bluuebunny/crossref_metadata_2025 huggingface dataset:
Oral Health Beliefs in Diverse Populations
Authors: Nakazono T.T. , Davidson P.L. , Andersen R.M.
Published: January 2009

Using data from population-based samples of adults participating in the ICS-II USA study, and using principal components analysis, we constructed oral health belief measures corresponding to the Health Belief Model (HBM) dimensions. Tests of validity and reliability were performed. Scales measuring perceived benefit of preventive practices and seriousness of oral disease had the highest validity and reliability. We used multiple regression analysis to examine sociodemographic predictors of perceived benefits of preventive practices. Race-ethnicity and age cohort were significant predictors among Baltimore and San Antonio adults. White adults and middle-aged persons in both research locations were more likely to believe in the benefit of preventive practices. Female gender, higher educational attainment, and better self-rated health were significant indicators of more positive oral health beliefs in every research location. Results also characterize persons who place lower value on preventive practices (i.e., males, less-educated persons, and those reporting poorer self-rated health). The design of effective dental public health messages and outreach efforts requires an analysis of the individual's health orientation and the factors influencing oral health beliefs. Oral health education interventions designed to improve health beliefs should contain an evaluation component for assessing the impact of education on health practices and oral health status.
Socio-Behavioral Determinants of Oral Hygiene Practices Among USA Ethnic and Age Groups
Authors: Davidson P.L. , Rams T.E. , Andfrsen R.M.
Published: January 2009

In this study, socio-behavioral determinants of oral hygiene practices were examined across several dentate ethnic and age groups. Oral hygiene scale scores were constructed from toothbrushing and dental floss frequencies self-reported by population-based samples of middle-aged (35-44 years) and older (65-74 years) dentate adults representing Baltimore African-American and White, San Antonio Hispanic and non-Hispanic White, and Navajo and Lakota Native American persons participating in the WHO International Collaborative Study of Oral Health Outcomes (ICS-II) survey. Female gender, education, certain oral health beliefs, household income, and the presence of a usual source of care were revealed with multivariate analysis to show a significant positive relationship with higher oral hygiene scale scores (indicating better personal oral hygiene practices). Other socio-behavioral variables exhibited a more varied, ethnic-specific pattern of association with oral hygiene scale scores.
Determinants of Dental Care Utilization for Diverse Ethnic and Age Groups
Authors: Davidson P.L. , Andersen R.M.
Published: January 2009

Dental services utilization in the past 12 months was compared across population-based samples of African-American, Navajo, Lakota, Hispanic, and White adults participating in the WHO International Collaborative Study of Oral Health Outcomes (ICS-II) at USA research locations. Bivariate results revealed that ethnic minority groups in both age cohorts reported significantly fewer dental visits in the past 12 months compared with White adults. When dentate status was controlled for, age cohort differences were not significant in Baltimore (African-American and White) and San Antonio (Hispanic and White) research locations. In contrast, older Native Americans (65-74 years) reported visiting the dentist significantly less often compared with their middle-aged (35-44 years) counterparts. Multivariate results indicated that generalizable variables were associated with dental contact in every ICS-II USA ethnic group (i.e., dentate, usual source of dental care, oral pain). Among the diverse ethnic groups, other determinants presented a varied pattern of risk factors for underutilizing dental care. Information on ethnic-specific risk factors can be used to design culturally appropriate and acceptable oral health promotion programs. Generalizable risk factors across ethnic groups inform oral health policy-makers about changing national priorities for promoting oral health.
Oral Effects of Smokeless Tobacco Use by Professional Baseball Players
Authors: Robertson P.B. , Walsh M.M. , Greene J.C.
Published: January 2009

This is a review of studies conducted from 1988-90 on the oral consequences of snuff and chewing tobacco use among professional baseball players. About half of the players studied were smokeless tobacco (ST) users, the majority of whom used snuff. Compared with non-users, players who used ST showed a significantly higher prevalence of leukoplakia, which was related to placement of the ST quid, and the frequency, amount, duration, and type of ST used. Sites adjacent to these mucosal lesions showed an increased prevalence of gingival recession with associated attachment loss, cervical abrasion, and root caries than did comparable sites in non-users. Extrinsic stain and occlusal attrition were also more frequent in ST users than in non-users. While ST use placed players at significantly increased risk for mucosal lesions and other oral problems, no differences were found between ST non-users and users in measurements of batting, fielding, and pitching performance during the baseball season.
Epidemiology of Cancer and Other Systemic Effects Associated with the Use of Smokeless Tobacco
Authors: Winn D.M.
Published: January 2009

