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.

The impact of methylene blue photosensitizer, aPDT and a calcium hydroxide-based paste on the physicochemical and mechanical characteristics of root canal dentin and the bonding interface of fiberglass posts

PURPOSE

To investigate the influence of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) and calcium hydroxide (CH) medication on the mechanical characteristics, degree of conversion (DC), quantification, and volume of gaps at the adhesive interface of glass fiber posts (GFPs) luted to distinct thirds of root canal dentin. Additionally, the microhardness (MH), elastic modulus (Eit), morphology, and chemical structure of the intraradicular dentin were assessed.

MATERIALS AND METHODS

6 experimental groups were formed by sorting 102 bovine incisors. Canals receiving deionized water irrigation as a negative control; canals receiving deionized water irrigation and filled with CH as a positive control; groups treated with CH + MB at 50 and 100 mg/L without irradiation; and groups treated with CH + MB at 50 and 100 mg/L irradiated by red laser for 60 s (660 nm; 100 mW; 6.5 J; 72 J/cm2). MH, Eit, and DC properties were evaluated for both the resin cement layer and root dentin substrate (n = 8). Volume and quantification of gaps at the bonding interface (n = 6), and dentin morphology and chemical content were investigated (n = 3). Data were analyzed using a repeated-measures 2-way ANOVA followed by Tukey post hoc analysis (α = 0.05).

RESULTS

The distinct intraradicular thirds and treatment with MB-mediated aPDT, whether activated or not, in combination with CH, had a significant impact on the mechanical characteristics of the root dentin. This effect was also observed in the MH, Eit, DC, quantification, and volume of gaps at the luting interface (P < .05). In general, a higher concentration of MB, whether activated by a red laser or not, led to lower values in the mechanical properties of the root dentin, as well as in MH, Eit, and DC at the adhesive interface (P < .05). Additionally, these groups exhibited higher values for quantification and volume of gaps at the luting substrate (P < .05). Scanning electron micrographs and energy dispersive X-ray spectra showed qualitative similarity among all groups, except for the negative experimental control group.

CONCLUSIONS

MB-mediated aPDT at 50 mg/L, in combination with CH, demonstrated favorable physico-chemical and mechanical characteristics in intraradicular dentin, along with satisfactory mechanical features and the adhesive interface integrity for GFPs at all intraradicular depths.

CLINICAL SIGNIFICANCE

MB-mediated aPDT at a concentration of 50 mg/L combined to CH medication represents a suitable choice for photosensitization in the context of intracanal disinfection following the biomechanical procedure and prior to luting of intraradicular restorations.

Endo-sinus bone gain following sinus membrane elevation without graft compared with sinus floor augmentation and a composite graft: a one-year single-blind randomized controlled trial

The objective of this study was to assess endo-sinus bone gain (ESBG) and bone density (BD) following maxillary sinus membrane elevation without graft (test) compared with maxillary sinus floor augmentation and 1:1 ratio of autogenous bone from the buccal antrostomy and deproteinized porcine bone mineral (control) using two- and three-dimensional radiographic methods. Forty healthy patients were randomly allocated to the test and control groups. Cone beam computed tomography scans were obtained at enrolment (T0), immediately after surgery (T1), at delivery of the prosthetic rehabilitation (T2), and 1 year after functional implant loading (T3). Mean differences were expressed with the 95% confidence interval. Significance was set at ≤ 0.05. ESBG and BD were significantly higher in the control group than test group at T1, T2, and T3 (P < 0.001). A significant decrease in ESBG and increase in BD was observed from T1 to T3 with both treatments (P < 0.001). There was a non-significant positive correlation of ESBG with implant protrusion length and non-significant negative correlation with residual bone height. In conclusion, test was associated with significantly lower ESBG and BD compared with control. However, the lower ESBG and BD did not appear to negatively affect the implant stability quotient or implant treatment outcome after 1 year of functional implant loading.

Surveying the landscape of diagnostic imaging in dentistry's future: Four emerging technologies with promise

BACKGROUND

Advances in digital radiography for both intraoral and panoramic imaging and cone-beam computed tomography have led the way to an increase in diagnostic capabilities for the dental care profession. In this article, the authors provide information on 4 emerging technologies with promise.

TYPES OF STUDIES REVIEWED

The authors feature the following: artificial intelligence in the form of deep learning using convolutional neural networks, dental magnetic resonance imaging, stationary intraoral tomosynthesis, and second-generation cone-beam computed tomography sources based on carbon nanotube technology and multispectral imaging. The authors review and summarize articles featuring these technologies.

RESULTS

The history and background of these emerging technologies are previewed along with their development and potential impact on the practice of dental diagnostic imaging. The authors conclude that these emerging technologies have the potential to have a substantial influence on the practice of dentistry as these systems mature. The degree of influence most likely will vary, with artificial intelligence being the most influential of the 4.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The readers are informed about these emerging technologies and the potential effects on their practice going forward, giving them information on which to base decisions on adopting 1 or more of these technologies. The 4 technologies reviewed in this article have the potential to improve imaging diagnostics in dentistry thereby leading to better patient care and heightened professional satisfaction.

Accuracy of linear measurements for implant planning based on low-dose Cone Beam CT protocols: a systematic review and meta-analysisAccuracy of low-dose CBCT: 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 4,684 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 (e.g., 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.

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.

Dental-dedicated MRI, a novel approach for dentomaxillofacial diagnostic imaging: technical specifications and feasibility

MRI is a noninvasive, ionizing radiation-free imaging modality that has become an indispensable medical diagnostic method. The literature suggests MRI as a potential diagnostic modality in dentomaxillofacial radiology. However, current MRI equipment is designed for medical imaging (eg, brain and body imaging), with general-purpose use in radiology. Hence, it appears expensive for dentists to purchase and maintain, besides being complex to operate. In recent years, MRI has entered some areas of dentistry and has reached a point in which it can be provided following a tailored approach. This technical report introduces a dental-dedicated MRI (ddMRI) system, describing how MRI can be adapted to fit dentomaxillofacial radiology through the appropriate choice of field strength, dental radiofrequency surface coil, and pulse sequences. Also, this technical report illustrates the possible application and feasibility of the suggested ddMRI system in some relevant diagnostic tasks in dentistry. Based on the presented cases, it is fair to consider the suggested ddMRI system as a feasible approach to introducing MRI to dentists and dentomaxillofacial radiology specialists. Further studies are needed to clarify the diagnostic accuracy of ddMRI considering the various diagnostic tasks relevant to the practice of dentistry.

