bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of early versus late removal of GTAM® membranes on bone formation at oral implants placed into immediate extraction sockets. An experimental study in dogs.
Authors: Lekholm U. , Becker W. , Dahlin C. , Becker B. , Donath K. , Morrison E.
Published: March 2003

The purpose of this study was to compare the effect of early versus late removal of expanded polytetrafluoroethylene (e‐PTFE) membranes on bone formation at oral implants. Thirty Brånemark™ fixtures were placed into immediate extraction sockets with buccal bone dehiscences augmented by e‐PTFE membranes. At 4 weeks, the membranes and underlying soft tissues were removed from 5 implants, but at 16 sites only the membranes were extirpated. In 9 sites, the membranes remained in place during the healing period. Sixteen weeks after fixture insertion, the sites in which the membrane was retained (MRET) showed an average of 5.2 mm of clinical bone height increase (lOO% of bone fill). For sites where the membrane together with underlying soft tissues were removed (MRB), the corresponding value was 2.0 mm (42% of bone fill. Implants at which only the membrane was removed (MR) showed the least clinical bone height increase (1.0 mm). resulting in 21% coverage of original threads. Histometric measurements verified that the MRET sites had the least distance from the top of the fixture to the newly formed bone level (0.4 mm). However, in contrast with the clinical findings, the histometric analyses showed that the MRB group had the greatest remaining bone defect (3.3 mm). The clinical and histometric results of the MRET group were statistically better, though, compared with those of the other two groups. Biopsies, removed from beneath the membranes, revealed slightly inflamed connective tissue, containing spicules of newly formed bone, indicating that more bone might have been created if the membranes had been retained longer. The current study thus showed that maximum bone formation around oral implants was created if the membrane augmentation material remained in place during the 16‐week healing period. Early removal of membranes, with or without elimination of the underlying tissues resulted, however. in less newly formed bone and an incomplete defect bone fill.
Titanium implant insertion into dog alveolar ridges augmented by allogenic material
Authors: Pinholt E. M. , Haanaes H. R. , Donath K. , Bang G.
Published: March 2003

The purpose of this investigation was to evaluate whether titanium endosseous implants would osseointegrate in dog alveolar ridges augmented by allogenic material. In 8 dogs en bloc resection, including 2 premolars, was performed bilaterally in the maxilla and the mandible. After a healing period of 6 weeks allogenic, demineralized and lyophilized dentin or bone was implanted subperiosteally. Titanium implants were installed 5.5 months later in some of the regions. Light and fluorescence microscopic evaluation revealed fibrous encapsulation of the implanted allogenic material, no osteoinduction and only minimal osteoconduction. few multi‐nuclear giant cells and a sparse inflammatory reaction. The titanium implants healed mainly by fibrous encapsulation.
Periotest® measurements and osseointegration of mandibular ITI implants supporting overdentures. A one‐year longitudinal study.
Authors: Mericske‐stern R. , Milani D. , Mericske E. , Olah A.
Published: March 2003

The Periotest values of mandibular implants, registered before and after loading by overdentures, were compared. Thirty edentulous patients with 60 Bonefit ITI implants were selected with an average age of 69 years. The Periotest values were measured 1) after a healing period of 3 months and 2) after the overdentures had been worn for a period of 12 months. Periodontal parameters were recorded at both examinations. Furthermore, 17 biopsies of mandibular bone taken from the implant sites during implant surgery were analyzed to assess the bone density. The histomorphometric evaluation was done using a point count method. At the end of the healing period. all registered Periotest values were negative, ranging from −1 to −8 with an average of 4.08. One year later, all measurements showed negative values again, ranging from −2 to −8 with an average of 4.97. The difference was statistically significant. Seventeen biopsies of mandibular bone were evaluated to determine the density. The range of bone density was from 22.4% and 90.9%. There was no correlation found between bone density and Periotest values. However, a significant correlation could be observed between mandibular atrophy and bone density.
The influence of abutment surface roughness on plaque accumulation and peri‐implant mucositis
Authors: Bollen Curd M. L. , Papaioanno William , Van Eldere Johan , Schepers Evert , Quirynen Marc , Van Steenberghe Daniel
Published: March 2003

