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Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 163 records · Page 9Linked to original sources
PubMed2001

The influence of fish, meat and polyunsaturated fat intakes on platelet phospholipid polyunsaturated fatty acids in male Melbourne Chinese and Caucasian.

OBJECTIVE: The aims of this study were to investigate (1) platelet phospholipid (PL) polyunsaturated fatty acid (PUFA) composition in subjects who were the Melbourne Chinese migrants, compared with those who were the Melbourne Caucasians and (2) the relationship between platelet PL PUFA and intake of fish, meat and PUFA. DESIGN: Cross-sectional comparison of the Melbourne Chinese and Caucasians. SETTING: Free-living male subjects. SUBJECTS: Ninety-seven Melbourne Chinese migrants and 78 Melbourne Caucasians who were recruited in Melbourne. OUTCOME MEASURES: Dietary intake was assessed using a semi-quantitative food frequency questionnaire. The platelet PUFA was measured by gas-liquid chromatography. RESULTS: The Melbourne Chinese had significantly higher proportions of platelet PL 20:5n-3 (P=0.006), 22:6n-3 (P<0.0001), total n-3 (P=0.027) and 22:5n-6 (P=0.0002), and a significantly higher intake of fish (P=0.012) and white meat (P=0.0045) compared with the Melbourne Caucasians. In addition, the Melbourne Chinese had significantly lower proportions of 20:3n-6 (P=0.023), 20:4n-6 (P<0.002), 22:4n-6 (P<0.0001), total n-6 (P=0.037), 22:5n-3 (P<0.0001) and ratio of n-6/n-3 (P=0.011), and a significantly lower intake of red and total meat (P<0.0001) than the Melbourne Caucasians. Fish consumption was significantly positively correlated with platelet PL 20:5n-3 and 22:6n-3, and significantly negatively correlated with 22:5n-3 (P<0.05). Meat consumption was significantly positively correlated with 22:5n-3 and significantly negatively correlated with 22:5n-6, 20:5n-3 and 22:6n-3 (P<0.05). Dietary PUFA intake was significantly positively correlated with 20:3n-6, 22:4n-6 and 22:5n-3, and significantly negatively correlated with 22:5n-6, 20:5n-3 and 22:6n-3 (P<0.05). CONCLUSIONS: Compared with Caucasians, the Melbourne Chinese had a significantly higher level of platelet PL n-3 PUFA, which might contribute to the low CVD mortality in this population. Platelet PL 20:5n-3 and 22:6n-3 were significantly positively correlated with fish intake, and negatively significantly correlated with dietary intake of meat and PUFA, while 22:5n-3 was significantly positively correlated with dietary meat and PUFA intake, and significantly negatively correlated with fish intake. Dietary intake of PUFA and fish are potential confounding factors for assessing the effects of meat consumption on platelet PL individual PUFA. Dietary intake of PUFA and meat did not influence the incorporation of fish long chain n-3 PUFA to platelet PL in this study population. SPONSORSHIP: Palm Oil Research Institute of Malaysia, Meat Research Corporation Australia.

Adult↗
PubMed2001

Protection against ischemia/reperfusion injury and myocardial dysfunction by antisense-oligodeoxynucleotide directed at angiotensin-converting enzyme mRNA.

