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Purpose: To evaluate if a different morphology of the implant-abutment connection (internal vs. external hexagon) is able to condition the behaviour of hard and soft peri-implant tissues., Materials and Methods: Twenty patients with significantly unfavourable prognoses for their residual maxillary or mandibular dentitions were selected and rehabilitated with immediately loaded fixed full-arch rehabilitations in two different centres. Four to six implants with identical macro- and micro-topography were inserted in each arch: external hexagon implants (EHC) in one randomly selected side of the dental arch and internal hexagon implants (IHC) in the other side. Primary outcome measures were the success rates of the implants and prostheses. Any technical and biological complication was recorded. Secondary outcome measures were: peri-implant marginal bone level (MBL) changes, Plaque Index (PI), probing depth (PD) and bleeding on probing (BoP), evaluated at implant insertion and at 3, 6 and 12 months post-loading., Results: Forty-three EHC and 40 IHC implants were inserted in 20 patients. No patients dropped out. Two implants failed; one IHC after 3 months and one EHC after 6 months in two different patients (difference IHC vs. EHC at patient level: 0.06%; 95% CI: -1.9 to 2.1; P = 0.99). No prosthesis failed. No biological complications were identified and three loose prosthetic abutment screws were identified in three different patients (two EHC and one IHC); difference at patient level IHC vs. EHC: 2.1% (95% CI: -0.8 to 5; P = 0.43). Overall marginal bone loss was not significantly different between the two treatment groups (EHC vs. IHC) at any time point. The mean difference of bone levels between EHC and IHC was 0.25 mm (95% CI: -0.18 to 0.69) at implant placement. Mean difference between IHC and EHC was -0.01 mm (95% CI: -0.34 to 0.36) at 3 months, 0.13 mm (95% CI: -0.48 to 0.22) at 6 months and 0.11 mm (95% CI: -0.45 to 0.25) at 12 months. All the implants showed good periodontal health at the 1-year-in-function visit, with no statistically significant differences between groups. At 12 months mean (± standard deviation) PI was 2 (± 1.5) for the EHC and 1.85 (± 1.58) for the IHC group (P = 0.57) with a mean difference between the two groups of 0.15 (95% CI: -0.56 to 0.85). Mean PD was 2.23 mm (± 0.52) for the EHC and 2.10 mm (± 0.39) for the IHC group (P = 0.39), with a mean difference between the two groups of 0.12 mm (95% CI: -0.08 to 0.33). At 12 months 41.4% of EHC and 43.6% of IHC implants presented no BoP (mean difference: -2.2%, 95% CI: -24.0 to 19.3; P = 0.51). No significant effect of centres over all outcomes was identified (P = 0.71 for MBL, P = 0.14 for PI, P = 0.14 for PD and P = 0.20 for BoP)., Conclusions: On the basis of the present trial the two types of implant connections were clinically reliable. After 12 months in function, both implants provided good clinical outcomes, without statistically significant differences between the two groups., Competing Interests: Conflict of interest statement: The authors declare that this study was partly funded by Sweden & Martina.

Purpose: To estimate implant survival and peri-implant bone resorption around long vs normal-length implants in full-arch immediate loading rehabilitation of maxillary arches of low bone quality (D4)., Materials and Methods: A total of 45 patients received two mesial normal-length (10 to 15 mm) or longer (18 to 20 mm) implants and two long (18 to 20 mm) distally tilted implants. Differences in bone resorption at 24 months were assessed using the Mann-Whitney U Test., Results: At the 24-month follow-up, no significant differences were found in survival (global cumulative survival rate: 98.9%) or bone resorption (mean: 1.1 mm) between long and normal implants (P = .053)., Conclusion: At 24 months, the use of long implants provides favorable survival and bone maintenance results in the immediate loading rehabilitation of low-quality maxillary arches.

