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2008| January-March | Volume 11 | Issue 1
October 16, 2008
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Alginate impressions: A practical perspective
V Vidyashree Nandini, K Vijay Venkatesh, K Chandrasekharan Nair
January-March 2008, 11(1):37-41
The choice of an impression material for a particular situation depends on the treatment being provided, operator preference, and so on. Even with the introduction of more advanced and more accurate rubber base impression materials, irreversible hydrocolloid impression materials have stood the test of time. This article gives a detailed perspective of how best to make alginate impressions.
Evaluation of natural smile: Golden proportion, RED or Golden percentage
BV Sreenivasan Murthy, Niketa Ramani
January-March 2008, 11(1):16-21
Creating geometric or mathematical proportion to relate the successive width of maxillary anterior teeth is a critical aspect in Esthetic dentistry. Golden proportion, recurring esthetic dental (RED) proportion and golden percentage are new theories in this field.
To investigate the existence and suitability of Golden proportion, Recurring Esthetic Dental, and Golden percentage between the widths of maxillary anterior teeth in individuals with natural dentition, with the aid of digital photographs and computer analysis.
Material and Methods:
Standardized frontal images of 56 dental students, 20 male and 36 female, were captured. Each maxillary anterior tooth was digitally measured. Once the measurements were recorded, the three theories were applied and the data was analyzed statistically.
The golden proportion was found to exist only in 14-25% of the subjects, between perceived maxillary anterior teeth in natural dentition. The value of RED proportion was not constant, and as one moved distally, this proportion gradually increased. Furthermore, the results revealed that golden percentage was rather constant in terms of relative tooth width. Central incisor represented 22%, lateral incisor 15% and canine 13% of the width of six maxillary anterior teeth, as viewed from the front.
Both golden proportion and RED proportion are unsuitable methods to relate the successive width of the maxillary anterior teeth in natural dentition. However, the golden percentage theory can be applied if percentages are adjusted, taking into consideration the ethnicity of the population.
Comparative evaluation of maintenance of cell viability of an experimental transport media "coconut water" with Hank's balanced salt solution and milk, for transportation of an avulsed tooth: An
cell culture study
Toby Thomas, Velayutham Gopikrishna, Deivanayagam Kandaswamy
January-March 2008, 11(1):22-29
The purpose of this study was to evaluate the efficiency of a new storage medium, coconut water, in comparison with other traditional storage media like Hank's balanced salt solution (HBBS) and milk, in maintaining the viability of an established cell line BHK-21/C13 (baby hamster kidney fibroblasts) using the direct suspension cell culture technique. The storage media tested in the study were divided into three major groups and two control groups - Group A: HBBS, Group B: milk, and Group C: coconut water. The positive and negative controls corresponded to 0-minute and 24-hour dry times respectively. The three groups were then divided into five subgroups, each denoting the storage time periods 15 min, 30 min, 45 min, 60 min and 120 min respectively. The cell line BHK-21/C13 was subcultured and the number of cells was standardized by making a cell suspension using Minimal Essential Medium in five culture plates. One ml of each experimental group (HBBS, milk and coconut water) was added to eight wells of each culture plate. The culture plates containing the cells and the experimental groups were incubated for the respective time periods. The cells were then counted with a Neubauer counting chamber, under light microscope. The results were statistically analyzed using One-way ANOVA and Multiple Range Test using the Tukey-HSD procedure to identify the significant groups at p ≤ 0.05. Within the parameters of this study, it appears that coconut water may be a better alternative to HBSS or milk, in terms of maintaining cell viability. Coconut water can be used as a superior transport medium for avulsed teeth.
Retrieval of a separated instrument using Masserann technique
Arun Kulandaivelu Thirumalai, Mahalaxmi Sekar, Sumitha Mylswamy
January-March 2008, 11(1):42-45
The fracture of endodontic instruments is a procedural problem creating a major obstacle to normal routine therapy. The separated instrument, particularly a broken file, leads to metallic obstruction in the root canal and impedes efficient cleaning and shaping. When an attempt to bypass such a fragment becomes difficult, it should be retrieved by mechanical devices. Masserann kit is one such device for orthograde removal of intracanal metallic obstructions. These clinical cases demonstrate the usage of Masserann technique in removal of separated instruments in anterior and also the posterior teeth.
