Dental Hypotheses
Volume:13 Issue: 2, Apr-Jun 2022

Frictional forces generation during orthodontic treatment with fixed appliances impedes appropriate tooth movement; hence, research is ongoing to explore “frictionless” techniques. This in vitro study compares Damon Q and Pactive self-ligating metallic brackets in terms of friction and surface characteristics of the bracket gates when using CuNiTi archwires during leveling and alignment stage and examines the effects of aging conditions on frictional force generation.

A total of 108 metallic self-ligating brackets (Damon Q and Pactive) were investigated for frictional resistance with round 0.014 ̋ and rectangular 0.014 ̋
0.025 ̋ CuNiTi archwires post exposure to water storage and acidic attack aging conditions. The bracket gate surface characteristics were evaluated using scanning electron microscope (SEM).

There was no statistically significant difference (P > 0.05) in friction generation between the two bracket systems when coupled with 0.014 ̋ CuNiTi archwire, but the Pactive brackets yielded significantly higher frictional forces (P < 0.05) when coupled with 0.014 ̋
0.025 ̋ archwire. The SEM findings revealed nonsignificant differences (P > 0.05) between the surface characteristics of the bracket gates.

Damon Q brackets generate low frictional forces, suggesting better performance than Pactive brackets during the first phase of orthodontic treatment. A modified scoring system was developed for an objective description of bracket surface characteristics.

Total antioxidant capacity (TAC) is an important marker to be measured to explore the effect of oil fume on oral tissue. This study examined the effect of longtime exposure to oil fume on oral and periodontal tissue.

A total of 52 participants consisted of four groups of 13 participants each. Oral examination and periodontal indices were taken. TAC was analyzed.

The study groups showed highly significant differences in plaque, gingival index, and clinical attachment level (P < 0.001) compared to the control. The older workers have shown the highest total antioxidant capacity levels. The oil group has expressed a significant lowest total antioxidant capacity level (P > 0.05) in comparison to the control. Oral lesions including ulcerations and white and red patches were absent in workers.

Total antioxidant capacity is an important biomarker in the diagnosis of oral and periodontal diseases.

This study aimed to assess and compare the depth of penetration of TotalFill BC, AH Plus Jet, and GuttaFlow Bioseal sealers into simulated lateral canals.

A total of 30 extracted mandibular premolars were selected. Simulated lateral canals were made. The specimens were randomized into three experimental groups of 10 each. The specimens were cleared for visualization under a stereomicroscope at 10× magnification. The depth of penetration was assessed by a four-grade scoring system. Data were submitted to Fisher exact test at 5% significance.

There was statistically no significant difference among the experimental groups regarding the depth of penetration (P > .05).

All root canal sealers experimented with herein showed a comparable depth of penetration in the simulated lateral canals regarding their filling ability.

This study aimed to compare the fracture resistance using a bioceramic sealer and an epoxy resin-based sealer.

One hundred maxillary central incisors were randomly assigned to three experimental groups: AH Plus sealer using the single-cone technique, AH Plus sealer using the lateral compaction technique, SureSeal Root sealer, and two positive and negative control groups. Then the fracture resistance of the prepared tooth roots was determined. The data were analyzed with one-way ANOVA and Tukey Post Hoc tests.

There were statistically significant differences between the five study groups (P < 0.001). There was no significant difference between the negative control and Sureseal groups (P = 0.183). There were significant differences between the SureSeal and AH Plus groups (P < 0.05).

SureSeal Root sealer significantly increased the fracture resistance of the teeth compared to AH Plus sealer.

Although of great scientific advancement in the properties and form, fracture of nickel-titanium (NiTi) files could occur during their use. The goal of this study was to compare resistance to cyclic fatigue of various rotary systems used in endodontics.

Three types of NiTi rotary systems were tested – group A: One Curve, group B: Edge File, and group C: lusterdent NiTi files. In these files, taper is 0.06, and their diameter is 25 mm. Stainless steel block was used. This block contains artificial canals with a 60 o curvature, 5 mm radius of curvature, 21 mm length, and 1.5 mm width. A number of cycles before fracture were obtained and measurement of fragment length was achieved. Statistical evaluation of readings was accomplished with ANOVA and Tukey post hoc test.

There were statistically significant differences between the three types of NiTi rotary systems considering the number of cycles before file fracture (P < 0.001). The differences between fracture lengths were not statistically significant (P = 0.15).

The Edge File revealed the highest cyclic fatigue resistance.

Dentinal defects during root canal preparation could lead to treatment failure and tooth extraction. Many rotary files are manufactured with asymmetric cross sections or alternating cutting edges to minimize contact with the canal wall. Decreasing contacts may generate low stresses and, hence, fewer dental defects during root canal instrumentation. This study aimed to evaluate the incidence of dentinal defects induced by ProTaper Next, Wave One Gold (Dentsply Maillefer, Ballaigues, Switzerland), and iRace (FKG Dentaire SA, La Chaux- de-Fonds, Switzerland) in comparison to the symmetric file HyFlex CM (Coltene-Whaledent, Allstetten, Switzerland).

