Skin dose from cone-beam computed tomography imaging
Akyalcin S, English JD, Abramovitch KM, Rong XJ. Measurement of skin dose from cone-beam computed tomography imaging. Head Face Med 2013;9:28
Cone-beam computed tomography (CBCT) scans are becoming more universal and are supported by claims that the radiation dose is lower than the combined dose of a lateral cephalogram, a panoramic radiograph, and a full series of periapical radiographs. However, there is no conclusive evidence to fully support these views. In computed tomography radiation dosimetry, the computed tomography dose index is used to compare dose levels; it is a dose descriptor, not a direct measure of patient dose. To determine the dose within certain points of the scan, an optically stimulated luminescence is used. The effective dose, which accounts for the types of tissues being exposed and the amount of radiation to those tissues, is calculated. Three CBCT units were compared with a conventional panoramic-cephalometric x-ray unit (Kodak 9500, i-CAT Next Generation, Galileos Comfort, ProMax pan/ceph x-ray unit). An RS-110 anthropomorphic phantom was used with 3 nanoDOT dosimeters at each anatomic level: eye lens (3.55 mGy), and parotid, submandibular, and thyroid glands (lowest dose at 0.46 mGy). The scans were completed by using medium (10-16 cm) and large (>16 cm) scanning fields of view. The results showed a much lower dose for conventional panoramic and cephalometric radiographs combined compared with the CBCT scans for all anatomic areas of the head and neck (about 1:4 mGy). However, the peak skin dose at any anatomic level did not exceed 4.62 mGy—well below 2000 mGy that is regarded as the threshold for deterministic effects in medical imaging. CBCT imaging can be useful in selected orthodontic patients and should be used prudently. When used, the scanning fields of view and milliamperes should be considered to lower the effective dose received by the patient.
Reviewed by Kevin Ward and Eryn Ence
Timing for gingival grafting
Kloukos D, Eliades T, Sculean A, Katsaros C. Indication and timing of soft tissue augmentation at maxillary and mandibular incisors in orthodontic patients. A systematic review. Eur J Orthod 2013 Oct 15 [Epub ahead of print]
Orthodontic tooth movement has been considered to be a potential risk factor for gingival recession. Several methods of periodontal therapy have been described to address this risk. Although historically recommended by periodontists, prevention of gingival recession with preorthodontic soft-tissue grafts remains controversial. Opposite to this preventive concept, some consider this to be overtreatment and prefer to wait until the potential gingival recession becomes a clinical entity. Subsequently, the recession can be treated during or after orthodontic therapy. The aim of this systematic review was to assess the available literature to determine whether soft-tissue augmentation is indicated for prevention or treatment of gingival recession, and the timing in conjunction with orthodontic treatment. Electronic searches of the following databases were performed: MEDLINE, EMBASE, Cochrane, and CENTRAL. No randomized controlled trials were identified. From 607 initial search results, 2 studies of low-to-moderate levels of evidence were included: one of prospective and retrospective data collection, and one retrospective study. Both implemented a periodontal intervention before orthodontic treatment. No randomized controlled trial was identified, and a meta-analysis was not possible. Although clinical experience might show that soft-tissue augmentation before orthodontic treatment is a viable treatment option, this treatment is not supported by conclusive scientific evidence. Data on the timing of a soft-tissue graft after recession has occurred are also lacking. This study showed that there is limited research from which to draw definitive conclusions. Both cited articles were more than 20 years old and were clinical in design. Future studies might prove more convincing with radiographic evaluations by using computed tomography technology. These findings demonstrate an opportunity and a need for well-designed studies evaluating these treatment options.
Reviewed by Travis Tingey