Anatomical analyses for maxillary sinus floor augmentation with a lateral approach: A cone beam computed tomography study

Collaboration between otolaryngologists and oral surgeons in maxillary sinus elevation planning

BACKGROUND

The collaboration between otolaryngologists and dental providers is crucial for the planning and execution of maxillary sinus elevation (MSE) procedures, which are integral to successful dental implant placements.

PURPOSE

This article examines the essential role of otolaryngological assessments in identifying potential sinonasal risks that could impact the outcomes of MSE.

MATERIALS AND METHODS

A comprehensive narrative review of existing literature was conducted.

DISCUSSION

The review underscores the importance of thorough preoperative evaluations, including patient history, computed tomography (CT) or cone-beam CT (CBCT) scans, and nasal endoscopy, to mitigate sinonasal health risks. It details various clinical scenarios and patient assessments, emphasizing a systematic approach to diagnosing and managing sinonasal conditions proactively. The discussion reveals that while some sinus conditions may not significantly affect MSE success, conditions impacting mucociliary clearance and sinus drainage are critical risk factors requiring otolaryngological intervention. Additionally, the article introduces a grading system to assist clinicians in identifying patients who would benefit from otolaryngological evaluations prior to MSE.

CONCLUSION

This review highlights the value of interdisciplinary collaboration and standardized protocols in enhancing the predictability and safety of MSE procedures, ultimately improving patient outcomes.

Pathogenic factors of maxillary sinus mucosal thickening observed by cone-beam computed tomography (CBCT)

OBJECTIVE

To explore the pathogenic factors associated with maxillary sinus mucosal thickening with Cone-beam computed Tomography (CBCT).

METHODS

From 2016 through 2020, 93 patients with periapical periodontitis or periodontitis in the maxillary posterior dental region were selected.

RESULTS

The preoperative thickness of the periodontitis group was significantly higher than that of the periapical periodontitis group (P < 0.05). The difference achieves statistical significance for the comparison of the thickness change with various severity of inflammation (F = 54.824, P = 0.000), the change with time (F = 312.741, P = 0.000). and the change with the interaction severity of inflammation and time（F = 86.132, P = 0.000).

CONCLUSIONS

Patients with maxillary sinus mucosa thickening caused by periodontitis and periapical periodontitis should be extracted their infectious teeth and get thoroughly debridement. Maxillary sinus augmentation can perform favorable efforts 3-6 months after extracting teeth.

Mucosal adhesion phenomenon after maxillary sinus floor elevation: A preclinical study

AIM

To describe the histological events that occur after maxillary sinus floor elevation when the elevated and undetached sinus mucosa are in close proximity or in contact with each other.

MATERIALS AND METHODS

From 76 rabbits, 152 elevated maxillary sinuses were analyzed histologically. Sites without adhesions were classified as "No proximity," whereas the adhesion stages were divided into "Proximity," "Fusion," and "Synechia stages." The width of the pseudostratified columnar epithelium and the distance between the two layers of the elevated and undetached sinus mucosae were measured at various standardized positions.

RESULTS

Thirty-one sites presenting with adhesions were found. Twelve sites were in the proximity stage," presenting cilia of the two epithelial layers that were shortened and interlinked within the mucous context. Hyperactivity of the goblet cells was also observed. In the other cases, the hyperplastic epithelium showed attempts to reach the contralateral mucosa. The 15 "fusion stage" sites presented regions with epithelial cells of the two mucosal layers that penetrated each other. Four sites presented "synechiae stages," represented by bridges of connective tissue connecting the two lamina propria.

CONCLUSIONS

Close proximity or tight contact between the elevated and undetached mucosa adhering to the bone walls might occur after maxillary sinus floor elevation. This induced hyperplasia of the epithelial cells and adhesion of the two layers until synechiae formation.

Anatomic evaluation of the posterior superior alveolar artery using cone-beam computed tomography: A systematic review and meta-analysis

Purpose

This systematic review examined the detection of the posterior superior alveolar artery, along with various anatomic characteristics, on cone-beam computed tomography images.

Materials and Methods

Studies were identified electronically through the Web of Science, MEDLINE, Scopus, and Embase databases. The quality of the included studies was evaluated using a 5-item binary scale. The detection rate, location, and classified diameter of the posterior superior alveolar artery were estimated as prevalence values. The diameter of this artery, as well as the distances from the artery to the alveolar crest and sinus floor, were estimated as means with associated 95% confidence intervals.

Results

Thirty-seven studies were enrolled, with 34 of these included in the meta-analysis. The mean detection rate was 79% (range: 72%-84%), and the mean diameter was 1.06±0.05 mm (range: 0.96-1.16 mm). The posterior superior alveolar artery was located intraosseously in 64% of cases. The mean distance of the artery from the alveolar crest was 16.71±0.49 mm (range: 15.75-17.68 mm), while the mean distance from the artery to the sinus floor was 8.85±0.4 mm (range: 8.05-9.64 mm).

