Maxillary Sinus Floor Elevation Surgery Research Articles

Research Progress on Titanium Implants for External Maxillary Sinus Augmentation

In patients with missing maxillary posterior teeth, the negative pressure generated by breathing leads to an increase in the gasification of the maxillary sinus cavity, as well as the absorption of alveolar bone due to the lack of physiological stimulation due to missing teeth. This often leads to insufficient bone height during implant restoration in the maxillary posterior tooth area, and maxillary sinus floor elevation surgery can effectively solve this problem. At present, there are two main techniques for lifting the maxillary sinus floor: internal lifting through the top of the alveolar ridge approach and external lifting through the lateral wall approach. Among them, the maxillary sinus alveolar ridge lifting surgery is widely used due to its advantages of small wound size, short surgical time, fewer postoperative complications, low cost, and easy acceptance by patients. With technological innovation, the indications for maxillary sinus floor elevation surgery have gradually expanded to cases with residual bone height (RBH) greater than 2 mm.

Evaluation of volume changes following lateral window maxillary sinus floor elevation using Minics software.

BackgroundSignificant volume changes at the site of lateral window maxillary sinus floor elevation have been reported 6 months postoperatively, with stabilization thereafter. However, at present, there is no consensus regarding the gold standard to assess the shape and volume of the bone graft site after implantation. This study aimed to analyze volume changes in the lateral window maxillary sinus floor elevation region using Minics software.MethodsWe analyzed 40 patients who underwent lateral window maxillary sinus floor elevation surgery at the Stomatology Department of Binhaiwan Central Hospital, Dongguan, China between 2017 and 2020. Twenty patients underwent lateral window maxillary sinus floor elevation with simultaneous implantation, while 20 patients underwent lateral window maxillary sinus floor elevation with delayed implantation 6 months later. Minics software was used for three-dimensional analysis of the elevation site on the day after surgery (T1) and 6 months after surgery (T2) in both groups.ResultsThe elevation site volume was reduced 6 months after lateral window maxillary sinus floor elevation. The differences in the length, width, height from the tip, and volume of the implant between T1 and T2 were statistically significant.ConclusionsThe length, width, height, and volume of the lateral window maxillary sinus floor elevation region were reduced using Minics software, suggesting that the volume of the elevation site should be enlarged as much as possible during the operation to prevent volume shrinkage.

Analysis of the Prevalence, Location, and Morphology of Maxillary Sinus Septa in a Northern Chinese Population by Cone Beam Computed Tomography.

Purpose The purpose of this study is to survey the prevalence and morphology of the maxillary sinus septum, which might increase the rate of maxillary sinus membrane perforation during maxillary sinus floor elevation surgery, among northern Chinese, and to further analyze the relationship between gender, age, edentulous type, and prevalence of maxillary sinus septa. Methods The cross-sectional retrospective study was based on an analysis of Cone Beam Computed Tomography (CBCT) images of maxillary sinus which had been obtained from patients who visited radiology department of Beijing Stomatology Hospital of Capital Medical University (Beijing, China) during the period from January 2019 to December 2019. The data of demographic characteristic, prevalence, position, direction, and morphology of maxillary sinus septum were collected and further analyzed by SPSS version 25.0.1 and R version 3.5.1 software program. Results 595 patients were included in this study, and 1190 maxillary sinuses were analyzed and the incidence rate of the sinus septum was 46.9%. 399 (33.5%) sinuses had one or more septa in 279 (46.9%) patients. In addition, maxillary sinus septa incidence showed no significant differences among gender, age, and edentulous type. The segment second molar had the highest incidence rate of septa. Conclusion In this study, a higher incidence of the maxillary sinus septum was found in the northern Chinese, and its distribution varied with its position, morphology, and direction.

Risk factors for sinus membrane perforation during lateral window maxillary sinus floor elevation surgery: A retrospective study.

