Mandibular Fractures

Mandible is embryologically a membrane bent bone although, resembles physically long bone it has two articular cartilages with two nutrient arteries.

Mandible in trauma

Mandibular fracture is more common than middle third fracture (anatomical factor)

It could be observed either alone or in combination with other facial fractures

 Minor mandibular fracture may be associated with head injury owing to the cranio-mandibular articulation

Mandibular fracture may compromise the patency of the airway in particular with loss of consciousness

Fracture of mandible occurred with frontal impact force as low as 425 lb (190 Kg) {Condylar fracture}

Fracture of condyle regarded as a safety mechanism to the patient

Frontal force of 800-900 lb (350-400 Kg) is required to cause symphesial fracture

Mandible was more sensitive to lateral impact than frontal one

Frontal impact is substantially cushioned by opening and retrusion of the jaw

(Nahum 1975)

Long canine tooth and partially erupted wisdoms represent line of relatively weakness

 

Anatomical considerations

Attached muscles:

• Masseter
• Temporalis
• Medial and lateral pterygoid
• Mylohyoid
• Geniohyoid and genioglosus
• anterior belly of digastrics

Blood supply

Endosteal supply via the ID artery and vein

Periosteal supply, important in aging due to diminishes and disappearance of alveolar artery

Bradley 1972

Nerve

Damage of inferior dental nerve

Facial palsy by direct trauma to ramus

Damage of facial nerve in temporal bone fracture

Goin 1980

Damage to mandibular division of facial nerve

Factors influenced site of fracture and displacement

Anatomy of the mandible and attached muscle (canine & wisdoms)

Weakening areas of mandible (resorption and pathologyl)

Direction of force of the blow

Age of the patient

Types of fracture

Simple

Greenstick fracture (rare, exclusively in children)

Fracture with no displacement (Linear)

Fracture with minimal displacement

Displaced fracture

Comminuted fracture

Extensive breakage with possible bone and soft tissue loss

Compound fracture

Severe and tooth bearing area fractures

Pathological fracture

(osteomyelities, neoplasm and generalized skeletal disease)

Sites of fractures

Condyle fracture

Intracapsular fracture

Extracapsular fracture

High condyle neck fracture

Low condylar fracture

Angle/ ramus fracture (body fracture)

Canine region (parasymphesial fracture)

Midline fracture (symphesis fracture)

Coronoid fracture (rare)

Incidence of mandibular fractures

Body fractures 33.6%

Subcondylar fracture 33.4%

Fractures at the angle 17.4%

Alveolar fractures 6.7%

Ramus fractures 5.4%

Midline fractures 2.9%

Fracture of coronoid process 1.3%

Oikarinen & Malmstrom 1969

Favourable or unfavourable

They can be vertically or horizontally in direction

They are influenced by the medial pterygoid-masseter “sling”

If the vertical direction of the fracture favours the unopposed action of medial pterygoid muscle, the posterior fragment will be pulled lingually

If the horizontal direction of the fracture favours the unopposed action of messeter and pterygoid muscles in upward direction, the posterior fragment will be pulled lingually

Favourable fracture line makes the reduced fragment easier to stabilize

Effects of muscles on displacement

Transverse midline fracture (symphesial) stabilizes by the action of mylohyoid and geniohyoid

Oblique fracture (parasymphesial) tends to overlap under the influence of muscles action

Bilateral parasymphesial fracture results in backward displacement associated with loss of tongue control when the level of consciousness is depressed

Condylar fractures

The most common mandibular fracture

Unilateral or bilateral

Intracapsular or extracapsular

Antero-medial displacement is common but it may remain angulated with the ramus

Dislocation of the glenoid fossa and fracture of petrous temporal bone which is very rare

Sign and symptoms

Swelling, pain, tenderness and restriction of movement

Deviation of mandible towards the side of fracture

Gagging of occlussion (premature contact on the posterior teeth) with bilateral condylar displaced or over-riding fractures

Displacement of mandible toward the affected side

Anterior open bite on opposite side of fracture

Laceration of EAM****

Retroauricular ecchymosis****

Cerebrospinal leak and otorrhea in association with skull base fracture

Sequlae of TMJ injury

Artheritic changes

Haemartherosis, fibrosis and aknylosis

Meniscal damage and detachment

TMD

Staph infection with condylar backward displacement and external auditory meatus injury

