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Successful osseointegration is the result of a controlled foreign body reaction to dental implants. Osseointegrated implants have demonstrated excellent long-term survivability, although they may be subject to limited marginal bone loss. Marginal bone loss during the first few years after implant placement seldom represents disease, but is instead the result of an adaptive bone response to surgical trauma and implant loading. It is not uncommon for implants with early marginal bone loss to enter a long-lasting state of bone stability. Extensive bone resorption after the first year is generally due to an exacerbation of adverse body reactions caused by non-optimal implant components, adverse surgery or prosthodontics and/or compromised patient factors. Disease in the form of peri-implantitis is a late complication that affects some implants with suppuration and rapid loss of crestal bone, and is probably caused by bacterial pathogens and immunological reactions. Unfortunately, the literature is not consistent with respect to the type or magnitude of clinical implant problems, including how they are defined and diagnosed. If the peri-implantitis diagnosis is confined to cases with infection, suppuration and significant bone loss, the frequency of the disease is relatively low, which is in sharp contrast to the frequencies reported with unrealistic definitions of peri-implantitis. We suggest that when modern implants are placed by properly trained individuals, only 1-2% of implants show true peri-implantitis during follow-up periods of 10 years or more. Peri-implantitis must be separated from the initial and self-limiting marginal bone loss., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

In the 1960s and 1970s, implant-supported prostheses based on subperiosteal or blade implants had a poor reputation because of questionable clinical outcomes and lack of scientific documentation. The change to a scientifically sound discipline was initiated by the two scientific pioneers of modern implant dentistry, Professor P. I. Brånemark from the University of Gothenburg in Sweden and Professor André Schroeder from the University of Bern in Switzerland. Together with their teams, and independently of each other, they laid the foundation for the most significant development and paradigm shift in dental medicine. The present volume of Periodontology 2000 celebrates 50 years of osseointegration. It reviews the progress of implant therapy over the past 50 years, including the basics of implant surgery required to achieve osseointegration on a predictable basis and evolving innovations. The development of bone-augmentation techniques, such as guided bone regeneration and sinus floor elevation, to correct local bone defects at potential implant sites has increased the indications for implant therapy. The paradigm shift to moderately rough implant surfaces resulted in faster and enhanced bone integration and led to improvements in various treatment protocols, such as immediate and early implant placement in postextraction sites, and made various loading protocols possible, including immediate and early implant loading. In the past 15 years, preoperative analysis and presurgical planning improved as a result of the introduction of three-dimensional imaging techniques. Hereby, cone-beam computed tomography offers better image quality with reduced radiation exposure, when compared with dental computed tomography. This opened the door for digital planning and surgical modifications. Over the last 50 years this evolution has facilitated tremendous progress in esthetic outcomes with implant-supported prostheses and improved patient-centered outcomes. This volume of Periodontology 2000 also discusses the current trends and open questions of implant dentistry, such as the potential of digital implant dentistry in the surgical and prosthetic field, the trend for an increasing average age of implant patients and the related adaptations of treatment protocols, and the second attempt to establish ceramic implants using, this time, zirconia as the implant material. Finally, some of the hottest controversies are discussed, such as recent suggestions on bone integration being a potential foreign-body reaction and the evidence-based appraisal of the peri-implantitis debate., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Cell interactions, adherence, and osseointegration at the bone-implant interface can be directly influenced by the surface properties of the titanium implant., Purpose: To characterize osseointegration of Neoss® implants with conventional (control group) and hydrophilic (test group) surface treatments., Materials and Methods: Six Labrador dogs received Neoss implants with conventional and hydrophilic surfaces. The bone-implant interfaces were evaluated 1 and 4 weeks after implantation, and osseointegration was evaluated using histological, histomorphometric, fluorescence, and resonance frequency analyses. The surfaces were also subjected to topographic and hydrophilicity analyses., Results: The topographic analyses revealed increased surface roughness in the test group compared with the control group (surface area roughness 0.42 and 0.78 μm, respectively, for control and test group surfaces; p ≤ .05). The wettability values were higher in the test group (contact angles 67.2° and 27.2° for the control and test group surfaces, respectively; p ≤ .05). Implants in the test group also exhibited better stability, more bone-implant contact, and increased bone area compared with implants in the control group., Conclusion: Neoss implants in the test group improved bone formation in the early stages of osseointegration compared with implants in the control group., (© 2014 Wiley Periodicals, Inc.)

Background: Clinical studies have shown a higher degree of implant failures in grafted bone compared with normal nongrafted maxillary bone. Additionally, a prolonged time for integration of titanium implants in grafted block bone has been shown by means of resonance frequency analysis (RFA)., Purpose: The aim of this prospective study was to compare the stability of implants placed in particulate bone, onlay block bone, interpositional bone, and nongrafted maxillary bone during the early phase of osseointegration using RFA and implant failure., Material and Methods: Thirty-five patients with edentulism in the maxilla were included in the study. In all, 260 Astra Tech TiOblast implants (Astra Tech AB, Mölndal, Sweden) were installed. Twenty-five of these patients had severe maxillary atrophy and were treated with iliac bone grafts 5 to 6 months prior to implant placement, 19 with lateral onlay block grafts on one side (group A, 38 implants) and particulate bone for lateral augmentation on the other (group B, 38 implants). These 19 patients also got bilateral sinus floor augmentation with particulate bone (group C, 76 implants). Six patients had an unfavorable sagittal relation between the jaws and underwent a LeFort I operation with interpositional bone blocks grafted to the nasal and sinus floors (group D, 48 implants). The remaining 10 patients could be treated with implants without bone augmentation and served as control (group E, 60 implants). RFA was performed at implant placement and abutment connection 6 months later and an implant stability quotient (ISQ) value was given for each implant., Results: Four implants (1.5%) were found mobile at abutment connection and removed (two in group A and two in group D). RFA showed a slight increase in stability from installation to abutment connection but the differences were not statistically significant in any of the groups (Wilcoxon signed rank test for comparison of paired data). Implants installed in group D had a significantly lower ISQ value at both measurements compared with the other groups (Wilcoxon Rank Sum test for comparisons of independent samples, p = .05)., Conclusion: It is concluded that TiO(2)-blasted implants placed in nongrafted and grafted maxillary bone using a two-staged protocol show similar stability during the early phase of osseointegration. Patients reconstructed with interpositional bone graft after a LeFort I osteotomy showed lower implant stability values than nongrafted patients and other grafting techniques., (© 2010 Wiley Periodicals, Inc.)

