Immediate Dentin Sealing For Indirect Esthetic Restorations: A Systematic Review

Background: The progress in the field of dental adhesion has shown great implications for restorative dentistry. Immediate dentin sealing is a technique that was introduced to improve the bonding of indirect restorations. The improvement of bonding techniques to both enamel and dentin promotes the practice of conservative dental treatment.Hencethe purpose of the current study was to search for the best available evidence concerning the clinical outcomes of immediate dentin sealing. Methodology: An extensive search was performed using different online databases (Pubmed, Scopus, Web of Science, Google Scholar and Cochrane library). These search engines were searched for relevant articles by developing relevant search strategies. Three independent authors reviewed studies, collected data, and assessed risk of bias. Systematic Review Alghulikah et al.; JPRI, 33(39A): 168-174, 2021; Article no.JPRI.71347 169 Results: After reviewing 221 studies, duplicates were removed and inclusion and exclusion criteria were applied. Finally, three clinical studies were accepted in this review. Conclusions: Previous in vitro studies have shown improved outcomes, although there was no strong evidence in clinical studies to prove superiority of this clinical approach.


INTRODUCTION
Adhesion is an important factor to consider in cases of severe tooth destruction. During the treatment, if significant dentin was exposed, it is suggested to seal it with a dentin bonding agent. The advancement of using dental adhesives to form a tight seal between freshly cut dentin and the restoration is crucial to protect the pulp and reduce sensitivity during the time between tooth preparation and bonding of the final restoration [1]. In addition, bonding to dentin has been the most challenging factor for bonding ceramic restorations, which impacts the clinical durability of it [2].
The clinical success of indirect restorations depends primarily on the quality of their adhesion to the tooth structure. Many developments and methods have been introduced in recent years to offer a better bond strength, such as immediate dentin sealing [3], which has shown a lot of advantages, but the evidence supporting its effectiveness is still limited [4]. Contaminated dentin after removal of the provisional restoration is not a proper substrate for bonding, so it can affect the bonding strength of self-adhesive cement because it does not require pretreatment prior to application. To overcome this problem, immediate dentin sealing [3] was proposed in the early 1990s by using etch-andrinse adhesive resin cement [5].
The immediate dentin sealing technique is a new and advanced method that enables clinicians to seal dentin immediately after preparation using a dentin bonding agent(DBA) after tooth preparation and before taking the final impression.
Application of DBA on newlyprepared and exposed dentin provides anultimate dentin bonding potential, since it provides protection to the pulp from bacteria leakage and dentin contamination with residual temporary cement [6]. The immediate dentin sealing approach will give clinicians a better and enhanced outcome, as it enables the dentin bond to evolve without stress during the provisional stage. In addition, it will allow for pre-polymerization of the dentin bond, providing a better tensile strength [6]. Evidence-based results also showed that IDS will reduce postcementation sensitivity, yield fewer gap formations, and assurelong-term survival of indirect restorations, thus saving both the dentist and patient time during the cementation stage [1,6]. The disadvantage is that most provisional restorative materials are incompatible with IDS, such as bisacodyl materials that failed to seal preparation appropriately, which resulted in IDS contamination and loss retention in the weeks before cementation [7].
Regarding the clinical steps in the IDS application, the first step is to etch the exposed dentin surface with 37% phosphoric acid for 15 seconds.This is followed by rinsing, removing excess moisture by using suction, applying primer and adhesive and light curing for 20 seconds,and then fabrication and cementation of the provisional restoration. One to two weeks later, the clinician starts the next phase by removing the provisional restoration/cement, cleaning and then etching the enamel-sealed surfaces, and then luting the final restoration with a contemporary system [4,5].
The longevity of the indirect ceramic restorations depends on the proper adhesion protocol [8].Several factors play a role in debonding the indirect esthetic restorations on IDS. These include chemical bonding of free radicals, the concentration of the free radicals, micromechanical interlocking and interpretating network matrices, depth of penetration, increased polarity of the surface due to contact with water, the film thickness, interaction with luting cement, preparation design, time of placement of the restoration, type of adhesive system, interaction with impression material and provisional restorations, conditioning method, microleakage, and hypersensitivity [9].
The result of significant evidence from in vitro studies and clinical trials is that immediate dentin sealing for indirect restoration has shown significant differences compared to delayed dentin sealing [2].More long-term studies need to be conducted in this field [2,7]. Hence the purpose of the current study was to search for the best available evidence concerning the clinical outcomes of immediate dentin sealing.

MATERIALS AND METHODS
This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement [10]. Three readers were standardized to evaluate the studies for risk of bias, and then strength of recommendation. The process of evaluation was completed using the revised risk of bias instrument [11] and the Ex-GRADE [12]. The calibration process for the three readers was performed on a pilot clinical trial.

RESULTS
The initial search identified 221 studies attained from five different databases. After removal of duplicate studies and applicationof the inclusion/exclusion criteria, 161 studies were screened, and the final number of studies that matched the PICOT question were 3, as shown in Graph (1).

Assessment of Clinical studies
The included studies were evaluated using the Ex-GRADE instrument, which has two main arms: quality of the evidence and strength of recommendation. The revised risk of bias instrument was used to evaluate the quality of the evidence by assessing design/quality, consistency, directness and precision. The second arm of Ex-GRADE has seven questions to evaluate the strength of recommendation.
The following clinical trials were accepted:  [15].
The assessment of these studies for quality of the evidence and strength of recommendation did not reveal any bias and showed strong quality of evidence.

