A Comparative Study Of Knowledge and Protocols Followed For Application Of Dentin Bonding Agents Amongst General Dental Practitioners and Endodontists In Chennai: A Questionnaire Based Survey

Keywords

Dental Adhesives; Bonding Agents; Self Etch Adhesives; Dental Acid Etching; Smear Layer; Dentin.

Introduction

Before the advent of composites, silver amalgam was the choice of restorative material for posterior teeth; owing to its high compressive strength. [1] Recently, the demand for aesthetic restorations has increased, leading to increased use of composite resins for posterior restorations. [2] Although highly aesthetic, composite restorations are highly technique sensitive. [3]

Composite resins bond micromechanically to the tooth structure. [4] Bonding to dentin possesses a greater challenge, unlike bonding to enamel. [5] The bonding protocols have evolved from the conventional etch and rinse technique, to the more recent selective etch technique and self etch adhesives. Self etch adhesives have the benefit of the absence on intermediary step of rinsing, which makes it more user friendly and less technique sensitive while bonding dentin to the resin restoration. [6] Self etch adhesives do not open the dentinal tubules, rather they dissolve the smear plug. [7] On the other hand, enamel benefits from the etch and rinse technique, owing to its ability to create micro porosities. [8] This concept lead to the evolution of selective etch technique where enamel is selectively etched prior to application of a universal adhesive.

Having the right knowledge and understanding of the properties of various adhesive systems will help the dental practitioner adopt the technique best suited for enamel and dentine respectively. Only when the correct protocols are followed, will the restoration have a successful outcome. Composite restorations are performed by general dental practitioners as well as Endodontists who even specialize in the field of conservative and restorative dentistry.

Previously our team had conducted numerous clinical studies[9, 12] , case reports [13], in vitro studies [14, 17], surveys [18, 19] and reviews [20, 23] in various aspects of endodontics and conservative dentistry over the past five years from which the idea of the present study has stemmed. Thus the present survey was conducted to compare the bonding protocols followed by the general dental practitioners and Endodontists.

Aim and Objectives

The present study was conducted with an aim to study and compare the attitude and explore the materials and techniques employed during application of dentin bonding agents by general dentists and Endodontists in Chennai and determine ways to reinforce their knowledge and skills for delivering a more proficient treatment.

The study was carried out with the underlying objectives:

To study and compare the attitude of general dentists and Endodontists towards the application of dentin bonding agents.

To explore and compare the materials and techniques employed by the general dentists and Endodontists during application of dentin bonding agents.

To come to a conclusion as to how the general dentists and Endodontists can upgrade themselves for provision of a more efficient treatment.

Materials and Methods

The present cross sectional questionnaire based survey was conducted amongst 384 general dentists and Endodontists in Chennai who were selected through block randomization. Lottery Method was adopted for selection of practitioners from each block to ensure a random sampling & equal representation from each area. The inclusion criterion was set to include the general dentists and those associated with the specialty of Endodontics (students currently enrolled in the Endodontic post graduate program and the practicing Endodontists) willing to participate in the present survey and giving a written informed consent. The exclusion criteria of the study included those practitioners who were absent on the day of the survey and up to two rounds of follow up. Single proportion formula was used to determine a sample size of minimum 384 dental practitioners as follows:

N= (Za p (1-p)/d)2
N = sample size estimated.
Z a = variant of type one error.
p = proportion of good practice of dentin bonding technique assumed at 50%
d = estimated error in the present study fixed at 5%.

Hence a minimum of 384 dental practitioners were included in the study. Using a cluster design, there were two groups for comparison. Hence a minimum of 192 subjects were present in each group.

Prior to the start of the study, clearance and permissions were obtained from Institutional ethics committee (IEC) after the study protocol was sent and reviewed by 2 blinded reviewers.

Data was collected using a self designed, pre tested questionnaire comprising of 18 questions which was circulated amongst the general dentists and Endodontists. The questionnaire comprised of 5 sections. Section A comprised of questions on demographic details. Section B comprised of questions regarding isolation and bonding techniques used in different depths of cavities. Section C comprised of questions on etching protocols. Section D comprised of question on bonding protocols. Section E comprised of questions regarding the need for knowledge upgradation.

The questionnaire was collected on completion by the primary investigator. M.S Office excel sheet (V.2010) was used to code and enter the collected data. Descriptive statistics in the form of frequency and percentage were calculated using Statistical Package for Social Sciences (SPSS, V.22.0, 1BM). Comparison of frequencies of categories of variables with groups was done using chi square test. For all the statistical tests, p<0.05 was considered to be statistically significant, keeping a error at 5% and ß error at 20%, thus giving a power to the study as 80%.

