The influence of sinus membrane thickness upon membrane perforation during transcrestal sinus lift procedure

Radiographic outcomes of lateral sinus floor elevation at sites without perforations and sites with perforations managed with a resorbable membrane: A retrospective study

AIM

To evaluate the radiographic outcomes of lateral sinus floor elevation with simultaneous implant placement at sites without sinus membrane perforation (SMP) and sites with SMP managed with a resorbable membrane.

MATERIALS AND METHODS

One hundred and thirty-nine patients and 170 implants (56 perforation, 114 non-perforation) were included. Cone-beam computed tomography (CBCT) images were taken before surgery (T0), immediately after surgery (T1) and 6 months after surgery (T2). Post-operative augmentation parameters, including endo-sinus bone gain (ESBG) along the implant axis, mean new bone height (NBH) surrounding the implant and augmentation volume (AV), were measured at T1 and T2.

RESULTS

At T1, there were no significant differences in ESBG, NBH and AV between the two groups. At T2, although ESBG did not significantly differ between the two groups, NBH (8.50 ± 1.99 mm vs. 9.99 ± 2.52 mm, p = .039) and AV (519.37 ± 258.38 mm3 vs. 700.99 ± 346.53 mm3, p < .001) were significantly lower in the perforation group. The shrinkage of graft material from T1 to T2, including ΔESBG (p = .002), ΔNBH (p < .001) and ΔAV (p < .001), was higher in the perforation group.

CONCLUSIONS

SMP during LSFE with simultaneous implant placement is associated with greater resorption of the grafted area at a 6-month follow-up.

Maxillary sinus membrane perforation rate utilizing osseodensification-mediated transcrestal sinus floor elevation: A multicenter clinical study

PURPOSE

This multicenter cross-sectional clinical study aimed to evaluate the membrane perforation rate during transcrestal sinus floor elevation (TSFE) using osseodensification (OD) burs and assess risk factors associated with the procedure.

MATERIALS AND METHODS

This study was conducted in six centers, following ethical standards and approved by local committees. It included patients over 18 years old missing maxillary posterior teeth with crestal residual bone height (RBH) ≥2 and ≤6 mm. Preoperative evaluations were done, including CBCT scans, to assess bone dimensions and sinus health. All centers and surgeons followed a standardized surgical protocol for TSFE using OD burs. Surgical complications, particularly sinus membrane perforations, were recorded and analyzed. Factors such as implant site, premolars or molars, as well as, healed or fresh socket, along with initial RBH were evaluated for their impact on membrane perforation rate. Descriptive statistics, χ2, and logistic regression analysis were used to analyze the data.

RESULTS

A total of 621 subjects with an average age of 57.9 years were included. Sinus lifting was performed at 670 sites, with 621 implants placed in the maxilla. The majority of sinus lifts were done in the molar region (76.87%) and in healed bone sites (74.33%). The average RBH was 5.1 mm (ranging from 2 to 7 mm). Sinus membrane perforation occurred in 49 cases (7.31%). RBH ≤3 mm posed a risk factor for sinus membrane perforations followed by RBH >3 and ≤5 mm. Tooth region and implant site were not associated as risk factors for sinus membrane perforation.

CONCLUSION

OD drilling used for TSFE resulted in low membrane perforation rate. Challenging scenarios of severe posterior maxillary atrophy presented as risk factors for increased perforation rate.

Sinus membrane thickness of healthy endodontically treated maxillary molars

OBJECTIVE

The study aimed to investigate the sinus membrane thickness (SMT) adjacent to healthy endodontically-treated maxillary molars with or without protruded apical foramen into the sinus cavity using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Images of 207 non-smoker patients aged 18-40 were retrospectively analyzed, 140 were endodontically treated, and 136 were without endodontic treatment. Patients with any sinus pathology, teeth that have symptoms, or poor root filling were excluded. Study groups consisted of Group EM-I (endodontically treated and protruded apical foramen), Group EM-C (endodontically treated and contacted apical foramen), and similarly without endodontic treatment; Group M-I and Group M-C. SMT upon the mesial, distal, and palatal roots was measured. One-way ANOVA and Student's t-tests were performed.

RESULTS

Group EM-I had the thickest sinus membrane compared to other groups (p = 0.013). SMT values were 2.37-2.60 mm in Group EM-I, and 1.34-1.58 mm in other groups. Thickening (> 2 mm) percentages were 33.45% in Group EM-I and between 4.25 and 8.25% in other groups. No statistical difference was detected between first and second molars and genders (p > 0.05).

CONCLUSION

When the apical foramen protruded into the sinus cavity, the conventional root canal treatment caused a minimal (between 2.37 mm and 2.60 mm) sinus membrane thickening with a rate of 33.45% based upon CBCT examinations.

Influence of Schneiderian Membrane Perforation on Implant Survival Rate: Systematic Review and Meta-Analysis

Background: Maxillary sinus lift is a well-documented and accepted technique in the rehabilitation of the posterior maxilla. Schneiderian membrane perforation is the most common complication and may occur in between 7% and 56% of cases. Different materials and techniques have been described to achieve reparation of the perforation. The aim of this study was to establish whether the perforation of the Schneiderian membrane and its repair during maxillary sinus lift surgery results in a lower implant survival rate compared to those cases where the membrane has not been perforated. Materials and methods: A systematic review and meta-analysis of studies assessing the survival rate of implants placed in regenerated sinus using the lateral window approach, where the perforation of the Schneiderian membrane occur, was carried out. Statistical analysis was performed with Open Meta-Analyst, calculating the odds ratio of implants placed in perforated sinuses and non-perforated sinuses. Results: Ten articles were included in the qualitative analysis and seven articles in the quantitative analysis or meta-analysis. A total of 1224 maxillary sinus augmentation surgeries were performed without perforation of the Schneiderian membrane and 2725 implants were placed; 62 implants failed during the follow-up period with an overall survival rate of 97.7%. In 480 perforated sinuses, 1044 implants were placed, of which 30 failed; the overall survival rate was 97.1%. There were no significant differences between the implant survival rate of the implants in the two groups (OR = 0.78; CI = 0.49-2.23; p = 0.28 and I2 heterogeneity: 0%, p = 0.44). Conclusions: Schneiderian membrane perforation, as long as it is repaired, does not appear to negatively influence implant survival rate. Membrane perforation should not be considered a reason to abort the procedure or an absolute contraindication to implant placement.

Maxillary sinus augmentation via the bone lid technique: A prospective, radiographic case series

BACKGROUND

Maxillary sinus augmentation is one of the most performed procedures to increase the bone quantity of the atrophic maxilla to allow implant placement. The aim of the present case series was to describe a surgical protocol to perform maxillary sinus augmentation with the "bone lid technique," and its outcomes in a cohort of patients eligible for the procedure.

METHODS

After the initial clinical evaluation, a cone-beam computed tomography (CBCT) examination was performed for preoperative assessment. Patients were then scheduled for surgical intervention. At 6-9 months follow-up, patients underwent a second CBCT scan to evaluate bone height following bone graft and to schedule implant placement.

RESULTS

A total of 11 patients were enrolled in the study with a total of 13 sinus lift procedures. Membrane perforation was registered in 4 cases (30.76%). Mean surgical time was 67.69 min (SD 6.51). Postoperative period was uneventful in all patients, in the absence of complications. The mean graft volume increase was 2.46 cm3 (SD 0.85), and the mean height increase was 14.27 mm (SD 3.18). Mean membrane thickness was 1.40 mm (SD 0.75). In all the 4 cases with sinus membrane perforation, the membrane had a thickness lower than 1 mm.

