Update on Enamel Bonding Strategies

Optimal strategies for the application of an adhesive differ between enamel and dentin because of the differences in their composition. The development of adhesive systems has mainly focused on the bonding of dentin, rather than on the enamel, by etching with phosphoric acid (PA). Dental adhesive technologies continue to rapidly advance, and various adhesive systems have been developed since the study of Buonocore in 1955. He introduced the enamel acid-etch technique. Then, the etch-and-rinse (ER) system was developed, and subsequently, the self-etch (SE) system. Universal adhesives are a new generation of one-bottle SE adhesives that can be applied with either ER mode or SE mode, or a combined system involving selective enamel etching mode. Since the combination of PA etching and the SE system differs from conventional ER systems, the enamel bonding strategy should be carefully considered. This concise review of the literature on reliable enamel bonding strategies should prove helpful to clinicians to choose an appropriate adhesive system to achieve optimal clinical outcomes.

Quantitative particle analysis of particulate matter release during orthodontic procedures: A pilot study.

Introduction: Transmission of SARS-Cov-2 through aerosol has been implicated particularly in the presence of highly concentrated aerosols in enclosed environments. It is accepted that aerosols are produced during a range of dental procedures, posing potential risks to both dental practitioners and patients. There has been little agreement concerning aerosol transmission associated with orthodontics and associated mitigation. Methods: Orthodontic procedures were simulated in a closed side-surgery using a dental manikin on an acrylic model using composite-based adhesive. Adhesive removal representing debonding was undertaken using a 1:1 contra-angle handpiece and fast hand-piece with variation in air and water flow. The removal of acid etch was also simulated with use of combined 3-in-1 air water syringe to remove etch. An optical particle scanner and a spectrometer particle scanner were both to assess particulate matter ranging from 'very small' (0.08 - 0.26 um) to large (2.7 - 10 um). Results: Standard debonding procedure (involving air but no water) was associated with clear increase in the very small and small (0.26 - 0.9 um) particles, but only for a short period with no significant increases for other sizes. Debonding procedures without air appeared to produce similar levels of aerosol to standard debonding. Debonding in association with water tended to produce large increase in aerosol levels, producing particles of all sizes throughout the experiment. The use of water and a fast hand-piece led to the most significant increase in particles. Combined use of the 3-in-1 air water syringe did not result in any detectable increase in the aerosol levels. Conclusions: Particulate matter was released during orthodontic debonding, although the concentration and volume was markedly less than that associated with the use of a fast hand-piece. No increase in particulates was associated with prolonged use of a 3-in-1 air-water syringe. Particulate levels reduced to baseline levels over a short period (approx. 5 minutes). Further research within alternative, open environments and without air exchange systems is required.

Evaluation of shear bond strength of amalgam restorations repaired with composite resin by different surface treatments

Aim: Repairing amalgam restorations with composite resins is a clinical practice with many advantages. An effective adhesion is achieved between amalgam and composite by applied different surface treatment on amalgam surface. In this study, the effect of adhesive systems applied on amalgam surface on composite-amalgam connection was investigated. Methodology: Standard cavities were opened in 70 acrylic molds that had completed their polymerization and amalgams were placed in these cavities. Seven groups were randomly assigned to different surface treatments on amalgam. In group 1 only roughening with diamond bur , in group 2 acid etch, in group 3 acid application after roughening with diamond bur, in group 4 roughening with diamond bur and silane, in group 5 acid etch and silane, in group 6 roughening with diamond bur and Alloy Primer and finally 7. acid etch and Alloy Primer was applied in the samples. After the application of clearfil universal bond to all groups, composite resins were placed and polymerized. Shear bond strengths were tested with a Universal testing machine. Obtained data were evaluated by one way ANOVA and Tukey B tests. Results: In the statistical evaluation of the groups, the highest shear bond strength between amalgam-composite was seen in the 3rd group where both roughening with diamond bur and acid were applied together, and the lowest shear bond strength was seen in the first group with only roughening with diamond bur. The differences between the groups were statistically significant (p <0.05). Conclusion: The roughening of the amalgam surface affects the shear bond strength between amalgam and composite resin. These results obtained in vitro conditions should be supported with clinical studies. How to cite this article: Cangül S, Adıgüzel Ö, Erpaçal B, Ünal M, Acartürk M, Satıcı Ö. Evaluation of shear bond strength of amalgam restorations repaired with composite resin by different surface treatments. Int Dent Res 2019;9(3):105-10. Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Shear Bond Strength of Brackets Bonded with Self-Etching Primers Compared to Conventional Acid-Etch Technique: A Randomized Clinical Trial

Objectives: The purpose of this randomized clinical trial (RCT) was to compare the shear bond strength (SBS) of orthodontic brackets bonded to enamel with conventional acid-etch (AE) technique and self-etching primers (SEP). Materials and Methods: Twenty-two patients, requiring extraction of two bicuspids for orthodontic reasons, were recruited. In each individual, following blinding and allocation concealment, one intact premolar received conventional AE, whereas the contralateral premolar received SEP with a split-mouth design. Bonded brackets remained in the oral cavity for two months. Afterward, the teeth were extracted without debonding the brackets. SBS and adhesive remnant index (ARI) were measured using a Universal Instron machine and a stereomicroscope, respectively. Results: The mean SBS of the conventional AE and SEP groups was 9.53 and 9.20 MPa, respectively. Paired t-test showed no statistically significant difference between the two groups (P=0.096). Comparison of ARI between the two groups, using Wilcoxon test, indicated that significantly less adhesive remained on enamel with brackets bonded with SEP compared to brackets bonded with conventional AE (P<0.001) although the SBS was higher in the AE group. Conclusion: The present study indicated that although there is no significant difference in SBS between SEP and conventional AE for bonding orthodontic metal brackets, the amount of residual adhesive on the enamel surface is significantly less with SEP than with conventional AE. (IRCT registration number: IRCT201705099086N3).

Shear Bond Strength of Brackets Bonded with Self-Etching Primers Compared to Conventional Acid-Etch Technique: A Randomized Clinical Trial

Objectives: The purpose of this randomized clinical trial (RCT) was to compare the shear bond strength (SBS) of orthodontic brackets bonded to enamel with conventional acid-etch (AE) technique and self-etching primers (SEP). Materials and Methods: Twenty-two patients, requiring extraction of two bicuspids for orthodontic reasons, were recruited. In each individual, following blinding and allocation concealment, one intact premolar received conventional AE, whereas the contralateral premolar received SEP with a split-mouth design. Bonded brackets remained in the oral cavity for two months. Afterward, the teeth were extracted without debonding the brackets. SBS and adhesive remnant index (ARI) were measured using a Universal Instron machine and a stereomicroscope, respectively. Results: The mean SBS of the conventional AE and SEP groups was 9.53 and 9.20 MPa, respectively. Paired t-test showed no statistically significant difference between the two groups (P=0.096). Comparison of ARI between the two groups, using Wilcoxon test, indicated that significantly less adhesive remained on enamel with brackets bonded with SEP compared to brackets bonded with conventional AE (P<0.001) although the SBS was higher in the AE group. Conclusion: The present study indicated that although there is no significant difference in SBS between SEP and conventional AE for bonding orthodontic metal brackets, the amount of residual adhesive on the enamel surface is significantly less with SEP than with conventional AE. (IRCT registration number: IRCT201705099086N3).