Maxillary Sinus and Surrounding Bone Anatomy With Cone Beam Computed Tomography After Multiple Teeth Loss: A Retrospective Multicenter Clinical Study

Radiographic Outcomes of Transcrestal Sinus Floor Elevation With RBH ≤ 5 mm: Non-Perforation and Laterally Repaired Cases

OBJECTIVE

This study aimed to compare the clinical effects of implants placed in sites with a transcrestal sinus floor elevation (TSFE) featuring a residual bone height (RBH) of ≤ 5 mm, without Schneiderian membrane perforations, to those in sites where a lateral window approach was utilized to repair perforations that occurred during TSFE.

METHODS

A total of 104 implants in 80 patients (80 sinuses) with RBH ≤ 5 mm who had undergone TSFE with simultaneous implant placement were included in this retrospective study. The implants were categorized into two groups based on whether the Schneiderian membrane was perforated, and the lateral window technique for sinus floor elevation (LSFE) was utilized to repair perforations that occurred during the TSFE procedure. The early implant loss, endo-sinus bone gain (ESBG), and implant apical bone resorption (ABR) were used to assess new bone formation between the non-perforated and the perforated groups.

RESULTS

The non-perforation group consisted of 89 implants in 69 patients (69 sinuses), whereas the perforated group included 15 implants in 11 patients (11 sinuses). No early implant loss or postoperative complications were observed in either group during the first 6 months following implant installation. The ESBG was (5.83 ± 2.06) mm for the non-perforation group and (7.76 ± 1.63) mm for the perforation-repaired group (p < 0.001). A linear mixed model indicated that group (β = 2.41, 95% CI = 1.49, 3.33, p < 0.001) and RBH (β = -0.53, 95% CI = -0.80, -0.27, p < 0.001) significantly influenced ESBG. The ABR between the non-perforation and perforated group has no statistically significant difference (β = 0.84, 95% CI = -0.41, 2.08, p = 0.185).

CONCLUSION

Repairing Schneiderian membrane perforations that occur during TSFE in cases with RBH ≤ 5 mm, using the lateral window technique, leads to ideal internal radiographic bone augmentation volume maintenance in the maxillary sinus compared to cases without perforation; no significant difference in early implant loss was observed.

TRIAL REGISTRATION

Clinical Trial Registry: (ChiCTR2200062886).

Comprehensive sinus contour classification and its characteristics from radiographic examination: a cross-sectional study

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.

CONCLUSION

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.

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.

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.

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.

Radiological changes in maxillary sinus morphology after lateral sinus floor augmentation

&lt;b&gt;Background:&lt;/b&gt; Restoration of the masticatory function in patients with edentulous posterior maxilla is often challenging due to the severe atrophy of the alveolar ridges and proximity of the maxillary sinus, resulting in insufficient bone quantity for implant-supported dentures. &lt;br&gt;&lt;b&gt;Aim:&lt;/b&gt; The purpose of this study was to analyze the changes in Schneiderian membrane thickness after lateral sinus floor augmentation (LSFA) using cone beam computed tomography (CBCT). &lt;br&gt;&lt;b&gt;Material and methods:&lt;/b&gt; WLSFA procedures using different bone grafting materials were performed in 87 patients, operated on in two clinical institutions from 2016 to 2018. CBCT examination was performed in all patients before the LSFA procedure, at 1 month after surgery, and after 6 months, before implant placement or loading. &lt;br&gt;&lt;b&gt;Results: &lt;/b&gt;Minor r adiological changes in mucous membrane morphology were observed preoperatively in 17.1% of patients. Postoperative CBCT in the early postsurgical period demonstrated that the number of intact non-specific sinuses decreased significantly, i.e. from 86.7% to 26.7%. The number of cases with local hypertrophia of the mucous membrane increased from 20.3% to 26.7%. Mucosal thickening was observed in 41.7% vs 7.5%. The number of intact sinuses increased to 57.8%. The number of cases with local membrane hypertrophia also increased - to 37.4%. The number of cases with mucosal thickening or fluid accumulation decreased significantly to 11.8 and 5.3% respectively. In 2 cases the development of chronic sinusitis required secondary surgeries. &lt;br&gt;&lt;b&gt;Conclusion:&lt;/b&gt; The present retrospective study revealed that minor radiological changes in the morphology of the maxillary sinus mucosa were observed preoperatively in 17.1% of patients who underwent LSFA procedures. In the early and late postoperative period their frequency increased to 68.5% and 47.1%, respectively. However, the clinical signs of sinusitis developed only in 19.26% of patients. No significant correlations were found between the frequency and severity of postoperative radiological changes and residual bone height, sinus anatomy, initial state of the mucous membrane and type of the grafting material.

