I understand your concern about exposure. However, the exposure from dental radiographs is extremely small, especially with new developments in film and equipment. We receive radiation exposure from natural or background sources. One source is cosmic radiation which is primarily a function of altitude. A person in an average location in the United States who receives a full mouth intraoral periapical and panoramic examination every 4 months for the rest of his or her life incurs approximately the same exposure as a person living in Denver, Colorado, USA who has not had dental radiographs.
Panoramic radiographs have advantages and disadvantages.
The main disadvantage is that the image does not provide the fine detail that bitewings and periapical radiographs provide. Panoramic radiographs are excellent for evaluation of trauma, third molars, tooth development, and certain anomalies. They are not good for diagnosing decay, bone level, and certain types of periapical pathosis. Bitewing radiographs are important for detecting decay in between the teeth and for evaluating the periodontal condition. They provide a good view of the bone level.