Surgical removal of impacted third molar

Surgical principles

Preparation for surgery
Patient management
Speed and efficiency
Surgical access
Osteotomy and sectioning
Surgical site debridement
Soft tissue management
Postoperative care

Preparation for surgery

Determine surgical difficulty

Angulation of the impacted tooth	Mesioangular impaction is the least difficult to remove Vertical impaction and horizontal impaction are intermediate in difficulty Distoangular impaction is the most difficult
Relationship to anterior border of ramus	If the length of the alveolar process anterior to the anterior border of the ramus is sufficient to allow tooth eruption, the tooth is generally less difficult to remove Teeth that are essentially buried in the ramus of the mandible are more difficult to remove
Depth of the impaction	Soft tissues and partial or complete bony impaction Full bony impactions are always more difficult to remove than are soft tissue impactions
Roots morphology	Length of the root Optimal time for the removal of an impacted tooth is when the root is one third to two thirds formed. When this is the case, the ends of the roots are blunt If the tooth is not removed during the formative stage and the entire length of the root develops, the possibility increases for abnormal root morphology and for fracture of the root tips during extraction or the root tips impeding root delivery If the root development is limited (i.e., less than one third complete), the tooth is often more difficult to remove because it tends to roll in its socket like a marble, which prevents routine elevation Fused or separate roots The fused, conical roots are more straightforward to remove than are widely separated roots Curvature of tooth roots Severely curved or dilacerated roots are more difficult to remove than are straight or slightly curved roots Direction of tooth root curvature During removal of a mesioangular impaction, roots that are curved gently in the distal direction (following along the pathway of extraction) can be removed without the force that can fracture the roots However, if the roots of a mesioangular impaction are straight or curved mesially, the roots commonly fracture if the tooth is not sectioned before being delivered Tooth width in mesiodistal direction compared to width of the tooth at the cervical line If the tooth root width is greater, the extraction will be more difficult. More bone must be removed, or the tooth should be sectioned before extraction Periodontal ligament space The wider the periodontal ligament space, typically the easier the tooth is to remove
Space around tooth	A large follicular sac around the crown of the tooth provides more room for access to the tooth, making it less difficult to extract than one with essentially no space around the crown of the tooth
Density of bone	Bone density is best determined by the patient’s age Patients who are 18 years of age or younger have bone densities favorable for tooth removal. The bone is less dense, is more likely to be pliable, and expands and bends somewhat, which allows the socket to be expanded by elevators or by luxation forces applied to the tooth itself. Additionally, the less dense bone is easier to cut with a dental bur and can be removed more rapidly compared with denser bone
Contact with mandibular second molar	Less likely to damage adjacent second molar if space exists between second molar and the impacted third molar
Relationship to inferior alveolar nerve	The availability of cone-beam CT scans makes preoperative assessment of the root and canal relationship easier to view, helping guide surgical decisions
Nature of overlying tissue	3 types of impactions : soft tissue, partial bony, full bony The soft tissue impaction is usually the easiest of the three extractions but can be complex, depending on factors discussed in the preceding sections The partial bony impaction occurs when the superficial portion of the tooth is covered by soft tissue, but at least a portion of the height of the contour of the tooth is below the level of the surrounding alveolar bone The complete bony impaction is an impacted tooth that is completely encased in bone, so that the tooth is visible when the surgeon reflects the soft tissue flap
Age of the patient	When impacted teeth are removed before age 20 years, the surgery is almost always less difficult to perform The roots are usually incompletely formed and thus less bone removal is required for tooth extraction Because the roots of the impacted teeth are incompletely formed, they are usually separated from the inferior alveolar nerve

Classification systems for mandibular third molar impactions

Angulation : angulation of the long axis of the impacted third molar with respect to the long axis of the adjacent second molar

Mesioangular impaction	The crown of the mesioangular-impacted tooth is tilted toward the second molar in a mesial direction
Horizontal impaction	When the long axis of the third molar is perpendicular to the second molar
Vertical impaction	The long axis of the impacted tooth runs parallel to the long axis of the second molar
Distoangular impaction	The long axis of the third molar is distally or posteriorly angled away from the second molar

