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Biomedical subjects

P Schüpbach

Publications and source records attributed to P Schüpbach.

At least 19 recordsLinked to original sources
PubMed2005

Bone quality at the implant site after reconstruction of a local defect of the maxillary anterior ridge with chin bone or deproteinised cancellous bovine bone.

The purpose of this study was to investigate the quality of bone at grafted implant sites in the anterior maxilla. Grafting of these sites was necessary because of insufficient bone volume in a buccopalatinal direction (width at the top of the crest 1-3mm). Reconstruction was performed with chin bone (N=5), chin bone and a resorbable Bio-Gide GBR membrane (N=5) or Bio-Oss spongiosa granules in combination with a Bio-Gide GBR membrane (N=5). Biopsies were taken prior to implantation, i.e. 3 months after grafting with chin bone, and 6 months after grafting with Bio-Oss. Evaluation was done by assessing the histological and histomorphometric characteristics of full-length biopsies taken from the actual implant site. Both areas with non-vital bone and areas with apposition of bone and remodelling phenomena were observed in the chin bone group at the time of placement of the implants. Similar results were observed at implant sites reconstructed with a chin bone graft covered by a membrane. In the chin bone group without and with a GBR membrane, the mean total bone volume (TBV) was 55.2+/-6.8% and 57.7+/-11.5%, respectively; the marrow connective tissue volume (MCTV) was 44.8+/-6.8% and 42.3+/-11.5%, respectively. Remnants of the resorbable GBR membrane were not detected. In the Bio-Oss((R)) group, at implant placement some newly formed bone was observed in the connective tissue surrounding the Bio-Oss((R)) particles (mean TBV (newly formed bone) 17.6+/-14.5%), but most particles were surrounded by connective tissue. No convincing signs of remodelling were observed (mean remaining Bio-Oss volume 40.5+/-9.3%; mean MCTV 41.9+/-13.1%). No implants were lost during follow up (12 months). At the time of placement of the implants the grafting material (either chin bone or Bio-Oss is still not fully replaced by new vital bone. In case of Bio-Oss, most of the grafting material is even still present. Despite these differences, the 1-year clinical results were very good and comparable between the various grafting techniques applied.

Adolescent↗
PubMed2004

Treponema putidum sp. nov., a medium-sized proteolytic spirochaete isolated from lesions of human periodontitis and acute necrotizing ulcerative gingivitis.

So far, little phenotypic heterogeneity has been detected in cultured oral treponemes with trypsin-like proteolytic activity, and all have been assigned to the species Treponema denticola. However, comparisons of protein patterns and antigen expression in our collection of proteolytic oral treponemes occasionally identified isolates with a unique phenotype; e.g. strain OMZ 830 (=ATCC 700768), which qualified as a 'pathogen-related oral spirochaete' due to the presence of a approximately 37 kDa protein reactive with the Treponema pallidum FlaA-specific mAb H9-2. In addition to such single isolates, a homogeneous group of seven independent strains is described that were highly motile, medium-sized, proteolytic but asaccharolytic spirochaetes and were cultured from human gingivitis, periodontitis and acute necrotizing ulcerative gingivitis in medium OMIZ-Pat supplemented with 1% human serum and antibiotics. Growth of these spirochaetes in OMIZ-Pat was not dependent on, but was stimulated by, human or bovine serum. Carbohydrates were neither required nor stimulatory for growth. The protein and antigen patterns of total cell extracts of these organisms separated by SDS-PAGE were distinct from those of all previously cultured spirochaetes, with highest similarity to T. denticola. The novel spirochaete has a 2 : 4 : 2 arrangement of the periplasmic flagella, similar to T. denticola. However, the flagellin pattern as detected by immunostaining or glycan staining of Western blots readily distinguished the novel group from T. denticola. Also, distinct from reference strains of T. denticola, none of the novel isolates displayed sialidase or dentilisin activities, both of which are expressed by most strains of T. denticola. Trypsin-like activity and other enzymes as detected by API ZYM test were similar to those of T. denticola. The status of a novel species is supported by the 16S rRNA gene sequence, with 98.5% similarity to its closest cultured relative, T. denticola. The name Treponema putidum sp. nov. is proposed (type strain OMZ 758T=ATCC 700334T=CIP 108088T).