CONCLUSIONS

The present study highlights that the maxillary sinus augmentation with bone lid repositioning could provide repeatable results in terms of bone height increase. The technique appears reliable both in terms of bone gain and absence of complications.

KEY POINTS

The bone lid technique for maxillary sinus augmentation provides repeatable results in terms of bone height increase. The favorable clinical outcomes can be related to an enhancement of bone formation due to the unique osteoconductive and osteoinductive properties of autogenous bone, along with a reduction of soft tissue ingrowth. Complications were not observed in any of the patients following the surgical procedures. The risk of Schneiderian membrane perforation is inversely proportional to membrane thickness; the thinner the membrane is, the higher the risk to perforate it.

Maxillary sinus floor augmentation: a review of current evidence on anatomical factors and a decision tree

Maxillary sinus floor augmentation using lateral window and crestal technique is considered as predictable methods to increase the residual bone height; however, this surgery is commonly complicated by Schneiderian membrane perforation, which is closely related to anatomical factors. This article aimed to assess anatomical factors on successful augmentation procedures. After review of the current evidence on sinus augmentation techniques, anatomical factors related to the stretching potential of Schneiderian membrane were assessed and a decision tree for the rational choice of surgical approaches was proposed. Schneiderian membrane perforation might occur when local tension exceeds its stretching potential, which is closely related to anatomical variations of the maxillary sinus. Choice of a surgical approach and clinical outcomes are influenced by the stretching potential of Schneiderian membrane. In addition to the residual bone height, clinicians should also consider the stretching potential affected by the membrane health condition, the contours of the maxillary sinus, and the presence of antral septa when evaluating the choice of surgical approaches and clinical outcomes.

Changes in sinus mucosal thickening in the course of tooth extraction and lateral sinus augmentation with surgical drainage: A cone-beam computed tomographic study

OBJECTIVES

The objective of the study was to evaluate the radiographic changes in sinus mucosal thickness (SMT) in patients with mucosal thickening of odontogenic origin after maxillary molar extraction and lateral sinus augmentation with simultaneous surgical drainage and implant placement.

MATERIALS AND METHODS

Forty-six patients were included in this study. The changes in SMT were evaluated using cone-beam computed tomography images produced at four time points: before extraction (T0), before surgery (T1), immediately after surgery (T2), and after prosthesis delivery (T3), and statistical differences between time points were analyzed. The changes in SMT and augmented bone height (ABH) regarding the reason of extraction, smoking, ostial patency, and the presence of postoperative sinusitis were also evaluated.

RESULTS

Over time points, SMT gradually decreased (T0: 19.44 ± 9.22 mm, T1: 15.10 ± 8.89 mm, T2: 8.42 ± 6.01 mm, and T3: 4.16 ± 4.91 mm) (p < .05). Five out of 6 patients with ostial obstruction at T1 presented ostial patency at T3. Two patients developed postoperative sinusitis but recovered with medication. Ostial patency at T1, SMT at T1, and reason of extraction did not statistically significantly influence SMT at T3. SMT at T1 had no statistically significant impact on ABH change between T2 and T3.

CONCLUSION

Sinus mucosal thickness was gradually reduced by extraction of compromised teeth and drainage during lateral sinus augmentation. The drainage contributed more to the reduction in SMT.

Intraoperative complications and early implant failure after transcrestal sinus floor elevation with residual bone height ≤5 mm: A retrospective multicenter study

OBJECTIVE

Clinical indications for maxillary sinus floor elevation with transcrestal techniques have increased in recent years even in sites with minimal residual bone height (RBH). Nevertheless, limited information is currently available on incidence of intraoperative complications and early implant failure in these cases.

MATERIAL AND METHODS

This retrospective multicenter study was performed on anonymized clinical and radiographic records of patients who underwent transcrestal sinus floor elevation in seven clinical centers. Influence of different factors related to patient, sinus anatomy and surgical technique on the incidence of intraoperative complications and early implant failure rate after transcrestal sinus lift were investigated.

RESULTS

A total of 430 patients treated with transcrestal sinus floor elevation for single implant insertion in sites with RBH ≤5 mm were included in the final analysis. After one year of loading, 418 implants out of 430 were satisfactorily in function. Early implant failure was recorded in 12 cases (2.8%), resulting significantly associated with the presence of large sinus cavities and with the occurrence of membrane perforation. The following adverse events were recorded: membrane perforation (7.2%), acute sinusitis (0.9%), implant displacement into the sinus cavity (0.7%), oro-antral fistula (0.2%) and benign paroxysmal positional vertigo (0.5% of osteotome cases). A strong direct correlation between sinus membrane perforation and bucco-palatal sinus width (p=0.000) was demonstrated.

CONCLUSIONS

Early implant failure after transcrestal sinus elevation showed significant direct correlation with bucco-palatal maxillary sinus width and the presence of membrane perforation. Sinus membrane perforation was strongly associated with bucco-palatal sinus width (extremely low perforation rate in narrow and much higher incidence in wide sinuses).

Effect of Schneiderian Membrane Thickening on the Maxillary Sinus Augmentation and Implantation Outcomes: A Systematic Review

Background

Schneiderian membrane thickness may influence the final clinical outcome of sinus augmentation and dental implantation. Mucosal thickening has been regarded as a contributing factor for post-treatment complications. This study aimed to systematically review the available literature on the association between mucosal thickening and potential complications related to sinus augmentation and implant placement.

Methods

An electronic search was carried out in MEDLINE, Embase, and Web of Science by two independent reviewers. It was complemented by manual search of the reference lists of all relevant studies. The studies reporting on sinus augmentation and dental implantation in cases with preoperative mucosal thickening were considered eligible for this study.

Results

The initial search yielded 1032 articles. Five hundred and sixty-four records were screened by title and abstract, and 57 studies succeeded the inclusion criteria for full-text evaluation. Finally, 10 records remained for data extraction. The included studies assessed sinus augmentation and implantation procedures in 765 patients, 324 (42.3%) of them showed mucosal thickening. Increased membrane thickness did not significantly elevate the frequency of sinus augmentation complications. In addition, the overall implant survival rate was 99.03%.

Conclusions

Within the limitations of the present study, the presence of mucosal thickening might not be a risk factor for sinus augmentation and implant survival rate.

Influence of maxillary antrolith on the clinical outcome of implants placed simultaneously with osteotome sinus floor elevation: A retrospective radiographic study

BACKGROUND

Large antroliths and those located adjacent to the sinus floor can affect clinical interventions and increase the difficulty of implant placement performed simultaneously with osteotome sinus floor elevation surgery.

PURPOSE

This retrospective study investigated the clinical outcomes of implants placed simultaneously with osteotome sinus floor elevation subjacent to maxillary antroliths.

MATERIAL AND METHODS

Twenty implants inserted subjacent to or intruding into the antrolith after sinus floor elevation were evaluated in 18 patients. Cone-beam computed tomography (CBCT) was used to measure antrolith size and membrane thickness at sites of osteotome sinus floor elevation. Periapical radiographs were used to assess the height of grafted bone. Generalized estimating equation (GEE) analysis was performed to correlate the occurrence of antroliths with patient background characteristics and dental outcomes, based on a sample population of 239, among whom 33 presented antroliths.

RESULTS

The 20 implants remained clinically stable over a mean follow-up period of 42.4 months. The mean thickness of the sinus membrane at osteotome sites was 5.4 ± 3.3 mm. None of the cases presented sinus membrane perforation or sinus symptoms following osteotome intervention. The mean gain in the height of grafted sinus bone was 4.0 ± 1.4 mm at the last follow-up. The occurrence of antroliths was higher among females and the elderly (>49 years old). The multivariable GEE analysis showed that the adjusted odds ratio for the occurrence of antroliths with root canal fillings was significantly lower than those without root canal fillings (odds ratio = 0.33; 95% confidence interval = 0.11-0.96).

