Prevention of Root Caries1

Primary prevention of root caries should focus on preventing periodontitis and the concomitant loss of gingival attachment. This requires a regimen of plaque control consisting of scrupulous oral hygiene, supplemented, if necessary, by antimicrobial agents. Once gingival recession has occurred, available data from human and animal studies indicate that to prevent root caries, patients should limit their dietary sucrose intake both in amount and frequency. The cornerstone of any preventive regimen for patients at high risk for caries is some mode of topical fluoride therapy. No controlled clinical data exist that show one agent (sodium fluoride versus stannous fluoride) or one vehicle (gel versus rinse) as more effective than another. When used daily at home, these topical fluoride agents reduce caries in patients with xerostomia. Some reports claiming efficacy are anecdotal, but ethical considerations preclude the use of an untreated control group. As no studies exist documenting an effect of topical fluoride in controlling root caries per se, current recommendations are based on extrapolation from studies of these xerostomic patients. Limited studies, both in humans and animals, indicate that drinking fluoridated water helps in reducing root caries. Progression of early root caries lesions can be arrested by a combination of mechanical/chemical therapy, recontouring and smoothing the roots, and applying topical fluoride to these surfaces.     

Epidemiology of Root Caries1

Over a dozen studies have been conducted on the prevalence of and factors associated with root caries, yet our knowledge of this disease process remains limited. This is due, in large part, to a lack of consistency of reporting among the studies undertaken and the wide spectrum of population groups investigated. Nevertheless, the occurrence of root caries is between 20 and 40 percent in healthy, urban adults. Certain population groups such as the institutionalized elderly and patients with periodontal disease tend to exhibit much larger prevalence rates. New root caries develops slowly and tends to be concentrated in a few individuals, usually on the buccal and proximal surfaces of teeth. It is generally accepted that only roots with gingival recession are susceptible to root caries and that age, sex, oral hygiene, diet, saliva, systemic fluoride and previous carious experience have been shown to be associated factors. The next wave of investigations of root canes should focus on testing hypotheses relating to causation so that efficacious preventive and treatment procedures can be developed.     

Analysis of 35 Inorganic Elements in Teeth in Relation to Caries Formation

As caries is a most common affliction of teeth, which are predominantly composed of inorganic elements, it was considered worthwhile to determine their elemental composition and to find if it bears any relation to caries formation. For this purpose, 35 inorganic elements were determined in 15 non-carious and an equal number of carious whole teeth after their dissolution in nitric acid. The results showed that out of 35 elements, strontium was the only element found to be present in significantly lower amount in carious teeth, thus strongly suggesting that its deficiency may help form caries. The decrease in Ca, Mg, Ti, P, Li, Be, V, Ni, Zn, Nb, Ag, Cd, Sb, Ba, La , W, Pb, and Bi and slight increase in K, Cr, Cu, and As was not statistically significant. However, statistically significantly greater amount of boron, manganese, molybdenum, and fluorine in the carious teeth indicates towards their possible role in predisposing or causing dental caries.     

Demineralization and Remineralization of Root Surface Caries

Although enamel, cementum and dentin all develop carious lesions in roughly the same manner there are significant differences between enamel and the other two tissues. While early enamel lesions are white, root surface lesions in cementum or dentin are light brown or yellow. The color probably arises from extrinsic stain materials, and it is possible that very early, actively forming lesions are colorless. Cementum and dentin often acquire a hypermineralized surface when first exposed to the oral environment. When caries begins to form, this layer can enlarge or disappear. Therefore, it is possible to have lesions with hypermineralized surface layers, hypomineralized surface layers, or no surface layer. Hypermineralization can also occur deeply within a lesion, probably as a result of remineralization. When this occurs the lumen of the tubules fill with mineral and the crystals within the lesion body become larger. Fluoride is readily taken up by carious root tissues and contributes to remineralization. Remineralization of artificial root surfaces after treatment with monofluorophosphate has been shown. In these lesions much of the newly acquired mineral was found near the surface but some was also found in the lesion body.     

