Evaluating the effect of rapamycin treatment in Alzheimer's disease and aging using in vivo imaging: the ERAP phase IIa clinical study protocol.

BACKGROUND: Rapamycin is an inhibitor of the mechanistic target of rapamycin (mTOR) protein kinase, and preclinical data demonstrate that it is a promising candidate for a general gero- and neuroprotective treatment in humans. Results from mouse models of Alzheimer's disease have shown beneficial effects of rapamycin, including preventing or reversing cognitive deficits, reducing amyloid oligomers and tauopathies and normalizing synaptic plasticity and cerebral glucose uptake. The "Evaluating Rapamycin Treatment in Alzheimer's Disease using Positron Emission Tomography" (ERAP) trial aims to test if these results translate to humans through evaluating the change in cerebral glucose uptake following six months of rapamycin treatment in participants with early-stage Alzheimer's disease. METHODS: ERAP is a six-month-long, single-arm, open-label, phase IIa biomarker-driven study evaluating if the drug rapamycin can be repurposed to treat Alzheimer's disease. Fifteen patients will be included and treated with a weekly dose of 7 mg rapamycin for six months. The primary endpoint will be change in cerebral glucose uptake, measured using [18F]FDG positron emission tomography. Secondary endpoints include changes in cognitive measures, markers in cerebrospinal fluid as well as cerebral blood flow measured using magnetic resonance imaging. As exploratory outcomes, the study will assess change in multiple age-related pathological processes, such as periodontal inflammation, retinal degeneration, bone mineral density loss, atherosclerosis and decreased cardiac function. DISCUSSION: The ERAP study is a clinical trial using in vivo imaging biomarkers to assess the repurposing of rapamycin for the treatment of Alzheimer's disease. If successful, the study would provide a strong rationale for large-scale evaluation of mTOR-inhibitors as a potential disease-modifying treatment in Alzheimer's disease. TRIAL REGISTRATION: ClinicalTrials.gov ID NCT06022068, date of registration 2023-08-30.

Low-dose, standard, and high-resolution cone beam computed tomography for alveolar bone measurements related to implant planning: An ex vivo study in human specimens.

AIM: To evaluate the performance of low-dose cone beam computed tomography (CBCT) protocols with regard to linear bone measurements in the posterior mandible for implant planning compared with higher dose protocols. MATERIALS AND METHODS: Forty-two edentulous posterior sites in human cadaveric mandibles were imaged in three CBCT scanners using three or four protocols with varying exposure parameters to achieve lower dose. Co-registration was performed to generate sagittal and cross-sectional image sections representative of the implant site. Three observers measured bone height, from the alveolar crest to the mandibular canal, and width, three mm from the top of the alveolar crest. Intra- and interobserver reproducibility were assessed for the cases rated as nonmeasurable as well as for completed measurements. The measurements were analyzed using paired t-tests for differences among the CBCT protocols and the frequency distribution of nonmeasurable cases with a Pearson Chi-square test. RESULTS: Reproducibility for registering nonmeasurable cases varied among observers; however, no consistent significant differences were found in the frequency distribution of these cases among observers, units, and protocols. Intraclass correlation coefficients (ICC) were >0.9 for all measurements of bone height and width. Mean differences of <0.5 mm were found regardless of protocol; however, one observer did in some cases produce larger differences. CONCLUSION: Linear bone measurements did not differ significantly and could be performed with excellent reliability, using low-dose CBCT protocols compared with standard and high-resolution ones. Varying approaches for rating nonmeasurable cases were found, indicating differences in diagnostic strategies related to implant planning among observers.

Jawbone measurements of edentulous sites related to implant planning using magnetic resonance imaging compared to cone beam computed tomography: An ex vivo study.

