Edentulous Posterior Maxilla Research Articles

A Randomized Controlled Clinical Trial of Two Types of Tapered Implants on Immediate Loading in the Posterior Maxilla and Mandible

The aim of this study was to compare clinical outcomes and stability following immediate loading of two types of tapered implants in the partially edentulous posterior maxilla and mandible. A randomized controlled trial with 1 year of follow-up was performed on participants missing two consecutive teeth in a posterior quadrant with tapered implants with a hybrid textured surface. Group 1 received Osstem TSIII HA implants, and group 2 received Zimmer TSV implants. Group 1 implants were 4.5 or 5.0 mm in diameter, and group 2 implants were 4.7 mm in diameter; all implants were 10 mm long. Subjects received provisional restorations within 48 hours. Definitive restorations were provided 3 months (mandible) or 6 months (maxilla) later. Outcome measures were survival and success rates, marginal bone level change, implant stability quotient, and peri-implant soft tissue indices. Fifty participants completed the trial (group 1: 52 implants in 26 patients; group 2: 48 implants in 24 patients). The success rates were similar--98.1% in group 1 and 97.9% in group 2--at 12 months after immediate loading, but marginal bone loss was significantly different according to the implant design. Implant stability increased significantly in both arches. There were no significant differences in soft tissue indices between implant systems. If high primary stability is acquired, tapered implants with hybrid textured surfaces are predictable for immediate loading in the posterior maxilla and mandible. In spite of the influence of implant design on marginal bone loss, all tapered implants showed successful clinical outcomes and stability in immediate loading.

Comparative Clinical Study of Three-Unit Fixed Partial Prostheses Supported by Two or Three Implants

To compare clinical outcomes of three-unit fixed prostheses supported by two or three implants in the posterior region. Patients in this retrospective study were restored with three-unit fixed partial prostheses supported by two (group 1) or three (group 2) implants in the partially edentulous posterior maxilla and mandible. Outcome measures were survival and success rate, marginal bone loss, complication rate, and peri-implant soft tissue indices. Two-way ANOVA and an independent t test were performed at a significance level of P < .05. A total of 48 implants placed in 23 patients (group 1) and 132 implants placed in 40 patients (group 2) were observed for 52.9 ± 19.7 months and 58.5 ± 22.0 months, respectively. Both groups showed a 100% survival rate. The success rate, considering marginal bone loss, was 82% (group 1) and 86% (group 2). Marginal bone loss was greater in group 1 every year during 3 years of measurement, but the difference was not statistically significant (P > .05). Differences of marginal bone loss according to sex, anatomical location (maxilla vs mandible), and connection type (external vs internal) also were not significant (P > .05). Complication rates were similar, but Plaque Index was significantly greater in group 2 (P < .05). Within the limitations of this study, three-unit fixed partial prostheses supported by two implants showed comparable clinical outcomes with those supported by three implants in the partially edentulous posterior maxilla and mandible during the short- to medium-term.

Minimally Invasive Sinus Augmentation Using Ultrasonic Piezoelectric Vibration and Hydraulic Pressure

The purpose of this study was to evaluate the success rate of implants and vertical bone gain of edentulous posterior maxilla using ultrasonic piezoelectric vibration and hydraulic pressure, namely the hydrodynamic piezoelectric internal sinus elevation (HPISE) technique through a crestal approach. A total of 250 maxillary sinuses were augmented using HPISE and 353 implants (averaging 11.8 mm in length and 4.5 mm in diameter), with 12 different systems, were placed simultaneously with or without additional bone grafting. Plain radiograms and cone beam computed tomograms were taken in all patients to evaluate sinus augmentation. Membrane perforation was recorded at 10 of the 353 implant sites. The perforation rate was 2.83%. The total success rate of implantation was 97.2% after an average of 69.3 weeks of loading. The crestally approached sinus augmentation using ultrasonic piezoelectric vibration and hydraulic pressure is an additional method of maxillary sinus augmentation.

