Effect of dentin roughness on the adhesive performance in non-carious cervical lesions: A double-blind randomized clinical trial

Abstract

Objective

This double-blind randomized clinical trial evaluates the influence of dentin roughening (RO) on the clinical behavior of a new universal multi-mode adhesive (Tetric N-Bond Universal; Ivoclar-Vivadent) applied as self-etch and as etch-and-rinse in non-carious cervical lesions (NCCLs).

Methods

A total of 192 restorations were randomly placed in 48 patients according to the following groups: ER – Etch-and-rinse (no preparation); SE – self-etch (no preparation); ER + RO and; SE + RO. The resin composite Empress Direct (Ivoclar-Vivadent) was placed incrementally. The restorations were evaluated after one week (baseline), 6 and 18 months, using the FDI and USPHS criteria. Statistical analyses were performed using appropriate tests (α = 0.05).

Results

Fifteen restorations were lost at 18 months (3 for SE, 2 for ER, 5 for SE + RO and 5 for ER + RO) (p > 0.05 between groups). Post-operative sensitivity wasn’t observed in any of the recall periods. Eighty-four restorations were considered to have minor discrepancies in marginal adaptation at the 18-month recall using the FDI criteria (24 for SE, 18 for ER, 22 for SE + RO and 20 for ER + RO; p > 0.05 between groups). Nineteen restorations were considered to have minor discrepancies in marginal discoloration at the 18-month recall (10 for SE, 03 for ER, 05 for SE + RO and 01 for ER + RO; p > 0.05 between groups).

Conclusion

The dentin roughening before application of Tetric N-Bond Universal as self-etch and etch-and-rinse didn’t affect the clinical behavior of composite restorations placed in NCCLs.

Introduction

Adhesive systems are the most important evolution in restorative dentistry, and adhesive procedures for direct and indirect use had become part of the dental professional’s daily life . However, not all of clinical procedure have controlled clinical evaluations that ultimately help predict their long-term clinical performance .

Currently, adhesive systems can be used in the etch-and-rinse and self-etch approach. For etch-and-rinse adhesive systems, there is the need to use a preliminary phosphoric acid before monomer infiltration to dissolve smear layer and the superficial mineral components of enamel and dentin. Despite the good clinical results of the etch-and-rinse strategy , this protocol is considered complex due to the number of clinical steps . On the other hand, self-etch adhesives have a simple bonding protocol , mainly when applied in one clinical step. The disadvantage of this simple protocol is that it does not produce a retentive etching pattern on enamel as it is the case with phosphoric acid. Consequently, composite resin restorations with higher rates of marginal discoloration are observed when self-etch adhesive systems are applied .

In the same line of simplification, the manufacturers recently launched a novel family of bonding systems known as “universal” or “multi-mode” adhesives . They are adhesives that can be associated or not with phosphoric acid etching, which gives the dentist a more versatile product . The main difference between the oldest SE systems and the most universal adhesives systems is the presence of monomers capable to produce chemical adhesion to dental substrates . This is expected to increase the durability of the bonds produced with simplified self-etch adhesive, which has been considered less durable in in vitro and in vivo studies .

Unfortunately, recently published clinical trials showed controversial results regarding the clinical performance of composite resin restoration bonded with universal adhesives in non-carious cervical lesions . This suggests that despite all efforts in the improvement of adhesives systems, the bonding to non-carious cervical lesions is always a complex procedure .

In contrast to caries-affected dentin, non-carious cervical lesions (NCCL) exhibit a high degree of sclerosis, with partial or complete obliteration of dentine tubules, which prevents the formation of the hybrid layer . The nature of the sclerotic dentin makes it very suitable for bonding with glass ionomer cements or resin-modified glass ionomers (GIC/RMGIC). These materials are capable to establish chemical bonding with calcium . However, the claiming for esthetic has impulse the use of direct resin composite restorations associated to universal adhesives.

To overcome this problem, some clinicians and researches indicate that enamel and dentin preparation with a diamond bur before adhesive application can make the substrate more receptive to the bonding procedure . One example of this procedure is the enamel beveling. It was believed that the additional area of bonding produced by beveling as well as the removal of unsupported enamel may provide an additional advantage in terms of bonding over non-beveled composite restorations . A meta-analysis revealed no beneficial effect of enamel beveling, neither on retention rate nor on marginal discoloration .

