Simplified methods of implant treatment in the edentulous lower jaw: a 3-year follow-up report of a controlled prospective study of one-stage versus two-stage surgery and early loading.

BACKGROUND: Interest in the use of one-stage surgery and immediate loading of oral implants has lately been increasing. PURPOSE: The aim of this study was to compare the 3-year results of one-stage surgery versus two-stage surgery, early loading versus loading after a 3-month healing period, and the use of one-piece implants versus the use of two-piece implants. MATERIALS AND METHODS: The study included 108 patients with edentulous mandibles. Each patient was treated with four Brånemark System implants (Nobel Biocare AB, Göteborg, Sweden) and with full fixed prostheses. Patients were consecutively treated and were distributed in four groups: group A (one-stage surgery), group B (control group with two-stage surgery), group C (one-piece implants), and group D (early loading). In groups A and B Brånemark Standard implants and standard abutments were used. In group C the conical one-piece Brånemark implant was used, and in group D the patients had Brånemark System Mk III implants together with multiunit abutments. All patients were observed for 3 years. RESULTS: Of the 432 inserted implants, 24 were lost. Survival rates in the three experimental groups ranged from 93.2 to 93.3% whereas the survival rate in group B (the control group with two-stage surgery) was 97.5%. The differences between the groups were not statistically significant. The changes in marginal bone level were measured from fixture insertion to the final follow-up at 3 years. The bone loss in group D (early loading) was significantly less than in group B (the control group) whereas there were no differences in marginal bone change between the other groups. CONCLUSIONS: Early loading seemed to give good results in the anterior part of the mandible. The survival rate of the early-loaded implants did not significantly differ from that of implants inserted with the conventional two-stage procedure, but the mean marginal bone loss around the surviving implants was less with early loading.

A three-year follow-up report of a comparative study of ITI Dental Implants and Brånemark System implants in the treatment of the partially edentulous maxilla.

BACKGROUND: Many longitudinal studies of different implant systems have been published but few controlled randomized investigations have been reported. A 1-year report of a comparative study of ITI Dental Implant System implants (Straumann AG, Waldenburg, Switzerland) and Brånemark System implants (Nobel Biocare AB, Gothenburg, Sweden) has been published by the present authors. This paper is a 3-year follow-up of that randomized study. PURPOSE: The aim of the study was to compare the outcome of fixed partial prostheses supported by ITI or Brånemark implants. The outcome was evaluated primarily in terms of survival rates and changes in marginal bone level. MATERIAL AND METHODS: The study group comprised 28 patients with anterior residual dentition in the maxilla. The patients were provided with two to four implants on each side of the dentition and were randomly allocated to Brånemark implants or ITI implants; 77 ITI implants and 73 Brånemark implants were inserted. After 6 months abutment connections were made to both ITI and Brånemark implants. All patients were provided with fixed partial prostheses of gold-ceramic. The patients were followed up annually with clinical and radiographic examinations for 3 years RESULTS: Two Brånemark implants and two ITI implants were lost. The Brånemark implants were lost before loading whereas the ITI implants were lost because of periimplantitis. The survival rate for both groups was 97.3%. The mean marginal bone level of the Brånemark implants was situated 1.8 mm from the reference point at both the baseline and the 3-year examinations. The corresponding values for the ITI implants were 1.4 mm at baseline and 1.3 mm after 3 years. There was no significant difference between the implant systems with regard to bone level or bone level change. A steady state of the marginal bone level was calculated to have been reached after 3 years for 95.5% of the Brånemark implants and 87.1% of the ITI implants. Periimplantitis (infection including pus and bone loss) was observed with seven ITI implants but with none of the Brånemark implants. This difference was statistically significant. CONCLUSIONS: No statistically significant differences were found between the implants studied, except for the frequency of periimplantitis, which was higher for the ITI implants. The survival rates were high, and the marginal bone loss was small for both systems.

Simplified methods of implant treatment in the edentulous lower jaw. Part II: Early loading.

BACKGROUND: Most implant treatment is performed with a two-stage surgical procedure. A disadvantage of these implant treatments is that they are time-consuming. PURPOSE: The aim of the present study was to evaluate the results of early loading in the edentulous mandible and to compare those results with treatment results of one-stage surgery followed by a healing period and with two-stage surgery. MATERIAL AND METHODS: The material comprises four treatment groups with a total of 108 patients with edentulous lower jaws and 432 implants. All patients were treated with Brånemark implants (Nobel Biocare AB, Gothenburg, Sweden) with a turned surface and fixed prostheses in the lower jaw, supported by four implants. The patients in group A were treated with a one-stage procedure, a two-piece implant, and a 3-month healing period before loading. Group B (control group) had a two-stage procedure, a two-piece implant, and a 3-month healing period. Group C had a one-stage procedure, a one-piece implant, and a 3-month healing period. Group D was treated with a one-stage surgical procedure, a two-piece implant, and early loading (within 3 weeks). All patients were provided with a Procera Implant Bridge (Nobel Biocare) with a framework made by computer-assisted milling of one piece of pure titanium. All patients have been followed up for 1 year. RESULTS: The survival rates were 93.2 to 93.3% in the experimental groups and 97.5% in the control group. The difference was not statistically significant. The measurements of the marginal bone level demonstrated a mean bone loss of 0.8 mm between fixture insertion and the 1-year examination in patients with early loading (group D) whereas the bone loss in patients who underwent a healing period before loading was 1.3 to 1.6 mm. The difference between the control group and the group with early loading was significant. CONCLUSIONS: Survival rates for patients treated with a one-stage procedure were lower than survival rates for patients treated according to a "classical concept," but the differences were not statistically significant. There was no difference between treatment results with one-piece and two-piece implants. The implant loss in patients with early loading was probably caused by overloading, and careful supervision of occlusal loading is recommended. Early loading gave significantly less marginal bone loss when compared with two-stage surgery.

