Role of Liners in Restorative Dentistry.

Tooth has two main organs- pulp and dentin which remain closely integrated. They depend on each other both functionally and anatomically, throughout the life of tooth. Protection of these tissues is important from trauma during cavity preparation or tooth preparation, from caries, from mechanical forces, from chemicals produced by bacteria and from galvanic shock and thermal injury. The main aim of the operative dentistry is to protect this tissue and preserve tooth vitality.(1) The purpose of a restoration is to replace missing tooth structure and provide the pulp adequate strength and protection from external insults. Sometimes, the restorations and \ or the restorative material is incapable of providing this property; hence, an auxiliary material such as liner and base or sub-base is required, which can fulfil this function. The material used to protect this tissue is called pulp protecting material or pulp capping material. For many decades clinicians have been using liners and bases under restorations. The type of auxiliary material to be used depends upon the minimum dentinal thickness which is left between the surface of the cavity and pulp. This is known as remaining dentin thickness (RDT). Dentin has excellent buffering capacity to neutralize the effects of cariogenic acids, and insulates the pulp from temperature increases during cavity percolation. The single most important criterion for protecting pulp is remaining dentinal thickness which is dependent upon the depth of cavity preparation.(2)

Removal Techniques for Intracanal Medicament- A Review

This article reviews irrigation techniques for removal of intracanal medicament in endodontic practice. Microorganisms are the primary etiological factors for pulpal and periradicular diseases. So primary purpose is to completely eradicate microorganism from the root canal. It is done through chemo-mechanical preparation of the canal. Complete disinfection of the pulp space cannot be achieved with most sophisticated instrumentation techniques. Therefore use of inter appointment intracanal medicaments is mandatory. Removal of the medicament is mandatory, as its remnants may mechanically block the apical area of the root canal system. Also affects viscosity, working time, tubule penetration and adhesion of root canal sealers. Remnants of Ca(OH)2 in the canal react with unreacted eugenol present in ZOE based sealer to form calcium eugenolate. Today’s irrigation armamentarium presents a diverse variety of tools and techniques , that can assist the practitioner in reducing bacteria, debris, intracanal medicament within the canal system. Conventional syringe irrigation is a routinely practiced method for removal of medicament. It consists of delivering the irrigant in the canal passively or by agitation. Rotary brush does not actually render irrigating solution for removal of medicament. This acts like auxiliaries during removal of medicament from canal or for increased movement of irrigating solution. Ultrasonic irrigation is done with or without simultaneous ultrasonic instrumentation. EndoVac is negative pressure irrigation, which can be used as an alternative method that helps in safe removal of medicament in apical thirds. RinsEndo is also based on pressure alteration technology like EndoVac. Sonically driven system safely acti­vates various intracanal reagents and vigorously produces the hydrodynamic phenomenon as it includes EndoActivator and Vibringe. Laser activated irrigation is more effective for cleaning of root canal. Er:YAG is most commonly used laser in endodontics. Therefore, the aim of this article is to highlight the irrigation techniques used for removal of the intracanal medicament in endodontic practice.

Comparative Evaluation of Microleakage in Cavities Restored with Nanohybrid and Microfilled Composites Using Oblique Incremental Technique- An in Vitro- Study.

Many advancements have been done in the field of dentistry for resin composites applications. However, polymerization shrinkage stays a problem. Marginal gap and microleakage in between tooth cavity wall and restorative material is caused by forces of contraction, masticatory forces, polymerization shrinkage, poor adhesion, temperature variables, and inadequate moisture control. An impaired marginal seal resulting due to microleakage provides entry of oral fluids, ions, bacteria which causes recurrent caries, discoloration and hastening of marginal breakdown of restoration, hypersensitivity, pathology of pulp that would decrease the life of restoration. The purpose of restoring cavities by using nanohybrid and micro filled composite was to assess if it would eliminate or decrease microleakage in this in vitro study. We wanted to assess the effectiveness of nanohybrid and micro filled composites with regard to microleakage in class I cavity restoration.METHODSStandardized class I cavities were prepared over thirty teeth. The teeth samples were randomly distributed in to two groups based on composite used for restoration. Group A (n=15): Restored with nanohybrid composite followed by light curing. Group B (n =15): Restored with micro filled composite followed by light curing. The samples were stored in a 1% chloramine beta-hemihydrate solution for a day and then thermocycling procedure was performed. The samples were soaked in 2 % methylene blue for a day and sectioning of samples was done through the center of restoration using a diamond disk and analysed for methylene blue dye penetration with a stereomicroscope in 12X magnification. Scoring was done based on the criteria of a 0-4 scale.RESULTSChi square test was used for performing statistical analysis. No significant difference in the microleakage score between nanohybrid and micro filled composite was seen (p = 0.338).CONCLUSIONSIn this study both groups showed microleakage. However, nanohybrid composite resin showed better marginal adaptation of restoration as compared to micro filled composite resin.