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.     

Radiographic evaluation of dental implants placed using an osteotome technique

BACKGROUND: The osteotome technique has been successfully used for implant placement when a limited vertical height is available at posterior maxilla. However, it is not clear if new bone is formed at the apical portion of the implant placed by this technique without any bone graft. The aim of this study was to radiographically evaluate bone formation around dental implant surfaces exposed to the space created at the sinus floor without the presence of any graft material. METHODS: Forty patients (21 male, 19 female; mean age 46.7 years) who received a total of 75 dental implants together with indirect sinus lifting procedure were included. Initial and 6-month postoperative panoramic films were scanned and analyzed using a commercially available software program. Implants were divided into two groups: initial alveolar bone height <9 mm or > or =9 mm. This helped determine the effect of available bone and exposed implant surface on bone formation in a system where the shortest implant was 8 mm. RESULTS: The mean implant length placed at locations with <9 mm initial bone height (mean 7 +/- 1.3 mm, N = 29 implants) was 11 +/- 1.7 mm; gain in bone height was 3.9 +/- 1.9 mm. At locations where minimum bone height was 9 mm (mean 10.4 +/- 0.7 mm), 44 implants were placed with a 13.5 +/- 1.06 mm mean length. Mean gain in bone height was 2.9 +/- 1.2 mm at these sites. Two implants were lost at stage 2 surgery. The success rate after 25 months of loading was 97.3%. CONCLUSIONS: It is possible to radiographically observe a gain of approximately 3 to 4 mm of bone from the sinus floor to the implant apex. The amount of initial alveolar bone height, presence of sinus membrane perforation, and the amount of exposed implant surface appear to play a role in the presence or absence of radiopacity within the elevated sinus floor, following 6 months of healing.     

Implant surface preparation in the surgical treatment of experimental peri-implantitis with autogenous bone graft and ePTFE membrane in cynomolgus monkeys

The aim of the present investigation was to assess the effect of four implant surface preparation methods used in the surgical treatment of experimental peri-implantitis with autogenous bone graft and expanded polytetrafluoroethylene (ePTFE) membrane. The methods were air-powder abrasive unit+citric acid, air-powder abrasive unit, gauze soaked in saline+citric acid, and gauze soaked alternately in chlorhexidine and saline. A total of 64 implants with a titanium plasma-sprayed (TPS) surface was placed in eight cynomolgus monkeys (Macaca fascicularis). After a 3-month period with plaque control, experimental peri-implantitis was induced. A bone loss of 4-6 mm was established after 9-17 months and plaque control was re-implemented. The peri-implantitis defects were surgically exposed, granulation tissue was removed, and each implant surface was prepared by one of the above-mentioned procedures. The defects were then filled with autogenous bone graft particles and covered by an ePTFE membrane. The animals were sacrificed after 6 months. Evaluation by clinical parameters, radiography including quantitative digital subtraction radiography, histology, and stereology did not reveal significant differences between the methods. Almost total bone regeneration and considerable re-osseointegration were obtained irrespective of the method applied. A mean bone-to-implant contact of 39-46% was observed within the defects. Therefore, the present study of implants with a TPS surface in cynomolgus monkeys indicates that the simplest method involving gauze soaked alternately in chlorhexidine and saline should be the preferred implant surface preparation method in the surgical treatment of peri-implantitis involving autogenous bone graft and ePTFE membrane.     

