Degradability of nanocomposites after cyclic immersion in red and white wines

Aims: To investigate surface microhardness of nanocomposites after cyclic immersion in red and white wines. Materials and Methods: Seventy-two specimens of each resin composite were prepared. Before immersion, baseline data of Vicker′s microhardness were recorded and surface characteristics were examined using scanning electron microscopy (SEM). Three groups of discs (N = 23) were then alternately immersed in red wine, white wine, and deionized water (as a control) for 25 min and artificial saliva for 5 min over four cycles. The specimens were then stored in artificial saliva for 22 h. This process was repeated for 5 days following immersion in artificial saliva for 2 days. Subsequently, the process was repeated. After immersion, specimens were evaluated and data were analyzed by two-way repeated analysis of variance (ANOVA) and Tukey′s honest significant difference (HSD) (α = 0.05). Results: Microhardness values significantly decreased after being immersed in the red and white wines (P < 0.05). SEM photomicrographs presented surface degradation of all groups after immersion in red and white wines. Conclusion: The effect of red and white wines on surface microhardness of nanocomposite restorative materials depended on the physical and chemical compositions of the materials and the types of wine

Effect of Acidic Agents on Surface Roughness of Dental Ceramics

Background: An increase in surface roughness of ceramics may decrease strength and affect the clinical success of ceramic restorations. However, little is known about the effect of acidic agents on ceramic restorations. The aim of this study was to evaluate the surface roughness of dental ceramics after being immersed in acidic agents. Methods: Eighty-three ceramic disk specimens (12.0 mm in diameter and 2.0 mm in thickness) were made from four types of ceramics (VMK 95, Vitadur Alpha, IPS Empress Esthetic, and IPS e.max Ceram). Baseline data of surface roughness were recorded by profilometer. The specimens were then immersed in acidic agents (citrate buffer solution, pineapple juice and green mango juice) and deionized water (control) at 37°C for 168 hours. One group was immersed in 4% acetic acid at 80°C for 168 hours. After immersion, surface roughness was evaluated by a profilometer at intervals of 24, 96, and 168 hours. Surface characteristics of specimens were studied using scanning electron microscopy (SEM). Data were analyzed using two-way repeated ANOVA and Tukey′s multiple comparisons (α = 0.05). Results: For all studied ceramics, all surface roughness parameters were significantly increased after 168 hours immersion in all acidic agents (P < 0.05). After 168 hours in 4% acetic acid, there were significant differences for all roughness parameters from other acidic agents of all evaluated ceramics. Among all studied ceramics, Vitadur Alpha showed significantly the greatest values of all surface roughness parameters after immersion in 4% acetic acid (P < 0.001). SEM photomicrographs also presented surface destruction of ceramics in varying degrees. Conclusion: Acidic agents used in this study negatively affected the surface of ceramic materials. This should be considered when restoring the eroded tooth with ceramic restorations in patients who have a high risk of erosive conditions

Bacterial aerosols in the dental clinic: effect of time, position and type of treatment

Objectives: The objectives of this study were to investigate changes in the concentration of total bacterial aerosols before, during, and after the working period at different positions within the same multichair dental clinics. Also to investigate the contribution to total bacterial aerosols, if any, of the aerosols generated from different types of dental procedures, as well as the environment.\ud \ud Methods: Air sampling using a Slit-to-Agar air sampler at three positions in a multichair dental clinic, performed three times per day over a three week period before work, during work and after work. The second part of the study, in another multichair dental clinic, was performed before working and during three types of dental procedures.\ud \ud Results: The concentration of total bacterial aerosols and Bacillus sp. in air which circulated in the dental clinic was lower at the end of the day than at the beginning. There was no significant change in the concentration of total bacterial aerosols in different positions in the dental clinic or after the three types of dental treatments. The concentration of Bacillus sp. in air not mainly generated during dental procedures and which may come from an environmental source, was reduced.\ud \ud Conclusions: This study suggests that the proportions of different types of bacteria in air may change before, during and after dental treatment. Preventive measures may need to be instituted to reduce build up of bacterial aerosols in the dental clinic during non-working periods

The effect of incomplete crown ferrules on fracture resistance and the failure modes of endodontically treated maxillary incisors restored with cast posts, cores, and crowns

