Acid Resistance Of Human Enamel Research Articles

The Effect of Titanium Tetrafluoride Treatment and the CO2 Laser on Acid Resistance of Human Enamel.

Introduction: Titanium tetrafluoride (TiF4 ) is deemed more effective than the previous fluoride compounds. To enhance the effect of the fluoride compounds, researchers have suggested their association with lasers, although there are conflicting results in this area. We evaluated the acid resistance of enamel after treatment with the CO2 laser and TiF4 . Methods: Thirteen human premolar teeth were sectioned into 5 parts and each segment was assigned to a study group: co (control): without treatment, AF: enamel treatment with APF 1.23% for 4 minutes, TF: enamel treatment with TiF4 4% for 1 minute, TF-L: enamel treatment with TiF4 4% and then the CO2 laser (Peak power: 1 W, pulse duration: 10 ms, interval time: 500 ms, Beam spot size: 0.2 mm, distance: 2 cm), L-TF: enamel treatment with the CO2 laser and then TiF4 4%. Each sample was kept for 7 days in acidic solution of hydroxyethyl cellulose at pH=4.5, and the amount of the calcium ion released in the solution was measured by atomic absorption spectrometry. Data were analyzed by ANOVA and Bonferroni tests. The significance level was set at 0.05. Results: The average concentration of the calcium ion released in acidic solution was 197.46, 153.30, 99.23, 61.23, 55.46 ppm in the groups respectively. There was a significant difference between the study groups (P<0.0001). Only the difference between TF-L and L-TF was not significant (P>0.05). Conclusion: The loss of calcium from the enamel samples in the groups treated with a combination of the laser and TiF4 was significantly lower than the groups treated with fluoride alone, or the control group. It did not make a significant difference whether the CO2 laser was applied before or after TiF4 .

A Comparative Analysis of Caries Inhibitory Effect of Remineralizing Agents on Human Enamel Treated With Er:YAG Laser: An In-vitro Atomic Emission Spectrometry Analysis.

The tug of war to maintain tooth integrity is dependent on a ratio between demineralization and remineralization. Hence, demineralization should be retarded and remineralization should be enhanced to maintain a natural equilibrium in the oral cavity. To compare in-vitro acid resistance of human enamel when using Casein Phosphopeptides Amorphous Calcium Phosphate (CPP-ACP) [GC Tooth mousse] cream, Casein Phosphopeptide Amorphous Calcium Fluoride Phosphate (CPP-ACFP) [GC Tooth mousse plus] cream, Er:YAG laser alone, combination of CPP-ACP with Er:YAG laser, CPP-ACFP with Er:YAG laser. An in-vitro study was done on 100 specimens which were prepared from 50 human premolars to investigate the caries inhibitory effect of remineralizing agents and laser on enamel using an atomic emission spectrometry analysis. The enamel specimens were randomly allocated into 6 groups: Untreated (control); CPP-ACP (GC Tooth mousse); CPP-ACFP (GC Tooth mousse plus); Er:YAG laser treatment alone; CPP-ACP with Er:YAG laser; CPP-ACFP with Er: YAG laser. Then specimens were immersed individually in 5ml of acetate buffer solution (0.1mol/L, pH 4.5) and incubated at 37°C for 24 hours, to determine the acid resistance by analyzing the calcium release using atomic emission spectrometry. An ANOVA model was constructed (p-value 0.05), followed by post-hoc Tukey's test for multiple pair wise comparisons of mean values. There was a significant difference among the various groups with respect to amount of calcium released (p<0.001). The lowest mean score of calcium release was observed for CPP-ACFP with Er:YAG laser followed by CPP-ACFP but the differences between these groups were statistically not significant (p>0.05). Similarly the differences between CPP-ACP with Er:YAG laser and CPP-ACP also were not significant (p>0.05). The highest mean score of calcium release was for Er:YAG laser and no significant statistical difference was noticed in comparison with control group (p>0.05). Combination of CPP-ACFP with Er:YAG laser is more effective in decreasing enamel demineralization when compared with other groups.

Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis.

Background:Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved.Aims:The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel.Design:An in vitro study was carried out on 30 human premolars to evaluate the enamel's acid resistance using an atomic emission spectrometry analysis.Materials and Methods:A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1) Untreated (control); (2) 1.23% acidulated phosphate fluoride (APF) gel application alone for 4 min; (3) Er:YAG laser treatment alone; (4) Co2 laser treatment alone; (5) Er:YAG laser + APF gel application; (6) Co2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5) and incubated at 37°C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry.Statistical Analysis:An ANOVA model was constructed (P value of 0.05), followed by Tukey's test for multiple pair wise comparisons of mean values.Results:Significant differences were found between the control group and the test groups (P < 0.001).Conclusions:Combining acidulated phosphate fluoride with either Er:YAG or Co2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone.

Influence of Er,Cr:YSGG laser irradiation on enamel caries prevention

The objective of this study was to evaluate the effects of chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation on the acid resistance of dental enamel. Forty human enamel samples were divided into four groups. They were manually irradiated with an Er,Cr:YSGG laser device (λ = 2.78 µm, 20 Hz, 20 s), in a scanning mode, with and without water cooling, according to the following parameters: Group 1: 0.25 W, 62.5 J/cm(2), no water cooling; group 2: 0.25 W, 62.5 J/cm(2), 5.0 ml/min; group 3: 0.5 W, 125 J/cm(2), no water cooling; group 4: 0.5 W, 125 J/cm(2), 5.0 ml/min. No airflow was used. Afterwards, the samples were submitted to an acid challenge and assessed by cross-sectional Knoop microhardness at different depths (20, 40, 60, 80, and 100 µm) from the outer enamel surface. Average values were obtained for both irradiated and control areas in each sample and they were compared to obtain a percentage of microhardness increase. Data were analyzed by analysis of variance and Fisher's exact test (α = 5%). The percentage of microhardness increase observed in group 1 (+23.58%) was similar to group 3 (+19.12%), but higher than groups 2 (+3.61%) and 4 (10.9%) (p < 0.05). The comparison of the depths showed that the Er,Cr:YSGG laser acted in the superficial layers of the dental enamel. The findings of the present study suggest that the energy densities of 62.5 and 125 J/cm(2) were capable of increasing the acid resistance of human enamel. The presence of water during irradiation makes it difficult to obtain an enamel surface more resistant to acids.

Effects of Lasers and Fluoride on the Acid Resistance of Human Enamel with Incipient Carious Lesions

Objectives In order to preserve the maximum amount of healthy enamel and increase the acid resistance of an incipient carious lesion, CO2 laser, Nd: YAG laser and APF were used to treat incipient carious lesions, then their effects were compared. Materials and Methods One hundred and twenty samples from human caries-free premolars were immersed in pH-cycling solution for 2 days for incipient carious lesion formation. Then all the samples, were divided into 4 groups randomly; control group, CO2 laser group, Nd: YAG laser group and APF group, and the lesions were treated by CO2 laser, Nd: YAG laser irradiation or APF application respectively. All the samples were immersed in pH-cycling solution a second time for 2 days. As for the acid-resistance evaluation, the calcium concentration dissolved from the enamel, surface was analyzed by ISE-trol. Scanning electron microscopy with energy dispersive X-ray analysis system was also used to assay the geographic change and the components of the enamel surface structures. Results According to the acid-resistance evaluation, the control group showed a statistically significant (P＜0.05) higher calcium concentration compared with the APF group and the other Mo laser groups. Moreover, the APF group showed a statistically significant higher calcium concentration compared with the Nd: YAG laser and CO2 laser groups (P＜0.05). However, there was no substantial statistical difference in the two laser groups (P＞0.05). From the SEM, the melting and re-crystallization surfaces and crater-like holes, 1-20µm in diameter, were found on the CO2 laser and Nd: YAG laser treated enamel surfaces. Finally, in the aspect of the EDS, there was no evidence of new components on the enamel surfaces after lasers and APF were applied. Conclusions The app1ication of CO2 laser, Nd: YAG laser and APF on enamel incipient carious increase acid resistance. Furthermore, the effect of laser irradiation is better than that application.

