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Multidisciplinary management of an enamel–dentine crown fracture with insufficient inter-occlusal restorative space: A case report Matthew Giudici Andrew Flett Andrew Legg Dental Update 2024 49:9, 707-709.
Dental trauma occurs commonly in young patients, can be complex to treat and can have negative psychological and social impacts on patients' lives. This case report outlines a multidisciplinary team approach to restoration of a traumatized anterior tooth with delayed presentation, insufficient inter-occlusal space for restoration and history of multiple failed restorations. This case report demonstrates orthodontic and restorative techniques for the management of insufficient inter-occlusal space and the indirect restoration of a traumatized anterior tooth.
CPD/Clinical Relevance: A multidisciplinary team approach can be used to reorganize a patients' occlusion to provide the inter-occlusal space required to provide restorations.
Article
Dental trauma is usually caused by an impact to the teeth and other hard and soft tissues of the oral cavity and facial skeleton.1 This is usually an unexpected, or accidental injury requiring emergency treatment and is most commonly seen during childhood with up to 3% of the population experiencing a dental injury before adulthood.2 At young ages, dental trauma is mostly related to falls, but as age increases, other factors, such as sport and road traffic accidents, begin to take precedence. Between the ages of 7 and 18 years, 8% of dental trauma injuries are related to sports.3 The incidence of dental trauma is also higher for males than it is for females of the same age.1,4 This has often been attributed to larger male participation in contact sports and increased high-risk behaviours.
Dental trauma impacts patients in many different ways. Treatment of dental trauma is often complex and can take many years to complete, with additional follow-ups and reviews.5 Dental trauma and the subsequent appearance of anterior teeth has also been shown to have important psychological and social impacts on patients creating significant emotional and social burdens for children and their families.6 Many children have also been shown to develop a negative attitude towards tooth brushing and oral hygiene following dental trauma, which can have severe impacts on oral health.7
To prevent the negative psychological, physical and emotional impacts of dental trauma, precise management and restoration of traumatized teeth is vital. Treatment should restore both function and aesthetics and increase the quality of life for patients. This case report discusses the management of an uncomplicated enamel–dentine crown fracture, with insufficient inter-occlusal restorative space using a multidisciplinary team (MDT) approach.
Initial presentation
A 20-year-old male patient presented complaining of a fractured upper central incisor, which had been traumatized playing football 3 years prior to the consultation. The patient had a history of multiple failed adhesive restorations and was now looking for a more definitive, aesthetic restoration. At presentation, the patient was asymptomatic, but was concerned about the appearance of his anterior teeth. The patient was medically fit and well, and a non-smoker.
Clinical examination revealed a horizontal, uncomplicated crown fracture of the UL1 with 50% loss of tooth structure (Figure 1). The patient was caries free and had good oral hygiene. The patient had a Class 1 incisal relationship with left and right lateral guidance in group function. UL1 had sufficient tooth structure to support an indirect restoration, but there was insufficient inter-occlusal space to accommodate this owing to an increased overbite and over-eruption of the opposing lower incisors. UL1 responded positively to thermal testing with ethyl chloride, and had no radiographic or clinical evidence of peri-apical pathology.
The patient had a Class I skeletal pattern with an average maxillary–mandibular plane angle. The patient had a Class I incisal relationship with an overjet of 2.5 mm and an overbite of 4 mm. There was over-eruption of the lower labial segment, in particular the LL1, leading to an edge-to-edge contact with the UL1. This resulted in a lack of both vertical and horizontal space for satisfactory restoration. The left and right molar segments also had a Class I relationship. The patient had 1 mm of crowding in the upper arch and 2 mm of crowding in the lower arch. The patient had no crossbites or displacement.
Treatment plan
The patient was assessed by an orthodontist and a restorative dentist. A treatment plan was formulated involving fixed orthodontic treatment followed by indirect restoration on the UL1. The treatment objectives were:
To relieve lower incisor crowding;
Create sufficient vertical and anterior-posterior restorative space for restoration;
Maintain Class I left and right buccal segments;
Provide definitive indirect restoration of the UL1 following orthodontic treatment.
Treatment options were discussed with the patient and restorative colleagues, and it was decided that, following initial hygiene therapy and oral hygiene instruction, the patient would have upper fixed full-arch ceramic appliances and lower fixed full-arch stainless steel appliances to align the teeth to fulfil the aims of treatment. Vertical restorative space would be created through intrusion of the UL1 and reduction in overbite through extrusion of posterior teeth and intrusion of lower incisors. Anterior–posterior restorative space would be created through an increase in overjet via inter-proximal reduction and marginal uprighting of the lower incisors. The UL1 would then be prepared and restored with a full-coverage ceramic crown. The upper and lower arches would be finished and retained using vacuum-formed retainers (VFR), with a new VFR being provided following resolution of restorative treatment and definitive restoration. The benefits and risks of surgical crown lengthening (SCL) were also discussed with the patient. The patient opted against treatment of this nature at this time.
