Is there one optimal repair technique for all composites?

Evaluation of Shear Bond Strengths of 3D Printed Materials for Permanent Restorations with Different Surface Treatments

The development of high-filled 3D printing resin necessitates a bonding protocol for dental indirect restorations to achieve optimal bond strength after cementation. This study evaluates shear bond strengths of high-filler 3D printed materials for permanent restorations with various surface treatments. Rodin Sculpture 1.0 (50% lithium disilicate fillers) and 2.0 Ceramic Nanohybrid (>60% zirconia and lithium disilicate fillers) were tested, with Aelite All-Purpose Body composite resin as control. Samples were prepared, post-cured, and sandblasted with alumina (25 µm). Surface roughness was analyzed using an optical profilometer. Two bonding protocols were compared. First, groups were treated with lithium disilicate silane (Porcelain Primer) or zirconia primer (Z-Prime Plus) or left untreated without a bonding agent. Beam-shaped resin cement (DuoLink Universal) specimens were bonded and stored in a 37 °C water bath. Second, additional sets of materials were coated with a bonding agent (All-Bond Universal), either followed by silane application or left untreated. These sets were then similarly stored alongside resin cement specimens. Shear bond tests were performed after 24 h. SEM images were taken after debonding. One-Way ANOVA and post hoc Duncan were performed for the statistical analysis. Rodin 1.0 exhibited increased adhesive failure with silane or zirconia primer coating, but significantly improved bond strengths with bonding agent application. Rodin 2.0 showed consistent bond strengths regardless of bonding agent application, but cohesive failure rates increased with bonding agent and filler coating. In all groups, except for Rodin 1.0 without bonding agent, silane coating increased cohesive failure rate. In conclusion, optimal shear bond strength for high-filler 3D printing materials can be achieved with silane coating and bonding agent application.

Effects of different surface treatments on surface topography and bond strength in the repair of fiber-reinforced dentin composite

OBJECTIVE

This study aimed to evaluate the effects of different surface treatments on the repair bond strength between a fiber-reinforced dentin composite and a posterior composite.

METHODS

Forty fiber-reinforced dentin composite resin blocks (4 mm × 4 mm × 4 mm) were separated into eight groups (n = 5) according to the surface preparation methods: (G1) negative control group, (G2) adhesive application, (G3) 50% dimethylsulfoxide (DMSO) application, (G4) 50% DMSO + adhesive application, (G5) 37% phosphoric acid etch + adhesive application, (G6) air abrasion + adhesive application, (G7) 37% phosphoric acid etch + 50% DMSO application + adhesive application, and (G8) air abrasion +50% DMSO application + adhesive application group. The composite surfaces were repaired in two layers with a posterior composite. Composite sticks were subjected to a micro tensile bond strength (μTBS) test. Fractured surfaces were evaluated using a stereomicroscope (×25). Short fiber-reinforced composite samples' surfaces were investigated by scanning electron microscope (SEM). Shapiro Wilk, one-way ANOVA, and Tukey HSD tests were used for statistical evaluation.

RESULTS

The highest average (μTBS) values were observed in G8, whereas the lowest mean μTBS values were evident in the G1 group. Statistically significant μTBS values were found in all adhesive-applied groups when compared with the negative control group. Notably, the application of 50% DMSO without adhesive did not lead to a statistically significant increase in μTBS values. SEM images demonstrated that acid etching partially eliminated residues on the composite surface, while air abrasion had a detrimental effect on the integrity of fiber structures.

CONCLUSION

In the repair of fiber-reinforced dentin composite with a posterior composite, adhesive application is an effective approach. The treatment of 50% DMSO without adhesive did not confer a statistically significant advantage, and the supplemental use of acid etch or air abrasion did not show an additional benefit compared to adhesive-only repairs.

CLINICAL SIGNIFICANCE

Adhesive application emerges as a potent and effective strategy for the repair of bur-roughened fiber-reinforced dentin composites. With its limitations, the study highlights the efficacy of adhesive-only repairs without the necessity for additional surface treatments.

Repairability of aged dimethacrylate-free ORMOCER-based dental composite resins with different surface roughening methods and intermediate materials

STATEMENT OF PROBLEM

The repair of damaged composite resin restorations has been recommended as a conservative treatment option. However, a reliable protocol for repairing ORMOCER-based restorations is lacking.

PURPOSE

The purpose of this in vitro study was to investigate the effect of different surface roughening methods, repair composite resins, and intermediate materials on the repair bond strength of a dimethacrylate-free ORMOCER-based composite resin.

MATERIAL AND METHODS

Cylindrical composite resin specimens (Admira Fusion) were roughened by using hydrofluoric acid (HF) or a diamond rotary instrument. In both groups, 4 types of intermediate materials were used (Monobond-S, Clearfil SE bond [second bottle], Clearfil Universal bond, GC Composite Primer), and then half of the specimens were repaired with a similar composite resin, and the other half with dimethacrylate composite resin (Clearfil-APX). The specimens (n=20) were then subjected to repair bond strength and failure mode evaluation. The data were analyzed by using the Weibull test, 3-way and 1-way ANOVA, and the Tukey honestly significant difference (HSD) test (α=.05).

RESULTS

All variables, including the surface roughening method, intermediate material, and repair composite resin, had a significant effect on repair bond strength (P<.001). The lowest repair bond strength values were obtained in the group roughened with HF, prepared with Monobond-S, and repaired with Admira Fusion, and the highest values were obtained in the group roughened with a rotary instrument, prepared with GC Composite Primer, and repaired with Clearfil APX (P<.05). All experimental groups had a lower bond strength than the cohesive and control groups (P<.05). In all experimental groups, the predominant failure modes were adhesive and mixed.

CONCLUSIONS

The use of a diamond rotary instrument was a more reliable method of creating roughness, and different intermediate materials based on the clinical situation can be used to repair dimethacrylate-free ORMOCER-based composite resin with similar or different composite resins. However, in general, the highest repair bond strengths were achieved with Clearfil APX-repaired specimens.

Scoping review: Effect of surface treatments on bond strength of resin composite repair

OBJECTIVE

to evaluate the existing evidence on surface treatment techniques employed in resin composite repair and their effect on the repair short- and long-term bond strength.

DATA AND SOURCE

This scoping review was performed under the PRISMA-ScR guidelines for scoping reviews and registered on the Open Science Framework platform.

STUDY SELECTION

A systematic search was conducted in PubMed, Embase, and Scopus and grey literature up to September 2022 without language or date restriction. In vitro studies comparing mechanical surface and/or chemical treatments on repair bond strength of resin composite were included. Studies evaluating experimental adhesive systems or resin composites were excluded. Selection of studies and data extraction were performed. Data from selected studies was qualitatively analyzed.

RESULTS

A total of 76 studies were included in the qualitative analysis. Among the mechanical treatments, alumina blasting was the most frequently used, followed by silica coating and diamond bur. As for chemical treatments, dentin bonding systems were the most frequently evaluated, followed by universal adhesive systems and silane/ceramic primer. The combination of mechanical and chemical pre-treatments increased the repair bond strength of resin composite in both short- and long-term simulated aging scenarios. The evidence obtained from the included studies was classified as moderate quality, mainly due to the medium risk of bias observed across most of the studies.

CONCLUSION

The techniques used to treat the surface of resin composites for repair are diverse. Incorporating a combination of mechanical and chemical pre-treatments resulted in superior repair bond strength of resin composite materials under both short- and long-term simulated aging conditions.

CLINICAL SIGNIFICANCE

The analysis of evidence revealed significant variability among protocols for repairing resin composites. Utilizing both mechanical and chemical pre-treatment methods is important for enhancing the bond strength of resin composites during both short- and long-term simulated aging situations.

Comparative Evaluation of the Repair Bond Strength of Dental Resin Composite after Sodium Bicarbonate or Aluminum Oxide Air-Abrasion

The dental prophylactic cleaning of a damaged resin-based composite (RBC) restoration with sodium bicarbonate can change the surface characteristics and influence the repair bond strength. The purpose of this study was to compare the effect of sodium bicarbonate (SB) and aluminum oxide (AO) surface treatments on the microtensile bond strength (µTBS) of repaired, aged RBC. Bar specimens were prepared from microhybrid RBC and aged in deionized water for 8 weeks. Different surface treatments (AO air-abrasion; SB air-polishing), as well as cleaning (phosphoric acid, PA; ethylene-diamine-tetraacetic-acid, EDTA) and adhesive applications (single bottle etch-and-rinse, ER; universal adhesive, UA), were used prior to the application of the repair RBC. Not aged and aged but not surface treated RBCs were used as positive and negative controls, respectively. The repaired blocks were cut into sticks using a precision grinding machine. The specimens were tested for tensile fracture and the µTBS values were calculated. Surface characteristics were assessed using scanning electron microscopy. AO-PA-UA (62.6 MPa) showed a 20% increase in µTBS compared to the NC (50.2 MPa), which proved to be the most significant. This was followed by SB-EDTA-UA (58.9 MPa) with an increase of 15%. In addition to AO-PA-UA, SB-EDTA-UA could also be a viable alternative in the RBC repair protocol.