Antigens, Bacterial↗
PubMed2001

Thoracoabdominal aortic repair in a 190-kg patient: optimized perfusion with two oxygenators.

A 190-kg patient was referred because of an acute type B aortic dissection. Conservative management was initially performed but the 34-year-old patient was shown to have an increasing aortic diameter 2 months later and was scheduled for elective repair of the thoracoabdominal aorta. To anticipate potential difficulties with perfusion and oxygenation the cardiopulmonary bypass circuit was constructed with two parallel oxygenators, which allowed an adequate oxygen supply through all phases of the intervention and accelerated the estimated rewarming time.

Adult↗
PubMed2001

Electron-microscopic demonstration of proline-rich proteins, statherin, and histatins in acquired enamel pellicles in vitro.

Proline-rich proteins (PRPs), histatins, and statherin are salivary proteins that exhibit high affinities for hydroxyapatite surfaces. In vitro experiments with parotid submandibular/sublingual or whole saliva have shown these proteins to adsorb selectively to tooth surfaces. This investigation focuses on the histo-morphological identification of PRPs, histatins, and statherin in acquired enamel pellicles. Synthetic hydroxyapatite or bovine enamel were exposed to glandular secretions, and whole saliva and pellicle precursor proteins were identified immunohistologically by electron microscopy. Results obtained by back-scattered scanning electron microscopy showed these proteins to be present in pellicles. Pellicles displayed a distinct structure consisting of a sponge-like meshwork of microglobules. Interconnections between structural elements were identified in submandibular/sublingual and whole saliva pellicles only. Transmission electron microscopy of pellicles formed on bovine enamel surfaces revealed a tendency for preferential localization of precursor proteins within the protein film. Since the data showed the presence of pellicle precursors in pellicles derived both from glandular secretions and from whole saliva, it is likely that PRPs, histatins, and statherin are integral components of acquired enamel pellicles in vivo.

Animals↗
PubMed2001

Treponema parvum sp. nov., a small, glucoronic or galacturonic acid-dependent oral spirochaete from lesions of human periodontitis and acute necrotizing ulcerative gingivitis.

Small oral spirochaetes with a strict dependence on either glucuronic acid (GluA) or galacturonic acid (GalA) were isolated from European patients with periodontitis and from Chinese patients with either gingivitis or acute necrotizing ulcerative gingivitis (ANUG). Thirteen such isolates were similar phenotypically to Treponema pectinovorum ATCC 33768T and this classification was confirmed by 16S rRNA sequencing. However, four isolates differed from T. pectinovorum by their small cell size, by a prominent beta-glucuronidase activity, by a distinct protein and antigen profile, by an inability to grow on pectin as sole source of carbohydrate and by a markedly enhanced growth rate when supplied with a second carbohydrate (L-arabinose, D-galactose, D-glucose, D-fructose, D-mannitol, D-mannose, pectin, D-ribose or D-xylose) in addition to the essential GluA/GalA. By 16S rRNA sequencing these four isolates clustered in the recently described phylotype 'Smibert-2'. T. pectinovorum (14 strains) and 'Smibert-2' (four isolates with beta-glucuronidase activity) could each be subdivided into two serotypes based on immunoblot reactivity with two mAbs. Representatives of the two groups, including T. pectinovorum ATCC 33768T, showed a 1:2:1-type periplasmic flagellar arrangement. 'Smibert-2' is described as a novel species, Treponema parvum sp. nov., with isolate OMZ 833T (= ATCC 700770T) proposed as the type strain and OMZ 842 (= ATCC 700773) as reference strain for a second serotype.

Acute Disease↗
PubMed2001

Validation of an in vitro biofilm model of supragingival plaque.