Conclusion

According to the findings of this meta-analysis regarding various anatomic characteristics of the posterior superior alveolar artery, severe hemorrhage after damage to this artery during sinus augmentation procedures is not a substantial clinical problem.

Which factors affect the risk of membrane perforation in lateral window maxillary sinus elevation? A prospective cohort study

It was the aim of this prospective cohort study to assess the various anatomical and other patient-related factors that increase membrane perforation risk. Patients underwent cone-beam computed tomography (CBCT) before surgery. The presence of septa, presence of mucous retention cyst, lateral wall thickness, membrane thickness, and residual bone height were predictive factors. Age, gender, and smoking were covariates for the study. The presence or absence of membrane perforation was the study outcome. In total, 140 subjects were studied. The hazard ratio (HR) for the presence of septa with membrane perforation was 8.07 (2.93-22.29) (p < 0.001). The HR for perforation with a single edentulous area relating to two or more teeth was 68.09 (9.52-49.16). The risk of membrane perforation in smokers was 25 times more than in non-smokers - HR 25 (7.58-82.51) (p < 0.001). The HR for membrane perforation in subjects with mucous retention cysts compared with subjects without retention cysts was 27.75 (8.73-88.23) (p < 0.001). Within the limitations of the study it seems that anatomical, habitual, and pathological factors may increase the risk of Schneiderian membrane perforation when a lateral window approach is used for sinus floor augmentation.

Evaluation of Two Configurations of Hydroxyapatite and Beta-Tricalcium Phosphate in Sinus Grafts with Simultaneous Implant Installation: An Experimental Study in Rabbits

BACKGROUND

This study aimed to evaluate peri-implant bone formation in rabbits after sinus grafting mediated by hydroxyapatite and beta-tricalcium phosphate (HA + β-TCP) in granule or paste configurations, concomitant with immediate implant installation.

MATERIAL & METHODS

Thirty-four rabbit maxillary sinuses were grafted with HA + β-TCP, half of which were applied in a granule and half in a paste composition. Implant placement was performed simultaneously. At 7 and 40 days postoperatively, the animals were euthanized, and samples were prepared for tomographic, microtomographic, histological, histometric (hematoxylin and eosin staining, HE), and immunohistochemical (labeling of transcription factor Runx-2 [RUNX2], vascular endothelial growth factor [VEGF], osteocalcin [OCN], and tartrate-resistant acid phosphatase [TRAP]) analysis. Implant removal torque was also measured.

RESULTS

On tomography, maintenance of sinus membrane integrity was observed in both the groups. Higher values of morphometric parameters evaluated by micro-CT were found in the "paste group" after seven days. At 40 days, there were no significant differences between the groups in most of the microtomographic parameters evaluated. In histological sections stained with HE, a higher percentage of newly formed bone was observed in the "granule group" after 40 days. Similar positive immunolabeling was observed for both RUNX2 and OCN in both the experimental groups. TRAP immunolabeling was similar in both groups as well. VEGF labeling increased in the "granule group", indicating a higher osteoconductive potential in this biomaterial. Similar removal torque values were observed in both groups. Thus, the two HA + β-TCP configurations showed similar healing patterns of simultaneously installed implants adjacent to sinus floor elevation. However, significantly higher bone values were observed for the "granule configuration".

CONCLUSIONS

The HA + β-TCP granules and paste presentations showed favorable long-term healing results, with bone formation in similar quantities and quality adjacent to the implants.

Modified transcrestal sinus floor elevation with concomitant implant placement in edentulous posterior maxillae with residual bone height of 5 mm or less: a non-controlled prospective study

The aim of this study was to describe a modified transcrestal sinus floor elevation (mTSFE) technique and to evaluate its clinical effectiveness and reliability when residual bone height is severely reduced. Forty-three maxillary edentulous patients who met the inclusion criteria were enrolled. All patients underwent the mTSFE technique; 66 dental implants were inserted simultaneously. Patient-reported outcomes were assessed 2 weeks after surgery. Prosthetic crowns were placed 6 months after surgery. Radiographic analyses and clinical analyses were conducted to assess the clinical effectiveness and feasibility of mTSFE during a follow-up period of 2-8 years. The mean vertical bone increase after surgery was 8.09 mm, and it decreased to 6.56 mm at 6 months after surgery. Two cases of membrane perforation occurred during surgery and one implant was lost in the third year after surgery; the survival rate at the implant level was 98.48%. No severe postoperative complication was reported and the subjective feeling of patients was acceptable. This mTSFE technique could simplify the operative procedure and might be helpful to reduce intraoperative trauma, as well as to alleviate postoperative discomfort.

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.