Relationship to anterior border of ramus (Pell and Gregory classes 1,2 and 3)

Class 1	Mesiodistal diameter of the crown is completely anterior to the anterior border of the mandibular ramus
Class 2	The tooth is positioned posteriorly so that approximately one half is covered by the ramus, the relationship of the tooth with the ramus
Class 3	The tooth is located completely within the mandibular ramus

Relationship to the occlusal plane : Pell and Gregory A, B, and C classification

Class A	Occlusal surface of the impacted tooth is level or nearly level with the occlusal plane of the second molar
Class B	Impacted tooth with an occlusal surface between the occlusal plane and the cervical line of the second molar
Class C	Occlusal surface of the impacted tooth is below the cervical line of the second molar

All surfaces are sterile
Surgical team is scrubbed
Patient is premedicated and prepared for surgery well
All instruments are sterile
Equipments are ready for use
Completed informed consent

Asepsis	Classification of dental instruments Critical : Those used to penetrate soft tissue or bone, or enter into or contact the bloodstream or other normally sterile tissue. They should be sterilized after each use Semi-critical : Those that do not penetrate soft tissues or bone but contact mucous membranes or nonintact skin, such as mirrors, reusable impression trays, and amalgam condensers. These devices also should be sterilized after each use Noncritical : Those that come into contact only with intact skin such as external components of X‐ray heads, blood pressure cuffs, and pulse oximeters. May be reprocessed between patients by intermediate‐level or low‐level disinfection
Antibiotics	Indications for prophylactic antibiotics Medically compromised patients especially those with ASA score of 3 or more Antibiotic prophylaxis is not indicated for lower third molar surgery Antibiotic prophylaxis may be indicated for minor surgery with a high degree of difficulty in which the duration of the surgery is predicted to be long
Antiseptic mouthwash	Preoperative antiseptic mouthwash (e.g., chlorhexidine) has been shown to decrease intraoral bacterial counts and alveolar osteitis.
Pain medication	NSAIDS combined with acetaminophen are more effective in controlling acute pain than narcotics
Documentation	All documents, including medical history and consent forms, should be completed prior to seating the patient

Patient management

Factors to consider when determining if local anesthetic without sedation is appropriate

Patient anxiety : impacted lower third molar extraction is significantly more difficult in anxious patients
Difficult local anesthesia : patients who are “difficult to numb” may need sedation or general anesthesia
Difficult procedure : patients may become less cooperative during long procedures. These surgeries may require additional local anesthetic, sedation, or general anesthesia
Dentist proficiency

Speed and efficiency

Long surgical procedures result in increased complications and delayed healing
Instruments should be arranged in the order of use on the surgical table

Surgical access : as conservative as possible

Factors affecting surgical access and vision

Surgical site : third molars are located in the posterior portion of the mouth. Access requires a vertical releasing incision or a large envelope flap to gain access and vision
Mucosa : difficult to handle and usually requires a small needle and suture to close, alternatively a large envelope flap can be used to gain access
Saliva : watery saliva tends to increase the flow of blood, requiring constant suction to maintain good vision
Coronoid process : can press against the maxillary alveolus when the mouth is opened wide. This may make surgical access very difficult
Tongue : may actually cover the mandibular posterior teeth. A Weider retractor is recommended to retract the tongue and isolate the surgical site

Osteotomy and sectioning : allows access for instruments and elevation of the third molar

