Ghassan M. Yared

An evaluation of 2% lidocaine with different concentrations of epinephrine for inferior alveolar nerve block

The purpose of this study was to compare the degree of anesthesia obtained with 2% lidocaine with three different concentrations of epinephrine for inferior alveolar nerve block. Using a repeated measures design, 30 subjects randomly received an inferior alveolar injection using masked cartridges of each solution at three successive appointments. The first molar, first premolar, lateral incisor, and contralateral canine (control) were blindly tested with an Analytic Technology pulp tester at 3-min cycles for 50 min. No statistically significant differences in success and failure were found among the 1:50,000, 1:80,000, and 1:100,000 concentrations of epinephrine.

Influence of apical enlargement on bacterial infection during treatment of apical periodontitis

This study sought to evaluate the influence of apical enlargement and 1-wk calcium hydroxide dressing on bacterial infection of root canals. Sixty single-rooted teeth were used. Half of these teeth were prepared to a size 25 file and the other half to a size 40 file. Then the root canals were dressed with calcium hydroxide for 1 wk. Bacterial sampling showed significant reduction of bacterial growth during the treatment. No statistically significant difference was noted between the size 25 and 40 file groups after instrumentation, and after 1-wk calcium hydroxide dressing.

In vitro study of the torsional properties of new and used ProFile nickel titanium rotary files.

The purpose of this study was to investigate torque and angle of rotation at fracture of new and used.06 ProFile instruments. ProFile sizes 15 to 40 were tested according to American National Standards Institute/American Dental Association Specification #28. Thirty new and used instruments were tested for each size. An analysis of variance was used to compare the torque and angle of rotation at fracture between new and used instruments. The relationship between torque at fracture and size of instrument was determined with a regression analysis. The used instruments had significantly lower torque and angle of rotation at fracture values compared with the new instruments (p < 0.0001). A stronger relationship was found between the size of the instrument and the torque at fracture for the new instruments (p < 0.0001) than for the used ones (p < 0.0001). In conclusion, the repeated use of.06 ProFile instruments significantly reduced the torque and angle of rotation at fracture.

Influence of torque control motors and the operator’s proficiency on ProTaper failures

OBJECTIVE The purpose of this study was to evaluate the influence of 2 electric torque control motors and operator experience with a specific nickel-titanium rotary instrumentation technique on the incidence of deformation and separation of instruments. STUDY DESIGN ProTaper (PT) nickel-titanium rotary instruments were used at 300 rpm. In the first part of the study, electric high torque control (group 1) and low torque control (group 2) motors were compared. In the second part of the study, 3 operators with varying experience (groups 3, 4, and 5) were also compared. Twenty sets of PT instruments and 100 canals of extracted human molars were used in each group. Each set of PT instruments was used in up to 5 canals and sterilized before each case. For irrigation, 2.5% NaOCl was used. The number of deformed and separated instruments among the groups (within each part of the study) was statistically analyzed for significance with pair-wise comparisons by using the Fisher exact test (alpha =.05). RESULTS In part 1, instrument deformation and separation did not occur in groups 1 and 2. In part 2, 25 and 12 instruments were deformed and separated, respectively, with the least experienced operator. Instrument deformation and separation did not occur with the most experienced operator. The Fisher exact test revealed a significant difference between groups 3 and 4 with respect to instrument deformation (P =.0296). In addition, the Fisher exact test revealed that the incidence of instrument deformation was statistically different between groups 3 and 5 (P <.0001) and groups 4 and 5 (P =.0018). The incidence of instrument separation was significantly higher in group 5 than in groups 3 and 4 (P =.001). CONCLUSIONS Preclinical training in the use of the PT technique at 300 rpm is crucial to prevent instrument separation and reduce the incidence of instrument deformation. The use of an electric high torque control motor is safe with the experienced operator.

Sealing ability of the vertical condensation with different root canal sealers

This study evaluated the influence of various root canal sealers on the quality of the apical seal of vertically condensed gutta-percha. One hundred and twenty human anterior teeth with single canals were used. After cleaning and shaping to an apical size 30 file, the teeth were divided into 4 equal groups of 30 teeth each and obturated with vertically condensed gutta-percha. In group 1, no sealer was used. In groups 2, 3, and 4, Kerr Pulp Canal Sealer, Roth 801, and AH 26 were used, respectively. Apical microleakage was determined using pressurized fluid filtration measured at different time intervals up to 24 wk. The no-sealer group showed significantly more apical leakage than the other groups. Kerr Pulp Canal Sealer was significantly better than Roth 801 and AH 26 at 24 wk.