To analyze the sinus membrane perforation (SMP) rate and its potential risk factors during lateral window maxillary sinus floor elevation (LSFE). For patients with LSFEs at Department of Implantology, Stomatology Hospital, School of Medicine, Zhejiang Universitiy during January 2014 to December 2020, patient-related risk factors (age/sex/smoking habit), surgery-related risk factors (operator experiment/number of tooth units/technique of osteotomy/surgical approach), and maxillary sinus-related risk factors (residual bone height/sinus membrane thickness/lateral wall thickness/maxillary sinus contours/presence of septa/blood vessels at the lateral maxillary sinus wall) were compared between perforated and nonperforated sites and were evaluated for their influence affecting SMP. The study sample comprised 278 LSFE procedures in 278 patients; a total of 47 LSFE procedures (16.91%) presented SMP. Four significant factors were identified: smoking habit (p < 0.001), thin (≤1.5 mm) sinus membrane (p=0.027), maxillary sinus contours (p < 0.001), and presence of septa (p=0.001). The SMP rate of irregular, narrow tapered, and tapering sinus contours was significantly higher than that of ovoid and square one (p < 0.05). In general, smoking habit, thin sinus membrane, irregular, narrow tapered, and tapering sinus contours, and presence of septa may increase the risk of SMP during LSFE.

Maxillary Sinus Floor Elevation Surgery With BioOss Mixed With Enamel Matrix Derivative: A Human Randomized Controlled Clinical and Histologic Study.

Xenograft bone substitutes are commonly used to increase bone volume and height in the deficient posterior maxilla. The addition of enamel matrix derivate (Emdogain) could increase the efficiency of the bone healing process. The aim of this prospective randomized, controlled split-mouth design study was to compare the percentage of newly formed bone in sinus floor augmentation with deproteinized bovine bone mineral with or without the addition of enamel matrix derivative after 6 months of healing. Sixteen bilateral sinus floor augmentation procedures were performed. Deproteinized bovine bone mineral combined with enamel matrix derivative (test) and deproteinized bovine bone mineral alone (control) groups were randomly allocated within each patient. Six months after augmentation and concurrent to implant placement, bone biopsies were taken for histomorphometric analysis. Additionally, implant survival and peri-implant bone levels were radiographically assessed at baseline and 24 months after functional loading. Histomorphometric analysis revealed a significantly higher amount of newly formed bone in the test group compared with the control group (22.6% and 15.5%, respectively; P = .033). No significant differences in the amount of remaining graft or connective tissue was found. Enamel matrix derivative added to deproteinized bovine bone mineral particles significantly increased new bone formation in sinus lift procedures in edentulous or partially edentulous patients with deficient bilateral posterior alveolar ridges requiring augmentation for implant placement.

Histological analysis of the use of biphasic ceramics based on hydroxyapatite and β-tricalcium phosphate in maxillary sinus floor elevation surgery: pilot study

Abstract Objective To evaluate the bone repair associated with the use of biphasic ceramics based on hydroxyapatite and β-tricalcium phosphate (HA/TCP) in the procedures of maxillary sinus membrane elevation in human beings. Material and method Ten patients with a residual bone ridge in the posterior maxillary region between 3 mm and 5 mm in height were selected and indicated for procedures of bone grafting associated with maxillary sinus lift procedure. The maxillary sinuses were filled with HA/TCP, and after 8 months, the implants were implanted and a bone biopsy was collected with the aid of a trephine drill, which was then submitted to histological analysis for the evaluation of the composition of the grafted area. Result The histological description analysis of the biopsies revealed the presence of vital and immature bone tissue, juxtaposed to the biomaterial. Histomorphometric analysis showed that the biopsy composition was in average 28.8%, 27.4%, and 43.6% of bone tissue, biomaterial, and soft tissue, respectively. Conclusion The areas grafted with HA/TCP presented the adequate amount of bone formation that allowed the implantation of the implants. The success of the grafting procedure with this biomaterial was associated with its osteoconduction potential that allowed the formation of bone tissue in close contact with HA/TCP.

