High-speed Handpiece Research Articles

A comparative evaluation of fracture resistance of three recent composite systems in Class II mesio occluso distal cavities - An in vitro study

Though composite resins have received popularity as restorative materials because of their physical properties, there was a dearth in the research about fracture resistance among recently emerged composite systems including Tokuyama Estelite Sigma Quick, Admira Fusion, and Beautifil II LS nanohybrid composite systems. To compare and evaluate the fracture resistance of maxillary premolars with class II mesio occluso distal cavities restored with Tokuyama Estelite Sigma Quick, Admira Fusion, and Beautifil II LS nanohybrid composite systems. Current invitro research was conducted on 44 intact human premolar teeth- Eleven specimens were kept completely intact for control group (Group G1). Class II MOD cavities were done with high-speed handpiece and under constant irrigation in remaining 33 teeth, Group G2, Group G3, Group G4 were restored with Tokuyama Estelite Sigma Quick (Tokuyama Dental, Tokyo, Japan.), Beautifil II LS (Shofu, Germany.), Admira Fusion (Shofu, Germany.) respectively. SPSS version 20 software to analyse the data; and ANOVA followed by Tukey’s post-hoc analysis to compare the fracture resistance were used. With a fracture resistance of 1297.27±10.27 N, Group 1 (Control) had highest fracture resistance. Group 4 has the least fracture resistance (Admira Fusion). Every pairwise comparison was significant too. Among the three materials studied, Beautifil II LS had higher fracture resistance and Admira Fusion had the least fracture resistance.

Three-axis load analysis of high-speed handpiece on dental training teeth and computer-aided design/computer-aided manufacturing blocks

This study aimed to evaluate and compare the mechanical properties of dental training teeth with subtractive and additive computer-aided design/computer-aided manufacturing (CAD/CAM) materials used to fabricate dental simulation models. Therefore, the three-axis load generated during cutting movements, including drilling and milling performed using a dental handpiece, was measured and compared. The samples were cut vertically downward by 1.5 mm, horizontally by 6 mm, and vertically upward at a constant speed (1 mm/s), while the rotational speed of the bur was maintained at 200,000 rotations per minute. A three-axis load cell was used to measure the X-, Y-, and Z-axis loads on the specimen. The median value of the X-, Y-, and Z-axis measurements and the resultant load during the vertical-downward, horizontal, and vertical-upward movements were compared using a one-way analysis of variance and Tukey's post hoc test. For vertical downward movement, the drilling force of the dental training teeth was lower than that of Vita Enamic® and similar to that of Lava™ Ultimate. In contrast to subtractive CAD/CAM blocks, the drilling force of the dental training teeth was higher than that of 3D-printed resin blocks. Regarding horizontal movement, the milling force of dental training teeth was lower than that of Vita Enamic®. In contrast, the milling force of Nissin was similar to that of Lava™ Ultimate, while that of Frasaco was lower. Furthermore, compared to additive CAD/CAM blocks, the milling force of the dental training teeth was higher than that of 3D-printed resin blocks. Regarding vertical upward movement, the resultant loads of dental training teeth was lower than that of Vita Enamic®. Similarly, the resultant load of Nissin was similar to that of Lava™ Ultimate, while that of Frasaco was lower. Additionally, compared to additive CAD/CAM blocks, the resultant loads of the dental training teeth were similar to those of the 3D-printed resin blocks.

Efficiency of a high-speed handpiece with anti-retraction adapter to minimize cross-contamination during the routine dental procedure: A clinical study.

This study aimed to detect the efficiency of anti-retraction adapter (ARA) attached to a handpiece (HP). Two types of dental HP with and without the ARA were used in this study. A total of 30 sets of samples were obtained from two groups and were subjected to a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and microbial culture for quantitative analysis of total bacterial and Legionella count. The data obtained were tabulated using the Statistical Package for the Social Sciences (SPSS, IBM version 26.0) for statistical analysis. The water samples were analyzed using PCR, Legionella-specific PCR, and culture-based analysis. In Groups 1 and 2, there was no significant difference between bacterial load in the water samples taken from both HP and coupling of the Dental Unit Waterline (DUWL). The reduction in bacterial load in DUWLs analyzed using quantitative RT-PCR was similar in both experimental groups. Overall, the bacterial load was lower in the group with ARA when compared to the group without ARA but not statistically significant. ARA was not effective in reducing the Legionella species load in DUWLs.