The Clinical Profiles of Individuals With and Without Root Surface Caries1

As part of a collaborative multidisciplinary investigation of root surface caries (RSC), 273 subjects (median age = 57) were clinically evaluated for coronal caries, debris, calculus, gingivitis, periodontal pocketing, recession, abrasion, as well as RSC. The entire study group was divided into three subgroups: (1) subjects whose exposed root surface were without lesions or restorations (non-diseased individuals, n= 43); (2) subjects whose exposed root surfaces had one or more lesions and may or may not have had restorations (diseased individuals, n= 110); (3) subjects with one or more restorations but no lesions, since it was not known whether these restorations were preceded by RSC or abrasion the disease status of these individuals was unclear (n= 120). A comparison of Subgroup 1 (unequivocally non-diseased) and Subgroup 2 (unequivocally diseased) revealed that subjects without RSC had more teeth, less coronal caries, less recession, less debris, less calculus, less gingivitis, and more abrasion. We infer that the common factor underlying most if not all of the subgroup differences is oral hygiene which must therefore be a major disease determinant.     

Methodological Issues Relative to the Quantification of Root Surface Caries1

The purpose of this study was to assess the effect upon the quantification of root surface caries (RSC) of (1) the separation of the disease into its discrete clinical phases, (2) the confounding caused by the presence of restored abraded surfaces, and (3) the decision rule formulated for dealing with lesions and restorations which involve both crown and root. It was found that the apparent prevalence of RSC varied widely depending upon arbitrary decisions as to what stages of the disease were included in the measurement scheme. The addition of restorations (confined to the root) greatly enlarged the various disease measures, but probably also introduced some degree of error since there are several indications from the data and the clinical patterns of affected surfaces which suggest that some of the restored surfaces were formerly abraded rather than carious. The inclusion of lesions and restorations involving both root and crown produced another conspicuous increment in all disease measures, which is a cause for concern given that these components are included in some studies and ignored in others. These findings serve as the basis for several recommendations for future prevalence and incidence studies of RSC.     

四种液体不同作用时间对根管壁的影响

目的：观察乙二胺四乙酸盐（Ethylene diamine tetraacetic acid,EDTA）、氯亚明（Chloramine）、丁克除（Desocclus01）和酚克除（Re-sosolv）等4种化学预备液根管内封药时对根管壁的影响。方法：选择因正畸拔除的健康前磨牙65颗,实验组60颗和对照组5颗。实验组随机分为A、B、C、D4组。每组15颗,各组又随机分为10d组、20d组和30d组,每组5颗。常规开髓、拔髓、干燥根管后丙烯酸树脂封闭根尖孔。根管内封药,磷酸锌暂封,4℃生理盐水中储存,对照组不做任何处理,相同条件下储存。丙烯酸树脂包埋,硬组织切片机切片,扫描电镜观察。结果：通过扫描电镜观察,在本实验周期内与对照组相比较,EDTA封药10天、20天和30天组,根管壁均有不同程度的脱矿,尤其是30d组。氯亚明和丁克除封药10天、20天和30天组,根管壁均有不同程度的脱矿,尤其是30d组,但脱矿部位主要位于根管壁内层,根管壁中外层脱矿较轻。酚克除封药3个时间组,根管壁均无脱矿。结论：EDTA根管内封药20天以内相对安全,不会造成根管壁的重度脱矿。氯亚明和丁克除根管内封药30天以内均不会造成根管壁的重度脱矿。酚克除对根管壁无影响。     

Effect of a 0.05% Neutral NaF Mouthrinse on Coronal and Root Caries of Adults1

Three-year coronal and root caries increments were compared in adults rinsing with either a 0.05% neutral NaF mouthrinse or a placebo mouthrinse. 1006 subjects, initially 20–65 years old (mean age: 39.9 yrs). who resided in fluoride deficient communities used a fluoride or placebo mouthrinse daily in their homes and brushed with an A.D.A. accepted fluoride dentifrice provided by the study. After three years, 731 subjects remained. Compliance was good. There were no significant differences (t-test, p≤ 0.05) in coronal DMFT, coronal DMFS, root DFT and root DFS between the two groups. In subjects exhibiting root caries at the final examination, the DF root surface increment was 25.1% less in the fluoride mouthrinse users compared to those using the placebo rinse, but this difference was not statistically significant. The only significant difference in the caries increment between the two study groups was found for the mesio-distal root surfaces of 45–65 year old participants.     