Dentin roughening with a diamond bur is also reported as a way to make the dental substrate of NCCLs more receptible to dental adhesives . Two recent reviews has pointed out that the dentin roughening of NCCLs was associated with statistically significantly increased retention rates which may be an alternative to improve the longevity of cervical composite restorations. The difference of retention rate between NCCLs with roughened dentin and NCCls without roughened dentin was increasing with time; it was more pronounced after 4–5 years observation period than for 1,5 years observation period. However, this finding was mainly based on pooled studies with roughening of the dentin and on those without. The number of randomized controlled clinical trials that investigated into the influence of dentin roughening are scarce and showed controversial results .

Therefore, the objective of this double-blind randomized clinical trial was to evaluate the influence of dentin roughening on the clinical behavior of a new universal multi-mode adhesive applied as self-etch and etch-and-rinse placed in non-carious cervical lesions (NCCL) over the course of 18 months. The null hypothesis tested was that bonding to NCCLs with or without dentin roughening before adhesive application in self-etch and etch-and-rinse yield similar retention rates over 18 months of clinical service.

Materials and methods

The description of the experimental design followed the Consolidated Standards of Reporting Trials (CONSORT) statement .

Ethics approval

The local Ethics Committee on Investigations Involving Human Subjects reviewed and approved the protocol and issued a consent form for this study (protocol CB027-2014). Written informed consent was obtained from all participants prior to starting the treatment.

Protocol registration

This clinical trial was registered in clinicaltrial.gov clinical registry under protocol # NCT02751970. All participants were informed about the nature and objectives of the study.

Trial design, settings and location of data collection

This was a double-blind, superiority, split-mouth randomized clinical trial. The study was carried out in the clinics of the School of Dentistry at the local University from January 2015 to November 2015.

Recruitment

Patients were recruited as they seek for treatment in the clinics of Dentistry of the local university. No advertisement was made for participant recruitment. Patients were recruited in the order in which they reported for the screening session, thus forming a sample of convenience.

Eligibility criteria

A total of 65 participants were examined by two calibrated dental students to check if they met the inclusion and exclusion criteria ( Fig. 1 ). The evaluations were performed using a mouth mirror, an explorer, and a periodontal probe. Participants had to be in good general health, be at least 18 years old, have an acceptable oral hygiene level, and present at least 20 teeth under occlusion.

Fig. 1
Flow diagram. Np: number of patients, Nr: number of restorations. SE = Self-etch, no preparation; ER = Etch-and-Rinse, no preparation; SE + RO = Self-etch, roughening dentin; ER + RO = Etch-and-Rinse, roughening dentin.

Participants were required to have at least four NCCLs to be restored in four different teeth. These lesions had to be non-retentive, deeper than 1 mm, and involve both the enamel and dentin of vital teeth without mobility. The cavosurface margin could not involve more that 50% of enamel . Patients with extremely poor oral hygiene, severe or chronic periodontitis, or heavy bruxism habits were excluded from the study as they would receive other treatments before restorative intervention.

Sample size calculation

The annual retention rate to one-step self-etch adhesives in NCCLs was reported to be 4.4% in a recent systematic review . Considering that this decline follow a linear trend, the overall retention rate of one-step self-etch adhesives will be approximately 78% after 5-year of clinical service. With an α of 0.05, a power of 80%, and a two-sided test, the minimal sample size will be 40 restorations in each group in order to detect a difference of 30% among the test groups . It was added 20% more patients to compensate future losses.

Random sequence generation and allocation concealment

The randomization was done on an intra-individual basis so that each subject ended up with four restorations, each one resulting from one of all possible combinations of adhesive strategy and roughening procedure. These randomization schemes were performed using software available at www.sealedenvelope.com .

