Behavioral profiles of inbred strains on novel olfactory, spatial and emotional tests for reference memory in mice.

Studying the behavior of genetic background strains provides important information for the design and interpretation of cognitive phenotypes in mutant mice. Our experiments examined the performance of three commonly used strains (C57BL/6J, 129S6, DBA/2J) on three behavioral tests for learning and memory that measure very different forms of memory, and for which there is a lack of data on strain differences. In the social transmission of food preference test (STFP) all three strains demonstrated intact memory for an odor-cued food that had been sampled on the breath of a cagemate 24 hours previously. While C57BL/6J and 129S6 mice showed good trace fear conditioning, DBA/2J mice showed a profound deficit on trace fear conditioning. In the Barnes maze test for spatial memory, the 129S6 strain showed poor probe trial performance, relative to C57BL/6J mice. Comparison of strains for open field exploratory activity and anxiety-like behavior suggests that poor Barnes maze performance reflects low exploratory behavior, rather than a true spatial memory deficit, in 129S6 mice. This interpretation is supported by good Morris water maze performance in 129S6 mice. These data support the use of a C57BL/6J background for studying memory deficits in mutant mice using any of these tasks, and the use of a 129S6 background in all but the Barnes maze. A DBA/2J background may be particularly useful for investigating the genetic basis of emotional memory using fear conditioning.

Analysis of debond rates of resin-bonded prostheses.

Debonding rates of 164 resin-bonded prostheses (RBP) placed from 1974 to 1985 were examined at recall. The yearly debond rates were calculated, the cumulative probability of failure was determined for the debonded RBPs, and Weibull distribution parameters were determined. For perforated prostheses, there was a high initial debond rate, followed by slowly decreasing rates for about 5 years. Increasing rates after 5 years indicated the beginning of wear-out. The Weibull parameters for the wear-out period of the perforated prostheses were: characteristic life = 128 (SE = 2) months, modulus = 1.27 (0.06), and threshold parameter = 0. Data were available for etched frameworks for 6 years and showed decreasing debond rates during this time. The characteristic life of the etched bridges was 318 (84) months. The cumulative failure data were also modeled with a cubic polynomial distribution that resulted in a U-shaped hazard function.

Systemic effects of epinephrine-impregnated retraction cord in fixed partial denture prosthodontics.

There still is conflict among practitioners and researchers concerning the systemic effects of epinephrine retraction systems. However, the concentration of epinephrine in our commercially available retraction systems, as reported by Shaw, is cause for concern. Therefore, before using these systems, the dentist must consider the following variables: medical history of the patient, health of the oral cavity (especially the dentogingival unit), type of procedure to be done, amount and length of retraction, and exposure of the vascular bed. After careful attention to the foregoing variables, the retraction system of choice is the 8% racemic epinephrine-impregnated retraction cord. In addition to these variables, a calm and organized manner in the dental operatory can and will reassure the patient of the best of care with the least side effects.

Acid-etch retained cast metal prostheses: a seven-year retrospective study.

The results of this study showed: retention rate was good, caries on the retainer teeth was almost nonexistent, and the supporting tissue clinically did not appear to have a greater incidence of periodontal problems. We believe that these results indicate that the cast acid-etch retained anterior prosthesis should be considered a permanent restoration and a valuable aid for the dental patient.

Restoration of endodontically treated molar with root fracture.

The management of an unusual and extreme tooth and root fracture has been presented and discussed. A somewhat unorthodox approach was used in preparing the fractured root surfaces to fit the cast gold crown instead of making a crown to fit a prepared tooth surface. Diagnosis and treatment planning is a key factor in treating unusual patients. All factors must be carefully considered. Condition of adjacent teeth, periodontal support, size and form of remaining tooth structure, and occlusion are all important considerations. With careful and proper study, simple and conservative restorations can frequently be made that will provide excellent service for extended periods of time.

Cast metal, resin-bonded prostheses: a 10-year retrospective study.

A sample of 99 resin-bonded prostheses placed over a 10-year period were examined by four clinicians using a standardized criteria sheet. Areas examined included hard tissues, periodontium, retainer and pontic design, retention, the effect of occlusion on framework design and retention rate, and bonding media. The data from 7- and 10-year retrospective studies were compared for meaningful trends. Results showed (1) caries on retainer teeth was 3%, (2) gingival index of the retainer teeth was less than the gingival index of the rest of the mouth (0.7 +/- 0.5 versus 0.9 +/- 0.6), (3) the respective mean probing depths of retainer teeth of 34 patients in the 7- and 10-year studies were 2.2 +/- 0.4 mm and 1.9 +/- 0.7 mm, (4) the debond rate of all the prostheses from all causes was 31%, (5) the debond rate comparing etched metal and perforated retainers from all causes was 32% and 31% [corrected], respectively, and (6) 83% liked the prosthesis; 17% were noncommittal. The authors concluded that the resin-bonded prosthesis may be considered a permanent restoration and a valuable asset in the clinician's armamentarium.

Acid-etched, resin bonded cast metal prostheses: a retrospective study of 5- to 15-year-old restorations.

Eighty-five resin bonded prostheses were evaluated in a retrospective study over a 15-year period. All had been in function for at least 4.5 years. Multifactorial variables were studied to ascertain their effect on debonding and the health of the oral tissues. The results showed: (1) the caries rate of the retainer teeth was 6%, (2) the mean gingival indices for the prostheses were significantly higher (P > .0001) than those of the remaining dentition, (3) 61% of the restorations had not debonded (if failure resulting from trauma was not included, the incidence of debonding dropped to 19%), and (4) all patients liked their prostheses.