bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency doubling perimetry in ocular hypertension and chronic open angle glaucoma
Authors: Cellini M. , Torreggiani A.
Published: March 2003

The authors have studied the reliability of frequency doubling perimetry (FDP) in screening glaucomatous disease and in ocular hypertension. The study was made on 30 patients affected by chronic simple open‐angle glaucoma (COAG) and 30 patients with ocular hypertension. MD and PSD variations were evaluated after a W/W perimetry and after FDP. In the COAG patients, FDP confirmed the perimetric alterations found by the W/W method. In the ocular hypertensive patients, with FDP we found a significant PSD increase over that found by the W/W technique: 4.051 ± 0.822 against 2.501 ± 0.928 (P < 0.001). FDP can therefore be put forward as a valid instrument for screening even precocious perimetric defects.
Intraocular pressure and progression of visual field damage
Authors: Brogliatti B. , Rigault R. , Palanza L. , Savio E. , Rolle T. , Fea A. , Boggio Merlo S.
Published: March 2003

Contradicting results concerning IOP control and visual field deterioration are presented. Some of these inconsistencies may be due to the statistical method of analysis. Sixty POAG patients with a perimetric follow‐up over 3 years were selected. Mean and maximum IOPs were considered during the same period. The patients were divided into two groups according to the IOP control (well controlled or poorly controlled). Visual field progression was defined as a reduction in sensitivity over the fifth percentile in more than four points. Mean IOPs were not significantly different in the group of patients with a visual field deterioration compared to the stable ones, but the percentage of patients with a visual field deterioration was significantly higher in patients with higher IOPs. This holds especially true if IOP below 16 mmHg (G) is considered the ‘target pressure’. IOP reduction seems to play an essential role in visual field progression. In glaucomatous patients, a strict (<16 mmHg (G)) might be necessary.
Comparison of factors potentially related to the occurrence of dental erosion in high‐ and low‐erosion groups
Authors: Johansson Ann‐Katrin , Lingström Peter , Birkhed Dowen
Published: March 2003

Soft drink intake, method of drinking, pH variations, plaque topography, and various salivary, microbial and clinical factors were compared in Saudi men with high (n=10, x̄=20.5 yr) and low (n=9, x̄=20.3 yr) dental erosion. pH‐measurements were carried out with a microtouch electrode at six different intraoral locations after the subjects had consumed 330 ml of regular cola‐type drink in their customary manner. The results showed that higher intake of cola‐type drinks was more common in the high‐ (253 l yr−1) than in the low‐erosion group (140 l yr−1). High erosion was associated with a method of drinking whereby the drink was kept in the mouth for a longer period (71 s vs. 40 s). pH after drinking did not differ between the groups for any of the six measuring sites. Plaque accumulation on the palatal surfaces of maxillary anterior teeth and urea concentration in unstimulated saliva were lower in high‐erosion subjects. Aside from these, there were no differences in salivary and microbial factors between the groups. First molar cuppings, buccal cervical defects, and mouth breathing were more common in the high‐ than in the low‐erosion group. In summary, consumption of cola‐type drink, method of drinking, amount of palatal plaque on anterior teeth, and salivary urea concentration are factors associated with dental erosion.
Sequential expressions of MMP‐1, TIMP‐1, IL‐6, and COX‐2 genes in induced periapical lesions in rats
Authors: Lin Sze‐Kwan , Kok Sang‐Heng , Kuo Mark Yen‐Ping , Wang Tzu‐Jou , Wang Jeng‐Tzung , Yeh Flora Tzu‐Chin , Hsiao Michael , Lan Wan‐Hong , Hong Chi‐Yuan
Published: March 2003

To elucidate the pathogenesis of periapical lesion‐associated bone resorption, a disease model of Wistar rat molar was employed. After lesion induction, the mRNAs encoding for matrix metalloproteinase‐1 (MMP‐1), tissue inhibitor of metalloproteinase‐1 (TIMP‐1), interleukin‐6 (IL‐6), and cyclooxygenase‐2 (COX‐2) in the developing lesions were detected by in situ hybridization at day 5, 10, 15 and 20, respectively. At day 5, MMP‐1, IL‐6 and COX‐2 mRNAs appeared predominantly in macrophages. During day 15 to day 20, increased expressions of these mediators were also found in osteoblasts but to a lesser extent compared with those in macrophages. MMP‐1 mRNA was also detected in osteoclasts. In contrast, expression of the TIMP‐1 gene was noted primarily in osteoblasts and was less pronounced compared with that of MMP‐1. The mediator‐expressing cells aggregated in the vicinity of bone resorption areas and their numbers increased with time. These data suggest that macrophages and osteoblasts are involved in the development of periapical lesions, and that they promote bone resorption by producing MMP‐1, IL‐6 and COX‐2. In addition, administration of a specific COX‐2 inhibitor, meloxicam, reduced the extent of periapical bone resorption by 43% and simultaneously diminished the numbers of cells synthesizing MMP‐1 and IL‐6 mRNAs. These results further elucidate the significance of COX‐2 in disease progression of periapical lesions as it modulates indirectly the production of MMP‐1 and IL‐6.
Actinobacillus actinomycetemcomitans proportion of subgingival bacterial flora in relation to its clonal type
Authors: Lakio Laura , Kuula Heidi , Dogan Basak , Asikainen Sirkka
Published: March 2003