Persons who use chewing tobacco and snuff experience an increased risk of oral cancer. Because of the pharmacologic properties of nicotine and other constituents of smokeless tobacco, there is also concern that smokeless tobacco products may lead to cardiovascular diseases as well. The relatively few human population studies to date conflict with respect to whether smokeless tobacco use elevates cardiovascular risk factors or leads to cardiovascular disease or death from cardiovascular causes. Hemoglobin adducts to carcinogens present in smokeless tobacco products are measurable in the blood of smokeless tobacco users, indicating that smokeless-tobacco-related carcinogens circulate throughout the body. This prompts a concern that smokeless tobacco may increase risks of other cancers as well. The evidence to date from epidemiologic studies indicates no relationship between smokeless tobacco and bladder cancer, but there is suggestive evidence linking smokeless tobacco use to prostate cancer risk. Only single studies have been conducted of some cancers, and inconsistencies among studies of the same cancer site have been reported. Molecular epidemiologic studies may help identify markers of malignant transformation in smokeless tobacco users that may help in early intervention to prevent or ameliorate the consequences of oral cancer. Further studies are needed to determine more clearly the cardiovascular and non-oral cancer risks potentially associated with smokeless tobacco use.
Chemical Composition and Carcinogenicity of Smokeless Tobacco
Authors: Hoffmann D. , Djordjevic M.V.
Published: January 2009

In the United States, smokeless tobacco (ST) is marketed as chewing tobacco and as oral snuff. During the past 15 years, consumption of chewing tobacco has declined by 30.6%, whereas snuff use has significantly increased, namely, by 51.8%. This increase is primarily due to the growing popularity of oral snuff use among teenage and young adolescent males. Chewing of tobacco is associated with an increased risk for oral cancer. Snuff dipping is causally and specifically associated with cancer of the cheek, gum, and pharynx. In laboratory animals, snuff induces cancer of the mouth. Several carcinogens have been identified in ST, the tobacco-specific N-nitrosamine (TSNA), N'-nitrosonornicotine (NNN), and 4(methylnitrosamino)-l-(3-pyridyl)-l-butanone (NNK) being the most important. NNN and NNK are formed from nicotine during curing, aging, and especially during fermentation of tobacco. Oral swabbing of a low concentration of a mixture of NNN plus NNK in water induces oral tumors in rats. The concentration of the strongly carcinogenic TSNA is higher in snuff than in other ST products. According to our analytical studies, the three leading snuff brands in the US (92% of the market) contain far higher concentrations of nicotine, unprotonated nicotine, and TSNA than the less popular brands. Thus, the leading US snuff brands are the strongest inducers of nicotine dependence and also have the highest carcinogenic potential.
A Spit Tobacco Cessation Intervention for College Athletes: Three-Month Results
Authors: Masouredis C.M. , Hilton J.F. , Grady D. , Gee L. , Chesney M. , Hengl L. , Ernster V. , Walsh M.M.
Published: January 2009

Sixteen colleges were matched on the baseline prevalence of spit tobacco (ST) use, and college pairs were randomized, one to the intervention and the other to the control group. Baseball and football athletes at each intervention college received: an oral examination by a dental professional who pointed out ST-related problems in the athlete's mouth and advised him to quit ST use; counseling by a dental hygienist on strategies to cope with cravings and triggers for use; and two follow-up telephone calls. At the three-month follow-up, quit rates were 24% and 16% for the intervention (n = 171) and control (n = 189) groups, respectively (p < 0.05). As the reported amount of ST used weekly increased, the percent of individuals who quit at 3 mos decreased (p < 0.05). Dental professionals appear to be effective in promoting spit tobacco cessation at 3 mos post-intervention in male college athletes, especially among those using lesser amounts of ST.
SIMS of Biomineralized Tissues: Present Trends and Potentials
Authors: Lodding A.
Published: January 2009

The technique of dynamic secondary ion mass spectrometry (SIMS) has, during the 1980s, become a firmly established tool in the microanalytical and microstructural characterization of dental hard tissues. SIMS has proved to be outstandingly suited for charting the distributions of most elements, even at extremely low concentrations, in tooth and bone materials. In-depth concentration profiles as well as surface distribution maps of elements have been recorded with excellent (sub-micron) morphologic resolution. In spite of documented success, only relatively few teams, in a handful of countries, are presently engaged, to any significant extent, in conducting tooth or bone research by the application of SIMS. For dental-medical-surgical laboratories, a partial reason for non-communication is a lack of information about SIMS and its particular assets. Another reason may be connected with an essentially groundless reputation, among non-specialists, of SIMS being an exclusive and expensive technique. Among SIMS laboratories, on the other hand, the inertia in tackling biomineralization is partly due to some particular artifacts of analysis, hitherto not generally known and controlled. The present paper briefly sketches the chief principles of modem SIMS, emphasizing factors of special relevance in the characterization of biomineralized tissues. Examples of recent applications are provided. Present procedures and their limitations are discussed, especially with regard to elemental quantification and imaging. Suggestions for relatively simple modifications to existing routines are offered with the aim of enhancing the ease and availability of SIMS in odontological and surgical research.
The Use of X-Ray Photoelectron Spectroscopy for the Study of Oral Streptococcal Cell Surfaces
Authors: Van Der Mei H.C. , Busscher H.J.
Published: January 2009

