Journal of Conservative Dentistry
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   2008| October-December  | Volume 11 | Issue 4  
    Online since March 20, 2009

 
 
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INVITED REVIEW
The chemical composition of mineral trioxide aggregate
Josette Camilleri
October-December 2008, 11(4):141-143
DOI:10.4103/0972-0707.48834  PMID:20351970
Mineral trioxide aggregate (MTA) is composed of Portland cement, with 4:1 addition of bismuth oxide added so that the material can be detected on a radiograph. The cement is made up of calcium, silicon and aluminium. The main constituent phases are tricalcium and dicalcium silicate and tricalcium aluminate. There are two commercial forms of MTA, namely the grey and the white. The difference between the grey and the white materials is the presence of iron in the grey material, which makes up the phase tetracalcium alumino-ferrite. This phase is absent in white MTA. Hydration of MTA occurs in two stages. The initial reaction between tricalcium aluminate and water in the presence of calcium sulphate results in the production of ettringite. Tricalcium and dicalcium silicate react with water to produce calcium silicate hydrate and calcium hydroxide, which is leached out of the cement with time.
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ORIGINAL ARTICLES
Clinical evaluation of carbon fiber reinforced carbon endodontic post, glass fiber reinforced post with cast post and core: A one year comparative clinical study
GA Preethi, M Kala
October-December 2008, 11(4):162-167
DOI:10.4103/0972-0707.48841  PMID:20351975
Aim: Restoring endodontically treated teeth is one of the major treatments provided by the dental practitioner. Selection and proper use of restorative materials continues to be a source of frustration for many clinicians. There is controversy surrounding the most suitable choice of restorative material and the placement method that will result in the highest probability of successful treatment. This clinical study compares two different varieties of fiber posts and one cast post and core in terms of mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology requiring crown removal over the period of 12months as evaluated by clinical and radiographical examination. Materials and Methods: 30 root canal treated, single rooted maxillary anterior teeth of 25 patients in the age range of 18-60 years where a post retained crown was indicated were selected for the study between January 2007 and August 2007; and prepared in a standard clinical manner. It was divided into 3 groups of 10 teeth in each group. After post space preparation, the Carbon fiber and Glass fiber reinforced posts were cemented with Scotch bond multipurpose plus bonding agent and RelyX adhesive resin cement in the first and second groups respectively. The Cast post and cores were cemented with Zinc Phosphate cement in the third group. Following post- cementation, the preparation was further refined and a rubber base impression was taken for metal-ceramic crowns which was cemented with Zinc Phosphate cement. A baseline periapical radiograph was taken once each crown was cemented. All patients were evaluated after one week (baseline), 3 months, 6 months and one year for following characteristics mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology. Results: Results after 12 months showed that none of the restorations among groups of cast post and core, carbon fiber reinforced post and glass fiber reinforced post with composite core restorations failed in terms of recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology. One case of cast post and core and one case of carbon fiber reinforced post with composite core restorations showed slight mobility of crown margin under finger pressure at 12 th month recall but all the cases of glass fiber post with composite core restorations did not show any signs of mobility of crown margin under finger pressure at all the recall periods on clinical and radiographical examination. Conclusion: From this 12 months clinical evaluation of all the cases in the 3 groups comprising of cast post and core; carbon fiber reinforced post with composite core and glass fiber reinforced post with composite core restored with porcelain fused to metal crowns, it is concluded that glass fiber reinforced post with composite core when used in single rooted upper anterior teeth are associated with a higher success rate in restoration of endodontically treated teeth.
  4,170 612 1
Effect of thermocycling on the flexural strength of porcelain laminate veneers
Deepa Subramanian, G Sivagami, D Sendhilnathan, CS Rajmohan
October-December 2008, 11(4):144-149
DOI:10.4103/0972-0707.48835  PMID:20351971
Aim: The aim of this study was to examine the impact of thermocycling on the flexural strength and development of surface flaws on the glazed surface of porcelain laminate veneer restorations with and without resin luting cement. Materials and Methods: 80 Vitadur alpha dentin porcelain discs (10 mm diameter, 0.9 mm thickness) were glazed on one side and divided into two groups: A (porcelain laminate veneer only without resin luting cement) and B (porcelain laminate veneer luted with resin cement), each containing 40 discs. The discs in groups A and B were then thermocycled at different temperatures and were subjected to SEM analysis to evaluate the effect of thermocycling on crack propagation. Mean flexural strength was determined by using the ball-on-ring test. Student's t -test was used to find out the difference between strength values of the thermocycled porcelain discs and discs luted with resin cement. Results: SEM analysis revealed crack propagation in the subgroups subjected to extremes of temperature, i.e., 4 1C, 37 1C and 4 1C, 65 1C in the porcelain laminate veneers luted with resin cement. Flexural strength analysis revealed superior flexural strength for porcelain laminate veneers: 88.58 6.94 Mpa when compared to porcelain laminate veneers luted with resin cement: 8.42 2.60 MPa. Results were tabulated and statistically analyzed using Student's t -test. Conclusion: Laminate veneer specimens exhibited greater flexural strength than those which were luted with resin cements. Laminate veneer specimens luted with resin cement and subjected to extremes of temperature, 4 1C and 37 1C and 4 1C and 65 1C, showed a marked decrease in flexural strength. After thermocycling at extremes of temperature, laminate veneer specimens luted with resin cement showed crack propagation. Fit of laminate veneers cannot / should not be compensated by the thickness of luting agent.
