Factors influencing long-term survival rates of implants placed simultaneously with lateral maxillary sinus floor augmentation: A 6- to 20-year retrospective study

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.

A Clinical Approach for the Removal of a Large Antral Pseudocyst with Simultaneous Maxillary Sinus Augmentation: A Case Series

For a large benign lesion within the maxillary sinus, such as an antral pseudocyst, maxillary sinus floor augmentation is more commonly performed using a two-stage approach. This involves first removing the lesion, and then, re-entry following several months of healing. In this case series, we described the "one-bony-window" approach, which is a technical surgical modification of the previous one-stage approach, for simultaneous cyst removal and maxillary sinus floor augmentation. Four patients with large maxillary antral pseudocysts were included. The "one-bony-window" approach involves the preparation of a large window opening of approximately 15 mm × 20 mm at the lateral wall. A mesiodistally extended intentional perforation was made in the upper part of the exposed membrane to enhance the access for instrumentation. The antral pseudocyst was removed in its entirety without being deformed to prevent rupture or leakage of the cystic contents. Subsequent detachment and elevation of the Schneiderian membrane at the sinus floor significantly reduced the perforation site, and bone grafting with implant placement was performed simultaneously. This alleviated the need to surgically repair the perforation. The lateral opening was either uncovered or repositioned using bony window lids. Healing abutments were connected after six months, and the final prosthesis was placed after two months. At the 1-year follow-up, the antral pseudocysts had resolved with no specific recurrence, and the stability of the augmented sinus was maintained with excellent implant survival. Within the limitations of our findings, the "one-bony-window" technique can be suggested for the simultaneous removal of large antral pseudocysts and maxillary sinus floor augmentation with favorable clinical outcomes.

Pilot study of fractal dimension analysis of osteogenesis for bone substitute materials of Bio-Oss in lateral sinus augmentation

BACKGROUND

Fractal dimension (FD) analysis has been proposed and validated in osseointegration-related research. The aim of this study was to evaluate the feasibility of FD analysis in the osteogenesis detection of bone substitute materials (BSMs) of Bio-Oss in maxillary lateral sinus augmentation.

METHODS

Patients who received lateral maxillary sinus augmentation and underwent grafting with BSMs (Bio-Oss) were included in the study. The cross sections of the BSMs under cone-beam computed tomography (CBCT) at mesial, distal, and sagittal directions were obtained immediately after the graft (T0) and 6 months later (T1), and the obtained images were cropped to include only the BSMs. The FD analysis was performed, and the FD value was obtained by the method of box-counting. Paired t-tests and analysis of variance (ANOVA) were used, and p-values <0.05 was considered statistically significant.

RESULTS

Twelve participants with 22 implants, which were inserted simultaneously after sinus augmentation, were included in this study. A total of 22 mesial, 22 distal, and 14 sagittal images were obtained after FD analysis. The mean FD value and standard deviation at T0 was 1.2860 ± 0.0896, while at T1, it was 1.2508±0.1023; thus, significant differences were detected (p = 0.022). However, the increasing or decreasing trend of FD value was not stable, and no significant difference was detected for FD values of mesial, distal, and sagittal images between T0 and T1. ANOVA indicated that no significant difference was detected among the FD values of mesial, distal, and sagittal images at any timepoint. Differences in FD values between the sexes were not significant either.

CONCLUSIONS

Since the FD analysis for the osteogenesis detection of BSMs in maxillary sinus augmentation indicated unstable trends of change, its feasibility is not reliable. The initially rough surface, self-degradation, and volume change of the BSMs during osteogenesis may be the reason for the variation in FD values.

Resorbable magnesium metal membrane for sinus lift procedures: a case series

BACKGROUND

The purpose of this case series was to demonstrate the use of a magnesium membrane for repairing the perforated membrane in both direct and indirect approaches, as well as its application in instances where there has been a tear of the Schneiderian membrane.

CASE PRESENTATION

The case series included four individual cases, each demonstrating the application of a magnesium membrane followed by bone augmentation using a mixture of xenograft and allograft material in the sinus cavity. In the first three cases, rupture of Schneiderian membrane occurred as a result of tooth extraction, positioning of the dental implant, or as a complication during the procedure. In the fourth case, Schneiderian membrane was perforated as a result of the need to aspirate a polyp in the maxillary sinus. In case one, 10 mm of newly formed bone is visible four months after graft placement. Other cases showed between 15 and 20 mm of newly formed alveolar bone. No residual magnesium membrane was seen on clinical inspection. The vertical and horizontal augmentations proved stable and the dental implants were placed in the previously grafted sites.

CONCLUSION

Within the limitations of this case series, postoperative clinical examination, and panoramic and CBCT images demonstrated that resorbable magnesium membrane is a viable material for sinus lift and Schneiderian membrane repair. The case series showed successful healing and formation of new alveolar bone with separation of the oral cavity and maxillary sinus in four patients.

Survival analysis of implants placed simultaneously with lateral sinus floor elevation in severely atrophic maxilla: A 3- to 12-year retrospective cohort study

OBJECTIVES

To retrospectively evaluate whether implants placed simultaneously with lateral sinus floor elevation (LSFE) in severely atrophic maxilla (residual bone height [RBH] ≤3 mm) could achieve long-term survival and comprehensively analyze the factors influencing their survival rates.

