Prospective Study Sanjay Rastogi, MDS,* Mancy Modi, MDS,† and
Brijesh Sathian, MSc‡
Purpose: The aims and objectives of this study were to evaluate the efficacy of collagen membrane asa biodegradable wound dressing material for surgical defects of the oral mucosa.
Materials and Methods: Sixty healthy adult patients were included in the study. Purified bovinereconstituted collagen with a dimension of 10 10 cm and 0.6 mm thickness was used. This study wasconfined to secondary defects of the oral mucosa, which occur after excision of premalignant lesions andother conditions, such as benign lesions, reactive proliferations, and incisional biopsy wounds. Only
those lesions that were sufficiently large and could not be closed primarily were included in the study.
Results: The results were evaluated on the day of surgery and in the postoperative period. Theusefulness of collagen membrane as an intraoral temporary wound dressing material to promotehemostasis, relieve pain, induce granulation, and assist in rapid epithelialization at the wound site andprevent infection, contracture, scarring, donor-site morbidity, and rejection of graft was evaluated; andfinally, the efficacy of collagen membrane was tested by use of
2 test and P less than .001, which is a
statistically and clinically significant value.
Conclusion: In this study of short duration and small sample, the nature of collagen membrane was
Wounds left uncovered are prone to infection, con-traction, and scarring with other clinical complica-tions. Raw wounds in the oral cavity behave similarly;a need therefore arises to use a biologic cover toprevent these complications.
Free split-skin graft and free mucosal graft have
been used to cover raw wounds in the oral cavity. Theuse of these grafts required a separate surgical proce-
dure with associated technical difficulties. The color and texture of skin do not conform totally to the oralcavity. Donor sites for mucous graft are limited, andthere is always morbidity associated with donor-sitehealing. The oral environment and its constant move-ments are impediments to graft acceptance.
The tolerance of xenogenous collagen by tissue and
its successful use as a temporary cover for burns haveprompted this clinical study using xenogenous, cross-linked collagen sheet as a cover for wounds in the oralcavity. These raw areas were the result of excision of premalignant lesions and were too large to be closedprimarily.12-19
The aims and objectives of the study were based onclinical parameters. The intentions were to make thetechnique as simple as possible, to treat patients un-
der local anesthesia whenever possible, and to deter-mine whether a xenogenous collagen sheet was asuitable dressing material for oral wounds. This study reflects the usefulness of collagen membrane dressingover the surgical defects of oral mucosa, which wouldotherwise require other means to close the defects. Italso discusses the qualitative properties of collagenmembrane, which were neglected over the past 25
years.
Materials and Methods
After approval of the protocol by the institutionalreview board, 60 consenting, healthy adult patients
who were free of any systemic disease were enrolledin the study.
The collagen used in this study is a purified bovine
“serosa” reconstituted collagen. Purified collagen re-fers to collagen that is free from other componentsnormally associated with it in its native state. Recon-stituted collagen refers to collagen that has beenreassembled into individual triple-helical molecules
with or without their telopeptide extensions, broughtinto solution, and then regrouped into the desiredform. This reconstituted collagen is cross-linked with tanning agents such as glutaraldehyde or chromiumsulfate so that its tensile strength is improved, it be-
comes insoluble, its rate of resorption is sloweddown, and its antigenicity is markedly lowered.
Collagen membrane comes in varying dimensionsof 10 10 cm, 10 25 cm, and 25 25 cm, and itsthickness is 0.6 mm. It is sterilized by ethylene oxideand is marketed in vial format containing isopropylalcohol and water as the preservative media.
Relevant history was taken from the patients, andcareful clinical examinations were performed. Oral
prophylaxis was given before the study was under-taken. The sample size of this study was 60 patients.Both male and female patients were included. Patientsranging in age between 30 and 70 years were in-cluded in the study. This study was confined to sec-ondary defects of the oral mucosa, which occur after
excision of premalignant lesions and other condi-tions, such as benign lesions, reactive proliferations,
FIGURE 1. Size of defect, which cannot be closed primarily.
Rastogi, Modi, and Sathian. Collagen Membrane as Wound Dress- ing Material. J Oral Maxillofac Surg 2009.
FIGURE 2. Immediate stabilization of collagen graft withsutures.
Rastog i, Modi, and Sathi an. Collagen Membra ne as Wound Dressing Material. J Oral Maxil lofac Surg 2009.
and incisional biopsy wounds. Only those lesions that
were sufficiently large and could not be closed pri-marily were included in the study ( Fig 1 ).