Induction of Reparative Dentin Following Pulpotomy with Calcium Hydroxide at Four Week Follow up visit: A Case Report

This in-vivo study used calcium hydroxide pulpotomy of a premolar tooth to investigate the potential for reparative dentin development without causing unfavorable side effects. For cosmetic reasons, a pulpotomy using calcium hydroxide was used to treat a patient's right first premolar tooth. In order to expose the pulp, a round cavity with a diameter of 2 mm was initially created on the occlusal surface using a flat end fissure bur and a high-speed hand piece under adequate cooling conditions. After using sterile cotton pellets to staunch the bleeding, Dycal was applied to the exposed pulp tissue in accordance with the manufacturer's instructions. The tooth was pulled at 4 weeks under local anesthetic, and it was preserved for 24 hours in 4% neutral buffered formaldehyde. After being demineralized, the specimen was imbedded in paraffin. A blind observer used a light microscope fitted with a digital camera and a computer for histometry to examine a series of sections containing pulp tissue that had been longitudinally serially sectioned at a thickness of 6 µm. lastly, the experimental tooth's amount of newly generated hard tissue was measured. The findings indicated that the exposed pulp tissue is only partially covered by the 0.9 ± 0.2 µm thick layer of reparative dentin development. In conclusion, although it does not entirely cover the exposed pulp, calcium hydroxide can promote reparative dentin production and pulpal lesion healing in exposed teeth.

In Vitro Analysis of Outcome Differences Between Repairing and Replacing Broken Dental Restorations.

Objective In light of several advancements and considerations in endodontic dentistry, there still remains a need to comprehensively evaluate the outcome disparities between repairing and replacing broken dental restorations. This study aims to compare the effectiveness of repairing dental restorations versus replacing them, focusing on how each method affects the structural strength and longevity of the restorations. Methods The study included 60 freshly removed human maxillary premolars. Initial processing involved rigorous washing, descaling, and polishing of the teeth. To ensure preservation, the specimens were stored in sterile, distilled water. To occlude the root canals, a self-hardening composite resin was used, and the roots were coated with two coats of clear nail polish to prevent moisture penetration. A 245 carbide bur attached to a high-speed dental handpiece with air and water spray cooling produced standardized Class II cavities on the occluso-proximal surfaces. Each cavity had a buccolingual breadth of 2 mm, an occluso-cervical length of 4 mm, and a gingival boundary that was 1 mm coronal to the cement-enamel junction. Following this preparation, the teeth were randomly separated into three groups (Group A, Group B, and Group C), each containing 20 teeth. Results Our analysis showed that teeth with entirely replaced restorations had a higher average fracture resistance than those with repaired restorations. However, the difference in fracture resistance between the repair and replacement groups for each type of material was not statistically significant. Conclusion Based on the findings, repairing a dental restoration can be a conservative and less invasive alternative to a full replacement without a significant compromise in the restoration's ability to withstand fracture. Therefore, dental professionals might consider full restoration as a viable option, taking into account the need to preserve dental tissue as well as the restoration's durability and structural integrity.

