Clinical Evaluation of Restorations Using Universal Adhesive Systems After 3 Years

The aim of this study is to examine the adhesive success of class II composite restorations made using six different dental adhesives in patients treated. From the voluntary patient group, which included 186 restorations in a total of 105 patients included in the study, 85 patients agreed to come for a control 3 years after the date of procedure, and a total of 141 restorations were evaluated by an only one dentist according to modified USPHS criteria. According to the criteria evaluated, the use of universal adhesives in self-etch mode in the construction of Class II restorations was found to be 98.6% successful in total at the end of three years. There was no statistically significant difference in clinical success between all adhesive resin groups (p>0.05). As a result of a 3-year retrospective evaluation of six different universal adhesives used in the study, all adhesives showed clinically acceptable success.

Keywords: Modified USPHS Criteria, Retrospective Study, Universal Adhesives

Adhesive dentistry has continued to develop rapidly since the 1990s [1]. Adhesive techniques using tooth-colored restorative materials enable teeth to be restored not only anatomically and functionally, but also aesthetically [2]. The basic mechanism of bonding to enamel and dentin; it is the micro-mechanical bonding of resin monomers by penetrating into the pores created by the minerals lost from the tooth tissue due to acid application. Using adhesive systems, the connection between biomaterial and dental tissue is achieved in one, two or three clinical application steps. Dental adhesive systems can be classified as “total etch”, “self-etch” and “glass ionomer adhesives” according to the adhesion mechanism as well as the number of application steps [3]. Self-etch adhesive systems are classified as mild (pH>2), medium (1<pH<2) and strong (pH<1) based on the acidity levels affecting the bond [4].

Furthermore, the classification of adhesive systems to date has been as follows: [5]

• Classification according to generations:

1st Generation: – NPG-GMA 2-3 Mpa;

2nd Generation: – phenyl-P, HEMA 1-5 Mpa;

3rd Generation: – HEMA, 10-MDP, PMDM + NPG-GMA, etching; hybrid layer;

4th Generation: – Three Stage Total Etch (acid + primer + bond) 17-30 Mpa;

5th Generation: – Single Bottle Total Etch (acid + [primer + bond]);

6th Generation: – Two Stage Self Etch ([acid + primer] + bond) No separate etching and washing steps;

7th Generation: – Single-Stage Self-Etch (All in One).

• Classification according to the effect on the smear layer:
• Applied on the smear layer;
• Modifying the smear layer;
• Completely removing the smear layer (removing);
• Partially dissolving the smear layer (dissolving).

First generation dental adhesives are relatively hydrophobic and require drying of the tooth for bonding. Placing adhesives on the smear layer cannot provide sufficient bond strength. Demineralization of intact dentin has been attempted to be achieved with systems that remove or modify the smear layer. By adding hydrophilic and acidic resin monomers to the adhesive system, bonding to wet tooth surfaces is significantly improved [6]. As the number of application steps of adhesive systems increases, the hydrophilicity and dentinal fluid permeability of the adhesive resin increases. This increase in permeability weakens the bond of the adhesive resin to dentin [1].

Improving the clinical behavior of the material used can be achieved in two different ways. The first is to adjust the proportions of ingredients in dental adhesives. Changing the number of application steps also means changing the formulation of dental adhesives. The second is to design new components. In particular, monomers can be modified to provide specific properties regarding polymerization and chemical bonding. This method is time consuming and expensive. The first method is widely used, and the development of new components and custom-made monomers seems promising for a significant improvement of dental adhesives [7]. One-step self-etch adhesive systems are hydrophilic structures that contain high concentrations of both ionic and hydrophilic monomers [8]. It was stated that universal adhesives can be used in self-etch mode by adding hydrophobic dimethacrylates to dental adhesive systems [9] developed to create stronger cross-linked polymer networks [10]. Evaluation of the use of composite restorations with these developed adhesive systems in clinical (in vivo) studies is the gold standard. This is because none of the other parameters can be evaluated if the restorations are lost [11].

The aim of this study is to retrospectively evaluate class II restorations using the self-etch mode of universal adhesive systems according to modified USPHS criteria after three years. The first hypothesis of this study; There is no difference in terms of Modified USPHS criteria between the universal adhesives used in the study. Second hypothesis; there is no difference in clinical success between the universal adhesives used in the study.

