Braz Dent J (1997) 8(1): 21-25 ISSN 0103-6440
| Introduction | Material and Methods | Results | Discussion | Acknowledgments | References |
The use of monofilament nonabsorbable suture materials is not common in Dentistry. Although it is known that multifilament suture materials induce greater cellular reaction, most Dentists prefer to use cotton and silk. Rigidity and package memory are disadvantages of monofilament nonabsorbable suture materials. A new material, Polybutester (Novafil®), has been used successfully in Medicine but its use is not common in Dentistry. Seventy male and female Wistar rats were used to study the clinical response of skin and abdominal wall muscle to the use of Novafil® and nylon sutures. Under general anesthesia, standard wounds were created in the dorsum and abdomen of the animals and sutured with either Novafil® or nylon. The animals were sacrificed immediately, 12, 24, and 72 hours and at 4, 5 and 7 days to evaluate the clinical aspect of both wounds. Polybutester presented some advantages such as strength, lack of package memory, elasticity and flexibility which made suturing quicker and easier. Some subjects presented abdominal wound edema during the period and six animals developed infection of abdominal wounds within seven days. These initial findings show that Novafil® is easy to handle and would be better tolerated in the mouth than nylon resulting in less discomfort for the patient. Novafil®can be used safely on skin and mucosal wounds and, if necessary, it can be used in internal sutures because it irritates less than nylon.
Key Words: Polybutester, tissue teaction, advantages.
Although nonabsorbable monofilament suture materials present advantages regarding their tensile strength, resistance to contamination and biocompatibility with living tissues, they are difficult to handle especially during suturing and knotting because of their rigidity. All nonabsorbable suture materials induce cellular reactions. Silk and cotton produce the greatest reaction which is followed in descending order by nylon, polyester, polypropylene and steel (Peacock, 1984).
Polybutester is a polymer with unique characteristics. It is made of a copolymer composed of polyglycol and polybutylene terephthalate in a ratio of 84:16 yielding optimal performance characteristics. This composition results in a material which may have benefits for both patients and surgeons. Polybutester has perceptible stretch, considerably improved flexibility compared with nylon and polypropylene and improved knot security over nylon (Le Blanc and Russo, 1986).
The oral cavity is one site with peculiar characteristics which must be considered during surgery planning. Its anatomy, physiology and its potentially contaminated nature must be considered. Because of this, threaded silk and cotton are still largely used in oral surgery in Brazil. Although these suture materials are cheap and easy to handle because of their texture, their multifilament aspect could result in contamination of the wound and delay healing. It is known that threaded cotton greatly influences intraoral tissue repair producing extensive areas of severe inflammation and tends to retain residue. Silk sutures result in less inflammation (Okamoto et al., 1990).
The handling of nonabsorbable monofilament suture materials is difficult for many surgeons because of the stiffness of the material. Nylon is typical in this group and its use results in a mild suture reaction, and fibroblastic and capillary proliferation occurs earlier in the sutured area in comparison to other materials (Okamoto et al., 1990). A previous study (Rodeheaver et al., 1987) has shown that NovafilÒ sutures presented new characteristics compared to monofilament nylon and polypropylene sutures. Its passive expansion was best observed under low tension. Under greater tension, the material behaved similarly to nylon. Excellent elasticity was also observed and is clinically important. Edema is one of the features of the early phases of wound healing, and results in an increased volume of the injured tissue. The use of rigid suture materials such as nylon would result in additional trauma for the tissue. However, due to its elasticity, NovafilÒ would improve the situation reducing trauma.
The handling of NovafilÒ was also considered to be better when compared to other suture materials. Rodeheaver et al. (1987) demonstrated that NovafilÒ is twice as flexible as nylon and polypropylene. A higher level of rigidity was observed in nylon in agreement with the findings of Nilsson (1981) and Bang and Mustafa (1989). Although sutures performed with NovafilÒ may slightly distort, they are more resistant to distortion than nylon sutures (Rodeheaver et al., 1987).
The animals were kept in groups of three in acrylic cages with shredded paper in an open air system at room temperature (28°C). The relative humidity was not regulated and the animals were kept in natural light, fed a standard laboratory pellet diet (Labina, Purina, São Paulo, Brazil) with ad libitum untreated drinking water. The animals were housed at the Núcleo de Cirurgia Experimental da UFPE where the surgical procedures were carried out.
The rats were anesthetized by intraperitoneal injection of ketamine (Ketalar, Aché, Guarulhos, SP, Brazil) and xylazine (Rompum, Bayer, Porto Alegre, Brazil), diluted in a ratio of 1:1 and given in a dose of 0.1 ml/100 mg.
The animals were divided into two main groups of 35 animals each. Five animals were allocated to each of seven sub-groups according to harvest time. Under general anesthesia, both the dorsum and abdomen were shaved and cleaned. Standard 5 cm wounds were created in the dorsum of the rat down to the parniculum carnosum. The wounds were then sutured either with NovafilÒ or 3.0 nylon. A 5 cm incision was made on the abdomen and the abdominal cavity was exposed. The muscle of the abdominal wall was then sutured with either NovafilÒ or 5.0 nylon. Skin wounds were closed with either NovafilÒ or 3.0 nylon.
The animals were sacrificed with an overdose of ip thiopental (2.5 ml/100 g) at the following times: immediately, 12, 24, and 72 hours and at 4, 5 and 7 days post-operatively. The clinical aspect of both wounds was recorded. After harvesting, the specimens were kept in neutral buffered formalin for 24 h and routinely processed with paraffin wax to be used for further histological assessment.
