Written by Gregori M. Kurtzman, DDS Saturday, 01 October 2005 00:00
Surgery involves the creation of a wound, and proper closure of this wound is usually necessary to promote optimal healing. Suturing a wound positions and secures the surgical flaps to promote healing. Surgical sutures should hold the edges of a flap in apposition until the wound has healed sufficiently to withstand normal functional stresses and resist reopening.
|Table 1. General Guidelines for Suturing.|
Sutures are usually first placed distal to the last tooth, in each interproximal space, with suturing continued in a mesial direction.
First insert sutures through the more mobile tissue flap.
When space is restricted, use a one-half circle needle.
Only needle holders should be used to grasp suture needles, and the suture needle should be inserted and pulled through the issue in line with the curve of the needle.
Grab the suture needle in the center of the needle, never at its tip or near where the thread is swage to the needle.
When suturing multiple tissue levels, the goal is to suture periosteum to periosteum and gingival tissue to gingival tissue. (Note: The connective tissue and epithelial layers are together being referred to as gingival tissue.)
The needle should enter tissue at right angles to the tissue.
Do not place sutures closer than 2 mm to 3 mm from the flap edges to prevent tearing through the flap during suturing, or if postoperative swelling occurs.
When suturing, flaps should be approximated without blanching of the tissue. Pull the suture just tight enough to secure the flap in place without restricting the flap's blood supply.
In addition to proper technique, it is critical to select the appropriate type and size (diameter) of suture material to ensure that wound margins are free of tension, allowing healing by primary intention.1 Accurate apposition of surgical flaps contributes to patient comfort, hemostasis, reduction of wound size, and prevention of unnecessary bone resorption. If surgical wound edges are not properly approximated, hemostasis can be compromised and blood/serum may accumulate under the flap. This could result in a space between the underlying soft tissue and bone, thus delaying the healing process.2 In addition, when this occurs, healing will be by secondary intention, which can lead to irregular soft-tissue contours and the formation of scar tissue (Table 1).
Conventional intraoral surgical treatment concludes with closure of the soft tissue. Proper suturing precisely positions the mucosal and/or mucoperiosteal flaps as required by the surgical procedure being performed. Certain periodontal surgical procedures (eg, excisional new attachment procedure [ENAP] and modified Widman flap procedure) require the surgical flap margins to be positioned in their original location, whereas other periodontal procedures may require that the surgical flaps be placed apically, coronally, or laterally to their original position in order to achieve the surgical objectives.3
Suturing technique, the type and diameter of suture material (thread), the type of surgical needle, and the design of the surgical knot are essential factors in achieving optimal wound healing. Wound closure variables are different when suturing over hard versus soft tissue, or suturing over various types of materials placed into the surgical site to promote periodontal regeneration (eg, bone graft material or a membrane). The suture material and needle design will change accordingly.
This article will discuss suturing materials and certain useful suture knot designs, with a focus on periodontal surgical procedures.
|Figure 1. Comparison of a one-half circle needle (top) and three-eighths circle needle|
The surgical needle is composed of the point, the body, and the swaged (press-fit) end. Classification of suture needles is usually based on their curvature, radius, and shape. For intraoral use, three-eighths and one-half circle needles are most commonly used3,4 (Figure 1).