Meningitis with petrous temporal bone fracture and intracranial involvement

Coronoid process fracture:

Rare fracture caused by direct trauma to ramus and results from reflux contraction of temporalis

Can be seen following operation of large ramus cyst

Elicit tenderness over the anterior part of ramus

Development of tell-tale haematoma

Fracture of the ramus:

Type I Single fracture

Mimics low condylar fracture that runs below the sigmoid notch

Type II comminuted fracture

Common in missile injuries and appears to be with little displacement due to effects of messeter and medial pterygoid muscles

Fracture of the angle and body

Pain, tenderness and trismus

Extra-oral swelling at the angle with obvious deformity

Step deformity behind the molar teeth

Movement and crepitus at the fracture site

Derangement of occlussion

Intra-oral buccal and lingula heamatoma

Involvement of IDN

Gingival tear if fracture in dentated area

Tooth involvement and possible longitudinal split fracture

Midline fracture

The most common missed fracture (always fine crack)

Can be symphesial or parasymphesial fracture

Commonly associated with one or both condyles fracture

Unilateral fracture leads to over-riding of the fragments and bilateral  may contribute in loss of voluntery tongue control

Long canine tooth represent a weak area and contributes to parasymphesial fracture

Rarely runs across mental foramen

Signs and symptoms

Pain and tenderness

Swelling and odemea

Development of step deformity

Mental anesthesia

Heamatoma in the floor of mouth and buccal mucosa

Soft tissue injury of the chin and lower lip

If associated with condylar fractures

Absence of condyle movement on the contrlateral side

Deviation of mandible

Anterior open bite

Gagging of oclussion

Limitation of mouth opening

Clinical assessment and diagnosis

History of trauma (traumatized patients with possible head injury) and facial injuries

Clinical Examination

▶ Extroral

Inspection (assessment of asymmetery, swelling, ecchymosis, laceration and cut wounds)

Palpation for eliction of tenderness, pain, step deformity and malfunction

▶ Intra- and paraoral

Bleeding, heamatoma, gingival tear, gagging of occlussion and step deformity and sensory and motor deficiency

Radiographs

Radiographs

Plain radiograph

OPG

Lateral oblique

PA mandible

AP mandible (reverse Townes)

Lower occlusal

CT scan

3-D CT imaging

MRI

Principles of treatment
similar to elsewhere fractures in the body

Reduction of fragments in good position

Immobilization until bony union occurs

These are achieved by:

Close reduction and immobilization

Open reduction and rigid fixation

Other objective of mandible fracture treatment:

Control of bleeding

Control of infection

Definitive treatment

Soft tissue repair

Debridment

Irrigation with saline and antibiotics

Closure in layers

Dressing

Reduction and fixation of the jaw

▶ Close reduction and IMF (traditional method by means of manipulation)

▶ Open reduction and semi-rigid fixation (using inter-ossous wirings)

▶ Open reduction and rigid fixation (using bone palates osteosynthesis)

Objective:

Restoration of functional alignment of the bone fragments in anatomically precise position utilizing the present teeth for guidance

Close reduction

Arch bars

Jelenko

Erich pattern

German silver notched

Cap splints

▶ IMF prior to rigid fixation

▶ For the purpose of close reduction

Close reduction

Bonded brackets

IMF screws

Dental wiring:

Direct wiring

Eyelet wiring

Local anesthesia or sedation

Minimal displacement

IMF for 6 weeks

Treatment can be performed under GA or LA and when surgery is contraindicated

Fracture mandible in children

Close reduction

Open reduction and fixation

Plating at the inferior border

Resorpable plates

Gunning’s splint

Old modality

Edentulous patient

Rigid fixation is not possible

To establish the occlusion

Open reduction and fixation

Intraoral approach

Extraoral approach

▶ Submandibular approach

Rigid fixation

Intraossous wiring

Plates and screws

Kirchener wire

Lag screws

Reconstruction palate

Severe trauma

Loss of part of the bone

Condylar fractures

Intraoral approach

Ramus  incision

Extraoral approach

Preauricular approach

Retromandibular approach

IMF

Transosseous wiring

Circumferential wiring

External pin fixation

Bone clamps

Trans-fixation with Kirschner wires

Osteosynthesis

Non-compression small plates

Compression plates

Miniplates

Lag screws

Resorbable plates and screws

Teeth in the fracture line

The fracture is compound into the mouth

The tooth may be damaged or lose its blood supply

The tooth may be affected by some preexisting pathology

Management of teeth retained in fracture line

Good quality intra-oral periapical radiograph

Insinuation of appropriate systemic antibiotic therapy

Splinting of tooth if mobile

Endodontic therapy if pulp is exposed

Immediate extraction if fracture becomes infected

Follow up for 1 year and endodontic therapy if there is a loss of vitality

Absolute indications

Longitudinal fracture

Dislocation or subluxation from socket

Presence of periapical infection

Infected fracture line

Acute pericoronitis

Relative indications

Functional tooth that would be removed

Advanced caries or periodontal diseases

Doubtful tooth which would be added to existing denture

Tooth in untreated fracture presenting more than 3 days after injury

Anomalies of eruption in mixed dentition

In the mixed dentition, three other anomalies of eruption are fairly common:

1. Infraoccluded primary teeth usually exfoliate provided that the permanent successors are present, but they should be kept under review. If they are not shed and eruption of the permanent tooth is seriously delayed, or if the infraocclusion becomes very marked, then they should be extracted and a space maintainer fitted if appropriate.

2. Impaction of the upper first permanent molar into the distal of the upper second primary molar causing resorption. It is possible to disimpact the tooth with an appliance, but the problem usually resolves spontaneously when the primary molar is shed. The resorption may cause pain if it involves the pulp, in which case the primary molar should be removed. This allows the permanent molar to move rapidly mesially, and a space maintainer or an active appliance to move it distally should be considered.

3. Second premolars in unfavourable positions are sometimes seen as incidental findings on panoramic radiographs, but fortunately they usually correct spontaneously and eventually erupt satisfactorily. Very occasionally this does not happen, and a few cases have been reported of a lower second premolar migrating towards the mandibular ramus. Upper or lower second premolars that are blocked out of the arch because of crowding usually erupt, but are displaced lingually.

ANOMALIES OF ERUPTION-THE ECTOPIC MAXILLARY CANINE

Introduction

The path of eruption of any tooth can become disturbed. Sometimes the reason is obvious, such as a supernumerary tooth impeding an upper incisor, but often it is obscure. In clinical orthodontics, the most common problem of aberrant eruption is the impacted maxillary canine, which is second only to the third molar in the frequency of impaction.

Prevalence of impacted maxillary canines

Ectopic maxillary canines occur in about 2% of the population, of which about 85% of canines are palatal and 15% buccal to the line of the upper arch. The risk of impaction of the upper canine is greater where the lateral incisor is diminutive or absent¾the lateral incisor root is known to guide the erupting canine. An impacted canine can sometimes resorb adjacent incisor roots, and this risk may be as high as 12%. Incisor resorption is sometimes quite dramatic.

Impacted canine causing root resorption

Clinical assessment

During the mixed dentition stage the normal path of eruption of the maxillary canines is slightly buccal to the line of the arch, and from about 10 years of age the crowns should be palpable as bulges on the buccal aspect of the alveolus.

If not, an abnormal path of eruption should be suspected, particularly where eruption of one canine is very delayed compared with the other side. Unerupted maxillary canines should be palpated routinely on all children from the age of 10 years until eruption.

Radiographic assessment

Where the canine is not palpable it should be assessed radiographically. A periapical radiograph shows whether the primary canine root is resorbing normally and whether the canine follicle is enlarged. If the apex of the primary canine is not resorbing, with either no root resorption or only lateral resorption, the path of eruption of the permanent canine may be abnormal. However, a single radiograph cannot fully determine the unerupted canine's position relative to the other teeth¾two views are needed for this, either at right angles to each other or for the parallax technique.

Parallax technique

This method, also known as the tube-shift method, compares two views of the area taken with the X-ray tube in two different positions. (a) shows a palatal canine on a periapical film being taken with the tube positioned forward or mesially. A second film taken with the tube positioned further distally gives an image which apparently shows the canine crown in a different position relative to the adjacent roots. In this case the image of the canine appears to have shifted distally when compared with the first film, that is in the same direction that the tube was moved, which indicates that the canine is palatal to the other teeth. An apparent shift in the opposite direction to the tube shift would indicate that the tooth is lying buccally to the other teeth.