We investigated whether certain Actinobacillus actinomycetemcomitans clones occur in elevated proportions in subgingival flora, and if the proportions relate to other bacteria in the samples. A total of 121 A. actinomycetemcomitans strains from 121 patients with periodontitis were serotyped and 60 strains were also genotyped. The 121 strains were divided into three groups and the 60 strains into two groups according proportion of A. actinomycetemcomitans. The samples from the 60 patients with genotyped strains were cultured for five other species. Among the 121 strains, serotype b occurred significantly more frequently in the high‐ (n=14, proportions >5%, mean=18.09, SD=20.07%) than low‐ (n=49, proportions ≤0.1%, mean=0.04, SD=0.03%) or intermediate‐proportion groups (n=58, proportions >0.5%, mean=1.31, SD=1.24%). Genotype 3 occurred significantly more frequently in samples with low A. actinomycetemcomitans proportions (n=28, ≤0.1%, mean=0.04, SD=0.03%) than in those with high proportions (n=32, >0.1%, mean=5.70, SD=14.60%) . No differences were seen in the detection frequencies or proportions of the five bacterial species between the samples with low or high A. actinomycetemcomitans proportions. The results indicate that certain clonotypes of A. actinomycetemcomitans may preferentially occur as low proportions, suggesting their controlled growth. Conversely, some serotype b clones may have a competitive advantage in subgingival flora.
Accuracy of computer‐automated caries detection in digital radiographs compared with human observers
Authors: Wenzel Ann , Hintze Hanne , Kold Louise Mejlhede , Kold Simon
Published: March 2003

The aim of this study was to compare diagnostic accuracy of a caries detection program with that of human observers. A total of 190 extracted teeth were radiographed with two Trophy RVG (RadioVisioGraphy) digital sensor systems. Four observers scored the approximal surfaces in all images on a disease severity scale. Each observer thereafter used the Logicon Caries Detector (LCD) program to analyse the surfaces in the digital images and recorded their outcome. To determine the true absence or presence of caries, histological validation was used. Sensitivities, specificities, positive and negative predictive values were calculated and differences between the diagnostic methods tested. Specificities for the outcome with the LCD were significantly lower for three observers than when they themselves assessed the RVG images and, correspondingly, the positive predictive values were lower for the LCD outcome for three of the observers. Sensitivity was also lower for two observers on the diagnostic threshold caries in dentine. It was concluded that the automated caries detection program is less accurate than human observers in detecting approximal caries lesions.
Effects of magnetic cell separation on monocyte adhesion to endothelial cells under flow
Authors: Nohé Boris , Zanke Christof , Johannes Tanja , Kiefer Thomas , Dieterich Hans‐Jürgen
Published: March 2003

Studies on monocyte adhesion are frequently limited by spontaneous changes of CD11b and CD62L during cell purification. Most isolation protocols for flow cytometric analysis that overcome this problem cannot be used when large numbers of living cells are needed for functional adhesion assays. This study investigated whether magnetic cell separation of monocytes with a paramagnetic bead against CD33 is a feasible method combining high yield with a low degree of spontaneous activation. As determined by flow cytometry, isolation of magnetically tagged monocytes at 4 °C did not alter the expression of CD11b and CD62L when compared to whole blood controls. Warming the cells slowly to room temperature immediately before starting the adhesion assay in a parallel plate flow chamber at 37 °C prevented further upregulation of adhesion molecules due to rewarming. When adhesion of magnetically tagged monocytes was compared with untouched monocytes that had been isolated via depletion of contaminating leukocytes, videomicroscopy showed that labelling CD33 neither affected rolling nor firm adhesion to human umbilical venous endothelial cells under flow. Finally, the subsequent upregulation of tissue factor expression on adherent monocytes indicates that magnetically separated monocytes responded properly to activating stimuli during cell adhesion. We conclude that magnetic cell separation via CD33 represents a feasible method for cell separation whenever large numbers of non‐activated monocytes are needed for adhesion assays under flow.
Low prevalence of Bartonella henselae infections in Norwegian domestic and feral cats
Authors: Bergh K. , Bevanger L. , Hanssen I. , Løseth K.
Published: March 2003

Bartonella henselae is the causative agent of cat scratch disease (CSD). This clinical entity is very rarely encountered in human medical practice in Norway. B. henselae infections including bacteraemia in cats have been frequently reported. The objective of the present study was to investigate the seroprevalence rate and the degree of B. henselae bacteraemia in Norwegian domestic and feral cats. One hundred cats investigated at a small animal veterinary practice in the middle of Norway were included in the study. Blood collected in Isolator blood‐lysis tubes and lysates of erythrocytes after freezing and thawing were cultured. PCR analysis of whole blood was also performed. Serology was performed by indirect fluorescence assay (IFA) and enzyme immunoassay (EIA) using immobilised B. henselae Houston‐1 strain as antigen. None of the 100 cats investigated was found to be bacteraemic. All 100 cats were seronegative when analysed by IFA; one cat was positive by EIA. The discrepancy between IFA and EIA of this particular cat is probably due to cross‐reactive antibodies. Contrary to findings reported from several geographic regions, B. henselae infections in Norwegian cats appear to be virtually absent. This in turn may explain why CSD has not been reported in human medical practice in Norway.
Numerical evaluation of minimal biochemical test combinations for the identification of Enterobacteriaceae species
Authors: Kronvall Göran , Hagelberg Annika
Published: March 2003

