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PubMed1986

Initial attachment of fibroblast-like cells to periodontally-diseased root surfaces in vitro.

The precise factors mediating both initial cell attachment and longer term connective tissue reattachment after tissue destruction due to periodontal disease are not known. An in vitro model was used to assess initial attachment of fibroblast-like cells to periodontally-diseased root surfaces. Root fragments were obtained from freshly extracted teeth from 6 different patients. Individual roots were prepared such that a comparison could be made of initial attachment to non-instrumented diseased root surface, curetted diseased root surface and the non-diseased, non-instrumented portion of the same root. The amount of hard tissue removed by instrumentation was quantitated and kept constant between 0.9-1.0 mm. The unsterilized fragments were incubated with human gingival fibroblasts (HGF) for 1 h at 37 degrees, after which the roots were first washed to remove non-adherent cells and then photographed. The number of attached cells per unit area was quantitated from the photographs using a grid system. No significant differences could be detected between the numbers of cells attached to the 3 types of root surfaces studied on the individual roots or between any of the roots studied. Thus, initial attachment of HGF to diseased root surfaces is not inhibited by the presence of plaque or endotoxins.

Cell Adhesion↗
PubMed1993

Resistance to vertical fracture of roots, previously fractured and bonded with glass ionomer cement, composite resin and cyanoacrylate cement.

A recently developed glass ionomer bone cement (Ionos) may be suitable for bonding vertically fractured teeth, but the resulting resistance to repeated fracture of the bonded teeth is unknown. The purpose of this study was to assess in vitro the resistance to repeated fracture of roots which were previously fractured and bonded with Ionos cement and other bonding agents. Thirty-six roots were separated at the cervix and grooved on the coronal surface. Each root was mounted in an Instron machine and a vertical force was exerted until fracture occurred. Both the force required to fracture the root (F) and the root surface area (A) were recorded, and the root halves were bonded with one of the following materials: Ionos bone cement without dentin etching, Permabond 910 cyanoacrylate adhesive, and Gluma bonding system. The bonded roots were maintained in a wet sponge. One week later the roots were re-fractured in the Instron machine, and the forces were recorded (RF). Each one of F, RF, A, and the ratios RF/F and RF/A were compared statistically among the three experimental groups. Overall, RF was at the most 20% of F. Statistically significant differences were obtained only in RF, RF/F, and RF/A (p < 0.0003). Roots bonded with Ionos cement demonstrated significantly lower values than roots bonded with Permabond and Gluma, both of which did not differ significantly. It was concluded that roots bonded with Ionos cement were the least resistant to re-fracture, due to a lesser bonding strength of Ionos bone cement as compared with Permabond and Gluma.

Acid Etching, Dental↗
PubMed1998

Pulp and root development after partial extrusion in immature rat molars: a histopathological study.

Experimental studies were undertaken in immature rat molar teeth to investigate the relationship between root development and the prognosis after partial extrusion. The experimental partial extrusion was induced at 1/2 root formation, 2/3 root formation and 3/4 root formation, using an extrusion device designed by the author. Histopathological studies and SEM observation of the pulpal tissue in rat maxillary first molars with partially formed roots after partial extrusion were conducted and evaluated. The degree of extrusion was changed according to the development of the root to produce a similar luxated state. The rats were sacrificed immediately after experimental extrusion, immediately after operation, and after 3 days, 7 days, 14 days, 30 days, and 60 days to compare the histopathological and SEM findings between experimental groups and control groups. Immediately after the extrusive injury, ablations of the odontoblast layer from dentin were seen with retention of a fluid component in the ablated spaces in the pulp. On 1 and 3 days after surgery, cellular components such as erythrocytes and leukocytes due to bleeding were seen. Ablations of the odontoblast layer were seen in the coronal pulp most frequently in the pulp horn, cervical area and floor of the pulp chamber. In general, pulp reaction after extrusion in groups with more complete root formation was more severe than in groups with less complete root formation. It is suggested that the more complete the root formation, the greater the effect on the pulp as result of partial extrusion, while with less complete root formation, the greater the malformation of the root apices.