Angiotensin-converting enzyme (ACE) activity in the myocardium and angiotensin-II (Ang-II) levels in plasma increase after myocardial ischemia, which lead to exacerbation of myocardial injury and cardiac dysfunction. We examined the protective role of novel antisense-oligodeoxynucleotide (AS-ODN) directed at ACE mRNA in myocardial ischemic injury. Sprague-Dawley rats were treated with ACE-AS-ODN (200 microg per rat, n = 8, i.v.) or inverted-ODN (IN-ODN, 200 microg per rat, n = 8, i.v.), given with 600 microg per rat of liposome DOTAP/DOPE. Hearts from AS-ODN- or IN-ODN-treated rats were excised, perfused in vitro, and subjected to 25 min of global ischemia followed by 30 min of reperfusion. Parallel groups of rats were given ACE inhibitor captopril (5 mg/kg, n = 8) or saline (n = 8) before excising the hearts. Ischemia/reperfusion resulted in myocardial dysfunction (increase in coronary perfusion pressure and LV end-diastolic pressure and a decrease in developed LV pressure) in the saline-treated rats. Myocardial dysfunction was associated with evidence of lipid peroxidation and enzyme leakage (MDA and LDH levels in the myocardium) and up-regulation of ACE protein expression. Administration of AS-ODN or captopril, but not IN-ODN, reduced Ang-II levels in the plasma, decreased ischemia/reperfusion-mediated cardiac functional deterioration and lipid peroxidation, and preserved LDH in the myocardium (all P < 0.05 versus the saline group). AS-ODN and captopril had equipotent effects on cardiac dynamics. ACE protein expression (western blot) was decreased in the hearts of the AS-ODN-treated group, but not in IN-ODN-treated rat hearts. In contrast, ACE protein expression was significantly increased in captopril-treated rat hearts. These observations suggest that AS-ODN directed at ACE mRNA can ameliorate myocardial dysfunction and injury after ischemia/reperfusion, and its use is associated with decreased expression of ACE protein in the ischemic myocardium.

Angiotensin II↗
PubMed2001

Morphometric assessment of gastric antral atrophy: comparison with visual evaluation.

AIMS: As part of a multinational effort to reach a consensus in the definition and evaluation of atrophic gastritis, we applied morphometric techniques to 22 antral biopsy specimens examined visually by 12 experienced gastrointestinal pathologists. METHODS AND RESULTS: Atrophy was defined as loss of glands. Each pathologist graded atrophy with both non-standardized and standardized approaches. Discriminant function analyses of morphometric measurements were conducted to validate and grade atrophy. Kappa statistics were used to compare the performance of each pathologist against the group mode and against the discriminant functions' grading of atrophy. Three morphometric indexes showed significant differences among categories of atrophy utilizing non-standardized as well as standardized visual atrophy grades: (i) the ratio of glandular length to total mucosal thickness; (ii) the proportion of the secretory compartment area occupied by glands; and (iii) the number of glandular cross sections per 40x microscopic field. The discriminant function analyses verified all cases classified visually as either non-atrophic, or moderately/severely atrophic; it verified as mildly atrophic 40% of the cases classified visually as mildly atrophic; and classified the remaining 60% as moderately or severely atrophic. The kappa statistics were good or excellent for the majority of pathologists. CONCLUSIONS: The evaluation of antral atrophy, simply defined as loss of glands, can be reliable and reproducible. The visual grading of atrophy as absent, moderate and severe is entirely consistent with objective morphometric observations.

Atrophy↗
PubMed2001

Method for simultaneous epicardial and endocardial mapping of in vivo canine heart: application to atrial conduction properties and arrhythmia mechanisms.

INTRODUCTION: It has been suggested that the three-dimensional structure of the atria may be crucial in arrhythmogenesis; however, previous in vivo atrial activation mapping studies have been limited to either endocardial or epicardial approaches. METHODS AND RESULTS: To investigate the role of endocardial and epicardial structures and their interaction in atrial conduction and arrhythmias, we used five epicardial plaques and two intra-atrial balloon arrays to record a total of 368 unipolar electrograms from the entire epicardial and endocardial surface of both atria. During regular 1:1 pacing from the right atrial appendage, right atrial endocardial activation spread considerably faster than epicardial (total activation time 45+/-12 msec vs 60+/-19 msec, respectively [mean +/- SD]; P < 0.05), pointing to preferential conduction over structures like the crista terminalis and pectinate muscles. No such differences were noted in the left atrium. Transseptal spread occurred via discrete anterior and posterior pathways, causing separate breakthroughs in anterior and posterior atrial regions, respectively. Dissociation between septal pathways played a role in reentry during vagal atrial fibrillation. In 2 of 4 dogs with atrial fibrillation associated with congestive heart failure, single macroreentrant circuits involving endocardial and epicardial components were revealed during the arrhythmia. CONCLUSION: We conclude that activation mapping using simultaneous recording from both epicardial and endocardial surfaces provides potentially important insights into the mechanisms of atrial conduction and arrhythmogenesis.

