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  Citation statistics : Table of Contents
   2006| July-September  | Volume 6 | Issue 3  
 
 
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ORIGINAL ARTICLE
Effect of the post geometry and material on the stress distribution of restored upper central incisors using 3D finite element models. Stress distribution on incisors with posts
WA Vasconcellos, CA Jr. Cimini, RC Albuquerque
July-September 2006, 6(3):139-144
DOI:10.4103/0972-4052.29365  
This study evaluated the effect of geometry and material of posts on the stress distribution in maxillary central incisors, using the finite element method. Four 3D models were developed: (i) healthy tooth and restored teeth using (ii) tapered, (iii) cylindrical and (iv) two-stage cylindrical posts. Materials used were stainless steel, titanium, zirconium dioxide, carbon and glass fibers on Bis-GMA matrix. Two stress concentration regions were verified: (i) adjacent to the alveolar bone crest and (ii) dentin-post boundary. Tensile and compressive stresses were concentrated on the palatal and facial surface, respectively, for all the analyzed models. In the dentin portion close to the alveolar bone crest, different anatomical form and material posts presented similar patterns of stress distribution. However, in the dentin-post boundary, more favorable results were presented by glass fibers and carbon fibers posts, followed by titanium, being the worst results associated to the use of stainless-steel or zirconium dioxide posts. Still in the dentin-post boundary, tapered posts presented more favorable results than cylindrical posts, followed by two-stage cylindrical posts, which presented the highest levels of stress concentrations. It was concluded that the insertion of post alters the pattern of stress distribution when compared with the healthy tooth and that smaller stress concentrations are associated to the use of glass fiber or carbon fiber tapered posts.
  2 5,836 457
Evaluation of surface roughness of glazed and polished ceramic surface on exposure to fluoride gel, bleaching agent and aerated drink: An in vitro study
KR Kamala, H Annapurni
July-September 2006, 6(3):128-132
DOI:10.4103/0972-4052.29363  
STATEMENT OF PROBLEM: The effect of acidic solutions on the surface roughness of ceramic material is not well documented. PURPOSE: Evaluate the surface roughness of three acidic solutions on exposure to two ceramic materials. MATERIALS AND METHODS: About 40 discs (10 mm diameter, 2 mm thick) were made from the following ceramic: low-fusing ceramic (Ivoclar classic) Group A and all ceramic (Ivoclar IPS empress 2) Group B. Each disc abraded with medium-grit diamond on one half of disc and polished with diamond paste while other half retains the glaze. The discs (10 specimens/group) immersed in 1.23% APF Gel, 16% carbamide peroxide, Coca-cola and distilled water (control). The surface roughness evaluated with surface profiler, before and after exposure to acidic solutions followed by SEM analysis. The data analyzed using Student's t -test and Student's independent t -test. Increase in surface roughness was calculated in percentage change. RESULTS: For Group A, Ra values for glazed surface were significantly higher than Ra values before exposure to acidic solutions (1.07 ± 0.17 mm, 1.090.33 mm, 1.29 ± 0.33 mm and P <0.05). For Group B, glazed surface showed higher values after exposure, not at significant level. Polished surfaces had no effect on exposure to acidic solutions. Coca-cola showed higher percentage changes in surface roughness among acidic solutions. SEM showed acidic solutions etched the ceramic surfaces of both materials. CONCLUSION: Polishing ceramic with diamond paste provides smoother surface than glazed surface. Roughening of porcelain may occur following application of fluoride gel, bleaching agent and on exposure to Coca-cola.
