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 ± 13.0 kPa, 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.     

Maxillary sinus floor augmentation and dental implant placement using dentin matrix protein-1 gene-modified bone marrow stromal cells mixed with deproteinized boving bone: A comparative study in beagles

ObjectiveThe aim of the study was to evaluate the effects of the combined use of dentin matrix protein-1 (DMP1) gene-modified bone marrow stromal cells (BMSCs) and Bio-Oss^® for maxillary sinus floor augmentation (MSFA) implant placement in dogs.Materials and methodsBMSCs were derived from bone marrow of six beagles and cultured. The cells were transduced with a lentiviral vector overexpressing the DMP1 gene and enhanced green fluorescent protein (EGFP) gene (Lenti-DMP1/EGFP) in test group, and with a lentiviral vector encoding EGFP gene (Lenti-EGFP) in control group. Six dogs received sinus augmentations using the bilateral approach with a simultaneous implant placement at each site respectively. At the same concentration, 2 × 10⁷ cells/ml, one sinus was grafted using a mixture of autologous DMP1/EGFP gene-modified BMSCs and Bio-Oss^® (DMP1 group), and the contralateral sinus was grafted with autologous EGFP gene-modified bMSCs and Bio-Oss^® (EGFP group). After a 3 month healing period, bone regeneration and osseointegration were evaluated using histologic and histomorphometric methods.ResultsThe bone-implant contact (BIC) and the bone area fraction in the DMP1 group (BIC: 34.67% ± 8.23%, bone area fraction: 35.16% ± 3.32%) were significantly greater compared with the EGFP group (BIC: 26.06% ± 5.16%, bone area fraction: 20.74% ± 1.63%) (P < 0.05). No significant difference between the residual bone substitute material volume (BSMV) in the DMP1 group (35.86 ± 7.35) and the EGFP group (32.16 ± 9.16) was found in our study (P > 0.05).ConclusionBMSCs modified with the DMP1 gene can be used as an adjunct to Bio-Oss^® to enhance new bone formation and the osseointegration of dental implants in MSFA of dogs.     

Dynamics and risk indicators of intrasinus elevation height following transalveolar sinus floor elevation with immediate implant placement: a longitudinal cohort study

Successful intrasinus graft consolidation is essential for the treatment outcome of transalveolar sinus floor elevation (SFE). This study was performed to examine the dynamics and risk indicators related to the elevation height after transalveolar SFE with grafting material and simultaneous implant placement. Fifty-two patients with 55 sites undergoing transalveolar SFE with immediate implant placement were enrolled retrospectively. Cone beam computed tomography (CBCT) images were collected and saved in DICOM format, at the following time-points: pre-surgery (T0), immediately post-surgery (T1), and 6 months post-surgery (T2). Voxel-based CBCT superimposition was performed to measure the sinus width, residual alveolar height, implant protrusion length, total elevation height, and apical graft height. The change in total elevation height from T1 to T2 was defined as the study outcome. Clinical and linear variables were analysed using linear regression. From T1 to T2, the total elevation height showed an average reduction of 1.0 ± 1.1 mm, while 10.9% sites showed an increased elevation height. Univariate regression analysis showed no significant correlation between tested clinical or linear variables and the study outcome. The results suggest that the change in elevation height was not influenced by the alveolar or sinus dimensions, graft materials, implant diameter, implant protrusion length, or the total elevation height at T1.     

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 ± 4.4 mm, width 4.1 ± 2.9 mm, height 3.5 ± 2.1 mm. 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.     

经牙槽嵴顶上颌窦底提升术植骨与否的研究进展

上颌后牙区常因骨量不足而成为种植的难点区域,常用的解决办法为上颌窦侧壁开窗窦底提升术和经牙槽嵴顶上颌窦底提升术。经牙槽嵴顶上颌窦底提升术因为手术操作简单、创伤小、愈合时间短、术后不适感少等优点逐步得到广泛应用。该技术早期应用常伴有同期植骨,但由于骨替代材料存在感染、低吸收率及引发上颌窦再气化等风险,近些年来临床上开始主张经牙槽嵴顶上颌窦底提升时不再植骨。目前对经牙槽嵴顶上颌窦底提升术中植骨与不植骨的愈合状况和临床疗效等方面都有较多的研究报道。本文就经牙槽嵴顶上颌窦底提升术是否需要同期植骨的研究进展做如下综述。     

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 ?1.73 mm (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).     