Rehabilitation of the Edentulous Posterior Maxilla After Sinus Floor Elevation Using Deproteinized Bovine Bone

To evaluate the long-term survival rate of rough-surfaced implants placed in maxillary sinuses augmented with deproteinized bovine bone (Bio-Oss; Geistlich Pharma AG, Wolhusen, Switzerland). Thirteen maxillary sinuses were augmented in 10 patients with Bio-Oss. After an average healing period of 13.8 months, 24 implants were placed. In 4 cases, biopsies were performed and submitted to histological analysis. Clinical and radiographic evaluation was performed 9 years after implant placement and minimum 8 years after functional loading. At the 9-year control, all the 24 implants were still functional. Thus, the implant survival rate was 100%. Bio-Oss is an acceptable substitute to the autogenous bone, and it can be used as a unique material for sinus floor elevation. Rough-surfaced implants placed in 100% Bio-Oss grafts showed a high survival rate (100%) on the long term. Larger clinical trials are necessary to confirm our results.

Maxillary Sinus Elevation by Lateral Window Approach: Evolution of Technology and Technique

Context: The maxillary sinus elevation procedure has become an important pre-prosthetic surgical procedure for the creation of bone volume in the edentulous posterior maxilla for the placement of dental implants. Research and clinical experience over the past 30 years has increased the predictability of this procedure as well as reduced patient morbidity.Evidence Acquisition: Data on grafting materials and implant survival rates comes from 10 published evidence-based reviews that include all relevant published data from 1980 to 2012. Supporting clinical material comes from the experience of the authors.Evidence synthesis: The evidence-based reviews report and compare the implant survival rates utilizing various grafting materials, implant surfaces, and the use or non-use of barrier membranes over the lateral window. Clinical studies report on complication rates utilizing piezoelectric surgery and compare them to complication rates with rotary instrumentation.Conclusions: The conclusions of all the evidence-based reviews indicate that the utilization of bone replacement grafts, rough-surfaced implants, and barrier membranes result in the most positive outcomes when considering implant survival. Further, the utilization of piezoelectric surgery, rather than rotary diamond burs, for lateral window preparation and membrane separation leads to a dramatic reduction in the occurrence of the intraoperative complications of bleeding and membrane perforation.

Maxillary Sinus in relation to Modern Oral and Maxillofacial Surgery

Maxillary Sinus in relation to Modern Oral and Maxillofacial Surgery

Schneider Membrane Elevation in Presence of Sinus Septa: Anatomic Features and Surgical Management

Maxillary sinus floor elevation via a lateral approach is a predictable technique to increase bone volume of the edentulous posterior maxilla and consequently for dental implants placement. The sinus floor is elevated and it can be augmented with either autologous or xenogeneic bone grafts following an opening bone window created on the facial buccal wall. Maxillary septa are walls of cortical bone within the maxillary sinus. The septa shape has been described as an inverted gothic arch arising from the inferior or lateral walls of the sinus and may even divide the sinus into two or more cavities. Some authors have reported a higher prevalence of septa in atrophic edentulous areas than in nonatrophic ones. Radiographic identification of these structures is important in order to perform the right design of the lateral window during sinus lift. Aim of this investigation is to highlight the correct steps for doing sinus lift surgery in presence of those anatomic variations. Clinicians should always perform clinical and radiographic diagnosis in order to avoid complications related to the sinus lift surgery.

Osteotome-Mediated Sinus Lift without Grafting Material: A Review of Literature and a Technique Proposal.

Implant rehabilitation of the edentulous posterior maxilla may be a challenging procedure in the presence of insufficient bone volume for implant placement. Maxillary sinus augmentation with or without using grafting materials aims to provide adequate bone volume. The aim of the present study was to systematically review the existing literature on transalveolar maxillary sinus augmentation without grafting materials and to propose and describe an osteotome-mediated approach in postextraction sites in combination with platelet derivative. The systematic review showed that high implant survival rate (more than 96% after 5 years) can be achieved even without grafting the site, with a low rate of complications. Available alveolar bone height before surgery was not correlated to survival rate. In the described case report, three implants were placed in posterior maxilla after extraction of two teeth. An osteotome-mediated sinus lifting technique was performed with the use of platelet derivative (PRGF); a synthetic bone substitute was used to fill the gaps between implant and socket walls. No complications occurred, and implants were successfully in site after 1 year from prosthetic loading. The presented technique might represent a viable alternative for the treatment of edentulous posterior maxilla with atrophy of the alveolar bone though it needs to be validated by studies with a large sample size.

