Influence Of Bone Loss Research Articles

Effect of Marginal Bone Integrity and Aftermarket Abutment Screws on Dental Implant Systems-A Preliminary Study with Finite Element Method.

Bone resorption around implants is quite common, and the maturity and popularization of computer-aided design and computer-aided manufacturing (CAD/CAM) technology have made the use of aftermarket abutment screws more widespread. This study aimed to explore the biomechanical influence of these two common factors on the internal stress of an implant system using three-dimensional finite element analysis (3D FEA). The FEA results indicated that under the same loading conditions, the use of an aftermarket screw had the greatest impact on the screw itself among the three components of the implant system, while the maximum stress increased by 6.3% and 10.5% in the bone integrity and bone loss models, respectively. Moreover, the marginal bone loss models had the greatest impact on the implant fixture, with a maximum stress increase of 51.8% on average. Evidently, the influence of bone loss might be far greater than that of the aftermarket screw; however, any factor could be enough to cause clinical failure. Therefore, we should pay more attention to the maintenance of the long-term peri-implant marginal bone integrity.

The influence of bone loss on peri-implant bending strain under overdentures.

The purpose of this study was to evaluate the biomechanical effects of bone loss on peri-implant bending strain underneath overdentures. One mandibular and one maxillary edentulous model were created and covered with 2 to 4 mm of silicone rubber to simulate the oral mucosa. Four strain gauges were attached to four sides of each implant. In the mandibular model, two implants were inserted, and the implant was placed bilaterally in the area between the mandibular canines and lateral incisors. A maxillary conventional denture and mandibular overdenture were fabricated with acrylic resin to fit the edentulous models. Five bone loss levels were created: no bone loss, 0.8 mm bone loss on only the left implant, 0.8 mm bone loss bilaterally, 1.5 mm bone loss on only the left implant, and 1.5 mm bone loss bilaterally. Magnetic attachments were used to retain the denture. The bending strains generated from three types of unilateral loading were measured by a sensor interface, and the data were analyzed using the Kruskal-Wallis test and Bonferroni's post hoc test. Bending strain increased with decreasing bone levels on the loading side. On the nonloading side, bending strains were greater at even bone loss (0.8 mm or 1.5 mm bone loss bilaterally) than at uneven bone loss (0.8 mm or 1.5 mm bone loss on only the left implant). Strains under loading at the left first premolar were approximately equal to that under loading with a cotton roll; these strains were higher than those generated with loading at the left first molar. Peri-implant bending strains rapidly increased on the loading side as bone loss levels increased. Peri-implant bending strains on the nonloading side were higher at bilaterally even bone loss than at unilateral bone loss.

Influence of bone loss and inclination of incisor on periradicular stresses due to simulated bite force

Abstract Introduction Adults with sequelae of periodontal disease tend to have bone loss, with consequent flaring of the maxillary incisors. Objective The influence of bone loss and the inclination of the maxillary incisor in the distribution of stresses due to simulated bite forces was studied. Material and method Models in epoxy resin were made in three conditions (without bone loss and with bone loss of 5mm and 8mm). Increases in the labial inclination of the maxillary incisor of 10° and 20° were obtained with a beveled metallic block. Loads of 100N were applied five times in each condition using a universal test machine. The models were observed and filmed with a circular polariscope. Orders of isochromatic fringes (stresses) on the labial, lingual, and apex surfaces were recorded. The agreement of the data was evaluated using the weighted kappa test, and the results were 0.89 and 0.82 for intra- and inter-examiners, respectively. Result The results of the Kruskal–Wallis and SNK tests indicated higher stresses (2.0) with increased labial inclination in the labial surface; higher stresses (2.67) with increased bone loss; higher greater stresses with the association of bone loss and labial-inclination (3.6); and the highest stresses tended to concentrate on the labial surfaces, except in cases of normal inclination and without bone loss (0.45). Conclusion It was concluded that increases in both the labial inclination of the maxillary incisors and bone loss increase periradicular stresses, and the combination of these factors further increases the stresses due to bite forces, with the highest concentration on the labial side.

The Influence of Bone Loss on Glenoid Version Measurement: A Computer-Modeled Cadaveric Analysis