In the NovafilÒ group, there was no complication up to five days post-operatively and the sutures were mostly tight. Interestingly, a fibrosis-like tissue could be observed in seven of the abdominal wounds from day three. Edema was observed in two animals and in one of them signs of infection were observed at day 7.
It is clear that the objective of suturing is to place various layers of tissues in close contact so that a minimal quantity of new connective tissue will be required to restore the structural integrity of the tissue in the shortest possible time.
Polybutester presents some advantages for use in the mouth, amongst them permanence, strength, lack of package memory, elasticity and flexibility. These are in agreement with the findings of Bernstein (1988) who reported that NovafilÒ is handled with great ease because of its flexibility and lack of memory. It is also important to note that this material does not tend to maintain its package shape.
Our results agreed with previous reports regarding the easy handling of NovafilÒ compared to nylon and its improved elasticity which makes suturing quicker and easier (Bernstein, 1988). Because NovafilÒ is less rigid then nylon it will probably be best tolerated in the mouth of patients who very often complain of local discomfort and the appearance of mechanically induced aphata when rigid suture materials are used.
We found that only 10% of the subjects (N = 70), five (14.3%, N = 35) of the nylon group and two (5.7%, N = 35) of the NovafilÒ group presented edema during the experimental period and that this was observed only in abdominal wounds. This complication can be either a result of surgical trauma of a highly susceptible area or an increased tissue response to a local irritant such as the suture material. The latter seems to be the most probable factor as tissue edema is a typical feature of early stages of healing in all wounds (Pinheiro, 1993).
Increased tissue volume immediately after surgery is a direct result of surgical trauma and tissue manipulation during surgical procedures. Edematous tissues are expanded and the use of any suture material will surely close the wound at this stage. However, with the resolution of the edema, the injured tissues will return to their regular volume. With the reduction of tissue volume, most of the available suture materials will become loose and additionally may irritate adjacent tissues. These aspects would result in creeping which is a tendency of a suture to stretch under constant tension. Elongated sutures will no longer maintain approximation of the edges. In nylon sutures this is particularly observed because of its greater rigidity. We found that NovafilÒ sutures were also efficient in closing both wounds and initially very similar to nylon. However, because of its elasticity, the NovafilÒ stitches expanded passively in a similar extent to tissue edema. This is particularly important in cases in which post-operative edema is expected to be greater and in which tight stitches may further induce mechanical tissue damage because it will not expand at the same rate. Interestingly, we observed that with the reduction of tissue edema, NovafilÒ sutures retracted progressively to the new position keeping the wound well closed up to the end of the experimental period, in accordance with previous studies (Bernstein, 1988; Rodeheaver et al., 1986; Trimbos et al., 1993) which also found that polybutester sutures resist creep.
One interesting finding was that observed in the group three days after wounds. A fibrosis-like tissue involving the suture could be observed in seven of the abdominal wounds. Such tissue was not observed in any nylon-sutured wound at any time. The reason for this could be better explained later when we analyze the histological aspects. However, the presence of this tissue may represent a minor potential for irritation of the NovafilÒ suture which resulted in a quicker response compared to nylon sutures which seem to irritate tissue longer.
Six (8.6%, N = 70) animals of both groups presented signs of infection of muscular abdominal wounds within seven days after surgery, five (14. 3%, N = 35) belonged to the nylon group and one (2.8%, N = 35) belonged to the NovafilÒ group. The reason for the appearance of infection later is difficult to explain because the skin incisions in both the dorsum and the abdomen did not show any sign of infection during the experimental period. It is possible that contamination occurred during surgery. However, there is no explanation, at the moment, why nylon sutures became infected more frequently than NovafilÒ sutures.
These initial clinical results suggest that the handling of these new materials is easier and that NovafilÒ would be better tolerated in the mouth than nylon suture materials resulting in less discomfort for patients. NovafilÒ can be used safely on skin and mucosal wounds and, if necessary, it can be used in internal sutures because it would probably irritate less than nylon.
Bernstein G: Polybutester suture. J Dermatol Surg Oncol 14: 615-616, 1988
LeBlanc KA, Russo VR: Clinical experience with Gore-Tex suture. J La State Med Soc 138: 39-45, 1986
Nilsson T: Mechanical properties of Prolene, Ethillon and surgical steel loops. Scand J Plast Rec Surg 15: 111-115, 1981
Okamoto T, Gabrielli MFR, Gabrielli MAC: Influence of different types of nonresorbable suture material on the healing of extraction wounds - a histological study in rats. J Nikkon Univ Sch Dent 32: 104-115, 1990
Peacock EE: Wound Repair. 3rd edn. Philadelphia, 148-157, 1984
Pinheiro ALB: Comparison of tissue damage and healing in scalpel and CO2 laser mucosal wounds. PhD Thesis, University of Birmingham, 1993
Rodeheaver GT, Nesbit WS, Edlich RF: Novafil: a dynamic suture for wound closure. Ann Surg 204: 193-199, 1986
Rodeheaver GT, Borzelleca DC, Thacker JG, Edlich RF: Unique performance characteristics of Novafil. Surg Gyn Obst 164: 230-236, 1987
Trimbos JB, Smeets M, Verdel M, Hermans J: Cosmetic result of lower midline laparotomy wounds: Polybutester and nylon skin sutures in a randomized clinical trial. Obst Gynecol 3: 390-393, 1993
Correspondence: Prof. Antonio Pinheiro, Departamento de Cirurgia e Traumatologia Buco-Maxilo-Facial, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235, Cidade Universitária, 50670-420 Recife, PE, Brasil.
Accepted June 10, 1996
Electronic publication: September, 1997