DISSERTATION –SYNOPSIS

DR. NIKESH P N

POSTGRADUATE STUDENT

DEPARTMENT OF PROSTHODONTICS

BATCH 2012-2013

A.J. INSTITUTE OF DENTAL SCIENCES, KUNTIKANA

MANGALORE


Rajiv Gandhi University of Health Sciences, Karnataka

Bangalore

ANNEXURE II

PROFORMA FOR REGISTRATION OF SUBJECT FOR MDS DISSERTATION

1.  / Name of the candidate / DR. NIKESH P N
DEPARTMENT OF PROSTHODONTICS
A.J. INSTITUTE OF DENTAL SCIENCES
KUNTIKANA
MANGALORE-575 004
2.  / Name of the Institution / A.J. INSTITUTE OF DENTAL SCIENCES
KUNTIKANA
MANGALORE -575 004
3.  / Course of the study and subject / MASTER OF DENTAL SURGERY
PROSTHODONTICS
4.  / Date of admission to course / 22-5-2012
5.  / Title of the topic / “A COMPARATIVE STUDY TO EVALUATE THE EFFECT OF DISINFECTION AND WATER IMMERSION ON HARDNESS OF AUTOPOLYMERISED RESIN,HEAT ACTIVATED DENTURE BASE RESIN AND FLEXIBLE DENTURE MATERIAL” – AN IN VITRO STUDY.
6.  / Brief resume of the intended work
6.1  Need for the study
1.  Cross contamination between patients and dental personnel can occur not only through contaminated dentures but also through polishing agents and instrumentation. Therefore to reduce chances of cross contamination denture should be completely disinfected before being sent to laboratory and before insertion.
2.  In choosing a disinfectant for dental prosthesis consideration should be given to its compatibility with type of material to be disinfected to avoid adverse effects.
3.  Ideally the physical and mechanical properties of denture base resin and artificial denture teeth should remain unaltered after disinfection process. It has been demonstrated that hardness, flexural strength and color stability of denture base resins can be significantly affected by disinfectant solutions such as glutaraldehyde, chlorhexidine,phenolic based,alcohol based and hypochlorite disinfectants.
4.  Certain components of the disinfection solutions may peneterate into denture base resin and result in softening of surface and alteration of the surface morphology. The degree of influence was dependent on duration of immersion and types of disinfectants used. In previous studies alternative chemicals concentrations and immersion times resulted in little deleterious effect. It was observed that 10 minutes of immersion in 4%chlorhexidine gluconate, 1% sodium hypochlorite or 3.78% sodium perborate produced no significant change in transverse strength of 2 denture base resins or in surface hardness of 2 brands of acrylic resin denture teeth.
6.2  Review of literature
1.  Karin Hermana Neppelenbroek and Claudia Pavarina et al (2005)An invitro study to evaluate hardness of 2 denture base resins after disinfections and long term water immersion had been studied. Acrylic resin materials used are lucitone 550 and Qc-20 were submitted to hardness test (Vickers hardness test) before and after disinfection. Qc-20 and lucitone550 specimen exhibited significantly lower hardness value after disinfection regardless of the disinfectant solution used.
2.  Ana Lucia Machado and Larry c. Breeding et al (2009)An invitro study to evaluate microwave and chemical disinfection on the vickers hardness(VHN) and surface roughness (Ra,µm ) of 2 hard chair side reline resins(kooliner,duraliner II) and 1 heat polymerise denture base resin (lucitone 550) duralinerII,kooliner and lucitone 550 were materials used. Disinfection by immersion in sodium perborate or microwave irradiation did not adversely affect the hardness of all materials evaluated. The effect of both disinfection methods on the roughness varied among materials.
3.  Vonica B. Chau and Timothy R.Saunders(1995)An invitro study determined whether bacteria peneterate any of three dental acrylic resins after overnight incubation in liquid broth medium that supports the growth of representative gram positive and gram negative bacteria. If bacteria were cultured from the interior of the acrylic resins the three different disinfectant solutions were evaluated for the ability to peneterate and disinfectant the interior of acrylic resin material. Heat cure lucitone199 (dentsply,york division,york,pa),orthodontic resin (the LD caulk co.Division of dentsply international Inc,milford,Del) and autocuring repair material (L.D. caulk co).This study indicates that alcide LD and biocide disinfectant solutions are not the best choice for adequately disinfecting dental prosthesis from the exterior to interior. The disinfectant and method of choice is a 10 minute in 0.525% sodium hypocholorite solution.
4.  Rosangela Seiko Seo and Carlos Eduardo Vergani et al(2007)An invitro study to evaluate dimensional stability of intact and relined acrylic resin denture bases after microwave disinfection had been studied. Four autopolymerising reline resin resin and heat polymerized acrylic resin were selected for the study. Lucitone 550 resin was selected as a representative of the poly (methyl methacrylate) heat polymerized acrylic resins which are commonly used for the fabrication of denture. Microwave disinfection produced increased shrinkage of intact specimens and those relined with new Truliner and kooliner.