A staff member not involved in the research protocol performed the randomization process with computer-generated tables. Details of the allocated groups were recorded on cards contained in sequentially numbered, opaque, sealed envelopes. Opening the envelope only on the day of the restorative procedure guaranteed the concealment of the random sequence. In all cases, the tooth with the highest tooth number received the treatment described first, while the tooth with the next number in sequence received the treatment mentioned second, with placement continuing in a similar manner until the fourth tooth. All restorations in the same subject were always placed in different sextants.

Interventions: restorative procedure

All the patients selected for this study received dental prophylaxis with a suspension of pumice and water in a rubber cup and signed an informed consent form two weeks before the restorative procedures.

The degree of sclerotic dentin from the NCCLs was measured according to the criteria described by Swift and others ( Table 1 ). The cavity dimensions in millimeters (height, width, and depth), the geometry of the cavity (evaluated by profile photograph and labeled at <45°, 45°–90°, 90° < 135°, and >135°) , the presence of an antagonist, and the presence of attrition facets were observed and recorded. Pre-operative sensitivity was also evaluated by applying air for 10 s from a dental syringe placed 2 cm from the tooth surface and with an explorer. These features were recorded to allow comparison of the baseline features of the dentin cavities among experimental groups.

Table 1
Dentin sclerosis scale. a
Category Criteria
1 No sclerosis present; dentin is light yellowish or whitish, with little discoloration; dentin is opaque, with little translucency or transparency
2 More sclerosis than in category 1 but less than halfway between categories 1 and 4
3 Less sclerosis than in category 4 but more than halfway between categories 1 and 4
4 Significant sclerosis present; dentin is dark yellow or even discolored (brownish); glassy appearance, with significant translucency or transparency evident

a Adapted from Swift et al. with permission from Elsevier.

To calibrate the restorative procedure, the study director placed one restoration of each group to identify all steps involved in the application technique. Then, the two operators, who were resident dentists with more than five years of clinical experience in operative dentistry, placed four restorations, one of each group, under the supervision of the study director in a clinical setting. The restoration failures were shown to the operators prior to starting the study. At this point, the operators were considered calibrated to perform the restorative procedures.

The operators restored all teeth. All participants received four restorations, one of each experimental group in different lesions previously selected according to the inclusion criteria.

Before restorative procedures, the operators anesthetized the teeth with a 3% mepivacaine solution (Mepisv, Nova DFL, Rio de Janeiro, RJ, Brazil) and cleaned all lesions with pumice and water in a rubber cup, followed by rinsing and drying. Then, shade selection was made using a shade guide.

After rubber dam was placed, half of NCCLs had the dentin roughened with a diamond bur (#3168, KG Sorense, Barueri, SP, Brazil) for 5 s in high speed with water cooling (#3134; KG Sorensen, Barueri, SP, Brazil) before application of the adhesive systems. As all cavities were circumvent by enamel, we consider that the, at least, superficial enamel was also roughened. The other half of NCCLs received no treatment in terms of roughening. The new universal adhesive system Tetric N-Bond Universal (also known in some countries as Adhese Universal, Ivoclar Vivadent, Schaan, Liechtenstein) was applied as described below. The compositions, application modes, and batch numbers are described in Table 2 .

  • Etch-and-rinse – The 37% phosphoric acid (N-Etch, Ivoclar Vivadent, Schaan, Liechtenstein) was applied for 15 s. Then, cavities were rinsed thoroughly for 5 s, and slightly air-dried, keeping dentin visible moist. One coat of adhesive was gently scrubbed on the entire enamel and dentin surface for approximately 20 s, according to the manufacturer’s recommendations ( Table 2 ). Then, the adhesive was evaporated by gentle air stream for 5 s and light cured for 10 s at 1100 mW/cm 2 (Bluephase, Ivoclar Vivadent, Schaan, Liechtenstein).

  • Self-Etch group – The adhesive system was applied as described in the etch-and-rinse group, without the previous step of phosphoric acid application ( Table 2 ). Solvent evaporation and light curing procedures were also the same.

Table 2
Adhesive system: composition and application mode.
Adhesive systems (batch number) Composition a Application Mode b
Tetric N-bond Universal (Ivoclar Vivadent, Schaan, Liechnstein)/ S54248
  • 1.

    Etchant: 37% phosphoric acid in water (total etch)

  • 2.