Physicochemical and structural properties of microbial cell surfaces play an important role in their adhesion to surfaces and are determined by the chemical composition of the outermost cell surface. Many traditional methods used to determine microbial cell wall composition require fractionation of the organisms and consequently do not yield information about the composition of the outermost cell surface. X-ray photoelectron spectroscopy (XPS) measures the elemental composition of the outermost cell surfaces of micro-organisms. The technique requires freeze-drying of the organisms, but, nevertheless, elemental surface concentration ratios of oral streptococcal cell surfaces with peritrichously arranged surface structures showed good relationships with physicochemical properties measured under physiological conditions, such as zeta potentials. Isoelectric points ap-peared to be governed by the relative abundance of oxygen- and nitrogen-containing groups on the cell surfaces. Also, the intrinsic microbial cell-surface hydrophobicity by water contact angles related to the cell-surface composition as by XPS and was highest for strains with an elevated isoelectric point. Inclusion of elemental surface compositions for tufted streptococcal strains caused deterioration of the relationships found. Interestingly, hierarchical cluster analysis on the basis of the elemental surface compositions revealed that, of 36 different streptococcal strains, only four S. rattus as well as nine S. mitis strains were located in distinct groups, well separated from the other streptococcal strains, which were all more or less mixed in one group.
Application of Transverse Microradiography for Measurement of Mineral Loss by Acid Erosion
Authors: Hall A.F. , Sadler J.P. , Strang R. , De Josselin De Jong E. , Foye R.H. , Creanor S.L.
Published: January 2009

This paper describes a novel application of transverse microradiography for the detection and quantification of mineral loss due to acid erosion in thin tooth sections. Sixty-four specimens were randomly divided into eight equal-sized groups and exposed to an orthophosphoric-acid-based erosive fluid (pH = 3) for 0, 0.25, 0.5, 1, 2, 5, 12, or 24 hrs. We made microdensitometric scans separately across both enamel and dentin to derive data for the total mineral loss and the minimum mineral content within the eroded area. We then analyzed specimens using a profilometer to determine (1) the area above a plot of penetration depth against distance and (2) the maximum depth of penetration. Correlation coefficients for comparisons between microradiographic and profilometric data for both enamel and dentin specimens varied between 0.87 and 0.96. Two-sample t tests demonstrated that the microradiographic technique could detect early erosion, i.e., discriminate between erosion times of less than 1 hr. It was concluded that this application of transverse microradiography was a useful and acceptable method for the measurement of early mineral loss in vitro, occurring as a result of acid erosion.
Applications of Confocal Laser Scanning Microscopy to Dental Bonding
Authors: Pioch T. , Stotz S. , Staehle H.J. , Duschner H.
Published: January 2009

The introduction of confocal laser scanning microscopy (CLSM) has provided a valuable new technique for the visualization of bonding structures such as a hybrid layer in dentin (Watson, 1989, 1991), In the case of seven commercially-available dentin bonding systems, it could be demonstrated that the CLSM renders considerably more detailed information than the SEM because of its nondestructive nature and because of the possibility of a distinction between components of bonding agents. With most of the bonding systems, measurements of the thickness of the hybrid layer could be carried out when the primer component was labeled with rhodamine B. It was found that this thickness is significantly increased by increases in etching time and only slightly decreased by increases in the drying time of the dentin and of the primer. When rhodamine B was used for dye penetration tests on four different dentin bonding systems, a leakage within the demineralized zone in the dentin was found in each of the specimens. This structure appears similar to that which Sano et al. (1995) called "nanoleakage". The amount of nanoleakage could not be measured by this method. In the case of enamel or ceramic bonding, a penetration zone was found which corresponded to the etching patterns found in enamel and ceramics, respectively. We conclude that CLSM can offer a wealth of new information about bonding morphology and, therefore, should be used in addition to conventional methods so that the maximum information can be obtained.
Incremental Lines in Root Cementum of Human Teeth: An Approach to their Ultrastructural Nature by Microscopy
Authors: Renz H. , Schaefer V. , Duschner H. , Radlanski R.J.
Published: January 2009

In ground sections of human teeth, root cementum shows under the light microscope as alternating, almost concentric, dark and light rings. In paleontology and forensic medicine, the number of these incremental lines or annulations is used to derive the age-at-death of the individual. To find the ultrastructural features underlying these cemental annulations, we used bright-field light microscopy (LM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and electron-dispersive x-radiation (EDX) in a scanning electron microscope (SEM). Annulations visible in ground sections of about 100-μm thickness were no longer visible in semi-thin sections (thickness, 1-2 μm) of the same specimen in the same area. The assumption that annulations could be caused by superimposing structures in the depth of field of the light microscope's objective lens was not verified by CLSM. Fiber bundles of higher density than the surrounding matrix in TEM micrographs could not be connected unambiguously with annulations in LM micrographs. After all, the ultrastructural nature of cemental annulations remains an open question.
The Dentin Disc Surface: A Plausible Model for Dentin Physiology and Dentin Sensitivity Evaluation
Authors: Gillam D.G. , Mordan N.J. , Newman H.N.
Published: January 2009

