Lesion Depth Values Research Articles

Lacticaseibacillus rhamnosus inhibits the development of dental caries in rat caries model and in vitro

ObjectivesDental caries result from a microbial imbalance in the oral cavity. Probiotics ecologically modulate the oral microflora to prevent caries. This study evaluated the anti-cariogenic effects of two Lacticaseibacillus rhamnosus strains in vitro and in vivo to provide a more theoretical basis for its clinical applications in caries prevention. MethodsIn the study, cariogenic biofilms were grown with L. rhamnosus (LGG) or L. rhamnosus ATCC 7469 and analyzed. Quantitative real-time PCR (qPCR), Scanning Electron Microscope (SEM), and Confocal laser scanning microscope (CLSM) were used to detect the changes in the composition and architectures; cariogenic activity was measured by the lactic acid production and Transverse Microradiography (TMR). The effects of LGG on the 12 Sprague-Dawley rat caries model were assessed using Keyes scores and micro-CT analysis. Oral microbiome changes were evaluated through 16S rRNA gene high-throughput sequencing. ResultsL. rhamnosus can reduce cariogenic bacteria in biofilm by 14.7 % to 48.9 %, with LGG exhibiting more potent inhibitory effects. Both strains of L. rhamnosus can adhere to the surface of biofilms, reduce the extracellular polysaccharides (EPS) matrix, and loosen the biofilm structure. L. rhamnosus inhibited cariogenic activity by reducing the lactic acid production in biofilms. The bovine enamel blocks presented lower mineral loss values and lesion depth values in the group Core+L.rh and Core+LGG. LGG-ingested rats had significantly lower levels of moderate dentin lesions and higher mineral density than the control group. The 16 s rRNA gene sequencing revealed that LGG regulated the beta diversity of the oral microbial community in the rat dental caries model. ConclusionsThis study revealed the promising potential of L. rhamnosus, especially the LGG strain, in the ecological prevention of dental caries. Clinical SignificanceProbiotics may provide a strategy for preventing caries by regulating the oral microecological balance. The study revealed the promising anti-caries potential of the LGG probiotic strain in vivo and in vitro. It is expected that LGG could be used as an oral probiotic for the clinical prevention and treatment of caries.

Evaluation of Resin Infiltration, Fluoride and the Biomimetic Mineralization of CPP-ACP in Protecting Enamel after Orthodontic Inter-Proximal Enamel Reduction

This study investigated the effect of using different agents for protecting enamel proximal surfaces against acidic attack after interproximal reduction (IPR) using the trans micro radiography technique. Seventy-five sound-proximal surfaces were obtained from extracted premolars for orthodontic reasons. All teeth were measured miso-distally and mounted before being stripped. The proximal surfaces of all teeth were hand stripped with single-sided diamond strips (OrthoTechnology, West Columbia, SC, USA) followed by polishing via Sof-Lex polishing strips (3M, Maplewood, MN, USA). Three-hundred micrometers of enamel thickness was reduced from each proximal surface. The teeth were randomly divided into 5 groups: group 1 (control un-demineralized) received no treatment, group 2 (control demineralized) had their surfaces demineralized after the IPR procedure, group 3 (fluoride) specimens were treated with fluoride gel (NUPRO, DENTSPLY, Charlotte, NC, USA) after the IPR, group 4 (Icon) resin infiltration material (Icon Proximal Mini Kit, DMG, Bielefeld, Germany) was applied after IPR, group 5 (MI varnish) specimens were treated with Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) containing varnish (MI Varnish, G.C, USA, St. Alsip, IL, USA) after the IPR. The specimens in (groups 2-5) were stored in a 4.5 pH demineralization solution for 4 days. The trans-micro-radiography (TMR) technique was conducted to evaluate the mineral loss (∆Z) and lesion depth of all specimens after the acid challenge. The obtained results were analyzed statistically using a one-way ANOVA at a significance level of α = 0.05. The MI varnish recorded significant ∆Z and lesion depth values compared to the other groups p > 0.05. There was no significant difference in ∆Z and lesion depth between the control demineralized, Icon, and fluoride groups p < 0.05. The MI varnish increased the enamel resistance to acidic attack, and thus can be considered an agent capable of protecting the proximal enamel surface after IPR.