Assessment of Bone Density in the Posterior Maxilla Based on Hounsfield Units to Enhance the Initial Stability of Implants

The poor bone quality that exists in the posterior maxilla is associated with lower initial stability and higher failure rates in implants. This study examined the bone densities of edentulous posterior maxillae by computed tomography (CT). Based on CT images, the voxel values representing implant replacement in the posterior maxillary regions of 30 patients were calculated in the range from 150 to 2,000 Hounsfield units (HU). The bone densities of these regions were categorized according to Misch's classification and compared among individuals and between sexes. The average of the median individual CT values was 495 HU (95% confidence interval: 442-547 HU) and was significantly higher in males than in females. Most of the bone in the posterior maxillae was classified as D3 (350-850 HU) or D4 (150-350 HU) according to Misch's classification, comprising 50% and 32% of the entire regions, respectively. More than 80% of the edentulous posterior maxillae consisted of porous cortical crest or no cortical bone according to CT, although the bone densities varied markedly among individuals. More detailed assessments of bone density may be useful to enhance initial stability of implants in the posterior maxilla.

Immediate and Early Loading of Chemically Modified Implants in Posterior Jaws: 3‐Year Results from a Prospective Randomized Multicenter Study

There is a lack of well-designed prospective, randomized clinical trials evaluating the efficacy of immediate and early loading of implants placed in the partially edentulous posterior maxilla or mandible. The aim of this study was to evaluate crestal bone level changes over 3 years following immediate or early loading of Straumann implants with a chemically modified surface (SLActive®, Institut Straumann AG, Basel, Switzerland) placed in the posterior maxilla and mandible. Subjects received temporary restorations immediately or 28 to 34 days after surgery, with permanent restorations placed at 20 to 23 weeks. Bone level changes were measured by comparison of standardized radiographs taken on the day of implant placement and 5, 12, 24, and 36 months thereafter. Two hundred thirty-nine of two hundred sixty-six patients (89.9%) completed the trial. Implant survival rates were 97.4% and 96.7% in the immediate and early loading groups, respectively (p = not significant). Over 36 months, the mean bone level change for immediately loaded implants was 0.88 ± 0.81 mm versus 0.57 ± 0.83 mm for the early-loaded group (p < .001). After adjusting for a slight difference in initial placement depth, the time of loading had no significant influence on bone level change. Changes in crestal bone level occurred mostly during the first 5 months postloading. After this bone remodeling period, crestal bone level was stable up to 36 months. Implants with a chemically modified surface are safe and predictable for immediate and early loading in the posterior maxilla and mandible.

Anatomical structures in the maxillary sinus related to lateral sinus elevation: a cone beam computed tomographic analysis

The objective of this study is to evaluate the anatomical structures in the maxillary sinus with relation to lateral approach sinus elevation utilizing cone beam computed tomography (CT) scans taken prior to sinus elevation surgery. A total of 150 CT images were acquired from 150 patients (90 men and 60 women; mean age, 49.4 years, range 23-86 years) who were being treated with implant-supported restorations in the posterior edentulous maxilla. Of the 150 CT scans, 65 were of the right sinus and 85 of the left sinus. Measurements of the anatomical structures in the maxillary sinus were conducted on the CT images. In the mean width of the lateral wall, there were statistically significant values among the measurement points (P < 0.05). The anterior area of the sinus lateral wall was thicker than the posterior lateral wall. There was a statistically significant difference between the vessel diameter and lateral wall width (P < 0.05). As sinus lateral wall width increased, so did the vessel diameter. The mean distance to the inferior border of the vessel from the sinus floor and from the alveolar crest was 8.25 and 17.03 mm, respectively. The intraosseous group among the vessel position was 64.3%, so the intraosseous vessel could be visualized in CT scans at 64.3%. In angle A, the group of less than 30° was 4.8%. Schneiderian membrane perforation by narrow angle had a low risk. The prevalence of the septa related to Schneiderian membrane perforation was 44%. The distance to the inferior border of the vessel from the alveolar crest being less than 15 mm was 31%. The vessel diameter greater than 1 mm was 37.8%. Based on present research about utilizing cone beam CT scans for sinus elevation, the alteration of the lateral approach sinus elevation technique is highly recommended if complications such as membrane perforation or bleeding are expected.