Schneiderian Membrane Collateral Damage Caused by Collagenated and Non-Collagenated Xenografts: A Histological Study in Rabbits

BACKGROUND

The Schneiderian membrane (SM) that is in contact with biomaterial granules may become thinner and eventually perforate. It has been shown that these events are related to the biomaterial used. Hence, the main aim of the present study was to compare the damaging effects of two xenografts with different resorbability rates on SM. The secondary aim was to evaluate the possible protection from damage offered by a collagen membrane placed adjacent to the SM and by inward displacement of the bone window with the SM during elevation.

METHODS

Thirty-six albino New Zealand rabbits underwent bilateral sinus elevation. One group of 18 animals received deproteinized bovine bone mineral (DBBM group) and the other received swine-collagenated corticocancellous bone (collagenated group). Moreover, in the DBBM group, the bone window was displaced inward during elevation in one sinus together with the SM. In the collagenated group, a collagen membrane was placed adjacent to the SM in one sinus. Six animals were assessed per period after 2, 4, and 8 weeks.

RESULTS

The mean pristine mucosa width ranged between 67 µm and 113 µm, and none had a width of <40 µm. In the 2-week group, the elevated mucosa of the DBBM group presented 59 thinned sites and five perforations, while in the collagenated group, 14 thinned sites and one perforation were observed. Damage to SM decreased in number in the 4-week treatment group. In the 8-week group, the number of thinned sites in the DBBM group increased to 124, and the perforations to 8. In the collagenated group, 7 thinned sites and 1 small perforation were observed.

CONCLUSIONS

More damage to the Schneiderian membrane was observed in the DBBM group than in the collagenated group. The presence of the inward bone window offered protection from damage to the Schneiderian membrane.

Healing Patterns of Non-Collagenated Bovine and Collagenated Porcine Xenografts Used for Sinus Floor Elevation: A Histological Study in Rabbits

Objective: To compare healing of collagenated and non-collagenated xenografts used for maxillary sinus floor elevation. Materials and Methods: Two different xenografts were used: deproteinized bovine bone (DBBM group) and collagenated corticocancellous porcine bone (collagenated group). Healing was studied after 2, 4, and 8 weeks. The loss of dimensions of the elevated area and the percentages of new bone, xenograft remnants, osteoclastic zones, vessels, inflammatory infiltrates, and soft tissues were analyzed. Three regions were evaluated: close to the bone walls (bone wall region), subjacent the sinus mucosa (submucosa region), and the center of the elevated area (middle region). The primary variables were the percentage of new bone and xenograft remnants. Results: Between 2 and 8 weeks, the elevated areas showed a reduction of 16.3% and 52.2% in the DBBM and collagenated groups, respectively (p < 0.01 between the two areas after 8 weeks). After 8 weeks, the highest content of new bone was observed in the bone wall region, which was higher in the collagenated group than in the DBBM group (41.6% and 28.6%, respectively; p < 0.01). A similar quantity of new bone was found between the two groups in other regions. A higher percentage of vessels in all regions evaluated (p < 0.01) and soft tissue in the sub-mucosa region (p < 0.05) was found in the collagenated group than in the DBBM group. Conclusions: The present study showed that both xenografts allowed new bone formation. In comparison with the non-collagenated xenograft, the collagenated xenograft underwent higher resorption, resulting in greater shrinkage of the elevated space after sinus lifting and a higher content of new bone in the regions close to the bone walls. Clinical relevance: In this study, the region adjacent to the bone wall showed the highest new bone content. This region resembles the base of the sinus, closest to the sinus floor and walls, and is the most important region from a clinical point of view because it is where the implant will be installed. Residues of the biomaterial remained after 8 weeks of healing. Other reports have shown that these biomaterial residues may interfere with the integration of implants.

Anatomical variations and accessory structures in the maxilla in relation to implantological procedures: an observational retrospective study of 212 cases using cone-bean computed tomography

PURPOSE

This study used cone-beam computed tomography (CBCT) to analyze the prevalence of several maxillary anatomical/accessory structures, as well as variations within each type, assessing how accurate diagnosis can minimize the risk of intraoperative complications during implantological procedures in the oral cavity.

METHODS

212 CBCT scans of the maxilla were analyzed, captured over a period of 18 months for surgical planning purposes. The prevalence of posterior superior alveolar arteries (PSAA), maxillary sinus septa (MSS), and branches of the canalis sinuosus (CS) were evaluated, as were the diameter and location of each anatomical structure in horizontal and vertical planes. P < 0.05 was considered statistically significant.

RESULTS

PSAAs were observed in 99.1% of cases, the intrasinus type being the most frequent; MSS were noted in 15.6% of the sample, mainly in the posterior region with sagittal orientation; CS branches were observed in 50% of patients, mainly in relation to the incisors and significantly more prevalent among males.

CONCLUSIONS

The use of CBCT significantly increases the possibility of clearly identifying these anatomical structures. The differences found between patients highlight the importance of carrying out an exhaustive radiological study of the individual to prevent complications, such as Schneiderian membrane perforation, neurovascular damage or bleeding during surgery.

