Low Window Sinus Elevation Technique: Bone Gain and Postsurgical Discomfort. A Retrospective Case Series.

Recently, the Low Window technique was proposed to facilitate sinus augmentation and reduce postsurgical patient discomfort. It was shown to be both safe and effective. This case series evaluates the postsurgical discomfort of patients undergoing Low Window sinus augmentation, the bone gain achieved, and whether these factors correlate with the osteotomy area. Records of patients (n = 26) who underwent a sinus elevation using the Low Window approach (n = 34 interventions), followed by implant placement and prosthetic rehabilitation (n = 97 implants), were assessed retrospectively. The analyzed outcomes were the medial, middle, and lateral bone gain ≥ 9 months after augmentation; pain at 5 to 6 hours postsurgery, evaluated on a visual analog scale (VAS; 0 to 100); pain, swelling, and hematoma formation every day up to 7 days postsurgery, evaluated by VAS; implant and prosthetic success and survival rates; and rate of complications. The average follow-up time was 62.1 ± 14.9 months. No intraoperative sinus membrane perforations or other complications occurred. Medial, middle, and lateral bone gains were 10.1 ± 1.7 mm, 11.6 ± 0.8 mm, and 10.7 ± 0.9 mm, respectively. At the last follow-up, the implant success rate was 99%. Postsurgical VAS pain 5 to 6 hours postsurgery was 12.3 ± 8.0 and decreased significantly thereafter. Swelling prevalence was 29.4% at 1 day postsurgery, 20.6% at 2 days, and 2.9% the following day. No swelling was observed from day 4 onward. Prevalence of hematoma was 8.8% for 2 days postsurgery, 2.9% the day after, and no hematoma was observed thereafter. Only the osteotomy area correlated with immediate postsurgical pain, but not with other discomfort outcomes or with bone gain. Low Window sinus elevation might allow bone gain and medium-term implant and prosthetic success rates similar to that of other access window designs. Prospective, comparative studies are needed to investigate whether the technique is more advantageous than traditional approaches.

The Low Window Technique: Comparison between Manual and CAD/CAM-guided Design.

AIM: The aim of this bench study was to provide quantitative data addressing the difference between the manual low window design and the corresponding computer-aided design and computer-aided manufacturing (CAD/CAM)-guided design. MATERIALS AND METHODS: Five cone-beam computed tomography (CBCT) scans of as many patients (two males and three females, age range: 61-78 years) with partially edentulous maxilla to be rehabilitated through sinus augmentation, one- or two-step implant placement, and implant-supported prostheses were used to 3D-print the corresponding five maxillary stereolithographic models. Five independent highly skilled maxillofacial surgeons, who were provided with the patients' orthopantomographs, drew on the models the access windows for sinus augmentation according to the "high" (standard) and the low window design both by free-hand and using a surgical guide prepared by computer-guided design. Accuracy and inter-operator variability were analyzed. RESULTS: The results of this study showed that the manual design is associated with a clinically relevant shift in the low window shape, size, and positioning compared with the CAD/CAM-based positioning. All four directions (apical, coronal, mesial, and distal) showed on average the same extent of placement error (approximately 3 mm). Overall, the intra-operator variability was very similar, and measurements were not influenced by the operator (low inter-operator variability). CONCLUSION: The compromised accuracy and reproducibility in the manual design may limit the advantages of the low window technique. Thus, within the limits of this study, the computer-guided approach should be preferred vs the manual approach when performing a low window sinus lift. This may limit intra- and postoperative complications, as well as patient discomfort. CLINICAL SIGNIFICANCE: The "best option" CAD/CAM-guided design should be chosen when performing a low window sinus lift because it reduces discrepancies in selected parameters both between and within groups. This should facilitate the achievement of better results by dentists who have insufficient experience performing implant surgery.

Implant and Prosthetic Success Following Peri-implant Guided Bone Regeneration in the Esthetic Zone Using an Equine Cortical Bone Membrane and an Equine Enzyme-Treated Bone Graft: A Retrospective Study with 9-year Follow-Up.

PURPOSE: A barrier membrane consisting of an equine-derived, demineralized cortical bone sheet has been made available, yet evidence of its effectiveness is currently only anecdotal. This study aimed to obtain preliminary evidence concerning the medium-term prosthetic and implant success rates that may be achieved when such a membrane is used in combination with an equine, enzyme-treated bone graft, concomitantly to implant placement in the esthetic zone. MATERIALS AND METHODS: Records of patients who had one or two implants placed in the anterior sectors of the two arches and had peri-implant bone regeneration carried out using the equine-derived membrane and equine-derived collagen-preserving bone granules were retrospectively collected. Peri-implant marginal bone loss (MBL) was used to assess implant survival. When available, histologic data concerning the equine membrane and cone beam computed tomography (CBCT) scans were analyzed as well. RESULTS: Records of 32 patients (ages 36 to 73 years), corresponding to 44 implants placed, were retrieved and analyzed. The mean follow-up was 113.9 ± 10.2 months. Two implants failed. The implant success rate was 90.9%. Twelve membrane samples could be retrieved and analyzed, showing the membrane was still occlusive at 4.2 ± 1.1 months and only beginning to undergo remodeling. Twelve CBCT scans showed that 65.1 ± 9.8 months after surgery, a newly formed cortical layer could be observed in the zone that had undergone grafting. CONCLUSION: The equine cortical bone membrane and the enzyme-treated bone graft used in this case series achieved a medium-term implant and prosthetic success rate that was not dissimilar to that of other resorbable membranes and grafts for peri-implant guided bone regeneration augmentation. Preliminary medium-term histologic and CBCT data suggest that the membrane may be occlusive for a period of at least 4 months and may contribute to preserve the ridge thickness over time.