Introduction: The purpose of this study was to investigate fracture resistance and the fracture modes of endodontically treated teeth restored with cast posts and cores in the presence of various configurations of incomplete ferrules. Materials and Methods: Fifty maxillary anterior teeth were endodontically treated and divided into five groups (n = 10) according to ferrule design: group complete ferrule (CF) had a 2-mm circumferential ferrule; group buccal-mesial-palatal (BMP) had a 2-mm ferrule on the buccal, mesial, and palatal sides; group P had a 2-mm ferrule only on the palatal side; group B had a 2-mm ferrule only on the buccal side of the tooth; and group no ferrule (NF) had no ferrule. Each tooth was restored with a cast post, core, and a Ni–Cr crown. All specimens were lingually loaded at 135° to their long axis in a universal testing machine until fractured. Fracture patterns were recorded. Data were analyzed using one-way analysis of variance and Tukey’s honestly significant difference (Tukeyï½s HSD) test (α = 0.05). Results: The highest load to fracture was CF (534.33 ± 100.30 N), followed by BMP (467.71 ± 54.54 N), P (462.71 ± 54.92 N), B (330.48 ± 54.86 N), and NF (275.93 ± 28.35 N), respectively. There was no statistically significant difference in load to fracture among CF, BMP, and P and between B and NF (P > 0.05). Conclusion: A tooth with incomplete ferrule had lower fracture resistance than one with complete ferrule, but it was still higher than one with no ferrule. The presence of a palatal ferrule was more effective than a buccal ferrule in providing fracture resistance to palatal occlusal loads

Occupational hygiene practices of dentists in southern Thailand

Objectives: The aims of this study were to investigate the prevalence and nature of infection control, radiation control and handling of mercury, reported by dentists in southern Thailand.\ud \ud Method: A cross-sectional study with self-report questionnaire to all 220 dentists working in 14 provinces in southern Thailand in 1997.\ud \ud Results: 178 dentists (80.9%) aged 22–54 years responded. All reported wearing personal protective measures, at least sometimes and using high level disinfection (formerly sterilisation) procedures for handpieces. Most (93.8%) reported changing sterilised handpieces for each patient. The most commonly reported method of high level disinfection was alcohol (37.1%). Just over two-thirds (68.0%) reported having HBV vaccination. Most (94.3%) reportedly took precautions when radiographs were taken and (89.9%) reported protecting their eyes with a UV/blue light shield or filter while using these units. About half of dentists (51.7%) reported storing excess amalgam under water compared with 20.1% that they stored it in a closed box. 77.7% reported using sealed mercury amalgam capsule systems, at least sometimes. Nearly half (47.1%) reported disposing of used capsules in the bin.\ud \ud Conclusions: The present study has indicated that occupational hygiene practices of dentists in southern Thailand are generally consistent with published guidelines for infection control and also with other populations of dentists studied in the areas of infection control and radiation protection. Further continuing education and investigation of appropriate interventions to promote good occupational hygiene standards may also be needed

Occupational health problems of dentists in southern Thailand

Aims: To investigate the prevalence and nature of some occupationally related health problems in dentists in southern Thailand.\ud \ud Design: A cross-sectional study using a self-report questionnaire distributed to all 220 dentists working in 14 provinces in southern Thailand in 1997.\ud \ud Participants: One hundred and seventy-eight dentists aged between 22 to 54 years responded.\ud \ud Results: The most common occupational health problems were musculoskeletal pain (78 per cent) and percutaneous injury (50 per cent). Associated factors were analysed using multivariate analysis. About 22 per cent of these dentists had a history of contact dermatitis mostly caused by allergy to latex gloves, 15 per cent had eye problems, and 3 per cent had hearing problems.\ud \ud Conclusions: Continuing education in the avoidance of percutaneous injuries would be beneficial, as exposure to potential infectious agents is of concern. Further studies are needed to identify causes of musculoskeletal pain and to identify appropriate interventions to reduce its prevalence, as would similar measures to reduce exposure to agents which may be producing contact dermatitis

Effect of Mouthwashes for COVID-19 Prevention on Surface Changes of Resin Composites

ABSTRACT: Objective: The aim of this research was to investigate the effect of various mouthwashes for COVID-19 prevention on surface hardness, roughness, and colour changes of bulk-fill and conventional resin composites and determine the pH and titratable acidity of mouthwashes. Methods: Four hundred eighty specimens were fabricated in cylindrical moulds (10 mm in diameter and 2 mm in thickness). Before immersion, baseline data of surface hardness, roughness, and colour values were recorded. Each product of specimens (Filtek Z350XT, Premise, Filtek One Bulk Fill Restorative, SonicFil 2) were divided into 4 groups for 0.2% povidone iodine, 1% hydrogen peroxide, 0.12% chlorhexidine, and deionised water (serving as a control). The specimens were immersed in mouthwashes for 1 minute and then stored in artificial saliva until 24 hours. This process was repeated for 14 days. After immersion, surface hardness, roughness, and colour values of specimens were measured at 7 and 14 days. The data were statistically analysed by 2-way repeated analysis of variance, Tukey honestly significant difference, and t test (P < .05). Results: After immersion, all mouthwashes caused significantly lower surface hardness and greater roughness and colour values (P < .05) on all resin composites tested. Conclusions: Mouthwashes had an effect on all resin composites evaluated leading to a significant decreased surface hardness and an increased roughness and colour values (P < .05)