Species identification of 572 clinical isolates of Enterobacteriaceae was determined using an in‐house biochemical test panel and API 20E. The overall agreement was 82.7 per cent. When a numerical identification programme for Enterobacteriaceae was used to analyze the results of 440 E.coli isolates, the agreement with API 20E increased from 81.4 to 91.1 per cent. Numerical identification was then employed to evaluate 14 routine biochemical test panels used in 12 Swedish laboratories, and an additional 18 potential new test panel variants. The theoretical identification power of the panels was measured by a scoring system, based on simulated test results for the 14 most common species of Enterobacteriaceae. The results showed wide variations in the performance of different panels, with a number of panels being of insufficient quality. Among the 32 test panels, 6 panels indicated excellent performance. These should be further evaluated for routine laboratory performance. Numerical identification methods constitute powerful tools in the hands of the clinical microbiologist to aid in species identification as well as to analyze the quality of identification charts in use.
Different effects of chloroquine and hydroxychloroquine on lysosomal function in cultured retinal pigment epithelial cells
Authors: Sundelin Staffan P. , Terman Alexei
Published: March 2003

Although relatively rare, retinopathy based on a disturbed metabolism of the retinal pigment epithelium (RPE), with ensuing degeneration of photoreceptors, is a known complication of treatment with the 4‐aminoquinolones, chloroquine (CQ) and hydroxychloroquine (HCQ), in autoimmune diseases. The reported frequency of retinopathy, however, is much lower for HCQ than for CQ (less than 0.08% versus 1–2%). To test whether the difference in toxicity between the two lysosomotropic drugs is related to different lysosomal influence, we exposed confluent RPE cell cultures to CQ or HCQ for 2 weeks. To induce lipofuscin (LF) formation, known to be accelerated by increased lysosomal pH and intra‐lysosomal oxidation during degradation of auto‐/heterophagocytosed material, such treatment was combined with feeding of cells with photoreceptor outer segments (POS) and hyperoxia (40% ambient oxygen). HCQ was found to be a less potent enhancer of lipofuscinogenesis compared to CQ, apparently due to its less effective inhibition of lysosomal degradative capacity (evaluated by vital staining of lysosomes with Lyso Tracker Red, and periodic acid‐Schiff reaction). This conclusion is supported by the fact that NH4Cl, a non‐fluorescent substance which acts similarly to 4‐aminoquinolones, induced an increase in LF fluorescence paralleled by increased periodic acid‐Schiff reactivity of RPE cells.
Suppression of antigen‐specific lymphocyte proliferation by Gram‐positive bacterial cell walls
Authors: Chen Tong , Toivanen Paavo , Vainio Olli
Published: March 2003

It is largely unknown how bacterial cell walls (BCW) modulate human immune responses. In the present work the effect of Gram‐positive BCW on lymphocyte proliferation responses towards several microbial antigens (Ag) or mitogens was studied. Gram‐positive BCW were derived from four indigenous bacterial strains and from one pathogen (Streptococcus pyogenes). All BCW preparations used non‐specifically suppressed the proliferation responses of peripheral blood mononuclear cells (PBMC) against bacterial and viral Ag, but not against mitogens. Both lymphocytes and macrophages or their secreted products mediated the suppressive effects of BCW, which were not IL‐10 dependent. Furthermore, the expression of HLA‐DR and CD86 on monocytes/macrophages was downregulated by BCW. Unlike in LPS‐induced suppression, the CD14 pathway was not used by BCW of Lactobacillus casei (L.c.). The observed results indicate that Gram‐positive BCW suppress antigen‐specific lymphocyte proliferation through several mechanisms. This non‐specific immunosuppression might be a general function of BCW in the bacteria‐host interaction, being of importance for bacterial survival and pathogenicity.
A removal torque and histomorphometric study of commercially pure niobium and titanium implants in rabbit bone
Authors: Johansson C. B. , Albrektsson T.
Published: March 2003

Screw‐shaped commercially pure (c.p.) niobium and c.p. titanium implants were inserted in rabbit bone. After a healing period of 3 months, a significantly higher removal torque was demonstrated to unscrew the niobium implants (average 32.9 Ncm) compared to the c.p. titanium implants (average 25.3 Ncm). In the histomorphometric part of the study, there were no significant differences in bone‐to‐metal contact between the 2 implant materials. An average of 41.1% bony contact was demonstrated for the niobium screws compared to an average of 37.2% for the c.p. titanium ones. Our removal torque findings could be related to the differences that we observed between the 2 implant surfaces as indicated by SEM. Since niobium implants showed a more irregular surface topography and niobium is a softer metal than c.p. titanium, this seems the most probable reason for the differences observed in removal torque between the 2 metals. Hypothetically, a more “positive biocom‐patibility” of the c.p. niobium in comparison to the c.p. titanium remains as another possible reason for the observed differences. However, against such a difference in biocompatibility between c.p. niobium and c.p. titanium, there is the very similar amount of bony contact registered 1 in the histomorphometric analysis.
Surgically modelled reduced ridge in the beagle dog
Authors: Kohavi D. , Pollack S. R. , Brighton G. , Bulkin B.
Published: March 2003

