To Örebro University

Purpose: The purpose of this study was to evaluate and compare the long-term performance of fixed partial prostheses supported by 2 or 3 implants.

Materials and methods: All patients treated with fixed partial prostheses supported by either 2 or 3 implants during the period 1985 to 1998 were included in this retrospective report. Annual clinical follow-up examinations were performed, with special attention to stability of the prostheses and peri-implant and occlusal conditions. Radiographic examination was performed when the prostheses were delivered (year 0) and subsequently at 1-year, 5-year, and 10-year examinations.

Results: A total of 178 patients had received fixed partial prostheses (FPPs) during this period of whom 123 (77 women and 46 men) were available for follow-up (mean age = 65 years, range 32-91). These 123 patients received a total of 146 implant-supported FPPs (63 two-implant- and 83 three-implant-supported) supported by 375 implants. The mean observation periods for the 2- and 3-implant-supported restorations were 9.6 years and 9.4 years (range, 5 to 18 years), respectively. Survival rates for the 2- and 3-implant-supported prostheses were 96.8% and 97.6%, respectively. The implant survival rate after loading was 98.4% for both groups. The mean bone loss at the 5-year follow-up was 0.3 mm for the 2 groups. No significant differences in bone loss (P > .05), implant failure rate (P > .05), or incidence of mechanical complications (P > .05) were found between the 2 prosthesis designs. The complications differed, significantly, with more loose gold and abutment screws in the 2-implant-supported group (P < .05) and more porcelain fractures in the 3-implant-supported group (P < .05).

Conclusion: The 2-implant-supported partial prostheses exhibited long-term clinical performance comparable to prostheses supported by 3 implants.

Purpose: The aim of this investigation was to evaluate the clinical outcome of two different surgical protocols in the edentulous mandible: submerged and nonsubmerged. Further, the Paragon dental implant with a titanium plasma-sprayed surface was evaluated.

Materials and methods: Twenty-nine consecutively treated patients with 168 implants supporting fixed prostheses were included. All but 3 patients were provided 6 implants, placed via nonsubmerged healing on one side and submerged healing on the other. Data were collected from patient records and radiographs. Twenty-four patients participated in the 5-year clinical follow-up examination.

Results: After 5 years, all patients still had their mandibular fixed prostheses in function. Cumulative survival rates were 100% for prostheses and 99.4% for implants. However, 3 implants fractured in 1 patient. One submerged implant was lost before loading but no further implants were lost during follow-up. The radiographic bone loss was small for all implants with a mean of 0.14 mm (standard deviation [SD]: 0.37) at 1 year and 0.42 mm (SD: 0.48) at 5 years for nonsubmerged implants and 0.17 mm (SD: 0.32) at 1 year and 0.51 mm (SD: 0.33) at 5 years for submerged implants. Nineteen implants (including the 3 that fractured) presented annual bone loss exceeding 0.2 mm after the first year, yielding a cumulative success rate of 86.2% after 5 years.

Conclusion: Single-stage surgery was shown to have the same predictability as two-stage surgery in the anterior edentulous mandible. Paragon implants with a titanium plasma-sprayed surface showed a fracture rate of 2.2% and a success rate of 86.2% after 5 years.

This study examined whether it is possible to restore an edentulous mandible with a complete-arch fixed prosthesis retained by only 4 implants without decreasing the survival rate. One hundred nineteen patients received complete-arch mandibular prostheses retained by 4 implants. Most patients were followed for 3 years or more. All patients followed a routine protocol, including annual check-ups and regular radiographic examinations. Twenty-one patients dropped out. Radiographic measurements used the threads of the implants as a basis for comparison. No indication was found that the number of supporting 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 teeth in mandibular prostheses was higher when patients had an implant-supported prosthesis in the maxilla. The present study revealed an implant survival 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 prosthesis, when implants at least 10 mm long can be used.

Background: New computer numeric controlled (CNC)-milled frameworks for implant-supported prostheses have been introduced. However, no data are available on the precision of fit of these new frameworks.

Purpose: The purpose of this study is to evaluate the precision of fit of a new CNC-milled framework technique (I-Bridge, Biomain AB, Helsingborg, Sweden) using Brånemark System (Nobel Biocare AB, Göteborg, Sweden) and NobelReplace (Nobel Biocare AB) system implants.

Materials and methods: Ten test frameworks were fabricated for one master model for each implant system. Five additional frameworks were fabricated for five different models simulating clinical cases as controls (Brånemark System). The distortion of implant center point positions was measured in x-, y-, and z-axes and in three dimensions by using a contact-type coordinate measuring machine and a computer program developed specifically for this purpose. Mann-Whitney U-test was used to compare differences of distortion within and between the groups.

Results: The maximal distortion in arch width (x-axis) and curvature (y-axis) was within 71 and 55 microm for all frameworks, respectively. The mean distortion in absolute figures in x-, y-, z-axes and three dimensions was for "clinical control" frameworks 23, 26, 4, and 34 microm as compared with less than 12, 12, 2, and 17 microm for Brånemark and NobelReplace frameworks, respectively. Control frameworks showed significantly (p < .05) greater mean and range of distortions in x- and y-axes and in three dimensions compared with test frameworks.

Conclusion: All measured frameworks presented signs of misfit, indicating that no framework had a "passive fit." Frameworks produced in a more routine clinical environment seem to present greater levels of distortion as compared with frameworks produced in a strict test situation. However, all measured frameworks presented levels of precision of fit within limits considered to be clinically acceptable in earlier studies of frameworks placed on abutments.

Background: New computer numeric controlled (CNC)–milled frameworks for implant-supported prostheses have been introduced. However, no data are available on the precision of fit of these new frameworks.

Purpose: The purpose of this study is to evaluate the precision of fit of a new CNC-milled framework technique (I-Bridge®, Biomain AB, Helsingborg, Sweden) using Brånemark System® (Nobel Biocare AB, Göteborg, Sweden) and NobelReplace™ (Nobel Biocare AB) system implants.

Materials and Methods: Ten test frameworks were fabricated for one master model for each implant system. Five additional frameworks were fabricated for five different models simulating clinical cases as controls (Brånemark System). The distortion of implant center point positions was measured in x-, y-, and z-axes and in three dimensions by using a contact-type coordinate measuring machine and a computer program developed specifically for this purpose. Mann–Whitney U-test was used to compare differences of distortion within and between the groups.

Results: The maximal distortion in arch width (x-axis) and curvature (y-axis) was within 71 and 55 µm for all frameworks, respectively. The mean distortion in absolute figures in x-, y-, z-axes and three dimensions was for “clinical control” frameworks 23, 26, 4, and 34 µm as compared with less than 12, 12, 2, and 17 µm for Brånemark and NobelReplace frameworks, respectively. Control frameworks showed significantly (p < .05) greater mean and range of distortions in x- and y-axes and in three dimensions compared with test frameworks.

Conclusion: All measured frameworks presented signs of misfit, indicating that no framework had a “passive fit.” Frameworks produced in a more routine clinical environment seem to present greater levels of distortion as compared with frameworks produced in a strict test situation. However, all measured frameworks presented levels of precision of fit within limits considered to be clinically acceptable in earlier studies of frameworks placed on abutments.