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One-year outcome of implants strategically placed in the retrocanine bone triangle.
No full textBACKGROUND:
Implant treatment in the partially edentulous maxilla is often challenging because of minimum bone volumes in distal direction.
PURPOSE:
The aim of this study was to evaluate, after 1 year of loading, the outcome of three-unit fixed partial dentures supported by two implants in the retrocanine triangle.
MATERIALS AND METHODS:
Twenty patients with atrophic posterior maxillae participated in the study. A total of 40 implants were placed in residual bone anterior to the sinus wall and posterior to the canine. Implant angulations and lengths were chosen to match as much as possible boundaries of the available bone. After a 6-month healing period, three-unit, screw-retained, fixed partial dentures were delivered. The patients were clinically and radiographically reexamined after 1 year of loading.
RESULTS:
All the implants survived at the end of the follow-up. No differences in bone level changes resulted between axial and tilted implants. No biological or mechanical complications were recorded.
CONCLUSIONS:
Within the limitations of this short-term study on relatively few patients, a positive outcome was seen for three-unit fixed partial dentures supported by two implants. Retrocanine placement of implants with carefully planned lengths and angulations might be an alternative to grafting procedures for restoration of atrophic posterior maxillae
One-year outcome of narrow diameter blasted implants for rehabilitation of maxillas with knife-edge resorption
No full textOBJECTIVES: This study aimed at assessing the clinical outcome of narrow diameter implants in the treatment of knife-edge edentulous maxillas of adequate bone height but inadequate width (class IV of Cawood and Howell).
MATERIAL AND METHODS: Twelve consecutive patients (eight women and four men, mean age 58 years) with class IV atrophic edentulous maxillas were included in the study. Seventy-three microthreaded TiO(2)-blasted implants were placed and the resonance frequency measured. All the implants had a diameter of 3.5 mm. After 6 months of submerged healing, fixed implant-supported prostheses were delivered to the patients and resonance frequency and radiographic examinations performed. After the first year of loading, the implant outcome was again evaluated clinically, radiographically and with resonance frequency analysis.
RESULTS: All the implants were followed up to 1 year of loading and their survival rate was 100%. Bone loss after 1 year of loading was (mean+/-SD) 0.30+/-0.13 mm. Stability values were (mean+/-SD) 63+/-5.8 ISQ at placement, 60+/-4.7 ISQ at the abutment connection and 61+/-5 ISQ after 1 year of loading. A significant difference resulted between placement and abutment connection values (P=0.03).
CONCLUSIONS: According to the present study, narrow implants may be used to restore edentulous maxillas with atrophies of class IV of Cawood and Howell. When planning the treatment of edentulous maxillas with such a resorption pattern, this possibility has to be considered as an alternative to more demanding grafting techniques
Correlation of radiographic fractal analysis with implant insertion torque in a rabbit trabecular bone model
No full textPURPOSE: Insertion torque and resonance frequency analysis are currently used to assess the initial biomechanical competence of an implant. It would be advantageous to have this information during treatment planning. Therefore, the aim of this study was to assess the correlation between a descriptor of bone architecture, namely the fractal analysis of plain radiographs, and implant insertion torque and resonance frequency.
MATERIALS AND METHODS: Sixteen femoral condyles from adult rabbits were subjected to conventional radiography and then received an implant each. The final insertion torque and resonance frequency were recorded for each implant. The fractal dimension of the bone area corresponding to the osteotomy was calculated using a box-counting algorithm. The Spearman test was used to evaluate the correlation between the variables examined.
RESULTS: A linear correlation was observed between fractal dimensions and insertion torque values (rs = 0.704; P = .007). No correlation resulted between fractal dimension and resonance frequency. In addition, a receiver operating characteristic analysis defined a fractal dimension breakpoint of 1.83 to detect soft bone quality, as defined by insertion torque values, with a sensitivity of 80%.
