|Year : 2012 | Volume
| Issue : 1 | Page : 7-10
Prevention of enamel from erosion by laser activated fluoride treatment
Aliya Sayed1, Vivek Hegde2, Naresh Thukral3
1 Department of Conservative Dentistry and Endodontics, M.A. Rangoonwala College of Dental Sciences and Research, Pune, Maharashtra, India
2 M.A. Rangoonwala College of Dental Sciences and Research, Pune, Maharashtra, India
3 Department of Periodontology and Oral Implantology. M. A. Rangoonwala College of Dental Sciences and Research, Pune, Maharashtra, India
|Date of Web Publication||15-Sep-2012|
7, Dr. Coyaji Road, Pune 411001
Source of Support: None, Conflict of Interest: None
Introduction:Irradiation of human dental enamel with laser energy at particular wavelengths in the visible and infrared regions result in greater resistance to acid and cariogenic attacks. The aim of the present study was to investigate the effectiveness of four commonly available laser wavelengths,KTP, Nd: YAG, Diode, CO2 in terms of the LAF protective effect to an erosive challenge. Materials and Methods: 40 sound human premolar teeth were used. The lingual and buccal surfaces of the teeth were sectioned into slabs using a diamond saw. The baseline Vicker's hardness number (VHN) of each surface was determined. 1.23% NaF gel was then applied to these slabs and they were divided into Group I - Control group. Group II - KTP Group III - Nd:YAG Group IV - Diode Group V - CO2. The Vicker's hardness number (VHN) of each surface was again determined after the fluoride and laser treatment. Results: Group II and Group III, which are KTP and Nd:YAG respectively showed significantly small amount of change as compared to the other groups. Conclusion: In order of merit least reduction in hardness after acid challenge was shown by Nd:YAG followed by KTP, CO2 and diode laser.
Keywords: Erosion, KTP, Nd: YAG, Diode, CO2, Fluoride
|How to cite this article:|
Sayed A, Hegde V, Thukral N. Prevention of enamel from erosion by laser activated fluoride treatment. J Dent Lasers 2012;6:7-10
| Introduction|| |
As lifestyles have changed through the decades, the total amount and frequency of consumption of acidic foods and drinks have also changed. Dental erosion can be defined as the "physical results of a pathologic, chronic, localized loss of dental hard tissues that is chemically etched away from the tooth surface by acid and/or chelation without bacterial involvement".  The pathogenesis of erosion is multifactorial,  but the fundamental event is etching and progressive and irreversible loss of the enamel surface layer. 
Numerous studies have shown that irradiation of human dental enamel with laser energy at particular wavelengths in the visible and infra-red regions result in greater resistance to acid and cariogenic attacks. ,, Sognnaes and Stern  were the first to demonstrate increased enamel resistance to demineralization as a result of laser irradiation. Since then numerous studies have examined the process by which laser energy, either alone or in combination with topical fluoride therapies (laser-activated, LAF), increases the resistance of tooth structure to mineral loss from the organic acids involved in dental caries.  More recently we have shown 25 that this effect is achieved with a broad spectrum of laser light with comparable results to that of the traditional Argon ion laser. With an increase in incidence of dental erosion, and in light of the above findings, it was of interest to determine whether LAF therapy may also offer protective benefits against dental erosion, which typically involves stronger acids such as phosphoric and hydrochloric acids. No previous studies have examined systematically the action spectrum of LAF, using laser wavelengths in the visible and near infrared regions, as protection against dental enamel loss caused by a strong erosive challenge. Accordingly, the aim of the present study was to investigate the effectiveness of four commonly available laser wavelengths, in terms of the LAF protective effect to an erosive challenge. Additionally, the authors also examined intra-pulpal temperature changes with each of the lasers. As softening of enamel is a key factor that links to its loss, we used microhardness measurements to assess the extent of protection afforded by LAF therapy.
| Materials and Methods|| |
Enamel slabs were prepared from 40 sound human premolar teeth that had been extracted for orthodontic reason. After debridement of gingival soft tissue remnants and prophylaxis with a fluoride-free paste, the lingual and buccal surfaces of the teeth were sectioned into slabs using a diamond saw. The surfaces of the slabs were polished with 1200 grit silicon carbide paper, and the prepared samples stored in a humidor at room temperature until used. The baseline Vicker's hardness number (VHN) of each surface was determined using a mini-load hardness tester (Ernst Leitz). 1.23% NaF gel was then applied to these slabs and they were divided into the following treatment groups of 10 teeth each [Table 1].
Group I - Control group.