MATERIALS AND METHODS

A total of 123 patients receiving LSFE and simultaneous implant placement from 2010 to 2019 and their 123 implants in sites with RBH ≤3 mm were included in this study. Basic characteristics of patients and implants were collected from the medical record system and cone-beam computed tomography (CBCT) images. Kaplan-Meier survival curves were applied to estimate cumulative survival rates (CSRs) and Cox proportional hazards regression models were used to detect factors influencing implant survival.

RESULTS

The 6-year and 12-year CSR of implants placed in sites with RBH ≤3 mm were 95.7% (95% confidence interval [CI]: 92.1%-99.5%) and 76.6% (95% CI: 58.1%-100%), respectively. Eight patients presented late implant failure. Univariate and multivariate Cox regression analyses demonstrated that RBH ≤2 mm (hazard ratio [HR]: 20.63, p = 0.000) and smoking habit (HR: 6.055, p = 0.024) were significantly associated with long-term implant survival. Specifically, the 10-year CSR of implants in sites with RBH ≤2 mm (53.3%, 95% CI: 27.5%-100%) was dramatically lower than those in sites with RBH >2 mm (92.9%, 95% CI: 81.7%-100%, p = 0.000).

CONCLUSIONS

Implants placed simultaneously with LSFE in sites with RBH ≤3 mm can achieve long-term survival. However, caution is required especially for implantation in sites with RBH ≤2 mm. Besides, the smoking habit is also considered a risk factor jeopardizing long-term implant survival.

Five Steps for the Maintenance and Interception of Complications in Zygomatic Implants

Zygomatic implants are used for the rehabilitation of the upper jaw of patients with severe and moderate bone atrophy. Possible post-surgical complications include soft tissue dehiscence, sinusitis, and prosthodontic fractures, and maintaining an accurate control is crucial. Additionally, zygomatic implants have a unique peri-implant anatomy, making traditional periodontal parameters unsuitable. The present paper aims to provide guidelines for the maintenance and interception of complications in patients rehabilitated with these kinds of implants. The proposed protocol includes: 1. intra/extraoral and temporo-mandibular joint examination; 2. soft tissue and transmucosal path observation with magnifiers; 3. peri-implant health indices and digital stimulation of tissues; 4. examination of prosthodontic devices; and 5. photographic recording. These steps facilitate the comprehensive evaluation and monitoring of clinical conditions of zygomatic-supported rehabilitations, including dehiscence and occlusal wear during follow-up appointments.

Minimally invasive techniques for lateral maxillary sinus floor elevation: small lateral window and one-stage surgery-a 2-5-year retrospective study

This study aimed to introduce a minimally invasive technique for maxillary sinus floor elevation using the lateral approach (lSFE) and to determine the factors that influence the stability of the grafted area in the sinus cavity. Thirty patients (30 implants) treated with lSFE using minimally invasive techniques from 2015 to 2019 were included in the study. Five aspects of the implant (central, mesial, distal, buccal, and palatal bone heights [BHs]) were measured using cone-beam computed tomography (CBCT) before implant surgery, immediately after surgery (T0), 6 months after surgery (T1), and at the last follow-up visit (T2). Patients' characteristics were collected. A small bone window (height, (4.40 ± 0.74) mm; length, (6.26 ± 1.03) mm) was prepared. No implant failed during the follow-up period (3.67 ± 1.75) years. Three of the 30 implants exhibited perforations. Changes in BH of the five aspects of implants showed strong correlations with each other and BH decreased dramatically before second-stage surgery. Residual bone height (RBH) did not significantly influence BH changes, whereas smoking status and type of bone graft materials were the potentially influential factors. During the approximate three-year observation period, lSFE with a minimally invasive technique demonstrated high implant survival rate and limited bone reduction in grafted area. In conclusion, lSFE using minimally invasive techniques was a viable treatment option. Patients who were nonsmokers and whose sinus cavity was filled with deproteinized bovine bone mineral (DBBM) had significantly limited bone resorption in grafted area.

Effect of the implant apical exposure and coverage < or ≥ 2 mm bone graft on transcrestal sinus floor elevation: a 1- to 7-year retrospective cohort study

OBJECTIVES

This study aimed to analyze the effect of the apex coverage by the bone graft, including exposure and coverage less than or greater than 2 mm on implant survival rate and peri-implant bone and soft tissue remodeling.

MATERIALS AND METHODS

A total of 264 implants in 180 patients who had undergone transcrestal sinus floor elevation (TSFE) with simultaneous implant placement were included in this retrospective cohort study. Radiographic assessment was used to categorize the implants into three groups based on apical implant bone height (ABH): ≤ 0 mm, < 2 mm, or ≥ 2 mm. The implant survival rate, peri-implant marginal bone loss (MBL) during short-term (1-3 years) and mid- to long-term (4-7 years) follow-up, and clinical parameters were used to evaluate the effect of implant apex coverage after TSFE.

RESULTS

Group 1 had 56 implants (ABH ≤ 0 mm), group 2 had 123 implants (ABH > 0 mm, but < 2 mm), and group 3 had 85 implants (ABH ≥ 2 mm). There was no significant difference in the implant survival rate between groups 2 and 3 compared to group 1 (p = 0.646, p = 0.824, respectively). The MBL during short-term and mid- to long-term follow-up indicated that apex coverage could not be considered a risk factor. Furthermore, apex coverage did not have a significant effect on other clinical parameters.

CONCLUSIONS

Despite limitations, our study found that implant apex coverage by the bone graft, including exposure and coverage levels less than or greater than 2 mm, did not significantly affect implant survival, short-term or mid- to long-term MBL, or peri-implant soft tissue outcomes.