Bacterial adhesion to intra‐oral, hard surfaces is firmly influenced by the surface roughness of these structures. Previous studies showed a remarkable higher subgingival bacterial load on rough surfaces when compared to smooth sites. More recently, the additional effect of a further smoothening of intra‐oral hard surfaces on clinical and microbiological parameters was examined in a short‐term experiment. The results indicated that a reduction in surface roughness below Ra=0.2 μm, the so‐called “threshold Ra”, had no further effect on the quantitative/qualitative microbiological adhesion or colonisation, neither supra‐ nor subgingivally. This study aims to examine the long‐term effects of smoothening immoral hard transgingival surfaces. In 6 patients expecting an overdenture in the lower jaw, supported by endosseus titanium implants, 2 different abutments (transmucosal part of the implant): a standard machined titanium (Ra=0.2 μm) and one highly polished and made of a ceramic material (Ra=0.06 μm) were randomly installed. After 3 months of intra‐oral exposure, supra‐ and subgingival plaque samples from both abutments were compared with each other by means of differential phase‐contrast microscopy (DPCM). Clinical periodontal parameters (probing depth, gingival recession, bleeding upon probing and Periotest‐value) were recorded around each abutment. After 12 months. the supra‐ and subgingival samples were additionally cultured in aerobic, CO,‐enriched and anaerobic conditions. The same clinical parameters as at the 3‐month interval were recorded after 12 months. At 3 months, spirochetes and motile organisms were only detected subgingivally around the titanium abutments. After 12 months, however, both abutment‐types harboured equal proportions of spirochetes and motile organisms, both supra‐ and sub‐gingivally. The microbial culturing (month 12) failed to detect large interabutment differences. The differences in number of colony forming units (aerobic and anaerobic) were within one division of a logarithmic scale. The aerobic culture data showed a higher proportion of Gram‐negative organisms in the subgingival flora of the rougher abutments. From the group of potentially “pathogenic” bacteria, only Prevotellu inter‐media and Fusobacterium nucleatum were detected after anaerobic culturing and again the inter‐abutment differences were negligible. Clinically, the smoothest abutment showed a slightly higher increase in probing depth between months 3 and 12, and more bleeding on probing. The present results confirm the findings of our previous short‐term study, indicating that a further reduction of the surface roughness, below a certain “threshold Ra”(0.2 μm), has no major impact on the supra‐ and subgingival microbial composition.
Evaluation of an endosseous titanium implant with a sandblasted and acid‐etched surface in the canine mandible: radiographic results
Authors: Cochran D. L. , Nummikoski P. V. , Higginbottom F. L. , Hermann J. S. , Makins S. R. , Buser D.
Published: March 2003

Previous studies have demonstrated in short‐term experiments that a sandblasted and acid‐etched (SLA) titanium implant had a greater bone‐to‐implant contact than a titanium plasma‐sprayed (TPS) implant in non‐oral bone. In the present study, an SLA implant was compared radiographically to a TPS implant under unloaded and loaded conditions in the canine mandible for up to 15 months. 69 implants were placed in 6 foxhounds. Standardized radiographs were taken at baseline, preload, 3, 6, 9, and 12 months of loading. Loaded implants were restored with gold crowns similar to the natural dentition. Radiographic assessment of the bone response to the implants was carried out by measuring the distance between the implant shoulder and the most coronal bone‐to‐implant contact (DIB) and by evaluation of bone density changes using computer‐assisted densitometric image analysis (CADIA). 5 different areas‐of‐interest (AOI) were defined coronally and apically along the implant. DIB measurements revealed that SLA implants had significantly less bone height loss (0.52mm) than TPS implants (0.69mm) at the preload evaluation (p=0.0142) as well as at 3 months of loading (0.73mm/1.06mm: p=0.0337). This difference was maintained between the implant types during the 1‐year follow‐up period. The same trend was also evident for CADIA measurements with SLA implants showing higher crestal bone density values when comparing preload to baseline data (p=0.0890) and 3 months to baseline data (p=0.0912). No measurable bone density changes were apparent in the apical areas of either implant. These results suggest that SLA implants are superior to TPS implants as measured radiographically in oral bone under unloaded and loaded conditions.
Bioactive glass and calcium carbonate granules as filler material around titanium and bioactive glass implants in the medullar space of the rabbit tibia
Authors: Turunen T. , Peltola J. , Helenius H. , Yli‐urpo A. , Happonen R.‐P.
Published: March 2003

The effect of bioactive glass (BG) and calcium carbonate (CC) granules on bone formation around titanium and BG implants projecting into the medullary space of rabbit tibia was studied. The bone marrow tissue was removed and the medullary space was filled either with BG or CC (Biocoral®) granules (0 630μ800 –m). Conical titanium and BG implants were inserted into the holes drilled in compact bone using the press fit technique. Histomorphometry was used to measure the bone‐biomaterial area in a 1.O mm wide zone around the head of the implant and the contact between formed bone and implant. Significantly larger bone‐biomaterial area was obtained around titanium implants using BG than CC granules while no difference was found in connection of BG implants. Better bone‐implant contact was achieved with BG implants than with titanium implants regardless of the type of granules used. The results indicate that BG may prove to be useful as filler and coating material in connection of implants projecting into bone cavities.
Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Evaluation of autogenous bone combined with porous hydroxyapatite.
Authors: Hürzeler Markus B. , Quifñones Carlos R. , Kirsch Axel , Schüpbach Peter , Krauβe Alex , Strub Jörg R. , Caffesse Raul G.
Published: March 2003

