bluuebunny/crossref_metadata_2025 huggingface dataset:
Five‐year prospective follow‐up report of the Astra Tech Dental Implant System in the treatment of edentulous mandibles
Authors: Arvidson Kristina , Bystedt Hans , Frykholm Anders , Von Konow Lars , Lothigius Eric
Published: March 2003

This report of the 1st 2 prospective studies using the Astra Tech Implant System and fixed detachable bridges for rehabilitation of mandibular edentulism, presents clinical and radiographic data at the 5‐year follow‐up. The original material comprised 109 subjects, 56 of whom had been included in the original study, using the 1st generation Astra Tech Implant. Two subjects were excluded and the 3‐year follow‐up report was based on the remaining 54 subjects and 310 fixtures. After some minor changes to the fixture and the abutment, the 2nd generation Astra Tech Implant was used in 53 subjects and 308 fixtures. In all 16 subjects were lost to follow‐up and the 5‐year results are based on the remaining 91 subjects with 517 fixtures in function: 5 fixtures were lost due to mobility at abutment installation and during the 1 st year, 2 fixtures were removed due to pain, and after 4 years in situ 1 fixture failed. As no clinical or radiographic differences were obvious in the annual registrations of the 2 studies the results have been combined. The fixed bridges were removed at 3 and 5 years to test each fixture and none was mobile. The cumulative fixture survival rate at 5 years was 98.7% and the bridge survival rate was 100%. Of the sites 82% were plaque free, and 96.8% showed no signs of inflammation. Over the 5‐year period after bridge insertion, i.e. from baseline registration, there was only minor deterioration in marginal bone levels as measured on standardized intraoral radiographs: the mean differences in mm and standard deviations (SD) were −0.09 (0.27&) in the 1st year, −0.20 (0.40) in the 3rd year, and −0.26 (0.53) in the 5th year. According to the stringent clinical and radiographic criteria by Albrektsson and co‐workers, the successful treatment outcome and the survival rate in 91 subjects over 5 years, indicates that the Astra Tech Dental Implant System with fixed detachable bridges is an appropriate method for rehabilitation of mandibular edentulism.
Incomplete bone regeneration of rabbit calvarial defects using different membranes
Authors: Aaboe Merete , Pinholt Else Marie , Schou Søren , Hjørting‐hansen Erik
Published: March 2003

The present study describes the use of a degradable and a non‐degradable material for guided bone regeneration. Forty rabbits were divided into 5 groups. Bicortical defects 15 mm in diameter were prepared in rabbit calvaria. A titanium microplate was placed over the defect to prevent collapse of the membrane. The calvarial defects of 2 groups were covered by an outer expanded polytetrafluoroethylene (e‐FTFE) membrane respectively by a Polyglactin 910 membrane. Bicortical e‐PTFE membranes or Polyglactin 910 membranes were used in 2 other groups. The defects were not covered by membranes in the control group. Undecalcified sections were prepared for histologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. The Polyglactin 910 material lacks physical strength, resulting in collapse of the membrane and brain tissue hemiation into the defects. Subsequently, bone regeneration was impaired. The cellular reactions due to degradation of the material were minor and did not interfere with bone healing. Defects covered bicortically by e‐PTFE membranes revealed the largest amount of regenerated bone. The e‐PTFE membrane induced a severe cellular reaction, but no inhibition of bone regeneration was noted.
Evaluation of single‐tooth restorations on ITI dental implants. A prospective study of 29 patients
Authors: Moberg Lars‐erik , Köndell Per‐åke , Kullman Leif , Heimdahl Anders , Gynther Göran W.
Published: March 2003

From January 1992 to March 1997, a total of 30 ITI hollow cylinder implants were installed to replace lost single maxillary incisor teeth. Conical abutments with cemented all‐ceramic crowns were used in 10 cases and the Octa‐abutment with screw‐retained metallo‐ceramic crowns in 19 cases. One implant failed due to postoperative infection, and was extracted a month after installation. After a mean observation time of 3.4 years, the cumulative success rate is 96.7%. Only minor bone loss has occurred around the implants, and there have been no other complications to date. The implant system fulfills the requirements for good function 1 and esthetics.
Clinical and radiological results of patients treated with three treatment modalities for overdentures on implants of the ITI® Dental Implant System. A randomized controlled clinical trial.
Authors: Wismeijer Daniel , Van Waas Marinus A. J. , Mulder Jan , Vermeeren Jacques I. J. F. , Kalk Warner
Published: March 2003

In a randomized controlled clinical trial carried out at the Ignatius teaching hospital in Breda, The Netherlands, I10 edentulous patients with severe mandibular bone loss were treated with implants of the ITI® Dental Implant System using 3 different treatment strategies: a mandibular overdenture supported by either 2 implants with ball attachments, 2 implants with an interconliecting bar, or by 4 interconnected implants. In this study, results of clinical and radiographic parameters were evaluated and compared over a period of 19 months after implant placement. A total of 283 ITP Dental Implants were placed. Six implants (2%) were lost during the osseointegration period. No further implant losses occurred after that, At the 19 month evaluation mean values and standard deviations for bleeding index were 0.51±0.5 (bleeding incidence=70%) and for plaque index they were 0.46±0.5 (plaque incidence=45%). The mean values and standard deviations for probing depth and loss of attachment were 2.7±1.1 mm and 0.26±O.6 mm respectively. The radiographic evaluation showed a mean bone loss of 1.5 mm± 0.26 after 19 months for all the implants. In cases with 4 interconnected implants there was significantly more bone loss around the central 2 implants (2.1±0.31 mm) in comparison with the lateral 2 (1.4±0.25 mm). No significant correlations were found between plaque and bleeding indices and bone loss.
Cell culture tests for assessing the tolerance of soft tissue to variously modified titanium surfaces
Authors: Säuberlich Simone , Klee Doris , Richter Ernst‐jürgen , Höcker Hartwig , Spiekermann Hubertus
Published: March 2003

