Assessment of oral implant mobility.

Most of the implant literature suggests that successful dental implants are immobile and any detected mobility indicates implant failure. This study evaluated the ability of the Periotest instrument to measure implant mobility in a controlled in vitro model with a sample of 56 in vivo implants. In the in vitro portion of the study, implant model mobility was determined by an axial testing machine (0 to 5 N at 0.2 mm/minute) and the Periotest instrument. The comparison showed a high level of correlation (Pearson's r 0.984). The load that the Periotest placed on the implants during mobility measurements was approximately 5 N, depending on the compliance of the test object. The in vivo portion evaluated the range of mobility of 56 clinically successful endosseous implants. The range of mobility as determined by the Periotest instrument was -6 to +2. This range corresponds to an in vitro model displacement (5 N load) of 0.038 mm to 0.113 mm with a mean of 0.066 mm +/- 0.018 mm (SD). These data demonstrate that clinically successful implants are not immobile, but have a range of mobility.

Bioelectric stimulation and residual ridge resorption.

The use of exogenous pulsed electromagnetic fields (PEMF) to stimulate the healing of nonunions and other long bone defects is common in medicine. This investigation used the dog model and image analysis of standardized radiographs to assess loss of residual ridge height following extractions. It demonstrates the effectiveness of intermittent PEMF to reduce the rate of residual ridge resorption. It further suggests there may be a causal relationship between residual ridge resorption and the alteration of endogenous bioelectric signals caused by the loss of teeth.

Skeletal osteopenia and residual ridge resorption.

Increased residual ridge resorption resulting from postmenopausal skeletal osteopenia has been a long-standing clinical assumption. This study was conducted to determine the relationship between the degree of residual ridge resorption, sex, and the age of the patient. The technique of measuring mandibular resorption uses panoramic radiographs as described by Wical and Swoope. Six readers received technique instructions and were then tested for uniformity. An analysis of variance demonstrated no significant difference between readers (p greater than 0.10). A random selection of 459 radiographs of edentulous patients were then measured by using a blind technique to determine the amount of residual ridge resorption. Analysis of this data demonstrated a significantly larger percentage of women with class 3 (severe) residual ridge resorption (p less than 0.01) but this difference could not be related to the occurrence of menopause.

Expectations and satisfaction of denture patients in a university clinic.

These results indicate that patients' expectations of dentures before treatment were unrealistically high and that informational videotapes did not significantly affect these expectations. Satisfaction with current dentures was surprisingly high before treatment and increased significantly from pretreatment to postreatment for both groups in the study. While it is likely that this increase in satisfaction reflects a change from poor to excellent denture status, this finding may also be attributed to cognitive dissonance theory; that is, high satisfaction may represent the means by which patients justify the expenses of their denture treatment. Although the videotape presentations did not alter the expectations of patients and their satisfaction with dentures, the tapes represent a potential source of accurate, standardized information for both patient and student dentist.

Techniques for assessing alveolar bone mass changes in periodontal disease with emphasis on 125I absorptiometry.

No practical methods are presently available for measurement of alveolar bone activity at one instant of time. However, roentgenological methods making measurements at 2 different times can be used to assess alveolar bone activity. The most sensitive, specific and accurate method for this purpose presently in use is 125I absorptiometry. This method has the further advantage of giving the patient minimal radiation exposure. New methodology is under development which obviates the need for fixed geometry and could provide a 3-dimensional image of alveolar bone.

Relationship between alveolar bone measured by 125I absorptiometry with analysis of standardized radiographs: 1. Magiscan.

PREVIOUS STUDIES have shown that 125I absorptiometry gives an accurate and sensitive measure of alveolar bone mass. The purpose of this study was to determine the relationship between alveolar bone mass determined by 125I absorptiometry and bone density obtained by analysis of standardized intraoral radiographs by the Magiscan System. A defect of increasing size was made at one site of the alveolar bone in a human skull. The amount of bone remaining at each step was calculated using 125I absorptiometry. Standardized radiographs were also taken at each step and the relative density in the area of the defect was determined by the Magiscan System. The Magiscan's System Computer Memory permits analysis of identical areas on a longitudinal series of films of the same alveolar bone location. The results indicate that in estimating amounts of alveolar bone the Magiscan analysis of standardized intraoral radiography is similar in sensitivity and accuracy to 125I absorptiometry.

Relationship between alveolar bone measured by 125I absorptiometry with analysis of standardized radiographs: 2. Bjorn technique.

THE BJORN TECHNIQUE is widely used in periodontal studies as a standardized measure of alveolar bone. Recent studies have demonstrated the feasibility of using 125I absorptiometry to measure bone mass. The purpose of this study was to compare 125I absorptiometry with the Bjorn technique in detecting small sequential losses of alveolary bone. Four periodontal-like defects of incrementally increasing size were produced in alveolar bone in the posterior segment of the maxilla of a human skull. An attempt was made to sequentially reduce the amount of bone in 10% increments until no bone remained, a through and through defect. The bone remaining at each step was measured using 125I absorptiometry. At each site the 125I absorptiometry measurements were made at the same location by fixing the photon source to a prefabricated precision-made occlusal splint. This site was just beneath the crest and midway between the borders of two adjacent teeth. Bone loss was also determined by the Bjorn technique. Standardized intraoral films were taken using a custom-fitted acrylic clutch, and bone measurements were made from the root apex to coronal height of the lamina dura. A comparison of the data indicates that: (1) in early bone loss, less than 30%, the Bjorn technique underestimates the amount of loss, and (2) in advanced bone loss, more than 60% the Bjorn technique overestimates it.

Experimental alveolar bone loss in the monkey evaluated by 125I absorptiometry.

An 125I absorptiometry technique is described which has sufficient precision to detect the alveolar bone loss associated with ligature-related periodontitis in the monkey. Six monkeys had significant drops in alveolar bone mass 14 days after the the application of a silk ligature around the gingival margin of an adjacent tooth. Variation in the magnitude of bone loss was observed. These may represent variations in the pathogenicity of the microflora produced in response to a ligature and/or variation in host response to the insult produced by specific dental plaque organisms. The lack of bone loss post-ligature plus antibiotic therapy supports the theory that the bacterial-host interaction, not simply irritation from the ligature alone, is responsible for the bone loss. The potential for bone regeneration after ligature-induced bone loss is demonstrated.