The aim of this study was to evaluate clinically, histologically, and histometrically the use of autogenous bone combined with porous hydroxyapatite (Interpore 200®) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted. After a healing period of 3 months. maxillary sinus augmentation procedures were performed in each monkey, and the sinuses were grafted with autogenous bone from the monkeys' tibia mixed in a 3:1 ratio with porous hydroxyapatite. At the same time. 2 pure titanium plasma‐sprayed IMZB cylinder implants were immediately placed into the augmented sinuses (i.e. simultaneous implants‐loaded group). After 4 months, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed implants‐loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold‐alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received similar treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants unloaded group and delayed implants unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation. The porous hydroxyapatite granules appeared integrated with the newly formed bone. Histometric analyses revealed that delayed implant placement resulted in a greater amount of direct mineralized bone‐to‐implant contact in the augmented area than the simultaneous implant placement. Furthermore, the percentage of direct mineralized bone‐to‐implant contact was far more significant in the residual bone than in the augmented area. It was concluded that the autogenous bone/porous hydroxyapatite graft combination enhanced bone formation and mineralized bone‐to‐implant contact in the augmented sinuses and that the delayed implant placement may be favorable for sinus augmentation procedures.
A 5‐year prospective clinical study of Astra Tech dental implants supporting fixed bridges or overdentures in the edentulous mandible
Authors: Makkonen Tuula A. , Holmberg Stig , Niemi Lief , Olsson Cecilia , Tammisalo Tapio , Peltola Juha
Published: March 2003

In a 5‐year prospective clinical study, 1.55 endosseous implants were installed in the mandible anterior to the mental foramina in 33 edentulous patients (13 males and 20 females). Usually 6 implants were installed for fixed prostheses (FP). 13 patients with 77 implants, and 4 implants for overdentures (OD) with a Dolder bar, 20 patients with 78 implants. At the time of abutment connection 1 implant in 2 patients was found to be loose and removed. However, in both these patients overdentures were successfully placed on the remaining 3 implants. Narrow‐beam radiography was used for radiological evaluation. The mean (SD) total marginal bone loss in 5 years was 0.48 (0.38) mm (0.36 (0.22) mm in the FP group and 0.56 (0.45) mm in the OD group). Very few complications were reported during the 5 years, most of them being related to the superstructures. The overall cumulative implant survival rate was 98.7%(100% in the FP group and 97.4% in the OD group). The survival rate of the superstructures was 100%. The present study has demonstrated that Astra Tech implants offer reliable and predictable medium‐term support for fixed prostheses and overdentures in the edentulous mandible.
Quantitative and qualitative investigations of surface enlarged titanium and titanium alloy implants
Authors: Han Chong‐hyun , Johansson Carina B. , Wennerberg Ann , Albrektsson Tomas
Published: March 2003

Screw shaped implants of commercially pure (c.p.) titanium and titanium‐6aluminum‐4vanadium (Ti6AI4V) were blasted with particles of TiO2 of mean sizes of 25 μm (Group I) and 7.5 μm (Group II) and inserted in rabbit bone for 3 months. The surface roughness of the implants was examined and quantified with an optical scanning 3‐dimensional instrument (TopScan 3D system), revealing the two alloy surfaces in each group had similar surface roughness. Biomechanical (removal torque) tests showed the c.p. titanium implants to be significantly more stable in the bone bed than those of Ti6AI4V. In Group I, the c.p titanium implants demonstrated a mean removal torque of 38 N cm while the Ti6AI4V demonstrated a mean removal torque of 27 Ncm (P=0.004). Group II implants revealed a mean removal torque of 70 Ncm for the c.p. ti and 50 Ncm for the alloy samples (P=0.003). The removal torque values were converted to shear forces/strengths by three calculation methods, based on (a) the entire length of the implant surface in the cortical region, (b) the thickness of the cortical bone measured in close vicinity to the thread peaks and *lpar;c) the bone‐metal contact length measured on the non‐unscrewed neighbouring implants. Group I: (a) the c.p. ti implants revealed a mean shear force of 4 vs a mean of 3 N/mm2 for the alloy samples. Shear strengths based on (b); were 8 for c.p. ti vs 6 N/mm2 for the alloy. The mean shear strength/force if calculated according to (c) revealed 23 for c.p. ti vs 18 N/mm2 for the alloy. Corresponding numbers for Group II; (a) cp. ti 8 compared to 6 N/mm2 for the alloy, (b) c.p. ti demonstrated a mean value of 17 vs 11 N/mm2 for the alloy. According to method (c); c.p. ti had a mean shear strength of 26 vs 22 N/mm2 for the alloy samples. Histomorphometrical comparisons were performed on 10 urn thick undecalcified ground sections in the light microscope. In both Group I and Group II, the calculations of the mean bone‐to‐metal contact demonstrated more bone in contact to the c‐p. titanium implants than to the Ti6AI4V ones. Whereas comparisons of the bone volume inside the threads demonstrated slightly higher bone volumes around the alloy samples, no statistically significant difference was obtained between the two materials histomorphometrically.
Adhesion of periodontal bacteria to titanium, and titanium alloy powders
Authors: Steinberg Doron , Sela Michael N. , Klinger Avigdor , Kohavi David
Published: March 2003

