Post-Operative Sensitivity in Teeth Restored With Posterior Dental Composites Using Self-Etch and Total-Etch Adhesives

Muhammad Amin¹                             BDS, FCPS

Farah Naz^{2                                                          BDS, FCPS}

Abubaker Sheikh^{3                             BDS, FCPS}

Adeel Ahmed^{4                                                BDS, MFDS RCS (Ed), FCPS}

INTRODUCTION

The demand for more esthetic posterior dental restorations has dramatically increased the use of directly placed composite restorations¹.

One of the most frustrating situations in the dental office is to craft an aesthetic restoration and have the patient call the office the following day, to complain that the tooth is sensitive. To the patient, it does not matter how beautiful the restoration looks if he or she experiences sensitivity or discomfort².

Postoperative sensitivity (POS) in posterior teeth restored with resin composite has been a problem experienced by clinicians for almost twenty years³. The occurrence of postoperative sensitivity is varies from clinician to clinician and factors other than operator’s experience and technique may be responsible⁴.

Introduction of new adhesive systems have reduced the number of steps in application of composite restoration. Self-etch adhesives, appeared to be advantageous to clinicians with lesser steps (no etch and rinse), less potential of over-drying, low technique sensitivity and so less reported post- operative sensitivity^5,6. Sale of self-etch adhesive has also grown considerably in past 10-12 years due to the view of clinicians that self-etch causes less post-operative sensitivity than total etch adhesive⁷.

When  total-etch dentine adhesive was used in a study while restoring posterior teeth with a resin composite, up to 56 % of the restorations resulted in sensitivity⁸. Few studies have also found total etch restorations to show lesser post-operative sensitivity⁹. A meta-analysis of clinical trials done on TE and SE comparisons showed that there is no significant difference in post-operative sensitivity¹⁰.

There are many studies on these two adhesives but there is still no confirmation regarding the assured lesser post-operative sensitivity in any one material.  We therefore planned this study with a directional hypothesis that total etch adhesive has more postoperative sensitivity as compared to self-etch adhesive.

To test this hypothesis, the objective of this study was therefore, to compare the level of post-operative sensitivity (POS) in teeth restored with posterior dental composite restorations using self-etch (SE) and total-etch (TE) adhesive systems.

METHODOLOGY

Eighty patients visiting the out-patient department of Altamash Dental Hospital were included. Patients with premolars (maxillary or mandibular) presenting with simple class I cavities with vital pulp, radiographic evidence of caries in outer to middle third of dentin and sound occlusal and proximal contacts were included in the study. Patients with any of the following complaint were excluded: teeth with preoperative sensitivity, generalized sensitivity, non-vitality, abnormal occlusion or history of para-functional habits, recent history of desensitizing treatment or any periodontal disease were excluded. Objectives and protocols of the study were explained to the subjects and consent was taken. Patients were then divided into two groups. Non probability purposive sampling was done for group allocation of patients. All patients with odd OPD numbers were placed in group I which was of self-etching bonding system; while all patients with even OPD numbers were placed in group II which was of total-etch bonding system. Local anesthesia was administered. Teeth were isolated by using rubber dam. All cavity preparations were of conventional design. In Group I, the self-etching adhesive (L-POPs 3M, ESPE) was applied for twenty seconds. The tooth surface was then light cured for 10 seconds. In Group II, phosphoric acid-etchant (37%) (Scotchbond 3M, ESPE) was applied for thirty seconds which was then washed with water and dried with air from triple syringe. In the end, bonding agent (Prime and Bond NT, Dentsply) was applied and light cured for ten seconds. In both groups, after application of respective adhesive, composite resin (Filtek Supreme, 3M) restorations were placed in increments by using layering technique to minimize polymerization shrinkage. The composite was cured for 20 second using Quartz tungsten curing light (HILUX 200, Turkey).Finishing of the restorations was carried out using flame shaped diamond burs and then polished with rubber cups by using composite polishing paste (Prisma gloss composite polishing paste, Dentsply).

