A method to assess the clinical outcome of ridge augmentation procedures.

BACKGROUND Alveolar ridge augmentation procedures are often needed prior to implant placement or prosthetic rehabilitation. The purpose of this study was to develop a quantitative method to assess the clinical outcome of such procedures. METHODS Two volumetric methods, based on the volume difference between the pre- and postoperative ridge, were developed. Either a transparent vacuum stent material (method A) or a silicone impression material in a custom acrylic tray (method B) was used to make an impression of the postoperative stone cast. This impression was then filled with polyvinylsiloxane bite registration material (PBRM) and placed on the preoperative cast. The volume of PBRM at the site of the augmented ridge (corresponding to the achieved ridge volume increase, in ml) was measured gravimetrically. Two independent examiners used both methods, in random order, to assess the outcome of 6 diverse clinical cases. Triplicate measurements were made (method precision). Method accuracy was assessed by fabrication of metal castings (known volumes) applied on a preoperative cast to simulate an augmentation procedure. RESULTS Intra- and inter-examiner reproducibility was high (intraclass correlation coefficients > or =0.84) for both methods. The volumetric measurements obtained by method B showed excellent correlation with the predetermined augmentation volumes (r2 = 0.99; y = 0.94x + 0.12), in contrast to the measurements obtained by method A (r2 = 0.46; y = 0.43x + 1.37). CONCLUSIONS The developed volumetric method (method B) is both precise and accurate in assessing the outcome of ridge augmentation. This simple, cost-effective, and easy to implement method should be helpful in clinical studies of ridge augmentation procedures.