Oral Surgery PDF: Fractures of the Mandible

> - MuhammedM.Nasser  Outline &Classification of mandibular fractures & Clinical features & Imaging & Treatment E Teeth in the line of fracture ⑥ Complications of mandibular fractures A fracture is defined as a break in the continuity of the bone which happens either as a result of...

> - MuhammedM.Nasser  Outline &Classification of mandibular fractures & Clinical features & Imaging & Treatment E Teeth in the line of fracture ⑥ Complications of mandibular fractures A fracture is defined as a break in the continuity of the bone which happens either as a result of violence or because the bone is unhealthy and unable to withstand normal stresses. The mandible is the second most commonly fractured part of the maxillofacial skeleton because of its position and prominence and blows to the mandible are transmitted directly to the base of the skull through the temporomandibular articulation, this means that relatively minor mandibular fractures may be associated with a surprising degree of closed head injury. The impact forces that are required to produce mandibular fracture are higher than those of the maxilla. When the force is applied to the bone, the buccal cortex at the site of application of the force undergoes compression and the other cortex (lingual cortex) of the bone undergoes tension. If the force is greater than the compressive and the tensile strength of the bone a fracture occurs  The teeth are important in determining where fractures occur. The long canine tooth and the partially erupted or un-erupted wisdom tooth both represent lines of relative weakness. Restoration of mandibular function, in particular, as part of the stomatognathic system must include the ability to masticate properly, to speak normally, and to allow for articular movements as ample as before the trauma. In order to achieve these goals, restoration of the normal occlusion of the patient becomes paramount for the treating surgeon. The alveolar resorption that follows tooth loss also weakens the mandible and fractures of the edentulous body often result from much smaller impact forces.  Classification of mandibular fractures According to their According to the According to the tendency to displace type of fracture, Anatomic site Simple/closed. Dentoalveolar Favorable Compound/opened. Condylar Unfavorable Coronoid Comminuted. Ramus Greenstick. Angle Pathologic. Body Complicated/complex. Symphysis/Parasymphysis Single. Multiple. According to the type of fracture Simple/ Compound/ Comminuted Greenstick closed opened Pathologic Complicated/ Single Multiple complex  According to the type of fracture Simple/ closed: A type of single fracture that does not have communication with the external environment. Compound/ opened: A type of fracture that extends into external environment through skin, mucosa, or periodontal membrane. Comminuted: When the bone is fragmented into multiple pieces. This usually requires considerably more energy than does a simple fracture. Greenstick: When only one cortex of the bone is broken with the other cortex being bent, it is found exclusively in children.  According tothe type of fracture Pathologic: Caused by pre-existing pathological condition of bone (such as osteomyelitis, neoplasms or generalized skeletal disease) that leads to fracture from minimal trauma. Complicated/complex: Fractures associated with the damage to the important vital structures complicating the treatment, as well as prognosis, including the severely atrophied mandible. Single: Only one fracture line in the same bone. Multiple: Two or more lines of fractures on the same bone that do not communicate. According tothe anatomic site - Dentoalveolar - Condylar - Coronoid - Ramus - Angle - Body (molar/premolar area( - Symphysis /Para-symphysis According to the anatomic site  According to their tendency to displace Mandibular fractures classified according to their tendency to displace as a result of the pull of the attached muscles into: - Favorable when the muscles tend to pull the fragments together (minimizing displacemen ( - Unfavorable when they are significantly displaced by the muscles. The principle of favorableness is based on the direction of a fracture line as viewed on radiographs in the horizontal or vertical plane. A horizontally favorable fracture line resists the upward displacing forces, such as the pull of the masseter and temporalis muscles on the proximal fragment when viewed in the horizontal plane. A vertically favorable fracture line resists the medial is pull of the medial pterygoid on the proximal fragment when viewed in the vertical plane. Although this principle can be applied to any fracture of the mandible where there are muscles attached, it is most commonly used with angle fractures.  When the force is applied to the mandible, the point of application of the force is compressed causing direct fracture and the resultant vector travels along the bone and applies tensile force on the point intersected By this vector causing indirect fracture. Whenever a direct fracture is seen at the site of primary impact, one must examine the corresponding indirect fracture site and rule out the indirect fracture.  Common combinations of direct and indirect fractures are: Symphyseal (direct)fracture combined with bilateral subcondylar (indirect) fractures also called parade ground fracture or guardsman's fracture. Parasymphyseal (direct) fracture combined with contralateral subcondylar or angle (indirect) fracture. Body (direct) fracture combined with contralateral angle or subcondylar(indirect) fracture.  