Effect of Schneiderian membrane perforation on sinus lift graft outcome using two different donor sites: a retrospective study of 105 maxillary sinus elevation procedures.

Background: Sinuslift is meanwhile an established method of bone augmentation in the posterior maxilla. Aim of the study was to evaluate the significance of intraoperative Schneiderian membrane perforations during maxillary sinus floor elevation surgery using autogenous bone harvested from two different donor sites using a Safescraper device on the success rate, graft survival and implant integration.Methods: The investigators conducted a retrospective cohort study at the Department of Oral and Maxillofacial Surgery of Military Hospital Ulm composed of patients with severe maxillary atrophy who underwent sinus augmentation from January 2011 until December 2011. Ninety-nine consecutive patients (89 men, 10 women) with a mean age of 43.1 years underwent sinus graft procedures in a 2-stage procedure using the lateral wall approach, as described by Tatum (1986). Data on patient age, smoking status, donor site and surgical complications were recorded and the relationship between Schneiderian membrane perforation and complication rate was evaluated. Dental implants were inserted 4 months after grafting.Results: A total of 105 sinus lift procedures were performed in 99 patients. Sixty-one patients (61.6%) underwent sinus elevation with autogenous bone from the buccal sinus wall, while 38 patients (38.4%) bone harvesting from the iliac crest. Intraoperative perforation of the Schneiderian membrane was observed in 11 of the 105 sinuses (10.4%). These perforations resulted in 4 (36.3%) of the cases in major postoperative complications accompanied by swelling and wound infection. Membrane perforations were slightly associated with the appearance of postoperative complications (p=0.0762). In 2.4% of all cases, regarding 2 patients the final rehabilitation with dental implants was not possible because of extensive bone resorption. Conclusion: Intraoperative complications performing sinus augmentation may lead to postoperative complications. With careful clinical and radiographic evaluation and appropriate treatment, the complications and risk for graft material displacement and implant loss can be eliminated.

An Assessment of the Efficacy of Sinus Balloon Technique on Transcrestal Maxillary Sinus Floor Elevation Surgery

Background: A minimally invasive antral membrane balloon elevation (MIAMBE) has been introduced to overcome the invasiveness of modified Caldwell-Luc (lateral approach) and the drawbacks of the osteotome (summers' technique) in maxillary sinus floor elevation surgery. Materials and methods: A total of 13 adult Iraqi patients aged 28-55 years, 4 males and 9 females underwent sinus floor elevation surgery via crestal approach by using sinus balloon technique. A panoramic radiograph and (Cone beam computed tomography (CBCT)/or medical CT scan) were obtained before and after surgery. Postoperative gained bone was assessed and the patient reactions including pain, nasal bleeding, and ecchymosis were recorded. The whole follow up period was 1year following the sinus lift surgery. Results:The total performed sinus floor elevation cases were 17 with a total of 27 sinus floor elevation sites. The maximum gained bone with sinus balloon technique was 10.6 mm. Twenty three dental implants placed in augmented maxillary sinuses, two implants early failed 8.70 % and the survival rate of the dental implants was (91.30 %). Schneider's membrane perforation didn’t occur in any case of this study 0%. Conclusion: Sinus floor elevation via crestal approach using the balloon technique solve the limitations for original osteotome technique (summers' technique) for cases even when the subantral bone height is less than 3 mm. The utilization of hydraulic pressure in combination with balloon technique also shows a great role in both sinus membrane elevation and as a diagnostic aid of Schneider's membrane perforation. Key words: Sinus lift surgery, antral membrane balloon elevation, Schneiderian membrane perforation.