When using the three-eighths needle to close tissue in the oral cavity, the clinician rotates the needle on a central axis to pass it from the buccal surface to the lingual surface in one motion, whereas the one-half circle needle is traditionally used in more restricted areas (eg, buccal surface of maxillary molars and facial surface of maxillary and mandibular incisors). The one-half circle needle is routinely used for periosteal and mucogingival surgery.1-4
|Figure 2. Conventional needle (left) and reverse-cutting needle|
Suture needles may also be classified as either conventional cutting or reverse cutting.5 In the oral cavity, reverse-cutting sutures should be used to prevent the suture material from tearing through the papillae or edges of the surgical flap (referred to as "cut out" ). Conventional su-ture needles are generally associated with cut out because the inside concave (inner) curvature is sharpened; as the needle is pulled through the tissue, it cuts the tissue. This is detrimental in dental surgery because the tears that are created will complicate healing. In contrast, the inner curvature of a reverse-cutting needle is smooth, with a third cutting edge located on the convex (outer) edge.4 Figure 2 illustrates the inner curvature of a reverse-cutting needle compared to a conventional needle. For suturing of mucoperiosteal flaps in the oral cavity, the three-eighths reverse-cutting needle with 3-0 or 4-0 thread diameters and the one-half reverse-cutting needle with thinner 5-0 or 6-0 thread diameters are commonly used combinations.
Tensile strength is an important quality when determining which suture material is appropriate for specific situations. Tissue biocompatibility and ease of handling, with a focus on minimal knot slippage, also influence which thread should be selected. The clinician should select the suture material and diameter based on the thickness of the tissue to be sutured and whether there is a need for flap tension.4
Therefore, selection of the suturing technique and material should be based on the goals of the surgical procedure and the physical/biologic characteristics of the suture material in relationship to the healing process. Adequate strength of the suture material will prevent breakage during suturing, and proper tying of the knot in consideration of the material being used will prevent untying or knot slippage. The clinician must also understand the nature of the suture material, the wound healing process, the biologic forces exerted on the healing wound (eg, muscle pulls and swelling), and the interaction of the suture and tissue. The suture must retain its strength until the tissues of the flaps regain sufficient strength to keep the wound edges together. In clinical situations where the tissues will not regain their preoperative strength, or tension is exerted on the surgical flaps, consideration should be given to using a suture material that retains long-term strength (up to 14 days) and resorbs in 21 to 28 days, such as conventional polyglycolic acid (PGA) suture material.2,4 A clinical example would be a resorbed anterior mandible that has muscle attachments close to the crestal ridge; when the flap margins are reapproximated there will be tension on the margins. Should a resorbable suture material be used that loses its tensile strength after a few days, the re-adhesion of the periosteum to the underlying bone will not have gained enough strength to overcome the muscle pull. Therefore, a longer-lasting suture material should be utilized until the flap has achieved sufficient reattachment to the bone.
Resorbable sutures lose tensile strength over a period of time from several days to several weeks, and the breakdown of the resorbable material should equal the healing rate of the tissue being coapted by the material. If a suture is to be placed in tissue that heals rapidly, a resorbable suture should be used that will lose its tensile strength at approximately the same rate as the tissue gains strength. The suture will be absorbed by the tissue, leaving no foreign material in the wound after healing. Examples are surgical gut or the rapidly resorbable PGA sutures (PGA-FA).1
Resorbable sutures re-sorb due to 2 mechanisms. Sutures of biological origin (eg, surgical gut, plain and chromic gut) are gradually digested by enzymes in the tissue, whereas resorbable sutures fabricated from synthetic materials such as polygycolic acid are hydrolyzed via the Kreb's cycle.2 Surgical gut suture material is made from animal protein (ie, gut), thus it can potentially induce an antigenic reaction.6 When used intraorally, this material loses most of its tensile strength in 24 to 48 hours; coating the material with a chromic compound extends resorption to 7 to 10 days, and extends significant tensile strength to 5 days.5
An additional consideration with regard to gut su-tures is that breakage of the material during the resorption process may occur too rapidly to maintain flap apposition, particularly if used in patients with a very low intraoral pH.4 Many physiological events can cause a decrease in intraoral pH, including disorders such as epigastric reflux, hiatal hernia, and bulimia. Sjogren's syndrome, chemotherapy, radiation therapy, and certain medications (eg, angiotensin-converting inhibitors, anti-psychotics, diuretics, antihypertensive agents, antipsoriasis medications, and steroid inhalers) can cause xerostomia and a low intraoral pH.2,7
