BackgroundAn aesthetic smile has a number of components, and people generally equate a good dental appearance with success in many areas of life. The features that determine smile aesthetics could provide significant insights into post-treatment satisfaction and may predict a patient’s objectives when undergoing treatment. The purpose of this study was to evaluate how smile characteristics are perceived by dental students.MethodsThe study was performed in 431 local and international dental students at the Lithuanian University of Health Sciences. The study data were collected using a three-part questionnaire. The first part of the questionnaire included sociodemographic items, i.e., student gender, age, nationality, and years of study; the second consisted of questions about facial aesthetic features; and the third elicited responses to photographs of 17 different smiles retrieved from the Lithuanian University of Health Sciences Clinic of Orthodontics database. The smile aesthetics were evaluated according to their dentolabial, dentogingival, dental, and dental arch characteristics using a 5-point numeric rating scale (1, best; 5, worst). The data were analysed using the Pearson’s chi-square and Mann-Whitney U tests.ResultsThe study included 336 local and 95 international dental students (132 men [30.6%], 299 women [69.4%]). Significantly more women than men focused on a person’s teeth when communicating (41.5% vs.32.6%, p < 0.005). Women were more critical than men when evaluating gingival smile, the ‘golden proportion’, occlusal cant, and dental crowding. The most unfavourable smile characteristics were identified in the dental analysis category, with hypodontia ranked as the worst smile feature (mean numeric rating scale score 4.71).ConclusionAmong dental students, the most distracting characteristics of a smile when determining its attractiveness were hypodontia, gingival smile, a reversed curvature of the occlusal plane, and dental crowding.

Analysed cephalometric data totally supported the concept of soft-tissue abnormalities in subjects with OSA, skeletal-only halfway; MP-H and SPAS being the most reliable parameters. Increased MP-H may serve as a predictor when differentiating normal subjects and patients with OSA. Reduced SPAS width could be a prognostic parameter for suspecting OSA. These two values should be kept in mind by dentists and can also be used as a simple auxiliary method by physicians; nevertheless, it is still underestimated and more studies are needed.

The objective of this in vitro study was to determine the effects of dental fluorosis on the tensile bond strength of metal brackets bonded to human teeth and to evaluate the changes in the tooth enamel surface after debonding. The study sample consisted of 68 recently extracted human upper premolars, which were divided into 2 groups: the fluorosis group (34 fluorosed teeth) and the control group (34 healthy teeth). Identical premolar metal brackets were bonded on the buccal surfaces of the teeth. Both groups were submitted to a tension test using a universal testing machine. The number and length of the enamel microcracks in the buccal surface of each tooth were determined before bracket bonding and after debonding using a stereomicroscope. The percentage adhesive remnant index (PARI) was calculated after debonding. The results showed that the tensile bond strength (TBS) of brackets bonded to fluorosed teeth was 21.08% lower than that of brackets bonded to healthy teeth (p < 0.0001). The length of the enamel microcracks on fluorosed teeth increased by 47.4% after debonding, whereas the control group showed an increase of only 12.6%. The PARI showed lower values for fluorosed teeth in comparison to the control group (p = 0.047). In conclusion, dental fluorosis has a negative impact on tensile bond strength and the length of microcracks formed after bracket debonding.