Post-Operative Sesitivity:

The presence of post-operative sensitivity was noted by placing an ice stick upon the junction of restoration and natural tooth structure on the occlusal surface for five seconds. The degree of severity in sensitivity was marked by using Visual Analogue Scale (VAS), with readings from 0-10. Zero denoting absence of sensitivity, 1-3 was taken as Mild, 4-7 was taken as moderate and 8-10 was taken as severe sensitivity. The readings were marked on 1st, 4th and 7th post- operative day. All the readings were recorded in a self-structured proforma. All the procedures and evaluations were performed by one operator (principal investigator) according to manufacturer’s instructions to minimize the technical / procedural variations. The data was analyzed in SPSS version 12.0. Frequency and percentage were computed for categorical variables like gender and depth, while mean and standard deviation were computed for quantitative variables like age and VAS score. Mann-Whitney test was applied to compare the difference in sensitivity between both groups. Wilcoxon sign rank test was also applied to compare VAS with respect to time for both groups. P < 0.05 was considered as the level of significance.

RESULTS

In a total of 80 patients, the average age of the patients was 26.59 ± 13.55 years. Age range was 13-40yrs.

Histogram of age distribution is presented in Figure I. There were 29 males (36%) and 51 females (64%). The sensitivity in terms of VAS scores at the time of each follow-up visits are displayed in table I. In both groups, sensitivity was found at Day 1, these scores reduced till day 7 in both groups.

Mann-Whitney test was used to compare the sensitivity

Mean ± SD = 26.59 ± 13.55 Years
Age range (13-40 years)

(VAS scores) in the two treatment groups at postoperative day-1 (p=0.027) and day-4 (p=0.006).  Postoperatively, at day-7, sensitivity (VAS score) between groups were not statistically significant (p=0.67). (Table I) Generally, in all follow-up visits, mean values of VAS were higher in treatment group I (Self etch group) as evident in Table I.

There was statistically significant difference in the sensitivity level within each group when the values were compared with each postoperative visits (Day1, Day 4, Day 7) in both groups. A progressive improvement was observed in sensitivity within a week in both groups. (Table II)

DISCUSSION

Our study results showed statistically significant difference in VAS scores within each group with respect to post-operative days. There was more initial sensitivity in self etch group but later on, no significant difference in sensitivity was found among both groups by the end of one week. Thus the hypotheses that total etch adhesive has more postoperative sensitivity as compared to selfetch adhesive was rejected till day 4, as by the end of the week there was no statistically significant difference among both groups. (Table I)

Post-operative sensitivity after application of a posterior dental composite resin restoration is reported as a common problem by dentists. It is generally found that postoperative sensitivity decreases during the first few weeks after restoration placement, but it sometimes persists for a longer period. POS can be caused by several factors, including etching, bacterial penetration of pulp, occlusion discrepancies, technique of restoration placement, depth of cavity, over drying of dentin, deformation of the cusps by shrinkage stress during polymerization of the posterior resin restorations, deformation of the cusps by the shrinkage stress and deformation of composite by occlusal forces¹¹. Literature reveals that in newer adhesive agents, postoperative sensitivity is still found in 30 % of the studied population ^9,12-16.

Our study was an experimental one which involved eighty patients in an academic environment to solve the problem of post-operative sensitivity with posterior dental composites. In comparison to our study Herrero¹ evaluated postoperative sensitivity in 104 class I composite resin restorations, placed with a self-etching and total-etch adhesive system using a visual analogue scale. Most of the studies have used the Visual Analog Scale measure the sensitivity score from 0 to 10 which is in accordance with our study.

In our study we used an ice stick to assess postoperative sensitivity after the placement of posterior dental composites, clinically. Many other studies have used an ice stick but few have also used other methods as compressed air, cool water from a disposable syringe and ethyl chloride spray^3,17.

In our study there was significant difference in the sensitivity level (VAS Score) during a week. This was later reduced to zero by end of the week. Yousaf A conducted a similar study and concluded that SE adhesive may be helpful in reducing post-operative sensitivity during first 24 hours after placing the restorative material as compared to TE adhesives¹⁸. These results were different from our study where SE group showed more sensitivity initially as compared to TE group in first 4 days. The reason for this could be because of use of a different brand of test material or bonding failure since SE adhesives have weak etchant and thus weaker bond strengths⁷. Some clinicians have suggested the use of SE in cavities with more dentin (deeper cavities) and TE in cavities with more enamel (shallow cavities)¹⁹. The cavities included in our study were all shallow extending not more than upper third of dentin. Other possibility could be due to some unintentional breach in application protocol which is less likely. Difference in brands is also important because there could be difference in bonding ability as well as concentration of etchant in various products. A study by Perdigao et al¹² evaluated the clinical performance of three different self-etch adhesives. The clinical efficacy of these self-etch adhesives was compared to the total etchadhesives as control. This study showed that significant post-operative sensitivity was present with one of the selfetch adhesive as compared to the control group. In another study by Baratieri et al ²⁰ , clinical performance of the self-etching adhesive system and the total-etch adhesive system in classes I and II for a period of 4 years was compared, this study showed that post-operative sensitivity was found with self-etchant adhesive. The same study also showed that the incidence of post-operative sensitivity reduced with the passage of time for the self-etch adhesive system.

