bluuebunny/crossref_metadata_2025 huggingface dataset:
Full- vs. Partial-mouth Disinfection in the Treatment of Periodontal Infections: Short-term Clinical and Microbiological Observations
Authors: Quirynen M. , Bollen C.M.L. , Vandekerckhove B.N.A. , Dekeyser C. , Papaioannou W. , Eyssen H.
Published: January 2009

In a standard periodontal treatment strategy with consecutive root planings ( per quadrant at a one- to two-week interval), re-infection of a disinfected area might occur before completion of the treatment. This study examines, both clinically and microbiologically, whether a full-mouth disinfection within 24 hours significantly improves the outcome of periodontal treatment. Ten patients with advanced chronic periodontitis were randomly allocated to a test and a control group. The patients from the control group received scalings and root planings as well as oral hygiene instructions per quadrant at two-week intervals. Full-mouth disinfection in the test group was sought by the removal of all plaque and calculus (in two visits within 24 hours). In addition, at each of these visits, the tongue was brushed with a 1 % chlorhexidine gel for one min and the mouth rinsed with a 0.2% chlorhexidine solution for two min. Furthermore, subgingival chlorhexidine (1%) irrigation was performed in all pockets. The recolonization of the pockets was retarded by oral hygiene and 0.2% chlorhexidine rinses during two weeks. The clinical parameters were recorded, and plaque samples were taken from the right upper quadrant at baseline and after one and two months. The test group patients showed a significantly higher reduction in probing depth for deep pockets at both follow-up visits (p < 0.05). At the one-month visit, differential phase-contrast microscopy revealed significantly lower proportions of spirochetes and motile rods in the test group (p = 0.01). Culturing showed that the test group harbored significantly fewer pathogenic organisms at one month (p = 0.005). At two months, the same sites harbored singificantly more "beneficial" bacteria (p = 0.02). Moreover, all sites of the test group initially harboring P. gingivalis (6/10) became negative after treatment. These findings suggest that it is possible to achieve a significant improvement of the treatment outcome (both microbiologically and clinically) with a one-stage full-mouth disinfection.
Evidence for the Role of Nitric Oxide in the Circulation of the Dental Pulp
Authors: Lohinai Z. , Balla I. , Marczis J. , Vass Z. , Kovach A.G.B.
Published: January 2009

Many authors have studied the hemodynamics of the dental pulp; however, there are scarcely any data regarding the involvement of the L-arginine/nitric oxide pathway in the regulatory mechanism. Thus, we have examined the physiological effects of (1) NG-nitro-L-arginine as an inhibitor of nitric oxide synthesis and (2) the nitric oxide donor 3-morpholinosydnonimine on blood flow and vascular resistance in the canines of anesthetized cats to study the potential involvement of nitric oxide in the regulation of dental vascular homeostasis. Mean arterial blood pressure, heart rate, blood gases, pH, cardiac output, and tissue blood flow were determined prior to and 15 min after i.v. administration of either NG-nitro-L-arginine (30 mg/kg, n = 9) or 3-morpholinosydnonimine (1 mg/kg, n = 7). Blood flow was measured by radioactive-labeled microspheres. There were no significant differences in baseline parameters between the two groups of cats. The dental pulp blood flow decreased to 53 ± 13% (p < 0.01) of the control level after NG-nitro-L-arginine administration, while it decreased only slightly (to 82 ± 12%) after 3-morpholinosydnonimine administration. The dental pulp's vascular resistance increased to 367 ± 69% (p < 0.01) of the control level after NG-nitro-L-arginine, while it decreased to 73 ± 10% (p < 0.05) of control after 3-morpholinosydnonimine. We found that the L-arginine/nitric oxide pathway plays an important role in the regulation of pulpal blood circulation. A nitric-oxide-dependent basal vasodilator tone exists in the dental pulp; furthermore, since the dental pulp circulation is sensitive to exogenous nitric oxide, the stimulated release of endogenous nitric oxide may also be involved in the control of the dental pulp vascular tone.
A Follow-up Study of Radiographic Findings in the Mandibular Condyles of Orthodontically Treated Patients and Associations with TMD
Authors: Peltola J.S. , Könönen M. , Nyström M.
Published: January 2009

Our earlier studies have shown that some radiographic structural findings in the mandibular condyles are more common in orthodontically treated populations than in normal populations. To test the hypothesis that these findings are stable, we studied condylar findings in panoramic radiographs longitudinally in 39 subjects and in 39 sex- and age-matched controls. The subjects had condylar findings at the end of orthodontic treatment at about 15 years of age; no such findings were seen in the controls. The subjects and controls were re-examined radiographically about 12 years after the posttreatment radiographic examination.

We also tested the hypothesis that radiographic condylar findings are associated with temporomandibular disorders (TMD). No statistically significant differences were found between subjects and controls in terms of reported subjective TMD symptoms. Clinically, the subjects had temporomandibular joint (TMJ) crepitation significantly more frequently (27%) than controls (8%) (p < 0.05). Crepitation correlated with some reported symptoms and clinical signs, suggesting that osteoarthrosis might have been an important etiological factor for TMD in the present subjects.

