Controlled local delivery of tetracycline in the treatment of periodontitis.
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Administration, Topical↗
Biomedical subjects
C M Cobb
Publications and source records attributed to C M Cobb.
The dentinal surface: its influence on dentinal adhesion. 2.
The first paper in this series presented a categorization of dentinal adhesive systems that was organized roughly according to chronology, chemistry, and shear bond strength values. Category I dentinal adhesives demonstrate the lowest shear bond strength values, approximately 5 to 7 MPa. Category II dentinal adhesives, including experimental ferric and aluminum oxalate pretreatments and two commercial products, demonstrate shear bond strength values between 8 and 14 MPa. This second category of dentinal adhesives is the subject of this paper. An attempt is made to draw a parallel between the penetrative ability of the adhesive (the wettability of the dentinal substrate) and the efficacy of the adhesive bond as determined by shear bond strength values. Category III dentinal adhesives will be discussed in another paper.
Adhesives↗
Microbial contamination in four brands of irreversible hydrocolloid impression materials.
A previous investigation showed unopened irreversible hydrocolloid impression material to be contaminated with viable microorganisms. This study tested and compared four brands of commercial irreversible hydrocolloid impression material in factory-sealed containers for the presence of viable microorganisms. Twenty-four measured samples of each brand were taken from previously unopened containers using a sterile technique. The samples were placed on chocolate agar plates or in thioglycolate broth tubes and were incubated along with appropriate parallel controls. After incubation, colonies were enumerated, stained with Gram's stain and identified using standard microbiologic methods. The four brands contained viable organisms in 50% to 100% of the samples incubated of agar media, and in 12% to 67% of the samples incubated in thioglycolate media. Samples from the top and middle portions of the containers had approximately equal contamination frequencies. The concentration of organisms varied from 12 to 82 colony-formed units per gram of contaminated sample. Most organisms isolated were common environmental contaminants. These samples contained viable microorganisms which, during routine use, may present a hazard to immunocompromised patients.
Actinomyces↗
Multicenter evaluation of tetracycline fiber therapy: I. Experimental design, methods, and baseline data.
The study design and baseline characteristics of a multicenter trial to test the effectiveness and safety of locally delivered tetracycline for treatment of adult periodontitis are described. Local delivery was provided by 0.5 mm diameter ethylene vinyl acetate copolymer fibers loaded 25% with tetracycline hydrochloride which were placed into periodontal pockets and maintained by an adhesive for 10 (+/- 2) days. A total of 113 subjects (56 male and 57 female; mean age 49.3 yr) at five centers participated in the study. Subjects were selected who had 4 nonadjacent teeth with 6-10 mm pockets that bled on probing. The selected sites in each subject were randomly assigned to 4 test groups: tetracycline fiber, control fiber, scaling with root planing, or untreated. A balanced experimental design was thereby established in which each subject contributed equally by providing 4 clinically comparable sites for evaluation. To provide a more specific model for testing periodontitis therapy, gingivitis was treated prior to the initiation of the study by prophylaxis with supragingival calculus removal and home care instruction. Clinical response variables measured were pocket depth reduction, attachment level gain and bleeding on controlled-force probing measured at baseline, 30 d, and 60 d. Levels of 6 bacterial species selected as probable periodontal pathogens were measured by DNA probe analysis of plaque samples. The design of this study provided several unique analytical opportunities. Controls included a comparison with conventional treatment, analysis of vehicle effects, and effects at untreated sites. Comparison of the test group with controls permitted evaluation of the principal variables that could effect interpretation of results.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Multicenter evaluation of tetracycline fiber therapy: II. Clinical response.