CLINICAL RELEVANCE

Based on 1- to 7-year data, the study suggests that implant apical exposure and coverage levels of less than or greater than 2 mm bone graft are both valid options for TSFE cases.

How to avoid intraoperative and postoperative complications in maxillary sinus elevation

Maxillary sinus floor elevation, via the lateral approach, is one of the most predictable bone augmentation procedures performed in implant dentistry. but both intra- and postoperative complications can occur, and some of them are severe. Our aim is as follows: To review the pertinent literature on the topic, especially assessing the risk factors related to complications. To give clinical recommendations to minimize intra- and postoperative complications with the ultimate scope of improving the standard of clinical care and patient safety.

Effects of different grafting materials on volumetric changes in the Schneiderian membrane following lateral maxillary sinus floor elevation: a preliminary study

OBJECTIVES

To investigate the potential influence of different grafting materials on maxillary sinus membrane dimensions and ostium patency following lateral sinus floor elevation (SFE) as assessed using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

A total of 40 sinuses in 40 patients were included. Twenty sinuses were referred for SFE with deproteinized bovine bone mineral (DBBM), and the remaining 20 sinuses were grafted with calcium phosphate (CP). CBCT was performed prior to and 3 to 4 days after surgery. The dimensions of the Schneiderian membrane volume and ostium patency were evaluated, and potential relationships between volumetric changes and any associated factors were analyzed.

RESULTS

The median increase in membrane-whole cavity volume ratios was 43.97% in the DBBM group and 67.58% in the CP group, demonstrating no statistically significant difference (p = 0.17). The rates of increased obstruction after SFE were 11.1% for the DBBM group versus 44.4% for the CP group (p = 0.03). The graft volume was found to be positively correlated with the postoperative membrane-whole cavity volume ratio (r = 0.79; p < 0.01) and the membrane-whole cavity volume ratio increase (r = 0.71; p < 0.01).

CONCLUSIONS

The two grafting materials seem to have a similar effect on transient volumetric changes in the sinus mucosa. However, the choice of grafting material should still be made with caution since sinuses grafted using DBBM exhibited less swelling and less ostium obstruction.

Association between smoking and Schneiderian membrane perforation during maxillary sinus floor augmentation: A systematic review and meta-analysis

OBJECTIVE

To estimate the association between smoking and Schneiderian membrane perforation in sinus floor augmentation.

MATERIALS AND METHODS

Searches were conducted in PubMed, Web of Science, Embase, and Cochrane Library. Data were extracted by two authors independently. The inclusion criteria were the (1) age of patients >18, (2) the number of participants >10, and (3) smoking and the patients of Schneiderian membrane perforation were accurately recorded. The risk of bias was assessed by the Newcastle-Ottawa scale (NOS). Statistics analyses were conducted using Reman5.4.1 and Stata (15.0). The association of Schneiderian membrane perforation with smoking habits during maxillary sinus floor elevation was expressed as odds ratios (ORs) with a 95% confidence interval (95% CIs). And the I2 statistic was used to estimate statistical heterogeneity. The funnel plot and Egger's tests were used to evaluate the reliability and stability of the results.

RESULTS

Of 1463 articles screened, nine studies were included in our systematic review, and eight were synthesized for meta-analysis. Eight were retrospective observational studies and one was a clinical trial, with a total of 1424 patients included. The nine studies were proved as high quality according to the NOS. There was no significant publication bias in the studies (p = 0.827). A random-effects model was used because of differences in the adopted methodologies (p = 0.39, I2  = 5%). During maxillary sinus augmentation, smoking and Schneiderian membrane perforation were associated (odds ratios, 1.58 [95% CI, 1.10-2.25]).

CONCLUSION

Smoking increased the risk of membrane perforation in maxillary sinus floor augmentation. Our evaluation was limited by the poor reporting of the number of cigarettes smoked per day (PROSPERO number was CRD42022306570).

Clinical and Radiological Evaluation of a Self-Condensing Bone Implant in One-Stage Sinus Augmentation: A 3-Year Follow-Up Retrospective Study

Stabilization of dental implants in the sinus region with a bone height below 4 mm gen-erally requires a two-stage sinus floor elevation surgery. To improve this aspect, the aim of this retrospective study was to demonstrate the feasibility of performing a one-stage maxillary sinus augmentation using an innovative self-condensing implant design, even in case of a bone height close to 2 mm. Clinical and radiological outcomes from 54 patients (26 females; 28 males; 69 total implants positioned) were analyzed 3 years post-surgery. The three-dimensional grafts change was evaluated by Cone-Beam Computed Tomography (CBCT) before surgery (T0), immediately after surgery (T1), and 1-year post-surgery (T2). The sinus floor levels measured at the medial (M-W), middle (MD-W), and lateral (L-W) walls reported: M-W of 1.9 ± 2.4 mm (T1) and 1.7 ± 2.6 mm (T2); MD-W of -0.1 ± 2.7 mm (T1) and 0.7 ± 2.4 mm (T2); L-W of 3.1 ± 3.0 mm (T1) and 3.1 ± 3.0 mm (T2); besides a bone crest height (C-F) of 4.6 ± 2.0 mm (T1) and 12.1 ± 1.4 mm (T2). Moreover, after 3 years only 1 implant was lost, and so an implant survival rate of 98.55% was recorded. In conclusion, these results suggest the efficacy of using this implant design for a one-stage sinus lift approach, not only in terms of increased implant survival rate and decreased marginal bone loss, but also for its potential applicability in case of reduced bone height.