At the follow-up examination, radiographic condylar findings were seen in 25 subjects and in four controls (p < 0.001). The condylar findings varied greatly between the time of orthodontic treatment and follow-up in the subjects. The findings had become more severe in 49% of the subjects, more often in females than in males (p < 0.05), whereas in 28% of the subjects the condylar findings had disappeared. Although the radiographic findings after orthodontic treatment fluctuated with age, in most adolescents with changes in their condyles, these findings remained constant or became more severe. It should be emphasized, however, that although there were certain associations between radiographic findings and TMD, the subjective symptoms and clinical signs seemed to cause the subjects no or only minor problems.
Urinary Catecholamine Levels in Children with and without Dental Caries
Authors: Vanderas A.P. , Manetas C. , Papagiannoulis L.
Published: January 2009

Urinary catecholamines have been used to measure emotionally stressful states which may affect the development of dental caries. This study investigates the hypothesis that children with and without dental caries do not differ significantly in the mean values of urinary catecholamines such as epinephrine, norepinephrine, and dopamine. As a test of this hypothesis, 314 children, males and females, aged from 6 to 8 years, were included in the study. Dental caries were recorded clinically and radiographically, and oral hygiene was evaluated by the recording of dental plaque. A 24-hour urine sample was collected for each subject, and a representative sample (25 mL) was analyzed by the HPLC technique to assay the catecholamine content. Socio-economic factors such as parental age, education, and profession were recorded by a questionnaire distributed to the parents. Of the examined children, 38 (14 males and 24 females) were free of dental caries and constituted the case group. Two control groups, A and B, of 38 children each (14 males and 24 females) with dental caries were matched by age and gender. Differences in the quantitative and qualitative data were tested by the paired t test and the X2-test, respectively, while a regression analysis was applied to measure the effects of norepinephrine and dopamine on epinephrine. The logistic multiple-regression analysis was used to test, in the entire population, the impact of catecholamines and other related factors on the probability of subjects' developing dental caries. The 95% probability was used. The results showed statistically significant differences in epinephrine values between the case group and control groups A and B. The data suggest, therefore, that children with emotionally stressful states have higher probability of developing dental caries.
Duration of Dentinal Tubule Occlusion Formed by Calcium Phosphate Precipitation Method: In vitro Evaluation Using Synthetic Saliva
Authors: Suge T. , Ishikawa K. , Kawasaki A. , Yoshiyama M. , Asaoka K. , Ebisu S.
Published: January 2009

The use of a calcium phosphate precipitation method occluded dentin tubules with apatitic mineral and, thus, showed good potential for the treatment of dentin hypersensitivity. The aim of this study was to elucidate the occluding behavior of the precipitate in the oral environment. Dentin disks treated by the calcium phosphate precipitation method, and disks treated with potassium oxalate, NaF, and SrCl2 solutions, were immersed in synthetic saliva, which was regularly replenished so that ionic concentration would be maintained. Treatment of dentin disks by the calcium phosphate precipitation method immediately reduced dentin permeability to 6 ± 8%. When the disk was immersed in synthetic saliva, dentin permeability remained low, even seven days after immersion. Scanning electron microscopic observation showed no distinct boundary line between the precipitate and intertubular dentin; this indicated further mineralization on the precipitate. Potassium oxalate treatment also reduced the dentin permeability to 8 ± 3%. However, the dentin permeability gradually but steadily increased with immersion time, reaching 39 ± 14% at seven days. To elucidate the mechanism underlying dentin permeability changes in synthetic saliva, we immersed the precipitates, i.e., apatitic mineral and calcium oxalate, in a fixed volume of synthetic saliva. When calcium oxalate was immersed in synthetic saliva, there was a large concentration of oxalate ions, indicating dissolution of the calcium oxalate; this phenomenon was ascribed to the increase in dentin permeability. In contrast, calcium and phosphate ions decreased when apatitic powder, the precipitate formed by the calcium phosphate precipitation method, was immersed in synthetic saliva. The decrease in the calcium and phosphate ions in synthetic saliva indicated further precipitation of calcium phosphate on the apatitic precipitate. We concluded, therefore, that the calcium phosphate precipitation method would have a continuous effect in reducing dentin permeability in the oral environment.
Concise Review: Statistical Issues in Periodontal Research
Authors: DeRouen T.A. , Hujoel P.P. , Mancl L.A.
Published: January 2009

In the past 10 to 12 years, there have been several statistical issues identified in periodontal research which require and have generated non-standard or new statistical approaches. The purpose of this paper is to give an overview of these issues and approaches. Three general categories of issues are described: (i) statistical methods for detecting when disease progression occurs, and biological theories and corresponding statistical models which attempt to describe how the disease progresses; (ii) design issues in studies of therapeutic efficacy; and (iii) analytic issues arising from periodontal data analysis.
Jaw Pain Prevalence Among French-speaking Canadians in Quebec and Related Symptoms of Temporomandibular Disorders
Authors: Goulet J.-P. , Lavigne G.J. , Lund J.P.
Published: January 2009

