Nine patients (five males and four females) were included in this study who had long-term (10-15 years) of long-span rigid mandibular fixed prostheses that may have led to radiographic changes around the supporting teeth. The treatment plans included the removal of the long-span fixed rigid prostheses followed by restoring the patients with segmented implant-supported prostheses. In order to digitally measure the mandibular flexure, reference markers were adhered to the prostheses, and intraoral scans were obtained before and after splitting the preexisting prostheses at the minimum and maximum mouth opening. The distances between the markers were measured, and mandibular flexure was calculated by subtracting the distance between the markers during the maximum mouth opening from the minimum mouth opening. An independent sample T-test was used to compare mandibular flexure before and after splitting the long-span fixed prostheses.

Inclusion Criteria:

• full-arch mandibular single fixed prostheses that served for many years (average 12 years) opposed by natural dentition.
• Patients were free from any systemic or debilitating diseases such as bone diseases, diabetes melilites, or blood dyscrasias.

Exclusion Criteria:

• patients with healthy fixed full-arch prosthesis
• patients with segmented prosthesis
• patients with systematic debilitating diseases.
• Patients with temporomandibular joint dysfunction, maxillofacial surgeries, or mandibular trauma.

All had the entire mandibular natural dentition (6-8 abutments) splinted with a single-unit metal-ceramic (long-span fixed prosthesis). All of them suffered from different negative consequences of their one-piece fixed restorations. The retrospective collection of the patient's data was tabulated and analyzed. Nine patients were included in this study. Five males and four females, with an age range of 50-76 years were enrolled in this study.

study protocol, raw data,statistics