5.  Andrea Azevedo and Ana Lucia Machado et al(2005)An invitro study to evaluate degree of conversion of two hard chair side reline resins and one heat cure acrylic resin indirectly by measuring hardness. The effect of immersion in water on this property was also analyzed. Two chairside reline resins (Duraliner II-D and Kooliner-k) and one heat cured acrylic resin (Lucitone-550-L) were materials used. In general the hardness of the materials evaluated increased during dry storage and decreased after immersion in water.
6.  Tsun Ma and Glen H. Johnson et al (1997).An invitro study to evaluate whether chemical disinfectants altered the surface denture after dentures are disinfected repeatedly and for various amount of time. Five chemical disinfectants (Colorox,Banicide,Cidex-7,Biocide and Multicide) in combination with five denture resins(Dentsply reline material, Hygenic Hyflo, Hygenic perm, Lucitone 199 and TriadVLC reline resin were materials used. One disinfectant (Multicide) cannot be used on all five resins,and the remaining four disinfectants can be used on any of the five resins for upto a period of 30 minutes. All resins tested can be immersed in the four remaining disinfectants for up to 30 minutes without appreciable alteration to surface texture on color. Lucitone 199 can be immersed in any of the four disinfectants for up to 7 days without perceivable color change.
6.3  Objectives of the study
·  To evaluate the effect of water on the hardness of autopolymerised resin,heat activated denture base resin and flexible denture material after keeping in water.
·  To evaluate the effect of disinfectant solution on the hardness of autopolymerised resin,heat activated denture base resin and flexible denture material after keeping in disinfectant solution.
·  To compare the effect of water and disinfectant solution on the hardness of autopolymerised resin,heat activated denture base resin and flexible denture material after keeping in water and disinfectant solution.
7.  / Materials and methods
7.1  Source of data
1.  Autopolymerised resin.(DPI -Mumbai).
2.  Heat activated denture base resin. (Heat cure acrylin H high impact resin).
3.  Flexible denture base material. (Valplast).
4.  One commercially available disinfectant solution.
4% Chlorhexidine gluconate solution. ( kayee aeropharm(p) LTD
5.  Distilled water.
6.  Seperating media.(cold mold seal).(DPI-Mumbai)
Equipments
1.  Rubber Bowl.
2.  Camel hair brush
3.  Flask and clamps(varsity flask,s.s products).
4.  Acrylizer.(Department of Prosthodontics,AJIDS,Mangalore).
5.  Tungsten carbide bur.
6.  Disposable plastic cups.
7.  Vickers hardness testing machine.((KREC,Surathkal,Mangalore).
7.2  Method of collection of data
Test specimen preparation :
Commercially available denture base material each one of autopolymerised resin, heat activated denture base resin, flexible denture material and commonly available disinfectants (4% chlorhexidine gluconate) were selected for the study. Test samples are collected in the form of disc of size 13mm in diameter and 8mm in thickness. Materials will be processed according to the manufacturers directions.
Methodology
42 samples of discs will be prepared:
Material A : 14 samples will be prepared using autopolymerised resin.
Group a1:7 samples in distilled water (control).
Group b1:7 samples in disinfectant.(4% chlorhexidine gluconate solution
Material B : 14 samples will be prepared using heat activated denture base
resin
Group a2 :7 samples in distilled water (control).
Group b2:7 samples in disinfectant(4% chlorhexidine gluconate solution.
Material C : 14 samples will be prepared using flexible denture material.
Group a 3 :7 samples in distilled water (control).
Group b 3 :7 samples in disinfectant.(4% chlorhexidine gluconate solution
42 samples were stored in distilled water at 370 C for 48 ± 2 hours. Micro hardness measurements were made for all samples with Vickers hardness tester using a 25 - gf load for 10 seconds (VHN before disinfection).The diagonals of the pyramid impressed on the sample by the Vickers diamond indentor were measured and noted. Ten indentations were made at different points on each sample and Hardness meaurements were made on each sample prior to disinfection.
Disinfection procedure
After evaluation of the hardness of each sample before disinfection, Each specimen was then scrubbed with 4% chlorhexidine gluconate for one minute,rinsed in water and immersed in 4%chlorhexidine gluconate solution for 10 minutes.Samples were disinfected 4 times to simulate the clinical condition in which both clinician and technician disinfect the prosthesis twice. After disinfection the samples were immersed in water for three minutes and blotted dry. Control samples were maintained in water during the time required to perform the disinfection procedures Hardness measurements as previously described were made again after disinfection.
Following disinfection,samples were stored in water and hardness measurements were made at different time intervals (15,30,60 and 90 days of water immersion). During water storage,each sample was individually immersed into 200 ml disposable plastic cups. The distilled water was discarded after each measurement. Each sample was washed in distilled water,dried with absorbent paper and Vickers hardness value of each sample evaluated using Vickers hardness tester. Statistical analysis of data was conducted with ANOVA test and Bonferroni test.
INVESTIGATION DESIGN







