Talon Cusp Management: A Case Series

Case 1

A fit and healthy 11-year-old female patient was referred to the paediatric dentistry department regarding a labially displaced maxillary right central incisor UR1 with a palatal accessory cusp. The patient was primarily concerned about the labial position of UR1, which had a well delineated palatal talon cusp extending subgingivally towards the mesial aspect of the incisal edge of UR1 (Figure 2). She presented with a Class II division 1 incisor relationship on a Class I skeletal base, increased vertical proportions and mild bimaxillary proclination. Both upper and lower arches were well aligned apart from the displaced UR1, which was associated with a 5 mm overjet (Figures 3 and 4).

The talon cusp created an occlusal interference causing labial displacement of the tooth that was of aesthetic concern to the patient (Figure 4). A pre-operative long cone peri-apical radiograph demonstrated a radiopaque ‘v-shaped’ structure superimposed over the crown of the tooth, with a pulpal projection extending into it (Figure 5). The UR1 was mature with a closed apex and no evidence of caries or peri-apical pathology. It responded positively to both thermal and electric sensibility testing.

Cone beam computed tomography (CBCT) clearly demonstrated the bifurcation of the pulp chamber UR1, with a buccal and palatal pulp horn (Figure 6).

Owing to the subgingival projection of the talon cusp, and the extent of the labial displacement, complete removal of the talon cusp was deemed the most appropriate treatment option. Leaving the talon cusp would have prevented orthodontic alignment of the UR1 and the subgingival extension was a local risk factor for caries and periodontal deterioration in the anterior maxilla. The patient opted for treatment under inhalation sedation. To expose the talon cusp fully, a palatal flap was raised extending from UR3 to UL2. The talon cusp was removed completely with a high-speed diamond bur. This resulted in a small supragingival pulpal exposure and a 2-mm partial pulpotomy was completed. Bleeding was arrested using a saline soaked cotton wool pledget and Biodentine (Septodont, Saint Maur des Fosses, France) was placed over the vital pulp tissue (Figure 7). Once set, the tooth was then restored definitively with a composite restoration. Owing to difficulties in placing rubber dam following exposure of the surgical site, moisture control was achieved using OptraGate (Ivoclar Vivadent, Schaan, Liechtenstein), cotton wool rolls and high-powered suction.

The flap was replaced and a small palatal gingivectomy was undertaken to fully expose the clinical crown of UR1 (Figure 8).

The labial displacement of UR1 had resulted in a loss of space in the maxillary arch, so the patient was fitted with an upper removable appliance (URA) with a labial bow and palatal finger spring to distalize UR2 and re-align UR1, 6 months following the partial pulpotomy (Figure 9).

The tooth was monitored for 13 months, remaining asymptomatic with no pathological mobility, and continued to respond positively to sensibility testing with no evidence of peri-apical pathology (Figure 10).

Case 2

A 12-year-old female patient was referred to the paediatric dentistry department regarding a palatal talon cusp on UL1. Medically, the patient had bilateral hearing aids and a history of iron deficiency anaemia, for which she was taking ferric sulphate.

The UL1 talon cusp was conical in shape, extending towards the incisal tip from a subgingival position (Figures 11 and 12). The talon was causing labial displacement of UL1 and lingual displacement of LL1. The patient had a Class II division 1 incisor relationship on a Class I skeletal base with average vertical proportions and the overjet was 5.5 mm to the UL1 (Figure 13).

CBCT views clearly demonstrated the bifurcation of the pulp chamber UL1 with a buccal and palatal pulp horn, the latter extending into the talon cusp. The cusp itself extended to within 1.5–2.5 mm of the palatal enamel surface of the incisal tip of the main crown (Figure 14).

Similarly to the first case, after full discussion of all available treatment options, the patient opted for complete surgical removal of the talon cusp to allow correction of the labial displacement. Aesthetically, this case was slightly less severe than the first, but still a concern to the patient. Selective reduction of the talon cusp was an alternative option. This would have been difficult to achieve due to the subgingival extension of the talon cusp and would have required greater time commitment from the patient and her parents to attend multiple treatment appointments. A palatal flap was raised, under local anaesthetic, extending from UR2 to UL3 to expose the talon cusp. The talon cusp was removed using a high-speed diamond bur, resulting in less than 1-mm pulpal exposure and a 1-mm partial pulpotomy was completed. Haemostasis was achieved using light pressure from a saline-soaked cotton wool pledget and Biodentine (Septodont) was placed over the exposed pulp. Again, moisture control was achieved using OptraGate (Ivoclar Vivadent), cotton wool rolls and high-powered suction. The tooth was restored with composite, and the flap was repositioned and sutured.

The patient was reviewed at regular intervals for a 12-month period. The UL1 continued to respond to sensibility testing and there were no clinical or radiographic signs of peri-apical pathology (Figure 15). Spontaneous realignment of the displaced incisors occurred due to pressure created from the soft tissues, as described by the equilibrium theory, following complete removal of the talon cusp (Figure 16).⁹

Case 3

A fit and healthy 10-year-old female patient was referred to the paediatric dentistry department regarding labially inclined maxillary lateral incisors, both with palatal accessory cusps and possible dens invaginatus.

