RAJIV GANDHI UNIVESITY OF HEALTH SCIENCES
BANGALORE, KARNATAKA
ANNEXURE-II
PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION
1. / NAME OF THE CANDIDATEAND ADDRESS
(IN BLOCK LETTERS) / DR. BHATIA VARUN BHARAT
POST GRADUATE STUDENT,
DEPARTMENT OF PERIODONTICS,
K.L.E. SOCIETY’S INSTITUTE OF DENTAL SCIENCES, #20,YESHWANTPUR SUBURB,
TUMKUR ROAD BANGALORE -22.
2. / NAME OF THE INSTITUTION / KLE SOCIETY’S INSTITUTE OF DENTAL SCIENCES, BANGALORE -22
3. / COURSE OF THE STUDY
AND SUBJECT / MASTER OF DENTAL SURGERY IN PERIODONTICS
4. / DATE OF ADMISSION TO
COURSE / 31ST MAY, 2011
5. / TITLE OF THE TOPIC / COMPARATIVE EVALUATION OF GINGIVAL TISSUE RESPONSE AND TENSILE STRENGTH OF SUTURE MATERIALS : A HISTOMORPHOMETRIC AND IN VITRO STUDY
.6. / BRIEF RESUME OF INTENDED WORK:
6.1 NEED FOR STUDY
The goal of suturing after a surgical procedure is to stabilize the tissue flaps in close approximation for an intended period of time. Sutures are made of different bioinert materials based on their physical and chemical properties. Suturing in dentistry is different from suturing in the other parts of the body because of the type of tissues involved, the constant presence of saliva, high tissue vascularization, and functions related to speech, mastication, and swallowing.1,2
The selection of appropriate suture material is a critical step that is based on appropriate tensile strength, tissue biocompatibility, and resorption rates. Biologic responses to suture materials may include varying degrees of inflammatory reaction, 3 related to the physico-chemical properties of the suture material and to the type and condition of the sutured tissues.
Appropriate sutures require specific physical characteristics and properties, such as good tensile strength, dimensional stability, lack of memory, knot security, and sufficient flexibility to avoid damage to the oral mucosa. Studies that have examined the tensile strength and resorption rates of different suture materials found that the tensile strength of the sutures decreased over time and was dependent on the rate of resorption.4,5
A thorough understanding of the physical, mechanical, and biologic properties of commonly used suture materials is essential to the clinical practice of oral surgical procedures and in particular periodontal surgical procedures. However, there are very few studies determining the human gingival tissue response to commonly used suture materials in periodontal surgical procedures and dearth of studies regarding the effect of simulated oral conditions on the tensile strength of suture materials over a period of time. Therefore, the goal of our study is to evaluate histomorphometrically gingival tissue response to four commonly used suture materials in periodontal surgical procedures and to compare the tensile strength of these suture materials under simulated oral conditions.
6.2 REVIEW OF LITERATURE
1. A clinical study was conducted to evaluate clinically and histologically tissue reactions to silk and expanded polytetrafluoroethylene (ePTFE) suture materials placed in human oral tissues. The results revealed that placement of sutures in gingival tissues elicit an inflammatory reaction and that the magnitude of this reaction may vary with the suture material used. Braided silk sutures apparently cause a more extensive inflammatory tissue reaction in an environment characterized by moisture and infectious potential.6
2. A clinical study was performed to study the reaction of human gingiva to four suture material i.e. Silk, Polyester, Perlon and Nylon used in periodontal surgery. The study revealed that silk sutures caused the most intense and prolonged inflammatory reaction. Polyester and Perlon provoked a shorter, less intense inflammatory response. Nylon caused the least inflammatory response and earliest healing process.7
3. An animal study was done to compare and evaluate the inflammatory responses of three widely used suture materials i.e. Silk, Polyglycolic acid and Nylon in the keratinized gingiva and buccal mucosa of beagle dogs. The results revealed that the suture materials placed in the oral mucosa elicited more inflammatory reactions than did those placed in the keratinized gingiva. The multifilament suture materials caused more inflammatory tissue reactions than did the monofilament suture materials in the oral mucosa.8
4. An in vitro study was conducted to compare the tensile strengths of three resorbable suture materials i.e. Chromic catgut (CG), Polyglactin (PG) and Polyglactin-fast absorbing (PG-FA) in 4-0 and 5-0 gauge over a 2-week period under simulated oral conditions. The findings showed that 4-0 sutures are stronger and have greater tensile strength than 5-0 sutures. CG seems to sustain its strength better than PG and PG-FA after 2 weeks. PG-FA may not be a desirable suture if tensile strength is required after 10 days.9