This prospective study reports the 6-year outcomes for patients rehabilitated with an immediate loading protocol of the maxilla (Columbus Bridge Protocol). In this study, 164 implants were inserted in 37 patients and loaded within 24 to 36 hours. Four implants failed during the first 6 months. At the 6-year follow-up, a mean bone loss of 1.52 mm was found. Significantly (P < .0083) less bone loss was found next to tapered implants compared with cylindric implants and next to machined collar implants compared with full acid-etched implants (P < .0083). No significant differences in bone loss were found in tilted versus upright implants or in mesial versus distal implant sites. In addition, there were no significant differences relating to either the degree of abutment angulation or the reason for tooth loss.

Purpose: This study compared the surgical protocol efficacy of immediate and delayed implant loading in edentulous maxillae opposed by natural or restored mandibular dentitions over an observational period of 6 years or longer. The selected outcome determinants included individual implant survival data, progressive measurements of peri-implant bone resorption, prosthodontic survival and success data, and report of complications., Materials and Methods: A convenience sample of 49 patients requiring fixed implant-supported maxillary prostheses was split into two groups. The test group (34 patients) was treated according to the Columbus Bridge Protocol, which prescribes the insertion of four to six implants, including distally tilted implants, and load within 24 hours. The control group (15 patients) was treated via a two-stage surgical protocol of 6 to 9 straight implants that were loaded a mean 8.75 months after stage-one implant surgery. Two hundred sixty implants (test: n = 163, control: n = 97) were placed, and all subjects were ultimately treated with screw-retained full-arch prostheses., Results: Two patients dropped out (one in the test group and one in the control group) by the time of the scheduled sixth annual visit. The other patients were followed up for 75.2 months (range: 72 to 90 months). At the 6-year follow-up, no differences in implant cumulative survival rates were found between groups. Significantly less bone loss was found in the test group (mean: 1.62 mm) compared with the control group (mean: 2.44 mm). All of the original prostheses were maintained throughout the study's observation period and were functioning satisfactorily at each patient's last recall appointment., Conclusion: Patients who received immediate and delayed implant loading in their edentulous maxillae demonstrated similar survival outcomes. However, less marginal bone loss was recorded around the immediately loaded implants over the study's 6-year follow-up period.

Purpose: The aim of this study was to compare survival rates and radiographic outcomes of immediate and delayed implant loading in edentulous maxillae., Materials and Methods: Forty-nine patients in need of maxillary full-arch treatment were randomized into two groups: test group (n = 34) treated following the Columbus Bridge Protocol with 4 to 6 implants loaded within 24 hours and a control group (n = 15) treated following the ad modum Branemark protocol with 6 to 9 implants loaded a mean 8.75 months after surgery. Two hundred sixty implants (test: n = 163, control: n = 97) were placed, and subjects were treated with screw-retained full-arch prostheses. Bone levels were measured at baseline and at 1, 2, and 3 years and analyzed using repeated-measures analysis of variance., Results: All patients appeared at all scheduled recall visits. No differences in cumulative survival rates were found between groups at 36 months. Ten implants (6.1%) failed in the test group; four (4.1%) failed in the control group. At 36 months, no prosthetic failures were detected. Significantly less bone loss was found in the test group at all time intervals (P < .001). The average bone level from the implant-abutment connection was 1.3 mm in the test group and 1.9 mm in the control group at 12 months, 1.5 mm and 2.2 mm at 24 months, and 1.6 mm and 2.3 mm at 36 months, respectively., Conclusion: In the edentulous maxilla, the Columbus Bridge Protocol involving immediate loading of implants placed in both healed and fresh extraction sites exhibited equivalent implant survival and less marginal bone loss at 3 years compared to the conventional two-stage delayed loading protocol. Int J Prosthodont 2011;24:294-302.