A reproducible surgical method for the production of reduced alveolar ridge in dogs using guided tissue regeneration principles is described. 3 defects resembling a reduced ridge were formed on both sides of the mandible in 4 dogs. In each of the dogs. a polytetrafluoroethylene membrane was placed on 4 defects. while 2 defects were covered by gingival flaps only. Half of the defects were allowed to heal for 6 weeks and half for 12 weeks. Bucco‐lingual width measurements revealed healing up to the membrane. In the uncovered defects, the bony wall width increased during the 12‐week healing period. Histological examination showed close adaptation between bone and membrane in well‐sealed defects. In cases of incomplete sealing, connective tissue had penetrated into the defect, resulting in unpredictable bone healing. The use of guided tissue regeneration techniques is suggested as a valuable tool in 1 creating experimentally reduced ridges.
Effect of membranes and porous hydroxyapatite on healing in bone defects around titanium dental implants. An experimental study in monkeys.
Authors: Gotfredsen K. , Warrer K. , Hjörting‐hansen E. , Karring T.
Published: March 2003

The purpose of the present study was to examine the effect of treating bony craters around titanium dental implants with polytetrafluoroethylene membranes PTFE, with and without grafting of hydroxyapatite (HA), and with HA alone. 4 standardized bone defects were prepared in the alveolar ridge of edentulous areas in each of 7 monkeys. A titanium implant was then placed centrally in each defect, and in each monkey, the defects were treated with 1 of the following 4 treament modalities: 1 coverage with PTFE membrane;(2) grafting of HA and covering with a PTFE membrane;(3) HA grafting;(4) no treatment. Following a healing period of 12 weeks, all animals were sacrificed and mesiodistal ground sections of the treated areas were prepared. The histological analysis showed that all bone defects around the implants treated with PTFE membranes and 5 of the defects treated with HA and PTFE membranes were completely filled with new bone. The defects treated with HA alone and the control defects with no treatment only demonstrated new bone formation in the bottom of the defects. The results suggest that bone defects around titanium implants can be 1 treated successfully with PTFE membranes.
Intraepithelial antigen‐presenting cells in the keratitied mucosa around teeth and osseointegrated implants
Authors: Tonetti M. S. , Schmid J. , Hauml;mmerle C. H. , Lang N. P.
Published: March 2003

The presence and distribution of intraepithelial antigen‐presenting cells was studied in the keratinized mucosa around healthy osseointegrated implants and teeth. Vimentin, cytokeratins, HLA‐Dr, CD18, ICAM‐I and CDla‐positive cells were assessed by a 3‐stage ABC immunoperoxidase system in serial sections from clinically characterized sites. A total of 11 biopsies (7 adjacent to osseointegrated dental implants and 4 adjacent to teeth in healthy volunteers) were qualitatively and quantitatively analyzed. All biopsies displayed the presence of a small inflammatory infiltrate subjacent to themost coronal portion of the junctional epithelium. Intraepithelial antigen‐presenting cell markers were present both around implants and teeth. The observations were consistent with the presence of functional local major histocompatibility complex Class II restricted antigen presentation. Quantitative differences were observed by analysis of variance in terms of different locations within the same section (i.e. junctional epithelium vs oral epithelium) and in terms of the source of the biopsy (i.e. implants vs teeth). The significance, if any, of the observed quantitative difference is discussed in terms of different maturity of the local immune response and possible environmental differences. It is concluded that clinically healthy keratinized mucosa around osseointegrated dental implants shares functional similarities with normal gingiva in terms ofantigen presentation. These results further contribute to the characterization of a functional local immune response that represents the basis for long‐term clinical success of osseointegrated dental implants.
Implant‐tissue interfaces following treatment of peri‐implantitis using guided tissue regeneration. A light and electron microscopic study.
Authors: Schüpbach P. , Hürzeler M. , Grunder U.
Published: March 2003

This study details the structural and ultrastructural features of the interfaces between titanium implants and their surrounding tissues. The material stemmed from an experiment in dogs in which guided tissue regeneration with Gore‐Text membranes was used to treat peri‐implant, ligature‐induced tissue breakdown around submerged and nonsubmerged com‐mercially pure titanium implants. Specimens from the nonsubmerged group were evaluated under light microscopy and scanning and transmission electron microscopy. A healthy gingiva and a gingival sulcus were formed around the implant necks. A regenerated junctional epithelium provided the epithelial union between implant and gingiva. The supracrestal connective tissue was characterized by a 3‐dimensional network of collagen fibers, fibroblasts and blood vessels. Near the implant surface the collagen fibers ran parallel to the titanium surface or were orientated perpendicular to the implant. The connective tissue‐implant interface was characterized by a fine fibrillar material interposed between the implant surface and the connective tissue. An unidentified material was also observed between the endings of functionally orientated collagen fibrils and the metallic surface. The apical portions of the implants were anchored in compact bone. At the bone‐implant interface, either mineralized bone matrix was intimately adapted to the titanium surface without any intervening space or a 0.5 μm wide unmineralized layer was interposed. These findings indicate that a perimucosal seal was formed around the implants consisting of a junctional epithelium‐implant union coronally and supported by the connective tissue‐implant junction apically. The implants were integrated in connective tissue, but only tightly adapted to bone.
Fixed implant‐supported prostheses in the edentulous maxilla. A five‐year follow‐up report.
Authors: Weber H. P. , Fiorellini J. P. , Paquette D. W. , Howell T. H. , Williams R. C.
Published: March 2003