AIM: To compare measurements on images obtained by magnetic resonance imaging (MRI) and cone beam CT (CBCT) for height, width, and area in alveolar bone sites in human jaw specimens. MATERIAL AND METHODS: Forty edentulous alveolar posterior sites in human cadaver specimens were imaged using CBCT scanners, and with zero-echo-time MRI (ZTE-MRI). Semi-automatic volume registration was performed to generate representative coronal sections of the sites related to implant planning. ZTE-MRI sections were also presented after grayscale inversion (INV MRI). Three observers measured bone height, bone width 5 mm from the alveolar crest, and bone area stretching from the width measurement to the top of the alveolar crest in the images. Interobserver agreement was assessed by intra-class correlation coefficients (ICC). The measurements were analyzed using two-way repeated measures ANOVA factoring observer and image type. RESULTS: ICC was >0.95 for bone height, width, and bone area. No significant differences among observers (p = 0.14) or image type (p = 0.60) were found for bone height. For bone width, observer (p = 0.14) was not a significant factor, while ZTE-MRI produced width estimates that were significantly different and systematically smaller than CBCT-based estimates (p ≤ 0.001). Observer (p = 0.06) was not a significant factor regarding the bone area measurements, contrary to the imaging type where ZTE-MRI led to significantly smaller area estimates than CBCT (p ≤ 0.001). CONCLUSION: Bone height measurements were essentially equivalent using CBCT and MRI. This was found regardless of grayscale choice for the MRI. However, ZTE-MRI resulted in smaller estimates of bone width and area.

Accuracy of linear measurements for implant planning based on low-dose cone beam CT protocols: a systematic review and meta-analysis.

OBJECTIVES: The aim of this systematic review was to verify the accuracy of linear measurements performed on low-dose CBCT protocols for implant planning, in comparison with those performed on standard and high-resolution CBCT protocols. METHODS: The literature search included four databases (Pubmed, Web of Science, Embase, and Scopus). Two reviewers independently screened titles/abstracts and full texts according to eligibility criteria, extracted the data, and examined the methodological quality. Risk of bias assessment was performed using the Quality Assessment Tool For In Vitro Studies. Random-effects meta-analysis was used for pooling measurement error data. RESULTS: The initial search yielded 4684 titles. In total, 13 studies were included in the systematic review, representing a total of 81 samples, while 9 studies were included in the meta-analysis. The risk of bias ranged from medium to low. The main results across the studies indicate a strong consistency in linear measurements performed on low-dose images in relation to the reference methods. The overall pooled planning measurement error from low-dose CBCT protocols was -0.24 mm (95% CI, -0.52 to 0.04) with a high level of heterogeneity, showing a tendency for underestimation of real values. Various studies found no significant differences in measurements across different protocols (eg, voxel sizes, mA settings, or dose levels), regions (incisor, premolar, molar) and types (height vs. width). Some studies, however, noted exceptions in measurements performed on the posterior mandible. CONCLUSION: Low-dose CBCT protocols offer adequate precision and accuracy of linear measurements for implant planning. Nevertheless, diagnostic image quality needs must be taken into consideration when choosing a low-dose CBCT protocol.

Accuracy and reliability of magnetic resonance imaging in orthodontic diagnosis and treatment planning-a systematic review and meta-analysis.

BACKGROUND: Magnetic resonance imaging (MRI) is a non-ionizing imaging technique. Using MRI in dentistry may potentially lower the general radiation dose of the examined population, provided MRI can replace various radiation-based images. Furthermore, novel MRI imaging modalities for three-dimensional and two-dimensional cephalometrics have recently been developed for orthodontic diagnosis. OBJECTIVES: This systematic review aimed to determine the diagnostic accuracy and reliability of MRI in orthodontic diagnosis and treatment planning. SEARCH METHODS: An electronic search was conducted on 20 November 2022 in the following databases: PubMed, LILACS, Web of Science, EMBASE, Scopus, and Cochrane. The search was updated on 30 August 2023. Furthermore, a grey literature search was performed in Google Scholar and Open-Grey. SELECTION CRITERIA: This review included descriptive, observational, cohort studies, cross-sectional, case-control studies, and randomized/non-randomized trials related to the research question. The study excluded studies related to patients with syndromes, chronic diseases, craniofacial anomalies, or bone diseases. DATA COLLECTION AND ANALYSIS: The included studies were quality assessed using the "Joanna Brigg's Critical Appraisal Tool for diagnostic test accuracy". The GRADE approach for non-randomized studies was used for strength-of-evidence analysis. RESULTS: Eight of the 10 included studies compared MRI with either cone beam computed tomography or lateral cephalogram and found a high intra- and inter-rater agreement for landmark identification. The risk of bias was high in four studies, moderate in three, and low in three studies. Homogeneity was lacking among the included studies in terms of MRI imaging parameters and sample characteristics. This should be taken into consideration by future studies where uniformity with respect to these parameters may be considered. CONCLUSIONS: Despite dissimilarity and heterogeneity in the sample population and other methodological aspects, all the included studies concluded that MRI enjoyed considerable intra- and inter-examiner reliability and was comparable to current diagnostic standards in orthodontics. Furthermore, the studies agreed on the innovative potential of MRI in radiation-free diagnosis and treatment planning in orthodontics in the future. REGISTRATION: CRD number: CRD420223XXXXX.