CONCLUSION

Our findings indicate that osteotome sinus floor elevation is a surgical procedure with a risk <17%. Thorough planning based on CBCT and careful management during surgery can eliminate the negative effects of antroliths on implant performance.

A modified transalveolar sinus floor elevation approach with a bilaterally enlarged osteotomy

Sinus floor elevation is the most commonly used method for vertical bone augmentation in the maxillary posterior area. This clinical report describes a modified transalveolar approach to elevate the sinus floor when placing implants on a severely resorbed maxillary posterior ridge with a buccal-palatal distance of more than 8.0 mm. In this approach, the osteotomy prepared on the crestal is bilaterally enlarged to 8.0-10.0 mm. The enlarged osteotomies can provide better access for practitioners, so that instruments can touch directly to the sinus floor and the Schneiderian membrane can be elevated with a reduced risk of perforation.

The Effectiveness of L-PRF in the Treatment of Schneiderian Membrane Large Perforations: Long-Term Follow-Up of a Case Series

The perforation of the Schneiderian membrane (SM) is a common surgical complication during the sinus floor augmentation (SFA) procedure. Different approaches have been proposed to completely closer the SM perforation and to avoid graft contamination or migration and postoperative sinus infection. In this context, the leukocyte and platelet-rich fibrin (L-PRF) membranes have been proposed for SM perforation treatment because of their natural adhesive property and resistance. Thus, this case series aims to evaluate the effectiveness of L-PRF in the treatment of SM large perforations during SFA. A total of 9 SM perforations were treated in this case series. The L-PRF membranes were interposed on the perforated SM until the rupture could not be visualized. The maxillary sinus cavities were filled with deproteinized bovine mineral bone (Bio-oss, Geistlich, Switzerland), and a collagen membrane was positioned to cover the lateral access window. After 8 months, 13 implants were placed, achieving satisfactory primary stability. The osseointegration of all implants and absence of infection signs/mucus in the maxillary sinus were observed in cone beam computed tomography or panoramic radiography qualitative analysis after 3-5 years of follow-up. It can be concluded that the use of L-PRF can be considered a viable alternative for the repair of large SM perforations.

Measurement of hydraulic pressure on the sinus membrane for safer control during transcrestal sinus lifting

The aim of this study was to determine the hydraulic pressures necessary to separate and lift the sinus membrane from the sinus floor in order to ensure a more controlled and safer hydraulic transcrestal sinus lifting surgery and prevent sinus membrane perforation. A flow-regulating hydrodynamic device with a pressure sensor was used in nine patients. The hydraulic pressure was found to increase steadily up to a mean peak of 25.0±13.0kPa, which is comparable to the medium suction power of ordinary vacuum cleaners. Subsequently, there was a short plateau followed by a sharp decrease in the hydraulic pressure.

Anatomical characteristics of maxillary sinus antroliths and their influence on sinus membrane thickness: a retrospective cone beam computed tomography analysis

The purpose of this study was to assess the anatomy of antroliths and its influence on the thickness of the maxillary sinus membrane. Cone beam computed tomography (CBCT) was performed on 239 patients (478 sinuses). The prevalence of antroliths per sinus was 8.4%. Regarding their distribution, antroliths were predominantly unilateral (82.5%), single (67.5%), and in a dentate area (60.0%). The antroliths were mainly located in the molar region (95.0%) and in the sinus floor (77.5%). The measured dimensions of the antroliths were as follows: length 5.6±4.4mm, width 4.1±2.9mm, height 3.5±2.1mm. The relationships between the antroliths and the sinus membrane (type 1, 34.1%; type 2, 52.3%; type 3, 13.6%) indicated that sinus membranes tended to encircle antroliths, which resulted in a gradual increase in membrane thickness. The sinus membrane was found to be significantly thicker in the presence of antrolith(s) (P<0.001). Antroliths which are sufficiently large or are located adjacent to the sinus floor or lateral wall increase the risk of sinus membrane perforation during sinus augmentation procedures. Therefore, a thorough CBCT evaluation is needed to minimize the risk of complications prior to sinus augmentation procedures.

Histological and Histomorphometric Evaluation of Applying a Bioactive Advanced Platelet-Rich Fibrin to a Perforated Schneiderian Membrane in a Maxillary Sinus Elevation Model

Background

Schneiderian membrane (SM) perforation is a major complication of maxillary sinus elevation with simultaneous bone grafting, yet under this scenario there is no standard biomaterial that maximizes favorable tissue healing and osteogenic effects.

Purpose

To compare the effect of advanced platelet-rich fibrin (A-PRF) and collagen membrane (CM) on a perforated SM with simultaneous bone grafting in a maxillary sinus elevation model.

Materials and Methods

After perforation of the SM was established, 24 animals were randomly divided into two groups: (i) group CM: CM and deproteinized bovine bone mineral (DBBM) (n = 12), (ii) group A-PRF: A-PRF and DBBM (n = 12). Radiographic and histological evaluations were performed at 1 and 4 weeks post-operation.

Results

At 1 week, an intact SM was found in group A-PRF. At each time point, the number of inflammatory cells at the perforated site was higher in group CM, and the area of new osteoid formation was significantly greater in group A-PRF (p < 0.0001). At 4 weeks, the osteogenic pattern was shown as from the periphery to the center of the sinus cavity in group A-PRF.

Conclusion

The higher elasticity, matching degradability, and plentiful growth factors of A-PRF resulted in a fully repaired SM, which later ensured the two osteogenic sources from the SM to generate significant new bone formation. Thus, A-PRF can be considered to be a useful bioactive tissue-healing biomaterial for SM perforation with simultaneous bone grafting.

Does sinus floor elevation in the presence of Schneiderian membrane pathology increase therisk of membrane perforation and implant failure rate?

Schneiderian membrane (SM) thickness >2mm is regarded to be a pathological mucosal change. The aim of the current study is to answer the question" Does presence of pathological changes in the SM increase the risk of sinus perforation during surgical sinus floor elevation (SFE)?" An electronic database (PubMed, Embase, Cochrane Library, and Chinese database) were systemically searched for the studies published until February 2020. Randomized and non-randomized studies that reported the incidence of SM perforation in patients with SM pathology (antral pseudocyst or mucosal thickening) during SFE. The outcome measures were the incidence of SM perforation and implant survival rate. The pooled odds ratio (OR) with 95% confidence intervals and the Fixed-effects model were calculated. P-value ≤ 0.05 was considered to be statistically significant. Eighteen studies with a total of 1542 patients and 1797 SFE were included. Statistically insignificant difference in the incidence of SM perforation was observed between the normal-appearing sinus and thickened sinus mucosa (Fixed; OR, 0.896; 95%CI, 0.504 - 1.59; P =0.707, I 2 =32%). The rate of SM perforation in the normal sinus, mucosal thickening, and antral pseudocysts was 14%, 6%, and 6% respectively. The Implant survival rate was 98% in the normal sinus, and 100% in antral pseudocyst and mucosal thickening. SM thickening or antral pseudocyst did not increase the risk of membrane perforation and implant failure rates. Future RCTs are needed to evaluate the risk of the presence of pathological changes in the SM on the failure of the bone augmentation and dental implant.

Endoscopically monitored maxillary sinus augmentation - The chairside approach (Rationale and protocol)

Sinus augmentation procedures have been reported since the time of Boyne, with variable techniques and outcomes. Sinus membrane perforations may or may not be detected at the intra-operative stage, thereby compromising the outcome. The aim of this study is to evaluate the usefulness and feasibility of an endoscope used intraorally during manipulation of the schnederian membrane. This would help confirm sinus health and integrity of the membrane during and after the augmentation.

