Caries-like Lesions Research Articles

Evaluation of the effectiveness of low power diode laser with different wavelengths in dental caries prevention

Objectives: To investigate the effectiveness of low power diode lasers, with different wavelengths and different irradiation times in caries prevention an ex vivo study. Materials and Methods: True experimental posttest design on 130 extracted human premolar teeth by measuring caries-like lesions examined by polarized light electron microscope after irradiation by four low power diode lasers 532 nm (4 mW), 671 nm (100 mW), 675 nm (30 mW), and 810 nm (20 mW). A fifth group was added as a control (without irradiation). The specimens were prepared by coating the teeth with acid resistance nail varnish leaving uncovered 2 mm × 2 mm of the enamel surface mesially or distally below the contact area. For each wavelength, samples were divided into three groups for three irradiation time as 4, 8, and 12 min; each group consisted of 10 teeth. Irradiated samples and the control were immersed in lactic acid (4.8 pH) and incubated for 21 days under controlled temperature of 37°C and controlled PH of 4.8. After the incubation period, the teeth were sectioned longitudinally by dissecting the 2 × 2 enamel window and the depth of the lesion was measured microscopically. ANOVA test was used to compare between different wavelengths and different irradiation times with level of significant set at P ≤ 0.05. Results: The depth of the caries-like lesions in 810 nm and 675 nm was more than that in control group (180 μm), while statistical significant difference was found (P = 0.002); when the 671 nm and 532 nm lasers wavelengths revealed depth of 70 μm and 112 μm, respectively. Increasing irradiation time decreases the depth of caries-like lesions. Conclusion: Diode laser of wavelengths 532nm and 671 nm showed less depth than control group, indicating caries prevention effect. Increasing irradiation time to a certain value increases resistance to acid dissolution.

Effect of casein phosphopeptide-amorphous calcium phosphate (cpp-acp) on caries-like lesions in terms of time and nano-hardness: An in vitro study.

Time bound increase in the nanohardness of the enamel after remineralization with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) in a regular interval of 1 h has not been explored in the literature to a greater extent. To determine and compare the maximum hardness of the remineralized caries-like lesions, in terms of nanohardness and the rate of achieving maximum hardness at 1-h interval, after treatment with artificial saliva and CPP-ACP, over 12 h. Fifty longitudinal sections of extracted sound permanent maxillary central, lateral incisors were immersed in demineralizing solution for 4 days. The samples were then randomly divided into three groups, consisting of 12 sections each for soaking them in three different media-isotonic saline, artificial saliva, and CPP-ACP for 12 h. The nanohardness was measured on the labial surface, at baseline, after erosion, and after remineralization at 1-h interval. The data was analyzed with paired t-test, one-way analysis of variance (ANOVA) and post-hoc analysis. CPP-ACP increased the enamel hardness significantly (P < 0.001), at an increased rate, than artificial saliva. This study has provided an insight into the frequency of use of CPP-ACP, once per day, as the nanohardness of enamel samples increased within 1 h of application and remained within the normal limits after 12 h.

Comparative assessment of bond strengths of affected dentin, using two different remineralizing solutions with or without lasers: Results of an in vitro pilot study

Aims: Assessing remineralization and bond strengths of remineralizing agents with or without LASERS. Settings and Design: In vitro pilot study. Materials and Methods: Artificial caries-like lesion was created with 10% citric acid in 50 non carious extracted posterior teeth which were divided into six groups according to treatment: GC Tooth Mousse and Toothmin cream with or without LASER, positive and negative control. Remineralization was done for 5 min every day for 7 days. Microhardness test was repeated. Pulsed Nd:YAG Laser (1.064 cm wavelength) was used with a focused beam at 1W and 15 Hz for 10 s on exposed dentin surface. Samples were etched with etching gel for 15 s and rinsed with water for 30 s. Bonding composite restoration of 4 mm height was done with Mylar Strip. Tensile bond strength was calculated. Statistical Analysis: Student's paired t- test evaluated difference between mean values of microhardness. Student's unpaired t -test evaluated the difference between mean values of bond strengths between groups. Results: Significant difference in microhardness in HV (50 g load) was seen in all groups ( P P = 0.0021). Conclusions: Toothmin and GC Mousse with or without LASER were found to be effective in increasing mineralization. Bond strength of Toothmin with LASER treatment was higher compared to others.