Surgical drills have several advantages over restorative handpieces when used to remove bone and section third molars:

efficient cutting
decreased heat
decreased vibration
rear exhaust

Surgical site debridement : can prevent infection and improve healing

The socket should be gently irrigated with sterile saline following the removal of the impacted third
A small surgical suction allows for close inspection of the surgical site and removal of small particles of bone and tooth
The socket walls should be gently curetted to remove loose bone, tooth remnants, and soft tissue
Any sharp bony edges around the socket should be smoothed using a bone file, #9 periosteal elevator, or rongeur
Soft tissue flaps accumulate debris from troughing and sectioning
Irrigation between the flap and lateral border of the mandible is required to flush out debris. Gentle irrigation of postextraction sockets is recommended. Aggressive irrigation of the extraction socket can impede healing and cause alveolar osteitis. The study demonstrated that the post-extraction socket bleeding is very important for proper uncomplicated socket healing. If it’s not washed away with irrigation solution at the end of extraction, the normal blood clot has a higher likelihood to form, and therefore, can potentially lead to an uncomplicated socket healing without development of alveolar osteitis
Irrigation is followed by close inspection and suctioning of the flap/bone interface to remove all debris

Soft tissue management

All flaps should have a broad base, which insures a good blood supply to the flap margins
The flap should be tension free and large enough to provide access to the surgical site. A tension-free flap prevents accidental tearing of delicate tissue

Postoperative care

Surgical sites should remain undisturbed for at least 24 hours
Rinsing, spitting, or drinking through a straw should be avoided
Patients should be cautioned to not chew food, brush their teeth, or touch the area of surgery for 24 hours
Patients should not be discharged until bleeding is controlled

Surgical techniques of removal of mandibular impacted third molars

Flap
Trough
Section
Split
Delivery
Debridement
Closure

Flap

The initial step in removing impacted teeth is to reflect a mucoperiosteal flap, which is adequate in size to permit access
The preferred incision for the removal of an impacted mandibular third molar is an envelope incision that extends from the mesial papilla of the mandibular first molar, around the necks of the teeth to the distobuccal line angle of the second molar, and then posteriorly to and laterally up the anterior border of the mandibular ramus
If greater access is required to remove a deeply impacted tooth, a release incision is done on the anterior aspect of the incision, creating a three-cornered flap
The envelope incision is usually associated with fewer complications and tends to heal more rapidly and with less pain than the three-cornered flap
The envelope flap is quicker to suture and heals better than the three cornered flap (envelope flap with a releasing incision)
However, if the surgeon requires greater access to the more apical areas of the tooth, which might stretch and tear the envelope flap, the surgeon should consider using a three-cornered flap
The buccal artery is sometimes encountered when creating the releasing incision, and this may be bothersome during the early portion of the surgery
The posterior extension of the incision must extend to the lateral aspect of the anterior border of the mandibular ramus. The incision should not continue posteriorly in a straight line because the mandibular ramus diverges laterally. If the incision were to be extended straight, the blade might damage the lingual nerve

Envelope flap

The initial incision for a mandibular envelope starts 1–1.5 cm distal to the second molar and ends near the central groove of the second molar
The incision starts on the buccal near the external oblique ridge and can be extended as needed for access
Do not place incisions directly distal to the second molar
Never place incisions or use instruments on the lingual of the surgical site, may cause lingual nerve paresthesia
Mandibular envelope flaps should end distal to the second premolar.
The papilla between first molar and second premolar is included in the flap

Incision

The scalpel blade stays on bone throughout the incision
The incision should be completed in one smooth stroke to create a flap with clean edges. This allows a full-thickness mucoperiosteal flap to be reflected
Must have a broad base if a releasing incision is used
The incision should be designed such that it can be closed over solid bone. This is achieved by extending the incision at least one tooth anterior to the surgical site when a vertical-releasing incision is used
The incision should avoid vital anatomic structures
Only a single releasing incision should be used
If the impacted third molar is deeply embedded in bone and requires more extensive bone removal, a releasing incision may be useful. The flap created by this incision can be reflected farther apically, without risk of tearing the tissue