  2,964 374 1
CASE REPORT
Endodontic management of a maxillary second premolar with an S-shaped root canal
Joseph Reuben, Natanasabapathy Velmurugan, Santhanam Vasanthi, Priya , Vijaylakshmi
October-December 2008, 11(4):168-170
DOI:10.4103/0972-0707.48842  PMID:20351976
Complex and unusual root canal morphology is an often occurring phenomenon. Understanding the unusual root canal morphology contributes to success in endodontic treatment. One such variant root canal morphology is the 'S' shaped or bayonet shaped root canal. This case report discusses endodontic treatment of a maxillary second premolar with an 'S' shaped root canal.
  2,669 468 1
ORIGINAL ARTICLES
Assessment of antibacterial activity of self-etching dental adhesive systems: An in vitro study
Mithra N Hegde, Priyadarshini Hegde, Veena Shetty, Pavitra B Sampath
October-December 2008, 11(4):150-153
DOI:10.4103/0972-0707.48838  PMID:20351972
Aim: To evaluate and compare the antibacterial activity of polymerized, two-step, self-etching and one-step, self-etching adhesive systems by using the direct contact test after one, seven, and fourteen days. Materials and Methods: The direct contact test was used to evaluate the antibacterial activity of Clearfil Protect Bond, Adper SE Plus, Clearfil SE Bond, and Adper Easy One on Streptococcus mutans after aging the samples in phosphate-buffered saline for one, seven, and fourteen days. Statistical analysis included the one-way Anova and Tukey's multiple comparison tests. Results: Among the tested materials, Clearfil Protect Bond exhibited an antibacterial effect for seven days when in contact with S. mutans . None of the adhesive systems exhibited any antibacterial effect after 14 days. Conclusion: The incorporation of antibacterial agents into dentine-bonding agents may become an essential factor in inhibiting residual bacteria in the cavity following a cavity disinfection procedure, and it could be recommended in situations where total disinfection of cavity is not accomplished due to lack of accessibility.
  2,526 377 1
Evaluation of the effects of the oxygen-inhibited layer on shear bond strength of two resin composites
Ankur Sehgal, Y Madhukar Rao, Martha Joshua, L Lakshmi Narayanan
October-December 2008, 11(4):159-161
DOI:10.4103/0972-0707.48840  PMID:20351974
Aim: The rising demand for aesthetic adhesive restorations has led to the wide use of composites. Multilayer techniques are recommended for the success of these restorations. However, this technique of layering causes the problem of interlayer adhesion, thus supporting the influence of the oxygen-inhibited layer. This study sought to test the hypothesis that the oxygen-inhibited layer increases the shear bond strength of composite resin by allowing the resins on both sides to cross the interface and form an interdiffusion zone. Materials and Methods: A microhybrid composite resin, Charisma, and a nanofill composite resin, Solare, were used in this study. Cylindrical specimens of the composites of 5 mm diameter and 6 mm height were prepared and embedded in acrylic resin moulds after curing. Curing was done in an argon atmosphere to prevent the formation of the oxygen-inhibited layer. To clinically simulate an inert atmosphere, a cellophane matrix strip was used during the process of curing. Results: Shear bond strength of the specimens was tested using a universal testing machine and the results were tabulated and statistically analyzed.
  2,407 242 1
Comparative evaluation of self-etching primers with fourth and fifth generation dentin-bonding systems on carious and normal dentin substrates: An in vitro shear bond strength analysis
Ramesh H Giriyappa, B Suresh Chandra
October-December 2008, 11(4):154-158
DOI:10.4103/0972-0707.48839  PMID:20351973
Aim: The aim of this study was to test the hypothesis that bonding to caries-affected dentin would yield strengths that are lower than bond strengths achievable when bonded to normal dentin. Dentin-bonding systems used in this study were fourth and fifth generation as well as self-etching primers. Materials and Methods: Forty-eight freshly extracted mandibular and maxillary molars were selected of which 24 were caries-affected teeth and the remaining were noncarious teeth. Random sampling was done with eight teeth in each group based on the bonding system used. In caries-affected teeth, the soft, stainable, caries-infected dentin was excavated using a caries detector dye whereas the hard, caries-affected, nonstainable dentin was retained. All the teeth were subsequently mounted in a suitable acrylic mould. Prepared teeth were restored with a single composite resin, using three different dentin bonding systems. These prepared specimens were transferred to a Hounsfield tensometer to measure the shear bond strength. The results obtained were analyzed using Anova, Student's unpaired t-test, and Student Neuman Keulis test. Results: The results showed that the self-etching primer required the highest mean shear load compared to the fifth and fourth generation dentin-bonding systems in both normal dentin and caries-affected dentin. Conclusion: Bond strength to dentin depends on whether the dentinal tubule is open or occluded. Within the limitations of this study, it was observed that bond strength to caries-affected dentin was low compared to normal dentin.
  1,888 276 1
GUEST EDITORIAL
"Old is gold"
AP Tikku
October-December 2008, 11(4):139-139
DOI:10.4103/0972-0707.48832  PMID:20351968
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EDITORIAL
Be original - You were born one
Velayutham Gopikrishna
October-December 2008, 11(4):140-140
DOI:10.4103/0972-0707.48833  PMID:20351969
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JOURNAL REVIEWS
Journal Reviews
R Meera
October-December 2008, 11(4):171-171
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