Influence of the contact area of the sub-antral space with sinus bone and the Schneiderian membrane on osteogenesis in lateral window sinus elevation surgery: a prospective experiment

BACKGROUND

Osteogenesis of lateral window sinus elevation surgery is the key to placement of the subsequent implant, excessive collapse of the sub-antral space may adversely affect long-term stability of implants. At present, few studies focus on the influence of the contact area of the sub-antral space on osteogenesis. This study evaluated whether the change in the contact area of the sub-antral space with maxillary sinus bone and the Schneiderian membrane can affect osteogenesis.

METHODS

Cone beam computed tomography (CBCT) images were collected of patients requiring maxillary sinus floor elevation (residual bone height < 6 mm) for standard-length implant placement before surgery, after surgery, and at 6-month follow-up visits. The postoperative sub-antral space volume (V₁) and surface area (S₁), and the remaining volume after six months of healing (V₂) were measured. Then, the contact area of sub-antral space with maxillary sinus bone (S_bc) and the Schneiderian membrane (S_mc), the absorbed volume during healing (V_a), and the percentage of remaining volume (V₂%) and absorbed volume (V_a%) were calculated. The correlation between anatomical parameters was analyzed using multiple linear regression.

RESULTS

A total of 62 maxillary sinuses from 56 patients were augmented, of which 57 were considered for the final analysis (5 withdrew due to perforation). Multiple linear regression results demonstrated that S_bc was significantly positively correlated with V_a (β coefficient = 0.141, p < 0.01) without correlation between S_mc and V_a (β coefficient =  - 0.046, p = 0.470). There was a positive correlation between S_bc and V₂% (β coefficient = 2.269, p < 0.05).

CONCLUSIONS

This study confirmed that the size of the S_bc in lateral window sinus elevation surgery affected osteogenesis after six months of healing. Clinicians should assess the sinus contour type preoperatively, then consider whether it is necessary to expand the range of the Schneiderian membrane elevation to avoid excessive collapse of the sub-antral space.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR), ChiCTR2200057924. Registered 22 March 2022-Retrospectively registered.

Bone Graft Packing and Its Association with Bone Regeneration in Maxillary Sinus Floor Augmentations: Histomorphometric Analysis of Human Biopsies

Research in maxillary sinus floor augmentation (MSFA) focussed on the optimisation of microstructural parameters such as microporosity and particle size of bone substitute particles (BS). However, little is known about the impact of BS packing and the corresponding (void) interparticular space on bone regeneration. The aim of this study was to characterise the spatial distribution of BS and its association with BS integration 6 ± 1 months after MSFA. Histological thin-ground sections of 70 human sinus biopsies were histomorphometrically analysed: In serial zones of 100 µm proceeding from the sinus floor (SF) up to the apical end of the biopsy, we measured the distribution of BS particles within these zones in terms of volume (BSV/TV), number and size of BS particles, interparticle spacing (BS.Sp) and bone-to-BS contact. BS particles were not homogeneously distributed over the length of biopsies: The first 200 µm directly adjacent to the SF represented a zone poor in BS particles but with high osteogenic potential. Graft packing density increased from the SF towards the apical part of the AA. Integration of BS particles was inversely associated with the distance to the SF and the graft packing density. A high packing density through excessive compaction of BS particles should be avoided to optimise the macrostructural environment for bone regeneration.

Large Grafting Void Resembling a Surgical Ciliated Cyst following Maxillary Sinus Augmentation. Four Case Reports with Histological Observation

The cause and pathogenicity of grafting voids following lateral maxillary sinus augmentation (MSA) have not yet been elucidated. The first purpose of this case series is to introduce an unusually large grafting void that radiologically resembles a surgical ciliated cyst (SCC) at the sinus augmented site; the second is to observe the histological findings of these grafting voids. In four patients, MSA was performed using the lateral window technique. An unusually large grafting void appeared on cone-beam-computed tomography (CBCT) taken one week after surgery and except for one patient, there were no clinical symptoms. On CBCT taken six months after surgery, the grafting voids were slightly smaller in size but showed radiographic findings similar to those of SCC. During uncovering, grafting voids were removed through the lateral window site. Histologically, the grafting void was empty or filled with dense connective tissue, and no ciliated columnar epithelium or inflammatory cells were observed. Within the limitations of this case series, the large grafting voids generated after MSA was not converted to SCCs. Rather, they remained scar tissue, which could infringe the sinus bone graft and affect the apical bone support of the implant.

Maxillary sinus floor augmentation comparing removing versus retaining antral pseudocyst: A retrospective cohort study

OBJECTIVES

To retrospectively compare multilevel volumetric changes in both hard and soft tissues between antral pseudocyst (AP) removal and retainment before maxillary sinus floor augmentation (MSFA) and immediate implant placement.

MATERIAL AND METHODS

Twenty-six patients with thirty-eight implants placed from 2016 to 2021 were included and divided according to a cohort design as follows: 13 removing the cyst (RC group) and 13 "leaving alone" the cyst (LC group). 3D radiographic parameters (primary outcome), 2D parameters and clinical records (secondary outcome) involving both hard and soft tissues were evaluated for 4 periods (T1: immediate postoperative, T2: 6-month, T3: 12-month, and T4: 2- to 5- year follow-up). Possible confounding factors, including sinus anatomical features and implant distribution, were also analyzed to eliminate their disturbance.