Our study includes patients between the ages of 18-25, with acceptable oral hygiene, without any pulpal or periodontal disease symptoms and systemic health problems, and who applied to the restorative dental treatment clinic due to caries. Class II restorations in the posterior region between January 2018 and January 2019 were evaluated. Patients who had any systemic health problems, had deep class II restorations, refused to participate in the study, and were unable to attend follow-up controls were excluded from the evaluation. The power analysis of this study was performed with the statistical power calculation program (G-Power, ver. 3.1.9.4 F.Paul, Kiel University, Germany) and a total of 141 restorations were included in the study, with a minimum of 15 restorations in each group. It was important that the restorations included in the study were made with one of six different universal adhesives with pH values ​​shown in Table 2.1.

Table 2.1. pH Values ​​of Adhesive Resins

In this study, volunteer patients who used the universal adhesive systems shown in Table 2.2 and composite materials of the same company in the restoration were included in the evaluation. The universal adhesives used had the content specified in Table 2.3 and were applied in accordance with the recommended instructions for use.

Table 2.2. Universal Adhesives and Dental Composites Used in the Restoration of Teeth

1- G Premio Bond		G-aenial Anterior Composite
2- Tetric N-Bond Universal		Tetric N Ceram Bulk Fill
3- Clearfil Universal Bond		Clearfil Photo Posterior
4- All-Bond Universal		AELITE All Purpose Body
5- Prime & Bond Universal		Ceram.X SphereTec One Composite
6- Nova Compo B Plus		Nova Compo N

Table 2. 3. Adhesive Resin Content and Instructions for Use

Adhesive	Production	Content	Solvent	Instructions for Use
G-Premio Bond	GC Corporation, Tokyo, Japan	10-MDP, 4-META, dimethacrylate monomer, MDTP(10-methacryloyloxydecyl dihydrogen thiophosphate), distilled water, acetone, photo initiator, fine silica powder	Water, acetone	1- It is applied for 10 seconds using a micro brush. 2- It is dried with air spray for 5 s. 3- It is polymerized for 10 seconds.
Tetric N-Bond Universal	Ivoclar Vivadent, Schaan, Liechtenstein	MDP, HEMA, ethanol, water, high percentage of silicon dioxide, initiator, stabilizer, D3MA and MCAP (methacrylated carboxylic acid polymer)	Water, ethanol	1- It is applied by rubbing on the tooth surface for 20 seconds. 2- It is dried in a way that does not form a film thickness. 3- It is polymerized for 10 seconds.
Clearfil Universal Bond	Kuraray, Noritake, Japan	10-MDP, Bis-GMA, HEMA, ethanol, hydrophilic aliphatic dimethacrylate, colloidal silica, 4-MET, dl-camphorquinone, silane	Water, ethanol	1- It is applied to the tooth surface by rubbing for 10 seconds using the applicator. 2- It is gently dried for 5 seconds until no movement is observed in the adhesive layer. 3- It is polymerized for 10 seconds.
All-Bond Universal	BISCO Dental Products, USA	MDP, Bis-GMA, HEMA, ethanol	Water, ethanol	1- It is applied in two separate stages, by rubbing for 10-15 seconds without polymerizing between applications. 2- It is dried with air spray for 10 seconds until there is no movement in the adhesive layer. 3- It is polymerized for 10 seconds.
Prime & Bond Universal	Dentsply, Sirona	PENTA, 10-MDP, Active Guard™ Technology	Water, isopropanol	1- It is applied to the entire surface without causing ponding. 2- It is applied by rubbing for 20 seconds. 3- The solvent part is removed with air for 5 s. 4- It is polymerized for 10 seconds.
Nova Compo B Plus	Imicryl Inc., Konya, Türkiye	Bis-GMA, 2-HEMA, ethanol, MDP, 4-MET, silanated nanosilica, dl-camphorquinone, accelerator, initiator, water	Water, ethanol	1-It is applied by rubbing for 20 seconds. 2- Gently air dry for 5 s. 3- It is polymerized for 10 seconds.

For the restorations performed in the Restorative Dentistry Clinic, the date of restoration, the universal adhesive resin-dental composite material group used during the restoration were recorded, and control groups were formed. A total of 105 patients in these groups were included in the study. Patients were divided into six groups according to the adhesive systems and composite materials used:

1 – G Premio Bond (GC Corporation, Tokyo, Japan) + G-aenial Anterior Composite;

2 – Tetric N-Bond Universal (Ivoclar Vivadent) , Schaan, Liechtenstein) + Tetric N Ceram Bulk Fill;

3 – Clearfil Universal Bond (Kuraray Noritake, Tokuyama, Japan) + Clearfil Photo Posterior;

4 – All-Bond Universal (Bisco, USA) + AELITE All Purpose Body (Bisco);

5 – Prime & Bond Universal (Dentsply, Sirona) + Ceram.X SphereTec One Composite (Dentsply, Sirona);

6 – Nova Compo B Plus (Imicryl, Türkiye) + Nova Compo N.