Hypothesis: This experimental study was undertaken to test the hypothesis that a new design of craniofacial implant shows a stronger tissue response than the currently used implant., Materials and Methods: A total of 60 newly designed Cochlear Baha BI300 titanium implants (test) and 60 of the current design (control) were placed in the tibiae of 30 adult loop-eared rabbits. The new implant had the surface modified by blasting with TiO2 particles to give a moderately rough surface topography. The control implant had an as-machined surface. The animals were euthanized after 5, 14, or 28 days. The implants with surrounding bone tissue were retrieved for descriptive histology and morphometric measurements of bone-implant contacts (BICs)., Results: The test implants showed integration through bone formation direct on the surface and ingrowth from the vicinity. Conversely, the control implants showed increased BICs because of ingrowth of bone from the adjacent bone surfaces only. The test implant showed significantly more BICs at all time points., Conclusion: It is concluded that the new craniofacial implant with a moderately rough surface showed integration through a contact-osteogenesis pathway, whereas the smoother control surface was integrated by distance osteogenesis. More bone contacts were seen for test implants and, thus, a stronger bone tissue response compared with control implants. Biomechanical tests are needed to also evaluate the impact of the different histologic responses on implant stability.

Purpose: This randomized, controlled study was designed to compare bone formation around microimplants with a sandblasted, acid-etched surface placed at the time of maxillary sinus floor augmentation with a synthetic biphasic calcium phosphate (BCP) or deproteinized bovine bone (DBB)., Materials and Methods: Nine completely edentulous patients and two partially edentulous patients (six women, five men) with a mean age of 67 years (range, 50 to 79 years) requiring bilateral sinus augmentation were included in the study. The patients were randomized for augmentation with BCP (test) in one side and DBB (control) in the contralateral side. At the time of augmentation, one microimplant on each side was placed vertically from the top of the alveolar crest, penetrating the residual bone and the grafting material. After 8 months of graft healing, at the time of ordinary implant placement, all 22 microimplants were retrieved with a surrounding bone core for histologic analyses., Results: The bone-to-implant contact in the BCP group was 64.6% +/- 9.0%, versus 55.0% +/- 16.0% for the DBB group. The difference was not significant. The corresponding values for the area of newly formed bone in the biopsies were 41.1% +/- 9.8% and 41.6% +/- 14.0% for BCP and DBB, respectively. There were significantly more DBB particles in contact with newly formed bone than BCP particles (87.9 +/- 18.2% versus 53.9 +/- 26.1%; Wilcoxon rank sum test; P = .007)., Conclusion: In this randomized, controlled clinical trial, new bone formation and bone-to-implant contact around microimplants with a sandblasted, acid-etched surface was found to be equivalent between sinuses augmented with BCP or DBB. Significantly more DBB particles than BCP particles were in contact with newly formed bone, but the clinical relevance of this has yet to be established.

Background: The use of immediate/early implant loading protocols offers obvious advantages for the patient. Although well documented in the totally edentulous mandible, information about clinical outcomes from such protocols in the partially edentate maxilla is lacking., Purpose: The present study was conducted to clinically and radiographically evaluate a tapered implant design with an oxidized surface for immediate/early loading in the partially edentulous maxilla. The aim was also to correlate implant stability measurements using resonance frequency analysis (RFA) with implant diameter and length, bone quality and quantity, and marginal bone levels and marginal bone loss., Materials and Methods: A total of 32 patients with a need of implant treatment in their partially edentulous maxilla were included in the study. A total of 53 Replace Select TiUnite implants (Nobel Biocare AB, Göteborg, Sweden) were used in the study; 16 for single tooth replacements in 16 patients and 37 implants for partial bridges in another 16 patients. The single tooth replacements were loaded the same day with a temporary crown, while permanent partial bridges were delivered within 16 days. Intraoral radiographs were taken at surgery and after 1 year for marginal bone measurements. RFA measurements were performed at baseline and after 3, 6, and 12 months., Results: One implant used for a single tooth replacement failed, giving an overall survival rate of 98.1% after 1 year. On average, 1.1 mm (SD 1.0) bone was lost during 1 year; 1.5 mm (SD 1.0) in single tooth and 0.9 mm (SD 1.0) in partial cases. The implant stability increased with time from 63.3 implant stability quotient (ISQ) (SD 6.1) at baseline to 64.3 (SD 5.3), 65.0 (SD 4.6), and 66.8 (SD 5.6) after 3, 6, and 12 months, respectively. The average change from baseline to 1 year was 3.3 ISQ (SD 5.0) and was statistically significant (p < .05). There was no difference between single and partial cases. Implant stability correlated with bone quantity and quality at implant sites, but not with marginal bone level measurements., Conclusions: It is concluded that immediate/early loading can be used in the partially edentulous maxilla with good clinical and radiographic short-term outcomes. Implant stability at placement correlated with bone quantity and quality, and increased with time as measured with RFA, indicating a favorable bone tissue response to the loaded implants. Any correlations between RFA and marginal bone level measurements were not observed in the present study.

Background: Clinical studies show promising outcomes with implants inserted at the time of extraction. However, this often results in an initial bone defect at the marginal region which preferably should heal for an optimal function. Therefore, monitoring of these implants is vital., Purposes: The aims of this study were to determine the initial stability of implants placed into fresh extraction sockets, and to explore the correlations between the peri-implant bone levels and implant stability parameters., Materials and Methods: Six human cadaver mandibles including all natural teeth were selected for this study. All natural teeth were gently extracted, and 84 implants were immediately placed into fresh extraction sockets with five different implant depths. The maximum insertion torque values were recorded, and primary implant stability measurements were performed by means of resonance frequency analysis (RFA). The vertical distance between implant/abutment junction and the first bone-implant contact was recorded using a periodontal probe., Results: It was found that the insertion torque and RFA were 28.9 +/- 7 Ncm and 65.6 +/- 9 implant stability quotient (ISQ), respectively, for 420 measurements from all 84 implants. Statistically significant correlation was found between insertion torque and ISQ values (r = 0.86; p < .001) for all implants. Both insertion torque and ISQ values dramatically decreased when the amount of peri-implant vertical bone defect increased., Conclusion: The results of this study demonstrated a linear relationship between peri-implant vertical bone defect depth and RFA value. It is proposed that the RFA method is sensitive to detect changes of the marginal bone level and may be used to monitor healing of peri-implant bone defects.

