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2008| April-June | Volume 11 | Issue 2
November 12, 2008
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Evaluation of depth of cure and knoop hardness in a dental composite, photo-activated using different methods
Mithra N Hegde, Priyadarshini Hegde, Babita Malhan
April-June 2008, 11(2):76-81
The study aimed at evaluating the depth of cure and knoop hardness of a microfine-hybrid composite resin that was photo-activated using different methods. A bipartite brass mold was filled with composite resin and photo-activation was performed using four methods: (1) Intermittent method using quartz tungsten halogen (QTH) light curing unit (LCU) (2) Continuous method (QTH) (3) Exponential method (QTH) (4) Continuous method using light-emitting diode (LED). Depth of cure was measured at the unexposed bottom surface of the specimen using microtester as a penetrometer. The surfaces exposed to light were subjected to knoop hardness testing, using a digital microhardness tester. Knoop hardness measurements were obtained at the top surface and at depths of 1, 2, 3, 4 and 5 mm. The data was analyzed using anova and Tukey's test (5%). Results showed that the depth of cure was higher with the intermittent method (QTH), followed by the continuous method (QTH), the exponential method and the continuous method (LED). At the top surface and up to 1 mm, continuous method (LED) demonstrated the highest knoop hardness number (KHN). At 2 mm and up to 5 mm, intermittent method (QTH) presented the highest KHN and continuous method (LED) showed the lowest KHN. At all depths, continuous method (QTH) showed higher KHN, as compared to the exponential method (QTH), except at 2 mm where both showed no significant difference.
Biphasic calcium phosphate in periapical surgery
Chinni Suneelkumar, Krithika Datta, Manali R Srinivasan, Sampath T Kumar
April-June 2008, 11(2):92-96
Calcium phosphate ceramics like hydroxyapatite and β -tricalcium phosphate (β -TCP) possess mineral composition that closely resembles that of the bone. They can be good bone substitutes due to their excellent biocompatibility. Biphasic calcium phosphate is a bone substitute which is a mixture of hydroxyapatite and β -tricalcium phosphate in fixed ratios. Studies have demonstrated the osteoconductive potential of this composition. This paper highlights the clinical use of biphasic calcium phosphate as a bone substitute in periapical surgery.
NATIONAL INVITED REVIEW
The periodontal - endodontic continuum: A review
V Sunitha Raja, Pamela Emmadi, Ambalavanan Namasivayam, Ramakrishnan Thyegarajan, Vijayalakshmi Rajaraman
April-June 2008, 11(2):54-62
Periodontal therapy deals with many aspects of the supporting structures, including the prevention and repair of lesions of the gingival sulcus. Endodontics deals primarily with disease of the pulp and periapical tissues. The success of both periodontal and endodontic therapy depends on the elimination of both disease processes, whether they exist separately or as a combined lesion. The relationship between periodontal and endodontic disease has been a subject of speculation for many years. This paper aims at presenting a comprehensive review of several aspects of perio-endo lesions.
Fiber optic backscatter spectroscopic sensor to monitor enamel demineralization and remineralization
Anil Kishen, Annie Shrestha, Adeela Rafique
April-June 2008, 11(2):63-70
In this study, a Fiber Optic Backscatter Spectroscopic Sensor (FOBSS) is used to monitor demineralization and remineralization induced changes in the enamel. A bifurcated fiber optic backscatter probe connected to a visible light source and a high resolution spectrophotometer was used to acquire the backscatter light spectrum from the tooth surface. The experiments were conducted in two parts. In Part 1, experiments were carried out using fiber optic backscatter spectroscopy on (1) sound enamel and dentine sections and (2) sound tooth specimens subjected to demineralization and remineralization. In Part 2, polarization microscopy was conducted to examine the depth of demineralization in tooth specimens. The enamel and dentine specimens from the Part-1 experiments showed distinct backscatter spectra. The spectrum obtained from the enamel-dentine combination and the spectrum generated from the average of the enamel and dentine spectral values were closely similar and showed characteristics of dentine. The experiments in Part 2 showed that demineralization and remineralization processes induced a linear decrease and linear increase in the backscatter light intensity respectively. A negative correlation between the decrease in the backscatter light intensity during demineralization and the depth of demineralization determined using the polarization microscopy was calculated to be
= -0.994. This
experiment highlights the potential benefit of using FOBSS to detect demineralization and remineralization of enamel.
The monk who wants to sell his zen...