The effect of residual bone height and membrane thickness on sinus membrane perforation in crestal sinus grafting: A prospective clinical study

This study sought to determine the rate of sinus membrane perforation in patients undergoing crestal sinus grafting, as well as the effect of Schneiderian membrane thickness and residual bone height (RBH) on membrane perforation, using cone beam computed tomography. The study included 25 patients undergoing 44 crestal sinus grafting procedures. The sites for crestal sinus grafting were divided into a control group (RBH≥5mm) and a test group (RBH<5mm). All sinus grafting procedures were also categorised based on membrane thickness: group A (<1mm), group B (1-2mm), and group C (≥2mm). The rate of membrane perforation was 18.2%. The median RBH measurement was 5.59mm. No statistically significant difference in membrane perforation rate was found between the test and control groups (P=0.262). The median thickness of the Schneiderian membrane was 1.35mm. There was no statistically significant difference in membrane perforation among the three membrane thickness groups (P=0.431). No significant correlation between RBH and membrane perforation was observed, although clinical observation indicated that there was a tendency for an increased membrane perforation rate in the presence of a RBH<5mm. The perforation rate was found to be at its highest when the membrane was thinner than 1mm.

CBCT Study of Morphologic Variations of Maxillary Sinus Septa in Relevance to Sinus Augmentation Procedures

Background:

Augmentation of the maxillary sinus increases the lost height of ridge in the posterior maxilla. Bony convolutions from the floor of the sinus called septa may be encountered during the procedure and significantly impact the outcome of the procedure.

Materials and Methods:

For this retrospective study, 120 cone-beam computed tomography (CBCT) scans were collected from the archives of the department of oral radiology in the time period between January 2016 and August 2018. Planmeca Romexis^® software version 3.2.7 was used to check for the incidence, and then among the septa, plane of orientation, location with respect to the wall of the sinus, and in terms of relation to tooth were examined. The average height and average width of all the septa were measured using a measuring tool in the software.

Results:

Thirty-five of the total 88 patients showed septa in 40 sinuses, in which 36 sinuses showed one septum and 4 sinuses showed 2 septa. Forty-one septa were located on the floor of the sinus in the frontal orientation and 3 septa were located on the lateral wall of the sinus in the axial orientation. The mean height and mean width of the 41 septa on the floor of the sinus were 5.72 mm and 3.47 mm, respectively. The mean height of septa found on the lateral wall of the sinus was 5.59 mm.

Conclusion:

Septa had a higher tendency to be in bucco-palatal direction and on the floor of the sinus and frequent occurrence in the region of molars. A thorough prediagnostic evaluation using CBCT is necessary prior to sinus augmentation procedures.

Managing Antral Wall Discontinuities in Sinus Elevation Surgery

INTRODUCTION

Schneiderian membrane perforation (SMP), which is usually readily manageable, is the most common intraoperative complication of sinus elevation surgery. Some evidence suggests that SMP is associated with increased risk for postoperative complications, including maxillary sinusitis. Antral wall discontinuity (AWD) is an acquired condition that may increase SMP likelihood and lead to larger, less-manageable perforations.

CASE PRESENTATION

A generally healthy patient receiving sinus elevation surgery exhibited an AWD in the palatine process of the maxilla. The osseous defect was isolated intraoperatively, and the Schneiderian membrane was sharply dissected from the palatal connective tissue. Favorable augmentation of the maxillary sinus was noted on cone-beam computed tomography (CBCT) assessment at postoperative month 34.

CONCLUSIONS

AWD (fusion of the Schneiderian membrane with the periosteum of the maxilla) is a condition identifiable on preoperative CBCT images, which may increase the incidence and severity of SMP during sinus elevation procedures. Careful assessment for integrity of antral osseous walls before surgery is essential. Presence of AWD may obligate modifications to the surgical plan, or in some cases, contraindicate sinus elevation surgery.

Efficacy of Dental Implants Placements between Lateral and Crestal Sinus Lift Techniques: A Split-Mouth Study

Background:

Bone atrophy and pneumatization of the maxillary sinus resulting from tooth loss, associated with low bone density in the region, do not usually allow adequate quantity and quality for the installation of osseointegrated implants.

Objective:

To evaluate the efficacy of crestal and lateral sinus lift techniques which are performed on same patients.

Materials and Methods:

Ten patients who required both crestal and lateral approaches in 20 sinus lifts were selected; 31 endosseous dental implants were placed into these patients, with a reported timeline for each approach. Assessment of the surgical procedures in all patients was done using a Visual Analog Scale (VAS). Clinical and radiographic parameters, including Pocket Probing Depth (PPD), distance between the implant shoulder and the mucosal margin (DIM) and distance between the implant shoulder and first visible bone-implant contact (DIB), were analyzed to compare implant survival for both approaches.

Results:

All implants were successfully osseointegrated. No significant differences were observed between lateral and crestal approaches in PPD, DIM and DIB (p-values = 0.0504, 0.7784 and 0.18170, respectively), and in the total VAS scores (p-value ≥ 0.05). Most of the patients preferred the crestal approach due to the delay in implant placements with the lateral approach.

Conclusion:

Evaluation of the sinus floor elevation is more precise when both techniques are performed on the same patient. Furthermore, although post-operative vertigo is a major concern with the crestal approach; patients preferred this approach over the lateral technique because it is less invasive and required less time for the procedure.

Preoperative Maxillary Sinus Imaging and the Outcome of Sinus Floor Augmentation and Dental Implants in Asymptomatic Patients

OBJECTIVES

Preoperative maxillary sinus imaging findings have been suggested to be associated with complications and outcomes of sinus lift and dental implant procedures; nonetheless the evidence is controversial. The aim of this study was to examine the association between preoperative maxillary sinus imaging findings and outcomes of sinus lift and dental implant procedures in asymptomatic patients.

METHODS

We included all patients who underwent maxillary sinus lift and dental implant procedures between 2014 and 2017. Maxillary sinus imaging findings were extracted from pre-procedural dental computed tomography scans, and outcomes of the procedures were assessed.

RESULTS

A total of 145 procedures were included. No sinonasal symptoms were reported preoperatively. In 46% of cases maxillary sinus imaging was abnormal. The most common imaging finding was peripheral mucosal thickening (38%). Sinus floor cyst/polyp was identified in 13% of the cases, of which 47% occupied more than 50% of the sinus volume. Partial or complete opacification of the maxillary sinus was documented in 3% of cases. The sinus ostium and ostiomeatal complex were obstructed in 7% and 1%, respectively. Mucosal perforation was documented in 22% of cases and was inversely related to mucosal thickening (P = 0.011). Other minor post-operative complications did not correlate with radiological findings. Post-surgical sinusitis was not observed in any of the patients regardless of pre-surgical imaging findings.

CONCLUSIONS

Incidental maxillary sinus imaging findings such as mucosal swelling, cysts or polyps, regardless of their severity or size, and maxillary ostial obstruction may not need to be addressed prior to sinus augmentation and dental implant procedures in asymptomatic patients. Patients with complete sinus opacification should be referred to an otolaryngologist prior to surgery. Further controlled trials, in larger cohorts, are needed to corroborate our findings.

Effect of staged crestal maxillary sinus augmentation: A case series

BACKGROUND

In sinus augmentation, when remaining bone height is ≤5 mm, a lateral window approach is often the preferred choice; nonetheless, patients prefer to have a less invasive approach such as crestal sinus augmentation (CSA). Prior case reports have described the use of various staged approaches of a CSA technique in cases of limited bone height. The aim of this report was to describe the results of a case series in which a two-stage CSA technique was used in patients with 4 to 6 mm of bone height.