Three years later, the tooth and restoration surfaces were dried and evaluated under reflector light by a dentist using an intraoral mirror and probe, according to the modified USPHS criteria. According to modified USPHS criteria; the stability of the anatomical form, marginal adaptation changes and possible marginal discolorations, any sensitivity at the patient after the procedure, tooth and restoration color compatibility, the presence of retention areas and secondary caries supported by radiographs were evaluated.

Scores of the findings were grouped as follows:

– Alfa (A), excellent clinical success;

– Bravo (B), clinically acceptable success;

– Charlie (C), clinically unacceptable success [12]. All collected data, together with the dental photographs taken, were recorded in the pre-prepared evaluation form shown in Table 2.4.

Table 2. 4. Evaluation Form

Each of the Modified USPHS criteria data obtained from volunteer patients whose teeth were restored using different universal adhesive systems and who were included in the study were statistically evaluated in pairs with the Two Proportion Test.

From the volunteer group consisting of 67 females (112 restorations) and 38 males (74 restoration) patients with completed restorations, 54 females (92 restorations) and 31 males (49 restoration) patients agreed to participate in this retrospective study. The maxillary and mandibular distribution of the evaluated teeth is given in Table 3.1.

Table 3. 1. The Maxillary and Mandibular Distribution of the Evaluated Teeth

Telephone interviews were conducted with all patients for the 3-year evaluation and patients were invited back to the clinic. Unfortunately, 15 of the patients could not be reached, and 1 patient in the Nova Compo B Plus patient group was excluded from the study group because his restoration was replaced 1 year later due to secondary caries. In this study conducted on volunteer patients, 81% (85 patients) of 186 Class II restorations of 105 patients were reached after 3 years, and 75.8% (141 restorations) of the restorations were re-examined. Re-examination was performed at a rate of 73% in the G-Premio Bond group, 72% in the Tetric N-Bond Universal group, 60% in the Clearfil Universal Bond group, 86% in the All-Bond Universal group, 88% in the Prime & Bond Universal group, and 94% in the Nova Compo B Plus group. 141 restorations were evaluated according to modified USPHS criteria. The number and percentage distribution of the scores obtained by retrospective evaluation of restorations made using different adhesive systems after 3 years are shown in Table 3.2.

Table 3. 2. Percentage Distribution of Restorations Evaluated According to Modified USPHS Criteria*

*Brackets represent the number of restorations.

When the restorations in our study were evaluated according to the modified USPHS Criteria; in the anatomical form examination, among six different universal adhesives, clinically acceptable B score was seen more frequently in the G-Premio Bond group. In the All-Bond Universal group, all restorations were recorded as A score. In marginal adaptation evaluations, the highest B score was seen in the G-Premio Bond and Tetric N-Bond groups. All restorations in the Nova Compo B Plus group were recorded as A score. For marginal coloration value, the highest B score was seen in the Clearfil Universal Bond group, while the Tetric N-Bond group received the highest A score. For post-operative sensitivity, a single C score was detected in the G-Premio bond group, while there was no difference between the Tetric N-Bond, Clearfil Universal Bond, All Bond Universal and Nova Compo B Plus groups, and an A score was recorded in all restorations. In the evaluation of color match, the highest B scores were detected in the G-Premio Bond and Nova Compo B Plus groups. The C score for loss of retention was recorded only in a single restoration in the Clearfil Universal Bond group. There was no difference between the All Bond Universal, Prime & Bond Universal and Nova Compo B Plus groups, and all restorations were recorded as A score. In secondary caries evaluations, a single C score was recorded in the G-Premio Bond group. There was no difference between Clearfil Universal Bond, All Bond Universal and Nova Compo B Plus groups and all were recorded as A score.

In our study, in which we retrospectively evaluated the restorations performed at the Restorative Dentistry Clinic of Selçuk University Faculty of Dentistry, we found that the use of universal adhesives in the self-etch mode was successful according to the modified USPHS criteria. When all criteria were evaluated, a total success rate of 98.6% was achieved. The length of time the restorations stay in the mouth depends on many factors such as the patient’s oral hygiene, susceptibility to caries, and the materials and techniques used. Most of the patients evaluated in our study have good oral hygiene and do not have caries or periodontal problems, which explains the high success rates of the restorations.