The collagen membrane was stabilized by use of No. 3 silk sutures at the periphery of the defect and by use of a few quilted sutures in the center of themembrane over the defect ( Fig 2 ). No pressure dress-
ing was used. None of the patients required antibioticcoverage.
The results were evaluated on the day of surgery
and in the postoperative period.On the day of surgery, the following parameters
were considered:
● Conformability of the collagen sheet was as-sessed (ie, suppleness, resiliency, and dressingability to mimic oral wound and surroundingnormal tissue). Usually, this reflects the handlingproperties of the membrane.
● Hemostasis by the membrane was assessed 1hour and 1 day postoperatively. It was consid-ered to be good when the bleeding stopped
within 5 minutes, fair when it was achieved after a more prolonged period, and poor when inter-
vention was required to stop bleeding ( Fig 3 ).
In the postoperative period, the following parame-ters were considered:
● Pain, being subjective, was categorized based onthe patient’s own words as good (none to mild),
fair (moderate), or poor (severe). It was recordedon day 3 after the procedure when the patient was no longer taking analgesic medications.
● Adherence was based on the ability of the colla-gen to adhere to the wound after irrigation of the
area with sterile saline solution contained in a10-mL syringe. This was recorded after 5 days
when the sutures were removed. It was recordedto be present or absent ( Fig 4 ). This property
should be measured independently (not includedin the criteria given by Bessho and Murakami13 ).
● The presence of granulation tissues was noted atthe end of 2 weeks and rated as good (entire
wound), fair (nearly the entire wound), or poor (inadequate).● The mean day on which collagen lysis (biode-
gradability) was achieved was recorded.
● Epithelialization was noted at the end of themonth and rated as good (entire wound), fair
(nearly the entire wound), or poor (inadequate)( Figs 5, 6 ).
● Contracture of the wound site at the end of 3months was noted and rated as good ( 25%), fair ( 50%), or poor (severe [ie, 50%]) ( Figs 7, 8 );this was usually measured by the amount of mouth opening preoperatively and postopera-
tively.
For all patients at the end of epithelialization, cyto-logic smears were taken from the wound site so as toshow the presence of normal cells and thus confirmthe biocompatibility of the material.
The criteria for judgment of collagen dressing mem-brane with respect to the results obtained are basedon the scoring pattern that was used by Bessho andMurakami.13
The criteria for judgment were hemostatic effects,
pain relief, granulation, epithelialization, and contrac-
FIGURE 3. Good hemostasis achieved by collagen membrane.
Rastogi, Modi, and Sathian. Collagen Membrane as Wound Dress- ing Material. J Oral Maxillofac Surg 2009.
FIGURE 4. Good adherence after fifth day postoperatively. Rastogi, Modi, and Sathian. Collagen Membrane as Wound Dress- ing Material. J Oral Maxillofac Surg 2009.
ture of the wound. These were judged as good, fair, or poor, which were given scores of 2, 1, and 0, respec-tively.
Effectiveness was assessed by adding up the scores,and a value ranging from 8 to 10 was considered very
effective; 5 to 7, effective; and 0 to 4, ineffective.
Reactivity/allergenicity of the material was assessed
depending on the reactions elicited and was graded asnone when no reactions were seen, moderate whenfew reactions were noted but resolved without any intervention, and severe when intervention and treat-ment were required. These were given scores of 2, 1,and 0, respectively. Usually, this is measured based onthe severity of the allergic reaction evoked by themembrane because it behaves as xenograft.
Finally, usefulness of the material was assessed by
adding the scores for effectiveness and reactivity (ef-fectiveness plus reactivity) and was graded as very
FIGURE 5. Poor epithelialization without collagen graft at the endof 1 month postoperatively.
Rastogi, Modi, and Sathian. Collagen Membrane as Wound Dress- ing Material. J Oral Maxillofac Surg 2009.
FIGURE 6. Good epithelialization with collagen graft at the end of 1 month postoperatively.
Rastogi, Modi, and Sathian. Collagen Membrane as Wound Dress- ing Material. J Oral Maxillofac Surg 2009.
FIGURE 7. Adequate mouth opening preoperatively.
Rastogi, Modi, and Sathian. Collagen Membrane as Wound Dress- ing Material. J Oral Maxillofac Surg 2009.