经侧壁开窗上颌窦底外提升植骨术窦黏膜穿孔及处理

垂直骨量不足是上颌后牙种植的常见问题。上颌窦底提升植骨技术为种植体植入及修复创造了条件,成为上颌后牙区骨量不足的常规骨增量技术。穿牙槽嵴技术（内提升）虽然具有创伤更小、手术时间缩短、并发症更少等优点,但是要求医生具有侧壁开窗上颌窦底提升（外提升）的经验,以便于临床中能够及时安全有效地处理内提升出现的并发症。上颌窦外提升虽可发生术中黏膜穿孔、术后感染等并发症,但经过妥善处理,仍可获得良好的植骨效果和较高的种植体存留率。文章针对上颌窦外提升最常见的黏膜穿孔,针对其发生的风险因素及穿孔处理进行报告,为上颌后牙缺失患者的种植修复治疗提供参考。     

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??Vertical bone deficiency is common in the edentulous posterior maxilla. During the last decades??maxillary sinus floor elevation has become a reliable and predictable augmentation technique to facilitate implant placement in the posterior maxilla region with inadequate bone height. Sinus floor elevation by transcrestal approach gained lots of popularity recently due to the advantages such as less trauma??shortened surgical time and less postoperative reaction??but it requires that clinicians have rich experience in lateral window technique in case of handling with the complications of membrane perforation and bleeding??etc. This article discussed the risk factors and management of membrane perforation during sinus floor elevation by lateral window approach.     

Effect of platelet rich plasma on bone regeneration in maxillary sinus augmentation (randomized clinical trial)

This study evaluates bone quality in sinus augmented with autogenous bone with or without platelet rich plasma (PRP) mix. 15 partially edentulous patients requiring maxillary sinus floor augmentation, followed by implant insertion were studied. In Group I, 5 patients underwent maxillary sinus lifting with autogenous bone augmentation and implant insertion at 6 months post grafting. In Group II, 10 patients underwent maxillary sinus lifting with autogenous bone augmentation mixed with PRP prepared from the patient's own blood with implant insertion at 4 or 6 months post grafting (n = 5 for each implantation time). A core biopsy was taken at the time of implant placement for histological and histomorphometric evaluation. Immediately and 3 months after implantation, Group I showed the statistically significant highest mean bone density (p = 0.046 and 0.022, respectively). At 6 months post-implantation, Group II showed the statistically significant highest mean bone density (p = 0.041). Histomorphometric analysis showed that Group I had the statistically significant highest mean value (39.5 ± 7.4; p = 0.003). Enrichment with PRP did not significantly improve bone density or morphometric value at 3 months post grafting. PRP enriched bone grafts were associated with superior bone density at 6 months post grafting.     

Virtual quad zygoma implant placement using cone beam computed tomography: sufficiency of malar bone volume,intraosseous implant length,and relationship to the sinus according to the degree of alveolar bone atrophy

The objective of this study was to investigate the malar bone volume and length that a zygomatic implant can engage, and the relationship to the sinus according to the degree of alveolar bone atrophy. A three-dimensional evaluation was performed using cone beam computed tomography scans from 23 patients with a totally edentulous maxilla; quad zygoma implants were virtually placed. The predictor variable was the amount of malar bone volume and length that a zygomatic implant can engage. The primary outcome variable was the relationship to the sinus according to the degree of alveolar bone atrophy. Other variables were the residual alveolar bone height to the floor of the sinus and the nasal cavity. The mean volume of malar bone engaged in this sample of 92 zygomatic implants was 0.19 ± 0.06 cm³. The implant had an extrasinus path in 60.9% of cases, a parasinus path in 25%, and an intrasinus path in 14.1%. The results suggest that the average volume of malar bone engaged by a zygomatic implant is constant regardless of implant position and the degree of alveolar bone atrophy. As alveolar atrophy increases, the trajectory of the implant becomes more parasinus and intrasinus. The examiners were able to find enough bone to adequately distribute the implants in all cases.     

Transcrestal sinus floor elevation: a retrospective study of 46 patients up to 16 years

Background: The aim of this study was to evaluate the clinical outcomes and radiographic data of transcrestal sinus floor elevation (TSFE) of residual alveolar bone ≤3 mm. Methods: Forty‐six patients, edentulous in one or both maxillary posterior segments, were enrolled in this study. The residual alveolar ridge was measured. TSFE without bone grafting was performed. Three months after the first surgery procedure, 66 implants were placed without grafting material. A presurgical distance from the alveolar crest to the floor of the maxillary sinus and the amount of new radiopacity between the sinus floor and alveolar crest were measured from the mesial and distal surfaces of each dental implant surface. Results: After a mean follow‐up period of 10.43 ± 5.01 years (ranged from 5 to 16 years), a survival rate of 95.45% was reported. Mean bone levels at implant placement were 7.12 ± 0.90 mm and, after 1 year, were 13.28 ± 1.23 mm. They were stable over time, reporting an up to 16 years' value of 13.07 ± 2.63 mm. Conclusions: The results of this retrospective clinical study confirmed the reliability of the TSFE procedure and the maintenance of bone levels without grafting procedures over time.     