Osseointegration of Osseotite and machined titanium implants in autogenous bone graft. A histologic and histomorphometric study in dogs

It has been shown that a roughened implant surface results in a higher percentage of bone to implant contact (%BIC) than a machined one. A modified implant surface using a dual thermo-acid etching process (Osseotite) has been introduced and evaluated clinically, mechanically and histologically. The aim of the present study was the histological evaluation of the %BIC between the Osseotite or machined surfaces and the autogenous bone graft. Twenty-two custom-made split-type 10-mm-long implants having two opposing surfaces (Osseotite and machined) were placed between the cranial and caudal dorsal iliac spine at the iliac wing of two adult mongrel dogs. An artificial bone defect was created leaving a 2 mm empty space around the coronal 5 mm of the implants, while the apical 5 mm was stabilized in the existing basal bone. The defects around the implants were filled with particulate autogenous bone graft, covered by an Osseoquest membrane, and left to heal for 5 months. All inserted implants showed a complete integration in the bone tissue. It was found that the resulting %BIC at the Osseotite surface was significantly higher than at the machined one in both regenerated (46.44+/-15.81% vs. 28.59+/-12.04%) and basal bone areas (32.32+/-15.09% vs. 17.25+/-7.40%). The findings of this study imply that the use of autogenous bone graft resulted in significantly higher %BIC values in the regenerated area than in the basal bone area itself, for both implant surfaces.     

Osteotome-mediated sinus floor elevation: a clinical report

PURPOSE: It was the aim of the present study to clinically evaluate the success of osteotome-mediated sinus floor elevation (OMSFE) using autogenous and xenogenic bone and a variety of screw-type implants. MATERIALS AND METHODS: From August 1995 to February 2003, 276 OMSFE procedures with simultaneous implant placement were completed in 167 patients. RESULTS: The mean residual bone height (RBH) of the alveolar ridge was 7.1 mm (range 3 to 10 mm). The mean increase in height of the implant sites using osteotome techniques was 3.8 mm (range 2 to 7 mm). Of the 276 implants placed, 240 had been loaded for an average of 27.9 months (range 1 to 84 months). There were a total of 18 failures: Ten implants failed to integrate, 3 implants were lost within the first 18 months of loading, 1 implant fractured after 3 years in function, and 4 implants demonstrated excessive bone loss. The overall survival rate was 93.5%. When only sites with an RBH of 4 mm or less were considered, the survival rate dropped to 73.3%. Small tears in the schneiderian membrane were clinically assessed at 13 sites, for a detectable perforation rate of 4.7%. DISCUSSION: The primary determinant in implant survival with OMSFE procedures was the height of the residual alveolar ridge. Implant design, graft material, and the method of sinus floor infracture (direct or bone-cushioned) exerted minimal influence on survival outcome; however, factors such as edentulism, osteoporosis, and an overdenture prosthesis were shown to negatively influence postloading survival of implants placed in areas of limited RBH. CONCLUSION: OMSFE procedures can be used predictably for implant placement at sites with moderate vertical deficiencies in the posterior maxilla.     

Patterns of tissue remodeling after placement of ITI dental implants using an osteotome technique: a longitudinal radiographic case cohort study

The aim of this prospective study was to document radiographically tissue remodeling patterns around ITI implants placed according to an osteotome technique. In 19 consecutive patients from a private practice, 25 implants of the ITI Dental Implant System were placed subjacent to the sinus floor. Implant beds were pre-prepared with pilot drills and/or using the Summers Osteotome Kit. Bio Oss particles were mixed with autologous bone and inserted into the apex area. Implants were placed self-tapping. The sinus floors were thereby pushed up with attempts not to sever the Schneiderian membrane. Healing occurred submerged or semi-submerged and was uneventful in 24/25 implants. At 1 year, all implants had been restored with crowns or short fixed partial dentures. One implant was lost in the first 3 weeks, but was replaced 6 months later in a second attempt. Intraoral radiographs were obtained presurgically and postsurgically at 3 and 12 months. The mean preoperative distance between the sinus floor and the crest was 7.0 mm (range 2.3-10.3 mm). The mean distances between the implant apex and the initial sinus floor were: 3.66 +/- 1.74 mm mesially and 4.44 +/- 1.62 mm distally. The mean height of the new bone reaching apically and mesially to the implants was 1.52 +/- 2.48 mm at surgery, but was reduced significantly to 1.24 +/- 1.30 mm at 3 months and 0.29 +/- 1.91 mm after 12 months (Hotelling's test P< or =0.01). Similar values were obtained at the disto-apical aspects. In an attempt to assess periapical bone/graft remodeling, a novel index was applied: 0=no bone/graft visible, 1=cloudy appearance of new bone/graft, 2=clearly visible new bone/graft disappearing structures of original sinus floor, 3=new bone/graft with new cortical plate and the former boundary of the sinus floor disappearing. This index increased statistically significantly from baseline to 12 months (Hotelling's test P< or =0.02). In conclusion, this study shows that in areas with reduced bone height subjacent to the sinus, an osteotome technique may provide a minimally invasive way to obtain implant abutments predictably. The grafted area apical to the implants undergoes shrinkage and remodeling. The original boundary of the sinus is eventually consolidated and replaced by a new cortical plate. In addition to the linear measurements, the novel index may assist in assessing periapical remodeling at implants placed with an osteotome technique.     