The safety and efficacy of periodontal disease treatment by intrapocket placement of tetracycline (TC) fibers was investigated in a 60-day multicenter study conducted by selecting 4 sites in each subject with 6-10 mm pockets that bled on probing. Sites were randomly assigned to 1 of 4 test groups: TC fiber therapy, scaling, control fiber (fibers without drug), or untreated. TC fibers and control fibers were placed to fill the pocket and were maintained with a cyanoacrylate adhesive for 10(+/- 2) d. Scaling was performed for a minimum of 5 min under local anesthesia. Following initial tooth cleaning procedures, pocket depth, attachment level and bleeding on controlled-force probing were measured at baseline and at 30 d, and 60 d following therapy. Analysis of data from 107 subjects who had complete clinical data sets indicated that TC fiber therapy significantly decreased pocket depth, increased attachment level, and decreased bleeding on controlled-force probing to a greater extent than observed in all other test groups including scaling. These effects were greater than, and in addition to, effects that occurred due to prophylaxis and improved home care. No serious adverse side-effects attributed to TC fiber therapy were observed. No TC fiber-treated sites abscessed and superinfection was not noted. A transient redness at fiber removal was seen at 21% of the sites. Although fibers were placed without anesthesia, mild pain on initial placement was infrequent (19%) and abated rapidly. The results indicate that TC fiber placement provides a safe and effective means for treatment of periodontal infections.
Adult↗
In vitro chemotactic response of osteoblast-like osteosarcoma cells to a partially purified protein extract of demineralized bone matrix.
The purpose of this investigation was to evaluate the chemotactic potential of a partially purified protein extract from bone matrix when tested against osteosarcoma cells with osteoblast characteristics. The chemotactic response of ROS 17/2 cells to a lyophilized bovine bone extract purified to "Urist step eight" was evaluated in Boyden blind well chambers. A checkerboard design was employed to test cell migration against positive, negative, and no concentration gradients, thereby controlling the effects of chemokinesis and/or random migration on results. The results demonstrate that the partially purified protein extract from bovine bone matrix is chemotactic since more cells migrated to positive gradients than to negative gradients (P less than .01). The chemotactic effect was confirmed by an increase in cell migration toward positive gradients of the bone extract compared to cell migration in the presence of no gradient (P less than .01). When no gradient was present, the cells exhibited an increased response in the presence of equal concentrations of the bone extract (P less than .01) indicating a chemokinetic effect. The proteinaceous nature of the chemoattractant was confirmed by its susceptibility to trypsin digestion and heat exposure.
Animals↗
Effects of chlorhexidine and stannous fluoride on fibroblast attachment to different implant surfaces.
This study evaluated, in vitro, the attachment of gingival fibroblasts to dental implants of differing surface character treated with 0.12% chlorhexidine, 1.64% stannous fluoride, or sterile saline. Specimens were divided into three groups, each composed of 18 dental implants. Each group featured a different implant surface texture, ie, smooth titanium, hydroxylapatite plasma-spray, or titanium plasma-spray. Following adsorption of salivary pellicle, six implants from each group were treated with chlorhexidine, stannous fluoride, or sterile saline. They were then cultured with fibroblasts for 24 hours and photographed by scanning electron microscopy. Cell counts were then performed. Analysis of results showed a significantly greater number of fibroblasts attached to specimens treated with saline or chlorhexidine than to those treated with stannous fluoride. Furthermore, fibroblasts were more likely to attach to rough-surfaced than to smooth-surfaced specimens.
Cell Adhesion↗
The dentinal surface: its influence on dentinal adhesion. Part I.
Three categories of dentinal adhesive are proposed: category I includes adhesives with shear bond strength values between 5 and 7 MPa; category II includes dentinal adhesives with shear bond strengths between 8 and 14 MPa; and category III includes adhesives with shear bond strength values up to 20 MPa. In part I of this article, photomicrographs of the dentinal smear layer and three category I first-generation dentin-adhesive interfaces are presented. The photomicrographs show that the wetting and penetration of the first-generation dentinal adhesives were not adequate to produce high shear bond strengths. When the category I adhesives were tested for shear bond strength, failures occurred at the interface or in the resin adhesive. Future articles will explain wetting and adhesive performance of category II and III adhesives.
Acrylic Resins↗
Aerobic bacterial contamination in dental materials.