Dentin sensitivity (DS) is a painful clinical condition which may affect 8-35% of the population. Various treatment modalities have claimed success in relieving DS, although at present there does not appear to be a universally accepted desensitizing agent. Current opinion based on Brannstrom's Hydrodynamic Theory would suggest that following exposure of the dentin surface (through attrition, abrasion, or erosion), the presence of open dentinal tubules, patent to the pulp, may be a prerequisite for DS. The concept of tubule occlusion as a method of dentin desensitization, therefore, is a logical conclusion from the hydrodynamic theory. The fact that many of the agents used clinically to desensitize dentin are also effective in reducing dentin permeability tends to support the hydrodynamic theory. This paper reviews the in vitro evaluation of desensitizing agents, the techniques used to characterize their effects on the prepared dentin surface, and the ability of these agents to reduce permeability through tubule occlusion, and presents recent findings from ongoing research based on the Pashley Dentin Disc model. It can be concluded that the use of this model to determine surface characteristics, and reductions in dentin permeability through tubule narrowing or occlusion, provides a useful screening method for evaluating potential desensitizing agents. Interpreting changes observed in vitro is difficult, and extrapolation to the clinical situation must be tempered with caution.
Quantification of Formation and Remineralization of Artificial Enamel Lesions with a New Portable Fluorescence Device
Authors: Al-Khateeb S. , Ten Cate J.M. , Angmar-Månsson B. , De Josselin De Jong E. , Sundström G. , Exterkate R.A.M. , Oliveby A.
Published: January 2009

Quantitative laser fluorescence has been reported as a useful method for the non-destructive in vitro and in vivo diagnosis of early enamel caries. A portable system for intraoral use has been developed with a new light source and filter system replacing the laser light to facilitate clinical application. This new device was validated with microradiographic and chemical analyses for assessment of mineral changes in enamel during lesion formation and remineralization in vitro and compared with the laser light equipment. A significant correlation was found between fluorescence changes and mineral loss: r = 0.79 (laser system) and r = 0.84 (portable lamp system). The correlation between the two fluorescence methods was r = 0.93. The portable fluorescence device seemed to be a promising new tool for reproducible and sensitive assesment of the severity of incipient enamel lesions.
Visualization of Root Caries Lesions by Means of a Diazonium Dye
Authors: Wilkinson S.C. , Higham S.M. , Ingram G.S. , Edgar W.M.
Published: January 2009

A diazonium dye was used to visualize caries lesions in root tissue. Root caries lesions were created in vitro according to a variety of protocols based on methylcellulose gel (6% w/v) and/or lactic acid buffer (0.05 M, pH 4.5). Teeth containing lesions were soaked overnight in an alkaline solution of 2% (w/v) 2-naphthol or resorcinol, rinsed with distilled water, and immersed in a diazonium solution (prepared by titration of aniline with sodium nitrite in 1 M HCl at 5°C) for up to 10 min, prior to being thoroughly rinsed with distilled water. The area of the caries lesion on the anatomical surface was clearly marked with a red/orange color following 5 minutes' incubation in the diazonium solution. The diazonium complex formed with 2-naphthol was found to be more resistant to leaching during rinsing and sectioning than that formed with resorcinol. Microscopic examination of sections taken in the apical-coronal plane showed that the depth of area of the lesion was also marked by the red/orange coloration. Chemical changes in root mineral monitored during lesion formation showed some degree of correlation between lesion area and mineral dissolution. Visualization of coronal caries by this technique is currently under investigation. The visualization technique provides a simple means of determining the extent and severity of root caries lesions and may be a useful first step in their classification.
Detachment of Linking Film Bacteria From Enamel Surfaces by Oral Rinses and Penetration of Sodium Lauryl Sulphate Through an Artificial Oral Biofilm
Authors: Landa A.S. , Van Der Mei H.C. , Busscher H.J.
Published: January 2009

The biofilm mode of growth protects plaque micro-organisms against environmental attacks, such as from antimicrobials or detergents. Dental plaque is linked to enamel through the adhesion of initial colonizers. Once this link is disrupted, the entire plaque mass adhering to it detaches. Experiments in a parallel-plate flow chamber demonstrated that bacteria adhering to saliva-coated enamel could not be stimulated to detach by perfusion of the flow chamber with two traditional mouthrinses (Corsodyl® and Scope®), whereas perfusion with a prebrushing rinse (Plax®) or its detergent components stimulated detachment from saliva-coated enamel of a wide variety of bacterial strains. Following perfusion of the flow chamber with the mouthrinses, little additional detachment of adhering bacteria by the passage of a liquid-air interface occurred. After perfusion with the prebrushing rinse, however, significant numbers of still-adhering bacteria could be stimulated to detach by passage of a liquid-air interface, indicating that Plax® had weakened their adhesive bond. The ability of Plax® or its detergent components to detach plaque bacteria is not always obvious from in vivo experiments, and reports on its clinical efficacy are inconsistent. Likely, antimicrobials or detergents are unable to penetrate the plaque and reach the linking film bacteria, as demonstrated here by Fourier transform infrared spectroscopy.
The Relationship between Surface Free-Energy and Kinetics in the Mineralization and Demineralization of Dental Hard Tissue
Authors: Wu W. , Nancollas G.H.
Published: January 2009