Activation Analysis↗
PubMed2001

A molecular comparison of T lymphocyte populations infiltrating the liver and circulating in the blood of patients with chronic hepatitis B: evidence for antigen-driven selection of a public complementarity-determining region 3 (CDR3) motif.

Despite a large number of T cells infiltrating the liver of patients with chronic hepatitis B, little is known about their complexity or specificity. To characterize the composition of these T cells involved with the pathogenesis of chronic hepatitis B (CHB), we have studied the clonality of VbetaT cell receptor (TCR)-bearing populations in liver tissue by size spectratyping the complementarity-determining region (CDR3) lengths of TCR transcripts. We have also compared the CDR3 profiles of the lymphocytes infiltrating the liver with those circulating in the blood to see whether identical clonotypes may be detected that would indicate a virus-induced expansion in both compartments. Our studies show that in most of the patients examined, the T cell composition of liver infiltrating lymphocytes is highly restricted, with evidence of clonotypic expansions in 4 to 9 TCR Vbeta subfamilies. In contrast, the blood compartment contains an average of 1 to 3 expansions. This pattern is seen irrespective of the patient's viral load or degree of liver pathology. Although the TCR repertoire profiles between the 2 compartments are generally distinct, there is evidence of some T cell subsets being equally distributed between the blood and the liver. Finally, we provide evidence for a putative public binding motif within the CDR3 region with the sequence G-X-S, which may be involved with hepatitis B virus recognition.

Adolescent↗
PubMed2001

Inhibition of prostaglandin E2 production by platycodin D isolated from the root of Platycodon grandiflorum.

Platycodin D, isolated from the root of Platycodon grandiflorum A. DC. (Campanulaceae) suppressed prostaglandin E2 production at 10 and 30 microM in rat peritoneal macrophages stimulated by the protein kinase C activator 12-O-tetradecanoylphorbol 13-acetate (TPA). Platycodin D3 and oleanolic acid showed no effect at these concentrations. Western blot analysis revealed that the induction of COX-2 protein by TPA was inhibited by platycodin D in parallel with the inhibition of prostaglandin E2 production. Platycodin D showed no direct effect on COX-1 and COX-2 activities. TPA-induced release of [3H]arachidonic acid from pre-labeled macrophages was also not inhibited by platycodin D.

Animals↗
PubMed2001

Gene expression in the mammalian cochlea: a study of multiple vector systems.

Successful delivery of genes to the inner ear has been demonstrated using a variety of vectors and animal models. As our understanding of the molecular pathophysiology of hearing and balance disorders increases, the delivery of genes is becoming central to our ability to manipulate the function of the inner ear. This study evaluates the efficacy of gene transfer and the distribution of three different vector types within the inner ear. Adenovirus vectors, herpes virus vectors and liposomes carrying a plasmid with the green fluorescent protein or beta galactosidase marker genes and a CMV promoter were introduced into the inner ear of 3-month-old mice. The temporal bones and brain were then removed from the animals and examined for transgene expression. Distribution of staining in the treated ear was compared with distribution of staining in the contralateral inner ear. Staining for T cell markers was also carried out to determine inner ear immune response to gene transfer. Herpes virus vectors appear to target neurons most efficiently. Liposome vectors were least efficient in terms of gene transfer. Adenovirus vectors accomplished gene transfer to the widest variety of inner ear cells including auditory and vestibular hair cells. Newer generation adenovirus vectors promise less immune reaction and toxicity than traditional vectors and will be useful for both research and future clinical applications.

