Bone contains considerable amounts of minerals and proteins. Hydroxyapatite [Ca10(PO4)6(OH)2] is one of the most stable forms of calcium phosphate and it occurs in bones as major component (60 to 65%), along with other materials including collagen, chondroitin sulfate, keratin sulfate and lipids. In recent years, significant progress has been made in organ transplantation, surgical reconstruction and the use of artificial protheses to treat the loss or failure of an organ or bone tissue. Chitosan has played a major role in bone tissue engineering over the last two decades, being a natural polymer obtained from chitin, which forms a major component of crustacean exoskeleton. In recent years, considerable attention has been given to chitosan composite materials and their applications in the field of bone tissue engineering due to its minimal foreign body reactions, an intrinsic antibacterial nature, biocompatibility, biodegradability, and the ability to be molded into various geometries and forms such as porous structures, suitable for cell ingrowth and osteoconduction. The composite of chitosan including hydroxyapatite is very popular because of the biodegradability and biocompatibility in nature. Recently, grafted chitosan natural polymer with carbon nanotubes has been incorporated to increase the mechanical strength of these composites. Chitosan composites are thus emerging as potential materials for artificial bone and bone regeneration in tissue engineering. Herein, the preparation, mechanical properties, chemical interactions and in vitro activity of chitosan composites for bone tissue engineering will be discussed.

Chitosan composites for bone tissue engineering--an overview.

A Position Paper Subcommittee of the American Academy of Oral and Maxillofacial Radiology (AAOMR) reviewed the literature since the original position statement on selection criteria for radiology in dental implantology, published in 2000. All current planar modalities, including intraoral, panoramic, and cephalometric, as well as cone beam computed tomography (CBCT) are discussed, along with radiation dosimetry and anatomy considerations. We provide research-based, consensus-derived clinical guidance for practitioners on the appropriate use of specific imaging modalities in dental implant treatment planning. Specifically, the AAOMR recommends that cross-sectional imaging be used for the assessment of all dental implant sites and that CBCT is the imaging method of choice for gaining this information. This document will be periodically revised to reflect new evidence.

Position statement of the American Academy of Oral and Maxillofacial Radiology on selection criteria for the use of radiology in dental implantology with emphasis on cone beam computed tomography

Recommendations of the International Commission on Radiological Protection, ICRP Publication 2: Keport of Committee II on Permissible Dose for Internal Radiation (1959)., Pergamon Press (London, New York, Paris, Los Angeles), 1960, 233頁, 18.5×25.0cm, 1800円(丸善の価格)

Background Anterior loop of the mental nerve is a very important anatomic landmark in implant placement and anterior mandibular osteotomies. Purpose Two-dimensional imaging techniques are not competent enough to locate and measure the mental nerve loop in majority of the cases. Any injury to this loop results in pain/paresthesia/numbness in the region supplied by the mental nerve. The aim of this study is to analyze the prevalence and measure the length of the loop using cone beam computerized tomography (CBCT) and calculate the average length and prevalence so that a safe margin can be given while placing the implants or the osteotomy cuts in the premolar region. Materials and methods A cross-sectional study was done using CBCT images of 85 patients taken for impaction surgery. The length of the loop was measured in mm using standardized lines drawn along specific anatomic landmarks. Results In our study 11.76% of patients had anterior loop in their mental nerve. Mean length of the mental nerve loop was calculated and found to be 2.79 mm. Conclusion A margin of 4 mm anterior to the mental foramen should be safe to avoid any damage to the mental nerve loop bundle in majority of the cases where the loop is present.

Prevalence and measurement of anterior loop of the mandibular canal using CBCT: A cross sectional study.

Digital and Advanced Imaging in Endodontics: A Review

Measurement of anterior loop length for the mandibular canal and diameter of the mandibular incisive canal to avoid nerve damage when installing endosseous implants in the interforaminal region: a second attempt introducing cone beam computed tomography.

