Detection of posterior superior alveolar artery using multi-detector row CT: a retrospective study focused on age-related changes.

PURPOSE: The posterior superior alveolar artery (PSAA) is a branch of the maxillary artery that supplies the lateral sinus wall and overlying membrane. This artery is one among several arteries in which arterial damage during surgery can cause massive and fatal bleeding. The purpose of this study was to detect the PSAA using multi-detector row computed tomography (MDCT) by age. MATERIALS AND METHODS: The present study was approved by our university ethics committee (EC19-010). The study included 230 patients (110 males, 120 females; ages 5-91 years, average age 42.5 years) who underwent MDCT of the jaw. The subjects were divided into two groups, one group in which the PSAA was observable and another in which the PSAA was not observable, to perform the Mann-Whitney U test. To perform the Tukey-Kramer multiple comparison test, the subjects were divided into the following ten groups depending on their age: 5-9 years, 10-19 years, 20-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years, 70-79 years, 80-89 years, and 90-91 years. RESULTS: The PSAA was identified in 74.5% (5-91 years) of the maxillary sinuses. The average age of subjects in whom the PSAA was observable was 33.4 years, and the average age of subjects in whom the PSAA was not observable was 11.3 years, indicating a significant difference between these two groups (p < 0.01). A comparison by age group showed a significant difference (p < 0.05). CONCLUSIONS: The detection ratio for the PSAA using MDCT increased with increasing age of the subject, reaching a high detection ratio of 94% in adults. This study has shown that MDCT is a very useful tool to observe the PSAA.

An on-site preparable, novel bone-grafting complex consisting of human platelet-rich fibrin and porous particles made of a recombinant collagen-like protein.

Platelet-rich fibrin (PRF) is widely used in regenerative medicine. Nonetheless, major issues include its controversial effects on bone regeneration and a lack of quality-assured glass tubes required for coagulation. We used porous particles (FBG) comprising a recombinant RGD motif-enriched collagen I-like protein to activate the coagulation pathway and examined the effects of the resulting PRF-FBG complex on bone regeneration. Human whole-blood samples were mixed with FBG in plastic tubes and centrifuged to prepare a PRF-FBG complex. Platelet-derived growth factor-BB (PDGF-BB) levels and cell growth activity were determined by ELISA and a bioassay using osteoblasts. Bone regenerative activity was assessed using a mouse model of calvarial bone defect. FBG facilitated PRF-like matrix formation during centrifugation. In this PRF-FBG complex, the microstructure of fibrin fibers was similar to that of PRF prepared conventionally in glass tubes. PDGF-BB levels and mitogenic action were not significantly influenced by FBG. In the bone defect model, although PRF did not exert any significant positive effects on its own, in combination with FBG, it synergistically stimulated new bone formation. This study demonstrated that incorporation of FBG into whole-blood samples induces PRF formation without the aid of glass tubes. The resulting PRF-FBG complex could be a promising bone grafting material in clinical settings. © 2018 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1420-1430, 2019.

Spectrophotometric determination of platelet counts in platelet-rich plasma.

BACKGROUND: Platelet-rich plasma (PRP) is widely used in regenerative dentistry and other medical fields. However, its effectiveness has often been questioned. For better evaluation, the quality of individual PRP preparations should be assured prior to use. We proposed a spectrophotometric method for determination of platelet counts and validated its applicability using two types of PRP preparations. METHODS: Blood samples were obtained from healthy male volunteers and pure PRP (P-PRP) and leukocytes-rich PRP (L-PRP) were prepared using the double-spin method. In serial dilutions, platelet counts in P-PRP and L-PRP were determined using an automated hematology analyzer and a compact spectrophotometer. For validation, P-PRP and L-PRP independently prepared by three well-trained operators were used for comparison of the calculated and measured platelet counts. RESULTS: In the two types of PRP samples evaluated, platelet counts were almost equal and greater amount of both white blood cells (WBCs) and red blood cells (RBCs) were included in L-PRP preparations. The calibration curve obtained from serially diluted P-PRP showed a strong correlation (R2 = 0.995), whereas that of L-PRP was relatively weaker (R2 = 0.975). In validation testing, the scatter plot of the calculated platelet counts versus the measured values showed a strong correlation in P-PRP (R2 = 0.671), whereas that of L-PRP showed a much weaker correlation (R2 = 0.0605). CONCLUSIONS: This method can precisely determine platelet counts in PRP preparations when the inclusion of WBCs or RBCs is minimized. Therefore, we recommend that clinicians use this method for quality assurance of individual PRP preparations.

