Amir Laviv

Mandibular reconstruction using stereolithographic 3-dimensional printing modeling technology

Mandibular reconstruction can be challenging for the surgeon wishing to restore its unique geometry. Reconstruction can be achieved with titanium bone plates followed by autogenous bone grafting. Incorporation of the bone graft into the mandible provides continuity and strength required for proper esthetics and function and permitting dental implant rehabilitation at a later stage. Precious time in the operating room is invested in plate contouring to reconstruct the mandible. Rapid prototyping technologies can construct physical models from computer-aided design via 3-dimensional (3D) printers. A prefabricated 3D model is achieved, which assists in accurate contouring of plates and/or planning of bone graft harvest geometry before surgery. The 2 most commonly used rapid prototyping technologies are stereolithography and 3D printing (3DP). Three-dimensional printing is advantageous to stereolithography for better accuracy, quicker printing time, and lower cost. We present 3 clinical cases based on 3DP modeling technology. Models were fabricated before the resection of mandibular ameloblastoma and were used to prepare bridging plates before the first stage of reconstruction. In 1 case, another model was fabricated and used as a template for iliac crest bone graft in the second stage of reconstruction. The 3DP technology provided a precise, fast, and cheap mandibular reconstruction, which aids in shortened operation time (and therefore decreased exposure time to general anesthesia, decreased blood loss, and shorter wound exposure time) and easier surgical procedure.

Failure Causes, Timing, and Cluster Behavior: An 8-year Study of Dental Implants

Objectives:The aim of this study was to analyze implant failure, causes, time of failure, and cluster behavior of implant failure among patients referred to a private surgical center. Methods:All failed implants placed during the years 1997–2004 were analyzed. Data collected included age, gender, smoking habits, implant type and dimensions, timing of implantation (immediate or nonimmediate), time to failure, and failure causes. Results:Overall, 99 of the 3609 implants placed between the years 1997 and 2004 failed in 61 patients resulting in a 97.3% survival rate. Patients with implant failure ranged in age from 21 to 78 years (average 54 years); 34% were men, 66% women; smoking was reported by 32.8%, pastsmoking 16.4%; time from implant placement to failure ranged from 1 to 99 months (average 24 months, SD = 24.8). Common causes for implant removal were bone loss and/or inflammation (52.5%), and implant mobility (43.4%). Cluster behavior (ie, more than one implant failure per patient, not necessarily in the same area or quadrant) was shown in one-third (32.8%) of the patients in which 56.6% of all failures were found. This cluster pattern was evident in both the surgical and prosthetic phase failures. Conclusion:There is a higher probability for a cluster pattern among patients with implant failure. Common signs for failure are implant mobility (surgical phase) and infection and marginal bone loss (prosthetic phase).

Alveolar sandwich osteotomy in resorbed alveolar ridge for dental implants: a 4-year prospective study.

PURPOSE To answer whether severe vertical alveolar defects can be resolved using the sandwich osteotomy technique with xenograft material as filler and to evaluate the predictability of this procedure. MATERIALS AND METHODS Ten graft sites (5 mandibular and 5 maxillary) in 9 patients treated at the Department of Oral and Maxillofacial Surgery, Hadassah Medical Center, were included in the present study. The patients underwent vertical bone augmentation using the sandwich osteotomy technique filled with xenograft material. The degree of bone augmentation was analyzed clinically at surgery and 4 to 6 months later from the computed tomography images taken just before the sites had been rehabilitated using dental implant insertion. A trephine histologic analysis was performed during implantation at 1 maxillary site. RESULTS The mean vertical bone gain in the interval between the sandwich osteotomy and implementation was 6 mm (range 4 to 10), and it remained stable after 4 to 6 months. In 2 cases, additional horizontal bone augmentation was needed. All graft sites were rehabilitated using dental implants with satisfactory results. In 3 cases, gingival porcelain was required for the final prosthesis. Histologic examination revealed vital segmentized bone and remodeling of the filled gap. CONCLUSIONS The interpositional alveolar bone graft using xenograft filler appears to be a viable and predictable alternative to block grafting or guided bone regeneration, resulting in good final results, with substantial vertical bone gain, even for challenging cases.

Computerized navigation for immediate loading of dental implants with a prefabricated metal frame: a feasibility study.

