International Journal of Oral Implantology, 01/2013

Purpose: To evaluate the efficacy of long implants (10-16 mm) inserted in maxillary sinuses augmented according to a lateral approach versus short (8 mm) implants placed in crestally augmented sinuses, early loaded after 45 days. Materials and methods: Forty partially or fully edentulous patients having 3 to 6 mm of residual crestal height and at least 4 mm in thickness below the maxillary sinuses were randomised according to a parallel group design to receive either one to three 10 to 16 mm-long hydroxyapatite-coated implants (20 patients) after lateral sinus lifting with 50% anorganic bovine (Bio-Oss) and 50% autogenous bone, or 8 mm implants (20 patients) after crestal sinus lifting with autogenous bone. Implants were submerged and left healing for 45 days before loading the implants. Within 1 week after abutment connection, implants were loaded with screw-retained full acrylic provisional prostheses. Definitive metal-ceramic prostheses were provisionally cemented 45 days after abutment connection. Outcome measures were prosthesis and implant failures, any complications, and radiographic periimplant marginal bone level changes. In addition, the stability of individual implants was assessed with Osstell and Periotest at abutment connection (baseline), and at 1 and 5 years after loading by blinded outcome assessors. All patients were followed up to 5 years after loading. Results: One patient dropped out (death) from the longer implant group. One implant failed in the short implant group versus 5 implants in 3 patients of the longer implant group. The difference was not statistically significant. Four complications occurred in 4 patients of the short implant group versus 8 complications in 7 patients of the long implant group, the difference being not statistically significantly different. However, the 2 major postoperative complications occurred in the longer implant group: 1 abscess, and 1 sinusitis that led to the complete failure of the treatment in 2 patients (4 implants lost). A total of 0.72 mm of peri-implant marginal bone was lost after 5 years at long implants and 0.41 mm at short implants, the difference between the two groups was statistically significant (P = 0.028). Osstell values increased and Periotest decreased over time and there were no differences between groups at any time points. Conclusions: In atrophic maxillary sinuses with a residual bone height of 3 to 6 mm, 8 mm short implants placed in a simultaneously crestally lifted sinus might be a preferable choice than a 1-stage lateral sinus lift for placing longer implants since they appear to be associated with less morbidity. If these implants are placed with an insertion torque >35 Ncm and are joined together under the same prosthesis, they can be early loaded at 6 weeks. Keywords: bone augmentation, bovine anorganic bone, early loading, short dental implants, sinus lift

Purpose: To compare 100% deproteinised bovine bone matrix (DBBM) grafts (test group) with 100% autogenous bone (AB) grafts (control group) for lateral maxillary sinus floor elevation in a parallel group, superiority, randomised controlled trial. Materials and methods: Patients with 1 to 3 mm of residual bone height below the maxillary sinus were randomised for sinus floor elevation with DBBM and AB grafts and simultaneous implant placement. Randomisation was computer generated with allocation concealment by sealed envelopes and the radiographic examiner was blinded to group assignment. The abutment connection was performed 8 months after surgery and insertion of the provisional prostheses was performed 9 months after surgery. Outcome variables were implant failures, prosthetic failures, complications, chair time, postoperative pain and radiographic bone level 6 months after loading. Results: Forty patients were randomised: 20 (32 implants) to the DBBM group and 20 (27 implants) to the AB group. One patient from the AB group dropped out. Two implant failures occurred in the DBBM group and no implant failure occurred in the AB group (P = 0.4872). All of the planned prostheses could be delivered. One complication occurred in the DBBM group and 2 in the AB group (P = 0.6050). Chair time was shorter for the DBBM group, with a difference of 27.3 minutes (P = 0.0428). Pain difference measured with a visual analogue scale for 6 days post-surgery was 0.2 in favour of the DBBM group (P = 0.6838). The difference in vertical bone height was 0.0 mm (95% CI -1.1, 1.1; P = 0.9703) and the difference in marginal bone level was 0.3 in favour of AB (95% CI -0.3, 0.9; P = 0.3220). Conclusions: No differences apart from chair time were observed when comparing DBBM and AB grafts with simultaneous implant placement in sinus elevation. Keywords: Bio-Gide, Bio-Oss, bone substitutes, dental implants, sinus floor augmentation

