Clinical evaluation of demineralization and remineralization of intact root surface lesions in the clinic by a quantitative light-induced fluorescence system.

Detection of demineralization of root surface caries is an important issue since preventive approaches prolong tooth life. Quantitative light-induced fluorescence (QLF) has been shown to be useful for the laboratory assessment of demineralization of root surfaces. The aim of this study was to determine the demineralization and remineralization of root surface intact and cavitated caries lesions using a QLF system as a nondestructive in vivo method. Noncavitated and demineralized root surface lesions were detected and scored using the QLF system. Oral hygiene education was given and periodontal cleaning was completed before the remineralization treatment. After obtaining baseline QLF data, the patients were informed about the remineralization treatment. Fluoride varnish was applied to the carious lesions at the baseline visit, and the patients were then reviewed after 1, 2, 3 and 4 weeks, with QLF assessment and fluoride varnish application repeated at each review. Repeated-measures ANOVA (α = 0.05) showed significant differences between ΔQ values at each visit (p < 0.001); ΔQ showed marked decreases at all the cut-off values (15, 20, 25, 30). The changes in ΔQ were not affected by the cut-off value. The ΔQ values of QLF showed differences at all visits. The QLF system was able to detect early root surface caries lesions in vivo. Bifluoride 12 varnish improved mineral levels as shown by the QLF system. The treatment response to chemicals of intact noncavitated root surface carious lesions could be followed nondestructively in the clinic using QLF to quantify remineralization at recall visits. Teeth with root surface caries can be kept by controlling their remineralization.

pH changes in external root surface cavities after calcium hydroxide is placed at 1, 3 and 5 mm short of the radiographic apex.

The purpose of this study was to test the null hypothesis that there is no difference in the pH on the external apical dentin surface when the canal is completely filled with calcium hydroxide or when it is placed 3 or 5 mm short of the apical foramen in extracted human teeth. The root canals of single-rooted anterior human teeth were cleaned and shaped after decoronation. Cavities about 0.50 mm deep and 1.0 mm wide located at 1, 3 and 5 mm from the radiographic apex were prepared on the external root surface and the teeth were randomly divided into four groups. The roots were filled with calcium hydroxide at 1, 3 and 5 mm from the radiographic apex, and the control group was left empty. pH readings were obtained at intervals over a 28-day study. The roots which were filled within 1 mm of the radiographic apex had the greatest increase in pH in each of the cavities. These results demonstrate that the greatest pH change on the external root surface near the apex is obtained when the canal is more completely filled with calcium hydroxide.

The effect of desalivation on coronal and root surface caries in rats.

Although the presence of coronal caries is declining in much of the Western Hemisphere, the prevalence of root surface caries is likely to increase as teeth are retained longer than heretofore. At the same time, an increasing number of the population suffer from dry mouth as a result of taking prescription drugs, with an apparent concomitant increased susceptibility to root surface caries. This study attempted to develop an animal model which would aid in the exploration of the effects of desalivation and the development of root surface caries. Animals were desalivated, infected with Actinomyces viscosus and Streptococcus mutans (sobrinus) 6715, and fed a cariogenic diet. Coronal caries developed rapidly in the animals; sufficient disease was present after two weeks to permit evaluation of potential therapeutic agents. Alveolar bone loss and root surface lesions developed in three to four weeks. S. mutans (sobrinus) and A. viscosus established readily in all animals; however, as the investigation progressed, populations of the latter declined, possibly because of the highly acidogenic environment. This model will facilitate investigation of the influence of hyposalivation and help in the exploration of agents to alleviate the adverse effects of salivary gland dysfunction.

Cariogenic potential of pooled plaque fluid from exposed root surfaces in humans.