Effect of surface treatment on the repair bond strength of OMNICHROMA and Charisma Diamond ONE resin composites bonded to variable substrates

Objectives

To compare repair bond strength of OMNICHROMA and Charisma Diamond ONE resin composites bonded to variable composite substrates. Also, to evaluate the influence of different surface treatments on repair bond strength.

Methods

A total of 80-disc shaped specimens was fabricated using two resin based composite materials; IPS Empress Direct Enamel and OptiShade (n = 40). Substrate discs were thermocycle 5000 cycles then each substrate material was subdivided based on the surface treatment into two groups; air particle abrasion (APA) and silicon carbide grinding (SiCr) both groups followed by phosphoric acid etching. All groups received a single bond universal adhesive application prior to repairing with composite, in a smaller disc shape. All specimens were thermocycled for 10,000 cycles prior to shear bond strength testing and subsequent failure analysis. Statistical analyses were conducted and the level of statistical significance was set at 0.05.

Results

The comparison of mean values (considering the combination of the two types of substrates, surface treatments and repairing materials) showed a highly statistically significant difference in the shear bond strength among the eight study groups (p < 0.0001). The highest value of mean shear bond strength was associated with OptiShade substrates repaired by Diamond ONE (38.6 ± 2.4). Meanwhile, the lowest value was recorded for the SiCr treated OptiShade group repaired by Diamond ONE (13.6 ± 2.3). The failure analysis revealed that cohesive mode of failure was the most predominant.

Conclusion

Omnichroma showed higher repair bond strength values with SiCr surface treatment. Meanwhile, Charisma Diamond ONE had better bond strength with APA. Surface pretreatment had a significant impact on the repair bond strength where APA groups had significantly higher values compared to SiCr groups. Clinical Significance: Within the limitation of the present study; APA is recommended as surface pretreatment for improved bond strength in restorative composite repairs.

The Effect of Morpholine on Composite-to-Composite Repair Strength Contaminated with Saliva

The aim of this study was to specifically explore the effects of morpholine on chemical surface treatments of aged resin composites contaminated with saliva to new resin composite repair strength. One hundred and thirty five resin composite specimens were fabricated and thermocycled to replicate an aged resin composite. These aged resin composites were randomly separated into nine groups (n = 15) depending on the various surface contaminants and surface treatment techniques. These groups were as follows: group 1—no surface treatment; group 2—no saliva + adhesive agent; group 3—no saliva + morpholine + adhesive agent; group 4—no saliva + morpholine; group 5—saliva; group 6—saliva + adhesive agent; group 7—saliva + morpholine + adhesive agent; group 8—saliva + morpholine; and group 9—saliva + phosphoric acid + adhesive agent. A mold was covered on the top of the specimen center and then filled with resin composite. The shear bond strengths and failure modes were examined. The collected data was analyzed using one-way ANOVA, and the significance level was determined using Tukey’s test. Group 5 (3.31 ± 0.95 MPa) and group 6 (4.05 ± 0.93 MPa) showed the lowest bond strength statistically, while group 3 (23.66 ± 1.35 MPa) and group 7 (22.88 ± 1.96 MPa) showed the most significantly high bond strength. The bond strength in group 2 (16.41 ± 1.22 MPa) was significantly different from that in group 1 (9.83 ± 1.13 MPa), group 4 (10.71 ± 0.81 MPa), and group 8 (10.36 ± 1.53 MPa), while group 9’s (17.31 ± 1.48 MPa) SBS was not significantly different. In conclusion, the application of morpholine on aged resin composite with or without contamination with saliva prior to the application of the adhesive agent increased the bond strength of aged resin composite repaired with new resin composite (p < 0.05).

Effect of different surface pretreatment methods on repair bond strength of resin composite subjected to pH-cycling

Objectives: The aim of this study was to evaluate the effect of two different repair methods (Er:YAG laser and bur) with or without silane application on the microtensile bond strength of a nanohybrid resin composite aged with two different aging methods (pH cycling and thermocycling). Material and Method: Resin composite blocks (Clearfil Majesty Esthetic, Kuraray, Japan) were randomly assigned into two groups for aging process: (a) pH cycling (b) thermocycling (5,000 cycles). After aging, the blocks were assigned to one of the following repair procedures: (1) Er:YAG laser (LightWalker STE-E, Fotona Medical Lasers, Ljubljana, Slovenia) (2) Er:YAG laser+silane (3) bur (4) bur+silane and (5) no-pretreatment group and (6) Cohesive control (cohesive strength of the resin). Resin composite (Clearfil Majesty Esthetic) was bonded to the conditioned substrates incrementally and light polymerized. Repaired samples were thermocycled (5.000 cycles). The microtensile bonding test was performed. The data were analyzed using Scheirer-Ray-Hare, Kruskal-Wallis Mann-Whitney U tests, Chi-square and Z tests with Bonferroni correction (p=0.05). Results: No statistically significant difference was found between the aging methods applied to filling material (p=0.821) and the interaction of applied surface treatments and aging (p=0.289). All repair procedures achieved bond strength values higher than the no-pretreatment group but they did not reach the resin composite’s cohesive bond strength. Failure modes distribution was found statistically different according to repair procedure and also aging methods (p

Silanizing Effectiveness on the Bond Strength of Aged Bulk-Fill Composite Repaired After Sandblasting or Bur Abrasion Treatments: An in vitro Study

Objective

To measure the repair shear bond strength (SBS) of an aged bulk-fill composite after different mechanical (diamond bur vs sandblasting) and chemical (universal adhesive with or without a previous silanization) surface treatments.

Materials and Methods

Bulk-fill composite (Filtek One Bulk Fill, 3M ESPE) was used to construct seventy-two specimens aged through 10,000 thermal cycles. The specimens were allocated into two groups (n = 36 each) according to the mechanical roughening: Db, treated with a diamond bur, and Sb, treated by sandblasting. Each group was further subdivided into three subgroups (n = 12 each) according to the chemical conditioning: Db-only and Sb-only, unconditioned specimens; Db-U and Sb-U, specimens were conditioned with silane-containing universal adhesive (Scotchbond Universal adhesive, 3M ESPE); and Db-S-U and Sb-S-U, specimens were conditioned with a silane agent (Prosil, FGM) before employing the universal adhesive. The same composite material was used for repair. An additional reference group was constructed to measure the cohesive strengths of the bulk-fill composite. SBS testing was performed using a universal testing machine at a crosshead speed of 1 mm/min, and the failure modes were evaluated by stereomicroscope. The surface topography of resin composite after roughening was assessed by scanning electron microscopy. SBS data were statistically analyzed by ANOVA, Tukey’s test and independent t-test.

Results

The significantly highest SBS was recorded in the reference group (P ≤ 0.05). Sb-only obtained significantly higher SBS than Db-only (P < 0.001). No significant difference in SBS was noted between Db-U and Sb-U or Db-S-U and Sb-S-U. Likewise, no significant difference was observed between the subgroups treated with or without silane (P > 0.05).

Conclusion

The sandblasted specimens demonstrated a higher repair SBS than the diamond bur-treated specimens. The use of an additional silanizing step before applying silane-containing universal adhesive did not enhance the SBS of the repaired composite.

Repair of Bulk-Fill and Nanohybrid Resin Composites: Effect of Surface Conditioning, Adhesive Promoters, and Long-Term Aging

The aim of the study was to investigate the effect of different repair procedures on the repair bond strength of bulk-fill and nanohybrid resin composites after different aging periods. The resin composite blocks (8 × 8 × 4 mm3) were prepared from a bulk-fill (reliaFIL Bulk) and a nanohybrid (reliaFIL LC) resin composite and grouped according to aging duration (6 months, 1 year, and 2 years). Following aging, the blocks were assigned to different surface treatments; air-abrasion with aluminum oxide powder, roughening with a diamond bur, and no treatment. After cleansing with phosphoric acid, a silane layer (Porcelain Primer) was applied on the surface of half of the specimens in each group. The specimens were subdivided into two groups (n = 5): Scotchbond Universal (3M Oral Care) and All-Bond Universal (Bisco). The blocks were repaired with the nanohybrid composite (8 × 8 × 8 mm 3). The repaired specimens were stored in distilled water (37 °C/24 h) and segmented into beams. Half of the beams were immediately subjected to microtensile μTBS testing (1 mm/min), while the other half was stored in distilled water (37 °C) for 6 months before testing. Failure modes were analyzed using stereomicroscope and SEM. Statistical analyses were performed with ANOVA and least significant difference tests (LSD) tests (p = 0.05). The extension of aging periods (6 months, 1 year, and 2 years) reduced the repair bond strength in some groups for both resin composites (p < 0.05). The air-abrasion and bur roughening improved the repair bond strength (p < 0.05). The silane application did not influence the repair bond strength and durability (p > 0.05). There was no difference among the universal adhesives in the same surface treatment groups (p > 0.05). The mechanical roughening treatments are necessary for the repair of resin composite. The universal adhesives might be used for the repair of resin composites regardless of silane content without prior silane application.