The Effect of Surface Treatments on Shear Bond Strength between Orthodontic Metal Bracket and Porcelain Face

Objectives: To report on the different approaches taken to improve the bonding of orthodontic brackets to porcelain surfaces and review the literature and test the available alternatives of hydrofluoric acid use. Materials and Methods: The search engine PubMed, Scopus, Google Scholar and Science Direct were used for this study to obtain relevant information. The sample comprises 18 Porcelain fused to metal crowns, etchant acids like Hydrofluoric Acid 9.6%; Orthophosphoric Acid 37%; Maleic Acid 10, 20, 30%. Acrylic tooth holder, high-speed hand piece, round bur, bonding agent, composite, brackets, bracket holder, light cure, and Universal Testing Machine were all used to conduct the study at Ajman University Prosthodontic Laboratory. Results: The highest shear bond strength value was observed for sandblasting without any acid etching. Maleic Acid 30% were found to have the highest shear strength amongst all other acids after 1-minute etching, while Maleic Acid 20% showed the highest value after etching for 2-minutes. Orthophosphoric Acid 37% showed the highest shear strength compared to the other acids after 3-minutes etching. Conclusions: Two essential factors to be considered when bonding in orthodontics is the concentration of acid being used and the amount of time subjected to the surface. Sandblasting alone without using any acid etching has the highest value, and it hails to be one of the most effective ways of increasing bond strength. Furthermore, compared with all the acids we have used, Maleic acid of 30% has shown the highest shear strength after 1-minute of etching.

Impact of high-speed handpiece noise-induced dental anxiety on heart rate: analyzing experienced and non-experienced patients - a comparative study

BackgroundDental anxiety is very much common among the patients and could be due to different factors like the behavior of the dentist, past experiences, Needle phobia, or word of mouth from other patients. According to recent studies, a strong association between sound and anxiety has been found, so this observational study has been conducted to find out the link between the activation of anxiety with the sound of a handpiece between experienced patients, who have already gone through the dental treatments and non-experienced patients.MethodsTotal of 297 participants were part of this study. These participants were divided into 2 groups according to the experienced and non-experienced dental patients. The researcher first filled out the CORAH Dental Anxiety Scale (DAS) form to mark the anxiety level of the patients, and then noted the readings of the heart rate in 3 intervals which were before during, and after the treatment with the pulse oximeter. Later the data was analysed using the SPSS independent t-test.ResultsResults show that patients in group 1 who have gone through the dental treatment before were less anxious and had a lesser effect on their heart rate than the patient who were having the treatment for the first time who were in group 2. Another interesting factor was noticed that in both the groups female were found to be more anxious than male participants. Participants with younger age were found to be more anxious than older age patient in both groupsConclusionsThe sound of the handpiece can provoke anxiety in the patient, affecting the heart and increasing the heart rate. Participants who were experienced were found to be less anxious than the participants who were inexperienced.

A Light Microscopic Study Comparing Pulp Histological Alterations Following Tooth Preparation Using a High-speed Handpiece and an Er: YAG Laser.

Histological alterations were evaluated in this study after tooth preparation with carbide burs using a traditional handpiece and Er: YAG laser. Tooth preparation was done on 30 intact maxillary first premolars of healthy patients. Ten maxillary first premolars were used as control, wherein no tooth preparation was done. Box-shaped tooth preparation was done on the occlusal surface of maxillary first premolars using carbide bur in the handpiece and Er: YAG laser (n = 10). After performing the recommended procedure for different groups, each tooth was extracted and 4-5 μm thick sections were prepared and stained using H and E stains. A 4-40× microscope was used to examine the morphological alterations in the odontoblasts. The Chi-square test was used to compare the outcomes. The high-speed drill group and the control group had statistically significant differences (P = 0.05). High-speed drill and laser group differences were not statistically significant (P > 0.05). The histological findings as seen with laser tooth preparation were nearly identical to those of control or nonmanipulated teeth under light microscope, whereas disruption of odontoblastic layer was seen with high-speed drills.

