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Shear Bond Strength of Nanocomposite Resin

ABSTRACT

OBJECTIVE: To compare the shear bond power of nanocomposite resin to superficial dentin and deep dentin using two different dentin bonding systems.

METHOD- All tooth were sectioned at various levels (Superficial Dentin: Dentin within 0. 5-1 mm of DEJ; Deep Dentin: Dentin within 0. 5 mm of the best pulp horn) utilizing a carborundum Disc and inlayed in acrylic stop of specific size. Determined specimens (60 premolar pearly whites) were grouped arbitrarily into three groupings, the communities were differentiated into superficial dentin, deep dentin and control group which were further split into sub group a and subgroup b formulated with 10 tooth each, depending on bonding brokers used.

In subgroup A, Tetric-n-bond, and in subgroup B Sole bond common was used. Inside the control group no bonding agent was used. The specimens were thermocycled for 500 cycles between 5 level c and 55 degree c water bathroom for 40 a few moments. Finally the specimens were subjected to shear bond strength study under INSTRON machine (General TESTING MACHINE). The maximum shear bond strengths were noted at the time of fracture (de-bonding) of the restorative materials. Results were analysed using ANOVA test, Bonferroni test and paired t test.

RESULTS- Bond power ideals of fifth technology bonding system (Tetric n bond) demonstrated higher mean shear connection strength compared to seventh generation bonding system (sole bond universal). There is a significant fall season in bond durability values as you reaches deeper levels of dentin from superficial to profound dentin.

CONCLUSION- There is a big change between the bond strength of fifth era bonding system (Tetric n relationship) and seventh generation bonding system (solo bond universal). Decrease in the bond durability values sometimes appears for deeper level of dentin when compared with superficial dentin.

INTRODUCTION

The success of any oral restoration is based on the high adhesive property of the materials. Various materials can be found which utilizes this adhesive property such as, cup ionomer cement restoration, amalgamated restorations and pit and fissure sealants. Among these amalgamated resins have been developed since few years to be able to provide the best esthetics to the anterior restorations as well for posterior restorations.

Dental adhesive systems are agencies used to promote adhesion between amalgamated resin and oral structure, and they should present similar performance on teeth enamel and dentine. Bonding to enamel and dentin has been known to be medically reliable with the introduction of acid etching technique. It differs from enamel, as it offers more organic articles, presence of liquid inside the dentinal tubules, smear coating and inherent wetness on the surface[1]. Dentin has been characterized as a biologic composite of an collagen matrix filled up with sub-micron to nanometer size calcium lacking carbonate abundant apatite crystallites dispersed between hyper mineralized collagen poor hollow cylinders. It is very well grasped that the thickness of dentinal tubules varies with dentinal depth and the as this content of dentin is least expensive in superficial dentin and highest in deep dentin. In superficial dentin which has fewer tubules and the permeation of resin into intertubular dentin will be accountable for the majority of the bond strength. In deep dentin, dentinal tubules are definitely more in number and therefore, intratubular permeability of resins will be accountable for higher bond durability.

Two major simplified bonding approaches have been developed particularly.

Total etch approach -will involve the all together removal of the smear covering from both teeth enamel and dentin surface followed by the application of one container agent that combines the primer and adhesive in a single solution.

Self-etching strategy - their bonding system is based upon the simultaneous etching, priming and adhesive of the dentin surface in a single container[2].

Bonding to enamel was achieved earlier and easier (Buonocore, 1955) because enamel is mostly made up of hydroxyapatite crystals. Though it is possible to acquire predictable and reliable adhesion to enamel, adhesion to dentin, which is the greatest part of the tooth, has proved to be more challenging because of its heterogeneous nature. The mechanism of dentin adhesion, improved by hybrid covering formation between your resin and dentin, was proposed by Nakabayashi (1982). The sufficient hybrid layer formation is believed to be necessary to create a solid and durable relationship between resin and dentin.

Adhesive restorations have been extensively accepted for both anterior and posterior use in restorative dentistry. Patient's requirements for esthetic restorations have caused a recent increase in the use of tooth coloured restorative materials. To achieve clinical success with such restorations, good adhesion between restorative materials and teeth substrates is of essential importance in order to ensure good marginal closing, reinforcement of the teeth framework, and longer life of the restoration. During the last two decades, a variety of adhesive systems have been continually developed in order to create good adhesion to dental care substrates. These great advancements in the adhesive dentistry have altered the concepts of cavity prep based on the principals proposed by GV Black (1955) into more conventional and minimally intrusive ones.

The current self-etching adhesives provide monomer formulation for simultaneous fitness and priming of both teeth enamel and dentin. Currently less research can be found to indicate the potency of new generation self-etching primers against superficial and deep dentin. Shear relationship strength measurements are generally used to evaluate effectiveness of dentin bonding systems. The purpose of the analysis was to judge the Shear Relationship Power of the newer bonding systems on superficial dentine and profound dentin.

