All ETDs from UAB

Advisory Committee Chair

Perng-Ru Liu

Advisory Committee Members

Jack Lemons

Amjad Javed

Keith Kinderknecht

Lance Ramp

Document Type


Date of Award


Degree Name by School

Master of Science in Dentistry (MScD) School of Dentistry


Aim: To develop a time and cost effective cleaning protocol for implant abutment screws that are used throughout the fabrication of an implant restoration in the dental laboratory. Materials and Methods: Ninety (90) implant abutment screws (Biohorizons PXAS®) were collected from different dental laboratories after abutment milling and restoration fabrication. Seventy five (75) of these screws were randomly divided into 5 groups (n=15). Each group was cleaned for 1, 5, and 10 minutes in an ultrasonic cleaner and all screws were observed under 40x magnification before and after cleaning. Any debris was collected and weighed by using paper filters. The group number and solutions were: 1; 70% isopropyl alcohol; 2; PerioGard ®; 3; Listerine Original ®; 4; hydrogen peroxide 3%; and 5; distilled water (control). Fifteen (15) screws were used for a microbiological analysis using distilled water. Generalized linear modeling with a robust estimator was used to perform pairwise comparisons between each group versus the control. The alpha level (a=.05) was adjusted using the sequential Bonferroni method for multiple comparisons. The visual observations of these screws by 15 dental students permitted utilization of the Liu-Barocio Cleanliness Scale. Fifteen (15) dental students were surveyed. The two tailed z-test for proportions was used to test for differences in perceived cleanliness between groups and the Bonferroni adjustment was applied to account for multiple comparisons (a=.005). Results: Measurements showed an increase in the weight of all paper filters, with Group 2 being the highest. Based on the Liu-Barocio Cleanliness Scale, Group 1 was most effective for removing debris, with 49.7%, followed by Groups 2, 3, 4, and 5, respectively. Bacterial colonies were found in all samples except for the control group. Conclusion: After the cleaning procedure in the ultrasonic, presence of debris was found in all implant abutment screws. However, visual and quantitative results demonstrated some debris removal. Bacterial colonies showed bacteria present on the screws. Statistical analysis showed a significant difference in weight of debris removed, but time did not have a significant effect. Observation showed alcohol-based products had the best visual result, and bacterial colonization was significant relatively to the control.

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Dentistry Commons