Intra-oral bone grafting: a clinical audit

18 April, 2011 / Infocus
 

Replacement of missing teeth has traditionally been achieved with a fixed or removable prosthesis, such as a bridge or partial denture. An alternative and more permanent solution is the use of dental implants, which are inserted into the alveolus and become integrated into alveolar bone (osseointegration).1

However, the placement of dental implants is dependant on the presence of an adequate volume of bone at the implant site. Inadequate bone volume may be a consequence of trauma or ridge resorption following tooth loss.2 Alveolar bone can be augmented prior to implant placement with a number of techniques.

The ‘gold standard’ technique is the use of autologous bone grafts, which are grafts taken from the patient, at a local or distant site from the implant recipient site.3 Other techniques include allografts (bone grafts derived from cadavers), xenografts (grafts derived from animals), synthetic bone substitutes, guided bone regeneration, bone promoting proteins, ridge expansion and distraction osteogenesis.2

Patients included in this audit received autologous grafts from local sites; mandibular symphysis or ramus. The procedure was carried out under antibiotic cover with post-operative antibiotics continued for five days. The procedure for the symphysis graft was carried out as follows: a buccal mucoperiosteal flap was raised and elevated to just above the lower border of the mandible. The graft was taken using a saline cooled bur (0.5mm diameter fissure bur) and fashioned to the dimensions of the recipient site using a bone wax stent (see Figure 1). The recipient site was prepared by raising a buccal mucoperiosteal flap. The cortex underneath the graft was perforated using a saline cooled bur and the graft was secured with titanium screws (see Figure 2).

Both sites were closed with vicryl rapide sutures. Implants were placed at the recipient sites circa six months following the grafting procedure.

Aims and objectives

The primary aim of this audit was to assess the success of the technique of autologous intra-oral bone grafting, performed prior to implant placement, as practised by the oral surgery team in the Edinburgh Dental Institute (EDI). This was achieved by comparing the EDI results against those of a previously published series (Misch CM 1997)4, which was chosen as a benchmark. A patient satisfaction questionnaire was carried out between five and seven years post-completion of the procedure.

The published benchmark selected was a paper by Craig Misch entitled ‘Comparison of Intra-oral Donor Sites for Onlay Grafting Prior to Implant Placement’ published in the International Journal of Oral and Maxillofacial Implants. This paper presented a clinical evaluation and comparison of bone grafting from the mandibular symphysis (31 cases) and ramus (19 cases) prior to implant placement. The parameters measured and used to evaluate the success of the procedure in the EDI are presented in Table 1 (below).

Methodology

A retrospective audit was carried out on 11 consecutive cases of autologous bone grafting performed in the oral surgery department of the EDI between January 2003 and November 2005. Data on post- operative complications, graft and implant success was collected from the electronic patient record and placed on a data collection form. Those patients on long-term recall were asked to complete a patient satisfaction questionnaire and in January 2010 the questionnaire was also posted to those patients not responding to recall. All patients were given the opportunity to attend the department for a review appointment to discuss any concerns regarding their treatment. Data was collected and analysed using Microsoft Excel.

Results

Of the 11 original cases (nine male, two female) in the series, seven had autologous bone grafts harvested from the mandibular symphysis and four had grafts harvested from the mandibular ramus. A total of 18 implants were placed (between one and three per patient). Seventeen implants were placed in the anterior maxilla and one was placed in the posterior right mandible. All surgical procedures were carried out under local anaesthesia.

Ten of the patients had lost teeth in the anterior maxilla through trauma and one had lost teeth in the posterior right mandible through caries. All grafts and implants placed were considered successful at one-year post implant placement. Eight cases from the original 11 (73 per cent) were successfully contacted to allow completion of a satisfaction questionnaire.

Early results

The incidence of post-operative complications following bone grafting is presented in Fig 3 and Table 2. The cases included compared favourably with the benchmark data. Although the EDI group had a lower incidence of nerve injury at the symphysis harvest site, there was a much higher incidence of nerve injury at the ramus harvest site.

However, this was transient paraesthesia and occurred in one of the four cases of ramus donor sites. The patient record gives no explanation why this should have occurred in this case. The percentage incidence of wound dehiscence at the symphysis was slightly higher in the EDI group – however this only occurred in one case.

The incidence of donor site infection at the symphysis was lower in the EDI group than the benchmark. All other incidences of post-operative complications in the EDI group were comparable to the benchmark.

Figure 3 and Table 2 show the comparison of post-operative complications after intra-oral bone grafting in EDI group compared to benchmark (Misch CM 1997). Table 2 shows comparison of EDI results to benchmark.

Long-term results

The patient satisfaction questionnaire was completed in the clinic or sent by post in January 2010. Of the 11 initial patients in the series, eight (six male, two female) were contacted to complete the questionnaire, giving a high response rate of 73 per cent. When asked if they had confidence to chew with their dental implants, all patients (except one) replied yes. The one negative responder wrote that they were “cautious biting into hard foods”.

All respondents were happy with the way their dental implant teeth looked, although one “had concerns for the future”. None of the respondents thought that someone else would be able to tell that the teeth were implant-supported. All would undergo the grafting and implant procedure again.

Two of the seven respondents stated that the mandibular symphysis grafting procedure was the worst part of the treatment and one found the local anaesthetic administration for implant placement the worst part of the procedure. One case found the sensation of bone chips falling onto his tongue, during implant placement, an unpleasant experience. The remaining respondents did not report a negative aspect of the treatment provided.

Conclusions

The purpose of this audit was to compare the success of intra oral bone grafting prior to the placement of dental implants at the EDI to a published benchmark. The early success rate of the grafting procedure was 100 per cent with a low rate of post- operative complications comparable to that of the benchmark.

All patients who responded to the questionnaire reported that they were happy with the treatment they received and would go through the process again. It is clear that this group of patients was highly motivated as the majority had lost anterior teeth through trauma and were keen to cease wearing a partial denture.

It is concluded that the success rate of this consecutive series of intra-oral bone grafting procedures, performed prior to dental implant placement, is high and matches a selected benchmark. It is also concluded that the long-term satisfaction with treatment, of this motivated patient group, is also high.

Maria Devine BDS (Nwc), MFDS, is a former
dental foundation trainee at the Edinburgh Dental Institute and now works in general dental practice in East Lothian.

Nick Malden BDS, FDS, is a consultant in oral surgery at the Edinburgh Dental Institute.

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REFERENCES

1. Branemark PI, Hanson BO, Adell R, Breine U, Lindstrom J, Hallen O, et al. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scandanavian Journal of Plastic and Reconstructive Surgery. Supplementum 1977; 16: 1-132

2. Esposito M, Grusovin MG, Worthington HV, Coulthard P. Interventions for replacing missing teeth: bone augmentation techniques for dental implant treatment. Cochrane Database Syst Rev. 2006 Jan 25; (1): CD003607.

3. Palmer P, Palmer R. Implant surgery to overcome anatomical difficulties. In: Palmer R editor(s). A clinical guide to implants in dentistry. London: British Dental Association, 2000: 57-65

4. Misch CM. Comparison of intra oral donor sites for onlay grafting prior to implant placement. Int J Oral Maxillofac Implants 1997; 12: 767-776

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