    Adhesive: HEMA, MDP, Bis-GMA, MCAP, D3MA, ethanol, water, highly dispersed silicon dioxide and camphorquinone

Etch-and-Rinse (ER) No preparation (ER)
  • 1.

    Apply etchant for 15 s

  • 2.

    Rinse for 5 s

  • 3.

    Gently air dry, keep dentin visible moist

  • 4.

    Scrub one coat of adhesive for 20 s

  • 5.

    Gently air thin for 5 s

  • 6.

    Light-cure for 10 s at 1200 mW/cm 2

Enamel/dentin were roughened as a diamond bur for 5 s (ER + RO)
Self-Etch (SE) No preparation (SE)
  • 1.

    No etchant was applied

  • 2.

    Scrub one coat of adhesive for 20 s

  • 3.

    Gently air thin for 5 s

  • 4.

    Light-cure for 10 s at 1200 mW/cm 2

Enamel/dentin were roughened as a diamond bur for 5 s (SE + RO)

a HEMA = 2-hydroxyethyl methacrylate; MDP = methacryloyloxydecyl dihydrogen phosphate; Bis-GMA = bisphenol glycidyl methacrylate; MCAP = Methacrylated carboxylic acid polymer; D3MA = Decandiol dimethadrylate.

b According to the manufacturer’s instructions.

After adhesive application, the resin composite Empress Direct (Ivoclar Vivadent, Schaan, Liechtenstein) resin composite was used in up to three increments, each one being lightly cured for 10 s at 1100 mW/cm 2 . The restorations were finished immediately with fine and extra-fine #2200 diamond burs (KG Sorensen, Barueri, SP, Brazil) and polished with OptraPol NG (Ivoclar Vivadent, Schaan, Liechtenstein) under constant water-cooling.

Calibration procedures for clinical evaluation

For training purposes, two experienced and calibrated examiners observed 10 photographs that were representative of each score for each criterion. They evaluated 10 to 15 patients each on two consecutive days. These subjects had cervical restorations but were not part of this project. An intra-examiner and inter-examiner agreement of at least 85% was necessary before beginning the evaluation .

Blinding

The examiners were not involved with the restoration procedures and therefore blinded to the group assignment, performed the clinical evaluation. Patient were also blinded to group assignment in a double-blind randomized clinical trial design.

Clinical evaluation

An individual standardized paper case report form was used for each evaluator at each recall time so that evaluators were kept blinded to earlier evaluations during the follow-up recalls.

The restorations were evaluated by World International Federation criteria (FDI) and the classical United States Public Health Service (USPHS) criteria (adapted by Bittencourt and others and Perdigão and others ) at baseline and after six and eighteen months of clinical service. Only the clinically relevant measures for evaluation of adhesive performance were used and scored ( Tables 3 and 4 ). The primary clinical endpoint was retention/fracture, but the following secondary endpoints were also evaluated: marginal staining, marginal adaptation, postoperative sensitivity, and recurrence of caries. The evaluation of the spontaneous postoperative sensitivity was performed one week after the restorative procedure by asking the patient if he experienced any pain during the period.

