OBJECTIVE: The aim of this study was to propose a comprehensive maxillary sinus (MS) contour classification system based on the evaluation of anatomical characteristics from cone beam computed tomography (CBCT) examination and investigate the relationship between sinus contours and sinus floor elevation (SFE).
METHODS: A total of 283 CBCT scans from patients who had single tooth loss in the posterior maxilla and underwent SFE were analyzed. The MS was classified at each tooth position. For buccal-palatal evaluation, the classification from Type A to E was narrow-taper, taper, ovoid, square, and irregular, respectively. For mesial-distal evaluation, the classification from Type 1 to 4 was flat, slope, concave, and septa, respectively. The major anatomical parameters evaluated were (1) residual bone height (RBH), (2) sinus width (SW), (3) maxillary sinus angle (MSA), (4) buccal dip angle (BDA), (5) palatonasal recess (PNR), and (6) sinus depth.
RESULTS: Eleven groups of MS contour were classified after detailed calculation. Differences in the RBH, MSA, BDA, and SW among different groups were statistically significant. The narrow-taper and slope MS (A2) group had the highest RBH (8.66 ± 0.77 mm), largest BDA (79.9° ± 3.18°), smallest MSA (19.8° ± 2.01°), and narrowest SW (6.30 ± 1.23 mm). The lowest RBH was in the square and concave sinus (D3) group (5.11 ± 2.70 mm). The ovoid and concave sinus (C3) group had the smallest BDA (50.64 ± 8.73 mm) and largest MSA (74.11° ± 11.52°). The square and flat MS (D1) group had the widest SW (19.13 ± 3.69 mm). A strongly significant positive correlation was observed between the SW and MSA (r = 0.67) and a strongly negative correlation between the SW and BDA (r = - 0.65). The prevalence of PNR (mean angle: 104.06° ± 16.83°, mean height: 14.72 ± 11.78 mm) was 38% and frequently observed in the ovoid and slope MS (C2) group.
CONCLUSIONS: Despite certain characteristics at different tooth sites, the same tooth position was categorized differently using different classification systems, indicating large anatomical variations in the MS. The classification system proposed herein allows for classification based on general characteristics at a single tooth site, aiming to help surgeons in improving presurgical evaluation.

Autogenous dentin matrix (ADM), derived from a patient\'s extracted tooth, can be repurposed as an autologous grafting material in reconstructive dentistry. Extracted teeth provide a source for ADM, which distinguishes itself with its low rejection rate, osteoinductive capabilities and ease of preparation. Consequently, it presents a viable alternative to autogenous bone. Animal studies have substantiated its effective osteoinductive properties, while its clinical applications encompass post-extraction site preservation, maxillary sinus floor augmentation, and guided bone tissue regeneration. Nevertheless, the long-term efficacy of ADM applied in bone regeneration remains underexplored and there is a lack of standardization in the preparation processes. This paper comprehensively explores the composition, mechanisms underlying osteoinductivity, preparation methods, and clinical applications of ADM with the aim of establishing a fundamental reference for future studies on this subject.

OBJECTIVE: Sinus membrane perforation is a common complication of sinus lift surgery. This review aimed to examine if anatomical factors such as the presence of septa and lateral wall thickness influence the risk of membrane perforation.
METHODS: This study was registered on PROSPERO (CRD42023488259). PubMed, Embase, and Web of Science were searched for relevant studies published up to 26th June 2024. The outcome of interest was the risk of perforation based on presence of septa and lateral wall thickness. Random-effects meta-analysis was conducted with dichotomous data to obtain the odds ratio (OR) of perforation using Review Manager.
RESULTS: Ten studies with 1865 patients undergoing 2168 \"lateral\" sinus lift procedures were included. The total incidence of Schneiderian membrane perforations was 19% (405 cases). Schneiderian membrane perforation was present in 169/425 cases (39.76%) with sinus septa and 184/1492 cases (12.33%) without septa. Meta-analysis showed that septa were significantly associated with an increased risk of perforation (OR: 4.03 95% CI: 1.77, 9.19) with high heterogeneity (I2 = 87%). The certainty of the evidence was very low. Data on lateral wall thickness and risk of perforation was too heterogeneous for a meta-analysis. Studies reported mixed results on the risk of perforation based on lateral wall thickness.
CONCLUSIONS: Our results show, with very low-quality evidence, that the presence of septa significantly increases the risk of perforations during maxillary sinus lift surgery. Evidence on the association between lateral wall thickness and a risk of perforations during sinus lift surgery is conflicting, and no clear conclusions can be derived at this stage.

