Characteristics of airborne particles in stone quarrying areas: Human exposure assessment and mitigation.

This investigation aims to assess the levels of human exposure to airborne particulate matter (PM) in various locations of a natural stone quarry for the first time based on simultaneous measurements of both PM mass and number concentrations (PMC and PNC). A quarry located in Danang city, Vietnam, considered to be a "hotspot" of air pollution in the city, was selected for detailed investigations. Both PMC and PNC were found to be significantly higher (1.2-6.0 times) within the quarry compared to surrounding areas. Mechanical activities during mining, notably crushing, screening, hauling, and loading stones, contributed to increased emissions of PM in the coarser mode (1-10 µm) compared to the accumulation mode (0.1-1 µm) and thus increased deposition of PM1-10 in the human upper respiratory tract. In contrast, combustion activities, especially the diesel engine exhaust from various machines and vehicles used in the quarry, resulted in increased emissions of small particles in the accumulation mode that dominated the PNC and in their deposition in the lower respiratory tract. Simultaneous measurements of PNC and PMC revealed that the PM counts were strongly associated with PM deposition in the alveolar region (accounting for ≈ 76% of total PNC of particles less than 10 µm, N10), while the PM mass concentration was a better indicator of the deposition of PM in the head airway region (≈92% of total PMC of PM10). Overall, this study demonstrates the significance of measuring both PNC and PMC to assess PM exposure levels, regional respiratory doses, and potential health effects associated with human exposure to PM generated from stone quarrying activities. The novelty of this work is the integration of real-time mass and number concentrations of PM over the size range from 20 nm to 10 µm to provide insights into respiratory deposited doses of size-fractionated PM among quarry workers.

Risk factors associated with the severity of pericoronitis of mandibular third molar.

PURPOSE: The factors related to pericoronitis severity are unclear, and this study aimed to address this knowledge gap. MATERIALS AND METHODS: In total, 113 patients with pericoronitis were included, and their demographic, clinical, and radiographic characteristics were recorded. The Patient-Clinician Pericoronitis Classification was used to score and categorize the severity of pericoronitis. Statistical analysis was conducted to examine the participants' characteristics, validity of the Patient-Clinician Pericoronitis Classification, and risk factors associated with the severity of pericoronitis. RESULTS: The demographic, clinical, and radiographic characteristics of males and females were similar, except for Winter's classification, pain, and intraoral swelling. The constructive validity of the Patient-Clinician Pericoronitis Classification was confirmed with three latent factors, including infection level, patient discomfort, and social interference. Ordinal logistic multivariate regression analysis revealed that upper respiratory tract infection was the sole risk factor associated with pericoronitis severity in males (odds ratio = 4.838). In females, pericoronitis on the right side (odds ratio = 2.486), distal radiolucency (odds ratio = 5.203), and menstruation (odds ratio = 3.416) were significant risk factors. CONCLUSION: This study demonstrated the constructive validity of the Patient-Clinician Pericoronitis Classification. Among females, pericoronitis in mandibular third molars on the right side with radiolucency in menstruating individuals was more severe. In males, upper respiratory tract infection was the sole risk factor associated with pericoronitis severity. CLINICAL RELEVANCE: Individuals with risk factors should be aware of severe pericoronitis in the coming future.

Zinc Deficiency and the Severity of Pneumonia in Vietnamese Children: A Hospital-Based Study.

Background Pneumonia is a critical global health concern that often results in severe complications and fatalities, especially among young children. Zinc plays a crucial role in immune function and maintaining respiratory epithelial integrity. Despite its importance, data on the prevalence of zinc deficiency and its impact on pneumonia severity in Vietnamese children are limited. Objectives This study aimed to investigate the prevalence of zinc deficiency and its association with pneumonia severity in Vietnamese children under five years old. The findings could significantly contribute to our understanding of the role of zinc in pneumonia severity, guiding future public health interventions, nutritional policies, and clinical practices to prevent zinc deficiency and reduce pneumonia morbidity and mortality in children. Methods An analytical cross-sectional study was conducted at a major pediatric center in Southwestern Vietnam from December 2022 to February 2024, involving 222 children aged 2 to 59 months diagnosed with pneumonia. Clinical assessments and laboratory measurements, including serum zinc levels, were performed. Statistical analyses were conducted to compare clinical characteristics and outcomes between zinc-deficient and non-deficient groups. Multivariable logistic regression was used to assess the association between zinc deficiency and pneumonia severity, with statistical significance set at p<0.05. Results The prevalence of zinc deficiency among children with pneumonia was 74.3%. Zinc-deficient children showed a significantly higher proportion of severe pneumonia (57.6% vs. 8.8%, p<0.001), as well as a higher proportion of high fever, poor feeding, vomiting, and respiratory distress compared to non-deficient children (p<0.001). Multivariable logistic regression identified zinc deficiency as an independent predictor of severe pneumonia (aOR=13.1, 95% CI: 4.7-36.8, p<0.001). Conclusion Zinc deficiency was prevalent among Vietnamese children with pneumonia and was associated with an increased risk of severe pneumonia.