PURPOSE To study the probability of using Image Guided Implantology (IGI) for planning and execution of a dental plan of 3 implants in a geometric pattern that fits a prefabricated metal frame accurately, simulating provisional restoration in immediate loading. MATERIAL AND METHODS Ten mandible models were imaged by standard computed tomography. Three implants, two in the premolar and one in the molar area on each side of the jaws, were planned by use of the IGI system (Image Navigation Ltd, Moshav Ora, Israel). Two millimeter drilling and subsequent 3 millimeter widening drilling was performed with the real-time computerized navigation technology in the 120 sampling sites. In each step, parallel pins were inserted, and metal gauging frames with preplanned holes of incremental diameters and in the predefined geometric pattern were placed on the pins to evaluate the precision of fit. RESULTS Full success was obtained in fitting all three 3-mm pins, with frames having clearance of 0.5 or 1 mm, and in matching pairs of pins 2 or 3 mm in diameter at clearances of 0.5 mm or greater. With more constrained clearances, matching of all 3 pins was 80% and 95% successful with 2-mm pins (clearance of 0.25 and 0.5 mm, respectively) and 60% and 95% successful with 3-mm pins (clearance of 0 and 0.25 mm, respectively). Some laterality bias was observed. CONCLUSIONS This preliminary study shows that the IGI system enables accurate planning of implant number and location to be achieved together with planning for a prefabricated metal frame for immediate loading.

Survival of Immediately Provisionalized Dental Implants: A Case-Control Study with up to 5 Years Follow-Up

PURPOSE The aim of this study was to evaluate the survival rate of immediately provisionalized implants with up to 5 years follow-up. MATERIALS AND METHODS The study consisted of 226 patients, 113 consecutive patients with immediately provisionalized dental implants (cases) and 113 randomly selected, age-, gender-, and implant position-matched controls with conventional late implant loading. Survival rate and incidence of complications were recorded. RESULTS Follow-up ranged from 6 to 60 months. Smoking was reported by 20.8% of patients. Maxillary incisors and mandibular lateral incisors were the most common areas for implant placement. Conventionally loaded implants were narrower (p = .03) and shorter (p = .001). Immediate implantation into a fresh extraction socket was performed in 69% of the cases and in 36.3% of the controls (p = .001). Implant survival rate was 96.5%. Of the eight failed implants, six were immediately provisionalized and two were conventionally loaded. No statistically significant difference was found in survival rates between groups (p > 0.05). Five of the failed implants (case group) were immediately loaded implants placed in fresh extraction sockets. CONCLUSION Immediate implant provisionalization achieved similar high success rates compared with the conventional, delayed approach. As immediate implant provisionalization is mainly desired in the anterior region, the high success rates are encouraging.

Pseudogout in the Temporomandibular Joint With Imaging, Arthroscopic, Operative, and Pathologic Findings. Report of an Unusual Case

The authors present a case of a 60-year-old woman with a destructive painful condition in the right temporomandibular joint (TMJ) that proved to be calcium pyrophosphate crystal deposits at subsequent biopsy examination. The patient presented with the chief complaints of pain and limitation that had not resolved with splint therapy, medications, and habit control. Magnetic resonance imaging studies showed internal derangement without reduction. Right TMJ arthroscopy with manipulation of the jaw under anesthesia showed unique findings of fronds of synovial tissue in the posterior joint space and areas of white matter. Because there was no long-term improvement in her clinical symptoms, she subsequently underwent arthroplasty of the right joint, with the white material clearly seen at surgery, and the biopsy examination confirmed the clinical and arthroscopic impression of pseudogout. The presentation, diagnosis, pathology, and treatment of pseudogout of the TMJ are discussed.

A comparative volumetric study of symphysis donor defects, unfilled or filled with bone substitute.

OBJECTIVES Background Intraoral autogenous bone grafts are a convenient source of bone in reconstruction of the residual ridge before dental implant placement. PURPOSE The aim of this study was to evaluate bone volume of symphysis donor defects filled with bone substitute compared with unfilled symphysis donor defects. PATIENTS, MATERIALS AND METHODS The study included 26 patients who underwent either alveolar ridge reconstruction or maxillary sinus elevation. Two groups were studied: symphyseal donor defects filled with bone substitute and unfilled symphyseal donor defects. Pre- and postoperative volumetric variables were determined using computed tomography scans and the software program SimPlant® (Materialise Dental Italia, Roma, Italy). RESULTS At 6 months postsurgery, the filled donor defects exhibited a significant increase in bone volume compared with unfilled donor defects (97.7% and 73.4%, respectively). At 18 months postsurgery, volume of unfilled donor defects was reevaluated with no significant increase in bone volume. CONCLUSIONS Six months following block harvesting procedure, filled donor defects maintained bone volume, while unfilled donor sites generated defects that cannot achieve full regeneration; even not 18 months postblock harvesting.