In vitro comparison of the erosive potential of four different wines on human dental enamel

Background/Aim: This study aimed to investigate the erosive potential of wines derived from Anatolia on human teeth in vitro. Material and Methods: In this study two red (Öküzgözü, Boğazkere) and two white (Sultaniye, Narince) wines, citric acid and distilled water were used to investigate erosive effects. The pH, titratable acidity, iron and calcium ion levels of the groups were measured. Each group included 10 specimen and they were exposed to 25 ml of wine sample for 5 seconds, artificial saliva for 10 seconds for 10 times. The initial and the final phosphate concentrations were measured by the UV spectrophotometer and the difference between the measurements was calculated. One sample was examined under a scanning electron microscope and the data were analyzed statistically using One-way ANOVA and Pearson correlation test. Results: Mineral loss and erosive lesion depth values were ranged from highest to the lowest Sultaniye, Boğazkere, Öküzgözü and Narince, respectively. Correlation between mineral loss and pH was statistically significant (p&lt;0.01). However, there was no correlation between the iron and calcium ion level and mineral loss. Conclusions: All the investigated wines have pH values below the critical value for enamel dissolution while Sultaniye was significantly more erosive than the others. There is a negative correlation between pH and erosive potential of the wine. Within the limits of this in vitro study, it can be expected that a regular consumption of wines might cause dental erosion.

Effect of silver diammine fluoride and glass ionomer on remineralisation of natural dentine caries

ObjectivesSilver diammine fluoride (SDF) is a caries-arresting agent for dentine lesions. This study investigated the effect of application frequency of SDF when used with glass ionomer cement (GI) for remineralising carious dentine. MethodsFreshly extracted human posterior teeth with advanced caries were used. After superficial removal of infected dentine, single (G3), double (G4), triple (G5) applications of SDF (Advantage Arrest SDF 38 %) followed by a layer of GI (GC Fuji IX GP) were compared to no treatment (negative control-G2), and GI only (G1). All teeth were stored in artificial saliva between treatments and for 2-weeks after final treatment. Micro-computed X-ray tomography (NSI) scans were obtained at each stage and analysed to plot mineral density-depth profile, lesion depth (LD) and mineral loss (ΔZ). Data was statistically analysed at a significance level of 0.05. ResultsMean LD values were 837 μm, 735 μm, 841 μm, 1008 μm, 707 μm at baseline and 785 μm, 727 μm, 712 μm, 855 μm, 639 μm after treatment for groups G1 to G5, respectively. Mean ΔZ values were 6327 vol%μm, 5995 vol%μm, 10014 vol%μm, 7192 vol%μm, 5649 vol%μm at baseline and 3686 vol%μm, 5126 vol%μm, 5539 vol%μm, 2327 vol%μm, 3218 vol%μm after treatment for groups G1 to G5, respectively. Paired t-test showed that LD and ΔZ changed significantly within all groups from baseline to treatment weeks following storage (p < 0.05) except LD in the control (p > 0.05). ANCOVA showed significant difference among groups in net lesion depth recovery and net mineral gain (p < 0.05), and G3 and G4 showed the highest mineral gains. ConclusionOne or two applications of SDF prior to placement of GI, were effective in remineralising advanced dentine lesions, while additional applications, when combined with GI, did not demonstrate additional benefit in this study. Clinical significanceThis short-term laboratory research study showed that one or two applications of SDF followed by GI coverage could remineralise advanced dentine caries in the presence of artificial saliva. This procedure carries potential in the treatment of difficult lesions where conventional restorations would require significant tooth structure removal through traumatic procedures.

