Dr. Sarvesh B Urolagin, Dr. Tejraj P Kale Dr. Shankargouda Patil
There is always hesitation by the dental surgeon to carry out any surgical procedure either because of fear of excessive bleeding or damage to the vital structures or complications related to surgery and anaesthesia. One should have adequate knowledge of regional anatomy and plan of placing an incision. Correct management of the soft tissues during surgical procedure is of paramount importance to enable rapid and uncomplicated healing. A surgical incision will heal by primary intention, but if tissue is torn as a result of poor flap design or handling, then healing will be delayed. This article explains the management of soft tissues hoping to boost up confidence of handling surgical procedures.
The term ‘flap’ indicates a section of soft tissue that is outlined by a surgical incision, carries its own blood supply, allows surgical access to underlying tissues, can be replaced as required in its original position, maintained with sutures and is expected to heal. In order to design a mucoperiosteal flap successfully for oral surgery there are number of points that must be considered:
- Broad base
- Adequate size
- Anatomical consideration
- Margins on sound bone
- Relieving incisions
Healing of flap with adequate blood supply is rarely a matter of concern because of rich vascularity in the head and neck region. The base of the flap should be broader than the free edge to ensure that all areas contained within the flap have a source of uninterrupted blood supply. If this is not adhered to, then areas within the flap, or entire flap itself can undergo ischemic necrosis. Enough width of the base also adds to adequate access to the operating field.
| Figure 1. Base of the flap should be broad to ensure adequate blood supply to the free edge. Correct (green) and incorrect (red) flap design.
A flap is raised to gain access to underlying hard tissue. In order to complete the procedure efficiently, the flap must be large enough to allow the surgeon to visualize the tooth in question and adjacent teeth fully. Small flap causes difficulty for the surgeon and tension on the flap, resulting in excessive tissue trauma. Such a wound will heal slowly than if it had been incised with a surgical blade. A general rule for the size of a flap is to start one tooth behind the tooth to be operated and continue to one tooth in front.
Anatomical structures that must be taken into consideration when designing a flap are explained according to the area of flap placement.
There are three main nerves which should be considered when planning surgery in mandible:
On leaving the safety of its bony canal, the inferior alveolar nerve exits as the mental nerve. The mental nerve emerges via the mental foramen, which is situated either in the interdental space between the apices of the lower first and second premolar teeth, or a position apical to the second premolar. There are some age and racial related differences in its location. Radiographic image of the mental foramen prior to surgery to ensure the position is imperative. When making a flap in this region the anterior relieving incision should be placed mesial to the first premolar. The nerve lies within the buccal soft tissues and therefore will be retracted intact with the flap. Care must be taken during the procedure not to cause crush injury to the nerve by excessive pressure with the flap retractor.
| Figure 2. The dashed line passes too close to the mental nerve. Green line is the correct incision.
In the third molar region, it is only covered by a thin layer of mucous membrane. When making incisions in the posterior mandible, especially in this region, all incisions should be made buccally to prevent severing the nerve. Lingual flap can be kept intact during third molar surgery to prevent lingual nerve injury.
| Figure 3. Notice the close proximity of lingual nerve to third molar tooth. Green line is the correct placement of incision to gain access.
Inferior alveolar nerve
This nerve is encased within the mandibular canal in the body of the mandible. Therefore there is no risk to this nerve when considering purely the soft tissue management of the surgical process. This nerve is of great importance during the planning of surgical removal of teeth. While removing root pieces in the apical third of molar teeth care should be taken not to put excessive force. When roots are close to the canal in case of third molar, sectioning of the tooth is given more importance than forced removal with the elevator.
The greater palatine nerve and vessels
The hard palate is innervated by the greater palatine nerve, with which the greater palatine vessels run. The vast majority of palatal surgeries are done using an envelope flap around the necks of the teeth, the neurovascular bundle are reflected with the flap without much difficulty. If vertical relieving incision is required for access, then this must be done at the anterior end of the flap, as posterior relieving incision will severe the greater palatine vessel causing brisk bleeding.
This nerve emerges on the hard palate through the incisive fossa to supply the anterior palatal mucosa. If the anterior part of the palate needs to be reflected, then this neurovascular bundle can be safely cut at the level of the foramen. The resultant bleeding can be easily controlled with pressure and the nerve can regenerate. However, as the area of mucosa supplied by this nerve is minimal, if any temporary or permanent anaesthesia is caused, it is barely perceptible.
| Figure 4. Diagram showing palatal nerves and vessels. Green line is the placement of crevicular incision.
Margins on sound bone
This rule does not mean that the incision should be made on to sound bone, but that they rest on sound bone once the surgery is complete. The surgeon should anticipate the approximate amount of bone that will need to be removed so that this can be taken into account when designing the flap. If the incision does not lie on a sound bone, then this will result in delayed healing and a higher chance of wound breakdown.
| Figure 5. Red line is in close proximity to the mental neurovascular bundle and also it will lie in the defect after removing the bone. Green line shows the correct placement of incision in the anterior region.