Animals↗
PubMed2001

Effects of light intensity, n-alcohols, water-soluble colorants, and solution viscosity on photoisomerization of sorivudine.

Effects of various factors, such as light intensity, polarizability of n-alcohol solvents, addition of colorants, and viscosity of solutions on the kinetics of the photoisomerization of therapeutically effective E-isomer of sorivudine to its less effective Z-isomer were studied. Solutions of known concentrations of E-isomer or Z-isomer in water or in a series of n-alcohols were directly exposed to ultraviolet (UV) A light, or visible light of 400 or 900 foot candles (fc). E-isomer solutions containing various colorants at 1% w/v, or in a series of poloxamer solutions of different viscosities, were also exposed to 400 or 900 fc light. Using the stability-indicating HPLC assay, which showed mass-balance between the starting isomer and the converting isomer, the kinetics of photoisomerization were monitored. The photoisomerization reaction, which takes place on the vinyl side chain, was found to be a first-order reversible reaction. In water, the rate of conversion of E-isomer to Z-isomer was faster than that of Z-isomer to E-isomer, since, E-isomer with higher extinction coefficient absorbed substantially more light than Z-isomer. The rate of photoisomerization increased with the intensity of the visible light and was very rapid in the presence of UV A light (300 to 400 nm), which is to be expected based on the 239 nm and 283 nm absorption maxima of sorivudine. Addition of water-soluble colorants retarded the photoisomerization process significantly, especially as the maximum absorption wavelengths (lambda max) of the colorants approached the UV region. The rate of photoisomerization increased with increasing polarizability (alpha s) of the n-alcohol solvents. Polarizable solvents such as alcohols could compensate for the electron density built up in the excited state, and thus facilitated the photoisomerization process. The rate of photoisomerization decreased as the viscosity of solution increased. This may be attributed to the fact that the twisting of the C=C bond in the excited state can be inhibited by the friction imposed by the viscous medium.

Alcohols↗
PubMed2001

Magnetic resonance imaging of coronary arteries.

Conventional x-ray angiography is presently the gold standard for detecting coronary artery disease. This is a highly invasive procedure with a risk of developing potentially serious complications in addition to its drawback of exposure to ionizing radiation. Magnetic resonance imaging (MRI), a noninvasive method with no known adverse effects, offers exciting possibilities with its ability to acquire true three-dimensional (3D) volume information, image double oblique tomographic planes in the body, and generate excellent soft tissue contrast. These advantages have led to the emergence of MRI as one of the important tools for cardiac imaging. There have been significant improvements in MR systems in recent years that allow for higher gradient subsystems and higher slew rates. This has enabled the realization of magnetic resonance (MR) angiography, which now is consistently used for imaging the head, neck, and body vasculature. Despite all these advances, coronary MR angiography remains a challenge due to the small size of the coronary vessels, their tortuous nature, and the sensitivity of MRI to motion. Different methods, such as electrocardiographic gating and breath-holding or free-breathing approaches using navigators, have been investigated to overcome the cardiac and respiratory motion in coronary MR angiography, respectively. Various pulse sequences have been used in conjunction with these strategies. Injection of extravascular contrast agents led to the improvement of angiographic techniques in terms of higher signal-to-noise and contrast-to-noise ratios. The advent of intravascular agents may improve further the quality and reliability of coronary MR angiography. Recently, true fast imaging with steady-state precession (FISP), an imaging technique with an inherently high imaging efficiency, has emerged as a new angiographic technique. Although coronary MR angiography is still not proven clinically, it is a promising modality for detecting coronary artery disease.

Contrast Media↗
PubMed2001

Understanding dynamic state changes in temporal lobe epilepsy.