METHODS

Nineteen subjects with 28 sinuses of initial vertical bone height of 4 to 6 mm were included in which a two-stage CSA technique was used in place of a lateral window approach. In the first surgery, 0.3 mL graft material was inserted into all sites. In the second surgery, 13 sites were filled with 0.2 mL graft material and remaining 15 sites were filled with 0.4 mL.

RESULTS

No damage was observed in the maxillary sinus floor membrane after first 0.2 mL filling; however, one case had Schneiderian membrane perforation after filling 0.4 mL. The average elevation height (EH) after first surgery was 5.81 ± 0.7 mm, 5.15 ± 0.91 mm before second surgery, 6.69 ± 0.89 mm with 0.2 mL filling (total 0.5 mL) and 8.11 ± 1.24 mm with 0.4 mL filling (total 0.7 mL). The thickness of maxillary sinus membrane before first surgery was 2.6 ± 2.59 mm; however, it has become 0.97 ± 1.59 mm before second surgery, with a decrease of 1.6 mm estimate.

CONCLUSION

This case series that assessed outcomes of staged crestal maxillary sinus augmentation was an effective approach to elevating 6 or 8 mm alveolar bone height without causing major membrane perforation. However, the two-stage approach was used in the limited residual bone height (4 to 6 mm) and required two separate surgical procedures.

Evaluation of the survival of implant placement simultaneously with sinus augmentation: relationship in maxillary sinus pathologies

OBJECTIVES

This retrospective study aimed to evaluate the effects of existing maxillary sinus pathologies on the survival rates of dental implants placed simultaneously with sinus augmentation.

METHODS

Cone-beam computed tomography images of 88 patients (34 females, 54 males), who underwent sinus augmentation, were retrospectively analyzed and the patients were divided into two groups: with (pathology group) and without pathology (control group). All maxillary sinus pathologies were recorded and categorized into mucosal thickening ( ≥ 3 mm), antral pseudocyst (polypoid mucosal thickening), and complete opacification. Implant survival rates were evaluated after a mean follow-up period of 28.2 ± 9.8 months based on the patient's records and control radiographs.

RESULTS

A total of 115 maxillary sinuses of 88 patients with 168 dental implants were included in the study. Maxillary sinus pathology was detected in 45 patients in the pathology group and 43 patients in the control group. In the pathology group, one implant was lost out of 82 implants during the 27.8 ± 9.5 months follow-up period, while in the control group, 5 implants were lost out of 86 implants during the 25.1 ± 10 months follow-up period. There was no statistically significant difference in the survival rates between the two groups.

CONCLUSIONS

The study concluded that the presence of pathology in the maxillary sinus before surgery does not affect the survival rates of dental implants placed simultaneously with sinus augmentation. The most common pathology noted included mucosal thickening (61.4%), which was detected in 35 patients.

Microscope and micro-camera assessment of Schneiderian membrane perforation via transcrestal sinus floor elevation: A randomized ex vivo study

OBJECTIVE

We sought to assess the effectiveness of using a microscope and non-invasive camera for assessing sinus membrane perforations during transcrestal sinus floor elevation (TSFE).

MATERIALS AND METHODS

Five fresh human cadaver heads corresponding to eight maxillary sinuses (six bilateral and two unilateral) underwent 4 TSFEs per sinus (a total of 32 single site elevations). Each elevation was randomly assigned to receive a three or six mm membrane elevation height (MEH). A microscope and micro-camera were used to assess the sinus membrane perforation. Afterwards, radiological and clinical membrane perforation assessments were performed. The statistical analysis results are expressed using the means, standard deviations, range values of the residual ridge height (RRH), residual ridge width (RRW), sinus membrane thickness (SMT) and incidence of perforation (IoP). Generalized linear methods were used to test for the correlation of RRH and MEH to the microscope and micro-camera perforation assessments and the correlation of microscope and micro-camera assessments with the post-operative CBCT and crestal liquid evaluation.

RESULTS

The cumulative percentage of IoP was 40.62%, (23.07% with 3 mm MEH, and 76.92% with 6 mm MEH, p < 0.05). The perforation assessed using either the microscope or micro-camera coincided with the post-operative CBCT and crestal liquid assessment in 87.55% sites. No significant correlation was found between the microscope or micro-camera assessments with RRH or MEH.

CONCLUSION

Application of a microscope and micro-camera during transcrestal sinus floor elevation may allow the detection of the integrity of the Schneiderian membrane with greater than 85% accuracy in this ex vivo model.

The clinical and radiographic outcomes of Schneiderian membrane perforation without repair in sinus elevation surgery

BACKGROUND

The aim of this comparative study was to evaluate the clinical outcome of nonrepair of the perforated maxillary sinus membrane compared to the nonperforated cases.

MATERIALS AND METHODS

A retrospective comparative study was performed by identifying all lateral window sinus augmentation procedures, which were done during a defined period. Demographic data, systemic diseases, and smoking habits of patients were recorded. Thickness of the Schneiderian membrane and the amount of residual bone before surgery were measured by cone-beam computed tomography (CBCT). In case of perforation, no attempt was made to repair the membrane. Alloplast was used for bone augmentation. The thickness of the Schneiderian membrane and gained bone height were recorded using CBCT at the time of prosthesis delivery.

RESULTS

Sixty-three patients with 65 sinuses were included in this retrospective study. The rate of sinus perforation was 39%. There was a significant association between the presence of sinus pathoses before surgery and the occurrence of Schneiderian membrane perforation (P = 0.03). The Schneiderian membrane was significantly thicker in patients with perforation compared to the patients without perforation (P < 0.001). There was no correlation between the size of the perforation and the thickness of the Schneiderian membrane. Most of the perforations (83%) occurred at the mesial and middle part of the lateral window. The Schneiderian membrane thickness was decreased significantly in both groups after the sinus elevation procedure (P < 0.05). The bone graft height was stable over the follow-up period in both groups (P > 0.05). There was no implant failure in any of the groups.

CONCLUSIONS

Nonrepair of the Schneiderian membrane perforation did not adversely affect the clinical and radiographical outcomes. There were higher intraoperative and postoperative complications in the nonrepair group.

Analysis of Forces Applied During Transalveolar Sinus Lift: A Preliminary Clinical Study

PURPOSE

To introduce a novel modality that enables the measurement of forces applied during a transalveolar sinus floor elevation (tSFE) and to investigate the influence of anatomical and surgical factors on the necessitated force in sinus membrane detachment.

MATERIAL AND METHODS

A new endosinus probe, innovated with a calibrated load cell, was used to test the forces needed to perforate ten maxillary sinuses in 5 human cadavers. The same probe was also used to detach the Schneiderian membrane from the bony floor of 21 human subjects undergoing tSFE.

RESULTS

The force needed to cause membrane perforation in the cadaver sample was on average 3.46 ± 1.04 N. The maximum force applied in vivo to a sinus membrane without perforation was 2.01 ± 0.67 N on average. Regression analysis showed that smoking (P < 0.001), as well as 3.0 mm osteotomy (P < 0.001), was significantly correlated to increased forces during membrane detachment.

CONCLUSIONS

The maximum force needed to detach the membrane was found to be, on average, lower than the membrane breaking load in cadavers. Furthermore, because of smoking and a 3.0-mm osteotomy diameter demonstrating a high association with increased forces during membrane detachment, they may be considered as risk factors of membrane perforation.