REMINERALIZATION EFFECT OF EGG SHELL POWDER AND NOVAMINE ON INITIAL CARIES-LIKE LESIONS IN YOUNG PERMANENT TEETH (IN-VITRO STUDY)

Introduction: Despite the cariostatic effect of fluoride, the continuous use of fluoridated toothpastes increases the risk of dental fluorosis. Therefore, new safe alternative technologies of teeth remineralization must be introduced to arrest dental caries and remineralize the early enamel carious lesions. Objectives: The aim of the study was to evaluate the remineralizing effect of eggshell powder and novamine on initial caries-like lesions in young permanent teeth compared to fluoride. Material and Methods: A total of 96 permanent teeth were selected. Each Tooth was coated with nail varnish, leaving squares of 4x4 mm. Each tooth was sectioned into 2 halves longitudinally in a buccolingual direction through the center of the window to obtain a mesial and a distal half (192 specimens). One half was treated and the other half was remained untreated to serve as its negative control. Teeth were assigned into three groups according to treatment agent; group I (eggshell powder solution), group II (novamine toothpaste) and group III (fluoride toothpaste) .Specimens were immersed in the demineralizing solution for 72 hours to produce artificial carious lesions on the exposed enamel surface. Results: There was a statistically significant mean microhardness and lesion depth values between test subgroups IA (eggshell powder), IIA (novamine) and their controls (P 0.001). There was statistically significant difference in mean percent difference values of enamel microhardness among three groups (P 0.001). Conclusions: Both eggshell powder and novamine were effective for remineralization of initial caries-like lesions of young permanent teeth.

Effectiveness of Theobromine on Enamel Remineralization: A Comparative In-vitro Study

BackgroundRemineralizing agents demonstrate potential to reverse early carious lesions. Theobromine containing dentifrices claim to remineralize enamel lesions effectively. The aim of this in-vitro study was to evaluate and compare the remineralization potential of dentifrices containing theobromine, 0.21% sodium fluoride (NaF) with functionalized tricalcium phosphate (f-TCP) and amine fluoride on artificial enamel caries.Materials and methodsSound extracted human premolars were demineralized to produce deep artificial carious lesions. The teeth were sectioned longitudinally and allocated to three treatment groups with nine specimens in each group: Group A (NaF + f-TCP), Group B (amine fluoride), and Group C (theobromine). The specimens were then subjected to pH cycling for seven days. Confocal laser scanning microscopy (CLSM) was utilized to record the patterns of demineralization and remineralization. One-way ANOVA and paired t-test were used to analyze changes in lesion depth. The level of significance was set at p<0.05.ResultsAll three dentifrices effectively remineralized artificial carious lesions (paired t-test, p<0.001). Of the groups, Group A (54.97%) reported the highest percentage change in lesion depth values followed closely by Group B (51.51%) and Group C (31.71%), respectively.ConclusionWithin this in-vitro study, theobromine containing dentifrice was effective in remineralizing lesions of enamel. However, theobromine demonstrated less remineralization potential in comparison to dentifrices containing NaF + f-(TCP) and amine fluoride.

In situ Effect of Arginine-Containing Dentifrice on Plaque Composition and on Enamel Demineralization under Distinct Cariogenic Conditions

There is limited evidence that arginine-containing fluoridated dentifrices (AFD) have a better anticaries effect than regular fluoridated dentifrices (FD), especially in subjects at a higher risk for caries development. This study aimed to assess the effect of AFD on enamel demineralization and on the microbial and biochemical compositions of biofilm formed under different frequencies of sucrose exposure. It consisted of an in situ split-mouth design, where 12 adult volunteers who used FD for at least 2 months prior to the beginning of this study wore acrylic palatal appliances containing 4 bovine enamel specimens (1 pair at each side of the appliance) during 2 phases of 14 days each. FD slurry (3×/day) and 20% sucrose solution (4× and 8×/day) were dripped on the specimens during the first experimental phase. The same volunteers then used AFD during a 2-month washout period, followed by a second experimental phase where the AFD slurry and sucrose solution were applied onto a new subset of specimens. The percentage of enamel surface hardness loss (%SHL), the lesion depth (LD), the integrated mineral loss (IML), microbial counts on biofilms, the biomass, and inorganic and insoluble extracellular polysaccharide (IEPS) biofilm concentrations were determined. Higher %SHL, biomass, and IEPS and lower fluoride values were found at sucrose 8×/day exposure. Lower IEPS were found in the presence of AFD compared to FD. Similar %SHL, LD, and IML values were found between FD and AFD, irrespectively of the cariogenic challenge. The results suggest that AFD have an anticaries effect similar to that of regular FD.

