A Full Mouth Survey (FMS or FMX) is a comprehensive set of intraoral dental radiographs that provides a complete diagnostic picture of the teeth and supporting bone structures. Dental professionals use this series of images to evaluate the entire oral cavity, including areas not visible during a standard clinical examination. The FMS is typically recommended for new patients or as a baseline assessment, and it is repeated periodically, often every few years, based on a patient’s individual risk factors for oral disease.
This complete radiographic examination generally consists of 18 to 20 total films. The purpose of this extensive series is to capture every tooth in its entirety, along with the bone that anchors it, to identify underlying pathology. The FMS allows for the detection of conditions such as cysts, tumors, bone loss from periodontal disease, and infections at the root tips that would otherwise go unnoticed.
Differentiating Periapical and Bitewing Films
The complete FMS is composed of two distinct types of images: periapical radiographs and bitewing radiographs. Both are intraoral films, meaning the sensor or film packet is placed inside the patient’s mouth during exposure.
Periapical (PA) films are named for the periapex, the area surrounding the root tip (apex) of a tooth. These radiographs are specifically angled to capture the full length of a tooth, extending from the crown to the root tip, and include a few millimeters of the surrounding alveolar bone. PAs are utilized to evaluate the health of the entire tooth and its supporting structures, making them the preferred image type for diagnosing abscesses, root fractures, or changes in bone density related to infection or trauma.
Bitewing (BW) films focus on the crowns of both the upper and lower teeth in the same image, held in place as the patient bites down on a tab. The primary diagnostic focus of bitewings is the interproximal spaces (the areas between adjacent teeth where dental decay frequently begins). Bitewings also provide a clear representation of the height of the alveolar bone, which is a useful indicator for monitoring the progression of periodontal disease.
The Standard Numerical Breakdown of Posterior Films
The standard adult FMS typically contains 18 images, systematically distributed to ensure complete coverage of all dental structures. This 18-film series includes 14 periapical films and four bitewing films. The 14 periapical films are divided between the front (six dedicated to the anterior teeth) and the back (eight dedicated to the posterior teeth).
The number of posterior periapical radiographs in a full mouth survey is typically eight. This number is derived from the four quadrants of the mouth (upper right, upper left, lower right, and lower left posterior segments). Two separate periapical views are required for each of these four quadrants to achieve diagnostic quality without excessive image overlap.
These eight posterior PAs consist of four molar views and four premolar views, with one of each taken in every quadrant. The molar view is centered over the second molar to capture the entire third molar region (if present) and the apices of all molar roots. The premolar view is centered over the first or second premolar and is positioned to include the distal surface of the canine tooth. This separation into two distinct views per quadrant is necessary due to the complex, curved anatomy of the posterior arch, which prevents a single film from capturing all root apices without distortion.
Factors Influencing the Total Film Count
While the 18-film series is the most widely recognized standard, the total number of radiographs in an FMS can vary, sometimes ranging up to 20 images. Some practices utilize a 20-film series, which frequently incorporates six bitewing films instead of four. This addition usually includes two vertical bitewing films, oriented differently to provide a more detailed view of the bone level in patients with advanced periodontal disease.
Anatomical variations can also necessitate adjustments to the standard protocol, potentially altering the final count. Patients with a shallow palate, a strong gag reflex, or bony growths called tori may be unable to tolerate standard sensor placement for certain views. In these cases, the dental professional may need to take alternative projections or substitute views, which might slightly increase or decrease the total number of films required for a complete assessment.
Another factor influencing the decision to take an FMS is the availability of other imaging options. A panoramic X-ray, which captures the entire jaw on a single extraoral film, is sometimes used as a screening tool in combination with four bitewings. While this combination provides a broader overview of the facial structures and is faster for the patient, it does not offer the same level of periapical detail as the FMS. The decision to perform a full 18-film FMS versus an alternative protocol is ultimately determined by the patient’s specific diagnostic needs and the clinical judgment of the practitioner.