FIGURE 8. Minimal change in mouth opening postoperatively(less contracture) after 3 months.
Rastogi, Modi, and Sathian. Collagen Membrane as Wound Dress- ing Material. J Oral Maxillofac Surg 2009.
useful (8-10 points), useful (5-7 points), or useless (0-4points).
Criteria for judgment of the membrane are pre-sented in Table 1.
Results
We selected 60 patients (both male and female)between the ages of 30 and 70 years for inclusion in
the study. Of the patients, 36 had lesions on thebuccal mucosa, 4 had lesions on the hard palate, 8had lesions over the anterior one third of the lateralborder of the tongue, and 12 had lesions over themaxillary alveolus.
All the patients were comfortable with intraoralgrafting of collagen. None complained about the sen-sation of foreign body or any odor. Allergy (systemicor local) to graft material was not seen in any of the
cases.
The collagen membrane showed good conformabil-
ity in 56 cases, whereas it was fair in 4 cases whenused on the buccal mucosa. Hemostasis was good
when used on the buccal mucosa of 40 patients andfair when used on the maxillary alveolus or lateralborder of the tongue in 20 patients.
Pain relief was good in 48 cases and fair to poor
in only 12 cases, where the collagen membranefailed to adhere to the underlying wound bed andgot sloughed off within the first 4 days after grafting.
In these 12 cases the membrane was used in dynamicareas of the oral cavity, where it was subjected toconstant movements and masticatory forces.
Granulation was good in all 60 cases showing de-fects of the buccal mucosa, lateral border of thetongue, palate, and maxillary alveolus.
Epithelialization was good in 56 cases and fair in 4.No contracture was noted in 36 patients, and slightcontracture was noted in 24.
In this study, 44 cases showed adherence and 16cases showed no adherence, and on average, theadhered collagen underwent lysis/sloughing off onthe seventh postoperative day.
The membrane was very effective in 36 patients,effective in 20, and ineffective in 4. The membrane
was very useful in 48 patients and useful in 12.Efficacy of collagen membrane was tested by use of
2 test and P less than .001, which is a statistically and
clinically significant value.
Discussion
Biomaterials derived from animal origin, especially those based on collagen, have been used in variousfields of surgery.1-3 The use of catgut is popular evento this day. Collagen is widely available with advancesin its method of extraction, purification, and cross-
linkage. It has been possible to use collagen in variousforms in recent times.4-6 Collagen in the form of laminates, sheets, fabrics, gels, powders, and spongesis available and has been used as dressing for ulcersand burns,15,20 as a hemostatic agent,21 and in tendongrafting in the induction of bone formation.3,11
In this study, bovine xenogenous collagen sheet
cross-linked with glutaraldehyde has been used as atemporary cover in excised lesions which could not
be closed primarily.Raw wounds of the oral cavity, like any other
wounds, heal by epithelialization and granulation.However, in the oral cavity the healing of raw woundspresents some special problems. The environment isalways moist with contamination from salivary secre-tion and food ingestion. This, compounded by poor oral hygiene and constant movements of the cheek and tongue and masticatory forces, may interfere with
graft adherence and acceptance. The risk of infection
Table 1. CRITERIA FOR JUDGMENT OF MEMBRANE
Score Definition
Hemostatic effectGood No bleedingFair Slight bleeding; no hemostasis
required
Poor Bleeding requiring hemostasisPain relief
Good None to mildFair Slight or moderatePoor Severe requiring analgesics
in the oral cavity is also quite high, which may result
in scarring and contraction. The oral cavity is highly sensitive to any residual scarring, which may undergoulceration and could be a constant source of irritationto patients wearing dentures.9-15
Wounds that are left uncovered are prone to infec-tion and scarring with attendant clinical problems. It
has been well documented that the incidence of in-fection and degree of contraction are considerably reduced when wounds are dressed with biologic ma-
terials rather than left exposed or dressed with non-biologic materials during healing.16-26 The fact thatgrafted wounds heal faster with fewer complicationsthan open wounds has been recognized in generalsurgery for almost a century.
Mucosal grafts25 offer the best solution becausethey come nearest to fulfilling the requirements of anideal graft material, which include the ability to re-place lost structures and the ability to induce the
formation of such tissues. There is, however, a limitedquantity of oral mucosa available for grafting, andthick mucosa taken from the cheek may result in scar formation, whereas a uniform thin graft removed with a microtome from the cheek is costly and compli-cated. There is always a degree of donor-site morbid-ity present.