Table 3
World Dental Federation (FDI) criteria used for clinical evaluation .
Esthetic Property Functional Properties Biological Properties
1. Staining margin 2. Fractures and retention 3. Marginal adaptation 4. Postoperative (hyper-) sensitivity 5. Recurrence of caries
1. Clinically very good 1.1 No marginal staining 2.1 Restoration retained, no fractures/cracks 3.1 Harmonious outline, no gaps, no discoloration. 4.1 No hypersensitivity. 5.1 No secondary or primary caries
2. Clinically good (after correction very good 1.2 Minor marginal staining, easily removable by polishing. 2.2 Small hairline crack. 3.2.1 Marginal gap (50 μm). 4.2 Low hypersensitivity for a limited period of time 5.2 Very small and localized demineralization.
3.2.2 Small marginal fracture removable by polishing. No operative treatment required
3. Clinically sufficient/satisfactory (minor shortcomings with no adverse effects but not adjustable without damage to the tooth) 1.3 Moderate marginal staining, not esthetically unacceptable. 2.3 Two or more or larger hairline cracks and/or chipping (not affecting the marginal integrity). 3.3.1 Gap < 150 μm not removable 4.3.1 Premature/slightly more intense 5.3 Larger areas of demineralization, but only preventive measures necessary (dentine not exposed)
3.3.2. Several small enamel or dentin fractures 4.3.2 Delayed/weak sensitivity; no subjective complaints, no treatment needed.
4. Clinically unsatisfactory (repair for prophylactic reasons) 1.4 Pronounced marginal staining; major intervention necessary for improvement 2.4 Chipping fractures which damage marginal quality; bulk fractures with or without partial loss (less than half of the restoration). 3.4.1 Gap > 250 μm or dentine/base exposed. 4.4.1 Premature/very intense 5. 4 Caries with cavitation (localized and accessible and can be repaired
3.4.2. chip fracture damaging margins 4.4.2 Extremely delayed/weak with subjective complaints
3.4.3 Notable enamel or dentine wall fracture 4.4.3 Negative Sensitivity Intervention necessary but not replacement.
5. Clinically poor (replacement necessary) 1.5 Deep marginal staining not accessible for intervention. 2.5 (Partial or complete) loss of restoration. 3.5 Filling is loose but in situ. 4.5 Very intense, acute pulpitis or non vital. Endodontic treatment is necessary and restoration has to be replaced. 5.5 Deep secondary caries or exposed dentine that is not accessible for repair of restoration.
Acceptable or not acceptable (n, % and reasons Aesthetic criteria Functional criteria Biological criteria

Table 4
Modified United States Public Health Service (USPHS) criteria according to Bittencourt and others and Perdigão and others .
Marginal staining Retention Fracture Marginal adaptation Postoperative sensitivity Recurrence of caries
Alfa No discoloration along the margin Retained None Restoration is continuous with existing anatomic form. No postoperative sensitivity directly after the restorative process and during the study period None evidence of caries contiguous with the margin
Bravo. Slight and superficial staining (removable, usually localized) Partially retained Small chip, but clinically acceptable Detectable V-shaped defect in enamel only. Catches explorer going both ways.
Charlie Deep staining cannot be polished away Missing Failure due to bulk restorative fracture Detectable V-shaped defect to dentin-enamel junction Sensitivity present at any time during the study period Evidence of presence of caries

These variables were ranked according to FDI criteria into clinically very good, clinically good, clinically sufficient/satisfactory, clinically unsatisfactory but repairable, and clinically poor (replacement required) and in the USPHS criteria into alfa, bravo, and Charlie . Both examiners evaluated all the restorations once and independently. When disagreements occurred during the evaluations, they had to reach a consensus before the participant was dismissed. The restoration retention rates were calculated according to the ADA guidelines . Cumulative failure percentage = [(PF + NF)/(PF + RR)] × 100%, where PF is the number of previous failures before the current recall, NF is the number of new failures during the current recall, and RR is the number of currently recalled restorations.

Statistical analysis

The statistical analyses followed the intention-to-treat protocol according to CONSORT (Consolidated Standards of Reporting Trials) suggestion . Descriptive statistics were used to describe the distributions of the evaluated criteria. Statistical analysis for each individual item was performed for each evaluation criteria (FDI and USPHS criteria).

The differences in the ratings of the four groups after 6 and 18 months were tested with the Friedman repeated-measures analysis of variance by rank (α = 0.05), and differences in the ratings of each group at baseline and after 6 and 18 months were evaluated using the Wilcoxon test (α = 0.05). Cohen’s kappa statistics was used to test inter-examiner agreement. In all statistical tests, we pre-set the level of significance to 5%.

Materials and methods

The description of the experimental design followed the Consolidated Standards of Reporting Trials (CONSORT) statement .

Ethics approval

The local Ethics Committee on Investigations Involving Human Subjects reviewed and approved the protocol and issued a consent form for this study (protocol CB027-2014). Written informed consent was obtained from all participants prior to starting the treatment.

Protocol registration

This clinical trial was registered in clinicaltrial.gov clinical registry under protocol # NCT02751970. All participants were informed about the nature and objectives of the study.

