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Comparative Evaluation of Stress Distribution Patterns and Location of Centre of Resistance During Temporary Anchorage Device Assisted Molar Intrusion With and Without Micro Osteoperforation: A Three-Dimensional Finite Element Analysis
No full textINTRODUCTION:
MicroOsteoPerforation (MOP) is a minimally invasive method to elicit an inflammatory response to accelerate tooth movement without compromising the supporting alveolar bone. Molar intrusion is a difficult tooth movement. Hence, micro osteoperforation can be used to facilitate molar intrusion to reduce the treatment duration by reducing the resistance to tooth movement.
AIM OF THE STUDY:
Our study compared the stress distribution patterns, the position of the center of resistance, and the amount of molar intrusion in temporary anchorage device assisted molar intrusion with microosteoperforation and temporary anchorage device (TAD) assisted molar intrusion without microosteoperforation using a finite element model (FEM).
MATERIALS AND METHOD:
A finite element model of maxilla with teeth, fixed orthodontic appliance was constructed with stainless steel metal brackets and molar bands. Full strap up with MBT prescription 0.022 slot was designed in the model. The simulation was to replicate and compare the clinical situation of a NiTi closed coil spring exerting a force of 1.96 Newtons directed apically on the first molar under the influence of 6 microosteoperforations, using mini-implants as anchorage units with NiTi closed coil spring exerting a force of 1.96 Newtons directed apically on the first molar without the influence of 6 microosteoperforations, using mini-implants as anchorage units.
CONCLUSION:
The study revealed that microosteoperforation reduced the stress experienced and, reduced the resistance to tooth movement. The center of resistance also shifted to a more favorable position. The displacement achieved was greater when microosteoperforation was done
Comparative Evaluation of Mechanical Properties of Cobalt-Chromium, Stainless Steel and β-Titanium Wires: An In Vitro study
No full textAIMOF THE STUDY:
To evaluate and compare the mechanical properties of heat treated cobalt-chromium wires with as received stainless steel (SS) and titanium Molybdenum alloy (TMA) wires manufactured by three different companies.
METHODS:
Nine samples of 0.016″ × 0.022″ inch dimension archwire of SS, TMA and BE from three different companies were chosen. Elgiloy wires were subjected to heat treatment in Furnace at 500oC for 10 minutes. The wire samples were tested in universal testing machine. Each group's specimens were tested at 25°C in 0.5 mm and 1 mm loading, as well as unloading 0.5 mm (from the 1 mm loading) and returning to their original position (zero position). To evaluate mechanical performance in unloading and possible wire deformation, each test was conducted three times with the same wire (A, B, C).
RESULTS:
The results showed that Blue Elgiloy after heat treatment produced highest force levels on loading and unloading compared to stainless steel and TMA which showed that the mechanical properties of Blue Elgiloy were improved after heat treatment. On comparing the companies of blue Elgiloy wires, all the companies produced similar forces on initial loading and unloading whereas Rocky mountain orthodontics wires produced highest forces after testing for third time indicating higher formability of wires whereas G&H orthodontics wires showed lesser forces after third loading indicating higher shape memory of wires. On comparing the companies of Stainless steel wires, Rocky mountain orthodontics wires showed higher forces on loading and unloading which showed highest stiffness compared to other wires. On comparing the companies of TMA wires, Rocky mountain orthodontics wires showed higher forces on loading and unloading which showed highest stiffness compared to other wires. Wires from Dentaurum and G&H Orthodontics are more resilient than those from Rocky Mountain Orthodontics.
CONCLUSION:
Heat-treated BE, as received SS and TMA wires of RMO had higher forces and rigidity when compared to other company wires. After heat treatment, Blue Elgiloy wires produced similar force levels to SS wires and increased resistance to deformation during loading and unloading, which could have important clinical implications in the finishing stage of treatment
Comparative Evaluation of Marginal Adaptation of Two Epoxy Resin-Based Root Canal Sealers in Apical Third of Root canal: A Randomized In Vitro study
No full textThe root canal filling materials should be closely adapt to the walls of root canal, be radiopaque and dimensionally stable. To obtain these functional characteristics the filling materials should adhere to the dentinal walls and provide a hermetic seal.
Epoxy is a polymer that initializes the process of polymerization, due to its resin nature, flow and long setting time, epoxy resin sealer penetrates deeper into the surface microirregularities, as well inside the lateral root canals. These properties lead to greater intertwining of the sealer with dentin structure, which, together with the cohesion among the cement molecules, provides greater adhesiveness and resistance to dislodgment from dentin.