The retromolar foramen (RMF) is an anatomical structure on the alveolar surface of the retromolar area. This foramen runs consecutive to the retromolar canal (RMC), which diverges from the mandibular canal. It is important to confirm the RMF and canal locations prior to surgical procedures, such as extraction of an impacted molar and bone harvesting as a donor site for bone graft surgery. This aim of this study was to investigate the RMF in Japanese cadaver mandibles using cone-beam computed tomography (CBCT) images and anatomical observations. Ninety sides of 46 cadaver mandibles were investigated in this study. CBCT images around the retromolar region were acquired for all of the mandibles. The frequency and anteroposterior and buccolingual locations of the RMF were examined on these images. Subsequently, four sides of three mandibles were dissected to confirm the contents of the RMC/RMF. In 24 of 46 (52%) mandibles and 34 of 90 (37%) sides, at least one RMF was observed in the images. In 26 dentate mandibles, 12 (48%) mandibles and 14 (33%) sides presented at least one RMF. The average location of the RMF was 14.4 mm posterior from the distal edge of the second molar. The buccolingual location was 3.0 mm lingual from the mandibular canal. Observations made during the cadaver dissections confirmed that the vessels and nerves diverged from the mandibular canal. The findings suggest that the RMF is not a rare anatomical structure and that practitioners should take this foramen into account in all anesthetic and surgical procedures involving the retromolar area.

Observation of the retromolar foramen and canal of the mandible: a CBCT and macroscopic study

The mental artery displays several branches internal to the anterior region of the mandible as confirmed by macroscopic observation and computed tomography. The inferior alveolar artery formed complex branches and divided into mental and incisive branches, which were found in the right internal side of the mandible of one male cadaver (88 years old). The branches of these two arteries ran through the bony lingual canal to the lingual foramen between the canine and premolar region of the inner surface of the mandible body, where they emerged to enter the mylohyoid and anterior belly of the digastric muscles and communicate with the submental artery. The observation of the anastomotic artery is considered important for surgical placement of dental implants in the mandibular region.

Anastomosis between the inferior alveolar artery branches and submental artery in human mandible.

The inferior alveolar artery, vein and nerve send some branches to the molar teeth via the mandibular canal to the mental foramen. The present study attempted to define the presence and course of the mandibular canal in the mandible with the alveolar process by macroscopic cadaveric dissection and computerized tomography (CT) in order to provide information that might prevent injuries to vessels and nerves at risk during root canal treatment. We identified the position of the mandibular canal within a 30% ratio of the distance from inferior border of mandible to the apices of the root for 39 out of 131 sides (mesial root of first molar, 20%; distal root of first molar, 22.6%; mesial root of second molar, 27.8% and distal root of second molar, 47%) on panoramic X-ray observation. In one cadaver (male, 64 years old), the root apex of the second molar was in close proximity to the upper bony mandibular canal. Macroscopic dissection and computerized tomography showed that the main trunks of the inferior alveolar artery, vein, and nerve were in tight contact with the apex of the second molar. These observations of the anatomic course of the mandibular canal will be important to consider during root canal treatment of mandibular teeth.

Rare courses of the mandibular canal in the molar regions of the human mandible: a cadaveric study.

Objectives
We investigated the lingual foramina and their bony canals in the median region of the mandible using cone beam computed tomography (CBCT).

Classification of the lingual foramina and their bony canals in the median region of the mandible : cone beam computed tomography observations of dry Japanese mandibles

Takashi Yosue

Papers

Measurement of anterior loop length for the mandibular canal and diameter of the mandibular incisive canal to avoid nerve damage when installing endosseous implants in the interforaminal region: a second attempt introducing cone beam computed tomography.

Observation of the retromolar foramen and canal of the mandible: a CBCT and macroscopic study

Anastomosis between the inferior alveolar artery branches and submental artery in human mandible.

Rare courses of the mandibular canal in the molar regions of the human mandible: a cadaveric study.

Classification of the lingual foramina and their bony canals in the median region of the mandible : cone beam computed tomography observations of dry Japanese mandibles