Influence of plugger penetration on the sealing ability of vertical condensation

This study sought to evaluate the influence of plugger penetration on the sealing ability of vertical compaction. Ninety anterior teeth were used. After cleaning and shaping to a size #30 file, these teeth were divided into three equal groups (A, B, and C) according to the level of plugger penetration set at 5, 7, and 9 mm short of the working length, respectively. Then vertical compaction was performed. Apical microleakage was determined using pressurized fluid filtration at 90 min, 1 day, and 1, 4, 12, 18, and 24 wk after root canal obturation. Leakage tended to increase over time for the three groups. The deeper plugger penetration groups (A and B) showed significantly less apical leakage than group C.

Evaluation of lidocaine in human inferior alveolar nerve block

The purpose of this study was to measure the degree of anesthesia following the administration of 3.6 ml of 2% lidocaine solutions with either 1:50,000, 1:80,000, or 1:100,000 for inferior alveolar nerve block and to compare the results with those obtained following the administration of 1.8 ml of the same solutions (1). With the use of a repeated measures design, 30 subjects randomly received an inferior alveolar injection at three successive appointments. The first molar, first premolar, lateral incisor, and contralateral canine (control) were blindly tested with an Analytic Technology pulp tester at 3-min cycles for 50 min. The degree of anesthesia was comparable for the three solutions following the administration of 3.6 ml of each solution. Retrospective evaluation showed that the volume of the solution influenced the degree of anesthesia.

An in vitro study of the torsional properties of new and used rotary nickel-titanium files in plastic blocks.

OBJECTIVE The purpose of this study was to compare torque (in grams per centimeter) and angle of rotation (in degrees) at the time of fracture of new and used nickel-titanium .04 ProFile rotary files. The relationship between the size of the instrument and the torque at fracture was also investigated. STUDY DESIGN The torque and angle of rotation at fracture of new and used nickel-titanium .04 ProFile rotary files Nos. 15 to 40 were determined according to American National Standards Institute/American Dental Association Specification No. 28. Analysis of variance was used to compare the torque and angle of rotation at fracture of the different sizes of the new instruments and of new and used instruments of the same size (alpha =.05). The relationship between torque at fracture and the size of the instrument was determined by means of regression analysis. RESULTS The torque at fracture of the new instruments increased significantly with the diameter. The used instruments, Nos. 25 to 40, had significantly lower values of torque at fracture than did the new ones. There were no statistically significant differences between the angle of rotation at fracture of the new and the used instruments (P >.05). A stronger relationship was found between the size of the file and the torque at fracture for the new instruments (P <.0001) than for the used ones (P <.0001). CONCLUSION The results of the present study suggest that the values of the torque at fracture of new instruments increased significantly with the diameter. The results also suggest that repeated use of ProFile .04 instruments mainly affected the torque at fracture.

Apical enlargement: Influence on the sealing ability of the vertical compaction technique

This study sought to evaluate the influence of apical enlargement on the sealing ability of vertical compaction. Sixty anterior teeth were used. Half of these teeth were prepared to a size 25 file and the other half to a size 40 file. Then vertical compaction was performed. Apical microleakage was determined using pressurized fluid filtration at 90 min, 6 h, 1 day, 4 days, and at 1, 2, 4, 8, 12, 16, and 24 wk after root canal obturation. Leakage tended to increase over time for both groups. The size 25 file group showed significantly less apical leakage than the size 40 file group.

Comparison of three files to prepare curved root canals.

Flex-R, Ultra-Flex (Ni-Ti construction), and K-type files were compared using a circumferential filing technique on 96 extracted human maxillary molars. Buccal canals with minimal initial curvature of 24 degrees were used. The maximal initial curvature was 52 degrees. Canal curvature was measured before and after filling, and changes were analyzed statistically. The angle of curvature was better maintained with the Flex-R and Ultra-Flex files.