Coaptation of tissue flaps requires a minimum of 5 days.5 Selection of a fast-absorbing PGA suture is indicated in clinical situations where there is a low intraoral pH (and surgical gut sutures are contraindicated). PGA-FA suture material is not affected by low intraoral pH; it is manufactured from synthetic polymers and is mainly degraded by hydrolysis in tissue fluids (via enzymes involved in the Kreb's cycle). This requires 7 to 10 days.1,2 This material has a higher tensile strength than surgical gut suture material, but its resorption rate is comparable to that of surgical gut sutures under normal intraoral physiologic conditions.1,2
Nonresorbable sutures are fabricated either from natural or synthetic materials. Silk has been the most widely used material for dental and many other types of surgery.8 Silk is easy to handle, is tied with a slipknot, and costs less than many other nonresorbable suture materials. However, silk sutures have certain disadvantages. Being nonresor-bable, silk sutures must be removed by the clinician, usually 1 week following surgery. The patient generally is not anesthetized for this suture removal. Further, being a multifilament thread, silk demonstrates a "wick effect," which pulls bacteria and fluids into the wound site.9 Therefore, silk is not the suture material of choice when foreign materials such as dental implants, bone grafts, or regenerative barriers are placed under a mucoperiosteal flap, or when infection of the surgical site is present at the time of surgery (ie, removal of a septic tooth).
Nonresorbable sutures that can be used in situations where silk is contraindicated include nylon, polyester, polyethylene, polypropylene, or expanded polytetrafluoroethylene (e-PTFE). Polyester sutures comprise multiple filaments of polyester polymer, which are braided into a single strand that possesses high tensile strength and does not weaken when moistened. A biologically inert, nonresorbable compound of proprietary composition4 is often used to coat these sutures to aid the suture in passing more easily through tissues. However, this coating allows the material to untie easily unless the suture is secured with a surgeon's knot.4 Nonresorbable e-PTFE suture material is a monofilament with high tensile strength, good handling properties, and good knot security. It is, however, expensive compared with other nonresorbable suture materials.1
|Table 2. Suture Thread Types Used in Dentistry.|
In addition to material composition, surgical threads are also classified by numbering from 1 to 10; higher numbers indicate thinner, more delicate thread.10 For example, in implant dentistry a 3-0 thread diameter is generally used to secure flaps when a mattress suturing technique is used, and a 4-0 thread is used closer to the flap edges to coapt tension-free flap edges. A 4-0 thread also is used to secure implant surgical flaps when interrupted sutures, horizontal or vertical mattress sutures (depending on where the tissue is positioned), and most continuous suture techniques are utilized. In periodontal plastic surgery procedures a 5-0 thread diameter is most often used to secure soft-tissue grafts and transpositional/sliding pedicle flaps. When securing most other periodontal mucoperiosteal flaps, 4-0 thread is used (Table 2).
|Figures 3a to 3c. Slipknot being tied.||3b.|
|3c.||Figures 4a to 4c. Surgeon's knot being tied.|
Tying surgical knots is a critical aspect of suturing. The appropriate surgical knot should be used for the specific suture material in order to ensure knot security. For example, a slip (granny) surgical knot, which allows the surgeon to tighten the suture toward the tissue without loosening or opening, could be used for e-PTFE, chromic gut, or plain gut suture material (Figures 3a to 3c). However, a surgeon's knot, which will remain where positioned, must be used with synthetic resorbable and nonresorbable suture materials to prevent untying of the knot4 (Figures 4a to 4c). The mode of manufacture of each specific suture thread determines the type of knot that is used.5
EXAMPLES OF USEFUL SUTURING TECHNIQUES
|Figure 5. A simple loop suture used to coapt flap margins.||Figure 6. The simple loop suture being tied to coapt the edges of the incision.|
Two suturing techniques can be used for the interrupted suture: the simple loop and the criss-cross (which is a modification of the horizontal mattress suture technique). In dental surgery, the simple loop (Figure 5) is used most commonly to coapt tension-free, mobile surgical flaps.4 Procedures where the simple loop is useful include surgery of edentulous ridge areas, to coapt vertical releasing incisions, for periosteal suturing, and to coapt flaps as part of certain periodontal surgical procedures (ie, modified Wid-man flap, some periodontal regeneration surgery, and some exploratory flap procedures). A simple loop is created by entering the buccal flap from the epithelial surface (position 1) and crossing under the periosteum to exit the epithelial surface of the lingual flap (position 2); a knot is tied toward the buccal (Figure 6). (Note: This example assumes a simple flap where all the soft tissue has been elevated off the bone, including the periosteum.)
