Single Appointment Aesthetic Replacement of Anterior Tooth with Fibre Reinforced Natural Tooth Pontic- A Report of Two Cases.

INTRODUCTION

Missing teeth are most often replaced for reasons related to cosmetics, masticatory function, phonetics, and space maintenance¹. Although an anterior tooth has mechanical functionality, it is the compromised facial aesthetics associated with tooth loss is the patient's primary concern. Whether the tooth is removed surgically or lost due to trauma, the dentist is forced to consider an immediate means to satisfy the patient's cosmetic requirements in such situations. Tooth loss in the anterior region is for most patients a deeply traumatic experience. 

Various clinical techniques have been described for the immediate replacement of anterior teeth. Selection of a procedure for particular situation requires consideration of several factors such as, conservation; natural preservation, minimum invasion, aesthetics, cost as well as prosthesis biocompatibility and oral hygiene maintenance². The replacement can be temporary, semi-temporary or permanent in nature. Depending on many clinical and economic factors, the selection of definitive treatment for missing teeth can vary between removable prosthesis, tooth-supported prosthesis and the increasingly popular implant supported prosthesis.

Immediate replacement of the extracted teeth with partial denture or implant supported prosthesis may not be the best treatment option, not only because of cost but also due to minimal bone support³. Partial dentures can jeopardize the periodontal health of the remaining teeth and induce gingival changes according to the denture-gingiva relationship⁴. Tooth supported prosthesis require additional tooth preparation and complicated laboratory fabrication⁵. Use of prefabricated acrylic denture tooth as a pontic bonded to adjacent teeth was a reliable treatment choice but it can present challenges in regard to matching colour, size and shape, and may require modifications to achieve an acceptable appearance⁶. Using patient's own natural tooth as a pontic offers the benefits of being the right size, colour, shape and also allows for repositioning of the extracted tooth in its original intraoral position.

Previous attempts at adding an extracted natural tooth as a pontic to the adjacent teeth with adhesive composite resins⁷ were with wire, metal mesh and cast metal frameworks. The inherent problems associated with them were their inability to be chemically incorporated into the dental resin and failures due to the repeated loading stresses placed on the bridge, during normal and parafunction. To overcome this, increased bulk and thickness of composite resin was used, which led to increased plaque retention⁸. Since composite splints showed a high frequency of failures due to fracture through the material, efforts have been made to reinforce them⁹.

The challenge to place a thin but strong, bonded composite resin-based single visit bridge was met with the introduction of a high strength polyethylene, bondable, biocompatible, aesthetic, easily manipulated, fibre ribbons that could be embedded into a resin structure. The two most important mechanical properties of fibre reinforced resins are strength and stiffness. Ribbond® (Ribbond, Seattle, WA, USA)is a plasma treated, bondable, polyethylene-woven reinforcement ribbon for composite resin which provides an increase in flexure strength and flexure modulus of resins that resists cracking⁸. Clinically successful uses of woven fibre reinforcement ribbon have been described in the dental literature including periodontal splinting^9,10, restoration of the endodontically treated tooth¹¹ where fibre connected the pontic to the abutment teeth with strength and retention greater than conventional composite bonding systems alone⁵. 

The present article is a report of 2 cases that describes the integration of aesthetic and functional factors in single appointment replacement of periodontally weak anterior teeth, as a natural tooth pontic with fibre ribbon reinforced composite resin technique.

CASE REPORT 1

A 37 year old male patient reported to the Department of Periodontology, Bapuji Dental College and Hospital, Davangere, Karnataka with a chief complaint of loosening of upper front tooth. He expressed his desire to retain the loose teeth by minimal invasive, cost effective, fast and immediate treatment procedure. On examination, upper right central incisor showed Grade III mobility and Miller's Class II gingival recession (Fig. 1), periodontal status of the remaining teeth was fair. Patient had satisfactory oral hygiene maintenance. 

The problem was discussed with the patient and knowing his concern and anxiety for aesthetics, decision was made to extract the grade III mobile tooth 11, following which fabrication of a single visit fibre ribbon reinforced composite resin bridge, by using the crown of extracted tooth as a natural tooth pontic was planned. After explaining the pros and cons of treatment procedure, a written consent was obtained from the patient. Oral hygiene instructions were given and thorough scaling and polishing was done.