Animals↗
PubMed1999

Number of roots and canals in maxillary first premolars: study of an Andalusian population.

A study of 150 extracted maxillary first premolars from citizens of Seville, Andalusía, southern Spain, revealed 60 teeth with one root (40.0%), 85 teeth with two roots (56.7%) and five teeth with three roots (3.3%). The distribution of root canal shapes in the sample showed that all teeth with two or three roots had type I root canals (each canal had one apical foramen). Conversely, most of the single-rooted maxillary first premolars had root canal shape type II (two canals converging in the same apical foramen). Only 1.3% of the teeth had a unique orifice in the pulp chamber and only one root canal. These results emphasized the importance of good knowledge of the root canal morphology and the need for a careful radiographic examination as part of competent root canal therapy of maxillary first premolars.

Bicuspid↗
PubMed1989

Three-year root caries increments: implications for clinical trials.

Seven hundred and ninety-six adult subjects (mean age, 39.9 years) received visual-tactile examinations for root caries over a three-year period. All subjects were employed or were the spouses of employees and resided in fluoride-deficient communities on Long Island, New York. During the three-year observation period, 81.4 percent of the subjects did not develop root caries. The 18.6 percent who developed root caries averaged 0.8 DFS/year. The subjects' ages and baseline root DFS status were associated with the development of a root DFS increment. The older the patient, especially aged 45 and older, the greater was the risk of developing root lesions or having root fillings placed. Subjects who had a root DFS score at baseline also were more likely to experience a root DFS increment. It is recommended that when designing clinical trials of agents purported to inhibit root caries, preselection criteria for the study population should consider the subjects' ages and past history of root lesions.

Adult↗
PubMed1997

Do root lesions tend to develop in the same people who develop coronal lesions?

OBJECTIVES: The three purposes of this study are to: (1) describe the relationship between the prevalence of coronal caries and root caries; (2) describe the relationship between the three-year incidence of coronal caries and root caries; and (3) if the two conditions are associated, develop a multiple regression model that identifies characteristics distinguishing people who had increments of both root caries and coronal caries from people who had increments of either coronal caries or root caries, or who had no new caries. METHODS: Dental examinations and interviews were conducted in the homes of a randomly selected, stratified sample of people over the age of 65 years in five North Carolina counties. The relationships between coronal and root D and DF were analyzed through contingency table analyses, and ordinal logistic regression was used to identify characteristics that differentiated people who had both coronal and root D over the three years from people who had either coronal or root D and people who had no new disease. RESULTS: Evidence of root and coronal caries in whites was much more likely to be in the form of fillings, while for blacks, it was more likely to be in the form of untreated decay. Prevalence rates of coronal and root D and DF were significantly associated for both blacks and whites. Incidence rates based on DF indicated that root and coronal caries were not associated in whites, but were associated in blacks. People more likely to experience both types of caries had more gingival recession at baseline, greater average attachment loss over the three years, and lactobacilli at baseline. In addition, the presence of Porphymonas gingivalis at three years was important for whites. CONCLUSIONS: It appears that coronal and root caries do tend to appear together in the same individuals, but fillings attenuate that relationship. The impact of dental treatment on the epidemiology of dental caries appears to be considerable and calls into question whether the F component of the caries index is related to disease as defined by epidemiologic criteria.

Aged↗
PubMed1998

Root morphology of the maxillary first premolar in Singaporeans.

Extracted teeth were collected from clinical procedures performed in the Faculty of Dentistry, National University of Singapore. A selected sample of 957 maxillary first premolars were subjected to visual examination and digital radiography. There was a higher incidence of two-root form (50.6 per cent) than previously reported for the Singaporean dentition. In the two-root category, 307 teeth exhibited the fused-root form (two fused roots with two root canals) and 177 were distinctively of the two-root form (two separate roots with two root canals and two foramina). The fused-root form was emphasized as an entity in this study. The one-root form accounted for 49.4 per cent. No three-root form was detected.

Bicuspid↗
PubMed2006

The ability of thiourea to scavenge hydrogen peroxide and hydroxyl radicals during the intra-coronal bleaching of bloodstained root-filled teeth.