Maxillary sinus floor elevation surgery with BioOss® mixed with a bone marrow concentrate or autogenous bone: test of principle on implant survival and clinical performance

The purpose of this study was to assess implant survival and 1-year clinical performance of implants placed in the posterior maxilla that had been subjected to maxillary sinus floor elevation surgery with bovine bone mineral (BioOss®) mixed with autogenous bone marrow concentrate or autogenous bone. In a randomized, controlled, split-mouth design study, a bilateral sinus floor augmentation procedure was performed in 12 edentulous patients. At random, one side was treated with BioOss® seeded with an iliac crest bone marrow concentrate enriched in mesenchymal stem cells (test side) and the other with BioOss® mixed with autogenous bone (control side). Three to four months after augmentation, 66 implants were placed. Implant survival, plaque, gingival, and bleeding indices, probing depth, and peri-implant radiographic bone levels were assessed at baseline and 12 months after functional loading. During osseointegration, three implants failed on the test side (two patients) and no implants failed on the control side, resulting in 3-month survival rates of 91% and 100%, respectively. No implants were lost after functional loading and no differences in soft tissue parameters or peri-implant bone loss were observed between the control and test sides. After 1 year in function, no clinically relevant differences were observed regarding soft tissue parameters or peri-implant bone loss.

Engineering of bone using rhBMP-2-loaded mesoporous silica bioglass and bone marrow stromal cells for oromaxillofacial bone regeneration

In present study, CaO–P2O5–SiO2-system mesoporous silica (MS) scaffolds were synthesized and loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2), while their protein release properties and other characteristics were investigated. Furthermore, rabbit bone marrow stromal cells (bMSCs) were cultured and seeded on rhBMP-2-loaded MS (rhBMP-2/MS) scaffolds. Cell adhesion and proliferation were evaluated by scanning electron microscopy (SEM) and MTT assays, while osteogenic differentiation was measured by ALP activity and real-time PCR analysis on the osteogenic markers of runt-related transcription factor 2 (Runx2), collagen type 1 (COL1), osteocalcin (OCN), and osteopontin (OPN). Finally, twenty-four rabbits received unilateral maxillary sinus floor elevation surgery at each time point (2 and 8weeks), and randomly filled with one of the following four materials: MS alone; autologous bMSCs/MS complexes; rhBMP-2/MS complexes; or autologous bMSCs/rhBMP-2/MS complexes. New bone formation and mineralization were detected by histological/histomorphometric analysis, and fluorochrome labeling. The results showed that MS scaffolds presented excellent hierarchically large pore and well-ordered mesopore properties; moreover, rhBMP-2/MS scaffolds efficiently released rhBMP-2 in a sustained manner. Furthermore, rhBMP-2/MS scaffolds significantly enhanced the proliferation and osteogenic differentiation of bMSCs. In the maxillary sinus floor elevation experiments, rhBMP-2/MS scaffolds promoted new bone formation and augmented the height of the sinus floor, while the addition of bMSCs further enhanced new bone formation and mineralization. The present study revealed that CaO–P2O5–SiO2-system MS scaffolds could act as drug delivery carriers for rhBMP-2 and could be used to construct tissue-engineered bone with bMSCs for oromaxillofacial bone regeneration.

Lamb Ex Vivo Model for Training in Maxillary Sinus Floor Elevation Surgery: A Comparative Study With Human Standards

Many models have been suggested for surgical training in sinus floor elevation (SFE), but information on key features that provide feedback to the trainee is scarce. The aim of this study is to compare the thickness of the lateral wall of the maxillary sinus (TLWMS) and the thickness of the Schneiderian membrane (TSM) between an animal model and the human standard. The observational study used 20 fresh lamb heads. Cone-beam computed tomography (CT) was performed for recording the following: TLWMS, sinus lateral floor width, distance from the lateral border of the anteroposterior bone crest to the sinus wall, and height of lateral maxillary sinus. Thirty human radiologic exploration cone-beam CTs were used for comparisons. The sinus membrane thickness was measured at three points per section and compared to those of 10 formalin-preserved human membranes. TLWMS in the animal model scored 2.25 ± 0.3 mm and was thicker than that of humans with subsinusal edentulism (Xi - Xj = 0.3; 95% confidence interval = 0.1 to 0.4), although this difference was not considered clinically relevant. The average thickness of the sinus membrane was 485.5 ± 137.1 μm with no significant differences between sides (P = 0.12) or between the thickness of human and lamb Schneiderian membranes. The model based on lambs is potentially useful for training in SFE techniques because of the similarities in the TLWMS and particularly the TSM. Additional studies are needed to validate this model within a teaching environment.