RESULTS

The 3D volumetric change rate of bone grafts in the RC group (-9.32 ± 10.01%) from T2 to T3 was significantly lower than that in the LC group (-19.8 ± 10.59%) (p < .05). The change rate of apical bone height (ABH), endo-sinus bone gain (ESBG) and other 2D parameters were not significantly different between the two groups. 5.3% implants in RC group and 9.1% implants failed during follow-ups. 0% postoperative complications were observed in RC group. The Schneiderian membrane of RC group was significantly thinner than that of LC group at two measuring points in sinus.

CONCLUSION

The present study demonstrated that compared to AP retainment, AP removal before MSFA and immediate implant placement can obtain higher bone graft volumetric stability and favorable prognosis. The study protocol was approved by the Medical Ethics Committee of the Affiliated Hospital of Stomatology, School of medicine, Zhejiang University, China (Acceptance number: 2021-117(R)).

Clinical and radiographic outcomes of dental implant after maxillary sinus floor augmentation with rhBMP-2/hydroxyapatite compared to deproteinized bovine bone

Objectives

This study aimed to evaluate the clinical and radiographic outcomes of early implant placement and functional loading in maxillary sinus floor augmentation (MSFA) using recombinant human bone morphogenetic protein 2/hydroxyapatite (rhBMP-2/HA) and to compare these outcomes with those of the conventional protocol in MSFA using deproteinized bovine bone (DBB).

Materials and methods

The rhBMP-2/HA and DBB groups consisted of 14 and 13 patients who underwent MSFA with BMP and DBB, respectively. After placement of 22 implants and 21 implants in the rhBMP-2/HA and DBB groups, respectively, abutment connections were performed 3 months after implant placement for the rhBMP-2/HA group and 6 months after implant placement for the DBB group. Changes in grafted sinus height (GSH), marginal bone loss (MBL), and implant stability were evaluated up to one year after functional loading.

Results

Survival rates for the rhBMP-2/HA and DBB groups after one year of functional loading were 90.9% and 90.5%, respectively. Both groups exhibited no significant time-course changes in GSH until one year of functional loading (rhBMP-2/HA, p = 0.124; DBB, p = 0.075). Although significant MBL occurred after one year of functional loading for both groups (rhBMP-2/HA, p < 0.001; DBB, p < 0.001), there were no significant differences in time-course changes in MBL between the two groups (p = 0.450). The mean implant stability quotient values in the rhBMP-2/HA and DBB groups were 75.3 and 75.4 after one year of functional loading, respectively, and there were no significant differences between the two groups (p = 0.557).

Conclusions

MSFA using rhBMP-2/HA allowed implant rehabilitation with early implant placement and functional loading and led to a comparable survival rate and implant stability after 1 year of functional loading with acceptable MBL and stable maintenance of GSH compared to the MSFA using DBB with 6 months of healing after implant placement.

Repositioning of the bone window in lateral sinus floor elevation with simultaneous implant placement: A retrospective radiographic study

OBJECTIVES

To retrospectively evaluate whether repositioning the bone window leads to a better outcome of three-dimensional sinus augmentation in lateral sinus floor elevation (LSFE) with simultaneous implant placement.

METHODS

34 patients with a total of 40 implants (14: test group, 26: control group) receiving LSFE with simultaneous implant placement were included in this retrospective research. CBCT images were taken before surgery, immediately and 6 months after surgery. The two-dimensional augmentation parameters, including apical bone height (ABH), endo-sinus bone gain (ESBG), and palatal/buccal bone height (PBH/BBH), and three-dimensional parameters, including augmentation volume (AV) and palatal/buccal augmentation volume (PAV/BAV), were measured. The lateral defect length (LDL) and lateral window length (LWL) were also measured to evaluate the lateral antrostomy recovery.

RESULTS

At the 6-month follow-up, the reduction rates at ABH, ESBG, and BBH of the test group (ABH: 10.41% ± 30.30%, ESBG: 2.55% ± 8.91%, BBH: 2.50% ± 8.65%) were significantly lower than those of the control group (ABH: 25.10% ± 22.02%, ESBG: 11.47% ± 9.79%, BBH: 7.10% ± 5.37%; p < .05). In addition, the test group showed better three-dimensional augmentation stability on the buccal side (BAV reduction: 15.51% ± 10.86% vs. 27.15% ± 12.61%; p < .05). Moreover, the LDL/LWL ratio of the test group was significantly lower than that of the control group (p < .05).

CONCLUSION

Within the limitations of this study, repositioning of the bone window in LSFE with simultaneous implant placement could contribute to endo-sinus augmentation stability on the buccal side at the 6-month follow-up. Moreover, it would also facilitate recovery of the lateral antrostomy defect.

Tomographic Imaging of Mucociliary Clearance Following Maxillary Sinus Augmentation: A Case Series

Mucociliary clearance (MCC) allows ventilation of graft particles that are displaced through a perforated Schneiderian membrane during maxillary sinus augmentation (MSA). However, it is very rarely confirmed by cone-beam computed tomographic (CBCT) images. It is not yet known how long the dislodged bone graft particles remain in the maxillary sinus or how quickly they are ventilated after MSA. The purpose of these case reports is to introduce tomographic imaging of ventilation of bone graft particles displaced through a perforated Schneiderian membrane after MSA. Four patients, who needed implant placement in the posterior maxilla, received MSA, during which the Schneiderian membrane was perforated but was not repaired. Therefore, some bone graft particles were dislocated into the sinus cavity. The sizes of the perforated membranes were measured and recorded. CBCT scans were taken at multiple time points after the surgery to visualize and trace the ejected material. In addition, the time from when the bone graft substitute was delivered to the sinus until the CBCT scans were taken was recorded. The expelled bone graft particles migrated to the ostium along the sinus wall immediately after MSA on CBCT images taken immediately after the surgery. No displaced graft particles were observed in the maxillary sinus on CBCT scans after 1 week. The CBCT scans at 6 months showed no unusual radiographic images. Within the limitations of the case reports, tomographic imaging revealed an MCC system that allows displaced graft particles to be ventilated into the ostium very early during MSA healing and not stagnate in the maxillary sinus.