BACKGROUND: Hydrogen peroxide, an agent used in the intra-coronal bleaching of root-filled teeth for over a century, has been shown to diffuse from the pulp chamber to the outer root surface. Furthermore, it has been demonstrated that destructive hydroxyl radicals, the by-products of the bleaching process, have been detected on the external root surface. The control of such diffusion may be of importance in minimizing the risk of invasive cervical resorption (ICR) which has been linked to intra-coronal bleaching of discoloured root-filled teeth using hydrogen peroxide. The aims of the present in vitro study are to quantify the diffusion of hydrogen peroxide and hydroxyl radicals to the outer root surface following intra-coronal bleaching, and to evaluate the ability of thiourea incorporated into the bleaching protocol to scavenge residual hydrogen peroxide and hydroxyl radicals. METHODS: Thirty-five single rooted premolar teeth with intact cementum at the cemento-enamel junction were used in this project. Thirty teeth were stained with red blood cells and root-filled with gutta-percha and AH26. The five unstained teeth were root-filled and constituted a negative control (Group 1). The stained teeth were divided equally into the following experimental groups and subjected to various intra-coronal bleaching regimes: Group 2--'walking bleach' with 20 microl 30 per cent w/w hydrogen peroxide; Group 3--20 microl 30 per cent w/w hydrogen peroxide and thermocatalytically activated; Group 4--20 microl acidified thiourea; Group 5--20 microl acidified thiourea and 20 microl 30 per cent w/w hydrogen peroxide; Group 6--20 microl acidified thiourea and 20 microl one per cent sodium hypochlorite; Group 7--20 microl acidified thiourea, 20 microl one per cent sodium hypochlorite and 20 microl 30 per cent w/w hydrogen peroxide. The reaction products of the bleaching process were quantified at the outer root surface using high performance liquid chromatography and electrochemical detection (HPLC-ECD). RESULTS: Results showed that hydrogen peroxide used alone in Groups 2 and 3 was able to be detected at the outer root surface in 100 per cent of the samples, and that the presence of the hydroxyl radical generated in both groups was detected in equal amounts (P < 0.05). When thiourea was incorporated into the bleaching protocols in Groups 5-7, it was shown to scavenge both hydrogen peroxide and hydroxyl radicals to a significant degree (P < 0.05). CONCLUSIONS: Acidulated thiourea is an effective scavenger of residual hydrogen peroxide and hydroxyl radicals generated during the intra-coronal bleaching of bloodstained root-filled teeth.

Antioxidants↗
PubMed1993

Spread of the dorsal root reflex in an isolated preparation of hamster spinal cord.

In an isolated preparation of hamster spinal cord maintained at 27 degrees C, stimulation of a single dorsal root has been shown to evoke dorsal root reflexes in ipsilateral roots throughout the lumbar and thoracic cord. The dorsal root reflex was evoked by activity in low threshold dorsal root fibres, and left the cord through dorsal root fibres conducting at 5.9 m/s. The ipsilateral dorsal root reflex travelled equally well in both directions along the cord at a calculated velocity of 0.5 m/s at 27 degrees C. Comparison of the stimuli required to evoke dorsal root reflexes in adjacent and distant ipsilateral dorsal roots suggests that once this system is activated it operates largely in an all-or-none manner. The delay in the generation of the dorsal root reflex within the cord was calculated to be 4.7 +/- 0.2 ms at 27 degrees C, corresponding to approximately 2 ms at body temperature, suggesting that a trisynaptic pathway is involved in the generation of the dorsal root reflex at the segmental level.

Afferent Pathways↗
PubMed1996

[Geotropic reaction of different types of roots in Hevea brasiliensis].