Effects of different universal adhesives and surface treatments on repair bond strength between resin composites

OBJECTIVE

This study aimed to evaluate the effects of different universal adhesives and surface treatments on the repair bond strength between resin composites.

MATERIALS AND METHODS

A total of 220 composite samples were divided into three groups according to the adhesive resin to be applied: 1) Scotchbond Universal, 2) G-Premio Bond, and 3) Peak Universal Bond. They were then divided into seven subgroups according to surface treatments (n = 10): A) air abrasion, B) air abrasion+silane, C) hydrofluoric acid, D) hydrofluoric acid+silane, E) air abrasion+hydrofluoric acid+silane, F) silane, and G) no surface treatment (negative control). After surface treatment, a repair composite was applied. Samples aged in the thermocycle were subjected to micro-tensile bond strength testing. Cohesive strength values of 10 non-aged composite blocks were used as a positive control. Kruskal-Wallis and one-way ANOVA tests were used for statistical evaluation. Fractured surfaces were evaluated using a scanning electron microscope.

RESULTS

In Scotchbond Universal and G-Premio Bond, the mean micro-tensile bond strength value of the no surface treatment subgroup was significantly lower than that of the positive control. All subgroups of Peak Universal Bond showed similar values to the positive control.

CONCLUSION

While Scotchbond Universal and G-Premio Bond required mechanical roughening before adhesive application, Peak Universal Bond did not require any surface treatment.

CLINICAL SIGNIFICANCE

Different universal adhesives may show different repair bonding strengths with different surface treatments. Since achieving a standard in this regard can be associated with many independent factors, clinicians should determine how to apply the adhesive they use most effectively with the most appropriate surface treatment based on their own clinical experience.

Novel Multifunctional Spherosilicate-Based Coupling Agents for Improved Bond Strength and Quality in Restorative Dentistry

The aim of this study was to investigate the restorative connections of composite materials after fracture, under controlled conditions of treating the materials with novel, spherosilicate-based (SS) primers bearing both methacryl (MA) and trimethoxysilyl (TMOS) groups. The chemistry of methacrylate group insertion and reactive groups hydrolysis has been studied with the aid of ¹H NMR (Nuclear Magnetic Resonance) spectroscopy. The light-cured resin composites were repaired by activating the connection site with the obtained primers and, for comparison, a silane (methacryloxypropyltrimethoxysilane, MATMOS) as a conventional coupling agent bearing the same reactive groups. The resistance of such a joint was tested in a three-point bending test after 24 h and 28 days period of sample conditioning. The effect of bond application was also studied, showing that spherosilicate-based primers may be used more effectively than MATMOS for two-step (primer-composite) restorative process, while for silane, the three-step process with bond application is crucial for satisfactory joint quality. The joint failure mode was determined by microscopic analysis and it was found that SS-4MA-4TMOS and SS-2MA-6TMOS application resulted in mostly composite, and not joint, failure. After 28 days of conditioning, the flexural strength of the joint repaired with SS-4MA-4TMOS was at 94% of the neat, solid material under the same procedure. However, the strength of the neat composite was observed to decline during the conditioning process by ~30%. The joint behavior was explained on the basis of the gradual hydrolysis effect (the greatest decrease being observed for silane).

Microtensile Repair Bond Strength of a Composite After Accelerated Artificial Aging: Effect of the Air Abrasion, Bur, Er:YAG Laser, Two-Step Self-etch Bonding, and Universal Bonding Repair System

Introduction: Repair of old composite restorations is a conservative approach. This study sought to compare the effects of two adhesive systems on the bond strength of repaired composites prepared by three different surface treatments: erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation, air-abrasion, and bur preparation. Methods: Eight microhybrid (Polofil Supra, VOCO, Germany) composite resin blocks were fabricated. The blocks were aged and assigned to four groups as stated by the surface treatment: (I) air-abrasion (50 µ aluminum oxide particles), (II) diamond bur (fine grit), (III) Er:YAG laser (3 W output power, 300 mJ energy) and (IV) control. After surface treatment, the blocks were acid-etched and salinized. Each group was divided two subgroups, and the Clearfil SE Bond or All-Bond Universal was applied on their surface. Composite resin was bonded to the aged composites. The blocks were cut into eight samples, and the microtensile bond strength (MTBS) was measured. Results: The maximum MTBS was noted in the air-abrasion (25.1+6 MPa) group, followed by the Er:YAG laser (21.2+4.7 MPa). The mean MTBS in laser and air-abrasion groups was significantly higher than that in other groups (P<0.05). The mean MTBS was not significantly different between the laser and air-abrasion groups (P>0.05). Composite resin conditioning by All-Bond Universal in laser and air-abrasion groups yielded significantly higher MTBS than the Clearfil SE Bond (P<0.05). Conclusion: All surface treatments created acceptable bond strength. The surface treatment of the aged composite by the Er:YAG laser or air-abrasion along with the application of silane and All-Bond Universal provide high bond strength.

The Effect of Different Surface Roughening Systems on the Micro-Shear Bond Strength of Aged Resin Composites

Background

There are controversies regarding the most effective surface treatment method to be applied for the effective repair of resin composites.

Aims

This study aimed to compare the effects of surface roughening processes on repair bond strength of different types of aged composites. Water aging was applied to 60 nanohybrid and 60 micro-hybrid resin composite samples for 1 year. Samples were randomly divided into five groups and four types of roughening processes. Bur, OPTIDISC, SUPERSNAP, and BISCO were applied to the water-aged resin composite samples. Micro-shear test method was used to measure the repair bond strength.

Materials and Methods

Data were analyzed with IBM SPSS V23. Compliance with normal distribution was examined by Kolmogorov-Smirnov test. Two-way analysis of variance (ANOVA) and Tukey HSD test for multiple comparisons were used.

Results

The main effect of the type of resin composites and surface roughening methods were found to be significantly different. The MPa values of surface roughening groups were similar while the lowest mean value was obtained for the untreated group of the nanohybrid resin composite (P < 0.001). The bond strength for both resin composites was generally considered within acceptable limits except for no treatment group of nanohybrid resin composite.

Conclusions

This study showed that surface roughening method is mandatory for effective bond strength and the type of fillers in resin composite affects the micro-shear bond strength.

Effect of Argon Plasma Surface Treatment on Repair of Resin Composite Aged Two Years

OBJECTIVES

To evaluate the effect of argon plasma treatment (PLA) when combined with sandblasting (SAN), silanization (SIL), and hydrophobic bonding resin (HBR) on the shear bond strength (SBS) of a two-year water-aged resin composite bonded to a newly placed composite after 24 hours and one year of water-storage.

METHODS AND MATERIALS

Thirty-six light-cured composite plates (20mm x 20mm x 4mm thick) were obtained and stored at 37°C in distilled water for 2 years. These aged plates were distributed into 6 groups (n=6) according to the surface treatment: no treatment (Negative Control); SAN+SIL+HBR (Positive Control); SAN+PLA+SIL+HBR; PLA+ SIL+HBR; PLA+SIL; PLA+HBR. Fresh resin composite cylinders were built up using silicone molds (hole: 1.5 mm high x 1.5 mm diameter) positioned over the aged plates. Half of the SBS samples were stored in distilled water for 24 hours and loaded until failure, while the other half were stored for 1 year before being tested. Data were submitted to two-way analysis of variance and post-hoc Tukey Test (preset alpha of 0.05).

RESULTS

Positive Control, SAN+PLA+SIL+HBR and PLA+SIL+HBR groups presented higher SBS means at the 24 hour evaluation. After 1 year of water storage, all groups demonstrated significant SBS reduction, with the SAN+PLA+SIL+HBR group presenting the highest SBS.

CONCLUSIONS

Resin plasma treatment in combination with other surface treatments can improve the SBS of composite repairs after one year of water storage. The SBS of the composite repair was not stable over time regardless of the surface treatment.