Effect of epigallocatechin-3-gallate application for remaining carious dentin disinfection.

Context:Epigallocatechin-3-gallate (EGCG) is a flavonoid extracted from green tea that demonstrated antimicrobial activity.Aims:To evaluate the efficacy of EGCG 0.5%, 1%, and 2% concentrations as an antimicrobial solution in dentin caries-like lesions induced in a bacterial-based in vitro model.Materials and Methods:Twenty-five human dentin specimens were submitted to a microbial-based caries model by immersion in brain heart infusion (BHI) broth inoculated with Streptococcus mutans UA159, for 5 days. After the demineralization period, the specimens were randomly divided into groups: Group I: 0.9% saline solution; Group II: 2% chlorhexidine digluconate; Group III: 0.5% EGCG; Group IV: 1% EGCG; and Group V: 2% EGCG. After the treatments, carious dentin samples were harvested from dentin specimens and analyzed by colony-forming unit (CFU) counts. Data were analyzed by ANOVA and Tukey's test.Results:Log reduction values (SD, CFU.mg-1) for Groups I–V were: 5.02 (0.16), 3.96 (0.43), 4.74 (0.26), 4.89 (0.56), and 4.91 (0.40), respectively. There was no statistical difference between the EGCG concentrations and saline solution (P > 0.05). Furthermore, there was no statistical difference between EGCG concentrations (P > 0.05). However, there was a statistically significant difference between the chlorhexidine digluconate group and the other groups (P < 0.05).Conclusion:EGCG at the studied concentrations were not effective in eliminating S. mutans from dentin caries-like lesions.

Polarized light microscopic evaluation of remineralization by casein phosphopeptide-amorphous calcium phosphate paste of artificial caries-like lesion: An in vitro study

Introduction: Dental caries was considered to be an irreversible disease, but this concept of caries is changing because of the availability of many newer products for its treatment. One of such product is casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). Aim: The present in vitro study was aimed to evaluate remineralization of artificial caries-like lesion by topical application of CPP-ACP paste. Materials and Methods: In this study, 40 caries-free premolar and molar teeth requiring extraction for orthodontic reasons and impactions were used. Artificial caries-like lesion was produced on sound enamel surface by immersing the samples in demineralizing solution for 96 h. Longitudinal sections were made through the white spot lesion with hard tissue microtome and were subjected to polarized light microscopic evaluation. The sections were divided into CPP-ACP group (Group I), positive control (Group II), and negative control (Group II). The Group I and Group II samples were subjected to 10 days of pH cycling, and all the samples were evaluated by polarized light microscopy. The lesion depth was calculated, and all the data was subjected to statistical analysis. Results: CPP-ACP group showed 27.306% decrease in lesion depth after 10 days of pH cycling. Conclusion: Based on the findings of this study, it can be concluded that the CPP-ACP paste can cause remineralization of white spot lesion and can be prescribed as topical application paste for the treatment of initial caries lesions.

Resin infiltration into differentially extended experimental carious lesions.

Resin infiltration of initial caries lesions is a novel method of caries therapy. However, it has some limitations. Therefore, further experimental studies are needed to improve resin infiltration. It was the aim of this investigation to study resin infiltra-tion into different experimental carious lesions. Caries-free extracted human molars and premolars were demineralized for 3, 6, 9 and 12 days and infiltrated with resin. Prior to infiltration, the teeth were incubated with sodium fluorescein. After em-bedding, serial sections were cut through the experimental lesions, and the penetration of the resin was measured with fluo-rescence microscopy. Two infiltrated teeth from each time interval were not embedded and cut. Infiltration of the resin was then studied with EDS element analysis. The results showed that with increasing demineralization time, the lesion expansion was also increasing, and the resin infiltration was always almost complete. From these results it can be concluded that artifi-cial standardized caries-like lesions are suitable for experimental studies of resin infiltration.

