Purpose: The purpose of this study was to perform a longitudinal follow-up study of implant stability in grafted maxillae with the aid of clinical, radiological, and resonance frequency analysis (RFA) parameters. Materials and Methods:The atrophic edentulous maxillae in 29 patients were reconstructed with free iliac crest grafts using onlay/inlay or interpositional grafting techniques. The endpoint of the resorption pattern in the maxilla determined the grafting technique used. Endosteal implants were placed after 6 months of bone-graft healing. Implant stability was measured four times using RFA: when the implants were placed, after 6 to 8 months of healing, after 6 months and 3 years of bridge loading. Individual checkups were performed at the two later RFA registrations after removal of the supraconstructions (Procera® Implant Bridge, Nobel Biocare AB, Göteborg, Sweden). Radiological follow up of marginal bone level was performed annually.Results: Twenty-five patients remained for the follow-up period. A total of 192 implants were placed and with a survival rate of 90% at the 3-year follow up. Women and an implant position with a class 6 resorption prior to reconstruction were factors with significant increased risk for implant failure (multivariate logistic regression). Twelve of the 20 failed implants were lost before loading (early failures). The change in the marginal bone level was 0.3 ± 0.3 mm between baseline (bridge delivery) and the 3-year follow up. The implant stability quotient (ISQ) value for all implants differed significantly between abutment connection (60.2 ± 7.3) and after 6 months of bridge loading (62.5 ± 5.5) (Wilcoxon signed ranks test for paired data, p = .05) but were nonsignificant between 6 months of bridge loading and 3 years of bridge loading (61.8 ± 5.5). There was a significant difference between successful and failed implants when the ISQ values were compared for individual implants at placement (Mann-Whitney U test, p = .004). All 25 patients were provided with fixed implant bridges at the time of the 3-year follow up. Conclusion:This clinical follow up using radiological examinations and RFA measurements indicates a predictable and stable long-term result for patients with atrophic edentulous maxillae reconstructed with autogenous bone and with delayed placement of endosteal implants. The ISQ value at the time of placement can probably serve as an indicator of level of risk for implant failure.KEY WORDS: autogenous bone graft, edentulous atrophic maxilla, endosteal implants, implant survival, marginal bone level, resonance frequency analysis 46 T he secondary effects of tooth loss are alveolar bone resorption. The loss of alveolar bone compromises soft tissue support and the lower anterior facial height.

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The aim of this prospective study was to compare implants placed in grafted and normal non-grafted maxilla by means of resonance frequency analysis (RFA), clinical stability and implant failure. Twenty-nine patients with severe atrophy of the edentulous maxilla were treated with autogenous bone grafts as onlay (24 patients) or as interpositional grafts in conjunction with a Le Fort I osteotomy (five patients) 6 months prior to placement of 222 implants. Ten non-grafted patients treated with 75 Brånemark implants in the edentulous maxillae served as a control group. RFA was performed at implant placement, abutment connection and after 6 months of bridge loading. Seventeen (8%) implants were lost in the grafted bone and one (1%) in normal bone. RFA revealed a similar pattern in both grafted and normal maxillae, i.e. increasing resonance frequency (RF) with time (Wilcoxon Signed Rank test for paired data). Twenty implants that were rotation mobile (low primary stability) at the time of insertion showed a significantly lower value at implant placement according to RFA (Mann-Whitney U-test, P = 0.020). The RF for the failed implants revealed a tendency towards lower values (Mann-Whitney U-test, P = 0.072), compared to the successful implants. It is concluded that implants placed in grafted bone when using a two-stage technique achieve a stability similar to that of implants placed in normal non-grafted bone.

The purpose of the present study was to examine the criterion-related validity of the sit-and-reach test (SRT) and the modified sit-and-reach test (MSRT) for estimating hamstring flexibility in children and adolescents as well as to determine whether the MSRT is more valid than the SRT. A total of 87 (45 boys and 42 girls) children (6-12 years old) and adolescents (13-17 years old) performed the SRT and the MSRT. Hamstring flexibility was measured with goniometry through the passive straight-leg raise test. Regression analysis was performed to study the association of SRT and MSRT with hamstring flexibility (criterion measure). The SRT was associated with hamstring flexibility in both children (beta=1.089, R (2)=0.281, p=0.001) and adolescents (beta=0.690, R (2)=0.333, p=0.004). The MSRT was also associated with hamstring flexibility in both children (beta=1.296, R (2)=0.298, p<0.001) and adolescents (beta=0.588, R (2)=0.243, p=0.027). It is concluded that the criterion-related validity of the SRT and the MSRT for estimating hamstring flexibility is weak. The present data do not support that the MSRT is a more valid method than the SRT in children and adolescents.

The aim of the present study was to histologically analyse the bone graft-titanium implant interface after six and twelve months of healing for a simultaneous approach and after six months for a delayed approach. For this purpose, screw-shaped c.p. titanium microimplants, 2 mm in diameter and 5 mm long, were placed and retrieved at different time intervals in ten consecutive patients with severely resorbed maxillae and treated with iliac cortico-cancellous bone grafts and titanium implants in a two-stage procedure. The histomorphometrical analyses of ground sections of the specimens showed a higher degree of bone-implant contact and more bone filling the implant threads in the delayed approach microimplants. This was probably due to the partly revascularized grafted bone in the delayed approach being able to respond to the surgical trauma, resulting in interfacial bone formation. It is concluded that the results from the present study favour the use of a delayed approach when using free autogenous bone grafts and titanium implants for reconstruction of the severely atrophied maxilla.

Summary Background Evidence concerning the most appropriate retention strategy after orthodontic treatment is still inconclusive. Objective This trial compares the retentive capacity of vacuum-formed Essix C-retainers (VFR) and bonded cuspid-to-cuspid retainers (CTC) in the mandible 6 and 18 months after orthodontic treatment. Trial design A single-centre two-arm parallel-group randomized controlled trial. Methods This study included 104 adolescent patients, computer-generated randomized with sequentially numbered, opaque, and sealed envelopes into two groups and stratified by gender (52 females and 52 males). The patients were treated with fixed appliances with and without tooth extractions in both jaws and were ready for debond. In the intervention arm, patients received a VFR (n = 52); in the active comparator arm, patients received a CTC (n = 52). Dental casts were obtained at debond (T1), after 6 months (T2), and after 18 months (T3). The casts were digitized. The retentive capacity was evaluated on digital three-dimensional models using Little’s Irregularity Index (LII), overbite, overjet, arch length, and intermolar and intercanine width. Results Baseline values were similar for both groups. Statistically significant increases were noted in LII and overbite, mainly between T1 and T2, but also between T1 and T3 in the VFR group (LII = 0.52 mm, P < 0.001, overbite = 0.51 mm, P < 0.001) and in the CTC group (LII = 0.45 mm P < 0.001, overbite = 0.36 mm, P < 0.001). There were no significant differences between groups. Overjet showed small variations during the observation periods but was overall stable within and between groups after 18 months. Arch length decreased slightly in both groups after 6 and 18 months. Intermolar and intercanine widths remained stable after debond. Limitations Patients, operator, and outcome assessor could not be blinded due to the study design. Conclusions VFR and CTC have the same retention capacity in the mandible after 6 and 18 months. Relapse mainly occurs during the first 6 months of retention, but the post-treatment changes are generally small. Shorter VFRs in the mandible do not cause negative vertical effects. Part-time wear regimen is not associated with increased relapse. Trial registration NCT03070444.

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