ABSTRACT
The purpose of this in vitro study was two-fold. First the effectiveness of ozone, as a bleaching agent, in comparison with other commercJaJJy available bleaching products was evaluated by measuring the change in color index of teeth. Second the presence of any surface damages, which may occur in enamel surface following bleaching, was investigated by measuring the surface roughness of enamel as this may have an implication on the functional properties of the surface. One bleaching gel with two different concentrations [Opalescence 10% and 20%], and an Ozone gas [O3] were used in this study. The Ozone was incorporated into: 10% carbamide peroxide gel, neutral KY gel and distilled water. Twenty five intact maxillary first premolars were used. The teeth were randomly divided into five groups. Group J was treated with ozonated 10% carbamide peroxide, group fl was exposed to ozonated water, group III was treated with ozonated KY gel, group IV and V were subjected to 10% and 20% carbamide peroxide respectively. For each specimen, a photomicrograph was undertaken before and after treatment by a digital camera attached to a zoom stereo microscope. The tricolor index (RGB system) for brightness index measurement and the surface roughness (Ra) 'were automatically calculated using image analysis software. The value of the blue color parameter was specifically registered.
Results: There was no statistically significant difference between the control and the experimental specimens for the groups I, II and IV [p > 0.05]. However, by looking at the results of the blue color paramcL-r; there was a statistically significant difference between the control and the experimental speomens of group IV. This difference was not observed for group I and JI respectively. Regarding groups III and V a significant difference in color index and blue color parameter was observed between the control and the experimental specimens [p< 0.05] indicating a good brightness effect. By comparing the changes in color indices of the five groups, there was a statistically significant difference [p< 0.05] among them. Groups III and V showed a significantly higher color index than the other groups. The most effective bleaching regimen was obtained when the teeth were treated with 20% carbamide peroxide and ozonated KY gel respectively. In general, there was an increase in the 1 average surface roughness [Ra] with all different treatments. By comparing the surface roughness of the five groups, there was a statistically significant difference between the five groups and they were ranked as follow [from the lowest to the highest]: Group II, Group I, Group IV, Group III and Group V. Pearson correlation coefficient showed no correlation between the color iadex -and Ra for group I, while the correlation between color indices and Ra for the rest of the groups were not statistically significant. In general, no relation between surface roughness and color index could be established.
Conclusions: The use of Ozone is an effective and viable method for bleaching teeth. Bleaching has an adverse effect on the surface roughness of enamel. Although the correlation between the color index and the surface roughness was not significant, yet there was a trend showing that the brighter the bleached teeth the higher the surface roughness. The change in the blue color parameter is an appropriate descriptor of brightness. Clinical Relevance The use of Ozone as a bleaching agent should provide a fast, effective and harmless method to whiten teeth. It should be easily supplied and integrated in dental offices. The potential adverse effects of bleaching must be known to the dentist in order to be able to overcome these effects. Clinically, brightness index from computer analysis of digitized photographic images may be useful for monitoring the effectiveness of bleaching.
ABSTRACT
This study was conducted to investigate the effect of chemo-mechanical caries removal on the chemistry and morphology of carious dentin and on subsequent dentin adhesion. A total of 52 carious third molar teeth were used. Twenty teeth were used for chemical analysis and morphological analysis using energy dispersive spectroscope and scanning electron microscope, respectively. Twenty teeth were used for shear bond strength measurements, and twelve teeth for evaluating the microstructure of resin dentin interface. The teeth were divided into four groups: Group I is carisolv treated dentin, group II dentin is treated with carisolv followed by phosphoric acid etching, group III is carisolv followed by sodium hypochlorite while group IV is carisolv followed by self-etching primer. In the chemical analysis results, the highest peak heights for calcium and phosphorous were recorded for group I, followed by group III, then followed by group IV, while the least peak heights were recorded for group II. Scanning electron photomicrographs of dentin after caries removal using carisolv and different treatments revealed the removal of the smear layer, opening of the dentinal tubules and morphological alteration of the intertubular dentin. While scanning electron photomicrographs of the resin-dentin interface revealed an acid resistant resin dentin interdiffusion zone, irrespective of the surface treatment performed. The mean shear bond strength values for group I, III and IV were 16.64 MPa, 14.97 MPa and 15.52 MPa respectively, and the difference was statistically insignificant. Group II showed the lowest mean shear bond strength value of 9.55 MPa and the difference was statistically significant from the three other groups. It was concluded that dentin surface after chemo-mechanical caries removal is sound, mineralized and very suitable for restoration. Bonding to carisolv treated dentin is dependant on the adhesive system used; a separate etching step is not indicated, while deproteinization of carisolv treated dentin or the use of self-etching primer is a viable bonding protocol
Clinical Relevance: To achieve successful bonding to Carisolv treated dentin, the etching step should be omitted from the regular bonding procedure. The dentist should shift to the primer step directly, or use self-etching primers
ABSTRACT
Life usually gets simpler, but in the case of photocuring dental restorative materials just the opposite is true. Confusing and contradictory barrages of clinical claims have been made with the evergrowing variety of light curing sources, techniques and materials available today. This study was carried out to evaluate the marginal integrity of different elastic modulus resin composites polymerized using Light Emitting Diodes [LED] and Halogen light curing units [LCUs] in either standard or exponential curing mode. Sixty standardized box-shaped class V cavities were prepared in sound human premolars. The teeth were randomly divided into three equal groups according to the resin composite utilized. In the first group, cavities were restored with Teric Ceram, the second group, restored with Tetric Flow, and the third group, cavities were lined with Tetric Flow then restored with Tetric Ceram. Each group was further subdivided into two equal subgroups according to the LCU used; either LED or Halogen. In all teeth the buccal cavities were cured in standard full intensity mode [400 mW/cm[2] for 40 seconds], while the lingual cavities were cured in an exponential mode [0-400 mW/cm[2] for 12 seconds, plus 400 mW/cm[2] for 28 seconds] in case of LED, and [120- 400 mW/cm[2] for 15 seconds plus 400 mW/cm[2] for 25 seconds] in case of Halogen curing. The teeth were then sectioned buccolingually and observed under a binocular stereo microscope connected to an image analysis soft ware. For each specimen, the pore number, mean pore area, as well as the mean surface area of pores, [representing the total gap area at the tooth/restoration interface] were calculated. The results were statistically analyzed using unpaired two-way analysis of variance [Students' t-test]. The results revealed that all groups cured with Halogen LCU showed significantly less total gap area than those cured with LED LCU. The results also revealed that using exponential curing mode or using low modulus flowable resin composite showed superior marginal integrity of class V restoration cured with Halogen LCU, but no statistical significant difference was found in LED cured restorations. Therefore, it was concluded that in order to optimize clinical success, the polymerization protocol must be appropriate for a given light and composite system. Problems reto LED LCU may be corrected when more powerful LEDs are introduced and when LEDs with different spectral outputs are added to the LEDs currently used in dentistry. Clinical relevance. The use of initial low curing intensities and low-modulus composites as a liner or restorative material in class V cavities is strongly advocated when curing with Halogen LCU, but has no significant effect when curing with LED LCU