There is increasing interest in how pathways of tissue destruction around dental implants are similar as for teeth and how these pathways can be modulated to slow loss of supporting bone. The purposes of this study were to develop a short‐term animal model to study the effect of the nonsteroidal anti‐inflammatory drug flurbiprofen, on slowing the rate of induced peri‐implant bone resorption. A total of 20 cylindrical titanium implants were placed in 2 beagle dogs using a low‐trauma surgical technique. During the 3‐month healing period without functional loading of the implants, daily oral hygiene was performed to maintain a Gingival Index of 0 to 0.5. At completion of the healing period, a baseline evaluation was performed which included the uptake of the bone‐seeking radiopharmaceutical (BSRU)99mtechnetium‐tin‐diphosphonate (99mTc‐Sn‐MDP) in peri‐implant bone and standardized radiographs. Peri‐implantitis was induced with 4‐O silk ligatures, cessation of oral hygiene and soft diet. One beagle was given 0.02 mgikg of flurbiprofen by mouth; the other received a placebo. BSRU and radiographic height of bone were remeasured to calculate the rate of bone loss during the 60‐day treatment period. The percent rate of bone loss during the study period was calculated from the radiographs using a computer‐assisted method. The radiopharmaceutical uptake for the flurbiprofen‐treated implants remained unchanged. However, BSRU for placebo‐treated implants was significantly increased from baseline. Radiographic measurements of bone height revealed that the mean rate of bone loss around implants in the flurbiprofen‐treated dog (0.066±0.351%/month) was significantly lower than the rate around implants in the placebo‐treated dogs (5.729±0.384%/month) over the 60‐day treatment period. These data indicate that peri‐implant bone loss can be rapidly induced and measured in the beagle and that flurbiprofen. administered orally, can significantly decrease the rate of induced peri‐implant bone loss.
Damping characteristics of bone‐to‐implant interface; A clinical study with the Periotest® device.
Authors: Van Steenberghe D. , Tricio J. , Naert I. , Nys M.
Published: March 2003

The Periotest® device was used to evaluate the damping characteristics of different bone‐to‐implant interfaces of Brånemark implants. Implant and abutment lengths were found to have a significant influence on Periotest value (PTV). There was no statistical difference between PTVs of implants located in the anterior and posterior areas of the same jaw at abutment connection. No differences were found between PTVs of standard and self‐tapping implants. PTVs at abutment connection were highly influenced by the bone quality. The contact with two corticals, one at each extremity of the implant, was of a greater influence in the maxillary than in the mandibular jaw, indicating a firmer anchorage between the bicortical implants and the surrounding bone. A proaressive decrease of PTVs over time was observed, significant up to 5 years of loading.
Initial healing in the dog of submerged versus non‐submerged porous‐coated endosseous dental implants
Authors: Levy D. , Deporter D. A. , Pilliar R. M. , Watson P. A. , Valiquette N.
Published: March 2003

It has previously been reported that porous‐coated root form endosseous dental implants, became well integrated when used in the traditional 2‐stage surgical approach. In this study, the placement of the implant in a 1‐stage (non‐submerged)technique was to be explored. Implants were placed in the mandibles of dogs, and 2 designs were used differing only in that one (experimental) had a 3mm transgingival extension, permitting it to be exposed lo the oral cavity from the outset. 12 (3 per animal) non‐submerged implants were placed on I side of 4 beagle dogs and 12 control (submerged) implants were placed contralaterally. All implants were allowed to heal for 6 weeks, after which histological preparations were made. 2 of 12 non‐submerged implants were lost due to post‐operative complications: otherwise, all implants healed uneventfully. Histomorphometric analysis revealed bone‐implant contact, as assessed by absolute bone contact (ABC) and contact length fraction (CLF). to be greater for the submerged design, suggesting that bone healing may be delayed with the non‐submerged approach. As well. at this early stage of healing, for both implant designs, ABC and CLF were significantly greater on proximal than on buccal and lingual aspects.
Simultaneous force measurements in 3 dimensions on oral endosseous implants in vitro and in vivo. A methodological study.
Authors: Mericske‐stern R. , Assal P. , Buergin W.
Published: March 2003

A novel piezo‐electric force transducer was developed that is mounted directly on ITI‐implants and allows for simultaneous force measurements in 3 dimensions. The reliability of this measuring method in vitro and in vivo was evaluated. For test and calibration measurements 5 edentulous patients with 2 mandibular implants were selected and master casts obtained with original implants in situ. Preload of the abutment screw was measured with a torque controller by repeated tightening and loosening. The introduction of additional preloads when bar connectors or telescopes were mounted was examined on the casts and in the mouth. Tests were carried out to identify the influence of screw tensions on force measurements by loading the implants in vertical and transverse directions. Calibration measurements in vivo and in vitro were carried out by means of a spring balance. A regression model was calculated to analyze the influence of the applied preload on measured forces. The mean preload value was 315, ranging from 200 to 480N. A significant correlation of applied loads to measured forces was found (r=0.99). It was independent of the preload in vertical direction but dependent in transverse direction. No additional tension of the abutment screw was ever observed when bars were mounted. Calibration measurements with the spring balance showed that bars contribute to load sharing between the implants. Comparable results were found for all measurements in vitro and in vivo. It was concluded that the new piezo‐electric transducer is an adequate instrument to measure forces in 3 dimensions on ITI‐implants.
The effect of hyperbaric oxygen treatment on bone tissue reactions to c.p. titanium implants placed in free autogenous bone grafts. A histomorphometric study in the rabbit mandible.
Authors: Sawai Toshihiro , Niimi Atsushi , Johansson Carina B. , Sennerby Lars , Ozek Kenji , Takahashi Hideyo , Albrektsson Tomas , Ueda Minoru
Published: March 2003

