Purpose:
The purpose of this case series study was to clinically, radiographically and histologically evaluate the treatment of dehiscence defects in extraction sockets using a minimally-invasive GBR technique that involved the application of a particulate bone allograft and a non-resorbable d-PTFE (Dense polytetrafluoroethylene) membrane.
Methods:
Subjects with single-rooted teeth exhibiting a bone dehiscence defect indicated for extraction and interested in future implant therapy for tooth replacement were recruited based on eligibility criteria. An intraoral scan and a cone-beam computed tomography (CBCT) scan of the arch containing the tooth to be extracted were obtained prior to tooth extraction. Following minimally invasive tooth extraction and debridement, the presence of a dehiscence defect was confirmed After creating a soft tissue ‘pouch’ using tunneling instruments, a d-PTFE barrier membrane, trimmed to a size and shape that would allow for complete extension over the intact bone surrounding the dehiscence defect, was tucked between the mucosa and the alveolar bone. Then, the extraction sockets were grafted with particulate allograft and sealed with an extension of the membrane, which was stabilized using a cross mattress suture. Subjects were recalled at one, two, five, and twenty week(s) to monitor healing and assess the level of discomfort using a visual analog scale at the end of each visit. At the 5-week visit, the membrane was gently removed and the site was left to heal by secondary intention. At 20 weeks after tooth extraction a second intraoral scan and CBCT scan were obtained to radiographically evaluate the site for implant placement. Bone volumetric reconstructions of the alveolar ridge at baseline and at 20 weeks were made using the CBCT data to assess changes affecting the bone housing. If the site healed adequately, implant placement was performed at 24 weeks after tooth extraction. At the time of implant placement, a bone core biopsy was obtained in order to histologically analyze the characteristics of the grafted substrate. The ability to achieve implant placement and the need for additional grafting at the time of implant placement were recorded. Subjects returned for the final study visit at 2 weeks following implant placement to evaluate the healing prior to being referred to the restorative dentist.
The main outcomes of interest included the magnitude of volumetric changes of the alveolar ridge, both at a hard and soft tissue level, as measured using the radiographic CBCT and intraoral scan data. Secondary outcomes included the change in buccal and lingual bone height, histologic outcomes, and patient-centered outcomes. One-sample t-tests were performed to assess whether the observed changes in volume and bone heights were significantly different than zero.
Results:
At baseline, the average defect height in an apico-coronal dimension as measured clinically was 7.7mm. Linear radiographic measurements revealed an increase in buccal bone height of 4.87mm at 20 weeks following the surgery, indicating that the ridge defects were effectively repaired. Interestingly, the average reduction in ridge volume at 20 weeks was only 1.69% as measured on CBCT scans and 12.15% as measured on the intraoral scans; only the latter, which included the soft tissue component of the alveolar ridge, was found to be statistically significant. All treated sites demonstrated adequate ridge volume and height at the 20-week follow-up to allow for implant placement at 24 weeks, without need for further site development or delayed implant placement. All implants demonstrated adequate primary stability at the time of implant placement. Although adequate bony housing was present at all of the prepared osteotomies to provide stability, seven of the fourteen sites underwent additional bone grafting at the time of implant placement to increase the thickness of the buccal bone and provide support for a stable soft tissue profile. The histological analysis of bone core biopsies [n=9] revealed the presence of remaining allograft particles that were well integrated with vital bone. Among these samples, an average area of 31.4% mineralized tissue, 17.7% remaining allograft, and 50.9% non-mineralized tissue was measured. Additionally, the procedure employed was very well accepted by patients, with low reported pain that was decreasing over the follow-up period. The highest mean pain reported score using the VAS scale was 19/100 at the 2-week follow-up following the baseline surgery and this decreased and remained low [mean VAS ranging 3.1-7.8] through the remainder of the study. Patients reported a very high satisfaction level at the study’s completion – a mean of 95.1% satisfaction.
Conclusions:
The reconstructive technique employed in this study for the treatment of extraction sites exhibiting significant bone dehiscences was highly successful, allowing for the predictable treatment of deficient ridges via implant therapy, and it was well accepted by the participants.