The parallax technique works best using two periapical views, but with care it can also be applied to a panoramic tomogram with a standard occlusal view, using vertical shift. The tube position is low down for the panoramic tomogram and much higher for the occlusal view, and so in this example the palatal canine appears to be nearer the incisor apices in the occlusal view, i.e. its apparent movement is upwards with the tube. The size of the image of a displaced tooth on a panoramic radiograph is another indicator, being enlarged if it is palatal and reduced if it is labial or buccal. However, a periapical view is still necessary to check for associated pathology, and this can be used with the occlusal view to make another parallax pair. The combination of panoramic, standard occlusal, and periapical views, such as that in, allows comprehensive assessment of a maxillary canine.

Two films at right angles

This method is more applicable to the specialist as it involves a taking lateral skull view and a posteroanterior (p-a) view: possibly a p-a skull, but more commonly using a panoramic radiograph for the same purpose. The lateral skull view shows whether the canine crown is buccal or palatal to the incisor roots, and the p-a or panoramic view shows how close it is to the mid-line. The angulation of the tooth and its vertical position are assessed using both views. An intraoral view must also be taken to check for any associated pathology.

The position of the impacted canine's crown should be determined as being buccal, palatal, or in the line of the arch. The degree of displacement should be assessed horizontally, that is how close it is to the mid-line, in terms of how far it overlaps the roots of the incisors. The canine crown's vertical position is assessed relative to the incisor apices. An estimate should also be made of the tooth's angulation and the position of its apex relative to the line of the arch.

Other radiographic signs that may suggest an abnormal path of eruption are: obvious asymmetry between the positions of the two upper canines; lack of resorption of the root of the primary canine on the affected side; and resorption of permanent incisor roots. If there are signs of incisor resorption, urgent advice and treatment should be sought.

Parallax location of |3. (a) Radiograph taken with the tube positioned forward shows that the image of the canine crown is slightly mesial to the image of |1. (b) Radiograph taken with the tube positioned further distally shows that the image of |3 is further distally. The image of |3 has shifted in the same direction as the tube shift:|3 is therefore nearer to the film than |1, i.e. it is palatal to the line of the arch. (c) Diagrammatic representation of how a palatally positioned tooth moves 'with' the tube from left to right

Early treatment

During the later mixed dentition, if an upper canine is not palpable normally and is found to be ectopic, extraction of the primary canine has a good chance of correcting or improving the path of eruption of the permanent canine, provided it is not too severely displaced. Extraction of the primary canine is only appropriate under these conditions:

(1) early detection¾mixed dentition;
(2) canine crown overlap of no more than half the width of the adjacent incisor root as seen on a panoramic view;
(3) canine crown no higher than the apex of the adjacent incisor root;
(4) angle of 30° or less between the canine's long axis and the mid-sagittal plane;
(5) reasonable space available in the arch¾no more than moderate crowding.

Unless the upper arch is spaced, the contralateral primary canine should also be removed to prevent the upper centreline shifting. Eruption of the permanent canine should be monitored clinically and if necessary radiographically, and specialist advice sought if it fails to show reasonable improvement after a year.

The main disadvantage of extracting the primary canine is losing the option of retaining it if the permanent canine fails to erupt. It may also allow forward drift of the upper buccal teeth where there is a tendency to crowding, and if space is critical a space maintainer should be fitted.

 Later treatment
The treatment options in the permanent dentition are to:

(1) expose the canine and align it orthodontically;
(2) transplant the canine;
(3) extract the canine;
(4) leave the impacted canine in situ.

Exposure and orthodontic alignment

This is the treatment of choice for a well-motivated patient, provided the impaction is not too severe. The canine should lie within these limits:

(1) canine crown overlapping no more than half the width of the central incisor root;
(2) canine crown no higher than the apex of the adjacent incisor root;
(3) canine apex in the line of the arch.

