Replacing a fractured single central incisor: a natural approach

Dr. Attiq Rahman presents a UL1 implant case

One of the most difficult challenges faced by dentists and technicians alike is the placement and restoration of an implant to replace a single central incisor tooth, especially in a medium- to high-smile line when the contralateral incisor exhibits complex internal characteristics.

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The dentist not only must place the implant in the ideal 3D position, but also must take into consideration possible future resorption of the ridge, recession of the peri-implant tissues, and also the final white esthetics of the definitive restoration. In some cases, achieving a perfect match of the white esthetics can prove to be exceptionally difficult.

Frequently, the dentist must ask the patient to attend for multiple try-in appointments in the hope of getting incrementally closer to an acceptable esthetic result; however, it can feel like a case of taking one step forward and two steps back.

Presented below is a case where a novel approach was adopted in order to achieve the best possible white esthetics.

Case presentation
The patient was a 36-year-old male who was referred to the practice presenting with trauma to the UL1. There was an obvious subgingival fracture, and the patient had been advised by his GP that an implant would be required. He was a nonsmoker, nondrinker, with no relevant medical history. The oral hygiene was good, and the only other restoration was an electively placed cantilever bridge at UR3 (UR2).

Figure 1: First presentation
Figure 1: First presentation
Figure 2: Note gingival inflammation, incisal edge position, and complex enamel structure; Figure 3: PA showing horizontal fracture
Figure 2: Note gingival inflammation, incisal edge position, and complex enamel structure; Figure 3: PA showing horizontal fracture

The UL1 was darker than UR1, Grade III mobile, and the incisal edge was positioned 1 mm lower than the UR1 seen in Figure 1. Note the highly complex pattern of striations, mild fluorosis, halos, translucencies, and opacities within the enamel of UL1. There was significant gingival inflammation around the UL1, and therefore, the gingival margin was clearly visible at full smile, whereas at the UR1 it was not (Figure 2). The periapical radiograph showed a horizontal fracture approximately 2 mm apical to the cementoenamel junction (CEJ) with 1-1.5 mm recession of the buccal plate (Figure 3).

Treatment options presented to the patient were:

  • Extraction under local anesthetic (XLA) UL1 and a partial acrylic prosthesis
  • Root canal therapy on UL1 followed by extrusion of the remaining root and a post crown
  • Extraction under local anesthetic and an implant-retained crown

Having fully discussed all the options, the patient elected to have the tooth extracted and an implant-retained restoration. It is vitally important when treatment planning anterior implant cases to carry out an esthetic risk assessment (ERA) to determine the correct placement protocol.

The options for placement are:

  • Immediate: immediately following XLA
  • Early: 4–6 weeks post XLA and following soft tissue closure
  • Delayed: 3–6 months post XLA following full ridge healing

A simplified ERA table is presented on Figure 4.

In this case, the gingival biotype was thick, smile line was medium to high, oral hygiene was good, there was no recession, and there was seen to be 4–6 mm of attached gingiva throughout the upper anterior and premolar segments (Figure 5).

Figure 4: Simplified ERA table. John C. Kois, DMD, MSD: Predictable single-tooth peri-implant esthetics: five diagnostic keys. Compendium. 2004:25 (11):585. AEGIS Communications ©2004.; Figure 5: Note medium to thick biotype and abundance of attached gingiva Figure 6: Highly complex enamel
Figure 4: Simplified ERA table. John C. Kois, DMD, MSD: Predictable single-tooth peri-implant esthetics: five diagnostic keys. Compendium. 2004:25 (11):585. AEGIS Communications ©2004.; Figure 5: Note medium to thick biotype and abundance of attached gingiva Figure 6: Highly complex enamel
Figure 7: Removal of pulp and dentin color noted; Figure 8: Enamel shell; Figure 9: Enamel shell
Figure 7: Removal of pulp and dentin color noted; Figure 8: Enamel shell; Figure 9: Enamel shell
Figure 10: Implant placed
Figure 10: Implant placed

The esthetic risk in this case was low to medium, and therefore, an immediate placement protocol was deemed appropriate.