Sinus Mucosal Damage Triggered by Synthetic or Xenogeneic Bone Substitutes: A Histological Analysis in Rabbits

Background: It has been shown in rabbit models that the sinus mucosa in contact with graft particles might experience a progressive thinning and perforations. The phenomenon depends on the graft used. Hence, the aim of the present study was to compare the damaging effects of a synthetic of a xenogeneic graft. Methods: Forty New Zealand rabbits received a bilateral sinus elevation. Both sinuses of twenty rabbits were grafted with a biphasic 60% hydroxyapatite and 40% β-tricalcium phosphate while the other twenty received a deproteinized bovine bone mineral graft. Thinned sites (<40 µm) and perforations on the mucosa in contact with graft particles were evaluated after 2 and 10 weeks (ten animals each period). The width of the pseudostratified epithelium was also measured as control. Results: After 2 weeks of healing, 61 thinned sites were detected in the Synthetic group and 49 in the Xenogeneic group. After 10 weeks, the number of thinned mucosae increased to 79 sites in the Synthetic group (p = 0.222 between periods), and to 114 sites in the Xenogeneic group (p = 0.030 between groups; p = 0.001 between periods). Perforations were few in the 2-week period, two in two sinuses out of 20 in the Synthetic group, and four in two sinuses out of 20 in the Xenogeneic group (p = 0.721). In the 10-week period, the perforations increased to eight in the Synthetic group, distributed in six sinuses out of 20, and to sixteen in the Xenogeneic group, distributed in 11 sinuses out of 20 (p = 0.082). The pseudostratified epithelium presented a reduced width at the thinned sites. Conclusions: The contact with synthetic or xenogeneic grafts will induce thinning and possible perforations of the sinus mucosa. This effect will increase over time, and it is stronger at the xenogeneic than the synthetic graft.

Contribution to Bone Formation of the Schneiderian Membrane after Sinus Augmentation: A Histological Study in Rabbits

AIM

to evaluate bone formation in close contact with the sinus mucosa after different periods from sinus augmentation and the influence on healing of the presence of an inward dis-placed bone window.

MATERIAL AND METHODS

Eighteen rabbits were included in the experiment. A trap-door technique was applied at the test sites, and the bony window was elevated inward (inward window; IW) together with the sinus mucosa. At the control sites, the bony window was removed before the elevation of the sinus mucosa. The elevated space was filled with deproteinized bovine bone mineral (DBBM) and both access windows were covered with a collagen membrane. Histometric measurements were performed subjacent the sinus mucosa after 2, 4, and 8 weeks of healing.

RESULTS

Very few sinuses presented small percentages of new bone in close contact with the sinus mucosa in the various period examined. The presence of bone in the neighbor areas might have influenced bone formation close to the sinus mucosa. The inward displaced bone window supported bone formation close to the sinus mucosa only in the earliest period of healing, while the bone walls increased their influence over time. The lack of increased new bone percentage over time in the most central regions of the elevated sinus mucosa do not support the hypothesis that the sinus mucosa may express its potential in bone formation. It can be speculated that the new bone found in the intermediate and middle regions of the control sites in the earliest period of healing might be due to residual of bone from the osteotomy.

CONCLUSIONS

Very small amounts of new bone were found subjacent to the sinus mucosa, mostly formed from the bone walls, the inward displaced bone window or from possible bone residues from the osteotomy procedures. The lack of increased new bone percentage over time in the most central regions of the elevated sinus mucosa indicates that the contribution to bone formation provided by the sinus mucosa is limited.

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)).

Buccal bone thickness of posterior mandible for microscrews implantation in molar distalization

BACKGROUND

This study explored the inter-radicular space and buccal bone thickness of the posterior mandibular region to provide an appropriate miniscrew insertion site for lower dentition distalization.

METHODS

The cone-beam computed tomographic (CBCT) records of 63 subjects were collected. Buccal bone thickness (BBT) was measured at four sections: (I) the root of the second premolar(P₁); (II) the mesial root of the first molar(P₂); (III) the distal root of the first molar(P₃); (IV) the mesial root of the second molar(P₄). The narrowest inter-radicular space of the four sections was also detected. Both BBT and inter-radicular space were measured at 4 height levels, 2, 4, 6 and 8mm from the alveolar ridge.

RESULTS

The largest BBT was observed at the mesial root of the second molar at 6 and 8mm, demonstrating a thickness of 6.77±2.50mm and 7.46±1.94mm, respectively. It provided sufficient coverage for mini-implants inserted 10°-30° oblique to the root. Therefore, during distalization of the mandibular dentition, roots have sufficient space to bypass the inclined mini-implants on the lingual side, avoiding miniscrew-root contact. The width between the mesiodistal roots of the first molar was the smallest, showing 1.53±0.69mm and 2.13±0.65mm at 4 and 6mm. Miniscrews implanted in this region had an increased risk of root proximity.