To describe the different types of geotropic reactions of hevea (Hevea brasiliensis), young seedlings were cultivated in root observation boxes and submitted to a double gravistimulation (90 degrees rotation of the minirhizotrons in the vertical plane). It was demonstrated that the taproot is a strongly orthogeotropic organ since it resumed rapidly its prestimulation vertical position. Morphological and morphogenetic modifications were associated with the geotropic response: reduced speed of growth coupled with a reduction of the apical diameter as well as an alteration of ramification density in the curving zone and the following one. Early secondary roots showed a somewhat reduced orthogeotropism that was weaker as the growth direction before gravistimulation was more distant from the vertical. Secondary roots of the acropetal sequence were semiplagiotropic, that is only those roots oriented upward after the gravistimulation resumed, more or less, the original direction. Tertiary roots didn't respond to the gravistimulation and therefore were ageotropic. Complementary observations conducted in large laboratory rhizotrons showed that late forming secondary roots were plagiotropic in their younger stages, thereafter loosing most of their sensitivity to gravity. Quaternary roots were ageotropic. On the basis of these data, a geotropic gradient was defined within the hevea root system, where the strongly responding taproot and late secondary roots are opposed to the weakly or nonresponding tertiary and quaternary roots. Functional significations of the differential geotropic reactions in different hevea root types are discussed.

Gravitation↗
PubMed1992

Prediction of root caries in periodontally treated patients maintained with different fluoride programmes.

The aims of the investigation were to evaluate the effect of different fluoride programmes, as adjuncts to professional plaque control every 3-4 months, on root caries incidence in periodontally treated patients and to identify risk factors for root caries development. Ninety-nine individuals, 33-76 years old, who had been treated for periodontal disease were subjected to one of three fluoride programmes during a 2-year period: (1) professional application, 3-4 times/year, of Duraphat (n = 34) or (2) of a 0.4% stannous fluoride gel (n = 33), or (3) daily mouthrinsing with a 0.05% sodium fluoride solution (n = 32). A number of clinical recordings and laboratory tests, used as presumptive risk indicators for root caries, were carried out before and on three different occasions after the periodontal treatment. No statistically significant differences were found between the various fluoride programmes. During the 2-year period, a total of 246 new decayed or filled surfaces (DFS) were recorded, 72 (29.3%) of which were diagnosed as active and 124 (50.4%) as inactive root caries lesions; 50 (20.3%) of the surfaces had been restored. Individuals with > or = 1 new root DFS during the 2 years (n = 50) differed significantly from those with 0 new root DFS (n = 49) as concerns salivary counts of mutans streptococci and lactobacilli, root plaque scores and percentage of exposed root surfaces. Baseline root caries prevalence (r = 0.43) and root plaque scores (r = 0.36) showed the highest correlations with new root DFS.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2001

The predominant aciduric microflora of root-caries lesions.

The etiology of root caries is not fully understood, and although mutans streptococci, lactobacilli, and A. naeslundii have been implicated in its initiation and progression, this study was designed to determine the potential role of other microbial species and the nature of predominant aciduric microflora in the root caries process. We isolated the predominant aciduric microflora from root-caries lesions (n = 14) and sound root surfaces in subjects with (n = 13) or without (n = 10) root caries, using both a "most probable numbers" method and conventional plating methods. The predominant aciduric bacteria from root lesions were lactobacilli and A. israelii, while from sound root surfaces in subjects with root caries, A. gerencseriae comprised over 60% of aciduric isolates. Mutans streptococci were not among the aciduric isolates. Subjects without root caries harbored fewer bacteria, and S. anginosus (pH 4.8) and S. oralis (pH 5.2) were the predominant aciduric bacteria. The microbial etiology of root caries is more complex than was previously appreciated, and factors underlying the microbial succession occurring during the disease process are not known. Taxa with previously unrecognized aciduric characteristics have been isolated routinely, and the role of these organisms in the root caries process requires further investigation.

Actinomyces↗
PubMed1984

Fluoride-treated roots and viability and attachment of human gingival fibroblasts.