The study of biofilm structure and function mandates the use of model systems for which a host of environmental variables can be rigorously controlled. We describe a model of supragingival plaque containing Actinomyces naeslundii, Veillonella dispar, Fusobacterium nucleatum, Streptococcus sobrinus, and Streptococcus oralis wherein cells are cultivated anaerobically in a saliva-based medium on hydroxyapatite discs coated with a salivary pellicle, with material and pieces of apparatus common to all microbiology laboratories. After 0.5 hr, 16.5 hrs, 40.5 hrs, and 64.5 hrs, the composition of adherent biofilms was analyzed by culture techniques, live/dead fluorescence staining, and confocal laser scanning microscopy. Repeated independent trials demonstrated the repeatability of biofilm formation after 40.5 hrs and 64.5 hrs. Brief exposures of biofilms to chlorhexidine or Triclosan produced losses in viability similar to those observed in vivo. This biofilm model should prove very useful for pre-clinical testing of prospective anti-plaque agents at clinically relevant concentrations.

Actinomyces↗
PubMed2001

Alveolar ridge augmentation with Bio-Oss: a histologic study in humans.

The aim of the present study was to investigate the healing of alveolar ridge defects augmented with cancellous bovine bone mineral. In six partially edentulous patients, bone augmentation was necessary prior to implant placement because of severe alveolar ridge resorption. The defect sites, all located in the maxilla, were filled with Bio-Oss and covered with the resorbable collagen membrane Bio-Gide. Biopsies were obtained from the defect sites 6 to 7 months following grafting and were processed for ground sectioning. The histologic analysis revealed that the Bio-Oss particles occupied 31% of the total biopsy area. An intimate contact between woven bone and Bio-Oss was detected along 37% of the particle surfaces. A mixed type of bone was found; it contained woven bone and parallel-fibered bone, which demonstrates features of remodeling activity. Signs of resorption of the grafting material were observed in the histologic sections, which indicates that the material takes part in the remodeling process. It is suggested that Bio-Oss may be a very suitable material for staged localized ridge augmentation in humans.

Adult↗
PubMed2001

Fissure sealing: optimization of sealant penetration and sealing properties.

PURPOSE: This in vitro study determined the penetration depth of a fissure sealant into an empty fissure system and into a conditioned enamel surface, using different sealing procedures. MATERIALS AND METHODS: 48 extracted, non-carious human molars were sealed with the unfilled sealant (Heliobond) using the enamel adhesive technique (35% phosphoric acid gel, 120 s etching time, bond application, light-curing for 60 s). The following factors were tested in comparison to the control group (1): influence of a precuring time lapse of 20 s after sealant application (2); ultrasound application with a plastic tip during the etching procedure (3); a wetting agent in an acid vehicle (4); enamel drying with acetone after the etching procedure (5); and finally, the combination of ultrasound during etching; a drying procedure with acetone; and a 20 s precuring time lapse (all applied to the same sample). The sealed teeth were sectioned and evaluated by conventional light microscopy to determine the penetration depth into the fissure, and by confocal laser microscopy to investigate the quality of the adhesion zone. RESULTS: Strict adherence to a specified penetration time, an intensified etching procedure with ultrasound, and the use of a drying procedure with acetone each showed a positive effect on the fissure penetration depth of the sealant and on the adhesion zone. The combination of these measures improved significantly the quality of the fissure sealing. Penetration depth increased to 92% of the fissure depth. From 95-100% of the total length of the analyzed adhesion zone shows excellent tags of sealant in the conditioned enamel surface. CLINICAL SIGNIFICANCE: Simple changes in the application technique of fissure sealants, such as ultrasonic treatment during etching procedure and drying the etched fissure system by acetone, improved the quality of the fissure sealing, which is a noninvasive preventive measure.

Acetone↗
PubMed1999

The ultrastructure of a compomer adhesive interface in enamel and dentin, and its marginal adaptation under dentinal fluid as compared to that of a composite.