Purpose: This prospective study was designed to assess the long-term outcome of immediately loaded zygomatic implants placed in atrophic maxillae. Materials and methods: Forty-two consecutively treated patients received 81 zygomatic implants and 140 conventional implants for oral rehabilitation and were followed for 5 years. Complete arch rehabilitation was accomplished in 37 patients and partial arch rehabilitation in 5 (one zygomatic implant in combination with two conventional implants). Outcome measures were prosthetic and implant failures, and complications. Results: Twelve zygomatic and 22 conventional implants in 6 patients were not reviewed as patients were lost to follow-up. One zygomatic implant was removed at the 3-year follow-up visit because of lack of osseointegration and disturbances around the zygomatic region. The success rate of zygomatic implants was 98.5% (68/69). Six conventional implants were lost, with a success rate of 94.9% (112/118). One of the definitive prostheses was changed after 4 years of follow-up. Six complications occurred during the entire follow-up period. Conclusions: The 5-year prognosis was found to be good for immediately loaded zygomatic implants together with conventional implants in severely resorbed maxillae. Keywords: dental implants, edentulism, prospective study, zygomatic implants

Purpose: To report the outcome of implant-supported fixed partial prostheses with cantilevers at 5 years after loading. Material and methods: A total of 174 patients, 106 females and 68 males with 225 implants (maxilla: 149; mandible: 76), supporting 191 fixed dental prostheses (maxilla: 125; mandible: 66) were included. Inclusion criteria were patients rehabilitated with partial prostheses with cantilevers and sufficient amount of bone to place implants of at least 7 mm long. Primary outcome measures were prosthesis and implant success as well as biological and mechanical complications. The secondary outcome measure was peri-implant marginal bone loss. Results: Sixteen patients with 21 implants dropped out (9.2% of patients; 9.4% of implants). Three implants were lost in 3 patients. Two prostheses were lost rendering a survival estimation of 99.0% at 5 years (Kaplan-Meyer). Overall mean (standard deviation) bone level was 0.15 mm (0.34 mm), 1.56 mm (0.88 mm) and 1.88 mm (1.05 mm) at implant insertion, and 1 and 5 years after implant placement, respectively. The frequency at patient level of biological and mechanical complications was 2.9% and 27.6%, respectively. Conclusions: Within the limitations of this study, it is possible to conclude that it is viable to use fixed implant-supported partial rehabilitations with a cantilever, judging by the 99% prosthetic success rate at 5 years. However, there is a relatively high frequency of complications to cope with in these rehabilitations. Keywords: cantilever, complications, dental implants, dental prosthesis

Purpose: This retrospective cohort study evaluated metal-cast silan-coated three-unit resin-bonded fixed dental prostheses (RBFDPs) after at least 16 years and identified covariates affecting the survival. Materials and methods: A total of 37 patients with 42 RBFDPs placed by one operator between 1986 and 1993 were recalled and invited for a clinical examination in conjunction with scrutiny of clinical records. Results: Thirteen RBFDPs were lost to follow-up after an average of 58.5 months (SD = 39.4) and considered unaccounted for, 10 failed prior to the research recall and had a survival of 130.2 months (SD = 68.3), and 19 were still in function with a mean survival of 236.2 months (SD = 24.7). The estimated, cumulative survival via Kaplan-Meier analysis of the total number of 43 RBFDPs resulted in 95% (SE = 4%) survival after 5 years, 88% (SE = 6%) after 10 years and 66% (SE = 9%) after 20 years. No covariates were found having a significant effect on the survival rates. Conclusions: RBFDPs have an acceptable clinical survival although lower than conventional FDPs and single implants. They should therefore be considered as a temporary provision, as a provision for geriatric or medically-compromised patients because of the simplicity of the provision, as a less expensive alternative, and for patients where the amount of bone loss impedes the use of dental implants. Keywords: Maryland bridge, prosthetic complications, prosthetic survival, resin-bonded bridge, resin-bonded fixed dental prosthesis

Purpose: In this anatomical study, we compared the diagnostic accuracy of rotational panoramic radiography (OPG), computed tomography (CT) and cone beam computed tomography (CBCT) to the actual anatomical situation. Materials and methods: Dental images were taken of 10 human cadaver heads. Thereafter, they were prepared and measured. The height of the alveolar ridge to the mandibular canal was compared with the prior images taken. The deviation from the anatomical situation was calculated for each imaging technique. Results: In the group of OPG images, there was a median of 2.3 mm distortion ranging from -0.2 to 5.7 mm in the vertical plane compared to the actual situation found during dissection. If steel balls were used during OPG, the median distortion was lowered to 0.2 mm, but the width of -1.6 to 3 mm was still quite extensive. CT images showed a mean distortion of -0.2 mm and a width of -1.5 to 1.3 mm. The mean distortion of the CBCT images was similar to the one found in CT, namely -0.3 mm with a range from -1.5 to 0.8 mm. Conclusions: The results show that OPG using steel balls as a calibration reference seems reliable in a standard situation. In more difficult cases, modern three-dimensional techniques should be used to additionally determine available bone volume. Keywords: dental imaging, dental implantation, dental implants