Clinical Evaluation of Demineralized Bone Allograft for Sinus Lifts in Humans: A Clinical and Histologic Study

Severe alveolar bony resorption in the edentulous posterior maxilla and pneumatization of the maxillary sinus wall make traditional implant placement impossible in the posterior maxilla. To reconstruct the severely resorbed maxilla for dental implant placement, 1 successful technique is to elevate the maxillary sinus floor using demineralized bone matrix (DBM) grafts. The purpose of this study was to evaluate a histologic and histomorphometric evaluation of DBM grafts in the human maxilla. Nine months after grafting, at the time of dental implantation, biopsy samples were taken from the grafted areas of 8 patients and were analyzed histologically. All the sinus lifts were successful in the clinical study conducted after implantation. Resorption of the graft materials and new bone formation were observed, and there was direct deposition of bone on the surface of the graft particles. The results of this study indicate that limited maxillary sinus lift with DBM graft material is a clinically reliable preimplant procedure.

Displacement of three dental implants into the maxillary sinus in two patients. Report of two cases

Reconstruction of the posterior edentulous maxilla with dental implants has become a popular practice worldwide. However, the poor bone quality and quantity in this area is sometimes related with complications. Dental implant displacement into the maxillary sinus is a rare complication. In the present paper, we present two patients with three implants displaced into the maxillary sinus. The implants were removed soon after their displacement, using the classic intraoral approach, through the anterior wall of the maxillary sinus. The operation was performed under local anesthesia for both of the patients. The postoperative course was uneventful for both of the patients without any wound dehiscence. Recovery remained uneventful, without any signs of postoperative sinusitis. Implant displacement into the maxillary sinus is of rare occurrence and usually related to inadequate bone quality and quantity. Dental implants into the maxillary sinus usually act as foreign bodies and should be removed, to avoid the development of sinus complications. Removal of dental implants from the maxillary sinus can be performed either with functional endoscopic sinus surgery, or with intraoral operation through the anterior maxillary wall especially in fresh cases and in the presence of oroantral communication.

Clinical, Histological, and Histomorphometrical Analysis of Maxillary Sinus Augmentation Using Inorganic Bovine in Humans: Preliminary Results

The aim of the present study was to evaluate bone formation after maxillary sinus augmentation using bovine bone substitute material Bio-Oss alone by means of clinical, histological, and histomorphometrical examination of human biopsies. Deproteinized bovine bone (DPBB, Bio-Oss) was used to fill cavities after elevation of the sinus mucosa following major sinus pneumatization. Twenty patients with edentulous posterior maxillae were treated with 20 sinus augmentation procedures using a 2-stage technique. Residual lateral maxillary bone height was less than 3 mm. Forty-nine Straumann endosseous implants were used to complete the implant-prosthetic rehabilitation. Forty cylinder-shaped bone biopsies were taken from the augmented maxillary region 8 months after grafting during the second-stage surgery before implant placement. All implants were loaded 3 months after insertion, and no failures were recorded. Histomorphometrical analysis showed an average percentage of newly formed bone of 17.6% (± 2.8%) and a proportion of residual bone substitute material of 29.9% (± 4.9%) of the total biopsy area. Intimate contact between newly formed bone and Bio-Oss was detected along 28.2% (± 6.8%) of the particle surfaces. The results also showed that in all cases, the DPBB granules had been interconnected by bridges of vital newly formed bone. Inorganic bovine bone appears to be biocompatible and osteoconductive, and it can be used with success as a bone substitute in maxillary sinus augmentation procedures.

Expression of MMP‐2, 9 and 13 in newly formed bone after sinus augmentation using inorganic bovine bone in human