Fluoride-modified implant surfaces improves osseointegration in the tibias of rats with induced diabetes

This study evaluated the influence of a fluoride-modified titanium surface on osseointegration in rats with induced diabetes. One hundred and eighty rats were randomly allocated into 3 groups with 60 animals each: Control group (C): Animals without diabetes; Diabetes Group (D): Animals with uncontrolled induced diabetes; Controlled Diabetes Group (CD): Animals with diabetes induced controlled by the insulin administration. Diabetes was induced by streptozotocin injection. Each animal received 2 implants in the proximal tibial metaphysis, one with the machined surface (M) and the other one with a fluoride-modified titanium surface (F), after 4 weeks of induction of diabetes. The animals were submitted to euthanasia 2, 4, and 6 weeks after the implant placement (n = 20 animals/group). The osseointegration was evaluated by the implant removal torque test and the histometric analysis of the non-decalcified histological sections: 1) Contact bone/implant (%BIC); 2) Bone tissue area between implant threads (%BBT). Implants with F surface showed a higher removal torque than implants with surface M in all groups. There was no difference in %BIC between the groups regardless of the surface used. The F surface showed a tendency to present higher %BBT values for the 3 evaluation periods in the D group. The fluoride-modified implant surface has no impact on the %BIC and %BBT. However, the fluoride-modified implant surface increases the locking of the implants with the bone. The hyperglycemia was associated with lower removal torque values despite the surfaces of the implant used.

Maxillary sinus membrane elevation and coagulum compared with maxillary sinus floor augmentation and a composite graft: A 1-year single-blinded randomized controlled trial

OBJECTIVE

The aim was to evaluate the 1-year implant outcome and patient-related outcome measures (PROMs) after maxillary sinus membrane elevation and coagulum (test) compared with maxillary sinus floor augmentation and a 1:1 ratio of autogenous bone graft from the buccal antrostomy and deproteinised porcine bone mineral (DPBM) (control).

MATERIALS AND METHODS

Forty patients (30 female, 10 male) with a mean age of 50 years (range 25-71 years) and an alveolar ridge height between 4 and 7 mm were randomly allocated to test or control. Outcome measures included survival of suprastructures and implants, implant stability quotient, health status of the peri-implant tissue, peri-implant marginal bone loss, frequency of complications and PROMs using Oral Health Impact Profile-14 combined with questionnaires assessing patient's perception of the peri-implant soft tissue, implant crown, function of the implant, and total implant treatment outcome using visual analogue scale. Mean differences were expressed with standard deviation and 95% confidence interval. Level of significance was 0.05.

RESULTS

All suprastructures and implants were well-functioning after 1-year of functional implant loading. No significant difference in any of the applied outcome measures was observed between test and control. Both treatments revealed high patient satisfaction scores and significant improvement in oral health-related quality of life.

CONCLUSION

There were no significant differences in implant outcome and PROMs between test and control, after 1-year of functional implant loading. Neither of the treatments can therefore be considered better than the other. Thus, long-term randomized controlled trials are needed before definitive conclusions can be provided about the two treatment modalities.

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.

Endo-sinus bone gain following osteotome-mediated sinus floor elevation with Bio-Oss Collagen compared with no grafting material: a one-year single-blind randomized controlled trial

The objective of this study was to assess endo-sinus bone gain (ESBG) following osteotome-mediated sinus floor elevation with Bio-Oss Collagen (test) compared with no grafting material (control) using two- and three-dimensional radiographic methods, as part of a randomized controlled trial (ClinicalTrials.gov, NCT04618900). Forty healthy patients who met the necessary eligibility criteria were allocated by block randomization to either the test group (20 patients) or control group (20 patients). Cone beam computed tomography scans were obtained at enrolment (T0), immediately after surgery (T1), at delivery of the prosthetic rehabilitation (T2), and 1 year after functional implant loading (T3). Mean differences were expressed with the 95% confidence interval; significance was set at P < 0.05. ESBG was significantly increased with Bio-Oss Collagen compared with no grafting material at T1, T2, and T3 (P < 0.001). A gradual decrease in ESBG was observed over time with both treatment modalities (P < 0.001), which diminished the difference between the test and control groups at T2 and T3. ESBG was observed to be positively correlated with implant protrusion length and negatively correlated with the residual bone height. In osteotome-mediated sinus floor elevation, the application of Bio-Oss Collagen underneath the elevated Schneiderian membrane improved ESBG significantly when compared with no grafting material. However, the increased ESBG seems not to have positively improved the treatment outcomes in terms of the implant stability quotient or the survival of the implants or suprastructures.

Effect of micro-CT acquisition parameters and individual analysis on the assessment of bone repair

This study aimed to investigate whether two acquisition parameters, voxel size and filter thickness, used in a micro-computed tomography (micro-CT) scan, together with the examiner's experience, influence the outcome of bone repair analysis in an experimental model. Bone defects were created in rat tibiae and scanned using two voxel sizes of 6- or 12-µm and two aluminum filter thickness of 0.5- or 1-mm. Then, bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) were analyzed twice by two groups of operators: experienced and inexperienced examiners. For BV/TV, no significant differences were found between scanning voxel sizes of 6 and 12 µm for the experienced examiners; however, for the inexperienced examiners, the analysis performed using a 12-µm voxel size resulted in higher BV/TV values (32.4 and 32.9) than those acquired using a 6-µm voxel size (25.4 and 24.8) (p < 0.05). For Tb.Th, no significant differences between the analyses performed by experienced and inexperienced groups were observed when using the 6-µm voxel size. However, inexperienced examiners' analysis revealed higher Tb.Th values when using the 12-µm voxel size compared with 6 µm (0.05 vs. 0.03, p < 0.05). Filter thickness had no influence on the results of any group. In conclusion, voxel size and operator experience affected the measured Tb.Th and BV/TV of a region with new bone formation. Operator experience in micro-CT analysis is more critical for BV/TV than for Tb.Th, whereas voxel size significantly affects Tb.Th evaluation. Operators in the initial phases of research training should be calibrated for bone assessments.

