Dr. MH. Nekoofar

DDS, MSc, DoIBoE, PhD

Author: admin

  • Water Content of Ampoule Packaged with ProRoot MTA

  • pH of Pus Collected from Periapical Abscesses

    Aim: To determine the pH of pus collected from periapical abscesses. Methodology Forty patients (Male = 17/Female = 23) between the ages 17 and 37 years, each with a periapical abscess and with no relevant medical history, were recruited. All the participants had moderate- to-severe pain on percussion accompanied by localized or generalized swelling. At least 1 mL of pus was aspirated from each participant using a No 20 gauge needle. A pH meter was used to define the pH of the pus immediately following aspiration.
    Result: The mean pH of pus from the periapical abscesses of patients was 6.68 ± 0.324 with a range between 6.0 and 7.3. There was no statistically significant difference in pH by gender or age.
    Conclusion: The mean pH of pus from periapical abscesses was generally acidic, but some samples (two female and three male) were neutral and some samples (four female and one male) were alkaline.

     pH of pus collected from periapical abscesses.pdf

  • Comparative Evaluation of the Microhardness of White and Gray MTA after Contamination with Blood

  • Microleakage of Human Saliva in Coronally Unsealed Obturated Root Canals in Anaerobic Conditions

  • Letter to the Editor: Water Content of Ampoule Package with Proroot MTA

     Letter to the editor Water content.pdf

  • Accuracy of Two Root Canal Length Measurement Devices Integrated into Rotary Endodontic Motors When Removing Gutta‐Percha from Root‐Filled Teeth

    Aim To evaluate ex vivo the accuracy of the integrated electronic root canal length measurement devices within TCM Endo V and Tri Auto ZX motors whilst removing gutta-percha and sealer from filled root canals. Methodology Forty freshly extracted maxillary and mandibular incisor teeth with mature apices were selected. Following access cavity preparation, the length of the root canals were measured visually 0.5 mm short of the major foramen (TL). The canals were prepared using the HERO 642 system and then filled with gutta-percha and AH26 sealer using a lateral compaction technique. After 7 days the coronal temporary filling was removed and the roots mounted in an alginate experimental model. The roots were then randomly divided in two groups. The access cavities were filled with chloroform to soften the gutta-percha and allow its penetration using the Tri Auto ZX and the TCM Endo V devices in groups 1 and 2, respectively. The ‘automatic apical reverse function’ (ARL) of both devices was set to start at the 0.5 setting and the rotary instrument inserted inside the root canal until a beeping sound was heard and the rotation of the file stopped automatically. Once the auto reverse function had been initiated, the foot pedal of the motor was inactivated and the rubber stop placed against the reference point. The distance between the file tip and rubber stop was measured using a digital calliper to 0.01 mm accuracy (ARL). Then, a size 20, 0.02 taper instrument was attached to each device and inserted into the root canals without rotary motion until the integrated ERCLMDs positioned the instrument tips at the 0.5 setting as suggested by the devices. This length was again measured using a digital calliper (EL). The Mann–Whitney U-test was used to investigate statistical differences between the true canal length and those indicated by the two devices when used in ‘automatic ARL and when inserted passively (EL).
    Results: In the presence of gutta-percha, sealer and chloroform, the auto-reverse function for the Tri Auto ZX and TCM Endo V, set to start at 0.5 level, was initiated beyond the foramen in 60% and 95% of the samples, respectively during active (rotary) penetration of the instruments. There was a statistically significant difference between the devices for the mean discrepancies between the length at which the auto reverse function was initiated and the true length (P < 0.001). Electronic detection of the apical terminus when the instruments were introduced passively (not rotating) was beyond the foramen in 20% and 37% of cases in the Tri Auto ZX group and the TCM Endo V group, respectively. There was a statistically significant difference between the devices for the mean discrepancies between the electronically determined (passive) length and true length (P < 0.01).
    Conclusion: The auto reverse function of the Tri Auto ZX and TCM Endo V devices, set to start at 0.5 level, were initiated beyond the foramen in the majority of root-filled teeth during active (rotating) penetration  of root filling material. Thus, this automatic function must be used with caution when removing guttapercha root fillings. There were significant differences between the accuracy of measurements in active (rotating) and passive (not-rotating) modes; both devices were more accurate when used in passive mode. However, the Tri AutoZX was significantly more accurate in a greater proportion of cases.