Given the extremely complex enamel patterns described earlier, the favorable position of the fracture in relation to the CEJ and in consultation with the patient, it was decided to try to use the patient’s natural UL1 as both the immediate temporary and eventually convert it to the final definitive restoration.

Surgery
The patient was anesthetized with buccal and palatal infiltrations, and following standard aseptic surgical protocol, the fractured coronal portion of UL1 was easily removed and inspected (Figure 6).

Figure 11: Before Bio-Oss; Figure 12: After Bio-Oss
Figure 11: Before Bio-Oss; Figure 12: After Bio-Oss
Figure 13: Immediate temporary abutment fitted; Figure 14: Etching of enamel shell interior; Figure 15: Adding flowable resin to interior of enamel shell
Figure 13: Immediate temporary abutment fitted; Figure 14: Etching of enamel shell interior; Figure 15: Adding flowable resin to interior of enamel shell

As the crown dehydrated, its complex structure became even more apparent. The crown was then given to the technician who, using a turbine and a diamond bur, removed the necrotic pulp and noted the color of the underlying dentin (Figure 7). This dentin was then also removed to leave a hollow enamel shell (Figures 8 and 9). The remaining root was atraumatically extracted, and a 4.3 mm x 13 mm tapered implant placed (Figures 10 and 11). The gap between the buccal plate and the implant was then filled with xenograft, (Bio-Oss® Geistlich Pharma North America Inc.) (Figure 12).

An immediate temporary abutment was then placed and tightened with finger pressure only (Figure 13). The inner surface of the enamel shell was then etched with 37% orthophosphoric acid followed by Scotchbond™ Primer and then Scotchbond™ Bonding Resin (3M ESPE) (Figure 14). Flowable Resin shade A2 was then placed in the shell and cured in increments to approximately the correct shape to fit the immediate temporary abutment (Figures 15 and 16). The shell was tried in over the abutment to ensure proper seating (Figure 17), following which the interior of the shell was filled with a bisacryl temporary crown material (Luxatemp®, DMG America) and seated until the material had fully set (Figure 18). The shell was then removed from the abutment in situ and mounted on a duplicate abutment, following which flowable resin was added to create an ideal junction between the abutment and the cementum (Figures 19-23).

Figure 16: Approximately the shape around the immediate temporary abutment; Figure 17: Enamel shell tried over abutment; Figure 18: Enamel shell filled with Luxatemp and seated over abutment
Figure 16: Approximately the shape around the immediate temporary abutment; Figure 17: Enamel shell tried over abutment; Figure 18: Enamel shell filled with Luxatemp and seated over abutment
Figure 19: Shell removed from abutment to show hexagonal shape; Figure 19: Shell removed from abutment to show hexagonal shape; Figure 21: Addition of flowable resin to create submergence profile
Figure 19: Shell removed from abutment to show hexagonal shape; Figure 19: Shell removed from abutment to show hexagonal shape; Figure 21: Addition of flowable resin to create submergence profile
Figure 22
Figure 22

Abrasive discs were then used to shape and polish the area until a seamless polished junction was achieved without overhangs or areas of deficiency (Figures 24-26). The crown was then seated with firm pressure onto the abutment and the occlusion checked (Figure 27).

It was imperative to ensure that there was no contact in centric occlusion or in protrusive movements. The palatal surface was eased to ensure this (Figure 28), and a radiograph was then taken to check that the crown was fully seated (Figure 29). The removal of necrotic pulp and stained dentin together with dehydration resulted in an immediate improvement in value (Figure 30).