Maxillary Sinus Floor Augmentation Surgery with Autogenous Bone Grafts as Ceiling: A Pilot Study and Test of Principle

Background: Studies have pointed out that the mere elevation of the maxillary sinus membrane might suffice to allow for bone formation indicating the additional use of augmentation materials to be redundant. Purpose: The purpose of this study was to assess whether elevation of the sinus mucosal lining combined with applying an autologous bone graft as a ceiling and placement of a short implant would allow for bone formation around the implant thus surpassing the need for applying augmentation materials around the installed implants. Materials and Methods: Fourteen consecutive patients were subjected to maxillary sinus floor elevation surgery and simultaneous placement of an implant. Using the lateral bone‐wall window technique, the membrane was exposed and elevated. Next, a bone graft taken from the zygomatic rim was placed as a ceiling above the inserted implant to ensure that the sinus membrane would not collapsed around a significant part of the implant. Finally, the bone window was returned in place. After connecting the healing abutment, the wound was closed. Results: All implants were stable and no implants were lost. There were no complications after harvesting the bone graft. Radiographic evaluation showed a bone gain of 3.2 ± 0.9 mm after 3 months and 3.6 ± 0.9 mm after 1 year. Less than 6% of the implant was not covered by bone after 1 year. Conclusion: Maxillary sinus membrane elevation and simultaneous placement of short endosseous implants with a bone graft as a ceiling on top of the implant result in predictable bone formation around the implant and good osseointegration on radiographs.     

A 5-year follow-up study on one-stage implants inserted concomitantly with localized alveolar ridge augmentation

The aim of this study was to evaluate the success of one-stage implants placed at the time of alveolar bone augmentation using simultaneous guided bone regeneration technique with a collagen barrier membrane in patients suffering from insufficient bone width. Seventeen patients were treated with 20 one-stage OSTEOFIX (Oulu, Finland) implants using simultaneous guided bone regeneration technique. Dehiscence defects were filled by bovine bone mineral Bio-Oss and covered with collagen membrane. Clinical and radiographic parameters of the peri-implant conditions were assessed at the moment of prosthesis placement and at 1- and 5-year follow-ups. Diagnostic dehiscence defect measurements after implant placement showed that the mean vertical defect varied from 3.8 mm to 10.0 mm. At the moment of prosthesis placement and at 1- and 5-year follow-ups all implants were stable, painless and without biological complications. Clinical and radiographic parameters of the peri-implant conditions remained stable during follow-up. The cumulative implant survival rate was 100% after the 5-year observation period and the success rate for all pooled implants was 90%. The present study showed predictable treatment outcomes recorded after 5 years of function for one-stage OSTEOFIX (Oulu, Finland) oral implants placed simultaneously with guided bone regeneration using collagen membrane and deproteinized bovine bone mineral.     