Current concern about disease transmission points out the need for better infection control in dentistry. The purpose of this study was to test samples of dental materials in factory-sealed containers for aerobic bacterial contamination. Multiple unopened containers of 12 different dental materials were obtained from the dental school dispensary. Samples were removed from each container and incubated at 38 degrees C in standard broth medium for 1 week. Those that exhibited visual signs of possible bacterial growth were subjected to a Gram stain for verification. The results of that test indicated that 20% to 30% of the samples of alginate, glass ionomer cement and base powders, and retraction cord contained bacterial contamination. The remaining eight dental materials exhibited no apparent bacterial growth. Thus viable aerobic organisms were found in samples from 4 of 12 dental material products.
Air Microbiology↗
Mechanical behavior of mandibular continuity defects reconstructed using combinations of hydroxylapatite and autogenous bone.
The purpose of this investigation was to determine the mechanical behavior of primate (Macaca mulatta) mandibles with continuity defects reconstructed using varying ratios of an alloplastic hydroxylapatite (HA) implant material mixed with autogenous bone (AB). The defects were allowed to heal for 6 and 18 months before killing the animals and mechanical testing. Each animal had one side of the mandible restored with 100% AB as control. The fracture strength and section modulus of the opposite side of the mandible, containing the test ratio of HA-AB, were directly compared with the mechanical behavior of the control side. The fracture strength and section modulus were evaluated by a cantilever type of mechanical test that took into account the anisotropic, viscoelastic, and geometric nature of the mandible. The type of bone and tissue at the fracture site was examined by scanning electron microscopy and a direct correlation between the amount of bone and/or fibrous tissue growth around the HA implant material and the fracture strength and section modulus values was established. The average fracture strength of the AB graft sites at 18 months was 9,975 +/- 4,300 psi, with ratios of 25:75 and 50:50 HA-AB giving test results approaching those of the AB graft sites.
Alveolar Ridge Augmentation↗
Restoration of mandibular continuity defects using combinations of hydroxylapatite and autogenous bone: microscopic observations.
The purpose of this investigation was to assess by light, transmission, and scanning electron microscopy the healing of mandibular continuity defects reconstructed with varying ratios of an alloplastic hydroxylapatite implant material (HA) mixed with autogenous bone (AB). This study reports the microscopic observations of implant and control sites at 6 and 18 months postsurgery. The results confirm the biocompatibility of dense HA granules. Specimens exhibited differing degrees of osseous regeneration that appeared related to the percent composition of HA. At 18 months, 86% and 91% of the HA granules were completely surrounded by bone in those specimens reconstructed with implants consisting of 25% and 50% HA, respectively. In contrast, specimens receiving implants consisting of 75% and 100% HA features osseous encapsulation of 75% and 66% of the granules, respectively. The results of this limited study indicate that dense HA granules mixed with AB in ratios ranging from 3:1 to 1:1 (AB:HA) may be successfully used as a bone extender during reconstructive surgery.
Animals↗
Ultrastructural evidence of large granular lymphocyte (LGL) activity in lesions of chronic adult periodontitis.
The purpose of this investigation was to determine, on the basis of ultrastructural evidence, whether large granular lymphocyte (LGL)-mediated cytotoxic activity could be identified in lesions of chronic adult periodontitis. 18 gingival papilla biopsies were obtained from 8 adult patients, each satisfying the clinical criteria for chronic adult periodontitis. One-half of each biopsy was processed for examination by transmission electron microscopy (TEM). B-lymphocyte, T-lymphocyte, and NK-cell contributions to the inflammatory cell infiltrate were determined by subjecting the remaining one-half to the 3-layer avidin-biotin affinity immunoperoxidase technique. Immunohistochemistry using the anti-human leu-11b monoclonal antibody (representative of NK-cells which are known to comprise approximately 80% of the LGL population) showed that the Leu-11b+ population comprised 3-7% of the total monocytic infiltrate. The Leu-11b+ cells tended to occur as single cells or in small clusters of 3-12 cells. Generally, the Leu-11b+ cells exhibited perivascular locations situated subjacent to the epithelial basal lamina. TEM observations showed LGLs in intimate contact with fibroblasts that exhibited morphologic changes consistent with cellular damage or degeneration. In addition, LGLs were observed to exhibit apparent non-cytotoxic contacts with plasma cells, macrophages and other monocytic cells.