The interfacial free-energy is an important factor in the regulation of mineralization and dissolution at the surfaces of dental hard tissues. However, few thermodynamic studies have been aimed at the elucidation of the interfacial terms. Contact angle measurements (sessile drop and thin layer wicking) and kinetic dissolution and growth techniques have been used to study the interfacial properties of root dentin (D), human enamel (E), and hydroxyapatite (HAP). The interfacial tensions between water (w) and each of these phases were calculated from contact angle data according to surface tension components theory. The values γwD = 4.5 x 10-3J m-2, γ wE = 8.8 x 10-3J m-2, and γw,HAP = 10.4 x 10-3J m-2 were of the same order of magnitude as those obtained from dissolution kinetic data (pH = 4.5): γwD = 1.4 x 10-3J m-2, γwE = 3.2 x 10-3J m-2, and γwHAP = 9.3 x 10-3J m-2. Kinetics studies of the crystallization of HAP on HAP, dentin, and enamel yielded the interfacial free-energy values, γwHAP = 17.1 x 10-3J m-2, 17.7 x 10-3J m-2, and 9.4 x 10-3J m-2, respectively, probably reflecting the interfacial energies of the deposited phases rather than those of the dental hard-tissue substrata. The lower interfacial tension values are consistent with the higher solubilities of these solid phases: logKso = -52.0, -55 - 57, and -58 - 59, for root dentin, enamel, and HAP, respectively, expressed as an equivalent HAP ionic product. The higher interfacial free-energy is also consistent with the slower mineralization of HAP on dentin and enamel surfaces.
Inhibition of MMP Synthesis by Doxycycline and Chemically Modified Tetracyclines (CMTs) in Human Endothelial Cells
Authors: Hanemaaijer R. , Visser H. , Koolwijk P. , Sorsa T. , Salo T. , Golub L.M. , Van Hinsbergh V.W.M.
Published: January 2009

Doxycycline is a commonly used broad-spectrum antibiotic. Recently, it has been shown that it also inhibits the activity of mammalian collagenases and gelatinases, an activity unrelated to its antimicrobial efficacy. In this study, we show that doxycycline not only inhibits MMP-8 and MMP-9 (gelatinase B) activity, but also the synthesis of MMPs in human endothelial cells. Doxycycline (50 μM) completely inhibited the phorbol-12-myristate-13-acetate (PMA)-mediated induction of MMP-8 and MMP-9, as measured by Western blotting and gelatin zymography, respectively. The inhibition was also observed at the mRNA level. No effect was observed on the expression of MMP-2 and of the MMP inhibitors TIMP-1 and TIMP-2. Chemically modified tetracyclines (CMTs) showed an inhibition similar to that of doxycycline, albeit less efficient. These observations demonstrate that endothelial cells display a specific regulation of MMPs, which may have implications for the pharmaceutical interaction in angiogenesis and angiogenesis-related diseases.
How do Tetracyclines Work?
Authors: Ryan M.E. , Ashley R.A.
Published: January 2009

This paper is a summary of a panel discussion by the following panelists: L. Golub, J. te Koppele, G. Nieman, M. Nelson, R. Ashley, T. Sorsa, and S. Simon. The panel discussed the mechanisms by which the tetracyclines and their non-antimicrobial counterparts may provide therapeutic efficacy in a variety of chronic and acute diseases.
Safety and Efficacy of Sub-Antimicrobial-Dose Doxycycline Therapy in Patients with Adult Periodontitis
Authors: Ciancio Sebastian , Ashley Robert
Published: January 2009

The objectives of the studies presented here were to assess the safety and efficacy of the adjunctive administration of sub-antimicrobial-dose doxycycline (SDD) for the treatment of adult periodontitis and to confirm the optimal dosing regimen. The studies summarized included four double-blind, placebo-controlled, randomized clinical trials, conducted over a period of 9 to 12 months. Analysis of efficacy data demonstrated that adjunctive SDD treatment resulted in: (1) increases in clinical attachment levels; (2) decreases in probing pocket depths; and (3) reductions in bleeding on probing in patients with adult periodontitis. There were no significant adverse events or unwanted long-term antimicrobial effects associated with orally administered SDD. The results of these clinical trials indicate that the adjunctive use of SDD 20 mg BID is an effective and well-tolerated regimen which can significantly improve several indices of periodontal health.
Root-Surface Caries in Rats and Humans: Inhibition by a Non-Antimicrobial Property of Tetracyclines
Authors: Ramamurthy N.S. , Schroeder K.L. , McNamara T.F. , Gwinnett A.J. , Evans R.T. , Bosko C. , Golub L.M.
Published: January 2009

The incidence of root caries has been found to increase as the population ages and as edentulism becomes less prevalent due to improved dental awareness and care, and as exposure of roots due to gingival recession has also increased in the elderly. The mechanism of root caries is thought to be mediated by both bacterial and mammalian proteases produced by plaque and the periodontal tissues, respectively. In the current study, a rat model of periodontal disease was used in which gnotobiotic rats were infected intra-orally with a periodontal pathogen ( P. gingivalis). Infecting the rats with P. gingivalis increased the collagenase activity in the gingival tissue in association with severe alveolar bone loss. Treating P. gingivalis-infected rats with doxycycline or CMT-1 prevented the destruction of the periodontium by MMPs, thus preventing exposure of roots to subgingival bacterial plaque and host tissue collagenases and the subsequent development of root caries. In addition, a low-dose doxycycline (LDD, 20 mg bid, non-antimicrobial dose) for 3 months was used in humans predisposed to increased root caries as the result of heavy use of smokeless (chewing) tobacco, causing gingival recession, subgingival plaque accumulation with Gram-negative bacteria, increased gingival crevicular fluid flow (GCF), and elevated GCF collagenase. Daily administration of LDD in smokeless tobacco patients reduced the GCF collagenase and prevented the further development of root caries.
Chemical and Biological Dynamics of Tetracyclines
Authors: Nelson M.L.
Published: January 2009

Key words: Tetracyclines, mechanism of action, biological activity.
The Potential Role of Doxycycline in the Treatment of Osteoarthritis of the Temporomandibular Joint
Authors: Israel H.A. , Ramamiurthy N.S. , Greenwald R. , Golub L.
Published: January 2009

Collagenase and gelatinase are matrix metalloproteinases (MMPs) which play an important role in tissue destruction in arthritic joints. Studies have demonstrated that tetracyclines can inhibit MMPs and prevent tissue destruction independent of their antimicrobial activity. The purpose of this pilot study is to assess the potential therapeutic role of Doxycycline in patients with advanced osteoarthritis of the temporomandibular joint (TMJ).