The purpose of this study was to assess the prevalence and pattern of self-reported TMD jaw pain in a randomized stratified sample from the general population living in the Province of Quebec, Canada. Through a telephone survey, standardized questions were asked to 897 French-speaking respondents, aged 18 years old and over, regarding frequency, severity, daily pattern of jaw pain, presence of difficulty in opening, joint clicking, and sleeping problems. All prevalence estimates were adjusted to the sociodemographic distribution of the non-institutionalized population. The results indicate that TMD jaw pain is self-reported by 30% of the general population; however, the prevalence of cases reporting frequent episodes (quite often or very often) is estimated at 7%, with more than two-thirds (69%) of the respondents in this subgroup experiencing moderate to severe pain. The prevalence rates of frequent difficulty in opening and joint clicking were estimated at 9% and 4%, respectively. Approximately one in four subjects with frequent episodes of jaw pain also reported frequent joint clicking or difficulty in opening, and a strong association (Gamma coefficient > 0.6) was found among all three TMD symptoms. Our data suggest that the prevalence of clinically significant TMDrelated jaw pain (frequent jaw pain of moderate to severe intensity) is approximately 5% in the general population of the Province of Quebec. In the nine months preceding the survey, about 2% of the total population sought treatment for a TMD symptom.
High-resolution and Analytical Electron Microscopic Studies of New Crystals Induced by a Bioactive Ceramic (Diopside)
Authors: Miake Y. , Yanagisawa T. , Yajima Y. , Noma H. , Yasui N. , Nonami T.
Published: January 2009

Diopside has been developed for use in dental root implants and for the filling of bone defects. In previous studies, diopside developed hydroxyapatite (HA) on its surface and achieved a direct bond with bone. The purpose of this study was to investigate the mechanism of crystal formation on the diopside surface. We ultrastructurally evaluated the interface between new diopside-induced crystals and diopside. Specimens were prepared in three experiments: (1) Granular diopside was immersed in simulated body fluid (SBF); (2) granular diopside was implanted into a cavity in rabbit bone; and (3) a diopside dental root implant was implanted into a Japanese monkey. The specimens were examined by contact microradiography, high-resolution transmission electron microscopy, and analytical electron microscopy. In the experiment with SBF, many platelet-like crystals formed in the diopside surface layer. The lattice of diopside and that of the new crystals were very close, but no clear continuation of the lattice was observed. In the experiments which used a rabbit and a monkey, contact microradiography showed close contact between bone and diopside. High-resolution transmission electron microscopy revealed crystal growth from the diopside surface layer, and continuity between the diopside lattice and that of the new crystals. The morphological characteristics of the new crystals and the results of these analyses suggest that these new crystals are HA. With regard to the mechanism by which crystals are formed on the diopside surface layer, it is possible that epitaxial crystal growth could originate as a nucleus on the surface. In this case, epitaxial crystal growth of primarily octacalcium phosphate (OCP) may have occurred, and this may have changed to HA by a phase transition. However, epitaxial growth of OCP on the diopside surface is still highly speculative, since there is no direct supporting evidence.
Reversible Structural Changes of Octacalcium Phosphate and Labile Acid Phosphate
Authors: Suzuki O. , Yagishita H. , Amano T. , Aoba T.
Published: January 2009

Acid phosphate is one of the major impurities incorporated into bioapatites, and its quantity and environment in forming mineral have been used as diagnostic probes to pursue acidic precursor(s). Currently, little is known about the structural feature of non-stoichiometric octacalcium phosphate (OCP), which has been advocated to be, most plausibly, mineral salt initially formed during amelogenesis. In the present report, we attempt to define the state of acid phosphate in OCP crystals which were Ca-deficient and contained 40% total phosphate as acid phosphate. We assessed fractions of acid phosphate in discrete environments by extracting the crystals in either deionized water, 10 mmol/L NaOH solution (initial pH 11), or 150 mmol/L Tris buffer at pH 7.4. Solid samples before and after the treatments were examined by chemical analyses and x-ray diffraction. The results indicated that successive extractions with use of the alkaline solution brought about a reversible change (not hydrolysis) in the interior structure of OCP, which accompanied a marked decrease in acid phosphate. A substantial part of the lost acid phosphate was restored during subsequent treatments at neutral pH, and, intriguingly, this restoration accompanied a re-ordering of OCP structure. The data suggested that the acid phosphate in OCP is separated into three pools: (a) a stable pool corresponding to roughly 50 to 60% of the total acid phosphate, (b) a reversibly exchangeable pool corresponding to 25 to 30% of the acid phosphate which may exist either in the water layer or on crystal surfaces, and (c) an unstable (or irreversibly lost) pool corresponding to 15 to 20% of the acid phosphate, a part of which might be explained by the presence of excess hydrogen in OCP. The present work supports the concept that protons and, to a lesser magnitude, phosphate species can diffuse into and out of the OCP lattice prior to initiation of its hydrolytic transition into apatite.
Mineral Element Analysis of Carious and Sound Rat Dentin by Electron Probe Microanalyzer Combined with Back-scattered Electron Image
Authors: Tjäderhane L. , Hietala E.-L. , Larmas M.
Published: January 2009