     Accuracy of two root canal length measurement.pdf

  • The Effect of pH on Surface Hardness and Microstructure of Mineral Trioxide Aggregate

    Aim: To evaluate the surface microhardness of mineral trioxide aggregate (MTA) specimens following exposure of their surface to a range of acidic environments during hydration. In addition, the morphological microstructure features of samples were studied by scanning electron microscopy (SEM). Methodology White ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN, USA) was mixed and packed into cylindrical polycarbonate tubes. Four groups, each of 10 specimens, were formed using a pressure of 3.22 MPa and exposed to pH 4.4, 5.4, 6.4 and 7.4, respectively, for 4 days. Vickers microhardness of the surface of each specimen was measured after exposure. Four groups of two specimens were prepared and treated in the same way prior to qualitative examination by SEM. Data were subjected to one-way anova and post hoc Tukey’s test.

    Result: The greatest mean surface hardness values (53.19 ± 4.124) were observed following exposure to pH 7.4 with the values decreasing to 14.34 ± 6.477 following exposure to pH 4.4. The difference between these values at the 95% CI (33.39–44.30) was statistically significant (P < 0.0001). There were no distinct morphological differences between groups in terms of the internal microstructure. However, a trend was observed that the more acidic the solution, the more extensive the porosity of the specimens.
    Conclusion: Under the conditions of this study, surface hardness of MTA was impaired in an acidic environment.

     The effect of pH on surface hardness and.pdf

  • The Effect of Condensation Pressure on Selected Physical Properties of Mineral Trioxide Aggregate

    Aim: To examine the effect of condensation pressure on surface hardness, microstructure and compressive strength of mineral trioxide aggregate (MTA). Methodology White ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN, USA) was mixed and packed into cylindrical polycarbonate tubes. Six groups each of 10 specimens were subjected to pressures of 0.06, 0.44, 1.68, 3.22, 4.46 and 8.88 MPa respectively. The surface hardness of each specimen was measured using Vickers microhardness. Cylindrical specimens of 4 mm in diameter and 6 mmin height were prepared in polycarbonate cylindrical moulds for testing the compressive strength. Five groups of 10 specimens were prepared using pressures of 0.06, 0.44, 1.68, 3.22 or 4.46 MPa. Data were subjected to one-way anova. The microstructure was analysed using a scanning electron microscope (SEM) after sectioning specimens with a scalpel.

     The effect of condensation pressure on selected.pdf

  • Failure Mechanisms of NiTi Rotary Instruments During Clinical Use: A Microscopic Study

  • The Fundamental Operating Principles of Electronic Root Canal Length Measurement Devices

    It is generally accepted that root canal treatment procedures should be confined within the root canal system. To achieve this objective the canal terminus must be detected accurately during canal preparation and precise control of working length during the process must be maintained. Several techniques have been used for determining the apical canal terminus including electronic methods. However, the fundamental electronic operating principles and classification of the electronic devices used in this method are often unknown and a matter of controversy. The basic assumption with all electronic length measuring devices is that human tissues have certain characteristics that can be modelled by a combination of electrical components. Therefore, by measuring the electrical properties of the model, such as resistance and impedance, it should be possible to detect the canal terminus. The root canal system is surrounded by dentine and cementum that are insulators to electrical current. At the minor apical foramen, however, there is a small hole in which conductive materials within the canal space (tissue,  fluid) are electrically connected to the periodontal ligament that is itself a conductor of electric current. Thus, dentine, along with tissue and fluid inside the canal, forms a resistor, the value of which depends on their dimensions, and their inherent resistivity. When an endodontic file penetrates inside the canal and approaches the minor apical foramen, the resistance between the endodontic file and the foramen decreases, because the effective length of the resistive material (dentine, tissue, fluid) decreases. As well as resistive properties, the structure of the tooth root has capacitive characteristics. Therefore, various electronic methods have been developed that use a variety of other principles to detect the canal terminus. Whilst the simplest devices measure resistance, other devices measure impedance using either high frequency, two frequencies, or multiple frequencies. In addition, some systems use low frequency oscillation and/or a voltage gradient method to detect the canal terminus. The aim of this review was to clarify the fundamental operating principles of the different types of electronic systems that claim to measure canal length.

     The fundamental operating principles of electronic.pdf