Maxillary Sinus Floor Augmentation Surgery with Autogenous Bone Grafts as Ceiling: A Pilot Study and Test of Principle

Studies have pointed out that the mere elevation of the maxillary sinus membrane might suffice to allow for bone formation indicating the additional use of augmentation materials to be redundant. The purpose of this study was to assess whether elevation of the sinus mucosal lining combined with applying an autologous bone graft as a ceiling and placement of a short implant would allow for bone formation around the implant thus surpassing the need for applying augmentation materials around the installed implants. Fourteen consecutive patients were subjected to maxillary sinus floor elevation surgery and simultaneous placement of an implant. Using the lateral bone-wall window technique, the membrane was exposed and elevated. Next, a bone graft taken from the zygomatic rim was placed as a ceiling above the inserted implant to ensure that the sinus membrane would not collapsed around a significant part of the implant. Finally, the bone window was returned in place. After connecting the healing abutment, the wound was closed. All implants were stable and no implants were lost. There were no complications after harvesting the bone graft. Radiographic evaluation showed a bone gain of 3.2 ± 0.9 mm after 3 months and 3.6 ± 0.9 mm after 1 year. Less than 6% of the implant was not covered by bone after 1 year. Maxillary sinus membrane elevation and simultaneous placement of short endosseous implants with a bone graft as a ceiling on top of the implant result in predictable bone formation around the implant and good osseointegration on radiographs.

Comparison between Conventional and Piezoelectric Surgical Tools for Maxillary Sinus Floor Elevation. A Randomized Controlled Clinical Trial

The aim of this study was to assess the performance of conventional rotative instruments and a piezoelectric device for maxillary sinus floor elevation surgery, and to assess whether application of a resorbable membrane reduces resorption of an augmented site in a randomized clinical trial. Thirty-six consecutive patients (59.2 ± 10.7 years, range 38-76 years) needing bilateral sinus floor elevation surgery agreed to participate in this study. In a parallel split mouth design randomized clinical trial, in which the allocation of the surgical technique to be used on the determined sites was randomly assigned, one site was always treated with conventional rotative instruments (control group) and the other site with piezosurgery (test group). In addition, in a random order, the grafted sites were covered with a collagen membrane or no membrane. After a healing period of 3-4 months implants were placed. Comparison of clinical features of the test and control sites revealed no differences with regard to wound healing and complications (perforations of the sinus membrane) during or postsurgery (p = .458, p = 1.0, respectively). A clinically insignificant, but statistically shorter operation time was observed when using conventional rotative instruments (11.1 ± 2.4 minutes) than using piezosurgery (15.1 ± 2.9 minutes; p < .001). In both groups, application of a resorbable membrane did not result in less horizontal bone resorption (membrane: 1.43 mm, no membrane: 1.06 mm; p = .062); All 193 implants could be placed with primary stability. One year after functional loading, survival rate was 100%. It can be concluded that, for maxillary sinus floor elevation surgery, a piezoelectric device shows no advantages over rotative instruments as well as that placement of a barrier membrane did not reduce resorption of the augmented site.

Relationship among Schneiderian Membrane, Underwood's Septa, and the Maxillary Sinus Inferior Border

Osseo-integrated implants are increasingly being used to restore functional dentition; however, in the posterior region, implant placement can be problematic because of inadequate bone height. In this condition, maxillary sinus floor elevation surgery has become the treatment of choice. The presence of anatomic variations within the maxillary sinus such as Underwood's septa and thin Schneiderian membrane decreases the success of the sinus floor elevation. In this study, we tried to determine the relationship between the anatomic variations of the maxillary sinus: Underwood's septa, Schneiderian membrane thickness, and the cortical thickness of the inferior border of the maxillary sinus. The left and right maxillary sinus images of 74 patients were obtained by using dental computed tomography (CT). The Schneiderian membrane and the cortical thickness of the inferior border of the maxillary sinus were measured on the coronal images of dental CT scans at the deepest portion of the sinus cavity. The presence of Underwood's septa was identified on the axial images. The correlations between these variables were assessed. We found that there was only a negative correlation between the Schneiderian membrane thickness and the presence of Underwood's septa (r = -0.168 p = .042). It is suggested that Underwood's septa may be the reason for the thinness of the Schneiderian membrane. However, future studies among larger groups are necessary for confirming the finding by using well-designed clinical studies.