Group a 1 Group b 1 Group a2 Group b2 Group a 3 Group b3





Statistical analysis using ANOVA and BONFERRONI test done.
7.3  Does the study require any investigation or interventions to be made on patients or other humans or animals? If yes, please describe briefly
NO
7.4  Has ethical clearance been obtained from your institution, if yes for 7.3
Not applicable
8.  / List of references
1.  Vonica B.Chau,Timothy R. Saunders,-In –depth disinfection of acrylic resins .J Prosthet Dent 1995;74;309-13.
2.  Tsun Ma,Glen H. Johnson, and Glen E. Gordon-Effects of chemical disinfectants on the surface characteristics and color of denture resins. J Prosthet Dent 1997;77:197-204.
3.  Karin Hermana Neppelenbroek,Ana Claudia Pavarina,Carlos Eduardo Vergani,and Eunice Teresinha Giampaolo-Hardness of heat – polymerized acrylic resins after disinfection and long- term water immersion. J Prosthet Dent 2005;93:171-6.
4.  Andrea Azevedo; Ana Lucia Machado;Carlos Eduardo Vergani; Eunice Teresinha Gimpaolo; Ana Claudia Pavarina. Hardness of denture base and hard chairside reline acrylic resin. J Applied Oral Science 2005;13.
5.  Rosangela Seiko Seo,Carlos Eduardo Vergani,Ana Claudia Pavarina,Marco Antonio Compagnoni,Ana Lucia Machado.Influence of microwave disinfection on the dimensional stability of intact and relined acrylic resin denture bases. J Prosthet Dent 2007;98:216-223.
6.  Ana Lucia, Machado,Larry c.Breeding,Carlos Eduardo Vergani, Luciano Elias da Cruz Perez .Hardness and surface roughness of reline anddenture base acrylic resins after repeated disinfection procedures. J Prosthet Dent 2009;102;115-122.