The current role and future potential of digital diagnostic imaging in implant dentistry: A scoping review.

OBJECTIVES: Diagnostic imaging is crucial for implant dentistry. This review provides an up-to-date perspective on the application of digital diagnostic imaging in implant dentistry. METHODS: Electronic searches were conducted in PubMed focusing on the question 'when (and why) do we need diagnostic imaging in implant dentistry?' The search results were summarised to identify different applications of digital diagnostic imaging in implant dentistry. RESULTS: The most used imaging modalities in implant dentistry include intraoral periapical radiographs, panoramic views and cone beam computed tomography (CBCT). These are dependent on acquisition standardisation to optimise image quality. Particularly for CBCT, other technical parameters (i.e., tube current, tube voltage, field-of-view, voxel size) are relevant minimising the occurrence of artefacts. There is a growing interest in digital workflows, integrating diagnostic imaging and automation. Artificial intelligence (AI) has been incorporated into these workflows and is expected to play a significant role in the future of implant dentistry. Preliminary evidence supports the use of ionising-radiation-free imaging modalities (e.g., MRI and ultrasound) that can add value in terms of soft tissue visualisation. CONCLUSIONS: Digital diagnostic imaging is the sine qua non in implant dentistry. Image acquisition protocols must be tailored to the patient's needs and clinical indication, considering the trade-off between radiation exposure and needed information. growing evidence supporting the benefits of digital workflows, from planning to execution, and the future of implant dentistry will likely involve a synergy between human expertise and AI-driven intelligence. Transiting into ionising-radiation-free imaging modalities is feasible, but these must be further developed before clinical implementation.

The influence of smoking on the incidence of peri-implantitis: A systematic review and meta-analysis.

OBJECTIVE: The aim of this study was to systematically analyze the influence of smoking on the incidence of peri-implantitis. MATERIALS AND METHODS: The search was performed in the National Library of Medicine (MEDLINE-PubMed), SCOPUS, EMBASE, and ISI Web of Science databases (finished on November 30, 2022). Systematic review and meta-analysis were conducted according to PRISMA statement. Prospective cohort studies that evaluate the incidence of peri-implantitis in smokers and non-smokers were included. Two authors independently searched for eligible studies, screened titles, and abstracts, did the full-text analysis, extracted data, and performed the risk-of-bias assessment. The results were summarized through random-effects meta-analyses. The GRADE method was used to determine the certainty of evidence. RESULTS: A total of 7 studies with 702 patients and 1959 implants were included for analysis. The meta-analysis revealed a significant difference between smokers and non-smokers for the risk of peri-implantitis in the implant-based (p < .0001) and patient-based analysis (p = .003). A strong association between smoking and the risk for peri-implantitis was verified at the implant level (RR: 2.04, 95% CI: 1.46-1.85) and the patient level (RR: 2.79, 95% CI: 1.42-5.50). CONCLUSIONS: Moderate certainty evidence suggests that smoking is associated with peri-implantitis compared to non-smoking at the patient and implant levels.

Definition of the Region of Interest for the Assessment of Alveolar Bone Repair Using Micro-computed Tomography.