Histomorphometric evaluation of different graft associations for maxillary sinus elevation in wide antral cavities: a randomized controlled clinical trial

OBJECTIVES

Pneumatization of the maxillary sinus can make it difficult, if not impossible, to install osseointegrated implants, and undertake their eventual functional rehabilitation, which may ultimately require regenerative techniques to achieve. This randomized controlled study proposed conducting a histological evaluation of the behavior of different graft materials in wide maxillary sinuses, at a height of 8 to 10 mm from the alveolar ridge, combined with bone remnants less than 3mm.

MATERIALS AND METHODS

Thirty-six patients underwent a sinus elevation procedure through the lateral window. The sinuses were randomly filled with the following materials (n=12/group): group 1, xenogenic bone + autogenous bone (ratio 70:30, respectively); group 2, xenogenic bone + L-PRF; and group 3, xenogenic bone. At 8 months, bone biopsies of engrafted sites were harvested and analyzed histomorphometrically in order to quantify newly formed bone tissue.

RESULTS

The results showed a greater area of newly formed bone for G1, averaging 2678.37 (1116.40) μm², compared with G2 at 984.87 (784.27) μm², and G3 at 480.66 (384.76) μm² (p < 0.05). Additionally, fewer xenogenic bone particles and a large amount of connective tissue were observed in G2.

CONCLUSIONS

In maxillary sinuses with large antral cavities, autogenous bone combined with xenogenic bone seems to demonstrate better graft remodeling and improve bone formation, compared with the addition of L-PRF.

CLINICAL RELEVANCE

L-PRF produces few advantages regarding new bone formation in the wide maxillary sinuses.

TRIAL REGISTRATION

Brazilian Clinical Trials Registry (REBEC) number RBR-2pbbrvg.

Prevalence of and factors associated with maxillary sinus cyst in a Chinese population

PURPOSE

This study used cone-beam computed tomography (CBCT) to assess the prevalence of and factors associated with maxillary sinus cysts (MSCs) in a Chinese population.

METHODS

A total of 2,571 CBCT scans of 5,000 sinuses were analyzed. MSCs were diagnosed on the basis of imaging features within the maxillary sinus. Sex, age, dental condition, and anatomic condition were assessed. Associations with these factors were evaluated with logistic regression and a generalized estimating equations model.

RESULTS

The prevalence of MSCs was 15.46% at the sinus level and 23.44% at the patient level. The prevalence of MSCs was higher for men (OR = 1.864, P < 0.001) and for patients with apical lesions (OR = 1.76, P < 0.001), severe bone loss (OR = 1.363, P < 0.05), tooth roots in contact with the sinus floor (OR = 1.68, P < 0.001), and pits or septa on the floor of the maxillary sinus (OR = 1.539, P < 0.001).

CONCLUSION

This large sample had a high prevalence of MSCs. MSC prevalence was associated with multiple factors, including sex, dental condition, and anatomic condition. Maintenance of healthy dental and periodontal status might help prevent MSCs.

Implant survival after graftless sinus floor augmentation in highly atrophic maxillae: a randomized controlled trial in a split mouth study

PURPOSE

The success rate of dental implants after graftless sinus augmentation versus conventional sinus augmentation surgery in atrophic maxillae in edentulous patients was investigated.

METHODS

This randomized study was performed in ten edentulous patients with marked maxillary atrophy. On the graftless side, the sinus membrane was lifted by a resorbable membrane. The control side was augmented with a mixture of autografts and xenografts. Implant placement followed 6 months postoperatively. Outcomes were implant survival, success of prosthetic rehabilitation and stability of vertical bone gain.

RESULTS

Ten patients were included. Postoperative radiology showed sufficient bone gain on both maxillary sides. Follow-up varied from 57 to 88 months. The conventional side showed significant (p = 0.041) more bone gain than the experimental side (respectively, 9.69 mm and 6.20 mm). A total of 59 implants were placed: 30 after conventional, 29 after graftless augmentation. One implant was lost on the conventional side and four on the experimental side. The implant survival was significantly higher on the conventional side (96.7% vs. 86.2%, p < 0.001, RR = 4.14). Prosthetic restoration was functionally successful in all cases.

CONCLUSION

Bone gain and implant survival were significantly lower in the non-grafted side versus the grafted side. Prosthetic rehabilitation was possible in all ten patients. The non-grafted technique may have some potential for clinical use, although it showed poorer results. Trial registration The Netherlands Trialregister. NTR NL3541 (NTR3696). Registered 20 January 2013, https://www.trialregister.nl/trial/3541 .

