About this trial

Group I (control) Edentulous mandible receiving all on four fixed mandibular prosthesis using conventionally screw retained multiunit abutments.

Group II (intervention) Edentulous mandible receiving all on four fixed prostheses using OT bridge attachments system.

For both groups, the implant sites will be prepared aided by the surgical template. 4 implants with length 11-13 mm will be placed, two anterior implants will be aligned in an axial orientation and two posterior implants will be distally aligned according to the all-on-four concept in the inter foraminal area. Implants will be ideally placed at bone level.

For both groups:

After implant placement and surgical guide removal, healing abutments ( will be connected during healing periods (eight to twelve weeks).

Group I ( control) After eight to twelve weeks from implant placement, multiunit abutments with appropriate heights and angulations will be connected to the implants.

Group II ( intervention) After eight to twelve weeks from implant placement, narrow- and low-profile OT Equator abutment will be screwed onto the implants according to the manufacturer.

marginal bone changes and prosthetic complications are the outcomes Radiographic follow up will be performed for marginal bone changes Serial of standardized digital periapical radiographs using will be taken at the time fixed prosthesis insertion (baseline), 3,6,9,12 months.

Type and incidence of prosthetic complications for the prothesis for each group will be evaluated in 3, 6,9 and 12 months, these complications included: loosening or fracture of the prosthetic screw, prosthesis mobility and fracture of the prosthesis.

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

Aged 40 years or older.

Sufficient inter -arch space not less than 13 mm.

Good oral hygiene

Minimum bone height 10 mm and minimum bone diameter should be 6 mm

Disqualifiers

General contraindications for oral surgery

Heavy smokers (greater than 20 cigarettes a

Local acute or chronic infections

Substance abuse (drugs or alcohol)

Trial design

Design model

Parallel

Treatments tested in this trial

patients reciveing all on 4 fixed mandibular prosthesis usimg conventionally screw retained multiunit abutments
Procedure/Surgery
Multiunit abutments is considered a gold standard screw retained abutments. Multi-unit abutments are used to correct for varying heights among the implants, to establish a level restorative platform for the prosthesis, as well as to situate the implant connection even with or just below the gingival surface. Also they are used to correct the angulation of implants, helping to keep the screw access holes away from the facial surfaces of the restoration, and facilitate the path of insertion of prosthesis.
all on 4 fixed mandibular prosthesis using OTbridge attachment system
Procedure/Surgery
The OT bridge attachment system introduced by (Rhein 83) is a global, well-established system used in the removable prosthetic protocols, the presence of seeger acetal ring placed between the sub-equatorial area of the OT Equator and the cylindrical "Extragrade" abutment compensates the space between the extragrade abutment and the OT equator attachment correcting the minor misalignments that produced during the prosthetic procedure and resulting in more passive fit.

Treatment groups

20 Participants

are divided into 2 treatment groups

Group A: All-on-four fixed mandibular prosthesis using conventionally screw retained multiunit abutments.Active comparator 1 intervention

Group B: All-on-four fixed mandibular prosthesis using OT bridge attachment systemExperimental treatment 1 intervention

Trial outcomes

Primary outcomes

1

marginal bone loss

Radiographic follow up will be performed for marginal bone changes. Serial of standardized digital periapical radiographs using; long cone paralleling technique, XCP periapical film holder and an individually constructed radiographic acrylic template will be taken at the time fixed prosthesis insertion (baseline), 3,6,9,12 months. The software of the Digora system will be used for evaluation of the marginal bone changes. Lines parallel to the long axis of the mesial and distal surface of each abutment will be made. The distance in mm from the crest of alveolar bone to the apex of the tooth will be measured and the marginal bone changes in the subsequent measurements will be calculated.

Time frame

1 year follow up

Secondary outcomes

1

prosthetic complications

Type and incidence of prosthetic complications for the prothesis for each group will be evaluated in 3, 6,9 and 12 months, these complications included: loosening or fracture of the prosthetic screw, prosthesis mobility and fracture of the prosthesis