Accuracy and Technical Predictability of Computer Guided Bone Harvesting from the Mandible: A Cone-Beam CT Analysis in 22 Consecutive Patients.

This study assesses the accuracy and technical predictability of a computer-guided procedure for harvesting bone from the external oblique ridge using a patient-specific cutting guide. Twenty-two patients needing bone augmentation for implant placement were subjected to mandibular osteotomy employing a case-specific stereolithographic surgical guide generated through computer aided design. Differences between planned and real cut planes were measured comparing pre- and post-operative Cone Beam Computed Tomography images of the donor site according to six validated angular and displacement indexes. Accuracy and technical predictability were assessed for 119 osteotomy planes over the study population. Three different guide fitting approaches were compared. An average root-mean-square discrepancy of 0.52 (0.30-0.97) mm was detected. The accuracy of apical and medial planes was higher than the mesial and distal planes due to occasional antero-posterior guide shift. Fitting the guide with an extra reference point on the closest tooth performed better than using only the bone surface, with two indexes significantly lower and less disperse. The study showed that the surgical plan was actualized with a 1 mm safety margin, allowing effective nerve preservation and reducing technical variability. When possible, surgical guide design should allow fitting on the closest tooth based on both radiological and/or intra-oral scan data.

The Vestibular Shifted Flap Design for Vertical Bone Augmentation in the Maxilla: Case Report and Technical Notes.

During bone augmentation procedures, primary wound healing determines the bone augmentation result. After a crestal incision in the maxilla, the palatal flap might not be an adequate length to correctly couple to the vestibular flap and to seal the wound with horizontal mattress and single sutures. Due to the histologic structure made of dense connective tissue, the palatal flap eversion is impossible, negatively impacting the wound seal and primary healing. This case report describes the effectiveness and efficacy of an incision design to improve palatal flap management during bone augmentation procedures in the maxilla. Indeed, palatal flap verticalization is achieved. The incision line is proportionally shifted on the vestibular side, based on the defect anatomy, to obtain a palatal flap length extending at least 4 mm coronal to the bone graft level prior to wound closure. The described approach simplifies the optimal adaptation of the inner faces of the palatal and vestibular flaps, reducing the risk of nonprimary wound healing.

Mandibular Canal Position in Posterior Mandible: Anatomical Study and Surgical Considerations in Relation to Bone Harvesting Procedures.

The aim of this study is to evaluate the anatomical characteristics of the posterior region of the mandible and their surgical relevance related to bone harvesting procedures. Fifty retromolar cone beam computed tomography scans were analyzed considering the donor site anatomies. For each site, linear measurements were taken of cross-sectional scans to record perpendicular distances between the mandibular canal (MC) and the vestibular and crestal bone walls. Data showed that the distance from the MC to the vestibular bone wall is lower in the ramus area than in the external oblique ridge area (< 2.00 mm in 26% of cases). However, the distance between the MC and the crestal bone wall is higher in the ramus area than in the external oblique ridge area. There is less bone thickness in the ramus area, and this could expose the inferior alveolar nerve to damage if osteotomies are performed with fewer depth limitations, as reported in the literature.

Assessing the accuracy of computer-planned osteotomy guided by stereolithographic template: A methodological framework applied to the mandibular bone harvesting.

Intraoral autologous bone grafting represents a preferential choice for alveolar reconstruction prior to dental implant placement. Bone block harvesting guided by a computer-planned lithographic template is a novel and promising technique for optimizing the volume of harvested material, while controlling the osteotomy 3D position with respect to delicate anatomical structures. We provide a quantitative framework to non-invasively estimate the accuracy of this technique. In the proposed framework, the planned osteotomy geometry was compared to the real outcome of the procedure, obtained by segmentation of post-procedural cone beam computed tomography data. The comparison required the rigid registration between pre and post-procedural mandibular models, which was automatically accomplished by minimizing the sum of squared distances via a stochastic multi-trial iterative closest point algorithm. Bone harvesting accuracy was quantified by calculating a set of angular and displacement errors between the planned and real planes which characterized the excision block. The application of the framework to four cases showed its capability to quantify the tolerance associated with computer-guided bone harvesting techniques with submillimetric accuracy (<0.4 mm), within the limits of native image resolution. The validation methodology proved suitable for defining the safety margins of osteotomy surgical planning.

Short, parallel-walled, conical-connection implants for a broad range of indications in the maxilla and mandible: Retrospective multicenter study with up to 33 months of follow-up.