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.

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.

Magnetic resonance imaging in the diagnosis of periodontal and periapical disease

OBJECTIVES

Early pre-clinical inflammatory changes in periodontal and/or periapical lesions, which typically precede bone loss, are challenging to diagnose using ionizing-radiation-based imaging modalities. MRI provides relevant additional diagnostic information of inflammatory processes in soft and hard tissues. The aim of the present study is to undertake a systematic review of the literature on MRI in the diagnosis of periodontal and/or periapical disease.

METHODS AND MATERIALS

The PubMed/MEDLINE and Scopus bibliographic databases were searched (2000-2021) using the search string: ("MRI" or "magnetic resonance imaging") and ("periodontitis" or "periodontal" or "apical pathology" or "endodontic pathology" or "periapical" or "furcation" or "intrabony"). The search was limited to studies published in English. The studies were assessed independently by three reviewers, focusing on the MRI sequences, imaging modalities (radiographs, cone beam CT (CBCT), and MRI), disease definition, assessed parameters, and outcome measurements.

RESULTS

The search strategy yielded 34 studies, from which 13 were included. Overall, the findings of MRI were in agreement with CBCT. The studies showed that MRI provided diagnostic information of the hard and soft tissue components affected by periodontal and/or periapical disease with a fairly high sensitivity and specificity. However, the assessed parameters (e.g. MRI acquisition protocols, and disease definition) differed substantially.

CONCLUSIONS

The included studies indicate that the use of MRI in the diagnosis of periodontal and/or periapical disease is feasible and promising. More studies are needed to define the accuracy of this non-ionizing-radiation-based diagnostic modality, in the assessment of periodontal and/or periapical lesions.

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.

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.

Radiographic outcome after maxillary sinus floor augmentation with allogeneic adipose tissue-derived stem cells seeded on deproteinized bovine bone mineral. A randomized controlled experimental study

The objective was to test the hypothesis of no difference in radiographic outcome after maxillary sinus floor augmentation (MSFA) with allogeneic adipose tissue-derived stem cells (ASCs) seeded on deproteinized bovine bone mineral (DBBM) (test) compared with excipient on DBBM (control). Eighteen minipigs were assigned into three groups of six animals and euthanised after one month (T1), two months (T2), and four months (T3), respectively. Each maxillary sinus was randomly allocated to either test or control with an equal volume of graft. Computed tomography scans (CTs) after MSFA (T0) were compared with CTs after euthanasia to evaluate graft volume (GV) changes and bone density (BD) using three-dimensional measurements and Hounsfield units. GV was larger in test compared with control at T1 (P = 0.046), whereas GV was larger in control compared with test at T3 (P = 0.01). BD increased from T0 to T1-T3 (P < 0.001) with both treatments. Higher BD was observed in control compared with test at T3 (P = 0.01), while no significant difference was observed at T1 and T2. Conclusively, the present study demonstrate that allogeneic ASCs seeded on DBBM in conjunction with MSFA seemed not to improve the radiographic outcome compared with excipient on DBBM. However, radiological outcomes need to be supplemented by bone histomorphometry before definitive conclusions can be provided about the beneficial use of allogeneic ASCs seeded on DBBM in conjunction with MSFA compared with DBBM alone.

Influence of supracrestal tissue height on peri-implant hard and soft tissues of single implants placed in the esthetic areas using one abutment-one time approach: A pilot, prospective interventional study

OBJECTIVE

This pilot, prospective interventional study aimed to analyze the influence of supracrestal tissue height (STH) when using the one abutment-one time concept (OAOT) at the time of implant placement, on peri-implant hard and soft tissue remodeling in esthetic areas. The definitive crown was placed seven days later.

METHOD AND MATERIALS

Facial mucosal margin position (FMMP), mesial and distal papilla levels (MPL and DPL, respectively), and mesial and distal marginal bone loss (M-MBL and D-MBL, respectively) were assessed after seven days (placement of the definitive crown), and 1, 2, 3, 6 and 12 months after implant placement. Patients were classified according to the STH in thin (STH < 3 mm) and thick (STH ≥ 3 mm).

RESULTS

Fifteen patients fulfilled the eligibility criteria and were included in the study. Eight presented a thick STH and seven a thin STH. After 12 months, the implant success rate was 100%. The mean recession at FMMP was -0.47 ± 0.57 mm and -0.19 ± 0.41 mm in thin and thick groups, respectively (p = 0.29). The mean MPL recession was -0.19 ± 0.06 mm in the thin group and -0.01 ± 0.07 mm in the thick group (p < 0.01), and the mean DPL recession was -0.15 ± 0.09 mm in the thin group and 0.00 ± 0.15 mm in the thick group (p < 0.05). The mean bone loss was -0.21 ± 0.18 mm and -0.04 ± 0.14 mm in the thin and thick groups, respectively (p < 0.05).

CONCLUSION

Single maxillary anterior implants with thin supracrestal tissue height (< 3 mm) at the time of implant placement had greater bone loss and papillary recession than implants with a thick soft tissue height (≥ 3 mm), even when using the one abutment one time concept.

Magnetic resonance imaging artefacts caused by orthodontic appliances and/or implant-supported prosthesis: a systematic review

OBJECTIVES

Dental materials, including orthodontic appliances and implants, are commonly mentioned as a possible source of artefacts in magnetic resonance imaging (MRI). The aim of the present study was to undertake a systematic review of the relevant literature on MR image artefacts due to dental materials, limited to orthodontic appliances and implant-supported dental prosthesis, on both technical and diagnostic levels.

METHODS

The MEDLINE (PubMed) bibliographic database was searched up to September 2020. The search was limited to studies published in English, using the search string: (MRI or magnetic resonance) and (artefact or artifact) and (dental or ortho or implant or restoration or restorative). The studies were assessed independently by three reviewers, focusing on the following parameters: MRI sequences, tested materials, assessed parameters, efficacy level and outcome.

