and prepared for histological analysis.
Results: Ten implants were placed in each group. Two failed (one of each group). The percentage of bone–implant contact was very similar in both groups: 64.8% and 65.1% for the flap and the flapless group, respectively. The difference between the mean distance from the peri-implant mucosa margin to the first bone–implant contact at the buccal aspect was statistically significant between both groups (3.02 mm. flapless and 3.69 mm. flap group). The mean first bone–implant contact at the buccal aspect was located in relation to the sand-blasted and acid-etched level at 0.82 mm for the flapless group and 1.33 mm for the flap group. This difference was not statistically significant.
Conclusion: Flapless immediate implant surgery produces a significant reduction in the vestibular biologic width and a minor reduction in buccal bone plate resorption.     

Sinus floor augmentation with simultaneous placement of dental implants using a combination of deproteinized bone xenografts and recombinant human osteogenic protein-1. A histometric study in miniature pigs

Maxillary sinus floor augmentation with autogenous bone has become a widely accepted procedure in implant dentistry. The use of osteoconductive bone substitutes in this indication is controversial, since their use can lead to a prolonged healing time, inhomogenous ossification, foreign body reaction, migration of particles and low bone-implant contact (BIC). The purpose of this study was to examine whether the combination of an osteoinductive protein (recombinant human osteogenic protein-1 (rhOP-1 = bone morphogenetic protein-7) with natural bovine bone mineral (BioOss) would improve ossification and the bone-implant contact (BIC) in a sinus floor augmentation with simultaneous placement of implants. In this study, the maxillary sinus floors in 5 miniature pigs were augmented with 3 ml BioOss containing 420 micrograms rhOP-1 on the test side and 3 ml BioOss alone on the control side. At the time of augmentation a titanium implant (ITI) was inserted from a laterocaudal direction. After 6 months of healing the sites of augmentation were removed and examined in non-decalcified sections by microradiography, fluorescence microscopy of sequentially labelled specimens and by histometry. On both sides, significant amounts of newly-formed bone were observed. However, on the test sites, the percentage of BIC in the augmented area was 80.0% versus 38.6% on control sites. It can be concluded that the application of bone morphogenetic proteins caused a more rapid and enhanced osseointegration of simultaneously placed implants when compared to the bone substitute alone. Therefore recombinant human osteogenic protein-1 delivered by natural bone mineral has the potential to become a clinical alternative for autogenous bone grafts in sinus floor augmentation.