The tooth can either be exposed into the mouth and the wound packed open, or a bracket attached to a gold chain can be bonded to it and the wound closed. An orthodontic appliance, usually fixed, then applies traction to bring the tooth into alignment. This treatment can take up to 2 years, depending on the severity of the canine's displacement. Exposure works well for palatally impacted canines, but buccally impacted canines usually have a poor gingival contour following exposure, even when an apically repositioned flap procedure has been used. For this reason some operators prefer to attach a chain to buccally impacted canines and to close the wound, so that the unerupted canine is brought down to erupt through attached, rather than free, gingiva.

Transplantation

The attraction of transplantation is that orthodontic treatment is avoided and yet the canine is brought into function. Two criteria must be met: the canine can be removed intact with a minimum of root handling; and there must be adequate space for the canine in the arch.

The major cause of failure is root resorption, but the incidence of this is reduced if the surgical technique is atraumatic and the transplanted tooth is root- filled with calcium hydroxide shortly after surgery. The success rate for canine transplantation is about 70% survival at 5 years, but many clinicians regard it as being appropriate in only a few cases.

Extraction of the permanent canine

This is appropriate if the position of the canine puts it beyond orthodontic correction, or if the patient does not want appliance treatment. If present, the primary canine can be left in situ, and although the prognosis is unpredictable, a canine with a good root may last for many years. When it is eventually lost a prosthesis will be needed, and provision of this can be difficult if the overbite is deep¾another factor to be taken into account when considering treatment options.

Extraction of the permanent canine may also be considered where the lateral incisor and premolar are in contact, giving a good appearance. In this case it is often expedient to accept the erupted teeth and extract the canine.

Leaving the unerupted canine in situ

During the early teenage years there is a risk of resorption of adjacent incisor roots so that annual radiographic review is necessary, although the risk of root resorption reduces with increasing age. The onset of root resorption can be quite rapid, and for this reason many impacted canines are removed. There may be a case for retaining the canine in the short term in a younger patient, in case they have a change of heart about orthodontic treatment to align the tooth.

Key Points
Ectopic canines
· About 2% of children have ectopic upper canines, of which 85% are palatal.
· Always palpate for upper canines from the age of 10 years until eruption.
· Non-palpable upper canines should be located radiographically or referred for investigation.
· Consider extraction of a primary canine if a permanent canine is mildly displaced.
· Untreated, unerupted permanent canines may resorb incisor roots and should be radiographed annually during the teenage years.

RUBBER DAM - Benifits for the patient and dentist, technique

Introduction

Most texts that discuss operative treatment for children advocate the use of rubber dam, but it is used very little in practice despite many sound reasons for its adoption. In the United Kingdom less than 2% of dentists use it routinely. It is perceived as a difficult technique that is expensive in time and arduous for the patient.

In fact, once mastered, the technique makes dental care for children easier and a higher standard of care can be achieved in less time than would otherwise be required. In addition, it isolates the child from the operative field making treatment less invasive of their personal space.

The benefits can be divided into three main categories as shown below.

Safety

Damage of soft tissues

The risks of operative treatment include damage to the soft tissues of the mouth from rotary and hand instruments and the medicaments used in the provision of endodontic and other care. Rubber dam will go a long way to preventing damage of this type.

Risk of swallowing or inhalation

There is also the risk that these items may be lost in the patient's mouth and swallowed or even inhaled and there are reports in the literature to substantiate this risk.

Risk of cross-infection

In addition, there is considerable risk that the use of high-speed rotary instruments distribute an aerosol of the patients' saliva around the operating room, putting the dentist and staff at risk of infection. Again, a risk that has been substantiated in the literature.

Nitrous oxide sedation

If this is used it is quite likely that mouth breathing by the child will increase the level of the gas in the environment, again putting dentist and staff at risk. The use of rubber dam in this situation will make sure that exhaled gas is routed via the scavenging system attached to the nose piece. Usually less nitrous oxide will be required for a sedative effect, increasing the safety and effectiveness of the procedure.

Benefits to the child

Isolation

One of the reasons that dental treatment causes anxiety in patients is that the operative area is very close to and involved with all the most vital functions of the body such as sight, hearing, breathing, and swallowing. When operative treatment is being performed, all these vital functions are put at risk and any sensible child would be concerned. It is useful to discuss these fears with child patients and explain how the risks can be reduced or eliminated.

