Planning implants crown down--a systematic quality control for proof of concept.

PURPOSE: We evaluated an innovative approach for conventional surgical or transmucosal implantation applying backward planning with bone oriented crown down implant positions, followed by immediate restoration. MATERIALS AND METHODS: Our workflow combined computer-assisted preoperative planning with the well-known intraoperative handling of surgical templates. To guarantee optimal accuracy, the complete process was bone borne, not soft tissue borne. Furthermore, in this concept, the definite prosthesis was manufactured on a plaster cast and fixed with technical implants inserted into the model using the same drilling template applied for intraoperative guidance of the drill. This bone-based workflow avoids the accumulation of errors throughout all steps of the treatment. In the present study, we have provided a concise quantitative quality control using 4 in vivo implants. This goal was accomplished by image matching of the preoperative plan with the corresponding postoperative computed tomography scan, applying descriptive statistics, the 1-sample t test, and the Student t test. RESULTS: Statistical evaluation showed that the bone-borne drilling template provides sufficient accuracy for immediate restoration with the definite prosthesis at the end of the operation. Deviation in the apex plane was 0.8 ± 0.42 mm, with 0.33 at the maximum. The angular deviation was 3.18° ± 0.78°. CONCLUSIONS: Our workflow is a promising approach with respect to handling, accuracy, and intraoperative safety.

Influence of platform switching on crestal bone changes at non-submerged titanium implants: a histomorphometrical study in dogs.

OBJECTIVES: The aim of the present study was to investigate histomorphometrically the influence of platform switching on crestal bone changes at non-submerged wide-body titanium implants in a dog model. MATERIAL AND METHODS: One-stage insertion of sand-blasted and acid-etched screw-type implants with either matching (CAM) or smaller-diameter healing abutments (CPS) were randomly assigned to the lower jaws of nine beagle dogs. The animals were killed after 7, 14, and 28 days of non-submerged healing. Dissected blocks were processed for histomorphometrical analysis. Measurements were made between the implant shoulder (IS) and:--the apical extension of the long junctional epithelium (aJE), --the most coronal level of bone in contact with the implant (CLB), and --the level of the alveolar bone crest (BC). RESULTS: At 7, 14, and 28 days, the mean IS-aJE values were significantly the lowest at CPS implants. However, after 28 days of healing, both groups revealed significantly increased mean IS-BC values at the buccal aspect of the alveolar bone. The difference in IS-CLB and IS-BC between groups was not significant. CONCLUSIONS: Within the limits of the present study, it was concluded that both CAM and CPS implants revealed crestal bone-level changes after 28 days of healing.

Bone apposition to titanium implants biocoated with recombinant human bone morphogenetic protein-2 (rhBMP-2). A pilot study in dogs.

The aim of the present study was to investigate bone formation to recombinant human bone morphogenetic protein-2 (rhBMP-2)-biocoated and rhBMP-2-nonbiocoated titanium implants after implantation in dogs. Implantation of sand-blasted and acid-etched (C), chromosulfuric acid surface-enhanced (CSA), and rhBMP-2-biocoated CSA [BMP-A: noncovalently immobilized rhBMP-2 (596 ng/cm(2)), BMP-B: covalently immobilized rhBMP-2 (819 ng/cm(2))] implants was performed in both the mandible and tibia of dogs. After 4 weeks of healing, the percentage of direct bone to implant contact (BIC) and the induced bone density (BD) at a distance of less than and greater than 1 mm adjacent to each implant was assessed. Histomorphometric analysis of implants inserted in the mandible and tibia revealed that BIC values appeared to be highest in the BMP-B group, followed by BMP-A, CSA, and C. BD as measured at a distance of <1 mm revealed obvious differences between groups: BMP-B>BMP-A>CSA>C. However, no differences between groups were observed at a distance of >1 mm. Within the limits of the present study, it may be concluded that rhBMP-2 immobilized by covalent and noncovalent methods on CSA-treated implant surfaces seemed to be stable and promoted direct bone apposition in a concentration-dependent manner.

Radiographic and histologic evaluation of a sinus augmentation with composite bone graft: a clinical case report.

BACKGROUND: The purpose of the present study was to present a clinical case report of a sinus augmentation with a composite bone graft and delayed implant placement with a 5-year follow-up. METHODS: A 40-year-old female in good health required replacement of her partial upper removable denture with a prosthesis supported by implants. Due to insufficient bone, she had to undergo a sinus lift. A block graft of autogenous chin bone, along with anorganic bovine bone covered by collagen, was utilized. Eight months postsurgery, a biopsy core was taken and 3 endosseous implants were placed. RESULTS: The sinus lift and implantation site are illustrated with clinical, radiological, and histological data. The discussion covers the problems raised by the choice of the surgical technique, grafting material, and immediate or delayed placement of the appropriate implant design. CONCLUSION: Our results show that a maxillary sinus augmentation with a composite bone graft is a possible method for creating adequate bone volume before implantation.