Schneiderian membrane perforation via transcrestal sinus floor elevation: A randomized ex vivo study with endoscopic validation

OBJECTIVE

To endoscopically determine the incidence of Schneiderian membrane perforation during transcrestal maxillary sinus floor elevation (SFE), in relation to the bone preparation technique, amount of bone graft, membrane elevation height and different surgical steps.

MATERIALS AND METHODS

Seven cadaver heads corresponding to 12 maxillary sinuses were used to perform three SFE via transcrestal approach per sinus (36 elevations). Each sinus was randomly assigned to either the Sinus Crestal Approach (SCA) drill kit technique (experimental group) or the conventional osteotome technique (control group). During all phases of the surgery, the integrity of the sinus membrane was monitored through endoscopic examination.

RESULTS

A significant difference was found in the incidence of perforation (p = 0.007) and vertical elevation height (p < 0.001) between the study groups, favoring the experimental group. A safety elevation threshold of 5 mm without bone graft and implant placement was estimated. A significant correlation was observed between the residual ridge height and the incidence of perforation (p < 0.001; OR = 0.51).

CONCLUSION

The SCA drill kit may demonstrate superior osteotomy preparation and membrane elevation capabilities to the osteotome technique, and significantly when a 6-mm SFE is indicated. Residual ridge height and vertical elevation height are risk determinant factors.

Successful Use of Leukocyte Platelet-Rich Fibrin in the Healing of Sinus Membrane Perforation: A Case Report

PURPOSE

The aim of this case report was to demonstrate the repair of a large sinus membrane perforation related to a sinus floor augmentation procedure, using leukocyte platelet-rich fibrin (L-PRF), for subsequent rehabilitation of a partially edentulous patient.

MATERIALS AND METHODS

The patient presented the absence of teeth numbers 18, 17, and 16, associated with insufficient bone height because of the maxillary sinus pneumatization. A maxillary inlay bone graft was proposed, however, during the sinus floor augmentation procedure, a large portion of the sinus membrane was ruptured. To avoid interruption of the surgical procedure, membrane mending was proposed using L-PRF and collagen membranes.

RESULTS

After 8 months, 2 external hexagon connection dental implants were placed in the 16 and 17 teeth regions, and a screw-retained implant-supported prosthesis was installed.

CONCLUSION

The use of L-PRF associated with collagen membrane was efficient for the sealing of the sinus membrane perforation and enabled bone formation for subsequent implant installation.

Crestal Sinus Augmentation in the Presence of Severe Sinus Mucosal Thickening: A Report of 3 Cases

PURPOSE

In the presence of severe sinus mucosal thickening, the ostium can be blocked when the sinus membrane is lifted, causing drainage disturbances and sinusitis. Here, we present 3 cases in which maxillary sinus floor elevation was performed using a crestal approach in the presence of severe sinus mucosal thickening (>10 mm).

MATERIALS AND METHODS

The effects of maxillary sinus floor elevation using the crestal approach technique on sinus mucosal thickening and bone formation in the sinus were evaluated using cone beam computed tomography.

RESULTS

None of the patients exhibited an increase in sinus membrane thickness. No complications were encountered during the follow-up periods, and bone formation was observed around the implants at the sinus floor. All implants were functioning successfully.

CONCLUSIONS

Maxillary sinus floor elevation using the crestal approach technique in the presence of severe sinus mucosal thickening allows for minimally invasive sinus grafting and simultaneous implant placement and does not increase sinus membrane thickness.

Thickness of the Schneiderian membrane and its correlation with anatomical structures and demographic parameters using CBCT tomography: a retrospective study

Background

The aims of the present study were to determine the thickness of the Schneiderian membrane and identify the width of the maxillary sinus, which is indicated by the buccal and lingual walls of the sinus angle between. Furthermore, to investigate the possibility of a correlation between the aforementioned structures and also other anatomical and demographic parameters using CBCTs for dental implant surgical planning.

Methods

The study included CBCT images of 76 consecutive patients with field-of-view 15 × 12 or 12 × 8cm. Reformatted cross-sectional CBCT slices were analyzed with regard to the thickness of the Schneiderian membrane designated by the medial and the lateral walls of the sinus, in three different standardized points of reference. Age, gender, and position of the measurement were evaluated as factors that could influence the dimensions of the anatomical structures, using univariate and multivariate random effects regression model.

Results

The mean thickness of the Schneiderian membrane was 1.60 ± 1.20 mm. The average thickness revealed now differentiation by age (p = 0.878), whereas gender seemed to influence the mean thickness (p = 0.010). Also, the thickness of the Schneiderian membrane increased from medial to distal (p = 0.060). The mean value of the angle designated by buccal and lingual walls of the sinus was 73.41 ± 6.89 °. The angle measurements revealed no correlation with age, but a tendency towards lower mean angles in females (2.5 ° on average, p = 0.097). According to the anatomical position of the measurement, a differentiation was also detected. No correlation between thickness of the Schneiderian membrane and the angle of the walls of the sinus was concluded (p = 0.662).

Conclusions

This study demonstrated that the thickness of the Schneiderian membrane and the width of the maxillary sinus can only be affected by gender and anatomical position, but not by the age of the patient.

Nonlinear Biomechanical Characteristics of the Schneiderian Membrane: Experimental Study and Numerical Modeling

Objective

The aim of this study is to quantify the nonlinear mechanical behavior of the Schneiderian membrane.

Methods

Thirty cadaveric maxillary sinus membrane specimens were divided into the elongation testing group and the perforation testing group. Mechanical experimental measurements were taken via ex vivo experiments. Theoretical curves were compared with experimental findings to assess the effectiveness of the nonlinear mechanical properties. The FE model with nonlinear mechanical properties was used to simulate the detachment of the Schneiderian membrane under loading.

Results

The mean thickness of the membrane samples was 1.005 mm. The mean tensile strength obtained by testing was 6.81 N/mm². In membrane perforation testing, the mean tensile strength and the linear elastic modulus were significantly higher than those in membrane elongation testing (P < 0.05). The mean adhesion force between the Schneiderian membrane and the bone was 0.052 N/mm. By FE modeling, the squared correlation coefficients of theoretical stress-strain curves for the nonlinear and linear models were 0.99065 and 0.94656 compared with the experimental data.

Conclusions

The biomechanical properties of the Schneiderian membrane were implemented into the FE model, which was applied to simulate the mechanical responses of the Schneiderian membrane in sinus floor elevation.

Mechanical characteristics of the maxillary sinus Schneiderian membrane ex vivo

OBJECTIVES

It has been speculated that certain Schneiderian membrane thickness (SMT) might be more prone to perforation. This investigation was aimed at studying the mechanical characteristics of the Schneiderian membrane under one- and two-dimensional tests and their correlation to the histological SMT in human samples.

MATERIAL AND METHODS

Sixteen Schneiderian membranes were collected from 11 cadaver heads treated with Thiel's embalming method. The samples were processed and analyzed clinically and histologically. One-dimensional maximum elongation until perforation and two-dimensional resistance to ball penetration were performed after the biopsy. Data was analyzed by using the Wilcoxon rank test and the Spearman's rank correlation.

RESULTS

The histological SMT was 1.36 ± 0.42 mm, whereas the clinical thickness was 0.27 ± 0.21 mm, yielding statistical significance (p = 0.000). The resistance under ball penetration was 0.59 ± 0.43 N and the mean maximum elongation in the one-dimension test 11.19 ± 7.14 mm. Expressed in percentage, the mean stretch was 241.36 ± 227.97% (range 31.5 up to 947%). A weak positive correlation was found between the ball penetration test and the SMT (r = 0.10, p = 0.711), while a weak negative correlation was found between stretching test and the SMT (r = -0.021, p = 0.94).

