| Summary: |
Aim: This retrospective study aimed to determine the consequence of early cover
screw exposure on peri-implant marginal bone level.
Material and Methods: Sixty Astra Techs MicroThread implants installed in
partially edentulous jaws were compared: 20 implants were placed following
a two-stage procedure and were unintentionally exposed to the oral cavity (two-stage
exposed), 20 implants were placed following a two-stage procedure and were
surgically exposed after a subgingival healing time of 3–6 months (two-stage
submerged), and 20 implants were placed following a one-stage surgical protocol
(one-stage). Digital radiographs were taken at implant placement for all implants, and
after abutment surgery for the two-stage exposed and two-stage submerged groups or
after 3 months for the one-stage group. Bone loss mesially and distally was measured
with an on-screen cursor after calibration.
Results: Mean bone re-modelling was 1.96mm (range: 0.2–3.2 mm) around the
two-stage exposed implants, 0.01mm (range: 0.0–0.3 mm) around the two-stage
submerged implants and 0.14mm (range: 0.0–1.2 mm) around the one-stage implants.
Conclusion: The unintentional perforation of two-stage implants resulted in
significant bone destruction, probably because the biological width was not
considered.
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