Milled in Versus Round Bar for Mini-implant Retained Mandibular Overdentures :A8 Year Retrospective Study of Peri-implant Bone Changes and Posterior Ridge Resorption

Study Design:

A convenience sample of 18 completely edentulous participants were selected for this retrospective study from patients originally available at the start of the trial. The patients were informed about the study objectives and they were signed an informed consent and the protocol were approved by the Ethical Committee, Faculty of Dentistry, Mansoura University.

The patients were equally divided into two groups at the start of the trial. The patients (average age 45-60 years) were selected for this study from outpatient clinic of Removable Prosthodontics Department, Faculty of Dentistry, Mansoura University.

Patients' criteria:

Completely edentulous maxillary and mandibular residual alveolar ridges covered with healthy mucosa without any remaining roots or local inflammation as detected by digital panoramic x-ray and clinical examination.. Anterior mandibular bone length was sufficient to allow proper implant placement as assessed by digital panoramic radiograph. Patients were of class I Angel's maxillo-mandibular relation with at least 22mm of restorative space allow for bar construction as detected by tentative jaw relation, and good bone quality (classes 1 to 3 according to Lekholm and Zarb). Participants with diabetes mellitus, osteoporosis, immunological dysfunction, anticoagulant medication, radiation to the head and neck region, smoking habits ,and systemic diseases that interfere with implants osseointegration were excluded from the study .For each patient, overdentures assisted by four splinted mini dental implants According to type of bar attachment used for splinting the four MDIs, patients were divided into two equal groups where: Group I: Received milled-in bar and Group II: Received round bar joint attachment. O-Ball impression copings were snapped directly onto each O-Ball MDI Implant. A Pick-Up closed tray impression technique was made using polyether impression material. MDI Lab Analog was pressed into the coping until a snap fit was observed .The impression was poured into dental stone to form a stone model for scanning Bar construction