Treatment progression
Following placement of upper ceramic brackets (3M Clarity, MBT prescription, 3M, USA) and lower stainless steel brackets (mini master series, MBT prescription, American Orthodontics, Sheboygan, WI, USA), 016 NiTi wires (GAC, Sentalloy, Dentsply, USA) were placed in both arches for initial alignment. Upper and lower 16/22 NiTi wires (GAC, Neosentalloy) were placed 5 weeks later.
Next, stainless steel brackets were bonded to the patient's upper and lower second permanent molars and glass ionomer cement (GIC) was placed on the occlusal surface of the patient's upper first permanent molars to disclude the posterior teeth and prevent de-bonding of the lower brackets during function. The upper and lower archwires were also replaced with 18/25 NiTi wires.
At the subsequent appointment, upper and lower 19/25 stainless steel wires were placed with a reverse curve of Spee bent into the lower archwire to intrude the lower incisors and reduce the patients' overbite, increasing vertical restorative space. The disclusion cement was also removed.
Next, an intrusion offset was bent into the upper 19/25 stainless steel wire to prevent extrusion of the UL1 and loss of inter-occlusal space. A total of 0.25 mm of interproximal reduction was completed on the left and right lower incisors to allow for their retroclination and an increased overjet in the UL1 region. A 018 stainless steel archwire with a reverse curve of Spee was placed in the lower arch. A closed-link powerchain and Class III elastics (American Orthodontics, Gorilla, 4½ oz) were also placed to further increase overjet and create additional inter-occlusal space for the UL1 (Figure 2).
Figure 2. Intrusion offset UL1 and interproximal reduction of lower incisors. (a) Anterior view. (b) Right buccal view. (c) Left buccal view. (d) Upper occlusal view. (e) Lower occlusal view.
At the following visit, vertical restorative space for the UL1 had increased, but more anterior–posterior clearance was needed for a predictable restorative outcome. A further 1.3 mm of interproximal reduction was completed on the lower incisors and canines to allow for additional retroclination. A new lower 018 stainless steel archwire with reverse curve of Spee was placed, along with a closed power chain extending from right to left lower first permanent molars. Class III elastics were continued to promote further increase in overjet.
Following this, impressions were taken and study models were reviewed. A restorative opinion was requested, and it was decided that further overbite reduction was required. The incisal edge of the LL1 was reduced to create further vertical restorative space for the UL1 and improve the lower arch aesthetics. It was also requested that the UL1 be extruded by 1–2 mm to allow for a more predictable restorative outcome, particularly on the palatal aspect of the fractured tooth.
To facilitate further reduction in overbite, anterior composite bite turbos were bonded palatally to the upper right central and the upper left lateral incisors (Figure 3) to create posterior disclusion and allow extrusion of posterior teeth. The UL1 was repositioned marginally through placement of a new upper 19/25 stainless steel archwire with no intrusion bend to level up the gingival height to the UR1 and prevent discrepant gingival margins.
There was now sufficient inter-occlusal space to accommodate indirect restoration of the UL1. Anterior composite bite turbos were removed and both upper and lower archwires were replaced. One month later, upper and lower de-bond was completed (Figure 4). Upper and lower impressions were taken using an irreversible hydrocolloid for study models, and fabrication of upper and lower VFRs. The patient was instructed to wear the upper VFR all day and all night (apart from at mealtimes) and the lower VFR at night only. The total orthodontic treatment time was 14 months.
Following generation of sufficient inter-occlusal space, the patient attended for reconstruction of the UL1. Initial impressions were taken using an irreversible hydrocolloid and sent to the dental laboratory for diagnostic mock-up of the UL1 to mirror the shape and anatomy of the contralateral tooth. The UL1 was then prepared for a lithium disilicate all-ceramic full-coverage crown with 1.5 mm reduction carried out on all surfaces and in all planes. Following preparation, a dual cord gingival retraction technique was used, and upper polyvinylsiloxane and lower irreversible hydrocolloid impressions were taken. A temporary restoration was fabricated with a bis-acryl based resin (Luxatemp, DMG, Hamburg, Germany) using a clear silicone matrix (Memosil 2, Hereaus-Kulzer, Newbury, Berkshire, UK) formed from the laboratory mock-up. This temporary restoration was cemented using a non-eugenol based temporary cement (TempBond NE, Kerr, CA, USA).