Bonding Performance for Repairs Using Bulk Fill and Conventional Methacrylate Composites

This study compared the bond strength of a composite repair made with a bulk fill composite and a conventional one using different surface treatments. Specimens were prepared as truncated cones (bases: 4 mm × 2 mm, height: 4 mm) using a bulk fill (OBFa: Filtek One) or a conventional resin (FTKa: Filtek Z250) (n = 66). They were artificially aged (10,000 cycles, 5°C–55°C, 30 sec) and subdivided according to surface treatments: NT—no treatment (control), Abr—abrasion with a diamond tip, and sand—sandblasting with aluminum oxide (50 μm). Treatments were performed over the smaller diameter surface, followed by adhesive (Scothbond Universal) application. A new specimen with similar dimensions was constructed over it using either the OBF or the FTK, totaling 12 groups (n = 11). Bond strength was assessed by tensile test. The data were submitted to two-way ANOVA separately for OBFa and FTKa, followed by Tukey's test (p < 0.05). For the aged OBFa groups, there was significant differences for composite type and surface treatment, with higher values of bond strength when repaired with the same material (OBFa/OBF > OBFa/FTK), and sandblasting and bur abrasion presented higher values compared to the control group (NT). For the aged FTKa groups, there were no differences for the composite or surface treatment. Therefore, the bulk fill resin composite tested present better repair performance when the same composite was used, while the conventional resin composite was less influenced by the material and the surface treatment performed.

Influence of Surface Conditioning on the Repair Strength of Bioactive Restorative Material

OBJECTIVE

To evaluate the effects of surface treatment and repair material on the repair shear bond strength (SBS) of the bioactive restorative material.

METHODS

A total of 240 Activa BioActive Restorative (Activa) discs were prepared, aged, and polished, and divided randomly into eight groups (n = 30). Groups 1-4 discs were repaired with bulk-fill flowable resin-based composite (Bulk-RBC), and Groups 5-8 discs with Activa. Surface treatment used for each repair material type were air abrasion with silica-coated 30-m Al₂O₃ particles (air abrasion) (Groups 2 & 6), Air abrasion with universal primer (Groups 3 & 7), and Air abrasion with universal adhesive (Groups 4 & 8). Groups 1 and 5 were controls without surface treatment. SBS test was performed, and the failure mode and surface topography were assessed.

RESULTS

Surface treatment with air abrasion significantly improved the SBS for repair using both Activa and Bulk-RBC. Repair SBS using Activa was significantly higher compared with Bulk-RBC. Cohesive failure in substrate and mixed failures were most common in the surface-treated groups (2-4, 6-8). Air abrasion produced prominent surface topography changes compared with polishing.

CONCLUSION

Air abrasion enhances the repair SBS of aged bioactive restorative material. The use of the same material (Activa) for repair affords a higher bond strength compared with the use bulk-RBC.

Effect of adhesive application method on repair bond strength of composite

Objectives

This study aimed to evaluate the effect of the application method of universal adhesives on the shear bond strength (SBS) of repaired composites, applied with different thicknesses.

Materials and Methods

The 84 specimens (Filtek Z350 XT) were prepared, stored in distilled water for a week and thermocycled (5,000 cycles, 5°C to 55°C). They were roughened using 400-grit sandpapers and etched with phosphoric acid. Then, specimens were equally divided into 2 groups; Single Bond Universal (SU) and Prime&Bond Universal (PB). Each group was subdivided into 3 subgroups according to application methods (n = 14); UC: 1 coat + uncuring, 1C: 1 coat + curing, 3C: 3 coats + curing. After storage of the repaired composite for 24 hours, specimens were subjected to the SBS test and the data were statistically analyzed by 2-way analysis of variance and independent t-tests. Specimens were examined with a stereomicroscope to analyze fracture mode and a scanning electron microscope to observe the interface.

Results

Adhesive material was a significant factor (p = 0.001). Bond strengths with SU were higher than PB. The highest strength was obtained from the 1C group with SU. Bonding in multiple layers increased adhesive thicknesses, but there was no significant difference in SBS values (p = 0.255). Failure mode was predominantly cohesive in old composites.

Conclusions

The application of an adequate bonding system plays an important role in repairing composite resin. SU showed higher SBS than PB and the additional layers increased the adhesive thickness without affecting SBS.

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

OBJECTIVE

To evaluate the effect of different adhesive protocols on the microtensile bond strength (μTBS) and integrity of the repaired bulk fill composite interface.

METHODS

Two hundred and seventy composite blocks made of bulk fill composites of different viscosity were randomly assigned to 18 surface conditioning groups (n = 15/group). The universal adhesive systems used were Heliobond™, Tokuyama bond force II™ and Scotchbond Universal™. A nanohybrid resin composite was applied as the repair material. Negative and positive control groups were included. Stick shape specimens of each group were subjected to μTBS testing. Representative samples from all test groups were subjected to microscopic, profilometric and SEM examination to determine their mode of failure. The data were analysed statistically using two-way ANOVA test, Tukey's test and the independent t-test (α = 0.05).

RESULTS

The mean μTBS of all test groups ranged between 28.5 and 46.8 MPa and varied with the type of adhesive system employed. Significantly highest μTBS values were obtained when Tokuyama bond force II™ and Scotchbond Universal™ adhesives were used (p < 0.01) which were comparable to the coherent strength of the bulk fill resin composite in the positive control groups (p > 0.05). The viscosity of the bulk fill composite did not significantly influence repair bond strength. The microscopy and SEM examination of the failed interfaces revealed a mixture of adhesive and cohesive failures.

CONCLUSIONS

Under the tested conditions, significantly greater μTBS of repaired bulk fill composite was achieved when the substrate surface was treated with adhesive systems containing a functional monomer.

CLINICAL SIGNIFICANCE

Eff ;ecting a repair of a bulk fill resin composite restoration with the application of a functional monomer containing adhesive system, such as Tokuyama Bond Force II™ or Scotchbond Universal™, would seem to enhance the interfacial bond strength and integrity of the repaired resin composite interface.

Effect of argon plasma on repair bond strength using nanofilled and microhybrid composites

OBJECTIVES

To evaluate the effect of atmospheric pressure plasma (PLA), sandblasting (SAN), silanization (SIL) and hydrophobic bonding resin (HBR) on the micro-shear bond strength (MSBS) of fresh nanofilled (NF) or microhybrid (MH) composites to water-aged nanofilled composite.

MATERIALS AND METHODS

NF plates were fabricated and stored in distilled water for 4 months. The aged plates were assigned to the groups (n = 6): 1- untreated; 2- SAN + SIL + HBR; 3- HBR; 4- PLA + HBR; 5- SAN + HBR; 6- SAN + PLA + HBR; and 7- PLA. Two fresh composite cylinders were constructed on each plate with NF or MH composites and tested after 24 h or 1 year of water-storage, using the MSBS testing. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05).

RESULTS

NF yielded better outcomes than MH at 24 h, which was not observed at 1 year. HBR showed the highest MSBS results, while untreated and PLA groups yielded the lowest one. MSBS reduced for all groups after 1 year.

CONCLUSIONS

Only HBR can obtain good MSBS results, while PLA alone was not beneficial. After 1 year, a reduction in repair MSBS was observed and the type of composite did not influence the results.

CLINICAL RELEVANCE

The repair technique can be simplified with the use of only an adhesive and macromechanical retentions in the old composite, regardless the type of fresh composite.

Effect of Varying Working Distances between Sandblasting Device and Composite Substrate Surface on the Repair Bond Strength

This study investigates the effect of defined working distances between the tip of a sandblasting device and a resin composite surface on the composite–composite repair bond strength. Resin composite specimens (Ceram.x Spectra ST (HV); Dentsply Sirona, Konstanz, Germany) were aged by thermal cycling (5000 cycles, 5–55 °C) and one week of water storage. Mechanical surface conditioning of the substrate surfaces was performed by sandblasting with aluminum oxide particles (50 µm, 3 bar, 10 s) from varying working distances of 1, 5, 10, and 15 mm. Specimens were then silanized and restored by application of an adhesive system and repair composite material (Ceram.x Spectra ST (HV)). In the negative control group, no mechanical surface pretreatment or silanization was performed. Directly applied inherent increments served as the positive control group (n = 8). After thermal cycling of all groups, microtensile repair bond strength was assessed, and surfaces were additionally characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The negative control group reached the significantly lowest microtensile bond strength of all groups. No significant differences in repair bond strength were observed within the groups with varying sandblasting distances. Composite surfaces sandblasted from a distance of 1 mm or 5 mm showed no difference in repair bond strength compared to the positive control group, whereas distances of 10 or 15 mm revealed significantly higher repair bond strengths than the inherent incremental bond strength (positive control group). In conclusion, all sandblasted test groups achieved similar or higher repair bond strength than the inherent incremental bond strength, indicating that irrespective of the employed working distance between the sandblasting device and the composite substrate surface, repair restorations can be successfully performed.

Effect of Tribochemical Coating on Composite Repair Strength

Clinical Relevance

Tribochemical treatment of existing composite surfaces is highly effective for composite repair. When repairing an old composite restoration, the clinician should try to use the same composite originally used for the restoration. If the information about the original restoration is not known, a composite with strong mechanical properties should be used for the repair restoration.