Results and Discussion

In the present study 192 general dentists and 192 Endodontists were included. Amongst the participants 61.2%were female and 38.8% were male practitioners. The practitioners were further divided into two groups based on their years of experience. Group A comprised of 330 dental practitioners who had an experience of less than 10 years and group B comprised of 54 dental practitioners who had an experience of 10 years or more.

It was observed that 52.6% practitioners used a rubber dam only sometimes while placing a composite restoration, of which 114 were Endodontists and 88 were general dentists. An alarming number of 59 general dentists said they never used a rubber dam as compared to only 3 Endodontists. Yet, a majority of 65.4% practitioners said they felt that complete isolation using rubber dam was always necessary. General dentists mainly preferred complete removal of smear layer prior to bonding while modification of the dentinal smear layer was preferred by Endodontists. (Graph 1).

---

---

The general dentists and Endodontists followed a similar protocol of ‘etch and rinse’ total etch technique for etching the enamel. While a majority of 93 general dentists preferred the etch and rinse total etch technique for cavities involving the dentin; selective etch technique was preferred by the Endodontists. Both the general dentists and Endodontists preferred Indirect Pulp Capping (IPC) followed by base for deep cavities and used the etch and rinse total etch technique while only 22.75% practitioners adopted the selective etch protocol. (Graph 2)

---

---

Calcium hydroxide was the choice of indirect pulp capping agent by 127 general dentists, while 83 Endodontists preferred Biodentin. Glass inomer cement (GIC) was the choice for base by 50.8% practitioners of which majority were general dentists, while Biodentin was preferred by Endodontists. (Graph 3)

---

---

A majority of 53.6% practitioners preferred etching for 15seconds, while etching for 20 seconds was mainly preferred by the general dentists. A majority of 44.5% practitioners rinsed the cavity for 10 seconds post etching. For drying the cavity, 104 general dentists used air through a three way syringe to dry the entire cavity while 70 Endodontists used an absorbent paper selectively for the dentin and used air to dry the enamel only. (Graph 4)

---

---

A majority of 91 general dentists preferred applying a single layer of bonding agent while a majority of 88 Endodontists applied two layers of bonding agent. When asked if they used air to spread the bonding agent, a majority of 39.1% practitioners with an equal distribution of Endodontists and general dentists said they always did. While 70 general dentists said they never did, 68 Endodontists said they used air to spread the bonding agent only sometimes. (Graph 5)

---

---

A majority of 44% practitioners including the general dentists and Endodontists cured the bonding agent for 30 seconds. When asked about the intensity of the curing light, a majority of 86 general dentists were not aware of it while majority of Endodontists used curing light of intensity between 300 to 1300mW/cm2. A majority of 88.8% practitioners held the curing light directly over the tooth, but not touching the tooth. (Graph 6)

---

---

A majority of 94.3% practitioners felt the need to upgrade their knowledge and 76% practitioners felt that workshops, seminars and symposiums were efficient ways of knowledge upgradation. (Graph 7)

---

---

Statistical significant difference in responses was observed while comparing the two groups based on type of practice and years of experience (P<0.05). (Table 1 and 2)

---

---

---

---

The present study revealed that the more recent techniques of modification of dentinal smear layer and the use of selective etch technique were mainly preferred by the Endodontists. They also preferred the use of biodentin against the conventional calcium hydroxide for IPC. One of the probable reasons for this could be that the Endodontists get trained in the field of conservative dentistry during their post graduation, giving them an opportunity to learn the more recent advances at the institutional level.

In the present study, it was seen that complete isolation using rubber dam is not always performed during a composite restoration even though the practitioners were aware of its importance. These results are in accordance to a study conducted by Gilmour. et.al which states that only 5% of the general dental practitioners in UK placed rubber dam during posterior composite restoration. [24] The role of rubber dam in maintaining a sterile environment at the site of the procedure cannot be deemphasized. Moreover, the bonding of a composite restoration to the tooth structure requires an environment that is free of moisture contamination. [25]

Complete removal of smear layer using the etch and rinse total etch technique was still the most prevalent etching protocol irrespective of the depth of the cavity. An etching time of 15 seconds followed by rinsing for 10 seconds and drying the cavity using air through a three way syringe was the protocol that was opted by a majority of the practitioners. These results are in accordance to a study conducted by Nesser.et.al amongst senior dental students. [6]