Glasses should be used to protect the eyes and rubber dam to protect the airways and the oesophagus. By doing this, and provided that good local analgesia has been obtained, the child can feel themselves distanced from the operation. Sometimes it is even helpful to show the child their isolated teeth in a mirror. The view is so different from what they normally see in the mirror that they can divorce themselves from the reality of the situation.

Relaxation

The isolation of the operative area from the child will very often cause the child to become considerably relaxed¾always provided that there is good pain control. It is common for both adult and child patients to fall asleep while undergoing treatment involving the use of rubber dam¾a situation that rarely occurs without. This is a function of the safety perceived by the patient and the relaxed way in which the dental team can work with its assistance.

 Shows rubber dam placed in the a child and with the comfort it provides it is not unusual for children to fall asleep in the dental chair during treatment under rubber dam.0

Benefits to the dentist

Reduced stress

As noted above, once rubber dam has been placed the child will be at less risk from the procedures that will be used to restore their teeth. This reduces the effort required by the operator to protect the soft tissues of the mouth and the airways. Treatment can be carried out in a more relaxed and controlled manner, therefore lessening the stress of the procedure on the dental team.

Retraction of tongue and cheeks

Correctly placed rubber dam will gently pull the cheeks and tongue away from the operative area allowing the operator a better view of the area to be treated.

Retraction of gingival tissue

Rubber dam will gently pull the gingival tissues away from the cervical margin of the tooth, making it much easier to see the extent of any caries close to the margin and often bringing the cervical margin of a prepared cavity above the level of the gingival margin thus making restoration considerably easier. Interdentally, this retraction should be assisted by placing a wedge firmly between the adjacent teeth as soon as the dam has been placed. This wedge is placed horizontally below the contact area and above the dam, thus compressing the interdental gingivae against the underlying bone. Approximal cavities can then be prepared, any damage from rotary instruments being inflicted on the wedge rather than the child's gingival tissue.

Quite often it can be difficult and time consuming to take the rubber dam between the contacts because of dental caries or broken restorations. It is possible to make life easier by using a 'trough technique', which involves snipping the rubber dam between the punched holes. All the benefits of rubber dam are retained except for the retraction and protection of the gingival tissues.

Moisture control

As mentioned previously, silver amalgam is probably the only restorative material that has any tolerance to being placed in a damp environment, and there is no doubt that it and all other materials will perform much more satisfactorily if placed in a dry field. Rubber dam is the only technique that readily ensures a dry field.

'Trough technique' of rubber dam placement.0.015625

Technique

Most texts on operative dentistry demonstrate techniques for the use of rubber dam. It is not intended to duplicate this effort, but it would seem useful to point out features of the technique that have made life easier for the authors when using rubber dam with children.

Analgesia

Placement of rubber dam can be uncomfortable especially if a clamp is needed to retain it. Even if a clamp is not required the sharp cut edge of the dam can cause mild pain. Soft tissue analgesia can be obtained using infiltration in the buccal sulcus followed by an interpapillary injection. This will usually give sufficient analgesia to remove any discomfort from the dam. However, more profound analgesia may be required for the particular operative procedure that has to be performed.

Method of application

There are at least four different methods of placing the dam, but most authorities recommend a method whereby the clamp is first placed on the tooth, the dam stretched over the clamp and then over the remaining teeth that are to be isolated. Because of the risk of the patient swallowing or inhaling a dropped or broken clamp before the dam is applied, it is imperative that the clamp be restrained with a piece of floss tied or wrapped around the bow. This adds considerable inconvenience to the technique and the authors favour a simpler method whereby the clamp, dam, and frame are assembled together before application and taken to the tooth in one movement. Because the clamp is always on the outside of the dam relative to the patient there is no need to use floss to secure the clamp.

A 5-inch (about 12.5 cm) square of medium dam is stretched over an Ivory frame and a single hole punched in the middle of the square. This hole is for the tooth on which the clamp is going to be placed and further holes should be punched for any other teeth that need to be isolated. A winged clamp is placed in the first hole and the whole assembly carried to the tooth by the clamp forceps. The tooth that is going to be clamped can be seen through the hole and the clamp applied to it. The dam is then teased off the wings using either the fingers or a hand instrument. It can then be carried forward over the other teeth with the interdental dam being 'knifed' through the contact areas. It may need to be stabilized at the front using either floss, a small piece of rubber dam, a 'Wedjet', or a wooden wedge.