Clinical results of alveolar ridge augmentation with mandibular block bone grafts in partially edentulous patients prior to implant placement

A group of 15 partially edentulous patients who needed alveolar ridge augmentation for implant placement, were consecutively treated using a two-stage technique in an outpatient environment. A total of 18 alveolar segments were grafted. During the first operation bone blocks harvested from the mandibular ramus or symphysis were placed as lateral or vertical onlay grafts and fixed with titanium osteosynthesis screws after exposure of the deficient alveolar ridge. After 6 months of healing the flap was re-opened, the screws were removed and the implants placed. Twelve months after the first operation implant-supported fixed bridges could be provided to the patients. Mean lateral augmentation obtained at the time of bone grafting was 6.5 +/- 0.33 mm, that reduced during healing because of graft resorption to a mean of 5.0 +/- 0.23 mm. Mean vertical augmentation obtained in the 9 sites where it was needed was 3.4 +/- 0.66 mm at bone grafting and 2.2 +/- 0.66 mm at implant placement. Mean lateral and vertical augmentation decreased by 23.5% and 42%, respectively, during bone graft healing (before implant insertion). Mandibular sites showed a larger amount of bone graft resorption than maxillary sites. All the 40 implants placed were integrated at the abutment connection and after prosthetic loading (mean follow-up was 12 months). No major complications were recorded at donor or recipient sites. Soft tissue healing was uneventful, and pain and swelling were comparable to usual dentoalveolar procedures. A visible ecchymosis was present for 4 to 7 days when the bone was harvested from the mandibular symphysis. From a clinical point of view this procedure appears to be simple, safe and effective for treating localised alveolar ridge defects in partially edentulous patients.     

Barrier membrane and bone graft treatments of dehiscence-type defect at existing implant: a case report

Dehiscence-type bony defects may occur after implant application because of microbial action as well as of biomechanical and occlusal overload. The aim of the treatment of a periimplant defect is to arrest the progression of the bone loss and to achieve a maintainable site for the implant. In these situations, barrier membranes and bone graft materials can be used to achieve complete bone healing around dental implants. Bone regeneration is possible in a periimplant bony defect of a functioning implant if the proper surgical technique is utilized and the etiologic cause is eradicated. This study presents the surgical coverage of a periimplant bony defect around an implant that was inserted 7 years ago. The surgical correction was made using a barrier membrane in conjunction with bone graft materials. A follow-up of 6 months seemed to reveal radiographic bone regeneration.     

Conditions for success in guided bone regeneration: retrospective study on 376 implant sites

BACKGROUND: Used alone or in association with bone, guided bone regeneration is a clinically accepted method to increase the volume of bone during implant placement. Concerns about appropriate surgical techniques and the predictability of the results questions still exist. The aim of this study was to assess the conditions for success. METHODS: Three-hundred-seventy-six implants were placed in association with 214 non-resorbable membranes. In 109 implants, the membrane was secured on a blood clot; for 213 implants, membrane was placed with autogenous bone; and for 54 implants it was placed with allogenic bone. The surgical procedure, the primary closure, the timing of re-entry, and the density of regenerated tissue were studied. RESULTS: In 19 membranes, barrier exposure occurred before 3 months in these instances, the regenerated tissue was removed; another 7 membranes were exposed between 3 and 6 months. The 188 non-exposed membranes were removed between 6 and 12 months. In cases of exposure before 3 months, the regenerated tissue was soft and then removed. After closure for 6 months or more, the regenerated tissue was dense and resistant to probe pressure. The best results were obtained when the membranes were placed with autogenous bone. CONCLUSIONS: If all the clinical steps are appropriately followed, guided bone regeneration using an autogenous bone graft and implant placement is a predictable technique for increasing bone volume.     