Background: Previous studies have shown the formation of more bone contacts with a moderately rough and porous titanium surface, created by anodic oxidation, as compared with nonmodified turned titanium control surfaces. The mechanisms leading to a stronger bone response to oxidized titanium are not well understood., Purpose: The aim of the study was to describe the early events of bone integration of titanium implants with oxidized and turned surfaces., Materials and Methods: Nine adult New Zealand White rabbits and 18 implants were used in the study. One oxidized and one turned threaded titanium implants, which had been placed in the right tibial metaphysis, were analyzed in the present study. The implants were retrieved after 7, 14, and 28 days for light microscopic examination and histomorphometric measurements in ground sections., Results: Integration of oxidized implants was seen to occur as direct bone formation on the surface, while the integration of turned implants was a result of bone ingrowth from preexisting bone and bone marrow. For oxidized implants, an almost acellular, darkly stained layer was seen after 7 to 14 days, which later became populated with osteoblasts. The presence of osteoid seams indicated appositional bone growth from the substrate toward the surrounding tissues. The bone contact values were higher for oxidized implants, and the bone area values were higher for turned implants., Conclusions: The present study confirms the idea that implant surface modification alters the bone tissue response to titanium. The early bone formation following surgery occurs directly on the moderately rough oxidized surface, while turned titanium surfaces are integrated by the ingrowth of bone from the adjacent bone marrow and preexisting bone tissues.

Objectives: To investigate the presence and composition of residual bone graft substitute material in bone biopsies from the maxillary sinus of human subjects, following augmentation with calcium sulphate (CaS)., Material and Methods: Bone cores were harvested from the maxillary sinus of patients who had undergone a sinus lift procedure using CaS G170 granules 4 months after the initial surgery. Samples from seven patients, which contained residual biomaterial particles, were examined by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy was used to determine the composition of the remaining bone graft substitute material., Results: Residual graft material occurred in isolated areas surrounded by bone and consisted of individual particles up to 1 mm in length and smaller spherical granules. On the basis of 187 separate point analyses, the residual material was divided into three categories (A, B and C) consisting of: A, mainly CaS (S/P atomic% ratio > or =2.41); B, a heterogeneous mixture of CaS and calcium phosphate (S/P=0.11-2.4) and C, mainly calcium phosphate (S/P< or =0.11; C), which had a mean Ca : P ratio of 1.63+/-0.2, consistent with Ca-deficient hydroxyapatite. Linescans and elemental maps showed that type C material was present in areas which appeared dense and surrounded, or were adjacent to, more granular CaS-containing material, and also occurred as spherical particles. The latter could be disintegrating calcium phosphate in the final stages of the resorption process., Conclusions: CaS resorption in the human maxillary sinus is accompanied by CaP precipitation which may contribute to its biocompatibility and rapid replacement by bone.

Objective: Compounds considered for drug delivery from oral implant surfaces in support of local bone formation might themselves influence osseointegration. Phosphorylcholine (PC) polymers have been shown to enhance the biocompatibility of medical devices and to serve as drug delivery systems. The objective of this study was to evaluate local bone formation and osseointegration at PC and positively charged PC (PC+)-coated endosseous implants in an established rabbit model., Material and Methods: Sixteen adult female New Zealand White rabbits were used. Eight animals received PC-coated and control titanium porous oxide surface implants placed in the left and right distal femural condyle (trabecular bone) and proximal tibial metaphysis (cortical bone) using aseptic routines. The remaining eight animals similarly received PC+ and control implants. One implant was placed in each femural condyle and two implants in each tibial metaphysis. Experimental and control implants were alternated between the left and right hind legs. Fascia and skin were closed in layers. The animals were euthanized following a 6-week healing interval for biomechanical (removal torque) and histometric analyses., Results: Peri-implant bone density was considerably greater at tibial compared with femoral sites within as well as immediately outside the implant threads. However, there were no significant differences in bone density among PC, PC+, and control implants. Nevertheless, bone-implant contact was significantly lower at PC compared with PC+ and control implants in cortical bone (p<0.05). Numerical differences in trabecular bone did not reach statistical significance. The removal torque evaluation revealed significantly lower values for PC compared with PC+ and control sites (p<0.05)., Conclusion: The histometric and biomechanical analyses suggest that PC coating may influence biological processes and ultimately osseointegration of endosseous implants. Apparently, incorporation of cationic charges may reverse or compensate for this scenario. Nevertheless, both PC coatings exhibited clinically acceptable osseointegration. In perspective, PC technology appears to be a viable candidate delivery system for agents in support of local bone formation at endosseous implant surfaces.

Objectives: The aim of this study was to compare the performance of two non-splinted implants used as retention for a mandibular overdenture when applying conventional or early loading protocols., Material and Methods: Twenty edentulous patients were treated with two unsplinted and non-submerged implants (15 mm long, TiUnite RP, Brånemark System) in the anterior mandible. The patients were randomly allotted into two groups: (i) test group (Group A), in which the overdenture was connected 1 week after surgery, and (ii) control group (Group B), in which the overdenture was connected after 12 weeks of healing. Resonance frequency analyses (RFA) for implant stability measurements were performed at implant surgery and after 1, 3, 6, 9 and 12 months. Marginal bone levels were evaluated at implant surgery and after 6 and 12 months., Results: No implant from either group was lost and all implants showed less than 1 mm of marginal bone resorption during the first year. The mean implant stability quotient (ISQ) values at implant surgery were 76.2+/-2.8 for Group A and 75.6+/-4.5 for Group B. The 12-month measurements showed 76.4+/-2.5 ISQ and 76.4+/-2.8 ISQ for Groups A and B, respectively. There were no statistically significant changes between or within the groups with time. There were no differences in marginal bone loss, which was on average 0.3 mm for both groups after 1 year., Conclusion: Although a limited number of patients were followed for 1 year only, the results of the present study indicate that early loading of two unsplinted 15 mm long implants with an overdenture does not negatively affect implant stability or marginal bone conditions when compared with implants subjected to 12 weeks of healing before loading.

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, 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.

