References
A guide to the orthodontic extrusion of traumatized permanent incisors in the mixed dentition
From Volume 45, Issue 5, May 2018 | Pages 427-433
Article
Extrusion of intruded maxillary incisors present the clinician with a great challenge, particularly in the mixed dentition. Due to their prominence and arch position, anterior teeth are the teeth most commonly involved in dental trauma.1 Traumatic incisal intrusion accounts for 0.3–1.9% of traumas affecting the permanent dentition.2 The complications after intrusive injury can be severe and include pulpal necrosis, inflammatory root resorption, replacement root resorption, ankylosis and loss of marginal bone support.3
Several methods have been suggested to treat an intruded maxillary incisor. Currently there is no definitive guideline on which method is most successful. The treatment mode selected should be based on the individual clinical situation and the best evidence available. The aim of this paper is to provide a guide for the orthodontic extrusion of maxillary incisors following intrusive luxation in the mixed dentition.
Immediate management
The immediate management of intrusion injuries, as with any dental trauma, requires a comprehensive clinical and radiographic examination. Common clinical findings when examining an intrusive luxation include: short clinical crown height relative to adjacent teeth, immobility, high metallic (ankylotic) sound, bleeding at the gingival margin and negative sensibility testing. A paralleling technique (utilizing the images of two radiographs) is recommended for the radiographic examination of traumatized teeth. This increases the ability to diagnose root or alveolar fractures. Radiographically an intruded tooth is likely to demonstrate a loss, or partial loss, of the periodontal ligament (PDL) space. The cemento-enamel junction (CEJ) will be located apically relative to neighbouring teeth and may even be apical to the marginal bone level.4
There are two main treatment approaches following an intrusive luxation injury outlined in the literature:
The mode of treatment chosen is based on the severity of the injury, presence of alveolar fracture and the number of teeth involved.5 According to the guidelines provided by the International Association of Dental Traumatology (IADT), immediate management generally depends on the severity of intrusion and root maturity.4,6 The suggested management is illustrated in Figures 1 and 2.
Treatment options
There are two main modes of therapeutic extrusion: orthodontic extrusion, with either fixed or removable appliances, and surgical extrusion. A major benefit of orthodontic extrusion is that, as the tooth extrudes, the gingival tissues and alveolar bone migrate coronally relative to the CEJ, improving the aesthetic outcome.7 Orthodontic extrusion is reported to be less traumatic than surgical repositioning and is the focus of this review.8
Orthodontic methods of extrusion are the following:
1. Orthodontic extrusion using a fixed appliance
Fixed appliances can be placed in the maxilla or mandible to facilitate extrusion of the traumatized tooth by the application of continuous forces. A major advantage of fixed appliances is that they usually do not require the patient to apply traction themselves, and are therefore not as reliant on patient compliance. Light continuous forces have been shown to provide more desirable remodelling of the periosteum and bone formation.9
The operator can choose between two types of attachment for the archwire; brackets or direct composite. Placing brackets may provide improved appliance rigidity, better control of force, allow for torque application and can be used to open or close spaces simultaneously. The authors' experience suggests that brackets pose less possibility for interference with the lips and lower incisors when compared to composite splints, which can be relatively bulky.
Composite used directly is accessible to practitioners who may not have orthodontic brackets available. This method is possibly more economical and simple to place chairside. However, the placement of loops in composite retained splints can be unaesthetic and may interfere with the upper lip and lower incisors. Fixed appliances can be placed in either the maxillary or mandibular arch to facilitate the extrusion of the intruded tooth (Table 1).
| Advantages | Disadvantages | Force Application (elastics) | |
|---|---|---|---|
| Maxillary |
|
|
|
| Mandibular |
|
|
|
Maxillary fixed appliance
Fixed labial brackets (Figure 3) can be used when an adequate number of permanent teeth are erupted. Brackets can be placed on two teeth mesial and distal to the intruded tooth (sectional appliance), or can be extended to the first permanent molars. Primary teeth can also be bonded temporarily but do not provide as much support. Primary teeth do not provide significant anchorage, particularly if they are mobile. Many clinicians favour a 2 x 4 appliance, where brackets are placed on the first permanent molars and erupted incisors. This can be particularly useful in mixed dentition as it removes the need to place brackets on primary teeth. A compliant patient is necessary for this procedure as gaining moisture control when bonding molars can be difficult.
If an inadequate number of supporting teeth are bonded, anchorage loss can occur and the surrounding teeth can begin to intrude. The clinician must carefully monitor the patient for any signs of anchorage loss and re-evaluate should any unwanted or unpredicted tooth movements occur.
Direct composite (Figure 4) can also be used to hold a wire in situ and allow an extrusive force to be placed on a tooth. Again, two teeth either side of the intruded tooth are bonded. This provides less control but can be easier for the clinician to place in general practice. An 0.018” round stainless steel wire with a loop for elastic attachment can be placed from the first visit for the application of force. Anchorage loss must always be monitored, especially if primary teeth are involved. Using direct composite instead of brackets means that the clinician will have less control of tooth movements, and it will not be possible to open space or to change archwires easily.