Effect of fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate on the acid resistance of the primary enamel.

BackgroundThis study aimed to investigate the effects of a fluoride varnish with added Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) treatments on acid resistance of primary teeth enamel.MethodsEnamel specimens obtained from 40 primary incisors (for surface microhardness testing) and 40 primary molars (for demineralization depth measurement) were randomly divided into four groups (n = 10 incisors and 10 molars) each according to surface treatment: no treatment (control), MI varnish (1–8 % sodium fluoride and 1–5 % CPP-ACP), Clinpro White (1–5 % sodium fluoride and <5 % modified tricalcium phosphate), Duraphat (<5 % sodium fluoride). Specimens were stored for 24 h in a moist environment. After varnish residues were removed, specimens were subjected to pH cycling. The effects of fluoride varnishes were evaluated according to surface microhardness, lesion depth and structural changes. Results were analyzed by ANOVA and Tukey’s tests.ResultsThe lowest changes in surface microhardness and lesion depth occurred in MI varnish group, followed by the Clinpro White, Duraphat and no treatment (control) group (for percentage of loss surface microhardness −20.80, −34.60, −57.80 and −73.40; for lesion depth values 23.60 μm ± 3.36, 29.85 μm ± 3.27, 40.37 μm ± 3.41 and 54.56 μm ± 4.16, respectively). Statistically significant differences in both surface microhardness and lesion depth were observed among all groups (P < 0.05).ConclusionsWithin the limitations of this in vitro study, fluoride varnish containing CPP-ACP was more effective in increasing the acid resistance of primary enamel than other fluoride varnishes. However, further clinical research is needed to confirm these in vitro results.

Correction to: Effects of Different Combinations of Er:YAG Laser-Adhesives on Enamel Demineralization and Bracket Bond Strength. Photomed Laser Surg 2016;34:164–170; DOI: 10.1089/pho.2015.4041

The purpose of this study was to investigate the demineralization around brackets and shear bond strength (SBS) of brackets bonded to Er:YAG laser irradiated enamel at different power settings with various adhesive systems combinations. A total of 108 premolar teeth were used for SBS testing and an additional 54 teeth were used to evaluate demineralization. Teeth were assigned into three groups according to the etching procedure, then each group divided into three subgroups based on the application of different adhesive systems. There were a total of nine groups as follows: Group 1: Acid + Transbond XT Primer; group 2: Er:YAG (100 mJ, 10 Hz) etching + Transbond XT Primer; group 3: Er:YAG (200 mJ, 10 Hz) etching + Transbond XT Primer; group 4: Transbond Plus self-etching primer (SEP); group 5: Er:YAG (100 mJ, 10 Hz) etching + Transbond Plus SEP; group 6: Er:YAG (200 mJ, 10 Hz) etching + Transbond Plus SEP; group 7: Clearfil Protect Bond; group 8: Er:YAG (100 mJ, 10 Hz) etching + Clearfil Protect Bond; group 9: Er:YAG (200 mJ, 10 Hz) etching + Clearfil Protect Bond. Brackets were bonded with Transbond XT Adhesive Paste in all groups. Teeth to be evaluated for demineralization and SBS were exposed to pH and thermal cyclings, respectively. Then, demineralization samples were scanned with micro-CT to determine lesion depth values. For SBS test, a universal testing machine was used and adhesive remnant index was scored after debonding. Data were analyzed statistically. No significant differences were found among the lesion depth values of the various groups, except for G7 and G8, in which the lowest values were recorded. The lowest SBS values were in G7, whereas the highest were in G9. The differences between the other groups were not significant. Er:YAG laser did not have a positive effect on prevention of enamel demineralization. When two step self-etch adhesive is preferred for bonding brackets, laser etching at 1 W (100 mJ, 10 Hz) is suggested to improve SBS of brackets. The authors regret this error.