In this study, the adhesion of radioactively labeled Actinomyces viscosus (A.viscous), Actinobacillus actinomicetemcomitans (Aa) and Porphyomonas gingivalis (P gingivalis) to titanium (Ti) and Ti6Al4V alloy (Ti‐alloy) coated with albumin or human saliva was investigated. All the tested bacteria displayed greater attachment to Ti‐alloy than to Ti. P. gingivalis exhibited less adhesion to Ti and Ti‐alloy than did the other bacterial strains. Adhesion of A. viscosus and Aa was greatly reduced when Ti or Ti‐alloy were coated with albumin or saliva. P. gingivalis demonstrated a lesser reduction in adhesion to albumin or saliva‐coated surfaces. The results show that oral bacteria have different adhesion ffinities for Ti and Ti‐alloy and that both albumin and human saliva reduce bacterial adhesion.
Soft tissue response to plaque formation at different implant systems. A comparative study in the dog
Authors: Abrahamsson Lngemar , Berglundh Tord , Lindhe Jan
Published: March 2003

The aim of the present experiment was to study the location and composition of plaque associated lesions in the mucosa adjacent to implant systems that differed with respect to both geometry and dimension. At day 0 extraction of the mandibular premolars were performed. After a healing period of 3 months, fixtures of the Astra Tech Implants, Dental System®, the Brånemark System® and the ITI Dental Implant System® were installed. In each mandibular quadrant 1 fixture of each implant system was installed in a randomized order. A period of plaque control was initiated. Following another 3 months of healing, abutment connection was performed in the 2‐stage systems (the Astra Tech Implants, Dental System® and the Brånemark System®). After 1 month, the plaque control measures were abandoned and plaque formation was allowed for 5 months. The animals were killed and biopsies representing each implant region obtained. The tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. The present study demonstrated that plaque formation resulted in the establishment of an ICT lateral to a pocket epithelium. The lesion was found to be similar regarding extension and composition in the peri‐implant mucosa of the 3 implant systems tested. The vertical extension of the ICT was in all systems within 91–99% of the vertical dimension of the junctional epithelium. The marginal bone level, measured from the abutment/fixture (PS) border, did not differ between the three systems.
Evaluation of filling materials in membrane‐protected bone defects. A comparative histomorphometric study in the mandible of miniature pigs.
Authors: Buser Daniel , Hoffmann Britt , Bernard Jean‐pierre , Lussi Adrian , Mettler Daniel , Schenk Robert K.
Published: March 2003

In recent years, bone grafts and bone substitutes have been increasingly utilized underneath barrier membranes to optimize the treatment outcome of bone reconstructive therapy for defects in the alveolar process. In the present study, 4 different filling materials were evaluated in bone defects of similar dimensions in the mandible of miniature pigs. Blood clots and autografts were used as controls. The defects were covered with barrier membranes and allowed to heal for 4, 12 or 24 weeks. Histologic examination demonstrated that bone repair progressed through a programmed sequence of maturation steps closely resembling the pattern of bone development and growth regardless of whether bone grafts or substitutes were present or not. Histomorphometric analysis showed that autologous bone grafts (autografts) had the best osteoconductive properties during the initial healing period, with 39% of newly formed bone inside the membrane‐covered defects at 4 weeks of healing. In addition, 87% of the graft surfaces were already covered by bone at this time. Both values were significantly higher for autografts than for the 4 alternative bone fillers (P<0.05). At 12 weeks, these differences were no longer apparent, with all 5 filling materials showing similar values. Among the tested bone substitutes, tricalcium hosphate (TCP) showed a significantly higher percentage of bone fill at 24 weeks of healing. It can be concluded that sites filled with autografts clearly demonstrated the best results underneath barrier membranes in the early phase of healing. As far as degradation and substitution are cnncemed, TCP showed the most promising results. This filler, however, needs to be tested further in a more demanding animal model. Less favorable results were obtained for coral‐derived hydroxyapatite granules and for demineralized freeze‐dried bone allografts.
Unbiased stereological methods used for the quantitative evaluation of guided bone regeneration
Authors: Aaboe Merete , Pinholt Else Marie , Schou Seren , Hjörting‐hansen Erik
Published: March 2003

The present study describes the use of unbiased stereological methods for the quantitative evaluation of the amount of regenerated bone. Using the principle of guided bone regeneration the amount of regenerated bone after placement of degradable or non‐degradable membranes covering defects in rabbit calvaria was compared. Forty rabbits were divided into 5 groups. A titanium microplate was placed over the defect to prevent collapse of the membrane. The non‐degradable expanded polytetrafluoroethylene membrane and the degradable Polyglactin 910 material were both placed unicortically and bicortically. Undecalcified sections were prepared for stereologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. Unbiased stereologic estimates revealed 48% bone regeneration in defects covered by 2 e‐PTFE membranes, and 12% in defects covered by 2 Polyglactin 910 membranes. Defects covered by 1 e‐PTFE or Polyglactin 910 membranes revealed 10% or 18% bone regeneration, respectively. The control group regenerated 14%. The major difference of the estimates was caused by real difference between specimens, i.e. biologic variation, whereas only minimal variance was added by the stereologic estimation procedure.
The EsthetiCone™ abutment: three‐year results of a prospective multicenter investigation
Authors: Kastenbaum Fred , Lewis Steve , Naert Lgnace , Palmquist Camilla
Published: March 2003