CONCLUSIONS

The most appropriate insertion site at the mandibular buccal shelf was the mesial point of the second molar at 6-8mm from the alveolar ridge, and an insertion angle of 10°-30° was recommended to avoid miniscrew-root contact. CBCT analysis is recommended before implantation due to individual differences.

Clinical and Histological Healing after Maxillary Sinus Floor Elevation

Sinus floor elevation is a surgical procedure that allows for the insertion of the implant in the posterior region of the maxilla in case of insufficient volume of native bone. Several studies have reported a high success rate, and this has helped to spread this surgical procedure around the world. The subject has been extensively studied and this could lead researchers to think that no new scientific evidence can be provided. However, new ideas and discoveries show that research never reaches a conclusion, and that new information can be added all the time. This collection aimed to provide new evidence that could be added to daily clinical work and to provide new ideas for future research.

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.

Radiographic Analysis of Graft Dimensional Changes in Transcrestal Maxillary Sinus Augmentation: A Retrospective Study

Background. The maxillary sinus lift is a popular and predictable technique associated with implant-supported rehabilitation of the severely atrophic maxilla. The aim of the present retrospective study was to investigate the effectiveness of transcrestal maxillary sinus augmentation and the graft resorption pattern using different heterologous bone substitutes. Methods. A total of 75 sinus-grafting procedures were performed and 89 implants were placed in 66 patients, 24 males and 42 females, with mean age 67.9 ± 10.64 years (range 43−84 years). Nineteen subjects were smokers. The mean follow-up period was 93.33 ± 54.71 months (range 14−240 months). Clinical and radiographical evaluations were performed. Graft height and width were measured at baseline and at the latest follow-up. Results. Mesiodistal and vertical resorption averaged 9.3 ± 20.7% (standard deviation), and 5.04 ± 9.9% of the postoperative size, respectively, considering the graft as the unit. Linear regression analysis showed that graft resorption in both the vertical and the mesiodistal dimension is independent of the follow-up time. Conversely, there was a trend for greater resorption when increasing the postoperative graft size, in both vertical (p = 0.001) and horizontal (p = 0.007) dimensions. When grouping the dimensional changes by graft particle size (only small (<300 μm) particles, combination of small and medium (>500 μm)/large (>1000 μm) particles, and only medium/large particles), there was a trend for greater resorption associated with smaller particles, but it was not significant; neither in the mesiodistal nor in the vertical dimension (p = 0.17 and p = 0.25, respectively). No implant was lost during the observation period. In conclusion, the transcrestal technique for maxillary sinus augmentation documented a high level of predictability. The low clinical morbidity and the contextual dental implant positioning is clinically useful in relation to a significant reduction of the time required for implant restoration, a consistent decrease of the number of surgical phases, and a cost-effectiveness approach for the rehabilitation. The graft resorption pattern in all cases was compatible with persistent implant protection and support.

Influence of the Use of a Collagen Membrane Placed on the Bone Window after Sinus Floor Augmentation-An Experimental Study in Rabbits

BACKGROUND

We studied the influence on healing of a resorbable membrane covering the osteotomy site after maxillary sinus grafting, evaluated in different regions of the augmented area.

METHODS

Maxillary sinus augmentation was performed in 24 New Zealand rabbits. Osteotomy, 4 × 6 mm, were performed bilaterally. A collagenated cortico-cancellous porcine bone was used to fill the elevated region. A collagen membrane was randomly placed over the osteotomy site on one side (MG), and the other side was left uncovered (NMG). The animals were euthanized after 2, 4, and 8 weeks; and histomorphometric analysis was performed in eight different regions.

RESULTS

New bone percentages were similar in both groups. There were no statistically significant differences. In MG, the overall percentages were 15.6 ± 7.3%, 22.9 ± 6.1%, and 24.9 ± 12.0% after 2, 4, and 8 weeks, respectively. In NMG, the percentages were 11.2 ± 4.5%, 24.1 ± 5.7%, and 24.5 ± 15.7%, respectively. The proportions of new bone in the various regions after 8 weeks were 31 ± 8.9% and 29.9 ± 9.1% in the bone walls region, 25 ± 10.1% and 32.8 ± 9.1% in the submucosa region, 22.6 ± 21.6% and 10.9 ± 11.5 in the middle region, 17.3 ± 14% and 13.4 ± 9.8% in the close-to-window region, and 21.8 ± 11.6%, 19.1 ± 6.4% in the osteotomy region-for MG and NMG, respectively.

CONCLUSIONS

In both groups the greatest amounts of bone formation occurred near to the pre-existing bone walls, followed by the sub-mucosa region. The smallest amounts were found in the close-to-window region, followed by the central region. The placement of a collagen membrane to cover the osteotomy site did not influence the amount of new bone formation after sinus grafting.

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

PURPOSE

To analyze the sinus membrane perforation (SMP) rate and its potential risk factors during lateral window maxillary sinus floor elevation (LSFE).

