RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES, BANGALORE, KARNATAKA.
ANNEXURE II.
PROFORMA FOR REGISTRATION OF SUBJECT FOR DISSERTATION.
1. NAME OF THE CANDIDATE AND ADDRESS:
Dr. Neha Darshan Navlani
P.M.N.M. Dental College and Hospital,
Bagalkot – 587 101.
Karnataka.
2. NAME OF THE INSTITUTION:
P.M.N.M. Dental College and Hospital,
Bagalkot – 587 101.
Karnataka.
3. COURSE OF STUDY AND SUBJECT:
M.D.S. (Master of Dental Surgery)
Prosthodontics, Crown and Bridge and Implantology.
4. DATE OF ADMISSION OF COURSE:
30th May 2012 5. TITLE OF THE TOPIC: “Comparative invitro evaluation of the flexural strength of bis-acryl composite resins for provisional crowns and fixed partial dentures”.
6. BRIEF RESUME OF THE INTENDED WORK: To evaluate and compare the flexural strength of bis-acryl composite resins for provisional crowns and fixed partial dentures.
6.1 NEED FOR THE STUDY:
Provisional crowns and fixed partial dentures are essential components of fixed prosthodontic treatment. They are cemented immediately after tooth preparation to reestablish esthetics and function, as well as to protect the adjacent periodontium and pulp tissue against exogenous damage. The need for provisional restorations in fixed prosthodontic treatment arises due to the considerable time that is required for the fabrication of the definitive prostheses. The provisional restorative materials must satisfy biologic and esthetic needs as well as mechanical requirements such as resistance to functional loads, resistance to removal forces, and maintenance of abutment alignment. Provisional restorative materials can be divided into four groups according to composition as polymethyl methacrylate (PMMA), polyethyl or butyl methacrylate, microfilled bisphenol A-glycidyl dimethacrylate (Bis-GMA) composite resin, and urethane dimethacrylate (light-polymerizing resins). Amongst them, bis-acryl composite resins have gained popularity due to recent advancement in their formulation with improved aesthetics, durability and properties such as low exothermic reaction and polymerization shrinkage, good fit, increased strength and colour stability, ease of dispensing, manipulation and use. The selection of provisional restorative material for crowns and fixed partial dentures is done considering various factors like flexural strength, marginal accuracy, colour stability, wear resistance, tissue compatibility, not irritating to pulp tissue and periodontium, ease of manipulation and cost. The flexural strength of provisional restorative material is of great importance because these materials are subjected to masticatory forces and should be able to survive them. The flexural strength of provisional restorative materials is critical particularly when the patient uses the provisional fixed restoration for an extended period, when the patient exhibits parafunctional habits, or when long-span prosthesis with short height pontics and connectors is planned. Fracture of provisional fixed restorations is annoying to the patient and clinician and repairs may be time consuming and expensive. Studies evaluating and comparing flexural strength of the bis-acryl composite resins for provisional crown and fixed partial dentures are scarce in the available dental literature. So an in vitro study was planned to evaluate and compare the flexural strength of bis-acryl composite resins for provisional crown and fixed partial dentures.
6.2. REVIEW OF LITERATURE:
An invitro study was done to compare the flexural strength of seven resins used to fabricate interim fixed prostheses. Materials used were Trim, Acropars, Protemp 3 Garant, Unifast LC, TempSpan, Tempron, and Duralay. Ten identical 25 × 2 × 2 mm specimens were made from seven interim materials (N = 70) according to ADA specification #27. After fabrication they were stored in artificial saliva for 14 days and thermocycled for 2500 cycles (5˚C to 55˚C), a standard three-point bending test was conducted on the specimens with a universal testing machine at a crosshead speed of 0.75 mm/min. The mean values of flexural strength of each interim material were calculated. Data were analyzed using the Kruskal-Wallis and Mann- Whitney U-test, and the significance level was set at α= 0.05.The lowest and highest flexural strengths were found for Trim from ethyl methacrylate resins and TempSpan from bis-acryl resins, respectively. There was no significant difference between Tempron and Protemp 3 Garant, but the other resins were significantly different. The study concluded that Bis-acryl interim materials exhibited higher flexural strength than the methacrylate resins tested in this study.1
