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 Table of Contents  
ORIGINAL ARTICLE
Year : 2012  |  Volume : 6  |  Issue : 1  |  Page : 7-10

Prevention of enamel from erosion by laser activated fluoride treatment


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 Publication15-Sep-2012

Correspondence Address:
Aliya Sayed
7, Dr. Coyaji Road, Pune 411001
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-2868.100976

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  Abstract 

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

How to cite this URL:
Sayed A, Hegde V, Thukral N. Prevention of enamel from erosion by laser activated fluoride treatment. J Dent Lasers [serial online] 2012 [cited 2017 Mar 30];6:7-10. Available from: http://www.jdentlasers.org/text.asp?2012/6/1/7/100976


  Introduction Top


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". [1] The pathogenesis of erosion is multifactorial, [2] but the fundamental event is etching and progressive and irreversible loss of the enamel surface layer. [3]

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. [4],[5],[6] Sognnaes and Stern [7] 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. [8] 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 Top


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].
Table 1: Laser equipment and parameters


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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 Top


Statistical analysis

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].
Table 2: Within group comparison of hardness

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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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Table 4: Between group comparison of hardness (P values)

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  Discussion Top


The pathogenesis of erosion is multifactorial in nature 9 and is influenced by intrinsic factors and extrinsic factors. [9] Brought on by etching and progressive and irreversible loss of the enamel surface layer, [10] 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 [11],[12],[13],[14],[15],[16],[17],[18],[19],[20],[21],[22],[23],[24] and the influence of aetiological and physiological factors on the location and severity of erosion. [25],[26] 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. [1],[27]

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. [28],[29],[30]

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. [6],[31],[32] Fowler and Kuroda [28],[29] 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:

  1. The creation of surface coating, on lased tooth structure, which increases the affinity for fluoride, calcium and phosphate ions from endogenous and exogenous sources.
  2. Swelling and denaturation of proteins on the enamel surface, with subsequent sealing of the surface pores.
  3. Alterations of micro-organism in plaque that may be irradiated, and
  4. Stabilization and decreased solubility of hydroxyapatite.

  Conclusion Top


In order of merit least reduction in hardness after acid challenge was shown by Nd:YAG followed by KTP, CO2 and diode laser.

 
  References Top

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]


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