The EsthetiCone™ abutment, designed for subgingival restorative margins, makes it possible to achieve ideal esthetics, function, and predictability. This study included 200 EsthetiCone abutments placed in 50 partial or complete edentulous patients participating in a multicenter study performed in Europe and the United States. The patients were followed for 3 years and the marginal bone level of the implants was determined from intra‐oral radiographs. During the follow‐up period, a total of 9 of patients were withdrawn from the study. Based on the remaining patients, a total of 164 EsthetiCone abutments (82%) were evaluated through the 3‐year follow‐up visit. Only 1 EsthetiCone abutment failed during the study period, resulting in a cumulative success rate of 99.2% in the maxilla and 100% in the mandible after 3 years. No bone loss due to the usage of short abutment collars (1 mm) was seen in this study. The marginal bone resorption during the 3‐year period did not exceed 1 mm as a mean neither for the 1 mm nor the higher abutments when analyzed separately. During the follow‐up period, few complications were reported and they were all easily rectified without compromising the treatment success. The outcome of this study indicates that safe long‐term and esthetically good results can be achieved when the Brånemark implants are loaded with EsthetiCone abutments. The reported need of a 3 mm peri‐implant sulcus with an animal model was not confirmed with patients in this study.
Characterization of the interface between prefabricated gold copings and cast dental alloy in implant restorations
Authors: Carotenuto Gianfranco , Palumbo Maria , Zarone Fernando , Nicolais Luigi
Published: March 2003

The objective of this study was to analyse the characteristics of the metal interface between the casting of a dental noble alloy and prefabricated gold copings (OCTA ITI Implant System) after the fabrication procedures of a prosthetic implant‐retained superstructure. The microscopical investigation, performed by optical microscopy (OM) and scanning electron microscopy (SEM). of the region around the cylinder after the casting process and the subsequent porcelain firing procedures showed the presence of an ideal interface, including: i) maintenance of coping and casting alloy microstructures up to the interface, and ii) absence of interfacial reaction products. A low content of porosity (less than 3% by volume in average( was observed in the casting alloy bulk as well as at interface. The investigation by energy‐dispersive spectroscopy (EDS) of the alloy composition close to the interface showed the presence of a minimal elemental interdiffusion. suggesting that an adequate compatibility between alloy and coping characterized the materials used. A small decrease of the prefabricated coping hardness was also observed after the casting 1 and porcelain firing procedures.
An assessment of the accuracy of ridge‐mapping in planning implant therapy for the anterior maxilla
Authors: Allen Finbarr , Smith David G.
Published: March 2003

The use of ridge‐mapping to assess bone levels available for implant placement in the anterior maxilla avoids some of the problems associated with CT scanning. The aim of this study was to assess the accuracy of ridge‐mapping callipers in determining bony ridge widths in the anterior maxilla prior to dental implant surgery. A modified surgical stent was designed to locate the beaks of ridge‐mapping callipers at the same points on the jaw before and after mucoperiosteal flap reflection. Eleven subjects were included in the study. Measurements (n=100) were made at 25 implant sites, 50 “pre‐operative” and 50 “intra‐operative” at 3 mm and 6 mm distances from the crest of the ridge. There were statistically significant (P<0.0001) differences between pre‐ and intra‐operative measurements. Based on pre‐operative measurements, clinical judgements were made as to whether supplementary procedures such as guided bone regeneration would be required. Unanticipated supplementary procedures were required at 10 fixture sites. The findings indicate that ridge‐mapping alone is insufficient to accurately predict bone available for implantation in the anterior maxilla. It is suggested that ridge‐mapping may provide reliable information about bone levels when the labial aspect of the anterior ridge is not markedly concave.
Behavior of implants in bone grafts or free flaps after tumor resection
Authors: Chiapasco Matteo , Abati Silvio , Ramundo Giuseppe , Rossi Alessandro , Romeo Eugenio , Vogel Giorgio
Published: March 2003

The authors compared bone resorption of autogenous bone grafts and revascularized free flaps used for the reconstruction of mandibular continuity defects following resection for tumors, before and after the placement of endosseous implants. Ten patients (group 1) were treated with autogenous bone grafts taken from the fibula or the anterior iliac crest; 8 patients (group 2) were treated with iliac or fibula revascularized flaps. Four to 8 months later, 72 endosseous implants were placed in the reconstructed areas. After a further healing period of 4–6 months, patients were rehabilitated with implant‐borne prostheses. The following parameters were evaluated and compared between the two groups: 1) bone resorption of grafts and free flaps before and after implant placement; 2) peri‐implant bone resorption mesial and distal to each implant, immediately after prosthetic rehabilitation and then during yearly follow‐ups. Bone resorption before implant placement showed mean values of 3.53 mm in group 1, and 0.96 mm in group 2. Peri‐implant bone resorption was: 0.49 mm (39 implants) in group 1, and 0.45 mm (30 implants) in group 2, at time of prosthetic rehabilitation; 0.78 mm (39 implants) in group 1, and 0.89 mm (30 implants) in group 2, 12 months after prosthetic load; 1.16 mm (24 implants) in group 1, and 1.02 mm (13 implants) in group 2, 24 months after the prosthetic load. A significant difference in bone resorption before implant placement was found between the two groups, whereas it was not found after implant placement and prosthetic load. The failure rate according to Albrektsson criteria was 4.9% (2/41 implants) in group 1, and was 3.2% (1/31) in group 2.
Anatomical aspects of sinus floor elevations
Authors: Van Den Bergh Johan P. A. , Ten Bruggenkate Christiaan M. , Disch Frans J. M. , Tuinzing D. Bram
Published: March 2003

