From Volume 51, Issue 11, December 2024 | Pages 748-754
Part 3 of this three-part series outlines the specific challenges associated with providing orthodontic–restorative treatment in adult patients experiencing dentitions injured by dental trauma or acquired disease.
Optimal management of patients with injured dentitions may necessitate a joint orthodontic–restorative approach.
The dentition may incur injury, acutely via dental trauma, or chronically via the progression (or treatment) of diseases that include: dental caries, tooth wear (TW) and periodontitis. Injury may result in loss of tooth structure, impaired quality of enamel and dentine, endodontic disease, tooth displacement, and fracture. For traumatic injuries, orthodontics can aid dental rehabilitation, particularly for re-aligning luxated teeth (that were not repositioned following displacement) or for extruding teeth with crown fractures, to create sufficient coronal dentine for restoration. While orthodontic therapy may assist in the management of damaged teeth, it poses additional risks, which must be accounted for within the treatment planning process.1 This article outlines the challenges, and presents orthodontic–restorative treatment solutions for adult patients with injured dentitions.
Approximately one-third of adults have experienced at least one episode of dental trauma2 and it is not uncommon for some patients to have suffered multiple traumatic insults to their adult dentitions. While trauma can have an immediate effect on both the dental and supporting tissues (Table 1), it may also initiate late-presenting conditions (including resorption, pulp necrosis and calcific metamorphosis), which can make both orthodontic and restorative care more complex.1
| Crown fracture* is a fracture involving enamel and dentine |
| Crown–root fracture* is a fracture involving enamel, dentine and cementum |
| Root fracture is a fracture involving cementum, dentine and pulp |
| Alveolar fracture is a fracture of the alveolar bone |
| Extrusive luxation is displacement of a tooth out if its socket in the coronal direction |
| Lateral luxation is displacement of a tooth in a lateral direction, usually associated with fracture or compression of the socket wall |
| Intrusive luxation is displacement of a tooth in the apical direction into the alveolar bone |
| Avulsion is the complete displacement of a tooth from its socket |
Teeth with uncomplicated crown fractures will often have sufficient tooth structure for bonding, although where such teeth need to be moved orthodontically, patients should be made aware that the application of orthodontic forces may lead to propagation of cracks and fractures. In turn, cracks/fractures may result in pulpal complications or discolouration (either due to ingress of extrinsic staining compounds via cracks, or from intrinsic sources secondary to pulpal complications).
For teeth with up to 50% loss of supragingival dentine, composite build-up is normally sufficient to restore the tooth function and aesthetics, as well as enable orthodontic bracket positioning (as applicable). For teeth with over 50% loss of supragingival dentine, composite build-up may not be predictable, particularly if the fracture line/cavity margin extends subgingivally. In such circumstances, there is a range of options that may be employed to expose additional supragingival tooth structure (Table 2). One option in such circumstances is orthodontic extrusion, and when coupled with crown lengthening surgery, may result in the exposure of sufficient supragingival dentine for predictable restoration (Figure 1). Considerations for orthodontic extrusion of teeth include: adequacy of root length; periodontal health; quality of residual dentine; and, sufficient root diameter to avoid overly scalloped emergence profiles and unaesthetic ‘black triangles’. It may be difficult to bond orthodontic brackets to broken down teeth/roots: these may require a temporary build-up of the exposed portion of root with glass-ionomer cement or composite resin. For severely damaged teeth, root canal treatment +/- post placement and a temporary crown may be necessary to facilitate bracket positioning/bonding.
| Treatment | Advantages | Disadvantages |
|---|---|---|
| Gingivectomy (via simple surgical excision, electro- or laser-surgery) | Increase in supragingival tooth tissue | Within healing phase, gingival tissue likely to ‘rebound’. |
| Resective crown lengthening of both gingival and alveolar complex | Increase in supra-crestal tooth tissue, and re-establishment of supra-crestal attachment at a more apical position | If single tooth is crown lengthened in isolation, this may result in asymmetric aesthetic deficit or bony deficit, therefore, there is often the requirement to extend, and ‘blend-in’, the osseous re-contouring to adjacent teeth. |
| Orthodontic extrusion +/- subsequent resection of the periodontium | Movement of tooth to a more coronal position | Required treatment time can be up to 6-months for this single aspect of the care pathway |
| Surgical extrusion (only suitable in cases of acute intrusion injury) | Efficient repositioning of intruded tooth | Not suitable in cases of delayed presentation |
Displacement of teeth or root fractures may complicate or preclude predictable restoration. Available management options for such situations are summarized in Table 3. Orthodontics can reposition teeth that have suffered intrusive, extrusive or lateral luxations, which have not been managed appropriately immediately post injury. For orthodontic extrusion of teeth, the migration of the gingival margin and supporting alveolar bone crest is thought to be related to the speed of tooth movement. Rapid extrusion, with greater forces, is typically associated with minimal tissue migration (where the speed of tooth movement exceeds the physiological adaptation rate), whereas a slower movement will generally see the gingival crest move with the tooth crown;4 however, in practice, variable results can be seen (Figure 2).