Effects of Different Combinations of Er:YAG Laser-Adhesives on Enamel Demineralization and Bracket Bond Strength.

The purpose of this study was to investigate the demineralization around brackets and shear bond strength (SBS) of brackets bonded to Er:YAG laser-irradiated enamel at different power settings with various adhesive systems combinations. A total of 108 premolar teeth were used in this study. Teeth were assigned into three groups according to the etching procedure, then each group divided into three subgroups based on the application of different adhesive systems. There were a total of nine groups as follows. Group 1: Acid + Transbond XT Primer; group 2: Er:YAG (100 mJ, 10 Hz) etching + Transbond XT Primer; group 3: Er:YAG (200 mJ, 10 Hz) etching + Transbond XT Primer; group 4: Transbond Plus self-etching primer (SEP); group 5: Er:YAG (100 mJ, 10 Hz) etching + Transbond Plus SEP; group 6: Er:YAG (200 mJ, 10 Hz) etching + Transbond Plus SEP; group 7: Clearfil Protect Bond; group 8: Er:YAG (100 mJ, 10 Hz) etching + Clearfil Protect Bond; group 9: Er:YAG (200 mJ, 10 Hz) etching + Clearfil Protect Bond. Brackets were bonded with Transbond XT Adhesive Paste in all groups. Teeth to be evaluated for demineralization and SBS were exposed to pH and thermal cyclings, respectively. Then, demineralization samples were scanned with micro-CT to determine lesion depth values. For SBS test, a universal testing machine was used and adhesive remnant was index scored after debonding. Data were analyzed statistically. No significant differences were found among the lesion depth values of the various groups, except for G7 and G8, in which the lowest values were recorded. The lowest SBS values were in G7, whereas the highest were in G9. The differences between the other groups were not significant. Er:YAG laser did not have a positive effect on prevention of enamel demineralization. When two step self-etch adhesive is preferred for bonding brackets, laser etching at 1 W (100 mJ, 10 Hz) is suggested to improve SBS of brackets.

Comparative Analysis of Different Methods of Modeling the Thermal Effect of Circulating Blood Flow During RF Cardiac Ablation.

Our aim was to compare the different methods of modeling the effect of circulating blood flow on the thermal lesion dimensions created by radio frequency (RF) cardiac ablation and on the maximum blood temperature. Computational models were built to study the temperature distributions and lesion dimensions created by a nonirrigated electrode by two RF energy delivery protocols (constant voltage and constant temperature) under high and low blood flow conditions. Four methods of modeling the effect of circulating blood flow on lesion dimensions and temperature distribution were compared. Three of them considered convective coefficients at the electrode-blood and tissue-blood interfaces to model blood flow: 1) without including blood as a part of the domain; 2) constant electrical conductivity of blood; and 3) temperature-dependent electrical conductivity of blood (+2%/°C). Method 4) included blood motion and was considered to be a reference method for comparison purposes. Only Method 4 provided a realistic blood temperature distribution. The other three methods predicted lesion depth values similar to those of the reference method (differences smaller than 1 mm), regardless of ablation mode and blood flow conditions. Considering the aspects of lesion size and maximum temperature reached in blood and tissue, Method 2 seems to be the most suitable alternative to Method 4 in order to reduce the computational complexity. Our findings could have an important implication in future studies of RF cardiac ablation, in particular, in choosing the most suitable method to model the thermal effect of circulating blood.

