Can chemical softening agents minimize cavity enlargement during removal of failed anterior resin composite restorations?

Effect of Different Chemical Solvents on Bond Strength of Orthodontic Brackets: An In Vitro Study

AIM

The purpose of the present study was to evaluate the impact of various chemical solvents on bond strength of orthodontic brackets.

MATERIALS AND METHODS

One hundred healthy human premolars with undamaged buccal surfaces that were extracted for orthodontic purposes were gathered. Using 37% orthophosphoric acid, primer, and Transbond XT adhesive, ceramic 0.018" × 0.022" slot orthodontic brackets were adhered to the tooth surface. Following thermocycling, all samples were divided into four groups, with 25 samples in each group: group I: control; group II: application of ethanol; group III: application of acetone; and group IV: application of dimethyl sulfoxide (DMSO). Following the debonding tests, a double-ocular stereomicroscope was used to inspect the tooth surfaces. Additionally, adhesive remnant index (ARI) values were evaluated at 40× magnification. Data were recorded and statistically analyzed.

RESULTS

The bond strength was lesser in acetone applied group (16.18 ± 3.64) followed by DMSO applied group (22.08 ± 2.86), ethanol applied group (24.36 ± 4.02), and control group (27.14 ± 3.68). There was a highly significant difference found between the chemical solvents group. The ARI score 3 was present in control (12%), ethanol (8%), and DMSO (4%), and it was absent in acetone applied group. The ARI score 0 was more in acetone applied group (24%).

CONCLUSION

The present study concluded that the reduced debonding force was found with the application of acetone solvent followed by DMSO, ethanol, and control groups. Applying acetone can be a substitute technique to help with ceramic bracket debonding.

CLINICAL SIGNIFICANCE

Orthodontic bracket debonding cannot occur without shear bond strength (SBS). The need for an ideal debonding technique for ceramic brackets without negative consequences arises from the risk of enamel damage that frequently follows the process. Acetone treatment prior to ceramic bracket debonding could be an alternate clinical technique to preventing enamel damage and facilitating debonding. How to cite this article: Bhushan R, Singh S, Sam G, et al. Effect of Different Chemical Solvents on Bond Strength of Orthodontic Brackets: An In Vitro Study. J Contemp Dent Pract 2023;24(12):940-943.

White-opaque flowable composite liner as a depth marker in composite restorations prevents tooth substance loss in filling removal: a randomized double-blinded in vitro study

OBJECTIVES

Removal of esthetic restorations leads to loss of tooth structure and the extent of the loss is difficult to estimate due to exact-shade matching. This randomized double-blinded in vitro study aimed examining the influence of a white-opaque flowable composite depth marker as an optical removal aid for tooth substance preservation and shortened restoration removal time.

MATERIALS AND METHODS

Class II cavities (n = 100) in extracted healthy mandibular molars (n = 50, two runs) were prepared, filled, and the restoration removed. Tooth weight and volume (before and after) and removal time were measured and remnants visually documented. An optimal tooth shade-matched flowable composite liner was used as control.

RESULTS

Tooth structure loss was significantly lower using a white-opaque liner. Mean values for volume/weight loss were 0.037 ± 0.030 g and 0.016 ± 0.005 cm3 (p < 0.01) for white-opaque liner; 0.067 ± 0.000 g and 0.028 ± 0.003 cm3 (p < 0.01) for tooth-colored composite. Removal time and number of pulp chamber perforations showed no significant differences (p = 0.80).

CONCLUSIONS

Within the limitations of this randomized double-blinded in vitro study, the use of a white-opaque flowable liner as a depth marker may provide the practitioner a visual aid in the replacement of a composite restoration and may protect against tooth structure loss.

CLINICAL RELEVANCE

When restoration replacement is indicated, removal of esthetic restorations often causes tooth structure loss due to difficult optical color matching. Using a white-opaque flowable liner as a depth marker clinically aids in restoration removal and protects against tooth structure loss.

In vitro evaluation of enamel surface roughness and morphology after orthodontic debonding: Traditional cleanup systems versus polymer bur

INTRODUCTION

The primary aim of this randomized in vitro study was to compare the effectiveness of carbide, fibreglass and polymer burs on resinous remnant removal after bracket debonding, by the evaluation of enamel surface roughness and morphology. The secondary objective was to compare the time dispended on the procedures.

METHODS

The buccal surfaces of 28 bovine incisors were analysed by a profilometer to initial roughness measurement (Ra-T1). Brackets were bonded with a light-cured resin and debonded with a debonding plier. The samples were randomly divided into four groups, according to the bur used (n=7): A-Tungsten carbide; B-Fibreglass; C-Polymer; D-Polymer with 75% ethanol pre-treatment. The second roughness measurements were made after resin removal (Ra-T2). Time for removal procedures was also recorded. The third measurements were made after polishing (Ra-T3). Scanning Electronic Microscopy was performed in two samples of each group: after resin removal and after polishing. Results of roughness and time measurements were statically analysed by analysis of variance with post-hoc Bonferroni.

RESULTS

After polishing, tungsten carbide (P=0.1555) and fibreglass burs provided final surface roughness statistically similar to the baseline condition (P=1.0000). Yet, polymer burs, associated (P<0.0001) or not to alcohol (P<0.0001), provided surface roughness significantly higher when compared to baseline values. Polymer burs were more time-consuming on resinous remnant removal than tungsten carbide and fibreglass burs (P<0.05).

CONCLUSION

Polymer burs were less effective and more time-consuming to remove the remaining resin than tungsten carbide and fibreglass burs. The polishing step created smoother surfaces regardless of the burs used for resin removal.

Bonded amalgams and their use in clinical practice

There has been a move in recent years for operative dentists to use the benefits of adhesive technology when placing dental amalgam restorations. This paper describes the potential advantages of the bonded amalgam technique. These benefits include decreased microleakage between the cavity wall and the restorative material. This, in turn, may decrease post-operative sensitivity, pulpal inflammation and the incidence of recurrent caries. Extra retention for the restoration may also be provided and the need for cavities to rely on traditional retention and resistance form may be decreased or even eliminated, thus conserving precious tooth tissue. If the restoration is bonded then flexure during function in teeth may be decreased and, in the case of teeth exhibiting a cracked cusp, this may alleviate or eliminate symptoms. Bonding may also provide support to weakened tooth tissue which otherwise would have to be removed, so rendering cavities more conservative, and may increase the fracture resistance of the tooth. Clinical examples are included to illustrate some of these benefits.

CLINICAL RELEVANCE

The use of adhesives to bond amalgam to tooth tissue offers potential advantages, although some of the current evidence is equivocal about their routine use.