This study aimed to investigate the effect of hyperbaric oxygen (HBO) therapy on the tissue reactions to commercially pure (c.p.) titanium implants placed in free autogenous bone graft by a 1‐stage procedure. Eighty c.p. titanium implants were placed in the bone grafted from iliac crest to bilateral mandible of 40 Japanese white rabbits without tapping. Twenty rabbits underwent daily a HBO treatment for 60 min under 2.4 ATA during 20 consecutive days and the other untreated 20 rabbits served as controls. The implants with surrounding bone tissue were retrieved 20, 30, 60, 90 and 120 days after surgery, fixated, dehydrated and embedded in resin. About 20 μm thick ground sections were prepared prior to microscopical observations. The bone area and the bone‐to‐implant contact inside the threads were calculated separately in the grafted bone and in the host bone for each implant. After 30 and up to 120 days, the HBO treated group showed more bone‐to‐implant contacts in the grafted bone as compared to the non‐HBO treated group. In the host bone there were no differences observed between HBO and non‐HBO treated groups. This study indicated that HBO treatment was beneficial for the tissue incorporation of c.p. titanium implants when placed immediately in free autogenous bone grafts.
Augmentation of skull bone using a bioresorbable barrier supported by autologous bone grafts. An intra‐individual study in the rabbit.
Authors: Lundgren A. K. , Lundgren D. , Sennerby L. , Taylor Å. , Gottlow J. , Nyman S.
Published: March 2003

The aim of this experimental investigation was to compare the effect of using autologous particulate bone grafts with and without a bioresorbable barrier covering for augmentation of the rabbit skull bone. For this purpose, bilateral, circular, 8 mm wide and 1 mm deep skull bone defects were prepared and overfilled with particulate bone grafts. The grafts placed in the test sites were covered with a bioresorbable barrier (Guidor® Matrix Barrier). The grafts placed in the control sites were covered only by the repositioned, cutaneous flap. 12 weeks later, the animals were sacrificed, the experimental sites were defleshed and the height and volume of the augmented bone in the test and control sites were measured clinically. Histologically, morphometrical measurements of the bone tissue were performed in decalcified vertical cross‐sections of the experimental sites. Statistically significant differences were found in favour of the coverage of the bone graft particles with the barrier, both with respect to the height and the volume of the augmented bone.
Short‐ and long‐term animal studies with a plasma‐sprayed calcium phosphate‐coated implant
Authors: Gottlander Magnus , Johansson Carina B. , Albrektsson Tomas
Published: March 2003

A commercially available hydroxyapatite(HA)‐coating was investigated in a 4‐ and 24‐week animal study. HA‐coated and uncoated commercially pure (c.p.) titanium threaded implants were inserted in rabbit tibia and femur. Qualitative histology showed giant cells and macrophages around both types of implants. Histomorphometry demonstrated significantly more bone in contact to the HA‐coated specimens at both follow‐up periods. In contrast, bone area measurements (the amount of bone inside and/or outside the threads) revealed significantly higher percentages of bone around the uncoated c.p. titanium controls after 6 months of follow‐up. The inferior amount of bone around the HA‐coated implants in the longer‐term perspective may relate to macrophage‐induced resorption.
Bovine hydroxyapatite for maxillary sinus grafting: comparative histomorphometric findings in sheep
Authors: Haas Robert , Donath Karl , Födinger Michael , Watzek Georg
Published: March 2003

This experimental study in animals examines the value of bovine hydroxyapatite as grafting material in one‐stage sinus lift procedure. The Schneiderian membrane was elevated from extraorally in 54 sinuses of 27 adult female mountain sheep. Two titanium plasma‐flame‐spray coated cylindrical implants were placed in each sinus in the same session. In 2 groups of 18 sinuses each, the subantral hollow space was filled with bovine hydroxyapatite and autogenous cancellous bone from the iliac crest, respectively. Eighteen sinuses that were left empty served as a control group. Polyfluorochrome sequential labelling (tetracycline, calcein green, alizarin complexon) was carried out 4 weeks postoperatively, 2 weeks before the animals were sacrificed, and halfway through the observation period to assess new bone formation. The selected observation periods were 12 weeks, 16 weeks, and 26 weeks. Six sinuses per observation period and test group were available for histologic evaluation. All implants showed favourable osseointegration into local bone. New bone formation was observed in a triangular area bound by the implant surface, the local buccal antral wall, and submucous connective tissue in all implants. Bovine hydroxyapatite adjacent to local bone was mainly surrounded by bone tissue. There was a great variation in the extent of bony sheathing of the hydroxyapatite particles, irrespective of the animals' survival time. Macrophages were found around HA particles that were not surrounded by bone as well as on free implant surfaces. The mean length of the bone‐implant bond was 3.86 mm in the group of empty sinuses, 4.87 mm in the group augmented with hydroxyapatite, and 5.66 mm in the group augmented with autogenous cancellous bone. During the observation period, the relative length of bone in direct contact with the implant surface increased from 20.0% to 25.1% in the control group, from 30.4% to 35.5% in the group treated with autogenous cancellous bone, and from 27.4% to 34.7% in the HA group. Autogenous cancellous bone showed a significantly greater bone‐implant contact than did the control group (P=0.0004) and the HA group (P=0.0499). When the apical implant portions were examined separately, both HA (P=0.006) and autoge‐nous cancellous bone (P=0.005) showed a significantly better bone‐implant bond than did the control group.
Comparison of four bone collectors designed for oral and maxillofacial surgery ‐ an in vitro study
Authors: Kainulainen Vesa , Oikarine Kyösti
Published: March 2003