TECHNIQUE

Prior to extraction of tooth 11, the length of the natural tooth pontic (NTP) was marked by measuring the distance from its mid-incisal edge to gingival margin, by adding 3-4 mm of additional length to compensate for the expected tissue shrinkage during healing. Tooth 11 was extracted under local anaesthesia (2% lignocaine hydrochloride containing 1:80,000 epinephrine), followed by socket compression with digital pressure for haemorrhage control (Fig. 2).

The extracted tooth was thoroughly cleaned and sectioned transversally at the marking with a rotary disc (Fig. 3A, 3B).  

The remaining amputated root part was discarded. The pulp tissues of 11 (NTP) were extirpated and root canal was enlarged by endodontic files and reamers from its apical end and incrementally sealed with flowable composite. A bullet shaped ovate design was given to the cervical area of NTP. An intra-coronal channel with a width of 3-4mm and depth of 1- 2mm was prepared on the middle third of lingual surface of the NTP (Fig. 3C). The required length of fibre strip was measured with a dental floss on the diagnostic cast, which was made before extraction. Using floss as a template, the ® Ribbond strip was cut with scissors and placed on a clean covered surface until its use. The abutment teeth were scaled, polished, root planed and thoroughly rinsed and air dried.

The NTP was temporarily stabilized in position with composite resin on facial surface without acid etching and bonding, to minimize distortion during treatment. After isolation, plastic wedges were placed in the embrasure area to limit the resin flow and to make interdental oral hygiene maintenance easy for the patient. On the lingual and proximal surfaces, enamel of the abutment teeth and pontic were acid etched with 35% phosphoric acid (Scotchbond^TM , 3M-ESPE, St. Paul, MN,USA) for 30 seconds and later rinsed and air dried. Bonding agent (Prime & Bond® , Dentsply, PA, USA) was applied on the etched surfaces and light polymerized with LED curing unit (Elipar Free Light II, 3M/ESPE, St. Paul, MN, USA; light intensity:1000mV/cm2) for 40 seconds. A TM thin layer of composite resin (Filtek P60, 3M-ESPE, St. Paul, MN, USA) was placed on etched and bonded lingual surfaces and then the premeasured fibre ribbon wetted with bonding agent was pressed into the composite resin and closely adapted to the lingual contours of upper anteriors. Polymerization of the fibre strip was done in a step-wise manner. After final verification of the correct position, a layer of composite resin was applied over the fibre to coat it completely and polymerized. This provided additional strength and a smooth polished surface. Occlusion was evaluated with articulating paper and premature contacts were eliminated. The composite was then finished and polished with carbide finishing burs and polishing discs. The temporarily placed composite resin on facial surfaces of upper anteriors was removed with hand instruments (Fig. 4).

The patient was asked to follow strict oral hygiene maintenance by using soft tooth brush and interdental aids. On recall visits (1 week, 1 month, 3 months and 6 months), patient showed a satisfactory oral hygiene maintenance. He expressed his satisfaction for functional and aesthetic outcome of treatment at one year recall (Fig. 5) without any postoperative complications around soft and hard tissues of upper anteriors. 

CASE REPORT 2

A 65 year old healthy male patient reported with a chief complaint of loosening of teeth in lower front tooth region. On examination, lower left central incisor 31 showed Grade III mobility and Miller's Class III gingival recession whereas adjacent teeth 32 and 41 had Grade I mobility and Miller's Class I gingival recession. Minimal probing depth with trauma from occlusion was observed in relation to lower anteriors. Intra oral periapical radiograph (IOPA) revealed bone loss extending up to the apical third in relation to tooth 31 and up to the middle third in relation to teeth 32 and 41(Fig. 6). The possible treatment options were explained to the patient. Since the patient was reluctant to undergo an elaborate prosthodontic treatment, it was decided to extract the tooth and use the extracted tooth crown as a natural pontic for immediate replacement using a fibre ribbon reinforced composite resin bridge. The treatment was explained to the patient and a written informed consent was taken. Figure 7 shows the immediate post-operative view and outcome at one year recall. 