In our study, marginal adaptation of two epoxy resin-based sealers; Acroseal and Simpliseal sealer was compared, it was found that Acroseal showed better marginal adaptation compared to Simpliseal sealer. However further in-vivo studies required to substantiate our study results.
CONCLUSION:
Within the limitations of the study methodology and performed procedures, marginal adaptation of Acroseal and Simpliseal are compared using scanning electron microscope. Among the Acroseal was found to have superior marginal adaptation compared to simpliseal sealer
Evaluation of the Effect of Cyclic Preloading on Cyclic Fatigue Resistance in Rotary File System
No full textAIM OF THE STUDY:
The aim of this study is to evaluate and compare the effect of cyclic preloading on cyclic fatigue resistance in two rotary file systems.
METHODOLOGY:
Rotary files – One Shape and KOMET F360 were used for instrumentation in simulated root canals. Artificial canals were simulated measuring 1.5mm in width, 20mm in length, and 2. 5mm in depth with U-shaped cross-section, were machined into 316L stainless steel blocks by computer-assisted milling and hardened with polished chrome plating. A straight cervical segment measuring 10.58mm with an arc length of 9. 52mm and a curvature radius of 6mm, and
the arc located in the apical portion of the canal.
All the instruments were operated with a torque-controlled electric motor. The time to fracture was recorded using a digital clock. The length of the time between the beginning of the procedure until instrument fracture occurred (Ncf) was recorded. The mean value of number cycles to fracture (Ncf) was calculated for each group of files. Then each file system was subjected to preloading of 25 % of mean Ncf and then subjected to cyclic fatigue test. The experimental procedure was performed by a single operator to avoid inter-operator variability.
CONCLUSION:
It was concluded that cyclic preloading decreases the cyclic fatigue resistance of One Shape and KOMET F360 rotary file systems. Comparatively, KOMET F360 had higher cyclic fatigue resistance than the One Shape rotary file system
Comparison of the Effect of Two Collagen Cross Linking Agents on Sodium Hypochlorite Treated Dentin and Tubular Penetration Capacity of Sealers: An Invitro study
No full textAIM OF THE STUDY:
The objective of the study is to compare the effects of two collagen cross-linking agents on sodium hypochlorite treated dentin by determining the push-out bond strength and also comparing the tubular penetration capacity of resin-based and bioceramic sealers.
METHODOLOGY:
Fifty human permanent mandibular premolars with single root and single canal and with curvature up to 10° were chosen for the study and decoronated at CEJ. Root canals were enlarged up to 20 sizes 6% taper (F1). All the groups were irrigated with NaOCl, 17% EDTA followed by CHX solution. All the teeth were randomly divided into 5 groups [n=10] group I: Irrigation with saline(Control), group II: Irrigation with cashew nut shell liquid, followed by obturation with bioceramic sealer obturation, [n=10], group III: Irrigation with cashew nut shell liquid followed by obturation with resin-based sealer obturation, [n=10], group IV: Irrigation with epigallocatechin-3-gallate followed by obturation with bioceramic sealer obturation, [n=10] and group V: Irrigation with epigallocatechin-3-gallate followed by obturation with resin-based sealer obturation, [n=10]. All the groups were rinsed with 10mL of water and the canals were dried with paper points. After that canals were obturated with gutta-percha points with respective sealers. For the evaluation of push-out bond strength, specimens were sectioned into coronal, middle, and apical third by diamond disc and tested under tension until fracture in the universal testing machine. For the determination of sealer penetration, specimens were sectioned in the buccolingual direction, in such a way that one portion retains the obturating material and the portion retained the obturating material were evaluated under a scanning electron microscope for analyzing the depth of penetration.
RESULTS:
Higher push-out bond strength was observed in maximum in group 2 (Cashew nut shell liquid + gutta-percha with bioceramic sealer obturation). Tubular penetration capacity of sealers was maximum in group 5 (EGCG + gutta-percha with Hybrid sealer obturation) when compared with the other groups.
CONCLUSION:
Both the collagen cross-linking agents tested in this study exhibited significant effects on the sodium hypochlorite treated dentin. Cashew nut shell liquid showed better results in the determination of the reversing effect after using sodium hypochlorite. Hybrid sealer showed maximum penetration capacity when compared with Bio-C-Sealer