This ongoing investigation includes patients with a diagnosis of osteoarthritis of the TMJ based on clinical and diagnostic imaging findings, symptoms (localized TMJ pain, limited mobility, dysfunction) for a minimum of 36 months, and failure of previous non-surgical and surgical modalities to alleviate the symptoms. A synovial fluid sample is collected by a saline injection and aspiration technique, followed by diagnostic arthroscopy. Patients are placed on Doxycycline 50 mg BID for three months and then undergo repeat diagnostic arthroscopy and synovial fluid collection. The samples are stored at -80°C. Collagenase activity is determined by a combination of SDS-polyacrylamide gel electrophoresis and fluorography and calculated based on the percentage of collagen alpha chains that are degraded into alphaA breakdown products.

Three patients have completed the three-month course of Doxycycline thus far, and 5 joints with osteoarthritis have been analyzed. All patients were female (mean age = 35, mean duration of symptoms = 132 months) and had undergone previous bilateral arthroscopies. One patient had undergone unilateral arthroplasty. The mean collagenase activity showed 55% collagen lysis prior to Doxycycline treatment and 19% after three months of therapy. The mean

gelatinase activity was 28% prior to Doxycycline treatment and 7% after three months of therapy. The mean interincisal opening was 33 mm initially and 41 mm after three months of Doxycycline. Subjectively, two of the three patients reported significant improvement in their overall symptoms, which they had not experienced over the previous three years. One patient did not experience any change in symptoms, in spite of a marked reduction in collagenase activity from 86.4% to 9.6%.

Because of the very small numbers of patients enrolled in this pilot study so far, no statistically significant differences could be appreciated. However, the dramatic reduction in collagenase activity in these patients, with a long history of TMJ symptoms from osteoarthritis, suggests the potential promising role of Doxycycline in the management of osteoarthritis, and further investigation is warranted.
Effects of Tetracyclines on Bone Metabolism
Authors: Vernillo A.T. , Rifkin B.R.
Published: January 2009

The anti-resorptive properties of tetracyclines (TCs) and their non-antimicrobial, chemically modified analogues (CMTs) have enormous therapeutic potential in medicine and dentistry. Osseous destructive diseases associated with excessive mammalian collagenase (matrix metalloproteinase) activity and collagen breakdown include malignancy, arthritis, and periodontitis. However, apart from the significant antimatrix metalloproteinase effects of TCs, TCs/CMTs are also potent inhibitors of osteoclast function (i.e., anti-resorptive). Thus, TCs can affect several parameters of osteoclast function and consequently inhibit bone resorption by (1) altering intracellular calcium concentration and interacting with the putative calcium receptor; (2) decreasing ruffled border area; (3) diminishing acid production; (4) diminishing the secretion of lysosomal cysteine proteinases (cathepsins); (5) inducing cell retraction by affecting podosomes; (6) inhibiting osteoclast gelatinase activity; (7) selectively inhibiting osteoclast ontogeny or development; and (8) inducing apoptosis or programmed cell death of osteoclasts. TCs/CMTs, as anti-resorptive drugs, may act similarly to bisphosphonates and primarily affect osteoclast function.
Effect of an Inhibitor of Matrix Metalloproteinases on Spontaneous Osteoarthritis in Guinea Pigs
Authors: De Bri E. , Lei W. , Svensson O. , Chowdhury M. , Moak S.A. , Greenwald R.A.
Published: January 2009

Recently discovered chemically modified tetracyclines have been found to be effective inhibitors of matrix metalloproteinase (MMP)-mediated connective tissue destruction in a variety of pathologic processes, including rheumatoid arthritis and osteoarthritis (OA). Since the histologic techniques used in our laboratory have been validated in Hartley guinea pigs, which have a high incidence of OA-like changes in the proximal tibia, we have used two tetracyclines which have potent inhibitory capacity against variuos MMPs, doxycycline (Dox) and a compound known as chemically modified tetracyclines (CMT-7). These were given by mouth to a group of guinea pigs for 4 to 8 months, and we assessed the effect of the compound on morphologic and biochemical aspects of OA. We found that prophylactic CMT-7 given orally decreases OA changes in the knee joints both in vitro and in vivo in the guinea pig OA model. Cartilage fibrillation and destruction, in addition to subchondral bone sclerosis and cyst formation, were all decreased in the central compartment of the medial condyle, which is most affected by OA compared with controls. Also collagen, hyaluronan and proteoglycancontent in cartilage was higher in the CMT-7 treated group compared with controls. In contrast, OA changes were not decreased in the Dox group. Our results confirm that various tetracyclines have reduced the severity of OA in animal models, indicating the therapeutic potential of this class of compounds in the future.
Tetracycline-Based MMP Inhibitors Can Prevent Fibroblast-Mediated Collagen Gel Contraction In Vitro
Authors: Myers S.A. , Wolowacz R.G.
Published: January 2009

