Analysis of nasal airway symmetry and upper airway changes after rapid maxillary expansion.

INTRODUCTION: The objectives of this study were to assess the changes in right vs left nasal cavity volumes and minimum cross-sectional width, nasopharyngeal, and oropharyngeal volumes of the upper airway in response to rapid maxillary expansion (RME). METHODS: Pretreatment and posttreatment cone-beam computed tomography scans of 28 patients with a mean age of 9.86 ± 2.43 years and 20 age- and sex-matched controls were digitized and linear, angular, and volumetric measurements were obtained. RESULTS: Nasopharyngeal volume, right, and left nasal cavity volumes, and minimum cross-sectional widths increased significantly 2 years post RME (P <0.05). These measurements did not show any significant increase in the control group (P >0.05), whereas the oropharyngeal volume increase for both groups was comparable (P = 0.92). In the experimental group, the right and left nasal cavity volumes were not significantly different at baseline or posttreatment. However, the change that occurred was significantly larger for the left nasal cavity. This change for the control group was more significant for the right nasal cavity. Maxillary right and left molar inclinations were positively correlated to the nasal cavity volume, showing that the more buccally inclined the maxillary molars were, the smaller the nasal cavity volume. CONCLUSIONS: Nasopharyngeal and right and left nasal cavity volumes and minimum cross-sectional widths increase significantly after RME in young children. Expansion decreases the degree of difference in volume between the right and left nasal cavities. The buccal inclination of maxillary molars is correlated with nasal cavity volume.

Association between incisor irregularity and coronal caries: A population-based study.

INTRODUCTION: The objective of this study was to investigate the association between incisor irregularity and anterior coronal caries by means of an arch-specific analysis among the U.S. population in the National Health and Nutritional Examination Survey (NHANES III) 1988-1994. METHODS: This study analyzed data from 9049 participants who were surveyed from 1988 to 1994 as a part of the NHANES III. Participants with a complete set of fully erupted permanent anterior teeth in the maxillary and mandibular segments (ie, canine to canine), who completed an examination of occlusal characteristics and anterior dental caries, and who reported no previous orthodontic treatment were included in the study. Incisor irregularity per arch was determined with the use of the Little irregularity index. Anterior coronal caries per arch was defined as ≥1 surface with decayed or filled surface (CDFS ≥1). Analyses were conducted with the use of chi-square test and logistic regression modeling taking into account the complex sampling design of the survey. RESULTS: In the maxillary arch, 25.1% of the study population had maxillary anterior coronal caries experience (CDFS ≥1), whereas only 5.5% of the study population had mandibular anterior coronal caries experience (CDFS ≥1). In both arches, no statistically significant association between incisor irregularity and anterior coronal caries experience was found. CONCLUSIONS: Maxillary and mandibular incisor irregularity is not associated with anterior dental caries prevalence in a subset of NHANES III data that included mostly highly educated adult participants who were white, of medium socioeconomic status, and with high oral health compliance and oral self-care. Future well designed prospective cohort studies are needed to confirm these results. Clinicians are still encouraged to continue providing oral health education to their patients about the well established effect of incisor irregularity on plaque retention.