单项选择题 Which of the following projections images the crowns of both maxillary and mandibular teeth on the same film and is helpful in diagnosing interproximal dental caries

单项选择题 Which one of the following anatomy should not appear on the periapical radiograph of the lower central incisor

单项选择题 Periodontal ligament space appears as a radiolucent space between the tooth root and the （）.