The authors review their work in applying nonlinear dynamics to predict onset of seizures in patients with medically refractory temporal lobe epilepsy. The underlying mathematical methodology is presented in some detail. To illustrate their approach, they present an extensive discussion of the analysis of preictal data from two seizures of one patient, and from one disease-free subject. They find similar behavior in some nonlinear measures across seizures, which suggests the possibility of forming a robust method of seizure prediction. However, despite clinical and electrographic preictal and ictal similarity, they have also found marked heterogeneity in other nonlinear measures of preictal activity across seizures arising out of stage 2 nonrapid eye movement sleep. The underlying basis for this variation remains uncertain and needs to be the subject of further intense study to gain a better understanding of the dynamic basis of epilepsy. The origin of these heterogeneities may or may not be related to the much larger differences in nonlinear measures between patients and disease-free subjects. To understand these differences, the authors think it is crucial to pay close attention to potentially confounding factors such as behavioral and other state changes, and to study and report in detail the ways in which relevant nonlinear measures behave in the presence of such changes, independent of seizure onset.

Adolescent↗
PubMed2001

Granulocyte-macrophage colony-stimulating factor in a combination gene therapy strategy for head and neck cancer.

OBJECTIVES/HYPOTHESIS: Gene therapy offers a new approach for treatment of head and neck squamous cell carcinoma (HNSCC). This study examined the effectiveness of granulocyte-macrophage colony-stimulating factor (GM-CSF) in combination gene therapy strategy against HNSCC in an orthotopic mouse model. STUDY DESIGN: Experimental animal research. METHODS: Established tumors were treated with recombinant adenovirus constructs containing the genes for murine granulocyte-macrophage colony-stimulating factor (Ad-mGM-CSF), murine interleukin 2(Ad-mIL-2), or herpes simplex virus thymidine kinase (Ad-tk). RESULTS: The combination of Ad-mGM-CSF or Ad-mIL-2 and Ad-tk resulted in significantly greater reduction in tumor size versus other treatment groups or control subjects. There was no statistical significance between the triple combination of Ad-mGM-CSF, Ad-mIL-2, and Ad-tk versus Ad-mIL-2 and Ad-tk at 1 to 2 weeks after treatment. There was no tumor reduction seen from Ad-mGM-CSF alone and no additional benefit seen from Ad-mGM-CSF combinations in long-term follow-up studies. The greatest cytotoxic T-lymphocyte and natural killer cell activity occurred in the combination Ad-mIL-2 and Ad-tk groups with and without Ad-mGM-CSF. CONCLUSION: Results suggest that the additional mGM-CSF did not enhance the immunogenicity of the HNSCC. Optimal activation of T lymphocytes may require additional co-stimulatory molecules to stabilize the interaction of the T lymphocyte and antigen presenting cell. The presence of major histocompatibility complex Class II may increase CD4+ T-cell mediated immunogenicity and augment therapeutic antitumor immune responses in combination with tk, mIL-2, and mGM-CSF.

Adenoviridae↗
PubMed2001

Combination nonviral cytokine gene therapy for head and neck cancer.

OBJECTIVE: To establish the feasibility and efficacy of combination nonviral murine interferon-alpha (mIFN-alpha)and murine interleukin-2 (mIL-2) or murine interleukin-12 (mIL-12) gene therapy for head and neck squamous cell carcinoma in a murine model. STUDY DESIGN: Randomized controlled studies in a murine head and neck cancer model were performed to assess antitumor responses, secondary cytokine expression, and both natural killer (NK) cell and cytolytic T-cell (CTL) activity. METHODS: Tumors were established in the floor of mouth in C3H/HeJ immunocompetent mice. Established tumors were directly injected with polymer-formulated murine interferon-alpha (mIFN-alpha), lipid-formulated mIL-2, and polymer-formulated mIL-12 alone or in combination. Primary and secondary cytokine expression,NK cell activity, and CTL activity were assayed. RESULTS: The use of mIFN-alpha gene therapy in combination with either mIL-2 or mIL-12 resulted in significant antitumor effects as compared with each of the single cytokine and control treatment groups (P = .002). Increased levels of NK cell activity and tumor specific CD8+ cytotoxic T-lymphocyte activity were found in the combination mIFN-alpha and mIL-2 or mIL-12 groups. Augmented immune responses correlated with clinical antitumor effects. CONCLUSIONS: The present study demonstrates that mIL-2 or mIL-12 augments tumor inhibition from mIFN-alpha and increases activation of NK and CD8+ T cells. These data support further investigation of polymer and lipid mediated delivery of cytokine genes for head and neck cancer.