OBJECTIVE: To evaluate the survival and complication rate of 7-mm short, parallel-walled, conical-connection implants in daily practice. METHOD AND MATERIALS: This multicenter retrospective study included 219 consecutive patients who received 323 implants. Indication was limited vertical bone height preventing placement of implants longer than 7 mm. Placement and loading protocols were determined on a case-by-case basis and included placement in fresh extraction sockets and healed sites, and loading was either immediate, early, or delayed. Patients were followed for up to 33 months. Outcome measures were implant survival rate and any biologic or technical complications. RESULTS: In total, eight implants in seven patients failed, accounting for the survival rate of 97.3% at implant level and 96.4% at patient level. The mean time to failure was 7.5 months and 10.2 months at the implant and patient level, respectively. The majority of patients (67.1%) received one implant and the placement was predominantly in healed sites (82.7%). Immediate loading was done for 21.4% of implants placed in the extraction site and for 21.3% of implants placed in healed sites. In most of the cases (71.8%) implants were placed in the premolar or molar position in the mandible. No complications were reported. CONCLUSION: These results suggest that in cases of limited vertical bone height, the short, parallel-walled, conical-connection implant can successfully support different prosthesis types in a wide variety of indications and loading protocols.

Results of Computer-Guided Bone Block Harvesting from the Mandible: A Case Series.

Autogenous bone harvesting is a well-documented surgical procedure. Autogenous mandibular bone harvesting carries a risk of anatomical structural damage because the surgeon has no three-dimensional (3D) control of the osteotomy planes. The aim of this case series was to describe the results of mandibular bone block harvesting applying computer-guided surgery. A sample of 13 partially dentate patients presenting bone deficiencies in the horizontal and/or vertical plane were selected for autogenous mandibular bone block graft. The bone block dimension was planned through a computer-aided design (CAD) process, defining ideal bone osteotomy planes to avoid damage to anatomical structures (nerves, teeth roots, etc) and to generate a surgical guide that imposed the 3D working direction to the bone-cutting instrument. The bone block dimension was always related to the defect dimension to be compensated. A total of 13 mandibular bone blocks were harvested to treat 16 alveolar defects (9 vertical and 7 horizontal). The mean planned mesiodistal dimension of the bone block was 24.8 ± 7.3 mm, the mean height was 8 ± 1 mm, and the mean thickness was 4 ± 2 mm. None of the treated patients experienced neurologic alteration of their alveolar nerve function. The preliminary data from this case series suggested that computer-guided bone harvesting could be a concrete opportunity for clinicians to obtain an appropriate volume of autogenous bone in a safe manner.

A computer-guided bone block harvesting procedure: a proof-of-principle case report and technical notes.

During autogenous mandibular bone harvesting, there is a risk of damage to anatomical structures, as the surgeon has no three-dimensional control of the osteotomy planes. The aim of this proof-of-principle case report is to describe a procedure for harvesting a mandibular bone block that applies a computer-guided surgery concept. A partially dentate patient who presented with two vertical defects (one in the maxilla and one in the mandible) was selected for an autogenous mandibular bone block graft. The bone block was planned using a computer-aided design process, with ideal bone osteotomy planes defined beforehand to prevent damage to anatomical structures (nerves, dental roots, etc) and to generate a surgical guide, which defined the working directions in three dimensions for the bone-cutting instrument. Bone block dimensions were planned so that both defects could be repaired. The projected bone block was 37.5 mm in length, 10 mm in height, and 5.7 mm in thickness, and it was grafted in two vertical bone augmentations: an 8 × 21-mm mandibular defect and a 6.5 × 18-mm defect in the maxilla. Supraimposition of the preoperative and postoperative computed tomographic images revealed a procedure accuracy of 0.25 mm. This computer-guided bone harvesting technique enables clinicians to obtain sufficient autogenous bone to manage multiple defects safely.

Immediately Loaded Intraorally Welded Complete-Arch Maxillary Provisional Prosthesis.

Guided implant surgery is not completely accurate when using computer-designed stereolithographic surgical guides. Complications are frequently reported when combining computer-guided flapless surgery with an immediately loaded prefabricated prosthesis. Achieving passive fit of a prefabricated prosthesis on the inserted implants the same day of the surgery can be difficult. The aim of this report is to show a new treatment approach to immediately loaded implants inserted with computer-guided surgery using an intraoral welded full-arch provisional prosthesis.