Application of an active attachment model as a high-throughput demineralization biofilm model

ObjectivesTo investigate the potential of an active attachment biofilm model as a high-throughput demineralization biofilm model for the evaluation of caries-preventive agents. MethodsStreptococcus mutans UA159 biofilms were grown on bovine dentine discs in a high-throughput active attachment model. Biofilms were first formed in a medium with high buffer capacity for 24h and then subjected to various photodynamic therapies (PACT) using the combination of Light Emitting Diodes (LEDs, Biotable®) and Photogem®. Viability of the biofilms was evaluated by plate counts. To investigate treatment effects on dentine lesion formation, the treated biofilms were grown in a medium with low buffer capacity for an additional 24h. Integrated mineral loss (IML) and lesion depth (LD) were assessed by transversal microradiography. Calcium release in the biofilm medium was measured by atomic absorption spectroscopy. ResultsCompared to the water treated control group, significant reduction in viability of S. mutans biofilms was observed when the combination of LEDs and Photogem® was applied. LEDs or Photogem® only did not result in biofilm viability changes. Similar outcomes were also found for dentine lesion formation. Significant lower IML and LD values were only found in the group subjected to the combined treatment of LEDs and Photogem®. There was a good correlation between the calcium release data and the IML or LD values. ConclusionsThe high-throughput active attachment biofilm model is applicable for evaluating novel caries-preventive agents on both biofilm and demineralization inhibition. PACT had a killing effect on 24h S. mutans biofilms and could inhibit the demineralization process.

Effects of CPP-ACP with sodium fluoride on inhibition of bovine enamel demineralization: A quantitative assessment using micro-computed tomography

ObjectivesThe present study evaluated the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and CPP-ACP with 900ppm fluoride (CPP-ACPF) pastes on inhibition of enamel demineralization over time, using polychromatic micro-computed tomography (micro-CT). MethodsEnamel blocks were prepared from bovine teeth. The specimens were each treated by one of the following agents, 30min daily for 7 days: deionized water (negative control); CPP-ACP paste; CPP-ACPF paste; and NaF solutions (positive controls) (90, 900, and 9000ppm F). After treatment, the specimens were immersed in a demineralizing solution (pH 4.5) for 24, 72, and 120h. Mean mineral loss (ML) and lesion depth (LD) after each period were determined from mineral density profiles obtained using micro-CT. ResultsML values in all the treatment groups were significantly smaller than those in the control group after 72 and 120h of demineralization (p<0.05, two-way ANOVA and t-test with Bonferroni correction). ML values in CPP-ACPF and NaF solution groups were significantly smaller compared to CPP-ACP group after 72h (p<0.05). LD values in the CPP-ACPF and all the NaF solutions groups were significantly smaller compared to the control group after 120h (p<0.05). The 9000ppm F group showed the lowest nominal ML and LD values. ConclusionsThe application of CPP-ACP or CPP-ACPF pastes to sound enamel surfaces resulted in inhibition of enamel demineralization, and a better effect was noted for the latter paste. Quantitative assessment using polychromatic micro-CT demonstrated to be useful for detecting mineral density changes.

In vitro evaluation of fluoride products in the development of carious lesions in deciduous teeth

The purpose of this study was to evaluate the effect of the application of fluoride products on the development of enamel caries in deciduous teeth. A total of 108 deciduous teeth were chosen for the study. Acid-resistant varnish was applied on the teeth, leaving only one area of 5 mm x 1 mm of dental enamel exposed. The teeth were allocated randomly to one of the following groups: 1) control - toothpaste without fluoride; 2) 1.23% fluoride gel; 3) Duraflur fluoride varnish; 4) Duraphat fluoride varnish; 5) Fluorniz fluoride varnish; 6) Fluorphat fluoride varnish; 7) varnish with Duofluorid; 8) 12% silver fluoride diamine (Cariestop); 9) children's fluoride toothpaste (500 ppm). The tested products were applied on the teeth according to the manufacturer's recommendations and the teeth were stored in a moist environment for 24 hours. Each group of teeth was then subjected to a pH cycling model for 14 days, after which the teeth were cut through the center for an analysis of the depth of the carious lesion by polarized light microscopy. Comparisons were made between the treatments and the control group. The mean lesion depth values were 318 microm +/- 39 (control), 213 microm +/- 27 (fluoride gel), 203 microm +/- 34 (Duraflur), 133 microm +/- 25 (Duraphat), 207 microm +/- 27 (Fluor-niz), 212 microm +/- 27 (Fluorphat), 210 +/- 28 (Duofluorid), 146 +/- 31 (Cariestop) and 228 +/- 24 (fluoride toothpaste). None of the products used here was able to completely prevent the formation of lesions. The highest cariostatic effect was achieved by fluoride varnish Duraphat and the lowest by the fluoride toothpaste.