The aim of our research project was to achieve an improvement in the integration of enossal dental implants in the region of peri‐implantary soft tissue. Improvement in the adhesion of the gingiva to the surface of enossal implants was to be achieved by modification of the titanium surface. The effect of different modifications on the biocompatibility of the modified titanium surfaces was tested: sulfur dioxide plasma treatment of titanium; acetylene plasma treatment of titanium followed by sulfur dioxide plasma etching; plasma nitration of titanium: replacement of titanium by glycidoxypropyltrimethoxy silane; coating titanium with poly[(ethene‐co‐vinyl acetate)‐graft‐vinyl chloride] and coating titanium with fibronectin. Determination of the chemical composition of the surface was carried out using X‐ray photospectroscopy. The adsorption of fibronectin at the surface of the titanium was tested using an Enzyme Linked Immunosorbent Assay. In selected in vitro tests with human gingival fibroblasts, cell morphology was assessed using scanning electron microscopy and light microscopy. Cell proliferation and protein synthesis, as well as the activity of mitochondrial dehydrogenases were evaluated. By means of centrifugation and by determining initial cell adhesion, the adhesion of gingival fibroblasts was investigated. According to the kind of modification made to the titanium surfaces, it was possible to observe differences in the cellular behavior of gingiva fibroblasts on the differently modified surfaces of the implants. Coating the titanium using fibronectin produced optimization of cell growth and improvement in the adhesion of gingiva fibroblasts to the implant surface. In contrast, modification of the titanium with poly[(ethene‐co‐vinyl acetate)‐graft‐vinyl chloride] generally resulted in a deterioration of the biocompatibility of the surface. A marked correlation between the cellular compatibility of the modified titanium and the surface modification made did not become apparent. One reason for this is the large number of parameters determining the interaction between implant and tissue.
Characteristic features of trabecular bone in edentulous maxillae
Authors: Ulm Christian , Kneissel Michaela , Schedle Andreas , Solar Peter , Matejka Michael , Schneider Barbara , Donath Karl
Published: March 2003

Following tooth loss, the maxillary alveolar ridge is affected by extensive resorption and its cancellous bone substance undergoes intense remodeling processes. This is particularly important for endosseous implant surgery as the primary stability and thus the prognosis of endosseous implants depends on the cancellous bone density and structure of the alveolar ridge. To analyze the structure of alveolar trabecular bone, 156 sections were obtained from 52 edentulous maxillae (29 female, 23 male; mean age: 72.5 years) from the lateral incisor, first premolar, and first molar regions. The structural histomorphometric analysis was performed on cancellous bone of the section surfaces using semiautomatic image analysis. The following parameters were measured: trabecular bone volume, trabecular number, trabecular thickness, trabecular plate separation and trabecular interconnection. All examined parameters showed an extreme range of variation. A difference of more than 45% between the highest (=51.93%) and the lowest (=6.73%) trabecular bone volumes was found. Furthermore, the measurements showed that trabecular bone volume, thickness and number were distinctly lower in the molar region than in the incisal and premolar regions. Significant sex‐specific differences were found in all investigated regions, female maxillae showing a smaller amount and a lower connectivity of cancellous bone than male maxillae.
The combined use of bioresorbable membranes and xenografts or autografts in the treatment of bone defects around implants. A study in beagle dogs.
Authors: Hockers Thierry , Abensur David , Valentini Pascal , Legrand Roman , Hämmerle Christoph H. F.
Published: March 2003

The aim of the present investigation was to test the effect of a bioresorbable membrane supported by xenografts or autografts in regenerating bone into peri‐implant defects. In 3 dogs, the mandibular premolars P2, P3, P4 and M1 were extracted bilaterally. After 4 months of healing, 3 standardized bone defects were prepared on each side of the mandible and 1 implant per defect was placed. The 6 sites in each dog were distributed into 4 different treatment groups: 2 sites received a Bio‐Gide® membrane alone (BG); 2 sites received a Bio‐Gide® membrane supported by Bio‐Oss®(BG+BO); 1 site received the Bio‐Gide® membrane supported by auto‐genie bone harvested from the prepared defects (BG+Aut); 1 site received neither membrane nor bone graft and served as control (C). The soft tissue flaps were adapted and sutured for primary healing. No adverse events occurred during the experimental period. After 16 weeks, the dogs were sacrificed and histomorphometric examinations on non‐decalcified ground sections were carried out. The vertical bone growth amounted to 45%(SD±l3%) of the defect height in the BG group, to 78%(SD±29%) in the BG+BO group, to 69%(SD±9%) in the BG+Aut group, and to 22%(SD±10%) in C group. The horizontal bone growth measured 78%(SDi±16%) in the BG group, 81%(SD±21%) in the BG+BO group, 82%(SD±l2%) in the BG+Aut group, and 46%(SD±21%) in the C group. The vertical height of bone growth in contact with the implant measured 17%(SD±12%) in the BG group, 20%(SD±12%) in the BG+BO group, 17%(SD±7%) in the BG+Aut group, and 12%(SD±8%) in the C group. The surface fraction of the graft in direct bone contact measured 89%(SD±9%) in the BG+BO group and 93%(SD±3%) in the BG+Aut group. It is concluded that the bioresorbable membrane tested enhances bone regeneration, in particular in conjunction with the use of a supporting graft material. In addition, deproteinized bovine bone mineral and autogenic bone grafts appeared to be equally well integrated into regenerating bone. Finally, no additional effects in the bone growth was observed with the autogenous bone in comparison with the hydroxyapatite.
Sinus floor augmentation with simultaneous placement of dental implants using a combination of deproteinized bone xenografts and recombinant human osteogenic protein‐l. A histometric study in miniature pigs.
Authors: Terheyden Hendrik , Jepsen Søren , Möller Björn , Tucker Marjorie M. , Rueger David C.
Published: March 2003