Bone regeneration of dental implant dehiscence defects using a cultured periosteum membrane

OBJECTIVES: This study aimed to demonstrate the feasibility of a cultured periosteum (CP) membrane for use in guided bone regeneration at sites of implant dehiscence. MATERIAL AND METHODS: Four healthy beagle dogs were used in this study. Implant dehiscence defects (4 x 4 x 3 mm) were surgically created at mandibular premolar sites where premolars had been extracted 3 months back. Dental implants (3.75 mm in diameter and 7 mm in length) with machined surfaces were placed into the defect sites (14 implants in total). Each dehiscence defective implant was randomly assigned to one of the following two groups: (1) PRP gel without cells (control) or (2) a periosteum membrane cultured on PRP gel (experimental). Dogs were killed 12 weeks after operation and nondecalcified histological sections were made for histomorphometric analyses including percent linear bone fill (LF) and bone-to-implant contact (BIC). RESULTS: Bone regeneration in the treatment group with a CP membrane was significantly greater than that in the control group and was confirmed by LF analysis. LF values in the experimental and the control groups were 72.36+/-3.14% and 37.03+/-4.63%, respectively (P<0.05). The BIC values in both groups were not significantly different from each other. The BIC values in the experimental and the control groups were 40.76+/-10.30% and 30.58+/-9.69%, respectively (P=0.25) and were similar to native bone. CONCLUSION: This study demonstrated the feasibility of a CP membrane to regenerate bone at implant dehiscence defect.     

Evaluation of sinus floor elevation using a composite bone graft mixture

BACKGROUND: The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase needed vertical height to overcome this problem. The present study described and reported a simple, safe and predictable bone graft mixture for the sinus lifting procedure. MATERIAL AND METHODS: Seventy patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with a composite graft of cortical autogenous bone, bovine bone and platelet-rich plasma (PRP). A total of 263 implants (171 Astra Tech and 92 Microdent) were placed either simultaneously or delayed. All sites were clinically and radiographically evaluated 24 months after their prosthetic loading. Biopsy samples were taken from 16 delayed implant placement sites at the time of their implant placement. RESULTS: A 100% implant success rate was found after 24 months of functioning. Only two Microdent implants failed before loading, which translates to a 99% overall implant success rate. No statistically significant differences were found between simultaneous and delayed implant placement. Image processing revealed 34+/-6.34% vital bone, 49.6+/-6.04% connective tissue and 16.4+/-3.23% remaining Bio-Oss particles. However, the histomorphometric analysis showed that the bovine bone was incorporated into new bone formation. CONCLUSION: The results showed that a composite graft comprised of cortical autogenous bone, bovine bone and PRP mixture can be successfully used for sinus augmentation.     

上颌窦侧壁抬升植骨种植的临床研究

目的:探讨应用上颌窦侧壁抬升植骨方法进行种植的优缺点和近远期效果。方法:2000年1月至2006年12月对28例患者行上颌窦侧壁抬升植骨种植。上颌窦底提升高度6.9mm-14.7mm,平均11.2mm。采用人工骨Bio-Oss或自体血提取的富血小板血浆(platelet-richplasma,PRP)与人工骨Bio-Oss混合填入上颌窦,用可吸收性胶原膜Bio-Gide覆盖。共抬升32侧,植入种植体57枚,均采用固定修复。种植后追踪时间9-62个月,平均28个月。观察方法为临床检查和X线检查,采用Wheeler存留标准评估,纳入Kaplan-Meier存留曲线统计。结果:在随访过程中,一颗植体在植入7个月后松动最终取出,其余植体稳定性良好,使用正常,患者满意,据Wheeler存留标准统计存留率为98.2%。结论:当上颌后牙区牙齿缺失且余留骨量不足时,通过上颌窦侧壁开窗抬升植骨可以有效增加骨高度,满足种植的骨条件,近远期效果理想。     

Peri-implant bone loss around posterior mandible dental implants placed after distraction osteogenesis: preliminary findings