Statement of Problem: The benefits and limitations of jaw treatments with tilted versus vertical implants, as well as prosthesis design with and without posterior cantilevers, have been extensively discussed. However, biomechanical advantages associated with cantilevers in fixed dentures (FDs) and tilted implants in the maxillae are less well documented., Purpose: The purpose of this study was to compare and analyze, via 3-dimensional (3-D) finite element analysis, stresses transmitted to tilted versus vertical implants and the surrounding periimplant bone in the maxillae., Material and Methods: A 3-D edentulous maxillary model was created using customized computer software (FEMAP 8.3). Four implants were virtually placed in the premaxilla and splinted with an FD. Keeping the prosthesis length constant, 4 different configurations were evaluated with the distal implants inclined 0, 15, 30, and 45 degrees; cantilever extensions were 13, 9, 5, and 0 mm, respectively. A vertical load (150 N) was applied to the distal portion of the posterior cantilevers. Von Mises' stress values transmitted to periimplant bone and at the metal framework of FDs on implants were evaluated in cancellous and cortical bone., Results: The maximum stresses recorded in periimplant bone for the vertical implants were 75.0 MPa (distal implants), 35.0 MPa (mesial implants), and 95.0 MPa for the metal frameworks. Tilted distal implants, with consequent reduction of the posterior cantilevers, resulted in decreased stress values for all of the variables: -12.9%, -18.3%, and -11.5% for the 15-degree configuration; -47.5%, -52.6%, and -31.3% for the 30-degree configuration; and -73.5%, -77.7%, and -85.6% for the 45-degree configuration, Conclusions: Finite element analysis data regarding rehabilitation of atrophic maxillae revealed that tilted distal implants, rigidly splinted with an FD, decrease stress in the periimplant bone and frameworks. This treatment modality seems to be a valid therapeutic alternative to conventional maxillary fixed complete prostheses supported by vertical dental implants with posterior cantilevers., (Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Statement of Problem: Immediate occlusal loading of dental implants in the edentulous mandible has proven to be an effective, reliable, and predictable procedure. There is little long-term data available on similar treatments in the edentulous maxilla., Purpose: The purpose of this study was to evaluate the 12-month implant survival after immediate loading of 4 to 6 implants with fixed screw-retained prostheses in edentulous maxillae., Material and Methods: Twenty-one patients, edentulous or with remaining teeth to be extracted in the maxilla, received 4 to 6 implants (n=111). The patients were restored with screw-retained fixed provisional prostheses supported by palladium-alloy frameworks within 24 hours after surgery. Insertion torques for implants were at least 40 Ncm. Implants, grouped as tapered or cylindrical screws, were placed in healed bone or extraction sockets. Implants were also classified as either vertical or off-angle. Definitive prostheses were placed after a mean healing time of 18 weeks. Radiographic examinations were made at the time of placement of provisional prostheses and 12 months later. Between-groups bone resorption was compared using 2-way ANOVA (alpha=.05)., Results: The mean follow-up time for all of the patients was 20 months (range, 13 to 28 months). The cumulative implant survival rate at the 12-month follow-up visits (after surgery) was 92.8%; the prostheses survival rate was 100%. No significant differences were found between the survival of tapered or cylindrical screw-type implants placed in postextraction sockets versus those in healed edentulous sites or between vertical and off-angle placed implants. Eight implants failed during the first 3 months, 5 of which were the most distal implants. The mean reduction in marginal bone height over the 12-month observation period was 0.84 mm (CI 95%; 0.68-0.99 mm)., Conclusions: In this study with 12-month follow-up, 4 to 6 implants were sufficient to successfully support fixed implant screw-retained prostheses in the edentulous maxillae of 21 patients.

Tilted implants have been proposed as an alternative to traditional protocols in the rehabilitation of edentulous maxillae. The aim of this meta-analysis was to evaluate the outcomes of upright and tilted implants supporting full-arch fixed dentures for the immediate rehabilitation of edentulous maxillae, after at least 1 year of function. An electronic search of databases and a hand search of relevant journals in oral implantology were performed according to PRISMA guidelines through August, 2011. The literature search yielded 1,069 articles. Eleven articles were available for analysis. A total of 1,623 implants (778 tilted, 845 upright) were inserted into the maxillae of 324 patients. Seventeen tilted (2.19%) and 16 upright implants (1.89%) failed during the first year. No significant difference in failure rate was found between tilted and upright implants (p value = 0.52). Marginal bone level results were obtained from 6 studies. A non-significant mean difference between tilted and upright implants was found with regard to bone loss. Tilted implants demonstrated a favorable short-term prognosis in full-arch immediate loading rehabilitations of the maxillae. Randomized long-term trials are needed to better elucidate long-term success of tilted vs. upright-positioned implants. [ABSTRACT FROM PUBLISHER]