Maxillary sinus floor augmentation with autogenous bone has become a widely accepted procedure in implant dentistry. The use of osteoconductive bone substitutes in this indication is controversial, since their use can lead to a prolonged healing time, inhomogenous ossification, foreign body reaction, migration of particles and low bone‐implant contact (BIC). The purpose of this study was to examine whether the combination of an osteoinductive protein (recombinant human osteogenic protein‐l (rhOP‐1=bone morphogenetic protein‐7) with natural bovine bone mineral (Bio‐Oss®) would improve ossification and the bone‐implant contact (BIC) in a sinus floor augmentation with simultaneous placement of implants. In this study, the maxillary sinus floors in 5 miniature pigs were augmented with 3 ml Bio‐Oss® containing 420 μg rhOP‐1 on the test side and 3 ml Bio‐Oss® alone on the control side. At the time of augmentation a titanium implant (ITI®) was inserted from a laterocaudal direction. After 6 months of healing the sites of augmentation were removed and examined in non‐decalcified sections by microradiography, fluorescence microscopy of sequentially labelled specimens and by histometry. On both sides, significant amounts of newly‐formed bone were observed. However, on the test sites, the percentage of BIC in the augmented area was 80.0% versus 38.4% on control sites. It can be concluded that the application of bone morphogenetic proteins caused a more rapid and enhanced osseointegration of simultaneously placed implants when compared to the bone substitute alone. Therefore recombinant human osteogenic protein‐l delivered by natural bone mineral has the potential to become a clinical alternative for autogenous bone grafts in sinus floor augmentation.
Considerations preliminary to the application of early and immediate loading protocols in dental implantology
Authors: Szmukler‐Moncler Serge , Piattelli Adriano , Favero Gian Antonio , Dubruille Jean‐Hermann
Published: March 2003

In oral implantology, a 3–6 month stress‐free healing period is presently accepted as a prerequisite to achieve bone apposition without interposition of a fibrous scar tissue. This protocol was introduced by Brånemark and co‐workers in 1977. The aim of the present paper is to review the reasons that led Brånemark and collaborators to require long delayed loading periods. It is shown that the requirement for long delayed loading periods was drawn from the initiation and development periods of their original clinical trial. Demanding conditions were met involving simultaneously: 1) patients with poor bone quality and quantity, 2) non‐optimized implant design, 3) short implants, 4) non‐optimized surgical placement, 5) non‐optimized surgical protocol and 6) biomechanically non‐optimized prosthesis. Extrapolation of the requirement for long healing periods from these particular conditions to more standard situations involving refined surgical protocols and careful patient selection might be questioned. Albeit premature loading has been interpreted as inducing fibrous tissue interposition, immediate loading per se is not responsible for fibrous encapsulation. It is the excess of micromotion during the healing phase that interferes with bone repair. A threshold of tolerated micromotion exists, that is somewhere between 50 μm and 150 μm. It is suggested that loading protocols might be shortened through 2 different approaches. The first way would be to decrease stepwise the delayed loading period for free‐standing implants below the presently accepted 3–6 months of healing. The second way would be to identify immediate loading protocols that are capable of keeping the amount of micromotion beneath the threshold of deleterious micromotion. Immediate loading protocols for implants‐retained overdentures and fixed bridges are reviewed. It is shown that successful premature loading protocols require a careful and strict patient selection aimed to achieve the best primary stability. These various protocols need to be further documented in order to assess their predictability.
Guided bone regeneration around endosseous implants using a resorbable membrane vs a PTFE membrane
Authors: Schliephake Henning , Dard Michael , Planck Heinrich , Hierlemann Helmut , Jakob Andrea
Published: March 2003