Maxillary sinus floor elevation with bovine bone mineral combined with either autogenous bone or autogenous stem cells: a prospective randomized clinical trial

To assess whether differences occur in bone formation after maxillary sinus floor elevation surgery with bovine bone mineral (BioOss(®)) mixed with autogenous bone or autogenous stem cells. The primary endpoint was the percentage of new bone three months after the elevation procedure. In a randomized, controlled split-mouth design, in 12 consecutive patients (age 60.8 ± 5.9 years, range 48-69 years) needing reconstruction of their atrophic maxilla, a bilateral sinus floor augmentation procedure was performed. Randomly, on one side the augmentation procedure was performed with bovine bone mineral (BioOss(®)) seeded with mononuclear stem cells harvested from the posterior iliac crest (test group) while BioOss(®) mixed with autogenous bone (harvested from the retromolar area) was applied on the contra-lateral side (control group). On 14.8 ± 0.7 weeks after the sinus floor elevation, biopsies from the reconstructed areas were taken at the spots where subsequently the endosseous implants were placed. The biopsies were histomorphometrically analyzed. Significantly more bone formation was observed in the test group (17.7 ± 7.3%) when compared with the control group (12.0%± 6.6; P=0.026). In both the test and control group, all implants could be placed with primary stability. In one patient, not all biopsies contained BioOss(®). This patient was excluded from analysis. Mesenchymal stem cells seeded on BioOss(®) particles can induce the formation of a sufficient volume of new bone to enable the reliable placement of implants within a time frame comparable with that of applying either solely autogenous bone or a mixture of autogenous bone and BioOss(®). This technique could be an alternative to using autografts.

RFA Values of Implants Placed in Sinus Grafted and Nongrafted Sites after 6 and 12 Months

Maxillary sinus floor elevation surgery is widely used as a preimplantology method to permit implant insertion. Nevertheless, very few data are available about long-term stability of dental implants inserted in grafted sites. The aims of the present study were to evaluate the evolution of resonance frequency analysis (RFA) values at 6 and 12 months from the implant insertion in sinus grafted sites and nongrafted sites. In 14 patients, 80 Xive implants (Dentsply Friadent GmbH, Mannheim, Germany) were inserted. Sixty-three implants were inserted in a site previously treated with a sinus lift; 17 implants were inserted in healed or postextraction sites. For each implant diameter, length, bone density, insertion torque, and percentage of implant fixed to a nongrafted bone were recorded. RFA values at implant insertion after 6 and 12 months were recorded. After 6 and 12 months, grafted sites showed higher RFA values than the control sites; after 12 months, the difference was statistically significant (.007). A statistically significant positive correlation was found between resonance frequency values and bone quality after 12 months (.05). No statistically significant correlation between RFA values and all the other variables considered was found. Sites treated with sinus lift can offer good long-term stability. After 6 and 12 months, the geometric characteristics of the implant are no longer important to obtain high RFA values, and the bone-implant interface seems to be determinant.