CONCLUSIONS: Given its correlation with insertion torque, the box-counting fractal dimension could be useful to evaluate bone quality at implant sites preoperatively and noninvasively. Further studies are needed to confirm the same accuracy for human bone
Damping factor for monitoring the bone interface at dental implants
No full textThe aim of this study is to investigate whether the damping of osseointegrated implants, as measured quantitatively with the Osstell TM equipment, is related to the fractal dimension of peri-implant bone. Fifty-five maxillary implants in function for 3 years before the present study were investigated. Two OsstellTM measurements were obtained for each implant with the transducer oriented first palatally and then distally. Using the half-power bandwidth method, the damping was calculated from the frequency/amplitude plot obtained from the OsstellTM. Damping data were then related to the fractal dimension of peri-implant bone. Fractal dimensions were calculated using a box-counting algorithm on digitally processed intra-oral radiographs of the implants. A Spearman's test was used to verify the correlation between damping and fractal dimension values. All the implants were clinically stable and free from symptoms. The mean ISQ was 63 for the palatal orientation and 71 for the distal orientation. The mean fractal dimension was 1.47; the mean damping value for palatal orientation was 12.3%, while that for the distal orientation was 8.2%. No significant correlation was found. Damping values, measured at peri-implant bone, were found not to be related to a radiographic parameter of trabecular bone pattern like the fractal dimension. The clinical implication would be that OsstellTM graphs displaying distinct or more rounded peaks might both indicate a stable implant as long as the associated implant stability quotients are in the range of satisfactory values proposed in the literature
An eleven-year case report of an avulsed maxillary central incisor after delayed replantation
No full textA 12 year-old girl presented with an avulsed maxillary central incisor for a trauma occurred two days earlier. The avulsed tooth was endodontically treated and replanted. Regardless of the ankylosis and replacement root resorption the tooth was retained for a very favourable nine-year period after trauma. In addition no severe infraposition occurred. When the extraction was necessary, despite the slight atrophy, as a result of compromised alveolar bone development due to ankylosis, an implant-supported crown was placed as definitive rehabilitation without recourse to bone augmentation procedures. In conclusion, delayed replantation in children will require long-term therapeutic commitment. In favourable cases, tooth with delayed replantation might be retained for a very long time thus avoiding the bone atrophy that would have accompanied early tooth loss and, consequently, reducing grafting requirements when a definitive implant-supported restoration will be required
Implant placement in combination with sinus membrane elevation without biomaterials: a 1-year study on 15 patients
No full textAbstract
Background: Membrane elevation in combination with implant placement without biomaterials is a rather new technique proposed for sinus lifting. Purpose: This study assessed the clinical outcome of such technique during the first year of loading. Material and Methods: Fifteen patients with a mean residual bone height of 6.2 mm were consecutively recruited for sinus lifting. After opening a replaceable bone window, the membrane was dissected from the sinus walls. A total of 28 implants were placed in the residual crest and they kept the membrane lifted upwards. After window repositioning, the flap was sutured. A 6-month healing period was allowed. Patients were re-examined after 12 months of loading. Results: All the implants survived at the end of the follow-up. The 5.5 mm mean bone reformation was significantly lower than the 8.2 mm mean membrane lift achieved after implant placement. Regeneration at the distal surface of the most posterior implants was significantly less than at other aspects. The height of membrane lift was not correlated with the amount of regenerated bone. Conclusions: All of the 28 implants placed in combination with sinus membrane elevation were stable during the first year of loading. No extra costs for biomaterial or morbidity for bone harvesting were necessary
Cement thickness at implant-supported single-tooth Lava assemblies: a scanning electron microscopic investigation.
No full textOBJECTIVES:
The fit of implant-supported single-tooth Lava zirconia assemblies was investigated in this study. The implant-abutment interface, the interface between the metallic and the zirconia portion of the abutment and the interface between Lava abutments and copings were evaluated. The adaptation of titanium abutments to implants and Lava copings was investigated as a control.