Collagen gels in vitro can be contracted by fibroblasts. The role of matrix metalloproteinases (MMPs) in the contraction of collagen lattices by human neonatal foreskin fibroblasts (HuFFs) was investigated in tissue culture media supplemented by various doses of known gelatinase inhibitors. Fluorescent assays with model gelatinase substrates and media conditioned by fibroblasts apparently confirmed the ability of chemically modified tetracyclines (CMTs) to act as inhibitors of MMP2, and zymography demonstrated that this was the major cell-derived MMP activity. There were no observable effects on the rate of contraction of attached FPCLs containing 6 x 104 HuFFs (passages 18-25) with either CMT-5 or CMT-2 at all concentrations tested (0-100 μg/mL). However, at greater than 20 μg/mL doxycycline and greater than 5 μg/mL CMT-3, FPCL contraction was completely abolished. Quantitative assessment of cell viability by means of the MTT assay in monolayer and qualitatively within the FPCLs with CalceinAM suggested that differences were not due to cytotoxic effects. Seeding FPCLs with lower-passage fibroblasts produced identical trends. These results may implicate the involvement of MMPs in the process of gel contraction, although tetracyclines have effects additional to their ability to inhibit MMPs directly.
Clinical Experience with One-Stage, Non-Submerged Dental Implants
Authors: Buser Daniel , Mericske-Stern Regina , Dula Karl , Lang Niklaus P.
Published: January 2009

This review article describes the scientific documentation of one-stage, non-submerged dental implants. In the past 25 years, numerous in vivo studies have demonstrated that non-submerged titanium implants achieve osseointegration as predictable as that of submerged titanium implants. This observation was confirmed in prospective clinical studies, mostly done with the ITI® Dental Implant System. ITI implants have been widely documented for up to 10 years of prospective follow-up at various centers. All studies showed success rates well above 90%. In summary, the non-submerged approach is a true alternative to the original healing modality with submerged titanium implants. The non-submerged approach offers several clinical advantages: (i) the avoidance of a second surgical procedure and less chair time per patient, resulting in overall reduced treatment cost; (ii) the lack of a microgap at the bone crest level, leading to less crestal bone during healing and resulting in a more favorable crown-to-implant length ratio; and (iii) a simplified prosthetic procedure, presenting an ideal basis for cemented implant restorations. Due to these significant clinical advantages, the non-submerged approach will become more important in implant dentistry in the near future, particularly in implant sites without esthetic priority.
Two-Stage Implant Systems
Authors: Fritz Michael E.
Published: January 2009

Since the advent of osseointegration approximately 20 years ago, there has been a great deal of scientific data developed on two-stage integrated implant systems. Although these implants were originally designed primarily for fixed prostheses in the mandibular arch, they have been used in partially dentate patients, in patients needing overdentures, and in single-tooth restorations. In addition, this implant system has been placed in extraction sites, in bone-grafted areas, and in maxillary sinus elevations. Often, the documentation of these procedures has lagged. In addition, most of the reports use survival criteria to describe results, often providing overly optimistic data. It can be said that the literature describes a true adhesion of the epithelium to the implant similar to adhesion to teeth, that two-stage implants appear to have direct contact somewhere between 50% and 70% of the implant surface, that the microbial flora of the two-stage implant system closely resembles that of the natural tooth, and that the microbiology of periodontitis appears to be closely related to peri-implantitis. In evaluations of the data from implant placement in all of the above-noted situations by means of meta-analysis, it appears that there is a strong case that two-stage dental implants are successful, usually showing a confidence interval of over 90%. It also appears that the mandibular implants are more successful than maxillary implants. Studies also show that overdenture therapy is valid, and that single-tooth implants and implants placed in partially dentate mouths have a success rate that is quite good, although not quite as high as in the fully edentulous dentition. It would also appear that the potential causes of failure in the two-stage dental implant systems are periimplantitis, placement of implants in poor-quality bone, and improper loading of implants. There are now data addressing modifications of the implant surface to alter the percentage of osseointegration. New types of reinforcements for dental implants and the use of growth factors to augment bone regeneration so that implants can be placed more easily are now being actively investigated.
Determination of the Success and Failure of Root-Form Osseointegrated Dental Implants
Authors: Tonetti Maurizio S.
Published: January 2009

Permucosal osseointegrated dental implants are a highly effective and predictable treatment modality for edentulism. This review discusses some controversial aspects of the definitions for success and failure of root-form dental implants. The discussion will focus on the underlying pathologies that, if untreated, may lead to loss of the implanted device. Few clinical syndromes are described based on human pathological material and clinical presentation. The theoretical chronological relationship between implant loss and the incidence of pathology of the soft- and hard-tissue seal around implants is also discussed. The review also examines the finding that implant failures are not randomly distributed in the treated populations and that implant loss clusters in specific high-risk groups and individuals. Known risk indicators, and possible risk factors, are discussed, taking into account the patient, the reconstruction, the implant, and implant site-specific factors. Particular emphasis is placed on the need for better determination of whether periodontal patients are at higher risk for implant failures as a consequence of their increased susceptibility to infectious, inflammatory-response-driven tissue breakdown.
Materials Characteristics of Uncoated/Ceramic-Coated Implant Materials
Authors: Lacefield William R.
Published: January 2009

