Evaluation of the airway space changes after extraction of four second premolars and orthodontic space closure in adult female patients with bimaxillary protrusion - A retrospective study.

BACKGROUND & OBJECTIVES: Previous studies have found that first premolar extractions during orthodontic treatment may alter the upper airway dimensions. The objective of this study is to investigate the effects of second premolar extraction during orthodontic treatment on the dimensions of the upper airway in a sample of female adults. METHODS: Twenty-nine female adult patients with ages between 18 and 30 years old and incisor bimaxillary protrusion were included in this study. They were treated with comprehensive orthodontic treatment which included the extraction of four second premolars. Pre and post cephalometric radiographs were analyzed using Dolphin imaging software for changes in tongue length and height, soft palate thickness and length, the superior, middle, and inferior airway space, and vertical airway length. Descriptive statistics were used to characterize measurements. Student's paired t-test was preformed to compare the pre- and post-test mean values of the dimensions. RESULTS: A significant increase in the vertical airway length was observed after the extraction of the second premolars (p = 0.02). The soft palate length showed a tendency towards an increase that did not reach statistical significance (p = 0.053). No other significant changes in the airway soft tissue measurements were observed. The proclination and protrusion of the upper and lower incisors were significantly decreased compared to pre-treatment measurements.Interpretation & conclusions.Orthodontic treatment involving the extraction of all four second premolars in females with bimaxillary protrusion increases the vertical airway length, which is the amount of distance between base of the tongue and posterior nasal spine. No other significant alterations in the upper airway measurements were observed.

Enamel demineralization around two different orthodontic bracket adhesive systems: An in vivo study.

OBJECTIVE: To compare the enamel demineralization around the two precoated adhesive bracket systems, APC Flash-Free and APC PLUS (3M Unitek, Monrovia, CA, USA), in clinical settings. MATERIAL AND METHOD: This prospective experimental in-vivo study included 40 premolar teeth, which were planned for extraction due to orthodontic purposes. They were divided into two groups (Group A; n = 20 teeth were bonded with APC Flash Free ceramic brackets and group B; n = 20 teeth were bonded with APC Plus ceramic bracket). After four weeks, the teeth were extracted, sectioned, and examined under the Scanning Electron Microscope (SEM) to evaluate the amount of demineralization from the enamel surface to the deepest point. RESULTS: Findings revealed that the mean values of demineralization under SEM were significantly higher in APC Plus compared to APC Flash Free (149.95 µm vs. 112.96 µm, respectively) (P < 0.05). The difference between the two systems was mainly found in the middle part of the facial surfaces, while there were no differences between the two systems in the proximal parts. CONCLUSION: The enamel demineralization around APC Flash-Free adhesive bracket system was significantly less than that of APC plus Adhesive bracket system, which can be due to the absence of the caries promoting adhesive flash during tooth bonding using the flash free system.