Inadequate bone height in the lateral part of the maxilla forms a contra‐indication for implant surgery. This condition can be treated with an internal augmentation of the maxillary sinus floor. This sinus floor elevation, formerly called sinus lifting, consists of a surgical procedure in which a top hinge door in the lateral maxillary sinus wall is prepared and internally rotated to a horizontal position. The new elevated sinus floor, together with the inner maxillary mucosa, will create a space that can be filled with graft material. Sinus lift procedures depend greatly on fragile structures and anatomical variations. The variety of anatomical modalities in shape of the inner aspect of the maxillary sinus defines the surgical approach. Conditions such as sinus floor convolutions, sinus septum, transient mucosa swelling and narrow sinus may form a (usually relative) contra‐indication for sinus floor elevation. Absolute contra‐indications are maxillary sinus diseases (tumors) and destructive former sinus surgery (like the Caldwell–Luc operation). The lateral sinus wall is usually a thin bone plate, which is easily penetrated with rotating or sharp instruments. The fragile Schneiderian membrane plays an important role for the containment of the bonegraft. The surgical procedure of preparing the trap door and luxating it, together with the preparation of the sinus mucosa, may cause a mucosa tear. Usually, when these perforations are not too large, they will fold together when turning the trap door inward and upward, or they can be glued with a fibrin sealant, or they can be covered with a resorbable membrane. If the perforation is too large, a cortico‐spongious block graft can be considered. However, in most cases the sinus floor elevation will be deleted. Perforations may also occur due to irregularities in the sinus floor or even due to immediate contact of sinus mucosa with oral mucosa. Obstruction of the antro‐nasal foramen is, due to its high location, not a likely complication, nor is the occurrence of severe haemorrhages since the trap door is in the periphery of the supplying vessels. Apart from these two aspects, a number of anatomical considerations are described in connection with sinus floor elevation.
Characterization, at the bone crystal level, of the titanium‐coating/bone interfacial zone
Authors: Leize Elisabeth‐Marie , Hemmerlé Joseph , Leize Maurice
Published: March 2003

Well integrated and clinically functional titanium dental implants retrieved in humans after 14 and 40 months of settlement were used for the characterization of the interfacial area between the plasma‐sprayed coating and the surrounding mineralized bone. Electron microscopic studies were performed from undecalcified intact coating/bone interfaces. The concomitant presence of direct bone tissue apposition on the titanium coating, as well as the interposition of amorphous material along the same interfacial zones emphasizes the dynamic biologic aspect of the osseointegration process. A very striking finding of these ultrastructural and microanalytical investigations was the presence of tiny titanium grains ranging from 5 to 50 nm in diameter at the surface of bulky plasma‐sprayed coating particles. High‐resolution transmission electron microscopy revealed a continuity between the lattice planes of the coating material and those of the minute titanium grains; thus indicating a chemical binding. The thickness of the granular titanium layer interposed between coating particles and mineralized bone tissue ranged up to 600 nm. The observation of calcium‐phosphate needle‐like crystallites within the porous layer made of titanium grains indicates a bone ingrowth process, suggesting a bone‐binding mechanism to the outer surface of the coated titanium implant.
Oblique lateral cephalometric radiographs of the mandible in implantology: usefulness and reproducibility of the technique in quantitative densitometric measurements of the mandible in vivo
Authors: Verhoeven Jan Willem , Ruijter Jan , Cune Marco Stephan , Terlou Maarten
Published: March 2003

In the literature intraoral periapical radiographs are commonly used for densitometric measurements of the mandible with implants. These films give detailed information of the implant and the surrounding bone. However, in extreme mandibular atrophy it can be difficult to obtain intraoral radiographs of adequate diagnostic quality. Extraoral Oblique Lateral Cephalometric Radiographs (OLCRs) can then be the alternative: reproducible images of large parts of the mandible can be obtained. In vitro, the results of densitometry using periapical films and OLCRs were shown to be similar. The present study aims to determine the measurement error of densitometry with OLCRs in vivo. In 16 patients (group I) with atrophic mandible and implants, duplicate OLCRs of one side of the jaw were obtained. The error of measurement for the densitometric measurements of the mandibular bone was 5.5%. The use of a specially developed correction program to compensate for undesired variations in the projection of the soft tissues of the face (tongue, lips, cheek and neck) on the radiographs resulted in a 40% reduction of that measurement error to 3.5%. This remaining error is mainly brought about by an imperfect repositioning of the patient when the duplicate OLCRs are obtained. The error caused by the image acquisition, processing and measurement is less than 1%. Deliberate variation up to 7.5 degrees of the horizontal angle wherein the OLCRs are made, results in a large error of measurement of 13.5% (group II: 17 patients). To reduce this variation the additional soft tissue correction program is unsuitable. It is concluded from this study that the described radiographic and image analysis technique is a promising tool for prospective densitometric studies of the mandible with or without implants. Especially in mandibles with bone grafts and implants, substantial changes in the graft can occur. The described technique may be particularly valuable in analyzing these changes.
Displacement of the incisive foramen in conjunction with implant placement in the anterior maxilla without jeopardizing vitality of nasopalatine nerve and vessels: a novel surgical approach
Authors: Artzi Zvi , Nemcovsky Carlos E. , Bitlitum Ilan , Segal Pnina
Published: March 2003