OBJECTIVE: 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.
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.

BACKGROUND: We reviewed the literature to examine if the thickness of the sinus membrane is a risk factor for perforation during lateral sinus lift surgery.
METHODS: We searched Embase, PubMed, and Web of Science databases till 4th December 2023 for studies examining the risk of perforation with different sinus membrane thicknesses. Studies reporting sinus membrane thickness in perforation and non-perforation cases were also included.
RESULTS: Eleven studies were eligible. All studies used cone beam computed tomography for measuring sinus membrane thickness. Meta-analysis showed that sinus membrane thickness was significantly lower in perforation cases as compared to non-perforation cases (MD: -0.91 95% CI: -1.48, -0.33 I2=94%). Four studies used 2mm as the cut-off to define thick and thin sinus membranes. Pooled analysis failed to demonstrate any significant difference in perforation rates (OR: 0.97 95% CI: 0.44, 2.17 I2=56%). Meta-analysis of studies using 1.5mm (OR: 0.66 95% CI: 0.29, 1.48 I2=72%) and 1mm cut-off (OR: 0.93 95% CI: 0.34, 2.56) also demonstrated similar non-significant results.
CONCLUSIONS: Our study shows that the sinus membrane is significantly thinner in cases with perforations as compared to those with no perforations. However, a meta-analysis based on different membrane thickness cut-offs failed to demonstrate a relationship between thinner sinus membranes and a higher risk of perforation. There is a need for further studies examining the role of sinus membrane thickness on perforation rates.

The aim of this study is to analyze the resorption rate of bone graft materials after crestal sinus floor elevation, study its influencing factors, and improve the long-term success rate of implants after crestal maxillary sinus floor elevation. Measurement and analysis were conducted at six postoperative timepoints (0 months, 6 months, 12 months, 18 months, 24 months, and 30 months) using cone beam computed tomography (CBCT) data on 31 patients from the Chenghuaxinguanghua Dental Clinic who underwent crestal maxillary sinus floor elevation, involving 38 graft sites. The materials resorption rates of the bone graft height (BH) and bone graft width (BW) were assessed. BH and BW resorption rates followed the same trend (p = 0.07), with BH and BW resorption rates decreasing with time (rBH = -0.32, p < 0.01; rBW = -0.18, p < 0.01), and were maximal in the 0-6 month interval, with BH and BW resorption rates of 3.42%/mth and 3.03%/mth, respectively. The average monthly BH and BW resorption rates in the 6-12 month interval rapidly decreased to 1.75%/mth and 1.29%/mth, respectively. The monthly BH and BW resorption rates in the 12-30 month intervals stabilized at 1.45%/mth (p > 0.05) and 1.22%/mth (p > 0.05), respectively. The higher the initial bone graft height (BH0), the lower the BH resorption rates (rBH = -0.98, p < 0.05), and the BW resorption rate was different for different graft sites (p = 0.01). The resorption rates of bone graft materials implanted through crestal maxillary sinus floor elevation decreased rapidly within the first 12 months post operation and remained stable after 12 months. BH0 was identified as a significant factor influencing the resorption rates of bone graft materials. These results could suggest dentists should pay attention to the trend of resorption rates over time and carefully manage the initial height of bone grafts and inspire the research of new bone grafting materials for crestal maxillary sinus floor elevation.

OBJECTIVE: To date, it remains a challenge to conduct maxillary sinus floor elevation (MSFE) owing to heterogeneity of anatomical structures and limited operative visibility of the maxillary sinus. The aim of this study is to investigate the safety of MSFE and the accuracy of implant placement using dynamic navigation.
METHODS: Forty-two implants were placed in thirty-five patients requiring implantation in posterior maxilla with dynamic navigation. They were assigned to either lateral window sinus floor elevation (LWSFE) group (n = 22) or transcrestal sinus floor elevation (TSFE) group (n = 20) according to the residual alveolar bone height (RBH). Platform deviation, apex deviation and angular deviation between actual and planned implant placement were measured in precision evaluation software. Three deviations of two groups were compared via SPSS 22.0 software.
RESULTS: Neither accidental bleeding nor perforation of Schneiderian membrane occurred in any patients. The actual window position of LWSFE was consistent with the preoperative design. There were no significant differences in platform, apex and angular deviations between the two groups (P > 0.05).
CONCLUSIONS: In this study the dynamic navigation harvested clinically acceptable safety of MSFE and accuracy for implant placement in posterior maxillary region. The dynamic navigation would provide the clinician with assistance in achieving precise preoperative planning and reducing complications in surgical procedures. The granular bone grafts used in the LWSFE did not significantly affection on the accuracy of the simultaneous implant placement under the guidance of dynamic navigation.