Extensive Description and Comparison of Human Supra-Gingival Microbiome in Root Caries and Health

Knowledge of the polymicrobial etiology of root caries is limited. To conduct a comprehensive research study on root caries, we utilized 454-pyrosequencing of 16S rRNA gene libraries and quantitative PCR to compare supra-gingival bacterial communities from healthy sites and carious sites of 21 patients with root caries (Patient-controls and Patient-cases) and the sites of 21 healthy individuals (Healthy-controls) from two nursing homes. Healthy-controls and Patient-cases showed no significant differences in terms of biomass, species richness, and species diversity. However, as for beta diversity based on either community membership metric (unweighted UniFrac) or community structure metric (weighted UniFrac), Healthy-controls and Patient-cases were clearly distinguished from each other, appearing more variable in the community membership and structure in root caries microbiome but relatively conserved in the health microbiome. The Patient-controls group was at an intermediate stage between Healthy-controls and Patient-cases, but was more inclined to the former. Demonstrated in both relative abundance and prevalence of species in health and root caries, Propionibacterium acidifaciens, Streptococcus mutans, Olsenella profusa, Prevotella multisaccharivorax, and Lactobacillus crispatus were found to be most associated with root caries, whereas Delftia acidovorans, Bacteroidetes[G-2] sp., Lachnospiraceae[G-3] sp., and Prevotella intermedia are most associated with health. Our study provides a basis for further elucidating the microbial etiology of root caries in the elderly.     

Er,Cr:YSGG激光照射对牙周病牙根面的影响

目的:观察不同能量输出的Er,C r:YSGG激光照射对牙周病牙根面的影响,探讨Er,C r:YSGG激光用于牙周治疗的可行性和有效性。方法:选择因牙周病松动Ⅲo而拔除牙12颗,随机分3组,每组4颗。分别以1.5 W、2.0 W、2.5 W激光照射。扫描电镜(SEM)观察各组牙根表面和纵剖面。结果:低倍镜下各组根面改变无明显差异,表面干净,粗糙程度均匀,未见明显弹坑状痕迹;高倍镜下1.5 W激光照射组显示根面粗糙程度更均匀一致,无弹坑状改变,无熔融、炭化迹象,未见牙本质小管暴露。结论:Er,C r:YSGG激光能有效去除牙周病牙根面玷污层及病变牙骨质,根面无熔融、炭化等改变。1.5 W激光照射组优于2.0 W组和2.5 W组。     

Stacking Increments: A New Model and Morphospace for the Analysis of Bivalve Shell Growth

A model employing stacking increments is introduced for the analysis of bivalve shell growth and form. The model is based on the components of shell growth that are potentially independent: the rate of mantle cell proliferation, the rate of precipitation of shell material, and the rate of translation of the pallial line, where the mantle is attached to the shell. This model is defined in terms of the following parameters: (1) the ratio of accretion of shell material at the shell margin to growth of the mantle by cell division, (2) the ratio of shell accretion at the pallial line to mantle growth, and (3) the ratio of the amount of pallial muscle translation, away from the umbo toward the shell margin, to mantle growth. In this model, the shape of a radial section through the shell is simulated by stacking of internal microgrowth increments. The mode of stacking of the increments is determined by the balance among the parameters defining growth. A theoretical morphospace defined on the basis of this model is largely consistent with the range of forms of naturally occurring bivalve shells. Analysis of the distribution of actual shell forms in relation to this morphospace suggests that the absolute rate of shell precipitation and the gradient in precipitation rate away from the shell margin along a radial cross-section are physiologically as well as geometrically constrained.     

