International Journal of Oral Implantology, 03/2011

Purpose: To evaluate the efficacy of flapless versus open flap implant placement in partially edentulous patients. Materials and methods: Forty patients with two separate edentulous areas characterised by residual bone at least 5 mm thick and 10 mm in height had these sites randomised following a split-mouth design to receive at least one implant to each side after flap elevation or not. Implants were first placed in one site, and after 2 weeks in the other site freehand. Implants inserted with a torque >48 Ncm were immediately loaded with full occluding acrylic temporary restorations. Definitive single cemented crowns or screw-retained metal ceramic fixed dental prostheses were delivered after 2 months. Outcome measures were prosthesis and implant failures, complications, postoperative swelling and pain, consumption of analgesics, patient preference, surgical time, marginal bone level changes, and implant stability quotient (ISQ) values. Results: Seventy-six implants were placed flapless and 67 after flap elevation. In the flapless group, four flaps had to be raised to control the direction of the bur, whereas one haemorrhage and one fracture of the buccal bone occurred in two patients of the flap elevation group. Four implants did not reach the planned stability (three belonging to the flapless group) and they were all immediately replaced by larger diameter ones. After 1 year, no drop-outs occurred. Two definitive bridges could not be placed when planned (one in each group) and two crowns had to be remade (one in each group). Two implants failed in each group, all in different patients. There were no statistically significant differences for prosthetic and implant failures, complications, ISQ values and marginal bone levels between groups. However, flapless implant placement required significantly less operation time (17 minutes less, saving almost two-thirds of the time for implant placement), induced less postoperative pain, swelling, analgesic consumption and was preferred by patients. Mean ISQ values of both groups significantly decreased over time. Conclusions: Implants can be successfully placed flapless and loaded immediately, reducing treatment time and patient discomfort. Keywords: dental implants, flapless, immediate loading, partial edentulism, randomised controlled trial

Purpose: To evaluate whether short (5 to 8.5 mm) dental implants could be a suitable alternative to longer (>11.5 mm) implants placed in atrophic maxillae augmented with autogenous bone for supporting dental prostheses. Materials and methods: Twenty-eight patients with fully edentulous atrophic maxillae having 5 to 9 mm of residual crestal bone height at least 5 mm thick, as measured on computerised tomography scans, were randomised into two groups either to receive 4 to 8 short (5 to 8.5 mm) implants (15 patients) or autogenous bone from the iliac crest to allow the placement of at least 11.5 mmlong implants (13 patients). Bone blocks and the windows at maxillary sinuses were covered with rigid resorbable barriers. Grafts were left to heal for 4 months before placing implants, which were submerged. After 4 months, provisional reinforced acrylic prostheses or bar-retained overdentures were delivered. Provisional prostheses were replaced, after 4 months, by definitive screw-retained metal-resin cross-arch fixed dental prostheses. Outcome measures were: prosthesis and implant failures, any complications (including prolonged postoperative pain) and patient satisfaction. All patients were followed for 5 months after loading. Results: All patients could be rehabilitated with implant-supported prostheses and none dropped out. One bilateral sinus lift procedure failed due to infection, though short implants could be placed. One implant failed in the augmented group versus 2 short implants in 2 patients. All failures occurred before loading. Significantly more complications occurred in augmented patients: 8 complications occurred in 5 augmented patients (all complained of pain 1 month after bone harvesting from the iliac crest). No complications occurred in the short implant group. All patients were fully satisfied with the treatment and would do it again. Conclusions: This pilot study suggests that short implants may be a suitable, cheaper and faster alternative to longer implants placed in bone augmented with autogenous bone for rehabilitating edentulous atrophic maxillae. However, these preliminary results need to be confirmed by larger trials with follow-ups of at least 5 years. Keywords: augmentation, RCT, short implants

Purpose: To evaluate the clinical outcome of 2 implants versus 4 implants placed flapless in fully edentulous mandibles and immediately restored with metal-resin screw-retained cross-arch prostheses. Materials and methods: Sixty patients from two different centres were randomised: 30 to the allon- 2 group and 30 to the all-on-4 group. To be immediately loaded, implants had to be inserted with a minimum torque of 40 Ncm. Outcome measures were prosthesis and implant failures, and biological and biomechanical complications. Results: Flaps were raised in 18 patients. Two implants in 2 patients did not reach the planned insertion torque and were immediately replaced by larger diameter ones. Four months after loading, no drop-out or implant failure occurred. One biomechanical complication occurred in the all-on-2 group versus 4 in the all-on-4 group. There were no statistically significant differences between groups for complications. There were no differences between centres. Conclusions: These very preliminary results, just 4 months after loading, suggest that immediately loaded mandibular cross-arch fixed dental prostheses can be supported by only 2 dental implants. Longer follow-ups (around 10 years) are needed to understand whether cross-arch mandibular prostheses can be successfully supported by only 2 dental implants. Keywords: dental implants, flapless, immediate loading, randomised controlled trial