Clinical features The main clinical features of mandibular fractures include: 1. Pain especially on talking and swallowing leading to drooling of saliva. 2. Swelling due to edema and hematoma causing facial asymmetry. 3. The teeth near the fracture site may become loosened, displaced or avulsed with laceration of the gingiva. 4. Bleeding from the fracture site. 5. Trismus and difficulty in moving the jaw.. 6. Bone tenderness over fracture site. 7. Mobility of fractured segment. 8. Step deformity palpable at the site due to the displacement of the fracture segments. 9. Numbness of the lower lip due to injury to the inferior alveolar nerve in the bony canal during the fracture. 10. Altered occlusion due to displacement of the fracture segments. si 11. Sublingual hematoma which is regarded as a pathognomonic sign of fracture. 12.In some cases of bilateral subcondylar fractures with condylar displacement and shortening of the ramus leads to premature contact of the posterior teeth and anterior open bite. 13. Bilateral parasymphyseal fracture may be readily displaced posteriorly under the influence of the genioglossus muscle and to a lesser extent, the geniohyoid allowing the tongue to fall back and obstruct the oropharynx which constitutes a threat to the airway especially in patients with depressed level of consciousness. 14.In some cases of condylar fractures bleeding from the ear may result from laceration of the anterior wall of the external auditory meatus, caused by violent movement of the condylar head against the skin in this region. It is important to distinguish bleeding originating in the external auditory canal from the more serious middle ear hemorrhage while signifies a fracture of the petrous temporal bone and may be accompanied by cerebrospinal otorrhea. In all cases of suspected condylar fracture the ear should be examined carefully with an otoscope.  The clinical diagnosis of the fracture is essential but radiographs confirm the diagnosis of the fracture and are mandatory. The principle in trauma radiology is to obtain at least two views, each taken at right angles to the other, in order to assess the degree of displacement and angulation of the fragments A panoramic radiograph (OPG) represents the best single overall view of the mandible including the condyles. The combination of a posteroanterior (PA) view of the mandible and OPG usually provide a complete view of the mandible and obviate the need for further radiographs in most patients and significantly reduces the overall radiation dose to the patient. - > MuhammedM.Nasser Imaging In PA mandible view the condylar head may be obscured by superimposition of the skull base and mastoid process,for this reason , the 30° anteroposterior Townes projection is sometimes used. This view demonstrates the condylar region very well, along with the posterior fossa of the skull. A reverse Townes projection may be used to achieve the same effect. In both projections, the central ray is angled at 30°to the horizontal base line, which shows the image of the condylar head and subcondylar region clear of the dense bony structures of the base of the skull. - MuhammedM.Nasser Imaging Occlusal Views are valuable for demonstrating midline fractures of the mandible with minimal displacement. = MuhammedM. Nasser Imaging CT scan is not normally undertaken for isolated mandibular fractures unless there are complicating factors such as significant comminution, it is also useful in the assessment of displaced and comminuted fractures of the condylar region where it will demonstrate considerable detail that would otherwise not be clear on standard radiographs, such as an un- displaced vertical fracture of the condylar head. = MuhammedM. Nasser Treatment = MuhammedM.Nasser  The aim of treatment is primarily to restore function, namely to restore both the occlusion and pain-free normal movements of both TMJs. For these goals to be reached, precise anatomical reduction is not essential in every case, although it is clearly desirable. Factors affecting treatment of mandibular fractures 1. The fracture pattern 2. The skill of the operator. 3. The resources available. 4. The general medical condition of the patient. 5. The presence of other injuries. 6. The degree of local contamination and infection. 7. Associated soft-tissue injury or loss. - MuhammedM.Nasser The principles of treatment of fractures are: Debridement Reduction; it is the restoration of functional alignment of the fractured bone fragments. Fixation. Immobilization. Rehabilitation. = MuhammedM.Nasser Treatment of mandibular fractures can be closed or open => MuhammedM.Nasser  It consists of closed reduction with indirect fixation and immobilization with intermaxillary fixation (IMF )also called mandibulomaxillary fixation (MMF)]. It is the traditional conservative treatment of mandibular fractures. Closed reduction is achieved without surgical exposure of the fracture site by manipulation or elastic traction and indirect fixation utilizes the standing teeth to place the teeth in normal occlusion and immobilize them in that position thus indirectly reduce the bone fragments. This method can be used as a definitive treatment of mandibular fractures or as temporary fragment stabilization in emergency cases before definitive open treatment. > MuhammedM.Nasser Methods of immobilization After proper reduction and achievement of good occlusal relationship, the upper and the lower jaws are immobilized by fixing them together in occlusal relationship by IMF, this can be achieved by: Bonded