BACKGROUND: The present study evaluates implant survival and peri-implant bone loss around posterior mandible dental implants placed at sites of distraction osteogenesis. METHODS: On removal of the distraction devices, 34 dental implants were inserted into 14 posterior mandible sites in 10 healthy, non-smoking female patients. Prosthetic treatment was performed 4 months after implant placement using fixed implant prostheses. After 6 to 16.5 months, periapical radiographs were taken and evaluated for peri-implant bone loss and radiolucency. The distance between the implant margin and the first visible bone-implant contact was measured on the mesial and distal aspects of the implants using imaging software. Radiographic dimensional distortion was corrected as a function of the known true dimension of the implant. RESULTS: Of the 34 implants placed, two (5.9%) failed to integrate at reentry surgery. Both were replaced and restored during the course of the study so that a total of 34 implants was followed for 12.1 +/- 3.8 months post-restoration and 16.1 +/- 3.8 months post-insertion. Mean loss of marginal bone height was 2.6 +/- 1.0 mm. During the follow-up period, radiolucent lines along the implant surface were absent. CONCLUSIONS: The mean peri-implant bone loss in areas of alveolar bone distraction was 1.9 mm/year. A high implant survival rate was observed.     

Immediate loading of the grafted maxillary sinus using platelet rich plasma and autogenous bone: a preliminary study with histologic and histomorphometric analysis

OBJECTIVE: The goal of this clinical study was to evaluate dental implant survival rates using the concept of a nonfunctional, immediate loading protocol with nonsplinted dental implants in the grafted maxillary sinus during a 52-week period. Random histomorphological and histomorphometric analysis was completed to evaluate the early healing effect of platelet rich plasma (PRP) and 50% autogenous bone combined with 3 different substitute graft materials. MATERIALS: Four to 8 months after grafting the sinus with PRP sprayed autogenous bone combined with 3 different substitute graft materials in a 50:50 composite ratio, 27 hydroxyapatite- coated dental implants were surgically placed in 41 patients and immediately loaded between 48 hours and 5 days later with custom titanium abutments and acrylic provisional restorations placed out of functional occlusion. Six months later, definitive ceramometal restorations were cemented on to the custom abutments. RESULTS: During a 52-week observation period, no implants were lost. Between 4 and 8 months of graft healing time, histologic and histomorphometric analysis revealed formation of new vital bone in different graft specimens ranging from 77% to 100%. CONCLUSION: The preliminary results of this clinical study indicate that immediate nonfunctional loading using PRP and 50% autogenous bone combined with different substitute graft materials is a predictable protocol in the grafted maxillary sinus as early as 4 months of postgrafting. The high implant survival rate is due to the early formation of large percentages of new vital bone as confirmed by using histologic and histomorphometric analysis.     

钛膜和胶原膜联合应用引导种植体周骨缺损骨再生的临床研究

目的：评价钛膜与胶原膜联合应用引导种植体骨缺损骨再生的临床效果。方法：将34颗种植体植入30例患者的狭窄形牙槽嵴或唇颊骨壁缺损拔牙窝,所有种植体的唇、颊侧面部分暴露,种植体周骨缺损空间维持能力较差。测量种植暴露部分的最大长度,将羟基磷灰石珊瑚骨粉置于骨缺损处,采用钛膜覆盖稳定骨移植材料,然后将胶原膜覆盖于钛膜表面,无张力缝合伤口,术后6个月行Ⅱ期手术,取下钛膜,检查骨缺损骨再生的状况,再次测量种植暴露部分的最大长度。结果：2例患者于手术3个月左右因钛膜局部暴露,将钛膜取出。钛膜暴露率为6.6%。术后6个月Ⅱ期手术时见,所有种植体暴露部分完全被再生骨覆盖,种植体暴露部分长度为0。结论：在空间维持能力较差的骨缺损处,钛膜和胶原膜联合应用引导骨再生可获得理想结果。钛膜和胶原膜联合应用可显著降低钛膜的暴露率,延迟发生膜暴露的时间,从而使引导骨再生的结果更加具有可预测性。     

Histologic results from a human implant retrieved due to fracture 5 years after insertion in a sinus augmented with anorganic bovine bone