Validity and Reliability of the Vietnamese Version of the Dental Fear Survey.

OBJECTIVES: The use of questionnaires to assess patients' dental fear is critical to dental research and practice. As one of the most well-established tools in this field, the Dental Fear Survey (DFS) was translated into Vietnamese (V-DFS) and employed in previous studies. However, its validity and reliability have not been reported. This study aimed to determine the validity and reliability of V-DFS in adults. METHODS: The DFS was translated to Vietnamese in accordance with the "Guideline for the Process of Cross-cultural Adaptation of Self-reported Measures" to create the V-DFS. Next, 414 students at Pham Ngoc Thach University of Medicine completed the V-DFS to examine its validity and reliability. The factorial validity of V-DFS was assessed using exploratory factor analysis (EFA) and structural equation modeling (SEM). The internal consistency and test-retest reliability of the V-DFS were assessed using Cronbach's alpha (α), intraclass correlation coefficient (ICC), and Spearman's rank-order correlation coefficient (rs). RESULTS: The rotated component matrix of the EFA revealed 3 factors: specific stimuli, anticipatory fear and avoidance, and physiologic arousal. The statistical indices of the best-fitting V-DFS model in SEM analysis satisfied the cutoff values. Cronbach's α ranged from .82 to .94 for the 3 factors. The ICC and rs of the whole questionnaire were .86 and .86, respectively. CONCLUSIONS: DFS was successfully translated into Vietnamese with good validity and reliability. Further research should be conducted to examine its validity in various populations and to improve its characteristics.

Improvement of the Impacted Level of Lower Third Molars After Orthodontic Treatment.

OBJECTIVES: The early or delayed surgical removal of an asymptomatic lower third molar (M3) in orthodontic patients remains controversial. This study aimed to determine the changes in the impacted level of M3 such as angulation, vertical position, and eruption space, after orthodontic treatment in 3 groups, namely non-extraction (NE), first premolar (P1) extraction, and second premolar (P2) extraction. METHODS: Relevant angles and distances related to 334 M3s from 180 orthodontic patients were assessed pre- and posttreatment. Angle between lower second molar (M2) and M3 (M3-M2) was used for evaluating M3 angulation. For M3 vertical position, distances from occlusal plane to the highest cuspid (Cus-OP) and fissure (Fis-OP) of M3 were used. Distances from the distal surface of M2 to anterior border (J-DM2) and centre (Xi-DM2) of the ramus were used for assessing M3 eruption space. Pre- and posttreatment values of the angle and distance in each group were compared using a paired-sample t test. Measurements of the 3 groups were compared using analysis of variance. Hence, multiple linear regression (MLR) analysis was used to determine significant factors that impacted changes in M3s' related measurements. Independent factors used for MLR analysis included sex, treatment starting age, pretreatment respective angle/distance, and premolar extraction (NE/P1/P2). RESULTS: M3 angulation, vertical position, and eruption space at posttreatment were significantly different from those at pretreatment in all 3 groups. MLR analysis showed that P2 extraction significantly improved M3 vertical position (P < .05) and eruption space (P < .001). P1 extraction significantly decreased Cus-OP (P = .014) and eruption space (P < .001). Treatment starting age was significant factor that affected Cus-OP (P = .001) and M3 eruption space (P < .001). CONCLUSIONS: After orthodontic treatment, M3 angulation, vertical position, and eruption space changed in favour of the impacted level. These changes in the 3 groups were clearer in order: NE, P1, and P2, respectively.

Anatomical Positions of Mesially/Horizontally Impacted Mandibular Third Molars are Significant Predictors for Distal Caries in Adjacent Second Molars.

Background: Prevalence of distal caries in mandibular second molars (M2Ms) and its relationship with impacted condition of the adjacent mandibular third molars (M3Ms) have been reported in some studies. The results, however, were ambiguous because of including all impaction types and using univariate analysis for statistics. Aim: This study aimed to determine anatomical features of mesially/horizontally impacted mandibular third molars (M3Ms) that could predict distal caries in the adjacent mandibular second molars (M2Ms) using multivariable analysis. Materials and Methods: The study sample consisted of 300 digital panoramic radiographs of patients who underwent impacted M3Ms extraction. Two independent researchers collected the following variables from 446 pairs of M2M-M3M: sex, age, status of distal caries in M2Ms, mesial angulation, and Pell-Gregory classification of M3Ms. Results: The prevalence of distal caries was 50.67%. Multivariable Firth's logistic regression analysis showed that age (ß = 0.066, 95% CI = 0.023-0.113), mesial angulation (<30°: ß = -1.205, 95% CI = -1.955 to -0.499; >70°: ß = -0.730, 95% CI = -1.184 to -0.282), vertical position (level B: ß = 2.275; 95% CI = 0.015-7.175; level A: ß = 3.008; 95% CI = 0.755-7.905), and horizontal position (level II: ß = 1.515; 95% CI = 0.444-2.874; level I: ß = 1.423; 95% CI = 0.283-2.825) were significant variables after adjusting for sex in the final model for predicting distal caries (p < 0.05). Conclusions: In conclusion, anatomical positions of impacted M3Ms, such as mesial angulation and Pell-Gregory classification were significant predictors of distal caries in M2Ms.