The aim of the present study was to analyse the expression of MMP-2, MMP-9 and MMP-13 in newly formed bone following maxillary sinus augmentation using inorganic bovine bone substitute, because these MMPs play a major role in bone remodeling and bone resorption. Deproteinized bovine bone (Bio-Oss(®)) was used to fill cavities after elevating the sinus mucosa. Twenty patients with edentulous posterior maxilla were treated with 20 sinus-augmentation procedures using a two-stage technique. Forty-nine Straumann(®) endosseous implants were used to complete the implant-prosthetic rehabilitation. One cylinder-shaped bone biopsy from each patient was taken from the augmented maxillary region using trephine burs at the second stage of surgery, 8 months after grafting. A biopsy was also taken as a control from the upper molar region from six different patients who did not undergo the sinus procedure. All biopsies were subjected to biochemical analysis and staining for TRAP. No implant losses or failures occurred. The large number of TRAP-positive multinucleated osteoclasts in resorption lacunae indicated that the resorption was very active in all grafts, in contrast with the control group. Zymography and western blot analysis demonstrated a significantly increased expression of MMP-2, MMP-9 and MMP-13 in the newly formed bone compared with controls (p < 0.05). The quantity of osteoclastic cells and the increased expression of proteolytic enzymes suggest that 8 months after grafting, inorganic bovine bone is slowly resorbing and is the site of important remodeling of the newly formed bone by means of resorption and synthesis.

Tissue-Engineered Polymer-Based Periosteal Bone Grafts for Maxillary Sinus Augmentation: Five-Year Clinical Results

Augmentation of the maxillary sinus with allogenic or alloplastic materials, as well as autologous bone grafts, has inherent disadvantages. Therefore, the aim of our study was to evaluate the long-term clinical repair effect of autologous periosteal bone grafts on atrophic maxillary bone. In the present retrospective cohort study, augmentation of the edentulous atrophic posterior maxilla was performed using autologous tissue-engineered periosteal bone grafts based on bioresorbable polymer scaffolds and, in a 1-step procedure, simultaneous insertion of dental implants. The clinical evaluation of 10 patients was performed by radiologic assessment of bone formation, with a follow-up of 5 years. Bone formation was further documented by measuring the bone height and by histologic examination. Excellent clinical and radiologic results were achieved as early as 4 months after transplantation of the periosteal bone grafts. The bone height remained significantly (P < .05) greater (median 14.2 mm) than the preoperative atrophic bone (median 6.9 mm) during the 5-year observation period. Histologically, the bone biopsy specimens of 2 patients obtained after 6 months showed trabecular bone with osteocytes and active osteoblasts. No signs of bone resorption, formation of connective tissue, or necrosis were seen. Our results suggest that the transplantation of autologous periosteal bone grafts and implantation of dental implants in a 1-step procedure is a reliable procedure that leads to bone formation in the edentulous posterior maxilla, remaining stable in the long term for a period of at least 5 years.

The alveolar process of the edentulous maxilla in periodontitis and non‐periodontitis subjects

Early implant failures may document that the bone tissue or the wound-healing process following installation surgery was compromised. Subjects who have lost teeth for periodontal reasons exhibit more earlier implant failures than subjects who had experienced tooth loss for other reasons. To describe the tissue of the fully healed extraction sites in subjects who had lost teeth as a result of periodontitis or for other reasons. Thirty-six otherwise healthy, partially dentate subjects with fully healed edentulous portions in the posterior maxilla were included. Nineteen of these subjects had lost teeth because of advanced periodontitis (group P) and 17 for other reasons (group NP). Using a trephine drill, a 4-6 mm long hard tissue specimen was harvested. The biopsies were decalcified, embedded in paraffin, sectioned, stained and examined. The edentulous posterior maxilla was comprised of 47.1 ± 11% lamellar bone, 8.1 ± 7.1% woven bone, 4.3 ± 3.1% osteoid and 16.5 ± 10.4% bone marrow. There were no significant differences in the tissue composition of post-extraction sites of (i) P and NP subjects and (ii) premolar and molar sites. More than 50% of the edentulous maxilla was comprised of mineralized bone (lamellar and woven bone). The bone trabeculae frequently appeared to have a random orientation. The direction of the trabeculae rather than the lack of mineralized bone tissue may explain the clinical impression that the bone in the posterior maxilla provides limited resistance to mechanical instrumentation.

