Three-Dimensional Assessment of Volumetric Changes in Sinuses Augmented with Two Different Bone Substitutes.

Introduction. The bone volume of the posterior maxilla may not be appropriate for implant placement, due to factors such as pneumatized maxillary sinus. The purpose of this study was to evaluate the percentage of graft volume reduction following sinus floor elevation (SFE), with either slow resorbable bone substitute only or a composite of slow and fast resorbable bone substitutes, using cone beam computed tomography (CBCT). Materials and Methods. In this retrospective study, CBCT scans of SFE procedures were evaluated to determine the volume of grafted sinus with either deproteinized bovine bone (DBB) or a 2 : 1 mixture of biphasic calcium sulfate (CS) and DBB, as a composite. The volumetric changes of sinus augmentations were measured 2 weeks (V-I) and 6 months (V-II) after operation. Results. Thirty-three patients were included in this study. The average percentage volume reduction was 9.39 ± 3.01% and 17.65 ± 4.15% for DBB and composite grafts, respectively. A significant graft volume reduction was observed between V-I and V-II for both groups (p < 0.01). The DBB group exhibited significantly less volume reduction than the composite group (p < 0.01). Conclusions. Augmented sinus volume may change before implant placement. DBB offers greater volume stability during healing than composite grafts.

Accuracy of two stereolithographic guide systems for computer-aided implant placement: a computed tomography-based clinical comparative study.

BACKGROUND: Stereolithographic surgical guides provide significant benefits during the simultaneous placement of multiple implants with regard to the final prosthetic plan. However, deviation from the planning poses a significant risk. Deviations of implants that were placed by bone-, tooth-, and mucosa-supported stereolithographic surgical guides were examined in this study. METHODS: After enrolling 54 eligible patients, 294 implants were planned on cone-beam computerized tomography CB(CT)-derived images. Sixty guides, both single- and multiple-type, were produced using two commercial systems. Mucosa-supported guides were fixed with osteosynthesis screws. Implants were inserted, and at the end of osseointegration period, a new CB(CT) scan was performed. Preoperative planning was merged with the new CB(CT) data to identify the deviations between the planned and placed implants for each support type and manufacturer. The Kruskal-Wallis and Mann-Whitney U tests were used for comparison (P <0.05). RESULTS: There were no damage-related complications in any critical anatomy. Implants that were placed by bone-supported guides had the highest mean deviations (5.0 degrees +/- 1.66 degrees angular, and 1.70 +/- 0.52 mm and 1.99 +/- 0.64 mm for implant shoulder and tip, respectively), whereas the lowest deviations were measured in implants that were placed by mucosa-supported guides (2.9 degrees +/- 0.39 degrees angular, and 0.7 +/- 0.13 mm and 0.76 +/- 0.15 mm for implant shoulder and tip, respectively). CONCLUSIONS: Computer-aided planning and manufacturing surgical guides in accordance with CB(CT) images may help clinicians place implants. Rigid screw fixation of a single guide incorporating metal sleeves and a special drill kit further minimizes deviations.