SUMMARY

This study evaluated the effect of tribochemical coating on composite-to-composite repair interfacial fracture toughness (iFT). Sixty beam-shaped specimens (21×4×3 ± 0.2 mm) were prepared with a nanofill composite (Filtek Supreme Ultra [FSU]) and a nanohybrid composite (Clearfil Majesty ES-2 [CME]) and aged for 50,000 thermocycles (5°C-55°C, 20-second dwell time) and then sectioned in half. The resulting 120 hemispecimens (60 for each composite) were randomly assigned to different repair methods (n=10): universal adhesive (Clearfil Universal Bond Quick [CUB]), sand-blasting followed by CUB, or tribochemical coating (CoJet, CoJet sand, Espe-Sil, and Visio-Bond). The repair surface was prepared with a diamond bur (Midwest #471271), rinsed, and dried. Each aged composite brand (FSU, CME) was repaired with either the same composite or the opposite composite. All adhesives and composites were light cured with a high-irradiance LED curing light (Elipar DeepCure-S). After postrepair storage in 100% humidity and at 37°C for 24 hours, iFT was measured as KIc (MPa m½). Data were analyzed for statistical significance using two-way analysis of variance (ANOVA) and the Tukey honest significant difference post hoc test (α=0.05). Regardless of the substrate composite, ANOVA showed significant differences for surface treatment (p&lt;0.0001) and repair composite (p&lt;0.0001). Mean iFT values (SD) ranged from 0.91 (0.10) MPa·m½ to 2.68 (0.12) MPa·m½. Repairs made with FSU after CoJet resulted in significantly higher iFT (FSU: 2.68 MPa·m½; CME: 2.21 MPa·m½) when compared to the other experimental groups. The repair iFT was higher with CoJet treatment and when the nanofill composite FSU was used as the repair composite.

[Evaluation of microtensile bond strength between resin composite and glass ceramic]

OBJECTIVE

To evaluate the microtensile bond strength of resin composite to glass ceramic, and the effect of surface treatment of resin composite and thermal cycling aging on the microtensile bond strength.

METHODS

Rectangular blocks were made with dentin of extracted molars, resin composite or feldspathic glass ceramic respectively. The bonding surfaces of these rectangular blocks were sanded by 600-grit silicon carbide paper before luting. A self-etching resin cement was used as luting agent. The specimens were divided into groups according to the types of substrates of adhesion (dentin/glass ceramic or resin composite/glass ceramic), the way of surface treatments and whether thermal cycling aging ocurred. The dentin blocks were adhered to ceramic blocks as controls (group A1 and A2). The resin composite blocks were adhered to the ceramic blocks as experiment groups. The resin composite surfaces were treated by different ways before luting: no extra surface treatment (group B1 and B2), treated by ethyl methacrylate solution (group C1 and C2) or silane coupling agent (group D1 and D2), coarsened by 360-grit silicon carbide paper (group E1 and E2) or polished by 1 200-grit silicon carbide paper (group F1 and F2). After luting, the microtensile bond strength of the specimens were tested before (group A1-F1) or after (group A2-F2) thermal cycling aging. After microtensile bond strength test, the fracture bonding surfaces of the specimens were observed by a scanning electron microscopy to determine the type of bonding failure. The data were statistically analyzed using one-way analysis of variance.

RESULTS

The microtensile bond strength of resin composite to glass ceramic with no extra treatment achieved high bond values before and after thermal cycling [B1 (30.02±3.85) MPa, B2 (26.83±3.14) MPa], which were statistically different from those of the control groups [A1 (20.55±4.51) MPa, A2 (12.94±0.69) MPa, P < 0.05]. The microtensile bond strength between the glass ceramic and resin composite did not increase after different surface treatments of resin composite.

CONCLUSIONS

The microtensile bond strength between resin composite and glass ceramic achieved as similar bond strength as that between dentin and glass ceramic and even better. Surface treatment of resin composite via methyl methacrylate solution, silane coupling agent, coarsening, or polishing did not increase the microtensile bond strength effectually.

Chemical and Mechanical Roughening Treatments of a Supra-Nano Composite Resin Surface: SEM and Topographic Analysis

Background: Repairing a restoration is a more advantageous and less invasive alternative to its total makeover. The aim of this study was to analyze the effects of chemical and mechanical surface treatments aimed at increasing the roughness of a supra-nano composite resin. Methods: 27 cylindrical blocks of microhybrid composite were made. The samples were randomly divided into nine groups (n = 3). The samples’ surface was treated differently per each group: acid etching (35% H3PO4, 30 s and 60 s), diamond bur milling, sandblasting and the combination of mechanical treatment and acid etching. The samples’ surface was observed by a scanning electron microscope (SEM) and a confocal microscope for observational study, and surface roughness (Ra) was recorded for quantitative analysis. Results: The images of the samples sandblasted with Al2O3 showed the greatest irregularity and the highest number of microcavities. The surfaces roughened by diamond bur showed evident parallel streaks and sporadic superficial microcavities. No significant roughness differences were recorded between other groups. The difference in roughness between the control group, diamond bur milled group and sandblasted group was statistically significant. (p < 0.01). Comparison between the diamond bur milled group and the sandblasted group was also significant (p < 0.01). Conclusion: According to our results, sandblasting is the best treatment to increase the surface roughness of a supra-nano composite.

Does use of silane-containing universal adhesive eliminate the need for silane application in direct composite repair?

This in vitro study aimed to evaluate the effect of a silane-containing universal adhesive used with or without a silane agent on the repair bond strength between aged and new composites. Forty nanohybrid composite resin blocks were stored in distilled water for 14 d and thermo-cycled. Sandpaper ground, etched, and rinsed speciments were randomly assigned into four experimental groups: silane + two-step etch-and-rinse adhesive system, two-step etch-and-rinse adhesive system, silane + silane-containing universal adhesive system, and silane-containing universal adhesive system. Blocks were repaired using the same composite. After 24 h of water storage, the blocks were sectioned and bonded sticks were submitted to microtensile testing. Ten unaged, non-repaired composite blocks were used as a reference group to evaluate the cohesive strength of the composite. Two-way ANOVA and Tukey's tests were used to analyze average µTBS. One-way ANOVA and Dunnet post-hoc tests were used to compare the cohesive strength values and bond strength obtained in the repaired groups (α = 0.05). The µTBS values were higher for the silane-containing universal adhesive compared to the two-step etch-and-rinse adhesive system (p = 0.002). Silane application improved the repair bond strength (p = 0.03). The repair bond strength ranged from 39.3 to 65.8% of the cohesive strength of the reference group. Using universal silane-containing adhesive improved the repair bond strength of composite resin compared to two-step etch-and-rinse adhesive. However, it still required prior application of a silane agent for best direct composite resin repair outcomes.

The Effects of Aluminablasting on Bond Durability Between Universal Adhesives and Tooth Substrate

The aim of this study was to determine the effect of aluminablasting on the bond durability of universal adhesives and adherent surface characteristics. Adhese Universal (Ivoclar Vivadent), All-Bond Universal (Bisco), Bondmer Lightless (Tokuyama Dental), G-Premio Bond (GC), and Scotchbond Universal (3M ESPE) were used in self-etch mode. The prepared bovine enamel and dentin specimens were divided into two groups based on whether they received an aluminablasting prior to application of the universal adhesives. The resin composite bonded specimens were stored in distilled water at 37°C for 24 hours, following which the shear bond strength (SBS) of half of the specimens was measured (24-hour group). The other half was subjected to 30,000 thermal cycles between 5 and 55°C before SBS measurement (TC group). Surface roughness (Ra) and surface free energy (SFE) of the adherent surfaces were also measured, and scanning electron microscopy observation and scanning electron microscopy/energy-dispersive X-ray analysis were carried out. Most of the adhesives did not show any significant differences in enamel SBS values between the two pretreatment groups, regardless of the storage condition. However, the dentin SBS values were significantly lower in specimens that underwent aluminablasting compared with those that did not, irrespective of their storage conditions. Significantly higher Ra and SFE values were observed in the enamel and dentin of specimens that underwent aluminablasting. Although aluminablasting increased the Ra and SFE values of enamel and dentin, its effect on the SBS value was dependent on the tooth substrate. In addition to C, O, Na, Mg, P, and Ca, the element Al was detected in the enamel and dentin of samples that had undergone aluminablasting. These results suggest that although aluminablasting of the tooth surface is thought to be effective for modification of the adherent surface, it may not enhance enamel bond performance and may also adversely affect the dentin bond effectiveness of the universal adhesives.

Fluorescence-aided Composite Removal in Directly Restored Permanent Posterior Teeth

AIM

The aim of this study was to quantitatively compare conventional composite removal and composite removal supported by the fluorescence-aided identification technique (FIT) regarding the completeness, selectivity, and duration of the procedure in directly restored permanent posterior teeth.