Animals↗
PubMed2001

Effects of a modified sandblasting surface treatment on topographic and chemical properties of titanium surface.

A modified sandblasting surface treatment (a noncoating, roughening surface modification of dental implants) has been developed that will overcome the defects of conventional coating techniques. To verify the feasibility and reliability of this method at the chemical and topographic levels, scanning electron microscopy, x-ray diffraction, and a titanium ion releasing test were used; the topography of titanium surface, the embedding of sandblasting particles, nonpollution of heteroelements, and anticorrosiveness of titanium were criteria. Results showed that the rough surface created by sandblast was rather irregular, full of sharp tips and many embedded sandblast particles, and its corrosive rate was increased. These characteristics were modified by oxalic acid attack; the contour of the rough surface became more regular and round, the embedded particles and the heteroelement pollution were thoroughly removed, and the Ti corrosive rate decreased dramatically. Oxalic acid attack modification also created numerous secondary micropores (2.0-micron diameter) on the basis of sandblasted surface macrotexture. This modified sandblasting surface treatment is feasible and reliable to apply to dental implants and does not decrease the biocompatibility of titanium.

Aluminum Oxide↗
PubMed2001

Bone interface of dental implants cytologically influenced by a modified sandblasted surface: a preliminary in vitro study.

To study the influences of a modified sandblasted surface (developed by the authors) on the integrating status of titanium (Ti) dental implants and bone in vitro, a three-dimensional experimental model of implant material-osteoblast culture was used. The interaction of Ti discs and osteoblasts at the interface was followed with phase-contrast microscope examination and was further observed histologically and ultra-structurally after one-month culture. Results showed that there was no significant difference between the modified sandblasted surface group and the smooth surface group in the capacity of osteoblasts migrating and attaching to Ti discs. There was, however, a significant difference in the pattern of attachment. Around the polished surface, the migrating and attaching osteoblasts oriented themselves parallel to it; however, around the modified sandblasted surface, the osteoblasts were migrating and attaching perpendicularly. There was also a major difference in the shapes of cells lining the interface; spindle-shaped on the smooth surface versus round and ovoid with a large cellular body and abundant cytoplasm on the modified sandblasted surface. Moreover, transmission electron microscopy revealed an active secretion of collagen fibrils, a bone-matrix-vesicles-mediated mineralization process, and the formation of osteocytes in the modified sandblasted surface group. Therefore, at this in vitro level, it can be concluded that the modified sandblasting surface treatment of dental implants can facilitate bone healing at their osseous interface and enable the real perpendicularly connecting bone-fiber osseointegration to form instead of the capsule-like osseous adaptation.

Cell Adhesion↗
PubMed2001

Color stability of provisional restorative materials after accelerated aging.

PURPOSE: Color of 11 provisional restorative materials (4 acrylic resins and 7 resin composites) was evaluated by reflection spectrophotometry immediately after fabrication, after aging for 15 kJ/m(2), and after aging for 60 kJ/m(2) to determine relative color stability under experimental aging conditions. MATERIALS AND METHODS: Specimens of provisional restorative materials were polymerized according to manufacturers' instructions and aged in an artificial aging chamber with exposure to a total ultraviolet irradiation of 60 kJ/m(2) in increments of 15 kJ/m(2). Color was measured by CIE L*a*b* on a reflection spectrophotometer before and after aging. Color change (Delta E*) was calculated and analyzed statistically by analysis of variance with repeated measures after 15 and 60 kJ/m(2) intervals of aging. RESULTS: Statistically significant changes in color were observed after accelerated aging at both the initial and final aging intervals. Five of the 11 provisional materials tested showed perceptible color change (Delta E* from 3.6 to 9.3) after accelerated aging of 15 kJ/m(2). Seven of the 11 provisional materials tested showed perceptible color change (Delta E* from 3.4 to 9.4) after accelerated aging of 60 kJ/m(2). CONCLUSIONS: Clinically perceptible color changes (Delta E* Delta 3.3) can be expected in some acrylic resin and composite resin provisional materials after accelerated aging.