We recently demonstrated the advantages of back-scattered electron images (COMPO) in the visualization of dentinal caries, and the relationship of the change in the dentin fluorescence pattern in caries lesions. However, the exact nature of these changes is not known. In this paper, the nature of the changes in the areas with reduced mineral content in COMPO images was investigated. We examined the relation of changes in mineral elements and the appearance of soft carious and sound dentin in COMPO images using a scanning electron microscope (SEM) equipped with an electron probe microanalyzer (EPMA). Rat molars with small dentinal caries lesions just under the DEJ were chosen for the study. The Ca, P, Na, Mg, Zn, F, and total contents were determined by EPMA from five different dentin sites, and the Ca/P and Mg/Ca ratios were calculated. Generally, the lowest contents were found in caries lesions and highest in mantle dentin, with the exceptions of Mg and Zn. The Ca/P ratio was lowest in mantle dentin and highest in carious dentin. The results confirm that the change in fluorescence in the dentinal caries lesion is correlated with the very initial changes in mineral content, and that EPMA used in combination with COMPO images is a useful tool for determining small changes in mineral elements in the carious and adjacent areas of dentin.
LPS Responsiveness in Periodontal Ligament Cells is Regulated by Tumor Necrosis Factor-α
Authors: Quintero J.C. , Piesco N.P. , Langkamp H.H. , Bowen L. , Agarwal S.
Published: January 2009

Gingival fibroblasts function as accessory immune cells and are capable of synthesizing cytokines in response to lipopolysaccharides (LPS) from Gram-negative microbes. Recently, we have isolated, cloned, and characterized two cell lines which exhibit characteristics of periodontal ligament (PDL) cells. In this report, we demonstrate that PDL cells showing osteoblast-like phenotype are not LPSresponsive cells. However, treatment of PDL cells with tumor necrosis factor-α (TNF-a) inhibits the expression of their osteoblast-like characteristics. As a consequence of this TNF-a-induced phenotypic change, PDL cells become LPSresponsive, i.e., synthesize several pro-inflammatory cytokines in response to LPS. These phenotypic changes occur at concentrations of TNF-a that are frequently observed in tissue exudates during periodontal inflammation, suggesting a physiological significance for these in vitro observations. It is of interest that TNF-a-induced phenotypic changes in PDL cells are transient, since removal of rhTNF-a from the supernatants of PDL cell cultures results in re-acquisition of the osteoblast-like characteristics and lack of LPS responsiveness of PDL cells. These results suggest that TNF-a, by regulating the PDL cell functions, may allow these cells to participate in the disease process as accessory immune cells at the expense of their structural properties.
Expression of Transglutaminase C during the Prenatal Development of Human Submandibular Glands
Authors: Lee S.K. , Chi J.G. , Jeon Y.J. , Park S.C. , Mori M. , Chung S.I.
Published: January 2009

The involvement of transglutaminase C (TGase C) in morphogenesis and cytodifferentiation during glandular tubule formation was addressed by immunolocalization of the protein at different stages of prenatal human submandibular gland development in 100 fetuses and 20 adult salivary glands. Immunocytochemical detection was carried out using a monospecific antibody to TGase C. The results showed TGase C reactivity in both acini and ducts early in development (from 10 to 14 weeks), followed by a marked increase in ductal activity and a decline in acinar activity up to 32 weeks. During the peak of reactivity at 25 to 32 weeks, staining was concentrated in the apical ends of the columnar cells. In the adult, staining was weakly and diffusely distributed in the striated and excretory ducts. Western blot analysis of the cellular extracts of pooled samples from various stages of salivary gland development showed a single strong band at 76 kDa early in development. This band became weaker after 32 weeks of prenatal development and in the adult. These findings of transient high expression of TGase C, which coincide with the development of tubulo-alveolar structure, suggest that TGase C may play a role in morphogenesis in human salivary gland development.
Functional Comparison of Native and Recombinant Human Salivary Histatin 1
Authors: Driscoll J. , Zuo Y. , Xu T. , Choi J.R. , Troxler R.F. , Oppenheim EG
Published: January 2009

Histatin 1 is a histidine-rich phosphoprotein present in human parotid saliva that possesses candidacidal activity and functions in mineralization by adsorbing to hydroxyapatite. The objective of the present study was to develop a system for recombinant production of histatin 1 and to examine the role of phosphorylation in the functional activities of this molecule. Native histatin 1 (containing a phosphoserine at residue 2) was purified from parotid saliva, whereas a bacterial expression system was used to produce a recombinant form of histatin 1 (re-Hstl) that lacked phosphorylated serine. Histatin 1 cDNA was inserted into the vector pGEX-3X, which expresses foreign genes as soluble fusion proteins attached to the carboxyl-terminus of glutathione S-transferase (GST). The GST/re-Hstl fusion protein was isolated from cell lysates by affinity chromatography on glutathione (GSH)-Sepharose and digested with cyanogen bromide to separate re-Hstl from the GST fusion partner. The digest was subjected to reversed-phase high-performance liquid chromatography on a C18 column, and re-Hstl was eluted as a well-defined peak. The yield of re-Hstl was 4 mg/L of bacterial culture. Amino-terminal sequencing and amino acid analysis confirmed the final product as re-Hstl. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that native histatin 1 and re-Hstl had the same apparent molecular weights, while cationic PAGE showed that re-Hstl was more basic. Phosphate analysis indicated 1 mol phosphate/mol of native histatin 1, while re-Hstl lacked any detectable phosphate. Re-Hstl demonstrated candidacidal activity comparable to that of native histatin 1, but displayed substantially lower binding to hydroxyapatite. These results show that phosphorylation of histatin 1 at residue 2 contributes significantly to its ability to bind to hydroxyapatite.
The Re-innervation of the Tongue and Salivary Glands after Lingual Nerve Repair by Stretch, Sural Nerve Graft or Frozen Muscle Graft
Authors: Smith K.G. , Robinson P.P.
Published: January 2009