Simulation of sinus floor augmentation with symphysis bone graft using three-dimensional computerized tomography

The objective of this study was to evaluate the maximum amount of harvestable bone graft in the mandibular symphysis and the augmentation volume needed for different sinus lift levels (from 10 to 18 mm), in addition to calculating which sinus lift level can be acquired using the individual's symphysis bone graft volume with three-dimensional computerized tomography (3D CT) and software. Data from 15 CT scans was obtained from 15 adult patients (10 males, five females). The CT data, in DICOM format, was read into Mimics software from Materialize (Leuven, Belgium), with a slice thickness of 0.5 mm. The mandibular symphysis bone graft volumes and different levels of sinus lift augmentation volumes were calculated on the 3D images using Mimics software. It was determined that the average symphysis bone volume (3491.08 ± 772.12 mm³) could provide approximately 14 mm of sinus lift height (3167.84 ± 1067.65). 3D CT techniques and software can be used to calculate the required graft volume for sinus floor augmentation and symphysis bone graft volume, and the mandibular symphysis region can provide adequate bone volume for sinus lift augmentation.     

Calvarial graft resorption index in the reconstruction of the maxillary sinus in patients with atrophic maxillas: a prospective clinical study

The objective of this study was to assess the resorption index of particulate calvarial grafts in maxillary sinuses of patients undergoing total reconstruction of an atrophic maxilla with residual alveolar bone that was less than, or equal to, 3 mm thick. Twenty-one maxillary sinus floor elevations were carried out using particulate calvarial grafts in 11 individuals with totally edentulous maxillas. All patients had computed tomography (CT) before (T0), and 48 hours (T1) and six months after surgery (T2). For each CT scan, linear measurements were taken of sections of the anterior, medial, and posterior regions of the maxillary sinus. There was a significant increase in the height of the maxillary sinus floor when T0 was compared with T1 (p = 0.001). There was a statistically significant reduction in all maxillary sinus measurements when T1 was compared with T2; the mean height reduction being 2.36 mm (16.87%) in the anterior region, 3.53 mm (22.47%) in the medial region, and 2.21 mm (22.78%) in the posterior region (p = 0.001). Mean resorption was 20.7%. Autogenous calvarial bone used alone is an option for graft material in pneumatised maxillary sinuses and in cases where there is limited alveolar bone.     

Evaluation of the posterior superior alveolar artery location and diameter with a newly defined stable plane

The aim of this study was to analyse the vertical location of the posterior superior alveolar artery (PSAA) using a reliable new reference plane regardless of tooth and alveolar bone, and to measure the diameter in each posterior tooth region, which is of relevance to lateral sinus floor elevation surgery. A total of 270 sinuses in 139 patients were examined in this study. The A-plane was defined by A-point and the bilateral jugal points on reconstructed three-dimensional images. The distance from the PSAA to the defined plane was measured in four regions: first premolar (P1), second premolar (P2), first molar (M1), and second molar (M2). The average distance of the PSAA above the plane in the P1, P2, M1, and M2 regions was determined to be 10.24 mm, 7.35 mm, 5.47 mm, and 7.23 mm, respectively. The PSAA was found to run above the plane in 97.4% of sinuses, below the plane in 1.1%, and on the plane in 1.5%. In conclusion, the new plane is useful for intraoperative location of the PSAA. According to the study findings, the area below the reference plane can be considered safe for lateral approach sinus surgery in terms of preserving the integrity of the PSAA.     

Short implants (≤8 mm) compared to standard length implants (>8 mm) in conjunction with maxillary sinus floor augmentation: a systematic review and meta-analysis

The objective was to test the hypothesis of no difference in the treatment outcome after the installation of short implants (≤8 mm) in the posterior part of the maxilla compared to standard length implants (>8 mm) in conjunction with maxillary sinus floor augmentation (MSFA) using the lateral window technique, after an observation period of ≥3 years. A search of the MEDLINE, Embase, and Cochrane Library databases, in combination with a hand-search of relevant journals, was conducted. The search yielded 1102 titles. Finally, three studies that fulfilled the inclusion criteria were included. All were considered to have a low risk of bias. Meta-analyses revealed no significant differences in implant survival or peri-implant marginal bone loss between the two treatment modalities. However, the use of standard length implants in conjunction with MSFA was characterized by a tendency towards more peri-implant marginal bone loss. There was no statistically significant difference between the two treatment modalities with regard to overall patient satisfaction. Short implants seem to be a suitable alternative to standard length implants in conjunction with MSFA. However, further randomized controlled trials with larger patient samples and an observation period of more than 3 years are needed before one treatment modality might be considered superior to the other.     