Purpose: The aim of this study was to compare the histological presentation of local mandibular bone grafts fixed with one screw or two screws in buccal anterior maxillary augmentation procedures. Study design: Local buccal defects of the anterior maxilla were reconstructed in 12 patients (mean age 47 ± 17 years, range 18 to 67 years) using autogenous cortical bone grafts from the mandibular retromolar area. Patients were randomised using envelopes containing study identification numbers. After randomisation, two screws were used to fix the bone graft in six patients, and one screw was used in the other six patients. Four months later during implant placement, a bone biopsy was taken with a trephine. The biopsies were processed for light microscope evaluation. Results: The mean total bone volume varied from 35.8% to 72.4% (mean 51.1% ± 13.4%) in the one-screw group and from 28.7% to 56.6% (mean 40.8% ± 11.5%) in the two-screw group. The mean non-vital bone volume ranged from 0% to 2% (mean 0.9% ± 0.9%) in the one-screw group and from 0% to 8.9% (mean 2.2% ± 3.7%) in the two-screw group. The mean osteoid volume ranged from 2.2% to 7.3% (mean 5.4% ± 1.7%) in the one-screw group and from 2.0% to 16.4% (mean 7.3% ± 5%) in the two-screw group. Conclusion: No significant histological differences were found between the use of one or two screws to fix an autologous bone graft in buccal bone grafting procedures prior to implant placement. Keywords: bone reconstruction, onlay bone grafts, ramus grafts, screw fixation

Purpose: To report the long-term outcome of immediately loaded implants in the rehabilitations of completely edentulous maxillae with different classifications. The secondary aim was to evaluate the influence of possible explanatory variables on the incidence of biological and mechanical complications. Material and methods: In total, 221 patients were consecutively included and classified into four groups that allowed implant placement in a vertical position: Group 1 (bone available up to first molar), Group 2 (bone available up to second premolar), Group 3 (bone available up to first premolar) and Group 4 (bone available up to canine). Outcome measures were prosthesis and implant survival, and biological and mechanical complications. Results: A total of 995 implants were placed. Eighteen patients (8% of the sample) dropped out of the study. After 5 years, three patients lost their prosthesis due to implant failures, giving a survival rate of 98.6%; 25 patients lost 41 implants, giving a survival rate of 88.7% (25/221) and an implant-specific survival rate of 95.8% (41/995). According to the edentulism classification, the patient-specific survival rate after 5 years was 78.6% for Group 1, 89.3% for Group 2, 92.4% for Group 3 and 91.7% for Group 4. In total, 129 biological complications occurred affecting 129 implants (13%) in 66 patients (30%). Smoking was identified as a risk factor for the incidence of biological complications with an OR of 3.03 (95% CI 2.03-4.56; P 0.0001), while 'gender' (male; OR = 0.56; 95% CI 0.37-0.85; P = 0.007) was a factor that had a protective effect. A total of 170 mechanical complications occurred, affecting 170 implants (17%) in 71 patients (38%). Bruxism was identified as a risk factor for the incidence of mechanical complications with an OR of 60.95 (95% CI 21.40-173.54; P 0.0001), while a Group 2 edentulism classification had a protective effect for the incidence of mechanical complications with an OR of 0.22 (95% CI 0.07-0.71; P = 0.011). Conclusions: It is a viable treatment option to rehabilitate completely edentulous maxillae using four implants or more to support a fixed prosthesis. Keywords: All-on-4, completely edentulous, dental implants, immediate loading, maxilla

Purpose: To evaluate the outcome of immediately loaded cross-arch bridges 4 months after loading. A second aim was to compare survival rates of implants placed in healed versus fresh extraction sites. Materials and methods: In total, 105 consecutive patients about to have their mandibles rendered fully edentulous (mean extractions per patient: 6.1 teeth) received four to six implants each (total number = 448), which were immediately placed in healed sites (266 implants, 59%) or fresh sockets (182 implants: 41%). Immediate loading of provisional prostheses was performed and all patients were followed-up for 4 months. The success criteria included prosthesis success, assessment of individual implant stability and complications. Results: No patient dropped out and all 105 patients received definitive fixed prostheses after four months of loading. The overall implant survival rate after four months was 98.2%. Eight implants were lost in eight patients (8%). Four of them were inserted in fresh extraction sockets (2.2%) and four in healed sites (1.5%). No significant difference (P = 0.4990) was found for implants placed into healed sites versus fresh extraction sites. No complications were reported. Conclusions: Immediate implant placement and loading resulted in high implant as well as prosthetic survival rates. Placement in healed or fresh extraction bone sites did not influence implant survival. Keywords: cross-arch bridge, full rehabilitation, immediate implant placement, immediate loading, mandibular edentulous patients, provisional screw-retained prostheses