Background: Studies indicate that implants placed at the time of extraction have high success rates. Implants must be stable at the time of insertion. Presently there are no data indicating the degree of implant stability when implants are placed at the time of extraction. This study evaluated changes in stability of implants from implant placement to abutment connection utilizing resonance frequency analysis (RFA). The unit of measurement was the international stability quotient (ISQ)., Methods: Prior to treatment, patients were given medical history and dental evaluations. Periapical and panogram radiographs were taken. Fifty-two patients requiring extraction of one or two teeth and implant placement immediately after extraction were enrolled in this study. Under conscious sedation and local anesthesia or local anesthesia alone, teeth were atraumatically removed and the extraction sockets were debrided. A total of 73 dental implants (57 in the maxilla, 16 in the mandible) were placed. Using a one-stage approach, all implants were placed within the patient's alveolar envelope and were never placed directly into extraction sockets. All implants were placed into contained extraction sites. Bone augmentation procedures were not performed. After implant insertion, the RFA electronic transducer was attached to the head of the implant with the retaining screw. The device was attached to a computer designed to register RFA scores in ISQ units. RFA measurements were taken at implant placement and abutment connection. Bone qualities, quantity, implant length and width as well as site of placement were recorded., Results: The average interval between implant insertion and abutment connection was 5.6 months (SD 2.05). Two implants were lost between implant insertion and 1 year. At 2 to 3 years, the cumulative survival was 97.2%. Resonance frequency measurements at implant placement showed a mean primary stability of 62.0 (SE 1.1; range 43 to 83 ISQ) and a mean secondary stability after 1 year of 64.0 (SE 1.2; range 40 to 98 ISQ) for all implants. The increase was marginally significant (generalized estimating equation z-statistic = 1.79; P value = 0.07)., Conclusions: Implants placed at the time of extraction and inserted into native bone and not directly into extractions sockets have a high degree of initial stability as evidenced by RFA measurements. Implants with initial high ISQ levels revealed a slight drop in levels over time, while implants with levels lower than 60 had increases in levels between implant insertion and abutment connection. At 2 to 3 years the cumulative survival rate was 97.2%.

Background: The influence of thread design at the millimeter level and surface topography at the micrometer level on bone integration and the stability of dental implants have been studied extensively. However, less is known about the influence of implant structures in the range of 50 to 200 microm., Purpose: The present in vivo investigation was undertaken to study if bone formation and implant stability were influenced by 110 (S1) and 200 (S3) microm-wide and 70 microm-deep grooves positioned at a thread flank of oxidized titanium implants., Materials and Methods: Eighteen rabbits and oxidized titanium implants (3.75 mm in diameter and 7 mm long) were used in the study. Nine rabbits received three control implants and three test implants with a 110 microm-wide groove added to one thread flank. The remaining nine rabbits received three control implants and three test implants with a 200 microm-wide groove. The animals were followed for 6 weeks. Removal torque (RTQ) tests were applied to two of the implants in each leg. The remaining implant per leg was retrieved for histology. The degree of bone fill within the grooves and corresponding bone formation at the opposing surfaces, the bone area within the threads, and the degree of bone-implant contact were calculated for each implant., Results: The histologic analyses revealed an affinity for bone formation within the grooves. The RTQ tests showed that the peak RTQ was approximately 30% higher for the S1 implants compared with control implants without a groove. The difference was statistically significant (p < .05) for tibial and pooled implants. A similar but smaller and not statistically significant effect, approximately 8%, was measured for the S3 implants. The histomorphometric measurements confirmed the observed affinity of bone for the grooves. For S1 implants, 78.7 +/- 15.8% of the grooves were filled with bone, whereas only 46.2 +/- 27% of the corresponding flank surface showed the presence of bone (p < .05). The corresponding figures for S3 and control implants were 72.7 +/- 25.1% and 48.5 +/- 13.6%, respectively (p < .05). The degrees of bone-implant contact and bone area within the threads were similar for test and control implants., Conclusion: It is concluded that 110 and 200 microm-wide and 70 microm-deep grooves at oxidized implant surfaces stimulated bone to preferentially form within and along the groove in the rabbit model. The 110 microm-wide groove was shown to increase the resistance to shear forces significantly. It is suggested that implants with such a groove may be one way to optimize implant stability in suboptimal clinical conditions.

Background: Surface modification of titanium implants by anodic oxidation may lead to enhanced bone integration. For instance, in vivo studies have demonstrated formation of more bone contacts in less time than for turned control implants. In addition, oxidized implants have shown a higher resistance to torque forces, indicating a strong interlock between bone and the oxide layer. However, the structure of the oxidized titanium-bone interface in high resolution is not known., Purpose: The aim of the study was to analyze the human bone-oxidized titanium interface at a high-resolution level. Of particular interest was the relationship between bone tissue and the pores of the surface oxide., Materials and Methods: Twelve clinically retrieved implants with an oxidized surface (TiUnite, Nobel Biocare AB, Göteborg, Sweden) were used. Seven were regular dental implants and five were experimental mini-implants and had been subjected to immediate, early, or no loading. They were retrieved after 5 to 9 months of healing and were processed and analyzed using light microscopy, scanning electron microscopy (SEM) in normal and back-scatter (BS-SEM) modes, and energy-dispersive x-ray (EDX) analysis techniques., Results: Bone formation was observed to occur from adjacent bone structures toward the implant surface, and it was evident that bone formation had occurred at the implant surface. SEM, BS-SEM, and EDX revealed that mineralized bone had grown into the pores of the surface oxide layer, including pores with small diameters (< 2 microm)., Conclusions: The clinically retrieved oxidized implants showed evidence of bone growth into the pores of the surface oxide layer. The findings indicate the establishment of a strong interlock between the bone and the oxidized titanium implant, which is suggested to be beneficial for clinical performance.

Background: Histologic studies have demonstrated the possibility to reestablish direct bone-implant contacts after ligature-induced periimplantitis. The influence of the reosseointegration on the stability of implants is not known., Purpose: The aim of the present investigation was to study bone tissue and associated implant stability alterations that occurred during induction and resolution of periimplantitis using resonance frequency analysis (RFA), radiography, and histology., Materials and Methods: Three implants with smooth (turned) or roughened (SLA) surfaces were placed in each side of the edentulous mandible of four dogs. Experimental periimplantitis was induced for 3 months. Five weeks later, the animals were treated with antibiotics and surgical therapy and were followed for another 6 months. Periapical radiographs and RFA were used to evaluate marginal bone levels and implant stability throughout the study period. After termination, the tissue-implant interface was evaluated by light microscopy in ground sections., Results: There was a linear relationship between radiographic and RFA findings because continuous loss of marginal bone and a decrease in implant stability were observed for both implant surfaces during the periimplantitis period. Antibiotic treatment and surgical therapy resulted in some reosseointegration, which was more marked for the SLA surface. The resonance frequency values corresponded well to the histometric measurements because reosseointegration resulted in an increase in implant stability., Conclusions: The findings from the present study indicate a linear relationship between marginal bone level and resonance frequency value. It is suggested that the RFA technique is sensitive and may be used to detect even a minor change in the level of bone-implant contact.