The lingual nerve is sometimes injured during the surgical removal of impacted third molar teeth and may require repair. Removal of the damaged section of nerve prior to repair leaves a gap between the nerve ends, and we have investigated methods of closing the gap. The characteristics of regenerated fibers in the chorda tympani have been recorded in cats 24 weeks after the removal of a segment of lingual nerve and repair of the defect by three methods. The nerve gap was closed either by stretching the nerve ends together and repairing under tension, or by the insertion of a sural nerve graft or freeze-thawed muscle graft. The properties of gustatory, thermosensitive, and mechanosensitive units and the return of the vasomotor and secretomotor responses were investigated by electrophysiological techniques and the data from each of the repair groups compared with those obtained from a series of normal control animals. After each method of repair, the integrated whole-nerve activity recorded from the chorda tympani during gustatory or thermal stimulation of the tongue was reduced when compared with controls, but there was little significant difference between the repair groups. Recordings made from single units in the chorda tympani revealed that conduction velocities were faster after stretch repair than after sural nerve graft or frozen muscle graft. In addition, 48% of the units had developed into principally gustatory units after stretch repair, indicating a better level of recovery than in the graft groups, which contained 33% and 32%, respectively. The secretomotor responses were also significantly greater after stretch repair than in either of the graft groups or the controls, but there was no difference in the vasomotor responses. These results reveal that repair of a short gap in the lingual nerve by stretching the ends together is followed by better overall recovery than after grafting, but where a graft is used, a similar level of recovery results from use of a frozen muscle graft or a sural nerve graft.
Development and Histologic Characterization of an Animal Model of Antigen-induced Arthritis of the Juvenile Rabbit Temporomandibular Joint
Authors: Kapila S. , Lee C. , Tavakkoli Jou M.R. , Miller A.J. , Richards D.W.
Published: January 2009

Children with juvenile rheumatoid arthritis or juvenile chronic arthritis often exhibit temporomandibular joint (TMJ) involvement accompanied by pain, dysfunction, and growth abnormalities. Despite the severe functional and developmental consequences of this disease, its pathogenesis remains poorly understood, but important insights may be provided by a suitable animal model of this disease. The purpose of this study was to develop and histologically characterize a juvenile animal model of antigen-induced arthritis of the TMJ. Arthritis was induced with an intra-articular administration of ovalbumin in previously sensitized 10-week-old male New Zealand white rabbits. Sham-treated and untreated rabbits were used as controls. The TMJs were retrieved en bloc at 5, 10, 15, 35, and 55 days post-challenge for histology and matrix histochemistry. Antigen-treated joints demonstrated severe arthritis, including mononuclear cell infiltration, synovial lining and villous hyperplasia, and pannus formation, as early as 5 days after challenge; the arthritis was maintained up to 55 days post-challenge. A decrease in the area of the TMJ disc that stained positively for glycosaminoglycans was observed throughout the experimental period. Loss of collagen staining was primarily localized to sites at the junction of the synovium with bone and fibrocartilage. The histopathologic features of this model of antigen-induced arthritis of the juvenile rabbit TMJ are similar to those observed previously in adult animal models of experimental arthritis and in human rheumatoid arthritis. This animal model will be useful for understanding the pathogenesis of juvenile rheumatoid arthritis of the TMJ, and for exploring the mechanisms for aberrant craniofacial growth.
Alternative Splicing of Amelogenin mRNA from Rat Incisor Ameloblasts
Authors: Li R. , Li W. , DenBesten P.K.
Published: January 2009

Amelogenin proteins are a major component of the developing enamel matrix, and are likely to have a key role in the control of enamel biomineralization. The heterogeneity of amelogenin is in part due to alternative splicing of the amelogenin RNA transcripts. Several patterns of alternative splicing have been described in mouse, bovine, porcine, and human enamel, with all alternatively spliced products having homologous 5' and 3' sequences within the coding regions. In these studies, we have used anchored PCR to identify alternatively spliced amelogenin cDNA sequences in the rat. We found amelogenin cDNAs that could be divided into two groups based on their 3' sequence. Group 1 cDNAs had a novel terminal sequence that has not been previously identified, while group 2 cDNAs were similar to those previously identified in other animal species. We identified a sequence, identical to the novel 3' amelogenin cDNA sequence, in rat genomic DNA downstream from the previously identified exon 7. The putative amelogenin proteins predicted for the two groups differed in their predicted isoelectric points, with the novel group 1 proteins having a more basic isoelectric poi
HeNe-Laser Light Scattering by Human Dental Enamel
Authors: Zijp J.R. , ten Bosch J.J. , Groenhuis R.A.J.
Published: January 2009

Knowledge of the optical properties of tooth enamel and an understanding of the origin of these properties are necessary for the development of new optical methods for caries diagnosis and the measurement of tooth color. We measured the scattering intensity functions for HeNe-laser light of 80- to 100-pm-thick human dental enamel slabs. The asymmetry factors were calculated to be g = 0.68 at 633 nm. By measuring the collimated beam attenuation, we determined the scattering coefficient to be s = 6.6 mm-1. From Fraunhofer diffraction patterns, obtained from transmission of the laser beam, we calculated the periodicity of the prismatic structure as 5.4 μm. We present a model containing scattering by crystals and by prisms. It shows that the prisms are the most important scatterers but that the crystals are responsible for the back-scattering.
Shear Strength of Composite Bonded to Er:YAG Laser-prepared Dentin
Authors: Visuri S.R. , Gilbert J.L. , Wright D.D. , Wigdor H.A. , Walsh J.T.
Published: January 2009

