Master of Science (M.S.) in Dentistry
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College of Dental Medicine
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Nova Southeastern University
Nickolaos Z. Kallis. 2018. Evaluation of Enamel Surface Roughness After Laser Removal of Clear Aligner Attachments. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, College of Dental Medicine. (116)
Introduction: Following orthodontic appliance removal, the primary objective is to remove all remaining adhesive from the facial surfaces and return the enamel to its pretreatment state. Composite remnant removal must be performed with as little to no damage to the superficial layer of enamel to ensure long-term health and esthetics of the dentition. Numerous studies have investigated the efficacy of multiple composite remnant removal methods with no consensus as to which method should be the standard of care1-7. Traditional methods of composite removal after bracket debonding have included tungsten-carbide burs, white stone burs, green stones, and composite discs; which all damage the enamel surface to some degree. Technological advances in the last decade have allowed for the use of lasers to be incorporated into the field of dentistry. Very few studies have evaluated the prospect of using Nd:YAG, CO2, and Er:YAG laser for composite removal following orthodontic bracket debonding but no studies have investigated these methods for clear attachment removal. Therefore, the goal of this research study was to evaluate the effectiveness of Er:YAG laser to remove clear aligner attachments. Methods: Forty freshly extracted human premolars were randomly divided into four groups (one control group and three experimental groups). Prior to experimentation, the sample teeth had a portion of the buccal enamel surface flattened to normalize the surfaces. Pre-treatment enamel surface roughness value (Ra) was measured using the Veeco DEKTAK 150 stylus profilometer, pre-treatment surface gloss (degrees) was measured using the Novo-Curve Glossmeter, and pre-treatment enamel surface morphology was analyzed using the Olympus SZX7 stereomicroscope. Clear aligner attachments were bonded to the sample teeth using the small wire bonder Mini Mold attachment. In the control group, clear aligner attachment removal was completed using a multi-fluted tungsten carbide bur with high-speed handpiece. In experimental group 1, clear aligner attachment removal was completed using Er:YAG laser at 215 mJ/30 Hz/6.45 W. In experimental group 2, clear aligner attachment removal was completed using Er:YAG laser at 300 mJ/20 Hz/6W. In experimental group 3, clear aligner attachment removal was completed using Er:YAG at 240 mJ/20 Hz/4.8 W. Pulp temperature changes during clear aligner attachment removal was measured using a K-type thermocouple. Surface roughness, surface gloss, and morphology were also be examined following clear aligner attachment removal. Results: Post hoc analyses using the Tukey HSD post hoc criterion for significance indicated that the average roughness score was significantly lower before treatment than the control group (p < 0.001), experimental group 1 (p < 0.001), experimental group 2 (p < 0.001), and experimental group 3 (p < 0.001). It was also noted that the average roughness score was significantly lower in the control group (M = 2.77, SD = 1.18) when compared to the three experimental groups. Post hoc analyses using the Tukey HSD post hoc criterion for significance indicated that the average gloss was significantly lower in the control (M = -5.93, SD = 1.67) than experimental group 1 (M = -12.25, SD = 3.39, p < 0.001), experimental group 2 (M = -13.36, SD = 3.12, p < 0.001) and experimental group 3 (M = -11.89, SD = 2.03, p = 0.001). Post hoc analyses using the Tukey HSD post hoc criterion for significance indicated that the average temperature was significantly lower in the control group (M = 1.58, SD = 0.53) and experimental group 2 (M = 1.49, SD = 0.29) than experimental group 1 (p = 0.006) and experimental group 3 (p = 0.001). Conclusions: All four clear aligner attachment removal methods significantly increased the enamel surface roughness and decreased gloss; however, the multi-fluted tungsten-carbide bur provided the least amount of unwanted side effects on enamel surface roughness, morphology, and gloss. The multi-fluted tungsten-carbide bur and Er:YAG laser can both safely remove clear aligner attachments with very little to no risk of pulpal necrosis.
Attachments, Clear aligners, Lasers, Orthodontics, Orthodontic appliance removal
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