Sixty extracted single-rooted premolars with round canals were selected for this study. All teeth were decoronated and divided into four experimental groups according to the tested file systems. In each group, 15 canals were prepared with the crown down technique using a speed and torque recommended by manufacturers. The root samples were then sectioned horizontally at 3, 6, and 9 mm from the apex and examined under a stereomicroscope to evaluate the presence or absence of dentinal defects. Data were statistically analyzed with SPSS software using a chi-square test.

Dentinal defects were observed at all canal levels following all methods of instrumentation. ProTaper Next showed the lowest values of dentinal defects, whereas Hyflex CM displayed the highest values.

Files with few contacts with the canal wall decreased the number of dentinal defects compared to the HyFlex CM file, with a nonsignificant difference being observed.

In the field of pediatric dentistry, an urge to adopt a more comfortable, minimally invasive, and stressless technique for caries removal became a must. Coronavirus disease-2019 outbreak necessitates a paradigm change in the global health care protocols, requiring alternative, nonaerosol generating approaches. This study aimed to measure and compare the influence of two methods of caries removal, namely, Brix3000 and CeraBur, on the microleakage of glass hybrid restorative material.

Thirty human primary molar teeth with accessible occluso-gingival carious cavitation were randomly allocated into CeraBur and Brix3000 groups. After selective caries excavation, samples were restored with Equia Forte HT, thermocycled, dipped in thiazine dye, washed, and sectioned through the restoration center. Then microleakage was measured using a stereomicroscope (30× magnification) at both occlusal and gingival margins.

No statistically significant difference was found between the two methods of caries removal (CeraBur and Brix3000) at both occlusal (P = 1.000) and gingival margins (P = 0.612).

Brix3000 caries removing gel did not negatively affect the microleakage of Equia Forte HT compared to the CeraBur and hence can be used alternatively to the conventional drilling methods.

 Preliminary evidence have shown that low intensity laser therapy is able to increase the rate of tooth movement. The aim of this study was to analyze the effects of gallium aluminum arsenide (GaAlAs) laser therapy in the enhancement of speed of orthodontic tooth movement (OTM) in a clinical protocol.

Thirty-six upper canines were analyzed on 18 enrolled patients. On all experimental canine, an orthodontic force of 40 g/side was applied by a nickel-titanium closed coil spring. Using a split mouth randomized design, the test side was treated using a diode laser operating at a wavelength of 780 nm in continuous wave mode with flattop handpiece (20 mW output power, dose of 5 J/cm 2 , and exposure time of 10 seconds) (test side) at baseline and at 7, 14, and 28 days and every 14 days until the space closure. On the control side, selected teeth were only tractionated. The primary outcome was the overall time needed to complete leveling and closing space, measured on study cast. The secondary outcome was the evaluation of pain levels related to tooth traction, evaluated using a visual analogue scale (VAS).

The test side showed a significant reduced overall time needed for tooth space closure (at 7 and 14 days) and less VAS score (P<0.001) compared to control side.

This study shows that the use of low-level laser therapy by means of GaAlAs laser was effective for accelerating tooth movement and reducing pain levels related to OTM.

In vitro studies supporting the hydrodynamic theory have reported that cavity provocation results in fluid flow from dentin tubules via pulp tissue to a capillary connected apically. Our preliminary findings did not corroborate this. Therefore, the aim was to perform experiments closely following the descriptions in the mentioned articles to find out if there is a direct fluid flow communication from a prepared cavity to pulp tissue detectable with this method.

Class V cavities were prepared and provocations (air blast, scraping, temperature change) initiated within 1 hour of extraction in 17 teeth and after 1 week in 3 teeth. Fluid flow was monitored during and after stimulation using a microscope.

No fluid flow was registered during stimulations performed within an hour of extraction. One week after extraction fluid movement was registered during the air blast.

The finding of no direct continuum in freshly extracted teeth from cavity surface via dentin fluid to pulp tissue to an apically placed capillary does not per se disprove the hydrodynamic theory. As the in vitro experiment by Brännström et al. has been a major foundation for the hydrodynamic theory, it may be time to investigate the true mechanism(s) of dentin sensitivity.

The structural characteristics of unilaterally impacted maxillary canines and adjacent teeth were compared to the nonimpacted side. Three-dimensional (3D) cone-beam computed tomography (CBCT) was used to analyze and evaluate the various parameters. The aim of this study was a quantitative comparison of teeth adjacent to buccally and palatally impacted maxillary canines.

CBCT records of 40 patients with unilateral impacted maxillary canine were allocated to this study. The morphological characteristics of teeth on the impaction and non-impaction sides of the same patient were examined. 3D reconstructed CBCT images were assessed using the OnDemand 3D program.

The dependent samples t test was used for data analysis with a level of statistical significance of 0.05. There was a significant increase in the size of the maxillary canine crown and a decrease in the maxillary lateral incisor root dimensions on the impacted side. No significant difference was observed in the morphology of the maxillary first premolar on either side.

The impacted canine showed greater size compared to the eruption side. The decrease in root dimensions of the lateral incisor on the impacted side may indicate the possibility of root resorption.