MATERIALS AND METHOD:

The present in- vitro research was conducted in the division of conservative dentistry and endodontic, M. R. Ambedkar Dentistry College and Medical center, Bangalore. Sixty intact real human maxillary pre molar tooth extracted for orthodontic reasons were gathered from Mouth and Maxillo-Facial Division at M. R. Ambedkar Dental College & Medical center. One's teeth were stored, disinfected and completed according to the suggestions and guidelines laid down by OSHA and CDC. Pearly whites selected were arbitrarily split into three sets of twenty pearly whites each. Group A, Group B and Control group.

Group A and B were further subdivided into Subgroup A & Subgroup B, of ten each.

All tooth were sectioned at various levels using a Carborundum Disc under copious drinking water and embedded in acrylic block of specific size.

Group I: Superficial Dentin - 20 specimens

Sub group A - Superficial Dentin (Tetric N Connection) 10 specimens

Sub group B - Superficial Dentin (Solo Bond General) 10 specimens

Group II: Deep Dentin - 20 specimens

Sub group A - Deep Dentin (Tetric N Bond) 10 specimens

Sub group B - Profound Dentin (Solo Bond Common) 10 specimens

Group III: Control Group - 20 specimens

Sub group A - Superficial Dentin 10 specimens

Sub group B - Profound Dentin 10 specimens

The occlusal floors of teeth were ground over a water-cooled trimming steering wheel to prepare even dentin areas.

Group 1 (Superficial Dentin)

Subgroup A

All the specimens were etched on the prepared dentinal flat surface with (N Etch), and cleaned. The top was blotted with gauze to produce a visible moist dentin surface. The total-etching adhesive (Tetric N Relationship) was applied on the well prepared dentinal flat work surface left undisturbed for 20 a few moments and the surplus solvent was removed with a delicate blast of air. Light curing was done for 40 mere seconds with a obvious light curing product. After healing the bonding agent, nanocomposite resin (Tetric N Ceram) was put on the ready dentinal surface using Teflon mold and cured relating to manufacturer's instructions. The exact same procedure was carried out on the 10 specimens in this group.

Subgroup B

The self-etching adhesive (sole bond general) was applied on the prepared dentinal flat work surface still left undisturbed for 20 seconds and the excess solvent was removed with a delicate stream of air. Light curing was done for 40 a few moments with a obvious light curing product. After healing the bonding agent, nanocomposite resin was put on the prepared dentinal surface using Teflon mildew and cured relating to manufacturer's instructions. The identical procedure was carried out on the 10 specimens in this group.

Group II (Deep Dentin)

Subgroup A

The same procedure as completed in the group I, subgroup A is carried out on all specimens in this group.

Sub group B

The same method as completed in the group I, subgroup B is carried out on all specimens in this group.

Group III (Control Group)

No bonding agent was applied. Nanocomposite resin was located and cured regarding to manufacturer's instructions.

Specimens were then stored under room temp for 48 time. The specimens were then thermocycled for 500 cycles between 50 c and 550 c water shower. A dwell time of 40 seconds were used for each bath.

All the sixty specimens were used in the Instron evaluation machine separately and subjected to shear bond power test.

STATISTICAL Examination: The statistical data derived from the four subgroups were analysed using ANOVA test, Bonferroni test and matched t test .

RESULTS: For superficial dentin - Higher mean shear bond strength was recorded in Fifth generation bonding system followed by seventh generation bonding system and control respectively.

The difference in mean shear bond strength between the groups was not statistically significant (P>0. 05).

Deep dentin - Higher mean shear bond strength was noted in fifth generation bonding agent accompanied by seventh technology bonding agent and Control respectively. The difference in mean shear relationship strength between the teams was found to be statistically significant (P<0. 001).

The difference in bond power using fifth era bonding agent in superficial dentin and deep dentin was not statically significant. (P>0. 05).

The difference in bond durability using seventh era bonding agent in superficial and deep dentin was statically significant. (P<0. 001).

DISCUSSION

Adhesion to acidity etched enamel was suggested by Buonocore in 1955. Bond strength to enamel or dentin is an important indicator of any adhesive system's effectiveness. The bonding covering should never only support composite shrinkage stress, but also occlusal loads in stress bearing area to avoid difference formation resulting in micro leakage, secondary caries and post - operative awareness[3]. Bond power testing and dimension of marginal - sealing effectiveness are the two most commonly employed methodologies to find out bonding performance in the lab in predicting medical performance.

Dentin is a strong tissue. It symbolizes an issue to resin established adhesives while the bond power of enamel has been examined thoroughly, bonding to dentin with the era of bonding systems has remain unsolved. The dentin substrate has been characterized as a biologic composite of collagen matrix filled with apatite crystals dispersed between parallel micrometer measured hypermineralized collagenpoor dentinal tubules made up of peritubular dentin. The structure of dentin substrate is made up of 50 % nutrients, 20% of normal water and 30% of organic and natural matrix. But as the dentin deepens this composition may change accordingly. This is due to the fact that the superficial dentin has few tubules and is made up mainly of intertubular dentin. Deep dentin is made up mainly of much larger funnel designed dentinal tubules with significantly less intertubular dentin[4].