Following fabrication of the final restoration, the temporary crown was removed and the preparation was polished with pumice. The final crown was tried-in with a translucent try-in paste to assess fit and shade. Following rubber dam isolation, the tooth was selectively etched with phosphoric acid 15% and a layer of enamel bond was applied (Scotchbond, 3M). The final lithium disilicate crown was prepared with hydrofluoric acid for 90 seconds.
Silane was applied, and air dried before cementation with a dual-cure composite resin (Rely X Ultimate, 3M). Occlusion was reviewed in inter-cuspal position, protrusion and lateral excursions. Finally, an irreversible hydrocolloid impression was taken for a new upper VFR. The patient was delighted with the final restoration (Figure 5). The overall treatment time for this case was 15 months.
At the 1-year review, no orthodontic relapse was seen. The patient remained very happy with the aesthetics and function of the final restoration.
Discussion
Cases with localized insufficient inter-occlusal space to accommodate a restoration can be challenging to manage. The prognosis of an indirect restoration is directly proportional to the amount of available remaining tooth structure and the subsequent height of the tooth preparation. A minimum of 4 mm axial height for posterior preparations and 3 mm for anterior preparations is recommended for indirect restorations to have adequate retention and resistance form.8 Teeth must also have an adequate amount of reduction to accommodate the restorative material of choice. In cases with insufficient inter-occlusal space, where the existing occlusion is being conformed to, additional tooth preparation is needed to sufficiently accommodate restorative material. This increases the risk of pulpal damage, and can compromise the vitality of prepared teeth9. Furthermore, additional preparation will lead to a reduction in preparation height resulting in reduced retention and resistance form.8
To avoid overpreparation of teeth in cases with localized insufficient inter-occlusal space, alternative treatment options include increasing the patients' occlusal vertical dimension (OVD) and SCL.9 Crown lengthening is a surgical intervention that aims to increase the amount of tooth tissue available for preparation through the apical repositioning of gingival tissues with or without the removal of alveolar bone.10 SCL is an invasive procedure, and the aesthetic implications of soft tissue surgery in the anterior maxilla must be considered. Performing SCL on a single tooth is likely to lead to discrepant gingival margins.10 This will have a negative impact on the patient's appearance as the symmetry of the gingival margins of the central maxillary incisors is an essential part of an aesthetic smile.11 Alteration of OVD is therefore a more acceptable alternative to SCL in anterior single tooth cases where the aesthetics of the final outcome are of primary concern.
Increase in OVD to gain sufficient inter-occlusal space can be achieved through orthodontic intervention.12 This is increasingly appropriate when other aspects of occlusion require treatment.13 Orthodontic intervention gives control of bodily tooth movements both vertically and horizontally to generate the space needed for successful restoration.14 Vertical inter-occlusal space can be created through implementation of the Dahl concept, which refers to the axial tooth movements observed when localized appliances or restorations are placed in supra-occlusion and the occlusion is re-established over time.13 Anterior bite platforms can be used to implement this concept and result in the extrusion of posterior teeth leading to a reduction in overbite and the generation of localized vertical inter-occlusal space.15 Bite turbos can be used in a similar way and have additional advantages to removable appliances including prevention of accidental bracket debonding, improving the effect of light wires and increased patient comfort during treatment.16
Interproximal enamel reduction of incisors is a successful and safe way to generate space for orthodontic treatment.16,17 Enamel reduction in this case, allowed for marginal uprighting of the lower incisors resulting in increased overjet. This in turn, increased anterior–posterior space for indirect restoration.
Material choice for indirect restoration is dependent on a variety of factors, including remaining tooth structure, aesthetics, occlusal loading and financial implication for the patient. Lithium disilicate, layered zirconia and porcelain fused to metal crowns, have been found to be the most popular choices of restorative materials for single unit anterior indirect restorations.18 When replacing anterior teeth, the aesthetics of the final restoration must be considered. Lithium disilicate restorations are more translucent than zirconia restorations and, therefore, have superior aesthetics in the anterior region, providing there is no requirement to mask underlying tooth tissue.19 Furthermore, lithium disilicate crowns can be etched with hydrofluoric acid and chemically bonded to enamel with silane primer and an adhesive resin, giving them superior retention compared to layered zirconia, providing there is sufficient enamel for bonding.20 If there is little enamel remaining to achieve the necessary bond strength, then an alternative, such as porcelain fused to metal, or layered zirconia restorations, would have to be considered.21
Conclusion
This case highlights the complexities that can arise in the treatment of dental trauma, especially those associated with delayed presentation. Through careful planning and an MDT approach, localized insufficient inter-occlusal space can be safely and predictably managed using orthodontic treatment to generate both vertical and anterior-posterior restorative space to allow for successful definitive indirect restoration of both function and aesthetics.
