The natural tooth pontic: a novel approach

Case report

An 80-year-old female patient presented complaining of a loose lower front tooth. She explained that the tooth had become progressively loose and, although currently asymptomatic, she had suffered multiple abscesses. Medically, this patient suffered from rheumatoid arthritis and back pain. She had previously been diagnosed with Malignant Peripheral Nerve Sheath Tumour (MPNST) in the post nasal space with extension to the left orbit and frontal lobe. This had been treated by endoscopic craniofacial resection of the tumour and radiotherapy in 2013. She had subsequently undergone a nasal reconstruction procedure.

She found attending appointments difficult, having a long journey and relying on hospital transport. Owing to her back, it was also difficult to sit in the dental chair for long periods. She had been a regular attender to her general dental practitioner, brushed twice a day with a manual toothbrush but admitted that brushing was challenging owing to the effects of rheumatoid arthritis on her hands.

Extra-oral examination was unremarkable except for nasal collapse (Figure 1). She had a young biological age and took great care in her appearance. On speaking and smiling the lower incisors were visible, but the gingival margins did not show.

Intra-oral examination (Figure 2) demonstrated normal soft tissue appearance and a good quality and quantity of saliva. She was partially dentate, the teeth present being:

She wore a partial acrylic resin denture in the maxillary arch replacing the incisors and right premolars. There was a reduced mandibular dental arch and obvious supragingival calculus and plaque deposits in each sextant. There was no caries. The LR1 and LL1 were grade 1 mobile, whilst the LR1 was also tender to percussion and had a negative response to sensibility testing with ethyl chloride. The LL1 and LR2 were not tender to percussion, had vital responses to ethyl chloride and were asymptomatic (Figures 3, 4). The LR2 was not mobile. A periapical radiograph (Figure 5) of LR2, LR1 and LL1 demonstrated a vertical pattern of bone loss of 80% around the lower central incisors and 50% on the LR2. Supra- and subgingival calculus was clearly visible interdentally. A periapical radiolucency was apparent on LR1, as was sclerosis of the pulp canal.

Treatment stages

Following a stabilization stage, including oral hygiene instruction, in particular, use of electric brush and scaling, the treatment was performed as follows:

Impression of lower arch prior to extraction of LR1. This was carried out uneventfully using an addition-cured medium and light-bodied silicone twin mix technique. If there has been greater mobility of teeth, undercuts may have been blocked out using wax prior to the impression, or the impression could have been taken in alginate and cast immediately in the lab.

Laboratory construction of an IPS e.max retainer on the lingual aspect of the crowns of LR21, covering the full lingual crown height (Figure 6).

A silicone putty index was then formed over the cast, to capture the position of the LR1 and two teeth either side of this for stability. This was made by adapting the silicone putty to the labial aspect and just overlapping the incisal edges (Figure 7). The index was then confirmed in the mouth.

The e.max retainer was tried in, confirming its fit against the LR2 and LR1.

Local anaesthesia (Dentsply Xylocaine 2% with adrenaline 1:80,000) was administered as buccal and lingual infiltrations of LR1.

The gingival level was marked on the LR1 using a bur.

Following atraumatic extraction of LR1 using root forceps, haemostasis was achieved by applying pressure for 5 minutes with gauze dampened with saline. Using a bur, the LR1 was then decoronated at the appropriate level. A retrograde preparation of the pulp cavity was performed and irrigated with sodium hypochlorite. The root end was then etched, bonded and sealed with composite resin. A modified ridge lap pontic was made (Figure 8).

Bonding of natural pontic to IPS e.max retainer with Calibra Esthetic Resin Cement (Dentsply). The retainer was etched with 9% hydrofluoric acid etch for 90 seconds, washed and dried, then silanated. The LR1 was etched for 60 seconds and dental bonding agent applied and light-cured for 20 seconds. The resin cement was then applied to the e.max retainer and the LR1 crown cemented using the putty index to aid correct positioning.

The LR2 was cleaned with pumice powder and water slurry and washed and dried. Moisture control was achieved using cotton wool rolls and the aspirator tip.

The putty index was then used to carry the pontic and wing to LR2 and confirm positioning in the mouth.

The LR2 was etched for 60 seconds, dental bonding agent applied and cured before using Calibra in the same manner as described in Stage 8 to bond the IPS e.max retainer to LR2 lingual aspect.

The occlusion was checked and the LR1 pontic adjusted using composite finishing burs to ensure light contact of LR1 pontic in intercuspal position, but with no contacts in excursive movements.

Figures 9, 10 and 11 present postoperative views.

Discussion

Anterior teeth are often lost due to traumatic injury or periodontal disease. The number of solutions for immediate replacement have been described, including the provision of a single tooth on a removable acrylic prosthesis, use of a prefabricated acrylic tooth as a pontic splinted to adjacent teeth, immediate bridgework or an implant.

If not grossly carious or discoloured, an extracted tooth can be used as a natural pontic and splinted to a stable adjacent tooth. The natural pontic provides the characteristics of colour, shape, size and alignment without the need for substantial modifications and avoids the patient having to wear a removable prosthesis. This approach has been described in the dental literature for over 30 years. It enhances the psychological and social acceptability of an extraction and offers a conservative option for tooth replacement.

For this approach to be used, the abutment tooth must be intact or minimally restored and have substantial enamel available for bonding. Candidates for a natural tooth pontic include periodontally involved teeth, teeth with fractured roots and teeth unsuccessfully replanted after avulsion or following failed endodontic procedures. Contra-indications include parafunctional habits, insufficient coronal tooth structure, insufficient occlusal clearance for a splint and an inability to maintain isolation during bonding procedures.

Techniques described include pure composite resin, twist-flex wire, metal or nylon meshwork, fibre reinforced composite resin, a cast metal framework¹ and even one technique describing the use of palatal archwire and orthodontic bands.² Many of the options could be available for use at an emergency appointment.

IPS e.max is an all-ceramic material used in dentistry for inlays, veneers, crowns and bridges.³ Available from Ivoclar Vivadent, the IPS e.max system offers materials for both Press and CAD/CAM applications. Being a lithium disilicate glass ceramic, it has a flexural strength of 400 MPa⁴ and, owing to its ability to be etched, can form a strong resin–ceramic bond through the use of hydrofluoric acid etching and silane application.⁵ All-ceramic prostheses can also provide an aesthetic and biocompatibility advantage when compared to metal-ceramic structures.⁶ It has therefore been used to great effect in anterior fixed prosthesis.^7,8

The cost of a laboratory constructed ceramic retainer compared to a metal retainer or a direct technique should be considered and may present a barrier to its use. In addition, the evidence for resin-bonded bridges supports the use of metal retainers for resin bonding over all-ceramic or fibre-reinforced resins in terms of long-term survival.^9,10 A literature review estimated the annual failure rates per year to be 4.6% for metal-framed, 4.1% for fibre-reinforced and 11.7% for all-ceramic resin-bonded bridges.¹¹ The most frequent complications include debonding of metal-framed resin-bonded bridges, delamination of the composite veneering material in fibre-reinforced bridges, and fracture of the framework of all-ceramic bridges. In this case, the NTP was opposed by a removable acrylic resin tissue-supported denture which would reduce occlusal load on the bridge compared to a natural dentition or fixed restoration.

Conclusion

The use of a natural tooth pontic in this 80-year-old female patient allowed an immediate, aesthetic and functional result which permitted good oral hygiene and prevented the need for a removable partial denture. Considering the patient's age and evidence relating to longevity of e.max bridgework, this restoration will be monitored as a long-term treatment modality.