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Biomedical subjects

L R Gerbo

Publications and source records attributed to L R Gerbo.

7 recordsLinked to original sources
PubMed1997

A comparison of a computer-based orthognathic surgery prediction system to postsurgical results.

This retrospective study analyzes the accuracy of a prediction algorithm from Quick Ceph Image. Pre- and postsurgical lateral cephalograms of 35 adult patients were computer imaged and specific landmarks digitized. Digitization error was assessed from duplicate digitizations. Sixteen measurements of the predicted and actual postsurgical hard and soft tissue landmarks were compared using Student's t test, one- and two-way analysis of variance, and a modified Bradley-Blackwood test. Results showed a good correlation between repeated digitization of all variables except soft tissue point B and E-plane. Comparison of the predicted and actual changes found that all differences were less than 1.8 mm or 3.1 degrees. Student's t test showed 10 of the 16 measurements did not differ significantly, and interclass correlation demonstrated moderate to good correlations for 13 of 16 variables. Overall the results of this study suggest that the magnitude of the differences were within clinically acceptable limits.

Adult↗
PubMed1993

Applications of the air-powder polisher in clinical orthodontics.

Air polishers are relatively new devices that have provided dentistry with an alternative method for cleansing the tooth surface. Many publications attest to the efficacy of the instrument in plaque and stain removal while advising the practitioner of potential health risks to the patient. In spite of the information available, little research has been published concerning air polishing procedures in the treatment of the tooth surface before placement of the orthodontic bracket. In light of the research supporting the efficacy of plaque and stain removal, the use of the air polisher has been shown to have no detrimental influence on the bonding of the resin bracket cement to the tooth surface. It would appear that the system may be ideal for use in conjunction with orthodontic treatment. The air-powder polisher has been found to be the most effective method of plaque removal for orthodontic patients without causing breakage of elastics or wires or loss of zinc phosphate or composite material. Another application for the air-powder polisher in the orthodontic practice is surface preparation of the tooth before bracket placement. The instrument should be held approximately 4 to 5 mm from the tooth surface, at a 60 degree angle for anterior smooth surfaces, at an 80 degree angle for posterior smooth surfaces, and at a 90 degree angle for occlusal surfaces. A constant circular motion should be used, with an exposure time of 30 to 60 seconds.

Air Pressure↗
PubMed1993

Clinical evaluation of a highly wear resistant composite.

The purpose of this clinical study was to determine the long-term potential of a resin composite restorative material. A total of 62 restorations of a modified Herculite Incisal formulation were inserted into Class I and Class II preparations. A control group of the conventional Herculite formulation was also placed into Class I and Class II cavity preparations at an earlier date. The cavity preparations for both formulations were standardized to conform to that of conventional conservative amalgams. Deep portions of the preparations were lined with calcium hydroxide. The enamel margins were etched per manufacturers' directions followed by a dentin bonding agent. After application of the appropriate matrix, the restorations were placed incrementally. Each restoration was independently evaluated by two clinicians at baseline, 6-months, 1, 2 and 3 years in accordance with the USPHS criteria. In addition, all restorations were evaluated for wear using a series of optical standards (M-L). The color matching ability of the material never fell below 96%. The percent of restorations exhibiting a surface texture similar to enamel never fell below 90% Alfa. At the end of 3 years, the total average loss of material was only 28 microns. No clinical evidence of bulk fracture was detected with the modified Herculite formulation at 3 years. The wear rate of the modified formulation of Herculite was essentially one-half that of conventional Herculite XR. Marginal ditching, which is characteristic of most posterior resin composites in which the filler particle is 1 micron or less, was exhibited.(ABSTRACT TRUNCATED AT 250 WORDS)

Bicuspid↗
PubMed1993

Enamel roughness after air-powder polishing.

The purpose of this study was to quantify differences in enamel surface roughness following treatment with an air abrasive system when compared to a rubber cup and pumice. The coronal portion of 40 bovine teeth were tested. Half of the teeth were placed in a control group and cleansed with a rubber cup and pumice, the other half or "test" group were treated with an air-powder polisher. All teeth were exposed to the given cleansing agent for a time equivalent to a 15-year recall program. Pre- and post-treatment surface evaluation was completed using a surface profilometer. In addition, representative samples were evaluated before and after cleansing under the scanning electron microscope (SEM). The results of this study showed no statistically significant increase in enamel surface roughness in teeth cleansed with the air polisher when compared to the roughness of the control teeth. This was confirmed visually by use of SEM taken at magnifications of up to x1000. The findings of this study indicate there is no significant alteration of the enamel surface when a tooth is treated with an air-powder polisher for the equivalent of a 15-year recall program.

Air Pressure↗
PubMed1992

The effect of enamel preparation on the tensile bond strength of orthodontic composite resin.

The bonding of orthodontic brackets to enamel surface using bis-GMA composite resin is usually accomplished by first cleaning the tooth surface then etching with phosphoric acid. This study compared the tensile bond strength of composite resin applied to a tooth surface which had been cleansed with an air-powder polisher to that of the same resin applied to a surface cleansed using a rubber cup and pumice. A wire loop apparatus was attached to bonded orthodontic brackets and pulled in tension in order to test the adherence of the bracket to the tooth. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to evaluate the tooth surface to determine whether sodium bicarbonate material remained after the cleaning operation. All data was analyzed by the one way analysis of variants, the Student-Newman-Keuls test and Duncan's multiple comparison test. No statistical differences were found between the tensile strength of the bonds on the teeth cleansed with the air-powder polisher and those cleansed with a rubber cup and pumice. However, a double exposure of the tooth to phosphoric acid may lower the tensile bond strength by a significant amount.

Acid Etching, Dental↗