Trial design, settings and location of data collection

This was a double-blind, superiority, split-mouth randomized clinical trial. The study was carried out in the clinics of the School of Dentistry at the local University from January 2015 to November 2015.

Recruitment

Patients were recruited as they seek for treatment in the clinics of Dentistry of the local university. No advertisement was made for participant recruitment. Patients were recruited in the order in which they reported for the screening session, thus forming a sample of convenience.

Eligibility criteria

A total of 65 participants were examined by two calibrated dental students to check if they met the inclusion and exclusion criteria ( Fig. 1 ). The evaluations were performed using a mouth mirror, an explorer, and a periodontal probe. Participants had to be in good general health, be at least 18 years old, have an acceptable oral hygiene level, and present at least 20 teeth under occlusion.

Fig. 1
Flow diagram. Np: number of patients, Nr: number of restorations. SE = Self-etch, no preparation; ER = Etch-and-Rinse, no preparation; SE + RO = Self-etch, roughening dentin; ER + RO = Etch-and-Rinse, roughening dentin.

Participants were required to have at least four NCCLs to be restored in four different teeth. These lesions had to be non-retentive, deeper than 1 mm, and involve both the enamel and dentin of vital teeth without mobility. The cavosurface margin could not involve more that 50% of enamel . Patients with extremely poor oral hygiene, severe or chronic periodontitis, or heavy bruxism habits were excluded from the study as they would receive other treatments before restorative intervention.

Sample size calculation

The annual retention rate to one-step self-etch adhesives in NCCLs was reported to be 4.4% in a recent systematic review . Considering that this decline follow a linear trend, the overall retention rate of one-step self-etch adhesives will be approximately 78% after 5-year of clinical service. With an α of 0.05, a power of 80%, and a two-sided test, the minimal sample size will be 40 restorations in each group in order to detect a difference of 30% among the test groups . It was added 20% more patients to compensate future losses.

Random sequence generation and allocation concealment

The randomization was done on an intra-individual basis so that each subject ended up with four restorations, each one resulting from one of all possible combinations of adhesive strategy and roughening procedure. These randomization schemes were performed using software available at www.sealedenvelope.com .

A staff member not involved in the research protocol performed the randomization process with computer-generated tables. Details of the allocated groups were recorded on cards contained in sequentially numbered, opaque, sealed envelopes. Opening the envelope only on the day of the restorative procedure guaranteed the concealment of the random sequence. In all cases, the tooth with the highest tooth number received the treatment described first, while the tooth with the next number in sequence received the treatment mentioned second, with placement continuing in a similar manner until the fourth tooth. All restorations in the same subject were always placed in different sextants.

Interventions: restorative procedure

All the patients selected for this study received dental prophylaxis with a suspension of pumice and water in a rubber cup and signed an informed consent form two weeks before the restorative procedures.

The degree of sclerotic dentin from the NCCLs was measured according to the criteria described by Swift and others ( Table 1 ). The cavity dimensions in millimeters (height, width, and depth), the geometry of the cavity (evaluated by profile photograph and labeled at <45°, 45°–90°, 90° < 135°, and >135°) , the presence of an antagonist, and the presence of attrition facets were observed and recorded. Pre-operative sensitivity was also evaluated by applying air for 10 s from a dental syringe placed 2 cm from the tooth surface and with an explorer. These features were recorded to allow comparison of the baseline features of the dentin cavities among experimental groups.

Table 1
Dentin sclerosis scale. a
Category Criteria
1 No sclerosis present; dentin is light yellowish or whitish, with little discoloration; dentin is opaque, with little translucency or transparency
2 More sclerosis than in category 1 but less than halfway between categories 1 and 4
3 Less sclerosis than in category 4 but more than halfway between categories 1 and 4
4 Significant sclerosis present; dentin is dark yellow or even discolored (brownish); glassy appearance, with significant translucency or transparency evident

a Adapted from Swift et al. with permission from Elsevier.

