Effects of different surface treatments and adhesive self-etch functional monomers on the repair of bulk fill composites: A randomised controlled study

Effects of silane coupling treatment on the clinical performance of direct repaired resin-based composite (RBC) restorations with or without prior surface sandblasting: A randomized controlled trial

OBJECTIVE

To evaluate the effects, of using silane coupling agent within the procedures of repairing old composite restorations with or without sandblasting their surfaces, on the clinical performance of repaired composite restorations.

METHODS

The study involved repairing 130 Class I and II defective composite restorations. After recurrent caries removal, the repair process included etching with 37 % phosphoric acid, Adper Single Bond 2 application for bonding and Filtek Z250 composite for restoring all defects. The restoration surfaces were subjected to one of the following additional surface treatments within the repair process: Control: No additional treatment; the Silane-Adhesive treatment: A separate step involved the application of a silane coupling agent after acid etching; and the Sandblast-Silane-Adhesive treatment: included intra-oral sandblasting of old composite surfaces followed by silane application. Two calibrated examiners evaluated all repaired restorations according to a modified USPHS criteria after 6 months. Comparisons of the clinical performance between the treatment groups were made using Chi-square test, while responses to cold tests before and after repair treatment were made using Wilcoxon's Signed Rank's (α = 0.05).

RESULTS

Of 130 cases, only 116 cases turned up for evaluation. The primary reasons for composite repair were recurrent caries and anatomical deficiencies. No statistically significant differences were found between the groups for all clinical criteria (p > 0.05). The control group experienced one total and two partial retention losses.

CONCLUSIONS

The application of a silane coupling agent, with or without intra-oral sandblasting, demonstrated no improvement on the clinical performance of repaired posterior composites after 6-months.

CLINICAL SIGNIFICANCE

Surface treatment of defective composite restorations using silane with intra-oral sandblasting within their repair process offered marginal improvement in their clinical performance over conventional etching technique, but insignificantly so. Repair reduced exaggerated cold test responses and eliminated POS within 6-months. Repair reduces cold sensitivity and promotes restoration longevity. This clinical trial was registered at ClinicalTrials.gov with the registration number NCT06005571.

Repair bond strength of bulk-fill composites: influence of different primers and direction of debonding stress

Background

The purpose of this in vitro study was to evaluate the effect of different adhesion primers on the repair bond strength of bulk-fill resin composite and short-term hydrolytic stability of the repair interface before and after accelerated aging. In addition, direction of debonding stress was examined.

Materials and methods

Bulk-fill substrates were aged in water for 14 days at 37 °C. Smooth resin composite surfaces were prepared for the substrates with a superfine grinding paper (FEPA #500, #1200, #2000). Test specimens were produced by attaching bulk-fill composite to the substrate surfaces, using three different primer/bonding systems. Specimens were aged 24 h at 37 °C in water, or thermal cycled (5-55 °C/5,000 cycles). Subsequently, shear bond strength and micro-tensile bond strength were evaluated. In total there were 60 specimens for the shear bond strength and 60 specimens for the micro-tensile bond strength measurements (30 stored in water 24 h, 30 thermal cycled, n = 10 in each primer/bonding mode).

Results

The mean shear bond strength was 9.1-13.1 MPa after 24 h water storage and 6.9-10.7 MPa after thermal cycling. The mean micro-tensile bond strength was 28.7-45.8 MPa after 24 h water storage and 22.7-37.9 MPa after thermal cycling.

Conclusion

The Ceramic primer (silane containing) seems to perform better than the three-step etch and rinse adhesive or the Composite primer. Shear-type stress had an adverse effect on the repair bond strength of bulk-fill resin composites.

Randomized prospective clinical trial of class II restorations using flowable bulk-fill resin composites: 4-year follow-up

OBJECTIVES

This randomized, prospective, and split-mouth study aimed to evaluate flowable bulk-fill resin composites in class II restorations, comparing it with a conventional layering technique after 4-year follow-up.

MATERIALS AND METHODS

Fifty-three subjects received three class II restorations according to the restorative systems: conventional microhybrid composite resin (PA - Peak Universal + Amelogen Plus, Ultradent); flowable bulk-fill and nanoparticulate composite resins (ABF - Adper Single Bond 2 + Filtek Bulk Fill Flow + Filtek Z350XT, 3M/Espe); and flowable bulk-fill and microhybrid composite resins, (XST - XP Bond + SDR + TPH3, Dentsply). The clinical performance and interproximal contacts were evaluated. Statistical analyses were performed using the Kaplan-Meier, equality test of two proportions, Friedman, Wilcoxon, Kruskal-Wallis, Mann-Whitney, and Logistic regression analysis tests (alpha = 0.05).

RESULTS

In total, 106 restorations were evaluated at 4 years. Both systems with bulk-fill composites presented higher marginal discoloration than PA. About surface texture, ABF restorative system showed superior bravo scores being statistically similar to XST. Better performance for wear and surface staining was found for XST restorative system. All restorative systems resulted in the decreased interproximal contacts, occurring early for XST.

CONCLUSIONS

The restorative systems that used flowable bulk-fill resin composites showed satisfactory clinical performance compared with conventional resin composite after 4 years. All restorative systems had decreased proximal contact after 4 years.

CLINICAL RELEVANCE

Initial marginal discoloration was observed in more than 50% of class II restorations performed with restorative systems that used flowable bulk-fill resin composite. All restorative systems had decreased proximal contact strength over time.

Teaching of the repair of defective composite restorations in Middle Eastern and North African Dental Schools

OBJECTIVES

To evaluate the status of teaching of repair of defective resin-based composite restorations in dental schools in the Middle Eastern and North African (MENA) countries.

METHODS

A validated 14-item questionnaire was mailed to the directors of the operative/restorative dentistry department in 40 MENA dental schools. Data were collected on teaching, including whether the repair of resin-based composite restorations was part of the dental school curriculum; the rationale behind the teaching; how techniques were taught, indications for repair, operative techniques, materials used, patient acceptability and expected longevity of the repair procedure.

RESULTS

Thirty-two schools responded to the survey (response rate of 80%). Twenty-two (69%) schools reported the teaching of resin-based composite repairs as an alternative to the replacement of restorations. Of the schools not teaching repairs, 80% indicated that they plan to include this topic in the curriculum within the next five years. Most schools taught theoretical and practical aspects of repair at a clinical level only. Two-thirds of schools reported tooth substance preservation being the main reason for teaching repair techniques. The main indications for repair treatment were marginal defects (59%), followed by partial loss of restoration (56%). Most schools that performed repairs reported high patient acceptability. Considerable variation was noted in relation to expected longevity of resin- based composite repairs.

CONCLUSIONS

The repair of defective resin-based composite restorations is actively taught within most of the surveyed schools. Advantages of repair, compared to replacement include minimum intervention, preservation of tooth structure, and savings of time and cost.

CLINICAL SIGNIFICANCE

The decision between replacing or repairing a defective resin-based composite restoration in the MENA region tends to be based on clinicians' subjective experience and judgement. However, to further enhance the teaching of resin-based composite repair standardised guidelines need to be developed based on existing evidence.