Dentin Matrix Protein 1 and Dentin Sialophosphoprotein in Human Sound and Carious Teeth: An Immunohistochemical and Colorimetric Assay

Dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP) are extracellular matrix proteins produced by odontoblasts involved in the dentin mineralization. The aim this study was to compare the distribution of DMP1 and DSPP in human sound dentin vs human sclerotic dentin. Sixteen sound and sixteen carious human molars were selected, fixed in paraformaldehyde and processed for immunohistochemical detection of DMP1 and DSPP by means of light microscopy, transmission electron microscopy (TEM) and high-resolution field emission in-lens scanning electron microscopy (FEI-SEM). Specimens were submitted to a pre-embedding or a post-embedding immunolabeling technique using primary antibodies anti DMP1 and anti-DSPP and gold-conjugated secondary antibodies. Other samples were processed for the detection of DMP1 and DSPP levels. Dentin from these samples was mechanically fractured to powder, then a protein extraction and a protein level detection assay were performed. DMP1 and DSPP were more abundant in carious than in sound samples. Immunohistochemical analyses in sclerotic dentin disclosed a high expression of DMP1 and DSPP inside the tubules, suggesting an active biomineralization of dentin by odontoblasts. Furthermore, the detection of small amounts of these proteins inside the tubules far from the carious lesion, as shown in the present study, is consistent with the hypothesis of a preventive defense of all dentin after a noxious stimulus has undermined the tooth.Key words: sclerotic dentin, dentin matrix protein, dentin sialophosphoprotein, immunohistochemistry     

Consumption of Meals Prepared at Home and Risk of Type 2 Diabetes: An Analysis of Two Prospective Cohort Studies

BackgroundThere has been a trend towards increased dining out in many countries. Consuming food prepared out of the home has been linked to poor diet quality, weight gain, and diabetes risk, but whether having meals prepared at home (MPAH) is associated with risk of type 2 diabetes (T2D) remains unknown.ConclusionsIn two large prospective cohort studies, frequent consumption of MPAH is associated with a lower risk of developing T2D, and this association is partly attributable to less weight gain linked with this dining behavior.     

Action of Urea Solutions on Unerupted and Erupted Teeth: An Investigation on Late Maturation of Human Enamel1

Replicas of unerupted and erupted human enamel submitted to protein-disrupting solutions showed: (1) an inequal distribution of porosities in the subsurface; (2) such porosities were restricted gradually in each enamel subunit (enamel segments limited by two perikymata). First the whole surface was covered by a network, reduced at a later stage to half of the surface and ultimately the porosities were present only in the perikymata. This paper confirms the occurrence of a late maturation at stage where cells are no longer active and details the time-dependent involution of these porosities.     

Breast and Bottle Feeding as Risk Factors for Dental Caries: A Systematic Review and Meta-Analysis

Understanding the role that breastfeeding and bottle feeding play in the development of dental caries during childhood is essential in helping dentists and parents and care providers prevent the disease, and also for the development of effective public health policies. However, the issue is not yet fully understood. The aim of this systematic review and meta-analysis was to search for scientific evidence in response to the question: Do bottle fed children have more dental caries in primary dentition than breastfed children? Seven electronic databases and grey literature were used in the search. The protocol number of the study is PROSPERO CRD 42014006534. Two independent reviewers selected the studies, extracted data and evaluated risk of bias by quality assessment. A random effect model was used for meta-analysis, and the summary effect measure were calculated by odds ratio (OR) and 95% CI. Seven studies were included: five cross-sectional, one case-control and one cohort study. A meta-analysis of cross-sectional studies showed that breastfed children were less affected by dental caries than bottle fed children (OR: 0.43; 95%CI: 0.23–0.80). Four studies showed that bottle fed children had more dental caries (p<0.05), while three studies found no such association (p>0.05). The scientific evidence therefore indicated that breastfeeding can protect against dental caries in early childhood. The benefits of breastfeeding until age two is recommended by WHO/UNICEF guidelines. Further prospective observational cohort studies are needed to strengthen the evidence.     