RESULTS

The search strategy yielded 31 studies, which were included in this systematic review. These studies showed that metallic dental materials, commonly present in orthodontic appliances and implant-supported dental prosthesis led to diverse types/severities of artefacts in MR images. Fifteen studies were in vivo, based on human subjects. The studies differed substantially in terms of tested materials, assessed parameters, and outcome measurements.

CONCLUSIONS

Metallic dental materials cause artefacts of diverse types and severities in MR images of the head and neck region. However, the diagnostic relevance of the investigated artefacts for the diverse MRI applications is yet to be studied.

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.

In vitro study on how photodynamic therapy and calcium hydroxide medication influence adhesive interface properties of glass-fiber posts to intraradicular dentin

PURPOSE

This in vitro study evaluated the influence of antimicrobial photodynamic therapy (aPDT), using methylene blue (MB) as photosensitizer (PS) and calcium hydroxide (CH) as intracanal medication on adhesive bond strength, sealing, and integrity of the luting interface of glass-fiber posts to different thirds of endodontically treated root canal dentin.

MATERIAL AND METHODS

102 incisors were sorted into 6 groups: a negative control irrigated with deionized water; a positive control irrigated with deionized water and filled with CH; CH + MB 50 mg/L without laser radiation; CH + MB 100 mg/L without laser radiation; CH + MB 50 mg/L radiated by red laser; and CH + MB 100 mg/L radiated by red laser. Push-out bond strength (n = 8), adhesive interface sealing (n = 3), and volume and quantification of voids (n = 6) were assessed using a universal testing machine, confocal laser scanning microscope, and computerized microtomography, respectively. Scanning electron micrographs were obtained from representative samples to qualify the fracture patterns. Push-out bond strength and adhesive interface integrity data were subjected to 2-way ANOVA for repeated measures followed by Tukey's test (α = 0.05). Adhesive interface sealing was evaluated by the inter-examiner Kappa test and submitted to Kruskal-Wallis and Dunns tests (α = 0.05).

RESULTS

Assessing the apical region, the positive control and MB_100WA + Ca(OH)₂ groups showed lower adhesive bond strength compared to the MB_100A + Ca(OH)₂ group (P < 0.05). The cervical third showed higher bond strength than the apical third for the positive control, MB_50WA + Ca(OH)_2, MB_100WA + Ca(OH)_2, and MB_50A + Ca(OH)₂ groups (P < 0.05). A prevalence of mixed failure was observed in all experimental groups. There were no statistically significant differences in adhesive interface sealing for any of the parameters assessed (P > 0.05). MB_100WA + Ca(OH)₂ and MB_100A + Ca(OH)₂ groups promoted a higher volume and quantification of voids compared to the negative control group evaluating the cervical third (P < 0.05). In general, there were no differences in the quantification of voids comparing the intraradicular thirds (P > 0.05), differently to the volume of voids in which, in general, the cervical third promoted higher values compared to the middle and apical thirds (P < 0.05).

CONCLUSION

aPDT with methylene blue PS at 50 mg/L associated with calcium hydroxide as intracanal medication demonstrated satisfactory bond strength, sealing, and integrity of the adhesive interface at any intraradicular depth.

Quantitative and qualitative comparisons of pulp cavity volumes produced by cone beam computed tomography and micro-computed tomography through semiautomatic segmentation: An ex vivo investigation

OBJECTIVE

The aim of this study was to measure the volume and visually assess 3-dimensional (3D) virtual models of pulp cavities obtained through semiautomatic segmentation on images from 6 cone beam computed tomography (CBCT) units compared with the reference standard of micro-CT.

STUDY DESIGN

Fifteen mandibular premolar teeth were scanned with 6 CBCT units: Prexion 3D Elite, i-CAT Next Generation, NewTom 5G, Cranex 3D, 3Shape X1, and Orthophos SL 3D, using the smallest available field of view and highest resolution settings. Pulp cavity volumes were quantitatively assessed by 2 calibrated examiners. The volumes from each CBCT unit were compared with micro-CT. Qualitative assessment of the 3D reconstructions was also performed. Repeated-measures analysis of variance and the Friedman test compared the CBCT reconstructions to micro-CT. Intra- and interexaminer agreements were calculated with the intraclass correlation coefficient and kappa statistic.

RESULTS

The CBCT-based volumes were all significantly larger than micro-CT (P ≤ .0061). Prexion, X1, and Orthophos provided the segmentations that most closely resembled the reference standard. Intra- and interexaminer agreements ranged from good to excellent for quantitative measurements. Interexaminer agreement for qualitative evaluation was substantial.

CONCLUSIONS

Semiautomatic segmentation of CBCT images is a feasible method to produce virtual 3D models of the pulp cavity. Prexion, X1, and Orthophos were the CBCT units that resulted in 3D reconstructions most similar to the reference standard.

A pilot study comparing optical coherence tomography, radiography, clinical photography, and polarisation microscopy for studies of hypomineralisation disturbances in enamel

Aim

To investigate the use of optical coherence tomography (OCT) as a tool to assess general and localised hypomineralisation defects in the enamel.

Design and Materials

Ten extracted permanent teeth (four teeth with localised hypomineralisation, four teeth with general hypomineralisation, and two healthy controls) were used in this study. In addition, four participants who underwent OCT served as living controls for the extracted teeth.

Methods

The OCT results were compared with clinical photographs, digital radiographs, and polarising microscopy images of tooth sections (considered the gold standard) to determine the method with the most accurate information regarding the extent of enamel disturbances: 1) visibility of enamel disturbance (visible yes/no); if yes, 2) extent of the disturbance in the enamel; and 3) determination of the plausible involvement of the underlying dentin.

Results

OCT was more accurate than digital radiography and visual assessment. OCT could provide information about the extent of localised hypomineralised disturbances in the enamel that was comparable to that with polarisation microscopy of the tooth sections.

Conclusion

Within the limitations of this pilot study, it can be concluded that OCT is suitable for investigating and evaluating localised hypomineralisation disturbances; however, it is less useful in cases with generalised hypomineralisation of the enamel. In addition, OCT complements radiographic examination of enamel; however, more studies are necessary to elucidate the full extent of the use of OCT in case of hypomineralisation.

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.