Group II - KTP
Group III - Nd:YAG
Group IV - Diode
Group V - CO 2
Immediately after laser treatment, the fluoride gel was rinsed from the enamel surfaces with distilled water. The surfaces were then subjected to an acid challenge (1.0M hydrochloric acid for 5 minutes) to provide an erosive (corrosive) challenge sufficient to cause softening of the unprotected enamel. The Vicker's hardness number (VHN) of each surface was again determined after the fluoride and laser treatment.
| Results|| |
Groups II and III showed significantly smaller amount of change compared to Group I (Controls). Approximately similar amount of change seen in Groups IV and V compared to Group I (Controls) Groups II and III showed significantly smaller amount of change compared to Group IV [Table 2].
Statistical methods used
Values are shown as Mean (SD). Average hardness across all study groups were compared using Kruskal Wallis H test (a Non-parametric ANOVA test procedure) adjusted for multiple comparisons. Percentage relative change in hardness after the treatment from baseline values is calculated using following formula: 100x (Hardness After - Hardness Before)/Hardness Before. P-value less than 0.05 were considered to be statistically significant [Table 3] and [Table 4]. The entire statistical analysis was performed using Statistical Package for Social Sciences (SPSS version 11.5) for MS Windows.
|Table 3: P value by Wilcoxon's signed rank test. Between group comparison of hardness (P values)|
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| Discussion|| |
The pathogenesis of erosion is multifactorial in nature 9 and is influenced by intrinsic factors and extrinsic factors.  Brought on by etching and progressive and irreversible loss of the enamel surface layer,  the softened tooth structure is easily removed with mechanical stimuli 12 such as normal chewing and tooth brushing. Numerous studies have investigated the erosive potential of different substances ,,,,,,,,,,,,, and the influence of aetiological and physiological factors on the location and severity of erosion. , Factors such as protection by saliva and pellicle are known to influence the location of erosion lesions, 30, 31 while the severity of the condition is affected by medical conditions including gastro-oesophageal reflux. 46-48 Preventive strategies for dental erosion are few, and for this reason greater efforts are required to address the increasing clinical problems posed by dental erosion. ,
A variety of mechanisms involving chemical or physic-chemical changes have been postulated to explain laser preventive and Laser activated fluorides (LAF) effects. A decrease in the permeability or solubility of enamel or a combination of both is a common explanation for the effect of laser radiation on enamel. ,,
Studies of the effect of laser irradiation on human dental enamel have reported changes in the craystal structure of hydroxyapatite, together with a reduction in the extent of dissolution following acid challenge. ,, Fowler and Kuroda , have suggested that irradiation with high- intensity laser radiation ultimately leads to the formation of pyrophosphate, which is responsible for decreased enamel solubility in acidic conditions. According to their predictions the temperature at the laser-irradiated enamel surface increases from the ambient temperature to reach approximately 1400o C. Fox et al have demonstrated that enamel lased with CO 2 laser has a reduced dissolution rate. Furthermore, in a separate study the same group demonstrated that laser irradiation of enamel reduces the critical Ph at which enamel dissolution occurs, from 5.5 to 4.8. This critical Ph is further reduced in the presence of fluoride, even at concentration as low as 0.01 ppm, to 4.3.
Further mechanisms for LAF that have been proposed include:
- The creation of surface coating, on lased tooth structure, which increases the affinity for fluoride, calcium and phosphate ions from endogenous and exogenous sources.
- Swelling and denaturation of proteins on the enamel surface, with subsequent sealing of the surface pores.
- Alterations of micro-organism in plaque that may be irradiated, and
- Stabilization and decreased solubility of hydroxyapatite.
| Conclusion|| |
In order of merit least reduction in hardness after acid challenge was shown by Nd:YAG followed by KTP, CO2 and diode laser.