Mandibular fixed appliance (Figure 5)
A mandibular fixed appliance is often appropriate to provide increased rigidity if there are not enough erupted maxillary anterior permanent teeth to use as support. This fixed appliance may also be placed with or without orthodontic brackets. Disadvantages include the possibility that the mandibular incisors will extrude, the overbite may increase, and speech can be affected during its use, as there will need to be an intermaxillary force (eg an elastic) applied between the intruded upper tooth and the lower arch. Another issue is that the force may be applied more palatally than desired, which can affect the tooth position once it has been extruded. With a lower fixed appliance, the clinician is reliant on patient compliance to wear and replace elastics, which can also be problematic. Elastics will apply intermittent rather than a continuous force, which is not as effective at initiating the desired tooth movement.9
2. Orthodontic extrusion using a removable appliance
In certain clinical situations, removable appliances may be preferable to fixed. This can be the case in a younger patient with a limited number of permanent teeth available for bonding, and also in patients who are less tolerant of treatment in the dental chair. These appliances can be removed by the patient to allow for oral hygiene but do rely heavily on compliance. Maxillary and mandibular removable appliances can be used for orthodontic extrusion. The main advantages and disadvantages of these are outlined in Table 2.
| Advantages | Disadvantages | Force Application (elastics) | |
|---|---|---|---|
| Maxillary |
|
|
|
| Mandibular |
|
|
|
Maxillary removable appliance (Figures 6a and b)
Using a removable appliance increases the number of teeth and surface area available to provide anchorage. These appliances are often a very simple design and can be removed by the patient at home, making it easier for them to maintain optimal oral hygiene. By taking an impression and sending it to the laboratory, it lessens the amount of chairside armamentarium required and is also less technique sensitive than an orthodontic bond-up. As a result of its increased anchorage, the appliance may be used to extrude multiple teeth without compromising abutments. It also may be used as a retainer post extrusion to help reduce relapse.
A potential difficulty arises when attempting to make an impression of the maxillary arch in an anxious child post trauma. A great deal of clinical time may be required to get the patient to tolerate an impression. The forces applied by a removable appliance are interrupted, which can reduce the rate of tooth movement.10 In addition to this, intermittent forces may have a negative impact on patient comfort (in the authors' opinions). Comfort has been shown to have a positive influence on compliance, which is essential when using a removable appliance.11
Mandibular removable appliance
A lower removable appliance may occasionally be used to extrude maxillary incisors if there are not enough maxillary teeth available for retention of the appliance. This can occur in the following: hypodontia cases; cases where the patient has exfoliated numerous primary teeth but the permanent successors have not yet erupted sufficiently to allow application of a clasp; or if the maxillary teeth lack undercuts for retention. In certain circumstances, such as with an upper lip laceration, it may be more appropriate to select a mandibular appliance to avoid further trauma to the soft tissues during impression-taking.
Mandibular removable appliances are not usually the appliances of choice due to challenges in directing the force, achieving retention of the appliance during function, and the discomfort caused to a child when wearing an appliance that impinges on the tongue.
Success rates and complications
In a qualitative meta-analysis reported by Chaushu et al, repositioning was achieved in 90.3% of cases of luxated maxillary incisors using orthodontics. Treatment time for orthodontic extrusion has been reported to range from 21–150 days.12 Most of the cases included commenced extrusion within 3 months of injury. It has been reported that all teeth with closed apices, regardless of the severity of the intrusion, and all teeth with open apices that suffer severe intrusions, lose vitality.12 Therefore, it may be justified to complete endodontic treatment electively on severely intruded incisors to help reduce risk of further complications. Due to the increased likelihood of pulpal necrosis, low forces should be selected and vitality monitored until the end of the retention period if endodontic treatment is not completed.13 The incidence of root resorption has been reported to be 40%, regardless of which extrusive method is used, something to bear in mind when explaining treatment options to patients and parents.12
Retention
Retention post trauma has not been widely researched. In some case reports the appliance was left passively in situ for 5–8 weeks post extrusion,14 whereas others provided bonded retainers for 3 months.15
A bonded retainer may be recommended to provide vertical control during the transition into the permanent dentition. A simple wire suitably bonded to adjacent teeth would suffice in the majority of cases.13 The retainer should be reviewed regularly in case debond occurs. Removable appliances are not recommended for retention following extrusion as they cannot prevent vertical relapse. The IADT guidelines recommend that, following the repositioning of the tooth surgically or digitally, a flexible splint should be provided for 4–8 weeks to allow for stabilization.8
Conclusion
Almost 2% of dental traumas include incisal intrusive luxation, which is why knowledge in relation to the diagnosis, management options and both the long and short term complications are important for dental clinicians. By firstly diagnosing and determining if the root of the traumatized tooth is mature or immature, Figures 1 and 2 can then be used as a guide to select the most appropriate treatment. An ability to explain the potential advantages and disadvantages of various management options is important to gain informed consent from the patient and/or parent. If the particular clinician was not comfortable completing the treatment him/herself, he/she would be able to make an appropriate referral and could explain to the patient and/or parent the treatments that are likely to be offered in a specialist unit. Long term, these patients will be attending general practice for check-ups over many years and clinicians should be aware of the possible associated complications.