Aim: To retrospectively evaluate the 1-year outcome of implant therapy involving various types of localised lateral alveolar ridge and/or sinus floor augmentation procedures performed before implant placement. Materials and methods: Forty-seven patients were consecutively treated with oral implants on average 6.5 months after bone grafting. A total of 82 regions were augmented and 151 implants were inserted. All regions were augmented with autogenous bone harvested intraorally. Block grafts (13 regions, 16%), particulate grafts (25 regions, 30%), and a combination of block and particulate grafts (44 regions, 54%) were used. The particulate grafts were sometimes mixed with less than 25% anorganic porous bovine-derived bone mineral (28 regions, 34%). Finally, the grafted areas were in most cases covered by either an expanded polytetrafluoroethylene (e-PTFE) membrane (58 regions, 71%) or a resorbable collagen membrane (11 regions, 13%). The selection of the performed procedure was based upon the experience of the surgeon and thorough evaluation of each case. All surgical procedures were performed by two oral and maxillofacial surgeons with extensive clinical experience with regenerative procedures. The outcome measures were complications related to the augmentation procedure, prosthesis survival, implant survival and peri-implant marginal bone loss. Results: No dropouts occurred. Complications occurred in eight patients (17%) after bone harvesting: temporary paraesthesia (two patients, 4%), membrane exposure (five patients, 11%) and acute sinusitis (one patient, 2%). Membrane exposure was exclusively observed when an e-PTFE membrane was used. However, the subsequent implant placement was not compromised. Regarding the patient with acute sinusitis, the graft was removed and implant/prosthesis placement was not possible. No further prosthesis failures occurred during the 1-year follow-up period. Thus, the prosthesis survival was 99%. The implant survival involving sinus lift, lateral augmentation, and combined sinus lift and lateral augmentation was 91%, 97%, and 100%, respectively. A total of four patients (9%) experienced implant failure. The mean peri-implant marginal bone loss at patient level involving sinus lift, lateral augmentation, and combined sinus lift and lateral augmentation was 0.60 mm (range: 0.31-1.25), 0.31 mm (range: 0.00-0.75) and 0.41 mm (range: 0.00-1.25), respectively. No technical complications were observed. Moreover, no episodes of peri-implant mucositis or peri-implantitis were registered. Conclusions: Localised lateral alveolar ridge and/or sinus floor augmentation performed before implant placement seems to be associated with few complications after 1 year. However, it should be emphasised that all surgical procedures were selected and performed by oral and maxillofacial surgeons with extensive clinical experience in the field of regenerative procedures. Keywords: alveolar ridge augmentation, bone transplantation, dental implants, retrospective study

Purpose: The aim of the present cross-sectional study was to propose a classification system based on a cross-sectional survey of zygomatic implant cases. Materials and methods: Cone beam computerised tomography (CBCT) postoperative images and clinical intra-surgery photographs of 200 sites corresponding to 100 patients, treated with a total of 198 zygomatic implants in the maxilla according to an anatomy-driven prosthetic approach, were reviewed with regard to anatomy and pathway of the zygomatic implant body. The patients were consecutively selected independently of the type of surgery performed, with the unique requirement of a post-surgical CBCT performed at the moment of selection. Of special interest was the morphology of the lateral sinus wall, residual alveolar crest and the zygomatic buttress. An attempt was made to divide the patients into groups, describing typical anatomies and implant pathways. Results: Five basic skeletal forms of the zygomatic buttress-alveolar crest complex and subsequent implant pathways could be identified in a sample of 100 patients. Out of them, 62% were female and 38% male, with ages varying between 36 and 83 years (mean age 59.6, SD: 9.67). The five groups were classified as ZAGA 0 to 4 representing 15%, 49%, 20.5%, 9% and 6.5% of the studied sites, respectively. Intra-individual anatomical differences affecting the zygomatic buttress-alveolar crest complex was also found in 58% of the patients. Conclusions: Five typical anatomical and implant pathway situations could be identified. A classification system comprising five groups named ZAGA 0 to 4 is proposed. Anatomical intra-individual differences were also found in the 58% of the studied population. It is believed that the proposed classification system is useful for categorising zygomatic implant cases for therapy planning and for scientific follow-up purposes. Keywords: atrophic maxilla, dental implants, extra-sinus pathway, zygomatic implants