| References|| |
|1.||Ten Cate JM, Imfeld T. Dental erosion, summary. Eur J Oral Sci 1996;104:241-4. |
|2.||Moss SJ. Dental erosion. Int Dent J 1998;48:529-39. |
|3.||McIntyre JM. Erosion. Aust Prosthodont J 1992;6:17-25. |
|4.||Nelson DA, Shariati, Glena R, Shields CP, Featherstone JD. Effect of pulsed low energy infrared laser irradiation on artificial caries like lesion formation. Caries Res 1987;20:289-99. |
|5.||Stern RH, Sognnaes RF. Laser inhibition of dental caries suggested by first tests in vivo. J Am Dent Assoc 1972;85:1087-90. |
|6.||Stern R H, Vahl J, Sognnaes RF. Lased enamel: Ultra-structural observations of pulsed carbon dioxide laser effects. J Dent Res 1972;51:455-60. |
|7.||Sognnaes RF, Stern RH. Laser effect on resistance of human dental enamel to demineralization in vitro. J South Calif Dent Assoc 1965;33:328-9. |
|8.||Anderson JR, Ellis RW, Blankenau RJ, Beiraghi SM, Westerman GH. Caries resistance in enamel by laser irradiation and topical fluoride treatment. J Clin Laser Med Surg 2000;18:33-6. |
|9.||Zero DT. Etiology of dental erosion - extrinsic factors. Eur J Oral Sci 1996;104:162-77. |
|10.||Sheutzel P. Etiology of dental erosion - intrinsic factors. Eur J Oral Sci 1996;104:178-90. |
|11.||Hughes JA, West NX, Parker DM, Newcombe RG, Addy M. Development and evaluation of a low erosive blackcurrant juice drink in vitro and in situ. 1. Comparison with orange juice. J Dent 1999;27:285-9. |
|12.||Hunter ML, West NX, Hughes JA, Newcombe RG, Addy M. Relative susceptibility of deciduous and permanent dental hard tissues to erosion by a low pH fruit drink in vitro. J Dent 2000;28:265-70. |
|13.||Bartlett DW, Coward PY. Comparison of the erosive potential of gastric juice and a carbonated drink in vitro. J Oral Rehabil 2001;28:1045-7. |
|14.||Mok TB, McIntyre J, Hunt D. Dental erosion: in vitro model of wine assessor's erosion. Aust Dent J 2001;46:263-8. |
|15.||Gray A, Ferguson MM, Wall JG. Wine tasting and dental erosion. Case report. Aust Dent J 1998;43:32-4. |
|16.||Hunter ML, West NX, Hughes JA, Newcombe RG, Addy M. Erosion of deciduous and permanent dental hard tissue in the oral environment. J Dent 2000;28:257-63. |
|17.||Milosevic A, Kelly MJ, McLean AN. Sports supplement drinks and dental health in competitive swimmers and cyclists. Br Dent J 1997;182:303-8. |
|18.||Wiktorsson AM, Zimmerman M, Angmar-Mansson B. Erosive tooth wear: prevalence and severity in Swedish winetasters. Eur J Oral Sci 1997;105:544-50. |
|19.||Meurman JH, Härkönen M, Näveri H, Koskinen J, Torkko H, Rytömaa I, et al. Experimental sports drinks with minimal dental erosion effect. Scand J Dent Res 1990;98:120-8. |
|20.||Eisenburger M, Addy M. Evaluation of pH and erosion time on demineralisation. Clin Oral Investig 2001;5:108-11. |
|21.||Rees JS, Davis FJ. An in vitro assessment of the erosive potential of some designer drinks. Eur J Prosthodont Restor Dent 2000;8:149-52. |
|22.||Lussi A, Kohler N, Zero D, Schaffner M, Megert B. A comparison of the erosive potential of different beverages in primary and permanent teeth using an in vitro model. Eur J Oral Sci 2000;108:110-4. |
|23.||West NX, Hughes JA, Addy M. Erosion of dentine and enamel in vitro by dietary acids: The effect of temperature, acid character, concentration and exposure time. J Oral Rehabil 2000;27:875-80. |
|24.||West NX, Hughes JA, Addy M. The effect of pH on the erosion of dentine and enamel by dietary acids in vitro. J Oral Rehabil 2001;28:860-4. |
|25.||Hughes JA, West NX, Parker DM, van den Braak MH, Addy M. Effects of pH and concentration of citric, malic and lactic acids on enamel, in vitro. J Dent 2000;28:147-52. |
|26.||Jarvinen V, Rytomaa I, Meurman JH. Location of dental erosion in a referred population. Caries Res 1992;26:391-6. |
|27.||Lussi AR, Schaffner M, Hotz P, Suter P. Dental erosion in a population of Swiss adults. Community Dent Oral Epidemiol 1991;19:286-90. |
|28.||Nunn JH. Prevalence of dental erosion and the implications for oral health. Eur J Oral Sci 1996;104:156-61. |
|29.||Kuroda S, Fowler BO. Compositional, structural and phase changes in in vitro laser-irradiated human tooth enamel. Calcif Tiss Int 1984;36:361-9. |
|30.||Fowler BO, Kuroda S. Changes in heated and in laser irradiated human tooth enamel and their probable effects on solubility. Calcif Tiss Int 1986;38:197-208. |
|31.||Yamamoto H, Ooya K. Potential of yttrium-aluminum-garnet laser in caries prevention. J Oral Pathol 3: 7-15, 1974. |
|32.||Dugmore CR, Rock WP. The prevalence of tooth erosion in 12- year-old children. Br Dent J 2004;196:279-82. |
[Table 1], [Table 2], [Table 3], [Table 4]