PubMed Health⌕ Search

PubMed · 9540492

Multiple cantilevers: an alternative to dental implants.

Abstract

A solution to the problem of missing posterior teeth is presented. The prerequisite for solving this problem is that the remaining teeth must be positioned in one form or another in a triangle, as one can see in Figs. 2, 3 and 4. The tripod effect, in connection with the controlling effect of the mechano-receptors in the periodontal ligaments of the remaining abutment teeth, permit us to construct a functional fixed prosthesis. The feather-edged or knife-edged preparation technique creates long axial walls. Together with the parallel prepared abutment teeth, this must be viewed as the main-retentive feature for fixed prostheses with multiple cantilevers. In extreme situations, where one is uncertain about the outcome of a case, provisional laboratory fabricated restorations are excellent for evaluating the stability of the cross-arch splinted teeth. The whole bridge occasionally shows some mobility. As long as the mobility shows no increase over a period of time, and does not interfere with the patient's chewing ability, a permanent bridge with multiple cantilevers can be inserted. I usually include no more than three cantilevered pontics on each side of the arch in a multiple cantilevered bridge. A second molar is not replaced by a third cantilevered pontic. Its position in the arch may cause an overly strong lever action on the fixed prosthesis.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

E D Schweikert. 1994. Multiple cantilevers: an alternative to dental implants.. https://pubmed.ncbi.nlm.nih.gov/9540492/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

The effect of excessive tibial torsion on the capacity of muscles to extend the hip and knee during single-limb stance.

Excessive tibial torsion, a rotational deformity about the long axis of the tibia, is common in patients with cerebral palsy who walk with a crouch gait. Previous research suggests that this deformity may contribute to crouch gait by reducing the capacity of soleus to extend the knee; however, the effects of excess external torsion on the capacity of other muscles to extend the stance limb during walking are unknown. A computer model of the musculoskeletal system was developed to simulate a range of tibial torsion deformities. A dynamic analysis was then performed to determine the effect of these deformities on the capacity of lower limb muscles to extend the hip and knee at body positions corresponding to the single-limb stance phase of a normal gait cycle. Analysis of the model confirmed that excessive external torsion reduces the extension capacity of soleus. In addition, our analysis revealed that several important muscles crossing the hip and knee are also adversely affected by excessive tibial torsion. With a tibial torsion deformity of 30 degrees , the capacities of soleus, posterior gluteus medius, and gluteus maximus to extend both the hip and knee were all reduced by over 10%. Since a tibial torsion deformity reduces the capacity of muscles to extend the hip and knee, it may be a significant contributor to crouch gait, especially when greater than 30 degrees from normal, and thus should be considered by clinicians when making treatment decisions.

Biomechanical Phenomena↗

Predicting the subject-specific primary stability of cementless implants during pre-operative planning: preliminary validation of subject-specific finite-element models.

Pre-operative planning help the surgeon in taking the proper clinical decision. The ultimate goal of this work is to develop numerical models that allow the surgeon to estimate the primary stability during the pre-operative planning session. The present study was aimed to validate finite-element (FE) models accounting for patient and prosthetic size and position as planned by the surgeon. For this purpose, the FE model of a cadaveric femur was generated starting from the CT scan and the anatomical position of a cementless stem derived by a skilled surgeon using a pre-operative CT-based planning simulation software. In-vitro experimental measurements were used as benchmark problem to validate the bone-implant relative micromotions predicted by the patient-specific FE model. A maximum torque in internal rotation of 11.4 Nm was applied to the proximal part of the hip stem. The error on the maximum predicted micromotion was 12% of the peak micromotion measured experimentally. The average error over the entire range of applied torques was only 7% of peak measurement. Hence, the present study confirms that it is possible to accurately predict the level of primary stability achieved for cementless stems using numerical models that account for patient specificity and surgical variability.

Biomechanical Phenomena↗

Experimental validation of intact and implanted distal femur finite element models.

Four finite element (FE) models of intact and distal femur of knee replacements were validated relative to measured bone strains. FE models of linear tetrahedrons were used. Femoral replacements with cemented stemless, cemented and noncemented femoral stems of the PFC Sigma Modular Knee System were analyzed. Bone strains were recorded at ten locations on the cortex. The magnitude of the FE bone strains corresponded to the mean measured strains, with an overall agreement of 10%. Linear regression between the FE and mean experimental strains produced slopes between 0.94 and 1.06 and R(2) values between 0.92 and 0.99. RSME values were less than 12%. The FE models were able to adequately replicate the mechanical behavior of distal femur reconstructions.

Biomechanical Phenomena↗