| Clinical situation | Potential restorative challenges | Pre-restorative management options |
|---|---|---|
| Extrusive luxation | Occlusal interference |
Surgical repositioning (if feasible to manipulate root back into socket). |
| Lateral luxation | Occlusal instability and tooth movement | Surgical repositioning (if feasible to manipulate root back into socket) |
| Intrusive luxation | Reduced clinical crown height |
If ≤3 mm intrusion, allow spontaneous re-eruption. If no re-eruption within 8 weeks reposition orthodontically |
| Avulsion | Bone resorption and gingival recession |
Socket reconstruction surgery with particulate graft |
| Root fracture | Tooth mobility |
Accept position of apical and coronal portions |
Traumatically compromised teeth are prone to resorption processes5 that include: external cervical resorption, surface resorption, replacement resorption, and inflammatory related root resorption (secondary to endodontic infection). Resorption is often asymptomatic and can be accelerated with orthodontic forces, leading to additional restorative complexities and/or tooth loss. For teeth assessed to have an increased risk of resorption, it is recommended that during orthodontic treatment, root length and morphology are monitored with radiographs at 6-month intervals; allowing intervention/alteration of the treatment as indicated by findings.6 Ankylosed teeth with replacement resorption cannot be orthodontically repositioned. Failure to diagnose ankylosis may result in unwanted anchorage, and consequently, during fixed appliance therapy, may lead to intrusion of the adjacent teeth. Conversely, on occasion, such anchorage can be used to the patient's advantage, for example, in cases when intrusion is required to reduce a deep overbite.
Dental caries and tooth wear (TW), along with invasive restorative interventions for management of these conditions, results in a reduction of coronal tooth structure. In the case of vital teeth, the properties of the remaining tooth structure may be altered via the physiological response of the odontoblasts to these insults, resulting in dentine sclerosis via deposition of secondary dentine. Such changes within the dentine, as well an overall reduction in enamel, negatively impact the quality of adhesive bonding procedures. However, in general, orthodontic brackets for fixed appliance systems can be predictably bonded to enamel, dentine or composite.7
Prior to embarking on a complex orthodontic–restorative care pathway it is paramount that the oral hygiene regimen is optimized and any primary disease is stabilized; particularly as the presence of orthodontic appliances adds to the oral hygiene maintenance burden. The use of clear orthodontic aligners (versus fixed appliances) may reduce plaque retention and the risk of decalcification.8 However, such appliances cannot be used in all clinical situations.
The adult patient will often present with pre-existing amalgam and ceramic restorations; materials that do not readily lend themselves to bonding of orthodontic brackets. Amalgam restorations that interfere with desired bracket positioning can be managed via either their replacement with composite, use of a banded attachment, or bypassing the tooth if minimal movement is required. Particular care should be taken within the application of orthodontic forces to unsupported cusps/coronal structure, as this may result in bulk fracture coupled with bracket debond.
Although ceramic brackets can be bonded to ceramic crowns using a silane coupling agent, the bond may repeatedly fail. In such cases, bonding may be more predictable if the ceramic crowns are removed and replaced with provisional laboratory- or chairside-constructed composite crowns (Figures 3 and 4).9
Provisional indirect composite restorations may also be indicated where there is pre-existing fixed bridgework, and/or the requirement to adjust the vertical dimension of the occlusion (Figure 4). A joint orthodontic–restorative approach will often offer the most predictable way of adjusting the pattern of occlusal forces exerted during lateral and protrusive excursive movements, ensuring they are sufficiently controlled to improve the survival of the definitive restorations and surrounding teeth.
It is now accepted that localized TW, with loss of inter-occlusal space, can be managed restoratively using either direct or indirect restorations bonded at an increased vertical dimension, with re-establishment of occlusal contacts via vertical axial re-alignment.10-12 A restorative-only approach for TW becomes increasingly difficult with severe malocclusion, particularly with inter-incisal relationship discrepancies, and orthodontics may improve the predictability of the subsequent definitive restorations.
In mild Class II incisor relationship cases with a 3–5 mm overjet, anterior contacts can be achieved using composites applied to both the labial and palatal surfaces of the mandibular and maxillary anterior teeth respectively. For overjets beyond this limit, there becomes an increased requirement for restorations with thick, overly contoured palatal surfaces, which can cause lisping and present difficulties with cleaning (Figure 5). Orthodontic therapy to reduce an overjet or improve angulation of the incisors in the adult patient will often require camouflage of the skeletal base, typically via extraction of premolars, retraction of the upper anterior teeth and/or proclination of the lower labial segment.
