Introduction

This assignment examines the technique, and factors predisposing to the success of replacing failing teeth with an immediately placed implant. Immediate replacement circumvents the time (typically 4-6 months) taken for sockets to heal, and is thus attractive to patients.

Factors affecting the suitability of a failing tooth for immediate replacement

1.Periapical Health of the failing tooth.

In their study of 124 implants placed in 104 patients immediately after extraction in the early 90’s, Gomez-Roman, Weber et al1 excluded teeth with acute periapical pathology, and achieved success rates of 97% after 5 years. However Novaes Snr and Jnr published three cases in 19952 which showed that with thorough debridement, and adequate pre-operative, and post-operative care, implants can be placed into chronically infected sites, and survive. Obviously this second study can be criticised for the small sample size, and the short follow-up period (the longest follow-up was on an implant that had been loaded for 14 months). The first study relates to the placement in one centre of Frialit-2 implants which are no longer manufactured, however the follow-up protocols were much more rigorous. Novaes et al. also did an animal study3 where they placed sixteen implants immediately into extraction sites in dogs, eight of which had been peri-apically infected for nine months. From this study they demonstrated that there was no significant difference between the successful integration of implants placed in infected, or un-infected sites. Criticisms of this study could include that success was measured by histological studies after only twelve weeks, and that integration was measured quantitively by the percentage of bone-implant contact.A very recent study of 34 patients needing immediate single-tooth replacement4 by Siegenthaler et al. showed that providing primary stability is achieved, immediate implant placement in extraction sockets exhibiting periapical pathology does not lead to an increased rate of complications and renders an equally favourable type of tissue integration of the implants. Again criticism could be levelled at this study in that initial results were reported after only 12 month follow-up, however on-going follow-up data is being collected, and will be reported on in a future publication. Sethi and Kaus in their text-book condense this information into the advice that there should be no acute peri-apical infection, and and chronic lesions should be well-contained.

2. The health, thickness, and contours of soft tissues around the failing tooth.

Whilst researchers such as Tarnow have shown that soft tissues are dependent on bone support, thin friable soft tissues are more likely to recede/dehisce than thick fibrous tissues, reducing the aesthetic outcome for the eventual restoration. Current research is establishing whether abutment micro-surfaces could be adapted to allow attachment of fibroblasts, further supporting soft-tissues.

3. The presence of an intact socket.

Any dehiscences in the socket following extraction will have an effect on the eventual bone/soft-tissue levels around the implant. Buccal dehiscences are to be suspected in teeth that have root-fractures, and are a contra-indication to immediate placement. Loss of vertical bone height between teeth will make regeneration of papillae difficult. Multi-rooted teeth may not be suitable for immediate replacement, as primary stability in a position condusive to restoration may be difficult to achieve, eg a lower molar.

An appropriate Clinical Protocol for the immediate replacement of a tooth with an implant.

1. Extraction.

From the above, any technique for extracting the failing tooth should concentrate on preserving the walls of the socket, especially the buccal plate. Good radiographs will establish the root form of the tooth to be extracted. Instruments such as peritomes, and luxators which cut the periodontal membrane should be used in preference to elevators and blunt forceps which may damage the socket. Fine forceps may be used with a twisting motion on straight conical teeth. Multiple roots should be sectioned and removed individually, and single roots of a form resistant to removal, may have to be divided and removed in sections to preserve the integrity of the socket. On no account should a flap be raised, as removal of the periosteum from the surface of the bone will increase resorbtion.

2. Implant placement

As noted in Siegienthaler’s study4, primary stability is essential for immediately placed implants. Typically this entails extending the osteotomy beyond the base of the socket, whilst not penetrating external cortical bone and creating a dehiscence. In the anterior maxilla this will require extending the socket nearer the palatal wall. An implant of suitable size to engage the walls of the osteotomy should be chosen. Any gaps in a bucco-palatal dimension should be left between the implant and the buccal plate, allowing ingrowth of bone, and subsequent thickening of the buccal plate. The head of the implant should be left at the prescribed level in relation to the bone, not the soft tissues.

3. Provisional/transitional restoration.

The important factors here are that any blood clot between implant and bone is protected against bacterial or mechanical trauma, and that the soft tissues are adequately supported. Studies have shown that minimal disturbance of the implant abutment interface preserves bone height, and therefore a suitable abutment is preferred to a healing cap. Said abutment should provide soft-tissue support, and a seal for the socket. The provisional restoration must be free of all occlusal contact and excursion to prevent micro-movement whilst integration is occurring.

If delayed loading is preferred, then transitional restorations such as rochette bridges, or partial dentures can be used. As with provisional restorations, no force should be transmitted trans-mucosally to the implant. Delayed loading allows manipulation of the soft-tissues when uncovering the implant to enhance the soft-tissue contours using incisions such as the H, S, or C-shaped as described in ‘Practical Implant Dentistry’

Risks and Benefits of immediate placement.</h3

Chen et al.5 in their review of the literature relating to immediate placement of implants note that delayed placement has the advantage of stable soft tissue, whereas immediate placement reduces bone resorbtion following extraction. Immediate placement also has the advantage of being minimally invasive, so reducing overall treatment time, and the number of surgical interventions.

References:

1. Gomez-Roman G, Kruppenbacher M, Weber, H, Schulte W. Immediate Postextraction Implant Placement with Root-Analog Stepped Implants; Surgical Procedure and Statistical Outcome After 6 Years. Int J Oral Maxillofac Implants 2001;16:503-513.
2. Novaes A Snr, Novaes A Jnr. Immediate Implants Placed into Infected Sites: A Clinical Report. Int J Oral Maxillofac Implants 1995;10:609-613.
3. Novaes A Jnr, Vidigal G, Novaes A, Grisi M, Polloni S, Rosa A. Immediate Implants Placed into Infected Sites: A Histomorphometric Study in Dogs. Int J Oral Maxillofac Implants 1998; 13:422-427.
4. Siegenthaler D, Jung R, Holderegger C, Roos M, Hammerle C. Replacement of teeth exhibiting periapical pathology by immediate implants. Clin Oral Impl Res 18, 2007;727-737.
5. Chen S, Wilson T, Hammerle C. Immediate or Early Placement of Implants Following Tooth Extraction: Review of Biological Basis, Clinical Procedures, and Outcomes. Int J Oral Maxillofac Implants 2004;19(Suppl):12-25.