To calibrate the restorative procedure, the study director placed one restoration of each group to identify all steps involved in the application technique. Then, the two operators, who were resident dentists with more than five years of clinical experience in operative dentistry, placed four restorations, one of each group, under the supervision of the study director in a clinical setting. The restoration failures were shown to the operators prior to starting the study. At this point, the operators were considered calibrated to perform the restorative procedures.

The operators restored all teeth. All participants received four restorations, one of each experimental group in different lesions previously selected according to the inclusion criteria.

Before restorative procedures, the operators anesthetized the teeth with a 3% mepivacaine solution (Mepisv, Nova DFL, Rio de Janeiro, RJ, Brazil) and cleaned all lesions with pumice and water in a rubber cup, followed by rinsing and drying. Then, shade selection was made using a shade guide.

After rubber dam was placed, half of NCCLs had the dentin roughened with a diamond bur (#3168, KG Sorense, Barueri, SP, Brazil) for 5 s in high speed with water cooling (#3134; KG Sorensen, Barueri, SP, Brazil) before application of the adhesive systems. As all cavities were circumvent by enamel, we consider that the, at least, superficial enamel was also roughened. The other half of NCCLs received no treatment in terms of roughening. The new universal adhesive system Tetric N-Bond Universal (also known in some countries as Adhese Universal, Ivoclar Vivadent, Schaan, Liechtenstein) was applied as described below. The compositions, application modes, and batch numbers are described in Table 2 .

  • Etch-and-rinse – The 37% phosphoric acid (N-Etch, Ivoclar Vivadent, Schaan, Liechtenstein) was applied for 15 s. Then, cavities were rinsed thoroughly for 5 s, and slightly air-dried, keeping dentin visible moist. One coat of adhesive was gently scrubbed on the entire enamel and dentin surface for approximately 20 s, according to the manufacturer’s recommendations ( Table 2 ). Then, the adhesive was evaporated by gentle air stream for 5 s and light cured for 10 s at 1100 mW/cm 2 (Bluephase, Ivoclar Vivadent, Schaan, Liechtenstein).

  • Self-Etch group – The adhesive system was applied as described in the etch-and-rinse group, without the previous step of phosphoric acid application ( Table 2 ). Solvent evaporation and light curing procedures were also the same.

Table 2
Adhesive system: composition and application mode.
Adhesive systems (batch number) Composition a Application Mode b
Tetric N-bond Universal (Ivoclar Vivadent, Schaan, Liechnstein)/ S54248
  • 1.

    Etchant: 37% phosphoric acid in water (total etch)

  • 2.

    Adhesive: HEMA, MDP, Bis-GMA, MCAP, D3MA, ethanol, water, highly dispersed silicon dioxide and camphorquinone

Etch-and-Rinse (ER) No preparation (ER)
  • 1.

    Apply etchant for 15 s

  • 2.

    Rinse for 5 s

  • 3.

    Gently air dry, keep dentin visible moist

  • 4.

    Scrub one coat of adhesive for 20 s

  • 5.

    Gently air thin for 5 s

  • 6.

    Light-cure for 10 s at 1200 mW/cm 2

Enamel/dentin were roughened as a diamond bur for 5 s (ER + RO)
Self-Etch (SE) No preparation (SE)
  • 1.

    No etchant was applied

  • 2.

    Scrub one coat of adhesive for 20 s

  • 3.

    Gently air thin for 5 s

  • 4.

    Light-cure for 10 s at 1200 mW/cm 2

Enamel/dentin were roughened as a diamond bur for 5 s (SE + RO)

a HEMA = 2-hydroxyethyl methacrylate; MDP = methacryloyloxydecyl dihydrogen phosphate; Bis-GMA = bisphenol glycidyl methacrylate; MCAP = Methacrylated carboxylic acid polymer; D3MA = Decandiol dimethadrylate.

b According to the manufacturer’s instructions.

After adhesive application, the resin composite Empress Direct (Ivoclar Vivadent, Schaan, Liechtenstein) resin composite was used in up to three increments, each one being lightly cured for 10 s at 1100 mW/cm 2 . The restorations were finished immediately with fine and extra-fine #2200 diamond burs (KG Sorensen, Barueri, SP, Brazil) and polished with OptraPol NG (Ivoclar Vivadent, Schaan, Liechtenstein) under constant water-cooling.