April-June 2008, 11(2):51-53
Problem based learning….Need for the hour
April-June 2008, 11(2):49-50
An evaluation and comparison of shear bond strength of composite resin to dentin, using newer dentin bonding agents
Mithra N Hegde, Shruti Bhandary
April-June 2008, 11(2):71-75
The purpose of this study was to assess the shear bond strength of Total etch Prime and Bond NT and self etch newer dentin bonding agents Clearfil S3, Xeno III Bond, Clearfil Protect Bond and G Bond used to bond composite resin to dentin, and to compare the difference in the shear bond strengths of the self etch newer dentin bonding agents. Hundred freshly extracted noncarious human maxillary premolar teeth were selected. The occlusal surfaces of each tooth were ground to prepare flat dentin surfaces at a depth of 1.5 mm and were randomly grouped, with twenty specimens in each: Group I - Prime and Bond NT, Group II - Clearfil Protect Bond, Group III - Xeno III Bond, Group IV - Clearfil S3 Bond, Group V - G Bond. Each group was treated with its respective bonding agents, as per the manufacturers' instructions Clearfill - Kuraray , Japan, G bond - GC Tokyo, Japan, Xeno- De Trey Densply, Germany. Blocks or Cylinders of composite resin were built up using Teflon mold and cured. Shear bond strengths were tested using Instron Universal testing machine and recorded in Mpa. The results were statistically analyzed using One-way anova and Tukeys HSD test. The total etch adhesive showed higher shear bond strength than self etching adhesives (
<0.001). Within the limitations of this
study, it can be concluded that all the adhesive agents evaluated showed optimal shear bond strength 17-20 Mpa, except G bond. However, shear bond strength of composite resin to dentin is better with one bottle total etch adhesive than with the newer self etching bonding agents.
evaluation of the accuracy of two electronic apex locators
Viresh Chopra, Shibani Grover, S Datta Prasad
April-June 2008, 11(2):82-85
This study involves evaluating the accuracy of two electronic apex locators (EALs), Raypex and Neosono Co-pilot. Ten single-root human anterior teeth were used for the study. The crown was sectioned to gain access to the root canal. For each tooth, the reference (or control) length, corresponding to the actual length, was determined, after which all the teeth were measured independently. The results obtained with each EAL were in turn compared with the corresponding control length. The statistical analysis of the results showed that EAL reliability in detecting the apex varies from 80 to 85% for Neosono systems and 85 to 90% for the Raypex systems. Combined with a high observer concordance, these results suggest that electronic root canal measurement can be an objective and acceptably reproducible technique.
The effect of McInnes solution on enamel and the effect of Tooth mousse on bleached enamel: An
HE Darshan, ND Shashikiran
April-June 2008, 11(2):86-91
To evaluate the effect of McInnes bleaching agent on the micro hardness of enamel before and after bleaching and to evaluate the effect of G C Tooth Mousse on the bleached enamel surface for its microhardness.
Materials and Methods:
McInnes bleaching solution, Casein phosphopeptide-amorphous calcium phosphate CCP-ACP (G C Tooth mousse) artificial saliva (Dept of Oral Pathology, College of Dental Sciences, Davengere), deionized water, Vickers Micro Hardness tester (Zwick/ZHV, Germany), freshly extracted teeth, cold cure acrylic, Diamond disc (Horico - PFINGST New jersey USA, KAVO- Germany), straight handpiece (kavo peca reta) and plastic moulds (6.5 x 2 mm). The purpose of this study was to evaluate and compare microhardness of the sound enamel surface by Vickers Hardness Number before and after bleaching with McInnes solution, and to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (G C Tooth Mousse) on the bleached enamel surface for its microhardness.
The data obtained from the test were subjected for statistical analysis and are presented as range, mean and standard deviation. P value of 0.05 or less was considered for statistical significance. The changes in microhardness at different times of assessment were analyzed using the paired 't' test
All the samples showed decrease in the microhardness after two cycles of bleaching, though immediately after bleaching the decrease in the microhardness was not significant (P = 0.34). However, after the second cycles, it showed a significant decrease (P<0.01) in the microhardness. After application of remineralization solution (GC Tooth mousse), the samples showed a marginal increase in the microhardness (P<0.05) after seven days and a marked increase after fourteen days (P<0.001).
McInnes bleaching agent does decrease the microhardness of enamel by causing enamel demineralization and GC Tooth mousse used in the study causes an increase in the microhardness of bleached enamel by maintaining a high gradient of calcium and phosphate ions at the enamel subsurface.
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