The aim of the present experimental pilot study was to assess bone regeneration underneath resorbable barrier membranes vs non‐resorbable extended polytetrafluoroethylene (ePTFE) membranes in peri‐implant defects. Two implants were inserted into surgically created defects on each side of the mandibles of 6 adult beagle dogs 3 months after extraction of all premolar teeth. One implant on each side was covered with a porous polylactic acid membrane or a ePTFE membrane, respectively, while the second implant served as control. Fluorochrome labelling was administered during the 1st, 5th, 12th and the 18th week. Three animals each were evaluated after 3 and 6 months. Bone regeneration was assessed by measuring the distance from the first fluorochrome label to the level of the regenerated bone immediately adjacent to the implant surface and to the top of the newly formed alveolar contour both on the lingual and buccal side. The increase in bone height was significantly higher compared to the controls under both barrier membranes after 3 months at the top of the alveolar crest but not immediately adjacent to the implant surface. After 6 months, bone height was significantly increased only at the top of the alveolar contour underneath the ePTFE membranes, while bone underneath the polylactic acid membranes showed signs of superficial resorption. It is concluded that guided bone regeneration underneath barrier membranes can restore alveolar bone contour but is not necessarily associated with a higher bone/implant contact. The use of resorbable membranes may be associated with untoward biological effects at later stages, when membrane degradation starts due to degradation products of the polymer material or decreasing membrane stability. Future efforts have to refine the relation between degradation kinetics, membrane porosity and mechanical properties of degradable barrier membranes to improve membrane performance.
Magnitude and distribution of occlusal forces on oral implants supporting fixed prostheses: an in vivo study
Authors: Duyck Joke , Van Oosterwyck Hans , Vander Sloten Jos , De Cooman Michel , Puers Robert , Naert Ignace
Published: March 2003

Since loading is increasingly believed to be a determining factor in the treatment outcome with oral implants, there is a need to expand the knowledge related to the biomechanics of oral implants. The aim of this study is to gain insight in the distribution and magnitude of occlusal forces on oral implants carrying fixed prostheses. This is done by in vivo quantification and qualification of these forces, which implies that not only the magnitude of the load but also its type (axial force or bending moment) will be registered. A total of 13 patients with an implant supported fixed full prosthesis were selected. Occlusal forces on the supporting implants were quantified and qualified during controlled load application of 50 N on several positions along the occlusal surface of the prostheses and during maximal biting in maximal occlusion by use of strain gauged abutments. The test was conducted when the prostheses were supported by all (5 or 6) implants and was repeated when the prostheses were supported by 4 and by 3 implants only. Despite considerable inter‐individual variation, clear differences in implant loading between these test conditions were seen. Loading of the extension parts of the prostheses caused a hinging effect which induced considerable compressive forces on the implants closest to the place of load application and lower compressive or tensile forces on other implants. On average, higher forces were observed with a decreasing number of supporting implants. Bending moments were highest when 3 implants only were used.
A new microtomographic technique for non‐invasive evaluation of the bone structure around implants
Authors: Sennerby Lars , Wennerberg Ann , Pasop Freek
Published: March 2003

Abstract: A new X‐ray microtomographic technique for non‐invasive assessment of the structure of bone surrounding implants was tested. Three titanium microimplants retrieved directly (n=2) or 6 months (n=1) after insertion in 3 patients were used as test samples. Two samples were used dry and one was embedded in plastic resin prior to microtomography. The technique provided high‐resolution consecutive cross‐sectional X‐ray images of the specimens with a slice‐to‐slice distance of 4.4 to 11.0 μm. The pictures could be imported into an image analysing software with which semiautomatic quantitative measurement of the bone area and three‐dimensional images of the specimens could be made. It is suggested that the technique may be used for non‐invasive assessment of the bone structure around implants. Further studies are needed to evaluate the accuracy of the technique, for instance by comparing tomographic sections with histologic ones.
Long‐term evaluation of non‐submerged hollow cylinder implants
Authors: Merickse‐Stern Regina , Aerni Dominik , Geering Alfred H. , Buser Daniel
Published: March 2003

Abstract: From 1974 various types of hollow cylinder ITI‐implants were placed before the new generation of Bonefit ITI‐implants was developed in the mid‐eighties. The aim of this study was the clinical and radiographic evaluation of hollow cylinder implants that were inserted during the time period of 1978–1987 in partially and completely edentulous patients to support overdentures, fixed partial prostheses and single crowns. Altogether, 71 patients with a total of 132 hollow cylinder ITI‐implants still in situ had been followed regularly during the entire observation period of 11.4 to 19.7 years (mean 14.1). Thirteen implants had to be removed before an observation period of 10 years was completed, 4 additional implants were lost after being in function for over 10 years and two further implants were considered to be failures at the time of the examination. Thus 91.4% of the implants were still in situ after 10 years and the survival rate for a mean observation period of 14.1 years was 84.6%. Periimplant parameters were used to assess the clinical conditions of the implants. On the radiographs, horizontal bone loss or angular defects could be detected on 40% of all implants if compared to the base‐line situation. The probing depths around these implants were significantly increased compared to implants with an unchanged bone level, however the mean probing depths did not exceed 3.5 mm and 2.8 mm respectively. From this clinical evaluation one may conclude that with the early generation of hollow cylinder ITI‐implants favorable long‐term results were achieved.
Histology of human alveolar bone regeneration with a porous tricalcium phosphate
Authors: Zerbo Ilara R. , Bronckers Antonius L. J. J. , De Lange Gert L. , Burger Elisabeth H. , Van Beek Gert J.
Published: March 2003