METHODS AND MATERIALS

Two operators removed standardized direct class II composite restorations (n=32 per operator) in human tooth models under simulated clinical conditions. According to a randomized allocation scheme, removal was performed with either the conventional technique (contra-angle handpiece) or supported by FIT. The duration of each removal procedure was recorded. The completeness and selectivity were volumetrically assessed through superimposition of three-dimensional surface scans. Statistical significance was tested by examining the overlap of 95% confidence intervals (CI). Multiple comparison was performed with Tukey tests for each variable.

RESULTS

Compared with the conventional technique, composite removal with FIT was faster (329 seconds [95% confidence interval (CI): 268-390 seconds] vs 179 seconds [95% CI: 150-208 seconds]), generated less tooth substance loss (4.53 mm³ [95% CI: 3.77-5.30 mm³] vs 2.77 mm³ [95% CI: 2.11-3.43 mm³]), and left behind less composite residue (1.58 mm³ [95% CI: 1.23-1.94 mm³] vs 0.53 mm³ [95% CI: 0.39-0.67 mm³]).

CONCLUSION

Within the limitations of this in vitro study, FIT facilitated the selective and expeditious removal of tooth-colored composites in directly restored posterior teeth.

A randomised controlled study on the effects of different surface treatments and adhesive self-etch functional monomers on the immediate repair bond strength and integrity of the repaired resin composite interface

OBJECTIVES

To evaluate the effects of different surface conditioning methods on the immediate repair bond strength and integrity of the repaired composite interface.

METHODS

One hundred and five resin composite blocks made of a nanohybrid resin composite were randomly assigned to one of the following surface conditioning groups (n = 15/group): Group 1: Gluma Self Etch™ adhesive system, Group 2: Tokuyama Bond Force II™ adhesive system, Group 3: non-roughened and non-conditioned surfaces, Group 4: sandblasting and Gluma Self Etch™, Group 5: sandblasting and Tokuyama Bond Force II™, Group 6: sandblasting only. A positive control group was also used. Resin composite identical to the substrate was applied and the repaired specimens were subjected to shear bond strength (SBS) testing. Representative samples from all groups were subjected to scanning electron microscopy and surface profilometry to determine their mode of failure. The data were analysed statistically using Analysis of Variance (ANOVA) and two independent sample t-test (α = 0.05).

RESULTS

The mean SBS of all test groups ranged between 1.92 and 5.40 MPa and varied with the degree of composite surface roughness and the type of adhesive system employed. Significantly highest SBS values (5.40 ± 0.36 MPa) were obtained in Group 5 (p = 0.017) which were comparable to the coherent strength of the resin composite in the positive control group (p > 0.05).

CONCLUSIONS

Under the tested conditions, significantly greater SBS of repaired resin composite was achieved when the substrate surface was conditioned by sandblasting followed by the application of the Tokuyama Bond Force II™ adhesive system.

CLINICAL SIGNIFICANCE

Effecting a repair of a nanohybrid composite restoration with sandblasting and the application of TBF II would seem to enhance the interfacial bond strength and integrity of the repaired resin composite interface. Clinical trials are necessary to determine the usefulness of this technique.

Effect of Argon Plasma Surface Treatment on Bond Strength of Resin Composite Repair

Objectives:

This study evaluated the effect of argon plasma treatment (PLA) and its combination with sandblasting (SAN), silanization (SIL), and hydrophobic bonding resin (HBR) application on the micro-shear bond strength of water-aged restorative resin composite to a newly placed composite, simulating restoration repair.

Methods and Materials:

Forty-five light-cured composite plates (20-mm long × 20-mm wide × 4-mm thick) were fabricated using a hybrid composite and stored at 37°C in distilled water for six months. The aged composite surfaces were treated according to the following experimental groups, varying both treatment and order of application: 1) SAN + SIL + HBR (control), 2) SAN + PLA for 30 seconds + SIL + HBR, 3) SAN + SIL + PLA + HBR, 4) PLA + SIL + HBR, 5) PLA + SIL, 6) PLA + HBR, 7) SIL + PLA + HBR, 8) SIL + PLA, and 9) PLA. After the surface treatments, four fresh resin composite cylinders (1.5-mm high × 1.5-mm diameter) of the same composite were built on each aged composite surface using a silicone mold. After water storage for 24 hours or one year, the specimens were submitted to shear bond strength testing. Data were statistically analyzed by two-way analysis of variance and Tukey's test (5%).

Results:

Groups 1, 2, and 4 presented significantly higher bond strength means at 24 hours, although group 4 did not differ from group 7. Groups 5, 8, and 9 demonstrated significantly lower means than the other groups. Even though groups 1 and 2 had a significant bond strength reduction after 1 year, they still demonstrated higher bond strength at one year of storage.

Conclusions:

While PLA application combined with surface treatment methods demonstrated high bond strength results, this treatment alone was not as beneficial as other methods that included SAN, SIL and HBR.

Original and Repair Bulk Fracture Resistance of Particle Filler and Short Fiber-Reinforced Composites

OBJECTIVE

This study aimed to evaluate the original (OR) and repair (RR) fracture resistance of a semi-interpenetrating polymer network (semi-IPN)-based short fiber-reinforced composite compared to dimethacrylate-based composite materials by means of the V-notch test.

METHODS AND MATERIALS

Circular specimens (5×2 mm) with a centrally machined 90° V-shaped notch were prepared. Four bulk fill (Filtek Bulk Fill, Venus Bulk Fill, TetricEvo Ceram Bulk Fill, SDR), three microfilled hybrid (GC-Anterior, GC-Posterior, Z250), one nanofilled (SupremeXTE), and two short fiber-reinforced (Alert, everX Posterior) composites were selected. EverX Posterior was the semi-IPN material. Specimens (n=12/group) were either dry or water stored for 7 and 30 days, respectively, at 37°C and then loaded in two-point load until fracture. One-half of each tested specimen was used for the repair procedure. Repairing surfaces were diamond-bur ground, etched, and treated with silane containing universal adhesive (Scotchbond Universal) before repair.

RESULTS

Three-way analysis of variance revealed a significant statistical difference between the groups ( p<0.05). The fracture resistance of dry-stored groups was greater than that of water-stored groups. The highest OR was observed for dry-stored Alert (23.4 N/mm), which significantly deteriorated in water (17.4 N/mm) ( p<0.05). The highest RR was observed for everX Posterior (20.0 N/mm), which did not deteriorate in water significantly (19.0 N/mm) ( p>0.05). The everX Posterior preserved the specimens' integrity at the final fracture load (ductile fracture), whereas all other materials fractured into two halves at the interface (adhesive failure).

CONCLUSIONS

The only material that provided enhanced repair strength that was close to the original cohesive strength of the material was everX Posterior. The endurance of repaired restorations can be improved by using semi-IPN-based filling material.

Color Repair of a Composite Resin Restoration

Fractured teeth with both enamel and dentin involvement might be treated with adhesive composite resin restorations. In cases where a perfect color match between the composite restoration and the remaining tooth structure is not achieved, a repair might be carried out to correct the color of restoration. This procedure avoids the restoration replacement, preserving tooth structure without compromising the esthetic outcome.

Influence of material and surface treatment on composite repair shear bond strength

OBJECTIVES

The aim of this study is to investigate the influence of the composite material and surface treatment to the bond strength when repairing an aged composite surface with new composite.

MATERIALS AND METHODS

One hundred and sixty resin blocks of methacrylate composite and silorane composite prepared and aged in artificial saliva for 6 months. Specimens treated either with a diamond bur (DB) or air abrasion (AA), conditioned with orthophosphoric acid (OA) or sodium hypochloride (SH) and repaired with methacrylate or silorane composite using the corresponding adhesive system. Repaired composites underwent thermocycling fatigue (×5000), and bond strength was measured at shear.

RESULTS

Methacrylate achieved the highest bond strengths as repair material, in all combinations (26.54-55.56 MPa). Silorane only reached 8.12 MPa when repairing silorane treated with DB and OA. For all other treatment combinations repairing with silorane led to pretest failures. The most susceptible to repair composites/surface treatment combination is when repairing methacrylate treated with AA and SH and methacrylate composite (55.56 MPa).

CONCLUSIONS

Silorane composites are not suitable to be used when repairing an old composite restoration. The repair material is the most critical factor, while aged surface treatment has only a minor influence to the shear bond strength.