DISCUSSION
Qualitative analysis was performed for the included clinical trials. Data extraction was performed to combine results from the included studies and are summarized in Table (1) for further assessment.Here interpretation of the results primarily focused on intervention and measuring the outcomes. (Table 2) i.

Performance of ceramic laminate veneers with immediate dentine sealing: 11 year prospective clinical trial [13]
A total of 118 patients were involved in this prospective clinical study. These patients received 444 indirect ceramic laminate veneers had teeth with more than 50% dentin exposure that were sealed with immediate dentin sealing. Two calibrated dentists evaluated these restoration the follow-up visits (baseline, three months, one year and final followevaluation included mirror and probe inspection, light transillumination and the patient's response questionnaire. In the first four years of this study, IDS was Once IDS was used for teeth with 50% of

171
Qualitative analysis was performed for the included clinical trials. Data extraction was performed to combine results from the included studies and are summarized in Table (1) for assessment.Here interpretation of the results primarily focused on intervention and Performance of ceramic laminate veneers with immediate dentine sealing: 11 year prospective clinical were involved in this prospective clinical study. These patients received 444 indirect ceramic laminate veneers had teeth with more than 50% dentin exposure that were sealed with immediate dentin sealing. Two calibrated dentists evaluated these restorations during up visits (baseline, three months, -up). Clinical evaluation included mirror and probe inspection, light transillumination and the patient's response questionnaire. In the first four years of this study, IDS was not used. Once IDS was used for teeth with 50% of dentin exposed, it showed improved clinical outcomes and significantly less failure.

ii. Prospective Randomized Clinical
Trial on the Survival of Lithium Disilicate Posterior Partial Crowns Bonded Using Immediate or Delayed Dentin Sealing: Short-term Results on Tooth Sensitivity and Patient Satisfaction [14] In this prospective randomized clinical trial, 30 patients received indirect ceramic restorations on two molars each (60 in total). The teeth received IDS or DDS, and the aim of the study was to evaluate postoperative sensitivity and the patient's satisfaction. A coolant spray was used for the assessment of sensitivity, and avisual analog scale was used for the assessment of color. Patients were asked to evaluate their satisfaction regarding color and shape of the restorationsand chewing ability. No significant differenceswerereported in postoperative sensitivity or the patient's satisfaction.

Fig. 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)
; Article no.JPRI.71347 dentin exposed, it showed improved clinical outcomes and significantly less failure.

Prospective Randomized Clinical Trial on the Survival of Lithium Posterior Partial Crowns Bonded Using Immediate or Delayed term Results on Tooth Sensitivity and Patient
In this prospective randomized clinical trial, 30 patients received indirect ceramic o molars each (60 in total). The teeth received IDS or DDS, and the aim of the study was to evaluate postoperative sensitivity and the patient's satisfaction. A coolant spray was used for the assessment of sensitivity, and avisual the assessment of color. Patients were asked to evaluate their satisfaction regarding color and shape of the restorationsand chewing ability. No significant differenceswerereported in postoperative sensitivity or the patient's Analyses (PRISMA) iii. Randomized clinical trial on the survival of lithium disilicate posterior partial restorations bonded using immediate or delayed dentin sealing after 3 years of function [15] Thirty patients were recruited for this randomized clinical trial to receive two partial coverage ceramic restorations. These restorations were evaluated at follow-up visits for up to 36 months. FDI criteriawere used for the evaluation of these restorations. The results showed non-significant differences in the success and survival rates and the quality of survival when comparing the use of IDS and DDS.
Because of the limitations of the included studies, a strong clinical recommendation cannot be made, but the qualitative assessment supports the positive clinical outcomes of IDS. These improved clinical results have been associated with using filled DBA [16]. In contrast, a recent in vitro study has shown superior marginal adaptation of ceramic inlays when using IDS [16].Clinicians have reported that there is a disadvantage of this technique due to the interaction between impression materials and the layer of resin. The interaction results in formation of an oxygen inhibition layer. Prophy paste and Marseille soap have been proven to prevent any negative interaction between the impression material and the bonded dentin [8]. Coating IDS with flowable resin composite is recommended to preserve the bonded layer and prohibit interaction with the impression material [16].

CONCLUSION
The inconsistency of the study designs and the outcomes of measurements did not allow performing a meta-analysis and statistical interpretation. One study showed improved clinical outcomes when IDS was applied. Although the evidence reported from in vitro studies showed better clinical outcomes, there was no strong evidence in clinical studies to demonstrate superiority of this clinical approach.

RESEARCH RECOMMENDATIONS
In terms of a systematic review, the current review has the limitation of including only a small number of studies. More clinical trials and observational clinical studiesare needed for the assessment of immediate dentin sealing in clinical practice. There is a need to investigate whether the use of immediate dentin sealing can reduce sensitivity and improve the bonding of indirect esthetic restorations.

CLINICAL RECOMMENDATIONS
Data in the literature support the use of immediate dentin sealing. Although clinical studies in the field are limited, it is suggested to implement immediate dentin sealing when exposed dentin is encountered after preparing the tooth for indirect esthetic restoration.

CONSENT
It is not applicable.

ETHICAL APPROVAL
It is not applicable.