  1 6,418 460
An investigation into the transverse and impact strength of a new indigenous high-impact denture base resin, DPI- tuff and its comparison with most commonly used two denture base resins
R Arundati, NP Patil
July-September 2006, 6(3):133-138
DOI:10.4103/0972-4052.29364  
An investigation into the transverse and impact strength of a new indigenous high - impact denture base resin, DPI- TUFF and its comparison with two most commonly used two denture base resins. INTRODUCTION: The heat cure denture base resins are extensively used for their excellent properties such as ease of handling, durability and esthetics etc. However, their strength properties are field for ongoing research, leading to various modifications of the resins to improve its strength, which include the high - impact resins. AIMS AND OBJECTIVES: A study was carried out to evaluate and compare the transverse and impact strength of a new high - impact denture base resin and it was compared with two most commonly available resins in the market. The materials used were DPI-TUFF, Lucitone 199 and DPI heat cure denture base resins. MATERIALS AND METHODS: A total of 120 resin samples were prepared (60 samples for transverse strength and 60 samples for impact strength) from three different materials. The samples were prepared using the short and long curing cycle and tested under dry conditions and after immersion in water for a week. RESULTS AND DISCUSSION: The obtained values for transverse and impact strength were subjected to statistical analysis. A student's T-test was performed to determine the difference between the materials selected. CONCLUSION: The DPI-TUFF high impact denture base resin appears to be comparatively superior to the other two resins, with mean transverse strength of 115.0 MPa and impact strength of 18.95 kJ/m2. The dry strength of the samples of the materials tested show that it is greater than after immersion of the samples in water at 37șC for a week. The long curing cycle shows considerably higher values of transverse and impact strength as compared to short curing cycle.
  1 6,808 501
CASE REPORT
Role of small diameter implants in prosthetic treatment
R Bansal, N Sharma, BP Singh
July-September 2006, 6(3):145-147
DOI:10.4103/0972-4052.29366  
After years of edentulism, the bone volume gets reduced significantly in width, length and height. So for placement of standard size implants, we have to perform augmentation of the edentulous site, which is time consume and relatively expensive. Hence in these cases we can opt for relatively smaller diameter implants @2-3 mm. A 48 years old lady reported with complaint of poor esthetics due to missing upper front teeth. On examination, her upper central incisors were missing. Implant supported metal ceramic crowns splinted to each other were placed in this patient.
  - 4,009 361
A close-up on obturators using magnets: Part II
Vinaya Bhat
July-September 2006, 6(3):148-153
DOI:10.4103/0972-4052.29367  
Part I of this article presented an exhaustive collection of data about magnets used in Dentistry. Large maxillectomy defects have been restored with multiple segment prostheses retained with the help of magnets. When prosthesis comprises of several components, it is easy to incorporate other features, which would increase the success rate of the treatment. This clinical case report deals with rehabilitation of a patient with an extensive maxillary defect using a 2-segment obturator retained with magnets. The additional features being that, the bulb is fabricated as a closed, single piece structure processed with heat-polymerized acrylic resin unlike most other obturators.
  - 6,358 481
Hidrotic ectodermal dysplasia in a 40-year-old female patient
FM Fabian, BS Lembariti, AP Gesase
July-September 2006, 6(3):154-156
DOI:10.4103/0972-4052.29368  
BACKGROUND: Hidrotic ectodermal dysplasia presents with anomalies such as enamel hypoplasia, hypodontia and facial dysmorphy. In the developed world diagnosis is done during childhood, but in the developing countries patients fail to report for various reasons. Continued documentation of such conditions therefore remains important in oral health. AIM: To report a case of hidrotic ectodermal dysplasis that was successfully treated with removable dentures. FINDINGS: This patient was assessed clinically and by the use of X-ray. The patient presented with mild dysmorphy, severe enamel hypoplasia and hypodontia. The radiograph revealed retained teeth at different stages of development. DISCUSSION: The patient was disturbed by her appearance and pain that prompted her to seek medical attention. Such cases may exist in society but probably resort to traditional healers thus remains undocumented. CONCLUSION: Oral health education is important to bring awareness regarding different conditions of the orofacial region and the importance of seeking medical attention.
  - 6,246 243
A hollow complete denture for severely resorbed mandibular ridges
AM Bhat
July-September 2006, 6(3):157-161
DOI:10.4103/0972-4052.29369  
This article presents a case report of a severely resorbed mandibular ridge situation treated with a hollow complete lower denture, states the rationale behind the treatment and highlights on a technique for the fabrication of a hollow complete lower denture with the objective of emphasizing the use of a hollow complete denture in situations where there is excessive resorption of the residual alveolar ridges and implant treatment is not a realistic option.