Bonding performance of self-adhesive flowable composites to enamel, dentin and a nano-hybrid composite

This study aimed to analyze bond strengths of self-adhesive flowable composites on enamel, dentin and nano-hybrid composite. Enamel, dentin and nano-hybrid composite (Venus Diamond, Heraeus Kulzer, Germany) specimens were prepared. Three self-adhesive composites (Constic, DMG, Germany; Fusio Liquid Dentin, Pentron Clinical, USA; Vertise Flow, Kerr Dental, Italy) or a conventional flowable composite (Venus Diamond Flow, Heraeus Kulzer, Germany, etch&rinse technique) were applied to enamel and dentin. Nano-hybrid composite specimens were initially aged by thermal cycling (5000 cycles, 5-55 °C). Surfaces were left untreated or pretreated by mechanical roughening, Al₂O₃ air abrasion or silica coating/silanization. In half of the composite specimens, an adhesive (Optibond FL, Kerr Dental, Italy) was used prior to the application of the flowable composites. Following thermal cycling (5000 cycles, 5-55 °C) of all specimens, shear bond strengths (SBS) and failure modes were analyzed (each subgroup n = 16). Statistical analysis was performed by ANOVAs/Bonferroni post hoc tests, Weibull statistics and χ ²-tests (p < 0.05). SBS (MPa) of the self-adhesive composites on enamel and dentin were significantly lower (enamel: < 5, dentin: < 3) than those of the conventional flowable composite (enamel: 13.0 ± 5.1, dentin: 11.2 ± 6.3), and merely adhesive failures could be observed. On the nano-hybrid composite, SBS were significantly related to the pretreatment. Adhesive application improved SBS of the conventional, but not of the self-adhesive composites. The self-adhesive composite groups showed less cohesive failures than the reference group; the occurence of cohesive failures increased after surface pretreatment. Bonding of self-adhesive flowable composites to enamel and dentin is lower than bonding to a nano-hybrid composite.

Repair bond strength of nanohybrid composite resins with a universal adhesive

Objective: To investigate the repair bond strength of fresh and aged nanohybrid and hybrid composite resins using a universal adhesive (UA).

Materials and methods: Fresh and aged substrates were prepared using two nanohybrid (Venus Pearl, Heraus Kulzer; Filtek Supreme XTE, 3 M ESPE) and one hybrid (Z100, 3 M ESPE) composite resin, and randomly assigned to different surface treatments: (1) no treatment (control), (2) surface roughening with 320-grit (SR), (3) SR + UA (iBOND, Heraus Kulzer), (4) SR + Silane (Signum, Ceramic Bond I, Heraeus Kulzer) + UA, (5) SR + Sandblasting (CoJet, 3 M ESPE) + Silane + UA. After surface treatment, fresh composite resin was added to the substrates at 2 mm layer increments to a height of 5 mm, and light cured. Restored specimens were water-stored for 24 h and sectioned to obtain 1.0 × 1.0 mm beams (n = 12), and were either water-stored for 24 h at 37 °C, or water-stored for 24 h, and then thermocycled for 6000 cycles before microtensile bond strength (µTBS) testing. Data were analyzed with ANOVA and Tukey’s HSD tests (p = .05).

Results: Combined treatment of SR, sandblasting, silane and UA provided repair bond strength values comparable to the cohesive strength of each tested resin material (p < .05). Thermocycling significantly reduced the cohesive strength of the composite resins upto 65% (p < .05). Repair bond strengths of UA-treated groups were more stable under thermocycling.

Conclusions: Universal adhesive application is a reliable method for composite repair. Sandblasting and silane application slightly increases the repair strength for all substrate types.

Adhesive system affects repair bond strength of resin composite

Purpose:

This study evaluated the effects of different adhesive systems on repair bond strength of aged resin composites.

Materials and Methods:

Ninety composite discs were built and half of them were subjected to thermal aging. Aged and non-aged specimens were repaired with resin composite using three different adhesive systems; a two-step self-etch adhesive, a two-step total-etch adhesive and a one-step self-etch adhesive; then they were subjected to shear forces. Data were analyzed statistically.

Results:

Adhesive type and aging significantly affected the repair bond strengths (p<0.0001). No statistical difference was found in aged composite groups repaired with two-step self- etch or two-step total-etch adhesive. One-step self-etch adhesive showed lower bond strength values in aged composite repair (p<0.0001).

Conclusion:

In the repair of aged resin composite, two-step self-etch and two-step total-etch adhesives exhibited higher shear bond strength values than that of one-step self-etch adhesive.

Attitudes of Greek dentists towards repair of conservative restorations. An online survey

OBJECTIVES

Repair versus replacement of a defective direct restoration is one important step for conserving tooth structure. This study was designed to collect information on the attitudes of Greek dentists towards repairing direct restorations.

METHODS

An electronic questionnaire with 16 multiple-choice and rank-ordering questions was created online and its URL address was randomly emailed to 800 dentists in the area of Athens, Greece. The questionnaire remained open for 3 months, and after two reminder emails the data collected were analysed statistically to identify differences between clinician's sex or years of practicing dentistry, using the chi-square and Kruskal-Wallis tests at α = 0.05.

RESULTS

Three-hundred and twenty dentists completed and submitted the questionnaire (response rate = 40%). A high proportion (86.8%) of the respondents reported that they routinely repair defective restorations, ranking the order of their frequency as 2.47 for amalgam and 2.41 for resin restorations. The reasons, with the highest ranks, for repairing amalgams were the restoration of bulk fractures (4.10) and restoration of marginal fractures (3.69). For repair of resin restorations, the reasons with the highest ranks were improving their colour (4.04) and removing marginal discoloration (3.99). Moreover, 94.1% of the respondents stated that they were enough, much and very much satisfied with the repair, 1 year after it was performed.

CONCLUSIONS

A high percentage of Greek dentists are repairing defective direct restorations. There are discrepancies in the indications, techniques and materials used for repairs, such as bulk fractures and marginal restorations. Further studies on the efficacy of repairs, the criteria and procedure protocols are needed. Further, additional clinical education should be offered at the undergraduate or continuing education levels.

Evaluation of a technique for color correction in restoring anterior teeth

OBJECTIVE

This study aimed to evaluate the ability of the proposed technique in producing restorations that exhibit mimesis with tooth structure and to define a restorative clinical protocol.

MATERIALS AND METHODS

For this study a typodont was used. The right upper central incisor with Class IV lesion was restored with the layering technique (reference tooth, RT). For the left upper central incisor with Class IV lesion, six teeth were restored monochromatically (test teeth, TT), using DA3.5 (n = 3) and DA4 (n = 3) composite resins-resulting in six unsatisfactory color restorations. TT were divided into six groups depending on the color of unsatisfactory restoration and preparation depth. First, a preparation was realized on the labial surface with 0.5 mm, 0.7 mm or 1.0 mm of depth. A second preparation was then performed to reproduce the dentinal mamelons. Next, adhesive procedures were performed and the teeth restored. Opaque halo, opalescent halo and vestibular enamel were then reproduced by the addition of different composite resins. The RT and TT were photographed side by side in typodont to obtain six photographic prints. The photographs of the groups were subjected to visual evaluation by 120 volunteers via a questionnaire. Data were analyzed by the prevalence of answers, and Chi-square test was used to investigate the association between variables at .05 significance. Furthermore, ΔE of groups was evaluated in comparison RT.

RESULTS

The results demonstrated that the moderate intensity restorations (DA3.5) with depths of 0.5 mm and 0.7 mm had the highest prevalence of acceptance. For severe intensity restorations (DA4), the preparation depth of 1.0 mm obtained better acceptance.

CONCLUSIONS

The technique was able to modify the final color of Class IV restorations, producing satisfactory color restorations.

CLINICAL SIGNIFICANCE

This technique can be used for color correction in cases of Class IV restorations, in situations where there is no time for immediate layered restoration, and as a restorative technique.

Effect of Surface Treatment, Silane, and Universal Adhesive on Microshear Bond Strength of Nanofilled Composite Repairs

Purpose: The aim of this study was to evaluate the effect of surface treatment and universal adhesive on the microshear bond strength of nanoparticle composite repairs.

Methods: One hundred and forty-four specimens were built with a nanofilled composite (Filtek Supreme Ultra, 3M ESPE). The surfaces of all the specimens were polished with SiC paper and stored in distilled water at 37°C for 14 days. Half of the specimens were then air abraded with Al2O3 particles and cleaned with phosphoric acid. Polished specimens (P) and polished and air-abraded specimens (A), respectively, were randomly divided into two sets of six groups (n=12) according to the following treatments: hydrophobic adhesive only (PH and AH, respectively), silane and hydrophobic adhesive (PCH, ACH), methacryloyloxydecyl dihydrogen phosphate (MDP)–containing silane and hydrophobic adhesive (PMH, AMH), universal adhesive only (PU, AU), silane and universal adhesive (PCU, ACU), and MDP-containing silane and universal adhesive (PMU, AMU). A cylinder with the same composite resin (1.1-mm diameter) was bonded to the treated surfaces to simulate the repair. After 48 hours, the specimens were subjected to microshear testing in a universal testing machine. The failure area was analyzed under an optical microscope at 50× magnification to identify the failure type, and the data were analyzed by three-way analysis of variance and the Games-Howell test (α=0.05).