Abstract: Porous β‐phase tricalcium phosphate particles (pTCP) (Cerasorb®) were used in two patients to restore or augment alveolar bone prior to the placement of dental implants. In one patient, pTCP was used to fill a large alveolar defect in the posterior mandible after the removal of a residual cyst, and in another patient to augment the sinus floor. Biopsies were taken at the time of implant placement, 9.5 and 8 months after grafting, respectively, and processed for hard tissue histology. Goldner‐stained histological sections showed considerable replacement of the bone substitute by bone and bone marrow. In the 9.5 months biopsy of the mandible, 34% of the biopsy consisted of mineralised bone tissue and 29% of remaining pTCP, while the biopsy at 8 months after sinus floor augmentation consisted of 20% mineralised bone and 44% remaining pTCP. Bone and osteoid were lying in close contact with the remaining pTCP and were also seen within the micropores of the grafted particles. Tartrate resistant‐acid phosphatase (TRAP) multinuclear cells, presumably osteoclasts, were found surrounding, within and in close contact with the pTCP particles, suggesting active resorption of the bone substitute. Remodelling of immature woven bone into mature lamellar bone was also found. No histological signs of inflammation were detected. The limited data presented from these two cases suggest that this graft material, possibly by virtue of its porosity and chemical nature, may be a suitable bone substitute that can biodegrade and be replaced by new mineralising bone tissue.
Multidimensional osteodistraction for correction of implant malposition in edentulous segments
Authors: Zechner Werner , Bernhart Thomas , Zauza Konstantin , Celar Ales , Watzek Georg
Published: March 2003

Abstract: This study examined multidimensional osteodistraction as a treatment method for correction of implant malposition and as an alternative to augmentation procedures. The prosthetically unfavourable implant positions were due to growth‐related implant malposition (in the context of treatment of young patients with oligodontia) or primary bone‐driven implant insertions. The radiographical and clinical findings obtained with this osteodistraction technique are presented and discussed. A tooth‐supported osteodistractor for multidimensional distraction with custom‐fabricated distraction abutments was used for treatment of 8 patients with a total of 9 maxillary and mandibular edentulous segments including single‐tooth gaps. All patients underwent an osteotomy at a minimum distance of 1 mm from the implant surface. Following primary wound healing, distraction was carried out by 1 mm in vertical direction and 0.5 mm in the demanded transverse direction daily until the prosthetically optimized position was achieved. During and after the 12‐week retention phase, the patients were evaluated clinically and radiographically. Multidimensional osteodistraction was carried out successfully in all 8 patients. The distraction distances were 3 to 11 mm in vertical direction and a maximum of 5 mm in buccolingual/buccopalatal direction. The malpositioned implants were brought into a prosthetically optimized position in all cases. The results of this study show that this multidimensional osteodistraction technique allows both augmentation of edentulous segments with a clearly compromised implant host site and correction of unfavourable implant positions.
Infectious risks for oral implants: a review of the literature
Authors: Quirynen Marc , De Soete Marc , Van Steenberghe Daniel
Published: March 2003

Abstract: The use of oral implants in the rehabilitation of partially and fully edentulous patients is widely accepted even though failures do occur. The chance for implants to integrate can for example be jeopardised by the intra‐oral presence of bacteria and concomitant inflammatory reactions. The longevity of osseointegrated implants can be compromised by occlusal overload and/or plaque‐induced peri‐implantitis, depending on the implant geometry and surface characteristics. Animal studies, cross‐sectional and longitudinal observations in man, as well as association studies indicate that peri‐implantitis is characterised by a microbiota comparable to that of periodontitis (high proportion of anaerobic Gram‐negative rods, motile organisms and spirochetes), but this does not necessarily prove a causal relationship. However, in order to prevent such a bacterial shift, the following measures can be considered: periodontal health in the remaining dentition (to prevent bacterial translocation), the avoidance of deepened peri‐implant pockets, and the use of a relatively smooth abutment and implant surface. Finally, periodontitis enhancing factors such as smoking and poor oral hygiene also increase the risk for peri‐implantitis. Whether the susceptibility for periodontitis is related to that for peri‐implantitis may vary according to the implant type and especially its surface topography.
Effect of RGD peptide coating of titanium implants on periimplant bone formation in the alveolar crest
Authors: Schliephake Henning , Scharnweber Dieter , Dard Michael , Rößler Sophie , Sewing Andreas , Meyer Jörg , Hoogestraat Dennis
Published: March 2003

Abstract: The aim of the present study was to analyse the effect of organic coating of titanium implants on periimplant bone formation and bone/implant contact. Three types of implants were used: (i) Ti6Al4V implants with polished surface (control 1) (ii) Ti6Al4V implants with collagen coating (control 2) (iii) Ti6Al4V implants with collagen coating and covalently bound RGD peptides. All implants had square cross‐sections with an oblique diameter of 4.6 mm and were inserted press fit into trephine burr holes of 4.6 mm in the mandibles of 10 beagle dogs. The implants of five animals each were evaluated after a healing period of 1 month and 3 months, during which sequential fluorochrome labelling of bone formation was performed. Bone formation was evaluated by morphometric measurement of the newly formed bone around the implant and the percentage of implant bone contact. After 1 month there was only little bone/implant contact, varying between 2.6 and 6.7% in the cortical bone and 4.4 and 5.7% in the cancellous bone, with no significant differences between the three types of implants. After 3 months, implants with polished surfaces exhibited 26.5 and 31.2% contact in the cortical and cancellous bone, respectively, while collagen‐coated implants had 19.5 and 28.4% bone contact in these areas. Implants with RGD coating showed the highest values with 42.1% and 49.7%, respectively. Differences between the surface types as such were not significant, but the increase in bone/implant contact from 1 to 3 months postoperatively was significant only in the group of RGD‐coated implants (P = 0.008 and P = 0.000). The results of this pilot study thus provide only weak evidence that coating of titanium implants with RGD peptides in the present form and dosage may increase periimplant bone formation in the alveolar process. The results therefore require further verification in a modified experimental setting.
Comparative evaluation of casting retention using the ITI solid abutment with six cements
Authors: Mansour Ahmed , Ercoli Carlo , Graser Gerald , Tallents Ross , Moss Mark
Published: March 2003