Radiological changes in maxillary sinus morphology after lateral sinus floor augmentation

<b>Background:</b> Restoration of the masticatory function in patients with edentulous posterior maxilla is often challenging due to the severe atrophy of the alveolar ridges and proximity of the maxillary sinus, resulting in insufficient bone quantity for implant-supported dentures. <br><b>Aim:</b> The purpose of this study was to analyze the changes in Schneiderian membrane thickness after lateral sinus floor augmentation (LSFA) using cone beam computed tomography (CBCT). <br><b>Material and methods:</b> W LSFA procedures using different bone grafting materials were performed in 87 patients, operated on in two clinical institutions from 2016 to 2018. CBCT examination was performed in all patients before the LSFA procedure, at 1 month after surgery, and after 6 months, before implant placement or loading. <br><b>Results:</b> Minor r adiological changes in mucous membrane morphology were observed preoperatively in 17.1% of patients. Postoperative CBCT in the early postsurgical period demonstrated that the number of intact non-specific sinuses decreased significantly, i.e. from 86.7% to 26.7%. The number of cases with local hypertrophia of the mucous membrane increased from 20.3% to 26.7%. Mucosal thickening was observed in 41.7% vs 7.5%. The number of intact sinuses increased to 57.8%. The number of cases with local membrane hypertrophia also increased – to 37.4%. The number of cases with mucosal thickening or fluid accumulation decreased significantly to 11.8 and 5.3% respectively. In 2 cases the development of chronic sinusitis required secondary surgeries. <br><b>Conclusion:</b> The present retrospective study revealed that minor radiological changes in the morphology of the maxillary sinus mucosa were observed preoperatively in 17.1% of patients who underwent LSFA procedures. In the early and late postoperative period their frequency increased to 68.5% and 47.1%, r espectively. However, the clinical signs o f sinusitis developed only in 19.26% of patients. No significant correlations were found between the frequency and severity of postoperative radiological changes and residual bone height, sinus anatomy, initial state of the mucous membrane and type of the grafting material.

Factors influencing the sinus membrane thickness in edentulous regions: a cone-beam computed tomography study

BACKGROUND

During implant treatment in the maxillary molar area, maxillary sinus floor augmentation is often performed to ameliorate the reduced alveolar bone height attributable to bone remodeling and pneumatization-induced expansion of the maxillary sinus. However, this augmentation may cause complications such as misplaced implants, artery damage, and maxillary sinus mucosal perforation; infections like maxillary sinusitis; and postsurgical complications such as bone graft leakage and postoperative nasal hemorrhaging. To reduce the complications during maxillary sinus floor augmentation and postoperative infections, we performed retrospective investigations of various systemic and local factors that influence pre-operative sinus mucosal thickness (SMT) by using cone-beam computed tomography (CBCT). Subjects included patients who underwent maxillary sinus floor augmentation in an edentulous maxillary molar area with a lateral approach. Pre-operative SMT, existing bone mass, and nasal septum deviation were measured using CBCT images. Relationships between SMT and the following influencing factors were investigated: (1) age, (2) sex, (3) systemic disease, (4) smoking, (5) period after tooth extraction, (6) reason for tooth extraction, (7) residual alveolar bone height (RBH), (8) sinus septa, and (9) nasal septum deviation. Correlations were also investigated for age and RBH (p < 0.05).

RESULTS

We assessed 35 patients (40 sinuses; 11 male, 24 female). The average patient age was 58.90 ± 9.0 years (males, 57.9 ± 7.7 years; females, 59.9 ± 9.4 years; age range, 41-79 years). The average SMT was 1.09 ± 1.30 mm, incidence of SMT > 2 mm was 25.0%, incidence of SMT < 0.8 mm was 50.0%, and the average RBH was 2.14 ± 1.02 mm. The factors that influenced SMT included sex (p = 0.0078), period after tooth extraction (p = 0.0075), reason for tooth extraction (p = 0.020), sinus septa (p = 0.0076), and nasal septum deviation (p = 0.038).

CONCLUSIONS

Factors associated with higher SMT included male sex, interval following tooth extraction < 6 months, periapical lesions, sinus septa, and nasal septum deviation. Factors associated with SMT > 2 mm were sex and reason for tooth extraction, while factors associated with SMT < 0.8 mm were time following tooth extraction and nasal septum deviation. Despite the limitations of this study, these preoperative evaluations may be of utmost importance for safely conducting maxillary sinus floor augmentation.