An Er:YAG laser coupled with a cooling stream of water effectively removes dental hard tissues. However, before such a system can be deemed clinically viable, some safety and efficacy issues must be addressed. We compared the bonding of composite to dentin following the preparation of the dentinal surface with either an Er:YAG laser (A = 2.94 pm) or a standard dental bur and with and without a subsequent acid-etching treatment. The crowns of extracted human molars were removed, revealing the underlying dentin. We removed an additional thickness of material with either a dental handpiece or an Er:YAG laser (350 mj/pulse at 6 Hz) by raster-scanning the samples under a fixed handpiece or laser. Comparable surface roughnesses were obtained. Several samples from each group received an acid-conditioning treatment. A cylinder of composite was bonded onto the prepared surfaces. The dentin-composite bond was then shear-stressed to failure on a universal testing apparatus. The results indicate that laser-irradiated samples had improved bond strengths compared with acid-etched and handpiece controls. SEM photographs of the surfaces show exposed tubules following the laser treatment; tubules could also be exposed with acid etching. We conclude that Er:YAG laser preparation of dentin leaves a suitable surface for strong bonding of an applied composite material.
Relationships Between Clinician Variability and Radiographic Guidelines
Authors: Flack V.F. , Atchison K.A. , Hewlett E.R. , White S.C.
Published: January 2009

This study evaluated the replicability of clinical measurements under careful calibration of multiple dentists and how the replicability can relate to their use as selection criteria in guidelines for prescribing dental radiographs. For 48 consenting patients, three dentists clinically examined each patient and recorded the presence of all clinical findings using standardized selection criteria. The examinations were performed independently of each other, but with periodic conferences of the dentists to clarify general measurement criteria. The degree of agreement among the dentists is described by the interrater agreement kappa for several standard clinical indications such as rating of caries, periodontal disease, and tooth mobility. Almost perfect agreement was obtained for tooth status, restoration size, and restoration material. Moderate agreement resulted for measures of caries, defective restoration presence, and gingival recession presence. Only fair agreement was obtained for other periodontal disease measures. The relationship between extent of agreement and guidelines' results was examined for the FDA Guidelines. The differences among the dentists' clinical measurements resulted in considerable differences among the radiographs that were selected by the FDA Guidelines' criteria. Even so, the missed disease rates for 490 patients in a larger study of the FDA Guidelines' efficacy were very low and did not vary greatly among the three dentists. We conclude that guidelines' criteria can be quite robust to variation from dentists' clinical measurement differences, as seen from the FDA Guidelines applied under the idealized setting where the dentists are periodically recalibrated through group discussions of the clinical measurements' definitions and interpretations.
Serum Cotinine Levels, Smoking, and Periodontal Attachment Loss
Authors: Gonzalez Y.M. , De Nardin A. , Grossi S.G. , Machtei E.E. , Genco R.J. , De Nardin E.
Published: January 2009

Cigarette smoking and tobacco use have been the subjects of numerous studies for many years. Smoking has also been associated with periodontal disease. However, no relationship between a reliable biochemical marker and increased severity of the periodontal condition has yet been described. It was thus the aim of this study to apply the measurement of cotinine, the major metabolite of nicotine, as a quantitative method to assess levels of smoking, and to correlate serum levels of cotinine with severity of periodontal disease. The degree of association between smoking and periodontal attachment loss was investigated in a study including 79 patients 25 to 64 years old suffering from periodontitis. Patients were examined and the following parameters recorded: Gingival Assessment (GA), Probing Pocket Depth (PPD), Clinical Attachment Level (CAL), and Bone Crest Height (BCH). In addition, self-reported histories of tobacco use as well as blood samples for quantitative analysis of serum levels of cotinine were taken. The serum samples were analyzed for cotinine content by means of a competitive-inhibition ELISA technique. The differences in mean cotinine levels were statistically significant (p = 0.0001) between smokers and non-smokers, showing no overlap between the groups. Severity of periodontal attachment loss was positively correlated with serum levels of cotinine for both measures of periodontal disease (CAL p = 0.005; BCH p = 0.008). Results from the present study indicate that serum cotinine levels used as a biochemical marker of smoking status are correlated with severity of periodontal attachment loss.
The Inhibiting Effect of Aqueous Azadirachta indica (Neem) Extract Upon Bacterial Properties Influencing in vitro Plaque Formation
Authors: Wolinsky L.E. , Mania S. , Nachnani S. , Ling S.
Published: January 2009