Soft tissue development around abutments with a circular macro‐groove in healed sites of partially edentulous posterior maxillae and mandibles: a clinical pilot study

The aim of this study was to evaluate soft tissue development at concave circular macro-grooved titanium abutments in healed sites. In a split-mouth pilot study 10 patients received two implants each at healed posterior sites in contralateral maxillary or mandibular jaw quadrants. Either circular macro-grooved concave study abutments or conventional convex control abutments were immediately provisionalized and received permanent crowns 3 months postimplantation. Marginal bone level, papilla index, modified plaque and bleeding index were recorded. The esthetic outcome was evaluated with standardized perpendicular pictures according to the Pink Esthetic Score (PES). Statistical analysis included the description of all variables by mean value, standard deviation and range. PES values were compared using the Wilcoxon signed rank test for paired data. Cumulative survival rate for all 20 implants was 100%. At the 1-year follow-up, there was no statistical significant difference of marginal bone levels between sites restored with the study (-0.11 ± 0.77 mm) vs. the control (-0.34 ± 0.53 mm) abutments (P>0.05). Esthetic evaluation (PES) revealed statistically significant differences in scores between the study group [study abutment group] (7.2 ± 2.82, 8 ± 1.89) and the control group [control abutment group] (9.5 ± 1.58, 10.5 ± 1.72) at the time of prosthetic delivery and the 1-year follow-up. Whereas PES scores for mesial papilla at control sites at the 1-year follow-up demonstrated statistically significant higher values, both soft tissue level and soft tissue contour at control sites revealed statistically significantly higher PES values (P<0.05) at time of prosthetic delivery and at 1-year follow-up when compared with study sites. Concave macro-grooved abutments in healed posterior maxillary and mandibular sites did not exhibit a superior soft tissue development compared with standard convex abutments.

Porcine Bone Used in Sinus Augmentation Procedures: A 5-Year Retrospective Clinical Evaluation

Rehabilitation of the edentulous posterior maxilla with dental implants often represents a clinical challenge because of the insufficient bone volume resulting from pneumatization of the maxillary sinus and crestal bone resorption. The aim of this study was a retrospective clinical evaluation of maxillary sinus augmentation using porcine bone. One hundred twenty-one healthy patients with a noncontributory medical history were included in this study. All patients underwent sinus augmentation procedures with porcine bone. After a 4- to 6-month healing period, sandblasted and acid-etched implants were inserted. All grafted sinuses healed without major complications, except for 2 that showed no regeneration at the time of implant placement. A total of 21 implants were lost, 8 after the second-stage surgery and 13 in the 5 years' follow-up after loading. The cumulative survival rate was 92% after a mean loading time of 5 years. Only minor peri-implant marginal bone resorption was found. Within the limitations of this study, porcine bone can be used with success in sinus augmentation procedures, and rougher-surfaced implants are probably preferable.

Extrasinus Zygomatic Implants: Three Year Experience from a New Surgical Approach for Patients with Pronounced Buccal Concavities in the Edentulous Maxilla

The surgical protocol for zygomatic fixtures prescribes an intrasinus approach ideally maintaining the sinus membrane intact and the implant body inside the sinus while gaining access to the zygomatic bone. In the presence of a pronounced buccal concavity, the implant head has to be placed far from the alveolar crest in a palatal direction, which results in a bulky bridge construction. The aim of this study was to report on the preliminary experiences with zygomatic implants placed with an extrasinus approach in order to have the implant head emerging at or near the top of the alveolar crest. Twenty consecutive patients with pronounced buccal concavities in the edentulous posterior maxilla were treated with 104 regular and 36 zygomatic implants as support of fixed dental bridges. Sixteen patients were treated bilaterally and four patients were treated unilaterally. The zygomatic implants were inserted by using an extrasinus surgical approach with the implant body passing from the alveolar crest through the buccal concavity into the zygomatic bone. This enabled placement of the implant head at or close to the alveolar crest. The patients were followed from 36 to 48 months after occlusal loading with a mean follow-up of 41 months. The relation of the zygomatic implants to the crest was measured and compared with a control group of 20 patients treated with conventional placement of zygomatic implants. No implants were lost during the study period. No pain, discomfort, or complications related to the extrasinus path of the zygomatic implants were recorded after the initial healing period and up to the 36th-month checkup. The zygomatic implants emerged, on average, 3.8 mm (SD 2.6) palatal to the top of the crest compared with 11.2 mm (SD 5.3) to the conventional technique. The present 3-year clinical study shows that an extrasinus approach can be utilized when placing zygomatic implants in patients with pronounced buccal concavities in the posterior maxilla. Moreover, the technique results in an emergence of the zygomatic fixture close to the top of the crest, which is beneficial from a cleaning and patient-comfort point of view.