The lifespan of dental restorations can be influenced by various factors, including the type and location of the teeth, the size of the caries, the patient’s age and gender, and the restorative material used [13,14]. As a result of the development of modern adhesive systems over time, adhesive resin-dentin tissue bond values strive to reach a level that can show successful results against problems such as possible microleakage, marginal discoloration, adaptation disorders, secondary caries and related postoperative sensitivity [15,16]. The infiltration of monomers with both hydrophobic and hydrophilic groups into dental tissues forms the adhesion system. The polymerization process of monomers penetrating into dental tissues prevents stress accumulation at the adhesive resin-dentin tissue interface [17]. Universal adhesive systems are developed by adding functional acidic monomers to single-step self-etch adhesive systems, according to the recent adhesive system classification [18]. These functional monomers, which form chemical bonds with hydroxyapatite, are effectively acidic monomers; such as 2-MEP, 4-MET, 10-MDP, Phenyl-p, Bis-HEMA P, HEMA P, MAC 10, GPDM, MA, 4-AETA, GDMA-P, MDPB. [7, 19, 20] 10-MDP monomers, responsible for demineralization and chemical bonding, is important as it was the first functional monomer used in universal adhesives. It binds to the hydroxyapatite structure and forms stable MDP-Ca bridges, and establishes a connection between dental tissues and restorative material with its methacrylate tip and hydrophilic phosphate tip [21]. All of the adhesives we evaluated in our study contain 10-MDP. Additionally, G-Premio Bond contains functional monomers such as 4-META, MDTP; Tetric N-Bond contains D3MA, MCAP; Clearfil Universal Bond contains 4-MET; Prime & Bond Universal contains PENTA; Nova Compo B Plus contains 4-MET. The abrasion of the dentin surface, the dissolution of the smear layer and the resulting adhesive resin-dentin interface connection stability are also related to acidity [22]. There are adhesives categorized according to their pH as ultra-mild (pH> 2.5), mild (pH ≈ 2), medium (pH ≈ 1.5) and strongly acidic (pH<1.5). [23, 24] In our study, G-Premio Bond has a pH of 1.5 and is an example of the intermediate self-etch group. Tetric-N Bond, All-Bond Universal, Prime & Bond Universal and Nova Compo B Plus have pH values ​​between 2.5-3.2 and are included in the ultra-mild self-etch group. Clearfil Universal Bond has a pH value of 2.3 and is in the mild self-etch group (Table 2.1.).

After conducting a 3-year retrospective evaluation of six different universal adhesives used in this study, all adhesives showed clinically acceptable success. As a result of this study, the first hypothesis of the study; ‘there is no difference between the universal adhesives used in the study in terms of Modified USPHS criteria’ was rejected because of the statistical evaluation of the Alfa and Bravo data obtained from the modified USPHS criteria, it was observed that there was a difference between them. No significant differences were observed in all adhesives tested, except for the differences detected in B scores, and a clinical success rate of 98.6% was determined. The second hypothesis of the study, ‘there is no difference in clinical success between the universal adhesives used in the study’ was accepted as the data obtained from all adhesive systems used in the study remained at the clinical acceptability level.

To increase the adhesive resin-dentin interface bond strength and durability of universal adhesives; There are laboratory studies to increase the adhesive resin-dentin interface bond strength and durability of universal adhesives such as application of MMP inhibitors during adhesive application to the dentin layer, application of cross-linking agent to the demineralized dentin surface, application of hydrophobic resin, separate acidification of the enamel layer, application of adhesive resin in two layers, application of adhesive resin by rubbing, increasing the waiting time for solvent evaporation, deproteinization of the acid treated dentin layer, use of ethanol-containing wet bonding, biomimetic remineralization [25, 26]. In vitro studies provide much information about the clinical performance of materials and need to be supported in vivo as well [27]. Criteria such as FDI, modified Ryge and modified USPHS are used in retrospective studies in which patients who have been treated within a certain period of time are recalled, all restorations are clinically monitored by the evaluator, and the performance of the restorations is evaluated [28].

Stating that treatment protocols constitute an accurate and reliable way to track the results of time information calculated from relatively standardized and regular records, Rho et al. collected their data from patient records at a university hospital. In their study, they concluded that the lifespan of posterior dental resin composites under occlusal load in the mouth can be determined by the dental adhesive system used rather than the restorative material and cavity classification, and that further research is needed on this subject [29]. In our study, we used the hospital follow-up system similar to Rho et al. We established a standardized procedure to evaluate the patients’ returns and the condition of the restorations and examined the treatments performed in accordance with the modified USPHS criteria.

In our study, in the re-evaluation of 141 restorations made with universal adhesive applied in self-etch mode, the values of anatomical form, marginal adaptation, marginal coloration, color matching were scored as Alfa and Bravo and found to be within clinically acceptable limits.

Similarly, Özkubat et al. reported that there was no significant difference in anatomical form, surface properties, coloration and color matching, and marginal adaptation scores up to 18th month depending on whether universal adhesive was used in total etch or self-etch mode [30].