Long-Term Clinical Study of Implants Placed in Maxillary Sinus Floor Augmentation Using Beta-Tricalcium Phosphate

Introduction. The aim of this study was to show the long-term clinical outcomes of implants placed in maxillary sinus floor augmentation (MFSA) using beta-tricalcium phosphate (β-TCP). Patients and methods. Maxillary patients were diagnosed for MFSA and used beta- β-TCP. After the lateral sinus surgery, implants were loaded at 6 months with restorations. The clinical follow-up was at 10 years. Results. One hundred and one patients (58 females and 43 males) were treated with MFSA. Twenty-nine patients (28.7%) had a history of periodontitis. Thirty-three patients (32.7%) were smokers. One hundred and twenty-one MFSA, 81 unilateral and 20 bilateral sites, with 234 implants were performed. The average vertical bone height available was 4.92 ± 1.83 mm. The average vertical bone gain obtained was 6.95 ± 2.19 mm following MFSA. The implant cumulative survival rate was 97.2%. Three implants (1.3%) were lost during the healing period. Six implants (2.6%) were lost by peri-implantitis. One hundred and fifteen restorations were placed in the patients. Mean marginal bone loss was 1.93 mm ± 1.03 mm. Six patients (27.3%) showed technical complications. Thirty-six implants (15.3%) in 14 patients (13.9%) were associated with peri-implantitis. Conclusions. This study indicates that treatment with implant-supported restoration by MFSA using β-TCP constitutes a successful implant approach.

A retrospective preliminary histomorphometric and clinical investigation on sinus augmentation using enzyme-deantigenic, collagen-preserving equine bone granules and plasma rich in growth factors

Background

Enzyme-deantigenic equine bone (EDEB) is a substitute of autogenous bone. Mixing it with plasma rich in growth factors (PRGF) seems a viable option to achieve enhanced bone formation in alveolar bone augmentation surgeries. This retrospective study aims to first report the histomorphometric and clinical outcomes achieved when using the EDEB/PRGF mixture for performing sinus augmentation procedures followed by delayed implant placement.

Materials and methods

Records of 11 patients who underwent 14 sinus augmentation surgeries using EDEB/PRGF followed by delayed implant placement were retrospectively collected and analyzed to assess histomorphometric data concerning newly formed bone (NFB) and residual biomaterial (RB) recorded at implant placement, marginal bone loss (MBL) values of implants placed in the augmented sinuses, and implant and prosthetic success and survival rates.

Results

At 5.6 ± 1.1 months after grafting, NFB and RB were 34.0 ± 9.1% and 11.3 ± 2.2% respectively, and no histologic signs of inflammation or immune reaction were observed in any of the 34 bone biopsies being collected. Further, 86.5 ± 4.3 months after implant placement, MBL was 0.40 ± 0.07 mm. No implant or prosthesis failed, and the implant success and survival rates were 100%

Conclusions

Within the limitations of the present study, grafting EDEB/PRGF for lateral sinus augmentation and delayed implant placement seems to be safe. Compared to published data concerning EDEB alone, results of the present study do not suggest that the EDEB/PRGF combination may provide a histomorphometric or medium-/long-term clinical advantage.

Non-grafted versus grafted sinus lift procedures for implantation in the atrophic maxilla: a systematic review and meta-analysis of randomized controlled trials

The aim of this systematic review and meta-analysis was to critically evaluate the currently existing clinical evidence on the efficacy of graftless maxillary sinus membrane elevation for implantation in the atrophic posterior maxilla. A search protocol without limitations to November 2020 was followed by two independent researchers. Randomized controlled trials using the lateral window approach for graftless sinus membrane elevation were included. Uncontrolled, retrospective, non-comparative studies, case reports, and experimental studies in animals or cadavers were excluded. The search identified 2777 studies. Critical selection by two independent researchers then led to the inclusion of a total of nine studies. A risk of bias assessment was applied using the revised Cochrane risk-of-bias tool for randomized trials. A meta-analysis was conducted for seven studies. Results showed a high overall implant survival rate in both the graftless and bone-grafted sinus lift groups (97.92% and 98.73%, respectively). The graftless sinus lift group showed a significantly lower vertical bone height gain, with a mean difference of -1.73mm (P=0.01), and a significantly lower bone density, with a mean difference of -94.7 HU (P<0.001). The implant stability quotient values did not differ significantly between the test and control groups (P=0.07).

Long-Term Comparison of Survival and Marginal Bone of Implants with and without Sinus Augmentation in Maxillary Molars within the Same Patients: A 5.8- to 22-Year Retrospective Study

Maxillary sinus floor augmentation (MSFA) is widely used and considered a predictable procedure for implant placement. However, the influence of MSFA on implant survival and marginal bone loss (MBL) is still inconclusive. The purpose of this retrospective observational study is to evaluate the long-term genuine influence of MSFA on the survival and MBL of implants by comparing those with and without MSFA only in maxillary molars within the same patients. Thirty-eight patients (28 male and 10 female), with a total of 119 implants, received implants with and without MSFA, and were followed up for 5.8 to 22 years. Patient- and implant-related factors were assessed with a frailty model for implant survival and with generalized estimation equations (GEE) for MBL around the implant. No variables showed a statistical significance for implant failure in the frailty model. In GEE analysis for MBL, MSFA did not show any statistical significance. In conclusion, MSFA demonstrated no significant influence on implant failure and MBL in posterior maxilla in this study.