Where management of TW is required in Class III incisal relationships (particularly with ‘edge-to-edge’ incisors, or postured reverse overjet), there is a requirement for a minimum depth of 2 mm of restorative material thickness both in the labio-palatal/lingual and vertical dimensions. Subsequently, restorations may be overcontoured, with resultant negative impact on aesthetics and speech. For patients who can achieve an edge-to-edge incisal contact, orthodontic appliances can procline the upper labial segment, to re-establish a positive overjet, and achieve sufficient space for restorations to restore lost tooth structure (Figure 6). Proclination and increased arch width will result in additional spacing which should be accounted for within the restorative phase of the plan. If the patient is not able to achieve an incisal edge-to-edge contact, then orthognathic surgery is usually required to modify the skeletal base and facilitate occlusal realignment.
Damage to tooth structure, or displacement of teeth, may lead to pulp necrosis and apical periodontitis,13 which increases the risk of orthodontic-induced root resorption (OIRR).14 However, successfully treated apical periodontitis (via root canal treatment) does not increase the risk of OIRR.15
As outlined in the first article of this series, surrogate measures of pulp and peri-apical status should be used to identify any endodontic related problems, which where present, should be managed via root canal (re)treatment (as applicable) prior to embarking on orthodontic treatment. However, radiographic evidence of healing outcome may not be determinable until 12-months post-operatively.16 Therefore, clinical judgement should be applied as to the timing of commencement of orthodontics. There is also a risk of gutta percha being left within the peri-radicular tissues as the root apex resorbs during movement (Figure 7). This complication can be avoided by obturating short of the terminus, normally to around 1–2 mm from the radiographic apex.
Where a post is indicated, its length should be at least equal to the height of the crown,17 and 5 mm of root filling should be maintained apically to preserve the seal.18 Root filled teeth with post-retained crowns can be orthodontically moved19 as long as the post is centred within the canal space and has sufficient diameter and extension to avoid debond. Conversely, posts that are too long, generally over two-thirds of the root diameter, or are divergent from the canal space, are at increased risk of root fracture from fixed orthodontic appliances. Restorative modification of the crown-root angle should also be accounted for in the bracket positioning, to ensure that the desired three-dimensional movement is achieved.
In patients with clinical attachment loss secondary to periodontitis, orthodontic treatment can be predictably provided once their periodontal condition has been stabilized.20 Prior to initiation of orthodontic treatment, the patient must be able to demonstrate excellent plaque control, and periodontal health should be regularly (re)assessed via bleeding scores and six-point pocket charting during treatment.
A reduction in bony support is seen in advancing age and comorbidities, and the magnitude of orthodontic forces and vectors must be modified accordingly. Reduced alveolar bone levels move the centre of resistance of the tooth to a more apical position, which in-turn requires more cervical bracket positioning, and/or the use of light forces, and smaller wires to prevent the full expression of the bracket prescription. However, in general, orthodontic tooth movement can be safely employed even in cases with severe attachment loss.21
Following orthodontic treatment, bonded retainers are used for splinting periodontally compromised teeth, stabilizing the ‘jiggling forces’ that can be exacted on teeth via regular insertion and removal of removable retainers. However, the use of bonded retainers must be balanced against increased complexity of patient-delivered plaque control, and the associated propensity for calculus retention associated with fixed retainer wires.
There are conflicting views regarding the role that orthodontic therapy may play in gingival recession. Some researchers found a weak correlation between orthodontic treatment and recession,22 while others have advocated that recession can be treated with orthodontics.23 On balance, it is likely that orthodontic therapy can exacerbate recession,24,25 particularly if teeth are being proclined26 or moved bodily, closer to the envelope of alveolar bone. Risk factors for gingival recession include: reduced height of keratinized mucosa (<2 mm), thin gingival phenotypes, high frenal attachments (that displace the gingival margin upon tension of the lip or cheeks), and a more buccal positioning of teeth within the arch. Pre-orthodontic therapies for high-risk sites may include soft tissue augmentations such as free gingival grafts or coronal advancement flaps (with or without connective tissue grafts).27 If tooth extraction is required as part of the orthodontic plan, for example a requirement to removal a single lower incisor, the most compromised tooth should be chosen (which may include teeth that have suffered the greatest amount clinical attachment loss/gingival recession).
Adult orthodontic care is challenging even within the unrestored dentition. Acquired damage to the tooth and supporting structures increases the complexity and risks of providing care and may reduce the predictability of achieving the desire outcome. Meticulous case assessment and planning is recommended for successful outcomes.