In this paper, the biocompatibility of dental implant materials is discussed in the context of both the mechanical characteristics of the materials and the type of surface presented to the surrounding tissues. The proper functioning of the implant depends on whether it possesses the strength necessary to withstand loading within the expected range, with other properties such as elongation being of importance in some instances. A suitable modulus of elasticity may be of major importance in situations when optimum load transmission from the implant into the surrounding bone is key to the successful functioning of the device. Dental implants present a wide range of surfaces to the surrounding tissues based on surface composition, texture, charge energy, and cleanliness (sterility). Metallic implants are characterized by protective oxide layers, but ion release is still common with these materials, and is a function of passivation state, composition, and corrosion potential. An effective surface treatment for titanium appears to be passivation or anodization in a suitable solution prior to implantation. Inert ceramic surfaces exhibit minimal ion release, but are similar to metals in that they do not form a high energy bond to the surrounding bone. Some of the newly developed dental implant alloys such as titanium alloys, which contain zirconium and niobium, and high-strength ceramics such as zirconia may offer some advantages (such as lower modulus of elasticity) over the conventional materials. Calcium phosphate ceramic coatings are commonly used to convert metallic surfaces into a more bioactive state and typically cause faster bone apposition. There is a wide range of ceramic coatings containing calcium and phosphorus, with the primary difference in many of these materials being in the rate of ion release. Although their long-term success rate is unknown, the calcium phosphate surfaces seem to have a higher potential for attachment of osteoinductive agents than do uncoated titanium and other more inert implant materials.
Implant Surface Characteristics Modulate Differentiation Behavior of Cells in the Osteoblastic Lineage
Authors: Schwartz Z. , Lohmann C.H. , Oefinger J. , Bonewald L.F. , Dean D.D. , Boyan B.D.
Published: January 2009

This paper reviews the role of surface roughness in the osteogenic response to implant materials. Cells in the osteoblast lineage respond to roughness in cell-maturation-specific ways, exhibiting surface-dependent morphologies and growth characteristics. MG63 cells, a human osteoblast-like osteosarcoma cell line, respond to increasing surface roughness with decreased proliferation and increased osteoblastic differentiation. Alkaline phosphatase activity and osteocalcin production are increased. Local factor production is also affected; production of both TGF-β1 and PGE2 is increased. On rougher surfaces, MG63 cells exhibit enhanced responsiveness to 1,25-(OH)2D3. Prostaglandins mediate the effects of surface roughness, since indomethacin prevents the increased expression of differentiation markers in these cells.
Soft Tissue and Epithelial Models
Authors: Jansen J.A. , Den Braber E.T. , Walboomers X.F. , De Ruijter J.E.
Published: January 2009

The applicability of a biomaterial for the manufacturing of oral implants is determined by its physicochemical and geometric surface properties. Research, therefore, is concerned with the cellular reactions that occur when an implant material comes into contact with body tissues. For permucosal oral implants, this involves both the reaction of bone and gingival cells. In vitro cell culturing-including the use of various analytical techniques like light microscopy, scanning and transmission electron microscopy, confocal laser scanning microscopy, and digital image analysis-is a good tool whereby investigators can obtain more insight into the relevant components of implant-tissue adhesion. In the current overview, the role of cell models in oral implant research is discussed, specifically with reference to responses of epithelial cells and fibroblasts.
Bone Induction by Implants Coated with Cultured Osteogenic Bone Marrow Cells
Authors: DeBruijn Joost D. , Van Den Brink Ineke , Mendes Sandra , Dekker Robert , Bovell Yvonne P. , Van Blitterswijk Clemens A.
Published: January 2009

The availability of osteoinductive coatings on dental and orthopedic implants will result in an improved fixation of these devices. Those cases where implants are placed in poor-quality bone or where high failure rates are obtained are especially expected to gain from such coatings. This paper presents a novel, biological approach to obtain bioactive and osteoinductive coatings on bone-replacement implant materials. This so-called tissue engineering approach utilizes osteogenic bone marrow cells that are cultured on an implant material to form a bone-like tissue. The implant materials used herein included porous calcium phosphate scaffolds and metallic plates, the latter of which were coated with a biomimetic calcium phosphate coating to facilitate cellular attachment. Bone marrow cells were obtained from a variety of species, including humans, and were grown to facilitate cellular proliferation. The cells were subsequently seeded onto the implants and cultured for an additional week to facilitate osteogenic differentiation and extracellular matrix production. The resulting hybrid implants, encompassing the biomaterial carrier and cultured bone-like tissue, were subsequently implanted subcutaneously in nude mice for 4 weeks, followed by histological examination for de novo bone formation. The results revealed that newly formed bone was seen both in porous implants and on flat metallic surfaces. This bone tissue engineering approach, therefore, offers great potential to enhance bony healing around implants in a compromised bone bed.