Topical fluoride treatment is used to help prevent root caries. It may also be useful in periodontal therapy because of its antimicrobial property. In addition, for therapeutic new attachment to occur, the fibroblasts approximating the treated root surface should remain viable, and should also be able to attach and grow onto the treated root surface. These conditions, at least, are required for fluoride not to interfere with new attachment. This study was designed to determine whether treatment of roots with fluoride adversely affects human gingival fibroblasts in culture; and what effect fluoride treatment has on attachment and growth of cells to the root surface. Cells originally obtained from human gingiva were allowed to grow to confluency in multi-well tissue culture petri dishes, and were then incubated for 24 hr in the presence of root sections as follows: (1) no treatment; (2) root-planed only; (3) 2% NaF only; (4) root-planed + 2% NaF; (5) root-planed + citric acid, pH 1 + 2% NaF. In addition, cells were plated onto roots similarly treated and were subsequently allowed to incubate for 72 hr. Viability of cells was determined by exclusion of vital dye and 51Cr retention. Attachment and growth of cells were determined by histology and scanning electron microscopy. Results indicated that, after 24 hours' exposure, there was little or no difference in cell viability between different treatment groups and control cultures. Also, all roots which had been planed accommodated cell attachment, regardless of additional treatment rendered.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1993

The epidemiology of root surface caries: North American studies.

After some problems resulting from the lack of standardized methods in the conduct of root caries studies and the lack of standardized reports of findings are reviewed, the prevalence and incidence of root surface caries in North America are reviewed through a combination of epidemiologic studies and large clinical trials. As part of this review, the available evidence on the relationship between root caries and missing teeth is presented. These data lead to the conclusion that the prevalence and, to some extent, the incidence of root caries are underestimated in adults with missing teeth. This review resulted in a number of observations regarding the status of root caries as an oral health problem. First, there is little evidence that would allow conclusions regarding the secular increase or decrease in the prevalence or incidence of root caries to be drawn. Other observations gleaned include the remarkably similar prevalence and incidence rates obtained from the studies reviewed, positive associations between root caries and age, negative associations between the prevalence and incidence of root caries and consumption of water containing fluoride, indications that root caries is a problem in adults with incidence rates that approach caries rates in children, and associations between the prevalence and incidence of root caries and a wide variety of oral, behavioral, and medical conditions. The final observation is the need for the acceptance of conventions for the definition of root caries as well as the reporting of findings in order for more firm conclusions to be drawn from future studies.

Adult↗
PubMed1979

Afferent fibers in the ventral root.

The dorsal rhizotomy was one of the earliest operations used for the treatment of chronic, intractable, segmental pain. The theoretical basis underlying the use of this procedure was the law of separation of function of the spinal roots that implies, among other things, that sensory fibers are located in the dorsal root and motor fibers are located in the ventral roots. On this basis, it should be possible by cutting the appropriate dorsal roots to relieve pain for any particular part of the body at the cost of making that part of the body anesthetic. Unfortunately, however, the dorsal rhizotomy seems to have a relatively low success rate in that the pain is often not relieved or is relieved for a variable period of time and then returns. Many different reasons may account for these failures, but one reason that is not often considered is that the law of separation of function of the spinal roots may not be accurate. This is pertinent at the present time, because large numbers of ventral root afferent fibers have recently been discovered. This review summarizes the work, both old and new, on ventral root afferent with particular emphasis on possible clinical applications. In particular, it is pointed out that the ventral root afferent fibers are probably present in humans and, if so, they may be involved in explanations for the failure of dorsal rhizotomy to relieve chronic pain. If these fibers are important, then they can be removed by a dorsal root ganglionectomy, which would remove both the dorsal and ventral root afferent fibers, as opposed to a dorsal rhizotomy, which would remove only the dorsal root afferent fibers.

Animals↗
PubMed2006

Different amounts of DNA in each mitochondrion in rice root.

The DNA content of individual mitochondria in rice root cells was analyzed by fluorescence microscopy. Differences in DNA content were detected between individual mitochondria. Some mitochondria contained no detectable nucleoid (DNA-protein complexes). The percent of mitochondria with DAPI(4',6-Diamidino-2-phenylindole) -stained nucleoids varied over the length of the root (root base, 33%; middle portion of root, 41%; root tip, 91%). The mean amounts of DNA per mitochondrial nucleoid were equivalent to 46.4 kbp in the root base, 52.0 kbp in the middle portion of root and 124.2 kbp in the root tip. The amount of DNA in individual mitochondria and the ratio of mitochondria with visible nucleoids were higher in the root tip than in other parts of the root. The estimated amount of DNA in almost all of the observed mitochondria was smaller than the amount of DNA equivalent to the rice mitochondrial genome size (490 kbp), even in root tip.