An invitro study was done to compare the flexural strength of 5 methacrylate-based resins and 8 bis-acryl resins used to fabricate provisional crowns and fixed partial dentures. Materials used were Alike, Caulk, Instatemp, Integrity, Jet, Luxatemp, Protemp Garant, Protemp 3 Garant, Provipont, Provitec, Temphase, Unifast LC, and Zeta C&B Acrylic. Bar-type specimens were fabricated according to American National Standards Institute/American Dental Association specification 27. After being immersed in artificial saliva at 37°C for 10 days, the specimens were fractured under 3-point loading in a universal testing machine at a crosshead speed of 0.75 mm/min. Maximal loads to fracture in Newtons were recorded. Mean flexural strengths were calculated in MPa (n = 10 per group). Comparisons were made with analysis of variance and Duncan’s multiple range test (P<.05). Mean flexural strengths ranged from 56.2 to 123.6 MPa. There were 4 statistically similar groups. The group with the highest strengths consisted of 4 bis- acryl materials (Provipont, Integrity, Protemp 3 Garant, and Luxatemp).Within the limitations of this study, flexural strengths were material- rather than category specific.2
An invitro study was done to investigate the flexural strength and flexural modulus of provisional crown and bridge materials at different storage times after mixing using materials with different curing mechanisms (dual-curing vs. self-curing). Flexural strength and flexural modulus of four proprietary materials (Trim, Luxatemp AM Plus, Luxatemp AM Plus Solar and Cool Temp Natural) were tested in a 3-point bending test according to EN ISO 4049:2000 at various times after mixing (37 0C dry/water) including thermocycling (5000:5-550C). Mean values of all measurements were calculated and subjected to the Games–Howell test ( p = 0.05) as well as a regression analysis ( p = 0.05). A two-way ANOVA (p = 0.05) was used to identify the influence of the curing mechanism and chemical nature of the materials used. Flexural strength ranged between 11.1 and 24.0 MPa and Flexural modulus between 82.5 and 548.2 MPa for all tested materials except for the dual-curing material (FS: 82.4 MPa; FM: 2060 MPa) 10 min after mixing. The chemical nature and curing mechanism significantly influenced (p < 0.001) the mechanical properties, however, the influence of the curing mechanism disappeared at progressive points in time after mixing, comparing Luxatemp AM Plus versus Luxatemp AM Plus Solar. The study concluded Flexural strength and Flexural modulus significantly depend on the time after mixing. Composite resin based materials are preferred versus methacrylate resins due to more favorable mechanical properties. If a high mechanical strength is indispensable directly after fabrication, a dual-curing provisional material is recommended.3
An invitro study was done to compare the flexural elastic moduli and moduli of rupture of four materials used to make provisional restorations. Material used were Provipont DC resin, Triad provisional restorative material, Jet acrylic resin, and a 50:50 mixture of Jet acrylic resin and orthodontic resin. Thirty-nine identical 63 10 3 mm specimens were made from each of the four materials. Method used was after storing for 24 hours, 30 days, and 60 days in water at 37° C (13 specimens each), standard three-point bend tests were conducted on an Instron universal testing machine at a crosshead speed of 0.5 cm/minute. Stress strain curves were generated, and values for the flexural elastic moduli and moduli of rupture were calculated. Data were subjected to two-way and one-way analyses of variance (a = 0.05). Provipont DC resin exhibited significantly higher flexural elastic moduli and moduli of rupture values at the 24-hour test time. However, Provipont DC resin exhibited the greatest decrease in these values overtime.4
An invitro study was done to compare the fracture strength of several commercial interim fixed partial denture materials in an artificial oral environment. Materials used were Trim and Cronsin and the composite-based materials Protemp 3 Garant, Protemp Garant, Luxatemp, and Tempofit. Twenty identical three-unit FPDs of the PMMA materials were cemented on Co-Cr alloy dies. Ten FPDs of each material were stored for 24 hours in distilled water as a control group and the other ten FPDs of each material were stored for 14 days in distilled water and artificially aged as test group. Fracture resistance was determined using a universal testing machine. It was found that the tested interim materials showed initial fracture values between 484 and 1,081 N. The study showed that all Tempofit FPDs, four Luxatemp FPDs, two Protemp Garant FPDs, and one Protemp 3 Garant FPD failed because of fracture during artificial aging. The remaining FPDs showed fracture values of 759 N (Luxatemp), 772 N (Protemp Garant), and 956 N (Protemp 3 Garant). It was concluded that the PMMA FPDs and the composite Tempofit FPDs showed poor stability during artificial aging, the highest values for fracture resistance with low fracture rates were displayed by the provisional FPD material Protemp 3 Garant. This may allow clinical application for long-term interim restorations.5
6.3 OBJECTIVE OF THE STUDY: 1. To evaluate and compare the flexural strength bis-acryl composite resins for provisional crowns and fixed partial dentures. 2. To evaluate the effect of immersion time in artificial saliva on the flexural strength of bis-acryl composite resins for provisional crowns and fixed partial dentures.
