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Results for “Tooth Remineralization”

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PubMed1988

Effect of an anticalculus dentifrice on lesion progression under pH cycling conditions in vitro.

The aim of the present study was to examine a sodium fluoride anticalculus dentifrice product containing soluble pyrophosphate for its ability to promote remineralization and/or inhibit demineralization of dental enamel in a pH cycling model in vitro. Enamel crowns with windows were subjected to 14 days of alternating demineralization and remineralization periods at 37 degrees C. Teeth were immersed 5 min daily in one of the test dentifrice systems (1:3 slurry in deionized water) between the demineralization and remineralization cycles. Test dentifrices included (1) sodium fluoride (NaF; 1,100 ppm F)/silica abrasive (Crest) and (2) NaF (1,100 ppm F) with 3.3% soluble pyrophosphate/silica abrasive (Crest Tartar Control). Controls included a placebo dentifrice (silica abrasive) with no added fluoride and a group which received no treatment at all, i.e., demineralization/remineralization only. Overall, both of the NaF dentifrices were very effective in limiting in vitro caries progression and were not significantly different from each other. Inclusion of pyrophosphate in the NaF dentifrice did not affect the net outcome of the cycling demineralization/remineralization processes which is in agreement with recent clinical and in situ studies of these products.

Dental Calculus↗

PubMed2006

In vitro quantitative light-induced fluorescence to measure changes in enamel mineralization.

A sensitive, quantitative method for investigating changes in enamel mineralization of specimens subjected to in vitro or in situ experimentation is presented. The fluorescence-detecting instrument integrates a Xenon arc light source and an object positioning stage, which makes it particularly suitable for the nondestructive assessment of demineralized or remineralized enamel. We demonstrate the ability of in vitro quantitative light-induced fluorescence (QLF) to quantify changes in mineralization of bovine enamel discs that had been exposed in vitro to a demineralizing gel (n=36) or biofilm-mediated demineralization challenges (n=10), or were carried in situ by three volunteers during a 10-day experiment (n=12). Further experiments show the technique's value for monitoring the extent of remineralization in 36 specimens exposed in vitro to oral multispecies biofilms and document the repeatability of in vitro QLF measurements (n=10) under standardized assay conditions. The validity of the method is illustrated by comparison with transversal microradiography (TMR), the invasive current gold standard for assessing experimental changes in enamel mineralization. Ten discs with 22 measurement areas for comparison demonstrated a positive correlation between TMR and QLF (r=0.82). Filling a technological gap, this QLF system is a promising tool to assay in vitro nondestructively localized changes in mineralization of enamel specimens.

Analysis of Variance↗

PubMed1986

Intraoral effects of a fluoride-releasing device on acid-softened enamel.

Among the anticaries benefits of fluorides is the remineralization of incipient carious lesions. There is increasingly convincing evidence that low-potency fluoride agents applied frequently are effective in remineralizing early carious lesions. This study of in vivo remineralization used an intraoral appliance with demineralized enamel slabs mounted in the appliance and an innovative method of fluoride delivery, the fluoride-releasing device, which releases a controlled amount of fluoride (0.3 mg fluoride every 24 hours) on exposure to saliva. After control and treatment periods of 7 and 30 days, the enamel specimens were removed from the appliance and evaluated for microhardness, acid resistance, and fluoride uptake. The treated specimens significantly exceeded the values of their corresponding controls in all parameters measured, indicating that considerable remineralization of the treated enamel had occurred at both 7 and 30 days. Although the longer period of treatment produced greater results, considerable effects were observed after 7 days. This model system provided for an in vivo environment to study the effects of treatment of the FRD and allowed for subsequent recovery of the enamel specimens for evaluation. The results of this study are encouraging with respect to the efficacy of a fluoride-releasing device but indicate that subsequent clinical testing of the effects of FRDs on incipient carious lesions in the natural dentition of human subjects is necessary.

Adult↗

PubMedDate not supplied

Dental composites based on hybrid and surface-modified amorphous calcium phosphates.

