The purpose of this study was to compare maxillary anterior teeth positions and smile appearances between four first premolar extraction and nonextraction in Class I crowding cases. Forty-one participants with moderate Class I crowding who had finished orthodontic treatment were recruited and divided into two groups. The first group consisted of 21 participants who had finished nonextraction orthodontic treatment, and the other group consisted of 20 participants who had finished orthodontic treatment with four first premolars extracted. Smiling pictures in frontal and lateral positions of the participants were taken. In part one, the maxillary anterior teeth positions and smile appearances were measured and analyzed. In part two, the smile esthetic of the cropped frontal smiling pictures was rated by three certificated board orthodontists and ten laypersons using the visual analog scale (VAS), and then the VAS scores were compared between the nonextraction and the extraction groups. In the assessment using smiling pictures, the ratio of the distance between the maxillary dental midline and the distal surface of the maxillary canine to the distance between the maxillary dental midline and the angle of the mouth, as well as the ratio of the distance between the left and right maxillary canine cusp to the distance between the left and right alar of the nose in four first premolar group, was significantly higher than in the nonextraction group. The difference between the horizontal distance of the left and the right alar of the nose to left and right maxillary canine cusp tip in the four first premolar extraction group was significantly lower than the nonextraction group. Maxillary canines in the four first premolar extraction group are significantly closer to the alar of the nose and the labial commissures than the maxillary canines in the nonextraction group. Maxillary teeth positions and smile appearances evaluated from the other smile parameters did not differ significantly between the two groups.

This cross-sectional study was conducted in 80 patients at prosthodontics department, faculty of dentistry, Chulalongkorn University in 2022. Two outcomes, oral health (OHRQoL) and health-related quality of life (HRQoL), were interviewed using the Oral Impacts on Daily Performances and the World Health Organization Quality of Life-Bref index, respectively. Independent variables, collected by intraoral examination and interview, were general characteristics of patients, tooth loss status (number of posterior occluding pairs and remaining natural teeth), and removable denture status.  The association between each outcome and independent variables were analyzed using Mann-Whitney U or Kruskal-Wallis test. The correlation between OHRQoL and HRQoL score was calculated to determine the Spearman correlation coefficient. Data were analyzed at a 5% significance level. The results showed that a greater number of posterior occluding pairs (p = 0.019) and natural teeth (p = 0.001) and having functional denture (p = 0.001) were associated with better OHRQoL. Meanwhile, higher income (p = 0.09) and better medical conditions (p = 0.012) were associated with HRQoL. There was a correlation between psychological dimension of OHRQoL and overall HRQoL (Spearman rho = -0.217; p = 0.045). In conclusion, tooth loss and poor denture status were associated with worse OHRQoL. However, the OHRQoL and HRQoL were not directly related.

The aim of this in vitro study was to investigate the effect of the surface preparation by polishing on the microtensile bond strength of resin composite to carious dentin treated with silver diamine fluoride. Thirty human
posterior teeth with natural carious dentin were stored in artificial saliva for 14 days after application of 38 percent silver diamine fluoride on the carious lesion. After 14 days, the samples were sectioned in half through the middle of the carious lesion and randomly assigned to either the test or the control group (n=30), with or without superficial dentin polishing by 600-grit silicon carbide paper. Rinsing the specimens were performed prior to the bonding with composite resin using universal adhesives in etch-and-rinse mode. Following the bonding, the specimens were sectioned perpendicularly to the interface to produce sticks (1 mm x 1 mm in dimensions) and submitted to the microtensile bond strength testing. The bond strength data were obtained after 24-hour water storage by a universal testing machine, followed by the failure mode assessment with a stereomicroscope and a scanning electron microscope. Data were analyzed by independent samples T-test. The mean and standard variations of microtensile bond strength in the control and the test group, superficial dentin polishing, were 13.29 ± 11.67 MPa and 17.80 ± 12.34 MPa, respectively (p=0.000). The superficial polishing prior to the bonding affects the bond strength of resin composite to carious dentin of permanent tooth treated with silver diamine fluoride and promisingly encourages the bonding efficacy.

The purpose of this study was to evaluate wear resistance and surface roughness of injectable resin composites after undergoing chewing simulation and compared with those of conventional flowable resin composites and conventional paste resin composites. Ten specimens of each product from three different types: 1) two injectable resin composites (GU, BI), 2) two conventional flowable resin composites (SF, BF) and 3) two conventional paste resin composite (GP,BT), were fabricated in a sample holder and the top surface was polished using silicon carbide papers. The surface topography of the specimens was profiled using a three-dimensional contact profilometer before being subjected to a chewing simulation at 120,000 cycles with a flat enamel antagonist. The surface topography of the specimens was profiled again to determine the wear resistance and surface roughness (Ra). SEM was used to evaluate the surface characteristics of the specimens. After chewing simulation, the conventional flowable resin composites (BF and SF) showed lower wear volume (0.066±0.017 mm3, 0.084±0.015 mm3, respectively) than the others. The lowest maximum wear depth was found in the BF group (23.04±4.243 μm). The injectable resin composites (GU and BI) demonstrated a significantly (P<0.05) lower mean Ra value (0.147±0.036 μm, 0.168±0.051 μm respectively) than the others. The SEM micrographs of the GU group showed the smoothest surface texture while the BT group demonstrated the largest area of wear as well as the most prominent cracks and plucks of fillers. The baseline surface roughness and surface roughness after chewing simulation have a positive correlation (R=0.367, p=0.004). Wear volume and maximum wear depth have a positive correlation as well (R=0.892, p=<0.001). There was no
correlation between wear volume and surface roughness. In conclusion, the injectable resin composites exhibited material dependent wear resistance which might relate to intrinsic factors of the material. In addition, they exhibited

The objective of this study was to investigate the knowledge, attitudes, and practices concerning COVID-19 dental practice guidelines. A questionnaire was distributed to undergraduate dental students at the Faculty of Dentistry, Chulalongkorn University, who practiced in the clinic during the academic year 2022 through online platforms. Data was collected during December 2022 and February 2023. One hundred and fifty-seven responses were received and analyzed, resulting in a 53.95% response rate. The average knowledge score was 6.52 out of 10, with a standard deviation of 1.175. Among all respondents, 53.5% provided all correct answers related to general knowledge of COVID-19. However, only 10.2% and 8.9% accurately answered all questions regarding self- and interpersonal transmission prevention, and environmental contamination prevention, respectively. More than 80% of the participants exhibited a positive attitude toward infection control protocols. In contrast, 65.6% and 46.5% expressed positivity towards social distancing and COVID-19 risk assessment questionnaires, respectively. In accordance with the COVID-19 dental practice guidelines, practices that were consistently followed by over 80% of the respondents included wearing personal protective equipment during dental treatments, instructing patients to use antimicrobial mouthwash before treatment, and disinfecting dental unit surfaces before and after procedures. Additionally, more than 50% of UGs requested a laundry delivery room for long-sleeved gowns near treatment areas, as well as an increase in the availability of alcohol gel and air purifiers. In conclusion, while UGs exhibited positive attitudes, their knowledge and adherence to COVID-19 dental guidelines were lacking. Urgent actions are needed to enhance UGs’ understanding and compliance with these guidelines.