Adult↗
Microscopic characterization of root surface-associated microbial plaque in localized juvenile periodontitis.
The purpose of this investigation was to characterize by scanning electron microscopy, the microbial morphotypes associated with the roots of teeth from patients exhibiting localized juvenile periodontitis (LJP). Eighteen teeth were examined from 10 adolescent patients who satisfied the standard clinical diagnostic criteria for LJP. The microscopic evaluation was facilitated by dividing that portion of the root exposed to the periodontal pocket into coronal, middle, and apical one-thirds. Controls consisted of an equal number of teeth matched as to pocket depth and anatomical type obtained from patients exhibiting adult periodontitis (AP). All specimens were coded and examiners were unaware of their origins. Results of the SEM evaluation revealed little difference in microbial morphotypes comprising the root associated plaque in the coronal one-third of LJP specimens when compared to the AP controls. The dominant microbial morphotypes were cocci, short and long rods, filamentous microorganisms, and spirochetes. However, microbial plaque located in the middle and apical one-third root zones of LJP specimens was distinctly different than that of AP specimens. In the deeper pocket zones the dominant microbial morphotypes in LJP specimens were limited to cocci, short rods, coccobacilli, and various sized spirochetes. In contrast, AP specimens exhibited a collection of microbial morphotypes consisting of cocci, short rods, long rods, filamentous organisms and spirochetes. Calculus was found on the root surfaces of all specimens regardless of disease category although, as a group, the LJP specimens featured lesser amounts. Although areas of root resorption were common in both LJP and AP groups, they were more frequently observed in LJP specimens, likely associated with the generally less confluent deposits of calculus and plaque.
Adolescent↗
Microbial colonization in human periodontal disease: an illustrated tutorial on selected ultrastructural and ecologic considerations.
The oral cavity is populated by a prodigious microbial flora that exhibits a unique successional colonization of enamel and subgingival root surfaces. A wide range of oral sites provide different ecologic conditions and are, therefore, populated by different commensal microbial combinations. The sequence of microbial colonization, regardless of location within the oral cavity, commences with the acquisition of salivary and/or crevicular fluid-derived pellicle. As the process of successional colonization of the gingival crevice area proceeds uninterrupted, achieving critical mass between 10 and 21 days, gingivitis becomes evident at a clinical level. However, at a histologic level, gingivitis may be evident within 2-3 days of plaque accumulation. The inflammatory response sufficiently alters the ecological conditions so as to allow proliferation of supragingival plaque into subgingival areas. The subgingival plaque becomes progressively more Gram-negative and anaerobic in nature as the periodontal pocket deepens, leading ultimately to a chronic, progressive deterioration of the periodontium--adult periodontitis. Both gingivitis and adult periodontitis are characterized by the successive colonization of cocci, short and long rods, filamentous microbes with "corn cob" and "bristle brush" formations, flagellated microbes, and spirochetes. Localized juvenile periodontitis (LJP), in contrast to the adult form of periodontitis, features a comparatively sparse microbial flora. The subgingival microbial colonization characteristically features cocci, short rods, coccobacilli, and spirochetes.
Adolescent↗
Chronic pulmonary histoplasmosis with an oral lesion.
Histoplasmosis is a fungal disease resulting from inhalation of airborne spores of the organism Histoplasma capsulatum. The disease is endemic to the Ohio and Mississippi river valleys. Oral lesions are not common, but when present, they are usually associated with the severe disseminated form of histoplasmosis. This particular case is presented as an example of chronic pulmonary histoplasmosis in which a localized gingival lesion represented the initial clinical manifestation of the disease. Diagnosis was based on a positive biopsy and the results of chest radiographic examination. If, as in this case, serologic, hematologic, and physical examination results are negative, the biopsy of suspicious lesions is of paramount importance to the clinical differential diagnosis.
Aged↗
Scanning electron microscopic examination of pocket wall epithelium and associated plaque in localized juvenile periodontitis.