The objectives of this study were to prepare hybrid and surface-modified amorphous calcium phosphates (ACPs) as fillers for mineral-releasing dental composites, and determine whether the mechanical strength of the composites could be improved without decreasing their remineralization potential. ACP was hybridized with tetraethoxysilane or zirconyl chloride and surface-treated with 3-methacryloxypropoxytrimethoxy silane (MPTMS) or zirconyl dimethacrylate (ZrDMA). Composites fabricated with unmodified ACP (u-ACP), hybrid or surface-modified ACP filler and photo-activated Bis-GMA, TEGDMA and 2-hydroxyethyl methacrylate (HEMA) (BTH resin), Bis-GMA, TEGDMA, HEMA and MPTMS (BTHS resin) or Bis-GMA, TEGDMA, HEMA and ZrDMA (BTHZ resin) were tested for their remineralizing potential and biaxial flexure strength (BFS). Ion releases from all composites were significantly above the minimum necessary for reprecipitation of apatite. The BFS of unfilled polymers was not adversely affected by immersion in saline solutions. The BFS of BTH and BTHS composites deteriorated upon soaking. However, BTHZ composites were practically unaffected by exposure to saline solutions. Filler hybridization resulted in a modest, but significant, improvement in the BFS (up to 24%) of BTHZ composites. Heterogeneous distribution of the ACP on disk surfaces was detected by the FTIR microspectroscopy analyses. This might have been caused by uncontrolled aggregation of ACP particles that appeared to hinder interfacial filler/resin interactions and diminish the mechanical strength of composites.

Animals↗

PubMed2006

The evidence supporting alternative management strategies for early occlusal caries and suspected occlusal dentinal caries.

OBJECTIVE: To assess the strength of the evidence describing the effectiveness of alternative strategies to the detection and management of early occlusal caries and suspected occlusal dentinal caries. METHODS: Nine detection and intervention decision points were identified as being central to the management of early occlusal caries and suspected occlusal dentinal caries, or suspicious areas. For each decision point, the evidence for effectiveness was assessed, using existing systematic reviews when available, and nonsystematic review methods when necessary. RESULTS: For the 2 detection decisions (early occlusal caries and suspicious areas) the strength of the evidence was weak. Accuracy in detecting early occlusal caries was extremely variable within and across detection methods. Approximately 50% of suspicious areas identified had dentinal caries. The strength of the evidence for effectiveness of nonsurgical approaches for the management of early occlusal caries was weak for all 3 management strategies examined (doing nothing, sealants, remineralization). This evidence suggested that sealants were highly effective, with remineralization reflecting moderate effectiveness. For the management of suspicious areas, the strength of the evidence was still weaker and reflected the same relative effectiveness. For the surgical management strategy for suspicious areas, operative treatment, the evidence was strong and reflected high effectiveness for preventive resin restorations, but no evidence was available for minimally invasive techniques. CONCLUSION: Identification methods for early occlusal caries are not accurate. The strength of the evidence for effectiveness of nonsurgical management strategies for early occlusal caries is at best, weak. The available evidence suggests that sealing both enamel caries and suspected occlusal dentinal caries is the most effective management approach if subsequent maintenance of the sealed surfaces can be assured.

Adolescent↗

PubMed1997

Review on fluoride, with special emphasis on calcium fluoride mechanisms in caries prevention.

Low concentrations of fluoride have a beneficial effect on enamel and dentin de- and remineralization. After fluoride treatments, such as topical applications, rinses or dentifrices, salivary fluoride concentrations decrease exponentially in a biphasic manner to very low concentrations within a few hours. For treatments to be effective over periods longer than the brushing and the following salivary clearance, fluoride needs to be deposited and slowly released. Calcium fluoride (or like) deposits act in such a way, owing to a surface covering of phosphate and/or proteins, which makes the CaF2 less soluble under in vivo conditions than in a pure form in inorganic solutions. Moreover, due to the phosphate groups on the surface of the calcium fluoride globules, fluoride is assumed to be released with decreasing pH when the phosphate groups are protonated in the dental plaque.

Calcium Fluoride↗

PubMed2004

Mineralization of dentin induced by treatment with bioactive glass S53P4 in vitro.

Dentin hypersensitivity can be managed to occlude dentin tubules, but none of the agents used are components of natural dentin. Using a calcium phosphate precipitation (CPP) method, dentin tubules can be occluded with a calcium phosphate (CaP) layer similar to the major inorganic component of dentin. The CPP method utilizes acidic pH conditions, such as etching of dentin, over the course of several dental treatments. A gentler method can be used to produce a CaP layer on the surface of dentin. By treating with bioactive glass S53P4 (BAG), or regular commercial glass (CG), mineralization occurs in physiologically neutral solutions such as simulated body fluid (SBF) and remineralization solution (RMS). After a short period of immersion, silica is dissolved from both types of glass, but the amount of silica released is much greater from BAG than from CG. The dissolved silica is adsorbed on the surface of dentin during the pretreatment procedure and enhances the mineralization of dentin in SBF. After 14 days' mineralization the dentin is fully covered by the CaP layer, but after 14 days' immersion in RMS decalcification of the dentin occurs. Pretreatment with BAG decreases the degree of decalcification of dentin during the mineralization process. These findings suggest that bioactive glass S53P4 can be used as a therapeutic material for mineralization of dentin and its tubules in a physiological environment.