Results: The variables “surface treatment” and “adhesive” showed statistically significant differences for p&lt;0.05. The highest mean shear bond strength was found in the ACU group but was not statistically different from the means for the other air-abraded groups except AH. All the polished groups except PU showed statistically significant differences compared with the air-abraded groups. The PU group had the highest mean among the polished groups. Cohesive failure was the most frequent failure mode in the air-abraded specimens, while mixed failure was the most common mode in the polished specimens.

Conclusions: While air abrasion with Al2O3 particles increased the repair bond strength of the nanoparticle composite, the use of MDP-containing silane did not lead to a statistically significant increase in bond strength. Silane-containing universal adhesive on its own was as effective as any combination of silane and adhesive, particularly when applied on air-abraded surfaces.

Reparability of giomer using different mechanical surface treatments

Background

In the repair process achieving high bond strength between the new and old resin based materials is necessary for clinical longevity. This study compared the effect of three different mechanical surface treatments (air abrasion, Nd:YAG laser and diamond bur) on the repair bond strength of giomer.

Material and Methods

In this in vitrostudy, 125 cylindrical giomer samples were used. The giomer samples were randomly assigned to 5 groups (n=25). In group 1, the samples did not undergo any surface treatment. In groups 2 to 4, the samples underwent surface treatments with air abrasion, Nd:YAG laser and a diamond bur. The samples in group 5 were prepared to measure giomer cohesive strength. Subsequently, the new giomer was bonded to the existing giomer in groups 1 to 4. Then the repair bond strength of the samples was measured. One-way ANOVA and post hoc Tukey test were used to compare the bond strength.

Results

There were significant differences between the different surface treatments (P<0.001); the repair bond strength in the air abrasion group was significantly higher than that in the Nd:YAG laser group, in which it was significantly higher than that in the diamond bur group, which was in turn higher than that in group 1 (no surface treatment) (P<0.001). In addition, the cohesive strength of giomer was significantly higher than the repair bond strength in the 4 other study groups (P<0.001).

Conclusions

Of all the surface treatments, air abrasion and Nd:YAG laser, in descending order, yielded the highest repair bond strength values, with the repair bond strength values of 60‒70% of the giomer cohesive strength.

Key words:Air abrasion, bond strength, giomer, Nd:YAG laser, repair, surface treatment.

Repair Strength in Simulated Restorations of Methacrylate- or Silorane-Based Composite Resins

The study verified the bond strength in simulated dental restorations of silorane- or methacrylate-based composites repaired with methacrylate-based composite. Methacrylate- (P60) or silorane-based (P90) composites were used associated with adhesive (Adper Single Bond 2). Twenty-four hemi-hourglass-shaped samples were repaired with each composite (n=12). Samples were divided according to groups: G1= P60 + Adper Single Bond 2+ P60; G2= P60 + Adper Single Bond 2 + P60 + thermocycling; G3= P90 + Adper Single Bond 2 + P60; and G4= P90 + Adper Single Bond 2 + P60 + thermocycling. G1 and G3 were submitted to tensile test 24 h after repair procedure, and G2 and G4 after submitted to 5,000 thermocycles at 5 and 55 ?#61616;C for 30 s in each bath. Tensile bond strength test was accomplished in an universal testing machine at crosshead speed of 0.5 mm/min. Data (MPa) were analyzed by two-way ANOVA and Tukey's test (5%). Sample failure pattern (adhesive, cohesive in resin or mixed) was evaluated by stereomicroscope at 30?#61655; and images were obtained in SEM. Bond strength values of methacrylate-based composite samples repaired with methacrylate-based composite (G1 and G2) were greater than for silorane-based samples (G3 and G4). Thermocycling decreased the bond strength values for both composites. All groups showed predominance of adhesive failures and no cohesive failure in composite resin was observed. In conclusion, higher bond strength values were observed in methacrylate-based resin samples and greater percentage of adhesive failures in silorane-based resin samples, both composites repaired with methacrylate-based resin.

Effect of curing and silanizing on composite repair bond strength using an improved micro-tensile test method

Objectives: To evaluate the micro-tensile repair bond strength between aged and new composite, using silane and adhesives that were cured or left uncured when new composite was placed.

Methods: Eighty Filtek Supreme XLT composite blocks and four control blocks were stored in water for two weeks and thermo-cycled. Sandpaper ground, etched and rinsed specimens were divided into two experimental groups: A, no further treatment and B, the surface was coated with bis-silane. Each group was divided into subgroups: (1) Adper Scotchbond Multi-Purpose, (2) Adper Scotchbond Multi-Purpose adhesive, (3) Adper Scotchbond Universal, (4) Clearfil SE Bond and (5) One Step Plus. For each adhesive group, the adhesive was (a) cured according to manufacturer’s instructions or (b) not cured before repair. The substrate blocks were repaired with Filtek Supreme XLT. After aging, they were serially sectioned, producing 1.1 × 1.1 mm square test rods. The rods were prepared for tensile testing and tensile strength calculated at fracture. Type of fracture was examined under microscope.

Results: Leaving the adhesive uncured prior to composite repair placement increased the mean tensile values statistically significant for all adhesives tested, with or without silane pretreatment. Silane surface treatment improved significantly (p < 0.001) tensile strength values for all adhesives, both for the cured and uncured groups. The mean strength of the control composite was higher than the strongest repair strength (p < 0.001).

Conclusions: Application of freshly made silane and a thin bonding layer, rendered higher tensile bond strength. Not curing the adhesive before composite placement increased the tensile bond strength.

Microtensile bond strength of repaired indirect resin composite

PURPOSE

The objective of this study was to investigate the effect of surface treatments on microtensile bond strengths (MTBSs) of two types of indirect resin composites bonded to a conventional direct resin composite.

MATERIALS AND METHODS

Indirect resin composite blocks of Ceramage and SR Nexco were prepared in a plastic mold having a dimension of 10 × 10 × 4 mm. These composite blocks were divided into three groups according to their surface treatments: Group1: Sandblast (SB); Group2: Sandblast and ultrasonically clean (SB+UL); Group3: Sandblast plus silane (SB+SI). After bonding with direct resin composite, indirect-direct resin composite blocks were kept in distilled water for 24 hours at 37℃ and cut into microbars with the dimension of 1 × 1 × 8 mm. Microbar specimens (n = 40 per group) were loaded using a universal testing machine. Failure modes and compositions were evaluated by SEM. The statistical analyses of MTBS were performed by two-way ANOVA and Dunnett's test at α = .05.

RESULTS

Surface treatments and brands had effects on the MTBS without an interaction between these two factors. For SR Nexco, the MTBSs of SB and SB+SI group were significantly higher than that of SB+UL. For Ceramage, the MTBSs of SB and SB+SI were significantly higher than that of SB+UL. The mean MTBS of the Ceramage specimens was significantly higher than that of SR Nexco for all surface treatments.

CONCLUSION

Sandblasting with or without silane application could improve the bond strengths of repaired indirect resin composites to a conventional direct resin composite.

Microtensile Bond Strength of Composite Cement to Novel CAD/CAM Materials as a Function of Surface Treatment and Aging

Objectives: To evaluate the effect of different surface treatments on the bond strength to a composite and a polymer-infiltrated ceramic CAD/CAM block after six-month artificial aging.

Methods and Materials: Two types of CAD/CAM blocks (Cerasmart, GC; Enamic, Vita Zahnfabrik) were cut in slabs of 4-mm thickness, divided into six groups, and subjected to the following surface treatments: group 1: no treatment; group 2: sandblasting (SB); group 3: SB + silane (Si); group 4: SB + Si + flowable composite (see below); group 5: 5% hydrofluoric acid etching (HF) + Si; and group 6: 37% phosphoric acid etching (H3PO4) + Si. Sections of the same group were luted together (n=3: 3 sandwich specimens/group) using a dual-cure self-adhesive cement for all groups, except for the sections of group 4 that were luted using a light-curing flowable composite. After three weeks of storage in 0.5% chloramine at 37°C, the sandwich specimens were sectioned in rectangular microspecimens and trimmed at the interface to a dumbbell shape (1.1-mm diameter). One half of the specimens was subjected to a microtensile bond strength (μTBS) test, and the other half was tested after six months of water storage (aging). Data were statistically analyzed with a linear mixed-effects model for the factors surface treatment, material type, and aging, together with their first-degree interactions (α=0.05).

Results: The lowest bond strengths were obtained in the absence of any surface treatment (group 1), while the highest μTBSs were obtained when the surface was roughened by either SB or HF, this in combination with chemical adhesion through Si. Loss in bond strength was observed after six-month aging when either surface roughening or silanization, or both, were omitted.

Conclusions: Both the composite and polymer-infiltrated ceramic CAD/CAM blocks appeared equally bonding-receptive regardless of the surface treatment used. Creating a microretentive surface by either SB or HF, followed by chemical adhesion using Si, is mandatory to maintain the bond strength after six months.