Background: Zirconia ceramics are biocompatible and have mechanical properties that make them suitable as materials for dental implants. Little is known about how surface modification influences the stability and bone tissue response to zirconia implants., Purpose: The objective of the investigation was to histologically and biomechanically evaluate the bone tissue response to zirconia implants with two different surface modifications in comparison with machined, nonmodified zirconia implants and oxidized titanium implants., Materials and Methods: Threaded zirconia implants with a diameter of 3.75 mm with either a machined surface (Zr-Ctr) or one of two surface modifications (Zr-A and Zr-B) were manufactured. Oxidized titanium (Ti-Ox) implants 3.75 mm in diameter were also used. The implants were characterized with regard to surface topography using an interferometer. Twelve rabbits received 96 implants using a rotational scheme, two in each tibia and two in each femur. The implants in six rabbits were subjected to removal torque (RTQ) tests after a healing period of 6 weeks. The implants in the remaining six animals were removed en bloc for light microscopic analysis. Back-scatter scanning electron microscopic (BS-SEM) analyses were used to evaluate the state of the bone-implant interface at the modified zirconia implants after RTQ testing., Results: The Ti-Ox and Zr-A implants showed the highest surface roughness, followed by the Zr-B implants and, finally, the Zr-Ctr implants. The nonmodified ZrO2 implants showed statistically significant lower RTQs than all other implants. No significant differences in bone-implant contact or bone area filling the threads were observed. BS-SEM showed intact surface layers of the surface-modified implants after RTQ testing and revealed fracture of the interface bone rather than a separation., Conclusion: The present study showed a strong bone tissue response to surface-modified zirconia implants after 6 weeks of healing in rabbit bone. The modified zirconia implants showed a resistance to torque forces similar to that of oxidized implants and a four- to fivefold increase compared with machined zirconia implants. The findings suggest that surface-modified zirconia implants can reach firm stability in bone.

Background: An increased number of publications report that one-stage surgery and immediate/early loading of dental implants may be a feasible approach for prosthetic reconstruction of the edentate patient. However, little is known about the histologic response to implants subjected to immediate/early loading in patients., Purpose: The aim of the present study was to histologically evaluate oxidized titanium implants subjected to loading immediately following surgery or after 2 months of healing and removed after 5 to 9 months loading., Materials and Methods: Five patients participated in the study; each had consulted for implant treatment in the posterior mandible and subsequently volunteered to have extra implants inserted for the purpose of histologic research. Nine oxidized titanium implants (Brånemark System TiUnite , Nobel Biocare AB, Gothenburg, Sweden) were retrieved after 5 to 9 months in function. Two implants had been loaded the same day, whereas seven implants were loaded after 2 months of healing. Resonance frequency analysis was performed at retrieval on seven implants. Ground sections were prepared for histology and analyzed using light microscopic morphometry., Results: Seven and 8.5 mm implants were placed, predominantly in quality 3 and 4 bone. Four implants were straight (Mk III), and five were tapered (Mk IV). All implants were clinically stable at retrieval and showed ISQ values of 65 to 79 with a mean of 71.4 +/- 4.4. Eight of the implants were able to be used for histology. A gross histologic examination showed an undisturbed healing of soft and bone tissues with no apparent differences between response to immediately and early loaded implants. Lamellar bone surrounded the implants, and remodeling was evident and more marked near the implant surface. A condensation of bone toward the implant surface was seen; this resulted in a lamina dura-like structure in trabecular bone. Thin rims of newly formed bone were often seen following the contour of the implant surface. The morphometric measurements showed a mean bone-to-implant contact value of 84.2 +/- 10.5% and a mean bone area value of 79.1 +/- 6.8%. The two immediately loaded implants showed bone-to-implant contact and bone area values of 92.9 +/- 0.1% and 84.9 +/- 0.9%, respectively. The corresponding values for the six early loaded implants were 81.4 +/- 10.6% and 77.1 +/- 6.8%, respectively., Conclusions: The present study demonstrated that oxidized implants subjected to immediate or early loading do integrate with soft and bone tissues in the posterior mandible.

Purpose: This study was designed to clinically and histologically evaluate the integration of titanium implants in different grafting materials used for maxillary sinus augmentation procedures., Materials and Methods: A total of 21 patients and 36 maxillary sinuses were augmented with (1) autogenous particulated bone from the mandibular ramus, (2) bovine hydroxyapatite (BH) with membrane coverage, or (3) an 80/20 mixture of BH and autogenous bone. The grafts were allowed to heal for 6 to 9 months prior to placement of microimplants for histology and standard implants for prosthetic rehabilitation. After another 6 months of healing, when abutments were connected, the microimplants were retrieved for histologic and morphometric analyses. The outcome of the standard implants was clinically evaluated after 1 year of loading., Results: The mean bone-implant contact was 34.6 +/- 9.5%, 54.3 +/- 33.1%, and 31.6 +/- 19.1% for autogenous bone, mixture of 20% autogenous bone/80% BH, and 100% BH, respectively. The corresponding values for the bone area parameter were 37.7 +/- 31.3%, 39.9 +/- 8%, and 41.7 +/- 26.6%. The BH area was found to be 12.3 +/- 8.5% and 11.8 +/- 3.6% for 20% autogenous bone/80% BH and 100% BH, respectively. There were no statistically significant differences for any parameter between any of the groups. After 1 year of loading, 6 of the 33 implants placed in autogenous bone grafts, 2 of the 35 implants placed in the BH/autogenous bone mixture, and 2 of 43 implants placed in BH were lost. There were no statistically significant differences between any of the groups., Discussion: The histomorphometric analysis showed no differences between the 3 groups, indicating that autogenous bone graft can be substituted with bovine hydroxyapatite to 80% or 100% when used for maxillary sinus floor augmentation. The effect of adding autogenous bone remains unclear but may allow for a reduction of the healing time., Conclusion: The results from this clinical and histologic study indicate that similar short-term results can be expected when using autogenous bone, BH, or a mixture of them for maxillary sinus floor augmentation and delayed placement of dental implants.