The composition of pooled plaque fluid from exposed root surfaces of five population samples was determined before and at selected times (3, 7 and 15 min) after a 5 and 10% sucrose rinse. Subjects were 45-65 yr old, had exposed, sound root surfaces, and were grouped according to root caries status [caries-free (CF), no root caries history; caries-positive (CP), recorded root caries experience]. Samples were obtained only from the sound surfaces of the CF and CP subjects after overnight fasting. Plaque samples from each subgroup were pooled under mineral oil and maintained on ice. Plaque fluid was then isolated by centrifugation and analysed for organic acids and inorganic ions (ion chromatography), and pH (microelectrodes). From these data, the degree of saturation [DS(TM)] in plaque fluid with respect to tooth mineral (TM) was calculated. Before exposure to sucrose, plaque fluids from the CF and the CP subgroups had similar ionic compositions. These fluids were also found to be supersaturated with respect to tooth mineral. After exposure to sucrose, a rapid decrease in plaque fluid pH was observed, which corresponded primarily to lactic acid production. For all times examined, mean pH and DS(TM) values were lower and lactic acid concentrations were higher in the CP than the CF samples. Lower values of DS(TM) suggest that plaque fluid from CP subjects had a measurably greater cariogenic potential. Calcium concentrations also increased significantly and to comparable levels in all plaque fluid samples after sucrose exposure, despite lower acid production in CF samples.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of a resin-modified glass ionomer restorative material on artificially demineralised dentine caries in vitro.

OBJECTIVES: Recurrent caries is one of the most common reasons for the replacement of restorations. One method of reducing the frequency of this problem may be by using fluoride-releasing restorative materials. The aim of this in vitro study was to evaluate the progression of artificial lesions around resin-modified glass ionomer (Vitremer) restorations placed in root surfaces. Class V cavities were prepared on the mesial and distal surfaces of 28 human premolar teeth. Artificial carious wall lesions were created in all cavities. The root of each tooth was then hemisected through the middle of the two cavities, before being restored with either the glass ionomer or amalgam, while the opposing cavities on the same root portion were varnished as negative controls. Forty-eight specimens were pH-cycled in remineralising and demineralising solutions for 20 h and 4 h, respectively, each day for 4 weeks, whilst in a smaller control group of eight specimens, the demineralising solution was replaced with deionised water. Mineral changes in the carious lesions were evaluated using contact microradiography. RESULTS: Results showed that varying degrees of subsurface demineralisation and remineralisation were evident, with a laminated appearance in lesions adjacent to the glass ionomer. There was higher remineralisation in the glass ionomer-filled cavities compared with the amalgam-filled cavities. In the water-cycled group, glass ionomer showed an increase in mineral content (p < 0.05), while no changes were observed in the amalgam-filled cavities. CONCLUSIONS: This model has shown that glass ionomer has a greater potential than amalgam for remineralisation of artificially created wall lesions within an acidic environment.

Studies of dental root surface caries. 2: The role of cementum in root surface caries.

Artificial caries lesions were produced in roots of teeth using an acetate buffer system, when the layer of cementum was either normal in thickness, excessively thickened by hypercementosis, or had been removed completely. The rates of lesion progression were measured in each case using polarized light microscopy to measure lesion depth. Analysis of calcium (Ca) and phosphorus (P) loss during the demineralizing process was carried out. The removal of cementum was found to significantly increase the initial rate of penetration of the lesion into the root, although this rate progressively reduced to a level consistent with that found in normal roots after seven days of demineralization. The overall depth remained consistently greater than that observed in normal roots, or when lesions were produced entirely within hyperplastic cementum. Chemical analysis also showed removal of cementum resulted in an initial doubling of the Ca and P lost from the root surface. Prior direct exposure of segments of normal roots to the oral environment was found not to significantly alter the rate of artificial lesion progression, in comparison with that in the originally protected segment of the root surface. It was concluded that an intact cementum layer has the intrinsic ability to protect the underlying dentine of exposed tooth roots against acidic demineralization and that prior exposure to the oral environment does not significantly alter this ability.

Explorer probing of root caries lesions: an in vitro study.

Probing with a dental explorer is the preferred method of root caries diagnoses. However, studies suggest that use of a dental explorer in coronal caries detection may damage tooth structure. This pilot study investigated the effect of probing on remineralization of root surface lesions in vitro. Root-surface lesions were created on 10 extracted teeth by exposing them to a demineralizing solution for 21 days. One side of each lesion was then randomly selected and probed with an explorer, while the other side was not probed. The teeth then were placed in a remineralizing solution containing 10 parts per million (ppm) fluoride for 21 days. Of the 9 teeth with usable sections, all showed frank evidence of defects on the probed halves. Sites of remineralization were seen in the non-probed halves and adjacent to the probed defects, but not within or at the base of these defects. These results suggest that probing of root surfaces may create defects that do not fully remineralize.