Effect of Using Hydrogen Peroxide for Periodic Disinfection Combined With Continuous Disinfection to Control Contamination in Dental Unit Waterline

To observe the effect of using hydrogen peroxide in periodic disinfection combining with continuous disinfection of dental unit waterlines and to provide references for the selection of waterway disinfection measures. A total of 4 dental units in a hospital of stomatology were selected through convenience sampling. The dental unit waterlines received periodic disinfection once every 4 weeks in addition to continuous disinfection (When the dental units were not used for more than 3 days, an additional periodic disinfection would be performed.). Periodic disinfection referred to filling up the waterlines with a disinfectant solution (1.4% hydrogen peroxide) by using the waterline disinfection device that came with the dental unit, immersing for 24 hours, and then emptying out the disinfectant solution. Continuous disinfection referred to using hydrogen peroxide at a concentration of 0.014% as dental treatment water and using it to flush the waterlines for 2 minutes before any dental treatment in the morning and to flush the waterlines for 30 seconds after each dental treatment. The study lasted for 25 weeks, with periodic disinfection being performed for 7 times and continuous disinfection carried out for the rest of the dental treatment time. During the 25 weeks, water samples were collected from air/water syringes and high-speed handpieces. Then, the water samples were incubated and the bacterial concentration and the qualification rates were calculated accordingly. When the bacterial concentration≤100 CFU/ mL, the water samples were considered to be qualified. Waterline tubes of 1 cm were collected before and after the 25 weeks of disinfection with hydrogen peroxide. Biofilms in the waterline tube were observed under scanning electron microscope. A total of 352 water samples were collected. Eight water samples were collected before disinfection with hydrogen peroxide, with the median of bacterial concentration being 3140 CFU/mL. On the first day of disinfection with hydrogen peroxide, the median bacterial concentration in dental treatment water was 7.5 CFU/mL. There was a significant difference between the bacterial concentration of the water samples before the disinfection and that after the disinfection (P=0.012). A total of 344 water samples were collected after the disinfection, with the median bacterial concentrations for air/water syringes and high-speed handpieces being 11 CFU/mL and 11CFU/mL and the qualified rates being 83.7% and 82.0%, respectively. There was no significant difference in bacterial concentration or the qualification rates. During week 1 through week 9 of the disinfection, the qualification rates of the dental treatment water always exceeded 80% in 8 weeks, with week 3 being the exception. In the two four-week disinfection periods of week 14 through week 17 and week 18 through week 21, the qualification rate was maintained at above 80% for only the first two weeks and started to decrease from the third week. Biofilm morphology was observed under scanning electron microscope. Before the disinfection, the biofilm was found to be a dense structure and the mixture of a large number of bacteria. After 25 weeks of the disinfection, the biofilm structure appeared to be loose and did not show consistent characteristics of a large number of bacteria retained. Periodic disinfection combined with continuous disinfection using hydrogen peroxide can effectively control contamination in dental unit waterlines. But the cycles of periodic disinfection and the concentration of hydrogen peroxide for continuous disinfection should be further discussed according to the actual clinical situation.

The Effect of Water Coolant and Bur Type on Pulp Temperature When Removing Tooth Structure and Restorative Dental Materials.

The aim was to compare intrapulp temperature (IPT) changes when flat-fissure diamond burs and pear-shaped tungsten carbide burs were used to cut tooth structure, amalgam, and composite resin with and without water coolant. Thermocouples were inserted into the pulp chamber of extracted intact mandibular molars. The thermocouples were connected to an electronic thermometer that detects temperature every second to an accuracy of 0.1°C. IPT changes were recorded while using a high-speed handpiece during MOD cavity preparations (n=40), composite resin removal (n=40), and amalgam removal (n=40). A two-way ANOVA was used for each procedure to test for the effect of bur (pear-shaped tungsten carbide vs flat-fissured diamond) and water coolant (on vs off), with significant main effects (α=0.05) further analyzed using Tukey's multiple comparison test. During MOD cavity preparation, water coolant reduced changes in IPT (0.03±0.27°C) compared to no water coolant (1.27±0.29°C) when tungsten carbide burs were used (p<0.05) but not when diamond burs were used. During composite resin removal, tungsten carbide burs had less changes in IPT (0.55±0.18°C) compared to diamond burs (1.66±0.50°C) with no water coolant (p<0.05). Water coolant also reduced changes in IPT (0.09±0.14°C) compared to no water coolant (1.66±0.50°C) when diamond burs were used (p<0.01). Water coolant did not significantly affect IPT when tungsten carbide burs were used. During amalgam removal, tungsten carbide burs had lower changes in IPT (0.56±0.15°C) compared to diamond burs (1.88±0.43°C) with no water coolant (p<0.05). Water coolant also significantly reduced changes in IPT (0.71±0.2°C) compared to no water coolant (1.88±0.43°C) when diamond burs were used (p<0.05) but not when tungsten carbide burs were used. Water coolant reduced IPT changes when drilling tooth structure with tungsten carbide burs, but not when removing amalgam or composite. Conversely, water coolant reduced IPT changes when drilling with flat fissure diamond burs to remove amalgam and composite, but not when removing tooth structure. When amalgam and composite were removed without water coolant, the tungsten carbide burs resulted in lower IPT changes than when flat fissure diamond burs were used in the same way.