OBJECTIVES: To visualise the ultrastructure of the interface of SCA compomer adhesive and of Optibond composite adhesive in enamel and dentin, and to relate the findings to the marginal adaptation of these two products in mixed class V restorations. METHODS: The ultrastructure was investigated using a scanning electron microscope (SEM) with and without prior argon ion etching, an environmental SEM, a field emission SEM, a confocal laser scanning microscope, and a transmission electron microscope. The marginal adaptation was quantified in mixed class V restorations by using the replica technique and a SEM under simulated dentinal fluid before and after simultaneous mechanical and thermal loading. RESULTS: The ultrastructure of the compomer adhesive interface differed from those of the composite. However, no significant difference was discerned as regards the percentage of "continuous margin" in the enamel marginal area before loading, and in the dentin area before and after loading (p < 0.05; unpaired t-test). Only after loading, the percentage of "continuous margin" in enamel was significantly (p < 0.05; unpaired t-test) better than that of the compomer. SIGNIFICANCE: The results indicated that the ultrastructure of the adhesive interface allowed no clear conclusions to be drawn as to the quality of marginal adaptation.

Compomers↗
PubMed1999

Treponema lecithinolyticum sp. nov., a small saccharolytic spirochaete with phospholipase A and C activities associated with periodontal diseases.

Strong phospholipase A (PLA) and phospholipase C (PLC) activities as potential virulence factors are the outstanding characteristics of eight strains of small oral spirochaetes isolated from deep periodontal lesions. By qualitative dot-blot DNA-DNA hybridization and 16S rDNA sequence comparison, these spirochaetes form a distinct phylogenetic group, with Treponema maltophilum as its closest cultivable relative. Growth of these treponemes, cells of which contain two endoflagella, one at each pole, was autoinhibited by the PLA-mediated production of lysolecithin unless medium OMIZ-Pat was prepared without lecithin. N-Acetylglucosamine was essential and D-ribose was stimulatory for growth. All isolates were growth-inhibited when 1% foetal calf serum was added to the medium. Growth on agar plates supplemented with human erythrocytes produced haemolysis. In addition to PLA and PLC, the new isolates displayed strong activities of alkaline and acid phosphatases, beta-galactosidase, beta-glucuronidase, N-acetyl-beta-glucosaminidase and sialidase, intermediate activities of C4- and C8-esterases, naphthol phosphohydrolase and alpha-fucosidase and a distinctive 30 kDa antigen detectable on Western blots. This phenotypically and genotypically homogeneous group is proposed as a novel species, Treponema lecithinolyticum sp. nov., with isolate OMZ 684T designated as the type strain. A molecular epidemiological analysis using a T. lecithinolyticum-specific probe showed this organism to be associated with affected sites when compared with unaffected sites of periodontitis patients. This association was more pronounced in patients with rapidly progressive periodontitis than in those with adult periodontitis.

Adult↗
PubMed1997

[Acute type B aortic dissection: prognosis after initial conservative treatment and predictive factors for a complicated course].

OBJECTIVE: Today there is still debate concerning the optimal mode of treatment for type B dissection of the aorta. Controversies are mainly due to discordant results regarding survival following medical or surgical treatment. We assessed the early and long-term outcome of acute dissection of the descending aorta after initial conservative treatment. METHODS: Between 1980 and 1995, 225 patients were hospitalized in the medical or surgical department of our institution with the diagnosis of acute type B aortic dissection. 38 patients (16.8%) underwent replacement of the descending aorta within the first week after hospital admission. Primary indications for immediate surgery were rupturing aneurysm in 15 patients, extensive dilatation of the descending aorta in 13, distal malperfusion in 8, and pseudocoarctation syndrome with uncontrollable hypertension in 2. All other patients (n = 187) underwent primary conservative treatment in the intensive care unit, which included appropriate antihypertensive medication. RESULTS: Hospital mortality during and after initial conservative treatment was 17.6% (33/187 patients). Main causes of death were rupture in 14 patients, intestinal malperfusion in 13 and cardiac failure in 3, whereas in 3 patients the cause of death could not be determined. Nine additional patients had to be referred for early surgery during the initial hospitalization because of contained rupture (n = 4), rapidly increasing size of the aorta (n = 2) and suspected intestinal ischemia (n = 3). Hospital mortality after early surgery was 21% (8/38 patients) for the overall time period. After hospital discharge from the initial acute dissection, surgery for chronic dissection was performed in 47 patients, mainly because of expanding descending aortic aneurysm. Hospital mortality was 8% in these patients (4/47). Actuarial survival rates after primary conservative therapy were 76 +/- 5% and 50 +/- 7% after 5 and 8 years respectively. CONCLUSION: Currently, surgery for acute type B dissection is limited to patients with rupturing disease, distal malperfusion or uncontrollable hypertension and pains. Despite aggressive antihypertensive treatment, hospital mortality after primary conservative treatment is still high and a substantial proportion of patients requires surgery during initial hospitalization. Although conservative treatment is recommended in most uncomplicated type B aortic dissections, early surgery should be considered in the following situations: younger patients with 5 cm diameter of the aorta at initial evaluation, as well as those with Marfan syndrome, patients with limited false aneurysm or retrograde dissection into the aortic arch, and those with poor medical compliance or uncontrollable proximal hypertension. Radiographic follow-up for an indefinite period may allow detection of potential late complications and proper planning of elective operations when indicated.