Background: Implants are placed in either one or two stages. There is an absence of histologic human evidence relating to implant integration after loading., Purpose: The purpose of this case report was to present clinical and histologic findings for smooth-surfaced titanium turned microimplants placed in one stage and loaded after healing., Materials and Methods: Five one-piece microimplants were placed in a fully edentulous mandible. Three microimplants (tests) were placed in one stage and extended through the keratinized mucosa for 3 mm. Two additional microimplants (controls) were placed even with the mucosa. After 3 months of healing, three test implants were loaded for an additional 3 months. At this time, three loaded implants and one control were removed en bloc., Results: Histologic and histometric evaluations were made. For all specimens, there was excellent bone-to-implant contact. The loaded implants had from two to four exposed threads. Using marginal bone levels as the reference, the highest percentage of bone-to-implant contact was noted with the unloaded control implant (92.2%). One nonaxially loaded implant had 66.9% bone-to-implant contact, whereas the axially loaded implants (n = 2) had 77.8% bone-to-implant contact., Conclusions: Within the limits of this case report, smooth-surfaced, titanium threaded microimplants placed in one stage and loaded for 3 months demonstrated excellent osseointegration, with varying bone-to-implant contact. The amount of bone-to-implant contact may be related to axial implant loading.

Purpose: To analyze the bone graft-implant interface of titanium microimplants (MIs) placed at the time of bone grafting or after a healing period of 6 months and retrieved after another 6 to 14 months of healing. Integration of MIs placed in interpositional bone grafts (IBGs) in conjunction with a Le Fort I osteotomy was compared with the integration of those placed in onlay/inlay bone grafts (OBGs). Materials and Methods: The severely atrophied edentulous maxillae of 23 patients (14 women, 9 men) were restored with autogenous bone grafts (either IBG [n = 8] or OBG [n = 15]) and titanium implants. Six-month periods were allowed between grafting, implant placement, and abutment connection. The bone-implant interface was studied histologically with the use of unloaded titanium MIs. Results: Sixty-eight MIs were either (1) placed simultaneously with grafting and retrieved after 6, 12, or 14 months or (2) placed after 6 months of healing and retrieved after another 6 to 8 months. Histomorphometry indicated equal degrees of osseointegration for the 2 intraoral reconstruction techniques when looking at bone-implant contact, bone area in threads, and newly formed bone (NFB) (Student t test for unpaired observations). There was a significant difference between simultaneous and delayed implant placement with respect to BIC and NFB (Student t test for paired observations). Three additional MIs placed in the nongrafted residual alveolar ridge and retrieved after 6 months showed significantly more bone in threads and NFB (Student t test for paired observations; P = .003 and P = .009, respectively) compared to MIs placed at graft placement (6 months' healing). Discussion: Timing of implant placement appeared more important than healing time or surgical technique. The delayed approach resulted in better implant integration, probably because of the initial revascularization of the graft. Conclusions: Implant integration was similar in the IBG and OBG groups. Placement of MIs after an initial healing period of 6 months resulted in better integration than placement simultaneously with grafting. [ABSTRACT FROM AUTHOR]

Sixty-seven patients ranging in age from 16 to 86 years were included in this 3- to 5-year retrospective report focusing on implant survival and marginal bone remodeling in relation to implant diameter. A total of 299 Brånemark implants (3.75-mm diameter: 141; 4.0-mm diameter: 61; 5.0-mm diameter: 97) were placed in 16 completely and 51 partially edentulous arches. Seven of the 141 implants in the 3.75-mm-diameter group failed (5%). The corresponding value for the 4.0-mm-wide implants was 2 of 61 (3%). The highest failure rate, 18% (17/97), was seen for the 5.0-mm-diameter implants. The least favorable cumulative survival rates were seen in mandibles after 5 years and involving 4.0-mm- and 5.0-mm- diameter implants (84.8% and 73.0%, respectively). The marginal bone loss was generally low over the 5-year period. When the data were evaluated by the Cox regression analysis, a relationship was found between implant failure and implant diameter (P < .05), with a higher failure rate for the 5.0-mm-diameter implant. However, no relationship could be seen between implant failure and jaw type, or bone quality and quantity (P > .05). Neither was any relationship seen between marginal bone loss and bone quality and quantity, implant diameter, or jaw type when tested by multiple linear regression analysis (P > .05). A learning curve, poor bone quality, and changed implant design were suggested as possible reasons for the less positive outcome seen for the 5.0-mm-diameter implant. The fact that this implant was often used as a rescue implant when the standard ones were not considered suitable or did not reach initial stability was another plausible explanation. [ABSTRACT FROM AUTHOR]

Purpose: The Periotest is an electronic instrument that has been advocated for the measurement of implant stability and osseointegration. The aims of this investigation were to establish the relationship between contact time and PTV values when the Periotest was used to assess implants in vivo and in vitro, and to investigate the influence of the striking height of the Periotest handpiece and the length of implant abutment. Materials and Methods: The accelerometer signal from a Periotest was captured and compared with the resulting PTV value. In vitro measurements of PTV and contact time were performed on a 3-mm abutment that had been attached to a 15-mm implant luted into an aluminium block, and were repeated on a patient in vivo. Further measurements were made of the abutments of six implants in turn in the maxilla of the same patient. The standard abutment lengths on the implants were 3, 4 (× 2), 5.5 (× 2), and 7 mm. Results: The results indicated that there was a linear relationship between contact time and PTV value for implants measured in vitro and in vivo. Greater scatter of the in vivo data was attributed to test and patient variables including striking position, distance, and damping as a result of the presence of soft tissues. There was a linear relationship between the PTV value and the striking height for implant measurements in vivo and in vitro. Conclusion: It can be concluded that the sensitivity of the Periotest to clinical variables including striking height and handpiece angulation limit the application of the instrument as a clinical diagnostic aid to measure implant stability. [ABSTRACT FROM AUTHOR]

The term osseointegration is analyzed in relation to its theoretical and clinical definitions, and comparisons are made to other implant modalities. The term osseointegration has a clear clinical meaning, but there is doubt about its precise usage in an experimental setting. Clinically, an implant can be described as osseointegrated if there is no discernable movement when force is applied to the fixture. This is in contrast to implants surrounded by fibrous connective tissue, which move within soft tissue. Newly developed laboratory techniques may be used in the future to precisely characterize osseointegration in the laboratory. [ABSTRACT FROM AUTHOR]