orthodontic brackets Interdental wiring Arch bars IMF screws Cap splints Dentures or Gunning type splints = MuhammedM.Nasser  Closed treatment Bonded orthodontic brackets: By bonding a number of modified orthodontic brackets onto the teeth and applying light wires or intermaxillary elastic bands. gisl - MuhammedM.Nasser Arch bars: They are tooth-borne devices used in IMF of dentate patients. They are the most versatile form of IMF. They are also used in temporary stabilization of mandibular fractures and for fixation of avulsed teeth and dentoalveolar fractures. Arch bars are indicated where the patient has an insufficient number of suitably shaped teeth or when a direct linkage across the fracture is required. Different types of arch bars are in use. They come as custom made or commercially manufactured available in aluminum, stainless steel, and nowadays titanium, as well as various alloys. Many patterns or designs of arch bars are present; Erich, Schuchardt, Jelenko, Krupps and Dautreys patterns. Recently hybrid arch bar systems that use bone support have been developed. - MuhammedM.Nasser Interdental wiring: This method is only applicable when the patient has a complete, or almost complete, number of suitably shaped teeth, 0.5 mm soft stainless wire is usually. used. Many different techniques for wire fixation exist; direct interdentaI wiring, eyelet or Ivy loops, and Ernst ligatures, in addition to other techniques. After applying the fixation wires, tie wires are applied to immobilize the mandible. · · = MuhammedM.Nasser IMF screws: These screws are self-drilling and self-tapping.The screw head is elongated and contains holes for wire placement.They are inserted through small incisions in the labial vestibule avoiding injury to the apices of the nearby teeth, it is regarded as a rapid method to achieve IMF. - MuhammedM.Nasser Cap splints: They are fabricated by making an impression of the fractured jaw and preparation of the cast on which a cap splint made of acrylic or metal can be fabricated and used for fixation of the fracture. The acrylic splint is secured to the mandible by circummandibular wiring, using a bone awl. => MuhammedM.Nasser Dentures or Gunning type splints Dentures or Gunning type splints in edentulous jaw fractures, complete denture can be used as a splint and if the patient is not denture wearer Gunning-type splints can be fabricated, they take the form of modified dentures with bite blocks in place of the molar teeth and a space in the incisor area to facilitate feeding. They are fixed to the jaws by circummandibular and maxillary peralveolar wires or screws, and IMF is achieved by connecting the two splints with wire loops or elastic bands. - MuhammedM.Nasser External pin fixation: This method is seldom used nowadays, it is indicated in special conditions, such as infected fractures, fractures caused by gunshot injuries or pathological fractures. Ideally, at least two self-tapping screw pins are placed either side of the fracture or defect. The fracture is then reduced and the pins linked by an external bar framework. - MuhammedM.Nasser With early uncomplicated treatment in a healthy young adult union can on average be achieved after 3 weeks, at which time 4(Mobile or comminuted fractures. the fixation can be released. 5(Fractures in alcoholics, particularly those with nutritional As an empirical guide a further 1-2 weeks problems should be added for each and any of the Rules such as these are designed for following circumstances: guidance only, and it must be 1)Where a tooth is retained in the emphasized that the IMF should be fracture line. released and the fracture tested clinically before the fixation is finally 2)Patients aged 40 years and over. removed. 3) Patients who are smokers. - MuhammedM.Nasser  Non-displaced favorable fractures. Limited resources and facilities for open treatment. Medically compromised patients where conservative line of treatment is required. Grossly infected fractures. Pediatric fractures with mixed dentition phase. sit Edentulous fractures. > MuhammedM.Nasser Advantages of closed treatment Non-invasive, simple, easy to master. Can be performed under local anesthesia. Less expensive. = MuhammedM.Nasser Disadvantages of closed treatment The closed treatment relies on positioning the occluding teeth in a correct way, based on the assumption that this will result in precise reduction of the attached bony fragments, but in fact closed treatment provides only a limited control over the final repositioning of the fractured bone fragment and it does not ensure anatomical reduction of the fracture. In certain cases, closed treatment may be difficult especially in cases of malocclusion, missing, diseased, or damaged teeth. The immobilization may not be adequate which delays the healing. The treatment induces morbidity to the patient due to the IMF affecting eating and speech. Closed treatment is contraindicated in some conditions, e.g., epilepsy, chronic respiratory diseases, incompliant patient, or chronic alcohol or drug abuse. = MuhammedM. Nasser  It consists of open reduction and internal fixation (ORIF) or direct skeletal fixation. In open reduction, the fracture site is surgically exposed and the fracture is reduced under direct vision and the fractured fragments are immobilized by different internal direct fixation methods. ORIF is now considered the main method of treatment of mandibular fractures. = MuhammedM. Nasser Open treatment Themainindications for opentreatment: 1. Displaced unfavorablefractures. 