MATERIALS AND METHODS

For patients with LSFEs at Department of Implantology, Stomatology Hospital, School of Medicine, Zhejiang Universitiy during January 2014 to December 2020, patient-related risk factors (age/sex/smoking habit), surgery-related risk factors (operator experiment/number of tooth units/technique of osteotomy/surgical approach), and maxillary sinus-related risk factors (residual bone height/sinus membrane thickness/lateral wall thickness/maxillary sinus contours/presence of septa/blood vessels at the lateral maxillary sinus wall) were compared between perforated and nonperforated sites and were evaluated for their influence affecting SMP.

RESULTS

The study sample comprised 278 LSFE procedures in 278 patients; a total of 47 LSFE procedures (16.91%) presented SMP. Four significant factors were identified: smoking habit (p < 0.001), thin (≤1.5 mm) sinus membrane (p = 0.027), maxillary sinus contours (p < 0.001), and presence of septa (p = 0.001). The SMP rate of irregular, narrow tapered, and tapering sinus contours was significantly higher than that of ovoid and square one (p < 0.05).

CONCLUSION

In general, smoking habit, thin sinus membrane, irregular, narrow tapered, and tapering sinus contours, and presence of septa may increase the risk of SMP during LSFE.

Prevalence of maxillary sinus septa: systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to determine the prevalence and characteristics of maxillary sinus septa using cone beam computed tomography and computed tomography data. Publications were searched until October 5, 2020 in three electronic databases. Additionally, article bibliographies were searched, and authors were contacted if required. This review has been registered in PROSPERO (CRD42019124933). Two independent evaluators assessed methodological quality using the Joanna Briggs Institute levels of evidence; inter-rater reliability tests were performed (Cohen's κ). The prevalence of maxillary sinus septa was expressed as a proportion; differences according to sex were reported in terms of the odds ratio (OR) and 95% confidence interval (95% CI). Heterogeneity and sources of heterogeneity were evaluated by meta-regression. Publication bias was assessed by visual analysis of the funnel plot. Statistical significance was set at P < 0.05. The 62 studies identified and included in the review involved 13,701 patients (22,460 sinuses). The meta-analysis of 35 studies (14,664 sinuses) revealed an overall mean sinus septa prevalence per sinus of 33.2% (95% CI 27.8-38.5%; I² = 98.32%). The meta-analysis of 42 studies (9631 patients) found an overall mean sinus septa prevalence per patient of 41.0% (95% CI 36.0-46.0%, I² = 96.45%). The OR for the difference in septa prevalence between sexes was 0.785 (95% CI 0.590-1.046; P = 0.098, I² = 73.24%). Septa were most frequent in the middle area of the sinus and with a transverse orientation (86.0%). Within the limitations, the results suggest a high proportion of septa in the sinus, commonly in the middle area, which can interfere with the success of sinus floor elevation required for implant rehabilitation.

A Reliable Surgical Procedure for Sinus Floor Augmentation with Antral Pseudocysts

An antral pseudocyst (AP) is a common well-defined ‘dome-shaped’ faintly radiopaque lesion of the maxillary sinus, and usually does not require treatment in asymptomatic patients. However, when sinus floor augmentation is required to increase bone volume for implant installation, the elevation of the sinus mucosa might drive the AP against the ostium. This might cause its obstruction and, as possible consequence, sinusitis. The purpose of this study was to investigate the clinical and tomographic conditions of APs to identify a predictable cyst removal that might allow a safety sinus floor augmentation. A total of 52 maxillary sinuses in 46 patients (mean age 55.1 years) presenting AP were examined by cone beam computed tomographies (CBCTs). A two-stage approach was applied. At the first surgery, the cystic lesions were further inspected by an endoscope through the antrostomy, and histopathological diagnosis of the removed tissues was carried out. After the confirmation of decrease of the swelling of sinus membrane by CBCT, the sinus floor augmentation was performed, at least four months after cyst removal. The color and transparency of the 86 cystic lesions were classified into 4 types. The whitish transparent cysts were 34 (39.5%), the yellowish transparent cysts were 18 (20.9%), the dark purple transparent cysts were 8 (9.3%) and the milky-white opaque cysts were 26 (30.2%). The contents of the 60 (69.8%) transparent cysts were serous fluid, but those of milky-white cysts were composed of viscous or elastic soft tissues, and the aspiration of the contents was unsuccessful. The analysis of the preoperative CBCT did not provide certainty on the contents of the cystic lesions. All cystic lesions were diagnosed as AP, and an infection was identified in one AP, presenting marked infiltration of the inflammatory cells. Considering the difficulties of performing a correct diagnosis of the AP content by a CBCT analysis, the risk of failure of the surgery that creates severe afflictions to the patients, and the necessity of a histological evaluation of the cyst, a two-stage surgery appeared to be the most reliable procedure.