Effect of Er:YAG laser on enamel demineralization around restorations

This study evaluates in situ the effect of erbium-doped yttrium aluminum garnet (Er:YAG) laser parameters on the development of caries-like lesions adjacent to dental restorations. One hundred fifty bovine enamel slabs were randomly allocated among 15 volunteers. The specimens were subdivided into ten groups: nine experimental groups prepared with Er:YAG laser (300 mJ output, frequency of 2, 4 or 6 Hz, water flow rate of 2.0, 5.0, or 8.0 mL/min) and one control group (high-speed handpiece). The prepared cavity was restored with a composite resin, and the slabs were mounted on palatal appliance to be installed in the volunteers to the cariogenic challenge. After this, the specimens were sectioned to the longitudinal microhardness measurements. Data were submitted to Friedman and Wilcoxon paired tests. All groups prepared with Er:YAG laser demonstrated microhardness values higher than those prepared with high-speed handpiece, which showed the lowest microhardness values (24.86). The group prepared with Er:YAG laser (2 Hz-2.0 mL/min) showed the highest microhardness values (152.43), followed by those prepared with Er:YAG laser (2 Hz-5.0 mL/min) (133.08) and Er:YAG laser (2 Hz-8.0 mL/min) (91.61), respectively. The groups Er:YAG laser with 4 and 6 Hz of frequency and water flow rates of 2.0, 5.0, and 8.0 mL/min showed microhardness values lower than the groups cited above and showed statistical similarity among them. The Er:YAG laser parameters employed to cavity preparation influenced the acid resistance of the irradiated substrate, and the Er:YAG laser was capable to control the development of caries-like lesions around composite resin restorations.

In vitro Remineralizing Effect of Fluoride Varnishes Containing Sodium Trimetaphosphate

This study analyzed the effects of fluoride varnishes supplemented with sodium trimetaphosphate (TMP) on the remineralization of caries-like lesions in vitro. Bovine enamel discs were selected through surface hardness (SH) and caries-like lesions were induced. SH was again determined and the blocks were divided into 7 experimental groups (n = 24/group): placebo (no fluoride or TMP), 5% TMP, 2.5% NaF, 2.5% NaF/5% TMP, 5% NaF, 5% NaF/5% TMP and commercial formulation (Duraphat™, 5% NaF), following a blind protocol. Discs were treated with the varnishes and kept in a remineralizing solution for 4 h and a demineralizing solution for 2 h. Varnishes were then removed and half of the discs were used for analysis of loosely (CaF₂) and firmly bound fluoride. The remaining discs were submitted to a pH-cycling regimen for 6 days. The percentage of surface hardness recovery (%SHR), cross-sectional hardness (ΔKHN) and enamel CaF₂ and fluoride were determined. Data were analyzed by ANOVA and by Student-Newman-Keuls' test (p < 0.05). A dose-response relationship was observed between fluoride concentrations in the varnishes and %SHR. The 5% TMP varnish led to %SHR similar to that obtained for the placebo. When TMP was used in association with fluoride, however, significantly higher %SHR were observed in comparison with their counterparts without TMP. Moreover, ΔKHN obtained for the 5% NaF/5% TMP was significantly lower among all groups tested. Higher concentrations of CaF₂ and fluoride were observed for Duraphat and 5% NaF, followed by 5% NaF/5% TMP, 2.5% NaF and 2.5% NaF/5% TMP (p < 0.05). It was concluded that the supplementation of fluoride varnishes with TMP leads to enhanced remineralizing effect of artificial caries lesions in vitro.

Effect of acidulated phosphate fluoride – gel and foam – on enamel caries-like lesion of primary teeth: an in vitro study