2. Multiplefractures of the facial bones 3. Fractures of an edentulousmandiblewith severe displacement. 4. Delay of treatment andinterposition of soft tissue betweennon-contactingdisplaced fracture fragments. 5. Special systemic conditions contraindicating IMF. - MuhammedM. Nasser Depending on the planned method of internal fixation and the site of the fracture, three different surgical approaches to the mandibular body, with slight modifications, are possible: Intraoral Extraoral Combined access. # MuhammedM. Nasser Methods of internal fixation (osteosynthesis( Interosseous or Miniplates Three-dimensional Non-compression Trans-osseous wiring (miniaturized plates( titanium miniplates rigid plates Compression Lag screws Bioabsorbable plates plates and screws Interosseous or Trans-osseous wiring It is the direct skeletal fixation of two or more bone fragments with the aid of wire ligatures pulled through previously drilled holes, it is considered a non-rigid fixation method. It can be applied on the upper or lower border following reduction, but additional fixation of the fractured mandible with IMF is required to maintain stability. Wiring can be in the form of simple ligature, combination of simple ligature and figure-of-eight wiring or in the form of double ligature. The advent of plating techniques has superseded interosseous wiring in most situations especially in developed countries. Miniplates (miniaturized plates( These are the most common form of internal fixation used in the management of mandibular fractures. They provide semi-rigid or load sharing fixation and were developed in 1970s and were originally fabricated in stainless steel but titanium is now the metal of choice. The miniplate principle involves placing the miniplates along the tension and torsion lines across the fracture, the plate can be anchored using only the outer cortical bone with so-called "monocortical" screws which are 2 mm in diameter. As a result, plates and monocortical screws can be placed safely in anatomically correct position where they are biomechanically desirable. - MuhammedM.Nasser Three-dimensional titanium miniplates They are based on the principle of the quadrangle as a geometrically stable configuration for support. The plates are adapted to the bone and are secured with monocortical self-cutting screws. - MuhammedM.Nasser Non-compression rigid plates These plates provide rigid or load bearing fixation, they are mainly used in the management of infected, severely comminuted fractures, in fractures where there are continuity defects, and in fractures in which delayed union or non-union has occurred. Adaptation of the plates is technically more demanding and they often require an extra-oral approach for accurate placement. They require bicortical screws and are fixed in place at or near the lower border of the mandible in order to avoid damage to the inferior alveolar nerve and the dental roots. Some modern designs of plates employ locking screws that lock into the plate at the completion of insertion in order to avoid any micro-movement between the plate and the screw. => MuhammedM.Nasser Compression plates These plates provide rigid fixation, the principle of compression plating is by transforming the downward force of screw insertion into a longitudinally directed compressive force. This action displaces the screw and the fractured fragment in the direction of the opposite fragment, resulting in compression between the bone ends. Studies have shown that this type of plates does not offer any advantage to the patient in the treatment. = MuhammedM.Nasser Lag screws In oblique fractures compression lag screws can be applied without plates, they are placed perpendicularly across the fracture line in order to avoid displacing the fragments. To produce compression, the proximal bone hole is oversized so that only the distal fragment is engaged by the screw. Tightening applies sufficient compression and consequently fixation of the fracture site. It is an effective method, which can be employed transorally in a number of cases. This technique appears to be ideal for parasymphyseal and symphyseal fractures, but it becomes technically more difficult in body or angle fractures because the risk of damage to the alveolar inferior nerve increases - MuhammedM.Nasser Bioabsorbable plates and screws These are made from materials that undergo degradation, so they do not have to be removed after fracture healing. They are mainly indicated in pediatric fractures. => MuhammedM.Nasser  Teeth in the fracture line may cause infection of the fracture site either from the oral cavity via the disrupted periodontium or directly from an infected pulp or chronic apical infection. Infection of the fracture site will result in protracted healing or even non-union. > MuhammedM.Nasser 1. Longitudinal fracture involving the root. 2. Dislocation or subluxation of the tooth from its socket. 3. Presence of periapical infection. 4. Advanced periodontal disease. 5. Already infected fracture line. 6. Acute pericoronitis. 7. Where a displaced tooth prevents reduction of the fracture. - MuhammedM.Nasser 1. Functionless tooth that would probably eventually be removed. 2. Advanced caries. 3. Doubtful teeth that could be added to existing dentures. Otherwise teeth that are structurally undamaged and potentially functional should be retained and antibiotics administered. Teeth in line of fracture should be followed up for 1 year and should be endodontically treated if there is demonstrable loss of vitality. If fracture becomes infected, immediate extraction should be performed. - MuhammedM. Nasser