Effect of Self-Adhesive Resin Cement Film Thickness on the Shear Bond Strength of Lithium Disilicate Ceramic–Cement–Tooth Triplex

Cement film thickness may have an impact on the shear bond strength (SBS) of lithium disilicate dental ceramics luted to human enamel with resin cement. The objective of this study was to evaluate SBS of lithium disilicate ceramics adhered to enamel using resin cement at different thicknesses. In total, 50 ceramic specimens (3 × 3 × 3 mm) and 50 premolar teeth were prepared and randomly assigned to 5 groups (n = 10 each). Ceramic specimens were designed with five cement film thicknesses (50 μm; 100 μm; 150 μm; 200 μm; and 300 μm). Teeth surfaces (4 × 4 mm) were prepared with a high-speed handpiece mounted on a dental surveyor. Ceramic specimens were cemented to teeth with resin cement (3MTM RelyXTM U200, Resin-Self-Adhesive-Cement). The specimens were then thermocycled for 6000 cycles with a 30 s dwell time and a 5 s transfer time in water (5 °C and 55 °C). A Universal-Testing-Machine was used to measure SBS (MPa). Statistical analysis in SPSS included Anova and Tukey’s tests. The SBSs of ceramics adhered to teeth revealed significantly different values across all test groups (p = 0.000). The findings showed that as cement layer thickness increased, so did the SBS. The cement spaces at 50 and 300 μm had the lowest SBS (9.40 + 1.15 MPa) and maximum SBS (21.98 + 1.27 MPa), respectively. The SBS of the lithium disilicate ceramic luted to natural human enamel increased along with the cement layer thickness.

The effect of location and method of tooth preparation on aerosol and splatter mitigation

Abstract Objectives: This study investigated the influence of tooth position within the quadrant and method of tooth preparation on aerosol and splatter reduction by suction techniques. Materials and methods: Using four suction techniques, tooth preparation was done using fast handpiece and combined air and water spray on tooth #28, #29 and #30. Splatter, aerosol and total sound generated were recorded. Two-way analysis of variance and posthoc pairwise comparisons compared amount of aerosol, spatter and total sound among suction techniques, tooth location and method of preparation. Results: There were statistically significant more splatter (P &lt; 0.000) for tooth preparation with air and water spray compared with high-speed handpiece for all suction techniques, but no significant difference in aerosol and total sound (P &gt; 0.05) was recorded. A significant reduction in environmental splatter during tooth preparation of the distal tooth #30 by all suction methods was observed compared with tooth #28. However, there was no significant difference in the amount of face shield, chest, right arm and left arm splatter, aerosol and total sound based on tooth location. Overall, the prototype suction device had statistically significant less environmental splatter (P &lt; 0.001) and aerosol (P = 0.004) than the conventional HVE device. Conclusions: The method of tooth preparation affected splatter mitigation by suction techniques but had no influence on aerosol mitigation. Mitigation of environmental splatter by suction techniques was affected by tooth position within the arch. The prototype suction device reduced environmental spatter and aerosol more than the conventional HVE device. Clinical Significance: The variations observed in aerosol and splatter mitigation based on tooth preparation methods and tooth location provides evidence for adjunctive means of reducing risk of direct transmission of infection in the dental practice such as combining strategies of protective equipment, improved room ventilation and use of air filtration system.