MATERIAL AND METHODS:
Twenty implants were randomly assigned and connected to Lava abutments (group 1) or titanium abutments (group 2). All specimens were subjected to scanning electron microscopy (SEM) analysis of the fixture/abutment fit. Afterwards, specimens were luted to Lava copings and subjected to a SEM evaluation of the marginal external adaptation of the abutments with the copings. Finally, the samples were embedded in resin, sectioned and subjected to SEM analysis of the following interfaces; group 1: titanium/zirconia interface (between the constitutive components of the Lava abutment) and the zirconia/zirconia interface (between the Lava abutment and the coping); group 2: the titanium/zirconia interface (between the titanium abutment and the Lava coping). Non-parametric analysis of variance and a post hoc test were used for statistical analysis.
RESULTS:
Significant differences emerged in the cement thickness between titanium and zirconia components of the Lava abutments as compared with the thickness measured at the interface between Lava copings and the abutments investigated. No differences were found in cement thickness between Lava copings and the two different abutments.
CONCLUSIONS:
When Lava abutments are used, the most critical cement thickness is the internal interface between its titanium and zirconia components. Lava coping adaptation for both Lava and titanium abutments is within the clinical acceptable range
Influence of transducer orientation on Osstell stability measurements of osseointegrated implants
No full textBACKGROUND: Resonance frequency (RF) analysis is frequently used to monitor implant stability in patients. The influence of transducer orientation on RF of implants placed in jawbone has not been evaluated.
PURPOSE: The aim of this study was to evaluate to what extent transducer orientation influences RF. The second aim was to evaluate if measurements taken with any particular orientation would best relate to marginal bone levels.
MATERIALS AND METHODS: Nine patients edentulous in the upper jaw received 55 implants 3 years before this study. They underwent clinical and radiographic evaluation. Using Osstell (Integration Diagnostics AB, Göteborg, Sweden), four RF measurements were made for each implant. Measurements were obtained with the transducer cantilever placed buccally (B), distally (D), palatally (P), and mesially (M).
RESULTS: All implants were clinically stable. Significant differences resulted between the measurements perpendicular to the bony crest (B, P) and the parallel ones (M, D). A tendency of negative correlation was found between marginal bone levels and implant stability quotient (ISQ) measurements; however, this correlation was not statistically significant.
CONCLUSIONS: In conclusion, when measuring the RF of dental implants using the Osstell, it has to be taken into account that the transducer orientation influences the measurement. It seems therefore advisable to standardize the orientation. Moreover, although there was a tendency, any statistical significant correlation between ISQ values and marginal bone levels could not be established
Stability values of titanium dioxide-blasted dental implants in edentulous maxillas: a 3-year pilot study.
No full textThe purpose of this follow-up study was to measure the resonance frequency of Astra Tech TiO(2) blasted implants at second surgery, at one and 3 years of loading. Secondly, it was investigated whether resonance frequency at second surgery could discriminate between successful implants and those that will fail over a 3-year period. Fifty titanium dioxide-blasted implants in eight consecutive patients with edentulous maxillas seeking fixed rehabilitations, were included in the study at abutment connection after 6 months of healing. Resonance frequency, clinical and radiographic records were obtained at abutment connection and after one and 3 years of loading. The cumulative survival rate after 3 years was 100%. The mean resonance frequencies were 65 +/- 4.8 implant stability quotient (ISQ) at second surgery (range 50-78 ISQ), 66 +/- 3.4 ISQ after 1 year of loading (range 53-76 ISQ) and 64 +/- 3.8 ISQ after 3 years of loading (range 53-77 ISQ). No significant differences resulted between these three time points. The marginal bone level decrease of 0.6 mm between the second surgery and the 3-year follow-up was observed. One limitation of the study is that no late failures were encountered in this relatively small sample. Consequently, it was not possible to establish a cut-off ISQ for implants that, after abutment connection, would maintain their stability over a 3-year period. Nevertheless, it might be concluded that following the first year of loading the range of 53-76 ISQ describes the stability of osseointegrated Astra Tech TiO(2) blasted implants
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