When considering incisions, the surgeon must decide if a relieving incision is required. This decision will depend on the amount of reflection required to gain adequate access to surgical field. Unless the surgery is to be quite superficial and an envelope flap is viable, then a relieving incision will be required.
There remains controversy as to the angulation that should follow. Tradition dictates the incision should be made obliquely, so the base of the flap is broader than the free edge, to ensure adequate bold supply. However, there is some evidence to show that gingival blood vessels run vertically.3,4 This suggests that the relieving incision should be made vertically to minimize trauma to the vessels.
| Figure 6. Vertical releasing incision is parallel to microvasculature.
The incision should be a smooth curve allowing good apposition of the edges and should also not divide interdental papillae. This aids flap replacement in the original position because, once divided, it is very difficult to get adequate apposition of the wound edges. It is also important not to cross bony prominences like canine prominence, if done flap will be under tension, which could lead to dehiscence.
There are various different mucoperiosteal flaps available to use for minor oral surgery. We will discuss three commonly used flaps.
Envelope flap (Sulcular flap)
This flap can be used for removal of superficial retained roots or bony prominences, and removal of teeth which require minimal bony removal. Almost all surgical procedures in the palate are done using this type of access as the soft tissue is displaced away from a concave surface and good access is therefore achieved. The same can be used in the lingual flap. The incision is made along the gingival crevice and extended anteriorly to posteriorly beyond the surgical site. If the patient is edentulous, then the incision is made along the crest of the ridge.
Triangular flap (Two sided flap)
This flap is used if greater reflection than the envelope flap provides, is required in an apical direction. A relieving incision is made at either the anterior or posterior edge of the envelope flap although; incision is usually made anteriorly for increased vision and access. When aesthetics are important like in anterior maxilla, a relieving incision should be made away from the midline to prevent any scarring being visible. This flap is most commonly used for removal of lower third molar. The distal incision extends from distobuccal cusp of the second molar (or third molar if partially erupted) up the external oblique ridge. The anterior relieving incision starts from same point or anterior to the distal papilla of the second molar and curves antero-inferiorly into the buccal sulcus. For deep impactions requiring extensive bone removal, the incision can extend to the distal aspect of the first molar.
Trapezoidal flap (Three sided flap)
Essentially, this flap is an envelope flap with relieving incision anteriorly and posteriorly, which allows very good access and reflection, and is therefore useful for surgical endodontics.
| Figure 7. Red line is for an envelope flap, blue for triangular or two sided flap and green for three sided flap.
The best management of soft tissues is very important during surgery and care must be taken not to put the patient for unnecessary harm. Orofacial region in the whole body is very sensitive and should carry out the procedure with utmost care. Gentle and respectful handling of the tissues is essential not only to have clean surgical field during the procedure but also to have minimal postoperative inflammation and uneventful healing. There are basic steps for any surgery and best management of tissues will be discussed.
- Flap reflection and protection
- Suture placement and removal
Flap design and surgical exposure should be planned before initial incision is made. A number 15 blade is used in a number 3 scalpel handle which should be held in pen grip. When making an incision, the operator should start posteriorly, working towards the front of the flap. For sulcular incisions, the blade is placed vertically into the gingival sulcus, following the shape of the tooth, keeping the sharp edge of the blade against the tooth surface to prevent unnecessary damage to gingiva. The interdental papilla should be preserved, this allows the flap to be easily repositioned to its original position and therefore provides good aesthetics.
| Figure 8. A number 15 BP blade is used in a number 3 BP handle held in pen grasp.
When making the relieving incision, the operator’s supporting hand should retract the cheek to exert tension on the mucosa to ensure the blade runs cleanly through the tissues. Once the tissue has been tensed, the incision is made in a single smooth stroke slightly curving forward downward and stopping at the level of the apices of the teeth. Incisions should be made at right angles to the tissue and must be straight down to bone, to allow easy reflection of the flap without any soft tissue left still attached to the underlying perioteum and bone. Replacing back flap in its original position is vital for rapid healing.
Flap reflection and protection
Flap reflection begins with the papillae. These should be turned out and separated from the underlying bone with the small triangular end of the Molt’s no. 9 periosteal elevator, keeping the smooth surface towards soft tissue. Firm controlled small push will separate the papillae atraumatically. There are number of periosteal elevators which are acceptable to reflect the flap like Howarth’s, Molt’s no.9, Hu-Friedy 24G elevator. The flap can be elevated in two ways; after reflecting the papillae, the attached gingival is separated keeping the sharp edge of the periosteal elevator firmly on the bone, this is often hardest part of the flap reflection, and care must be taken to ensure the soft tissues are not put under undue tension. Then instrument is pushed downwards and backwards to complete the reflection. Another technique is to insert the periosteal elevator into the base of the relieving incision keeping firmly on the bone, to prevent trauma to the soft tissue, and then push upwards and backwards to raise the remaining flap. Independent of the type of the flap, the important factor is to ensure that the flap is retracted full thickness, ie mucosa and periosteum are reflected together. The periosteum plays an important role in healing of the flap, so minimizing damage to this tissue, and replacing it back to its original position is vital for rapid healing.
| Figure 9. Elevation starts at the middle portion of the vertical incision.