The intertubular dentin takes on an important role during hybrid level formation in superficial dentin and the contribution to resin retention is proportional to the intertubular dentin designed for bonding[5].

Adhesive dentistry is dependant on the introduction of materials which create an effective connection with the teeth tissues. Successful adhesive bonding depends upon the chemistry of adhesive, on appropriate medical handling of the materials as well as on the knowledge of the morphological changes caused on the oral structure by different bonding steps[6].

The rationale behind the bond strength testing is the fact higher the actual bonding capacity of an adhesive, the better it'll withstand such tensions and longer the restorations will survive in vivo. Connection strength screening is relatively easy and fast and remains most popular technique for calculating the bonding efficiency of adhesive systems[7].

The results of today's study disclosed that superficial dentin offered bond strength principles that were statistically higher and different from beliefs obtained in dentin at profound level.

Tagami J et al (1990) attributed this either to differences in chemical structure or regional dissimilarities in wetness (dentin permeability). Thus there are several factors which could donate to high coefficient of variance that is often reported in dentin shear connection power studies. Several preceding reports signify that the connection strength of resin is highest on superficial dentin and minimum in deep dentin[8].

Suzuki T et al (1988) analyzed the efficiency of dentin bonding systems predicated on the website of dentin with regards to the observation of Causton et al that relationship strengths to deep dentin were considerably less than those to superficial dentin. Today's study has established the observation of Causton et al that the effectiveness of dentin adhesives is based upon the dentin surface from superficial to profound dentin in the tooth tested[8].

Different from etch and rinse adhesives, self-etch adhesives do not require a different etching step as they contain acidic monomers that concurrently condition and perfect the oral substrate. Consequently, this approach has been claimed to be customer friendlier and less approach sensitive, thereby resulting in a reliable specialized medical performance. Self-etch adhesives are user friendly because of shorter request time and less steps and less approach delicate because of no wet bonding but simple drying. Comparatively with the self-etch adhesives there is leaner occurrence of post-operative level of sensitivity experienced by the patient. This will to a great amount be related to the less aggressive and therefore more superficial relationship with the dentin leaving tubules mainly obstructed with smear level[9].

This study is within consensus with Suzuki et al, with regard to, higher bond strength in any way degrees of dentin with TETRIC N Connection which belongs to the-etch and rinse way.

Pegadu Rafeal et al (2010)[4]compared the result of different bonding strategies on adhesion to deep and superficial dentin and concluded that bond durability obtained in superficial dentin was significantly higher than that in profound dentin for everyone adhesives tested. They further concluded that the bond advantages of dentin bonding agents at any depth is dependent on the area occupied by resin tags, the region of intertubular dentin that is infiltrated by the resin and the area of surface adhesion.

In the present study, evaluation (combined t test) on the list of tetric n bond group, higher mean connection strength was noted at the superficial dentin level than profound dentin. And evaluation (combined t test) among the list of single bond common group higher connection strength was documented at the superficial dentin level than profound dentin.

Van Meerbeek et al (2011) [9] suggested that for even more search engine optimization of the self-etch procedure, synthesis of functional monomers tailored to exhibit good chemical bonding potential carrying out a mild self-etch approach. The approach seems to assure the most durable bonding performance at dentin so long as it deals sufficiently with the dirt smeared across the surface by the bur. Micromechanical interlocking is still the best technique to bond to enamel. Selective phosphoric acid etching of teeth enamel cavity margins is therefore today strongly suggested followed by applying a self-etch method to both the earlier etched enamel and un-etched dentin. Such moderate self-etch adhesives should contain functional monomers with a high substance affinity to hydroxyapatite.

CONCLUSION:

At superficial dentin level higher suggest shear bond power was registered in Fifth generation bonding system accompanied by Seventh era bonding system and control group respectively. The difference in mean shear connection strength between your groups had not been statistically significant (P>0. 05).

At deep dentin level, higher mean shear connection strength was noted in Fifth technology bonding system accompanied by Seventh generation bonding system and control group respectively. The difference in mean shear relationship strength between your groupings was found to be statistically significant (P<0. 001).

At profound dentin level, statistically significant results were obtained with the Fifth era (Tetric N Bond) bonding system which experienced higher mean shear bond strength values set alongside the Seventh technology self-etch bonding system (Single Bond General).

There was a statistically factor in shear connection strength beliefs with Fifth generation bonding system and control group ( without bonding system) at profound dentin.

There was a substantial fall in connection strength values as you extends to deeper levels from Superficial dentin to Deep dentin.

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