Figure 23: Resin addition complete
Figure 23: Resin addition complete
Figure 24: Abrasive discs used to shape and polish resin to cementum interface; Figure 25: Submergence profile complete; Figure 26: Removed from duplicate abutment, ready to seat
Figure 24: Abrasive discs used to shape and polish resin to cementum interface; Figure 25: Submergence profile complete; Figure 26: Removed from duplicate abutment, ready to seat
(counterclockwise) Figure 27: Seating on abutment with no need for cement; Figure 28: Palatal surface eased to eliminate contact in centric and protrusive excursions; Figure 29: PA showing full seating of UL1 crown on abutment
(counterclockwise) Figure 27: Seating on abutment with no need for cement; Figure 28: Palatal surface eased to eliminate contact in centric and protrusive excursions; Figure 29: PA showing full seating of UL1 crown on abutment
Figure 30: UL1 fully seated. Note improvement in value; Figure 31: Review at 2 weeks. Note stabilization of value
Figure 30: UL1 fully seated. Note improvement in value; Figure 31: Review at 2 weeks. Note stabilization of value

The patient was advised that in the coming days, rehydration would lower this value once again, but given that the dentin color was now more favorable, the end result should be a good match for UR1. The patient attended for review at 2 weeks, and this was indeed found to be the case (Figure 31). There was also found to be a significant improvement in the health and color of the gingival tissues at UL1 (Figure 32), and it was likely that the gingival margin would migrate apically as the tissues continued to heal.

During the healing phase, orthodontic treatment of the mandibular arch was carried out to lingualize the lower anteriors. This was done in order to reduce the risk of heavy contacts on protrusive movements. The lingualization process was completed using a series of clear aligners since the patient could not tolerate an Inman Aligner™. The process took nearly 12 months, during which time the enamel shell temporary performed faultlessly.

At 12 months post-op, the patient was reviewed and bleaching trays fitted to allow him to bleach his teeth, including UL1. After 2 weeks, the UL1 was removed, and a fixture head impression was taken for the definitive abutment that would support the enamel shell.

Figure 32: Note significant improvement in gingival health and color
Figure 32: Note significant improvement in gingival health and color
Figure 33: Enamel shell bonded to definitive IPS e.max hybrid abutment; Figure 34: Immediately after fit. Note dehydration causing value to be too high; Figure 35: Final review at 2 weeks
Figure 33: Enamel shell bonded to definitive IPS e.max hybrid abutment; Figure 34: Immediately after fit. Note dehydration causing value to be too high; Figure 35: Final review at 2 weeks
Figure 36: Some loss of the mesial and distal papilla but much improved pink esthetics; Figure 37: A very acceptable esthetic result
Figure 36: Some loss of the mesial and distal papilla but much improved pink esthetics; Figure 37: A very acceptable esthetic result

The technician then repeated the original hollowing out procedure until again only the enamel shell remained. This was then bonded to a custom IPS e.max hybrid abutment (Ivoclar Vivadent) bonded to a titanium base (Figure 33). This was fitted, and again, the value appeared to be too high (Figure 34). The patient was reassured again that rehydration over the coming days and weeks would lower this value until it matched the UR1.

The patient is delighted with the overall esthetic result, and with the exception of his wife, no one in his family is aware that he ever lost his tooth.

The patient was reviewed at 2 weeks, and the value had indeed lowered to match the UR1, and the difference was almost indistinguishable (Figure 35). Pink esthetics were much improved with a healthy gingival cuff; however, there had been some loss of the mesial and distal papillae (Figures 36 and 37). This will need to be monitored in the coming years, and if necessary, connective tissue grafting can be planned.

A final radiograph was exposed (Figure 38), which shows acceptable bone levels with no recession since placement approximately 1 year previously. The patient is delighted with the overall esthetic result, and with the exception of his wife, no one in his family is aware that he ever lost his tooth.

Acknowledgment
The author would like to thank the team at Visage Dental Lab for their very skilled handling of this case.

 
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headshot_rahmanDr. Attiq Rahman qualified from Glasgow Dental School in 1994 and is in full-time private practice in Glasgow, Scotland. His practice is limited to implant, restorative, and esthetic dentistry at Visage Clinic, Glasgow, where he is clinical director.

Dr. Rahman lectures nationally and inter-nationally on the subject of implant and esthetic dentistry.

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