BACKGROUND: Little is known about the healing pattern and the osseointegration processes at the interface of implants placed into different grafting materials in man. Anorganic bovine bone (ABB) is a xenogenic material with a high biocompatibility and osteoconductivity. METHODS: A 47-year-old patient underwent a monolateral sinus-augmentation procedure using 100% ABB. Two titanium dental implants were inserted at the same time as the grafting procedure. After 6 months, a fixed prosthetic restoration was placed. After a 5-year loading period, the distal implant fractured, and the implant was removed with a 5-mm trephine bur. RESULTS: At low magnification, in the peri-implant bone in the grafted area, many particles of ABB were still present. Bone was always interposed between the ABB particles and the metal surface, and in no case were the graft particles in contact with the implant. No acute or chronic inflammatory cell infiltrate or foreign body reactions were present around the particles or at the bone-implant interface. The tissues around the implant were composed of 40% +/- 2.4% bone, 12% +/- 2.9% ABB particles, and 50% +/- 6.2% marrow spaces. The percentage of bone-to-implant contact was 48.6% +/- 3.7%. CONCLUSIONS: A high percentage (~50%) of direct contact between bone and implant, without the interposition of graft material particles, was present. ABB had enabled implant integration to take place, which had remained stable for 5 years.     

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目的观察冲压法上颌窦底提升同期牙种植体植入术对上颌窦黏膜的影响。方法收集2012年1月至2015年8月于第四军医大学口腔医院口腔种植科就诊,因上颌后牙区垂直骨高度不足连续行冲压法上颌窦底提升术的患者100例(共100侧上颌窦),同期植入Straumann种植体126枚。于术前、术后1 d、术后6个月拍摄锥形束CT(CBCT),分析该术式对上颌窦黏膜的影响。结果上颌窦正常黏膜和增厚黏膜在术后1 d的CBCT上均观察到黏膜厚度的增加,与术前黏膜厚度的差异有统计学意义(P<0.05);术后1 d上颌窦鼻道开口阻塞发生率显著增加(0.09%),与术前差异有统计学意义(P<0.05)。不同时期上颌窦假性囊肿直径无明显变化(P>0.05)。结论从对上颌窦黏膜及生理功能的影响来看,上颌窦黏膜增厚和假性囊肿并非冲压法上颌窦提升术的绝对禁忌证。     

Comparative study of buccal dehiscence defects in immediate,delayed, and late maxillary implant placement with collagen membranes: clinical healing between placement and second-stage surgery

BACKGROUND: Implants can be placed at the time of tooth extraction (immediate), after several weeks (delayed), or after complete healing (late). The purpose of this study was to evaluate clinical bone healing of buccal dehiscence-type defects around maxillary implants placed together with bioabsorbable collagen barrier membranes and bone graft at the 3 time points. METHODS: Three implant placement protocols were compared: immediate procedures primarily closed by a rotated split palatal flap (19 patients, 23 implants; group 1); delayed sites closed by a rotated (full-thickness) palatal flap at the time of tooth extraction (25 patients, 39 implants; group 2); and late implantation (22 patients, 40 implants; group 3). One to 3 proximal implants were simultaneously placed. Defect height and width were measured at the time of implant placement and at second-stage surgery. Surface area was calculated as half ellipses. RESULTS: The best results were obtained with delayed implantation. The mean percentage of the reduced defect height for groups 1, 2, and 3 was 77.4%+/-16.92%, 88.8%+/-15.29%, and 75.2%+/-17.99%, respectively, and the mean percentage area of the reduced defect was 90.2%+/-9.15%, 95.6%+/-8.73%, and 87.6%+/-11.48%, respectively. Differences between groups were statistically significant. The mean percentage of the reduced defect height and area was significantly smaller when there was spontaneous implant cover screw exposure. Single rather than multiple implant placement led to significantly better results. CONCLUSIONS: Timing of placement, number of simultaneously placed implants, and spontaneous implant exposure significantly influence clinical bone healing around maxillary implants placed together with augmentation procedures.