Four bone collectors designed for oral and maxillofacial surgery were compared in an in vitro study. Two commercially available bone collectors (Osseus Coagulum Trap, Quality Aspirators and Frios, Friatec) with mesh sizes of 0.17 × 0.17 and 0.44 × 2.40 mm, respectively and models developed by the authors with mesh sizes of 0.355 × 0.355 or 0.50 × 0.50 (Model I) and 0.80 × 0.80 (Model II) were tested. All collectors are designed to be connected to the suction device. Five dissected pig mandibles were used to determine the harvesting capacity during drilling and suctioning for 30 s. All collectors harvested bone quite effectively, but the highest amount of bone chips was harvested by Model I which had been designed by the investigators.
The use of a conical fixture design for fixed partial prostheses. A preliminary report.
Authors: Nordin Thomas , Jönsson Göran , Nelvig Per , Rasmusson Lars
Published: March 2003

A specially designed, TiO2‐blasted titanium fixture, partially conical and microthreaded, the Astra Tech Fixture ST, was used for rehabilitation of partial edentulism in the posterior mandible. Superior to the mandibular canal 25 fixtures were placed in 10 patients. Fixed metal‐ceramic bridges were then performed. After 1‐year follow‐up, all bridges were found to be clinically stable. The implant survival rate was 100% and the mean marginal bone resorption was 0.05 ± 0.11 mm.
Electrically charged GTAM membranes stimulate osteogenesis in rabbit calvarial defects
Authors: Chierico Andrea , Valentini Robert , Majzoub Zeina , Piattelli Adriano , Scarano Antonio , Okun Laura , Cordioli Giampiero
Published: March 2003

Bone neogenesis was studied in membrane‐protected defects in a rabbit calvaria defect model using neutral, negatively, and positively charged titanium‐reinforced GTAM membranes. Two standardized circular 8 mm wide and 1 mm deep defects were created in the calvaria of 36 rabbits leaving the inner cortex intact. The defects were subsequently covered with dome‐shaped Ti‐reinforced GTAM membranes stabilized with a titanium screw allowing the edges of the membranes to be closely approximated to the bone surface. The animals were divided into 6 groups of 6 rabbits each and were sacrificed at 5 days (Group l), 10 days (Group 2), 3 weeks (Group 3), 5 weeks (Group 4), 10 weeks (Group 5), and 20 weeks (Group 6). The distribution of the 72 membranes according to charge yielded 4 positively charged, 4 negatively charged and 4 neutral domes in each group. Histomorphometric analysis showed a more rapid and increased bone neogenesis with the negatively charged domes. A mean total area of 27.95% of newly‐formed bone was observed in the negatively charged membrane sites at 10 days while negligible bone formation occurred with the neutral and positively charged domes at the same evaluation interval. Over time, negatively charged membranes supported more new‐bone formation than neutral membranes while positively charged membranes showed the least new bone. This work demonstrates that negative electrical stimulation accelerates and maintains bone neogenesis. These results also suggest the potential applications of negatively charged GTAM membranes in clinical settings.
Histological observations on biopsies harvested following sinus floor elevation using a bioactive glass material of narrow size range
Authors: Tadjoedin Ette S. , De Lange Gert L. , Holzmann Paulien J. , Kuiper Luit , Burger Elisabeth H.
Published: March 2003

We evaluated the bone augmenting capacity of bioactive glass particles, size range 300–355 μm (BG‐particles), in human sinus floor elevations using histomorphometrical methods. A total of 10 patients underwent bilateral grafting, using a 1:1 mixture of autogenous bone particles (from iliac crest) and BG‐particles at one side (experimental side), and bone particles only at the other side (control side, split mouth design). A total of 72 bone biopsies were taken at the time of fixture installation; that is, 3 patients at 4 months, 3 at 5 months and 3 at 6 months after grafting and 1 patient at 16 months (when she presented again). In each case 6 biopsies were taken, 3 left and 3 right. Histomorphometry showed that in grafts at control sides, trabecular bone was present after 4 months, comprising almost 41% of the tissue volume. This bone contained viable osteocytes and was of mature lamellar type and showed a mature histological appearance. Bone volume continued to increase slightly, to 42% at 5 months, 44% at 6 months and 45% at 16 months. The graft volume at experimental sides consisted at 4 months for 28% of woven and some lamellar bone, and increased to 35% at 5 months and 38% at 6 months, when mainly lamellar bone was found. At 16 months a lamellar bone volume of 45% was found. The BG‐particles transformed and became excavated with time, starting at 4 months, and their centers gradually filled with bone tissue. All BG‐particles had disappeared by resorption at 16 months after grafting and had been replaced by bone tissue. Parameters of bone turnover (% osteoid surface, % resorption surface, mineral apposition rate as measured by tetracycline labeling) indicated that bone remodeling was very active at both sides, during more than 6 months, despite the mature histological appearance of the bone tissue. From these histological observations, we conclude that a 1:1 mixture of autogenous bone/BG‐particles seems a promising alternative to autogenous bone only, when low amounts of bone tissue are available for sinus augmentation.
Soft tissue response to clinically contaminated and thereafter cleaned titanium surfaces
Authors: Ericsson Ingvar , Lekholm Ulf , Sennerby Lars , Holmén Anders
Published: March 2003