Acrylic Resins↗
PubMed2001

The Hong Kong Bridge Protocol. Immediate loading of mandibular Brånemark fixtures using a fixed provisional prosthesis: preliminary results.

BACKGROUND: The Brånemark System Classic is well documented for its successful and predictable results in dental implant rehabilitation. However, the classic two-stage protocol is associated with problems, such as long treatment time and high treatment cost. To overcome these problems, new developments, including early functional loading protocol and Brånemark System Novum, have been introduced by various groups of researchers. In Hong Kong, a protocol has been developed to immediately load the Brånemark System fixtures with a fixed provisional prosthesis. PURPOSE: The goal of this prospective study was to present the Hong Kong Bridge protocol and report the short-term evaluation of this protocol in a group of patients who had undergone dental implant treatment for their edentulous mandibles. MATERIALS AND METHODS: Twenty-seven consecutive patients being treated at the Hong Kong Osseointegration Implant Centre between June 1998 and December 2000 were included in this study. A total of 123 Brånemark System fixtures were installed and regularly followed up for 3 to 30 months. The prosthesis stability and the marginal bone level were regularly evaluated clinically and radiographically, respectively, after the implant surgery. RESULTS: Fifteen of the 27 patients had been followed up for 1 year or longer. Two patients with eight fixtures were withdrawn from the study. Two of the 115 remaining fixtures failed, resulting in an overall implant survival rate of 98.3%. The mean marginal bone change was reported on 49 fixtures that had passed the 1-year review. The mean marginal bone loss was 0.60 mm (p < .05) after 1 year of functional loading. CONCLUSIONS: To load the mandibular Brånemark System fixtures immediately according to the Hong Kong Bridge protocol was a predictable and simple method with good results during this preliminary study period.

Adult↗
PubMed2001

Immediate provisional for single-tooth implant replacement with Brånemark system: preliminary report.

BACKGROUND: The success of osseointegrated implants ad modum Brånemark for single-tooth restorations is documented. Future developments should aim at improving the benefits to patients by decreasing treatment time, minimizing surgical stages, and maximizing esthetic outcomes. Using knowledge from studies of immediate implant placement, one-stage, immediate loading protocols, the authors developed the immediate provisional. PURPOSE: The purpose of this study was to develop a protocol to provide an immediate solution for restoring a single missing tooth in the esthetic zone. The protocol should be simple, predictable, cost effective, and allow the use of other techniques to improve esthetic outcome. MATERIALS AND METHOD: This prospective clinical study included 24 patients treated from August 1999 to October 2000. Single-tooth implant replacement was done according to immediate provisional protocol. Thirteen of the 24 patients had immediate implant placement after tooth extraction. All implants were placed in the esthetic zone. During surgery, emphasis was placed on obtaining primary stability by achieving bicortical anchorage and maximum insertion torque of at least 40 Ncm. CeraOne (Nobel Biocare) abutments were used, and provisional crowns were fabricated immediately before wound closure. The occlusion was protected by adjacent teeth. RESULTS: Within the follow-up period of between 1 month and 15 months, all fixtures in the 24 patients were stable. Crestal bone loss greater than one thread-width was not detected. The esthetic result was considered satisfactory by all patients. CONCLUSIONS: The implant placement and restoration protocol used in this study showed promising initial results for both the immediate implant and healed extraction site groups. The desirable goals of patient satisfaction, excellent esthetic outcomes, and no increase in treatment cost were achieved in this protocol. Further studies to elucidate the potential of the immediate provisional protocol are justified.

Adolescent↗