• All-ceramic crowns had the lowest incidence of complications (8%)
• Reviewing the literature from 1981 through 2001
• The mean bone loss was 0.9 mm (range from 0.4 to 1.6 mm).
• The mean loss per year in subsequent years was 0.1 mm (range from 0 to 0.2 mm).
• Mandibular implant fixed complete dentures measured an average total bone loss of 0.9 mm after 10 years and a total of 1.2 mm after 15 years.
• Lack of keratinized gingiva and poor oral hygiene were some of the most common reasons for implant loss.

– Categories of complications associated with implant prostheses:

1. Surgical complications

• • Hemorrhage-related complications (24%)
  • Neurosensory disturbance (7%)
  • Mandibular fracture (0.3%)

2. Implant loss

• • Implant loss ranged from a high of 19% with maxillary overdentures to a low of 3% that occurred with both mandibular fixed complete dentures and single crowns.
  •  Implant loss was greater with implants that were 10 mm or less in length (10%) compared with implants greater than 10 mm long (3%)
  •  Type IV bone (16%) compared with types I to III bone (4%).
  • Smokers had greater implant loss (11%) than nonsmokers (5%).
  • Radiation treatments to the maxilla resulted in a greater implant loss (25%) than the mandible (6%).

3. Bone loss

• • The mean bone loss occurring during the first year was 0.9 mm, and the subsequent loss per year after the first year was 0.1 mm.

4. Peri-implant soft tissue complications

• • The most common peri-implant complications were fenestration/dehiscence (7%), gingival inflammation/proliferation (6%), and fistulas (1%).

5. Mechanical complications

• • There were 14 mechanical complications identified in the literature and the incidence ranged from 30% (implant overdenture clip/attachment loss of retention) to 1% (implant fractures)

6. Esthetic/phonetic complications.

• • Esthetic complications occurred with a mean incidence of 10% and phonetic complications were recorded with a mean incidence of 7%.