Clinical case. Bilateral subtotal mandibulectomy with fusion of the tympanic part of the temporal bone with the medial surface of the angle of the mandible in a puppy

Relevance. A rare, predominantly congenital pathology Fusion of the tympanic part of the temporal bone with the medial surface of the angle of the mandible leads to irreversible pathological processes in the maxillofacial region, which significantly reduces the quality of life of the animal. The article discusses surgical correction options that can improve the dog’s quality of life. A timely procedure increased the comfort of existence and improved the general health of the animal, eliminating discomfort, otitis media and pain.Methods. The method of choice was technically complex bilateral subtotal mandibulectomy. To perform the procedure, the following were used: surgical dental instruments; dental unit with high-speed and low-speed handpieces; various types of bur. For extra- and intraoral radiography, the following were used: CR7Vet X-ray digitizer with luminoform plates (0, 1, 2, 3, 4, 5); combined general anesthesia with the use of narcotic and potent drugs.Results. The solution of this problem is possible only operationally, therefore, the method of choice was bilateral subtotal mandibulectomy, the evaluation of which served as the purpose of the study. As a result of the procedure, already on the 14th day, the dog had activity, satisfactory well-being, and no problems with taking food and water. The study of the results of the study showed that the pathology requires immediate intervention, since the outcome of the fusion of the tympanic part of the temporal bone with the medial surface of the angle of the lower jaw in a few weeks can lead to inoperable.

Comparison of Heat Transfer Through Various Fixed Prosthetic Materials During Grinding.

To measure and compare the mean temperature values due to heat generated during the grinding of different prosthetic materials with diamond burs using a high-speed instrument with and without water cooling. In total, 120 disk-shaped specimens (10 × 2 mm), each with a smaller disk in the center (3 × 2 mm), were fabricated from yttrium-stabilized zirconia, monolithic zirconia, glass-ceramic, indirect composite, polyetheretherketone (PEEK), and cast metal (Ni-Cr alloy). The specimens were divided into six groups (n = 20) according to material type. The specimens in each group were ground continuously with a high-speed handpiece and diamond burs with (n = 10) and without (n = 10) water cooling until the smaller disks were removed. Two different methods (thermocouple and thermal camera) were used to measure the temperature during the grinding process. Results were analyzed using two-way ANOVA and paired-samples t test (P < .05). PEEK had the lowest mean temperature and metal had the highest values, both with and without water cooling, according to data measured with a thermocouple. Zirconia and monolithic zirconia samples without water cooling had the highest mean temperature when measured with a thermal camera. Both with and without water cooling, composite samples had the lowest mean temperatures for thermal camera measurements. Water cooling is strongly recommended when grinding all prosthetic materials. The heat transferred to the supporting teeth may depend on the thermal conductivity of the material used.

Effect of open windows on airborne contamination and its topographical distribution in the dental operatory.

Aerosols produced by dental handpieces represent a permanent risk of disease transmission in the dental environment. The current study evaluated the effects of natural ventilation (open windows) on Streptococcus mutans airborne contamination by dental handpieces in simulated clinical conditions. A dental phantom was placed on a dental chair at a standard university dental clinic operatory. An S. mutans suspension was infused into the phantom's mouth while an operator performed standardized dental procedures using low (contra-angle) and high speed (turbine) dental handpieces or an ultrasonic scaler, with windows open or closed. Selective medium Petri dishes were placed in 18 sites of the operatory environment to evaluate contamination topographically. Sites were clustered as: wall, floor, ceiling, dental chair, and cabinet. Contamination was expressed as log10 CFU/cm2 . A linear mixed model analysis was used, nesting the sites within each ventilation and handpiece combination. Open windows significantly reduced contamination. The high-speed handpiece provided the highest contamination, followed by the ultrasonic scaler and the low-speed handpiece. Contamination values were much smaller at the ceiling, and much larger at the chair. Opening windows produced more homogeneous contamination of the operatory compared to closed windows. Natural ventilation during dental procedures decreases contamination and affects its topographical distribution.