DISCUSSION

Loss of anterior teeth due to periodontitis, trauma or any other cause is aesthetically more concerning for the patients. Hence patients demand an attractive provisional solution immediately after extraction of these teeth.

The most challenging decision to replace such tooth involves the selection of an effective treatment modality, which depends on numerous objective and subjective factors that are specific for particular situation. Adhesive bonding of an extracted tooth to the adjacent teeth as a NTP was found to be quite successful over several years to consider as a long term provisional restoration.^12,13

In both the cases, though a single NTP was planned, the adjacent teeth on either side of extracted tooth showed a fair periodontal support, which were considered to be non-satisfactory abutments. Clinical report suggests that mobile teeth with reduced hard and soft tissue support benefit by splinting them together¹⁴ . Therefore the bridge was extended laterally by incorporating sound abutment teeth on either side. Hence it provided dual function of replacement of missing tooth along with splinting action on adjacent mobile teeth. It also served as a protective covering over the extraction site, preventing debris and contaminants from entering the surgical area and also allows the surgically altered tissues to fully mature in preparation for the definitive fixed prosthesis.¹⁵

Fibre reinforced composite exhibit different mechanical properties in different configuration. A woven configuration of Ribbond provided strength to take load from different directions compared to unidirectional fibre composites¹⁶. The effect of plasma treatment on the fibres of Ribbond® was not only to increase the wettability, but also for the creation of a chemical bond between the polyethylene fibre and the resin¹⁷. The degree of chemical bonding between the resin and fibre along with its woven structure prevents crack propagation within the resin matrix¹⁸. The reinforcement of these fibres have been shown to increase the flexural strength and fracture toughness of composite resin restorations and this helps to prevent fracture due to high stresses associated with mastication¹⁹. These fibres are made for chair-side use in a single appointment procedure that requires no special treatment preparation or instrumentation⁹. The susceptibility for surface contamination of these fibres was prevented by using clean cotton pliers during handling and by storing them in a clean covered surface till its use.

A bullet shape design was given to the cervical area of NTP to prevent its contact with the healing tissues, to make it easy for the patient to maintain oral hygiene and to complement the emerging profile²⁰. Intracoronal channel prepared in the midlingual section of NTP ensures maximum adhesion and durability²¹ by increasing the bulk of composite resin and by creating a room for the reinforced fibre ribbon, during its bonding to the adjacent natural teeth. Use of acid etch technique for the abutment teeth avoids irreversible preparation of intact adjacent teeth.⁷

Because of its strength, adaptability of various shapes and potential for direct bonding to tooth structure²¹, the described fibre reinforced composite resin technique for natural tooth pontic may be considered as a definitive alternative in certain situations. It is an affordable and fast solution for patients who reject more invasive treatment. 

Though the method is technically demanding and takes sufficient time for installation, it offers the advantages of excellent aesthetic results, preserves natural crown structure, replaces extracted tooth at the same appointment, causes less psychological trauma to the patient and avoids the sophisticated laboratory requirement, thereby reducing the cost of treatment. The pontic's micro-resilience stimulates the underlying tissues and avoids excessive ridge resorption after the extraction²⁰. Its reversibility due to non-invasiveness for abutment teeth permits exploration of other traditional definitive treatment options for single tooth replacement.

Although this technique was used for an interim method of anterior tooth replacement, its natural preservation, conservative preparation, cost effectiveness and reported success suggest that, it can be considered as a predictable procedure. This treatment option reflects the dentist's concern for the patient's facial disfigurement. But its success mainly depends on the right case selection, precise clinical skill of a dentist and manual dexterity of a patient for proper oral hygiene maintenance. Further studies are needed to evaluate the long-term functional and durable result of this technique in different situations with patient's satisfaction rating.

ACKNOWLEDGMENTS

The authors do not have any financial interest in the companies whose materials are included in this article. 

MANUFACTURER NAME

Ribbond® : Ribbond, Seattle, WA, USA 

35% phosphoric acid: Scotchbond^TM, 3M-ESPE, St. Paul, MN, USA

Bonding agent: Prime & Bond® , Dentsply, PA, USA

LED curing unit: Elipar Free Light II, 3M/ESPE, St. Paul, MN, USA 

Composite resin: Filtek^TM P60, 3M-ESPE, St. Paul, MN, USA