Comparison of time required for traditional versus virtual orthognathic surgery treatment planning

Virtual surgical planning (VSP) is a tool for predicting complex surgical movements in three dimensions and it may reduce preoperative laboratory time. A prospective study to compare the time required for standard preoperative planning versus VSP was conducted at Massachusetts General Hospital from January 2014 through January 2015. Workflow data for bimaxillary cases planned by both standard techniques and VSP were recorded in real time. Time spent was divided into three parts: (1) obtaining impressions, face-bow mounting, and model preparation; (2) occlusal analysis and modification, model surgery, and splint fabrication; (3) online VSP session. Average times were compared between standard treatment planning (sum of parts 1 and 2) and VSP (sum of parts 1 and 3). Of 41 bimaxillary cases included, 20 were simple (symmetric) and 21 were complex (asymmetry and segmental osteotomies). Average times for parts 1, 2, and 3 were 4.43, 3.01, and 0.67h, respectively. The average time required for standard treatment planning was 7.45h and for VSP was 5.10h, a 31% time reduction (P<0.001). By eliminating all or some components of part 1, time savings may increase to as much as 91%. This study indicates that in an academic setting, VSP reduces the time required for treatment planning of bimaxillary orthognathic surgery cases.

Imperforate Titanium Shell Enclosing Recombinant Human Bone Morphogenetic Protein-2–Induced Bone Formation for High-Profile Dental Implants in Rabbit Tibia

PURPOSE To evaluate the use of a nonperforated titanium occlusive device over high-profile dental implants in rabbit tibia using recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) for augmentation grafting. MATERIALS AND METHODS Eight New Zealand white rabbits were used for the experiment. All rabbits underwent computed tomography of the right tibia. A custom titanium shell was manufactured for each rabbit using a computer-assisted design to confine the graft. Three high-profile implants were placed in the right tibia of each rabbit; the middle implant was placed 8 mm in supracrestal fashion and the adjacent implants were placed 5 mm in supracrestal fashion. There were 4 groups (n = 2 per group): non-shell control, titanium shell only, titanium shell over buffered collagen, and titanium shell over the ACS enriched with rhBMP-2. The animals were sacrificed after 6 or 12 weeks. Histologic preparation was carried out to evaluate bone formation. RESULTS After 6 weeks, negligible bone growth was found around the implants. After 12 weeks, there was minimal bone formation around the implants in the control group, whereas in the group treated with ACS enriched with rhBMP-2, the titanium shell was filled with mature bone, which was expressed at the implant surface, the shells interior, and the exterior surfaces. CONCLUSION The placement of ACS enriched with rhBMP-2 beneath an occlusive nonperforated titanium shell confining high-profile dental implants resulted in visibly more formation of mature bone.

Island osteoperiosteal flap vitality when isolated from basal bone by silicone interposition: an experimental study in rabbit tibia.

PURPOSE This study sought to confirm, through histologic evaluation, the vitality and viability of the island osteoperiosteal flap (i-flap) in a rabbit tibia model. MATERIALS AND METHODS In four rabbits, an osteotomy was performed on the tibial aspect of the right leg. A bone flap was raised, but the periosteal attachment was kept intact. The free-floating i-flap was separated from the rest of the bone by a silicone sheet. The rabbits were to be sacrificed after 1, 2, 4, and 8 weeks and histologic samples examined. RESULTS All surgeries were accomplished successfully; however, three animals showed fractured tibiae within a few days after surgery and were sacrificed immediately after the fractures were discovered. The fourth rabbit was sacrificed at 4 weeks. Histologic specimens showed vital new bone in the i-flap area and signs of remodeling in the transition zone and the original basal bone. CONCLUSION The i-flap remained vital. This suggests potential for use in bone augmentation strategies, particularly for the alveolar split procedure.