Abstract: Objective: The purpose of this study was to test the retention of metal copings fabricated to fit on the one‐groove, one flat‐sided solid titanium abutment using six different cements.

Materials and methods: Ten hollow screw 3.8 mm ITI implants were mounted in acrylic resin blocks. A solid titanium abutment was placed on each implant and torqued at 35 Ncm. Prefabricated burn‐out caps were placed on the titanium abutment and wax loops added to the occlusal surface to allow for subsequent retention testing. All plastic caps were embedded in phosphate‐bonded investment and cast with noble alloy. Castings were inspected for surface irregularities using a stereomicroscope at 10× magnification.

The six cements were: 1) eugenol‐free zinc oxide (Temp Bond NE); 2) zinc‐oxide eugenol (IRM); 3) zinc phosphate (Hy‐Bond); 4) resin‐modified glass ionomer (Protec Cem); 5) zinc polycarboxylate (Durelon) and 6) 10‐methacryloyloxydecyl dihydrogen phosphate resin (Panavia 21). After cementation, implant–abutment–casting assemblies were stored for 24 h in 100% humidity. Samples were subjected to a pull‐out test using an Instron universal testing machine at a crosshead speed of 0.5 mm/min. The load required to de‐cement each coping was recorded and mean values for each group calculated. Means and standard deviations of loads at failure were analyzed using ANOVA and a Tukey studentized test. Statistical significance was set at P ≤ 0.05.

Results: The mean values (± SD) of loads in kilograms at failure (n = 10) for the various cements were as follows: Temp Bond 3.18 (± 1.1) (Tukey group D), IRM 9.25 (± 3.83) (Tukey group CD), HY‐Bond 10.9 (± 6.52) (Tukey group C), Protec Cem 18.98 (± 6.23) (Tukey group B), Durelon 23.55 (± 4.29) (Tukey group B) and Panavia 21, 36.53 (± 8.1) (Tukey group A). Means with the same letter in the Tukey grouping are not significantly different.

Conclusions: The retention values of castings cemented to ITI solid abutments have not been reported in the literature. Within the limitations of this in vitro study, the results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements in their ability to retain the castings. This ranking is somehow different than that obtained when the same cements are used on natural teeth. The material and surface characteristics of the implant abutment are likely responsible for this difference. Cement retention values obtained from studies that use teeth as abutments may be misleading when used in cement‐retained implant‐supported crowns. It is at the clinician's discretion to use a certain type of cement, based on the situation at hand.
Biologic outcome of implant‐supported restorations in the treatment of partial edentulism
Authors: Naert Ignace , Koutsikakis George , Quirynen Marc , Duyck Joke , Van Steenberghe Daniel , Jacobs Reinhilde
Published: March 2003

Abstract: The purpose of this study was to evaluate over time the marginal bone level changes around implants installed to treat partial edentulism and to investigate the possible effect of several confounding variables. Consecutive intraoral radiographs taken with the paralleling technique were used. In all, 660 partially edentulous patients ever treated in the departments (248 males; 15–83 years of age) with 1655 implants, which were successfully integrated at abutment connection, were loaded by means of fixed partial prostheses. The observation period starting at abutment connection reached 16 years (mean 5.1). Implants were divided into three groups: 235 implants supported single‐tooth crowns, 398 supported implant‐tooth connected and 1022 free‐standing fixed partial prostheses. Implants were placed in maxilla and mandible, both anteriorly and posteriorly. No significant difference in bone level evolution was predicted between the three groups of implants, either for posterior or for anterior sites. The estimated marginal bone loss for the first 6 months is 0.31 mm/year and after that 0.015 mm/year higher in the maxilla than in the mandible. More bone loss was predicted for the first 6 months when dehiscences existed, when a membrane or a bone graft were used, or when metal/ceramic prosthesis material was applied. Age and gender did not affect the change in bone level. The use of subsequently situated single‐implant crowns to restore an edentulous space did not lead to more marginal bone loss than around splinted implants. Based on marginal bone height maintenance, the excellent prognosis of the presently used implants to support restorations in the treatment of partial edentulism was confirmed.
Freeze‐dried homogeneous and heterogeneous bone for sinus augmentation in sheep
Authors: Haas Robert , Haidvogl Daniela , Donath Karl , Watzek Georg
Published: March 2003

