Five-year results with fixed complete-arch mandibular prostheses supportedby 4 implants

This study examined whether it is possible to restore an edentulous mandibl e with a complete-arch fixed prosthesis retained by only 4 implants without decreasing the survival rate. One hundred nineteen patients received compl ete-arch mandibular prostheses retained by 4 implants. Most patients were f ollowed for 3 years or more. All patients followed a routine protocol, incl uding annual check-ups and regular radiographic examinations. Twenty-one pa tients dropped out Radiographic measurements used the threads of the implan ts as a basis for comparison. No indication was found that the number of su pporting implants could have influenced the observed frequency of technical and surgical complications. Three implants were lost, 2 after 1 year and 1 after 5 years. A statistically significant difference in bone loss between the mesial and distal implants was found. The number of fractured resin te eth in mandibular prostheses was higher when patients had an implant-suppor ted prosthesis in the maxilla. The present study revealed an implant surviv al rate of 98.6% after 5 years. Therefore, it was concluded that there may not be a need for more than 4 implants to support a fixed mandibular prosth esis, when implants at least 10 mm long can be used.