DNA, Mitochondrial↗
PubMed2001

Seasonal capacity of attached and detached vineyard roots to support grape phylloxera (Homoptera: Phylloxeridae).

Field experiments were conducted to evaluate population densities and survival, developmental rate, and fecundity of grape phylloxera, Daktulosphaira vitifoliae (Fitch), as influenced by root attachment or detachment from mature, field-grown, Vitis vinifera L. grapevines through the growing season. Experiments were performed using artificial infestations of California biotype A grape phylloxera. Thirty-day bioassays on attached- and detached-roots were repeated monthly from May to September in 1997 (cultivar 'Carignane') and April to September in 1998 (cultivar 'Thompson Seedless'). The bioassays showed that attached roots had lower population densities than detached roots in all months of both years. Densities varied by month, tending to be higher in spring than in summer. Of the population parameters studied, survival was most influenced by attachment condition, being higher on detached than on attached roots by up to 25-fold. These results imply the importance of vine-related mortality factors to grape phylloxera population density. Influence of root attachment condition on developmental rate and fecundity was not uniform across bioassay months for either year; however, in the four out of 21 assays where there was a significant difference it favored detached roots by twofold. Fruit harvest resulted in higher survival in the July assay but not for assays in August and September; however, neither developmental rate nor fecundity was affected by harvest in any ofthe assays. We conclude that mortality rather than nutritional factors are most limiting for field populations on susceptible vines. This work suggests that detachment of roots as occurs with root girdling by root pathogens may increase grape phylloxera populations on infested, susceptible vines. These results imply that excised root bioassays over-estimate grape phylloxera virulence and underestimate rootstock resistance.

Animals↗
PubMed2005

Changes of root morphology and Pb uptake by two species of Elsholtzia under Pb toxicity.

Elsholtzia argyi and Elsholtzia splendens, which are Chinese endemic Pb/Zn mined and Cu mined ecotype respectively, were investigated in the aspect of their response to Pb toxicity in the presence or absence of EDTA addition. After 8 d's Pb treatment, root length, root surface area and root volume of E. splendens decreased much more than those of E. argyi, and reduced considerably with increase of Pb, while no marked change was noted for root average diameter. Compared to E. argyi, length of root with diameter (D)<0.2 mm was significantly reduced for E. splendens as Pb increasing. Root with cross-sectional area of D<0.1 mm for E. splendens was at Pb> or =10 mg/L, while for E. argyi, it was at Pb> or =25 mg/L. DW of E. splendens decreased much more than that of E. argyi with increase of Pb. E. argyi exhibited much more tolerance to Pb toxicity than E. splendens. Treatment with 100 mg/L Pb plus 50 mmol/L EDTA significantly decreased the length and surface area of D< or =0.2 mm root, increased the length and surface area of 0.2< or =D< or =0.8 mm root for the case of E. argyi, while for E. splendens, length and surface area of D<0.6 mm root reduced, as compared to 100 mg/L Pb treatment, alone. At 100 mg/L Pb, shoot Pb accumulation in E. splendens and E. argyi were 27.9 and 89.0 microg/plant DW respectively, and much more Pb was uptaken by the root and translocated to the stem of E. argyi as compared to E. splendens. Treatment of the plant with 100 mg/L Pb plus 50 mmol/L EDTA increase leaf Pb accumulation from 16.8 to 84.9 g/plant for E.splendens and from 18.8 to 52.5 g/plant for E. argyi, while both root and stem Pb pronouncedly reduced for both Elsholtzia species. The increased translocation of Pb to the leaf of E. splendens than that of E. argyi at the treatment of 100 mg/L Pb plus 50 mmol/L EDTA should be further investigated.

Biodegradation, Environmental↗