The purpose of this investigation was to examine the inhibitory effects of aqueous extracts derived from the bark-containing sticks (Neem stick) of Azadirachta indica upon bacterial aggregation, growth, adhesion to hydroxyapatite, and production of insoluble glucan, which may affect in vitro plaque formation. Neem stick extracts were screened for minimal bacterial growth inhibition (MIC) against a panel of streptococci by means of a broth dilution assay. Initial bacterial attachment was quantified by the measurement of the adhesion of 3H-labeled Streptococcus sanguis to saliva-conditioned synthetic hydroxyapatite. The effect of the Neem stick extract upon insoluble glucan synthesis was measured by the uptake of radiolabeled glucose from 14C-sucrose. Aggregating activity of the Neem stick extracts upon a panel of streptococci was also examined. No inhibition of bacterial growth was observed among the streptococcal strains tested in the presence of ≤ 320 pg/mL of the Neem stick extract. The pre-treatment of S. sanguis with the Neem stick extract or the gallotannin-enriched extract from Melaphis chinensis at 250 ug/mL resulted in a significant inhibition of the bacterial adhesion to saliva-conditioned hydroxyapatite. Pre-treatment of saliva-conditioned hydroxyapatite with the Neem stick or gallotannin-rich extract prior to exposure to bacteria yielded significant reductions in bacterial adhesion. The Neem stick extract and the gallotannin-enriched extract from Melaphis chinensis inhibited insoluble glucan synthesis. Incubation of oral streptococci with the Neem stick extract resulted in a microscopically observable bacterial aggregation. These data suggest that Neem stick extract can reduce the ability of some streptococci to colonize tooth surfaces.
Developing Ethical Standards for Responsible Research: Why? Form? Functions? Process? Outcomes?
Authors: Frankel M.S.
Published: January 2009

Any profession that is considering the development of ethical standards should give serious attention to the intended purposes of such standards, what form they should take, what functions they will serve, how the process for developing them should be organized, what outcomes are sought, and what values are central to the mission and performance of the profession. The profession serves as a normative reference group for individual practitioners and through ethical standards clarifies, for both its members and outsiders, the norms that ought to govern professional behavior. Such standards may be aspirational, educational, or regulatory, and may perform many functions, nine of which are discussed. The process of developing standards is assessed because of the role it plays in gaining consensus on professional values and ethical norms. Finally, several outcomes likely to increase the value and utility of ethical standards are identified. Key words: ethical standards, accountability, professional association.
Process and Procedures for Dealing with Misconduct: A Necessity or a Nightmare?
Authors: Bersoff D.N.
Published: January 2009

After a scientific and professional association has developed a code of ethics, it must develop a set of procedures to investigate, adjudicate, and enforce the code's provisions. The author, who is a scientist and an attorney, describes and discusses the fundamental legal principles that must be adhered to so that complaints against members can be adjudicated fairly, objectively, and with little legal risk to the association. The paper defines the concept of due process as it applies to private, non-profit associations and provides an example of how one professional and scientific association actually goes about adjudicating claims of misconduct against its members. It also informs associations about the liability risks that may confront them when they enforce a code of ethics, offers suggestions of how to manage those risks successfully, and concludes by cataloguing some of the financial burdens enforcement entails.
Correlative Transmission Electron Microscopy Examination of Nondemineralized and Demineralized Resin-Dentin Interfaces Formed by Two Dentin Adhesive Systems
Authors: Van Meerbeek B. , Conn L.J. , Duke E.S. , Eick J.D. , Robinson S.J. , Guerrero D.
Published: January 2009

The resin-dentin interface formed by two dentin adhesives, Optibond (OPTI, Kerr) and Scotchbond MultiPurpose (SBMP, 3M), was ultramorphologically examined by transmission electron microscopy (TEM). Ultrastructural information from nondemineralized and demineralized sections was correlated. It was hypothesized that the different chemical formulations of the two adhesives would result in a different morphological appearance of the hybrid layer. Ultrastructural TEM examination proved that each of the two dentin adhesive systems was able to establish a micromechanical bond between dentin and resin with the formation of a hybrid layer. However, the interfacial hybridization process that took place to produce this resin-dentin bond appeared to be specifically related to the chemical composition and application modes of both systems. OPTI consistently presented with a hybrid layer with a relatively uniform ultrastructure, electron density, and acid resistance. These three parameters were found to be more variable for the hybrid layer formed by SBMP. Characteristic of SBMP was the identification of an amorphous phase deposited at the outer surface of the hybrid layer. Although both adhesive systems investigated follow a total-etch concept, their specific chemical formulations result in different interfacial ultrastructures that are probably related to different underlying bonding mechanisms. The clinical significance of these morphological findings, however, is still unknown.
Induction of Lymphocytes Cytotoxic to Oral Epithelial Cells by Streptococcus mitis Superantigen
Authors: Matsushita K. , Sugiyama A. , Uchiyama T. , Igarashi H. , Ohkuni H. , Nagaoka S. , Kotani S. , Takada H.
Published: January 2009