Sequential Fluorescent Labeling Observation of Maxillary Sinus Augmentation by a Tissue‐engineered Bone Complex in Canine Model

AimTo evaluate the effects of maxillary sinus floor elevation by a tissue-engineered bone complex of β-tricalcium phosphate (β-TCP) and autologous osteoblasts in dogs.MethodologyAutologous osteoblasts from adult Beagle dogs were cultured in vitro. They were further combined with β-TCP to construct the tissue-engineered bone complex. 12 cases of maxillary sinus floor elevation surgery were made bilaterally in 6 animals and randomly repaired with the following 3 groups of materials: Group A (osteoblasts/β-TCP); Group B (β-TCP); Group C (autogenous bone) (n=4 per group). A polychrome sequential fluorescent labeling was performed post-operatively and the animals were sacrificed 24 weeks after operation for histological observation.ResultsOur results showed that autologous osteoblasts were successfully expanded and the osteoblastic phenol-types were confirmed by ALP and Alizarin red staining. The cells could attach and proliferate well on the surface of the β-TCP scaffold. The fluorescent and histological observation showed that the tissue-engineered bone complex had an earlier mineralization and more bone formation inside the scaffold than β-TCP along or even autologous bone. It had also maximally maintained the elevated sinus height than both control groups.ConclusionPorous β-TCP has served as a good scaffold for autologous osteoblasts seeding. The tissue-engineered bone complex with β-TCP and autologous osteoblasts might be a better alternative to autologous bone for the clinical edentulous maxillary sinus augmentation.

Anatomical and Surgical Findings and Complications in 100 Consecutive Maxillary Sinus Floor Elevation Procedures

To investigate the prevalence of anatomical and surgical findings and complications in maxillary sinus floor elevation surgery, and to describe the clinical implications. One hundred consecutive patients scheduled for maxillary sinus floor elevation were included. The patients consisted of 36 men (36%) and 64 women (64%), with a mean age of 50 years (range, 17 to 73 years). In 18 patients, a bilateral procedure was performed. Patients were treated with a top hinge door in the lateral maxillary sinus wall, as described by Tatum (Dent Clin North Am 30:207, 1986). In bilateral cases, only the first site treated was evaluated. In most cases, an anatomical or surgical finding forced a deviation from Tatum's standard procedure. A thin or thick lateral maxillary sinus wall was found in 78% and 4% of patients, respectively. In 6%, a strong convexity of the lateral sinus wall called for an alternative method of releasing the trapdoor. The same method was used in 4% of cases involving a narrow sinus. The sinus floor elevation procedure was hindered by septa in 48%. In regard to complications, the most common complication, a perforation of the Schneiderian membrane, occurred in 11% of patients. In 2%, visualization of the trapdoor preparation was compromised because of hemorrhages. The initial incision design, ie, slightly palatal, was responsible for a local dehiscence in 3%. To avoid unnecessary surgical complications, detailed knowledge and timely identification of the anatomic structures inherent to the maxillary sinus are required.

Effects of maxillary sinus floor elevation surgery on maxillary sinus physiology.

In a prospective study, the effects of elevation surgery of the maxillary sinus floor on maxillary sinus physiology were assessed. Seventeen consecutive patients without preoperative anamnestic, clinical and radiological signs of maxillary sinusitis underwent sinus floor elevation surgery with iliac crest bone grafts. All patients were subjected to unilateral endoscopic examination of the maxillary sinus, taking of a biopsy specimen from the sinus floor mucosa, and collection of a sinus lavage-fluid aspirate. This triad of evaluations was performed immediately preceding the elevation procedure, and 3 months (at implant insertion) and 9 months (at uncovering of implants) postoperatively. All procedures were performed under general anesthesia. Preoperatively, three out of 17 patients showed pre-existing mucosal pathology endoscopically, while the 3- and 9-month results revealed the presence of mucosal pathology in four and two patients, respectively. The 3-month microbiological evaluation showed a significant increase in cultures with bacterial growth, while the 9-month culture results were comparable to the preoperative status of the maxillary sinus. Morphologically, neither fibrosis nor an altered inflammatory response or thickening of the epithelium and lamina propria was observed postoperatively. The number of goblet cells in the epithelial layer was increased. From this study it is concluded that the effect of maxillary sinus floor elevation surgery with autogenous bone grafts does not appear to have clinical consequences in patients without signs of pre-existing maxillary sinusitis.