In this study, a new approach involving placement and subsequent retrieval of titanium microimplants was employed for the histologic investigation of the implant-tissue interface in conjunction with maxillary sinus floor augmentation. Nine patients scheduled for sinus floor augmentation and simultaneous placement of Brånemark implants were included in the study. After a sinus graft procedure and placement of implants, an additional microimplant was placed into the graft through the lateral wall of the sinus. At abutment connection, the microimplants were retrieved using a 3- or 5-mm-wide trephine drill. Six specimens were retrieved after 6 to 14 months from sites augmented with particulate radiated mineralized cancellous allograft. Another six implants were retrieved after 6 to 12 months from maxillary sinuses augmented with particulate autogenous bone grafts. The histologic analysis showed distinct differences between the two types of grafts. The sites with autogenous bone grafts displayed a normal morphology of bone and bone marrow, including formation of bone on the surfaces of the grafted particles and remodeling of newly formed as well as grafted bone. The bone was more mature after 11 to 14 months than at 6 months. The allografted sites had a mixed morphologic appearance of newly formed bone and nonviable allograft particles (about 75% of the total bone area) in loose connective tissue. Significantly more bone was found at the autografted than at the allografted implants. The use of autogenous bone for augmentation of the maxillary sinus floor resulted in a greater amount of viable bone surrounding the implant; however, simultaneous placement of implants apparently resulted in a low proportion of bone-implant contact after 6 to 14 months irrespective of graft type. [ABSTRACT FROM AUTHOR]

The purpose of this retrospective clinical investigation was to study possible soft tissue complications and marginal bone resorption related to exposed threads of osseointegrated Brånemark oral implants during a 5-year period. Group 1 comprised 27 patients with 38 test implants that had not become completely covered with bone at implant placement. Thirty control implants in 25 of the patients were each next to a test implant and had no exposed threads initially. Group 2 comprised 51 patients with 107 test implants that had developed marginal bone loss beyond the second thread, as judged radiographically at the first annual checkup. Forty-eight control implants showed no or minor marginal bone resorption up to the first thread. Initial marginal defects and fenestrations at Brånemark implants (group 1) did not lead to mucosal problems or progressive marginal bone resorption during the first 5 years of function. Moreover, bone resorption, seen after the first year of loading at initially completely bone-covered implants, did not lead to any specific soft tissue problems, nor did it result in any further progressive bone resorption during a subsequent 4-year period. Based on the observed low incidence of soft tissue pathology at implants with exposed threads, it is suggested that bone augmentation techniques in the situations studied be used with restriction. [ABSTRACT FROM AUTHOR]

The article gives information about an international study group's meeting to review research literature on peri-implant gingivitis and marginal bone loss around dental implants, the maintenance of osseointegration in denture patients, and the progressive deterioration of the mouth's hard and soft tissue in the mouth. It is noted that the symposium was funded by five implant manufacturers.

Several letters to the editor are presented in response to articles in previous issues including "Direct Bone Anchorage of Oral Implants: Clinical and Experimental Considerations of the Concept of Osseointegration," by Tomas Albrektsson and Lars Sennerby in the January/February 1990 issue and a response Albektsson and Sennerby to a letter to the editor about their article "Direct Bone Anchorage of Oral Implants: Clinical and Experimental Considerations of the Concept of Osseointegration."

Background. Hydrophilic and moderately rough implant surfaces have been proposed to enhance the osseointegration response. Aim. The aim of this study was to compare early changes of stability for two implants with identical macrodesign but with different surface topographies. Materials and Methods. In 11 patients, a total of 22 implants (11 bimodal (minimally rough, control) and 11 proactive (moderately rough and hydrophilic, test), Neoss Ltd., Harrogate, UK) were immediately placed into fresh extraction sockets and immediately loaded. The peak insertion torque (IT) was measured in Ncm at placement. Resonance Frequency Analysis (RFA) measurements were made at baseline and 2, 4, 6, and 12 weeks after surgery. Results. The two implant types showed similar IT and RFA values at placement (NS). A dip of RFA values after 2 weeks followed by an increase was observed, where the test implant showed a less pronounced decrease and a more rapid recovery than the control implant. The test implants were significantly more stable than the control ones after 12 weeks. Conclusions. The results from the present study indicated that the hydrophilic and rougher test implant was more resistant to immediate loading and showed a significantly higher stability than the smoother control implant after 12 weeks. [ABSTRACT FROM AUTHOR]

Background Cell interactions, adherence, and osseointegration at the bone-implant interface can be directly influenced by the surface properties of the titanium implant. Purpose To characterize osseointegration of Neoss® implants with conventional (control group) and hydrophilic (test group) surface treatments. Materials and Methods Six Labrador dogs received Neoss implants with conventional and hydrophilic surfaces. The bone-implant interfaces were evaluated 1 and 4 weeks after implantation, and osseointegration was evaluated using histological, histomorphometric, fluorescence, and resonance frequency analyses. The surfaces were also subjected to topographic and hydrophilicity analyses. Results The topographic analyses revealed increased surface roughness in the test group compared with the control group (surface area roughness 0.42 and 0.78 μm, respectively, for control and test group surfaces; p ≤ .05). The wettability values were higher in the test group (contact angles 67.2° and 27.2° for the control and test group surfaces, respectively; p ≤ .05). Implants in the test group also exhibited better stability, more bone-implant contact, and increased bone area compared with implants in the control group. Conclusion Neoss implants in the test group improved bone formation in the early stages of osseointegration compared with implants in the control group. [ABSTRACT FROM AUTHOR]