CONCLUSIONS

Mechanical tests seem to indicate that SMT might not significantly predispose to Schneiderian membrane perforation. Hence, other anatomical and operator's factors should be considered of surpassing importance.

CLINICAL RELEVANCE

Thinner SM might be more prone to perforation when detaching it from the maxillary sinus antrum; however, a thick membrane is not prevented to tear, as their resistance under elastic forces is not higher than thinner ones.

The effect of demographic and disease variables on Schneiderian membrane thickness and appearance

OBJECTIVES

The purpose of this study was to evaluate the prevalence of sinus mucosal thickening (MT) and mucosal appearance (MA) in a patient population as detected with cone beam computed tomography (CBCT) and to determine the effects of various disease and demographic factors on MT and MA.

STUDY DESIGN

The retrospective study consisted of CBCT images of 1000 maxillary arches in 500 patients. The arches were divided into 3 groups (atrophic, partially atrophic, and nonatrophic) according to the type of the maxillary dental crest. The CBCT scans were assessed to detect the prevalence of maxillary sinus MT and MA. χ² analysis was used to determine the significance of association of periodontal bone loss (PBL), periapical (PA) status, alveolar crest type, age, and gender on sinus MT and MA.

RESULTS

MT was significantly associated with PBL (P = .004), PA status (P = .001), and gender (P < .01). MA was significantly associated with PBL (P = .038), PA status (P = .009), and gender (P < .020). There were no significant associations between age or crest type and either MT or MA.

CONCLUSIONS

Periodontal bone loss, PA lesions, and gender may have an association with MT of the maxillary sinus.

Histological evaluation of effectiveness of platelet-rich fibrin on healing of sinus membrane perforations: A preclinical animal study

The aim of this study was to evaluate the effectiveness of platelet-rich fibrin (PRF) in repairing of Schneiderian membrane perforations in rabbit maxillary sinus. A total of 42 female New Zealand rabbits were randomly divided into two groups. Symmetrical bony defects were created 1 cm in diameter and the sinus membranes were exposed. The Schneiderian membranes were elevated in both sinuses and each membrane was perforated with a 1 cm incision. No treatment was applied to the right perforations in both groups. Left-sided perforations were closed with collagen membrane in the first group and PRF membrane in the other group. Seven animals randomly selected from each group were sacrificed at weeks 1, 2 and 4 in order to be able to examine the amounts of lymphocytes, fibroblasts, veins, and collagen fibers in the area where the membranes were applied. Histological analyses showed that there were no statistically significant differences between the collagen membrane and the PRF membrane in the healing of sinus perforation area. PRF may be considered as an alternative application to collagen membrane in sinus membrane perforations.

Association of Inflammatory Status and Maxillary Sinus Schneiderian Membrane Thickness

OBJECTIVES

Certain Schneiderian membrane thicknesses (SMT) have shown to be more prone to tearing/perforation, and some pathologies might influence SMT. Henceforth, we aimed at studying the correlation of inflammatory status to SMT in human fresh cadaver heads.

MATERIAL AND METHODS

A total of 14 fresh cadaver heads including 27 Schneiderian membrane specimens were histologically collected. A 10-item inflammatory score was determined in the entire sample and also in the thinner and thicker areas of each sample. Data was analyzed by using the Wilcoxon rank test and the Spearman's rank correlation.

RESULTS

The mean measured SMT was 0.40 ± 0.12 mm and the median was 0.33 ± 0.12 mm. A weak positive correlation was found between the mean SMT and inflammation score without a statistical significance. (r = 0.385, p = 0.115). The Wilcoxon signed-rank test showed a statistical difference between the medians of the thinner and thicker areas (p < 0.001). The mean inflammation score of the thinner and thicker areas was 8.55 ± 2.57 and 11.61 ± 2.65, respectively. A moderate positive and statistically significant correlation was found between the inflammation score and the thickness of the thinner and thicker areas (r = 0.638, p = 0.000).

CONCLUSION

A moderate association between the Schneiderian membrane thickness and the level of inflammation exists.

Dental implants and grafting success remain high despite large variations in maxillary sinus mucosal thickening

Background

Although mucosal thickening is the most common radiographic finding observed regarding sinus pathology, the knowledge regarding its clinical significance on the outcomes of dental implants and grafting in the maxillary sinuses is still limited. We hypothesized that mucosal thickening would not alter the predictability for sinus floor augmentation and dental implant placement. The purpose of this retrospective study was to evaluate the outcomes of dental implant placement in sinus-augmented areas with preexisting sinus mucosal thickening.

Methods

This study involved the review of cone-beam computed tomographic (CBCT) scans taken on patients that underwent both maxillary sinus elevation with grafting and implant placement at the University of Michigan School of Dentistry from 2004 to 2014. Cases with documented radiographic and clinical follow-up were included. The data analyses revealed the following.

Results

A total of 29 CBCT scans met the inclusion criteria for evaluation, and 93.1% of them had maxillary sinus mucosal/tissue thickening. Specifically, 6.9% of cases exhibited no thickening, 6.9% had minimal thickening (1–2 mm), 20.7% of cases had moderate thickening (2–5 mm), and 65.5% had severe thickening (>5 mm). We propose these categorical measurements of tissue thickening as a new “mucosal thickening index.” The tissue thickening did not vary based on gender, age, or smoking status, nor did it relate to the underlying alveolar ridge height. However, patients with a history of periodontal diseases demonstrated a significant association with mucosal thickening (p = 0.0043). These data indicate that there is high implant and grafting success rate (100%) in the maxillary sinus despite large and varied physiologic sinus mucosal/tissue thickening.

Conclusions

Based on study findings, this research will help guide dental practitioners regarding cases that exhibit mucosal thickening. These data support the concept that physiologic mucosal thickening in varied ranges is not associated with implant or grafting failure in the maxillary sinus.

Influences of Schneiderian membrane conditions on the early outcomes of osteotome sinus floor elevation technique: a prospective cohort study in the healing period

OBJECTIVES

To radiographically investigate early outcomes of osteotome sinus floor elevation in the healing phase utilizing cone beam computed tomography and evaluate influences of Schneiderian membrane conditions.

MATERIAL AND METHODS

One hundred patients were consecutively recruited for osteotome sinus floor elevation (OSFE) surgery using deproteinized bone mineral. CBCT was taken prior to (T0), immediately post-operatively (T1), and after the healing period (T2). Linear and volumetric measurements of the elevated region from T0 to T1 were performed for evaluation on computed tomography (CT).

RESULTS

Osteotome sinus floor elevation were performed in 100 patients. One implant of each patient was selected. Mean residual bone height (RH) was 7.21 ± 1.12 mm. Mean sinus floor elevation height (SE) was 4.81 ± 0.75 mm. The mean endo-sinus bone gain after the healing period was 3.25 ± 0.83 mm. Pre-opterative CBCT scans revealed that 72 patients had a normal sinus membrane in osteotome region, 13 patients presented with flat thickened mucosa and 15 patients with antral pseudocysts. There is no significant difference in sinus mucosa elevation height, bone graft volume and new bone formation in group of Thickening membrane and Antral pseudocysts compared with normal.

CONCLUSIONS

The radiographical results show that OSFE is a safe and predictable surgical procedure in residual bone height of 7.21 ± 1.12 mm. Mild flat thickening (>2 and <5 mm) and antral pseudocysts in a small size without clinical symptoms may not be contraindications to OSFE surgery.

Sinus Floor Cortication: Classification and Prevalence

PURPOSE

To present a classification and assess the presence and degree of cortication of the sinus floor utilizing Computerized Tomography (CT) scan images.