The purpose of this investigation was to describe the morphologic characteristics of epithelial-associated plaque in periodontal pockets of patients with localized juvenile periodontitis (LJP). 25 tissue specimens obtained from 10 adolescent patients were examined by scanning electron microscopy. Specimens were evaluated to determine the following specific features: (1) distribution of microbial colonies on the epithelial surface; (2) topographic features of pocket epithelium associated with microbial colonies; and (3) the predominante microbial morphologic types comprising the colonies. Observations made during this investigation revealed the following. (1) The surface epithelium in the coronal one-third of the pocket wall was essentially healthy in appearance and exhibited no distinct microbial colonies or unusual topographic features. (2) The surface epithelium in the middle one-third area featured randomly-dispersed microbial colonies consisting of 3 major morphotypes: cocci, bacilli and coccobacilli. Also in this zone, there was morphologic evidence of microbial penetration of the epithelial barrier along intercellular spaces. (4) The apical one-third zone was characterized by lymphocytic infiltration, epithelial cavitation and ulcerations, and singular organisms entrapped in fibrin meshworks. There were no distinct microbial colonies in this zone, although individual spirochetes, fusiforms, filamentous organisms, and short and long rods were observed.
Adolescent↗
Comparison of NK-cell (Leu-7+ and Leu-11b+) populations in clinically healthy gingiva, chronic gingivitis and chronic adult periodontitis.
Various investigations have reported the presence of cytotoxic lymphocyte activity in inflammatory periodontal disease. The collective evidence indicates that the inflammatory infiltrates of gingivitis and periodontitis should feature a major component of large granular lymphocytes (NK-cells) possessing cytotoxic potential. Thus, the purpose of this study was to determine and compare, by use of immunohistochemical methods, the numbers of NK-cells in biopsies of clinically healthy gingiva, chronic gingivitis and chronic adult periodontitis and their relationship, if any, to the T- and B-lymphocyte populations. Gingival biopsies were obtained from 8 patients in each of three disease groups selected on the basis of predetermined clinical criteria. Using the avidin-biotin immunoperoxidase technique, four consecutive serial sections from each biopsy specimen were stained with a panel of antihuman monoclonal antibodies for T-lymphocytes (UCHL-1) B-lymphocytes (CD-45R), and NK-cells (Leu-7 and Leu-11b). Analyses of variance yielded a statistically significant main effect for each cell immunophenotype. The Newman-Keuls Sequential Range Test showed statistically significant differences for all but two mean comparisons (p less than 0.01). The comparisons for UCHL-1 and Leu-7 between chronic gingivitis and periodontitis specimens did not demonstrate significance. Although T- and B-lymphocyte populations increased approximately 20 x progressing from healthy to gingivitis to periodontitis specimens, the NK-cell population showed only a 3 x increase which represented 19%, 6.6% and 7% of the total of all positively stained lymphocytes across biopsy groups.
Adolescent↗
In vitro model of Treponema pallidum invasiveness.
The purpose of this investigation was to develop an in vitro model with which invasion of tissues by pathogenic Treponema pallidum could be studied. Double-sided culture chambers were created by mounting abdominal walls excised from mice between two halves of small dialysis cells. The integrity of tissue barriers was confirmed by dye exclusion. T. pallidum subsp. pallidum, including intrinsically radiolabeled organisms, was introduced into one side of each chamber, and fractions from the other side were evaluated over time by dark-field microscopy and scintillation counting. Tissues were evaluated by scanning electron microscopy and immunologic staining. Motile T. pallidum, but not nonpathogenic, host-indigenous Treponema phagedenis biotype Reiter, was able to pass from one side of the chamber to the other side within 10 h. Up to 12% of the inoculum crossed the chamber within 24 h. Spirochetes were found within tissue in the greatest numbers between 6 and 8 h postinoculation. The murine abdominal wall has epithelium only on the peritoneum side, and results showed that T. pallidum required an epithelial surface on the entry side of the double-chambered cell in order to traverse the tissue barrier. This new in vitro technique may be of value in studying spirochete virulence and host resistance.
Abdominal Muscles↗