5. An in vitro study was performed to determine the tensile properties of seven commonly used absorbable and non-absorbable sutures i.e. Dexon (poly-glycolic acid), Vicryl (copolymer of glycolide and lactide), Surgical silk, Nurolon (Nylon 66), Ethilon (Nylon 66), Mersilene (Polyester), and Prolene (polypropylene). The findings of the study were that in terms of yield stress Nurolon, Ethilon and Prolene have lowest yield stress, Dexon and Vicryl have intermediate yield stress while Mersilene and Silk have highest yield stress. On the basis of breaking stress Dexon, Ethilon and Vicryl are the strongest; Prolene is in the middle while Silk, Nurolon and Mersiline are the weakest.10
6. An in vitro study was done to evaluate the stability of mechanical properties of seven surgical suture materials i.e. plain catgut, Dexon, Vicryl, Silk, Nurolon, Ethilon, Mersilene, and Prolene in various pH conditions. The findings of the study were that absorbable sutures were more sensitive to pH changes than non-absorbable suture. A strong alkaline medium has more adverse effect on the strength of suture compared to physiologic or acidic pH. Plain catgut sutures lost relatively significant amounts of strength at both acidic and alkaline conditions when compared with Dexon and Vicryl sutures. Among the non-absorbable suture materials, Silk and Nurolon exhibited the largest loss of strength in both alkaline and acidic environments after one month, while other sutures retained almost all of their original strength. Physical configuration of the suture materials seemed also to contribute to the sensitivity of suture materials toward pH.11
7. An animal study was conducted to evaluate the mechanical properties of 10 suture materials before and after in vivo incubation. The materials included were Vicryl, Dexon, Ethibond, silk, plain gut, chromic gut, Maxon, PDS, nylon, and Prolene. The findings of the study were that Elastic modulus was greatest for braided, least for monofilament, and intermediate for gut sutures. Strength, strain, and toughness decreased in all of the sutures over time in vivo with the exception of Ethibond which remained stable. Vicryl, Dexon, and gut sutures were absorbed to the point that they could not be tested after 6 weeks in vivo.12
6.3 OBJECTIVE OF THE STUDY:-
The study comprises of two parts i.e. an in vivo and in vitro.with following objectives:-
1. To evaluate histomorphometrically, the human gingival tissue response to the four suture materials i.e. Surgical silk, Chromic catgut, Polyglactin and Polypropylene used in periodontal surgery.
2. To determine and compare the effect on tensile strength of four commonly used suture materials of simulated oral conditions over two week period.
3. To evaluate microscopically the type of breakage and resorption of each suture material over two week period after placing in simulated oral conditions
To test the null hypothesis that “Suture materials do not differ in their gingival tissue response and tensile strength.”
7. / MATERIALS AND METHODS:-
The study comprises of two parts – in vivo and in vitro
7.1 Suture materials included in the study:-
1. Surgical silk (Mersilk, Ethicon)
2. Chromic Catgut (Surgical gut suture – Chromic, Ethicon)
3. Polyglactin (Vicryl, Ethicon)
4. Polypropylene (Prolene, Ethicon)
All the sutures are of 4-0 gauge
In Vivo part of Study:-
SOURCE OF DATA:-
Outpatient division of Department of Periodontics , KLE Society’s Institute
of Dental Sciences, Bangalore
METHODS OF COLLECTION OF DATA (INCLUDING SAMPLING PROCEDURES, IF ANY):-
Study type:- In vivo and In vitro study
In Vivo part of study:-
Sample size – 22 subjects (88 sites)
In Vitro part of study:-
Suture samples – 24 ( 144 specimens)
INCLUSION CRITERIA:-
Patients will be selected on following criteria:-
1. Systemically healthy
2. Patient requiring excision of gingival tissue as a part of routine periodontal
surgery
3. No history of periodontal surgery in the experimental area in the past 12
months
EXCLUSION CRITERIA:-
Patients that will be excluded if are:-
1. Patients with general contraindications for periodontal surgery
2. Medically compromised subjects,
3. Pregnant subjects
4. Subjects on use of antibiotics or non-steroidal anti-inflammatory drugs or
immunosuppressant medication within the last six months
5. Subjects with acute illnesses or acute oral lesions
6. Smokers And smokeless tobacco users
7. Chronic alcoholics
7.2 Study design:-
Informed consent:-
Patient will be explained about all the aspects of the study and an informed consent will be obtained from the patients before any procedure is performed.
