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At least 19 recordsLinked to original sources
PubMed2001

Bone loading pattern around implants in average and atrophic edentulous maxillae: a finite-element analysis.

Introduction: Oral implants placed in the maxilla, especially the posterior region, have a lower success rate than those placed in the mandible. Poor bone quantity and quality have been suggested as a reason for this differential success rate. Objective: The purpose of this study was, therefore, to evaluate stress and strain distributions around loaded implants in the normal and atrophic maxilla by finite-element (FE) analyses. Material: FE models of a solitary implant were generated to determine stresses and strains in the bone adjacent to the implant surface under loading conditions. Study design: Different bony situations and implant lengths were used in a FE model. Static loads were applied axially and the resulting stresses and strains calculated. Results: Bone quality and quantity play a major role in decreasing bone strains adjacent to the implant surface under loading. It was found that stresses were more homogeneously distributed when more spongy bone was present. Decreased bone height was found to have less pronounced effects on strain and stress alterations than poor bone quality. Atrophic bony dimensions in combination with poor bone quality were associated with surface strains exceeding physiological levels (>6000 microstrains). Conclusion: Our investigation indicates that supraphysiological bone strains adjacent to the implant surface should be expected under mechanical loading in the atrophic maxilla. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗
PubMedDate not supplied

A 3-arm study of early loading of rough-surfaced implants in the completely edentulous maxilla and in the edentulous posterior maxilla and mandible: results after 1 year of loading.

PURPOSE: The aim of the present prospective study was to evaluate the concept of early loading of rough-surfaced implants in the completely edentulous maxilla and in the edentulous posterior mandible and maxilla. MATERIALS AND METHODS: Fifty-four consecutive patients were treated. Twenty patients were completely edentulous in the maxilla (group A), 19 patients were edentulous in the posterior left and/or right maxilla (group B), and 15 patients were edentulous in the posterior left and/or right mandible (group C). One patient in group B and 5 in group C were bilaterally treated. Two hundred thirty-four solid screw-type, sandblasted, large-grit, acid-etched (SLA) ITI implants were placed, 58 (25%) immediately after tooth extraction. Mean placement torque and standard deviations were measured at all sites. Sixty fixed prostheses were delivered after a mean delay of 9 days (range, 4 to 22 days). Mean marginal bone reduction was measured after 1 year of loading. RESULTS: Two implants were lost (0.9%), 1 before functional loading and 1 after 1 year. All other implants were clinically stable, with a mean marginal bone loss of 0.75 mm (+/-1.3 mm). Marginal bone loss ranged from 0 to 3.5 mm. Mean placement torque on implants placed in healed bone or immediately after tooth extraction ranged from 29.1+/-9.3 Ncm to 35.5+/-5.8 Ncm. No statistical difference was found (P > .05) between implants placed in healed bone and those placed immediately after tooth extraction. DISCUSSION: There is little documentation for immediate or early loading in the areas studied. However, in this study, favorable results were obtained in 54 consecutive patients in these regions. CONCLUSION: In this study population, early loading protocols can be applied with predictable results using rough-surfaced implants for rehabilitation of the completely edentulous maxilla, posterior maxilla, and posterior mandible.

Adult↗
PubMedDate not supplied

Tridimensional reconstruction of knife-edge edentulous maxillae by sinus elevation, onlay grafts, and sagittal osteotomy of the anterior maxilla: preliminary surgical and prosthetic results.

The possibility of placing endosseous implants in the edentulous maxilla is frequently reduced by inadequate bone volume of the residual ridge. In totally edentulous maxillae with knife-edge conformation, insufficient thickness is frequently associated with insufficient height of the residual ridge in the posterior maxilla because of pneumatization of the maxillary sinuses. This surgical method combines grafting of the maxillary sinuses, onlay grafts on the buccal side of maxillary posterior segments, and sagittal osteotomy of the anterior maxilla with interpositional bone grafts. Five to six months after maxillary reconstruction, Brånemark implants were placed and, after osseointegration occurred, implant-supported dental prostheses were fabricated. Three patients have been treated with this method and 22 implants have been placed. The mean follow-up after final prosthetic rehabilitation has been 16 months; survival rate has been 100%. Despite the small number of patients and the short follow-up, preliminary results have shown very promising results.

Adult↗
PubMed1986

Presurgical planning for osseointegrated implants in the maxilla. A tomographic evaluation of available alveolar bone and morphological relations in the maxilla.

A clinical tomographic method of defining and demonstrating the hard and soft tissue morphology of those parts of the maxilla which are intended for osseointegrated implants is described. This preoperative examination is an useful aid in the choice and planning of the treatment as such, and in the decision concerning the calibre and position of the implants. Hence, it facilitates the surgical procedure.

Alveolar Process↗
PubMed1997

Bone grafting to the maxillary sinuses, nasal floor and anterior maxilla in the atrophic edentulous maxilla. A two-stage technique.