Adsorption↗

PubMed2006

In vitro microhardness studies on a new anti-erosion desensitizing toothpaste.

OBJECTIVE: To evaluate in vitro the efficacy of a new anti-erosion desensitizing toothpaste to inhibit enamel surface softening by a dietary acid, and promote re-hardening of artificial erosive lesions. METHODOLOGY: The ability of the toothpaste to inhibit formation and promote repair of erosive lesions in human enamel has been investigated. In an enamel surface softening study, sound human enamel was pre-treated with one of four toothpaste slurries for two minutes, before exposure to 1.0% citric acid, pH 3.8, for a total of 30 minutes. The surface microhardness (SMH) of the specimens was determined at baseline and at 10-minute intervals using a Struers Duramin-1 microindentor. In an enamel re-hardening study, the erosive lesions were prepared by exposure of the specimens to 1.0% citric acid, pH 3.8, for 30 minutes. After two minutes treatment with a toothpaste slurry, lesion repair was monitored by SMH after 4, 24, and 48 hours incubation in artificial saliva. This remineralizing phase was modified by the addition of an aliquot of the relevant toothpaste slurry, to mimic in vivo carryover of the formulation. RESULTS: The new test formulation, Elmex Sensitive, and Colgate Sensitive exhibited statistically significant inhibition of citric acid-mediated enamel surface softening versus a fluoride-free placebo at all time points. The test toothpaste gave statistically superior protection against the erosive challenge compared to Elmex Sensitive and Colgate Sensitive after 20- and 30-minute exposures. In the remineralization studies, erosive lesions treated with the test toothpaste exhibited statistically superior re-hardening versus lesions treated with Elmex Sensitive and Colgate Sensitive after 24- and 48-hour incubation in the artificial saliva. Lesions treated with Elmex Sensitive re-hardened to a statistically significant extent versus the fluoride-free placebo toothpaste. A re-hardening study, in which a series of the new toothpaste-base formulations containing increasing concentrations of NaF were evaluated, showed a clear fluoride dose response. CONCLUSION: The present microhardness studies show that treatment with fluoride-containing toothpastes helps protect sound enamel from acid-mediated surface softening, and promotes re-hardening of erosive lesions. The new test toothpaste exhibited statistically superior efficacy to Elmex Sensitive and Colgate Sensitive in both in vitro models.

Analysis of Variance↗

PubMed2004

Analysis of clinical trials involving non-cavitated caries lesions.

Treatments to halt or reverse the progression of non-cavitated caries lesions are of increasing interest. Diagnostic technologies under development offer potential for the assessment of gradual progression and regression of such lesions. Many therapies directed at correcting demineralization-remineralization imbalance should, in principle, protect enamel similarly across lesion severities from initiation to near cavitation. If this is so, and if acceptable reproducibility and predictive validity can be demonstrated for a diagnostic of acceptable cost, then clinical trials of agents to prevent cavitation can become more efficient by the use of outcome indices that reflect, in addition to cavitation, the expansion and regression of non-cavitated lesions. However, to achieve such a benefit will require data analyses that fully exploit ordinal or continuous-scale outcome measures. We consider comparison of such measures of lesion status between treatment groups, with most attention to ordinal categorical data. Interim data from a clinical trial in Lithuanian children are used for illustration.

Cariostatic Agents↗

PubMed1989

Electron probe micro-analysis for subsurface demineralization and remineralization of dental enamel.

A quantitative study of fluoride distribution profile changes in dental enamel was conducted by means of electron probe micro-analysis (EPMA). Fluoride-deposited hydroxyapatite powders were chosen as fluoride standards, and analytical conditions were optimized. The lower limit of detection for fluoride was estimated to be 270 ppm, with an accelerating voltage of 5 kV, a specimen current of 40 nA, and a counting time of 40 seconds. Fluoride profiles in fluoride-treated dental enamel, which exhibited intact surface layers and subsurface demineralization, were determined. The results were also compared with those of an acid-abrasion method, and reasonable consistency was found between these two methods, although the acid-abrasion procedure yielded a slightly lower fluoride content in the initial layers, followed by a higher content of fluoride in the deeper layers. The precision of fluoride profile data obtained from EPMA permits further studies to be conducted on the kinetics of subsurface demineralization and intact surface layer formation ("white spot" formation) which is observed during the acid challenge of dental enamel.

Animals↗

PubMed2002

Influence of cementum on the demineralization and remineralization processes of root surface caries in vitro.

