Comparison of micromorphological changes in enamel using SEM analysis after conventional and erbium, chromium:yttrium, scandium, gallium, and garnet hard-tissue laser fissurotomy: An in vitro study

Background

Well articulated by John Knowles - "Everything has to evolve or else it perishes." With the paradigm shift of emphasis toward the prevention of dental caries, it has been proven that laser irradiation protects against both caries initiation and caries progression.

Aim

The aim of the study was to evaluate and compare the micromorphology of caries-free extracted premolars using a Scanning electron microscope (SEM) after fissurotomy by conventional fissurotomy bur and erbium, chromium: yttrium, scandium, gallium, and garnet (ER, CR: YSGG) hard-tissue laser.

Methodology

Sixty caries-free premolars extracted atraumatically for orthodontic treatment were included in the study. The samples were divided into two groups randomly (Group 1: fissurotomy by bur, n = 30, and Group 2: fissurotomy by hard-tissue laser, n = 30). Each sample was further divided into halves from the occlusal surface wherein one-half of the occlusal surface received fissurotomy procedure and the other half was control. Samples were analyzed by scanning electron microscopy (SEM) for micromorphological changes.

Results

Profile image of control samples revealed the disorganization of enamel surface at the junction of fissures forming a heterogeneous tissue and agglomeration of enamel with deep pit and fissure. On the contrary, the image of experimented samples (with laser fissurotomy) showed smooth enamel surface and homogeneous enamel subsurface with wider pit and fissure owing to self-cleansing ability.

Conclusion

On the grounds of the present study results, it could be concluded that the intervention of ER, CR: YSGG hard-tissue laser possesses self-cleansable pit and fissures for caries prevention and has the potential to irradicate the smear layer entirely for superior attachment of remineralizing agents.

In vitro comparative evaluation of physical and chemical properties of surface enamel after using APF and SDF with or without laser activation

PURPOSE

To evaluate and compare the changes in physical and chemical properties of the enamel surface after application of Silver Diamine Fluoride (SDF), Acidulated Phosphate Fluoride (APF), LASER activated SDF and LASER activated APF.

METHODS

Sample consisted of 72 freshly extracted healthy human premolar teeth, extracted for orthodontic purpose, free from caries, fracture or any anomalies. The selected samples were randomly divided into four groups (n = 18): Group 1 (SDF); Group 2 (APF); Group 3 (LASER activated SDF) and Group 4 (LASER activated APF). All samples were evaluated for values of DIAGNOdent at baseline, after demineralisation and after remineralisation. They were further divided and assessed for colour changes, surface alterations and fluoride content of surface enamel using Spectrophotometer, Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometry respectively. The statistical analysis was done using One-Way ANOVA, Tukey's HSD test, Mann-Whitney U test and Kruskal-Wallis Test.

RESULTS

Highest remineralising potential and maximum colour changes of surface enamel was exhibited by Group 3. Scanning Electron Micrographs of Group 3 and Group 4 exhibited regular globular structures of enamel whereas Group 1 and Group 2 showed irregular globular surface of the enamel at 2000× and 5000× magnification. Maximum fluoride uptake on the surface enamel was seen in Group 4 followed by Group 3.

CONCLUSION

Use of LASER activated topical fluorides helps to achieve superior caries prevention. LASER activated APF can be used as an aesthetic alternative to SDF, as LASER activated APF showed higher uptake of fluoride on the enamel surface without discoloration effect.

Assessment of changes in Streptococcus pyogenes levels using N-acetylgalactosamine-6-sulfatase marker and pharyngeal airway space with appliance therapy in mouth breathers - An ELISA-based study

Background

The frequency of adenotonsillar hypertrophy in mouth-breathing children when compared to the average found in the general population is considered to be higher. Mouth breathing is considered as one of the causative factors for tonsillitis in children. Through continuous irritation on tonsillar wall, tonsils swell up and inflammation develops.

Purpose

The purpose of the study is to evaluate Streptococcus pyogenes count using colony-forming units (CFUs) and N-acetylgalactosamine-6-sulfatase side chain marker on ELISA (enzyme linked immunosorbent assay) in mouth breathers and to establish its correlation with pharyngeal airway space pre- and post-oral screen appliance therapy.

Materials and Methods

A total number of 24 (n) mouth breathers aged between 5 and 12 years were included in the study and given oral screen appliance therapy. The subjects were evaluated for the various parameters before the delivery of a habit-breaking appliance and then reevaluated for the same parameters (presence of S. pyogenes and its counts, size of tonsils, and pharyngeal airway space dimensions) after 6 months of appliance usage.

Results

A statistically significant difference was seen in levels of S. pyogenes using ELISA and CFUs. Furthermore, statistically significant difference was observed in Friedman tonsil scoring and pharyngeal airway space and pre- and post-oral screen appliance therapy.

Conclusion

Oral screen appliance therapy reduced the frequency of occurrence of tonsillitis in mouth breathers by decreasing the counts of S. pyogenes bacteria. Upper and lower pharyngeal airway space dimensions were increased after 6 months of appliance therapy in mouth breathers.

Evaluation of temperature rise and efficacy of cavity disinfection with diode laser: An in vivo study

Background

Management of caries using minimally invasive dentistry is prevalent in dentistry today. A newer technology is to disinfect/sterilize caries in depth of the dental tissue with diode laser. However, to have a bactericidal effect, increased energy density of light amplification by stimulated emission of radiation (LASER) may be required which in turn may lead to higher thermal load causing harmful effects on vital pulpal tissue.

Aims

The aim was to evaluate temperature rise and efficacy of cavity disinfection with diode laser.

