Evaluation of enamel roughness after the removal of brackets bonded with different materials: In vivo study

Structural and Color Alterations of Teeth following Orthodontic Debonding: A Systematic Review

AIM

The objective of this study was to explore the effects of fixed orthodontic appliances on enamel structure by assessing microfractures, surface roughness, and alterations in color.

METHODS

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic search of online databases was conducted using the keywords 'enamel' AND 'orthodontic debonding'. Eligibility criteria included both in vivo and ex vivo clinical trials conducted on human teeth.

RESULTS AND DISCUSSION

A total of 14 relevant papers were analyzed. Various instruments and techniques were utilized across different studies to assess surface roughness, color change, and surface fractures.

CONCLUSIONS

The findings of this study suggest that ceramic brackets may lead to an increase in enamel fractures, particularly during bracket removal. The surface roughness of enamel exhibits variability depending on the adhesive substance and polishing methods used post-removal. Fixed orthodontic appliances could induce changes in enamel color, which may be alleviated by the use of nano-hydroxyapatite or specific polishing techniques. Further research is necessary to identify effective strategies for managing these color changes and improving the overall outcomes of fixed orthodontic treatment.

Assessment of enamel surface roughness and hardness with metal and ceramic orthodontic brackets using different etching and adhesive systems: An in vitro study

Background

This study aimed to evaluate enamel surface roughness and microhardness following the use of different bracket materials (metal or ceramic), etchants (total- and self-etchants), and adhesive systems (precoated or flash-free).

Method

A total of 99 extracted human premolars were selected for the analysis. The surface roughness was first assessed (roughness control). One specimen from each subgroup was examined using a scanning electron microscope to illustrate the surface topography. Eighty-eight teeth were prepared using total- or self-etchants and bonded to precoated or flash-free adhesive metal or ceramic brackets. The remaining 11 specimens were not bonded to brackets (microhardness controls). The brackets were debonded after immersion in distilled water for 24 h. The specimens were again scanned for surface roughness and topography imaging. Finally, the microhardness was assessed using a micro-Vickers hardness test at a force of 200 g for 10 s.

Result

An overall statistically significant increase in surface roughness and reduced surface microhardness were observed in all experimental groups when compared with those in the control groups. The etchant type was the only variable found to contribute to the measured surface properties, with increased roughness and reduced microhardness introduced by total-etching compared to those by self-etching.

Conclusion

Orthodontic brackets introduced a significant increase in enamel surface roughness and reduce microhardness compared with untreated enamel, regardless of the bracket material, etchant type, and adhesive system. The etchant type was the only variable contributing to these changes, with total etching having a more pronounced effect.

Effects of Acidic Environments on Dental Structures after Bracket Debonding

Brackets are metallic dental devices that are very often associated with acidic soft drinks such as cola and energy drinks. Acid erosion may affect the bonding between brackets and the enamel surface. The purpose of this study was to investigate the characteristics of brackets' adhesion, in the presence of two different commercially available drinks. Sixty human teeth were divided into six groups and bonded with either resin-modified glass ionomer (RMGIC) or resin composite (CR). A shared bond test (SBS) was evaluated by comparing two control groups with four other categories, in which teeth were immersed in either Coca-Cola^TM or Red Bull^TM energy drink. The debonding between the bracket and enamel was evaluated by SEM. The morphological aspect correlated with SBS results showed the best results for the samples exposed to artificial saliva. The best adhesion resistance to the acid erosion environment was observed in the group of teeth immersed in Red Bull^TM and with brackets bonded with RMGIC. The debonded structures were also exposed to Coca-Cola^TM and Red Bull^TM to assess, by atomic force microscopy investigation (AFM), the erosive effect on the enamel surface after debonding and after polishing restoration. The results showed a significant increase in surface roughness due to acid erosion. Polishing restoration of the enamel surface significantly reduced the surface roughness that resulted after debonding, and inhibited acid erosion. The roughness values obtained from polished samples after exposure to Coca-Cola^TM and Red Bull^TM were significantly lower in that case than for the debonded structures. Statistical results evaluating roughness showed that Red Bull^TM has a more erosive effect than Coca-Cola™. This result is supported by the large contact surface that resulted after debonding. In conclusion, the prolonged exposure of the brackets to acidic drinks affected the bonding strength due to erosion propagation into both the enamel-adhesive interface and the bonding layer. The best resistance to acid erosion was obtained by RMGIC.