Calibration procedures for clinical evaluation

For training purposes, two experienced and calibrated examiners observed 10 photographs that were representative of each score for each criterion. They evaluated 10 to 15 patients each on two consecutive days. These subjects had cervical restorations but were not part of this project. An intra-examiner and inter-examiner agreement of at least 85% was necessary before beginning the evaluation .

Blinding

The examiners were not involved with the restoration procedures and therefore blinded to the group assignment, performed the clinical evaluation. Patient were also blinded to group assignment in a double-blind randomized clinical trial design.

Clinical evaluation

An individual standardized paper case report form was used for each evaluator at each recall time so that evaluators were kept blinded to earlier evaluations during the follow-up recalls.

The restorations were evaluated by World International Federation criteria (FDI) and the classical United States Public Health Service (USPHS) criteria (adapted by Bittencourt and others and Perdigão and others ) at baseline and after six and eighteen months of clinical service. Only the clinically relevant measures for evaluation of adhesive performance were used and scored ( Tables 3 and 4 ). The primary clinical endpoint was retention/fracture, but the following secondary endpoints were also evaluated: marginal staining, marginal adaptation, postoperative sensitivity, and recurrence of caries. The evaluation of the spontaneous postoperative sensitivity was performed one week after the restorative procedure by asking the patient if he experienced any pain during the period.

Table 3
World Dental Federation (FDI) criteria used for clinical evaluation .
Esthetic Property Functional Properties Biological Properties
1. Staining margin 2. Fractures and retention 3. Marginal adaptation 4. Postoperative (hyper-) sensitivity 5. Recurrence of caries
1. Clinically very good 1.1 No marginal staining 2.1 Restoration retained, no fractures/cracks 3.1 Harmonious outline, no gaps, no discoloration. 4.1 No hypersensitivity. 5.1 No secondary or primary caries
2. Clinically good (after correction very good 1.2 Minor marginal staining, easily removable by polishing. 2.2 Small hairline crack. 3.2.1 Marginal gap (50 μm). 4.2 Low hypersensitivity for a limited period of time 5.2 Very small and localized demineralization.
3.2.2 Small marginal fracture removable by polishing. No operative treatment required
3. Clinically sufficient/satisfactory (minor shortcomings with no adverse effects but not adjustable without damage to the tooth) 1.3 Moderate marginal staining, not esthetically unacceptable. 2.3 Two or more or larger hairline cracks and/or chipping (not affecting the marginal integrity). 3.3.1 Gap < 150 μm not removable 4.3.1 Premature/slightly more intense 5.3 Larger areas of demineralization, but only preventive measures necessary (dentine not exposed)
3.3.2. Several small enamel or dentin fractures 4.3.2 Delayed/weak sensitivity; no subjective complaints, no treatment needed.
4. Clinically unsatisfactory (repair for prophylactic reasons) 1.4 Pronounced marginal staining; major intervention necessary for improvement 2.4 Chipping fractures which damage marginal quality; bulk fractures with or without partial loss (less than half of the restoration). 3.4.1 Gap > 250 μm or dentine/base exposed. 4.4.1 Premature/very intense 5. 4 Caries with cavitation (localized and accessible and can be repaired
3.4.2. chip fracture damaging margins 4.4.2 Extremely delayed/weak with subjective complaints
3.4.3 Notable enamel or dentine wall fracture 4.4.3 Negative Sensitivity Intervention necessary but not replacement.
5. Clinically poor (replacement necessary) 1.5 Deep marginal staining not accessible for intervention. 2.5 (Partial or complete) loss of restoration. 3.5 Filling is loose but in situ. 4.5 Very intense, acute pulpitis or non vital. Endodontic treatment is necessary and restoration has to be replaced. 5.5 Deep secondary caries or exposed dentine that is not accessible for repair of restoration.
Acceptable or not acceptable (n, % and reasons Aesthetic criteria Functional criteria Biological criteria
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Jun 17, 2018 | Posted by in General Dentistry | Comments Off on Effect of dentin roughness on the adhesive performance in non-carious cervical lesions: A double-blind randomized clinical trial
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