The influence of implant design on the kinetics of osseointegration and bone anchorage homeostasis

Titanium implants have shown considerable success in terms of achieving quick and long-lasting stability in bone through the process of osseointegration. Further work aims to improve implant success rates by modifying implant design on the nano-, micro-, and macro- scales with the goal of achieving higher levels of bone anchorage more quickly. However, the most frequently used methods of analysis do not investigate bone anchorage as a whole but as a series of discrete points, potentially missing relevant insight which could inform the effects of topography on these 3 scale ranges. Herein we utilize an asymptotic curve fitting method to obtain a biologically relevant description of reverse torque data and compare the anchorage of 12 different implant groups. Implant surface topography had a significant effect on the rate and degree of anchorage achieved during the initial bone formation period of osseointegration but was not found to influence the relative change in anchorage during bony remodeling. Threaded implants significantly decreased the time required to reach peak anchorage compared to non-threaded implants and implants with micro-topographically complex surfaces required greater torque to be removed than implants without such features. Nanotopography increased overall anchorage and decreased the time required to reach peak anchorage but to a lesser degree than microtopography or macrogeometry respectively. The curve fitting method utilized in the present study allows for a more integrated analysis of bone anchorage and permits investigation of osseointegration with respect to time, which may lead to a more targeted approach to implant design.

Clinical and radiographic outcomes of reentry lateral sinus floor elevation after a complete membrane perforation

BACKGROUND

Although small perforation of the maxillary sinus schneiderian membrane is a well-documented complication during lateral sinus floor elevation (LSFE), complete perforations larger than 10 mm often result in discontinuation of surgery. Reports on reentry LSFE and its long-term outcomes are sparse.

PURPOSE

To evaluate the long-term outcomes of reentry LSFE following complete membrane perforation to elucidate the technical details of the reentry procedure.

MATERIALS AND METHODS

We assessed the medical records of all patients receiving LSFE from 2008 to 2017 in the Department of Oral Implantology, Peking University Hospital of Stomatology. Twenty-two patients receiving reentry LSFE after complete membrane perforation were enrolled. Data were recorded using cone beam computer tomography: including the residual bone height, membrane thickness of the sinus prior to surgery (MT₁ ), and before reentry (MT₂ ), and height of the bone graft during the reentry procedure (HBG). Cumulative survival rate of implants (CSR), marginal bone loss (MBL), and subsequent complications were also recorded.

RESULTS

From 2008 to 2017, 2023 consecutive patients (2262 sinuses) who underwent LSFE were screened. Complete membrane perforation occurred in 28 patients and resulted in discontinuation of surgery (1.2%). Twenty two patients were enrolled and received reentry LSFE within 3-6 months. Two patients undergoing the reentry procedure were suspended due to excessive membrane perforation, while the other 20 finished reentry sinus bone graft. In the reentry procedure, the HBG was 9.73 ± 2.67 mm with 34 implant placements. The MT₁ and MT₂ were 1.03 ± 0.43 and 1.91 ± 1.45 mm, respectively, showing a statistically significant difference (P < .05). After a follow-up of 2-10 years, CSR was 97.1%, and MBL was 0.64 ± 0.50 mm.

CONCLUSIONS

The long-term outcome of reentry LSFE is predictable and reentry LSFE offers a reliable alternative following complete membrane perforation. However, the procedure is relatively sensitive and should be performed by experienced surgeons.

Sinus membrane elevation and implant placement

Sinus Schneiderian membrane elevation surgery is widely performed for dental implant placement in the maxillary posterior region. With regard to sinus elevation surgery, various complications can occur and lead to implant failure. For successful implants in the maxillary posterior region, the clinician must be well acquainted with sinus anatomy and pathology, a variety of bone graft materials, the principles of sinus elevation surgery, and prevention and management of complications.

Injectable thermosensitive chitosan/gelatin-based hydrogel carried erythropoietin to effectively enhance maxillary sinus floor augmentation in vivo

OBJECTIVE

Maxillary sinus floor augmentation (MSFA) is commonly used to increase the alveolar bone height in the posterior maxilla before implant placement. In the present study, we evaluated if the injectable thermosensitive chitosan/β-sodium glycerophosphate disodium salt hydrate/gelatin (CS/GP/GA) hydrogel carried erythropoietin (EPO) could enhance the new bone formation for MSFA in vivo.

METHODS

EPO-CS/GP/GA hydrogel was prepared by ionic crosslinking. Then, characteristics of EPO-CS/GP/GA were evaluated by morphology, injectable property and pH on the gelling time (GT). The release profile of EPO was evaluated by enzyme linked immunosorbent assay (ELISA), and effects of EPO on proliferation and osteoblastic differentiation of bone marrow stromal cells (BMSC) were analyzed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and reverse transcription quantitative real-time PCR (RT-qPCR), respectively. Finally, EPO-CS/GP/GA was injected into the maxillary sinus floor of the rabbit to test the potential application for MSFA.

RESULTS

Results showed that GT was decreased with the increase of pH value. The GT was 110±15s at pH 7.0. SEM images showed that the CS/GP/GA hydrogel had a sponge network structure. Results from ELISA assay revealed that the cumulative release of EPO from the EPO-CS/GP/GA hydrogel reached 67% at 4h, and 94% at 15 days. MTT assay showed that EPO within EPO-CS/GP/GA hydrogel could significantly promote proliferation of BMSCs compared to control group (p<0.001) . Results of RT-qPCR assays demonstrated that the expression of Sp7, Runx2, Col I and Alp were significantly increased from EPO-CS/GP/GA group compared to control group on day 14 (p<0.001). Importantly, EPO-CS/GP/GA hydrogel could significantly induce bone formation (81.98mm³) compared with control group (43.11mm³) after 12 weeks post-implantation in vivo. The calculation of thickness of mesenchymal condensation indicated that thickness of mesenchymal condensation was significantly increased from EPO-CS/GP/GA group (∼121.4μm) compared to control group (∼37μm) resulting in enhancing intramembranous ossification.

SIGNIFICANCE

The EPO-CS/GP/GA hydrogel provides a novel strategy for MSFA with a minimally invasive way.