Purpose of the study: The aim of the present study was to investigate the marginal bone
height changes around maxillary and mandibular implants supporting all on four fixed detachable
prosthesis after one year follow up
Materials and methods: six completely edentulous patients (4 males and 2 females) received
new conventional maxillary and mandibular dentures and were asked to wear them for 3 months
to enhance adaptation. Four implants were inserted in the maxillary (between the nasal sinuses)
and mandibular (between the mental foramina) arch of each patient according to the All On four
protocol. Implants were immediately loaded with provisional dentures after connection of multiunit
abutments, and after 3 months of osseointegration temporary dentures were replaced by fixed
ceramo-metal prosthesis. Vertical marginal bone loss (VBL) was evaluated at the time of fixed
hybrid prosthesis insertion, 6 and 12 months later using standardized peri-apical radiographs.
Results: Maxillary anterior implants recorded significant higher VBL (P ≤ 0.005) than
mandibular implants after 6 months and 12 months of prosthesis insertion. Also, the maxillary
anterior implants showed significant VBL (P ≤ 0.005) than the posterior implants. For the posterior
implants, no significant difference in VBL was observed between the maxillary and mandibular
implants. For the mandibular implants, no significant difference in VBL between the anterior and
posterior implants was observed.
Conclusion: Within the limitation of this short-term study, taking the small patient cohort into
account, it could be concluded that maxillary anterior implants supporting all on four fixed hybrid
prosthesis are at increased risk for marginal bone loss compared to maxillary posterior implants or
mandibular implants.