Staged Sinus Floor Elevation Using Novel Low-Crystalline Carbonate Apatite Granules: Prospective Results after 3-Year Functional Loading

The aim of this study was to evaluate clinical outcomes of staged sinus floor elevation (SFE) using novel low-crystalline carbonate apatite (CO₃Ap) granules. Patients who needed SFE for implant placement were recruited into this clinical trial. A staged procedure (lateral window technique using CO₃Ap granules, followed by implant placement after 7 ± 2 months) was employed in 13 patients. Bone-height increase and insertion torque values (ITVs) were assessed along with histological evaluation. The survival and success rates of 3-year functioning implants were also evaluated. Mean of bone-height increase after SFE using CO₃Ap granules was 7.2 ± 2.5 mm and this increase allowed implant placement in all cases (17 implants). Mean of ITV was 25.1 ± 13.2 Ncm and primary stability was achieved successfully in all cases. Histological analyses revealed mature new bone formation (36.8 ± 17.3%) and residual CO₃Ap granules (16.2 ± 10.1%) in the compartment after SFE. The survival and success rates after 3-year functional loading were 100% and no complications were found. These results clearly indicate the clinical usefulness of CO₃Ap granules for SFE.

Argon Bioactivation of Implants Installed Simultaneously to Maxillary Sinus Lifting without Graft. An Experimental Study in Rabbits

Background: The treatment of the surface of titanium implants with argon plasma improved its hydrophilicity and cell adhesion, resulting in higher bone apposition on implant and graft surfaces. The spontaneous perforation over time of the sinus mucosa after sinus augmentation has been documented in experimental studies at both implants and graft particles. The aim of the present study was to evaluate the influence of plasma argon treatment of the implant surface on bone apposition and on the rate of sinus mucosa perforations. Methods: A sinus lifting procedure was performed bilaterally in sixteen rabbits, and implants, either treated with argon plasma or left without treatment (control), were placed simultaneously without grafts. After 8 weeks, histological analyses were carried out. Results: A collapse of the sinus mucosa was observed at all implants. Twenty-four out of thirty-two implants presented sinus mucosa perforations at the apex. Several perforations were also found at the threads. Thinned mucosa sites (width < 40 µm) were found around almost all implants. About 2.6–2.9 mm of the apical regions of the implant did not present signs of osseointegration and about 1.3 mm were exposed to the sinus cavity. No statistically significant differences were found between plasma and control sites. Conclusions: In conclusion, the sinus mucosa was damaged and perforated by direct contact with treated and non-treated implant surfaces. The treatment of the implant surface with argon plasma did not affect the outcomes.

Sinus Mucosa Thickness Changes and Ostium Involvement after Maxillary Sinus Floor Elevation in Sinus with Septa. A Cone Beam Computed Tomography Study

Background: A thickening of the sinus mucosa is observed after sinus floor augmentation. The objective of this retrospective study was to evaluate the influence of the presence of septa in the dimensional variation and ostium involvement over time of the Schneiderian mucosa after sinus floor augmentation. Materials and Methods: Fifteen sinuses with septa (septa group) and 15 without (control group) were selected. CBCTs taken before surgery, and were analyzed after 1 week and after 9 months. Schneiderian membrane thickness changes over time and involvement of the ostium were evaluated. Results: Four perforations occurred in the septa group and none in the control group. After 1 week of healing, the sinus mucosa thickness increased in height by 5.7 mm and 7.1 mm in the septa and control groups, respectively. In this period, the patency of the ostium decreased in both groups, and three infundibula were obstructed in the septa group, and five in the control group. The mucosa was thicker and the edema was closer to the ostium in the control compared to in the septa group. After 9 months of healing, the dimensions regressed to normal pattern and no obstruction of the infundibula were observed. No statistically significant differences were found between septa and control groups. Conclusions: after one week of healing, the sinus mucosa increased in dimensions in both septa and control groups. However, the sinus mucosa presented a tendency of being thicker and closer to the ostium, resulting in a higher number of infundibula obstructions, in the control group compared to in the septa group. After 9 months, the sinus mucosa regressed to normal dimensions and no obstructions of the infundibula were observed in any group.

Influence of Anatomical Parameters on the Dimensions of the Subantral Space and Sinus Mucosa Thickening after Sinus Floor Elevation. A Retrospective Cone Beam Computed Tomography Study

BACKGROUND

Various anatomical parameters might influence the surgical approach for maxillary sinus floor elevation. The objective of the present study was to retrospectively evaluate the influence of anatomical parameters on the dimensions of the subantral space and of the sinus mucosa thickening after sinus floor elevation.

MATERIAL AND METHODS

Seventy-eight maxillary sinuses in sixty-five patients were evaluated on cone beam computed tomographies taken before surgery and after one week (t1w) and nine months (t9m). Several parameters such as the distance XF between an axis parallel to the base of the nose (X-axes) and the sinus floor (F) were correlated with the height gain (IF) at t1w and t9m and the post-surgical edema.