|Figure 7. A criss-cross suture placed at an extraction site to close the margins and aid in retention of graft material placed in the socket.|
The criss-cross is similar to the simple loop on the buccal aspect; however, on the lingual aspect, the needle penetrates first through the epithelial surface of the lingual flap, thus interposing additional suture thread between the surgical flaps. The criss-cross technique is useful when suturing on the lingual aspect of the man-dibular molars, especially in a patient with an active gag reflex or a large tongue.4 A criss-cross suture is tied by entering the mesial buccal aspect (position 1) and exiting the distal buccal aspect (position 2); the suture is then crossed over the socket, enters the mesial lingual aspect (position 3), and exits the distal lingual aspect (position 4). The suture at the distal lingual (position 4) is tied to the free end at the mesial buccal (position 1), and the knot is positioned toward the buccal (Figure 7).
Interrupted sutures should be used only with tension-free mobile flaps and should have needle penetration ap-proximately 3 mm from the wound edges or at the base of an interdental papilla. For closing wounds with flaps free of tension, these interrupted suture techniques achieve similar results.
The mattress technique is a variation of the interrupted suture and is usually used in areas where tension-free flap closure cannot be accomplished.4 Mattress su-turing techniques generally are used to resist muscle pull, to evert the wound edges (which keeps epithelium away from underlying structures), and to adapt the tissue flaps tightly to underlying structures when a bone graft or regenerative membrane is used, or during dental implant surgery. A three-eighths reverse-cutting needle with a thicker thread diameter (3-0 or 4-0) is usually used with a mattress suture technique.1 Mattress sutures are usually left in place for 14 to 21 days before dissolution or removal.11
There are variations of the mattress suture technique referred to as the horizontal mattress and the apically or coronally repositioned vertical mattress.
|Figure 8. A horizontal mattress suture showing the sutures' position in relation to the mucogingival junction.||Figure 9. Horizontal mattress suture used to closely adapt nontension-free tissue around an implant abutment, coupled with simple loop sutures to coapt the tension-free flap margins created by the horizontal mattress suture.|
When performing a mattress suture, the needle penetration through the surgical flap should be approximately 8 mm away from the flap edge or just above the muco-gingival junction (in keratinized tissue; Figure 8). A horizontal mattress suture is placed by penetration of the needle at the mesial buccal (position 1) apical to the mucogingival junction and is then crossed under the flap to exit at the mesial lingual (position 2). The suture then penetrates the tissue at the distal lingual (position 3) and again crosses under the flap to exit at the distal buccal (position 4) apical to the mucogingival junction. The suture at the distal buccal (position 4) is tied to the free end at the mesial buccal (position 1; Figure 9).
|Figure 10. Sling suture used to reposition the buccal flap margin, independent of the position of the palatal/lingual tissues. The teeth are utilized to help hold the tissue in position.||Figure 11. Lingual view demonstrating the direction and position of the suture around the neck of the tooth.|
Another suture technique is the interrupted suspensory suture, commonly referred to as the sling suture. This technique is used when only 1 side (or 1 or more papillae of a flap) is independently repositioned to its original position or coronally repositioned. The sling suture technique is especially useful when performing coronally repositioned sliding flaps. When tying a sling suture, the needle enters the buccal flap papilla distally (position 1) and is carried lingually around the neck of the tooth or implant to penetrate the papilla mesially (position 2), exiting buccally. The suture is then looped back around the same tooth or implant lingually and is tied with the free end, positioning the knot buccally (Figures 10 and 11). With this technique, each suture includes the papilla on the mesial and distal aspects of every other tooth, using separate ties.