The objective of this study was to evaluate the influence of the extraction socket (distal or lingual root) and the type of region of interest (ROI) definition (manual or predefined) on the assessment of alveolar repair following tooth extraction using micro-computed tomography (micro-CT). The software package used for scanning, reconstruction, reorientation, and analysis of images (NRecon®, DataViewer®, CT-Analyzer®) was acquired through Bruker < https://www.bruker.com > . The sample comprised the micro-CT volumes of seven Wistar rat mandibles, in which the right first molar was extracted. The reconstructed images were analyzed using the extraction sockets, i.e., the distal and intermediate lingual root and the method of ROI definition: manual (MA), central round (CR), and peripheral round (PR). The bone volume fraction (BV/TV) values obtained were analyzed by two-way ANOVA with Tukey's post hoc test (α = 5%). The distal extraction socket resulted in significantly lower BV/TV values than the intermediate lingual socket for MA (P = 0.001), CR (P < 0.001), and PR (P < 0.001). Regarding the ROI, when evaluating the distal extraction socket, the BV/TV was significantly higher (P < 0.001) for MA than for CR and PR, with a lower BV/TV for CR. However, no significant difference was observed for MA (P = 0.855), CR (P = 0.769), or PR (P = 0.453) in the intermediate lingual extraction socket. The bone neoformation outcome (BV/TV) for alveolar bone repair after tooth extraction is significantly influenced by the ROI and the extraction socket. Using the predefined method with a standardized ROI in the central region of the distal extraction socket resulted in the assessment of bone volume, demonstrating the most critical region of the bone neoformation process.

Artificial Intelligence for Detecting Cephalometric Landmarks: A Systematic Review and Meta-analysis.

Using computer vision through artificial intelligence (AI) is one of the main technological advances in dentistry. However, the existing literature on the practical application of AI for detecting cephalometric landmarks of orthodontic interest in digital images is heterogeneous, and there is no consensus regarding accuracy and precision. Thus, this review evaluated the use of artificial intelligence for detecting cephalometric landmarks in digital imaging examinations and compared it to manual annotation of landmarks. An electronic search was performed in nine databases to find studies that analyzed the detection of cephalometric landmarks in digital imaging examinations with AI and manual landmarking. Two reviewers selected the studies, extracted the data, and assessed the risk of bias using QUADAS-2. Random-effects meta-analyses determined the agreement and precision of AI compared to manual detection at a 95% confidence interval. The electronic search located 7410 studies, of which 40 were included. Only three studies presented a low risk of bias for all domains evaluated. The meta-analysis showed AI agreement rates of 79% (95% CI: 76-82%, I2 = 99%) and 90% (95% CI: 87-92%, I2 = 99%) for the thresholds of 2 and 3 mm, respectively, with a mean divergence of 2.05 (95% CI: 1.41-2.69, I2 = 10%) compared to manual landmarking. The menton cephalometric landmark showed the lowest divergence between both methods (SMD, 1.17; 95% CI, 0.82; 1.53; I2 = 0%). Based on very low certainty of evidence, the application of AI was promising for automatically detecting cephalometric landmarks, but further studies should focus on testing its strength and validity in different samples.

Alveolar bone measurements in magnetic resonance imaging compared with cone beam computed tomography: a pilot, ex-vivo study.

OBJECTIVES: To compare alveolar bone height and width measurements from zero-echo-time MRI (ZTE-MRI) and cone beam CT (CBCT), in human specimens. MATERIAL AND METHODS: Twenty posterior edentulous sites in human cadaver specimens were imaged with CBCT and ZTE-MRI. Bone height and width at 1, 3, 5, 7 and 9 mm from the top of the alveolar ridge was measured by two trained observers in cross-sections of a site where an implant was to be planned. Twenty percent of the sample was measured in duplicate to assess method error and intra-observer reproducibility (ICC). The differences between CBCT and ZTE-MRI measurements were compared (t-test). RESULTS: Inter- and intra-observer reproducibility was >0.90. The method error (average between observers) for bone height was 0.45 mm and 0.39 mm, and for bone width (average) was 0.52 mm and 0.80 mm (CBCT and ZTE-MRI, respectively). The majority of the bone measurement differences were statistically insignificant, except bone width measurements at 5 mm (p ≤ .05 for both observers). Mean measurement differences were not larger than the method error. CONCLUSION: ZTE-MRI is not significantly different from CBCT when comparing measurements of alveolar bone height and width.