Flap elevation

A #9 periosteal elevator is used to open the flap beginning at the anterior portion of the flap and moving posterior
The small end of the elevator is used to elevate the papilla between second premolar and first molar, followed by elevating the papilla between the first molar, second molar, and the tissue distal to the second molar
The flap is reflected laterally to expose the external oblique ridge
Should not reflect more than a few millimeters beyond the external oblique ridge because this results in increased morbidity and an increased number of complications after surgery
The flap will open easily once dissected past the mucogingival junction
The flap should be passive, mobile, and allow the placement of a Minnesota retractor in the pocket created between the lateral surface of the mandible and the flap periosteum
The retractor is placed on buccal shelf, just lateral to the external oblique ridge and it is stabilized by applying pressure toward the bone
This technique, when combined with a Weider retractor on the lingual, isolates the surgical site and improves access and visibility
Another unique characteristic of the envelope flap is the ability to extend and enlarge the flap as needed. This is not possible when releasing incisions are used

Trough

The tooth location is determined after assessing a panoramic X-ray and patient arch form
A buccal trough next to the impacted mandibular third molar creates space for elevators
The trough is completed using a surgical drill and bur
The bone on the occlusal, buccal, and cautiously on the distal aspects of the impacted tooth is removed down to the cervical line
Bone on the occlusal aspect of the tooth is removed first to expose the crown of the tooth
Then, cortical bone on the buccal aspect of the tooth is removed down to the cervical line
Next, the bur can be used to remove bone between the tooth and cortical bone in the cancellous area of bone. This provides access for elevators to gain purchase points and a pathway for delivery of the tooth
It is advisable not to remove any bone on the lingual aspect because of the likelihood of damage to the lingual nerve
The burs that are used to remove the bone overlying the impacted tooth vary with surgeons’ preferences. A large round bur such as a No. 8 is desirable because it is an end-cutting bur and can be used effectively for drilling with a pushing motion. The tip of a fissure bur such as a No. 703 bur does not cut well, but the edge rapidly removes bone and quickly sections teeth when used in a lateral direction
The amount of bone that must be removed varies with the depth of the impaction
The trough should be as deep possible without injuring the IAN
The trough allows for the placement of elevators and mobilization of the tooth
It should continue in a mesial direction to a point adjacent to the distal buccal line angle of the second molar. The mesial extension of the trough facilitates placement of instruments mesial to the impacted third molar
Bone surrounding the second molar is not removed
The triangular area mesial to mandibular third molar roots can be considered an IAN “safe zone”

The bur should hug the crown of the impacted third molar to create a narrow trough and preserve bone. The impacted tooth enamel will feel harder than the surrounding bone
The trough should always extend apically past the impacted third molar height of contour to prevent undercut

Section

Once the tooth has been sufficiently exposed, it is sectioned into appropriate pieces so that it can be delivered from the socket
Sectioning allows portions of the tooth to be removed separately with elevators through the opening provided by bone removal
The direction in which the impacted tooth is divided is dependent on the angulation of the impaction

Tooth sectioning is performed with a bur
Mandibular third molar sections should cut approximately 3/4 through the tooth, stopping short of the lingual plate, submandibular fossa, and lingual nerve. This prevents injury to the lingual cortical plate and reduces the possibility of damage to the lingual nerve
The section should be deeper on the buccal than on the lingual. This precaution will minimize injury to the lingual nerve
Buccolingual diameter of third molars is normally 9.5–10.0 mm
Crown length is normally 6.5–7.0 mm
In all cases of sectioning, the cut should be kept within the tooth structure to prevent damage to the lingual tissues or the inferior alveolar canal
A straight elevator is inserted into the slot made by the bur and rotated to split the tooth

Mesioangular impaction

Usually the least difficult to remove
After sufficient bone has been removed, the distal half of the crown is sectioned off from the buccal groove to just below the cervical line on the distal aspect of the tooth
This portion of the tooth is delivered
The remainder of the tooth is removed with a small straight elevator placed at a purchase point on the mesial aspect of the cervical line
An alternative is to prepare a purchase point in the tooth with the drill and use a crane pick or a Cryer elevator in the purchase point to deliver the tooth