Materials and Methods

Twenty permanent molar teeth with dentinal caries were randomly assigned into two groups on the basis of LASER irradiation: Group 1 - at 1 W, Group 2 - at 2 W. The elevation of subsurface temperature during irradiation was measured using thermocouples positioned in the center of a prepared cavity. Dentinal samples were collected before and after disinfection of the cavity. These samples were subjected to microbiological evaluation for Streptococcus mutans on Mutans-Sanguis agar and Lactobacilli on Rogosa agar.

Statistical Analysis

Log transformed "t"-test and paired "t"-test were used for the statistical analysis.

Results

Although the reduction in microbial count revealed insignificant difference at two different wattages, the rise in temperature with 1 W was less than that with 2 W.

Conclusion

Efficacy of 1 W and 2 W is similar, but 1 W causes less thermal changes, thus, 1 W is recommended over 2 W.

Comparison of Visual Examination and Magnification with DIAGNOdent for Detection of Smooth Surface Initial Carious Lesion-Dry and Wet Conditions

Objective

The aim of this study was to assess the effectiveness and reliability of magnification, DIAGNOdent in detection of smooth surface white spot lesions.

Study design

Three hundred children aged 5–10 years were examined by two examiners for presence of smooth surface white spot lesions using naked eye and magnifying loupes in wet and dry conditions followed by DIAGNOdent analysis. Data was analysed using Cohen's kappa coefficient, Friedman test and Paired t test. Accuracy was assessed by sensitivity and positive predicted values.

Results

Significant difference was found between naked eyes and magnifying loupes with and without air drying. While insignificant difference was found between DIAGNOdent and loupes.

Conclusion

Magnifying loupes with air drying is an effective method in detection of smooth surface white spot lesion.

Clinical significance

With the increased knowledge about the pathogenesis of dental caries and its ability to be remineralisable if detected early, makes it all the more important for the clinician to be vigilant in detection of early lesion to prevent the avoidable restorative approach for the same. Incorporation of magnification to routine dental examination by general dentist can help in early diagnosis and treatment of dental decay. This could prevent further progression of dental caries and reduces the incidence of tooth decay

How to cite this article

Gupta N, Sandhu M, et al. Comparison of Visual Examination and Magnification with DIAGNOdent for Detection of Smooth Surface Initial Carious Lesion—Dry and Wet Conditions. Int J Clin Pediatr Dent 2019;12(1):37–41.

Shear Bond Strength of Self-etching Adhesives to Cavities Prepared by Diamond Bur or Er,Cr:YSGG Laser and Effect of Prior Acid Etching

PURPOSE

To compare and evaluate shear bond strength of self-etching adhesives bonded to cavities prepared by diamond bur or Er,Cr:YSGG laser and the effect of prior acid etching on shear bond strength.

MATERIALS AND METHODS

Ninety-six caries-free human premolars were selected and divided into 2 groups depending on mode of cavity preparation (48 teeth each). Cavities were prepared with Er,Cr:YSGG laser in group 1 and diamond burs in an air-turbine handpiece in group 2. Groups 1 and 2 were further subdivided into three subgroups of 8 teeth each, which were bonded with sixth- or seventh-generation adhesives with or without prior acid etching, followed by restoration of all samples with APX Flow. These samples were subjected to shear bond strength testing. In addition, the surface morphology of 24 samples each from groups 1 and 2 was evaluated using SEM. Data were analyzed using the Shapiro-Wilk test, one- and two-way ANOVA, the t-test, and the least significant difference test, which showed that the data were normally distributed (p > 0.05).

RESULTS

The shear bond strength of adhesives in cavities prepared by Er,Cr:YSGG laser was significantly higher than in diamond bur-prepared cavities (p < 0.05). SEM analysis showed a smear-layer-free anfractuous surface on laser-ablated teeth, in contrast to conventional bur-prepared teeth.

CONCLUSIONS

The Er,Cr:YSGG laser-ablated surface proved to be more receptive for adhesion than those prepared by diamond bur irrespective of the bonding agent used. Seventh-generation adhesives yielded higher shear bond strength than did sixth-generation adhesives. Prior acid etching decreased the shear bond strength of self-etching adhesives.

An in-vitro evaluation of the effect of 980 nm diode laser irradiation on intra-canal dentin surface and dentinal tubule openings after biomechanical preparation: Scanning electron microscopic study

Context:

Very recently, diode laser has been used for disinfecting the root canals in endodontic treatment and increasing its success rate and longevity utilizing the thermal effect of laser on surrounding tissues.

Aims:

The aim of this study is to evaluate the effect of 980 nm laser irradiation on intra-canal dentin surface – scanning electron microscopic (SEM) - in-vitro study.

Methods:

A total of 40 single-rooted freshly extracted permanent teeth were collected. Teeth were sectioned at the cemento-enamel junction using diamond disc. Root canals of all samples were prepared using hand ProTaper, which were randomly assigned into two groups (n = 20 each). Group 1: Receiving no treatment after biomechanical preparation; Group 2: 980 nm diode laser-treated root canals. Teeth were prepared for SEM analysis to check the size of intra-canal dentinal tubule openings.

Statistical Analysis Used:

Data were analyzed using SPSS V.16 software and compared using Levene's and independent t-test.

Results:

On statistical analysis, width of intracanal dentinal tubule openings in Group 1 (control) was significantly higher than those observed in Group 2 (diode laser-treated) (P < 0.001).

Conclusion:

This study showed that the application of 980 nm diode laser on intra-radicular dentin resulted in ultrastructural alterations resulting in melting of dentin.