Measurement of proximal contact of single crowns to assess interproximal relief: A pilot study

BackgroundIt is common for dental technicians to adjust the proximal surface of adjacent teeth on casts when fabricating single crowns. However, whether the accuracy of the proximal contact is affected if this step is eliminated is unclear. ObjectiveTo evaluate the accuracy of the proximal contact of single crowns for mandibular first molars fabricated from four different restorative materials, without adjustment of the proximal surface of the adjacent teeth by the laboratory/dental technician. MethodsThis study was in vitro; all the clinical procedures were conducted on a dentoform. The mandibular first molar tooth on the dentoform was prepared using diamond burs and a high speed handpiece. Twenty single crowns were fabricated, five for each group (monolithic zirconia, lithium disilicate, metal ceramic, and cast gold). No proximal surface adjacent to the definitive crowns was adjusted for tight contact in the dental laboratory. Both the qualitative analyses, using dental floss and shimstock, and the quantitative analyses, using a stereo microscope, were performed to evaluate the accuracy of the proximal contact of the restoration with the adjacent teeth. In the quantitative analysis, one-way analysis of variance was used to compare mean values at a significance level of 0.05. ResultsIn quantitative analysis, the differences between the proximal contact tightness of the four groups was not statistically significant (P = 0.802 for mesial contacts, P = 0.354 for distal contacts). In qualitative analysis, in most crowns, dental floss passed through the contact with tight resistance and only one film of shimstock could be inserted between the adjacent teeth and the restoration. However, one specimen from the cast gold crown had open contact. ConclusionsEven without proximal surface adjustment of the adjacent teeth during the crown fabrication process, adequate proximal contact tightness between the restoration and adjacent teeth could be achieved.

Occupational exposure to electromagnetic fields from dental devices: A descriptive study

Abstract&#x0D; &#x0D; Objective: Electromagnetic Field sources which are widely used as part of the operating mechanism occupational exposure occurs with the electricity is generated, distributed or usage in the everyday environment. We aimed to obtain the Extremely Low Frequency-Magnetic Field exposure profile for dental health workers from electrical devices used in dentistry. &#x0D; Methods: Measurements were performed while appliances under working conditions, 10 cm distance with the device for 6 minutes and for 7 days. The highest measured value in every 10 second was recorded. The mean ± SD of minimum and maximum Extremely Low Frequency-Magnetic Field for high-speed dental handpiece with LED, low-speed dental handpiece, model-trimming machine, automatic boil-out unit, steam machine, vacuum device, and polishing machine were recorded in milliGauss. &#x0D; Results: The values which obtains from model-trimming machine and polishing machine were remarkable (809.17 ± 37.70 / 975.00 ± 10.27, 649.33 ± 201.37 / 1367.00 ± 32.17, respectively). Conclusion: The results show that periodic Electromagnetic Field exposure measurements should be conducted to obtain more detailed information about workplace exposures and sources.&#x0D; &#x0D; Keywords: Health, electromagnetic field, extremely low-frequency field, exposure, occupational

Direct or indirect composite for restoring permanent first molars affected by Molar Incisor Hypomineralisation (MIH): a randomized clinical controlled trial

AimThis study was undertaken to compare direct composite resin restorations (DCRR) and indirect composite resin restorations (ICRR) for treating permanent first molars affected by MIH in terms of clinical performance.Materials and methodsThis was a controlled, randomized, clinical split-mouth study. The studied sample consisted of 40 asymptomatic first permanent hypomineralised mandibular molars in 20 children aged between 7–11 years, these cases were divided randomly into two groups: Group 1 (experimental): 20 first permanent mandibular molars were restored with ICRR, and Group 2 (control): 20 first permanent mandibular molars that were restored with DCRR. The cavity was prepared using a diamond bur on a high-speed handpiece, and the prepared cavity was wiped with cotton moistened with sodium hypochlorite. The composite was applied directly with a total-etch bonding system. In the ICRR group, an impression for the prepared cavity was taken using a silicon-based material, and the restoration was adhesive with self-adhesive resin cement. The child’s satisfaction with each of the two application techniques was assessed through the scale FACES. Restorations were evaluated during follow-up periods (3, 6, and 12 months) according to Modified USHPH criteria.ResultsThe clinical success rate was 90% in the ICRR group versus 85% in the DCRR group after 12 months of follow-up without statistically significant differences (P = 0.218). Children were significantly more satisfied (P = 0.0351) with ICRR than DCRR.ConclusionsBoth DCRR and ICRR can be considered effective restorations with acceptable clinical performance in the restoration of hypomineralised first permanent molars with an advantage of ICRR in terms of child acceptance of the restoration application technique.

