The purpose of this study was to determine the amount of root surface removal in vitro using an air-powder abrasive system or sharp curet on root surfaces simulating the cumulative effects of an every 3-month periodontal maintenance regimen over a 3-year period and to compare the amount of time spent in the utilization of each instrument. Fifty extracted teeth with fully formed roots were cleaned and mounted in one of 10 different artificial alveolar arches. Each arch contained one central incisor, one lateral incisor, one canine, one first and one second premolar. The buccal and mesial tooth root diameters were measured initially and after each treatment with a digital point micrometer. All teeth were stained with coffee and repositioned in their artificial alveolae and treated by the air-powder abrasive system or curet until all visible stain was removed. Time required for removal of stain in both treatment groups was recorded. Both groups were restained, retreated, and retimed 12 times to reproduce a 3-month maintenance interval for 3 years. The average root structure removed by the air-powder abrasive system following each treatment was 10.68 micron while the curet removed an average of 27.09 micron. Stain was removed 3.15 times faster by the air-powder abrasive system than with a curet.

The purpose of this investigation was to characterize by scanning electron microscopy, the microbial morphotypes associated with the roots of teeth from patients exhibiting localized juvenile periodontitis (LJP). Eighteen teeth were examined from 10 adolescent patients who satisfied the standard clinical diagnostic criteria for LJP. The microscopic evaluation was facilitated by dividing that portion of the root exposed to the periodontal pocket into coronal, middle, and apical one‐thirds. Controls consisted of an equal number of teeth matched as to pocket depth and anatomical type obtained from patients exhibiting adult periodontitis (AP). All specimens were coded and examiners were unaware of their origins. Results of the SEM evaluation revealed little difference in microbial morphotypes comprising the root associated plaque in the coronal one‐third of LJP specimens when compared to the AP controls. The dominant microbial morphotypes were cocci, short and long rods, filamentous microorganisms, and spirochetes. However, microbial plaque located in the middle and apical one‐third root zones of LJP specimens was distinctly different than that of AP specimens. In the deeper pocket zones the dominant microbial morphotypes in LJP specimens were limited to cocci, short rods, coccobacilli, and various sized spirochetes. In contrast, AP specimens exhibited a collection of microbial morphotypes consisting of cocci, short rods, long rods, filamentous organisms and spirochetes. Calculus was found on the root surfaces of all specimens regardless of disease category although, as a group, the LJP specimens featured lesser amounts. Although areas of root resorption were common in both LJP and AP groups, they were more frequently observed in LJP specimens, likely associated with the generally less confluent deposits of calculus and plaque. J Periodontol 1990; 61:475–484.