INTERNATIONAL INVITED REVIEW
A new paradigm for operative dentistry
Graham J Mount
January-March 2008, 11(1):3-10
It is over 100 years since G V black gathered together most of the knowledge then current on the caries process and set clear parameters for the discipline of operative dentistry. His four-volume treatise set standards that were relevant for the times and, in fact, were so well described that they remained dominant in this discipline until quite recently. However, over the last 50 years there has been great progress in scientific method and in knowledge of the common diseases of the oral environment, including the caries process, so maybe it is time for change. The term "paradigm" describes a philosophy of science, a generally accepted model of how ideas relate to one another, forming a conceptual framework within which scientific research is carried out. Black defined the paradigm within which further research was to be conducted during the following years and the profession accepted his lead. However, it is not expected that the parameters of a profession should remain unchanged over a substantial period so it is suggested that the dental profession should, at this time, recognize a new paradigm. Improvements in scientific method have led to a better understanding of the oral environment, resulting in extensive changes for this profession. It is suggested that the standards set by Black should be now consigned to history and an entirely new paradigm adopted. First, the profession must recognize that dental caries is a bacterial disease and its primary efforts should be directed towards identification and elimination of the disease prior to initiating repair of the damage that it has caused. Preservation of natural tooth structure is then the next responsibility. There should be maximum use made of preventive strategies, including remineralization, followed by minimal intervention cavity designs and the use of bioactive restorative materials to restore the lesions. The profession should be prepared to move on.
We have a dream…In pursuit of excellence
January-March 2008, 11(1):2-2
Bridging the gap…From clinical research to clinical practice
January-March 2008, 11(1):1-1
Dentine deproteinization and microleakage around gingival third resin restorations
Sowmya Shetty, B Mithra, B Sureshchandra
January-March 2008, 11(1):11-15
A significant factor in achieving satisfactory adhesion of restorative resins to dentine substrate is the method by which the dentine surface is treated before an adhesive is applied. The aim of this study was to evaluate the effect of deproteinization on microleakage around gingival third resin restorations.
Materials and Methods:
Standardised Class V preparations were made on randomly selected intact upper and lower human molars. These were treated in one of five ways (no treatment, enamel etch only, total etch, total etch followed by deproteinization, and deproteinization only) and then adhesively bonded using either an acetone or ethanol based bonding system. The samples were first immersed in 2% methylene blue dye and then 35% nitric acid, for 72 hours each. The solutions were filtered and centrifuged, and the supernatant was used to determine absorbance in a spectrophotometer at 670 nm. The results were recorded as a measure of transmission of light of the test solutions.
The results were subjected to multiple comparisons amongst groups, using anova. There was a statistically significant difference between all treatment groups for the two different bonding systems used. The experimental groups, total etch alone and total etch followed by deproteinization showed statistically significant differences, as compared to all other groups. However, although the total etch group showed a decrease in microleakage, when compared to the total etch followed by deproteinization group, this was not statistically significant.
Within the limitations of this study, collagen removal may be important to reduce microleakage whilst using acetone based adhesive systems and it may not influence the amount of microleakage for ethanol or water based adhesive systems.
Shear bond strength of eugenol- and non-eugenol-based endodontic sealers to gutta-percha and dentin: An
Shibu Thomas Mathew, Mithra N Hegde
January-March 2008, 11(1):30-36
a) To evaluate the bond strength of eugenol- and non-eugenol-based endodontic sealers to gutta-percha and dentin and b) To make a comparative evaluation of the bond strength of sealers to gutta-percha and dentin.
Material and Methods:
Seventy-two specimens were used in this study, which was divided into two groups - group I consisting of 36 freshly extracted human molars with 2 mm coronal cut surface; and group II consisting of gutta-percha disks of 10 mm diameter and 2 mm thickness embedded in 36 plaster of Paris specimens. Group I was further divided into three subgroups: subgroup 1, subgroup 2, and subgroup 3, consisting of 12 teeth each; and group II was further divided into three subgroups: subgroup 1, subgroup 2, and subgroup 3, consisting of 12 plaster specimens each. Each subgroup consisted of two materials each, which were placed in 5 mm long sections of polyethylene tubing and were then placed on coronal 2 mm cut surface of human molars; likewise subgroup 1, subgroup 2, and subgroup 3 of group II consisted of two materials each, which were also placed in 5 mm long sections of polyethylene tubing and then placed on gutta-percha disks 10 mm in diameter and 2 mm in thickness, which were embedded in the plaster specimens. After the materials were set, the specimens were subjected to test for shearing bond strength using a universal testing machine (Instron).
Group I, i.e., zinc oxide eugenol sealers, showed more bond to gutta-percha than to dentin, in which subgroup 2b, endomethasone, showed the maximum bond. Group II, i.e., non-zinc oxide eugenol sealers, showed more bond to dentin than to gutta-percha, where the maximum bond was shown by subgroup 3b, EndoRez.
Under the circumstances of this in
study, all the six endodontic sealers had significant differences in terms of shear bond strength to gutta-percha and dentin.
© 2008 Journal of Conservative Dentistry | Published by Wolters Kluwer -
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