Impact of the COVID-19 Pandemic on the Oral Health Workforce: A Multicenter Study from the Southern Region of Brazil

The aim of this study was two-fold: (1) to describe the surveillance and biosafety measures adopted by dentists, dental hygienists, and dental assistants who worked in the Southern Region of Brazil and (2) to evaluate access to information in the context of the COVID-19 pandemic. This was a multicenter and cross-sectional design, using a self-applied and validated online questionnaire. The availability of health-care-related supplies and the adoption of biosafety measures recommended by the Technical Note of the National Health Surveillance Agency No. 04/2020 were analyzed. A total of 2560 Brazilian workers participated (75.8% dentists, 15.7% dental assistants and 8.5% dental hygienists), 52.7% from the public and 37.7% from the private sector. Approximately 70% of the individuals reported being away from work during the pandemic. The surveillance measures adopted with higher mean scores were the investigation of respiratory infection symptoms when scheduling appointments and the adoption of distancing in the waiting room. Of the biosafety measures to avoid aerosols, the procedures with lower compliance were those related to the use of intraoral radiographs and rubber dams. Moreover, the correct use of personal protective equipment at work seems to be related to self-perceived stress and anxiety. Worryingly, high access to information through non-governmental documents was observed. Permanent health education policies should reinforce safe practices and encourage workers to implement biosafety and surveillance measures in health services.

Outcomes following osteotome-mediated sinus floor elevation with Bio-Oss Collagen or no grafting material: a one-year single-blind randomized controlled trial

The objective of this single-blind randomized controlled trial was to test the hypothesis of no difference in implant treatment outcome and patient-reported outcome measures (PROMs) following osteotome-mediated sinus floor elevation with Bio-Oss Collagen (test) compared with no grafting material (control) after 1 year of implant loading. Forty healthy patients (27 female, 13 male) with a mean age of 49 years (range 24-74 years) were randomly allocated to the test or control group. Outcome measures included survival of the suprastructures and implants, peri-implant marginal bone loss, complications, and PROMs; the latter included the Oral Health Impact Profile-14 and a self-administered questionnaire with visual analogue scales to assess the peri-implant tissue, implant crown, function of the implant, total implant treatment outcome, and oral health-related quality of life. Mean differences were expressed with the standard deviation and 95% confidence interval. The level of significance was 0.05. Survival of the suprastructures and implants was 100% with both treatment modalities. No significant difference in any of the outcome measures was observed between the test and control groups. High patient satisfaction and a significant improvement in quality of life were observed with both treatment modalities. Consequently, no significant difference in implant treatment outcome between the test and control groups was revealed after 1 year of implant loading. Neither of the treatment modalities can therefore be considered better than the other.

Single-Tooth Replacement in the Maxillary Esthetic Zone with Immediate Implant Insertion and Definitive Abutment Placement and Provisionalization: 1-Year Results of a Prospective Case Series

This prospective longitudinal study evaluated the peri-implant soft tissue remodeling, marginal bone levels, and implant success rate of immediately placed single implants-which received a definitive zirconia abutment and provisional restoration at implant placement-in the maxillary esthetic zone. The final crown was delivered 7 days later. Patients (n = 26) presenting a single extraction-indicated lateral or central incisor with adequate bone volume were eligible for this study. Mesial and distal papilla levels (MPL and DPL, respectively), facial gingival level (FGL), and mesial and distal marginal bone levels (MMBL and DMBL, respectively) were assessed after 7 days and at 1, 2, 3, 6, and 12 months. Patients were classified according to gingival phenotype: thin (≤ 2 mm) or thick (> 2 mm). After 1 year, the implant success rate was 100%. Mean soft tissue recession was -0.04 ± 0.15 mm (MPL), -0.09 ± 0.02 mm (DPL), and -0.13 ± 0.18 mm (FGL). Mean bone remodeling at 1 year was 0.12 ± 0.17 mm (MMBL) and 0.13 ± 0.18 mm (DMBL). The marginal interproximal bone was above the implant platform in 100% of sites. Patients with thick phenotype showed significantly less papillary recession than thin-phenotype patients. Minimal peri-implant hard and soft tissue changes were observed at the 1-year follow-up.

Effect of different thresholds on the accuracy of linear and volumetric analysis of native- and grafted-bone

The study aimed to evaluate the accuracy of Micro-CT in linear and volumetric measurements in native (NB) and grafted bone (GB) areas. A total of 111 biopsies of maxillary sinuses grafted with deproteinized bovine bone (DBB) in humans were evaluated. The linear measurements were performed to measure the length of the NB and GB. Furthermore, the amount of mineralized tissues at the NB and GB was performed. In the histomorphometry analysis the percentage of mineralized tissues at the NB and GB was obtained in two histological sections while the mineralized tissues were measure in the micro-CT varying the thresholds of the grayscale varying from 90-250 to 90-150 with 10 levels of variation between each one was applied. Then these data were correlated in order to check the higher r level between the histomorphometry and micro-CT thresholds intervals. The linear length of the NB was 2.44±0.91mm and 2.48±1.50mm, respectively, for micro-CT and histomorphometry (r =0.57), while the linear length of the GB was 3.63±1.66mm and 3.13±1.45mm, respectively, for micro-CT and histomorphometry (r =0.74) Histomorphometry showed 45.91±11.69% of bone in NB, and 49.57±5.59% of bone and biomaterial in the GB. The total volume of mineralized tissues that were closest to the histometric analysis were 43.75±15.39% in the NB (Threshold:90-240; r = 0.50) and 51.68±8.42% in the GB (Threshold:90-180; r =-0.028). The micro-CT analysis showed good accuracy in the linear analysis in both portions of the biopsies but for volumetric analysis just in NB.

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.