Skin graft is the next solution, but such graft used inthe mouth will always retain the coloration of the skin
and never attain the texture or the resiliency of theoral mucosa. Also seen is the growth of adnexal struc-tures such as hair and sweat glands. In elderly persons
the skin is atrophic and inelastic, making it unsuit-able.26-35
All collagen membranes, with time, slowly under- went collagenolysis and were eventually sloughed off.The weakening of collagen membranes, compoundedby the oral environment and its movements, is the
most probable reason why adhered collagen mem-branes sloughed off. This lysis of collagen was theresult of inflammatory reaction. Collagen lysis can becontrolled by cross-linking, which also helps in re-ducing or suppressing antigenicity.7,8 Among thecross-linkage agents are aldehydes, chromium sulfate,and glutaraldehyde. As the collagen underwent lysis,
the collagen became translucent, allowing one tonote changes in granulation tissues. However, despite
its weakening by collagenolysis, collagen membranes were robust enough to resist masticatory forces for asufficient time, to allow granulation tissue to form,
which appeared uniformly and clinically healthy. Whenever there is an absence of adherence of themembrane to the wounds, pain will be noticed by thepatients. Adherence may therefore be an importantfactor for the action of collagen membrane in oral
wounds. Hemostasis by collagen is a result of its
character, which includes being a specific activator of
platelets, as well as their adhesion, aggregation, and
release reaction.21,26,27
Clinically, collagen is well tolerated with no ad- verse effects. Pain, edema, and infection were negli-gible, and wounds healed uneventfully. The appear-ance of the areas of operation was seen to be restoredto normal texture within about 1 month of grafting.
There is also a morbidity associated with donor-sitehealing; this reflects the effectiveness of collagenmembrane as a suitable graft material, whereas the
usefulness of the collagen graft in this study refers tothe material devoid of any allergic reaction despitebeing xenogenic with minimal morbidity to the pa-tient.
Dermis consists almost entirely of collagen, and anautogenous dermal graft has been shown to be suc-cessful as a tissue transplant to cover areas in themouth denuded of mucous membrane. The graftsbecame revascularized within the first week, and
there was a gradual epithelialization of the graftedarea resulting in a covering of normal mucous mem-brane. There is still donor-site morbidity, and thetechnique is complicated, costly, and unsuitable for elderly persons with loss of dermal tissue.
A bovine xenogenous collagen membrane is easily obtainable, and its successful use in burns and in theoral cavity has promoted this study of collagen mem-brane as an alternative to cover secondary wounds of
the oral cavity.5,24,25,28-34 With the collagen mem-brane, one does not need to perform a second oper-ation for obtaining graft nor would one encounter
morbidity and problems associated with donor-sitehealing. It was observed that the xenogenous colla-gen membrane had good conformability in the muco-sal lining—that is, it yielded a good clinical assess-ment with regard to its suppleness, resiliency, anddressing ability to mimic oral wound and surrounding
normal tissue to some extent. Of 60 patients, 44showed adherence of collagen membrane to the
wound ranging from the fifth to the tenth day. Theadherence of collagen membrane may be a result of fibrin collagen interaction but is most likely a result of fibrovascular ingrowth into collagen membrane.There was, however, some contraction, and moderate
scarring was noted in some patients in whom there was early loss of collagen membrane. In patients in
whom the collagen dressing was lost early, the site of grafting was in the maxillary alveolus, one of the mostfunctionally demanding areas. Excluding the possibil-ity of a rejection reaction in view of the clinical natureof the wound, the paucity of sutures holding thecollagen membrane to the mucosa was the most likely cause of failure of the membrane early in the wound-healing process.36 The most important methods for controlling scarring have been controlling infection
and minimizing growth of granulation tissue. Colla-
gen membrane appeared to fulfill these goals. Though
xenogenic, it showed good biocompatibility asproven by cytologic smear reports.37
Collagen membrane obtained xenogenously doesnot fulfill all the requirements of an ideal graft but isan alternative. Its application in the oral cavity is easy because of the simple chair-side application and good
tolerance of the membrane by oral tissues; it cantherefore be advocated as a temporary biologic dress-ing material in the oral cavity devoid of mucous mem-
brane. It is an alternative to autologous grafts rather than a replacement of other grafts used in the oralcavity and a satisfactory addition to the armamentar-ium of oral surgeons.
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