The influence of the nature of the root surface on the demineralization and remineralization processes within artificial fluoride-treated caries lesions was investigated using microscopic and X-ray microanalytical methods. Traces of fluoride were detected in the outer parts (about 25 micrometers) of the lesions after the application of fluorides, and a high mineral content was proved for the same region by means of microanalytical calcium estimation. The location of this mineral-rich band in relation to the root surface was deeper into the root depending on the existence and thickness of a cementum layer. However, within the dentine the location and intensity of the mineral content were unaffected by the cementum. Investigation of artificial caries lesions without fluoride treatment showed the following: The degree of mineralization was kept at a higher level near the root surface in the presence of cementum. Consequently, a cementum layer gives some initial caries resistance of the root surface.

Amines↗

PubMed1992

An in situ enamel section model for assessment of enamel re/demineralization potential.

An enamel-section-carrying intra-oral appliance to predict the results of double-blind anti-caries studies has been developed. Initial validation was against the F concentration effect attained in a clinical trial where three sodium monofluorophosphate (SMFP) dentifrices were used. Original appliance-based work showed significant differences in remineralization between non-F and F dentifrices, but not between different F dentifrices. However, it was shown later that acidified gel-prepared lesions were not as responsive as solution-prepared lesions to de- and remineralizing processes, and lesion remineralization rates were found to be dependent on initial lesion size. An in situ cross-over study was then repeated with use of acid-solution-created lesions, and seven volunteers completed the project. Each brushed twice daily x 2 min with either 0, 1000, or 2500 ppm F, as SMFP dentifrice. After a two-week wash-out, subjects wore the appliances for four weeks. Enamel mineral content was assessed at 0, two, and four weeks via microradiography/microdensitometry, and a statistically significant dose-response was obtained between non-F and F as well as between 1000 and 2500 ppm F pastes, i.e., as per the three-year clinical trial data. Hence, the model's suitability for pre-clinical screening was confirmed. It has also been used in caries microbiological studies, in root caries investigations, and currently in chewing gum cariogenicity experiments.

Dental Enamel↗

PubMed1992

Importance of model parameters in the assessment of intra-oral remineralization.

Since the introduction of the Intra-oral Cariogenicity Test by Koulourides et al. (1974), many groups around the world have been developing and using intra-oral models to test new caries-preventive products, as well as to study physiological processes in the oral cavity. In spite of the large numbers of papers reporting these methods, very little research has been done to determine the importance of the many variable parameters which influence the performance of these models. Among these, the following can be identified: (a) panelist criteria, (b) the use of sound vs. pre-demineralized enamel of human or bovine origin, (c) the use of gauze or a recess to accumulate plaque, (d) the method to create incipient lesions, (e) the duration of the experiment, (f) the number of panelists required for statistical significance to be obtained, (g) the assessment techniques for mineral and/or fluoride uptake/loss, and (h) the choice of contralateral, 'cross-over', or 'monadic' experimental designs. Our results, supported by data from the literature, indicate that the choices made with respect to these parameters are of paramount importance in determination of the outcome of the respective study.

Dental Caries↗

PubMed1996

Ontario dentists' knowledge and beliefs about selected aspects of diagnosis, prevention and restorative dentistry.

Based on the responses of 1,276 general dental practitioners in Ontario to a mail questionnaire, variations in certain aspects of the dentists' diagnostic, preventive and restorative knowledge and beliefs are examined. Despite recent practice recommendations and guidelines indicating that patient need and service selectivity, rather than traditional, routine prescriptions, should be the guiding principle of practice, many dentists seem to follow tradition in defining optimal intervals for dental examinations and prophylaxes, bitewing radiographs and topical fluoride applications. Although the respondents' knowledge and beliefs were correct and consistent with current evidence in many areas, some large deficiencies were identified. These include: a lack of awareness that professional prophylaxis prior to topical fluoride application is usually unnecessary and that sealant applications to certain teeth are not cost-effective; an over-estimation of the speed at which dental caries progress through the enamel; and, despite good knowledge about the opportunities for the remineralization of enamel lesions with fluorides, a tendency to restore enamel caries. In some instances, practitioner beliefs were shown to influence practice. For example, dentists who knew about the slow progression of approximal surface caries also reported more often that bitewing intervals should be longer, and that the placement of a restoration should be delayed until the caries penetrates the dentin. Similarly, correct knowledge about sealant effectiveness was positively associated with high sealant use. If dentists are to be expected to understand and follow emerging diagnostic, preventive and restorative practice recommendations and guidelines, continuing education is required to correct and update some of their knowledge and beliefs, as displayed in the responses to this questionnaire.