Take two dentists: a tale of root caries.

Take two dentists, whose practices are about as different as they could possibly be, who both have a healthy respect for root caries. Our paper will start by describing these two practices and then review the literature to show what is known about the management of root caries. The paper ends by returning to the two dentists, who describe how the research reviewed in the literature may affect their work.

Remineralisation study of artificial root caries lesions after fluoride treatment. An in vitro study using electric caries monitor and transversal micro-radiography.

AIMS: To evaluate and compare remineralisation of root caries lesions after in vitro treatment with various fluoride (F) agents using an Electric Caries Monitor (ECM) and Transversal Micro-Radiography (TMR). MATERIALS: Permanent human teeth were extracted and root surface specimens were sectioned, prepared (n = 35), and randomly allocated into seven different experimental groups (groups 1-7). METHODS: Root surfaces were demineralised in an acidified gel (pH = 5.0) for 3 weeks followed by various F treatments and stored in a standardised remineralising solution at 37 degrees C for 6 weeks. The root surfaces were treated twice daily with different dentifrice slurries for 2 min, either with a neutral placebo dentifrice without F (group 5); or a neutral sodium fluoride (NaF) 1400 p.p.m. F dentifrice (group 1); or a neutral 1250 p.p.m. F dentifrice (group 6); or an acid dentifrice (pH 4.7) with 1400 p.p.m. F containing amine fluoride (AmF) (groups 3 and 4) or a 1250 p.p.m. (pH 4.7) AmF dentifrice (group 6). In groups 1, 2, 5, 6, and 7, the root surfaces were additionally rinsed for 2 min with a neutral non-F placebo solution. In groups 3 and 4, rinsing were performed for 2 min with an acid (pH 4.7) 250 p.p.m. F solution, containing 125 p.p.m. F as AmF and 125 p.p.m. F as potassium fluoride (KF), once or twice per day respectively. ECM was used to measure electrical resistance on root surfaces at baseline and after 3 and 6 weeks respectively. TMR technique was used to measure and compare root surface lesion depths and mineral loss. RESULTS: Six weeks daily treatment with a dentifrice slurry containing AmF followed by rinsing with a combination of equal amounts of AmF and KF solution twice a day showed a statistical significant higher ECM values compared with the other groups. TMR data measuring lesion depths and mineral loss reduction supported the results of the ECM findings. CONCLUSIONS: Daily application of a dentifrice slurry containing 1400 p.p.m. F as AmF combined with twice daily rinsing with a 250 p.p.m. F solution containing equal amount of AmF and KF significantly remineralise primary root caries lesions in vitro. ECM and TMR are valuable complementary methods in order to analyse the remineralisation processes.

Intra- and interexaminer variability and validity of laser fluorescence and electrical resistance readings on root surface lesions.

The purpose of this study was to investigate the validity and reproducibility of laser fluorescence and electrical resistance readings on root carious lesions. One hundred and three freshly extracted human teeth with various forms of natural root caries were investigated by 6 operators using the laser fluorescence device DIAGNOdent (DD) and the Electronic Caries Monitor (ECM III). As a reference, a caries-free root area of each tooth was also examined. Specimens were classified as to colour, surface texture and cavitation depth. Teeth were sectioned through the centre of the lesion and prepared for polarising light microscopy. Histological depth of the lesions was defined as the distance between the surface and zone of translucency. Depths ranged from 0.1 to 3.1 mm. Statistical analysis of the interexaminer reproducibility revealed a significant correlation (Kendall's W) for DD measurements of 0.85 and 0.76 for ECM readings. Moderate correlation between the histological depth and DD (r(s) = 0.45) or ECM scores (r(s) = -0.48) could be demonstrated. Electrical resistance readings revealed a positive correlation (r(s) = 0.43) with the thickness of the remaining dentine, whereas this was negative for laser fluorescence readings (r(s) = -0.43). However, scatter plots suggested that most lesions had very low resistance. This investigation suggests that laser fluorescence and electrical conductance measurements can be obtained reproducibly by different operators and correlate moderately with histological lesion depth and remaining thickness of the dentine bridge.