Background When a foreign body is placed in bone or soft tissue, an inflammatory reaction inevitably develops. Hence, osseointegration is but a foreign body response to the implant, which according to classic pathology is a chronic inflammatory response and characterized by bone embedding/separation of the implant from the body. Purpose The aim of this paper is to suggest an alternative way of looking at the reason for marginal bone loss as a complication to treatment rather than a disease process. Materials and Methods The present paper is authored as a narrative review contribution. Results The implant-enveloping bone has sparse blood circulation and is lacking proper innervation in clear contrast to natural teeth that are anchored in bone by a periodontal ligament rich in blood vessels and nerves. Fortunately, a balanced, steady state situation of the inevitable foreign body response will be established for the great majority of implants, seen as maintained osseointegration with no or only very little marginal bone loss. Marginal bone resorption around the implant is the result of different tissue reactions coupled to the foreign body response and is not primarily related to biofilm-mediated infectious processes as in the pathogenesis of periodontitis around teeth. This means that initial marginal bone resorption around implants represents a reaction to treatment and is not at all a disease process. There is clear evidence that the initial foreign body response to the implant can be sustained and aggravated by various factors related to implant hardware, patient characteristics, surgical and/or prosthodontic mishaps, which may lead to significant marginal bone loss and possibly to implant failure. Admittedly, once severe marginal bone loss has developed, a secondary biofilm-mediated infection may follow as a complication to the already established bone loss. Conclusions The present authors regard researchers seeing marginal bone loss as a periodontitis-like disease to be on the wrong track; the onset of marginal bone loss around oral implants depends in reality on a dis-balanced foreign body response. [ABSTRACT FROM AUTHOR]

ABSTRACT Background: Maxillary sinus floor augmentation is a procedure that is indicated in cases when the volume of the posterior maxillary bone is inadequate. The goal of this treatment is to obtain sufficient amount of bone tissue in order to gain osseointegration of endosseous implants. Purpose: The purpose of this study was to conduct a clinical and histological analysis of calcium sulfate (CaS) as bone graft substitute in sinus floor augmentation. Material and Methods: Ten patients with edentulous maxillas were included in this study. They had moderate to severe atrophy of the posterior maxilla. Surgiplaster (Classimplant®, Rome, Italy) was used as graft material in the maxillary sinus and was covered by BioGide® (Geistlish Pharmaceutical, Wolhusen, Switzerland). After 4 months of graft healing, 40 dental implants were placed and a biopsy for histomorphometry was taken at these occasions. The specimens were viewed by light microscope, and the extent of bone regeneration and remaining graft material was evaluated. Radiographs were taken at the time of sinus augmentation and after 4 months of graft healing. Results: At the time of abutment surgery, one implant was considered as a failure and was consequently removed, giving a survival rate of 97.5% after 1 year of loading. Radiographs showed a mean of 26.5% shrinkage of the augmented area. A significant resorption of CaS was noted with a mean value of 8.8% of remaining graft material after 4 months of healing. The biopsies also revealed new bone formation with a mean value of 21.2% of the total biopsy area. Histology showed signs of an acellular substitution of CaS with bone-like tissue. Conclusion: The results of this study show that new bone regeneration occurs in the maxillary sinus after augmentation with CaS. This enabled successful placement, integration, and loading of dental implants in the posterior maxilla, as only 1 of 40 implants was lost during 1 year of follow-up. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article discusses the development, clinical and histological evaluation of a new clinical technique involving the augmentation of the maxillary sinus floor, which does not include bone grafting. It emphasizes that the elevation of the maxillary sinus membrane as well as the placement of dental implants lead in bone formation and osseointegration. It highlights that the surface-modified implants reveal a stronger bone response.

Background: Flapless surgery requires penetration of the alveolar mucosa and bone without reflection of mucoperiosteal flaps. Do these techniques force gingival tissue or foreign materials into osteotomies? If so, do such tissues or materials interfere with osseointegration? A proof-of-principle study using a canine model attempted to answer these questions. Methods: Five young adult Hound Labrador mongrel dogs received implants with a moderately roughened surface by anodic oxidation using flapless or conventional one-stage (control) surgery in contralateral jaw quadrants. The implants were placed into the osteotomies, and the international stability quotient (ISQ) was recorded using resonance frequency analysis. These measurements were repeated following a 3-month healing interval when the animals were euthanized, and implants and surrounding tissues were retrieved and processed for histologic analysis. Results: The implants were stable upon insertion and demonstrated increased stability at 3 months without significant differences between surgical protocols. The histologic evaluation showed high bone-implant contact (flapless surgery: 54.7% ± 8.4%; control: 52.2% ± 13.0%; P>0.05) without evidence of gingival tissue or foreign body inclusions. There were no significant differences in marginal bone levels between the surgical protocols. Post-insertion and at 3 months, ISQ values depended on the amount of torque delivered. Immediately post-insertion, for every I unit increase in torque value, the ISQ increased by 0.3 (95% confidence interval: 0.1 to 0.4; P = 0.0043). Three months postoperatively, for every one-unit increase in torque the ISQ value decreased 0.2 (95% confidence interval: -0.4 to -0.1: P=0.0012). The effect of torque on ISQ values was independent of treatment effects and remained significant after adjustment for treatment. Conclusions: The results suggest that implants placed without flap reflection remain stable and exhibit clinically relevant osseointegration similar to when implants are placed with flapped procedures. Greater torque at implant placement resulted in less implant stability at 3 months. [ABSTRACT FROM AUTHOR]

The study presented was designed to analyse the mechanical performance and the primary and secondary stability characteristics of endosseous titanium implants with 1° (EXP1) and 2° (EXP2) of taper when compared with the standard Brånemark design (Nobel Biocare AB, Gothenburg, Sweden). One pair of 10 mm EXP1 and control implants were placed in the femoral condyles of six rabbits. Paired 6 mm EXP1 and control implants and 6 mm EXP2 and control implants were placed in the tibial metaphysis. The control implants used were 4 mm diameter standard Brånemark implants, the same length as the test implants. At placement, insertion torque (IT) and resonance frequency analysis (RFA) measurements were performed. Six weeks postoperatively when the animals were killed, RFA and removal torque (RT) measurements were made. At placement, significantly higher IT was needed to insert the EXP implants compared with the controls. RFA values were significantly higher for EXP1 implants placed in the tibia but not in the femur. In pooling data from the femur and tibia there was a significant difference. The EXP2 implants failed to insert fully and demonstrated a lower RFA value than may have been expected due to the exposed threads, although this difference was not statistically significant. The results from the present study showed that 1° of taper results in a better primary stability compared with the standard Brånemark design. There was no evidence that the tapered design caused negative bone tissue reactions. All the implants gained in stability during the healing period. To cite this article: O'Sullivan D, Sennerby L, Meredith N. Influence of implant taper on the primary and secondary stability of osseointegrated titanium implants. Clin. Oral Impl. Res. doi: 10.1111/j.1600-0501.2004.01041.x [ABSTRACT FROM AUTHOR]

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Copyright of Clinical Oral Implants Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)