三斜磷钙石糊剂封闭牙本质小管的体外研究

体外评价三斜磷钙石糊剂对牙本质小管的封闭作用,为牙本质敏感症的治疗提供新的手段。     

Minimal invasiveness in the transcrestal elevation of the maxillary sinus floor: A systematic review

In the attempt to reduce the invasiveness of a transcrestal sinus floor elevation procedure, different aspects must be considered; that is, the minimization of intra‑ and postsurgery morbidity, the reduction of treatment time, and the simplification/elimination of the reconstructive technology. Within this context, a systematic literature search was performed for controlled clinical trials evaluating the impact of one or more of these aspects on transcrestal sinus floor elevation invasiveness. Nineteen articles (15 studies) were included. Overall, the results confirmed that transcrestal sinus floor elevation is a minimally invasive and effective option for bone augmentation in the edentulous, atrophic posterior maxilla. By using powered instruments rather than manual osteotomes and hand mallet, the invasiveness of transcrestal sinus floor elevation can be further reduced without affecting its clinical effectiveness. To impact effectively on morbidity, the key elements to consider when selecting instruments for transcrestal sinus floor elevation are (a) their availability as a standardized sequence, to be adapted on predetermined residual bone height, and (b) the possibility to control pressure (eg, with screwable osteotomes) and/or instrument excursion (eg, with stop devices) to fracture the maxillary sinus floor. Among powered instruments, a standardized sequence of drills incorporating a trephine drill seem to be particularly indicated, due to reduced chair time, high tolerability for the patient, and the possibility to isolate a bone core to implement histomorphometric outcomes. At molar extraction sites with an interradicular septum characterized by a height of at least 4 mm, immediate transcrestal sinus floor elevation and implant placement can be considered a valid option to shorten treatment time.     

Radiographic outcomes of lateral sinus floor elevation with and without bone window repositioning: one-year results of a randomized controlled trial

The objective of this study was to perform a comparative evaluation of the radiographic outcomes of lateral sinus floor elevation with and without bone window repositioning (BLSFE and LSFE, respectively) when applied concomitantly with implant placement. A randomized controlled clinical trial was conducted between February 1, 2016 and May 1, 2017 including 26 individuals with at least one missing tooth. Participants were randomized 1:1 to undergo BLSFE (10 participants, 16 implants) or LSFE (13 participants, 19 implants). Bovine-derived xenograft was used in both groups and the implants were inserted concomitantly. In the BLSFE group, the antrostomy was covered with a repositioned bone window and then with a concentrated growth factors (CGF) membrane. In the LSFE group, the antrostomy was covered with a CGF membrane. Panoramic radiographs were taken before surgery (T0), immediately postoperative (T1), and at 12 months postoperative (6 months after loading) (T2). Marginal bone loss (MBL), apical bone gain, augmented alveolar bone height, and intra-sinus bone augmentation were evaluated on panoramic radiographs at T2. A linear regression analysis with generalized estimating equation models was performed. The implant survival rate was 100% at 1 year after implant surgery. The residual alveolar bone height at T0 was comparable in the BLSFE and LSFE groups (3.58 ± 1.49 mm vs 4.12 ± 1.61, P = 0.32), as was the alveolar bone height at T1 (13.61 ± 1.82 mm vs 12.38 ± 1.82 mm, P = 0.06). At T2_, significantly higher alveolar bone height, intra-sinus bone augmentation, and apical bone gain, and lower distal MBL were observed in the BLSFE group when compared to the LSFE group, with adjusting for covariates (β = 2.44, 95% CI 1.42–3.46, P < 0.0001; β = 2.38, 95% CI 1.35–3.41, P < 0.0001; β = 2.33, 95% CI 1.23–3.42, P < 0.0001; and β = ?0.43, 95% CI ?0.83 to ?0.02, P = 0.038, respectively). No significant difference was observed for mesial MBL or apical bone resorption at T2. Lateral sinus floor elevation with bone window repositioning may result in higher bone augmentation after 1 year than the traditional approach. Further research is needed to elucidate the effect of lateral sinus floor elevation with bone window repositioning.