Chemical, Clinical and Histomorphometric Comparison between Equine Bone Manufactured through Enzymatic Antigen-Elimination and Bovine Bone Made Non-Antigenic Using a High-Temperature Process in Post-Extractive Socket Grafting. A Comparative Retrospective Clinical Study.

Enzyme-deantigenic equine bone (EDEB) and anorganic bovine bone (ABB) are two xenografts made non-antigenic through different processing methods. This study aimed to characterize them for the presence of native bone collagen and other proteins and to compare their histomorphometric outcome when they were used to graft post-extractive sockets. The records of 46 patients treated with EDEB (n = 22) or ABB (n = 24) and followed-up for at least four months after delayed implant placement, were retrospectively collected. Samples of EDEB and ABB were analyzed using Attenuated Total Reflection Fourier Transform Infrared and Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis for the presence of collagen and other proteins. For histomorphometric analysis on bone specimens, newly formed bone and residual biomaterial percentages were calculated. Results of the present study show that EDEB contains type I bone collagen in its native conformation, while no proteins were detected in ABB. Grafting EDEB resulted in a significantly greater quantity of newly formed bone and less residual biomaterial. Our findings suggest that the manufacturing process can greatly affect the graft behavior and a process preserving collagen in its native form may favor bone tissue regeneration.

The Low Window Sinus Lift: A CAD-CAM-Guided Surgical Technique for Lateral Sinus Augmentation: A Retrospective Case Series.

INTRODUCTION: Recently, a rational design of the window osteotomy, the "Low Window" technique, was proposed to facilitate sinus augmentation and reduce postsurgical patient discomfort; this article aims to evaluate its safety and effectiveness. MATERIALS AND METHODS: Records were assessed retrospectively for patients who had sinus lifts using the low window approach, followed by implant placement and prosthetic rehabilitation. Outcomes analyzed were implant and prosthetic success and survival rates and rate of complications. Patients also provided their subjective evaluation on postoperative pain and swelling. DISCUSSION: Records of 22 patients who had 28 interventions (79 implants) were assessed. Average follow-up was 38.4 ± 13.2 months. No cases of intraoperative sinus membrane perforation or other complications occurred, and patients reported a high degree of satisfaction. At the final follow-up, all prostheses and implants were successful. CONCLUSION: The low window sinus lift seems to be an effective technique for reducing the risk of sinus-membrane perforation and patient postsurgical discomfort in lateral sinus augmentation. Prospective, comparative studies are needed to investigate whether the technique is more advantageous than the traditional lateral osteotomy and flap-preparation approaches.

Sinus augmentation and concomitant implant placement in low bone-density sites. A retrospective study on an undersized drilling protocol and primary stability.

BACKGROUND: Recently, a torque-measuring micromotor has been shown to provide a reliable, quantitative intraoperative evaluation of bone density and implant primary stability. This may be particularly useful for determining bone quality of residual bone and consequently the most appropriate site preparation in the posterior maxilla, where bone often is of low density and quality. PURPOSE: This work aimed to assess the medium-term success of implants placed during 1-stage sinus augmentations using an undersized drilling protocol. In case of low bone density, the relationship between residual bone height (RBH) and primary stability was also investigated. MATERIALS AND METHODS: Clinical records of patients who underwent sinus augmentation and concomitant implant placement following a 12.5% undersized drilling protocol were retrospectively analyzed. In all patients, bone density measured intraoperatively was ≤ 0.45 g/cm3 . A minimum of 60 months of follow-up was required for inclusion. RESULTS: Records of 106 patients who received 253 implants were reviewed. No significant difference in the implant success rate was found for patients who had less than 4 mm of RBH and those who had more. CONCLUSIONS: Underpreparation of the implant-placement sites enabled achievement of successful implant-supported rehabilitation of the posterior maxilla even when both RBH and bone density were low.

A Rational Approach to Sinus Augmentation: The Low Window Sinus Lift.

Sinus augmentation is a well-known approach to treating alveolar bone ridge atrophy in the posterior maxilla. The preparation of the lateral window is crucial. Its size, design, and position in the vestibular sinus wall may affect the intra- and postsurgical complication rates and affect the intrasurgical activity of both surgeons and assistants. The present paper describes a rational technique that also exploits the guided surgery approach for design and preparation of a lateral window for sinus augmentation, the Low Window Sinus Lift. To illustrate the use of this approach, a case is presented in which the 50-year-old patient had the left maxillary first molar extracted, followed two months later by sinus augmentation and placement of three implants. One year after delivery of the definitive prosthesis, all three implants were successful, and the prosthesis was fully functional. Controlled studies should be undertaken to assess whether this technique provides significant advantages compared to other sinus augmentation approaches.