Atalay et al. reported that the restorations obtained acceptable scores according to modified USPHS criteria at the end of a 36-month study comparing self-etch, total etch and selective etch modes of universal adhesives. Although the clinical values ​​of all restorations were acceptable, they concluded that restorations made using total etch and selective etch mode performed better clinically in terms of marginal discoloration and marginal adaptation than restorations made using self-etch mode [31].

Bayraktar et al. recorded the loss of retention in a single restoration as Charlie in a 1-year study evaluating restorations using universal adhesives, and stated that it was not statistically significant [32].

Similarly, we also determined the loss of retention in one of the restorations made using Clearfil Universal Bond. According to the results of our study, there is no clinical statistical difference at the loss of retention.

Loguercio et al reported that in their 36-month retrospective follow-up study, there was no post-operative sensitivity in any restoration in their evaluation using FDI and USPHS criteria [33].

In our 3-year follow-up study, postoperative sensitivity was detected in a single restoration in the restoration group using G-Premio Bond, according to modified USPHS criteria.

Pazinatto et al., in their 56-month follow-up study using universal adhesive, observed secondary caries in one of the restorations made in Class II cavities. Secondary caries, which was seen in only one patient, was associated with possible causes such as the patient changing hygiene habits and allowing bacteria to accumulate [34].

In our study, in the evaluation of secondary caries, Charlie values ​​were recorded in one restoration using G-Premio Bond and another restoration Prime&Bond Universal, among the restorations made in Class II cavities.

In the evaluation of the relatively new universal adhesive resin system, factors such as the bonding strength of the adhesive resin, different formulations of adhesive systems, the area where the restoration is located, and the oral hygiene of the patient may affect the clinical outcome.

As a result of a 3-year retrospective evaluation of six different universal adhesives used in this study, all adhesives showed clinically acceptable success. Increasing the number of long-term follow-up studies on universal adhesive resins that have entered widespread clinical use can guide the development of materials.

Acknowledgments

I would like to thank my professors at Selçuk University Faculty of Dentistry, Department of Restorative Dentistry, all my friends who helped me during the study, and my family who was always with me.

Conflicts of Interest

The authors declare no conflicts of interest.

% Percent

nm nanometer

μm micrometer

mm milimeter

Mpa mega pascal

s second

A Alfa

B Bravo

C Charlie

2-MEP Methakriloksi ethil phenil hydrogen phosphate

4-AETA 4- acryloyloxyethyl trimellitate anhydride

4-MET 4- methacryloxyethyl trimellitic acid

4-META 4-methacryloyloxylethyl trimellitate anhydride

10-MDP 10-methacryloxydecyl dihydrogen phosphate

A-D Adhesion-Decalsification

Bis GMA bisphenol A glycidyl methacrylate

Bis-HEMA P di-2-hydroksiethil methakril hydrogenphosphate

BPDM biphenil dimethakrilate

BHT butylhydroxytoluene

CHX chlorhexidine

D3MA decanediol dimethacrylate

DMAE-MA N,N- Dimethylamino Ethyl Methacrylate

DMP 1 Dentin Matrix Protein 1

DEJ Dento-Enamel Junction

FDI World Dental Federation

GPDM glycerol phosphate dimethacrylate

GDMA-P 1, 3 – glycerol dimethacrylate phosphate

HEMA 2-hydroxyethyl methacrylate

HEMA P 2-hydroxyethyl methacryl hydrogen phosphate

MA methacrylic acid

MAC 10 10-metakriloksidesil di-hidrojen fosfat

MDPB 12-Metakriloiloksidodesilpiridinyum bromür

MEHQ mono methyl ether hydroquinone MMP matriks metalloproteinaz

MDTP methacryloyloxydecyl dihydrogen thiophosphate

MCAP methacrylate carboxylic acid polymer

MDP-Ca Methacryloyloxidecyl dihydrogen phosphate – calcium

NaOCl sodium hypochlorite

NPG-GMA Glycerophosphoric acid dimethacrylate

OPPI p-octyloxy-phenyl-phenyl iodonium hexafluoroantimonate

PENTA dipentaerythritol pentaacrylate

Phenyl- P phenyl dihydrogen phosphate

PPD 1-phenyl-1,2 propanedione

PA proanthocyanide

PAA polyacrylic acid

PVPA polyvinylphosphoric acid

TEGDMA triethylene glycol dimethacrylate

THF tetrahydrofuran

TPO 2,4,6-trimethylbenzoyl diphenylphosphine oxide

UDMA urethane dimethacrylate

USPHS United States Public Health Service