7. MATERIALS AND METHODS:
7.1 SOURCE OF DATA: Materials used: 1. ProtempTM II (3M ESPE AG, Dental Products,D-82229 Seefeld-Germany). 2. Integrity (Dentsply Caulk, 38 West Clark Avenue Milford, DE 19963 USA). 3. Cool Temp0 NATURAL (Coltene/Whaledent AG, Feldwiesenstrasse 20 9450 Alstatten/Switzerland). 4. TempofitR (Detax, Carl-Zeiss-Str, 4.76275 Ettlingen/Germany). 5. Artificial saliva.
Instruments used:
1. Metal split mold for making specimens for flexural strength.
2. Universal Testing Machine. (Unitek 9450PC)
7.2 METHOD OF COLLECTION OF DATA:
1. Fabrication of specimens for evaluating of the flexural strength: The fabrication of specimens for evaluating of the flexural strength is done using metal split die with mold space of dimensions of 25 × 2 × 2 mm (ADA specification no. 27).The mold space is lubricated with thin layer of petroleum jelly and the provisional restorative materials selected in this study will be manipulated according to the manufacturer’s instructions and inserted into the mold. A weight of 1.5 kg is applied to the surface of the mold to allow excess resin from the mold to extrude and to apply needed pressure during polymerization. After polymerization the specimen are carefully removed from the mold and finished. In this manner 120 specimens are fabricated with 30 specimens for each provisional restorative material.
2. Grouping of specimens: Total 120 specimens are fabricated, 30 specimens of each provisional restorative material. The 30 specimens of each provisional restorative material, are randomly divided into three groups according to immersion time in artificial saliva as, T1 group (n=10), T14 group (n=10), T30 group (n=10).In T1 group the specimens are immersed in artificial saliva at 370C for 24 hours i.e. 1 day. In T14 group (n=10) the specimens are immersed in artificial saliva at 370C for 14 days. In T30 group (n=10) the specimens are immersed in artificial saliva at 370C for 30 days. The artificial saliva is changed daily. The storage protocol is selected to partially simulate the oral environment and to evaluate the effect of storage time on the provisional restorative materials.
3. Testing of flexural strength: The Flexural strength is evaluated by using a universal testing machine (Unitek 9450PC) by three point bending test. The test is carried out with a 10 KN load cell at a crosshead speed of 0.75 mm/minute. The force at fracture is recorded in Newtons and converted to MegaPascals (MPa). The flexural strength is calculated using the formula, S = 3PI/2bd2 where S = flexural strength, P = fracture load, I = distance between the supports, b = width of the specimen, and d = thickness of the specimen. The results are submitted to analysis of variance and compared by Tukey’s test (α=0.05).
7.3 DOES THE STUDY REQUIRE ANY INVESTIGATION OR INTERVENTION TO BE CONDUCTED ON PATIENTS OR OTHER HUMAN OR ANIMAL? IF SO, PLEASE DESCRIBE BRIEFLY.
NO. 7.4 HAS ETHICAL CLEARANCE BEEN OBTAINED FROM YOUR INSTITUTION? Not applicable
8.0 LIST OF REFERENCES:
1. Nejatidanesh F, Momeni G, Savabi O. Flexural strength of interim resin materials for fixed prosthodontics. J Prosthodont 2009; 18(6):507-11. 2. Haselton DR, Diaz-Arnold AM, Vargas MA. Flexural strength of provisional crown and fixed partial denture resins. J Prosthet Dent 2002; 87(2):225-8. 3.Balkenhol M, Mautner MC, Ferger P, Wostmann B. Mechanical properties of provisional crown and bridge materials: chemical-curing versus dual-curing systems. J.Dent2008; 36(1):15- 20. 4. Ireland MF, Dixon DL, Breeding LC, Ramp MH. In vitro mechanical property comparison of four resins used for fabrication of provisional fixed restorations. J Prosthet Dent 1998; 80(2):158-62. 5. Lang R, Rosentritt M, Behr M, et.al. Fracture resistance of PMMA and resin matrix composite-based interim FPD materials. Int J Prosthodont 2003; 16:381-384
9.0 SIGNATURE OF THE CANDIDATE:
10.0 REMARKS OF THE GUIDE:
11.1 NAME AND DESIGNATION OF THE GUIDE: Dr. Raviraj G. Desai Professor
Department of Prosthodontics
P.M.N.M. Dental College and Hospital,
Bagalkot, Karnataka.
11.2 SIGNATURE OF THE GUIDE:
11.3 HEAD OF THE DEPARTMENT: Dr. VIKAS B. KAMBLE
Professor and Head,
Department of Prosthodontics
P.M.N.M. Dental College and Hospital,
Bagalkot, Karnataka.
11.4 SIGNATURE OF THE HEAD OF THE DEPARTMENT:
12.1 REMARKS OF THE PRINCIPAL: 12.2 SIGNATURE OF THE PRINCIPAL: DR. SRINIVAS .S. VANAKI Principal, P.M.N.M. Dental College and Hospital, Bagalkot, Karnataka – State.