Incidence of peri-implant disease associated with cement- and screw-retained implant-supported prostheses: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Implant-supported fixed dental prostheses can be cement- or screw-retained on the implant or abutment, with advantages and disadvantages for each method. Cemented prostheses have been associated with peri-implant disease because cement remnants act as a reservoir for bacteria and hinder biofilm control. However, contrasting evidence has been presented regarding this association based on studies with varying designs, and a systematic review and meta-analysis is required. PURPOSE: The purpose of this systematic review and meta-analysis was to answer the focused question: In patients who received implant-supported prostheses, is the incidence of peri-implant diseases higher in cemented implant-supported prostheses than in screw-retained ones? MATERIAL AND METHODS: The search was conducted using the National Library of Medicine (MEDLINE-PubMed), SCOPUS, EMBASE, and ISI Web of Science databases. Randomized clinical trials (RCTs) that assessed the incidence of peri-implant disease in cement- and screw-retained prostheses were included. Two authors independently screened the titles and abstracts, and analyzed the full texts, extracted data, and assessed the risk of bias. The findings were summarized using meta-analyses with random effects, and the level of certainty of the evidence was determined using the grading of recommendations, assessments, development, and evaluations (GRADE) approach. RESULTS: The search yielded 4455 articles that met the inclusion criteria based on the title and/or abstract selection. A total of 6 RCTs were included for analysis. The meta-analysis revealed no significant difference between cement- and screw-retained prostheses for the risk of peri-implant mucositis (RR: 1.36, 95% CI: 0.42-4.38, P=.61). Similarly, no significant difference was observed between cement- and screw-retained prostheses for the incidence of peri-implantitis (RR: 1.00, 95% CI: 0.23-4.31, P=1.00). CONCLUSIONS: Moderate certainty evidence suggests that cement- and screw-retained prostheses present a similar risk for peri-implant mucositis and peri-implantitis.

Clinical outcomes of digital scans versus conventional impressions for implant-supported fixed complete arch prostheses: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: With the growing use of digital scanning, an evaluation of the clinical impact of digital scans versus conventional impressions in complete arch implant-supported prostheses is needed. However, systematic reviews on this subject are lacking. PURPOSE: The purpose of this systematic review was to evaluate the scanning and impression times and the radiographic marginal bone loss over time associated with digital scans and conventional impressions for complete arch implant-supported fixed prostheses. MATERIAL AND METHODS: The search was performed in MEDLINE/PubMed, SCOPUS, EMBASE, and Web of Science. Only randomized clinical trials (RCTs) comparing digital scans and conventional impressions for complete arch prostheses were included in the review. The scan and impression times and marginal bone loss were analyzed through random effects meta-analysis. RESULTS: Six RCTs were included. The meta-analysis was conducted by using a standardized mean difference (MD) and indicated a statistically significant reduction in time for the digital scan group compared with the conventional group (MD 10.01 [7.46, 12.55], P<.001, I²=80%). The fact that digital scans were used did not lead to significant differences in radiographic marginal bone loss compared with conventional impressions after 6 months (MD -0.03 [-0.14, 0.08], P=.58, I²=0%), after 12 months (MD -0.06 [-0.24, 0.12], P=.12, I²=45%), and after 24 months (MD -0.12 [-0.32, 0.09], P=.28, I²=58%). CONCLUSIONS: Digital scans significantly reduced the time required compared with conventional impressions for complete arch implant-supported prostheses. Nevertheless, additional studies with more consistent methodologies are needed for confirmation. No significant differences were found in radiographic marginal bone loss between treatments performed with digital scans and conventional impressions.

Effect of osseodensification on the increase in ridge thickness and the prevention of buccal peri-implant defects: an in vitro randomized split mouth pilot study.