This study presents the results from 20 consecutive patients treated with an autogenous bone graft from the iliac crest. In ten patients the graft was placed in the maxillary sinuses and the floor of the nose (inlay group). Ten patients, in addition to the inlay graft, had a corticocancellous bone block secured with mini-screws to the anterior maxillary ridge (inlay/onlay group). Endosteal implants (Brånemark) were placed six months after surgery. A total of 136 implants were placed, of which eight failed to integrate during the six-month healing period. A further 15 implants were lost during the follow-up period. For the inlay group the average follow-up period was 22 months and for the inlay/onlay group 19 months. Donor site morbidity was significantly less when iliac bone was harvested with a trephine (inlay group) than in patients treated with our routine procedure for bone harvesting (inlay/onlay group). Surgical technique, donor site morbidity, implant survival and patient acceptance are presented.

Adult↗
PubMed2003

Maxillae and mandibles of male mosquitoes and female autogenous mosquitoes (Diptera: Culicidae).

Maxillae and mandibles of males of 44 species of 12 mosquito genera and females of three autogenous genera and two partially autogenous species were examined under light microscopy and scanning electron microscopy. The maxillae and mandibles of male mosquitoes are delicate, tape-like structures with lengths characterizing genera or higher level classification units. Five patterns are recognized: (A) long maxillae and mandibles with mandibles longer than maxillae in Anopheles; (B) long maxillae and mandibles with maxillae longer than mandibles in Toxorhynchites; (C) short or intermediate lengths of maxillae with short mandibles in Aedes, Armigeres, Culex, Ochlerotatus, Orthopodomyia, and Uranotaenia; (D) short or intermediate length of maxillae with no mandibles in Mimomyia and Tripteroides; and (E) no maxillae and mandibles in Malaya and Topomyia. Maxillary and mandibular lengths of male mosquitoes show a positive correlation. Length of maxillae and mandibles of autogenous females are reduced to the same level as conspecific males. In contrast, females of partially autogenous species have complete maxillae and mandibles as in females of anautogenous species.

Animals↗
PubMed1989

[Study of internal reaction on the maxilla by orthopedic force].

For the purpose of analyzing deformations and movements in the maxilla loaded by orthopedic force to the maxillary first molar, a three dimensional finite element model of the maxilla was constructed. For modelling of the maxilla, the right side of an adult Indian skull was used. Constructed model was composed of 1,108 solid elements and 1,195 nodes. Materials of this model was composed of compact bone, cancellous bone, teeth and sutures. Constraint condition was fixed adjacent bone side surrounded by sutures. Load was directed from upward to downward 30 degree, changing every 30 degree reference to occlusal plane. Volume of load were weighed at 1 kg for each directions. Results 1. At upward load, stress was transmitted through the lateral wall of the maxillary sinus. The posterior portion of the maxilla was displaced more upward than anterior. Each process of the maxilla and the maxillary sinus was deformed, however, there was no stress on the orbitary surface. 2. At upward 60 degree load, the maxilla was compressed simply to the direction of load. At the upward 30 degree load, it was compressed backward-downward and rotated clockwise together with bending. 3. At backward load, the maxilla was moved backward and rotated clockwise. At downward 30 degree load, the maxilla was moved backward-downward and rotated clockwise. Both loads bended anterior portion of the maxilla and compressed posterior portion. The center of rotation or bending fell on the line joining the frontal process and the zygomatic process. 4. Of all five directions, backward load showed the maximum value of displacement and upward showed the minimum. Concerning with the absolute value of principal stress, backward load showed the maximum and upward 60 degree load showed the minimum. 5. Concerning with the principal stress value of sutures, compressive stress were distributed equally at upward load. However, as the load went to downward direction, it caused stress concentration. Especially, compressive stress in the pterygopalatine suture and transverse palatine suture, extensive stress in the midpalatal suture were especially great.

Adult↗
PubMed2005

Horizontal distraction of the anterior maxilla in combination with bilateral sinuslift operation--preliminary report.

In many cases alveolar ridge atrophy causes severe alveolar ridge deficiency in horizontal and vertical direction. In cases of severe atrophy of the edentulous maxilla a maxillary retrognathism results. In this article, a new technique of solving this problem prior to implant placement is described. In six patients with severe atrophy of the edentulous maxilla a sinuslift operation and placement of dental implants were carried out in the posterior maxilla. In the anterior part of the maxilla a segmental split osteotomy and placement of two miniplate distractors were performed. One week after surgery distraction started with a distraction speed of 0.5 mm a day until a clinical correct position of the anterior maxilla resulted. Then, the stabilisation period of 12 weeks followed before the distractors were removed and two to four implants were placed in the anterior distracted maxilla. After a second healing period of 4 months the implants were used for loading by a fixed prosthetic superstructure. Six patients were treated by this regime and 58 implants were placed. All implants were loaded by a fixed prosthesis. Distraction was performed without disturbances. Three months after healing new bone was formed in the distraction gap. There was no implant loss. An aesthetic satisfying superstructure with good red and white aesthetics was achieved together with a correct interalveolar relation. Distraction of the anterior part of the maxilla in combination with sinuslift operation is an alternative technique for correction of interalveolar incongruences in the edentulous maxilla and augmentation prior to implant placement.

Bone Substitutes↗