The preparation of a superantigenic fraction F-2 from the culture supernatant of Streptococcus mitis 108, a fresh isolate from human tooth surfaces, was reported previously. Now, to determine the possible pathogenic role of the superantigen in oral mucosal diseases, we examined the cytotoxic effects of human peripheral blood T-cells activated with F-2 on human oral epithelial cells. T-cells activated with F-2 were cytotoxic to the human squamous carcinoma HO-l-N-1 cells derived from the oral mucosa, similar to those activated with Staphylococcus aureus enterotoxin B (SEB). This cytotoxic effect was increased in a dose-dependent manner by the addition of the respective stimulant, F-2 or SEB, to the cytotoxic assay system. F-2 endowed mainly CD8+ T-cells with cytotoxic activity. Pretreatment with human interferon gamma increased the sensitivity of the HO-l-N-1 cells to the cytotoxic effects of F-2-activated T-cells. The F-2-activated T-cells were also cytotoxic to human keratinocytes derived from gingiva. There was no correlation between the degree of cytotoxicity and the levels of tumor necrosis factor alpha in co-cultures of F-2-activated T-cells and HO-l-N-1 cells. A double-chamber plate experiment revealed no cytotoxic effects when the F-2-activated T-cells were separated from the HO-l-N-1 cells. Supernatants of the co-cultures of target and effector cells were not cytotoxic to HO-1-N-1 cells. These findings suggest that the cytotoxic effects of the F-2-activated T-cells on HO-l-N-1 cells were mediated not by soluble factors but by the direct interaction between the activated T-cells and the target cells. The cytotoxicity of the F-2-activated T-cells against HO-l-N-1 cells was markedly inhibited by monoclonal antibodies (MAbs) against CDlla and CD54, but was only slightly inhibited by MAbs against human leukocyte antigen (HLA)-DR and CD2. Thus, the interaction between lymphocyte-function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) was crucial for the F-2-dependent T-cell-mediated cytotoxicity against oral epithelial cells, while HLA-DR and CD2 molecules are not necessarily involved in the cytotoxicity observed.
The Final pH of Bacteria Comprising the Predominant Flora on Sound and Carious Human Root and Enamel Surfaces
Authors: van Houte J. , Lopman J. , Kent R.
Published: January 2009

Acidogenesis at low pH appears to be an important bacterial cariogenic trait. However, most information in this regard pertains to only a few of the acidogenic dental plaque bacteria. Therefore, the 'final' pH in sugar broth was determined for a wide variety of oral bacteria. Their source was: (1) carious material from advanced root lesions (ARL), (2) plaque from sound root surfaces of root-caries-free subjects (SRS), (3) plaque from "white spot" coronal lesions and sound coronal surfaces of caries-active subjects, and (4) plaque from sound coronal surfaces of caries-free subjects. Strains from groups 1 and 2 (ARL, 389 strains; SRS, 358 strains) were previously identified (van Houte et al., 1994) to the genus/species level and belonged to the predominant cultivable flora (PCF). Strains from groups 3 and 4 also belonged to the PCF but were not identified. All strains were placed in one of 4 final pH categories: < 4.2, 4.2 - 4.4, 4.4 - 4.6, and ≥ 4.6. The main findings were: (1) ARL samples contained many strains with a final pH < 4.2 (mean percentage of 25.7). They included all strains of Lactobacillus and mutans streptococci (MS), most Bifidobacterium strains and non-mutans streptococci (non-MS), and about 20% of the Actinomyces strains. By contrast, SRS samples contained far fewer strains with a final pH < 4.2 (mean percentage of 8.4) which were nearly all non-MS. (2) Organisms with a final pH < 4.4 constituted mean percentages of 41.5 and 32.1 for the ARL and SRS samples, respectively. (3) The final pH distribution of strains in samples from coronal surfaces showed a tendency relative to caries activity (group 3 vs. group 4) similar to that for groups 1 and 2. Our findings further support the concept that increased cariogenic conditions are associated with increased proportions of organisms capable of acidogenesis at a low pH and that this shift involves organisms other than the MS and lactobacilli.
Quantitative Analysis of the Dentin Adhesive Interface by Auger Spectroscopy
Authors: Eick J.D. , Miller R.G. , Robinson S.J. , Bowles C.Q. , Gutshall P.L. , Chappelow C.C.
Published: January 2009

The ultimate success of a dentin adhesive bond is dependent in large part on specific conditions at the interface between the tooth and the adhesive. Most current dentin adhesive systems use some sort of pre-treatment to demineralize the first few microns of the dentin surface, leaving a meshwork of collagen into which the adhesive resin can penetrate, infiltrate, and polymerize. The general hypothesis tested in this experiment was that the penetration and distribution of adhesive resin into the demineralized zone are a function of the conditioner used as a pre-treatment for the adhesive application. Four commercially available adhesive systems were modified to incorporate hydroxyethylthiomethacrylate (HETMA), a sulfur-substituted, traceable analogue of 2-hydroxyethylmethacrylate (HEMA), thereby allowing for a qualitative measurement of the amount and distribution of monomer in the treated dentin substrate by energy-dispersive x-ray spectroscopy (EDS) and a quantitative measurement by Auger electron spectroscopy (AES). The dentin pre-treatments investigated were: (1) 10% citric acid/3% ferric chloride, (2) 10% maleic acid, (3) 2.5% nitric acid, and (4) an alcoholic solution of HEMA with a phosphorus acid ester. These pre-treatments were applied to freshly extracted teeth that had been sectioned to expose the dentin and ground to simulate the smeared layer. After the appropriate pre-treatment was applied, a 10% (v/v) solution of HETMA in acetone was applied to the surface, followed by the corresponding adhesive resin, which was then polymerized. The samples were then processed for observation by scanning transmission electron microscopy (STEM), AES, and STEM/EDS analysis. The results indicated significant differences in the ability of HETMA to penetrate the dentin surface conditioned by the four pre-treatments investigated here. This study also demonstrated that AES and STEM/EDS could be used in a correlative fashion to determine the distribution of HETMA within or adjacent to the treated dentin surface.