Perforation of the maxillary sinus membrane is a common complication during maxillary sinus elevation. Intraoperative perforation of the maxillary sinus membrane may complicate the procedure and indirectly lead to implant failure. Timely repair of the perforated maxillary sinus membrane can effectively improve the implant survival rate. This case describes a method of repairing a maxillary sinus membrane perforation with a suture-attached collagen membrane and shows stable repair results at a 31-month follow-up.

OBJECTIVE: To analyze the bone remodeling around the implant 10 years after disk-up sinus reamer(DSR)-based internal sinus floor elevation with implantation and to investigate the influence of different factors on implant retention.
METHODS: The clinical and imaging data of patients undergoing DSR-based sinus floor elevation with simultaneous implantation were collected from the Department of Dental Implantology, Affiliated Hospital of Qingdao University from January 2008 to December 2011. Panoramic film and CBCT were used to measure the changes of bone mass around implant in different periods. Kaplan-Meier and Log-rank tests were used to analyze the effects of different factors on implant retention with SPSS 26.0 software package.
RESULTS: The study included 98 patients with a total of 128 implants. During the follow-up of 0-168 months, 7 implants failed, and the remaining formed good osseointegration and functioned, with a 10-year cumulative retention rate of 94.53%. The height of bone formation was (0.29±0.15) mm at the top and (2.74±0.66) mm in the sinus of 75 implant sites with complete imaging data obtained ten years after surgery. Kaplan-Meier and Log-rank tests showed that 8 factors including initial bone height, elevated bone height, mucosal perforation, implant length, implant torsion, diabetes, smoking and periodontitis had significant effects on implant retention.
CONCLUSIONS: The DSR-based internal sinus floor elevation with implantation is a reliable and stable bone augmentation operation for vertical bone defect in maxillary posterior region, with a 10-year cumulative retention rate of no less than 94%. Initial bone height, elevated bone height, mucosal perforation, implant length, implant torsion, diabetes, smoking and periodontitis are the important factors affecting the long-term retention rate of implants.

OBJECTIVE: This study analyzed and compared the biomechanical properties of maxillary sinus floor mucosa with implants at three different maxillary sinus angles during a modified internal sinus floor elevation procedure.
METHODS: 3D reconstruction of the implant, maxillary sinus bone, and membrane were performed. The maxillary sinus model was set at three different angles. Two internal maxillary sinus elevation models were established, and finite element analysis was used to simulate the modified maxillary sinus elevation process. The implant was elevated to 10 mm at three maxillary sinus angles when the maxillary sinus floor membrane was separated by 0 and 4 mm. The stress of the maxillary sinus floor membrane was analyzed and compared.
RESULTS: When the maxillary sinus floor membrane was separated by 0 mm and elevated to 10 mm, the peak stress values of the implant on the maxillary sinus floor membrane at three different angles were as follows: maxillary sinus I: 5.14-78.32 MPa; maxillary sinus II: 2.81-73.89 MPa; and maxillary sinus III: 2.82-51.87 MPa. When the maxillary sinus floor membrane was separated by 4 mm and elevated to 10 mm, the corresponding values were as follows: maxillary sinus I: 0.50-7.25 MPa; maxillary sinus II: 0.81-16.55 MPa; and maxillary sinus III: 0.49-22.74 MPa.
CONCLUSIONS: The risk of sinus floor membrane rupture is greatly reduced after adequate dissection of the maxillary sinus floor membrane when performing modified internal sinus elevation in a narrow maxillary sinus. In a wide maxillary sinus, the risk of rupture or perforation of the wider maxillary sinus floor is reduced, regardless of whether traditional or modified internal sinus elevation is performed at the same height.