Another variation of the interrupted suture technique is called a continuous suture. Continuous sutures can be used to attach 2 surgical flap edges or to secure multiple interproximal papillae of one flap independently of the other flap. This technique offers the advantage of fewer individual suture ties; however, there are significant disadvantages associated with this technique. If one knot or loop breaks, the integrity of the entire surgical site will be compromised.12 For this reason, more control can be gained using individually placed interrupted, sling, criss-cross, or mattress sutures in lieu of placing one large continuous suture.
The introduction of different suture materials, and the availability of different suturing techniques designed for specific purposes, has eliminated some of the difficulties previously encountered during surgical closure. It is important for dentists to be knowledgeable about the various types of suturing materials that are available for optimal wound closure. The use of the appropriate suturing material and technique contributes to the success of access-type periodontal surgery (including regenerative procedures), dental implant procedures, periodontal plastic surgery (including microsurgery), exodontia, and excision of pathologic tissue.
1. Silverstein LH. Essential principles of dental suturing for the implant surgeon. Dent Implantol Update. 2005;16:1-7.
2. Silverstein LH. Suture selection for optimal flap closure and tissue healing. Perio-implant showcase. Pract Periodontics Aesthet Dent. 2005;16:2-3.
3. Cohen ES. Sutures and suturing. In: Atlas of Cosmetic Reconstructive Periodontal Surgery. 2nd ed. Philadelphia, Pa: Lea & Febiger; 1994:9-30.
4. Silverstein LH. Principles of Dental Suturing: The Complete Guide to Surgical Closure. Mahwah, NJ: Montage Media; 2000.
5. Wound Closure Manual. Somerville, NJ: Ethicon Inc; 1985:1-101.
6. Knot Tying Manual. Somerville, NJ: Ethicon, Inc; 1968.
7. Lilly GE, Salem JE, Armstrong JH, et al. Reaction of oral tissues to suture materials. Oral Surg Oral Med Oral Pathol. 1969;28:432-438.
8. Macht SD, Krizek TJ. Sutures and suturing—current concepts. J Oral Surg. 1978;36:710-712.
9. Manor A, Kaffe I. Unusual foreign body reaction to a braided silk suture: a case report. J Periodontol. 1982;53:86-88.
10. Meyer RD, Antonini CJ. A review of suture materials, part I. Compendium. 1989;10:260-265.
11. Mejias JE, Griffin TJ. The absorbable synthetic sutures. Compend Contin Educ Dent. 1983;4:567-572.
12. Hutchens LH. Periodontal suturing: a review of needles, materials and techniques. Postgrad Dent. 1995;2(4):1-15.
13. Silverstein LH, Kurtzman GM. A review of dental suturing for optimal soft-tissue management. Compend Contin Educ Dent. 2005;26:163-171.
Illustrations by David Kurtzman, DDS.
Dr. Silverstein is associate clinical professor of periodontics at the Medical College of Georgia in Augusta, Ga, and is author of the text Principles of Dental Suturing: A Complete Guide to Surgical Closure. He is in private practice in Mari-etta, Ga, and can be reached at (770) 952-5432.
Dr. Shatz is assistant clinical professor of periodontics at the Medical College of Georgia in Augusta, Ga, and is in private practice in Marietta, Ga. He can be reached at (770) 952-5432.
Dr. David Kurtzman is in private practice in Marietta, Ga. He can be reached at (770) 980-6336.
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