Abstract: Freeze‐dried bone has been reported to possess an osteogenetic potential, i.e. to be osteo‐inductive or osteoconductive depending on the grafted site. In this animal study homogeneous demineralized freeze‐dried bone from the sheep (s‐DFDB) and heterogeneous human demineralized freeze‐dried bone (h‐DFDB) used for single‐stage sinus elevation were examined for their potential to improve bone‐to‐implant bonding. In 72 sinuses of 36 adult female mountain sheep Schneider's membrane was elevated from the local bone through an extra‐oral approach and two cylindrical plasma‐flame sprayed titanium implants were inserted in the lateral wall of each sinus. At the same time 18 sinuses were reinforced with s‐DFDB, another 18 with h‐DFDB and yet another 18 with autogenous cancellous bone from the iliac crest. In 18 animals the subantral space remained ungrafted. At each follow‐up date, i.e. at 12, 16 and 26 weeks, 12 animals were re‐examined and one randomly selected implant from each sinus was analyzed histologically and histomorphometrically. With both s‐DFDB and h‐DFDB extensive fragmentation and disintegration were seen side by side with sporadic areas of remineralization. These were mainly located in the vicinity of the local host bone and coalesced over time to be ultimately replaced and consolidated by woven bone. But most of the h‐DFDB/s‐DFDB particles continued to be embedded in abundant collagenous connective tissue and were surrounded by mononucleated and multinucleated giant cells, ultimately causing extensive resorption. The mean bone‐to‐implant contact length was 16.4% of the implant surface for s‐DFDB, 16.9% for h‐DFDB, 32.8% for autogenous bone and 22.2% in ungrafted controls. In the autogenous bone group the mean bone‐to‐implant contact length progressively increased with increasing contact time. In the control group, by contrast, the mean bone‐to‐implant contact length initially increased in the first two follow‐up periods, but dropped again at 26 weeks. Both in the h‐DFDB and the s‐DFDB group the percent bone contact area was lower at 16 weeks than at 12 weeks but increased again by 26 weeks. In apical implant sections, s‐DFDB produced significantly less bone‐to‐implant contact than autogenous cancellous bone from the iliac crest. In basal implant sections, both DFDB‐grafted groups did significantly less well than the two control groups. The results of this experimental study showed that DFDB homografts and heterografts cannot be recommended alone instead of cancellous autografts from the iliac crest for augmenting the maxillary sinus in single‐stage sinus elevations. Longer follow‐up times than in the present study may perhaps show better results at the bone–implant interface.
Bone response to alteration of surface topography and surface composition of sandblasted and acid etched (SLA) implants
Authors: Perrin Daniel , Szmukler‐Moncler Serge , Echikou Casimir , Pointaire Philippe , Bernard Jean‐Pierre
Published: March 2003

Abstract: The titanium surface obtained by sandblasting and etching (SLA) is an easily alterable surface that smears and loose its typical texture. In addition, the etching process modifies the surface composition of commercially pure titanium; the latter contains titanium and an added 20–40% of titanium hydride. Therefore, the influence of a heavy surface alteration and the influence of the composition at the SLA surface, i.e. with and without titanium hydride, were investigated in vivo. Three implant groups were inserted in the mandible of Land Race pigs and left to heal during 10 weeks in a submerged way: (1) a standard SLA control group (SLAstd) with the SLA surface containing titanium hydride; (2) a test group with the SLA surface heavily altered at the thread level (SLAalt); (3) a test group with an SLA surface devoid of titanium hydride (SLAT). Sample size was n = 8. Histomorphometry analysis did not show a statistically significant difference between the control group (SLAstd: 82.12 + 6.1%), the altered surface test group (SLAalt: 86.25 + 7.4%) and the SLA without titanium hydride test group (SLAT: 75.12 + 7.6%). The data suggest that alteration of the SLA surface, if it occurs, should not be detrimental to bone response. The soft and easy smearable SLA surface might even be an advantage when surface maintenance is required. Surface composition did not play a significant role in the bone response to the SLA surface and it can therefore be concluded that the osteophilic properties of the SLA surface are due to its surface topography and not to its specific surface composition.
A prospective study evaluating a protocol for 6 weeks' loading of SLA implants in the posterior maxilla
Authors: Roccuzzo Mario , Wilson Thomas G
Published: March 2003

Abstract: Experimental and clinical studies have shown that modification of implant surfaces can result in increased bone‐to‐implant contact at earlier times thus reducing the healing period between surgery and prosthesis. Sandblasted and acid‐etched (SLA) implants are in this category and have successfully undergone early loading in patients with good bone quality and quantity. Nevertheless, premature loading of SLA implants was not routinely possible in predominantly trabecular bone, such as the posterior maxilla, as it is often characterized by a deficiency in initial bone to implant contact. The purpose of this prospective clinical investigation is to evaluate the efficacy of a modified surgical protocol followed by loading SLA implants at 6 weeks in the posterior maxilla. Drilling was limited to the minimum, and most of the site preparation was produced with osteotomes. Screw tapping was never performed and primary stability was always achieved. Abutment connection was carried out at 15 Ncm 43 (± 1) days after surgery and provisional restoration was fabricated. Further abutment tightening at 35 Ncm was performed after an additional 6 weeks. Of the 36 SLA implants placed in 19 patients, one was lost before final restoration. Clinical and radiographic measures were taken at baseline and 1 year postoperatively. The preliminary results suggest that, by means of the surgical and restorative technique presented, SLA implants are suitable for loading at 6 weeks in the posterior maxilla. More years of observation will verify whether osseointegration can be equally maintained over a long period.
Histological assessment of augmented jaw bone utilizing a new collagen barrier membrane compared to a standard barrier membrane to protect a granular bone substitute material
Authors: Friedmann Anton , Strietzel Frank Peter , Maretzki Burghard , Pitaru Sandu , Bernimoulin Jean‐Pierre
Published: March 2003