Effect of data binning and frame averaging for micro-CT image acquisition on the morphometric outcome of bone repair assessment

Despite the current advances in micro-CT analysis, the influence of some image acquisition parameters on the morphometric assessment outcome have not been fully elucidated. The aim of this study was to determine whether data binning and frame averaging affect the morphometric outcome of bone repair assessment using micro-CT. Four Wistar rats' tibiae with a surgically created bone defect were imaged with micro-CT six times each, frame averaging set to 1 and 2, and data binning set to 1, 2 and 4, for each of the averaging values. Two-way ANOVA followed by Bonferroni tests assessed the significance of frame averaging and data binning on a set of morphometric parameters assessed in the image volumes (p < 0.01). The effect of frame averaging was not significant for any of the assessed parameters. Increased data binning led to larger trabecular thickness. In contrast, smaller bone volume fraction and bone volume were found as data binning increased. Trabeculae number and trabecular separation were not influenced by any of the parameters. In conclusion, the morphometric outcome of bone repair assessment in micro-CT demonstrated dependency upon data binning, but not frame averaging. Therefore, image acquisition of small anatomical structures (e.g., rat trabeculae) should be performed without data binning.

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.

Magnetic Resonance Imaging for the Planning, Execution, and Follow-up of Implant-Based Oral Rehabilitation: Systematic Review

PURPOSE

To undertake a systematic literature review of magnetic resonance imaging (MRI) employed in the three phases of implant-based oral rehabilitation: planning, execution, and follow-up.

MATERIALS AND METHODS

MEDLINE (PubMed) and EMBASE bibliographic databases were searched up to January 2020 for studies assessing the use of MRI alone or in connection with CT and/or CBCT in the planning, execution, or follow-up of dental implant placement and/or bone grafting procedures in the maxilla or the mandible. Included studies were also assessed according to the diagnostic imaging efficacy scale presented by Fryback and Thornbury (F&T).

RESULTS

The search strategy yielded 10 studies, which were included in the systematic review. Six studies focused on the implant planning phase, one on the immediate follow-up phase, and three on both planning and follow-up. No studies acquired signal from the bone. There was no consensus on the gold standard, MRI sequence, or field strength (T). One study reached F&T level 1, eight reached level 2, and one reached level 3.

CONCLUSION

The possible transition from radiography to ionizing-radiation-free imaging through MRI is still a novelty in dentistry and has yet to establish itself as a viable imaging modality suitable for replacing CT and CBCT. More studies are needed on the accuracy of the diverse MRI possibilities when applied for implant planning, execution, and follow-up before this diagnostic method can be considered as a reality for the clinician.

Cortical Bone Modifications after Radiotherapy: Cortex Porosity and Osteonal Changes Evaluated Over Time

Aiming to evaluate cortical bone microarchitecture and osteonal morphology after irradiation, twelve male New Zealand rabbits were used. The animals were divided: control group (no radiation-NIr); and 3 irradiated groups, sacrificed after: 7 (Ir7d); 14 (Ir14d) and 21 (Ir21d) days. A single radiation dose of 30 Gy was used. Computed microtomography analyzed the cortical microarchitecture: cortical thickness (CtTh), bone volume (BV), total porosity (Ct.Po), intracortical porosity (CtPo-cl), channel/pore number (Po.N), fractal dimension (FD) and degree of anisotropy (Ct.DA). After scan, osteonal morphology was histologically assessed by means: area and perimeter of the osteons (O.Ar; O.p) and of the Haversian canals (C.Ar; C.p). Microtomographic analysis were performed by ANOVA, followed by Tukey and Dunnet tests. Osteon morphology analyses were performed by Kruskal-Wallis, and test Dunn's. Cortical thickness was significant difference (p<0.010) between the NIr and irradiated groups, with thicker cortex at Ir7d (1.15±0.09). The intracortical porosity revealed significant difference (p<0.001) between irradiated groups and NIr, with lower value for Ir7d (0.29±0.09). Bone volume was lower in Ir14d compared to control. Area and perimeter of the osteons were statistically different (p<0.0001) between NIr and Ir7d. Haversian canals also revealed lower values (p<0.0001) in Ir7d (80.57±9.3; 31.63±6.5) compared to NIr and irradiated groups. Cortical microarchitecture was affected by radiation, and the effects appear to be time-dependent, mostly regarding the osteons morphology at the initial days. Cortex structure in Ir21d revealed similarities to control suggesting that microarchitecture resembles normal condition after a period.

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.

Objective assessment of the combined effect of exomass-related- and motion artefacts in cone beam CT

OBJECTIVES

To assess quantitatively the combined effect of exomass-related- and motion artefacts on voxel value parameters in cone beam CT (CBCT).

METHODS

A cylindrical phantom was manufactured, containing 21 tubes filled with a radiopaque solution, allowing the inclusion of three titanium implants in the periphery to induce exomass-related artefacts. The phantom was mounted on a robot simulating 0.75-, 1.5-, and 3 mm movements (nodding/lateral rotation/tremor). CBCT images with/without exomass and with/without movements were acquired in duplicate in three units: Cranex 3Dx, Orthophos SL-3D, and X1 (with motion-artefact correction). A cylindrical volume of interest was defined in each tube and voxel value mean and standard deviation were assessed. For each CBCT volume, the 21 mean voxel values were averaged providing the overall mean voxel value (MVV), and the standard deviation (among the 21 values) was calculated providing overall voxel value inhomogeneity (VVI). The standard deviation from each of the 21 volumes-of-interest were averaged, providing overall image noise (IN). The effect of the diverse tested situations was inferred from a repeated-measures analysis of variance, followed by Sidak's test (α = 0.05).

RESULTS

Overall, images acquired with exomass showed significantly (p ≤ 0.05) lower MVV, and higher VVI and IN. Motion artefacts aggravated exomass-related alterations. MVV and VVI were mostly affected by 3 mm nodding movements. Motion-artefact correction eliminated the deleterious effect of movement.

CONCLUSIONS

CBCT voxel-value parameters are altered by exomass-related artefacts, and this finding is aggravated in the presence of motion artefacts. Motion-artefact correction effectively eliminated the deleterious impact of movement.

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.

Head motion and perception of discomfort by young children during simulated CBCT examinations

OBJECTIVES

To assess the frequency and characteristics (number, complexity, and distance) of head movements, and the perception of discomfort during simulated CBCT examinations in children, considering units with different patient positioning method and head immobilization device combinations.