Once the flap is reflected it must be retracted out of the way of the surgical site. The flap must not be put under tension as tearing of the flap may occur. This can be prevented by lengthening the flap if required. A number of retractors are available; Austin’s, Minnesota, Lack’s tongue retractor or a medium sized right angle retractor are most commonly used. The chosen retractor is placed over the periosteal elevator onto the reflected area, and the periosteal elevator is removed. This technique allows the retractor to hold the flap back safely and, if placed correctly, the retractor should sit against bone underneath the periosteum, protecting the delicate tissue. Care must be taken not to trap tissue between the retractor and the bone, particularly in the mandibular premolar area, as mental nerve damage could result. While removing bone, position the retractor between the drill and soft tissue to prevent damage to the flap from the bur.
| Figure 10. Various retractors used to retract and support the flap. From top to bottom medium sized right angle retractor, Lack’s tongue retractor and Austin’s retractor.
Once the tooth has been removed, make sure that the whole area, including that underneath the flap is thoroughly debrided and irrigated to remove any debris. This step helps to hasten the wound healing, reduces the inflammation and postoperative swelling. Bony and soft tissue haemostasis should be achieved before repositioning the flap. Flap is replaced back to its original position by using the interdental papillae as a guide. The flap can also be replaced to a new position like in buccal advancement flap and apically repositioned flap.
Suturing and suture removal
Sutures aim to
- Approximate wound edges to maximize healing by primary intention
- To cover bone as much as possible
- Hold the flap in desired position
- To aid in soft tissue haemostasis
- Hold the needle holder with the thumb and ring finger. The middle finger and the index finger help to give detailed control.
- Hold the needle in the needle holder approximately 2mm from where the suture material joins the needle.
- Ideally, start from the free tissue, ie the flap, and work towards the fixed tissue.
- Steady the tissue with toothed tissue holding forceps. Take a bite of tissue (approximately 2mm) making sure that the needle enters the tissue at right angle. Once the tip of the needle is through the tissue, hold the tip with the tissue forceps before opening the needle holder. Then pick up the needle with needle holder and pull through following the curve of the needle with wrist.
- Take second bite in the same way. If this is a lingual bite then make sure not to take too much tissue within the bite, to protect the lingual nerve and also retract the tongue away with a tongue depressor.
- Hold the needle between finger and thumb of your non-dominant hand. Wind any excess suture around your remaining fingers. The needle holder should be in dominant hand.
- Loop the suture around the needle holders twice in a forward direction.
- Pick up the end of the suture and clamp the needle holders together. Slide the loops off the needle holders and tighten on the buccal side of the wound.
- Make a further loop in the opposite direction around the holders (backwards) and slide off in a similar manner.
- Finish with one loop forward and tighten to secure the knot.
- Cut the suture so that 2-3 mm remains.
Two types of suture material are commonly used for intraoral suturing. Absorbable type Vicryl, can be used which is easier to handle but can incite a greater inflammatory response. Vicryl rapide is recently available useful material for intraoral suturing. Silk is still popular, especially when the wound needs to be firmly sutured, eg oro-antral communication closure. The sizes and strengths for all suture materials are standardized; the more zeros in the number, the smaller the size of the strand. 00000 is referred to as 5-0, which is smaller than a size of 4-0. For oral mucosal suturing usually size 3-0 material is used. Cutting, reverse cutting and round body needles are available. A cutting needle has a sharp edge on the inner curve of the needle that is directed towards the wound edge. Cutting needle is easier to pass through the tissues but carries an increased risk of tearing. A reverse cutting needle has a sharp edge on the outer curve of the needle that is directed away from the wound edge, which reduces the risk of the suture pulling through the tissue.
By far the most common type of suture is the simple interrupted. The first suture should always be placed at the most anterior papillae of the flap or the middle papilla if an envelope flap. This makes sure that the rest of the flap lies correctly.
| Figure 11. Correct way of holding the needle holder for suturing.
| Figure 12. Diagram shows placing interrupted suture.
Intraoral sutures should be left for 5-7 days. Removing sutures is a very simple procedure; however, it is often done incorrectly. To remove, pick up the knot of the suture with tweezers. In doing this the part of the suture that has been within the mucosa, and therefore clean, cut the suture at this point then pull the suture free. This technique prevents dragging the dirty part of the suture through the wound.
A general dentist routinely encounters fracture of tooth while extraction, in his practise. Usually many of them try invariably to extract a fractured tooth by closed method, resulting in maceration of flaps in turn leading to delayed healing also injuring the adjacent vital structures. Open extraction helps in saving time, less tissue injury and a faster uneventful healing. Incisions if placed, as described above would prevent any complications such as avascular necrosis, wound dehiscence, dry sockets and injury to vital structures. Also suturing plays a major role, hastens and promotes healing. Abiding with the basic principles and a sound knowledge of facial anatomy are of paramount importance for a successful dental practise.
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