The purpose of this study was to evaluate in vitro the effect of APF, gel and foam, for 1 to 4 minutes, on artificial enamel caries-like lesion of primary teeth submitted to the pH cycling. The specimens with medium values of initial superficial enamel micro-hardness between 272 and 331KHN were selected for the formation of the artificial caries lesion. Later, they were randomly divided into 6 groups (n=15): no pH cycling control, cycled control, gel 1min, gel 4min, foam 1min and foam 4min.The no pH cycling control group was maintained in an humid environment, while the application of APF and the pH cycling were accomplished. After, the specimens were sectioned at the center for the enamel cross-sectional micro-hardness test. The values of micro-hardness of the depths from 20 to 180mm were converted into percentile of mineral volume (%Vol) and the area of mineral recovery (∆ZR) was calculated. In spite of there is no statistically significant differences, it was observed through the analysis of the ∆ZR a difference in the values for the groups gel 1min and foam 4min (p&gt;0.05). The evaluation of %Vol indicated a significant difference only at 60mm depth (p=0.005). This study concluded that a single application of APF gel or foam, for 1 or 4 minutes, do not remineralize artificial enamel caries-like lesion of primary teeth

Molecular and Structural Evaluation of Dentin Caries-Like Lesions Produced by Different Artificial Models

This study evaluated structural and molecular issues of dentin caries-like lesions produced by different artificial models (ACL) compared with natural caries lesions (NCL). One hundred twenty-four sound occlusal dentin blocks and 47 carious blocks were obtained and surface hardness was analyzed (SH1). They were assigned to groups according to ACL: GB: Biological; GC: Chemical; GIS: In situ; GNC: natural caries (control). Blocks from groups 1, 2 and 3 were submitted to caries lesion induction. NCL and ACL blocks were submitted to surface hardness (SH 2), FT-Raman and µEDXRF analysis. All blocks were longitudinally sectioned and one of the halves was submitted to cross-sectional hardness (CSH) and the other to SEM analysis. SH1 and SH2 data were submitted to t test (unpaired and paired, respectively), CSH and SEM data to two-way and one-way ANOVA respectively, and Tukey and t tests, respectively (p<0.05). Data from FT-Raman/µEDXRF were submitted to one-way ANOVA and Dunnett multiple-comparisons test (a=0.05). GB and GNC showed lowest SH2 values that were significantly different from GC and GIS. Regarding CSH, GB and GNC showed no significant difference between them. SEM showed similar caries lesion depth for GB and GNC, being significantly higher than for GC and GIS. µEDXRF showed similar values of calcium and phosphate for GB and GNC; GNC values were significantly different from GIS. No significant difference was found among the groups concerning phosphate, carbonate and CH bonds values. For collagen type I, GC values were significantly different compared to other groups. It may be concluded that caries-like lesions produced by GB were the closest model to NCL.

The effect of ozone on progression or regression of artificial caries-like enamel lesions in vitro

ObjectiveThis study investigated the effect of ozone on the progression or regression of artificial caries-like lesions on enamel following pH cycling conditions in vitro. MethodsA randomized, single blind, four legs design was used. 20 full thickness enamel slabs were allocated to each of the four groups which were: Fluoride free toothpaste (control); ozone alone; Reductant/Patient Kit alone and a combination of both ozone/Reductant/Patient Kit. Artificial lesions were created and subjected to the pH cycling regime for a 14 days period. Assessments were carried out before and after the pH cycling on the slabs using the microhardness testing and Quantitative Light-induced Fluorescence (QLF). ResultsStatistical significant difference were found in the percentage change of enamel microhardness before and after pH cycling between ozone/Reductant/Patient Kit group and all the other three groups of the study, as well as between Reductant/Patient Kit group and control. There was a statistical significant difference in the change of size and severity of the lesion (ΔQ) between all the three regimes tested and the control with a trend favouring ozone/Reductant/Patient Kit group. ConclusionsIn our model, it appeared that ozone treatment alone is not effective in protecting the enamel against demineralisation or promoting remineralisation, unless combined with the Reductant/Patient Kit, which contain high levels of fluoride.

