Evaluation of Urist Putty, a Novel BMP Bioimplant, for Socket Preservation and Ridge Augmentation

Evaluation of a novel BMP bioimplant (URIST^TM) for socket preservation and ridge augmentation

Clokie, Cameron ML; Zhou, Aileen J; Peel, Sean AF.

A variable loss of alveolar bone volume following the extraction of a tooth may necessitate the need for an alveolar ridge augmentation procedure prior to dental implant placement. As a result, techniques for socket preservation and alveolar ridge augmentation have been developed.  Autologous bone grafts (ABG) are considered to be the gold standard for these procedures. However, they require additional surgery and add risk to the patient.  Bone morphogenetic protein-2 (BMP) bioimplants are an alternative to ABG (1,2), but require supraphysiologic doses of BMP, which increase the risk of complications and cost. Furthermore, these products require significant preparation time and are difficult to handle and place in the treatment site.  URIST™ putty (Induce Biologics Inc., Toronto) is a novel BMP bioimplant designed to overcome these shortcomings. This study evaluated the performance of URIST^TMfor socket preservation (SPR) and alveolar ridge augmentation (ARA) as compared to the use of autogenous bone grafting (ABG).

Twenty-four (24) skeletally mature dogs were divided into two equal groups. In all animals, both the left and right second molars and the left and right 4^th pre-molars of the mandible were extracted (i.e. 4 teeth per jaw). Group 1 animals had the sockets grafted following extraction, while those in Group 2 had the buccal wall of the socket removed before grafting. Two preparations of URIST^TM, containing either 0.5 or 1 mg BMP per ~1.3cc putty were tested.  ABG and unfilled defects were used as controls.  After 6 weeks, caliper measurements and histology were be carried out.  Alveolar ridge width was measured by caliper at 3 levels from the coronal aspect of the tooth socket:  crest(C), mid(C-5mm), and apex (C-10mm).  Dental implants were then placed at the completion of the study at all grafted sites.

In the SPR group, the unfilled sockets showed a loss in crest width as expected.  The crest width was maintained with the 0.5 mg BMP preparation and increased significantly at the 1 mg preparation compared to unfilled (P <0.05).  In the ARA group, there was some increase in crest width in the unfilled group, but the increase was significantly greater in the URIST^TM-treated groups at both doses vs. unfilled and ABG treatments (P <0.05 for all).  Similar trends were observed at the other levels (apex and mid ridge) that were measured.  The bone cores taken from the unfilled, ABG and URIST^TM-treated sockets were similar histologically. No significant inflammation or signs of infection were observed.  It was possible to place dental implants in the ideal location for all sites treated with URIST^TM, whereas ideal implant placement was not achieved in the other groups.

This study demonstrated that URIST^TM Putty was effective in maintaining the dimensions of the alveolar ridge when used for socket preservation, and was significantly more effective than autogenous bone for alveolar ridge augmentation in preparation for dental implant placement.  Further, the histological samples demonstrated that URIST^TM was able to achieve this primarily through the stimulation of new bone formation, rather than just having the graft material fill the space.  Finally, there were no adverse effects associated with the use of URIST^TMin this study.

References:

 1.         Misch, C.M. (2010).  The use of recombinant human bone morphogenetic protein-2 for the repair of extraction socket defects: a technical modification and case series report.  Int J Oral Maxillofac Implants, 25:1246-1252

2.         Fiorellini, J.P. et al. (2005).  Randomized study evaluating recombinant human bone morphogenetic protein-2 for extract socket augmentation.  J Periodontol, 76(4), 605-612