To characterize how increasing computed tomography (CT)-quantified glenoid bone loss influences measured version. Six embalmed cadaveric shoulders were used for this study. Glenoid bone defects were computer modeled in cadaveric shoulders; CT images were obtained and segmented using OsiriX software, creating 3-dimensional en face glenoids. Glenoid defects were made on CT images of intact glenoids superimposed with a glenoid clock face viewed en face to simulate anterior and posterior bone loss. Bony defects in various positions comprising 3%, 9.5%, and 19.5% were created posteriorly. Best-fit circles were superimposed to represent 10% and 25% defects anteriorly. Version was measured using the Friedman method. The average glenoid version measured 4° of retroversion, 2° after 10% anterior bone loss, and neutral version in the 25% bone loss group. Version was significantly altered when we compared intact glenoids versus 10% and 25% anterior glenoid bone loss (P < .001). Increasing from 10% to 25% bone loss showed a significant difference in measured version (P= .025). Posterior defects from the 6:30 to 8:30 clock-face position averaged 4.6° of retroversion; from the 6:30 to 9:30 clock-face position, 6.2° of retroversion; and from the 6:30 to 10:30 clock-face position, 8.7° of retroversion. When comparing glenoid defects at the 6:30 to 8:30 clock-face position with those involving the 6:30 to 9:30 and 6:30 to 10:30 clock-face positions (P < .001), a 1° correction may be used for every 5% of bone loss to account for version changes seen with bone loss. In this cadaveric analysis, glenoid version was altered in the setting of increasing posterior and anterior bone loss. A correction factor may be considered to account for this. When comparing glenoid defects at the 6:30 to 8:30 clock-face position with those involving the 6:30 to 9:30 and 6:30 to 10:30 clock-face positions (P < .001), a 1° correction may be used for every 5% of bone loss to account for version changes seen with bone loss. This cadaveric study shows that glenoid bone loss alters glenoid version, as measured by CT, in a meaningful way. This information is important in managing anterior and posterior shoulder instability, and correction of measured version should be considered in this setting to provide an accurate and comprehensive evaluation.

The contribution of bone loss to postmenopausal osteoporosis

We have addressed the relative importance of peak bone mass and subsequent rate of loss in determining postmenopausal women's bone mass in old age, by examining longitudinal measurements of radial mid-shaft bone mass on various samples of healthy white postmenopausal women. Using both the variance estimate of age-specific rates of bone loss and the population variance in bone mass, we determined that rates of loss could contribute importantly to future bone mass. However, since we found a small negative correlation between initial bone mass and rate of loss, it was necessary to estimate the effect of bone loss as the complement of the contribution of initial bone mass. We found that the influence of bone loss (relative to initial bone mass) increases as the women age, such that by about age 70, the contribution of initial bone mass and rate of loss approached equality. However, estimated rates of bone loss were not very stable over time, so it was difficult to identify long-term 'fast-losers'. We conclude that the rate of postmenopausal bone loss is an important contributor to osteoporosis at old age, but it is difficult to identify long-term fast-losers, thereby reducing the clinical value of assessments of rates of change in bone mass early in the postmenopause.

Bone loss and forms of tibial condylar fracture

Bone loss and fracture type were determined in 358 tibial condylar fractures. Degree of osteoporosis at the knee was defined by analogy to Singh's grades of osteoporosis at the hip and to Jhamaria's classification of osteoporosis at the calcaneum: grade V-normal; grade IV-slight reduction of trabecular bone; grade III-osteoporosis, predominantly of trabecular bone; grade II-osteoporosis of trabecular and cortical bone. Five fracture types were distinguished, with the component of trabecular bone compression increasing from a to e: a-pure split fractures; b-split fractures with displacement of a piece of the articular surface; c-split compression fractures; d-local compression fractures; e-compression of a whole condyle. There was a highly significant rank correlation between the two sets of ordered categories. Fractures in osteoporotics tended to involve the lateral condyle; this is explained by the fact that crush fractures occurred more frequently at the lateral condyle. The influence of bone loss on fracture type was demonstrated to be independent of age. A clear understanding of these associations concerning three variables at a time was reached by the use of log-linear-model analysis for cross-classified qualitative data.

Oral surgery

The influence of bone loss and periodontal splinting on strains in supporting bone is still not well understood. The aim of this study was to analyse the effect of bone loss and periodontal splints on strains in an anterior mandible structure.Ten anterior mandible models were fabricated using polystyrene resin. Eighty human teeth were divided in 10 groups (right first premolar to left premolar) and embedded in simulated periodontal ligament. Strain gauges were attached to the buccal and lingual mandible surfaces. The models were sequentially tested for 7 conditions: no bone alterations and no splinting; 5 mm of bone loss between canine teeth; bone loss associated with resin splint between canine teeth; bone loss with wire splint; bone loss with wire/resin splint; bone loss with extracoronal fibre–glass/resin splint; and bone loss with intracoronal fibre–glass/resin splint. Oblique loads (50, 100, and 150 N) were applied on the teeth. Data were analysed using 3-way ANOVA and Scheffe's test (α = .05).Strains on buccal surface were higher than on lingual surface. Bone loss resulted in strain increase at 100 and 150 N loading. Dental splinting with resin resulted in strain values similar to the control levels.Bone loss increased strain mainly in the buccal region. Dental splints with adhesive system and composite resin produced lower bone strains irrespective of occlusal load.