Accurate implant placement in the anterior maxilla is essential in achieving optimal prosthetic rehabilitation with proper function and acceptable esthetic and phonetic demands. One of the preferable prosthetic solutions to restore a missing maxillary incisor in young adults is by an implant‐supported crown. Bone resorption together with an enlarged incisive foramen, challenge proper implant placement. A simultaneous procedure where the implant osteotomy site penetrated the incisive canal is presented. A configurated cortico‐cancellous block graft core was adjusted to fit the foramen while its soft tissue content was pushed back posteriorly but not removed. This procedure was followed by an immediate implant placement. Re‐entry at 9 months revealed solid bone support embracing the implant body. Although the size of the incisive foramen diminished significantly, the nasopalatine branches were still evident. No complications and/or loss of sensation were observed.
Maxillary sinus floor augmentation using bioactive glass granules and autogenous bone with simultaneous implant placement
Authors: Cordioli Giampiero , Mazzocco Carlo , Schepers Evert , Brugnolo Enzo , Majzoub Zeina
Published: March 2003

Abstract: This clinical study was undertaken to: 1) evaluate the use of bioactive glass BiogranTM combined with autogenous bone as grafting material for maxillary sinus augmentation with simultaneous implant placement using radiography and histology; and 2) document the short‐term post‐loading success of implants inserted in sinus cavities augmented with this material. Unilateral or bilateral sinus augmentation was performed in 12 patients with 3–5 mm of alveolar crestal bone height in the posterior maxilla prior to grafting. The sinuses were grafted with bioactive glass mixed in a 4:1 ratio with autogenous bone. Simultaneously, 2–3 threaded titanium implants were inserted into the augmented sinuses. Second stage surgery was carried out 9 to 12 months post implantation. At abutment connection, 10 core biopsy specimens were taken from different grafted sites and evaluated histologically. All 27 implants were clinically stable at second stage surgery. A mean increase in mineralized tissue height of 7.1±1.6 mm was evident when comparing the pre‐surgical CT scans with those performed 9–12 months following the sinus augmentation procedure. Evaluation of the cores yielded a mean of 30.6±5.7% of bone tissue in the grafted sites. One implant failed during the prosthetic phase while the remaining 26 implants were stable 12 months post loading. This study suggests that BiogranTM/autogenous bone graft combination used in one‐stage sinus augmentation yields sufficient quality and volume of mineralized tissue for predictable simultaneous implant placement in patients with 3–5 mm of bone height prior to grafting.
The effects of fixed and removable implant‐stabilised prostheses on posterior mandibular residual ridge resorption
Authors: Wright Paul S. , Glantz Per‐Olof , Randow Kjell , Watson Roger M.
Published: March 2003

Abstract: This study investigated the change over time in the area of the posterior mandibular residual ridge in patients wearing either i) mandibular overdentures stabilised by two implants (Brånemark System; Nobel Biocare, Göteborg, Sweden) connected by a bar, or ii) mandibular fixed cantilever prostheses stabilised on five or six implants. Proportional measurements were made in order to compare the area of the residual ridge with an area of bone uninfluenced by resorption. Measurements were made by digitising tracings of panoramic radiographs that were taken shortly after implant insertion and up to seven years later. With the use of overdentures, the posterior bone area index reduced by a mean of 1.1% per annum, while a mean bone area index increase of 1.6% per annum was demonstrated in association with fixed prostheses. A multiple linear regression model was fitted to predict the change in posterior area from type of prosthesis, gender, age, years of edentulism and initial height of the mandible. The model was only significant for initial height of mandible (P = 0.04) and type of prosthesis (P = 0.0001). In conclusion, patients rehabilitated with implant‐stabilised mandibular overdentures demonstrated low rates of posterior mandibular residual ridge resorption, while patients rehabilitated with implant‐stabilised mandibular fixed cantilever prostheses demonstrated bone apposition in the same area.
Tooth–implant connection: some biomechanical aspects based on finite element analyses
Authors: Menicucci Giulio , Mossolov Alexei , Mozzati Marco , Lorenzetti Massimo , Preti Giulio
Published: March 2003

