Chitin is an absorbable agent used to promote wound healing and hemostasis, and is also used in medical treatment. We investigated the effects of carboxymethyl-chitin (CM-chitin), a water-soluble derivative of chitin, on bone augmentation.
Four maxillary incisors were extracted from 5 adult Crab-eating Macaques, then the extraction sockets on the subjects' right sides were immediately filled with CM-chitin (experimental sites), while the left sides were left unfilled (control). One, two, four, eight, and twelve weeks after the procedure, the animals were euthanized and acrylic resin was injected via the common carotid arteries. Bone-microvascular corrosion casts were made and observed using scanning electron microscopy to determine the volume ratio of newly-formed bone in each socket.
After 1 week, newly-formed capillary networks were observed in the sockets of the experimental sites. After 2 weeks, the sockets in both the experimental and control sites were filled with newly-formed capillary networks. After 4 weeks, newly-formed bone was observed in the sockets of both sites and the sockets were also filled with newly-formed bone after 8 weeks. After 12 weeks, trabecular bone was thicker and more compressed than after 8 weeks. Image analysis showed that the volume ratio of newly-formed bone was not significantly different between the experimental and control sites.
We concluded that CM-chitin does not obstruct bone augmentation in extracted tooth sockets and is useful to promote angiogenesis in the early stages.
In jaw bones with decreased bone mass, bone augmentation is desirable for better implant treatment results. Therefore, scaffolding with sufficient mechanical strength to ensure space for new bone formation needs to be developed. In a previous study we looked at coral as a scaffolding material and elucidated its mechanical strength and three-dimensional structure with micro CT. In the present study, we observed its microstructure and investigated the formation of blood capillaries in vitro, and conducted an in vivo experiment of bone augmentation in bone defects with coral. Materials and methods: The microstructure of coral skeleton was observed with a scanning electron microscope and atomic force microscope. Fibroblasts and vascular endothelial cells were cocultured and stained immunohistochemically with anti-CD31 antibody, and the state of capillary formation was observed. In the in vivo experiment, a block of coral was implanted into an experimental defect in a canine femur and covered with a porous filter. Calcein was administered at seven weeks after the implant procedure, and one week later the femur with the implanted portion was removed and observed with confocal laser scanning microscopy and light microscopy. Results: Inside the coral were innumerable tubular structures 100～300 μm in diameter that communicated with the outside, connected to neighboring ducts through pores. The surface of the skeleton was covered with 10～20 nm protrusions, on the surface of which further innumerable rounded projections of 60～200 nm were observed. In vitro, formation of capillaries was seen around coral particles. In vivo, multinucleated giant cells were observed in contact with the coral, and bone augmentation was seen together with new bone formation bordered by osteoblasts in the inner cavities of the coral block. These findings suggest that coral blocks are promising as a scaffolding material for bone augmentation in bone defects.
Purpose: Assessment of lingual foramina is important in implant surgery because the sublingual and submental artery run into the mandible anterior cortex. Penetration of a vessel by drilling may potentially cause life-threatening conditions. However, there has been no report on edentulous patients, even although the lingual foramina of dentate patients have been evaluated. The purpose of the present study was to assess the anatomical properties of mandibular lingual foramina using spiral computed tomography (CT) and the postoperative complications.
Materials and Methods: The regional frequency of the lingual foramina was investigated using spiral computed tomographic images of edentulous mandibles obtained from 22 patients. The position of the lingual foramina was classified. The position was measured vertically and horizontally by digital calipers on the CT images. Additionally, postoperative complications were evaluated.
Results: Lingual foramina were observed in 100% of subjects. The distance between the alveolar crest and lingual foramina was 11.4±4.6 mm. The highest regional frequency was recognized in the midline area (77%). The horizontal distance between the midline and lingual foramina was 2.0±0.0 mm (right) and 5.3±3.1 mm (left). As for postoperative complications, hemorrhage with tongue elevation of one case (5%) was observed in the floor of the mouth.
Conclusion: Information on the high regional frequency of lingual foramina in the midline is important to avoid incidents caused by the penetration of blood vessels. Therefore, confirmation of the location of lingual foramina and post-operative observation are required.
In recent years, various complications of implant treatment have been reported, as such treatments are now performed in various other clinics. To reduce such cases, it is important to clarify the problems that have troubled many dentists and patients. We therefore conducted a retrospective clinical study of complicated cases at other clinics.
From 2001 to 2008, 66 patients consulted the Department of Oral and Maxillofacial Surgery, Kyushu University Hospital after problems caused by implant treatment.
1. Complicated cases tended to increase year by year.
2. The average age was 62.0 years, with a female to male ratio of 2:1.
3. Ten patients consulted our department themselves, 15 patients were referred by the dentists who had performed the implants, and 41 patients were referred by dentists who had not performed the implants.
4. Chief complaints were abnormality of the implant circumference (18 cases), neuropathy and mobility (11 cases each), without symptoms (8 cases), occlusal pain and examination of the relationship between implants and other symptoms (5 cases each), nasal symptom and implant fracture (3 cases each), and implant discomfort and dysgeusia (1 case each).
5. Implant types were the root form type (45 cases), blade type (13 cases), home-made type (7 cases) and subperiosteal type (1 case).
6. The total number of implants was 236 (root form type: 165, blade type: 17, home-made type: 53, subperiosteal type:1). The average number of implants was 3.6.
7. Superstructures of implants were connected to implants or a single in 17 cases, to natural teeth in 32 cases, and not set in 17 cases.
8. Regarding the number of years elapsed from implant treatment, 33 cases were less than 5 years (7 cases were less than 1 month), and 19 cases were more than ten years.
9. Regarding the duration before receiving a medical examination after symptoms developed, 83.3% of cases received an examination within 3 years.
10. The diagnosis was peri-implantitis in 36 cases, neuropathy in 11, implant fracture in 6, migration into the maxillary sinus in 4, and other diagnosis in 9.
11. Implant removal was performed in 37 cases, other surgical treatment in 4, conservative management in 12, treatment of referred pain in 2, and no treatment in 11.
Complicated cases will increase in future as the use of implant treatment spreads. Therefore, there is an urgent need to enhance the education system, clear diagnostic criteria and guidance for medical care for implant treatment.
Objectives: CT number derived from medical CT (MDCT) is effective for evaluating the quality of bone. On the other hand, in dental cone beam CT (CBCT), it is questionable whether the pixel value of the CBCT reflects the quality of bone. To investigate this matter, we prepared a dry skull with gypsum markers attached at different positions, scanned by MDCT and CBCT, and compared the CT number or pixel value between gypsum markers.
Methods: Sixteen gypsum markers were attached on labial and buccal sites of maxillary and mandibular bone of a dry skull. They were scanned by a MDCT and three dental CBCT devices. The CT numbers or pixel values of gypsum markers measured by CT devices were examined, and their position and CT device dependencies were compared and discussed.
Results: In the case of MDCT, the average CT number and standard deviation of 16 markers was 2,011±79. In the case of CBCT, pixel value was 2,815±305. The pixel value changed significantly by a slight change in position of the dry skull. Similar results were obtained for other CBCT devices.
Discussion and Conclusion: These results are considered to be due mainly to the scattered beams in the CBCT. The incident beam extends conically-shaped in the CBCT and there is much beam scattering depending on the position of the measured object, causing pixel values to deviate. Flat panel detector equipped in the CBCT is not effective to defend scattered beam on the edges of the detector.
An effective device such as a collimator to eliminate beam scattering or software to compensate for beam scattering needs to be developed.