An Evaluation of the Accuracy of the Subtraction Method Used for Determining Platelet Counts in Advanced Platelet-Rich Fibrin and Concentrated Growth Factor Preparations.

Platelet concentrates should be quality-assured of purity and identity prior to clinical use. Unlike for the liquid form of platelet-rich plasma, platelet counts cannot be directly determined in solid fibrin clots and are instead calculated by subtracting the counts in other liquid or semi-clotted fractions from those in whole blood samples. Having long suspected the validity of this method, we herein examined the possible loss of platelets in the preparation process. Blood samples collected from healthy male donors were immediately centrifuged for advanced platelet-rich fibrin (A-PRF) and concentrated growth factors (CGF) according to recommended centrifugal protocols. Blood cells in liquid and semi-clotted fractions were directly counted. Platelets aggregated on clot surfaces were observed by scanning electron microscopy. A higher centrifugal force increased the numbers of platelets and platelet aggregates in the liquid red blood cell fraction and the semi-clotted red thrombus in the presence and absence of the anticoagulant, respectively. Nevertheless, the calculated platelet counts in A-PRF/CGF preparations were much higher than expected, rendering the currently accepted subtraction method inaccurate for determining platelet counts in fibrin clots. To ensure the quality of solid types of platelet concentrates chairside in a timely manner, a simple and accurate platelet-counting method should be developed immediately.

Computed Tomography Findings of Mandibular Nutrient Canals.

INTRODUCTION: The purpose of this study was to assess computed tomography (CT) findings of mandibular nutrient canals using CT images. MATERIALS AND METHODS: We retrospectively analyzed the mandibular CT images of 194 consecutive patients. For image analysis such as canal prevalence, location, number, size, shape, and the CT value of nutrient foramina were determined using CT axial images of 0.5 and 3 mm slice thickness. RESULTS: We revealed that the nutrient canals were seen 94.3% in the mandible, mostly seen in the anterior region. By location, nutrient canals were particularly seen between the central and lateral incisors. The mean number of nutrient canals was 2.7. The mean diameter of the nutrient foramen between the central and lateral incisors was 1.0 mm. In about 80% of the cases, foramina between the central and lateral incisors were ovoid. The mean CT value for the nutrient foramina between the central and lateral incisors was 411 HU. DISCUSSION AND CONCLUSIONS: Mandibular nutrient canals were ovoid shape, and the mean CT value was 411 HU. By preoperative knowledge of the position and anatomy of the mandibular nutrient canals, complications such as injury to the nutrient canals can be avoided.

Assessment of relationships between implant insertion torque and cortical shape of the mandible using panoramic radiography: preliminary study.

PURPOSE: To assess the relationship between mandibular cortical bone status as determined with panoramic radiography and insertion torque (IT) in implant treatment. MATERIALS AND METHODS: Using panoramic radiographs, two dental radiologists assessed patients' mandibular cortical bone status and classified them into two groups-normal or abnormal (mildly, moderately, or severely resorbed)-based on morphologic features of the mandibular cortical bone margins. Kappa coefficients between the two dental radiologists were calculated to determine interexaminer variability. Included patients underwent implant placement and surgery, during which IT was measured. Patients were classified into three groups based on these measurements: 15 Ncm or lower, between 15 and 35 Ncm, and 35 Ncm or higher. Correlations between mandibular cortical bone morphology and measured IT were assessed and analyzed statistically. RESULTS: Ninety-six patients (34 men, 62 women; mean age 59.1 years) were included in this study; 73 (76.0%) displayed a normal cortex and 23 (24.0%) had an abnormal cortex. In patients with a normal cortex, 13 (8.6%) had IT measurements of 15 Ncm or lower, 42 (27.6%) between 15 and 35 Ncm, and 97 (63.8%) of 35 Ncm or higher. In patients with an abnormal cortex, 3 (4.9%) had IT of 15 Ncm or lower, 35 (57.4%) between 15 and 35 Ncm, and 23 (37.7%) of 35 Ncm or higher. IT values were significantly lower in patients with an abnormal cortex compared to those with a normal cortex. A significant correlation between morphology of the mandibular cortex and IT was observed. CONCLUSION: The mandibular cortical bone status assessed on panoramic radiographs correlates with implant IT, suggesting that panoramic radiographs may be used effectively to determine bone density before implant treatment.