BACKGROUND: Implant installation with conventional drilling can create buccal bone defects in areas of limited ridge thickness. Implant installation with osseodensification may aid in preventing buccal bone defects in these situations. This in vitro pilot study evaluated the impact of osseodensification on the increase in alveolar ridge thickness and the prevention of buccal peri-implant defects. METHODS: Ten fresh pig mandibles with limited bone thickness were selected for use in an experimental randomized split mouth pilot study. Two site-preparation protocols were used: conventional drilling with cutting burs (CTL, n = 10) and osseodensification with Densah® burs (OD, n = 10). After implant bed preparation, 20 implants (4.5 × 10 mm) were placed in the prepared sites and the insertion torque was recorded. Clinical and photographic analysis evaluated ridge thickness and the extent (height, width, and area) of bone defects in the buccal and lingual bone walls following implant placement. Three-dimensional measurements were performed using STL files to analyze the increase in buccal ridge thickness following site preparation and implant placement. The height of the buccal bone defect was considered as the primary outcome of this study. Defect width, area, implant insertion torque, and linear buccal ridge increase after implant site preparation and installation were also assessed. Non-parametric evaluations were carried out with the Mann-Whitney test to verify intergroup differences. RESULTS: There was no statistically significant difference between groups in the baseline ridge thickness. OD presented a significantly higher insertion torque, associated with reduced buccal and lingual bone defect width, in comparison to CTL. CONCLUSIONS: The increase in buccal ridge thickness after site preparation and implant placement was significantly higher in OD compared to CTL. Osseodensification increased the ridge thickness through expansion and reduced buccal bone defects after implant installation.

Stability of mandibular implants with Morse taper and external hexagon connections placed under immediate loading: a longitudinal clinical study.

The aim of this study was to compare the longitudinal stability of implants with Morse taper and external hexagon connections placed in the anterior mandible and subjected to immediate functional loading. Nine patients each received 4 mandibular implants placed between the mental foramina. In each patient, 2 implants on the left side of the arch had Morse taper prosthetic connections, and 2 implants on the right side had external hexagon prosthetic connections. Mandibular overdentures and opposing removable complete dentures were placed within 72 hours after implant surgery. Clinical evaluation of the implants via magnetic transduction resonance frequency analysis was performed immediately following surgery and 3 months, 6 months, and 2 years following surgery to obtain the implant stability quotient (ISQ). The data obtained were parametric according to the Kolmogorov-Smirnov normality test. The lowest ISQ of any implant was approximately 67, representing reliable osseointegration. The only statistically significant difference between the 2 types of prosthetic connection was found in the initial period (immediately following surgery), when the external hexagon connection in the distal position presented greater stability than did the Morse taper connection in the same position on the opposite side (P < 0.05; Student t test). In intragroup comparisons, no statistically significant differences were found regarding the positions of the implants in the mandible. When the different follow-up periods were evaluated, there were statistically significant differences only in the external hexagon group, with significant reductions in stability of both mesial and distal implants at 6 months compared to other time periods (P < 0.05; Tukey test). Within the limitations of the study, it can be concluded that both Morse taper and external hexagon prosthetic connections provide good stability in an immediate functional loading protocol.

Fully versus conventionally guided implant placement by dental students: A randomized controlled trial.

OBJECTIVE: To compare fully guided with conventionally guided implant surgery performed by dental students in terms of deviation of actual implant position from an ideal implant position. MATERIALS AND METHODS: Twenty-five patients in need of 26 straightforward implant-supported single crowns were randomly allocated to a fully guided (FG, n = 14) or a conventionally guided (CG, n = 12) implant surgery. In the preoperative CBCTs, 3 experienced investigators placed a virtual implant in the ideal position, twice, allowing deviational analysis in the facio-lingual (coronal) and mesio-distal (sagittal) planes for 7 parameters. Facio-lingual crestal deviation, facio-lingual apical deviation, facio-lingual angular deviation, mesio-distal crestal deviation, mesio-distal apical deviation, mesio-distal angular deviation, and vertical deviation between the ideal, virtually placed position and actual implant position for the FG and CG groups were compared statistically (p < .05). RESULTS: Statistically significant differences between ideal and actual implant position were only seen for the facio-lingual apical deviation (p = .047) and for the facio-lingual angular deviation (p = .019), where the CG group deviated more from the ideal position than the FG group. The 5 other examined variables did not show any significant differences, and none of the implants in the FG group and CG group were placed in conflict with the clinical guidelines. CONCLUSIONS: The present study reported no difference in 5 out of 7 deviational parameters concerning actual implant position in relation to ideal implant position between a FG and CG implant placement protocol performed by dental students. Facio-lingual angular deviation and apical deviation were lower, when a FG protocol was followed. All implants were positioned according to clinical guidelines.