Acute Disease↗
PubMed1997

[Current techniques in heart surgery].

Significant advances in open heart surgery during the last two decades were achieved in the field of the extracorporal circulation and the preservation of the myocardium. In the last few years, new therapeutical tools were introduced to treat patients with coronary artery disease. The transmyocardial laser revascularization (TMR) technique was introduced for clinical investigation 1990. Despite limited experience with this device in selected patients, some conclusions after a short follow-up period are available. Patients treated with TMR have significantly less anginal pain and need fewer hospitalisations. With PET follow-up studies, a better subendocardial perfusion at the expense of the subepicardial perfusion was demonstrated. On the other hand, there was no substantial increase found in terms of ejection fraction in treated patients. Minimally invasive procedures have also gained acceptance during the last few years, especially the minimally invasive coronary artery bypass procedures (MIDCAB). Introduced initially to treat solitary stenoses of the LAD without cardiopulmonary bypass, this procedure is actually often used in conjunction with PTCA for three-vessel disease in selected patients. Due to the different methods used and summarized under the term of MIDCAB, definite conclusions about the advantages of this method are difficult to formulate. There is a trend to reduced patency rates of the IMA bypasses in MIDCAB procedures compared to the conventional technique due to the difficulty with limited access.

Angioplasty, Balloon, Coronary↗
PubMed1997

Guided bone regeneration around dental implants in the atrophic alveolar ridge using a bioresorbable barrier. An experimental study in the monkey.

The aim of this study was to evaluate guided bone regeneration (GBR) around dental implants placed in atrophic alveolar ridges using an experimental, nonporous bioresorbable barrier. In 8 Rhesus monkeys, the maxillary canines and lateral incisors were extracted bilaterally and the remaining alveoli were reduced to create atrophic ridges. After a healing period of 3 months, soft tissue expansion was performed using a subperiosteal tissue expander. After 1 month of tissue expansion, and IMZ implant was placed in the atrophic ridge on each side in such a way that its coronal 4 mm to 5 mm remained circumferentially exposed above the bone level. The test implants were covered with a bioresorbable barrier made of poly (D,L-lactid-co-trimethylencarbonate) in a 70/30 ratio, whereas the control implants were covered with a nonresorbable expanded polytetrafluoroethylene (e-PTFE) barrier. The e-PTFE barriers were stabilized with titanium minipins while the bioresorbable barriers were analogously fixed using bioresorbable minipins made of poly (L-lactid-co-D,L-lactid) 70/30. Clinical healing progressed uneventfully in both groups and no soft tissue dehiscences occurred. Histometric and histomorphometric analyses were performed 5 months post surgery. Both test and control implants exhibited direct bone-to-implant contact to variable extents. The mean direct mineralized bone-to-implant contact length fraction was 32% of the total implant length in the test sites and 58% in the control sites. Control sites exhibited significantly greater bone fill compared to the experimental sites (P < 0.001). Histologic observations of test specimens demonstrated a moderate inflammatory reaction related to the degradation and resorption products of the barrier. In conclusion, the nonresorbable e-PTFE GBR barrier was found to be superior to the bioresorbable barriers tested in the present investigation.