RESULTS

A weak significant positive correlation was observed between height gain vs. sinus height of interest (XF), the balcony, and the sinus floor angle. The post-surgical edema was influenced by the initial mucosa thickness and the xenograft used.

CONCLUSIONS

Various parameters might affect height gain and sinus mucosa thickening after sinus floor elevation. The height of interest, the balcony, and the sinus floor angle showed significant correlations with height gain. The initial thickness of the mucosa and the biomaterial used influenced the post-surgical edema.

Maxillary Sinus Augmentation Using Ceramic Alloplastic Granules or Paste: An Experimental Study in Rabbits

BACKGROUND

Due to the lack of data comparing the biological behavior of two formulations, granules and paste, of alloplastic graft from microtomographic and histomorphometric points of view, the aim of the present experiment was to compare the histomorphometric and microtomographic healing of two formulations, i.e., granules (MR sites) or paste (MR-inject sites) of an alloplastic graft composed of a combination of beta-tricalcium phosphate and hydroxyapatite used for maxillary sinus lifting.

METHODS

A sinus lifting procedure was carried out bilaterally in 20 rabbits, and the elevated space was filled with either paste or granules of an alloplastic material. A collagen membrane was placed on the antrostomy and the animals were euthanized after 2 or 10 weeks, 10 animals each group. Microtomographic and histological analyses were performed.

RESULTS

Higher proportions of new bone formation were found at the MR, compared to the MR-inject sites both after 2 weeks (2.65 ± 2.89% vs. 0.08 ± 0.12%; p < 0.01) and 10 weeks of healing (34.20 ± 13.86 vs. 23.28 ± 10.35%; p = 0.022).

CONCLUSIONS

It was concluded that new bone formation was faster in the MR sites, compared to the MR-inject. However, a longer time of healing should be allowed to make final conclusions about the efficiency in bone formation of the paste formulation of the biomaterial used in the present study.

Three-dimensional CBCT based evaluation of the inferior part of the maxillary sinus: Retrospective Study

The maxillary sinus is the largest of the four paranasal sinuses in humans, and its close proximity to the teeth means that caution is required during dental treatment. In particular, implant surgeries involving the maxillary posterior teeth should include evaluating the inferior part of the maxillary sinus. The purpose of this study is to evaluate the differences by comparing the inferior part of the maxillary sinus based on the nasal cavity floor (NCF) between patients (male 30, female 30) genders through the use of the three-dimensional (3-D) program that can facilitate 3-D visualizations. The present study results obtained from 3-D visualizations using cone beam computed tomography (CBCT) data showed that the inferior part of the maxillary sinus was mostly larger in males than in females. In addition, the utilization of 3-D visualization data was more likely to assure accuracy than when using data obtained by two-dimensional (2-D) imaging. Therefore, 3-D visualizations of the inferior part of the maxillary sinus will contribute to accurate analyses of its anatomical structure during implant surgery and other operations. Further studies utilizing 3-D visualization will yield useful fundamental data and guidelines for future research.

Involvement of the maxillary sinus ostium (MSO) in the edematous processes after sinus floor augmentation: a cone-beam computed tomographic study

Background

After sinus floor augmentation, a thickening of the sinus mucosa has been described. The aim of the present study was to evaluate the involvement of the maxillary sinus ostium in the edematous processes after a sinus floor augmentation procedure.

Methods

Seventy-two cone-beam computerized tomographies (CBSTs) were taken before sinus floor augmentation and after 1 week and 9 months from surgery and analyses. Sinus mucosa thickness and area, ostium diameter and patency, and extension of the post-surgical transient mucosal thickening in relation to the ostium were evaluated on the CBCTs for all three periods. The term “virtual” when referring to sinus mucosa thickness and area was introduced because of the edema and bleeding that both contributed to a transient thickening and additional elevation of the sinus mucosa.

Results

The mean virtual thickness of the sinus mucosa was 2.7 ± 4.0 mm, 7.7 ± 7.1 mm, 1.7 ± 2.0 mm before surgery, and after 1 week and 9 months. The virtual mucosa area was 37.2 ± 52.5 mm², 184.5 ± 153.8 mm², and 34.0 ± 50.7 mm². The ostium diameter at the three periods evaluated was 1.8 ± 0.5 mm, 1.1 ± 0.6 mm, 1.5 ± 0.8 mm, respectively. Three infundibula (4.2%) were found out of patency before surgery while this number increased to 14 (19.4%) after 1 week. Nine months after surgery, only one infundibulum (1.4%) was out of patency, however, without presenting signs of sinus pathologies. The extension of the mucosal edema on the palatal sinus was reduced after 9 months of healing.

Conclusions

One week after sinus floor augmentation, the maxillary sinus mucosa increased in dimensions and in several cases involved the ostium, reducing its diameter and producing a transient loss of patency. After 9 months of healing, the initial conditions were recovered.