Horizontal impaction

Usually requires the removal of more bone than does the mesioangular impaction
After sufficient bone has been removed down to the cervical line to expose the superior aspect of the distal root and the majority of the buccal surface of the crown, the tooth is sectioned by dividing the crown of the tooth from the roots at the cervical line
The crown of the tooth is removed, and the roots are displaced with a Cryer elevator into the space previously occupied by the crown
They may need to be sectioned into separate portions and delivered independently if the roots of an impacted third molar are divergent

Vertical impaction

The procedure for bone removal and sectioning is similar to that for the mesioangular impaction in that occlusal, buccal, and judicious distal bone is removed first
The distal half of the crown is sectioned and removed
The tooth is elevated by applying a small straight elevator at the mesial aspect of the cervical line
This is more difficult than a mesioangular removal because access around the mandibular second molar is difficult to obtain and requires the removal of substantially more bone on the buccal and distal sides

Distoangular impaction

The most difficult tooth to remove
After sufficient bone is removed from the bucco-occlusal and the distal sides of the tooth, the crown is sectioned from the roots just above the cervical line and delivered with a Cryer elevator
The entire crown is usually removed because it interferes with visibility and access to the root structure of the tooth
If the roots are fused, a Cryer or straight elevator can be used to elevate the tooth into the space previously occupied by the crown
If the roots are divergent, they are usually sectioned into two pieces and individually delivered
Extracting this impaction is difficult because so much distal bone must be removed and the tooth tends to rotate distally when elevated, running into the ramus portion of the mandible

Split

An ideal section stops short of the lingual plate and inferior alveolar canal
The split is usually accomplished with a straight elevator
The tip of the elevator is placed deep into the section and rotated along its long axis
An audible “pop” is heard, accompanied by a tactile sensation when the tooth is divided into segments

Delivery

An adequate trough and section provide an unobstructed pathway for delivery
Once adequate bone has been removed to expose the tooth and the tooth has been sectioned in the appropriate fashion, the tooth is delivered from the alveolar process with dental elevators
In the mandible the most frequently used elevators are the straight elevator, the paired Cryer elevators, or the Crane pick
An important difference between the removal of an impacted mandibular third molar and of a tooth elsewhere in the mouth is that almost no luxation of the tooth occurs for the purpose of expansion of the buccal or linguocortical plate. Instead, bone is removed, and teeth are sectioned to prepare an unimpeded pathway for delivery of the tooth
Application of excessive force may result in unfavorable fracturing of the tooth, of excessive buccal bone, of the adjacent second molar, or possibly of the entire mandible
Elevators are designed not to deliver excessive force, but to engage the tooth or tooth root and to apply force in the proper direction
Because the impacted tooth has never sustained occlusal forces, the periodontal ligaments are weak and permit displacement of the tooth root if appropriate bone is removed and force is delivered in the proper direction

Debridement

Débride the socket and the area under the flap with a periapical curette
Sharp or rough edges around the socket should be removed
The socket is gently irrigated, suctioned, and inspected with magnification
Debridement includes irrigation of the full thickness flap. The passive flap is retracted and saline is injected with pressure between the lateral surface of the mandible and flap
The flap is suctioned and inspected with magnification and loupe light to be certain that all debris has been removed
A mosquito hemostat is usually used carefully to remove any remnant of the dental follicle
The socket and wound should be thoroughly irrigated with saline or sterile water (30 to 50 mL is optimal) before the wound is closed

Closure

The incision should usually be closed by primary intention
The flap is returned to its original position, and the initial resorbable suture is placed at the posterior aspect of the second molar
Additional sutures are placed as necessary
Additional sutures are placed posteriorly from that position and anteriorly through the papilla on the mesial side of the second molar
Usually, only two or three sutures are necessary to close an envelope incision
If a releasing incision was used, attention must be directed to closing that portion of the incision as well
Check for adequate hemostasis. If brisk generalized ooze is seen after the sutures are placed, the surgeon should apply firm pressure with a small, moistened gauze pack

Reference

Peterson, L.J. (2004) Principles of oral and maxillofacial surgery. Philadelphia: Lippincott-Raven.
Fragiskos, F.D. (2010) Oral surgery. Berlin: Springer.