Cerium Chloride Reduces Enamel Lesion Initiation and Progression in vitro

Aim: Determination of the potential of cerium chloride to reduce artificial carious mineral loss and lesion depth progression. Methods: A total of 160 enamel samples were prepared from 40 bovine lower central incisors. Crowns were sectioned into four pieces, embedded in acrylic resin, ground flat and allocated to eight groups (S1-S4 and D1-D4; n = 20). Specimens of groups D1-D4 were stored (for 7 days) in a demineralizing buffer solution to induce caries-like lesions. Afterwards, samples were treated for 30 s with one of the following solutions: placebo (S1 and D1), amine fluoride (S2 and D2), cerium chloride (S3 and D3) and a combination of fluoride and cerium chloride (S4 and D4). After another 7 (D1-D4) or 14 (S1-S4) days in demineralizing buffer solution, integrated mineral loss and lesion depth were determined by transversal microradiography and compared by Scheffé's post hoc tests. Results: In groups S1-S4, the highest values for integrated mineral loss and lesion depth were observed for group S1 (placebo), the lowest values for group S4. The results in groups S2-S4 were not significantly different. In groups D1-D4, the highest values for integrated mineral loss and lesion depth were observed for group D1 (placebo), the lowest values in groups D3 and D4. In group D2, integrated mineral loss and lesion depth were significantly lower as compared to D1, but significantly higher compared to groups D3 and D4. Conclusion: Cerium chloride and its combination with fluoride are able to significantly reduce carious mineral loss and the progression of lesion depth.

Prosthodontic rehabilitation of a patient diagnosed with multiple idiopathic root resorption

A female college student was referred by her general dentist for evaluation of the interproximal caries-like lesions discovered during her biannual visit. The lesions were determined to result from external resorption of unknown origin. After the most affected teeth had been extracted and the other teeth were restored after periodontal surgery, an interim partial removable dental prosthesis was placed. Two months later, the resorption pattern had proliferated to the rest of her dentition, thus revising the treatment plan to involve full mouth extractions and to place immediate maxillary and mandibular complete removable dental prostheses. Subsequently, 6 titanium dental implants were placed in each arch, and, after healing, opposing metal ceramic screw-retained fixed dental prostheses were inserted.

Biomimetic remineralization of dentin

ObjectivesRemineralization of demineralized dentin is important for improving dentin bonding stability and controlling primary and secondary caries. Nevertheless, conventional dentin remineralization strategy is not suitable for remineralizing completely demineralized dentin within hybrid layers created by etch-and-rinse and moderately aggressive self-etch adhesive systems, or the superficial part of a caries-affected dentin lesion left behind after minimally invasive caries removal. Biomimetic remineralization represents a different approach to this problem by attempting to backfill the demineralized dentin collagen with liquid-like amorphous calcium phosphate nanoprecursor particles that are stabilized by biomimetic analogs of noncollagenous proteins. MethodsThis paper reviewed the changing concepts in calcium phosphate mineralization of fibrillar collagen, including the recently discovered, non-classical particle-based crystallization concept, formation of polymer-induced liquid-precursors (PILP), experimental collagen models for mineralization, and the need for using phosphate-containing biomimetic analogs for biomimetic mineralization of collagen. Published work on the remineralization of resin–dentin bonds and artificial caries-like lesions by various research groups was then reviewed. Finally, the problems and progress associated with the translation of a scientifically sound concept into a clinically applicable approach are discussed. Results and significanceThe particle-based biomimetic remineralization strategy based on the PILP process demonstrates great potential in remineralizing faulty hybrid layers or caries-like dentin. Based on this concept, research in the development of more clinically feasible dentin remineralization strategy, such as incorporating poly(anionic) acid-stabilized amorphous calcium phosphate nanoprecursor-containing mesoporous silica nanofillers in dentin adhesives, may provide a promising strategy for increasing of the durability of resin–dentin bonding and remineralizing caries-affected dentin.

Summary of: Treatment of early caries lesions using biomimetic self-assembling peptides – a clinical safety trial

Objective We previously reported that a rationally designed biomimetic self-assembling peptide, P11-4, nucleated hydroxyapatite de novo and was apparently capable of in situ enamel regeneration following infiltration into caries-like lesions. Our present aim was to determine the safety and potential clinical efficacy of a single application of P11-4 on early enamel lesions. Materials and methods Fifteen healthy adults with Class V 'white spot' lesions received a single application of P11-4. Adverse events and lesion appearances were recorded over 180 days. Results Patients treated with P11-4 experienced a total of 11 adverse events during the study, of which two were possibly related to the protocol. Efficacy evaluation suggested that treatment with P11-4 significantly decreased lesion size (p = 0.02) after 30 days and shifted the apparent progression of the lesions from 'arrested/progressing' to 'remineralising' (p <0.001). A highly significant improvement in the global impression of change was recorded at day 30 compared with baseline (p <0.001). Conclusions The results suggest that treatment of early caries lesions with P11-4 is safe, and that a single application is associated with significant enamel regeneration, presumably by promoting mineral deposition within the subsurface tissue.

