Comparison of posterior alveolar canal location measured on computer tomography scan with cadaveric measurement of posterior superior alveolar foramen in Japanese samples.

The aim of this study was to analyse anatomical characteristics of the most posterior alveolar canal (PAC) on computed tomography (CT) images and the posterior superior alveolar foramen (PSAF) physically identified in cadaveric samples, to avoid injuring the posterior superior alveolar artery (PSAA) during surgery in the maxillary tuberosity region. The study included 125 hemi-heads of 64 Japanese cadavers. Simple CT data of the maxillary bone region of the samples were obtained and analysed using measurement software. The alveolar crest (AC) and the PAC were identified to calculate the shortest distance between the AC and the PAC (AC-PAC). Then the samples were dissected to measure physically the shortest distance between the AC and the PSAF (AC-PSAF). The data were analysed statistically. The mean value and standard deviation were 20.7±4.2mm for AC-PAC and 20.7±4.3mm for AC-PSAF. The intraclass correlation coefficient between AC-PAC and AC-PSAF was 0.98. The CT-measured PAC locations were found to be almost identical to the PSAF positions identified physically in the samples. Preoperative CT localization of the PAC aids in avoiding injury to PSAA, while preoperative CT evaluation is important for each case due to significant individual variability in the anatomical PAC and PSAF locations.

Three-dimensional evaluation of healing joint morphology after closed treatment of condylar fractures.

Closed treatment for condylar fractures has long been widely accepted. With closed treatment, the deviated bone fragments heal in their new positions, and this may subsequently cause a range of functional impairments. The association between healing morphology and post-treatment functional impairment is unclear. In this study, computed tomography images of 26 patients (35 sides) who had undergone closed treatment for condylar fractures were used to perform a comparative investigation of three-dimensional (3D) bone morphology before and after treatment. As a result, the morphology of the condylar process after treatment was classified into four different patterns: unchanged, spherical, L-shaped, and detached. In terms of the association between fracture types and healing morphology, fractures of the condylar head healed in the spherical pattern, simple fractures of the condylar neck healed in the spherical or L-shaped pattern, and comminuted fractures of the condylar neck healed in the spherical, L-shaped, or detached pattern. The association between mandibular deviation and healing morphology was also investigated, and it was found that deviation was greater for the spherical and detached patterns than for the L-shaped pattern. The present findings indicate that 3D evaluation of the fractured condylar process is required to elucidate the association with functional impairment after healing.

Effect of allergen sensitization on external root resorption.

In orthodontic tooth movement (OTM), we should be concerned about external root resorption (ERR) as an undesirable iatrogenic problem, but its mechanisms are not fully understood. Since our previous epidemiologic studies found that patients with allergic diseases showed higher rates of ERR during orthodontic treatment, we explored the possible effect of allergic sensitization on ERR. In ovalbumin (OVA)-sensitized Brown-Norway rats, the amounts of ERR and OTM were greater than those in animals subjected to orthodontic force alone. The expression levels of RANKL and pro-inflammatory cytokines were increased in the periodontal tissues of sensitized rats with OTM, compared with control rats. Furthermore, leukotriene B4 (LTB4), a potent lipid mediator of allergic inflammation, and enzymes of the 5-lipoxygenase pathway, the biosynthetic pathway of leukotrienes, were also up-regulated. We found that low doses of aspirin suppressed ERR in allergen-sensitized rats, as well as the expressions of RANKL, pro-inflammatory cytokines, and LTB4. The present findings indicate that allergen sensitization has adverse effects on ERR under OTM, and that aspirin is a potential therapeutic agent for combating ERR.