Both the UR2 and UL2 had prominent palatal pyramidal accessory cusps with deep pits. These invaginations can both be described as Oehlers classification Type II – they extend beyond the CEJ, but do not communicate with the periodontal ligament (PDL).¹⁰ The patient had a Class II division 2 incisor relationship on a Class I skeletal base with reduced vertical proportions. The UR2 and UL2 were labially displaced and the talon cusps extended 1 mm subgingivally, with the patient's overjet measuring 5.5 mm to the maxillary lateral incisors (Figure 17). The maxillary central incisors were retroclined, and her occlusion was further complicated by transposition of LL2 and LL3 (Figure 18).

CBCT views showed that the UR2 had a prominent palatal talon cusp and cingulum invagination that extended towards the pulp chamber, but did not dilate the tooth (Figure 17). The UL2 also had a prominent palatal cusp, and two palatal invaginations into dentine placed mesially and distally (Figure 17). The roof of the UL2 pulp chamber passed in between the two invaginations.

Following multidisciplinary assessment, the patient opted for complete removal of the talon cusps to allow for orthodontic correction of the Class II malocclusion and alignment of the upper incisors. Treatment was completed under local anaesthetic and, unlike the first two cases, the teeth were isolated using rubber dam because the amount of tooth structure removal required to facilitate orthodontic alignment was supragingival. Owing to the complex anatomical pattern of the pulp chamber, magnification and illumination using a microscope was used. The UL2 talon cusp was removed using a high-speed bur. The small mesial and distal invaginations were explored using ultrasonics, which resulted in a pulpal exposure mesially. A 1-mm partial pulpotomy was completed, haemostasis was achieved using light pressure from a saline-soaked cotton wool pledget and Biodentine (Septodont) was placed over the remaining coronal pulp followed by a definitive composite restoration. Removal of the UR2 talon did not result in a pulpal exposure and the tooth was conventionally restored with a palatal composite restoration.

The long-term treatment plan is to monitor UR2 and UL2 and commence orthodontic treatment 6 months post-operatively, if the teeth are clinically and radiographically stable with no signs of pulpal necrosis.

Discussion

The aetiology of talon cusps is not fully understood; however, it has been suggested that during the morphodifferentiation stage of tooth development, talon cusps result from hyperactivity of peripheral cells of the dental papilla as well as the enamel organ folding outwards.¹¹ They may be referred to in the literature as dens evaginatus of the anterior teeth. Talon cusps have also been reported to occur in association with numerous syndromes. This list includes, but is not restricted to: oral facial digital syndrome 2 (Mohr syndrome); Sturge Weber syndrome; Ellis–Van Creveld syndrome; Rubinstein–Taybi syndrome; and Alagille syndrome.^11,12 In non-syndromic cases, talon cusps can present alongside other dental anomalies including ectopic canines, transposition, supernumerary teeth and dens invaginatus¹¹ – Case 3 in this series is an example of this.

Talon cusps requiring operative intervention need thorough assessment to formulate the most appropriate treatment plan, often necessitating a multidisciplinary approach with an orthodontic and restorative input. Careful pre-operative radiographic evaluation is crucial as the talon cusp is often superimposed over the crown of the tooth and can appear as a ‘v-shape’ radiopaque structure.¹² If the tooth is yet to erupt, this may cause diagnostic issues as the radiographic appearance can be mistaken for a mesiodens or compound odontome.¹² This may result in an unnecessary surgical procedure to remove a suspected supernumerary.

The superimposition can also make pulp canal anatomy of erupted teeth difficult to trace solely using conventional 2-dimensional imaging.⁸ The European Society of Endodontology position statement advises CBCT may be indicated to assess ‘anatomically complex root canal systems prior to endodontic management’, only if thorough clinical examination and conventional radiographs do not provide sufficient information.¹³ CBCT enables accurate interpretation of the location and anatomy of the pulp and, therefore, can increase the likelihood of successful outcomes.¹³ Three-dimensional imaging in the first two cases was also useful in determining the subgingival extent of the talon cusp and whether complete removal was a viable option. CBCT views meant that the invaginations were clearly diagnosed in Case 3, and the patient was advised that the deep pits into the pulp space are a common route for bacterial ingress, which negatively impacts on maintaining pulp vitality and prognosis.¹⁴