Abstract: Successful bone augmentation requires predictable space maintenance and adequate exclusion of those cells that lack osteogenetic potential from the defect area. Natural bone mineral is considered to be osteoconductive and is used as space maker in combination with membrane barrier techniques. The aim of this study was to compare qualitative histological results achieved by using deproteinized bovine bone mineral (DBBM) as a space maintainer and a new collagen barrier (Ossix™, test group) vs. the same bone substitute and the standard e‐PTFE membrane (Gore‐Tex®, control group). Twenty‐eight patients were randomly assigned to the test or the control group. Seven months after augmentation procedures, biopsies were obtained at reentry and were analysed histomorphometrically. In all, 14 specimens of group I (test group, Ossix™) and 13 specimens of group II (controls, PTFE‐membranes) showed close qualitative similarity of their histologies. Histomorphometrically, total mineralized bone area was 42% ± 18% in group I vs. 39% ± 15% in group II. The unmineralized tissue area was 44% ± 15% vs. 46% ± 12% and the area of DBBM remnants 14% ± 9% and 15% ± 12%, respectively. The differences were statistically nonsignificant (Mann–Whitney test). The occurrence of barrier exposure did not interfere with the histological outcome either in the test or in the control group. The new collagen barrier combined with the DBBM provided qualitative bone regeneration comparable to the standard e‐PTFE material combined with the same mineral.
Three‐dimensional finite element analysis of implant stability in the atrophic posterior maxilla
Authors: Tepper Gabor , Haas Robert , Zechner Werner , Krach Wolfgang , Watzek Georg
Published: March 2003

Abstract: Sinus lifting is performed with a variety of materials and techniques without a precise knowledge of the quantity of augmentation. This study based on three‐dimensional finite element analysis was designed to show which surgical procedure and which amount of peri‐implant packing yields the best bony support for dental implants. Eight 3D‐FE models were used. Four modeled standard situations simulated quantitatively different packing situations produced by differences in surgical approach: i. no packing; ii. thin 1 mm bony sheath; iii. oblique subcomplete packing; iv. complete bony peri‐implant packing up to the implant end. A fifth model compared a standard implant with a length of 13.5 mm and a diameter of 3.75 mm with a 7‐mm‐long and 5‐mm‐thick implant. In three additional models the stress response of the bone–implant system was evaluated in the absence of a cortical layer, thus simulating an extreme degree of maxillary atrophy. In all models the modeled implants were loaded at their points of emergence with an assumed force of 100 N. The vector of the loading force was inclined 30° posteriorly relative to the implant axis and 30° away from the sagittal plane. The bone–implant interface was assumed to be perfect simulating full osseointegration.

The final evaluation of the FE models showed complete peri‐implant packing to reduce displacements of the implant tip by 32% vs. no sheathing/packing. Van Mises' equivalent stresses were used to assess the stresses in both human bone and titanium alloy implants. The highest stress levels in bone were predicted for the case without sufficient implant sheathing. In the models with adequate bony implant support, intrabony stresses were generally reduced by up to − 40%. The structural stiffness of the bone–implant system increased with the extent of sinus floor elevation. The results indicate that more extensive peri‐implant packing reduces implant displacement, intrabony stresses and stresses at the bone–implant interface.
Community periodontal index of treatment needs and prevalence of periodontal conditions
Authors: Benigeri Mike , Brodeur Jean‐Marc , Payette Martin , Charbonneau Anne , Ismaïl Amid I.
Published: March 2003

Background/aims: In 1977, the World Health Organization (WHO) proposed a new index, the community periodontal index of treatment needs (CPITN) to evaluate the periodontal treatment needs of populations. The aim of this study is to compare different approaches of recording and presenting the CPITN.

Methods: A sample of 2110 subjects aged 35–44 years were examined between September 1994 and July 1995, throughout the province of Quebec, Canada. For each tooth (3rd molars excluded), the presence of bleeding and calculus, the level of epithelial attachment, and the depth of periodontal pockets were measured. Periodontal pocket depths were measured from the edge of the free gingiva, at 2 sites (mesiovestibular and vestibular), as well as all around the tooth.

Results: Only 8.5% of adults had at least one tooth with a 6 mm or deeper periodontal pocket when probing on 2 sites, whereas if probing is done all around the tooth, this percentageis 2.5× higher (21.4%). The partial recording of pocket depths (10 index teeth recommended by WHO, or 2 quadrants chosen at random) resulted in an underestimation of the prevalence of subjects with at least one tooth with a periodontal pocket (CPITN score 3 and 4). Among subjects with at least one tooth with a 6 mm or deeper periodontal pocket, 12% were not detected with the 10 index teeth recording, and 25% go undetected with the measure on 2 quadrants. Finally, using the % of subjects with periodontal pockets overestimates the prevalence of deep pockets compared with using sextants. Indeed, close to 30.0% of sextants have no treatment needs, whereas only 5.2% of subjects are in this category. Similarly, 7.7% of sextants have at least one tooth with a 6 mm or deeper periodontal pocket, yet there are 3× more subjects in this category (21.4%).