The sensitivity in both groups in our study also reduced completely in one weeks time, the reason for this could be the accumulation of precipitated protein in the dentinal tubules in few days after application of adhesive, limiting the fluid flow and reducing or eliminating the sensitivity.

Some of the studies regarding the issue of postoperative sensitivity with posterior dental composite showed no statistically significant difference either by using self-etching adhesives or by total-etch adhesives²¹. A meta-analysis was conducted by Krithikadatta on comparison of different clinical outcome of composite restoration placed with SE and TE found that there was no significant difference in post-operative sensitivity¹⁰. VV Gordon²²,  evaluated the post-operative sensitivity of posterior restorations restored with a resin-based restorative material and a self-etching primer showed that no statistically significant difference was found on either short term nor long term. Herrero et al¹ showed that there was no statistically significant difference either by using both self-etching or total-etch adhesives. Jorge Perdigao et al¹² also showed that no statistically significant differences in post-operative sensitivity was found between the self-etch and total etch adhesives at any recall time. This variation in results of all these studies leads us to understand that the clinical technique and operator factors of applying the composite restoration may be more important than the choice of adhesive system⁷. The results of many clinical trials do not support the anecdotal evidence of self-etch being better in terms of sensitivity; they found it similar in both the adhesive groups^7,23. Generally, mild self-etch systems are expected to have little or no , and total etch  systems are found to have more frequent and intense post-operative sensitivity⁷. This was not the case in our study, maybe because all the restorations were placed under meticulous isolation with rubber dam and were performed by single operator.

CONCLUSION

TE adhesives significantly showed less POS compared to SE group during the first four days of restoration placement after which the difference between the groups faded. The study results showed that post-operative sensitivity was found with both total-etch adhesive and self-etch adhesive till one week post-operatively. A reduction in sensitivity was found in both groups from day one to day seven.

LIMITATION / WEAKNESS OF THE STUDY

One group of the permanent teeth from patient’s mouth, a pre-molar was selected, which did not   represent the entire dentition. POS was measured in response to cold stimulus only. Stimuli like hot, biting forces, and air could have been used to simulate the natural oral environment more closely. Class I cavity design was selected which has a maximum ‘C’ factor (configuration factor) . This can inflate the VAS score.

CLINICAL SIGNIFICANCE/ STRENGTH OF THE STUDY

The problem discussed in this study is of vital importance in clinical practice of Operative dentistry. Post-Operative sensitivity is a very commonly associated with composite restorations. There are many subjective beliefs among clinicians that this sensitivity is reduced when self-etch adhesives are used with composites than total etch adhesives. Clinical trials however tend not to support this evidence. This study will also help the clinicians in a better understanding of the fact that technique of placement of restoration is more important than the choice of adhesive system used.

RECOMMENDATIONS

It is recommended that studies should be conducted while involving different groups of   patient’s dentitions like molar, canines and incisors to have a generalized assessment of post-operative sensitivity. Studies should be conducted to measure post-operative sensitivity in response to other stimuli like hot, biting forces and air to have more accurate assessment of post-operative sensitivity. Studies should be conducted to involve various cavity designs or classifications like class II, class V to establish more accurate evidence about post-operative sensitivity.

ACKNOWLEDGEMENT

We would like to acknowledge the continuous guidance and support of Dr. Ismail Sheikh, Dr. Mumtaz Khan and Dr. Azmat Mumtaz, Consultants of Operative Dentistry, during this research work.

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1. Assistant Professor & Consultant, Department of Operative Dentistry, Dental section, Dow International Medical College; DUHS, Karachi.
2. Associate Professor & Consultant, Department of Operative Dentistry, Dental section, Dow International Medical College; DUHS, Karachi. Clinical Faculty member (Part time), Department of Surgery, Section of Dentistry, The Aga Khan University and Hospital, Karachi.
3. Assistant Professor & Consultant, Department of Operative Dentistry, Fatima Jinnah Dental College, Karachi.
4. Assistant Professor & Consultant, Department of Operative Dentistry, Dental Section, Dow International Medical College; DUHS, Karachi. Corresponding author: “Dr Muhammad Amin ” < dr_mohdamin@yahoo.com >