Dens invaginatus, also known as dens in dente, is an abnormality that occurs during tooth development caused by the enamel organ infolding into the dentinal papilla.¹⁵ The reported prevalence ranges from 0.3% to 10%, and the most commonly affected teeth are permanent maxillary lateral incisors – as demonstrated by Case 3.¹⁵ Depending on the type and extent of the invagination, associated periodontal lesions may be present. 3D imaging can therefore be useful not only to visualize the morphology of the pulp canal and invagination, but also assess surrounding bone volume and peri-radicular tissues.¹⁶ Complex pulpal anatomy and enamel-lined invaginations in non-vital cases can pose difficulties in achieving optimal chemo-mechanical debridement necessary prior to obturation.¹⁷ A further complication may be a lack of apical constriction where invaginations communicate with the PDL, and this may require similar obturation techniques used to manage immature or resorbed apices.¹⁷ Periodontal involvement can require surgical assessment if infrabony defects are present.¹⁸

After comprehensive assessment, the most suitable treatment option for talon cusps must be determined having discussed the risks and benefits of each treatment modality with the patient/parent. In all three cases, the talon cusps needed to be eliminated to facilitate orthodontic treatment and to overcome occlusal interferences. The two available options for this were gradual reduction or complete removal of the additional cusps. Measured, periodic reduction of talon cusps induces a pulpal response and the formation of tertiary dentine. It has been suggested that the full length of the cusp should be reduced during sequential grinding, rather than just the incisal tip, in order to promote a greater amount of reparative dentine formation as the majority of the odontoblasts are located along the length of the cusp.^7,11 Fluoride varnish should be applied after each visit to minimize the risk of sensitivity and 1–1.5 mm should be removed every 6–8 weeks.⁷

Young patients often have large pulp chambers, meaning that the greatest risk with complete removal over progressive grinding of the talon cusp is pulpal exposure.⁷ In this series, a partial pulpotomy was undertaken following pulpal exposure. Partial pulpotomy is defined as the removal of a portion of vital pulp tissue, usually 1–3 mm, and the application of a therapeutic material – Biodentine (Septodont) was used in this series – in order to preserve the vitality of the remaining portion.^19,20,21 Partial pulpotomies are more conservative of the cell-rich coronal pulp compared with cervical pulpotomies, and this is beneficial as it has a greater capacity to facilitate healing than that of radicular pulp.¹⁹ The capacity pulpal tissue has for repair is largely dependent on hygienic operating conditions. Owing to the talon cusp anatomy, the pulpotomies in the first two cases could not be completed under rubber dam as a palatal flap was necessary. However, OptraGate (Ivoclar Vivadent) retraction and cotton wool rolls were used throughout the procedures to achieve moisture control and maintain as an aseptic as possible operating field.

Failures following vital pulp therapy most commonly occur within 2 months of the procedure.²¹ The first two cases have had at least 1 year of follow-up, and the treatment performed has maintained vitality of the affected teeth. Clinical signs of success of the partial pulpotomy treatment in this series were defined as: an absence of pain or sensitivity; positive responses to sensibility testing; no tenderness to percussion; no pathological mobility; and no swelling or sinus presence. Radiographic success was defined as normal periodontal ligament space, no apical pathology and no internal or external pathological resorption. The post-operative radiographs of the first two cases met these criteria (Figures 10 and 15). Post-operative radiographs in Case 3 showed radiographic signs of success at the 4-week review.

The success of partial pulpotomies in the literature ranges from 42–100%.^19,20 The various medicaments that can be placed directly over the pulp are, calcium hydroxide or bioceramic cements such as mineral trioxide aggregate (MTA) or Biodentine (Septodont).¹⁹ Calcium hydroxide allows for dentine bridge formation, hence its use as a pulp-capping agent.²² Predictable pulp tissue healing and the formation of a hard-tissue barrier also occurs when MTA is used in pulpotomies.^21,22 However, the use of MTA in anterior teeth carries a risk of discolouration and subsequent aesthetic issues due to the inclusion of the radiopacifier bismuth oxide.²² Biodentine (Septodont), when used as a direct pulp-capping material, has been shown to induce differentiation of odontoblast-like cells and the formation of mineralized tissue similar to that of MTA.²³ The main advantages of Biodentine over MTA are reported superior handling properties, shorter setting time and good colour stability.²³ Regardless of which material is used, the sealing capacity is paramount because it is bacterial ingress during pulpal healing that is the leading cause of failure in vital pulp therapies.²¹

Conclusions

Talon cusps are clinically important anomalies because they can cause plaque and bacterial accumulation leading to caries and pulpal pathology. The morphology of the cusps themselves can act as an occlusal interference or lead to periodontal tissue damage secondary to occlusal trauma, among other clinical issues. The management of patients with talon cusps may require a multidisciplinary team approach, including paediatric dentistry, orthodontics and restorative dentistry. It is important for dentists to be aware that talon cusps can occur in association with other dental anomalies and syndromes, and a thorough history and clinical assessment is necessary to identify these and arrange an onward referral if appropriate.

The complete removal of talon cusps followed by a partial pulpotomy has advantages over selective grinding as it involves fewer treatment visits for patient with high success rates in preserving pulpal vitality.^19,20 There is, however, a need for long-term studies of treatment outcomes to compare the effectiveness of complete removal of talon cusps over selective grinding.