METHODS

Forty children (20 boys/20 girls, age range 10-14 years) were video-recorded during simulated CBCT examinations. Children were randomly allocated to a sequence of five CBCT units: Newtom-5G, Orthophos-SL, Cranex-3Dx (patient standing/sitting), and X1. The child scored his/her discomfort perception (visual scale) and the preferred/ill-favored unit. Three observers scored the videos (20% in duplicate): child movement (yes/no), number (<3/≥3/continuous), complexity (uniplanar/multiplanar) and distance (<3 mm/≥3 mm). κ statistics provided intra-/interobserver reproducibility. Severe/extreme motion was defined based on movement characteristics. Chi-square tests assessed the frequency differences of severe/extreme motion among the units, age and operator. Logistic regression analyses with severe/extreme motion as outcome were performed.

RESULTS

The range of intra- and inter-observer reproducibility for movement observation was 0.78-0.89 and 0.61-0.64, respectively. Between 60% (Newtom-5G) and 100% (X1) of children moved during the examination. Severe/extreme motion was significantly related to unit and age. There was significantly less severe/extreme motion, when the child was in the supine position with a foam headrest as head support. The younger the child, the higher the risk for severe/extreme motion. The majority of the children preferred the unit with the supine position and a foam headrest.

CONCLUSIONS

The prevalence of severe and extreme motion was associated with the unit's patient positioning method and head immobilization devices combined, and child age.

Effect of computer-assisted-learning and simulation clinics on dental students' cognitive and performance skills: panoramic image errors related to patient's head position

OBJECTIVES

To assess dental students' ability to recognize head positioning errors in panoramic (PAN) images after individual learning via computer-assisted-learning (CAL) and in a simulation clinic (SIM). Both cognitive skills and performance in patient examination were assessed.

METHODS AND MATERIALS

60 students (mean age 23.25 years) participated in lectures on the relation between PAN-image errors and patient's head position. Immediately after they took a test, based on which they were randomized to three groups: control (CON) group, CAL group, and SIM group (both CAL and training in a simulation clinic with a phantom). 4-5 weeks after intervention/no intervention, all students individually examined a patient with PAN-exposure. A blinded rater, not knowing group allocation, supervised patient exposure and assessed student's performance (correct/incorrect head position in three planes). 1-2 weeks after, the students scored positioning errors in 40 PAN-images. Differences in cognitive test scores between groups were evaluated by ANOVA and in patient examination by χ² tests, and within-group differences by sign-tests.

RESULTS

No statistically significant difference in cognitive test scores was seen between the SIM and CAL group, while the CON group scored lower (p < 0.003). In all groups, several students positioned the patient incorrectly in the Frankfort horizontal plane. All students performed well in the sagittal plane. Students in SIM group positioned the patient more correctly in the coronal plane.

CONCLUSIONS

Training with CAL increased students' cognitive skills compared with a control group. Simulated patient exposure with a phantom increased to some extent their performance skills in examination of patients.

Alendronate Impairs Healing of Calvaria Critical Defects After Bone Graft With Different Bone Substitute Materials

PURPOSE

The aim of this preclinical study was to evaluate the healing of critical-sized defects (CSDs) in the calvarial bone of rats grafted with deproteinized bovine bone graft (DBB) and with a combination of hydroxyapatite (HA) and β-tricalcium phosphate (TCP) and bisphosphonate treatment.

MATERIALS AND METHODS

Eighty-four animals were randomly divided into 2 groups according to the type of solution administered: the control group (CTR, saline solution) and the test group (alendronate [ALD]; sodium alendronate-50 μg/kg/day). Medications were administered via oral gavage starting 15 days before the surgical procedure until the end of the experiment. A CSD (5 mm in diameter) was made in the calvaria of each animal, and the rats were randomly allocated to 3 subgroups according to the biomaterial used to fill the defect: coagulum, DBB, and HA/TCP. The animals were sacrificed 15 and 60 days after the surgical procedure (n = 7 animals/period/subgroup). Microcomputed tomography was used to evaluate the percentage of mineralized tissues (volume). The amount of newly formed bone and remaining bone substitute material in the calvaria were analyzed by histomorphometry.

RESULTS

There were no differences between the CTR and ALD groups with regard to the volume of mineralized tissues. The DBB and HA/TCP subgroups of CTR animals presented a significant increase in newly formed bone compared with these subgroups of ALD animals after 60 days of healing.

CONCLUSIONS

Collectively, our findings indicate that the use of oral ALD reduced bone formation in CSD in the calvaria of rats grafted with DBB and HA/TCP.

Effect of section thickness on cone beam computed tomography-based measurements of intrabony defects compared with clinical measurements

BACKGROUND

It is unknown whether cone beam computed tomography (CBCT) image reconstruction characteristics, including section thickness, may affect linear bone measurements of periodontal intrabony defects. The aim of this study was to compare intrasurgical and CBCT-based linear measurements of intrabony defects focusing on CBCT section thickness.

METHODS

Sixty-six intrabony defects were assessed in 21 patients with chronic generalized severe periodontitis. Linear measurements of alveolar bone (radiographic bone level [rBL]), assessed in CBCT images at diverse section thicknesses: 0.25 mm (voxel size), 1 mm, and 3 mm, were compared with clinical bone level (cBL) measurements obtained intrasurgically. To provide identical reference points for rBL and cBL measurements, individually adjusted grooves on the reference stent were prepared for each periodontal defect site. CBCT measurements were performed in two rounds by two trained observers. Observer agreement was assessed by intraclass correlation coefficients (ICC). ANOVA assessed the difference among cBL and rBL at different section thicknesses.

RESULTS

Intra- and inter-observer agreement was excellent (ICC >0.99) and highly significant independent of the observer, evaluation round, and CBCT section thickness. Mean rBL in the diverse CBCT section thicknesses was very close to that measured clinically (cBL). There was no statistically significant difference between cBL and rBL for any section thickness, neither for the overall evaluated sites, nor the maxilla or mandible separately.

CONCLUSIONS

No statistically significant difference between clinical and radiographic bone level for 0.25-, 1-, and 3-mm CBCT section thicknesses were observed when assessing intrabony periodontal defects.

Remodelling of sinus bone grafts according to the distance from the native bone: A histomorphometric analysis

OBJECTIVES

To evaluate graft remodelling according to the distance from the native bone in maxillary sinuses grafted with anorganic bovine bone (ABB).