Alveolar Bone Loss↗
PubMed1997

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part III. Evaluation of autogenous bone combined with porous hydroxyapatite.

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 IMZ 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.

Animals↗
PubMed1997

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part I. Evaluation of anorganic bovine-derived bone matrix.

The aim of this study was to evaluate clinically, histologically and histometrically the use of anorganic bovine bone matrix (i.e. Bio-oss) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted. The remaining bone between the alveolar crest and the bottom of the sinus was then reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey and the sinuses were grafted with the bovine bone matrix. At that time, 2 IMZ pure titanium plasma coated implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into these 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 the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side 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 significant bone formation with integration of the bovine bone matrix particles to the new bone. Direct mineralized bone-to-implant contact was greater for the delayed implant placement groups than for the implants installed simultaneously with the sinus augmentation. Furthermore, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that the anorganic bovine bone matrix facilitated bone formation and implant osseointegration in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure seemed to be preferable.

Alveolar Process↗
PubMed1997

Maxillary sinus augmentation using different grafting materials and osseointegrated dental implants in monkeys. Part II. Evaluation of porous hydroxyapatite as a grafting material.

The aim of this study was to evaluate clinically, histologically and histometrically the use of porous hydroxyapatite (i.e. Interpore-200) as a bone grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted and the remaining bone between the alveolar crest and the bottom of the sinus was reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey, and the sinuses grafted with the porous hydroxyapatite. Two IMZ titanium plasma-sprayed cylinder implants were then immediately placed into the augmented sinus (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). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side 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. Histologic analysis demonstrated a significant amount of new bone formation in the augmented sinuses. Porous hydroxyapatite graft particles appeared to be integrated to the new bone. The percentage of direct mineralized bone-to-implant contact in the augmented area was greater on the delayed-placed implants than on the simultaneously-placed implants. Also, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that this porous hydroxyapatite bone graft enhanced bone formation and bone-to-implant contact in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure appears to result in a higher percentage of direct mineralized bone-to-implant contact.

Alveolar Process↗
PubMed1997

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part IV. Evaluation of hydroxyapatite-coated implants.

The aim of this study was to evaluate clinically, histologically and histometrically the use of hydroxyapatite-coated dental implants in conjunction with maxillary sinus augmentation procedures. In 4 adult male Rhesus monkeys (Macaca mulatta) the 3 maxillary molars on 1 side of the jaws were extracted and the remaining bone between the alveolar crest and the floor of the sinus was reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed in each monkey and the sinuses were grafted with a porous hydroxyapatite bone graft (Interpore-200). At the same time, 2 hydroxyapatite-coated cylinder implants (IMZ) were immediately placed into the augmented sinuses (i.e. simultaneous-implants-loaded group). Four months later, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed-implants-loaded group). After 4 months, 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 the same treatment with the exception that removal of the maxillary molars was performed 7 months after those in the opposite side, and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous-implants-unloaded group and delayed-implants-unloaded group) were obtained. Clinically, all loaded and unloaded implants were stable the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation with integration of the porous hydroxyapatite graft particles and hydroxyapatite-coat of the dental implants to the new bone. Histometric analysis indicated that on the loaded side the implants placed simultaneously with the sinus lift procedure exhibited greater direct mineralized bone-to-implant contact than the delayed placed implants. In addition, the percentage of direct mineralized bone-to-implant contact was significantly greater in the residual bone in comparison to the augmented area in all groups. Loading of the implants exhibited a positive effect on the percentage of direct mineralized bone-to-implant contact in the augmented area. It could be concluded that hydroxyapatite-coated implants may be of benefit when used in conjunction with sinus augmentation procedures.

Alveolar Process↗