Remineralization of Artificial Enamel Lesions by Theobromine

Objective: This study investigated the remineralization potential of theobromine in comparison to a standard NaF dentifrice. Methods: Three tooth blocks were produced from each of 30 teeth. Caries-like lesion was created on each block using acidified gel. A smaller block was cut from each block for baseline scanning electron microscopy imaging and electron-dispersive spectroscopy (EDS) analysis for surface Ca level. A tooth slice was cut from each lesion-bearing block for transverse microradiography (TMR) quantification of baseline mineral loss (Δz) and lesion depth (LD). Then baseline surface microhardness (SMH) of each lesion was measured. The three blocks from each tooth were assigned to three remineralizing agents: (1) artificial saliva; (2) artificial saliva with theobromine (0.0011 mol/l), and (3) NaF toothpaste slurry (0.0789 mol/l F). Remineralization was conducted using a pH cycling model with storage in artificial saliva. After a 28-day cycle, samples were analyzed using EDS, TMR, and SMH. Intragroup comparison of pre- and posttest data was performed using t tests (p < 0.05). Intergroup comparisons were performed by post hoc multistep comparisons (Tukey). Results: SMH indicated significant (p < 0.01) remineralization only with theobromine (38 ± 32%) and toothpaste (29 ± 16%). With TMR (Δz/lD), theobromine and toothpaste exhibited significantly (p < 0.01) higher mineral gain relative to artificial saliva. With SMH and TMR, remineralization produced by theobromine and toothpaste was not significantly different. With EDS, calcium deposition was significant in all groups, but not significantly different among the groups (theobromine 13 ± 8%, toothpaste 10 ± 5%, and artificial saliva 6 ± 8%). Conclusion: The present study demonstrated that theobromine in an apatite-forming medium can enhance the remineralization potential of the medium.

Influence of photo-activation source on enamel demineralization around restorative materials

This study evaluated the effects of the photoactivation source and restorative material on the development of caries-like lesions on human enamel after an in vitro pH challenge. Enamel cavities were prepared in 36 blocks, which were assigned to two groups according to the restorative material: resin-modified glass ionomer (RMGI) and composite resin (CR). Samples were exposed to quartz-tungsten-halogen lamp, argon-ion laser, or light-emitting diode (n = 6). The Knoop microhardness (KHN) values of the top surface of all materials were evaluated. Restored enamel blocks were thermocycled and subjected to 10 demineralization-remineralization cycles at 37°C. KHN analysis of the superficial enamel was performed by four indentations located 100 μm from the restoration margin. The material KHN was not affected by the photoactivation source. No significant difference in KHN was noted between CR and RMGI. The enamel surface around RMGI exhibited a higher KHN (272.8 KHN) than the enamel around CR (93.3 KHN), regardless of the photoactivation source. Enamel demineralization around the dental restoration was not influenced by the photoactivation source. Less enamel demineralization was observed around the RMGI than around the CR restoration.

