**1. Introduction**

Ever since the discovery of X-rays by Wilhelm Conrad Roentgen in 1895, the diagnostic capabilities of medical and dental professions has been revolutionized and forever changed the practice of medicine and dentistry. Substantial advances in X-ray generator and X-ray detector technology have resulted in significant dose reductions and improved image quality. These advances in oral radiography have transformed into meaningful clinical applications improving the way we prevent, diagnose and treat periodontal disease [1–3].

In periodontics, the main purpose of radiography is to detect the level of the alveolar bone including the pattern and extent of bone loss. Measurements which are of linear from the cement enamel junction to the crest of alveolar bone and from the cement enamel junction to the osseous defect base are commonly used to measure crestal bone levels and osseous defects [4–7]. In radiographs, the periodontal ligament space, lamina dura and periapical region are evident and also useful in identifying risk factors, such as calculus and defective restorations [8].

Radiographs are valuable for diagnosis of periodontal disease, estimation of severity, determination of prognosis, and evaluation of treatment outcome. However, radiographs are an adjunct to the clinical examination, not a substitute for it. Radiographs demonstrate changes in calcified tissue; they do not reveal current cellular activity but rather reflect the effects of past cellular experience on the bone and roots.

Radiographs can provide critical information for diagnosis and treatment planning, which can also serve as baseline information for the assessment of treatment outcomes [9–11].

Periodontist need to understand the strength and weakness of diagnostic imaging and way the cost and benefits of the test before prescribing it. Prescribing the appropriate type and the number of radiographs is critical for optimizing the impact of radiographs on treatment out comes.

The adaption of imaging which is digital as a modality of radiographic assessment of the feature, according to scientific evidence, has the potential to change the way to see the periodontal tissues. There is a little doubt that future periodontist will be using as advanced imaging modalities, either directly or indirectly [12].