Relationship between the fluoride concentration of the fluoride-releasing elastomers and the acquired acid resistance of human enamel in vitro.

The objective of the study was to evaluate the relationship between the fluoride concentration of the fluoride-releasing elastomers and the acquired acid resistance of human enamel. Four kinds of fluoride concentration of the experimental fluoride-releasing elastomers were 1.25, 2.5, 3.75 and 5.0 wt%. An enamel block was cut into two smaller enamel blocks, one of which was set with an elastomer, the other as a control not set with elastomer. A plastic block that had the same shape as the small enamel block was also set with elastomer. Fluoride release and acid resistance tests were carried out. The mineral loss of the demineralized enamel was measured by microradiography. The results showed that the fluoride-releasing ability significantly increased with the increase of fluoride concentration in the elastomer (p < 0.05). The acid resistance of the enamel appeared to be enhanced greatly, however, its change was not proportional to the fluoride concentration in the elastomers.

In vitro Acid Resistance of CO2and Nd-YAG Laser-Treated Human Tooth Enamel

The purposes of this study were to test the effectiveness of laser treatment (pulsed CO₂ and pulsed Nd-YAG) on in vitro acid resistance of human enamel. Thirty enamel surfaces were prepared from 10 extracted permanent premolars (3 surfaces per tooth). Two experimental surfaces on each tooth were irradiated with either CO₂ or Nd-YAG lasers. All specimens were demineralized in 10 ml lactate buffer for 24 or 72 h after laser treatment. After 24-hour acid treatment the mean concentration of calcium that dissolved into the lactate buffer in the CO₂ laser group was significantly less than in the control group, while the dissolved calcium concentration in the Nd-YAG laser group did not differ from the control group (p > 0.05). The erosion depth in the CO₂ laser group was significantly shallower than in the Nd-YAG laser group (p < 0.001). After 72-hour acid treatment, the acid resistances of neither group of laser-treated surfaces differed significantly from the controls. By scanning electron microscopy, the acid-eroded laser-treated enamel surfaces had type I and type II etching patterns, fissures, and disordered rough surfaces compared to control enamel, with a regular type II etching pattern. CO₂ laser-treated tooth enamel was more resistant to acid challenge than was Nd-YAG laser-treated enamel, given the same fluence, but neither type of laser increased acid resistance of subsurface enamel.

Acid resistance of human enamel in vitro after bicarbonate application during remineralization

Objectives: The aim of this study was to investigate the acid resistance of subsurface enamel lesions remineralized with bicarbonate solutions during remineralization. Methods: Two experiments were carried out. In experiment 1, mineral uptake and acid resistance of remineralized enamel lesions were analyzed quantitatively by microradiography for mineral changes. Bicarbonate solutions of 0.5, 5.0 and 50.0 mM were used. In experiment 2, to clarify acid resistance mechanisms, the pH changes in demineralizing solutions on the remineralized enamel surfaces were measured continuously. Only a bicarbonate solution of 5.0 mM was used. Results: In experiment 1, the bicarbonate-treated groups were more acid resistant than the non-treated groups ( p<0.05). However, no statistically significant difference was observed among the different concentrations of bicarbonate. In experiment 2, the pH rise of the bicarbonate group was greater than the other groups. Conclusion: It was found that bicarbonate-treated enamel lesions were resistant to acid. It would suggest that bicarbonate ions applied during remineralization may have penetrated into the subsurface lesions. These ions may have worked as buffer agents against the acid challenge and inhibited the decrease in pH.

Combined Effect of Laser and Fluoride on Acid Resistance of Human Enamel

Combined Effect of Laser and Fluoride on Acid Resistance of Human Enamel