ABSTRACT
The aim of the present study was to assess the positive predictive value (PPV) of panoramic radiographic signs in the assessment of the relationship between impacted mandibular third molars (IMTMs) and the mandibular canal (MC). This cross-sectional study was conducted by reviewing 102 cone-beam computed tomography (CBCT) and panoramic radiographs of patients with IMTMs and radiographic signs of the contact of the IMTMs with the MC on panoramic radiographs (i.e., root apex darkening and interference with the white line). A positive relationship of the IMTM roots with the MC based on CBCT findings was recorded as the gold standard. The PPV of panoramic radiographic signs was calculated for the detection of the relationship of the IMTM root with the MC. The IMTMs were in contact with the MC on CBCT scans in 90.1% of the cases. The PPV of root apex darkening and the interference with the white line was found to be 89.09% (95% CI: (77.75, 95.88)) and 91.48% (95% CI: (79.62, 97.63)), respectively. The MC had a buccal position in 63.7%, and a lingual position in 35.2%, of the cases. The contact of IMTMs with the MC was more commonly seen in patients with a lingual position (100% of the samples). The IMTM root apex darkening and interference with the white line of the MC on panoramic radiographs had a high PPV for determination of the contact of IMTMs with the MC. Thus, presence of the above-mentioned risk factors indicates the need for subsequent 3D radiographic assessments.
ABSTRACT
BACKGROUND: Nicotine can have detrimental effects on dental implant osseointegration. This study aimed to evaluate the influence of systemic L-arginine supplement on the osseointegration of dental implants in nicotine consumer dogs. METHODS: Twelve 1-year Labrador Retriever dogs had their right and left third and fourth mandibular premolars removed, and the sockets were left to heal for 6 months. Dogs were randomly divided into three groups (n = 16): group 1-0.2 mg/kg nicotine was injected twice daily; group 2-0.2 mg/kg nicotine was injected twice daily in addition to 200 mg/kg L-arginine capsules taken orally; and group 3-placebo. Forty-eight dental implants were inserted into the healed sockets of the dog's mandible and were assessed by implant stability quotient (ISQ) using resonance frequency analysis (RFA) during 4 weeks and insertion and removal torque value analysis. RESULTS: No implant failure occurred during the study period. The change in torque value between insertion and removal was similar in the placebo and nicotine+arginine consumer dogs (p = 0.276), which shows a positive effect of arginine supplementation in nicotine consumers. There was a significant difference in torque value change between nicotine+arginine vs. nicotine consumers (p = 0.049) and placebo vs. nicotine (p = 0.003). After 4 weeks, the placebo had the most significant improvement in torque value (47.0 ± 16.9), followed by nicotine+arginine (25.1 ± 37.8), and the worst torque value was for the nicotine group (- 5.7 ± 24.0) pound per inch. The results show that except in the first week, there are significant differences in ISQ between the groups in different periods. ISQ in all of the groups has reduced at first but then increased over time. At the time of implant placement, insertion torque was significantly higher in the nicotine consumer group than the nicotine+arginine consumer group and placebo group (p = 0.020). CONCLUSION: Arginine supplementation promotes bone healing and implant primary stability by improving dental implant osseointegration biomechanical characteristics.
ABSTRACT
The purpose of this article was to evaluate the bone induction effects of an amnion membrane-protected graft compared with a collagen membrane-protected graft in the repair of tibial bony defects in dogs. This study was performed using the tibial bone of dogs. After the removal of periosteum, similar holes were made with a 16-mm trephine drill (38 holes in total). For the study group, 10 holes were covered by absorbable collagen and 16 holes by amniotic membrane. In the control group, 12 holes were made and covered by the overlying soft tissue. Tibial bones were exposed after 6 and 12 weeks, and the samples were harvested and histologically processed. New bone formation was evaluated by histomorphometric study. Four Iranian mixed dogs older than 1.5 years were included in this study. The new bone formation was less in the control group when compared with the collagen group ( P = .863). The collagen group showed less bone formation than the amnion group ( P = .194), but this difference was not significant. However, bone formation in the amnion group was significantly more than in the control group ( P = .050). Using the amniotic membrane appears to accelerate bone formation in guided bone regeneration. However, further studies should investigate its clinical impact on bone healing.