MATERIALS AND METHODS

One hundred CT scans, of patient who required a sinus augmentation procedure (SAP), were evaluated and classified according to the Type of sinus floor cortication (SFC). Type 1: sinus floor showing similar or higher density than the surrounding cortical areas. Type 2: sinus floor showing less density than the surrounding cortical areas. Type 3: sinus floor showing no cortical bone. Type 4: sinus floor showing the fusion of sinus floor bone and native crestal bone.

RESULTS

The SFC were present in 31, 41, 18, and 10 cases in Type 1, 2, 3, and 4, respectively.

CONCLUSIONS

This classification based on the level of cortication of the sinus floor is clinically useful as a method of determining if the dental implant can be placed simultaneously or not with the SAP, or can be placed even without a SAP.

Accuracy of Schneiderian membrane thickness: a cone-beam computed tomography analysis with histological validation

OBJECTIVES

Cone-beam computed tomography (CBCT) has been used in the literature to evaluate Schneiderian membrane thickness (SMT), but its accuracy has never been validated. The primary aim of this study was to compare the SMT measured by CBCT to the gold standard histological assessment. The correlations between SMT and anatomical structures of the maxillary sinus and alveolar bone were also tested.

MATERIALS AND METHODS

Fourteen fresh cadaver heads were used for the study, and 28 sinus lift augmentation procedures were performed to obtain the membrane samples. Samples were fixed in formalin and stained with hematoxylin-eosine and Masson trichrome. Specimens were measured by optic microscope at three points, and a mean was obtained. Anatomical landmarks were used to accurately position the CBCT slice, so the SMT could be measured in predetermined locations. Wilcoxon signed-rank test was used to compare values of histological and CBCT measurements, and Spearman's correlation coefficient was calculated to examine the relationship between thickness and anatomical parameters.

RESULTS

A total of 597 histological measurements were performed, and the mean SMT thickness was 0.30 ± 0.17 mm. The mean CBCT membrane thickness was 0.79 ± 0.52 mm. A statistically significant difference from histological and radiological readings was observed (P = 0.000). Interestingly, 87.77% histological measurements had membrane less than 0.5 mm in thickness compared to 26.66% in CBCT assessment.

CONCLUSIONS

Within the limitation of this study, the median histological Schneiderian membrane thickness was 0.30 mm. Cone-beam computed tomography assessment was 2.6 times higher than the histological examination.

Schneiderian Membrane Thickness and Clinical Implications for Sinus Augmentation: A Systematic Review and Meta-Regression Analyses

BACKGROUND

Schneiderian membrane thickness (SMT) has been regarded as a key factor for influencing membrane perforation, which may jeopardize the final clinical outcome of sinus augmentation. Hence, this systematic review aims at studying the mean SMT and further investigating patient-related factors that may affect SMT. As a secondary goal, the association between SMT and membrane perforation rate was studied.

METHODS

Three independent reviewers in several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register databases, conducted electronic and manual literature searches. This review was written and conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and MECIR (Methodological Expectations of Cochrane Intervention Reviews) guidelines. Quantitative assessment was performed for articles that met the inclusion criteria to investigate the mean SMT, its contributing factors, and the influence on membrane damage and surgical complications.

RESULTS

Thirty-one studies that reported maxillary SMT were considered for qualitative analysis. Nineteen were further meta-analyzed. Overall mean ± SE SMT was 1.17 ± 0.1 mm (95% confidence interval [CI] = 0.89 to 1.44). Although mean SMT for the three-dimensional radiography (3DR) group was 1.33 mm (95% CI = 1.06 to 1.60), for the histology group, it was 0.48 mm (95% CI = 0.12 to 1.1). Random-effects model showed that, although there is a trend for thicker SMT as determined using 3DR compared with histologic analysis, such difference did not reach statistical significance (P = 0.15). Also, regression analyses demonstrated that the variables periodontitis (P = 0.13) and smoking (P = 0.11) showed thicker SMT. Inconclusive data were obtained when correlating SMT and perforation rate, although it seems that thicker SMT might be more prone to perforation (P = 0.14).

CONCLUSIONS

SMT is, on average, 1 mm in patients seeking sinus augmentation. Three-dimensional technologies overestimate approximately 2.5 times SMT when compared with histologic analysis. Periodontitis and smoking may result in thickening of the sinus membrane. However, current data were inconclusive to link SMT to the rate of membrane damage.

Complications when augmenting the posterior maxilla

The maxillary posterior edentulous region presents a challenge when planning for restoring missing teeth with a dental implant. The available bone in such cases is often not dense and not adequate for the placement of a properly sized implant because of maxillary sinus pneumatization and alveolar bone loss. Maxillary sinus lift is a predictable procedure to provide adequate bone height for the purpose of implant placement. However, complications are encountered during or after the execution of the sinus lift procedure. In this article, the prevention and management of maxillary sinus complications are discussed.

The influence of sinus membrane thickness upon membrane perforation during lateral window sinus augmentation

OBJECTIVES

To investigate: (1) sinus membrane thickness in patients receiving lateral window sinus augmentation via cone-beam computed tomography (CBCT) and (2) the influence of Schneiderian membrane thickness upon membrane perforation during lateral window approach.

MATERIAL AND METHODS

A total of 73 subjects with 81 sinus lift procedures between years 2010 and 2013 were recruited consequently. Each patient selected had CBCT images in initial and immediately after surgery. The values and correlation between variables of membrane thickness, perforation rate, membrane morphology, residual bone height, and elevated bone height were evaluated.

RESULTS

The mean thickness of the Schneiderian membrane was 1.32 ± 0.87 mm. Perforation rate was lowest (7.14%) when membrane thickness was 1-1.5 mm. As membrane became thicker (≥2 mm) or thinner (<1 mm), the perforation rate increased abruptly. When examined the membrane thickness category, Class B (between ≥1 mm and <2 mm) had the lowest perforation rate. Statistically significant correlation was found between the perforation and the membrane thickness. The amount of the remaining bone height did not significantly correlate to the membrane thickness nor influence the membrane perforation.

CONCLUSIONS

This study demonstrated that membrane thickness was related to the sinus perforation during lateral window sinus augmentation. The perforation rate was lowest when the membrane thickness was 1-1.5 mm.

Graft Remodeling following Transcrestal Sinus Floor Elevation via the Gel-Pressure Technique (GPT) and Pasteous Nano-Crystalline Hydroxyapatite Bone Substitute

Bone grafting of the maxillary sinus is attempted to compensate for sinus pneumatization and permit reliable insertion of endosseous dental implants for prosthetic rehabilitation. The aim of the present clinical investigation was to study bone regeneration four months after transcrestal sinus floor elevation via the Gel-Pressure Technique (GPT) and application of pasteous nano-crystalline hydroxyapatite bone substitute. A total of 25 patients with deficient alveolar ridges in the posterior maxilla (mean residual bone height: 4.7 ± 1.8 mm) were subjected to 32 flapless transcrestal sinus floor augmentations and simultaneous insertion of 40 implants. Sinus membrane elevation height averaged 11.2 ± 2.7 mm and minimal vertical graft resorption of 0.1 mm was observed after four months. Radiographic bone density averaged 460 Hounsfield units in regions adjacent to the native jawbone (1 to 7 mm distance), while reduction of bone density by −7.2%, −11.3%, −14.8%, −19.6% and −22.7% was recorded in more apical regions of 8, 9, 10, 11, and ≥12 mm distance to the original sinus floor, respectively. The results suggest that graft remodeling is completed up to a distance of 7 mm within a healing period of four months after sinus augmentation using nano-crystalline hydroxyapatite bone substitute material.