Comparative fluorescence spectroscopy of root caries lesions.

In this study, the light-emission properties of carious and sound root surfaces were investigated under a wide range of excitation wavelengths. Human molar teeth with exposed root surfaces containing light- and dark-discolored root caries (n = 3 of each) were selected. Emission spectra were recorded from carious and corresponding sound root surface areas from each tooth by using a fluorescence spectrophotometer at excitation wavelengths from 360 nm up to 580 nm, in steps of 20 nm. The spectra were corrected for fluctuations in detector sensitivity and excitation light intensity, and normalized to peak intensity. Excitation spectra were recorded for selected emission wavelengths that showed maximum intensity. Light- and dark-discolored root surface caries showed distinct fluorescence emission bands between 600 and 700 nm that were not present in sound root surface areas. These bands were strongest for excitation wavelengths between 390 and 420 nm. The excitation spectra of root caries revealed maximum excitation at around 405 nm, which is equivalent to the Soret band of porphyrin compounds. The emission spectra of both types of root caries lesions were shifted towards longer wavelengths (red shift at half maximum) when compared to the spectra of corresponding sound root surfaces. The red shift for dark-discolored root caries was higher than for light-discolored lesions at all excitation wavelengths.

Evaluation of a computer-based caries risk assessment program in an elderly group of individuals.

The aim of this study was to evaluate a caries risk assessment computer program, the Cariogram, by comparing the risk assessment of the program with the actual caries increment in a group of elderly individuals over a period of 5 years. The participants were examined and interviewed at baseline about their general health and dietary habits. Data on oral hygiene and use of fluoride were obtained and saliva analyses included mutans streptococci, lactobacilli, buffering capacity, and secretion rate. Based on the baseline recordings, the individuals were divided into 4 risk groups according to the Cariogram. Where the program predicted 0% 20% (high risk), 21%-40%, 41%-60%, and 61%- 100% (low/rather low risk) "chance of avoiding caries", 13, 32, 23, and 48% respectively, had no new DFS over 5 years and 18, 40, 72, and 84%, respectively, had no new lesions at the 5th year. The mean DMFS increment over 5 years was 12.8 in the high/rather high risk group (0% 40% "chance of avoiding caries"), which included 43% of the individuals. In the low/rather low risk group (61%-100% "chance of avoiding caries"), the corresponding value was 5.2%, and 21% of the participants were sorted to this group. The mean DMFS increment for the whole group of elderly individuals was 9.5. In this particular study the Cariogram was able to sort the elderly individuals into risk groups that reflected the actual caries outcome.

Effects of a supersaturated pulpal fluid on the formation of caries-like lesions on the roots of human teeth.

Root surfaces were exposed to demineralizing buffer in a continuous-flow system, with or without simultaneous perfusion of the pulp chamber with a supersaturated surrogate dentine fluid (SDF). Experimental lesions formed with perfusion of the pulp were significantly less deep than control lesions formed without perfusion, but the application of hydrostatic pressure to the SDF (15 or 30 cm water) did not produce significantly greater reductions. The lesion depth reduction was attributed to reduced undersaturation at the advancing lesion front through interdiffusion of the demineralizing buffer and the SDF. Translucent bands, resembling sclerotic dentine, were observed beneath 9 of 24 experimental lesions and 5 of 24 control lesions. Scanning electron microscopy showed that, in most of the bands beneath experimental lesions, dentinal tubules were either partly occluded by granular mineral deposits or were reduced in diameter. Thus, in vivo, dentine fluid may modify the rate of lesion progression and promote sclerosis in the underlying dentine.

Caries progression and inhibition in human and bovine root dentine in situ.