Effect of Photobiomodulation Therapy on Reducing Acute Pain and Inflammation Following Surgical Removal of Impacted Mandibular Third Molars: A Randomized, Split-Mouth Clinical Trial.

Objective: This study aimed to compare the effects of photobiomodulation therapy (PBMT) on analgesic and inflammatory reduction with that of ibuprofen following surgical removal of impacted mandibular third molars (IMTMs). Methods: A randomized, split-mouth clinical trial was performed on patients undergoing bilateral IMTM removal. PBMT [gallium aluminum arsenide (GaAlAs) laser] with specific parameters (wavelength of 810 nm, power of 0.5% ± 20% W, and energy density of 4 J/cm2) was applied randomly on one side of the mouth immediately after surgery and 1 and 2 days after surgery. The pain level was self-rated with a Likert scale at 2, 4, 6, 24, and 48 h postoperatively. Swelling and trismus were measured on the first and second day after surgery. Saliva was collected for measuring pre- and postoperative salivary immunoglobulin A (sIgA) concentrations with the sandwich ELISA test. Results: The study sample included 25 patients (average age of 22.88 years) with 50 bilateral symmetrical IMTMs. Pain level was highest at 2 h after surgery in both groups and gradually decreased over time (p < 0.01). Swelling and trismus at 48 h were higher than at 24 h (p < 0.01). Within the first 48 h postoperatively, pain level, swelling, and trismus were significantly lower in the PBMT group (p < 0.05). Postoperative sIgA was also significantly lower in the PBMT group (p < 0.05). Conclusions: In short-term and specific conditions of this study, it was found that PBMT helped promote postoperative pain relief and anti-inflammation after surgical removal of IMTMs. The results suggested that there may be a link between a decrease in salivary sIgA levels and decrease in inflammatory processes after PBMT. Trial Registration No. NCT04280809 at ClinicalTrials.gov.

The Effects of Providing Advance Notice and Stress-Coping Traits on Physiological Stress of Patients during Dental Treatment.

Patients tend to feel stress in association with dental treatment due to uneasiness and fear. We investigated the effects of providing advance notice and stress-coping traits on the physiological stress of patients during dental treatment. Sixty non-dental professionals (male, n = 26; female, n = 34; mean age, 49.9 years) were recruited for this study and informed consent was obtained. Subjects were given simulated dental treatment including three stimuli, air, percussion and running of an air turbine, with or without advance notice of the stimulation during dental treatment. Real-time sympathetic nerve activity (SN) and parasympathetic nerve activity (PN) during the treatment were measured using a biological information monitor. The stress-coping traits of each subject were examined using the Lazarus-Type Stress Coping Inventory (SCI). Correlations between the nerve-activity and scores of eight stress-coping strategies of SCI and the presence/absence of advance notice were analyzed. Age, types of stimuli and order of stimuli significantly affected SN, while age, types of stimuli, and the pattern of stimulation significantly affected PN. The interaction of the stress-coping trait and presence/absence of advance notice significantly affected PN. Providing advance notice may have different effects on physiological stress depending on how the patient copes with stress.

Simplified conditions for storing and cryopreservation of dental pulp stem cells.

OBJECTIVES: This study aimed to simplify the collection, isolation and cryopreservation procedure of human dental pulp stem cells (DPSCs) to ease the establishment of dental stem cell banking. DESIGN: Extracted third molars were collected and stored either in growth medium or in gentamicin-saline (480µg/ml) for 6, 9 or 12h. DPSCs were isolated and subjected to cryopreservation by a controlled-rate or rapid freezing method in 5 or 10% DMSO. Flow cytometry and growth pattern of DPSCs before and after cryopreservation were conducted. RESULTS: Rate of contamination by which the extracted teeth were stored in control and gentamicin-saline were 9.1% (N=33) and 2.3% (N=43), respectively. Successful cell isolation rate of teeth preserved in gentamicin-saline at 6h (92.9%) was comparable to those of growth media group (90.3%). At 9 and 12h, the rates dropped significantly to 75% and 54%, respectively. Cryopreservation by controlled-rate freezing either in 5 or 10% DMSO resulted in a significantly higher percentage of viable cells than by rapid freezing. Cells conserved by controlled-rate freezing in 5% DMSO showed a pattern of growth similar to control unfrozen cells; 10% DMSO significantly deteriorated the growth pattern of the cells. After thawing, DPSCs conserved by controlled-rate freezing still expressed stemness characteristics, although hematopoietic stem cell markers were slightly increased. CONCLUSION: Gentamicin-saline was effective in preserving human teeth for DPSC isolation. Controlled-rate freezing in 5% DMSO gave the highest rate of cell viability. This study simplifies the storage conditions and proposes a simple method for cryopreservation of DPSCs.