Reduction of aerosol dissemination in a dental area generated by high-speed and scaler ultrasonic devices employing the "Prime Protector".

The use of an external dome aerosol containment device (Prime Protector) is proposed to reduce the spread of particles within the dental office. Hence, the aim of our study was to compare the spread of bioaerosols generated by a High-speed Handpiece (HH) and an Ultrasonic Prophylaxis Device (UPD), with and without the Prime Protector dome (PP) by counting Colony Forming Units (CFU) of Lactobacillus casei Shirota, at different distances on the x and y axis. The PP was located considering the parallelism between the base of the dome and the frontal plane of the simulator, aligning the center of the mouth with the center of the dome. The PP dome measurements are 560.0mm x 255.0mm x 5mm. Petri dishes were placed at 0.5 m, 1 m and 1.5 m respectively. Aerosol generation in the laboratory environment was done three times with the following experimental groups 1) HH, 2) HH-PP, 3) UPD, 4) UPD-PP. Each dental device activation (HH and UPD) had a time frame of 2 minutes on the upper anterior teeth of the dental phantom with a liquid suspension containing Lactobacillus casei Shirota (YAKULT 0836A 0123; 1027F 0407). Air pressure and ventilation were parameterized. No separate high-volume evacuation used, nor was there any air removal attached to the dome. Results showed no significant difference between distance and axis in the CFU count. When means for devices and distances were compared between each of them all showed significant differences except for UPD and UPD-PP (p <0,004). In conclusion, external devices like Prime Protector could help decrease aerosol diffusion during high-speed handpiece activation. However, this dome does not replace the use of PPE inside dental clinics.

Surface Roughness of Enamel and Dentin after Preparation Finishing with Rotary Burs or Piezoelectric Instruments

This study compares the effect of different handpieces (turbine, high-speed electric handpiece and piezoelectric device) on surface roughness of enamel and dentin when using diamond-coated working tips and burs of the same grit size. The experiment was conducted on 15 extracted first molars from patients aged 45 to 60 years. The occlusal portion was removed using a diamond-coated water wheel and then refined with a 120–130 μm grit bur in order to obtain a flat surface with an adequate exposition of the dentin core. Each surface was divided into three portions and every portion was finished with one of the three tested instruments. The rotary burs and piezoelectric tips had the same grit size (60 μm), and the load on handpiece during preparation never exceeded 150 g. Roughness parameters (Ra, Rsk, Rku) were recorded with a profilometer, and a SEM analysis of treated surfaces and working tips was conducted. Ra and Rsk differed significantly between enamel and dentin only after using turbine (p = 0.004 and p = 0.007, respectively). No significant differences were observed in Ra, Rsk and Rku between enamel and dentin when using a high-speed electric handpiece or piezoelectric device. The turbine produced higher Ra and Rsk values on dentin than the other devices, while no significant differences were found between piezoelectric handpiece and high-speed electric contra-angle on both substrates. Summarizing, the findings of the present study demonstrated that turbine generated rougher surfaces on dentin compared to the other handpieces. Moreover, the turbine produced more asymmetrical surface profiles on both enamel and dentin. However, it should be considered that these differences in roughness (Ra) were within the range of 0.25–0.30 μm: it is still unclear if these variations, although statistically significant, will influence final clinical outcomes.