Since the use of bovine instead of human dentine to evaluate cariogenic and anticariogenic substances is not well established, this in situ study was conducted. Eleven volunteers wore palatal acrylic devices containing 4 dentine slabs (2 human and 2 bovine). Sucrose solution (20%) was dripped over all slabs 4 times a day, simulating a cariogenic challenge. Dentifrice slurries, fluoridated or not, were dripped over specified dentine slabs 3 times a day to evaluate caries reduction. After 14 days, the biofilm formed on the dentine slabs was collected for microbiological analysis. In dentine, mineral loss (DeltaZ) and lesion depth (LD) were determined by cross-sectional microhardness and by polarized light microscopy, respectively. The total streptococci and mutans streptococci counts in the biofilm formed either on human or on bovine slabs, whether treated or not with fluoride dentifrice, were not statistically different. The DeltaZ and the LD values of dentine treated with fluoride dentifrice were significantly lower than the values of dentine treated with non-fluoride dentifrice. The differences in the DeltaZ and LD values between the human and bovine dentine were not statistically significant. The results suggest that bovine dentine can be used instead of human to evaluate caries development and inhibition.

How to measure the effects of fluoride treatments in clinical trials? Assessment: modern versus traditional methods.

In recent years there has been a pronounced change in the epidemiology and disease pattern of dental caries. In the current context, traditional methods of caries assessment, discriminating lesions at cavitation, are clinically inappropriate, and obsolete for research requiring detection of a very early phase of mineral loss. Modern prospective caries studies require sensitive methods permitting the measurement of small changes in tooth mineral content, and objective, quantitative measurements of such changes are now possible in a single caries lesion. For longitudinal studies there are noninvasive methods for assessment of new lesions as well as quantitative changes (progression or regression) in existing lesions. Among as yet unresolved issues are improved methods to assess the current activity of a lesion, methods for detection and quantification of secondary caries and root caries, calibration of methodologies between different research institutes, and methods capable of assessment of the whole continuum in the development of a caries lesion, from initial loss of mineral to cavitation.

[Clinical considerations apropos of topical fluorides in the control of dental caries]. / Considérations cliniques à propos des fluorures topiques dans le contrôle de la carie dentaire.

Studies on the caries reducing effect of topical fluorides have provided a great understanding of their therapeutic role in caries control. It is believed that topically applied fluorides interfere with dental tissue demineralisation and reduce the rate of caries progression. According to this assumption, topical fluorides are recommended to both children and adults as a measure to control coronal as well as root caries. In the present review, some aspects of caries development and arrest are considered and the reasoning behind topical fluoride application is discussed. Guidelines concerning self-applied and professionally applied topical fluorides regimes according to the patient's caries risk and caries activity are presented.

Composition and flow rate of saliva and caries development in young rats following administration of lithium.

Lithium carbonate (Li2CO3), an antipsychotic medication, was investigated to determine the effects on the stimulated flow and composition of saliva and on caries development in rats. Lithium carbonate was delivered via osmotic pumps at 10, 15 and 60 mg/kg/day. All animals were infected with Streptococcus sobrinus 6715 and fed a cariogenic diet. Lithium administration exerted a caries-protective effect on sulcal surfaces, though the reduction in caries scores was statistically significant only for the groups receiving Li2CO3 at 10 and 60 mg/kg/day compared to control animals (p +/- 0.05, ANOVA). There were no detectable alterations in protein concentration, electrophoretic profiles, or flow rates of stimulated parotid and submandibular saliva associated with the decreased sulcal caries incidence. Weight gain, water consumption and the populations of total cultivable flora recovered were not influenced by the administration of lithium. Investigation into the mechanisms of the sulcal caries reduction will require further exploration of changes caused by lithium on salivary gland function.

Effect of a two-solution fluoride mouth rinse on deposition of loosely bound fluoride on sound root tissue and remineralization of root lesions in vitro.

A constant-composition fluoride (F) titration method was used to measure the amount of leachable F deposited on root surfaces in vitro by a 1-min rinse with a 12 mmol/l sodium fluoride (228 micrograms/g F) solution or a two-solution rinse that contained 2 mmol/l sodium fluorosilicate (228 micrograms/g total F ) and 10 mmol/l calcium chloride. The mean +/- standard deviations (n = 3) F uptake from the two rinse treatments were 0.70 +/- 0.24 micrograms/cm2 and 3.25 +/- 0.74 micrograms/cm2, respectively. In a separate experiment, the effects of sodium fluoride and the two-solution rinses on remineralization of root lesions were evaluated in an in vitro pH cycling model. The results showed that the average decrease in mineral loss (delta Z) in the two-solution rinse group (60%) was significantly greater than that obtained in the NaF rinse (41%) or the control (9%) group.