Adolescent↗

PubMed1994

In vitro demineralization-remineralization of enamel caries at restoration margins utilizing fluoride-releasing composite resin.

The release of fluoride from a composite resin has been shown to inhibit enamel demineralization. The purpose of this study was to examine the remineralization effects of a fluoride-releasing resin. Twenty extracted molars were painted with an acid-protective varnish, excluding a 2 x 6-mm window. Artificial carieslike lesions were created in the exposed enamel with an acidified gel. A Class II preparation was restored with a fluoride-releasing or a non-fluoride-releasing composite resin. The teeth were sectioned longitudinally and photographed with polarized light microscopy in water and Thoulet's imbibition media. The sections were then painted with an acid-protective varnish, so that only the natural external surface of the lesion was exposed, and placed in separate closed environments of a nonfluoridated artificial saliva. Sections were removed after 2 weeks and 3 months and photographed under polarized light as before. A sonic digitizer was used to measure the area of the body of the lesion. Results demonstrated a statistically significant area reduction in the body of the lesions exposed to the fluoridated composite resin at 2-week and 3-month intervals.

Acrylic Resins↗

PubMed1997

Major topics in quantitative microradiography of enamel and dentin: R parameter, mineral distribution visualization, and hyper-remineralization.

Three aspects of quantitative transverse microradiography are described and discussed: (1) the average mineral loss parameter of enamel or dentin lesions (R) in vol%; (2) mineral distribution visualization of lesions by means of a computer-assisted videodensitometric (CAV) method; and (3) the microradiography of hyper-remineralized lesions. "R", defined as the average amount of mineral lost (or gained) in a lesion per unit lesion length, is a useful parameter in dental caries. The results show that, in vitro, R is about constant over the demineralization period for enamel and dentin. This was found even for quite different dissolution kinetics. R is strongly reduced by the presence of small amounts of fluoride in the demineralizing system. R of dentin lesions is smaller than for enamel lesions. We conclude that the mineral loss value (delta Z) and the lesion depth (ld) are in general dependent parameters during in vitro or in situ studies on enamel or dentin. During lesion formation, mineral loss from the lesion and acid penetration in the tissue are obviously linked. This is possible only if the mineral content in the lesion does not change very much after passage of the lesion front. The CAV method presented is illustrated for enamel lesions formed in vitro and in situ.

Absorptiometry, Photon↗

PubMed1995

The application of in vitro models to research on demineralization and remineralization of the teeth.

Progress in in vivo and in situ experimentation has led many researchers to speculate as to the relevance and importance of in vitro testing protocols in caries research. A Medline/Biosis search for the present review revealed well over 300 citations (since 1989) documenting in vitro tests associated with caries research on mineralization and fluoride reactivity. The present survey documents these recent applications of in vitro test methods in both mechanistic and 'profile' caries research. In mechanistic studies, in vitro protocols over the past five years have made possible detailed studies of dynamics occurring in mineral loss and gain from dental tissues and the reaction dynamics associated with fluoride anticaries activity. Similarly, in profile applications, in vitro protocols make possible the inexpensive and rapid--yet sensitive--assessment of F anticaries efficacy within fluoride-active systems, and these tests represent a key component of product activity confirmation. The ability to carry out single variable experiments under highly controlled conditions remains a key advantage in in vitro experimentation, and will likely drive even further utilization, as advances continue in physical-chemical and analytical techniques for substrate analysis in these protocols. Despite their advantages in vitro testing protocols have significant limitations, most particularly related to their inability to simulate the complex biological processes involved in caries.

Animals↗

PubMed1998

Caries development from 11 to 22 years of age: a prospective radiographic study. Prevalence and distribution.

The aim was to assess the distribution and pattern of caries development longitudinally in teenagers and adolescents whose treatment had been based on remineralizing rather than restorative strategies. A baseline cohort of 536 children was studied, using bite-wing radiographs, from 11 to 22 years of age. The results showed a slow but continuous increase in both enamel and dentin caries of approximal surfaces. At 21, 29% of all posterior approximal surfaces had enamel caries according to the radiographic diagnoses, 14% had dentin caries and another 5% were restored. At the age of 20 21, the skewed distribution of DMFS(appr) apparent at 12 and 15 had given way to a more uniform picture and the percentage of individuals with no decayed approximal surfaces (DMFS(appr) = 0) decreased from 71 at 12-13 to 28 at 20-21 years of age. The proportion of DFS(occl) in relation to all DFS decreased from 83% at 12 to 52% at 21. The occlusal, mesial and distal surfaces of the first molar accounted for 60% of all restored surfaces at 21.

Adolescent↗