Radiographic changes in height and volume after lateral GBR procedures with different ratios of deproteinized bovine bone mineral and autogenous bone at different time points. An experimental study.

OBJECTIVE: Estimate changes in augmentation height and volume after lateral guided bone regeneration (GBR) augmentation with different ratios of deproteinized bovine bone mineral (DBBM) and particulate autogenous bone (PAB) and autogenous bone block (ABB), at different time points. MATERIAL AND METHODS: Twenty-four minipigs were randomly allocated into three healing periods. Lateral augmentation in 96 sites with standardized quantity of graft material was performed with different ratios of DBBM and PAB (50:50, 75:25, and 100:0) and ABB in combination with DBBM, covered by a collagen membrane. Changes in augmentation height and volume were assessed on CT volumes acquired 10, 20, and 30 weeks after surgery. RESULTS: Reduction in bone augmentation height was as follows: 50:50-1.7 mm (-33.1%), 75:25-1.8 mm (-37.8%), 100:0-1.7 mm (-35.8%), and ABB - 0.2 mm (-3.7%), after 30 weeks. The augmentation height was significantly better preserved with ABB compared to 50:50, 75:25, and 100:0, while no significant difference was present among particulate grafts. No significant difference in volumetric reduction was found among 50:50, 75:25, 100:0 and ABB after 30 weeks, while 100:0 presented significant less reduction compared to 50:50, 75:25 and ABB after 10 and 20 weeks. CONCLUSIONS: Augmentation height following GBR was better preserved with ABB covered with DBBM. Addition of PAB to DBBM did not affect the changes in height of the graft. The volumetric stability seems to be comparable for ABB covered by DBBM and all particulate grafts after 30 weeks. However, DBBM alone revealed significant less volume reduction in the early healing phase.

Effect of a formalin-based fixation method on bone mineral content in human ex-vivo specimens.

OBJECTIVE: Histopathology of formalin-fixated human ex-vivo specimens may be used as reference standard for evaluation of diagnostic index tests like CBCT or MRI. The aim was to estimate changes in bone mineral content (BMC) over time in human ex-vivo bone specimens fixated in a formalin-based solution for 24 h followed by storage in an alcohol-based medium for six months, assessed by dual-energy X-ray absorptiometry (DXA). METHODOLOGY: Bone specimens (n = 19) from human ex-vivo mandibles donated for science were included. BMC was measured by DXA before fixation (D0), after 24 h of immersion fixation in a formalin-based solution (D1), and hereafter every 30 days (M1-M6) during storage in a 30% ethanol-based storage medium for 6 months. Changes in BMC from D0 to D1 and from D0 to M6 were calculated and mean change in BMC estimated. RESULTS: Mean change in BMC from D0 to D1 was -0.73% (95% CI -1.75%; 0.29%), and from D0 to M6 -1.19% (95% CI -2.14%; -0.23%). CONCLUSIONS: No changes in BMC of ex-vivo human bone specimens were found after 24 h formalin-based immersion fixation. After six months storage in an ethanol-based medium, BMC mean loss of 1% was detected. In this range, changes in BMC are not clinically relevant.

Sella Turcica Area and Location of Point Sella in Cephalograms Acquired with Simulated Patient Head Movements.