Abstract: This study investigated, with the use of two‐ and three‐dimensional finite element analysis, the peri‐implant stress that occurred during loading of a tooth that was rigidly connected to a distally placed implant. A fixed bond between the bone and the implant was assumed, while the periodontal ligament was represented by means of three‐dimensional nonlinear visco‐elastic spring elements. Two different loading conditions were compared in the study: i) an axially directed static load of 50 kg that was applied to the tooth for 10 s, and ii) a transitional load of 50 kg that was applied for 5 milliseconds. Load duration appeared to have a greater influence than load intensity on the stress distribution in the bone around an implant and a rigidly connected tooth. Static load is, therefore, potentially more harmful for peri‐implant bone than transitional load. The periodontal ligament seems to play a key role in the stress distribution between a tooth and a rigidly connected implant.
Mandibular flexure and stress build‐up in mandibular full‐arch fixed prostheses supported by osseointegrated implants
Authors: Zarone Fernando , Apicella Antonio , Nicolais Luigi , Aversa Raffaella , Sorrentino Roberto
Published: March 2003

Abstract: The biomechanical effect of mandibular functional flexure on stress build‐up in implant‐supported fixed restorations is discussed. The relative deformations and stress distributions in six different designs of implant‐supported prosthetic systems (six or four implants, with or without distal cantilevers, cross‐arch or midline‐divided bar into two free‐standing bridges) were analysed by a three‐dimensional finite element (FE) model of a human edentulous mandible. A significant amount of stress in the more distal implants and the superstructure at the symphysis arises as a consequence of mandible functional flexure. The analysis of the stress distributions generated by the different restorative patterns suggests that a division of the superstructure at the level of the symphysis significantly restores the natural functional flexure of the mandible.
Evaluation of accuracy and variability of scoring‐area‐based plaque indices
Authors: Shaloub A. , Addy M.
Published: March 2003

Background: Plaque scoring, using a variety of indices and methods, is widely used in clinical dentistry. There is limited information on inter‐ and intra‐examiner variability and almost no data on examiner accuracy.

Aims:

The aim of this study, was to determine the inter‐ and intra‐examiner variability and accuracy of 15 examiners, of differing plaque‐scoring experience, in recording and judging plaque areas from simulated plaque on tooth charts.

Methods: Plaque, shaded red, was drawn onto tooth charts of 8 simulated “patients” and measured by planimetry by 1 investigator. For each tooth for each “patient”, examiners subjectively copied the plaque onto blank charts and scored plaque in 5% increments for the global plaque index. This was repeated on 2 occasions. Drawn plaque areas were determine by the investigator and comparisons made with the actual areas and % scores of plaque.

Results: For both plaque recording methods, intra‐examiner variability was low and slighly better than inter‐examiner variability. Reproducing plaque areas showed a high level of accuracy in most examiners, as was judging areas in 5% increments, albeit slightly less accurate than area drawing. Overall examiner experience had little influence on judging plaque areas.

Conclusion: The data suggest that area‐based plaque indices can be scored or recorded accurately and with minimal variability within or between examiners. The laboratory model could be used to train and assess examiners.
Anticalculus agents
Authors: Fairbrother K. J. , Heasman P. A.
Published: March 2003

Most dentifrices and some mouthrinses now contain 1 or more active anticalculus agents to achieve so‐called tartar control. The aim of this article is to review the research associated with the development of anticalculus agents and to evaluate in some detail, the efficacy of those agents which are currently available in dentifrice products.
Periodontal treatment of rapid progressive periodontitis in 2 siblings with Papillon‐Lefèvre syndrome: 15‐year follow‐up
Authors: De Vree H. , Steenackers K. , De Boever J. A.
Published: March 2003

Aims: This paper reports the treatment of the periodontal component of the Papillon‐Lefèvre syndrome in 2 siblings (case A, born 1974; case B, born 1976).

Method: The initial treatment, in 1982, consisted of extraction of all primary teeth, scaling and rootplaning of the erupted permanent teeth and systemic antibiotic therapy. During 15 years, continuous and intensive periodontal treatment consisted of chlorhexidine 0.2% rinses, bi‐weekly professional prophylaxis, scaling and rootplaning or surgery if indicated. Systemic antibiotics often accompanied mechanical therapy after bacteriological analysis.

Results: In case A, a favourable number of permanent teeth could be maintained, but in case B, all permanent teeth were lost in spite of the intensive treatment. Darkfield microscopy at different intervals revealed high numbers of spirochetes and motile rods in both siblings. Only in case A were they temporarily reduced to zero after scaling and rootplaning combined with metronidazole. Anaerobic cultering revealed high numbers of Actinobacillus actinomycetemcomitans (A.a) in both patients. In 1994, 2 years after combined amoxicillin/metronidazole therapy, no A.a could be detected in case A. In case B, A.a could still be detected and was found to be resistant to metronidazole. One year after extraction of all permanent teeth, could no A.a be detected in case B.

Conclusion: Intensive periodontal treatment combined with antibiotic therapy was not able to prevent complete tooth loss in case B. In case A, the treatment was more effective, resulting in preserving a number of permanent teeth in a stable clinical situation. In these 2 cases, no attempt was made to create an edentulous period between the periodontally‐diseased mixed dentition and the eruption of the remaining teeth, which may have contributed to treatment failure.