Phase I therapy:-
All patients will be provided with thorough scaling and root planing before the commencement of in vivo phase of the study. The therapeutic endpoint will be defined as clean root surface devoid of visible or clinically detectable remnants of biofilm or calculus. The patient will be re-evaluated at 15 days following phase I therapy and sutures will be placed in the surgical area if there is a need for excision of gingival tissue as a part of routine periodontal surgery.
Placement of sutures:-
A 7-day observation period is considered adequate for the present study as stated by Leknes K.N et al, 2005.6 Seven days prior to scheduled excision procedure, sutures will placed in the gingival tissues planned for excision under local anaesthesia. The surgical area receiving a particular suture material will be decided by simple randomization by picking up strips of paper with name of suture material written on it from a box. Single interrupted suture will then be placed in the gingival tissues planned for excision. Each experimental suture will be tightly adapted and tied with a buccally placed surgical knot. The patients will be instructed to rinse twice daily with 0.2% chlorhexidine solution to maintain plaque control and to refrain from brushing the surgical area during the experimental period.
Surgical Procedure:-
The gingival tissues will be excised along with the sutures in situ as a part of scheduled surgical procedure and will be sent for histopathological evaluation. Each patient will receive postoperative care according to routines of the Department
Specimen Handling and Histologic Analysis:-
A total of 88 sutures will be placed in patients and will be harvested and processed for examination. Harvested tissues will be immersed in a formaldehyde fixative, rinsed in water, dehydrated in ethyl alcohol, and embedded in paraffin. The specimens will be oriented so that serial sections could be made parallel to the tissue surface, with the suture in situ. Thus, the suture will be intended to have a cross-sectioned profile in the section. Individual sections will be mounted on glass slides and stained with hematoxylin and eosin (H&E) and examined under optical microscope.
The following parameters will be evaluated histomorphometrically and tabulated for each section:-
1. Mean thickness of the perisutural epithelial sleeve if present
2. Proportion of inflammatory cells to perisutural epithelial cells
3. Diameter of the connective tissue inflammatory infiltrate (measured in mm) from the periphery of the epithelialization of the sutures.
In Vitro part of the Study:-
Study design:-
Suture specimens:-
Each suture specimen will be tied to two ends of a Instron Tensinometer with a square surgeon knot at a fixed distance of 45cms. The suture will be pretensioned to using the Instron tensionometer to avoid knot slippage during testing. All knots that will slip will be discarded and remaining samples will be used for the study.
Simulation of oral environment:-
A biologic simulation of the oral cavity will be prepared by mixing artificial saliva and human serum in a 1:1 ratio. This biologic solution will be maintained at a pH of 7.4 to 8.1 in an incubator at 370C.
4 suture samples (1 of each suture material) will be placed in the serum saliva mixture simulating the oral environment in six different flasks and maintained for a specified time in a non-tensioned state. The biologic solution will be replenished every 2 days to maintain the pH.
Tensile Strength measurement:-
Tensile strength of the specified suture samples will be tested at specified time periods i.e. preimmersion, 1, 3,7,10 and 14 days postimmersion. Tensile strength assessment will be done using the Instron Tensinometer. Each specimen will be stretched to failure and the maximum load will be recorded in Newtons (N) and tabulated for analysis. For each type of suture, six specimens will be tested to determine the tensile strength. A total of 144 suture specimens will be tested during the study period.
Microscopic evaluation:-
The point of breakage and the samples will be assessed at a magnification of 10 X under a light microscope with a attached digital camera to determine the type of breakage and the resorption pattern and extent.
STASTICAL TESTS THAT WILL BE USED:-
In Vivo part of study:-
1. The inflammatory cell and epithelial cell densities will be calculated by counting the number of grid points falling on leukocyte-like cells and epithelial cells, respectively.
2. The proportion of inflammatory cells to epithelial cells will then be used as a parameter for statistical comparisons between the four suture materials
3. All clinical and histomorphometric parameters will be tabulated and total subject mean and standard deviation will be calculated for each response variable.
4. An analysis of variance (ANOVA) with repeated measures will be employed to reveal any overall statistically significant differences between the suture materials
In Vitro part of Study:-
1. The knot slippage data will be compared descriptively and with the Fisher exact test.
2. Preliminary analyses will be conducted with analysis of variance (ANOVA) to determine if the materials are different with respect to tensile strength at preimmersion
3. Pairwise comparisons will be conducted using the least significant difference post hoc analysis.
4. In addition, a three-factor ANOVA will be used to assess the tensile strength of different materials over time
7.3 Does the study require any investigation or interventions to be conducted on patients or both humans or animals? If so, please describe briefly.