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 (ΔZ) 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 ΔZ 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 ΔZ 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.

In vitro Remineralization of in vivo and in vitro Formed Enamel Lesions

Thin sections of natural white spot enamel lesions (WS) and of artificial in vitro lesions (VL) were remineralized simultaneously in vitro. The sections, clamped in a PMMA holder, were microradiographed at baseline and after remineralization in a calcium– and phosphate–containing solution (pH = 7.0; 1 ppm F) after 2 and 4 weeks. All data were analyzed with respect to baseline. The results show that the lesion depth values did not change significantly during 2 and 4 weeks of remineralization. The mineral accumulation (change in ΔZ), however, was substantial and significant in WS and VL. In WS the change in mineral accumulation was roughly proportional to the amount of mineral at baseline. The WS accumulated more than two times the amount of mineral than VL in the same periods of remineralization. After 4 weeks of remineralization the maximum mineral value V_max in the surface layer of the WS was nearly up to the sound enamel level ≈87 vol%. This study shows that the technique and calculation procedure described make this single section method attractive for longitudinal demineralization–remineralization studies in vitro or in situ. Both WS and VL samples obviously remineralized in vitro similarly with respect to the baseline. Furthermore, this in vitro work indicates that remineralization inhibitors present in saliva, and previously penetrated into the enamel tissue, do not influence remineralization later on.

Secondary caries in dentine around composites: a wavelength-independent microradiographical study.

Composite restorations are prone to develop secondary caries if a gap exists between tissue and restoration. The aim of this article was to quantify the effects of a fluoridating and non-F composite on secondary dentine caries in vitro as a function of time. The mineral loss in dentine was assessed in an artificial gap of 200 microns width at the composite/dentine interface; the samples were demineralised in a carboxymethylcellulose gel (pH = 5, 37 degrees C) for 8 weeks. Once a week the mineral content of the samples was determined using non-destructive wavelength-independent microradiography (WIM). After 8 weeks transversal microradiography (TMR) was done on the samples to investigate the mineral distribution of the dentine lesions. The WIM results show that the fluoride-releasing composite decreased the dentine demineralisation statistically significantly with respect of the non-F control by approximately 45%. The mineral loss values are found to be strictly proportional to time; the demineralisation reduction is expected to continue over extended periods of clinical relevance. The TMR results show that the fluoridating composite reduced the mineral loss values significantly with respect to the non-F control by approximately 55%, but had a negligible effect on the lesion depth values. This study indicates that WIM is an accurate and reliable technique to measure in vitro secondary dentine caries next to a composite restoration as a function of time.

Secondary caries in situ around fluoride-releasing light-curing composites: a quantitative model investigation on four materials with a fluoride content between 0 and 26 vol%.

In the literature, secondary caries around composite restorations is reported often. Fluoridated composites are therefore interesting materials because they might reduce or inhibit secondary caries. In this article an in situ model investigation is presented in which the effect of F-releasing composites on enamel demineralisation around an artificial gap of 200 microns width was quantified after 1 month. The fluoride content of the composites varied between 0 and 26 vol%. The beneficial effect of the fluoride released was larger in the gap than at the outer enamel surface. In the gap, all fluoridated composites reduced the enamel demineralisation statistically significantly with respect to the non-fluoridated control. Microradiography showed a reduction of lesion depth values of 27-45%, and a reduction of mineral loss values of 25-56%. At the outer enamel surface next to the artificial gap, a beneficial fluoridation effect was measurable only near the most fluoridated composite. The results indicate that fluoridated composites may play a role in the future prevention of secondary caries.