  - 9,256 1,158
EDITORIAL
Conventional vs. Resin bonded prostheses
SJ Nagda
July-September 2006, 6(3):111-111
DOI:10.4103/0972-4052.29358  
  - 4,654 405
ORIGINAL ARTICLE
A comparative study to evaluate the marginal accuracy of provisional restorations fabricated by light polymerized resin and autopolymerized resin: A scanning electron microscope study
S Nivedita, DR Prithviraj
July-September 2006, 6(3):122-127
DOI:10.4103/0972-4052.29362  
BACKGROUND AND OBJECTIVES: To compare the vertical marginal discrepancy of provisional restorations fabricated using light polymerized composite resin by direct technique and provisional restorations fabricated using auto polymerized resin by direct and indirect technique. MATERIALS AND METHODS: A total of 45 provisional restorations were fabricated, 15- fabricated by using autopolymerized resin by direct technique on the metal dies and15- fabricated by indirect technique on stone dies. 15 - fabricated using light cured composite resin by direct technique on metal dies. Marginal discrepancies were calculated using scanning electron microscope (SEM). The restorations were then cemented using non-eugenol temporary cement and subjected to SEM analysis. RESULTS: Vertical marginal discrepancy of the provisional restorations fabricated using light cured composite resin by direct technique was least when compared to the vertical marginal discrepancy of the provisional restorations fabricated using autopolymerized resin by direct and indirect technique. Among the restorations fabricated using autopolymerized resin, marginal discrepancy observed with the indirect technique was less compared to the marginal discrepancy observed with direct technique. CONCLUSION: The vertical marginal discrepancy of the provisional restorations fabricated using light cured composite resins by direct technique was least and had a better marginal fit compared to the provisional restorations fabricated using autopolymerized resin by direct and indirect technique. The light cured resin could be a better material used to fabricate provisional restoration with an improved marginal adaptation.
  - 4,816 420
REVIEW ARTICLE
Need for an anterior point of reference in face bow transfer: The changing viewpoint. Changing concepts regarding anterior reference point*
Vidya Chitre
July-September 2006, 6(3):112-114
DOI:10.4103/0972-4052.29359  
It has been accepted for the past many decades that an anatomically related anterior reference point is required during a face-bow transfer to preclude functional and esthetic errors in the finished dental restoration. Various anterior reference points have been researched in an effort to achieve greater accuracy. There is at least one documented viewpoint that reference planes are not required for a correct mounting of stone casts. This paper explores the evolution of the concept of the anterior reference point and arrives at conclusions regarding the perceived need for an anterior reference point, the rationale behind the different anterior reference points and evidence supporting the need for one.
  - 10,845 1,302
CEREC - The power of technology
I Kaur, K Datta
July-September 2006, 6(3):115-119
DOI:10.4103/0972-4052.29360  
CEREC is an acronym for chairside economical restoration of esthetic ceramics. Translated, it means that a dentist can economically restore damaged teeth in a single appointment using a high-quality ceramic material that matches the natural colour of other teeth. With over 7,000,000 restorations placed since the introduction of CEREC technology in 1987, CEREC is one of the most researched restorative systems in the market, with documented success rate of more than 90% after 10 years. It uses a sophisticated combination of high-tech precision machinery and computer technology to produce custom restorations that include 3/4 crowns, full crowns, veneers, inlays and onlays. The CEREC 3D system allows the dentist to take digital impression with 100% control of the margin fit, aesthetics, proximal contacts and the occlusal surface. With ongoing research and development, the CEREC system has earned its role in dental history as the technology that gives patients one of the finest restorations in the world in only one visit.
  - 6,616 626
A modified technique for preparation of guiding planes for removable partial dentures
Mallika S Shetty, Kamalakanth K Shenoy
July-September 2006, 6(3):120-121
DOI:10.4103/0972-4052.29361  
Proximal tooth surfaces that bear a parallel relationship to one another must either be found or be created. More often they should be created in the patients mouth. Past literatures show that several attempts have been made to achieve parallel guiding planes. in the patients mouth. However, they are met with limited success. This article describes a predictable method of achieving parallel guiding planes in the patients' mouth.
  - 7,165 661