The aim of the present study was to evaluate the soft tissue response to intra‐orally exposed and contaminated titanium surfaces (machined, blasted or polished) after being chemically and/or mechanically cleaned. Eight adult Sprague‐Dawley rats were used for histomorphometrical and histological analyses. A total of 44 experimental abutments (26 tests and 18 controls) were inserted into abdominal skinpockets of the rats for 6 weeks. No differences regarding the soft tissue response between the different surface characteristics analysed and between test and control could be observed.
Diagnostic characteristics of clinical and microbiological tests for monitoring periodontal and peri‐implant mucosal tissue conditions during supportive periodontal therapy (SPT)
Authors: Luterbacher Stefan , Mayfield Lisa , Brägger Urs , Lang Niklaus P.
Published: March 2003

The aim of this study was to evaluate a clinical and a microbiological test for monitoring tissue condition during supportive periodontal therapy (SPT) and to compare their diagnostic characteristics at implant and tooth sites. Twelve female (age: 37–72 years) and 7 male patients (age: 26–83 years) were evaluated in this study on the basis of availability to follow a rigid SPT program. Patients had received a complete periodontal examination at 1 and 5 years after implant placement. This included standardized radiographs obtained at implants and matching control teeth. One implant site and one tooth site per patient were followed during the last 2 years of the SPT program. At each recall visit microbiological samples were analyzed according to DNA/RNA analysis identifying periodontal pathogens (IAI Pado Test 4.5®, Institute for Applied Immunology, Zuchwil, Switzerland). Presence or absence of bleeding on probing at these sites was also noted using a standardized probing force of 0.25 N (Audio Probe®, ESRO, Thalwil ZH, Switzerland). The percentage number of recall visits with positive bacteriological test results and positive BOP scores were calculated. Disease progression at the sites was defined if the annual increase in probing depth was ≥0.5 mm/year (2.5 mm in 5 years) or if the annual decrease in CADIA values (Computer Assisted Densitometric Image Analysis) was more than −0.7 per year (−3.5 in 5 years). Changes below these values were considered as negative test results indicating stability of the sites. The diagnostic characteristics (sensitivity, specificity, positive and negative predictive values) of BOP and microbiological tests alone or in combination were then calculated using two‐by‐two tables. By application of increasing thresholds of BOP frequencies set for definition of positive test outcome (BOP ≥10% ≥20% ≥25% ≥50% ≥75% ≥90% or the combined BOP ≥75%, but DNA positive ≥10%, ≥25% ≥34% ≥50% ≥67% ≥90%) receiver operator characteristics curves (ROC) were constructed for teeth and implants. The areas under the ROC curves were calculated and compared by means of chi‐square tests. The results indicated statistically significant better diagnostic characteristics of both tests at implants compared to teeth. The inclusion of an additional microbiological test significantly enhanced the diagnostic characteristics of BOP alone at teeth as well as at implants.
Mathematical analysis of projection errors in “paralleling technique” with respect to implant geometry
Authors: Schulze Ralf Kurt Willy , D'Hoedt Bernd
Published: March 2003

Abstract: “Standardized” radiographs acquired in paralleling technique serve for monitoring of marginal bone levels around endosseous implants. Under clinical conditions, parallel adjustment of the film to the implant is beset with great difficulties. A mathematical model matching clinical conditions was developed to evaluate projection geometry within an interval of clinically relevant angulations (± 10° from parallel position). Radiographs of two implants (Frialit 2, Friadent AG, Mannheim, Germany; Implant No. 1: ∅ 3.8 mm, length 10 mm; Implant No. 2: ∅ 6.5 mm, length 13 mm) were separately produced per angulation (2° increments) at one focus‐object distance (FO=322.9 mm). Implant images were repeatedly measured along their midline/vertical edge, local magnification (MF) was calculated and the values were compared to the computed ones. Projected dimensions of the implants were calculated for a second distance (232.3 mm). The experimentally acquired data were in agreement with the mathematical calculation. MF calculated for assessment along the vertical edge varied less (±1.94% from mean value) than along the midline (±2.74%), with a range of 1.037–1.068 (FO=322.9 mm) and 1.061–1.099 (FO=232.3 mm) for implant No.1, and 1.060–1.101 (FO=232.3 mm) and 1.037–1.069 (FO=322.9 mm) for Implant No. 2. Magnification revealed a mean variation of 4%. Radiographic evaluation of periimplant bone level should not exceed a precision of 0.5 mm, when parallelism between film and implant is not guaranteed and FO is less than 380 mm.
Magnetic resonance imaging assessment of a sinus lift operation using reoxidised cellulose (SurgicelR) as graft material
Authors: Gray Crawford F. , Redpath Thomas W. , Bainton Roger , Smith Francis W.
Published: March 2003

Abstract:Various materials have been used for bone grafts in the sinus lift operation, to increase the vertical bone height in the maxilla before the placement of dental implants in the atrophic maxilla. In this case history, SurgicelR(oxidised regenerated cellulose) was used as a graft material for one patient, allowing successful delayed implant placement within new and existing bone. The sinus region was examined three months after grafting with SurgicelRusing magnetic resonance imaging (MRI). The MR images showed that material of similar MR signal to bone had formed within the graft. MRI allowed us to gain tomographic information of the region without exposure of the patient to ionising radiation. The formation of bone within the SurgicelRmatrix was confirmed at implant placement. This poses interesting questions as to the physiology of bone formation within non‐particulate graft material, warranting further investigation.