Simplified methods of implant treatment in the edentulous lower jaw. A controlled prospective study. Part I: one-stage versus two-stage surgery.

BACKGROUND: The original protocol for Brånemark System implants in the mandible was a two-stage procedure with 3 months healing time. With five or six implants and a cast framework of gold, the treatment is rather expensive, and simplified methods would be desirable. PURPOSE: The goal of this controlled serial study was to investigate the outcome of a simplified procedure with one-stage surgery, four Brånemark implants, shortened healing time, and a new titanium-acrylic fixed full prosthesis. MATERIALS AND METHODS: Eighty-two patients were treated in three different groups at two specialist centers. All patients were provided with four implants, loaded with a Procera All-in-One bridge (Nobel Biocare, Gothenburg, Sweden) after 12 weeks. In group A (n = 30), one-stage surgery was combined with two-piece implants. In group B (n = 30), the control group, two-stage surgery and two-piece implants were used. In group C (n = 22), one-stage surgery was combined with one-piece implants. Marginal bone level was rated from radiographs at implant insertion, at baseline, and after 1 year. RESULTS: The survival rate after 1 year for group A was 93.3%; group B, 97.5%; and group C, 93.2%. The differences were not statistically significant. Between fixture insertion and baseline, the average bone loss for group A was 1.2 mm; group B, 1.3 mm; and group C, 1.3 mm. No complications in the form of bridge loosening or acrylic fractures were recorded during the first year. CONCLUSIONS: The survival rates and the marginal bone changes did not differ significantly between the one-stage groups and the control group. The survival rate and the marginal bone changes were similar for one-piece and two-piece implants. Four implants were sufficient to support full fixed prostheses in the mandibles. The Procera All-in-One bridges proved to be of high quality, and no complications were experienced. key words: endosseous implants, nonsubmerged implants, one-piece implants, prospective clinical study, submerged implants

Nonsubmerged and submerged implants in the treatment of the partially edentulous maxilla.

BACKGROUND: Dental implants vary in design and surfaces. In addition, different surgical techniques have been used for implant insertion. The ITI Dental Implant System (Straumann AG, Waldenburg, Switzerland) has always required a one-stage technique, whereas the Brånemark System (Nobel Biocare AB, Gothenburg, Sweden) requires a two-stage technique. PURPOSE: The aim of this study is to compare the outcome of fixed partial bridges in the maxilla supported by both ITI and Brånemark implants in a split-mouth design. MATERIALS AND METHODS: Twenty-eight patients with a residual anterior dentition in the maxilla were included in this split-mouth study. The Brånemark implants were used on one side and the ITI implants on the other side of the residual dentition according to a randomization procedure. A blocking size of four was used, giving equal probability of placing ITI or Brånemark implants in the right or left side of the jaw. The surgical and prosthetic procedures followed the guidelines given by the manufacturers. The prosthetic treatment with the two-implant systems was performed at the same time, and for that reason the healing period was 6 months for both systems. The observation period for all patients was 1 year after loading. RESULTS: Two Brånemark implants (in one patient) were lost before loading, and one ITI implant was lost 1 year after loading. There was no significant difference in survival rate. Radiographic examination of the bone level was performed at the time of delivery of the bridge and after 1 year. The mean marginal bone level at baseline was situated 1.9 mm from the reference point for the Brånemark implants and 1.5 mm for the ITI implants. With regard to the insertion depth used, these bone levels indicate that bone loss had taken place before baseline. However, between baseline and the 1-year examination, there was no significant change of the marginal bone (0.2 +/- 0.08 mm at the Brånemark implants and 0.1 +/- 0.11 mm at the ITI implants). The difference between results with the two implants was not statistically significant. Crater-form bone destructions were seen at some ITI implants, indicating periimplantitis. However, at only two implants were there clinical signs of periimplantitis. CONCLUSIONS: No significant difference in survival rate or in marginal bone change could be demonstrated between the two systems. At some ITI implants (18%), crater-form bone loss was observed.