Mechanical Properties of Orthodontic Cements and Their Behavior in Acidic Environments

The present research is focused on three different classes of orthodontic cements: resin composites (e.g., BracePaste); resin-modified glass ionomer RMGIC (e.g., Fuji Ortho) and resin cement (e.g., Transbond). Their mechanical properties such as compressive strength, diametral tensile strength and flexural strength were correlated with the samples' microstructures, liquid absorption, and solubility in liquid. The results show that the best compressive (100 MPa) and flexural strength (75 Mpa) was obtained by BracePaste and the best diametral tensile strength was obtained by Transbond (230 MPa). The lowestvalues were obtained by Fuji Ortho RMGIC. The elastic modulus is relatively high around 14 GPa for BracePaste, and Fuji Ortho and Transbond have only 7 GPa. The samples were also subjected to artificial saliva and tested in different acidic environments such as Coca-Cola and Red Bull. Their absorption and solubility were investigated at different times ranging from 1 day to 21 days. Fuji Ortho presents the highest liquid absorption followed by Transbond, the artificial saliva has the best absorption and Red Bull has the lowest absorption. The best resistance to the liquids was obtained by BracePaste in all environments. Coca-Cola presents values four times greater than the ones observed for artificial saliva. Solubility tests show that BracePaste is more soluble in artificial saliva, and Fuji Ortho and Transbond are more soluble in Red Bull and Coca-Cola. Scanning electron microscopy (SEM) images evidenced a compact structure for BracePaste in all environments sustaining the lower liquid absorption values. Fuji Ortho and Transbond present a fissure network allowing the liquid to carry out in-depth penetration of materials. SEM observations are in good agreement with the atomic force microscopy (AFM) results. The surface roughness decreases with the acidity increasing for BracePaste meanwhile it increases with the acidity for Fuji Ortho and Transbond. In conclusion: BracePaste is recommended for long-term orthodontic treatment for patients who regularly consume acidic beverages, Fuji Ortho is recommended for short-term orthodontic treatment for patients who regularly consume acidic beverages and Transbond is recommended for orthodontic treatment over an average time period for patients who do not regularly consume acidic beverages.

Evaluating changes in the color and luminosity of dental enamel after orthodontic treatment: A clinical study

The aims of this clinical study were to evaluate the Color change - ΔE (based on spectrophotometry and visual analysis) and luminosity - L* (based on spectrophotometry) of dental enamel surface (after orthodontic treatment) around the area where orthodontic brackets were fixed, based on different cementing materials such as a resin (R group) and resin-modified glass ionomer cement (RMGIC group). The split-mouth study initially comprised 14 patients. Orthodontic brackets were fixed to the upper central incisors with resin or RMGIC. The color of the buccal surface of each tooth was measured through spectrophotometry and visual examination before the bracket-fixation process. Four individuals were excluded during the follow-up; thus 10 patients were evaluated (n=10). Brackets were removed after 12 months of orthodontic treatment, tooth color measurement and visual examination were performed again, and Adhesive Remaining Index (ARI) was also measured. ΔE and L* results were subjected to Student's t-test and by repeated-measures analysis of variance, respectively (α=0.05). ARI data were analyzed in percentages. There was statistically significant difference in ΔE between groups; the R group showed statistically higher values of L* after orthodontic treatment. ARI of 2 and 3 prevailed in the RMGIC group, whereas the R group presented 0 and 1. After orthodontic treatment, the RMGIC group presented smaller changes in ΔE, and the increase in the white scale was observed on the enamel surface around the area where brackets were fixed in the R group. The visual analysis did not show color change on the evaluated teeth.