Currently there are two approaches for bonding which are widely being followed; ‘etch and rinse’ and the ‘self-etch’ technique. During cavity preparation, a smear layer is formed on the tooth surface which prevents effective bonding of the restoration. [26] The ‘etch and rinse total etch’ approach focuses on complete removal of this smear layer. [27] However, complete removal of smear layer from the dentin opens the dentinal tubules and increases the permeability through the tubules. [28] This dentinal fluid is believed to affect the bond strength. [29] The self etch adhesives focus on incorporating the smear layer. [30] The effect of acid etching on enamel and dentin differ due to their different compositions. Acid etching is beneficial for enamel owing to its ability to dissolve enamel rods and create micro porosities. [31] However, Dentin contains dentinal fluids and only 70% inorganic matter. Acid etching of dentin exposes the collagen fibrils which are then completely uncovered by hydroxyapatite crystals. [7, 27]

The ‘etch and rinse’ approach, requires the acid to be rinsed, followed by drying of the cavity as an intermediary step. Excessive drying of the cavity results in dehydration of dentin which eventually leads to collapse of the collagen fibrils. Once the collagen fibrils collapse, it prevents the diffusion of the resin monomer. Hence dentin requires some amount of water to keep the collagen fibrils intact to facilitate the formation of hybrid layer. [32] However, presence of excessive moisture prevents the complete polymerization of resin and leads to adsorption of water in the hybrid layer. [33] Thus the ‘etch and rise’ approach is highly technique sensitive when used in prepared cavities that involve dentin. One of the approaches to prevent dehydration of dentin is to use an absorbent paper selectively for drying the dentinal tissue and using air to dry enamel only.

As ‘Self-etch’ adhesives simplify the control of moisture they are best suited for dentin. However, the ‘etch and rinse’ approach is highly imperative to achieve adequate bond strength between the enamel and resin restoration. [34] The selective etch technique focuses on etching the enamel to improve the bond strength before the application of a universal adhesive.

Frankenberger.et.al in his study to compare the ‘etch and rinse’, ‘self-etch’ and ‘selective etch’ approach, states that bonding of the resin restoration to enamel when a self etch adhesive is used, is more effective when enamel is etched using phosphoric acid. [35] These results were in accordance to the study conducted by Ermis.at.al. [36]

The difference in the inorganic and organic composition of enamel and dentine also has an effect on the etching time. It is desirable to dissolve only minimum amount of enamel and dentin that is adequate enough to give optimum bond strength. [37] While enamel requires an etching time of 30 seconds, an etching time of 15 seconds is adequate for dentin. [38] Etching increases the concentration of calcium and phosphate ions at the gel-tooth interphase. This results in precipitate formation. Rinsing post etching is mandatory to eliminate the etchant and the precipitate. [39] The benefit of rinsing the cavity for duration that is comparable to the etching time as been proven in literature. It aids in adequate dissolution of minerals and prevents the formation of white halos around the margins of the prepared cavity. [6]

In the present study it was observed that even though the practitioners were aware of the need for complete polymerization of the bonding agent, a majority lacked the awareness of the intensity of curing light being used.

To compensate for the polymerization stress, it is has been proven advisable to apply more than one layer of bonding agent. [40, 41] Using air to spread the adhesive prevents its pooling within the cavity. [42] The curing efficiency of the bonding agent is best when the curing tip is placed close to the tooth. The further the tip is placed, more are the chances of incomplete polymerization. [43] However, touching of the curing tip to the tooth being restored might lead to cross contamination. [44] An adequate curing time and intensity of the curing light is essential for complete curing of the bonding agent. It has been observed in previous studies that most of the practitioners cure the bonding agent for a minimum time of 20 seconds while keeping the curing tip close to the tooth being restored but not touching it. [6] Further, an intensity of more than 800 mW/cm2 ensures optimum polymerization. [45]

One possible limitation of the present study is that the data collected is from a single geographical area. Considering the source of information, the participants gather to update their knowledge and skills. Hence we assume the extrapolation of the results of the present study to be generalized to all general dentists and Endodontists across India.

Conclusion

The present survey reflects that even though some practitioners follow the protocols for dent in bonding aptly, the need for knowledge upgradation remains. Newer adhesives and techniques have evolved based on scientific reasoning to improve the bond strength. The Endodontists are more acquainted with these owing to their expertise in the specialty of conservative dentistry. It is only through continuing education that the practitioners can update themselves with the recent advances so as practice evidence based dentistry.

Acknowledgement

The authors of this study would like to acknowledge all the participating general dental practitioners and Endodontists for their valuable time and input.