MATERIAL AND METHODS

Bilateral sinus grafting was performed in twenty patients with residual bone height <5 mm before implant placement. After 8 months, biopsy samples were harvested, and histomorphometric analysis was performed to examine bone formation according to the distance (in mm) from the native bone (sinus floor). In the grafted area, the percentages of new bone (NB), residual graft material (rABB), and soft tissue (ST) were evaluated.

RESULTS

A total of 103 biopsy samples were evaluated, and the percentages of NB, rABB, and ST were 31.62 ± 9.85%, 18.94 ± 7.88%, and 49.41 ± 9.52%, respectively, in the 1st mm; 27.15 ± 9.83%, 23.33 ± 9.45%, and 49.53 ± 11.73%, respectively, in the 2nd mm; 23.61 ± 13.02%, 21.35 ± 11.08%, and 55.03 ± 16.14%, respectively, in the 3rd mm; and 21.67 ± 12.29%, 19.67 ± 10.28%, and 58.66 ± 12.46%, respectively, in the 4th mm. The 1st millimetre of the grafted area (closer to the native bone) presented a larger amount of NB than the other portions of the grafted areas and a smaller amount of rABB than the 2nd mm of the grafted area (p < .05). The amount of ST was larger in the 3rd and 4th mm of the grafted area than in the first 2 millimetres (p < .05).

CONCLUSION

The distance from the native bone influences bone formation following maxillary sinus augmentation.

Radiopacity of endodontic materials using two models for conversion to millimeters of aluminum

The aims of the present study were to compare conventional radiography, radiographs digitized with a scanner or photographic camera, and digital radiography, used to evaluate the radiopacity of endodontic materials, and to compare the accuracy of linear and quadratic models used to convert radiopacity values to equivalent millimeters of aluminum (mm Al). Specimens of AH Plus, Endofill, Biodentine and BioMTA materials (n = 8) were radiographed next to an aluminum step-wedge using radiographic films and digital radiography systems (FONA CMOS sensor, Kodak CMOS sensor and photosensitive phosphor plate-PSP). Conventional radiographs were digitized using a scanner or photographic digital camera. Digital images of all the radiographic systems were evaluated using dedicated software. Optical density units (ODU) of the specimens and the aluminum step-wedge were evaluated by a photo-densitometer (PTDM), used in conventional radiographs. The radiopacity in equivalent mm Al of the materials was determined by linear and quadratic models, and the coefficients of determination (R2) values were calculated for each model. Radiopacity of the materials ranged from -9% to 25% for digital systems and digitized radiographs, compared to the PTDM (p < 0.05). The R2 values of the quadratic model were higher than those of the linear model. In conclusion, the FONA CMOS sensor showed the lowest radiopacity variability of the methodologies used, compared with the PTDM, except for the BioMTA group (higher than PTDM). The quadratic model showed higher R2 values than the linear model, thus indicating better accuracy and possible adoption to evaluate the radiopacity of endodontic materials.

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.

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.

Bone formation around two titanium implant surfaces placed in bone defects with and without a bone substitute material: A histological, histomorphometric, and micro-computed tomography evaluation

OBJECTIVE

To evaluate the histological and microtomographic response of peri-implant bone tissue around titanium implants with different surface treatments, placed in bone defects filled or not filled with bone substitute materials.

MATERIALS AND METHODS

Thirty rabbits were divided into two groups according to the implant surface treatment. A bone defect was created in both tibias of all the rabbits, followed by the placement of one implant in each of these defects. On the left tibia, the defect was filled with a blood clot (BC), and on the right tibia, the defect was filled with biphasic hydroxyapatite/β-tricalcium-phosphate (HA/TCP); thus, there were four groups in total: BC-N: bone defect filled with a BC and porous surface titanium implant (control group); BC-A: bone defect filled with a BC and porous-hydrophilic surface titanium implant; HA/TCP-N: bone defect filled with a bone substitute material and porous surface titanium implant; HA/TCP-A: bone defect filled with a bone substitute material and porous-hydrophilic surface titanium implant. The animals were submitted for euthanasia at three distinct periods: 15, 30, and 60 days after implant installation. The samples were evaluated histologically and histometrically, to assess the quantity and quality of cells and the remaining bone substitute material in the grafted areas. The bone quantity was assessed by micro-computed tomography (CT).

RESULTS

For both surface types, the presence of a bone substitute material led to higher values in all evaluated micro-CT parameters, except in the bone surface/volume ratio parameter. No significant statistical difference was found for new bone formation between the four groups (P < .05; CI 95%). At all periods, the HA/TCP-A group had a higher percentage of new bone formation.

CONCLUSION

These results suggest that a porous hydrophilic surface in the presence of bone substitute material can accelerate peri-implant bone tissue formation.

Cyclosporine A impairs bone repair in critical defects filled with different osteoconductive bone substitutes

The aim of this study was to assess the influence of cyclosporine administration on the repair of critical-sized calvaria defects (CSDs) in rat calvaria filled with diverse biomaterials. Sixty animals were divided into two groups: the control (CTR) group (saline solution) and the cyclosporine (CCP) group (cyclosporine, 10 mg/kg/day). These medications were administered daily by gavage, beginning 15 days before the surgical procedure and lasting until the day the animals were euthanized. A CSD (5 mm Ø) was made in the calvaria of each animal, which was allocated to one of 3 subgroups, according to the biomaterial used to fill the defect: coagulum (COA), deproteinized bovine bone (DBB), or biphasic calcium phosphate ceramics of hydroxyapatite and β-phosphate tricalcium (HA/TCP). Euthanasia of the animals was performed 15 and 60 days after the surgical procedure (n = 5 animals/period/subgroup). Bone repair (formation) assessment was performed through microtomography and histometry, while the analyses of the expression of the BMP2, Osteocalcin, and TGFβ1 proteins were performed using immunohistochemistry. The CSDs not filled with biomaterials demonstrated lower bone formation in the CCP group. At 15 days, less bone formation was observed in the CSDs filled with DBB, a smaller volume of mineralized tissue was observed in the CSDs filled with HA/TCP, and the expression levels of BMP2 and osteocalcin were lower in the CCP group compared to the CTR group. The use of cyclosporine impaired bone repair in CSD, and this effect can be partially explained by the suppression of BMP2 and osteocalcin expression.