Risk Assessment and Risk Management: An Essential Integration

The integration of Risk Assessment and Risk Management is a necessary step in environmental regulation. The compromises involved in the Risk Management process can not be allowed to violate the scientific integrity of the Risk Assessment. The inclusion of a cost/benefit analysis necessitates the valuation of ecological processes. These values are based on the costs of replacement in volume, in kind, and in place. The Risk Management is then presented as a Rolling Stewardship where Risk Management is balanced with Cash Management.     

Root Growth at the Cellular Level in Plants of Different Species: Comparative Analysis

Russian Journal of Plant Physiology - Analysis of root growth parameters was carried out on the seedlings of 53 monocotyledonous and 78&nbsp;dicotyledonous plant species. Daily increases of the...     

Accessing Developmental Information of Fossil Hominin Teeth Using New Synchrotron Microtomography-Based Visualization Techniques of Dental Surfaces and Interfaces

Quantification of dental long-period growth lines (Retzius lines in enamel and Andresen lines in dentine) and matching of stress patterns (internal accentuated lines and hypoplasias) are used in determining crown formation time and age at death in juvenile fossil hominins. They yield the chronology employed for inferences of life history. Synchrotron virtual histology has been demonstrated as a non-destructive alternative to conventional invasive approaches. Nevertheless, fossil teeth are sometimes poorly preserved or physically inaccessible, preventing observation of the external expression of incremental lines (perikymata and periradicular bands). Here we present a new approach combining synchrotron virtual histology and high quality three-dimensional rendering of dental surfaces and internal interfaces. We illustrate this approach with seventeen permanent fossil hominin teeth. The outer enamel surface and enamel-dentine junction (EDJ) were segmented by capturing the phase contrast fringes at the structural interfaces. Three-dimensional models were rendered with Phong’s algorithm, and a combination of directional colored lights to enhance surface topography and the pattern of subtle variations in tissue density. The process reveals perikymata and linear enamel hypoplasias on the entire crown surface, including unerupted teeth. Using this method, highly detailed stress patterns at the EDJ allow precise matching of teeth within an individual’s dentition when virtual histology is not sufficient. We highlight that taphonomical altered enamel can in particular cases yield artificial subdivisions of perikymata when imaged using X-ray microtomography with insufficient resolution. This may complicate assessments of developmental time, although this can be circumvented by a careful analysis of external and internal structures in parallel. We further present new crown formation times for two unerupted canines from South African Australopiths, which were found to form over a rather surprisingly long time (> 4.5 years). This approach provides tools for maximizing the recovery of developmental information in teeth, especially in the most difficult cases.     

Superoxide Dismutase Activity in Pseudomonas putida Affects Utilization of Sugars and Growth on Root Surfaces

To investigate the role of superoxide dismutases (SOD) in root colonization and oxidative stress, mutants of Pseudomonas putida lacking manganese-superoxide dismutase (MnSOD) (sodA), iron-superoxide dismutase (FeSOD) (sodB), or both were generated. The sodA sodB mutant did not grow on components washed from bean root surfaces or glucose in minimal medium. The sodB and sodA sodB mutants were more sensitive than wild type to oxidative stress generated within the cell by paraquat treatment. In single inoculation of SOD mutants on bean, only the sodA sodB double mutant was impaired in growth on root surfaces. In mixed inoculations with wild type, populations of the sodA mutant were equal to those of the wild type, but levels of the sodB mutant and, to a great extent, the sodA sodB mutant, were reduced. Confocal microscopy of young bean roots inoculated with green fluorescent protein-tagged cells showed that wild type and SOD single mutants colonized well predominantly at the root tip but that the sodA sodB double mutant grew poorly at the tip. Our results indicate that FeSOD in P. putida is more important than MnSOD in aerobic metabolism and oxidative stress. Inhibition of key metabolic enzymes by increased levels of superoxide anion may cause the impaired growth of SOD mutants in vitro and in planta.