AIM AND OBJECTIVE: This study assesses changes in the sella turcica area (STA) and location of the cephalometric point sella (S) on lateral cephalograms acquired by charge-coupled device (CCD)-based cephalostats with and without simulated patient head movements. MATERIALS AND METHODS: A real skull was placed on a robot, able to simulate four head movements (anteroposterior translation/lifting/nodding/lateral rotation) at three distances (0.75/1.5/3 mm) and two patterns (returning to 0.5 mm away from the start position/staying at maximum movement excursion). Two ProMax-2D cephalostats (Dimax-3, D-3 or Dimax-4, D-4), and an Orthophos-SL cephalostat (ORT) acquired cephalograms during the predetermined movements ("cases," 48 images/unit) and without movement ("controls," 24 images/unit). Three observers manually traced the contour of sella turcica and marked point sella using a computer mouse. STA was calculated in pixels2 by dedicated software based on the tracing. S was defined by its x and y coordinates recorded by the same software in pixels. Ten percent of the images were assessed twice. The difference between cases and controls (case minus control) for the STA and S (namely Diff-STA and Diff-S) was calculated and assessed through descriptive statistics. RESULTS: Inter- and intraobserver agreement ranged from moderate to good for STA and S. Diff-STA ranged from -42.5 to 12.9% (D-3), -15.3 to 9.6% (D-4), and -25.3 to 39.9% (ORT). Diff-S was represented up to 50% (D-3), 134% (D-4), and 103% (ORT) of the mean sella turcica diameter in control images. CONCLUSION: Simulated head movements caused significant distortion in lateral cephalograms acquired by CCD-based cephalostats, as seen from STA and S alterations, depending on the cephalostat. CLINICAL SIGNIFICANCE: Patient-related errors, including patient motion artifacts, are influential factors for the reliability of cephalometric tracing.

Odontogenic Myxoma: Systematic review and bias analysis.

BACKGROUND: Odontogenic myxoma (OM) is a rare neoplasm, which originates from odontogenic ectomesenchyme. There is no study in the literature that analyses the best standards for OM diagnosis and how the treatment modalities may influence the recurrence rates. OBJECTIVE: To evaluate the best standards for odontogenic myxoma (OM) diagnosis and treatment, and how these may influence the recurrence rates. STUDY DESIGN: Two independent researchers performed a systematic review in many databases. Fifty-two eligible studies were included for qualitative analysis. Bias analysis was conducted according to Oxford Centre for Evidence-Based Medicine. RESULTS: A total of 1363 OM cases were reported on, and female gender with average age of 27 years is the most common patient profile. Conventional microscopic findings were observed in 93.43% of the reported cases. In 57.49% of the cases, multilocular radiographic appearance was present, followed by unilocular appearance (32.87%). Posterior mandible was the site with the major prevalence, while surgical resection was the most common treatment modality, followed by enucleation. Recurrence rates for both treatment modalities were approximately close (13.04% and 25.0%, respectively). CONCLUSION: The correct diagnosis of OM relies on the association of clinical, radiographic and microscopic findings. About imaging examinations, panoramic radiography and computed tomography are sufficient for the evaluation of OM. Recurrence rates were closely among the two most used surgery treatments. So according to some clinical-radiological aspects, conservative surgery may be preferred than aggressive surgery modalities.

Histology of augmented autogenous bone covered by a platelet-rich fibrin membrane or deproteinized bovine bone mineral and a collagen membrane: A pilot randomized controlled trial.

OBJECTIVES: This study aimed to evaluate histologic and histomorphometric bone characteristics with a focus on vitality after lateral alveolar ridge augmentation using an autogenous bone graft as a block covered by either a platelet-rich fibrin (PRF) membrane (test group) or a standard procedure involving coverage of the bone block with a deproteinized bovine bone mineral and a resorbable collagen membrane (control group). MATERIAL AND METHODS: A total of 27 (test = 14, control = 13) partially edentulous patients with indication for bone block augmentation before implant installation were included. For analyses, a biopsy of augmented bone was retrieved six months after bone grafting. RESULTS: Histologic evaluation of augmented bone revealed a predominance of non-vital bone toward the periosteum and few localized areas of vital bone in the center of the graft in both groups. In contrast, augmented bone toward the native bone demonstrated extensive bone remodeling in both groups. Histomorphometric analyses demonstrated a mean of 14% vital bone, 80% non-vital bone, 5% soft tissue, and 1% blood vessels in the test group. In the control group, the corresponding shares were 14% vital bone, 63% non-vital bone, 22% soft tissue, and 1% blood vessels. We observed no significant differences between the groups (p > .05). CONCLUSION: In conclusion, a comparable low bone vitality of augmented bone was observed in the PRF and in the control group. Consequently, the present study could not verify the potential beneficial effect of a PRF membrane on bone vitality of an autogenous bone graft used as a block.