Influence of Laser Irradiation on Pits and Fissures: AnIn SituStudy

The aim of this in situ study was to analyze the influence of the Er:YAG, Nd:YAG, and CO(2) lasers on the enamel acid resistance of pits and fissures. The laser tissue interaction has been studied as a method of preventing occlusal caries. Thirteen volunteers wore palatal acrylic appliances containing human occlusal enamel blocks that were divided into four groups (G1, control; G2, Er:YAG; G3, Nd:YAG; G4, CO(2)). Each palatal acrylic appliance was used in the four studied groups and was used for 14 consecutive days. A sucrose solution was applied to the specimens six times per day. The specimens were then sectioned in half, and a microhardness test was applied. The other halves were analyzed using polarized light microscopy to measure the caries-like lesion areas, and a morphological analysis was conducted using a scanning electron microscope (SEM). For the statistical analysis of the data obtained from the microhardness test (Knoop hardness number. [KHN]) (α=5%), Fisher's exact test was performed, and the group means were as follows: G1, 247±71; G2, 258±70; G3, 272±73; and G4, 298±56. The results demonstrated that the control group was significantly different from G3 and G4, which presented higher microhardness values. The Wilcoxon signed-rank test was used to analyze the data obtained from the caries-lesion area measurements (mm(2)) (α=5%) (G1, 0.01±1.08; G2, 0.13±0.18; G3, 0.05±0.17; and G4, 0.09±0.22). The results no showed significant differences among the groups in this analysis. Based on the results from the present study, it may be concluded that the CO(2) and Nd:YAG lasers increased the enamel acid resistance in pits and fissures.

In vitro remineralization of enamel subsurface lesions and assessment of dentine tubule occlusion from NaF dentifrices with and without calcium

Currently, fluoride is the most effective preventive treatment for remineralization of incipient carious lesions and dentinal hypersensitivity due to wasting disorders. The products containing fluoride, calcium and phosphate are also claim to remineralize early, non-cavitated enamel demineralization. The aim of this study was to investigate and compare the efficacy of two such products, Tooth Mousse and Clinpro tooth crème on remineralization and tubule occluding ability with 5000ppm fluoride-containing toothpaste. Thirty third molar teeth were placed in demineralizing solution for 5 days such that only a window of 1mm x 5mm was exposed to the environment to produce artificial caries-like lesions and randomly assigned to three groups: Group I, 5000ppm sodium fluoride; Group II, GC MI paste plus and Group III, Clinpro tooth crème. Axial longitudinal sections of 140-160 μm of each tooth which included the artificial carious lesion taken and were photographed under polarized light microscope. The demineralized areas were then quantified with a computerized imaging system. The experimental materials were applied onto the tooth sections as a topical coating and subjected to pH-cycling for 28 days. To evaluate tubule occlusion ability, thirty dentin specimens of 2mm thickness were obtained from cervical third of sound third molars. Specimens were ultrasonicated and etched with 6% citric acid for 2 minutes to simulate the hypersensitive dentin. Specimens were randomly divided into above mentioned three groups (n=10). The test agents were brushed over the specimens with an electric toothbrush, prepared and observed under Scanning Electron Microscope for calculation of the percentage of occluded tubules. Group I showed a significantly greater percentage of remineralization than Group III and Group II. Comparison of the remineralization potential between group II and group III were not significant.In case of dentine hypersensitivity, Group I and group III showed greater percentage of tubule occlusion ability than Group II. Intergroup comparison of the tubule occlusion potential of group I and group III were not significant. Within the limitations of our study, sodium fluoride showed relatively greatest remineralizing and dentinal tubule occlusion property when compared with GC MI paste plus and Clinpro tooth crème.

Subablative Er:YAG Laser Effect on Enamel Demineralization

Objectives: To characterize the cariostatic potential of a low-energy Er:YAG laser treatment. Methods: Twelve sound premolars were selected. Two 2 × 1 mm windows were created on each tooth and randomly assigned to L₁ and L₂ groups. Three sites in each window were chosen with the middle site as the control and the left and right ones receiving Er:YAG laser treatment of 5.1 J/cm² (L₁) or 2.0 J/cm² (L₂), respectively. The teeth were further subjected to 4-day pH cycling to create caries-like lesions. After mineral quantification using a micro-computed tomography scanner, the preventive effects (ΔML = mineral loss of the control area minus that of the lased area) of L₁ and L₂ treatments were calculated based on the difference in the gray value of the control and lased sites. Results: Significant inhibitory effects of L₁ and L₂ on enamel demineralization were demonstrated (both p ≤ 0.001), with the L₁ treatment having a greater effect (45.2%) than the L₂ treatment (25.2%, p = 0.004). Conclusions: Subablative low-energy Er:YAG laser irradiation can significantly prevent enamel demineralization potentially through the retardation of enamel diffusion. This study confirmed that high-energy laser treatment, which may damage the peripheral and underlying tissues, may not be needed for caries prevention.